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Sezen Sekmen

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DOI: 10.21468/scipostphys.12.1.043
2022
Cited 50 times
The Dark Machines Anomaly Score Challenge: Benchmark Data and Model Independent Event Classification for the Large Hadron Collider
We describe the outcome of a data challenge conducted as part of the Dark Machines Initiative and the Les Houches 2019 workshop on Physics at TeV colliders. The challenged aims at detecting signals of new physics at the LHC using unsupervised machine learning algorithms. First, we propose how an anomaly score could be implemented to define model-independent signal regions in LHC searches. We define and describe a large benchmark dataset, consisting of >1 Billion simulated LHC events corresponding to $10~\rm{fb}^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV. We then review a wide range of anomaly detection and density estimation algorithms, developed in the context of the data challenge, and we measure their performance in a set of realistic analysis environments. We draw a number of useful conclusions that will aid the development of unsupervised new physics searches during the third run of the LHC, and provide our benchmark dataset for future studies at https://www.phenoMLdata.org. Code to reproduce the analysis is provided at https://github.com/bostdiek/DarkMachines-UnsupervisedChallenge.
DOI: 10.1007/jhep02(2019)186
2019
Cited 73 times
LHC-friendly minimal freeze-in models
A bstract We propose simple freeze-in models where the observed dark matter abundance is explained via the decay of an electrically charged and/or coloured parent particle into Feebly Interacting Massive Particles (FIMP). The parent particle is long-lived and yields a wide variety of LHC signatures depending on its lifetime and quantum numbers. We assess the current constraints and future high luminosity reach of these scenarios at the LHC from searches for heavy stable charged particles, disappearing tracks, displaced vertices and displaced leptons. We show that the LHC constitutes a powerful probe of freeze-in dark matter and can further provide interesting insights on the validity of vanilla baryogenesis and leptogenesis scenarios.
DOI: 10.21468/scipostphys.12.1.037
2022
Cited 31 times
Publishing statistical models: Getting the most out of particle physics experiments
The statistical models used to derive the results of experimental analyses are of incredible scientific value and are essential information for analysis preservation and reuse. In this paper, we make the scientific case for systematically publishing the full statistical models and discuss the technical developments that make this practical. By means of a variety of physics cases - including parton distribution functions, Higgs boson measurements, effective field theory interpretations, direct searches for new physics, heavy flavor physics, direct dark matter detection, world averages, and beyond the Standard Model global fits - we illustrate how detailed information on the statistical modelling can enhance the short- and long-term impact of experimental results.
DOI: 10.1088/1126-6708/2008/03/056
2008
Cited 100 times
Dark matter allowed scenarios for Yukawa-unified SO(10) SUSY GUTs
Simple supersymmetric grand unified models based on the gauge group SO(10) require—in addition to gauge and matter unification—the unification of t-b-τ Yukawa couplings. Owing to sparticle contributions to fermion self-energy diagrams, the Yukawa unification however only occurs for very special values of the soft SUSY breaking parameters. We perform a search using a Markov Chain Monte Carlo (MCMC) technique to investigate model parameters and sparticle mass spectra which occur in Yukawa-unified SUSY models, where we also require the relic density of neutralino dark matter to saturate the WMAP-measured abundance. For Yukawa unified models with μ>0, the spectrum is characterizd by three mass scales: first and second generation scalars in the multi-TeV range, third generation scalars in the TeV range, and gauginos in the ∼ 100 GeV range. Most solutions give far too high a relic abundance of neutralino dark matter. The dark matter discrepancy can be rectified by i). allowing for neutralino decay to axino plus photon, ii). imposing gaugino mass non-universality or iii). imposing generational non-universality. In addition, the MCMC approach finds a compromise solution where scalar masses are not too heavy, and where neutralino annihilation occurs via the light Higgs h resonance. By imposing weak scale Higgs soft term boundary conditions, we are also able to generate low μ, mA solutions with neutralino annihilation via a light A resonance, though these solutions seem to be excluded by CDF/D0 measurements of the Bs → μ+μ− branching fraction. Based on the dual requirements of Yukawa coupling unification and dark matter relic density, we predict new physics signals at the LHC from pair production of 350–450 GeV gluinos. The events are characterized by very high b-jet multiplicity and a dilepton mass edge around m02−m01 ∼ 50–75 GeV.
DOI: 10.1007/jhep02(2012)075
2012
Cited 65 times
Interpreting LHC SUSY searches in the phenomenological MSSM
We interpret within the phenomenological MSSM (pMSSM) the results of SUSY searches published by the CMS collaboration based on the first ~1 fb^-1 of data taken during the 2011 LHC run at 7 TeV. The pMSSM is a 19-dimensional parametrization of the MSSM that captures most of its phenomenological features. It encompasses, and goes beyond, a broad range of more constrained SUSY models. Performing a global Bayesian analysis, we obtain posterior probability densities of parameters, masses and derived observables. In contrast to constraints derived for particular SUSY breaking schemes, such as the CMSSM, our results provide more generic conclusions on how the current data constrain the MSSM.
DOI: 10.1016/j.cpc.2018.02.018
2018
Cited 56 times
Optimizing event selection with the random grid search
The random grid search (RGS) is a simple, but efficient, stochastic algorithm to find optimal cuts that was developed in the context of the search for the top quark at Fermilab in the mid-1990s. The algorithm, and associated code, have been enhanced recently with the introduction of two new cut types, one of which has been successfully used in searches for supersymmetry at the Large Hadron Collider. The RGS optimization algorithm is described along with the recent developments, which are illustrated with two examples from particle physics. One explores the optimization of the selection of vector boson fusion events in the four-lepton decay mode of the Higgs boson and the other optimizes SUSY searches using boosted objects and the razor variables. Program title: Random Grid Search Program Files doi: http://dx.doi.org/10.17632/mpcrnd7xb4.1 Licensing provisions: GNU General Public License 3 (GPL) Programming language: c++, python Nature of problem: We address the problem of scanning a large number of thresholds (cuts) on discriminating variables in order to find ones that maximize some measure of the degree of discrimination between classes of objects, for example, between signal and background events at the Large Hadron Collider (LHC). Solution method: The cuts searched are determined by the distribution of the objects that are the focus of an analysis. For example, if one is searching for supersymmetric events at the LHC, the cuts are determined by the predicted distribution of the variables that discriminate between the supersymmetric signal and the standard model background. In effect, we search for cuts using importance sampling determined by the signal distribution, thereby mitigating the curse of dimensionality. Additional comments including restrictions and unusual features: For cases with exceptionally large numbers of events, the program may take several hours to run. However, the system can be trivially parallelized, with no change to the program, by splitting large files into N smaller files and running the same set of cuts over the N files. The counts associated with each cut can then be summed over the N files.
DOI: 10.1088/1475-7516/2009/02/002
2009
Cited 60 times
Cosmological consequences of Yukawa-unified SUSY with mixed axion/axino cold and warm dark matter
Supersymmetric models with t-b-\tau Yukawa unification at M_{GUT} qualitatively predict a sparticle mass spectrum including first and second generation scalars at the 3--15 TeV scale, third generation scalars at the (few) TeV scale and gluinos in the sub-TeV range. The neutralino relic density in these models typically turns out to lie far above the measured dark matter abundance, prompting the suggestion that instead dark matter is composed of an axion/axino mixture. We explore the axion and thermal and non-thermal axino dark matter abundance in Yukawa-unified SUSY models. We find in this scenario that {\it i}). rather large values of Peccei-Quinn symmetry breaking scale f_a\sim 10^{12} GeV are favored and {\it ii}). rather large values of GUT scale scalar masses \sim 10-15 TeV allow for the re-heat temperature T_R of the universe to be T_R\agt 10^6 GeV. This allows in turn a solution to the gravitino/Big Bang Nucleosynthesis problem while also allowing for baryogenesis via non-thermal leptogenesis. The large scalar masses for Yukawa-unified models are also favored by data on b\to s\gamma and B_s\to \mu^+\mu^- decay. Testable consequences from this scenario include a variety of robust LHC signatures, a possible axion detection at axion search experiments, but null results from direct and indirect WIMP search experiments.
DOI: 10.1088/1126-6708/2009/09/005
2009
Cited 50 times
Is ``just-so'' Higgs splitting needed for<i>t</i>−<i>b</i>−τ Yukawa unified SUSY GUTs?
Recent renormalization group calculations of the sparticle mass spectrum in the Minimal Supersymmetric Standard Model (MSSM) show that t−b−τ Yukawa coupling unification at MGUT is possible when the mass spectra follow the pattern of a radiatively induced inverted scalar mass hierarchy. The calculation is entirely consistent with expectations from SO(10) SUSY GUT theories, with one exception: it seems to require MSSM Higgs soft term mass splitting at MGUT, dubbed ``just-so Higgs splitting'' (HS) in the literature, which apparently violates the SO(10) gauge symmetry. Here, we investigate three alternative effects: i). SO(10) D-term splitting, ii). inclusion of right hand neutrino in the RG calculation, and iii). first/third generation scalar mass splitting. By combining all three effects (the DR3 model), we find t−b−τ Yukawa unification at MGUT can be achieved at the 2.5% level. In the DR3 case, we expect lighter (and possibly detectable) third generation and heavy Higgs scalars than in the model with HS. In addition, the light bottom squark in DR3 should be dominantly a right state, while in the HS model, it is dominantly a left state.
DOI: 10.1140/epjc/s10052-012-1976-3
2012
Cited 39 times
Searches for new physics: Les Houches recommendations for the presentation of LHC results
We present a set of recommendations for the presentation of LHC results on searches for new physics, which are aimed at providing a more efficient flow of scientific information between the experimental collaborations and the rest of the high energy physics community, and at facilitating the interpretation of the results in a wide class of models. Implementing these recommendations would aid the full exploitation of the physics potential of the LHC.
DOI: 10.1007/jhep02(2010)055
2010
Cited 33 times
Testing Yukawa-unified SUSY during year 1 of LHC: the role of multiple b-jets, dileptons and missing E T
We examine the prospects for testing SO(10) Yukawa-unified supersymmetric models during the first year of LHC running at $ \sqrt s = 7\,{\text{TeV}} $ , assuming integrated luminosity values of ∼0.1-1 fb−1. We consider two cases: the Higgs splitting (HS) and the D-term splitting (DR3) models. Each generically predicts light gluinos and heavy squarks, with an inverted scalar mass hierarchy. We hence expect large rates for gluino pair production followed by decays to final states with large b-jet multiplicity. For 0.2 fb−1 of integrated luminosity, we find a 5σ discovery reach of $ {m_{\tilde g}} \sim 400\,{\text{GeV}} $ even if missing transverse energy, E T miss , is not a viable cut variable, by examining the multi-b-jet final state. A corroborating signal should stand out in the opposite-sign (OS) dimuon channel in the case of the HS model; the DR3 model will require higher integrated luminosity to yield a signal in the OS dimuon channel. This region may also be probed by the Tevatron with 5–10 fb−1 of data, if a corresponding search in the multi-b + E T miss channel is performed. With higher integrated luminosities of ∼1 fb−1, using E T miss plus a large multiplicity of b-jets, LHC should be able to discover Yukawa-unified SUSY with $ {m_{\tilde g}} \lesssim 630\,{\text{GeV}} $ . Thus, the year 1 LHC reach for Yukawa-unified SUSY should be enough to either claim a discovery of the gluino, or to very nearly rule out this class of models, since higher values of $ {m_{\tilde g}} $ lead to rather poor Yukawa unification.
DOI: 10.1088/1475-7516/2011/04/039
2011
Cited 29 times
Thermal leptogenesis and the gravitino problem in the Asaka-Yanagida axion/axino dark matter scenario
A successful implementation of thermal leptogenesis requires the re-heat temperature after inflation TR to exceed ∼ 2 × 109 GeV. Such a high TR value typically leads to an overproduction of gravitinos in the early universe, which will cause conflicts, mainly with BBN constraints. Asaka and Yanagida (AY) have proposed that these two issues can be reconciled in the context of the Peccei-Quinn augmented MSSM (PQMSSM) if one adopts a mass hierarchy m(sparticle) > m(gravitino)>m(axino), with m(axino) ∼ keV. In this case, sparticle decays bypass the gravitino, and decay more quickly to the axino LSP, thus avoiding the BBN constraints. In addition, thermally produced gravitinos decay inertly to axion+axino, also avoiding BBN constraints. We calculate the relic abundance of mixed axion/axino dark matter in the AY scenario, and investigate under what conditions a value of TR sufficient for thermal leptogenesis can be generated. A high value of PQ breaking scale fa is needed to suppress overproduction of axinos, while a small vacuum misalignment angle θi is needed to suppress overproduction of axions. The large value of fa results in late decaying neutralinos. We show that, to avoid BBN constraints, the AY scenario requires a rather low thermal abundance of neutralinos, while higher values of neutralino mass also help. We combine these constraint calculations along with entropy production from late decaying saxions, and find the saxion needs to be typically at least several times heavier than the gravitino. A successful implementation of the AY scenario suggests that LHC should discover a spectrum of SUSY particles consistent with weak scale supergravity; that the apparent neutralino abundance is low; that an axion direct detection signal (probably with ma in the sub-μeV range) may be possible, but no direct or indirect signals for WIMP dark matter should be observed.
DOI: 10.1103/physrevd.85.115022
2012
Cited 24 times
Higgs boson production via vectorlike top-partner decays: Diphoton or multilepton plus multijets channels at the LHC
We first build a minimal model of vector-like quarks where the dominant Higgs boson production process at LHC -- the gluon fusion -- can be significantly suppressed, being motivated by the recent stringent constraints from the search for direct Higgs production over a wide Higgs mass range. Within this model, compatible with the present experimental constraints on direct Higgs searches, we demonstrate that the Higgs ($h$) production via a heavy vector-like top-partner ($t_2$) decay, $pp \to t_2 \bar t_2$, $t_2\to t h$, allows to discover a Higgs boson at the LHC and measure its mass, through the decay channels $h\to \gamma\gamma$ or $h\to ZZ$. We also comment on the recent hint in LHC data from a possible $\sim 125$ GeV Higgs scalar, in the presence of heavy vector-like top quarks.
DOI: 10.1007/jhep11(2015)125
2015
Cited 23 times
General squark flavour mixing: constraints, phenomenology and benchmarks
We present an extensive study of non-minimal flavour violation in the squark sector in the framework of the Minimal Supersymmetric Standard Model. We investigate the effects of multiple non-vanishing flavour-violating elements in the squark mass matrices by means of a Markov Chain Monte Carlo scanning technique and identify parameter combinations that are favoured by both current data and theoretical constraints. We then detail the resulting distributions of the flavour-conserving and flavour-violating model parameters. Based on this analysis, we propose a set of benchmark scenarios relevant for future studies of non-minimal flavour violation in the Minimal Supersymmetric Standard Model.
DOI: 10.1007/jhep10(2010)018
2010
Cited 25 times
Effective supersymmetry at the LHC
We investigate the phenomenology of Effective Supersymmetry (ESUSY) models wherein electroweak gauginos and third generation scalars have masses up to about 1 TeV while first and second generation scalars lie in the multi-TeV range. Such models ameliorate the SUSY flavor and CP problems via a decoupling solution, while at the same time maintaining naturalness. In our analysis, we assume independent GUT scale mass parameters for third and first/second generation scalars and for the Higgs scalars, in addition to m 1/2, tan β and A 0, and require radiative electroweak symmetry breaking as usual. We analyse the parameter space which is consistent with current constraints, by means of a Markov Chain Monte Carlo scan. The lightest MSSM particle (LMP) is mostly, but not always the lightest neutralino, and moreover, the thermal relic density of the neutralino LMP is frequently very large. These models may phenomenologically be perfectly viable if the LMP before nucleosynthesis decays into the axino plus SM particles. Dark matter is then an axion/axino mixture. At the LHC, the most important production mechanisms are gluino production (for m 1/2 ≲ 700 GeV) and third generation squark production, while SUSY events rich in b-jets are the hallmark of the ESUSY scenario. We present a set of ESUSY benchmark points with characteristic features and discuss their LHC phenomenology.
DOI: 10.48550/arxiv.1803.10379
2018
Cited 17 times
Les Houches 2017: Physics at TeV Colliders New Physics Working Group Report
We present the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 5--23 June, 2017). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments.
DOI: 10.22323/1.450.0159
2024
Recent Searches for Supersymmetry in CMS
This report summarizes four of the recently published supersymmetry (SUSY) searches performed on 139 fb$^{-1}$ of 13 TeV pp collision data collected by the CMS experiment between years 2016-2018. These are the combined search for electroweak production of winos, binos, higgsinos, and sleptons; search for stealth SUSY in final states with two photons, jets, and low missing transverse momentum; search for new physics in multijet events with at least one photon and large missing transverse momentum; and search for SUSY in final states with disappearing tracks. The latter is presented first time at the LHCP2023 conference. These searches, all targeting challenging signatures, feature innovative analysis methodologies and have resulted in enhanced sensitivity in various regions of the SUSY parameter space.
DOI: 10.1088/1126-6708/2008/10/079
2008
Cited 23 times
Prospects for Yukawa unified SO(10) SUSY GUTs at the CERN LHC
The requirement of t−b−τ Yukawa coupling unification is common in simple grand unified models based on the gauge group SO(10), and it also places a severe constraint on the expected spectrum of superpartners. For Yukawa-unified models with μ>0, the spectrum is characterized by three mass scales: i) first and second generation scalars in the multi-TeV range, ii) third generation scalars, μ and mA in the few-TeV range and iii) gluinos in the ∼ 350−500 GeV range with chargino masses around 100-160 GeV. In such a scenario, gluino pair production should occur at large rates at the CERN LHC, followed by gluino three-body decays into neutralinos or charginos. Discovery of Yukawa-unified SUSY at the LHC should hence be possible with only 1 fb−1 of integrated luminosity, by tagging multi-jet events with 2-3 isolated leptons, without relying on missing ET. A characteristic dilepton mass edge should easily be apparent above Standard Model background. Combining dileptons with b-jets, along with the gluino pair production cross section information, should allow for gluino and neutralino mass reconstruction. A secondary corroborative signal should be visible at higher integrated luminosity in the ±102 → 3ℓ channel, and should exhibit the same dilepton mass edge as in the gluino cascade decay signal.
DOI: 10.48550/arxiv.1405.1617
2014
Cited 15 times
Les Houches 2013: Physics at TeV Colliders: New Physics Working Group Report
We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 3--21 June, 2013). Our report includes new computational tool developments, studies of the implications of the Higgs boson discovery on new physics, important signatures for searches for natural new physics at the LHC, new studies of flavour aspects of new physics, and assessments of the interplay between direct dark matter searches and the LHC.
DOI: 10.1103/physrevd.86.075025
2012
Cited 12 times
Phenomenological MSSM interpretation of LHC results using rernormalization group invariants
The LHC has started to constrain supersymmetry-breaking parameters by setting bounds on possible colored particles at the weak scale. Moreover, constraints from Higgs physics, flavor physics, the anomalous magnetic moment of the muon, as well as from searches at LEP and the Tevatron have set additional bounds on these parameters. Renormalization Group Invariants (RGIs) provide a very useful way of representing the allowed parameter space by making direct connection with the values of these parameters at the messenger scale. Using a general approach, based on the pMSSM parametrization of the soft supersymmetry-breaking parameters, we analyze the current experimental constraints to determine the probability distributions for the RGIs. As examples of their application, we use these distributions to analyze the question of Gaugino Mass Unification and to probabilistically determine the parameters of General and Minimal Gauge Mediation with arbitrary Higgs mass parameters at the Messenger Scale.
DOI: 10.1016/j.cpc.2018.06.023
2018
Cited 12 times
CutLang: A Particle Physics Analysis Description Language and Runtime Interpreter
This note introduces CutLang, a domain specific language that aims to provide a clear, human readable way to define analyses in high energy particle physics (HEP) along with an interpretation framework of that language. A proof of principle (PoP) implementation of the CutLang interpreter, achieved using C++ as a layer over the CERN data analysis framework ROOT, is presently available. This PoP implementation permits writing HEP analyses in an unobfuscated manner, as a set of commands in human readable text files, which are interpreted by the framework at runtime. We describe the main features of CutLang and illustrate its usage with two analysis examples. Initial experience with CutLang has shown that a just-in-time interpretation of a human readable HEP specific language is a practical alternative to analysis writing using compiled languages such as C++. Program summary Program title: CutLang Program Files doi: http://dx.doi.org/10.17632/pym39s7vy7.1 Licensing provisions: GNU General Public License 3 (GPL) Programming language: C++ Nature of problem: Obtaining a physics result from high energy collider (e.g. LHC) data typically involves complex software frameworks for data analysis. Operating such analysis frameworks usually demands high computational expertise from the physicists, which makes trying simple analysis ideas difficult. The difficulty can be overcome by decoupling the description of all physics components of an analysis from the software framework. Analyses would thus be fully and unambiguously described by a framework-independent domain specific language. Defining such a language, which would be text-based and human readable is the first problem this paper investigates. Once a text-based language is available, a major task is to write an interpreter (or compiler) that converts it into instructions that can actually be executed, perhaps in some framework. The second problem addressed here is to write an automated, just-in-time interpreter to perform this task. Solution method: CutLang addresses the above problems by first constructing a domain specific language which aims to provide a clear, human readable way to define high energy physics analyses. The language is capable of defining various components of the analysis like object selection, event selection, and allows analysis tools like variable definition, χ2 minimization, multiple selection regions definition and many others. CutLang also provides an automated interpretation framework for the language, which is achieved using C++ classes as a layer over the CERN ROOT framework. The interpreter evaluates each component of the analysis description at runtime, without compilation. It handles event selection by classes which consist of a function that evaluates event-by-event object or event related quantities, a comparison operator, and one or two limit values, For each evaluation, the function result is compared to the limit values to find a boolean result of 0 or 1. Multiple selection criteria are combined together using logical operators. CutLang evaluates such expressions numerically by first converting them into Reverse Polish Notation, and then by parsing them with the Shunting Yard algorithm. Several properties of the interpreter are being able to work with multiple particle types, allowing particle combinations to make new particles, offering standard functions, histogramming, etc. Additional comments including restrictions and unusual features: The CutLang language and interpreter can work for a large number of physics analyses at the LHC. However it would benefit from some generalizations which would make it eligible for a larger variety of analysis. These generalizations could be achieved by inclusion of external functions for computing analysis-related variables, and allowing user-defined particle collections.
2021
Cited 8 times
arXiv : The Dark Machines Anomaly Score Challenge: Benchmark Data and Model Independent Event Classification for the Large Hadron Collider
We describe the outcome of a data challenge conducted as part of the Dark Machines Initiative and the Les Houches 2019 workshop on Physics at TeV colliders. The challenged aims at detecting signals of new physics at the LHC using unsupervised machine learning algorithms. First, we propose how an anomaly score could be implemented to define model-independent signal regions in LHC searches. We define and describe a large benchmark dataset, consisting of >1 Billion simulated LHC events corresponding to $10~\rm{fb}^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV. We then review a wide range of anomaly detection and density estimation algorithms, developed in the context of the data challenge, and we measure their performance in a set of realistic analysis environments. We draw a number of useful conclusions that will aid the development of unsupervised new physics searches during the third run of the LHC, and provide our benchmark dataset for future studies at this https URL. Code to reproduce the analysis is provided at this https URL.
DOI: 10.1088/1475-7516/2010/11/040
2010
Cited 13 times
Reconciling thermal leptogenesis with the gravitino problem in SUSY models with mixed axion/axino dark matter
Successful implementation of thermal leptogenesis requires re-heat temperatures T_R\agt 2\times 10^9 GeV, in apparent conflict with SUSY models with TeV-scale gravitinos, which require much lower T_R in order to avoid Big Bang Nucleosynthesis (BBN) constraints. We show that mixed axion/axino dark matter can reconcile thermal leptogenesis with the gravitino problem in models with m_{\tG}\agt 30 TeV, a rather high Peccei-Quinn breaking scale and an initial mis-alignment angle θ_i &lt; 1. We calculate axion and axino dark matter production from four sources, and impose BBN constraints on long-lived gravitinos and neutralinos. Moreover, we discuss several SUSY models which naturally have gravitino masses of the order of tens of TeV. We find a reconciliation difficult in Yukawa-unified SUSY and in AMSB with a wino-like lightest neutralino. However, T_R\sim 10^{10}-10^{12} GeV can easily be achieved in effective SUSY and in models based on mixed moduli-anomaly mediation. Consequences of this scenario include: 1. an LHC SUSY discovery should be consistent with SUSY models with a large gravitino mass, 2. an apparent neutralino relic abundance Ω_{\tz_1}h^2\alt 1, 3. no WIMP direct or indirect detection signals should be found, and 4. the axion mass should be less than \sim 10^{-6} eV, somewhat below the conventional range which is explored by microwave cavity axion detection experiments.
DOI: 10.48550/arxiv.2203.10057
2022
Cited 4 times
Data and Analysis Preservation, Recasting, and Reinterpretation
We make the case for the systematic, reliable preservation of event-wise data, derived data products, and executable analysis code. This preservation enables the analyses' long-term future reuse, in order to maximise the scientific impact of publicly funded particle-physics experiments. We cover the needs of both the experimental and theoretical particle physics communities, and outline the goals and benefits that are uniquely enabled by analysis recasting and reinterpretation. We also discuss technical challenges and infrastructure needs, as well as sociological challenges and changes, and give summary recommendations to the particle-physics community.
DOI: 10.48550/arxiv.0802.3672
2008
Cited 9 times
Physics Beyond the Standard Model: Supersymmetry
This collection of studies on new physics at the LHC constitutes the report of the supersymmetry working group at the Workshop `Physics at TeV Colliders', Les Houches, France, 2007. They cover the wide spectrum of phenomenology in the LHC era, from alternative models and signatures to the extraction of relevant observables, the study of the MSSM parameter space and finally to the interplay of LHC observations with additional data expected on a similar time scale. The special feature of this collection is that while not each of the studies is explicitely performed together by theoretical and experimental LHC physicists, all of them were inspired by and discussed in this particular environment.
DOI: 10.1016/j.physletb.2010.01.035
2010
Cited 7 times
Beyond the Higgs boson at the Tevatron: Detecting gluinos from Yukawa-unified SUSY
Simple SUSY GUT models based on the gauge group SO(10) require t-b-\tau Yukawa coupling unification, in addition to gauge coupling and matter unification. The Yukawa coupling unification places strong constraints on the expected superparticle mass spectrum, with scalar masses \sim 10 TeV while gluino masses are much lighter: in the 300--500 GeV range. The very heavy squarks suppress negative interference in the q\bar{q}\to\tg\tg cross section, leading to a large enhancement in production rates. The gluinos decay almost always via three-body modes into a pair of b-quarks, so we expect at least four b-jets per signal event. We investigate the capability of Fermilab Tevatron collider experiments to detect gluino pair production in Yukawa-unified SUSY. By requiring events with large missing E_T and \ge 2 or 3 tagged b-jets, we find a 5\sigma reach in excess of m_{\tg}\sim 400 GeV for 5 fb^{-1} of data. This range in m_{\tg} is much further than the conventional Tevatron SUSY reach, and should cut a significant swath through the most favored region of parameter space for Yukawa-unified SUSY models.
DOI: 10.1088/1742-6596/1525/1/012025
2020
Cited 5 times
CutLang: a cut-based HEP analysis description language and runtime interpreter
Abstract We present CutLang, an analysis description language and runtime interpreter for high energy collider physics data analyses. An analysis description language is a declerative domain specific language that can express all elements of a data analysis in an easy and unambiguous way. A full-fledged human readable analysis description language, incorporating logical and mathematical expressions, would eliminate many programming difficulties and errors, consequently allowing the scientist to focus on the goal, but not on the tool. In this paper, we discuss the guiding principles and scope of the CutLang language, implementation of the CutLang runtime interpreter and the CutLang framework, and demonstrate an example of top pair reconstruction.
2007
Cited 7 times
Energy Response and Longitudinal Shower Profiles Measured in CMS HCAL and Comparison With Geant4
DOI: 10.48550/arxiv.1005.1229
2010
Cited 5 times
New Physics at the LHC. A Les Houches Report: Physics at TeV Colliders 2009 - New Physics Working Group
We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models of strong electroweak symmetry are discussed. In the fourth part, a special attention is devoted to high mass resonances, as the ones appearing in models with warped extra dimensions. Finally, prospects for models with a hidden sector/valley are presented. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 8-26 June, 2009).
DOI: 10.1140/epjc/s10052-021-08982-4
2021
Cited 4 times
Down type iso-singlet quarks at the HL-LHC and FCC-hh
Abstract We study the discovery potential of down type iso-singlet quarks, D , predicted by the $$E_6$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>E</mml:mi> <mml:mn>6</mml:mn> </mml:msub> </mml:math> GUT model in the $${pp\rightarrow D\bar{D}\rightarrow ZZd\bar{d} \rightarrow \ell ^+\ell ^-\ell ^+\ell ^- d\bar{d}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>p</mml:mi> <mml:mi>p</mml:mi> <mml:mo>→</mml:mo> <mml:mi>D</mml:mi> <mml:mover> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>→</mml:mo> <mml:mi>Z</mml:mi> <mml:mi>Z</mml:mi> <mml:mi>d</mml:mi> <mml:mover> <mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>ℓ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>ℓ</mml:mi> <mml:mo>-</mml:mo> </mml:msup> <mml:msup> <mml:mi>ℓ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>ℓ</mml:mi> <mml:mo>-</mml:mo> </mml:msup> <mml:mi>d</mml:mi> <mml:mover> <mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> </mml:math> channel, at the HL-LHC and FCC-hh colliders. The analysis is performed using a high level analysis description language and its runtime interpreter. The study shows that, using solely this channel, HL-LHC can discover D quarks up to a mass of 730 GeV whereas FCC-hh up to 2980 GeV with data collected in their complete run periods.
2008
Cited 5 times
Design, Performance, and Calibration of CMS Hadron Endcap Calorimeters
2014
Cited 3 times
Les Houches 2013: Physics at TeV Colliders: New Physics Working Group Report
We present the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments. Important signatures for searches for natural new physics at the LHC and new assessments of the interplay between direct dark matter searches and the LHC are also considered.
2010
Cited 3 times
New Physics at the LHC. a Les Houches Report: Physics at TeV Colliders 2009 - New Physics Working Group
We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models of strong electroweak symmetry are discussed. In the fourth part, a special attention is devoted to high mass resonances, as the ones appearing in models with warped extra dimensions. Finally, prospects for models with a hidden sector/valley are presented. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 8-26 June, 2009).
DOI: 10.22323/1.282.0181
2017
Cited 3 times
Recent Developments in CMS Fast Simulation
CMS has developed a fast detector simulation package, which serves as a fast and reliable alternative to the detailed GEANT4-based (full) simulation, and enables efficient simulation of large numbers of standard model and new physics events.Fast simulation becomes particularly important with the current increase in the LHC luminosity.Here, I will discuss the basic principles behind the CMS fast simulation framework, and how they are implemented in the different detector components in order to simulate and reconstruct sufficiently accurate physics objects for analysis.I will focus on recent developments in tracking and geometry interface, which improve the flexibility and emulation performance of the framework, and allow a better synchronization with the full simulation.I will then show how these developments have led to an improved agreement of basic analysis objects and event variables between fast and full simulation.
DOI: 10.22323/1.382.0065
2020
Cited 3 times
Analysis description languages for the LHC
An analysis description language is a domain specific language capable of describing the contents of an LHC analysis in a standard and unambiguous way, independent of any computing framework.It is designed for use by anyone with an interest in, and knowledge of, LHC physics, i.e., experimentalists, phenomenologists and other enthusiasts.Adopting analysis description languages would bring numerous benefits for the LHC experimental and phenomenological communities ranging from analysis preservation beyond the lifetimes of experiments or analysis software to facilitating the abstraction, design, visualization, validation, combination, reproduction, interpretation and overall communication of the analysis contents.Here, we introduce the analysis description language concept and summarize the current efforts ongoing to develop such languages and tools to use them in LHC analyses.
DOI: 10.1088/1361-6404/abdf67
2021
Cited 3 times
CutLang as an analysis description language for introducing students to analyses in particle physics
Abstract The fifth edition of the ‘Computing Applications in Particle Physics’ school was held on 3–7 February 2020, at İstanbul University, Turkey. This particular edition focused on the processing of simulated data from the large hadron collider collisions using an analysis description language and its runtime interpreter called CutLang. 24 undergraduate and 6 graduate students were initiated to collider data analysis during the school. After 3 days of lectures and exercises, the students were grouped into teams of 3 or 4 and each team was assigned an analysis publication from ATLAS or CMS experiments. After 1.5 days of independent study, each team was able to reproduce the assigned analysis using CutLang.
DOI: 10.48550/arxiv.1307.5865
2013
On the presentation of the LHC Higgs Results
We put forth conclusions and suggestions regarding the presentation of the LHC Higgs results that may help to maximize their impact and their utility to the whole High Energy Physics community.
DOI: 10.1088/1742-6596/2438/1/012075
2023
Declarative interfaces for HEP data analysis: FuncADL and ADL/CutLang
Abstract Analysis description languages are declarative interfaces for HEP data analysis that allow users to avoid writing event loops, simplify code, and enable performance improvements to be decoupled from analysis development. One example is FuncADL, inspired by functional programming and developed using Python as a host language. FuncADL borrows concepts from database query languages to isolate the interface from the underlying physical and logical schemas. The same query can be used to select data from different sources and formats and with different execution mechanisms. FuncADL is one of the tools being developed by IRIS-HEP for highly scalable physics analysis for the LHC and HL-LHC. FuncADL is demonstrated by implementing example analysis tasks designed by HSF and IRIS-HEP. Another language example is ADL, which expresses the physics content of an analysis in a standard and unambiguous way, independent of computing frameworks. In ADL, analyses are described in human-readable text files composed of blocks with a keyword-expression structure. Two infrastructures are available to render ADL executable: CutLang, a runtime interpreter written in C++; and adl2tnm, a transpiler converting ADL into C++ or Python code. ADL/CutLang are already used in several physics studies and educational projects, and are adapted for use with LHC Open Data.
DOI: 10.48550/arxiv.2312.14575
2023
Les Houches guide to reusable ML models in LHC analyses
With the increasing usage of machine-learning in high-energy physics analyses, the publication of the trained models in a reusable form has become a crucial question for analysis preservation and reuse. The complexity of these models creates practical issues for both reporting them accurately and for ensuring the stability of their behaviours in different environments and over extended timescales. In this note we discuss the current state of affairs, highlighting specific practical issues and focusing on the most promising technical and strategic approaches to ensure trustworthy analysis-preservation. This material originated from discussions in the LHC Reinterpretation Forum and the 2023 PhysTeV workshop at Les Houches.
DOI: 10.3389/fdata.2021.659986
2021
CutLang v2: Advances in a Runtime-Interpreted Analysis Description Language for HEP Data
We will present the latest developments in CutLang, the runtime interpreter of a recently-developed analysis description language (ADL) for collider data analysis. ADL is a domain-specific, declarative language that describes the contents of an analysis in a standard and unambiguous way, independent of any computing framework. In ADL, analyses are written in human-readable plain text files, separating object, variable and event selection definitions in blocks, with a syntax that includes mathematical and logical operations, comparison and optimisation operators, reducers, four-vector algebra and commonly used functions. Adopting ADLs would bring numerous benefits to the LHC experimental and phenomenological communities, ranging from analysis preservation beyond the lifetimes of experiments or analysis software to facilitating the abstraction, design, visualization, validation, combination, reproduction, interpretation and overall communication of the analysis contents. Since their initial release, ADL and CutLang have been used for implementing and running numerous LHC analyses. In this process, the original syntax from CutLang v1 has been modified for better ADL compatibility, and the interpreter has been adapted to work with that syntax, resulting in the current release v2. Furthermore, CutLang has been enhanced to handle object combinatorics, to include tables and weights, to save events at any analysis stage, to benefit from multi-core/multi-CPU hardware among other improvements. In this contribution, these and other enhancements are discussed in details. In addition, real life examples from LHC analyses are presented together with a user manual.
DOI: 10.2172/1437300
2018
HEP Software Foundation Community White Paper Working Group - Detector Simulation
A working group on detector simulation was formed as part of the high-energy physics (HEP) Software Foundation's initiative to prepare a Community White Paper that describes the main software challenges and opportunities to be faced in the HEP field over the next decade. The working group met over a period of several months in order to review the current status of the Full and Fast simulation applications of HEP experiments and the improvements that will need to be made in order to meet the goals of future HEP experimental programmes. The scope of the topics covered includes the main components of a HEP simulation application, such as MC truth handling, geometry modeling, particle propagation in materials and fields, physics modeling of the interactions of particles with matter, the treatment of pileup and other backgrounds, as well as signal processing and digitisation. The resulting work programme described in this document focuses on the need to improve both the software performance and the physics of detector simulation. The goals are to increase the accuracy of the physics models and expand their applicability to future physics programmes, while achieving large factors in computing performance gains consistent with projections on available computing resources.
DOI: 10.48550/arxiv.1607.01212
2016
LHCSki 2016 - A First Discussion of 13 TeV Results
These are the proceedings of the LHCSki 2016 workshop "A First Discussion of 13 TeV Results" that has been held at the Obergurgl Universitätszentrum, Tirol, Austria, April 10 - 15, 2016. In this workshop the consequences of the most recent results from the LHC have been discussed, with a focus also on the interplay with dark matter physics, flavor physics, and precision measurements. Contributions from the workshop speakers have been compiled into this document.
DOI: 10.48550/arxiv.2203.09886
2022
Analysis Description Language: A DSL for HEP Analysis
We propose to adopt a declarative domain specific language for describing the physics algorithm of a high energy physics (HEP) analysis in a standard and unambiguous way decoupled from analysis software frameworks, and argue that this approach provides an accessible and sustainable environment for analysis design, use and preservation. Prototype of such a language called Analysis Description Language (ADL) and its associated tools are being developed and applied in various HEP physics studies. We present the motivations for using a DSL, design principles of ADL and its runtime interpreter CutLang, along with current physics studies based on this approach. We also outline ideas and prospects for the future. Recent physics studies, hands-on workshops and surveys indicate that ADL is a feasible and effective approach with many advantages and benefits, and offers a direction to which the HEP field should give serious consideration.
2013
On the presentation of the LHC Higgs Results
We put forth conclusions and suggestions regarding the presentation of the LHC Higgs results that may help to maximize their impact and their utility to the whole High Energy Physics community.
2014
Inclusive SUSY searches at the LHC
I summarize the status of the inclusive SUSY searches conducted by the ATLAS and CMS experiments using the 20 fb-1 of 8 TeV LHC data in the all inclusive, 0 lepton, >=1 lepton and >=2 lepton final states. Current searches show that data are consistent with the SM. The impact of this consistency was explored on a rich variety of SUSY scenarios and simplified models, examples of which I present here.
DOI: 10.1016/j.nima.2012.01.031
2012
Dark matter searches with the CMS experiment in 2010
We report on the dark matter searches performed by the Compact Muon Solenoid experiment using the 35 pb−1 of 7 TeV pp data collected by the CERN Large Hadron Collider in 2010. All observations so far were found to be consistent with the Standard Model predictions. The search results were used for setting exclusion limits on various new physics scenarios.
2017
Recent Developments in CMS Fast Simulation
CMS has developed a fast detector simulation package, which serves as a fast and reliable alternative to the detailed GEANT4-based (full) simulation, and enables efficient simulation of large numbers of standard model and new physics events. Fast simulation becomes particularly important with the current increase in the LHC luminosity. Here, I will discuss the basic principles behind the CMS fast simulation framework, and how they are implemented in the different detector components in order to simulate and reconstruct sufficiently accurate physics objects for analysis. I will focus on recent developments in tracking and geometry interface, which improve the flexibility and emulation performance of the framework, and allow a better synchronization with the full simulation. I will then show how these developments have led to an improved agreement of basic analysis objects and event variables between fast and full simulation.
2009
New Physics at the LHC. A Les Houches Report: Physics at TeV Colliders 2009 - New Physics Working Group
We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models of strong electroweak symmetry are discussed. In the fourth part, a special attention is devoted to high mass resonances, as the ones appearing in models with warped extra dimensions. Finally, prospects for models with a hidden sector/valley are presented. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the New working group for the Physics at TeV Colliders workshop (Les Houches, France, 8-26 June, 2009).
2007
Synchronization and timing in CMS HCAL
The synchronization and timing of the hadron calorimeter (HCAL) for the Compact Muon Solenoid has been extensively studied with test beams at CERN during the period 2003-4, including runs with 40 MHz structured beam. The relative phases of the signals from different calorimeter segments are timed to 1 ns accuracy using a laser and equalized using programmable delay settings in the front-end electronics. The beam was used to verify the timing and to map out the entire range of pulse shapes over the 25 ns interval between beam crossings. These data were used to make detailed measurements of energy-dependent time slewing effects and to tune the electronics for optimal performance.
DOI: 10.48550/arxiv.2002.02837
2020
Report on the ECFA Early-Career Researchers Debate on the 2020 European Strategy Update for Particle Physics
A group of Early-Career Researchers (ECRs) has been given a mandate from the European Committee for Future Accelerators (ECFA) to debate the topics of the current European Strategy Update (ESU) for Particle Physics and to summarise the outcome in a brief document [1]. A full-day debate with 180 delegates was held at CERN, followed by a survey collecting quantitative input. During the debate, the ECRs discussed future colliders in terms of the physics prospects, their implications for accelerator and detector technology as well as computing and software. The discussion was organised into several topic areas. From these areas two common themes were particularly highlighted by the ECRs: sociological and human aspects; and issues of the environmental impact and sustainability of our research.
DOI: 10.3389/fdata.2021.736105
2021
Editorial: Innovative Analysis Ecosystems for HEP Data
This editorial summarizes the contributions to the Frontiers Research topic “Innovative Analysis Ecosystems for HEP Data”, established under the Big Data and AI in High Energy Physics section and appearing under the Frontiers in Big Data and Frontiers in Artificial Intelligence journals.
DOI: 10.22323/1.234.0576
2016
An MCMC study of non-minimal flavour violation in the MSSM
We present an extensive study of non-minimally flavour violating (NMFV) terms in the Lagrangian of the Minimal Supersymmetric Standard Model (MSSM). We impose a variety of theoretical and experimental constraints and perform a detailed scan of the parameter space by means of a Markov Chain Monte-Carlo (MCMC) setup. This represents the first study of several non-zero flavour-violating elements within the MSSM. We present the results of the MCMC scan with a special focus on the flavour-violating parameters. Based on these results, we define benchmark scenarios for future studies of NMFV effects at the LHC.
DOI: 10.22323/1.180.0311
2014
Search for Natural SUSY with inclusive search strategies at the LHC using the CMS detector
Natural SUSY suggests the existence of light stop quarks, accessible at the LHC, which are the focus of a dedicated CMS search program. I present two inclusive CMS searches that look for TeV scale colored sparticles in final states with jets, b-tagged jets and missing transverse energy performed using up to 19.4fb-1 of 8TeV LHC proton-proton data. No deviation from the Standard Model was observed in these searches, and the implications for this was shown for several simplified model scenarios and phenomenological MSSM.
2015
An MCMC study of general squark flavour mixing in the MSSM
We present an extensive study of non-minimally flavour violating (NMFV) terms in the Lagrangian of the Minimal Supersymmetric Standard Model (MSSM). We impose a variety of theoretical and experimental constraints and perform a detailed scan of the parameter space by means of a Markov Chain Monte-Carlo (MCMC) setup. This represents the first study of several non-zero flavour-violating elements within the MSSM. We present the results of the MCMC scan with a special focus on the flavour-violating parameters. Based on these results, we define benchmark scenarios for future studies of NMFV effects at the LHC.
2016
Exploring the squark flavour structure of the MSSM
We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC.
2015
An MCMC Study of General Squark Flavour Mixing in the MSSM
We present an extensive study of non-minimally flavour violating (NMFV) terms in the Lagrangian of the Minimal Supersymmetric Standard Model (MSSM). We impose a variety of theoretical and experimental constraints and perform a detailed scan of the parameter space by means of a Markov Chain Monte-Carlo (MCMC) setup. This represents the first study of several non-zero flavour-violating elements within the MSSM. We present the results of the MCMC scan with a special focus on the flavour-violating parameters. Based on these results, we define benchmark scenarios for future studies of NMFV effects at the LHC.
DOI: 10.48550/arxiv.1405.4730
2014
Inclusive SUSY searches at the LHC
I summarize the status of the inclusive SUSY searches conducted by the ATLAS and CMS experiments using the 20 fb-1 of 8 TeV LHC data in the all inclusive, 0 lepton, >=1 lepton and >=2 lepton final states. Current searches show that data are consistent with the SM. The impact of this consistency was explored on a rich variety of SUSY scenarios and simplified models, examples of which I present here.
2011
Priors for New Physics
The interpretation of data in terms of multi-parameter models of new physics, using the Bayesian approach, requires the construction of multi-parameter priors. We propose a construction that uses elements of Bayesian reference analysis. Our idea is to initiate the chain of inference with the reference prior for a likelihood function that depends on a single parameter of interest that is a function of the parameters of the physics model. The reference posterior density of the parameter of interest induces on the parameter space of the physics model a class of posterior densities. We propose to continue the chain of inference with a particular density from this class, namely, the one for which indistinguishable models are equiprobable and use it as the prior for subsequent analysis. We illustrate our method by applying it to the constrained minimal supersymmetric Standard Model and two non-universal variants of it.
2011
Status of CMS Dark Matter Searches in 2011
We present the status of dark matter searches performed by the Compact Muon Solenoid Experiment using 7 TeV pp data collected by the CERN Large Hadron Collider in 2010 and 2011. Majority of the results shown here were obtained using 1.1fb−1 of data. We give highlights from analyses searching for candidates like WIMPs, gravitinos, axinos and TeV scale particles. All observations so far were found to be consistent with the Standard Model predictions. The search results were used for setting exclusion limits on various new physics scenarios.
DOI: 10.48550/arxiv.1107.2877
2011
Model Inference with Reference Priors
We describe the application of model inference based on reference priors to two concrete examples in high energy physics: the determination of the CKM matrix parameters rhobar and etabar and the determination of the parameters m_0 and m_1/2 in a simplified version of the CMSSM SUSY model. We show how a 1-dimensional reference posterior can be mapped to the n-dimensional (n-D) parameter space of the given class of models, under a minimal set of conditions on the n-D function. This reference-based function can be used as a prior for the next iteration of inference, using Bayes' theorem recursively.
2012
SUSY with Heavy Scalars at the LHC
DOI: 10.48550/arxiv.1112.3518
2011
Status of CMS dark matter searches in 2011
We present the status of dark matter searches performed by the Compact Muon Solenoid Experiment using 7 TeV pp data collected by the CERN Large Hadron Collider in 2010 and 2011. The majority of the results shown here were obtained using 1.1 fb-1 of data. We give highlights from analyses searching for candidates such as WIMPs, gravitinos, axinos and TeV scale particles. All observations so far were found to be consistent with the Standard Model predictions. The search results were used to set exclusion limits on various new physics scenarios.
DOI: 10.48550/arxiv.1108.0523
2011
Priors for New Physics
The interpretation of data in terms of multi-parameter models of new physics, using the Bayesian approach, requires the construction of multi-parameter priors. We propose a construction that uses elements of Bayesian reference analysis. Our idea is to initiate the chain of inference with the reference prior for a likelihood function that depends on a single parameter of interest that is a function of the parameters of the physics model. The reference posterior density of the parameter of interest induces on the parameter space of the physics model a class of posterior densities. We propose to continue the chain of inference with a particular density from this class, namely, the one for which indistinguishable models are equiprobable and use it as the prior for subsequent analysis. We illustrate our method by applying it to the constrained minimal supersymmetric Standard Model and two non-universal variants of it.
DOI: 10.48550/arxiv.1311.1847
2013
Search for Natural SUSY with inclusive search strategies at the LHC using the CMS detector
Natural SUSY suggests the existence of light stop quarks, accessible at the LHC, which are the focus of a dedicated CMS search program. I present two inclusive CMS searches that look for TeV scale colored sparticles in final states with jets, b-tagged jets and missing transverse energy performed using up to 19.4fb-1 of 8TeV LHC proton-proton data. No deviation from the Standard Model was observed in these searches, and the implications for this was shown for several simplified model scenarios and phenomenological MSSM.
2017
Recent Developments in CMS Fast Simulation
DOI: 10.22323/1.282.0834
2017
Exploring the squark flavour structure of the MSSM
We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC.
2017
Exploring the squark flavour structure of the MSSM
We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC.
DOI: 10.48550/arxiv.1701.01700
2017
Exploring the squark flavour structure of the MSSM
We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC.
DOI: 10.48550/arxiv.1701.03850
2017
Recent Developments in CMS Fast Simulation
CMS has developed a fast detector simulation package, which serves as a fast and reliable alternative to the detailed GEANT4-based (full) simulation, and enables efficient simulation of large numbers of standard model and new physics events. Fast simulation becomes particularly important with the current increase in the LHC luminosity. Here, I will discuss the basic principles behind the CMS fast simulation framework, and how they are implemented in the different detector components in order to simulate and reconstruct sufficiently accurate physics objects for analysis. I will focus on recent developments in tracking and geometry interface, which improve the flexibility and emulation performance of the framework, and allow a better synchronization with the full simulation. I will then show how these developments have led to an improved agreement of basic analysis objects and event variables between fast and full simulation.
DOI: 10.48550/arxiv.0805.2664
2008
Search for WMAP-Compatible Simple SO(10) SUSY GUTs
Unification of GUT-scale t-b-τYukawa couplings is a significant feature of simple SO(10) SUSY GUTs. Here we present the results of a search that used the Markov Chain Monte Carlo technique to investigate regions of Yukawa unification and WMAP-compatible dark matter relic density in SO(10)-like MSSM parameter spaces. We mention the possible LHC signatures of Yukawa unified scenarios and discuss the consequences for dark matter.
2009
Letter of Intent from the Fourth Detector (“4th”) Collaboration at the International Linear Collider, INFN Lecce Internal Report, 2009.
DOI: 10.22323/1.398.0906
2022
Democratizing LHC data analysis with ADL/CutLang
Data analysis at the LHC has a very steep learning curve, which erects a formidable barrier between data and anyone who wishes to analyze data, either to study an idea or to simply understand how data analysis is performed.To make analysis more accessible, we designed the so-called Analysis Description Language (ADL), a domain specific language capable of describing the contents of an LHC analysis in a standard and unambiguous way, independent of any computing frameworks.ADL has an English-like highly human-readable syntax and directly employs concepts relevant to HEP.Therefore it eliminates the need to learn complex analysis frameworks written based on general purpose languages such as C++ or Python, and shifts the focus directly to physics.Analyses written in ADL can be run on data using a runtime interpreter called CutLang, without the necessity of programming.ADL and CutLang are designed for use by anyone with an interest in, and/or knowledge of LHC physics, ranging from experimentalists and phenomenologists to non-professional enthusiasts.ADL/CutLang are originally designed for research, but are also equally intended for education and public use.This approach has already been employed to train undergraduate students with no programming experience in LHC analysis in two dedicated schools in Turkey and Vietnam, and is being adapted for use with LHC Open Data.Moreover, work is in progress towards piloting an educational module in particle physics data analysis for high school students and teachers.Here, we introduce ADL and CutLang and present the educational activities based on these practical tools.
DOI: 10.48550/arxiv.2204.03053
2022
Highlights on Supersymmetry and Exotic Searches at the LHC
The Run 2 data taking period of the Large Hadron Collider (LHC) at CERN in years 2015-2018 has presented a great opportunity to search for physics beyond the standard model (BSM). It will be followed by the Run 3 period starting in 2022, and by the High-Luminosity LHC (HL-LHC) era starting in late 2020s, where the latter promises an unprecedented wealth of physics prospects due to very high expected integrated luminosity and improved detector features. The ATLAS, CMS and LHCb experiments pursued a rich physics program in Run 2, and are already assessing the physics expectations at the HL-LHC era. This report presents highlights from recent search results and HL-LHC studies on BSM physics by the ATLAS, CMS and LHCb experiments. Examples will be shown from model-independent generic searches, searches for supersymmetry, extended Higgs sectors, and new exotic fermions and bosons.
DOI: 10.48550/arxiv.2203.13302
2022
Democratizing LHC Data Analysis with ADL/CutLang
Data analysis at the LHC has a very steep learning curve, which erects a formidable barrier between data and anyone who wishes to analyze data, either to study an idea or to simply understand how data analysis is performed. To make analysis more accessible, we designed the so-called Analysis Description Language (ADL), a domain specific language capable of describing the contents of an LHC analysis in a standard and unambiguous way, independent of any computing frameworks. ADL has an English-like highly human-readable syntax and directly employs concepts relevant to HEP. Therefore it eliminates the need to learn complex analysis frameworks written based on general purpose languages such as C++ or Python, and shifts the focus directly to physics. Analyses written in ADL can be run on data using a runtime interpreter called CutLang, without the necessity of programming. ADL and CutLang are designed for use by anyone with an interest in, and/or knowledge of LHC physics, ranging from experimentalists and phenomenologists to non-professional enthusiasts. ADL/CutLang are originally designed for research, but are also equally intended for education and public use. This approach has already been employed to train undergraduate students with no programming experience in LHC analysis in two dedicated schools in Turkey and Vietnam, and is being adapted for use with LHC Open Data. Moreover, work is in progress towards piloting an educational module in particle physics data analysis for high school students and teachers. Here, we introduce ADL and CutLang and present the educational activities based on these practical tools.
DOI: 10.48550/arxiv.2212.04889
2022
Second Analysis Ecosystem Workshop Report
The second workshop on the HEP Analysis Ecosystem took place 23-25 May 2022 at IJCLab in Orsay, to look at progress and continuing challenges in scaling up HEP analysis to meet the needs of HL-LHC and DUNE, as well as the very pressing needs of LHC Run 3 analysis. The workshop was themed around six particular topics, which were felt to capture key questions, opportunities and challenges. Each topic arranged a plenary session introduction, often with speakers summarising the state-of-the art and the next steps for analysis. This was then followed by parallel sessions, which were much more discussion focused, and where attendees could grapple with the challenges and propose solutions that could be tried. Where there was significant overlap between topics, a joint discussion between them was arranged. In the weeks following the workshop the session conveners wrote this document, which is a summary of the main discussions, the key points raised and the conclusions and outcomes. The document was circulated amongst the participants for comments before being finalised here.
DOI: 10.5281/zenodo.7418264
2022
HSF IRIS-HEP Second Analysis Ecosystem Workshop Report
2007
The 4th concept detector for the international linear collider
The 4th Concept detector presently being designed for the International Linear Collider introduces several innovations in order to achieve the necessary experimental goal of a detecter that is 2-to-10 times better than the already excellent SLC and LEP detectors. We introduce a dual-readout calorimeter system, a cluster counting drift chamber, and a second solenoid to return the magnetic flux without iron. We discuss particle identification, momentum and energy resolutions, and the machine-detector interface that together offer the possibility of a very high-performance detector for e + e physics up to p s = 1 TeV.
2019
Beyond the Standard Model Physics at the High Luminosity LHC
The High-Luminosity Large Hadron Collider (HL-LHC) is expected to deliver an integrated luminosity of up to 3000 fb$^{-1}$. The very high instantaneous luminosity will lead to about 200 proton-proton collisions per bunch crossing (pileup) superimposed to each event of interest, thus providing extremely challenging experimental conditions, which will be addressed by accompanying improvements in the decetors. The sensitivity to find new physics Beyond the Standard Model (BSM) is significantly improved and will allow to extend the reach for SUSY, heavy exotic resonances, vector like quarks, dark matter and exotic long-lived signatures, to name a few. This note summarizes several ATLAS and CMS studies performed to asses HL-LHC sensitivity to various BSM models and signatures.
DOI: 10.22323/1.340.0283
2019
Beyond the Standard Model Physics at the High Luminosity LHC
The High-Luminosity Large Hadron Collider (HL-LHC) is expected to deliver an integrated luminosity of up to 3000 fb$^{-1}$. The very high instantaneous luminosity will lead to about 200 proton-proton collisions per bunch crossing (pileup) superimposed to each event of interest, thus providing extremely challenging experimental conditions, which will be addressed by accompanying improvements in the decetors. The sensitivity to find new physics Beyond the Standard Model (BSM) is significantly improved and will allow to extend the reach for SUSY, heavy exotic resonances, vector like quarks, dark matter and exotic long-lived signatures, to name a few. This note summarizes several ATLAS and CMS studies performed to asses HL-LHC sensitivity to various BSM models and signatures.
DOI: 10.48550/arxiv.1910.00117
2019
Confronting minimal freeze-in models with the LHC
We present a class of dark matter models, in which the dark matter particle is a feebly interacting massive particle (FIMP) produced via the decay of an electrically charged and/or colored parent particle. Given the feeble interaction, dark matter is produced via the freeze-in mechanism and the parent particle is long-lived. The latter leads to interesting collider signatures. We study current LHC constrains on our models arising from searches for heavy charged particles, disappearing tracks, displaced leptons and displaced vertices. We demonstrate not only that collider searches can be a powerful probe of the freeze-in dark matter models under consideration, but that an observation can lead as well to interesting insights on the reheating temperature and thus on the validity of certain baryogenesis models.
2019
Beyond the Standard Model Physics at the High Luminosity LHC
The High-Luminosity Large Hadron Collider (HL-LHC) is expected to deliver an integrated luminosity of up to 3000 fb$^{-1}$. The very high instantaneous luminosity will lead to about 200 proton-proton collisions per bunch crossing (pileup) superimposed to each event of interest, thus providing extremely challenging experimental conditions, which will be addressed by accompanying improvements in the decetors. The sensitivity to find new physics Beyond the Standard Model (BSM) is significantly improved and will allow to extend the reach for SUSY, heavy exotic resonances, vector like quarks, dark matter and exotic long-lived signatures, to name a few. This note summarizes several ATLAS and CMS studies performed to asses HL-LHC sensitivity to various BSM models and signatures.
2020
Analysis Description Languages for the LHC.
An analysis description language is a domain specific language capable of describing the contents of an LHC analysis in a standard and unambiguous way, independent of any computing framework. It is designed for use by anyone with an interest in, and knowledge of, LHC physics, i.e., experimentalists, phenomenologists and other enthusiasts. Adopting analysis description languages would bring numerous benefits for the LHC experimental and phenomenological communities ranging from analysis preservation beyond the lifetimes of experiments or analysis software to facilitating the abstraction, design, visualization, validation, combination, reproduction, interpretation and overall communication of the analysis contents. Here, we introduce the analysis description language concept and summarize the current efforts ongoing to develop such languages and tools to use them in LHC analyses.
DOI: 10.48550/arxiv.2011.01950
2020
Analysis Description Languages for the LHC
An analysis description language is a domain specific language capable of describing the contents of an LHC analysis in a standard and unambiguous way, independent of any computing framework. It is designed for use by anyone with an interest in, and knowledge of, LHC physics, i.e., experimentalists, phenomenologists and other enthusiasts. Adopting analysis description languages would bring numerous benefits for the LHC experimental and phenomenological communities ranging from analysis preservation beyond the lifetimes of experiments or analysis software to facilitating the abstraction, design, visualization, validation, combination, reproduction, interpretation and overall communication of the analysis contents. Here, we introduce the analysis description language concept and summarize the current efforts ongoing to develop such languages and tools to use them in LHC analyses.
DOI: 10.48550/arxiv.1902.03942
2019
Beyond the Standard Model Physics at the High Luminosity LHC
The High-Luminosity Large Hadron Collider (HL-LHC) is expected to deliver an integrated luminosity of up to 3000 fb$^{-1}$. The very high instantaneous luminosity will lead to about 200 proton-proton collisions per bunch crossing (pileup) superimposed to each event of interest, thus providing extremely challenging experimental conditions, which will be addressed by accompanying improvements in the decetors. The sensitivity to find new physics Beyond the Standard Model (BSM) is significantly improved and will allow to extend the reach for SUSY, heavy exotic resonances, vector like quarks, dark matter and exotic long-lived signatures, to name a few. This note summarizes several ATLAS and CMS studies performed to asses HL-LHC sensitivity to various BSM models and signatures.
2006
Supplemental Proposal to the ALCPG and LCDRD Groups for the Comprehensive Study, Construction and Testing of Multiple Readout Calorimeters of the 4th Concept
DOI: 10.1140/epjc/s2004-02111-1
2005
Observing higher-dimensional black holes at the LHC
2021
Digging deeper into SUSY parameter space with the CMS experiment
The classic searches for supersymmetry have not given any strong indication for new physics. Therefore CMS is designing dedicated searches to target the more difficult and specific supersymmetry scenarios. This contribution present three such recent searches based on 13 TeV proton-proton collisions recorded with the CMS detector in 2016, 2017 and 2018: a search for heavy gluinos cascading via heavy next-to-lightest neutralino in final states with boosted Z bosons and missing transverse momentum; a search for compressed supersymmetry in final states with soft taus; and a search for compressed, long-lived charginos in hadronic final states with disappearing tracks.
DOI: 10.22323/1.390.0280
2021
Digging deeper into SUSY parameter space with the CMS experiment
The classic searches for supersymmetry have not given any strong indication for new physics.Therefore CMS is designing dedicated searches to target the more difficult and specific supersymmetry scenarios.This contribution present three such recent searches based on 13 TeV proton-proton collisions recorded with the CMS detector in 2016, 2017 and 2018: a search for heavy gluinos cascading via heavy next-to-lightest neutralino in final states with boosted Z bosons and missing transverse momentum; a search for compressed supersymmetry in final states with soft taus; and a search for compressed, long-lived charginos in hadronic final states with disappearing tracks.
DOI: 10.21468/scipost.report.2694
2021
Report on 2102.04377v1
Measurements at particle collider experiments, even if primarily aimed at understanding Standard Model processes, can have a high degree of model independence, and implicitly contain information about potential contributions from physics beyond the Standard Model.The Contur package allows users to benefit from the hundreds of measurements preserved in the Rivet library to test new models against the bank of LHC measurements to date.This method has proven to be very effective in several recent publications from the Contur team, but ultimately, for this approach to be successful, the authors believe that the Contur tool needs to be accessible to the wider high energy physics community.As such, this manual accompanies the first user-facing version: Contur v2.It describes the design choices that have been made, as well as detailing pitfalls and common issues to avoid.The authors hope that with the help of this documentation, external groups will be able to run their own Contur studies, for example when proposing a new model, or pitching a new search.
DOI: 10.1051/epjconf/202125103062
2021
Recent advances in ADL, CutLang and adl2tnm
This paper presents an overview and features of an Analysis Description Language (ADL) designed for HEP data analysis. ADL is a domain specific, declarative language that describes the physics content of an analysis in a standard and unambiguous way, independent of any computing frameworks. It also describes infrastructures that render ADL executable, namely CutLang, a direct runtime interpreter (originally also a language), and adl2tnm, a transpiler converting ADL into C++ code. In ADL, analyses are described in human readable plain text files, clearly separating object, variable and event selection definitions in blocks, with a syntax that includes mathematical and logical operations, comparison and optimisation operators, reducers, four-vector algebra and commonly used functions. Recent studies demonstrate that adapting the ADL approach has numerous benefits for the experimental and phenomenological HEP communities. These include facilitating the abstraction, design, optimization, visualization, validation, combination, reproduction, interpretation and overall communication of the analysis contents and long term preservation of the analyses beyond the lifetimes of experiments. Here we also discuss some of the current ADL applications in physics studies and future prospects based on static analysis and differentiable programming.
DOI: 10.21468/scipost.report.3866
2021
Report on 2105.14027v2
We describe the outcome of a data challenge conducted as part of the Dark Machines (https://www.darkmachines.org)initiative and the Les Houches 2019 workshop on Physics at TeV colliders.The challenged aims to detect signals of new physics at the Large Hadron Collider (LHC) using unsupervised machine learning algorithms.First, we propose how an anomaly score could be implemented to define model-independent signal regions in LHC searches.We define and describe a large benchmark dataset, consisting of > 1 billion simulated LHC events corresponding to 10 fb -1 of proton-proton collisions at a center-of-mass energy of 13 TeV.We then review a wide range of anomaly detection and density estimation algorithms, developed in the context of the data challenge, and we measure their performance in a set of realistic analysis environments.We draw a number of useful conclusions that will aid the development of unsupervised new physics searches during the third run of the LHC, and provide our benchmark dataset for future studies at https://www.phenoMLdata.org.
DOI: 10.48550/arxiv.2101.10888
2021
Digging deeper into SUSY parameter space with the CMS experiment
The classic searches for supersymmetry have not given any strong indication for new physics. Therefore CMS is designing dedicated searches to target the more difficult and specific supersymmetry scenarios. This contribution present three such recent searches based on 13 TeV proton-proton collisions recorded with the CMS detector in 2016, 2017 and 2018: a search for heavy gluinos cascading via heavy next-to-lightest neutralino in final states with boosted Z bosons and missing transverse momentum; a search for compressed supersymmetry in final states with soft taus; and a search for compressed, long-lived charginos in hadronic final states with disappearing tracks.