Claire Shepherd-Themistocleous

We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.

We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of Standard Model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the $\mu$m scale up to the Big Bang Nucleosynthesis limit of $\sim 10^7$m. Neutral LLPs with lifetimes above $\sim$ 100m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging backgrounds, triggers, and small acceptances. MATHUSLA is a proposal for a minimally instrumented, large-volume surface detector near ATLAS or CMS. It would search for neutral LLPs produced in HL-LHC collisions by reconstructing displaced vertices (DVs) in a low-background environment, extending the sensitivity of the main detectors by orders of magnitude in the long-lifetime regime. In this white paper we study the LLP physics opportunities afforded by a MATHUSLA-like detector at the HL-LHC. We develop a model-independent approach to describe the sensitivity of MATHUSLA to BSM LLP signals, and compare it to DV and missing energy searches at ATLAS or CMS. We then explore the BSM motivations for LLPs in considerable detail, presenting a large number of new sensitivity studies. While our discussion is especially oriented towards the long-lifetime regime at MATHUSLA, this survey underlines the importance of a varied LLP search program at the LHC in general. By synthesizing these results into a general discussion of the top-down and bottom-up motivations for LLP searches, it is our aim to demonstrate the exceptional strength and breadth of the physics case for the construction of the MATHUSLA detector.

We present the Large Hadron Collider (LHC) discovery potential in the ${Z}^{\ensuremath{'}}$ and heavy neutrino sectors of a $U(1{)}_{B\ensuremath{-}L}$ enlarged standard model also encompassing 3 heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a ${Z}^{\ensuremath{'}}$ decay chain involving heavy neutrinos, eventually decaying into leptons and jets. In particular, this signature allows one to measure the ${Z}^{\ensuremath{'}}$ and heavy neutrino masses involved. In addition, over a large region of the parameter space, the heavy neutrinos are rather long-lived particles producing distinctive displaced vertices that can be seen in the detectors. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length enables an estimate of the absolute mass of the parent light neutrino.

We present the Large Hadron Collider (LHC) discovery potential in the Z' sector of a U(1)_{B-L} enlarged Standard Model also encompassing three heavy Majorana neutrinos, for \sqrt{s}=7 centre-of-mass energy, considering both the Z'_{B-L}\rightarrow e^+e^- and Z'_{B-L}\rightarrow \mu^+\mu^- decay channels. Electrons provide a higher sensitivity to smaller couplings at small Z'_{B-L} boson masses than do muons. The run of the LHC at \sqrt{s}=7 TeV, assuming at most \int \mathcal{L} \sim 1 fb^{-1}, will be able to give similar results to those that will be available soon at the Tevatron in the lower mass region, and to extend them for a heavier M_{Z'}. A 5\sigma discovery could be possible up to M_{Z'}=1.2(0.9) TeV at the LHC(Tevatron), while a 2\sigma exclusion at the LHC could be possible up to M_{Z'}=1.6 TeV. The new gauge coupling g'_1 can been probed, at 5\sigma, down to \sim (3 \div 4) \cdot 10^{-2} with electrons and down to \sim (4 \div 5) \cdot 10^{-2} with muons, both at the LHC and at the Tevatron, for M_{Z'}=600 GeV. The Z' boson in this model exhibits novel signatures at the LHC, as multi-lepton and multi-jet decays via heavy neutrinos, that allow one to measure the heavy neutrino masses involved. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length (over a large region of parameter space, the heavy neutrinos are rather long-lived particles) enables an estimate of the absolute mass of the parent light neutrino.

We examine the observability of heavy neutrino (ν h ) signatures of a U(1)′ enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the the Large Hadron Collider (LHC). We show that heavy neutrinos can be rather long-lived particles producing distinctive displaced vertices that can be accessed in the CERN LHC detectors. We concentrate here on the gluon fusion production mechanism gg → H 1,2 → ν h ν h , where H 1 is the discovered SM-like Higgs and H 2 is a heavier state, yielding displaced leptons following ν h decays into weak gauge bosons. Using data collected by the end of the LHC Run 2, these signatures would prove to be accessible with negligibly small background.

In this paper, we discuss the potential of observing heavy neutrino ($\nu_h$) signatures of a $U(1)_{B-L}$ enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the Large Hadron Collider (LHC). We exploit the theoretical decay via a pair of heavy (non-SM-like) Higgs boson and $Z'$ production followed by $\nu_h \rightarrow l^\pm W^{\mp (*)}$ and $\nu_h \rightarrow \nu_l Z^{(*)}$ decays, ultimately yielding a $3l+2j+E_{T}^{\rm{miss}}$ signature and, depending upon how boosted the final state objects are, we define different possible selections aimed at improving the signal to background ratio in LHC Run 2 data for a wide range of heavy neutrino masses.

We present the Large Hadron Collider (LHC) discovery potential in the $Z'$ sector of a $U(1)_{B-L}$ enlarged Standard Model (that also includes three heavy Majorana neutrinos and an additional Higgs boson) for $\sqrt{s}=7$, 10 and 14 TeV centre-of-mass (CM) energies, considering both the $Z'_{B-L}\rightarrow e^+e^-$ and $Z'_{B-L}\rightarrow \mu^+\mu^-$ decay channels. The comparison of the (irreducible) backgrounds with the expected backgrounds for the D$\O$ experiment at the Tevatron validates our simulation. We propose an alternative analysis that has the potential to improve the D$\O$ sensitivity. Electrons provide a higher sensitivity to smaller couplings at small $Z'_{B-L}$ boson masses than do muons. The resolutions achievable may allow the $Z'_{B-L}$ boson width to be measured at smaller masses in the case of electrons in the final state. The run of the LHC at $\sqrt{s}=7$ TeV, assuming at most $\int \mathcal{L} \sim 1$ fb$^{-1}$, will be able to give similar results to those that will be available soon at the Tevatron in the lower mass region, and to extend them for a heavier $M_{Z'}$.

The interference effects between an extra neutral spin-1 Z ′-boson and the Standard Model background in the Drell-Yan channel at the LHC are studied in detail. The final state with two oppositely charged leptons is considered. The interference contribution to the new physics signal, currently not fully taken into account by experimental collaborations in Z ′-searches and in the interpretation of the results, can be substantial. It may affect limits or discovery prospects of Z ′ at the LHC. As the Z ′-boson interference is model-dependent, a proper treatment would a priori require a dedicated experimental analysis for each particular model. Doing so could potentially improve the sensitivity to new physics, but would require significantly more experimental effort. At the same time, it is shown that one can define an invariant mass window, valid for a wide range of models, for which the contribution of the model-dependent interference to the Beyond the Standard Model signal is reduced to $ \mathcal{O} $ (10%), comparable to the level of the combined uncertainty from parton densities and higher order corrections. This quasi-model-independent “magic cut” does not scale with the mass of the Z ′-boson and is approximately constant over a large range of masses. Such control of the interference effects relies on not-too-small branching ratios of Z ′ to leptons (typically of at least a few percent) which can be suppressed, however, by additional new decay channels of the Z ′; a small width-to-mass ratio alone does not guarantee the interference to be small over an arbitrary kinematic range. Under the general assumption that these new decay channels of Z ′ are not dominant, one can perform quasi-model-independent analyses, preserving the current scheme used by the experimental collaborations for the Z ′-boson search using the suggested invariant mass window cut.

The Forward-Backward Asymmetry (AFB) in Z' physics is commonly only perceived as the observable which possibly allows one to interpret a Z' signal by distinguishing different models of such (heavy) spin-1 bosons. In this paper, we examine the potential of AFB in setting bounds on or even discovering a Z' boson at the Large Hadron Collider (LHC) and show that it might be a powerful tool for this purpose. We analyse two different scenarios: Z' bosons with a narrow and wide width, respectively. We find that, in the first case, the significance of the AFB search can be comparable with that of the bump search usually adopted by the experimental collaborations; however, being a ratio of (differential) cross sections the AFB has the advantage of reducing systematical errors. In the second case, the AFB search can win over the bump search in terms of event shape, as the structure of the AFB distribution as a function of the invariant mass of the reconstructed Z'boson could nail down the new broad resonance much better than the event counting strategy usually adopted in such cases.

A new tracking detector is under development for use by the CMS experiment at the High-Luminosity LHC (HL-LHC). A crucial requirement of this upgrade is to provide the ability to reconstruct all charged particle tracks with transverse momentum above 2–3 GeV within 4 μs so they can be used in the Level-1 trigger decision. A concept for an FPGA-based track finder using a fully time-multiplexed architecture is presented, where track candidates are reconstructed using a projective binning algorithm based on the Hough Transform, followed by a combinatorial Kalman Filter. A hardware demonstrator using MP7 processing boards has been assembled to prove the entire system functionality, from the output of the tracker readout boards to the reconstruction of tracks with fitted helix parameters. It successfully operates on one eighth of the tracker solid angle acceptance at a time, processing events taken at 40 MHz, each with up to an average of 200 superimposed proton-proton interactions, whilst satisfying the latency requirement. The demonstrated track-reconstruction system, the chosen architecture, the achievements to date and future options for such a system will be discussed.

Di-lepton searches for Beyond the Standard Model (BSM) Z′ bosons that rely on the analysis of the Breit-Wigner (BW) line shape are appropriate in the case of narrow resonances, but likely not sufficient in scenarios featuring Z′ states with large widths. Conversely, alternative experimental strategies applicable to wide Z′ resonances are much more dependent than the default bump search analyses on the modelling of QCD higher-order corrections to the production processes, for both signal and background. For heavy Z′ boson searches in the di-lepton channel at the CERN Large Hadron Collider (LHC), the transverse momentum qT of the di-lepton system peaks at qT≲10−2Mll, where Mll is the di-lepton invariant mass. We exploit this to treat the QCD corrections by using the logarithmic resummation methods in Mll/qT to all orders in the strong coupling constant αs. We carry out studies of Z′ states with large width at the LHC by employing the program reSolve, which performs QCD transverse momentum resummation up to Next-to-Next-to-Leading Logarithmic (NNLL) accuracy. We consider two benchmark BSM scenarios, based on the Sequential Standard Model (SSM) and dubbed ‘SSM wide’ and ‘SSM enhanced’. We present results for the shape and size of Z′ boson signals at the differential level, mapped in both cross section (σ) and Forward-Backward Asymmetry (AFB), and perform numerical investigations of the experimental sensitivity at the LHC Run 3 and High-Luminosity LHC (HL-LHC).

Interference effects are widely neglected in searches for new physics. This is the case in recent publications on searches for W'-bosons using leptonic final states. We examine the effects of interference on distributions frequently used to determine mass limits for possible W'-bosons and show that there are important qualitative effects on the behaviour of the new physics signal. There are two main consequences. Firstly, exclusion limits where interferences effects have not been considered are likely to have been overestimated. Secondly, presenting experimental results as a function of a transverse mass cut rather than in terms of the contribution of new physics to the total cross-section would be more informative.

This report summarizes the activity on comparisons of existings tools for the standard model and on issues in jet physics by the SMHC working group during and subsequent to the Workshop "Physics at TeV Colliders", Les Houches, France, 11-29 June, 2007.

A variety of searches have been performed at the LHC using Run I data, looking for decays of the discovered Higgs boson, h 125, decaying to a pair of low mass bosons, with mass in the range $$ 2{m}_{\mu }-{m}_{h_{125}}/2\simeq 62 $$ GeV. We summarise the most pertinent ones, and look at how their limits affect a variety of supersymmetric and non-supersymmetric models which can give rise to such light bosons: the 2HDM (Types I and II), the NMSSM, and the nMSSM.

Unlike other realizations of the 2-Higgs doublet model (2HDM), the so-called type-I allows for a very light Higgs boson spectrum. Specifically, herein, the heaviest of the two $CP$-even neutral Higgs states, $H$, can be the one discovered at the Large Hadron Collider (LHC) in 2012, with a mass of $\ensuremath{\approx}125\text{ }\text{ }\mathrm{GeV}$ and couplings consistent with those predicted by the Standard Model (SM). In such a condition of the model, referred to as ``inverted mass hierarchy,'' the decay of the SM-like Higgs state into pairs of the lightest $CP$-even neutral Higgs boson, $h$, is possible, for masses of the latter ranging from ${M}_{H}/2\ensuremath{\approx}65\text{ }\text{ }\mathrm{GeV}$ down to 15 GeV or so, all compatible with experimental constraints. In this paper, we investigate the scope of the LHC in accessing the process $gg\ensuremath{\rightarrow}H\ensuremath{\rightarrow}hh\ensuremath{\rightarrow}b\overline{b}\ensuremath{\tau}\ensuremath{\tau}$ by performing a Monte Carlo (MC) analysis aimed at extracting this signal from the SM backgrounds, in presence of a dedicated trigger choice and kinematic selection. We prove that some sensitivity to such a channel exists already at run 3 of the LHC while the High-Luminosity LHC (HL-LHC) will be able to either confirm or disprove this theoretical scenario over sizable regions of its parameter space.

We review the prospects for B-decay physics at the LHC as discussed in the 1999 workshop on Standard Model physics at the LHC. Contents

We explore the effects of photon induced (PI) production of a dilepton final state in the Large Hadron Collider environment. Using QED parton distribution function (PDF) sets we can treat the photons as real partons inside the protons and compare their yield directly to that of the Drell-Yan (DY) process. In particular, we concentrate on an error analysis of the two mechanisms. In order to do so, we use the neural network parton distribution functions (NNPDF) set, which comes with a set of replicas to estimate the systematic PDF error, and the CT14 set. On the one hand, we find that the PI contribution becomes dominant over DY above a dilepton invariant mass of 3 TeV. On the other hand, the PI predictions are affected by a large uncertainty coming from the QED PDFs, well above the one affecting the DY mode. We assess the impact of these uncertainties in the context of resonant and nonresonant searches for a neutral massive vector boson (${Z}^{\ensuremath{'}}$) through the differential cross section and forward-backward asymmetry (AFB) observables as a function of the dilepton invariant mass. While the former is subject to the aforementioned significant residual errors the latter shows the systematic error cancellation expected (recall that AFB is a ratio of cross sections) even in presence of PI contributions, so that the recently emphasized key role played by AFB as a valid tool for both ${Z}^{\ensuremath{'}}$ discovery and interpretation in both resonant and nonresonant mode is further consolidated.

The Drell-Yan di-lepton production at hadron colliders is by far the preferred channel to search for new heavy spin-1 particles. Traditionally, such searches have exploited the Narrow Width Approximation (NWA) for the signal, thereby neglecting the effect of the interference between the additional Z'-bosons and the Standard Model Z and {\gamma}. Recently, it has been established that both finite width and interference effects can be dealt with in experimental searches while still retaining the model independent approach ensured by the NWA. This assessment has been made for the case of popular single Z'-boson models currently probed at the CERN Large Hadron Collider (LHC). In this paper, we test the scope of the CERN machine in relation to the above issues for some benchmark multi Z'-boson models. In particular, we consider Non-Universal Extra Dimensional (NUED) scenarios and the 4-Dimensional Composite Higgs Model (4DCHM), both predicting a multi-Z' peaking structure. We conclude that in a variety of cases, specifically those in which the leptonic decays modes of one or more of the heavy neutral gauge bosons are suppressed and/or significant interference effects exist between these or with the background, especially present when their decay widths are significant, traditional search approaches based on the assumption of rather narrow and isolated objects might require suitable modifications to extract the underlying dynamics.

We present a study of di-lepton production at the CERN Large Hadron Collider with a particular focus on the contribution resulting from both real and virtual photons in the initial state. We discuss the region of phase space in which the invariant mass of the lepton pair is of the order of several TeV, where searches for new physics phenomena yielding a di-lepton signature are presently carried out. We study both the yield and associated uncertainties for all possible topologies in photon-induced di-lepton production and compare these with what is expected in the standard Drell-Yan channel, where quark-antiquark pairs are responsible for the production of lepton pairs. We analyse the impact of these QED contributions on the expected Standard Model background and on searches for new physics. In this latter case, we use the production of an extra heavy $Z^\prime$-boson predicted by the Sequential Standard Model (SSM) as a benchmark process.

The Compact Muon Solenoid (CMS) experiment has implemented a sophisticated two-level online selection system that achieves a rejection factor of nearly 105. During Run II, the LHC will increase its centre-of-mass energy up to 13 TeV and progressively reach an instantaneous luminosity of 2 × 1034 cm−2 s−1. In order to guarantee a successful and ambitious physics programme under this intense environment, the CMS Trigger and Data acquisition (DAQ) system has been upgraded. A novel concept for the L1 calorimeter trigger is introduced: the Time Multiplexed Trigger (TMT) . In this design, nine main processors receive each all of the calorimeter data from an entire event provided by 18 preprocessors. This design is not different from that of the CMS DAQ and HLT systems. The advantage of the TMT architecture is that a global view and full granularity of the calorimeters can be exploited by sophisticated algorithms. The goal is to maintain the current thresholds for calorimeter objects and improve the performance for their selection. The performance of these algorithms will be demonstrated, both in terms of efficiency and rate reduction. The callenging aspects of the pile-up mitigation and firmware design will be presented.

The work contained herein constitutes a report of the ``Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 26 May--6 June, 2003. The research presented is original, and was performed specifically for the workshop. Tools for calculations in the minimal supersymmetric standard model are presented, including a comparison of the dark matter relic density predicted by public codes. Reconstruction of supersymmetric particle masses at the LHC and a future linear collider facility is examined. Less orthodox supersymmetric signals such as non-pointing photons and R-parity violating signals are studied. Features of extra dimensional models are examined next, including measurement strategies for radions and Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. An LHC search strategy for a heavy top found in many little Higgs model is presented and finally, there is an update on LHC $Z'$ studies.

A bstract We examine scenarios in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), where pair-produced squarks and gluinos decay via two cascades, each ending in a stable neutralino as Lightest Supersymmetric Particle (LSP) and a Standard Model (SM)-like Higgs boson, with mass spectra such that the missing transverse energy, E T miss , is very low. Performing two-dimensional parameter scans and focusing on the hadronic $$ H\to b\overline{b} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> decay giving a $$ b\overline{b}b\overline{b}+{E}_{\mathrm{T}}^{\mathrm{miss}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mi>E</mml:mi> <mml:mi>T</mml:mi> <mml:mi>miss</mml:mi> </mml:msubsup> </mml:math> final state we explore the sensitivity of a current LHC general-purpose jets + E T miss analysis to such scenarios.

A new tracking system is under development for operation in the CMS experiment at the High Luminosity LHC. It includes an outer tracker which will construct stubs, built by correlating clusters in two closely spaced sensor layers for the rejection of hits from low transverse momentum tracks, and transmit them off-detector at 40 MHz. If tracker data is to contribute to keeping the Level-1 trigger rate at around 750 kHz under increased luminosity, a crucial component of the upgrade will be the ability to identify tracks with transverse momentum above 3 GeV/c by building tracks out of stubs. A concept for an FPGA-based track finder using a fully time-multiplexed architecture is presented, where track candidates are identified using a projective binning algorithm based on the Hough Transform. A hardware system based on the MP7 MicroTCA processing card has been assembled, demonstrating a realistic slice of the track finder in order to help gauge the performance and requirements for a full system. This paper outlines the system architecture and algorithms employed, highlighting some of the first results from the hardware demonstrator and discusses the prospects and performance of the completed track finder.

We study the possibility of observing lepton number violation in the right-handed sneutrino sector of the next-to-minimal supersymmetric Standard Model extended with right-handed neutrinos. The scalar potential introduces a lepton number violating mass term for the right-handed sneutrinos, which generates a phase difference that results in oscillations between the sneutrino and antisneutrino. If we have light Higgsinos and right-handed sneutrinos, the sneutrino decay width is determined by the tiny Yukawa couplings, which allows the phase difference to accumulate before the sneutrino decays. We investigate the possibilities of producing sneutrino pairs resonantly through a heavy Higgs of such a model and the ability of seeing a lepton number violating signature emerging from sneutrinos at the Large Hadron Collider. We also discuss how a possible future signal of this type could be used to determine the neutrino Yukawa couplings.

Results from the completed Phase 1 Upgrade of the Compact Muon Solenoid (CMS) Level-1 Calorimeter Trigger are presented. The upgrade was performed in two stages, with the first running in 2015 for proton and heavy ion collisions and the final stage for 2016 data taking. The Level-1 trigger has been fully commissioned and has been used by CMS to collect over 43 fb−1 of data since the start of the Run II of the Large Hadron Collider (LHC). The new trigger has been designed to improve the performance at high luminosity and large number of simultaneous inelastic collisions per crossing (pile-up). For this purpose it uses a novel design, the Time Multiplexed Trigger (TMT), which enables the data from an event to be processed by a single trigger processor at full granularity over several bunch crossings. The TMT design is a modular design based on the μTCA standard. The trigger processors are instrumented with Xilinx Virtex-7 690 FPGAs and 10 Gbps optical links. The TMT architecture is flexible and the number of trigger processors can be expanded according to the physics needs of CMS. Sophisticated and innovative algorithms are now the core of the first decision layer of the experiment. The system has been able to adapt to the outstanding performance of the LHC, which ran with an instantaneous luminosity well above design. The performance of the system for single physics objects are presented along with the optimizations foreseen to maintain the thresholds for the harsher conditions expected during the LHC Run II and Run III periods.

Correlations among hadrons with the same electric charge produced in Z0 decays are studied using the high statistics data collected from 1991 through 1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth order are used to measure genuine particle correlations as a function of the size of phase space domains in rapidity, azimuthal angle and transverse momentum. Both all-charge and like-sign particle combinations show strong positive genuine correlations. One-dimensional cumulants initially increase rapidly with decreasing size of the phase space cells but saturate quickly. In contrast, cumulants in two- and three-dimensional domains continue to increase. The strong rise of the cumulants for all-charge multiplets is increasingly driven by that of like-sign multiplets. This points to the likely influence of Bose–Einstein correlations. Some of the recently proposed algorithms to simulate Bose–Einstein effects, implemented in the Monte Carlo model Pythia, are found to reproduce reasonably well the measured second- and higher-order correlations between particles with the same charge as well as those in all-charge particle multiplets.

We define a focus point (FP) asymmetry, ${A}_{\mathrm{FP}}$, obtained by integrating the normalized transverse momentum distribution of either lepton produced in the Drell-Yan (DY) process below and above a point where a variety of popular ${Z}^{\ensuremath{'}}$ models all have the same magnitude. For a given ${Z}^{\ensuremath{'}}$ mass the position of this FP is predictable, depending only on the collider energy and on the low transverse momentum cut chosen in the normalization procedure. The resulting ${A}_{\mathrm{FP}}$ is very sensitive to the ${Z}^{\ensuremath{'}}$ width and can be used to constrain this parameter in experimental fits.

We review theoretical and experimental results on CP violation summarizing the discussions in the working group on CP violation at the UK phenomenology workshop 2000 in Durham.

Searches for extra heavy W and Z -bosons in the leptonic Drell-Yan channel at the Large Hadron Collider (LHC) are favoured by present and future data.We focus on a common approximation used in theoretical and experimental analyses: neglecting interference between the new gauge bosons W ± (Z ) and the Standard Model ones W ± (Z, γ).And present the implications of adopting this approximation on the data interpretation and the extraction of exclusion limits on W and Zboson masses.First results from experimental analyses are quoted.

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).

A bstract We study displaced signatures of sneutrino pairs potentially emerging at the Large Hadron Collider (LHC) in a Next-to-Minimal Supersymmetric Standard Model supplemented with right-handed neutrinos triggering a Type-I seesaw mechanism. We show how such signatures can be established through a heavy Higgs portal, the sneutrinos then decaying to charged leptons and charginos giving rise to further leptons or hadrons. We finally illustrate how the Yukawa parameters of neutrinos can be extracted by measuring the lifetime of the sneutrino from the displaced vertices, thereby characterising the dynamics of the underlying mechanism of neutrino mass generation. We show our numerical results for the case of both the current and High-Luminosity LHC.

We study the potential of the h_1 -&gt; a_1 a_1 -&gt; 4 tau signal from the lightest scalar (h_1) and pseudoscalar (a_1) Higgs bosons to cover the parameter space of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) at the Large Hadron Collider (LHC). We exploit a 2 mu + 2 jets signature from four taus decays (accompanied by missing transverse energy), resorting to both Higgs-strahlung (HS), by triggering on leptonic W^\pm decays, and Vector Boson Fusion (VBF), by triggering on two same sign non-isolated muons.

We investigate the potential of the Large Hadron Collider (LHC) to probe one of the most compelling beyond the Standard Model frameworks---walking technicolor (WTC), involving strong dynamics and having a slowly running (walking) new strong coupling. For this purpose we use recent LHC Run 2 data to explore the full parameter space of the minimal WTC model using dilepton signatures from heavy neutral ${Z}^{\ensuremath{'}}$ and ${Z}^{\ensuremath{'}\ensuremath{'}}$ resonances predicted by the model. This signature is the most promising one for discovery of WTC at the LHC for the low-intermediate values of the $\stackrel{\texttildelow{}}{g}$ coupling---one of the principle parameters of WTC. We have demonstrated complementarity of the dilepton signals from both resonances, established the most up-to-date limit on the WTC parameter space, and provided projections for the LHC potential to probe the WTC parameter space at higher future luminosities and upgraded energy. We have explored the whole four-dimensional parameter space of the model and have found the most conservative limit on the WTC scale ${M}_{A}$ above 3 TeV for the low values of $\stackrel{\texttildelow{}}{g}$, which is significantly higher than previous limits established by the LHC collaborations.

Abstract We assess the performance of different jet-clustering algorithms, in the presence of different resolution parameters and reconstruction procedures, in resolving fully hadronic final states emerging from the chain decay of the discovered Higgs boson into pairs of new identical Higgs states, the latter in turn decaying into bottom-antibottom quark pairs. We show that, at the large hadron collider (LHC), both the efficiency of selecting the multi-jet final state and the ability to reconstruct from it the masses of the Higgs bosons (potentially) present in an event sample depend strongly on the choice of acceptance cuts, jet-clustering algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark Beyond the SM (BSM) signal. We then repeat the exercise for a heavy Higgs boson cascading into two SM-like Higgs states, obtaining similar results.

We present a new approach to jet definition alternative to clustering methods, such as the anti-$k_T$ scheme, that exploit kinematic data directly. Instead the new method uses kinematic information to represent the particles in a multidimensional space, as in spectral clustering. After confirming its Infra-Red (IR) safety, we compare its performance in analysing $qq\to H_{125\,\text{GeV}} \rightarrow H_{40\,\text{GeV}} H_{40\,\text{GeV}} \rightarrow b \bar{b} b \bar{b}$, $qq\to H_{500\,\text{GeV}} \rightarrow H_{125\,\text{GeV}} H_{125\,\text{GeV}} \rightarrow b \bar{b} b \bar{b}$ and $gg,q\bar q\to t\bar t\to b\bar b W^+W^-\to b\bar b jj \ell\nu_\ell$ events from Monte Carlo (MC) samples, specifically, in reconstructing the relevant final states, to that of the anti-kT algorithm. Finally, we show that the results for spectral clustering are obtained without any change in the parameter settings of the algorithm, unlike the anti-kT case, which requires the cone size to be adjusted to the physics process under study.

Report of the Higgs working group for the Workshop "Physics at TeV Colliders", Les Houches, France 8-18 June 1999. It contains 6 separate sections: 1. Measuring Higgs boson couplings at the LHC. 2. Higgs boson production at hadron colliders at NLO. 3. Signatures of Heavy Charged Higgs Bosons at the LHC. 4. Light stop effects and Higgs boson searches at the LHC. 5. Double Higgs production at TeV Colliders in the MSSM. 6. Programs and Tools for Higgs Bosons.

The ${T}_{20}$ analyzing powers have been measured for the $^{120}\mathrm{Sn}(^{7}\mathrm{Li},^{8}\mathrm{Be}\ensuremath{\rightarrow}2\ensuremath{\alpha})^{119}\mathrm{In}$ and $^{120}\mathrm{Sn}(^{7}\mathrm{Li},^{6}\mathrm{Li}^{*}\ensuremath{\rightarrow}\ensuremath{\alpha}+d)^{121}\mathrm{Sn}$ transfer breakup reactions, using a $70\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ beam. The data exhibit excellent agreement with the results of coupled reaction channels calculations, providing an important test of these calculations when applied to the transfer breakup reaction mechanism.

We present the Large Hadron Collider (LHC) discovery potential in the $Z'$ and heavy neutrino sectors of a $U(1)_{B-L}$ enlarged Standard Model also encompassing three heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a $Z'$ decay chain involving heavy neutrinos, eventually decaying into leptons and jets. In particular, this signature allows one to measure the $Z'$ and heavy neutrino masses involved. In addition, over a large region of parameter space, the heavy neutrinos are rather long-lived particles producing distinctive displaced vertices that can be seen in the detectors. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length enables an estimate of the absolute mass of the parent light neutrino. For completeness, we will also compare the LHC and a future Linear Collider (LC) discovery potentials.

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).

The Compact Muon Solenoid (CMS) employs a sophisticated two-level online triggering system that has a rejection factor of up to 105. Since the beginning of Run II of LHC, the conditions that CMS operates in have become increasingly challenging. The centre-of-mass energy is now 13 TeV and the instantaneous luminosity currently peaks at 1.5 ×1034 cm−2s−1. In order to keep low physics thresholds and to trigger efficiently in such conditions, the CMS trigger system has been upgraded. A new trigger architecture, the Time Multiplexed Trigger (TMT) has been introduced which allows the full granularity of the calorimeters to be exploited at the first level of the online trigger. The new trigger has also benefited immensely from technological improvements in hardware. Sophisticated algorithms, developed to fully exploit the advantages provided by the new hardware architecture, have been implemented. The new trigger system started taking physics data in 2016 following a commissioning period in 2015, and since then has performed extremely well. The hardware and firmware developments, electron and photon algorithms together with their performance in challenging 2016 conditions is presented.

The Compact Muon Solenoid (CMS) experiment at CERN is scheduled for a major upgrade in the next decade in order to meet the demands of the new High Luminosity Large Hadron Collider.Amongst others, a new tracking system is under development including an outer tracker capable of rejecting low transverse momentum particles by looking at the coincidences of hits (stubs) in two closely spaced sensor layers in the same tracker module.Accepted stubs are transmitted off-detector for further processing at 40 MHz.In order to maintain under the increased luminosity the Level-1 trigger rate at 750 kHz, tracker data need to be included in the decision making process.For this purpose, a system architecture has to be developed that will be able to identify particles with transverse momentum above 3 GeV/c by building tracks out of stubs, while achieving an overall processing latency of maximum 4us.Targeting these requirements the current paper presents an FPGA-based track finding architecture that identifies track candidates in real-time and bases its functionality on a fully time-multiplexed approach.As a proof of concept, a hardware system has been assembled targeting the MP7 MicroTCA processing card that features a Xilinx Virtex-7 FPGA, demonstrating a realistic slice of the track finder.The paper discusses the algorithms' implementation and the efficient utilisation of the available FPGA resources, it outlines the system architecture, and presents some of the hardware demonstrator results.

We present the Large Hadron Collider (LHC) discovery potential in the $Z'$ and heavy neutrino sectors of a $U(1)_{B-L}$ enlarged Standard Model also encompassing three heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a $Z'$ decay chain involving heavy neutrinos, eventually decaying into leptons and jets. In particular, this signature allows one to measure the $Z'$ and heavy neutrino masses involved. In addition, over a large region of parameter space, the heavy neutrinos are rather long-lived particles producing distinctive displaced vertices that can be seen in the detectors. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length enables an estimate of the absolute mass of the parent light neutrino. For completeness, we will also compare the LHC and a future Linear Collider (LC) discovery potentials.

At the HL-LHC, proton bunches will cross each other every 25 ns, producing an average of 140 pp-collisions per bunch crossing. To operate in such an environment, the CMS experiment will need a L1 hardware trigger able to identify interesting events within a latency of 12.5 μs. The future L1 trigger will make use also of data coming from the silicon tracker to control the trigger rate. The architecture that will be used in future to process tracker data is still under discussion. One interesting proposal makes use of the Time Multiplexed Trigger concept, already implemented in the CMS calorimeter trigger for the Phase I trigger upgrade. The proposed track finding algorithm is based on the Hough Transform method. The algorithm has been tested using simulated pp-collision data. Results show a very good tracking efficiency. The algorithm will be demonstrated in hardware in the coming months using the MP7, which is a μTCA board with a powerful FPGA capable of handling data rates approaching 1 Tb/s.

Unlike other realisations of the 2-Higgs Doublet Model (2HDM), the so-called Type-I allows for a very light Higgs boson spectrum. Specifically, herein, the heaviest of the two CP-even neutral Higgs states, $H$, can be the one discovered at the Large Hadron Collider (LHC) in 2012, with a mass of $\approx 125$ GeV and couplings consistent with those predicted by the Standard Model (SM). In such a condition of the model, referred to as `inverted mass hierarchy', the decay of the SM-like Higgs state into pairs of the lightest CP-even neutral Higgs boson, $h$, is possible, for masses of the latter ranging from $M_H/2\approx 65$ GeV down to 15 GeV or so, all compatible with experimental constraints. In this paper, we investigate the scope of the LHC in accessing the process $gg\to H \to hh\to b\bar b\tau\tau$ by performing a Monte Carlo (MC) analysis aimed at extracting this signal from the SM backgrounds, in presence of a dedicated trigger choice and kinematic selection. We prove that some sensitivity to such a channel exists already at Run 3 of the LHC while the High-Luminosity LHC (HL-LHC) will be able to either confirm or disprove this theoretical scenario over sizable regions of its parameter space.

We analyse new signals of a 3-Higgs Doublet Model (3HDM) at the Large Hadron Collider (LHC) where only one doublet acquires a Vacuum Expectation Value (VEV), preserving a $Z_2$ parity. The other two doublets are \textit{inert} and do not develop a VEV, leading to a \textit{dark scalar sector} controlled by $Z_2$, with the lightest CP-even dark scalar $H_1$ being the Dark Matter (DM) candidate. This leads to the loop induced decay of the next-to-lightest scalar, $H_2 \to H_1 \ell \bar \ell $ ($\ell =e,\mu$), mediated by both dark CP-odd neutral and charged scalars. This is a smoking-gun signal of the 3HDM since it is not allowed in the 2-Higgs Doublet Model (2HDM) with one inert doublet and is expected to be important when $H_2$ and $H_1$ are close in mass. In practice, this signature can be observed in the cascade decay of the SM-like Higgs boson, $h\to H_1 H_2\to H_1 H_1 \ell \bar \ell$ into two DM particles and di-leptons or $h\to H_2 H_2\to H_1 H_1 \ell \bar \ell \ell \bar \ell$ into two DM particles and four-leptons, where $h$ is produced from gluon-gluon Fusion. In order to test the feasibility of these channels at the LHC, we devise some benchmarks, compliant with collider, DM and cosmological data, for which the interplay between these production and decay modes is discussed. In particular, we show that the resulting detector signatures, $\Et \ell \bar \ell$ or $\Et \ell \bar \ell \ell \bar \ell$, with the invariant mass of $ \ell \bar \ell$ pairs much smaller than $m_Z$, can potentially be extracted already from Run 3 data and at the High-Luminosity phase of the LHC.

Differential cross sections and ${\mathit{T}}_{20}$ and $_{20}^{\mathit{TT}}$ analyzing powers have been measured for 70 MeV $^{7}\mathrm{Li}$ breakup into the \ensuremath{\alpha} particle plus triton channel, on a $^{120}\mathrm{Sn}$ target. Measurements were made for both continuum breakup and sequential breakup via the 4.63 MeV state in $^{7}\mathrm{Li}$. The ${\mathit{T}}_{20}$ data for the continuum breakup do not agree with a semiclassical Coulomb model, indicating that the breakup at small angles does not proceed solely via a Coulomb force. The data generally show a somewhat better agreement with continuum discretized coupled channels calculations, indicating the importance of the nuclear force and channel coupling in the reaction mechanism.

The production of the lightest Higgs boson, $h^0$, in association with the lightest stop, $\tilde{t}_{1}$, in the Minimal Supersymmetric Standard Model, is an interesting channel, as its cross section can be higher than Higgs production in association with top quarks. Furthermore, the $\tilde{t}_{1}\tilde{t}^{*}_{1}h^{0}$ production rate is highly dependent on various Supersymmetric parameters. The mass, mixings, couplings and production cross sections relevant to the $\tilde{t}_{1}\tilde{t}^{*}_{1}h^{0}$ channel have been studied in the past. Here, we complement these analyses by performing a thorough decay study. We conclude that there is some scope for extracting this channel at the Large Hadron Collider, for suitable combinations of the Supersymmetric parameters, in several different decay channels of both the stop quarks and Higgs boson, the most numerically promising being the signature involving charm decays of the stops and bottom decay of the Higgs. This, in fact, remains true in the Supergravity inspired Minimal Supersymmetric Standard Model.

The CMS Level-1 calorimeter trigger is being upgraded in two stages to maintain performance as the LHC increases pile-up and instantaneous luminosity in its second run. In the first stage, improved algorithms including event-by-event pile-up corrections are used. New algorithms for heavy ion running have also been developed. In the second stage, higher granularity inputs and a time-multiplexed approach allow for improved position and energy resolution. Data processing in both stages of the upgrade is performed with new, Xilinx Virtex-7 based AMC cards.

The CMS collaboration is preparing a major upgrade of its detector, so it can operate during the high luminosity run of the LHC from 2026. The upgraded tracker electronics will reconstruct the trajectories of charged particles within a latency of a few microseconds, so that they can be used by the level-1 trigger. An emulation framework, CIDAF, has been developed to provide a reference for a proposed FPGA-based implementation of this track finder, which employs a Time-Multiplexed (TM) technique for data processing.

The Forward-Backward Asymmetry (AFB) in Z' physics is commonly only thought of as an observable which possibly allows one to profiling a Z' signal by distinguishing different models embedding such (heavy) spin-1 bosons. In this brief review, we examine the potential of AFB in setting bounds on or even discovering a Z' at the Large Hadron Collider (LHC) and proof that it might be a powerful tool for this purpose. We analyse two different scenarios: Z's with a narrow and wide width, respectively. We find that, in both cases, AFB can complement the conventional searches in accessing Z' signals traditionally based on cross section measurements only.

We show the reinterpretation of existing searches for exotic decays of the Standard Model (SM)like Higgs, → (ℎℎ), in various final states, in the framework of the 2-Higgs Doublet Model (2HDM) Type-I.We then explore a new search for such light Higgses, and ℎ, at the Large Hadron Collider (LHC) Run 3 for an integrated luminosity of 300 fb -1 .After performing a scan over the model parameters, we found that the inverted scenario of Type-I offers a new promising signal in the form of the following cascade decays:→ * → * * ℎ → -+ .We investigate then its significance through a full Monte Carlo (MC) simulation down to the detector level.

The Forward-Backward Asymmetry (AFB) in $Z^\prime$ physics is commonly only perceived as the observable which possibly allows one to interpret a $Z^\prime$ signal by distinguishing different models of such (heavy) spin-1 bosons. In this article, we examine the potential of AFB in setting bounds on or even discovering a $Z^\prime$ at the Large Hadron Collider (LHC) and show that it might be a powerful tool for this purpose. We analyze two different scenarios: $Z^\prime$s with a narrow and wide width, respectively. We find that in both cases AFB can complement the cross section in accessing $Z^\prime$ signals.

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).

The CMS 2004 Data Challenge (DC04) was devised to test several key aspects of the CMS Computing Model in three ways: by trying to sustain a 25 Hz reconstruction rate at the Tier-0; by distributing the reconstructed data to six Tier-1 Regional Centres (CNAF in Italy, FNAL in US, GridKA in Germany, IN2P3 in France, PIC in Spain, RAL in UK) and handling catalogue issues; by granting data accessibility at remote centres for analysis. Simulated events, up to the digitization step, were produced prior to the DC as input for the reconstruction in the Pre-Challenge Production (PCP04). In this paper, the model of the Tier-0 implementation used in DC04 is described, as well as the experience gained in using the newly developed data distribution management layer, which allowed CMS to successfully direct the distribution of data from Tier-0 to Tier-1 sites by loosely integrating a number of available Grid components. While developing and testing this system, CMS explored the overall functionality and limits of each component, in any of the different implementations that were deployed within DC04. The role of Tier-1's is presented and discussed, from the import of reconstructed data from Tier-0, to the archiving on to the local Mass Storage System (MSS) and the data distribution management to Tier-2's for analysis. Participating Tier-1's differed in available resources, setup and configuration. A critical evaluation of the results and performances achieved adopting different strategies in the organization and management of each Tier-1 centre to support CMS DC04 is presented.

Searches for Z' bosons are most sensitive in the dilepton channels at hadron colliders. Whilst finite width and interference effects do affect the modifications the presence of BSM physics makes to Standard Model (SM) contributions, generic searches are often designed to minimize these. The experimental approach adopted works well in the case of popular models that predict a single and narrow Z' boson allowing these effects to effectively be neglected. Conversely, finite width and interference effects may have to be taken into account in experimental analyses when such Z' states are wide or where several states are predicted. We explore the consequences of these effects in the 4-Dimensional Composite Higgs Model (4DCHM) which includes multiple new Z' bosons and where the decays of these resonances to non-SM fermions can result in large widths.

The Forward-Backward Asymmetry (AFB) in Z' physics is commonly only thought of as an observable which possibly allows one to profiling a Z' signal by distinguishing different models embedding such (heavy) spin-1 bosons. In this brief review, we examine the potential of AFB in setting bounds on or even discovering a Z' at the Large Hadron Collider (LHC) and proof that it might be a powerful tool for this purpose. We analyse two different scenarios: Z's with a narrow and wide width, respectively. We find that, in both cases, AFB can complement the conventional searches in accessing Z' signals traditionally based on cross section measurements only.

A number of searches at the LHC looking for low mass ($2m_{\mu} - 62 \mathrm{GeV}$) bosons in $\sqrt{s} = 8 \mathrm{TeV}$ data have recently been published. We summarise the most pertinent ones, and look at how their limits affect a variety of supersymmetric models which can give rise to such light bosons: the 2HDM (Types I and II), the NMSSM, and the nMSSM.

We discuss the effect of the Photon Initiated (PI) process on the dilepton channel at the LHC. Adopting various QED PDF sets, we evaluate the contribution produced by two resolved photons which is not included in the Equivalent Photon Approximation (EPA). We compare the PI central value as predicted by the CTEQ, MRST and NNPDF collaborations. With the NNPDF2.3QED set of replicas we also estimate the PDF uncertainties on the PI central value. We show the effect of the inclusion of the PI contribution and its PDF uncertainties on neutral heavy Z'-boson searches. We explore the two scenarios of narrow and broad resonances, including in the analysis the reconstructed Forward-Backward Asymmetry observable, the latter being less affected by systematics effects.

The di-lepton final states provide the greatest sensitivity in searches for Z′-bosons at the Large Hadron Collider (LHC). These additional neutral bosons are predicted by many theories. From a phenomenological point of view, they can be divided into two classes: narrow width and wide Z′s. The experimental collaborations at the LHC have searched for narrow width Z′-bosons via the measurement of the di-lepton invariant mass. Wide scenarios have not yet been considered. Exclusion limits on the narrow-width Z′-boson mass have been determined using the data collected at centre-of-mass energies of √ s = 7, 8 TeV by the LHC experiments corresponding to integrated luminosities of approximately L ' 20 f b−1 for each experiment. Here, we discuss the possibility of using an additional observable to complement the usual dilepton invariant mass in order to maximize the LHC potential in searching for Z′-bosons. The observable we consider is the Forward-Backward Asymmetry (AFB). This variable is commonly proposed as a tool to be used for interpreting data and discriminating between different models in the event of a prior Z′ observation. We propose that the AFB is also useful as an observable in the Z′ search process.

Searches for Z bosons are most sensitive in the dilepton channels at hadron colliders.Whilst finite width and interference effects do affect the modifications the presence of BSM physics makes to Standard Model (SM) contributions, generic searches are often designed to minimize these.The experimental approach adopted works well in the case of popular models that predict a single and narrow Z boson allowing these effects to effectively be neglected.Conversely, finite width and interference effects may have to be taken into account in experimental analyses when such Z states are wide or where several states are predicted.We explore the consequences of these effects in the 4-Dimensional Composite Higgs Model (4DCHM) which includes multiple new Z bosons and where the decays of these resonances to non-SM fermions can result in large widths.

Searches for Z' bosons are most sensitive in the dilepton channels at hadron colliders. Whilst finite width and interference effects do affect the modifications the presence of BSM physics makes to Standard Model (SM) contributions, generic searches are often designed to minimize these. The experimental approach adopted works well in the case of popular models that predict a single and narrow Z' boson allowing these effects to effectively be neglected. Conversely, finite width and interference effects may have to be taken into account in experimental analyses when such Z' states are wide or where several states are predicted. We explore the consequences of these effects in the 4-Dimensional Composite Higgs Model (4DCHM) which includes multiple new Z' bosons and where the decays of these resonances to non-SM fermions can result in large widths.

The Forward-Backward Asymmetry (AFB) in $Z^\prime$ physics is commonly only perceived as the observable which possibly allows one to interpret a $Z^\prime$ signal by distinguishing different models of such (heavy) spin-1 bosons. In this article, we examine the potential of AFB in setting bounds on or even discovering a $Z^\prime$ at the Large Hadron Collider (LHC) and show that it might be a powerful tool for this purpose. We analyze two different scenarios: $Z^\prime$s with a narrow and wide width, respectively. We find that in both cases AFB can complement the cross section in accessing $Z^\prime$ signals.

We discuss the effect of the Photon Initiated (PI) process on the dilepton channel at the LHC. Adopting various QED PDF sets, we evaluate the contribution produced by two resolved photons which is not included in the Equivalent Photon Approximation (EPA). We compare the PI central value as predicted by the CTEQ, MRST and NNPDF collaborations. With the NNPDF2.3QED set of replicas we also estimate the PDF uncertainties on the PI central value. We show the effect of the inclusion of the PI contribution and its PDF uncertainties on neutral heavy Z'-boson searches. We explore the two scenarios of narrow and broad resonances, including in the analysis the reconstructed Forward-Backward Asymmetry observable, the latter being less affected by systematics effects.

The Forward-Backward Asymmetry (AFB) in Z' physics is commonly only thought of as an observable which possibly allows one to profiling a Z' signal by distinguishing different models embedding such (heavy) spin-1 bosons. In this brief review, we examine the potential of AFB in setting bounds on or even discovering a Z' at the Large Hadron Collider (LHC) and proof that it might be a powerful tool for this purpose. We analyse two different scenarios: Z's with a narrow and wide width, respectively. We find that, in both cases, AFB can complement the conventional searches in accessing Z' signals traditionally based on cross section measurements only.

We present the Large Hadron Collider (LHC) discovery potential in the Z sector of a U(1) B-L enlarged Standard Model also encompassing three heavy Majorana neutrinos, for √ s = 7 centreof-mass energy, considering both the Z B-L → e + e -and Z B-L → µ + µ -decay channels.Electrons provide a higher sensitivity to smaller couplings at small Z B-L boson masses than do muons.The run of the LHC at √ s = 7 TeV, assuming at most L ∼ 1 fb -1 , will be able to give similar results to those that will be available soon at the Tevatron in the lower mass region, and to extend them for a heavier M Z .A 5σ discovery could be possible up to M Z = 1.2(0.9)TeV at the LHC(Tevatron), while a 2σ exclusion at the LHC could be possible up to M Z = 1.6 TeV.The new gauge coupling g 1 can been probed, at 5σ , down to ∼ (3 ÷ 4) • 10 -2 with electrons and down to ∼ (4 ÷ 5) • 10 -2 with muons, both at the LHC and at the Tevatron, for M Z = 600 GeV.The Z boson in this model exhibits novel signatures at the LHC, as multi-lepton and multijet decays via heavy neutrinos, that allow one to measure the heavy neutrino masses involved.Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length (over a large region of parameter space, the heavy neutrinos are rather long-lived particles) enables an estimate of the absolute mass of the parent light neutrino.

We review the most relevant LHC searches at $\sqrt{s}$ = 8 TeV looking for low mass bosons arising from exotic decay of the Standard Model Higgs and highlighting their impact on both supersymmetric and not supersymmetric Beyond the Standard Model scenarios.

We show the SM prediction of di-lepton production at the LHC where to the usual Drell-Yan production we add the contribution from Photon-Initiated processes. We discuss the effects of the inclusion of photon interactions in the high invariant mass region (TeV region) and their consequences on BSM heavy Z'-boson searches.

We report on recent studies of photon-induced (PI) contributions to di-lepton production and their implications for Beyond Standard Model (BSM) $Z^\prime$-bosons searches at the LHC.

While most BSM searches at the LHC focus on heavy new states, the NMSSM contains the possibility of new light states that have escaped detection due to their singlet nature. Here we focus on light pseudoscalars, investigating the parameter space impact of recent LHC searches for such light states stemming from the decay of the 125 GeV Higgs boson. It is shown that, though direct searches can not yet compete with the requirement of the 125 GeV scalar having SM-like couplings, the searches are touching the allowed parameter space and should make a phenomenological impact in the near future.

We recognise the appearance of a Focus Point (FP) in the transverse momentum distribution of either leptons originating from a BSM $Z^\prime$-boson decay, after a simple normalisation procedure. Exploring the properties of the FP we will be able to define in a general way a new observable, the Focus Point Asymmetry ($A_{\rm FP}$), which can be used to set constrains on the $Z^\prime$ width. We discuss the potential and the sensitivity of the $A_{\rm FP}$ in as diagnostic tool for $Z^\prime$ physics, considering various $Z^\prime$ phenomenological realisations.

We discuss the effect of the Photon Initiated (PI) process on the dilepton channel at the LHC. Adopting various QED PDF sets, we evaluate the contribution produced by two resolved photons which is not included in the Equivalent Photon Approximation (EPA). We compare the PI central value as predicted by the CTEQ, MRST and NNPDF collaborations. With the NNPDF2.3QED set of replicas we also estimate the PDF uncertainties on the PI central value. We show the effect of the inclusion of the PI contribution and its PDF uncertainties on neutral heavy Z'-boson searches. We explore the two scenarios of narrow and broad resonances, including in the analysis the reconstructed Forward-Backward Asymmetry observable, the latter being less affected by systematics effects.

We report on recent studies of photon-induced (PI) contributions to di-lepton production and their implications for Beyond Standard Model (BSM) $Z^\prime$-bosons searches at the LHC.

While most BSM searches at the LHC focus on heavy new states, the NMSSM contains the possibility of new light states that have escaped detection due to their singlet nature.Here we focus on light pseudoscalars, investigating the parameter space impact of recent LHC searches for such light states stemming from the decay of the 125 GeV Higgs boson.It is shown that, though direct searches can not yet compete with the requirement of the 125 GeV scalar having SM-like couplings, the searches are touching the allowed parameter space and should make a phenomenological impact in the near future.

We present the Large Hadron Collider (LHC) discovery potential in the Z' sector of a U(1)_{B-L} enlarged Standard Model also encompassing three heavy Majorana neutrinos, for \sqrt{s}=7 centre-of-mass energy, considering both the Z'_{B-L}\rightarrow e^+e^- and Z'_{B-L}\rightarrow \mu^+\mu^- decay channels. Electrons provide a higher sensitivity to smaller couplings at small Z'_{B-L} boson masses than do muons. The run of the LHC at \sqrt{s}=7 TeV, assuming at most \int \mathcal{L} \sim 1 fb^{-1}, will be able to give similar results to those that will be available soon at the Tevatron in the lower mass region, and to extend them for a heavier M_{Z'}. A 5\sigma discovery could be possible up to M_{Z'}=1.2(0.9) TeV at the LHC(Tevatron), while a 2\sigma exclusion at the LHC could be possible up to M_{Z'}=1.6 TeV. The new gauge coupling g'_1 can been probed, at 5\sigma, down to \sim (3 \div 4) \cdot 10^{-2} with electrons and down to \sim (4 \div 5) \cdot 10^{-2} with muons, both at the LHC and at the Tevatron, for M_{Z'}=600 GeV. The Z' boson in this model exhibits novel signatures at the LHC, as multi-lepton and multi-jet decays via heavy neutrinos, that allow one to measure the heavy neutrino masses involved. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length (over a large region of parameter space, the heavy neutrinos are rather long-lived particles) enables an estimate of the absolute mass of the parent light neutrino.

We show the SM prediction of di-lepton production at the LHC where to the usual Drell-Yan production we add the contribution from Photon-Initiated processes. We discuss the effects of the inclusion of photon interactions in the high invariant mass region (TeV region) and their consequences on BSM heavy Z'-boson searches.

We report on recent studies of photon-induced (PI) contributions to di-lepton production and their implications for Beyond Standard Model (BSM) $Z^\prime$-bosons searches at the LHC.

While most BSM searches at the LHC focus on heavy new states, the NMSSM contains the possibility of new light states that have escaped detection due to their singlet nature. Here we focus on light pseudoscalars, investigating the parameter space impact of recent LHC searches for such light states stemming from the decay of the 125 GeV Higgs boson. It is shown that, though direct searches can not yet compete with the requirement of the 125 GeV scalar having SM-like couplings, the searches are touching the allowed parameter space and should make a phenomenological impact in the near future.

We present a new approach to jet definition alternative to clustering methods, such as the anti-$k_T$ scheme, that exploit kinematic data directly. Instead the new method uses kinematic information to represent the particles in a multidimensional space, as in spectral clustering. After confirming its Infra-Red (IR) safety, we compare its performance in analysing $gg \rightarrow H_{125~\rm GeV} \rightarrow H_{40~\rm GeV}H_{40~\rm GeV} \rightarrow b\bar{b}b\bar{b}$, $gg \rightarrow H_{500~\rm GeV} \rightarrow H_{125~\rm GeV}H_{125~\rm GeV} \rightarrow b\bar{b}b\bar{b}$ and $gg, q\bar{q} \rightarrow t\bar{t} \rightarrow b\bar{b}W^+W^- \rightarrow b\bar{b}jjl\nu l$ events from Monte Carlo (MC) samples, specifically, in reconstructing the relevant final states, to that of the anti-$k_T$ algorithm. Finally, we show that the results for spectral clustering are obtained without any change in the parameter settings of the algorithm, unlike the anti-$k_T$ case, which requires the cone size to be adjusted to the physics process under study.

The ultimate motivation of our study is to look for signs of physics beyond the Standard Model (BSM). We investigate whether different jet clustering techniques might be more or less suited to the particular final states of interest. In particular, we are interested in fully hadronic final states emerging from the decay chain of the Standard Model like Higgs boson into pairs of light Higgs states, the latter in turn decaying into bottom-anti bottom pairs. We show that, the ability of selecting the multi-jet final state and to reconstruct invariant masses of the Higgs bosons from it depend strongly on the choice of acceptance cuts, resolution parameters and reconstruction algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark as a BSM signal. We then repeat the exercise for a heavy Higgs boson cascading into two SM-like Higgs states, obtaining similar results.

The ultimate motivation of our study is to look for signs of physics beyond the Standard Model (BSM). We investigate whether different jet clustering techniques might be more or less suited to the particular final states of interest. In particular, we are interested in fully hadronic final states emerging from the decay chain of the Standard Model like Higgs boson into pairs of light Higgs states, the latter in turn decaying into 𝑏𝑏 pairs. We show that the ability to select the multi-jet final state and to reconstruct invariant masses of the Higgs bosons from it depends strongly on the choice of acceptance cuts, resolution parameters, and reconstruction algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark as a BSM signal. We then repeat the exercise for a heavy Higgs boson cascading into two SM-like Higgs states, obtaining similar results.

A new tracking detector is under development for use by the CMS experiment at the High-Luminosity LHC (HL-LHC).A crucial component of this upgrade will be the ability to reconstruct within a few microseconds all charged particle tracks with transverse momentum above 3 GeV, so they can be used in the Level-1 trigger decision.A concept for an FPGA-based track finder using a fully time-multiplexed architecture is presented, where track candidates are reconstructed using a projective binning algorithm based on the Hough Transform followed by a track fitting based on the linear regression technique.A hardware demonstrator using MP7 processing boards has been assembled to prove the entire system, from the output of the tracker readout boards to the reconstruction of tracks with fitted helix parameters.It successfully operates on one eighth of the tracker solid angle at a time, processing events taken at 40 MHz, each with up to 200 superimposed proton-proton interactions, whilst satisfying latency constraints.The demonstrated track-reconstruction system, the chosen architecture, the achievements to date and future options for such a system will be discussed.

Supersymmetry relates neutrinos with their superpartners, sneutrinos. Unlike neutrinos, sneutrinos may decay visibly in colliders. We discuss how we could get information from neutrino Yukawa couplings in the NMSSM extended with right-handed neutrinos, if the right-handed sneutrinos are within the reach of the colliders.

Supersymmetry relates neutrinos with their superpartners, sneutrinos.Unlike neutrinos, sneutrinos may decay visibly in colliders.We discuss how we could get information from neutrino Yukawa couplings in the NMSSM extended with right-handed neutrinos, if the right-handed sneutrinos are within the reach of the colliders.

Supersymmetry relates neutrinos with their superpartners, sneutrinos. Unlike neutrinos, sneutrinos may decay visibly in colliders. We discuss how we could get information from neutrino Yukawa couplings in the NMSSM extended with right-handed neutrinos, if the right-handed sneutrinos are within the reach of the colliders.

We assess the performance of different jet-clustering algorithms, in the presence of different resolution parameters and reconstruction procedures, in resolving fully hadronic final states emerging from the chain decay of the discovered Higgs boson into pairs of new identical Higgs states, the latter in turn decaying into bottom-antibottom quark pairs. We show that, at the Large Hadron Collider (LHC), both the efficiency of selecting the multi-jet final state and the ability to reconstruct from it the masses of the Higgs bosons (potentially) present in an event sample depend strongly on the choice of acceptance cuts, jet-clustering algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark Beyond the SM (BSM) signal.

We review the prospects for B decay studies at the LHC.

Combined results on b-hadron lifetimes, b-hadron production rates, B{sub d}{sup 0}-{bar B}{sub d}{sup 0} and B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations, the decay width difference between the mass eigenstates of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system, the average number of c and {bar c} quarks in b-hadron decays, and searches for CP violation in the B{sub d}{sup 0}-{bar B}{sub d}{sup 0} system are presented. They have been obtained from published and preliminary measurements available in Summer 2000 from the ALEPH, CDF, DELPHI, L3, OPAL and SLD Collaborations. These results have been used to determine the parameters of the CKM unitarity triangle.

The measurement of the lifetimes of the individual B species are of great interest. Many of these measurements are well below the 10 % level of precision. However, in order to reach the precision necessary to test the current theoretical predictions, the results from different experiments need to be averaged. Therefore, the relevant systematic uncertainties of each measurement need to be well defined in order to understand the correla­ tions between the results from different experiments. In this paper we discuss the dominant sources of systematic errors which lead to correlations between the different measurements. We point out problems connected with the conventional approach of combining lifetime data and discuss methods which overcome these problems. 1) Dipartimento di Fisica Universita' di Roma II, 00173 Rome, Italy. 2) CERN, 1211 Geneva 23, Switzerland. 3) Department of Physics, University of Oxford, Oxford, OX1 3RB, UK. 4) Max Planck Institut fur Physik, 80805 Munchen, Germany. 5) Centre for Research in Particle Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada. tnow at Universite de Geneve, 1211 Geneva 4, Switzerland. tnow at Universitat Hamburg/DESY, 22603 Hamburg, Germany;>