Quantitative estimate of pion fluctuation and its multiplicity dependence in nuclear collisions
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: NON-STATISTICAL FLUCTUATIONS OF PIONS FOR RING- AND JET-LIKE EVENTS AT CERN SPS ENERGY — AN IN-DEPTH ANALYSIS WITH FACTORIAL CORRELATOR
abstract: This study reveals the analysis of ring-like and jet-like events in terms of factorial correlations of 16O–Ag/Br interactions at 60A GeV. The investigation revealed that the correlated moments are found to increase with decreasing bin–bin separation D and follows a power-law which suggests the presence of an intermittent nature of self-similar dynamical fluctuations pattern for ring-like and jet-like events. From the analysis we find that for jet-like events the strength of non-statistical fluctuation is greater than the ring-like and total event set. Jet-like events follow the bin size independence according to α model of intermittency as like total events, whereas ring-like events are not consistent with the prediction of α model of intermittency.

title: MULTIPLICITY DISTRIBUTION AND MULTIPLICITY MOMENT OF BLACK AND GREY PARTICLES IN HIGH ENERGY NUCLEUS–NUCLEUS INTERACTIONS
abstract: In this paper we have studied the multiplicity distribution of black and grey particles emitted from 16O–AgBr interactions at 2.1 AGeV and 60 AGeV. We have also calculated the multiplicity moment up to the fifth order for both the interactions and for both kinds of emitted particles. The variation of multiplicity moment with the order number has been investigated. It is seen that in the case of black particles multiplicity moment up to fourth order remains almost constant as energy increases from 2.1 AGeV to 60 AGeV. Fifth order multiplicity moment increases insignificantly with energy. However in the case of grey particles no such constancy of multiplicity moment with energy of the projectile beam is obtained. Later we have extended our study on the basis of Regge–Mueller approach to find the existence of second order correlation during the emission of black as well as the grey particles. The second Mueller moment is found to be positive and it increases as energy increases in the case of black particles. On the contrary in the case of grey particles the second Mueller moment decreases with energy. It can be concluded that as energy increases correlation among the black particles increases. On the other hand with the increase of energy correlation among the grey particles is found to diminish.

title: Evidence of different reaction mechanisms for hot and cold events in relativistic heavy-ion interaction
abstract: This paper reports evidence of different reaction mechanisms for two classes of events, ''hot,'' and ''cold,'' in /sup 12/C emulsion at 4.5 (GeV/c)/N observed by Ghosh et al., from a comparison of the transverse-momentum (P/sub T/) distribution with a mixture of two Maxwell-Boltzmann distributions with different temperatures. The hypothesis is substantiated by the significant difference, for ''hot'' and ''cold'' events, in the values of the average number of pions produced, average emission angle of ..cap alpha..-projectile fragments, and ratio of yield of ..cap alpha.. particles to protons as projectile fragments.

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.

title: Entropy scaling in high-energy nucleus–nucleus interactions
abstract: We studied the multiparticle production in high-energy nucleus–nucleus interactions in terms of particle entropy in 16O–AgBr and 32S–AgBr interactions at 60 A GeV and 200 A GeV, respectively. An approximate scaling behavior of total produced entropy normalized to maximum rapidity in the center of mass frame measured in different rapidity bins has been reported. The scaling behavior is not supported either by the FRITIOF model or by the Monte Carlo simulated events.

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: Using Jet Substructure at the LHC to Search for the Light Higgs Bosons of the CP-Violating MSSM
abstract: The CP-violating version of the Minimal Supersymmetric Standard Model (MSSM) is an example of a model where experimental data do not preclude the presence of light Higgs bosons in the range around 10 -- 110 GeV. Such light Higgs bosons, decaying almost wholly to b-bbar pairs, may be copiously produced at the LHC, but would remain inaccessible to conventional Higgs searches because of intractable QCD backgrounds. We demonstrate that a significant number of these light Higgs bosons would be boosted strongly enough for the pair of daughter $b$-jet pairs to appear as a single `fat' jet with substructure. Tagging such jets could extend the discovery potential at the LHC into the hitherto-inaccessible region for light Higgs bosons.

title: Observing CP violating MSSM Higgs bosons at hadron colliders
abstract: We report on the possibility of observing Higgs sector CP violation of the minimal supersymmetric standard model at a hadron machine. The CP phase dependent cross-sections for the VH i associated production processes are given for the Fermilab Tevatron and CERN LHC. Substantial production cross-sections for channels of all three Higgs bosons simultaneously are shown to be possible, giving a direct indication of the CP violation. The observability of the Higgs signals are discussed.

title: MSSM in view of PAMELA and Fermi-LAT
abstract: We take the MSSM as a complete theory of low energy phenomena, including neutrino masses and mixings. This immediately implies that the gravitino is the only possible dark matter candidate. We study the implications of the astrophysical experiments such as PAMELA and Fermi-LAT, on this scenario. The theory can account for both the realistic neutrino masses and mixings, and the PAMELA data as long as the slepton masses lie in the 500 − 106 TeV range. The squarks can be either light or heavy, depending on their contribution to radiative neutrino masses. On the other hand, the Fermi-LAT data imply heavy superpartners, all out of LHC reach, simply on the grounds of the energy scale involved, for the gravitino must weigh more than 2TeV. The perturbativity of the theory also implies an upper bound on its mass, approximately 6 −

title: Summary of the Activities of the Working Group I on High Energy and Collider Physics
abstract: This is a summary of the projects undertaken by the Working Group I on High Energy Collider Physics at the Eighth Workshop on High Energy Physics Phenomenology (WHEPP8) held at the Indian Institute of Technology, Mumbai, January 5-16, 2004. The topics covered are (i) Higgs searches (ii) supersymmetry searches (iii) extra dimensions and (iv) linear collider.