In recent years many models of supersymmetry have implied a large production rate for events including a high multiplicity of third generation quarks, such as four top quarks. It is arguably the best-motivated channel for early LHC discovery. A particular example is generic string theories compactified to four dimensions with stabilized moduli which typically have multi-TeV squarks and lighter gluinos (below a TeV) with a large pair production rate and large branching ratios to four tops. We update and sharpen the analysis 4-top signals and background to 7 TeV LHC energy. For 1 fb-1 integrated luminosity, gluinos up to about 650 GeV in mass can be detected, with larger masses accessible for higher luminosities or at higher energies. More than one signature is likely to be accessible, with one charged lepton plus two or more b-jets, and/or same-sign dileptons plus b-jets being the best channels. A non-Standard Model signal from counting is robust, and provides information on the gluino mass, cross section, and spin.
The ATLAS and CMS Collaborations at the CERN Large Hadron Collider (LHC) have devoted considerable effort to the study of SUSY signatures and measurements. This talk provides an overview of what can be learned at the LHC if TeV-scale SUSY exists.
If SUSY exists at the TeV scale, finding it at the LHC should be quite easy. The more difficult problem is to separate the various SUSY channels and to measure masses and other parameters. Substantial progress on this has been made within the ATLAS and CMS Collaborations.
The discovery of the Standard Model (SM) or supersymmetric (SUSY) Higgs bosons belongs to the main endeavors of the Large Hadron Collider (LHC). In this article the status of the signal and background calculations for Higgs boson production at the LHC is reviewed.
The SUSY-GUT paradigm is the most promising scenario for the physics beyond the Standard Model. After the LHC run I, it is of interest to reanalyze the room still remaining for SUSY-GUT inspired models and to study the limits on the SUSY mass spectrum. Assuming one step unification of gauge couplings, under some natural requirements we have obtained the energy upper bound for the observation of SUSY phenomenology. We found that in the SUSY-GUT framework the mass of lightest gluino or Higgsino cannot be larger than about 20 TeV.
In light of the discovery of the new particle at 125GeV and the strong lower limits on the masses of superparticles from LHC, we discuss a possible picture of weak scale supersymmetry.
This talk summarizes work by the ATLAS Collaboration at the CERN Large Hadron Collider on the search SUSY particles and Higgs bosons and on possible measurements of their properties.
In this talk I review the motivations for physics beyond the Standard Model at the TeV scale and the prospects for their detection in the second Run of LHC. Then I focus in the supersymmetric case, paying special attention to the formulation and implications of the Natural SUSY scenario.
I discuss the construction of Simplified Models for Dark Matter searches at the LHC. After reviewing the phylosophy and some simple example, I turn the attention to the aspect of the theoretical consistency of these models.
We present a case study for the synergy of combined LHC and LC analyses in Susy searches in which simultaneous running of both machines is very important. In this study only light non-coloured Susy particles are accessible at a Linear Collider with an initial energy of $\sqrt{s}=500$ GeV. Nevertheless the precise analysis at the LC leads to an accurate Susy parameter determination and prediction of heavy Susy particles. Providing these LC results as input for the LHC analyses could be crucial for the identification of signals resulting in a direct measurement of the heavy neutralinos. The inte…
I review the status of supersymmetry after the 2011 LHC search results. I concentrate in particular on interpretations beyond the conventional CMSSM, including i) natural SUSY with light stops, and ii) the so-called phenomenological MSSM, which is a general parametrization of the MSSM at the weak scale, without boundary conditions imposed by specific SUSY breaking schemes. We will see that the current searches are not yet sensitive to some of the theoretically most interesting scenarios.
ATLAS and CMS collaborations have searched for the supersymmetry (SUSY) in different channels with 7 TeV center-of-mass energy and their search strategies are optimized for the SUSY scenarios with fairly large mass splittings among the sparticles. In absence of any significant deviation of the data from the Standard Model (SM) prediction, stringent bounds are imposed on the squarks and gluino masses in the context of different SUSY scenarios. Since the exact SUSY breaking mechanism is not known, some part of the SUSY spectrum may be degenerate. In this paper, we consider two particular cases o…
We analyze the potential of the first LHC physics run, assuming 1/fb at sqrt[s] = 7 TeV, to discover Supersymmetry (SUSY). The results are based on SUSY parameter fits following a frequentist approach. They include the experimental constraints from electroweak precision data, (g-2)_mu, B-physics and cosmological data. The two SUSY models under consideration are the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking mass parameters, and a model with common non-universal Higgs mass parameters in the superpotential (NUHM1). We find that large parts of the regions preferred at the…
We present a short review of the LHC results at 7 TeV and their implications on the Standard Model (SM) and on its Supersymmetric (SUSY) extension. In particular we discuss the exclusion range for the SM Higgs mass, the tantalizing hint of an excess at $m_H \sim 125$ GeV, the negative results of searches for SUSY particles (as well as for any other new physics) and the present outlook.
We give detailed predictions for diffractive SUSY Higgs boson and top squark associated productions at the LHC via the exclusive double pomeron exchange mechanism. We study how the SUSY Higgs cross section and the signal over background ratio are enhanced as a function of tangent beta in different regimes. The prospects are particularly promising in the ``anti-decoupling'' regime, which we study in detail. We also give the prospects for a precise measurement of the top squark mass using the threshold scan of central diffractive associated top squark events at the LHC.
We show that presently available precision data are in good agreement with supersymmetry at a mass scale below 1 TeV. Using a SUSY point close to the best fit to present data, we give a projection of the capabilities of the LHC to constrain SUSY models and their parameters as function of the accumulated luminosity.
We re-evaluate prospects for supersymmetry at the proposed International Linear $e^+e^-$ Collider (ILC) in light of the first year of serious data taking at LHC with $\sqrt{s}=7$ TeV and $\sim 5$ fb$^{-1}$ of $pp$ collisions (LHC7). Strong new limits from LHC SUSY searches, along with a hint of a Higgs boson signal around $m_h\sim 125$ GeV, suggest a paradigm shift from previously popular models to ones with new and compelling signatures. We present a variety of new ILC benchmark models, including: natural SUSY, hidden SUSY, NUHM2 with low $m_A$, non-universal gaugino mass (NUGM) model, pMSSM,…
We present a case study for the synergy of combined LHC and LC analyses in Susy searches where simultaneous running of both machines is very important. In case that only light non-coloured Susy particles are accessible at a Linear Collider with an initial energy of $\sqrt{s}=500$ GeV, the precise analysis at the LC nevertheless leads to an accurate Susy parameter determination. This allows the prediction of heavy Susy particles. Providing these LC results as input for LHC analyses could be crucial for the identification of signals resulting in a direct measurement of the heavy neutralinos. The…
We compute Gamma(H+ -> t \bar{b}) at one-loop in the MSSM and show how future data at the Tevatron and/or at the LHC could be used to unravel the potential SUSY nature of the charged Higgs.
We study the signature of $H^\pm$ decay into $h^0W$ at the LHC in SUSY models. It has only marginal viability in the MSSM. But in the singlet extensions like the NMSSM one can have a spectacular signature for $H^\pm$ decay into $(h^0,A^0)W$ over a significant domain of parameter space.
The recent discovery of a SM-like Higgs boson at the LHC, with a mass around 125-126 GeV, together with the absence of results in the direct searches for supersymmetry, is pushing the SUSY scale ($m_\text{SUSY}$) into the multi-TeV range. This discouraging situation from a low-energy SUSY point of view has its counterpart in indirect SUSY observables which present a non-decoupling behavior with $m_\text{SUSY}$. This is the case of the one-loop lepton flavor violating Higgs decay rates induced by SUSY, which are shown here to remain constant as $m_\text{SUSY}$ grows, for large $m_\text{SUSY} >$…
After motivation and short presentation of the minimal supersymmetric model with R-symmetry (MRSSM), we address the question of accomodating the measured Higgs boson mass in accordance with electroweak precision observables and LHC constraints.
We estimate the inclusive double diffractive production of SUSY particles at the LHC using a modified version of the POMWIG Monte Carlo event generator. The diffractive events are produced via the Ingelman-Schlein model for double pomeron exchange. The MSSM parameter space is scanned using the ``Snowmass benchmark points'' and it is shown that the lightest Higgs boson is the only SUSY particle with a large enough rate to be detected using these diffractive events.
An effective mass scale Meffsusy for supersymmetric particles is defined and techniques for its measurement at the LHC discussed. Monte Carlo results show that, for jets + ETmiss events, a variable constructed from the scalar sum of the transverse momenta of all reconstructed jets together with ETmiss provides in most cases the most accurate model independent measurement of Meffsusy (intrinsic precision ~ 2.1 % for mSUGRA models). The overall precision with which Meffsusy could be measured after given periods of LHC running and for given classes of SUSY models is calculated. The technique is e…
These lectures, given at the 1997 TASI Summer School, describe the prospects for discovering supersymmetry (SUSY) and for studying its properties at the Large Hadron Collider (LHC) at CERN. If SUSY exists at a mass scale less than 1--2 TeV, then it should be easy to observe characteristic deviations from the Standard Model at the LHC. It is more difficult to determine SUSY masses because in most models there are two missing particles \tildeχ_1^0 in every event. However, it is possible to use various kinematic distributions to make precision measurements of combinations of SUSY masses and other…
The implications of the LHC SUSY searches as well as the discovery of a new bosonic state compatible with the lightest Higgs boson will be discussed in the context of constrained and general MSSM scenarios. Exploring the MSSM through the Higgs sector is an alternative and complementary path to direct searches, and tight constraints on the MSSM parameter space can be obtained.
Inspired by the recent LHC Higgs data and null search results of supersymmetry (SUSY), we scan the parameter space of the Minimal Supersymmetric Standard Model (MSSM) with relatively heavy sparticles (1-3 TeV). Then in the parameter space allowed by current collider experiments and dark matter detections, we calculate the complete one-loop SUSY QCD corrections to $pp\to b\bar{b}h$ at the LHC with $\sqrt{s}=14$ TeV and obtain the following observations: (i) For the large values of $\tanβ$ and low values of $m_{A}$, the SUSY QCD effects can be quite large, which, however, have been excluded by t…
Some supersymmetric models after the recent LHC reports are discussed. Especially, the light Higgs boson around 125GeV is attempted to be accommodated. An extra Z' from GUTs, and the scalar and pseudoscalar Higgs bosons in supersymmetric extension of the standard model are also discussed.
When several sparticle masses are known, the kinematics of SUSY decay processes observed at the LHC can be solved if the cascade decays contain sufficient steps. We demonstrate four examples of this full reconstruction technique applied to channels involving leptons, namely a) gluino mass determination, b) sbottom mass determination, c) LSP momentum reconstruction, and d) heavy higgs mass determination.
We analyze the LHC SUSY 1exclusion limits in the cha1-neu2 channel. We take into account the decay neu2 -> neu1 h (based on a full one-loop calculation in the complex MSSM), which has a non-negligible branching ratio. Including this decay strongly reduces the excluded parameter space in the m_neu2-m_neu1 plane. This opens up a large parameter space for electroweak SUSY particles, easily allowing the production of these particles at the ILC.
In this note we compare the latest 1.04 fb^{-1} LHC searches for squarks and gluinos from jets and missing transverse momentum (MET) with constraints arising from the LEP Higgs bound. For General Gauge Mediation models with moderate values of tan(beta) we find that the zero-lepton MET searches of supersymmetry at the LHC are only starting to be competitive with the Higgs bounds from LEP. From this perspective and for such models, the SUSY searches at the LHC are still very much in the beginning.
We re-evaluate prospects for supersymmetry at the proposed International Linear e^+e^- Collider (ILC) in light of the first two years of serious data taking at LHC: LHC7 with ~5 fb^{-1} of pp collisions at sqrt{s}=7 TeV and LHC8 with ~20 fb^{-1} at \sqrt{s}=8 TeV. Strong new limits from LHC8 SUSY searches, along with the discovery of a Higgs boson with m_h~125 GeV, suggest a paradigm shift from previously popular models to ones with new and compelling signatures. After a review of the current status of supersymmetry, we present a variety of new ILC benchmark models, including: natural SUSY, ra…
We evaluate the $t\bar{c}$ and $t\bar{u}$ productions at the LHC within the general unconstrained MSSM framework. We find that these single top quark productions induced by SUSY-QCD FCNC couplings have remarkable cross sections for favorable parameter values allowed by current low energy data, which can be as large as a few pb. Once large rates of the $t\bar{c}$ and $t\bar{u}$ productions are detected at the LHC, they may be induced by SUSY FCNC couplings. We show that the precise measurement of single top quark production cross sections at the LHC is a powerful probe for the details of the SU…
I start with a brief summary of Higgs Mechanism and supersymmetry. Then I discuss the theoretical constraints, current limits and search strategies for Higgs boson(s) at LHC - first in the SM and then in the MSSM. Finally, I discuss the analogous constraints and search strategies for the superparticles, concentrating on the minimal supergravity model. Recent advances in identifying the most promising channels for Higgs and SUSY searches are emphasized.
On the basis of frequentist analyses of experimental constraints from electroweak precision data, (g-2)_mu, B-physics and cosmological data, we predict the masses of Higgs bosons and SUSY particles of the CMSSM, NUHM1, VCMSSM and mSUGRA. In the CMSSM, NUHM1 and VCMSSM we find preferences for sparticle masses that are relatively light, leading to good prospects for the LHC and the ILC. Including first data from SUSY searches at the LHC leads to an increase of the preferred sparticle mass scales, but improves the consistency of the model predictions for M_h with the LEP exclusion bounds.
If SUSY is discovered at the LHC, the task will immediately turn to determining the model of SUSY breaking. Here, we employ a Mixed Modulus-Anomaly Mediated SUSY Breaking (MMAMSB) model with very similar LHC phenomenology to the more conventionally studied Constrained Minimal SUSY Model (CMSSM) and minimal Anomaly Mediated SUSY Breaking (mAMSB) models. We then study whether the models can be distinguished and measured. If we only fit to the various mass edges and mass end-points from cascade decay chains that are normally studied, a unique determination and measurement of the model is problema…
In Split-Supersymmetry models, where the only non-Standard Model states produceable at LHC-energies consist of a gluino plus neutralinos and charginos, it is conventionally accepted that only mass differences among these latter are measureable at the LHC. The present work shows that application of a simple `Kinematic Selection' technique allows full reconstruction of neutralino and chargino masses from one event, in principle. A Monte Carlo simulation demonstrates the feasibilty of using this technique at the LHC.
Combined analyses at the Large Hadron Collider and at the International Linear Collider are important to reveal precisely the new physics model as, for instance, supersymmetry. Examples are presented where ILC results as input for LHC analyses could be crucial for the identification of signals as well as of the underlying model. The synergy of both colliders leads also to rather accurate SUSY parameter determination and powerful mass constraints even if the scalar particles have masses in the multi-TeV range.
The magic couple of SUSY and GUT still appears the most elegant and predictive physics concept beyond the Standard Model. Since up to now LHC found no evidence for supersymmetric particles it becomes of particular relevance to determine an upper bound of the energy scale they have to show up. In particular, we have analyzed a generic SUSY-GUT model assuming one step unification like in SU(5), and adopting naturalness principles, we have obtained general bounds on the mass spectrum of SUSY particles. We claim that if a SUSY gauge coupling unification takes place, the lightest gluino or Higgsino…
After completion of the LHC8 run in 2012, the plan is to upgrade the LHC for operation close to its design energy sqrt{s}=14 TeV, with a goal of collecting hundreds of fb^{-1} of integrated luminosity. The time is propitious to begin thinking of what is gained by even further LHC upgrades. In this report, we compute an LHC14 reach for SUSY in the mSUGRA/CMSSM model with an anticipated high luminosity upgrade. We find that LHC14 with 300 (3000) fb^{-1} has a reach for SUSY via gluino/squark searches of m(gluino)\sim3.2 TeV (3.6 TeV) for m(squark)\sim m)gluino), and a reach of m(gluino)\sim1.8 T…
In order to establish supersymmetry (SUSY) at future colliders, the identity of gauge couplings and the corresponding Yukawa couplings between gauginos, sfermions and fermions needs to be verified. Here a first phenomenological study for determining the Yukawa coupling of the SUSY-QCD sector is presented, using a method which combines information from LHC and ILC.
We study the potential to observe CP-violating effects in SUSY cascade decay chains at the LHC. Asymmetries composed by triple products of momenta of the final state particles are sensitive to CP-violating effects. Due to large boosts that dilute the asymmetries, these can be difficult to observe. Extending the methods of momentum reconstruction we show that the original size of these asymmetries may be measurable. A study is done at the hadronic level with backgrounds to estimate the expected sensitivity at the LHC.
The ability of the LHC to make statements about the dark matter problem is considered, with a specific focus on supersymmetry. After reviewing the current strategies for supersymmetry searches at the LHC (in both CMS and ATLAS), some key ATLAS studies are used to demonstrate how one could establish that SUSY exists before going on to measure the relic density of a neutralino WIMP candidate. Finally, the general prospects for success at the LHC are investigated by looking at different points in the MSSM parameter space.
We demonstrate how the interplay of a future e^+e^- LC at its first stage with sqrt{s} sim 500 GeV and of the LHC could lead to a precise determination of the fundamental SUSY parameters in the gaugino/higgsino sector without assuming a specific supersymmetry breaking scheme. We demonstrate this for the benchmark scenario SPS1a, taking into account realistic errors for the masses and cross sections measured at the LC with polarised beams, including errors coming from polarisation measurements, and mass measurements at the LHC. The results clearly demonstrate the complementarity of the LHC and …
Most models of weak scale supersymmetry (SUSY) predict observable rates for production of SUSY matter at the CERN LHC. The SUSY collider events are expected to be rich in jets, isolated (and non-isolated) leptons and missing E_T. After first discussing the merits of mixed axion/axino vs. neutralino cold dark matter in SUSY models, I then survey prospects for detecting SUSY matter at the LHC via leptonic signatures. In the paradigm mSUGRA model, cascade decays of gluinos and squarks should yield high rates for multi-jet plus multi-lepton events, allowing values of m_{\tg}\sim 3 (1.8) TeV to be …
At the LHC, superpartners with the masses lighter than a few TeV may be found, and the masses of the supersymmetric (SUSY) particles and their interactions will be studied. The information would be the base to consider the SUSY breaking mechanism and cosmology related to the SUSY dark matter. We review the recent studies that aims for the ``precise SUSY study'' at the LHC.
SUSY searches at the LHC as well as the 126 GeV Higgs boson indicate that superparticles, especially squarks and gluinos, are not so light as we expected. It is important to investigate SUSY searches which do not rely on the colored superparticles. As a clue for the investigation, we focus on the muon g-2 anomaly, which can be explained by the SUSY contributions if some of neutralinos, charginos, and sleptons are as light as of order 100 GeV. We propose the muon-(g-2)-motivated MSSM as a benchmark model, where squarks are decoupled but the superparticles corresponding to the muon g-2 are light…
Both ATLAS and CMS have published results of SUSY searches putting limits on SUSY parameters and masses. A non-discovery of SUSY in the next two years would push these limits further. On the other hand, precision data of low energy measurements and the dark matter relic density favor a light scale of supersymmetry. Therefore we investigate if supersymmetry -- more specifically the highly constraint model mSUGRA -- does at all agree with precision data and LHC exclusions at the same time, and whether the first two years of LHC will be capable of excluding models of supersymmetry. We consider th…
We study CP asymmetries in two-body decays of top squarks into neutralinos and sleptons at the LHC. These asymmetries are used to probe the CP phases possibly present in the stop and neutralino sector of the Minimal Supersymmetric Standard Model. Taking into account bounds from experimental electric dipole moment searches, we identify areas in the mSUGRA parameter space where CP asymmetries can be sizeable and discuss the feasibility of their observation at the LHC. As a result, potentially detectable CP asymmetries in stop decays at the LHC are found, motivating further detailed experimental …
Recent theoretical developments concerning Higgs production at the Large Hadron Collider are reviewed, both in the Standard Model and in the MSSM. Emphasis is put on the inclusive and exclusive cross sections for gluon fusion, as well as on the associated production with bottom quarks.
The physics potential of the Large Hadron Collider in combination with the planned International Linear Collider is discussed for a difficult region of supersymmetry that is characterized by scalar SUSY particles with masses around 2 TeV. Precision measurements of masses, cross sections and forward-backward asymmetries allow to determine the fundamental supersymmetric parameters even if only a small part of the spectrum is accessible. No assumptions on a specific SUSY-breaking mechanism are imposed. Mass contraints for the kinematically inaccessible particles can be derived.
Weak scale supersymmetry is a highly motivated extension of the Standard Model that has a strong degree of support from data. It provides several viable dark matter candidates: the lightest neutralino (a WIMP), the gravitino, and the axion/axino supermultiplet. The LHC turn-on is imminent. The discovery of supersymmetry at the LHC will go a long way towards establishing the nature of dark matter. I present arguments why mainly axion cold dark matter is a better fit for supersymmetric models than neutralinos. I also argue that Yukawa-unified SUSY GUT theories based on SO(10) with mixed axion/ax…
It is often true that an invariant mass constructed from visible decay products of a heavy particle may attain a maximum(or minimum) for a certain kinematic configuration only -- this fact can be used to reconstruct relevant particle masses from observed decay product momenta of events near the invariant mass endpoint. MSSM neutralino and chargino mass reconstruction at the LHC from multi-lepton endstates is illustrated by way of example.
In the context of the Minimal Supersymmetric extension of the Standard Model, we discuss the impact of the decays of the neutral Higgs bosons into supersymmetric particles, charginos/neutralinos and sfermions. We show that these decay modes could be dominant, when they are kinematically accessible, thus strongly suppressing the branching ratios for the decay channels which are used to detect the Higgs bosons at hadron colliders. These SUSY decay modes should therefore not be overlooked in the search for the Higgs particles at the LHC.
Cascade decays of Supersymmetric (SUSY) particles are likely to be prolific sources of Higgs bosons at the Large Hadron Collider (LHC). In this work, we explore, with the help of detailed simulation, the role of non-universal gaugino masses in the production of the Higgs bosons under SUSY cascades. The analysis is carried out by choosing an appropriate set of benchmark points with non-universal gaugino masses in the relevant SUSY parameter space and then contrasting the resulting observations with the corresponding cases having universal relationship among the same. It is shown that even of da…
We examine the discovery reach of LHC14 for supersymmetry for integrated luminosity ranging from 0.3 to 3 ab^{-1}. In models with gaugino mass unification and M_1,\ M_2<< |μ| (as for mSUGRA/CMSSM), we find a reach of LHC14 with 3 ab^{-1} for gluino pair production extends to m_{\tg} 2.3 TeV while the reach via \tw_1\tz_2 \to W h +ETmiss extends to m_{\tg}\sim 2.6 TeV.
I start with a brief introduction to Higgs mechanism and supersymmetry. Then I discuss the theoretical expectations, current limits and search strategies for Higgs boson(s) at LHC --- first in the SM and then in the MSSM. Finally I discuss the signatures and search strategies for the superparticles.
