Search

One of the theories which attracted much attention for the new physics is the Supersymmetry. It explains the strong and the electroweak interactions from the grand unification scale down to the weak-scale. The last missing piece in the Standard Model, the Higgs boson, is discovered at the LHC, but there is no clue for any of the supersymmetric particles so far. The number of free parameters and the region for the supersymmetry is quite large, and it is highly probable that LHC could not get any hint of these sparticles. In this study, the chargino pair production via electron-positron and photon-photon collisions are studied in the context of the Stau-Neutralino annihilation scenario. This scenario is proposed after the negative results presented by the LHC. The calculation is carried out for all the possible one loop diagrams. The production cross section as a function of the collision energy is presented. The partonic cross section reaches up to 1.2 pb at the tree level, and the NLO correction reduces the cross section up to 19%. Employing this benchmark model for the chargino pair production shows the potential of the future lepton-lepton and photon-photon colliders regarding the searches of the supersymmetry. [ABSTRACT FROM AUTHOR]

Within the framework of the Minimal Supersymmetric Standard Model (MSSM), we explore a decoupling of the parameters into separate sectors that determine consistency with collider data, the abundance of dark matter, and potential signatures at direct dark matter searches. We consider weak-scale bino-like neutralino dark matter, and find that annihilations via light slepton exchange present a viable mechanism for obtaining the appropriate dark matter abundance assuming a thermal history. Constraints and prospects for discovery of these models are discussed, including the possibility that direct dark matter searches may be sensitive to these models if light squarks exhibit left-right mixing. Differences between the scenarios presented here and the typical expectations for the MSSM are discussed. [ABSTRACT FROM AUTHOR]

The lightest neutralino of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation is one of the most well-studied dark matter (DM) candidates. Using a set of models in the 19-parameter phenomenological MSSM (pMSSM), we examine the abilities of XENON100/1T, LUX-ZEPLIN, Fermi, CTA, IceCube/DeepCore, and the LHC to study neutralino dark matter. We find that direct detection, indirect detection, neutrino telescope, and collider searches for minimal supersymmetry often fulfill concomitant roles. [ABSTRACT FROM AUTHOR]

The success of supersymmetry is beyond any doubt. With the availabilility of the precise measurement of the dark matter content of the universe, SUSY models are used as cosmological connection to particle physics. The SUSY particles responsible for satisfying the dark matter content can be observed via cascade decay prcesses from the squarks, gluino productions. These particles also can be detected via vector boson fusion production processes. In this review, I will summarize various search strategies which will be importan and establish the cosmological connection. [ABSTRACT FROM AUTHOR]

The Tevatron collider has provided the CDF and DO collaborations with large datasets as input to a rich program of physics beyond the standard model The results presented here are from recent searches for SUSY particles using up to 6 fb-1 of data. [ABSTRACT FROM AUTHOR]

Supersymmetric grand unified theories based on the gauge group SO(10) are highly motivated. In the simplest models, one expects t-b-τ Yukawa coupling unification, in addition to gauge, matter and Higgs unification. Yukawa unification only occurs with very special GUT scale boundary conditions, leading to a spectra with ∼ 10 TeV first and second generation scalars, TeV-scale third generation scalars, and light gauginos. The relic density of neutralino cold dark matter is calculated to be 102-104 times higher than observation. If we extend the theory with the PQ solution to the strong CP problem, then instead a mixture of axions and axinos comprises the dark matter, with the measured abundance. Such a solution solves several cosmological problems. We predict a rather light gluino with mg∼300-500 GeV that should be visible in either Tevatron or forthcoming LHC run 1 data. We would also expect ultimately a positive result from relic axion search experiments. [ABSTRACT FROM AUTHOR]

At the Tevatron collider, the CDF and DO\ experiments are carrying out a wide program of searches for SuperSymmetry. Recent results, based on up to 4 fb-1 of collected data, are presented. No evidence of new physics is found and exclusion limits are extracted for the investigated SUSY phase space. [ABSTRACT FROM AUTHOR]

The exchange of electroweak gauginos in the t— or u—channel allows squark pair production at hadron colliders without color exchange between the squarks. This can give rise to events where little or no energy is deposited in the detector between the squark decay products. We discuss the potential for detection of such rapidity gap events at the Large Hadron Collider (LHC). We present an analysis with full event simulation using PYTHIA as well as Herwig++, but without detector simulation. We analyze the transverse energy deposited between the jets from squark decay, as well as the probability of finding a third jet in between the two hardest jets. For the mSUGRA benchmark point SPS1a we find statistically significant evidence for a color singlet exchange contribution. [ABSTRACT FROM AUTHOR]

We have recently completed a detailed scan of the 19-dimensional parameter space of the phenomenological MSSM, i.e., the CP-conserving MSSM assuming Minimal Flavor Violation(MFV) with the firs two sfermion generations degenerate. We found a large set of parameter space points that satisfie all of the existing experimental and theoretical constraints. This analysis allows us to examine the general features of the MSSM without reference to any particular SUSY breaking scenario or any other assumptions about physics at higher scales. This study opens up new possibilities for SUSY phenomenology both at colliders and in astrophysical observations. [ABSTRACT FROM AUTHOR]

While gluinos and neutralinos are Majorana fermions in the MSSM, they can be Dirac fermion fields in extended supersymmetry models. The difference between the two cases manifests itself in production and decay processes at colliders. In this contribution, results are presented for how the Majorana or Dirac nature of gluinos and neutralinos can be extracted from di-lepton signals at the LHC. [ABSTRACT FROM AUTHOR]

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 ET. 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 mg∼3 (1.8) TeV to be probed for mq≃mg (mq>mg) with 100 fb-1 of integrated luminosity. Direct production of gauginos and sleptons should also be possible in limited regions of parameter space. Even in the first year of LHC running, observable signals in multi-muon plus jets channel (without cutting on missing ET) can occur for interesting ranges of parameters. The highly motivated Yukawa unified SUSY models—where the dark matter is expected to be of mixed axion/axino type—should likely be testable in the first year of LHC running due to large rates for gluino pair production followed by cascade decays. [ABSTRACT FROM AUTHOR]

The Next-To-Minimal-Supersymmetric extension of the Standard Model (NMSSM) has been in the focus of extensive studies in the past two decades. In anticipation of the LHC era, the interest in automatized tools that can calculate collider signatures has grown. We present the implementation of the NMSSM into the event generator WHIZARD. In addition to a brief review of the implementation, we discuss the testing and validation procedure. Phenomenological studies will not be presented here. [ABSTRACT FROM AUTHOR]

If supersymmetry is discovered by the next generation of collider experiments, it will be crucial to determine its fundamental high-scale parameters. Three scenarios have been recently investigated by the SFitter collaboration : the case where the LHC “only” measures a light Higgs like signal, the case where SUSY signal are discovered at the LHC, and the dream scenario, where LHC and ILC measurements can be combined. [ABSTRACT FROM AUTHOR]

Littlest Higgs model with T-parity and Minimal Supersymmtric standard Model (MSSM) with R-parity both give similar signatures in collider experiment with a huge amount of missing energy depending upon mass of the lightest T-odd/R-odd particle. In this talk, I will discuss possibility of distinguishing the two models at the LHC in hadronically quiet signal where masses of R-odd particles are identical to masses of T-odd particles. [ABSTRACT FROM AUTHOR]

A new Abelian gauge symmetry U(1)′ is well motivated to extend the standard model or supersymmetric standard model. Leptonic Z′ resonances are clean signals even at the hadron colliders. We discuss how 4-lepton and 6-lepton Z′ resonances can help the search for Supersymmetry and Higgs, respectively, at the LHC. [ABSTRACT FROM AUTHOR]

The ATLAS and CMS experiments will take first data soon. I consider here the prospects for new physics (excluding SUSY) with a few fb-1 of data. This means processes with signal cross sections of a few 100 fb or less, with clear and fairly simple signatures—precision comparison of data to Standard Model tails will take longer, needing more luminosity and very good understanding of detector calibrations, resolutions and trigger efficiencies. The approach I take here is signature rather than model based, but examples of models will be given. [ABSTRACT FROM AUTHOR]

Many of the open questions beyond the Standard Model will be addressed by the LHC, including the origin of mass, supersymmetry, dark matter and the possibility of large extra dimensions. A linear e+e- collider (LC) with sufficient centre-of-mass energy would add considerable value to the capabilities of the LHC. [ABSTRACT FROM AUTHOR]

We stress that the lack of direct evidence for supersymmetry forces the soft mass parameters to lie very close to the critical line separating the broken and unbroken phases of the electroweak gauge symmetry. We argue that the level of criticality, or fine-tuning, that is needed to escape the present collider bounds can be quantitatively accounted for by assuming that the overall scale of the soft terms is an environmental quantity. Under fairly general assumptions, vacuum-selection considerations force a little hierarchy in the ratio between mZ2 and the supersymmetric particle square masses, with a most probable value equal to a one-loop factor. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report on some new results on interesting flavor violating Higgs decays in a supersymmetric standard model. The emphasis is on pure CKM-induced contributions in the case of the MSSM, with conserved R parity, with explicit numerical results. More generic cases including flavor violating soft masses and the case of contributions from R parity violating parameters will be discussed. Processes on focus are any of the three Higgs states to a b and an s quark. Very substantial branching fractions can be obtained. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

It is possible that the right-handed sneutrino is the lightest supersymmetric particle (LSP). We consider the cosmological implications of such an LSP, particularly under what conditions it can lead to the observed relic density. We then discuss the Tevatron and LHC signatures of this LSP. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In order to establish supersymmetry at future colliders, it is not sufficient to discover new particles, but the identity of gauge couplings and the corresponding Yukawa couplings between gauginos, sfermions and fermions needs to be verified. In detailed studies it was found that the SUSY-Yukawa couplings of the electroweak sector can be studied with great precision at the ILC, but a similar analysis for the Yukawa coupling of the SUSY-QCD sector proves to be far more challenging. Here a first phenomenological study for determining this coupling is presented, using a method which combines information from LHC and ILC. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Gravitinos and axinos produced in the late decays of other supersymmetric particles are well-motivated dark matter (DM) candidates, whose experimental evidences are very distinctive and different from other standard candidates, as thermal produced neutralinos in similar supersymmetric models. In particular, charged sleptons could appear stable because of the length of its lifetime. The direct production of such particles at both the Large Hadron Collider (LHC) and a future International Linear Collider (ILC) can give not only a clear signature of supersymmetry but also the first non-gravitational evidence of dark matter. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recently it was shown that the excess of diffuse Galactic gamma rays above 1 GeV traces the Dark Matter halo, as proven by reconstructing the peculiar shape of the rotation curve of our Galaxy from the gamma ray excess. This can be interpreted as a Dark Matter annihilation signal. In this talk we show that this interpretation is consistent with Supersymmetry. It is found that the EGRET excess combined with all electroweak constraints and WMAP CMB data is fully consistent with the minimal mSUGRA model with the neutralino mass around 60 GeV. It leads to the SUSY mass spectrum in the TeV range for scalars and gauginos below 500 GeV. The corresponding cross-sections for SUSY production are within the reach of the LHC. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We study the implications for electroweak baryogenesis (EWB) within the minimal supersymmetric Standard Model (MSSM) of present and future searches for the permanent electric dipole moment (EDM) of the electron, for neutralino dark matter, and for supersymmetric particles at high energy colliders. We show that there exist regions of the MSSM parameter space that are consistent with both present two-loop EDM limits and the relic density and that allow for successful EWB through resonant chargino and neutralino processes at the electroweak phase transition. We give present constraints on chargino/neutralino-induced EWB implied by the flux of energetic neutrinos from the Sun, the prospective constraints from future neutrino telescopes and ton-sized direct detection experiments, and the possible signatures at the LHC and at a future ILC. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report on direct searches for Higgs bosons carried out by the CDF and DØ Collaborations in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. Limits on the production cross section times branching fraction will be presented and a brief discussion of searches for supersymmetric Higgs bosons will be given. We will focus mainly on recent results only (those released in 2006), based on data sets of 260 – 950 fb-1 of data collected between 2004 – 2006. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Heavy flavor physics, in particular B and τ physics results from the B Factories, currently provides strong constraints on models of physics beyond the Standard Model. A new generation of colliders, Super B Factories, with 50 to 100 times the luminosity of existing colliders, can, in a dialog with LHC and ILC, provide unique clarification of new physics phenomena seen at those machines. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In about two years time the LHC is scheduled to deliver its first pp collisions at a centre of mass energy of 14 TeV. The LHC is expected to open up the discovery of new physics at the TeV scale, and give the final answer on the Standard Model Higgs. The LHC will however also be a tool for precision physics. Furthermore LHC is also a pA and AA collider. This report summarizes some of the physics opportunities of the LHC. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this paper I present the most recent results of the ongoing searches, mainly from Tevatron Collider experiments, for new physics beyond the Standard Model. While no signal has been seen so far, many analyses are reaching the point in which either a discovery will take place or strong limit on currently popular theories will be set. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Moduli dynamics is discussed in the scenario where gravitino is relatively heavy with mass of the order of 10 TeV, which is favored to relax the gravitino problem. Imposing a phenomenological requirement that CP phases in the gaugino masses do not arise from the conformal anomaly mediation, we find that the form of the superpotential for the modulus field is determined. Interestingly one solution is the sum of an exponential and a constant, which is identical to the one recently obtained by Kachru et al (KKLT). Supersymmetry breaking is discussed with this superpotential. In particular, it is shown that the soft supersymmetry breaking masses are admixture of the modulus mediation and the conformal anomaly mediation of supersymmetry breaking. The resulting mass spectrum is very characteristic. It is rather compact compared to the minimal supergravity or to the pure anomaly mediation, which is testable at future collider experiments. The higgsino mass parameter is expected to be small, and hence the lightest of the neutralinos, which is a candidate for dark matter of the universe, is an admixture of the gauinos and higgsinos. This has some impacts on dark matter searches. This talk is based on the work with Motoi Endo and Koichi Yoshioka. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

I summarize some recent work on supersymmetric neutralinos as candidates for cold Dark Matter in the Universe. This includes a new scan of mSUGRA parameter space, with special emphasis on neutralinos annihilating predominantly through exchange of the light CP-even Higgs boson, and on bounds on sparticle masses. Next, prospects of testing models with TeV higgsino-like Dark Matter at colliders are discussed. Finally, I briefly comment on extensions of the mSUGRA model, and on scenarios with non-standard cosmology. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Current supersymmetry searches at the Tevatron pp collider are reviewed. The Fermilab Tevatron with integrated luminosities now exceeding 1 fb-1 per experiment at a center-of-mass energy of 1.96 TeV is starting to test supersymmetric particle production at mass scales exceeding previous colliders. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

I present here a brief overview of supersymmetry theory as it pertains to collider physics. After a discussion of supersymmetric models and their constraints, I discuss prospects for supersymmetry at the DESY HERA, Fermilab Tevatron and CERN LHC colliders. I also compare with expectations for direct and indirect searches for neutralino dark matter. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

CMS and Atlas sensitivity to Standard Model Higgs boson discovery is discussed with the emphasis on aspects that could be verified by Tevatron experiments. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]