Testing the mechanism for the LSP stability at the LHC

The lightest supersymmetric particle (LSP) is a natural candidate for the cold dark matter of the universe. In this Letter we discuss how to test the mechanism responsible for the LSP stability at the LHC. We note that if R-parity is conserved dynamically one should expect a Higgs boson which decays mainly into two right-handed neutrinos (a “leptonic” Higgs) or into two sfermions. The first case could exhibit spectacular lepton number violating signals with four secondary vertices due to the long-lived nature of right-handed neutrinos. These signals, together with the standard channels for the discovery of SUSY, could help to establish the underlying theory at the TeV scale.     

Wino LSP detection in the light of recent Higgs searches at the LHC

Recent LHC data showed excesses of Higgs-like signals at the Higgs mass of around 125 GeV. This may indicate supersymmetric models with relatively heavy scalar fermions to enhance the Higgs mass. The desired mass spectrum is realized in the anomaly-mediated supersymmetry breaking model, in which the Wino can naturally be the lightest superparticle (LSP). We discuss possibilities for confirming such a scenario, particularly detecting signals from Wino LSP at direct detection experiments, indirect searches at neutrino telescopes and at the LHC.     

SUSY at the LHC

I discuss part of the program of work towards discoveries at the LHC with seeds for orientation and navigation in the parameter space given an anticipated multitude of excesses at start-up.     

Supersymmetry at the LHC

The success of supersymmetry is beyond any doubt. With the availability of the precise measurement of the dark-matter content of the universe, SUSY models are used as cosmological connection to particle physics. We are now ready to verify this theory directly at the upcoming large hadron collider (LHC). It is possible to use the LHC measurements to reconstruct the SUSY model parameters. These parameters will then be used to calculate the relic density very precisely to be compared with the dark-matter content measured from the astrophysical measurements. In this review, I will summarize various search strategies which will be important to measure supersymmetry parameters in different models in order to establish the cosmological connection.     

Inelastic diffraction at the LHC

The relativistic scattering was one of the scientific fields where Academician V.G. Kadyshevsky has made an important and highly cited contribution [1]. In this paper we discuss the high-energy dependencies of diffractive and non-diffractive inelastic cross-sections in view of the recent LHC data which reveal a presence of the reflective scattering mode.     

Quantum gravity at the LHC

We study the production of massless gravitons at the LHC and compare our results to those obtained in extra-dimensional models. The signature in both cases is missing energy plus jets. In case of non-observation, the LHC could be used to put the tightest limit to date on the value of the Planck mass.     

Higgs bosons at the LHC

The investigation of the dynamics responsible for electroweak symmetry breaking is one of the prime tasks of the experiments at the CERN Large Hadron Collider (LHC). In this article, the potential of the ATLAS and CMS experiments for the discovery of a standard model Higgs boson and for Higgs bosons in the minimal supersymmetric extension is summarized. Emphasis is put on those studies which have been performed recently by the experimental collaborations using a realistic simulation of the detector performance. This includes a discussion of the search for Higgs bosons using the vector boson-fusion mode, a discussion on the measurement of Higgs boson parameters as well as a detailed review of the MSSM sector for different benchmark scenarios.     

Higgs searches at the LHC

We review the prospects for searches of the Standard Model Higgs boson at the LHC, based on detailed studies performed by the ATLAS and CMS Collaborations. The search channels and strategies are described, resulting in the assessment of the discovery potential for the two experiments. We discuss the prospects for measurements in the Higgs sector. To cite this article: A. De Roeck, G. Polesello, C. R. Physique 8 (2007).     

signal of NMSSM at the LHC

For the Benjamin Ono equation, the Hirota bilinear method and long wave limit method are applied to obtain the breathers and the rogue wave solutions. Bright and dark rogue waves exist in the Benjamin Ono equation, and their typical dynamics are analysed and illustrated. The semirational solutions possessing rogue waves and solitons are also obtained, and demonstrated by the three-dimensional figures. Furthermore, the hybrid of rogue wave and breather solutions are also found in the Benjamin Ono equation.     

Higgs physics at LHC

The large hadron collider (LHC) and its detectors, ATLAS and CMS, are being built to study TeV scale physics, and to fully understand the electroweak symmetry breaking mechanism. The Monte-Carlo simulation results for the standard model and minimal super symmetric standard model Higgs boson searches and parameter measurements are discussed. Emphasis is placed on recent investigations of Higgs produced in association with top quarks and in vector boson fusion channels. These results indicate that Higgs sector can be explored in many channels within a couple of years of LHC operation, i.e.,L = 30 fb⁻¹. Complete coverage including measurements of Higgs parameters can be carried out with full LHC program.     

On minimum-bias effects at the LHC

In general, minimum-bias triggers planned for experiments at the LHC miss a considerable fraction of the total number of events. We exemplify the rejection rate using the Durham model of soft high-energy interactions to obtain quantitative estimates of the signals arising from the ATLAS scintillation counters positioned in the rapidity intervals 2<|η|<4$2<|\eta |<4$, and also from TOTEM detectors covering the intervals 3.1<|η|<6.5$3.1<|\eta |<6.5$. Typically we find that the expected signal is about half of the total cross section, σtot${\sigma }_{\mathrm{tot}}$. We also calculate the cross section for the so-called zero-bias measurement planned by CMS in the extended rapidity interval −5<η<7$-5<\eta <7$. We emphasize that only models which give satisfactory predictions for the measured minimum-bias or zero-bias cross sections can be used to obtain the value of the total inelastic cross section.     

Long-lived unstable superparticles at the LHC

In various models of supersymmetry (SUSY), the lightest superparticle in the minimal SUSY standard model sector, which we call MSSM-LSP, becomes unstable. Then, we may observe the decay of the MSSM-LSP in the detector at the LHC experiment. We show that the discovery of such a decay process (and the determination of the lifetime of the MSSM-LSP) may be possible at the LHC even if the decay length of the MSSM-LSP is much longer than the size of the detector; sizable number of the MSSM-LSPs decay inside the detector if the lifetime is shorter than 10^−(3–5) s. We also discuss the implications of the study of the MSSM-LSP decay for several well-motivated SUSY models.     

The ALICE experiment at the LHC

A free-energy function is constructed, which couples strain and magnetic moments in ferromagnetic shape memory alloys. The associated Gibbs function is used to calculate time-dependent transition probabilities between martensite variants in a magnetic field under applied stress. By keeping track of the variant fractions, the evolution of strain and magnetization is determined. The simulation model is built in a finite element program for structural analysis, in order to simulate magnetic field-dependent strain and magnetization characteristics of a test actuator. The influence of material parameters and sample geometry is discussed.