T. Dorigo

A precise determination of the energy scale of jets at the Collider Detector at Fermilab at the Tevatron pp¯ collider is described. Jets are used in many analyses to estimate the energies of partons resulting from the underlying physics process. Several correction factors are developed to estimate the original parton energy from the observed jet energy in the calorimeter. The jet energy response is compared between data and Monte Carlo simulation for various physics processes, and systematic uncertainties on the jet energy scale are determined. For jets with transverse momenta above 50 GeV the jet energy scale is determined with a 3% systematic uncertainty.

Abstract A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.

This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.

A bstract The unsupervised search for overdense regions in high-dimensional feature spaces, where locally high population densities may be associated with anomalous contaminations to an otherwise more uniform population, is of relevance to applications ranging from fundamental research to industrial use cases. Motivated by the specific needs of searches for new phenomena in particle collisions, we propose a novel approach that targets signals of interest populating compact regions of the feature space. The method consists in a systematic scan of subspaces of a standardized copula of the feature space, where the minimum p -value of a hypothesis test of local uniformity is sought by greedy descent. We characterize the performance of the proposed algorithm and show its effectiveness in several experimental situations.

For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at $\sqrt{s}=1800$ GeV and $\sqrt{s}=630$ GeV and comparing this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models. Two cones in $\eta$--$\phi$ space are defined, at the same pseudo-rapidity, $\eta$, as the jet with the highest transverse energy ($E_T^{(1)}$), and at $\pm 90^o$ in the azimuthal direction, $\phi$. The total charged track momentum inside each of the two cones is measured. The minimum momentum in the two cones is almost independent of $E_T^{(1)}$ and is similar to the momentum observed in minimum bias events, whereas the maximum momentum increases roughly linearly with the jet $E_T^{(1)}$ over most of the measured range. This study will help improve the precision of comparisons of jet cross section data and NLO perturbative QCD predictions. %this is new The distribution of the sum of the track momenta in the two cones is also examined for five different $E_T^{(1)}$ bins. The HERWIG and PYTHIA Monte Carlos are reasonably successful in describing the data, but neither can describe completely all of the event properties.

Since the beginning of 2020, the coronavirus disease (COVID-19) pandemic has dramatically influenced almost every aspect of human life. Activities requiring human gatherings have either been postponed, canceled, or held completely virtually. To supplement lack of in-person contact, people have increasingly turned to virtual settings online, advantages of which include increased inclusivity and accessibility and a reduced carbon footprint. However, emerging online technologies cannot fully replace in-person scientific events. In-person meetings are not susceptible to poor Internet connectivity problems, and they provide novel opportunities for socialization, creating new collaborations and sharing ideas. To continue such activities, a hybrid model for scientific events could be a solution offering both in-person and virtual components. While participants can freely choose the mode of their participation, virtual meetings would most benefit those who cannot attend in-person due to the limitations. In-person portions of meetings should be organized with full consideration of prevention and safety strategies, including risk assessment and mitigation, venue and environmental sanitation, participant protection and disease prevention, and promoting the hybrid model. This new way of interaction between scholars can be considered as a part of a resilience system, which was neglected previously and should become a part of routine practice in the scientific community.

hypothesis testing.

The full optimization of the design and operation of instruments whose functioning relies on the interaction of radiation with matter is a super-human task, due to the large dimensionality of the space of possible choices for geometry, detection technology, materials, data-acquisition, and information-extraction techniques, and the interdependence of the related parameters. On the other hand, massive potential gains in performance over standard, "experience-driven" layouts are in principle within our reach if an objective function fully aligned with the final goals of the instrument is maximized through a systematic search of the configuration space. The stochastic nature of the involved quantum processes make the modeling of these systems an intractable problem from a classical statistics point of view, yet the construction of a fully differentiable pipeline and the use of deep learning techniques may allow the simultaneous optimization of all design parameters. In this white paper, we lay down our plans for the design of a modular and versatile modeling tool for the end-to-end optimization of complex instruments for particle physics experiments as well as industrial and medical applications that share the detection of radiation as their basic ingredient. We consider a selected set of use cases to highlight the specific needs of different applications.

Complex computer simulations are commonly required for accurate data modelling in many scientific disciplines, making statistical inference challenging due to the intractability of the likelihood evaluation for the observed data. Furthermore, sometimes one is interested on inference drawn over a subset of the generative model parameters while taking into account model uncertainty or misspecification on the remaining nuisance parameters. In this work, we show how non-linear summary statistics can be constructed by minimising inference-motivated losses via stochastic gradient descent such they provided the smallest uncertainty for the parameters of interest. As a use case, the problem of confidence interval estimation for the mixture coefficient in a multi-dimensional two-component mixture model (i.e. signal vs background) is considered, where the proposed technique clearly outperforms summary statistics based on probabilistic classification, which are a commonly used alternative but do not account for the presence of nuisance parameters.

New physics theories often depend on a large number of free parameters. The phenomenology they predict for fundamental physics processes is in some cases drastically affected by the precise value of those free parameters, while in other cases is left basically invariant at the level of detail experimentally accessible. When designing a strategy for the analysis of experimental data in the search for a signal predicted by a new physics model, it appears advantageous to categorize the parameter space describing the model according to the corresponding kinematical features of the final state. A multi-dimensional test statistic can be used to gauge the degree of similarity in the kinematics predicted by different models; a clustering algorithm using that metric may allow the division of the space into homogeneous regions, each of which can be successfully represented by a benchmark point. Searches targeting those benchmarks are then guaranteed to be sensitive to a large area of the parameter space. In this document we show a practical implementation of the above strategy for the study of non-resonant production of Higgs boson pairs in the context of extensions of the standard model with anomalous couplings of the Higgs bosons. A non-standard value of those couplings may significantly enhance the Higgs boson pair-production cross section, such that the process could be detectable with the data that the LHC will collect in Run 2.

Computer science tools involving differentiable programming today enable the end-to-end modeling of the very complex instruments we develop for fundamental physics. A complete model of an experiment studying fundamental interactions usually involves a surrogate or parametric approximation of data-generating processes, along with models of detector layout, pattern recognition, and inference-extraction procedures. The resulting software pipeline enables the study of the dependence of a performance metric on detector-defining parameters and its maximization by stochastic gradient descent across the very large space of design options. The software may identify new design solutions, as well as indicate optimal compromises between cost and performance.

The optoelectronic devices play a crucial role in our daily lives by seamlessly integrating optics and electronics, enabling technologies like smartphones, solar cells, and optical communication. Solar cells have been very vital in terms of providing sustainable and clean energy. Conventional Perovskite-based solar cells possess limitations like stability and toxicity. Recently, ABO4-type materials have gained attention in optoelectronic devices due to their structural stability and suitable optoelectronic properties for solar cell applications. The structural, electronic, and optical properties of AgWO4 and PdWO4 have been explored using the first principal simulations in line with density functional theory (DFT) using WIEN2K simulation software. The Perdew-Burke-Ernzerhof Generalized-Gradient-Approximation (PBE-GGA) is acclimated to optimize the geometry of both materials under consideration. Trans-Balha modified Becke-Johnson approximation (TB-mBJ) approximation is implemented to study materials' optoelectronic properties. Structural analysis revealed the stable structure of AgWO4 and PdWO4 in the monoclinic phase with increasing lattice parameters and decreased unit cell volume upon replacement of Ag with Pd cation on the A site. Both materials ' negative values of ground state energies indicate the stability of both compounds. Upon analysis of the band structure of AgWO4 and PdWO4, it is found that both materials possess a band gap of 1.34eV and 0.73eV,respectively, signifying that both materials under consideration are semiconductors, with a potential for a controlled flow of electrical charges, coming up with promising various optoelectronic applications. Optical characteristics were explored and examined in depth in the framework of hypothetical dielectric constant. It has been discovered that the dielectric function has a broad span of energy integrity when it comes to its dielectric function. Materials with narrow bandgaps and excellent UV light absorption were found suitable for optoelectronic and solar cell applications.

An open scientific challenge is how to classify events with reliable measures of uncertainty, when we have a mechanistic model of the data-generating process but the distribution over both labels and latent nuisance parameters is different between train and target data. We refer to this type of distributional shift as generalized label shift (GLS). Direct classification using observed data $\mathbf{X}$ as covariates leads to biased predictions and invalid uncertainty estimates of labels $Y$. We overcome these biases by proposing a new method for robust uncertainty quantification that casts classification as a hypothesis testing problem under nuisance parameters. The key idea is to estimate the classifier's receiver operating characteristic (ROC) across the entire nuisance parameter space, which allows us to devise cutoffs that are invariant under GLS. Our method effectively endows a pre-trained classifier with domain adaptation capabilities and returns valid prediction sets while maintaining high power. We demonstrate its performance on two challenging scientific problems in biology and astroparticle physics with data from realistic mechanistic models.

During Run II, the Tevatron collider will operate with a 20-fold decrease of bunch crossing time and a similar increase of luminosity with respect to Run I: these new running conditions called for extensive improvements and extensions of the CDF muon system. The low light yield of aging scintillators has been effectively fixed by gluing light fibers to the long sides of these counters for added light output. The higher backgrounds of the Main Injector era will be suppressed by custom-shaped steel shielding structures. A new muon system has been developed to extend rapidity coverage up to |η|=1.5 with performances comparable to those of the central muon system. New front-end electronics will handle the reduced gas gain set in the central muon system. Several mechanical problems have been solved to allow the completion of azimuthal coverage.

We use a neural-network technique to search for standard model single-top-quark production in the $106{\mathrm{pb}}^{\ensuremath{-}1}$ dataset accumulated by the Collider Detector at Fermilab detector during the 1992--1995 collider run (``run I''). Using a sample of 64 $W+1,$ 2, 3 jets events, we set a 95% confidence level upper limit of 24 pb on the W-gluon and ${W}^{*}$ combined single-top cross section.

We present a measurement of the isolated direct photon cross section in p-pbar collisions at sqrt(s) = 1.8 TeV and |eta| < 0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two-track event signature. To remove pi0 -> gamma gamma and eta -> gamma gamma events we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of pT is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements.

We have measured the azimuthal angular correlation of $b\overline{b}$ production, using $86.5\text{ }\text{ }\mathrm{p}{\mathrm{b}}^{\ensuremath{-}1}$ of data collected by Collider Detector at Fermilab (CDF) in $p\overline{p}$ collisions at $\sqrt{s}=1.8\text{ }\text{ }\mathrm{TeV}$ during 1994--1995. In high-energy $p\overline{p}$ collisions, such as at the Tevatron, $b\overline{b}$ production can be schematically categorized into three mechanisms. The leading-order (LO) process is ``flavor creation,'' where both $b$ and $\overline{b}$ quarks substantially participate in the hard scattering and result in a distinct back-to-back signal in final state. The ``flavor excitation'' and the ``gluon splitting'' processes, which appear at next-leading-order (NLO), are known to make a comparable contribution to total $b\overline{b}$ cross section, while providing very different opening angle distributions from the LO process. An azimuthal opening angle between bottom and antibottom, $\ensuremath{\Delta}\ensuremath{\phi}$, has been used for the correlation measurement to probe the interaction creating $b\overline{b}$ pairs. The $\ensuremath{\Delta}\ensuremath{\phi}$ distribution has been obtained from two different methods. One method measures the $\ensuremath{\Delta}\ensuremath{\phi}$ between bottom hadrons using events with two reconstructed secondary vertex tags. The other method uses $b\overline{b}\ensuremath{\rightarrow}(J/\ensuremath{\psi}X)(\ensuremath{\ell}{X}^{\ensuremath{'}})$ events, where the charged lepton ($\ensuremath{\ell}$) is an electron ($e$) or a muon ($\ensuremath{\mu}$), to measure $\ensuremath{\Delta}\ensuremath{\phi}$ between bottom quarks. The $b\overline{b}$ purity is determined as a function of $\ensuremath{\Delta}\ensuremath{\phi}$ by fitting the decay length of the $J/\ensuremath{\psi}$ and the impact parameter of the $\ensuremath{\ell}$. Both methods quantify the contribution from higher-order production mechanisms by the fraction of the $b\overline{b}$ pairs produced in the same azimuthal hemisphere, ${f}_{\mathrm{toward}}$. The measured ${f}_{\mathrm{toward}}$ values are consistent with both parton shower Monte Carlo and NLO QCD predictions.

The polarization of the $W$ boson in $t\ensuremath{\rightarrow}Wb$ decay is unambiguously predicted by the standard model of electroweak interactions and is a powerful test of our understanding of the $tbW$ vertex. We measure this polarization from the invariant mass of the $b$ quark from $t\ensuremath{\rightarrow}Wb$ and the lepton from $W\ensuremath{\rightarrow}l\ensuremath{\nu}$ whose momenta measure the $W$ decay angle and direction of motion, respectively. In this paper we present a measurement of the decay rate (${f}_{V+A}$) of the $W$ produced from the decay of the top quark in the hypothesis of $\mathrm{V}+\mathrm{A}$ structure of the $tWb$ vertex. We find no evidence for the nonstandard $\mathrm{V}+\mathrm{A}$ vertex and set a limit on ${f}_{V+A}$ $&lt;$ 0.80 at $95%$ confidence level. By combining this result with a complementary observable in the same data, we assign a limit on ${f}_{V+A}$ $&lt;$ 0.61 at $95%$ CL. This corresponds to a constraint on the right-handed helicity component of the W polarization of ${f}_{+}&lt;0.18$ at $95%$ CL. This limit is the first significant direct constraint on ${f}_{V+A}$ in top decay.

We present a study of the production of ${K}_{S}^{0}$ and ${\ensuremath{\Lambda}}^{0}$ in inelastic $p\overline{p}$ collisions at $\sqrt{s}=1800$ and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of ${K}_{S}^{0}$ and ${\ensuremath{\Lambda}}^{0}$ multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and $⟨{p}_{T}⟩$ of ${K}_{S}^{0}$ and ${\ensuremath{\Lambda}}^{0}$ on charged particle multiplicity, are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The ${p}_{T}$ distributions extend above $8\text{ }\text{ }\mathrm{GeV}/c$, showing a $⟨{p}_{T}⟩$ higher than previous measurements. The dependence of the mean ${K}_{S}^{0}({\ensuremath{\Lambda}}^{0})$ ${p}_{T}$ on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.

The design of instruments that rely on the interaction of radiation with matter for their operation is a quite complex task if our goal is to achieve near optimality on some well-defined utility fu...

Scientific collaboration has been a critical aspect of the development of all fields of science, particularly clinical medicine. It is well understood that myriads of benefits can be yielded by interdisciplinary and international collaboration. For instance, our rapidly growing knowledge on COVID-19 and vaccine development could not be attained without expanded collaborative activities. However, achieving fruitful results requires mastering specific tactics in collaborative efforts. These activities can enhance our knowledge, which ultimately benefits society. In addition to tackling the issue of the invisible border between different countries, institutes, and disciplines, the border between the scientific community and society needs to be addressed as well. International and transdisciplinary approaches can potentially be the best solution for bridging science and society. The Universal Scientific Education and Research Network (USERN) is a non-governmental, non-profit organization and network to promote professional, scientific research and education worldwide. The fifth annual congress of USERN was held in Tehran, Iran, in a hybrid manner on November 7-10, 2020, with key aims of bridging science to society and facilitating borderless science. Among speakers of the congress, a group of top scientists unanimously agreed on The USERN 2020 consensus, which is drafted with the goal of connecting society with scientific scholars and facilitating international and interdisciplinary scientific activities in all fields, including clinical medicine.

The search for Higgs bosons in both the standard model and its extensions is well under way at the Tevatron. As the integrated luminosity collected increases into the multiple inverse femptobarn range, these searches are becoming very interesting indeed. Meanwhile, the construction of the Large Hadron Collider (LHC) and its associated experiments at CERN are nearing completion. In this TeV4LHC workshop, it was realized that any experience at the Tevatron with respect to backgrounds, experimental techniques and theoretical calculations that can be verified at the Tevatron which have relevance for future measurements at the LHC were important. Studies and contributions to these efforts were made in three broad categories: theoretical calculations of Higgs production and decay mechanisms; theoretical calculations and discussions pertaining to non-standard model Higgs bosons; and experimental reviews, analyses and developments at both the Tevatron and the upcoming LHC experiments. All of these contributions represent real progress towards the elucidation of the mechanism of electroweak symmetry breaking.

This review covers results of searches for new elementary particles that decay into boson pairs (dibosons), performed at the CERN Large Hadron Collider in proton–proton collision data collected by the ATLAS and CMS experiments at 7-, 8-, and 13-TeV center-of-mass energy until the year 2017. The available experimental results of the analysis of final states including most of the possible two-object combinations of W and Z bosons, photons, Higgs bosons, and gluons place stringent constraints on a variety of theoretical ideas that extend the standard model, pushing into the multi-TeV region the scale of allowed new physics phenomena.

Abstract The performance demands of future particle-physics experiments investigating the high-energy frontier pose a number of new challenges, forcing us to find improved solutions for the detection, identification, and measurement of final-state particles in subnuclear collisions. One such challenge is the precise measurement of muon momentum at very high energy, where an estimate of the curvature provided by conceivable magnetic fields in realistic detectors proves insufficient for achieving good momentum resolution when detecting, e.g., a narrow, high mass resonance decaying to a muon pair. In this work we study the feasibility of an entirely new avenue for the measurement of the energy of muons based on their radiative losses in a dense, finely segmented calorimeter. This is made possible by exploiting spatial information of the clusters of energy from radiated photons in a regression task. The use of a task-specific deep learning architecture based on convolutional layers allows us to treat the problem as one akin to image reconstruction, where images are constituted by the pattern of energy released in successive layers of the calorimeter. A measurement of muon energy with better than 20% relative resolution is shown to be achievable for ultra-TeV muons.

In the path towards a muon collider with center of mass energy of 10 TeV or more, a stage at 3 TeV emerges as an appealing option. Reviewing the physics potential of such muon collider is the main purpose of this document. In order to outline the progression of the physics performances across the stages, a few sensitivity projections for higher energy are also presented. There are many opportunities for probing new physics at a 3 TeV muon collider. Some of them are in common with the extensively documented physics case of the CLIC 3 TeV energy stage, and include measuring the Higgs trilinear coupling and testing the possible composite nature of the Higgs boson and of the top quark at the 20 TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stem from the fact that muons are collided rather than electrons. This is exemplified by studying the potential to explore the microscopic origin of the current $g$-2 and $B$-physics anomalies, which are both related with muons.

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.

Scientometrics and bibliometrics, the subfields of library and information science, deal with the quantity and quality of research outputs. Currently, various scientometric indices are being used to quantify and compare research outputs. The most widely known is the h-index. However, this index and its derivatives suffer from dependence on the mere count of a scholar's highly cited publications. To remedy this deficiency, we developed a novel index, the Universal Research Index (UR-Index) (https://usern2021.github.io/UR-Index/) by which every single publication has its own impact on the total score. We developed this index by surveying international top 1 % cited scientists in various disciplines and included additional component variables such as publication type, leading role of a scholar, co-author count, and source metrics to this scientometric index. We acknowledge that unconscious biases built into the component variables included in the UR-Index might put research from specific groups at a disadvantage, thus continued efforts to improve equitable scholarly impact in science and academia are encouraged.

The energy measurement of jets produced by b-quarks at hadron colliders suffers from biases due to the peculiarities of the hadronization and decay of the originating B hadron. The impact of these effects can be estimated by reconstructing the mass of Z boson decays into pairs of b-quark jets. From a sample of 584 pb-1 of data collected by the CDF experiment in 1.96 TeV proton-antiproton collisions at the Tevatron collider, we show how the Z signal can be identified and measured. Using the reconstructed mass of Z candidates we determine a jet energy scale factor for b-quark jets with a precision better than 2%. This measurement allows a reduction of one of the dominant source of uncertainty in analyses based on high transverse momentum b-quark jets. We also determine, as a cross-check of our analysis, the Z boson cross section in hadronic collisions using the b-bbar final state as sigma x B(Z-&gt;b-bbar) = 1578 +636 -410 pb.

We present a detailed examination of the heavy flavor properties of jets produced at the Fermilab Tevatron collider. The data set, collected with the Collider Detector at Fermilab, consists of events with two or more jets with transverse energy ET>~15GeV and pseudorapidity |η|<~1.5. The heavy flavor content of the data set is enriched by requiring that at least one of the jets (lepton-jet) contains a lepton with a transverse momentum larger than 8GeV/c. Jets containing hadrons with heavy flavor are selected via the identification of secondary vertices. The parton-level cross sections predicted by the HERWIG Monte Carlo generator program are tuned within theoretical and experimental uncertainties to reproduce the secondary-vertex rates in the data. The tuned simulation provides new information on the origin of the discrepancy between the bb¯ cross section measurements at the Tevatron and the next-to-leading order QCD prediction. We also compare the rate of away-jets (jets recoiling against the lepton-jet) containing a soft lepton (pT>~2GeV/c) in the data to that in the tuned simulation. We find that this rate is larger than what is expected for the conventional production and semileptonic decay of pairs of hadrons with heavy flavor.Received 2 December 2003DOI:https://doi.org/10.1103/PhysRevD.69.072004©2004 American Physical Society

We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, ${N}_{q}$ and ${N}_{g}$, produced at the Fermilab Tevatron in $p\overline{p}$ collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of ${\ensuremath{\theta}}_{c}=0.28$, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness $Q={E}_{\mathrm{jet}}{\ensuremath{\theta}}_{c}$ varies in the range from 12 to 25 GeV. At $Q=19.2\text{ }\text{ }\mathrm{GeV}$, the ratio of multiplicities $r={N}_{g}/{N}_{q}$ is found to be $1.64\ifmmode\pm\else\textpm\fi{}0.17$, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations.

We present a new search for ${H}^{0}V$ production, where ${H}^{0}$ is a scalar Higgs boson decaying into $b\overline{b}$ with branching ratio $\ensuremath{\beta}$, and $V$ is a ${Z}^{0}$ boson decaying into ${e}^{+}{e}^{\ensuremath{-}}$, ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, or $\ensuremath{\nu}\overline{\ensuremath{\nu}}$. This search is then combined with previous searches for ${H}^{0}V$ where $V$ is a ${W}^{\ifmmode\pm\else\textpm\fi{}}$ boson or a hadronically decaying ${Z}^{0}$. The data sample consists of $106\ifmmode\pm\else\textpm\fi{}4\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.8\text{ }\text{ }\mathrm{TeV}$ accumulated by the Collider Detector at Fermilab. Observing no evidence of a signal, we set 95% Bayesian credibility level upper limits on $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}{H}^{0}V)\ifmmode\times\else\texttimes\fi{}\ensuremath{\beta}$. For ${H}^{0}$ masses of 90, 110, and $130\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, the limits are 7.8, 7.2, and 6.6 pb, respectively.

We present the first measurement of the A_2 and A_3 angular coefficients of the W boson produced in proton-antiproton collisions. We study W-> e+nu and W-> mu+nu candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at sqrt(s)=1.8 TeV. The corresponding integrated luminosity was 110 pb^-1. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the Standard Model prediction, up to order alpha_s^2 in QCD.

We present a measurement of the coefficient alpha_2 of the leptonic polar-angle distribution from W boson decays, as a function of the W transverse momentum. The measurement uses an 80+/-4 pb^{-1} sample of proton-antiproton collisions at sqrt{s}=1.8 TeV collected by the CDF detector and includes data from both the W->e+nu and W->mu+nu decay channels. We fit the W boson transverse mass distribution to a set of templates from a Monte Carlo event generator and detector simulation in several ranges of the W transverse momentum. The measurement agrees with the Standard Model expectation, whereby the ratio of longitudinally to transversely polarized W bosons, in the Collins-Soper W rest frame, increases with the W transverse momentum at a rate of approximately 15% per 10 GeV/c.

The five-standard-deviation threshold is an established standard for discovery claims in experimental particle physics; however, the criterion is an ad-hoc recipe with no solid foundations. In this report I discuss its origins and the issues it was designed to address, pointing out its shortcomings and the need for a more flexible approach to decide when a new observed effect should be taken seriously.

The full optimization of the design and operation of instruments whose functioning relies on the interaction of radiation with matter is a super-human task, given the large dimensionality of the space of possible choices for geometry, detection technology, materials, data-acquisition, and information-extraction techniques, and the interdependence of the related parameters. On the other hand, massive potential gains in performance over standard, "experience-driven" layouts are in principle within our reach if an objective function fully aligned with the final goals of the instrument is maximized by means of a systematic search of the configuration space. The stochastic nature of the involved quantum processes make the modeling of these systems an intractable problem from a classical statistics point of view, yet the construction of a fully differentiable pipeline and the use of deep learning techniques may allow the simultaneous optimization of all design parameters. In this document we lay down our plans for the design of a modular and versatile modeling tool for the end-to-end optimization of complex instruments for particle physics experiments as well as industrial and medical applications that share the detection of radiation as their basic ingredient. We consider a selected set of use cases to highlight the specific needs of different applications.

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with pT > 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV pp collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63(+0.84)(-0.07) events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity (tanbeta = 3) model.

A search for the direct production of Higgs bosons in the di-tau decay mode is performed with 86.3±3.5 pb−1 of data collected with the Collider Detector at Fermilab during the 1994–1995 data taking period of the Tevatron. We search for events where one tau decays to an electron plus neutrinos and the other tau decays hadronically. We perform a counting experiment and set limits on the cross section for supersymmetric Higgs boson production where tanβ is large and mA is small. For a benchmark parameter space point where mA0=100 GeV/c2 and tanβ=50, we limit the production cross section multiplied by the branching ratio to be less than 77.9 pb at the 95% confidence level compared to the theoretically predicted value of 11.0 pb. This is the first search for Higgs bosons decaying to tau pairs at a hadron collider.5 MoreReceived 13 June 2005DOI:https://doi.org/10.1103/PhysRevD.72.072004©2005 American Physical Society

This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.

A high-statistics determination of the differential cross section of elastic muon-electron scattering as a function of the transferred four-momentum squared, dσel(μe→μe)/dq2, has been argued to provide an effective constraint to the hadronic contribution to the running of the fine-structure constant, Δαhad, a crucial input for precise theoretical predictions of the anomalous magnetic moment of the muon. An experiment called ‘‘MUonE’’ is being planned at the north area of CERN for that purpose. We consider the geometry of the detector proposed by the MUonE collaboration and offer a few suggestions on the layout of the passive target material and on the placement of silicon strip sensors, based on a fast simulation of elastic muon-electron scattering events and the investigation of a number of possible solutions for the detector geometry. The employed methodology for detector optimization is of general interest as it may be applied to the design of task-specific detectors for high-energy physics, nuclear physics, and astro-particle physics applications.

We report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDF II detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction.

Abstract With the increasing shift from STEM to STEAM education, arts-based approaches to science teaching and learning are considered promising for aligning school science curricula with the development of twenty-first century skills, including creativity. Yet the impact of STEAM practices on student creativity and specifically on how the latter is associated with science learning outcomes have thus far received scarce empirical support. This paper contributes to this line of research by reporting on a two-wave quantitative study that examines the effect of a long-term STEAM intervention on two cognitive processes associated with creativity (act, flow) and their interrelationships with intrinsic and extrinsic components of science motivation. Using pre- and post-survey data from 175 high-school students in Italy, results show an overall positive effect of the intervention both on the act subscale of creativity and science career motivation, whereas a negative effect is found on self-efficacy. Gender differences in the above effects are also observed. Further, results provide support for the mediating role of self-efficacy in the relationship between creativity and science career motivation. Implications for the design of STEAM learning environments are discussed.

The subsystems of the CMS silicon strip tracker were integrated and commissioned at the Tracker Integration Facility (TIF) in the period from November 2006 to July 2007. As part of the commissioning, large samples of cosmic ray data were recorded under various running conditions in the absence of a magnetic field. Cosmic rays detected by scintillation counters were used to trigger the readout of up to 15\,\% of the final silicon strip detector, and over 4.7~million events were recorded. This document describes the cosmic track reconstruction and presents results on the performance of track and hit reconstruction as from dedicated analyses.

We have investigated the invariant mass spectrum of dimuons collected by the CDF experiment during the 1992--1995 run of the Fermilab Tevatron collider to improve the limit on the existence of narrow resonances set by the experiments at the SPEAR ${e}^{+}{e}^{\ensuremath{-}}$ collider. In the mass range $6.3\ensuremath{-}9.0\text{ }\text{ }\mathrm{GeV}/{\mathrm{c}}^{2}$, we derive 90% upper credible limits to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the $\ensuremath{\Upsilon}(1S)$ meson. In this mass range, the average limit varies from 1.7 to 0.5%. This limit is much worse at the mass of $7.2\text{ }\text{ }\mathrm{GeV}/{\mathrm{c}}^{2}$ due to an excess of $250\ifmmode\pm\else\textpm\fi{}61$ events with a width consistent with the detector resolution.

Between the years 2015 and 2019, members of the Horizon 2020-funded Innovative Training Network named "AMVA4NewPhysics" studied the customization and application of advanced multivariate analysis methods and statistical learning tools to high-energy physics problems, as well as developed entirely new ones. Many of those methods were successfully used to improve the sensitivity of data analyses performed by the ATLAS and CMS experiments at the CERN Large Hadron Collider; several others, still in the testing phase, promise to further improve the precision of measurements of fundamental physics parameters and the reach of searches for new phenomena. In this paper, the most relevant new tools, among those studied and developed, are presented along with the evaluation of their performances.

The properties of three-jet events with total transverse energy greater than 320 GeV and individual jet energy greater than 20 GeV have been analyzed and compared to absolute predictions from a next-to-leading order (NLO) perturbative QCD calculation. These data, of integrated luminosity 86 pb^-1, were recorded by the CDF Experiment for proton-antiproton collisions at sqrt{s}=1.8 TeV. This study tests a model of higher order QCD processes that result in gluon emission and can be used to estimate the magnitude of the contribution of processes higher than NLO. The total cross section is measured to be 466 +/- 3(stat.)^{+207}_{-70}(syst.) pb. The differential cross section is furthermore measured for all kinematically accessible regions of the Dalitz plane, including those for which the theoretical prediction is unreliable. While the measured cross section is consistent with the theoretical prediction in magnitude, the two differ somewhat in shape in the Dalitz plane.

A proposal for a pixel-based Level 1 trigger for the Super-LHC is presented. The trigger is based on fast track reconstruction using the full pixel granularity exploiting a readout which connects different layers in specific trigger towers. The trigger will implement the current CMS high level trigger functionality in a novel concept of intelligent detector. A possible layout is discussed and implications on data links are evaluated.

In recent years novel inference techniques have been developed based on the construction of non-linear summary statistics with neural networks by minimising inferencemotivated losses. One such technique is inferno (P. de Castro and T. Dorigo, Comp. Phys. Comm. 244 (2019) 170) which was shown on toy problems to outperform classical summary statistics for the problem of confidence interval estimation in the presence of nuisance parameters. In order to test and benchmark the algorithm in a real world application, a full, systematics-dominated analysis produced by the CMS experiment, "Measurement of the top-antitop production cross section in the tau+jets channel in pp collisions at sqrt(s) = 7 TeV" (CMS Collaboration, The European Physical Journal C, 2013) is reproduced with CMS Open Data. The application of the inferno-powered neural network architecture to this analysis demonstrates the potential to reduce the impact of systematic uncertainties in real LHC analyses. This work also exemplifies the extent to which LHC analyses can be reproduced with open data.

The recent discovery of PeV gamma-ray emission especially from the LHAASO observatory, located in the Northern hemisphere, boosted the relevance of observing the Southern sky at such energies.SWGO (Southern Wide-Field Gamma-Ray Observatory) is the largest proposed detector with sensitivity in the 100 TeV-1 PeV energy range.The baseline SWGO idea is a km 2 array of water tanks to be placed above 4,400 m a.s.l. in the Andes, South America.In this contribution, we have studied the particle content and the morphology of Extensive Air Showers (EAS) generated by photons and protons in the 0.1 to 10 PeV energy range.We have simulated over 10 6 gamma-rays and proton induced showers respectively with primary energy in the 0.1-10 PeV energy range.We also show the particle distribution at ground, the lateral profile, the muon content and the average particle properties at ground.

We describe a software package, TomOpt, developed to optimise the geometrical layout and specifications of detectors designed for tomography by scattering of cosmic-ray muons. The software exploits differentiable programming for the modeling of muon interactions with detectors and scanned volumes, the inference of volume properties, and the optimisation cycle performing the loss minimisation. In doing so, we provide the first demonstration of end-to-end-differentiable and inference-aware optimisation of particle physics instruments. We study the performance of the software on a relevant benchmark scenarios and discuss its potential applications.

In this document we describe a model of an array of water Cherenkov detectors proposed to study ultra-high-energy gamma rays in the southern hemisphere, and a continuous model of secondary particles produced on the ground from gamma and proton showers. We use the model of the detector and the parametrization of showers for the identification of the most promising configuration of detector elements, using a likelihood ratio test statistic to classify showers and a stochastic gradient descent technique to maximize a utility function describing the measurement precision on the gamma-ray flux.

In this article we examine recent developments in the research area concerning the creation of end-to-end models for the complete optimization of measuring instruments. The models we consider rely on differentiable programming methods and on the specification of a software pipeline including all factors impacting performance -- from the data-generating processes to their reconstruction and the extraction of inference on the parameters of interest of a measuring instrument -- along with the careful specification of a utility function well aligned with the end goals of the experiment. Building on previous studies originated within the MODE Collaboration, we focus specifically on applications involving instruments for particle physics experimentation, as well as industrial and medical applications that share the detection of radiation as their data-generating mechanism.

This 5-day workshop, taught by renowned CERN physicist Tommaso Dorigo, is designed to equip PhD students, professors, and professional researchers with the skills to apply optimal statistical methods in any scientific field. The workshop covers the crucial topics necessary for researchers to avoid typical mistakes in statistical analysis and produce effective statistical inference, enabling you to extract more information from the same data than your peers. The course also provides an introduction to machine learning, offering a solid foundation in powerful statistical methods for all disciplines. An official Instats certificate of completion and 2 ECTS Equivalent points are provided at the conclusion of the workshop.

In this introductory seminar, attendees will learn about the importance of correct statistical practice in the quantitative analysis of complex data with a few examples. The seminar will describe in detail the contents of the full workshop on the same topic, which will be offered in January/February 2024 by the author on the instats platform.

For data sets populated by a very well modeled process and by another process of unknown probability density function (PDF), a desired feature when manipulating the fraction of the unknown process (either for enhancing it or suppressing it) consists in avoiding to modify the kinematic distributions of the well modeled one. A bootstrap technique is used to identify sub-samples rich in the well modeled process, and classify each event according to the frequency of it being part of such sub-samples. Comparisons with general MVA algorithms will be shown, as well as a study of the asymptotic properties of the method, making use of a public domain data set that models a typical search for new physics as performed at hadronic colliders such as the Large Hadron Collider (LHC).

Received 25 February 2005DOI:https://doi.org/10.1103/PhysRevD.71.059901©2005 American Physical Society

In this work we discuss the impact of nuisance parameters on the effectiveness of machine learning in high-energy physics problems, and provide a review of techniques that allow to include their effect and reduce their impact in the search for optimal selection criteria and variable transformations. The introduction of nuisance parameters complicates the supervised learning task and its correspondence with the data analysis goal, due to their contribution degrading the model performances in real data, and the necessary addition of uncertainties in the resulting statistical inference. The approaches discussed include nuisance-parameterized models, modified or adversary losses, semi-supervised learning approaches, and inference-aware techniques.

In this document we study the effect of anomalous Higgs boson couplings on non-resonant pair production of Higgs bosons ($HH$) at the LHC. We explore the space of the five parameters $\kappa_{\lambda}$, $\kappa_{t}$, $c_2$, $c_g$, and $c_{2g}$ in terms of the corresponding kinematics of the final state, and describe a partition of the space into a limited number of regions featuring similar phenomenology in the kinematics of $HH$ final state. We call clusters the sets of points belonging to the same region; to each cluster corresponds a representative point which we call a benchmark. We discuss a possible technique to estimate the sensitivity of an experimental search to the kinematical differences between the phenomenology of the benchmark points and the rest of the parameter space contained in the corresponding cluster. We also provide an analytical parametrization of the cross-section modifications that the variation of anomalous couplings produces with respect to standard model $HH$ production along with a recipe to translate the results into other parameter-space bases. Finally, we provide a preliminary analysis of variations in the topology of the final state within each region based on recent LHC results.

A novel method is proposed here to precisely model the multi-dimensional features of QCD multi-jet events in hadron collisions. The method relies on the schematization of high-$p_T$ QCD processes as $2 \to 2$ reactions made complex by sub-leading effects. The construction of libraries of hemispheres from experimental data and the definition of a suitable nearest-neighbor-based association map allow for the generation of artificial events that reproduce with surprising accuracy the kinematics of the QCD component of original data, while remaining insensitive to small signal contaminations. The method is succinctly described and its performance is tested in the case of the search for the $\rm{hh \to b \bar b b \bar b}$ process at the LHC.

This report discusses physics issues which can be addressed in photon and weak boson production in Run II at the Tevatron. The current understanding and the potential of Run II to expand our knowledge of direct photon production in hadronic collisions is discussed. We explore the prospects for using the W-boson cross section to measure the integrated luminosity, improving the measurement of the W and Z boson transverse momentum distributions, the Z -&gt; b\bar b signal, and the lepton angular distribution in W decays. Finally, we consider the prospects for measuring the trilinear gauge boson couplings in Run II.

The D0 and CDF collaborations recently published two independent analyses that both claim to represent the observation of the Omega_b particle, a baryon made up by a (bss) quark combination. Both signals are estimated to exceed the statistical significance of five standard deviations; however, the mass measurements derived from the candidates differ by over six standard deviations, accounting for estimated systematics. Measured rates also appear to differ, although they remain compatible within the large uncertainties. In this paper the author recomputes the significance of the D0 result, showing that it was considerably overestimated in the original publication; he then investigates with a pseudoexperiment-based approach which, among different hypotheses, appears the most likely cause of the observed discrepancy between the D0 and CDF signals.

The prospects for the search of the Standard Model Higgs boson with the CMS experiment at the LHC are presented. The analyses rely on a full simulation of the detector response and emphasis is put on explicit strategies for the measurement of experimental and background systematics from data. The discovery reach is presented as a function of the Higgs boson mass. A new complete strategy is presented for the early searches and for the control of systematics at very low luminosities of O(1/fb).

In the $W+2,3$ jet data collected by Collider Detector at Fermilab during the 1992--1995 Fermilab collider run, 13 events were observed to contain a superjet when $4.4\ifmmode\pm\else\textpm\fi{}0.6$ events are expected. A previous article detailed the selection and the kinematical properties of these events. The present paper provides estimates of the probability that the kinematics of these 13 events is statistically consistent with the standard model prediction.

We present a study of the dijet invariant mass distribution for the reaction $\pbp \to 2 $jets$+\gamma+X$, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. We compare the data to predictions for the production of a photon with two jets, together with the resonant processes $\pbp \to W/Z+\gamma+X$, in which the $W$ and $Z$ bosons decay hadronically. A fit is made to the dijet invariant mass distribution combining the non-resonant background and resonant processes. We use the result to establish a limit for the inclusive production cross section of $W/Z+\gamma$ with hadronic decay of the $W$ and $Z$ bosons.

This record contains the fully-preprocessed training/validation and testing datasets used to train and evaluate the final models for "Calorimetric Measurement of Multi-TeV Muons via Deep Regression" by Jan Kieseler, Giles C. Strong, Filippo Chiandotto, Tommaso Dorigo, &amp; Lukas Layer, (2021), arXiv:2107.02119 [physics.ins-det] (https://arxiv.org/abs/2107.02119). The files are LZF-compressed HDF5 format and designed to be used directly with the code-base available at https://github.com/GilesStrong/calo_muon_regression. Please use the 'issues' tab on the GitHub repo for any questions or problems with these datasets. The training dataset consists of 886,716 muons with energies in the continuous range [50,8000] GeV split into 36 subsamples (folds). The zeroth fold of this dataset is used as our validation data. The testing dataset contains 429,750 muons, generated at fixed values of muon energy (E=100, 500, 900, 1300, 1700, 2100, 2500, 2900, 3300, 3700, 4100 GeV), and split into 18 folds. The input features are the raw hits in the calorimeter (stored in a sparse COO representation), and the high-level features discussed in the paper.

The CMS experiment obtained a large number of groundbreaking results from the analysis of 7- and 8-TeV proton-proton collisions produced so far by the Large Hadron Collider at CERN. In this brief summary only a sample of those results will be discussed. A new particle with mass mH = 125.3 ± 0.4(stat.) ± 0.5(syst.) GeV and characteristics compatible with those expected for a standard model Higgs boson has been observed in its decays to photon pairs, WW pairs, and ZZ pairs. Searches for the rare decays Bd → µµ and Bs → µµ have allowed to set limits on the branching fractions which are close to standard model predictions, strongly constraining new physics models. The top quark has been studied with great detail, obtaining among other results the world’s best measurement of its mass as Mt = 173.49 ± 0.43(stat. + JES ) ± 0.98(syst.) GeV. New physics models have been strongly constrained with the available data.

The CMS experiment obtained a large number of groundbreaking results from the analysis of 7- and 8-TeV proton-proton collisions produced so far by the Large Hadron Collider at CERN. In this brief summary only a few of those results will be discussed. The new scalar discovered in 2012 has been studied in detail and all its characteristics have been found in agreement with standard model predictions for a Brout-Englert-Higgs boson. The large sample of top quark events collected in 2011 and 2012 have allowed world-class measurements of its mass; the combination of those results is Mt = 173.49 ± 0.36 ± 0.91 GeV. The rare decay Bs0 → μμ has been observed and found in agreement with standard model predictions; the search for the rare decay B0 → μμ has allowed to set a 95% CL limit on the branching fraction at 1.1 × 10−9. These two results strongly constrain new physics models.

The CMS experiment has produced a large number of new measurements with data collected during Run 1 by the CERN Large Hadron Collider (LHC). In this report a few results in Higgs and top physics will be mentioned. After a shutdown in 2013 and 2014, the LHC restarted proton-proton collisions at the unprecedented center-of-mass energy of 13 TeV in June 2015. The data collected until August 2015 have yielded interesting events and allowed the extraction of the first results of searches at the high-energy end of mass spectra, where the effect of the higher collision energy is largest.

The five-standard-deviation threshold is an established standard for discovery claims in experimental particle physics; however, the criterion is an ad-hoc recipe with no solid foundations. In this report I discuss its origins and the issues it was designed to address, pointing out its shortcomings and the need for a more flexible approach to decide when a new observed effect should be taken seriously.

The CMS experiment is a multi-purpose detector successfully operated at the LHC where predominantly pp collisions take place at various centre-of-mass energies up to sqrt(s)=8 TeV so far. Several weeks per year also heavy-ion collisions take place leading to interesting studies in Pb-Pb and p-Pb collisions at sqrt(s_(NN))=2.76 TeV and sqrt(s_(NN))=5.02 TeV centre-of-mass energies per nucleon, respectively. The excellent performance of the accelerator and the experiment allows for dedicated physics measurements over a wide range of subjects, starting from particle identification, encompassing forward physics, Standard Model measurements in multijet, boson, heavy flavour and top quark physics, building the basis for new physics searches interpreted within the framework of various models and theories. These pursued pp physics subjects are complemented by a rich heavy ion physics programme.

In this document we study the effect of anomalous Higgs boson couplings on non-resonant pair production of Higgs bosons ($HH$) at the LHC. We explore the space of the five parameters $\kappa_{\lambda}$, $\kappa_{t}$, $c_2$, $c_g$, and $c_{2g}$ in terms of the corresponding kinematics of the final state, and describe a partition of the space into a limited number of regions featuring similar phenomenology in the kinematics of $HH$ final state. We call clusters the sets of points belonging to the same region; to each cluster corresponds a representative point which we call a benchmark. We discuss a possible technique to estimate the sensitivity of an experimental search to the kinematical differences between the phenomenology of the benchmark points and the rest of the parameter space contained in the corresponding cluster. We also provide an analytical parametrization of the cross-section modifications that the variation of anomalous couplings produces with respect to standard model $HH$ production along with a recipe to translate the results into other parameter-space bases. Finally, we provide a preliminary analysis of variations in the topology of the final state within each region based on recent LHC results.

The Large Hadron Collider (LHC), CERN's flagship facility, has so far produced only a small fraction of the large number of collisions expected to be delivered in the core of the ATLAS and CMS detectors this year.

The CMS collaboration has recently produced results of a number of searches for new physics processes using data collected during the 2011 run of the Large Hadron Collider. Up to 5 inverse femtobarns of proton-proton collisions at 7 TeV centre-of-mass energy have been used to search for the standard model Higgs boson in five different decay modes, divided in 42 independent sub-channels. The combination of the results has allowed CMS to set 95% confidence-level limits on the Higgs boson mass, constraining it to lay in the region 114.4 600 GeV. An excess of events with a local significance of 3.1 standard deviations is observed for M(H)=124 GeV; the global significance of observing such an effect anywhere in the search range 110-600 GeV is estimated to be 1.5 standard deviations. A number of signatures of supersymmetric particles have also been investigated, significantly restricting the parameter space of natural low-scale theories. A search for the rare decays of neutral bottom mesons to muon pairs, Bs to mu mu and Bd to mu mu, has achieved the tightest limits to date, and is approaching the sensitivity to measure the standard model branching ratios. As it happens, though, the highly informative results extracted from 2011 data produce more questions than answers; this doubles expectations for the 2012 run of LHC, which will conclusively answer several of them.

The CMS experiment obtained a large number of groundbreaking results from the analysis of 7- and 8-TeV proton-proton collisions produced so far by the Large Hadron Collider at CERN. In this brief summary only a sample of those results will be discussed. A new particle with mass m(H) = 125.3 +- 0.4(stat.) +- 0.5(syst.) GeV and characteristics compatible with those expected for a standard model Higgs boson has been observed in its decays to photon pairs, WW pairs, and ZZ pairs. Searches for the rare decays B_d -> mu mu and B_s -> mu mu have allowed to set limits on the branching fractions which are close to standard model predictions, strongly constraining new physics models. The top quark has been studied with great detail, obtaining among other results the world's best measurement of its mass as m(top) = 173.49 +- 0.43(stat. + JES) +- 0.98(syst.) GeV. New physics models have been strongly constrained with the available data.

The CMS experiment has produced a large number of new measurements with data collected during Run 1 by the CERN Large Hadron Collider (LHC). In this report a few results in Higgs and top physics will be mentioned. After a shutdown in 2013 and 2014, the LHC restarted proton-proton collisions at the unprecedented center-of-mass energy of 13 TeV in June 2015. The data collected until August 2015 have yielded interesting events and allowed the extraction of the first results of searches at the high-energy end of mass spectra, where the effect of the higher collision energy is largest.

The CMS experiment obtained a large number of groundbreaking results from the analysis of 7- and 8-TeV proton-proton collisions produced so far by the Large Hadron Collider at CERN. In this brief summary only a sample of those results will be discussed. A new particle with mass m(H) = 125.3 +- 0.4(stat.) +- 0.5(syst.) GeV and characteristics compatible with those expected for a standard model Higgs boson has been observed in its decays to photon pairs, WW pairs, and ZZ pairs. Searches for the rare decays B_d -> mu mu and B_s -> mu mu have allowed to set limits on the branching fractions which are close to standard model predictions, strongly constraining new physics models. The top quark has been studied with great detail, obtaining among other results the world's best measurement of its mass as m(top) = 173.49 +- 0.43(stat. + JES) +- 0.98(syst.) GeV. New physics models have been strongly constrained with the available data.

The CMS collaboration has recently produced results of a number of searches for new physics processes using data collected during the 2011 run of the Large Hadron Collider. Up to 5 inverse femtobarns of proton-proton collisions at 7 TeV centre-of-mass energy have been used to search for the standard model Higgs boson in five different decay modes, divided in 42 independent sub-channels. The combination of the results has allowed CMS to set 95% confidence-level limits on the Higgs boson mass, constraining it to lay in the region 114.4<M(H)<127 GeV or M(H)>600 GeV. An excess of events with a local significance of 3.1 standard deviations is observed for M(H)=124 GeV; the global significance of observing such an effect anywhere in the search range 110-600 GeV is estimated to be 1.5 standard deviations. A number of signatures of supersymmetric particles have also been investigated, significantly restricting the parameter space of natural low-scale theories. A search for the rare decays of neutral bottom mesons to muon pairs, Bs to mu mu and Bd to mu mu, has achieved the tightest limits to date, and is approaching the sensitivity to measure the standard model branching ratios. As it happens, though, the highly informative results extracted from 2011 data produce more questions than answers; this doubles expectations for the 2012 run of LHC, which will conclusively answer several of them.

The European Physical Journal C—Particles and Fields—publishes scientific manuscripts of relevance to the scientific community following careful and strict peer reviewing and, whenever appropriate and necessary, through discussion with the authors, so as to optimise scientific content and style of presentation prior to publication. In some cases significant disagreement between authors and referees (and/or editors) of the journal cannot be resolved despite all efforts and best of intentions. While the journal—notwithstanding any appeals—retains the right to reject such manuscripts, the editors of this journal may decide, in cases deemed of exceptional interest and potential significance for the field, to accept the manuscript for publication, to amend it by “comments” of the editor(s) in charge and, if appropriate, by a “reply” of the authors of the commented manuscript. The present comment is on “Study of multi-muon events produced in $p\bar{p}$ interactions at $\sqrt{s}=1.96$ TeV” by T. Aaltonen et al. (the CDF Collaboration, Eur. Phys. J. C, 2010, doi: 10.1140/epjc/s10052-010-1336-0 ).