Probing the light neutral Higgs boson scenario of the CP-violating MSSM Higgs sector at the LHC
In the CP-violating minimal supersymmetric standard model (MSSM), for certain values of the CP-violating phases associated to the universal trilinear couplings (At, Ab) and the gluino mass $(M_{\tilde g})$, e.g., $\Phi_{{CP}} = 60^\circ$ or $90^\circ$, for $
M_{{H^{ + } }} \lesssim 140%
$ GeV and $\tan \beta \sim 2$-5, the lightest Higgs boson mass ($
M_{{H_{1} }} 
$
) is $
 \lesssim 50%
$ GeV. This mass interval is still allowed by results of standard LEP Higgs searches because of a strongly suppressed H1ZZ coupling. However, in the same region of parameter space in which these two conditions occur, the $H_1 H^\mp W^\pm $ coupling is enhanced because the two mentioned sets of couplings satisfy a sum rule. In this paper we probe such a light Higgs scenario at the Large Hadron Collider (LHC) by studying $H^\pm H_1$ associate production, leading to a $
4b + {\ell }^{ \pm } + \not{E}_{{\text{T}}} %
$
 signal. We show that the latter is readily accessible at the CERN hadron collider, upon the application of suitable selection cuts against the standard model (SM) backgrounds. Our parton level Monte Carlo (MC) analysis yields $\sim 15$-45 signal events, completely free of SM background, for ${\cal L} = 10$- 30 fb-1 of accumulated luminosity, after taking into account the overall efficiency for tagging four b-jets.

title: Signals for gauge mediated supersymmetry breaking model at an e−e− collider
abstract: We study the pair-production and decay of right handed selectrons within a Gauge Mediated Supersymmetry Breaking Model in polarised e−e− interaction. Detailed analyses of the possible signals and backgrounds are performed for a few selected points in the parameter space. A judicious choice for polarisation of the initial electron beam helps eliminate almost the entire Standard Model background. We also show that phase space distributions can be used to distinguish such a supersummetry breaking scheme from the supergravity inspired models.

title: Constraining anomaly mediated supersymmetry breaking framework via ongoing muon g − 2 experiment at Brookhaven
abstract: The ongoing high precision E821 Brookhaven National Laboratory experiment on muon $g\ensuremath{-}2$ is promising to probe a theory involving supersymmetry. We have studied the constraints on the minimal anomaly mediated supersymmetry breaking (AMSB) model using the current data of muon $g\ensuremath{-}2$ from Brookhaven. A scenario of seeing no deviation from the standard model is also considered, within a $2\ensuremath{\sigma}$ limit of the combined error from the standard model result and the Brookhaven predicted uncertainty level. The resulting constraint is found to be complementary to what one obtains from $\stackrel{\ensuremath{\rightarrow}}{b}s+\ensuremath{\gamma}$ bounds within the AMSB scenario, since only a definite sign of $\ensuremath{\mu}$ is effectively probed via $\stackrel{\ensuremath{\rightarrow}}{b}s+\ensuremath{\gamma}.$ A few relevant generic features of the model are also described for disallowed regions of parameter space.

title: Working group report: Physics at the Large Hadron Collider
abstract: This is a summary of the activities of the Physics at the LHC working group in the XIth Workshop on High Energy Physics Phenomenology (WHEPP-XI) held at the Physical Research Laboratory, Ahmedabad, India in January 2010. We discuss the activities of each sub-working group on physics issues at colliders such as Tevatron and Large Hadron Collider (LHC). The main issues discussed involve (1) results on W mass measurement and associated QCD uncertainties, (2) an attempt to understand the asymmetry measured at Tevatron in the top quark production, and (3) phenomenology of warped space dimension model.

title: Invisible decays of Higgs and other mesons in models with singlet neutrinos in large extra dimensions
abstract: In light of current atmospheric neutrino oscillation data, we revisit the invisible decay of the standard model Higgs boson and other pseudoscalar mesons which can be enhanced because of large number of KK modes in models with right-handed singlet neutrinos in large extra dimensions. We find that the invisible decay rate of Higgs can be as large as H→b b decay rate only for a very restricted region of parameter space. This parameter space is even further restricted if one demands that the dimensionless neutrino Yukawa coupling λ is O (1). We have also studied the scenarios where singlet neutrino propagate in a sub-space, which lowers the string scale M ∗ and keeps neutrino Yukawa coupling O (1). We have also considered decays of other spin-0 mesons to ν ν and found the rates to be too small for measurement.

title: Study of single sneutrino production in association with fermion pairs at polarized photon colliders
abstract: We investigate single sneutrino production in the context of R-parity-violating supersymmetry at future ?? linear colliders. The sneutrino is produced in association with fermion pairs and it is shown that its decays into two further fermions will lead to a clean signal. We also discuss possible standard model backgrounds and the effects of beam polarization.

title: Fluctuations of rapidity gaps in nucleus nucleus collisions: Evidence of erraticity
abstract: The fluctuations of the spatial pattern from event to event have been investigated by analyzing the data of multipion production ${\mathrm{in}}^{24}\mathrm{Mg}\ensuremath{-}\mathrm{AgBr}$ interactions ${\mathrm{and}}^{12}\mathrm{C}\ensuremath{-}\mathrm{AgBr}$ interactions at $4.5A\mathrm{GeV}$ and ${}^{16}\mathrm{O}\ensuremath{-}\mathrm{AgBr}$ interactions at $2.1A\mathrm{GeV}$ and $60A\mathrm{GeV}.$ Two entropylike quantities ${S}_{q}$ and ${\ensuremath{\Sigma}}_{q}$ have been estimated from two different moments of rapidity gaps of produced pions. The investigation provides evidence of the erraticity of rapidity gaps of produced pions in relativistic nuclear collisions.

title: Multiplicity scaling of target protons in high-energy nucleus-nucleus and hadron-nucleus interactions
abstract: Multiplicity scaling of target protons emitted from nucleus?nucleus (16O?AgBr interactions at 2.1 AGeV and 32S?AgBr interactions at 200 AGeV), pion?nucleus (???AgBr interactions at 350 GeV/c) and proton?nucleus interactions (p?AgBr interactions at 200 GeV/c) has been investigated. The experimental points are found to lie approximately on the curve described by ?(z) = Azexp?( ? Bz) with A = 3.36 ? 0.19 and B = 1.74 ? 0.06 for all the four interactions. A comparison of the fit with the function ?(z) = (Az + Bz3 + Cz5 + Dz7)exp?( ? Ez) has also been performed.

title: Rapidity dependence of multiplicity fluctuations and correlations in high-energy nucleus–nucleus interactions
abstract: The multiplicity fluctuations of the produced pions were studied using scaled variance method in 16O–AgBr interactions at 2.1 AGeV, 24Mg–AgBr interactions at 4.5 AGeV, 12C–AgBr interactions at 4.5 AGeV, 16O–AgBr interactions at 60 AGeV and 32S–AgBr interactions at 200 AGeV at two different binning conditions. In the first binning condition, the rapidity interval was varied in steps of one centring about the central rapidity until it reached 14. In the second case, the rapidity interval was increased in steps of 1.6 up to 14.4. Multiplicity distributions and their scaled variances were presented as a function of the dependence on the rapidity width for both the binning conditions. Multiplicity fluctuations were found to increase with the increase of rapidity interval and later found to saturate at larger rapidity window for all the interactions and in both the binning conditions. Multiplicity fluctuations were found to increase with the energy of the projectile beam. The values of the scaled variances were found to be greater than one in all the cases in both the binning conditions indicating the presence of correlation during the multiparticle production process in high-energy nucleus–nucleus interactions. Experimental results were compared with the results obtained from the Monte Carlo simulated events for all the interactions. The Monte Carlo simulated data showed very small values of scaled variance suggesting very small fluctuations for the simulated events. Experimental results obtained from 16O–AgBr interactions at 60 AGeV and 32S–AgBr interactions at 200 AGeV were compared with the events generated by Lund Monte Carlo code (FRITIOF model). FRITIOF model failed to explain the multiplicity fluctuations of pions emitted from 16O–AgBr interactions at 60 AGeV for both the binning conditions. However, the experimental data agreed well with the FRITIOF model for 32S–AgBr interactions at 200 AGeV.

title: Quantitative estimate of pion fluctuation and its multiplicity dependence in nuclear collisions
abstract: This paper presents the results of an investigation on the multiplicity dependence of the fluctuation pattern of pions for the entire accelerator energy range from 2.1 to 200 AGeV. The data set for produced pions is divided into four sets depending on the number of shower tracks ns. Analysis is carried out in two-dimensional η– space with the Hurst exponent to take care of the anisotropy of the phase space. The Hurst exponent is extracted by fitting one-dimensional factorial moment saturation curves to Ochs' saturation formula. The values of the effective fluctuation strength α eff are estimated and multiplicity dependence is studied w.r.t. α eff and the Hurst exponent H. It is highly interesting to observe that both fluctuation strength and degree of anisotropy (characterized by H) depend on pion multiplicity. The multiplicity dependence is more pronounced at lower projectile energy. The results of the study are discussed in detail.

title: Multiplicity fluctuations of pions and protons at SPS energy — An in-depth analysis with factorial correlator
abstract: We compute the factorial correlators to study the dynamical fluctuations of pions and a combination of pions and protons (compound multiplicity) in 32S-AgBr interactions at 200 A GeV. The study reveals that for both pion and compound multiplicity the correlated moments increase with the decrease in bin-bin separation D, following a power-law, which suggests the self-similarity of multiplicity fluctuation in each case. The results of the analysis also show a consistency with the prediction of α-model for the existence of intermittency in both cases.