123551661
Entropy scaling in high-energy nucleus–nucleus interactions
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.
123012389
Multiplicity fluctuations of pions and protons at SPS energy — An in-depth analysis with factorial correlator
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.
118199521
Evidence of different reaction mechanisms for hot and cold events in relativistic heavy-ion interaction
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.
119866414
Evidence of scaling of void probability in nucleus-nucleus interactions at few GeV energy
The rapidity gap probability in the ${}^{24}\mathrm{M}\mathrm{g}\ensuremath{-}\mathrm{A}\mathrm{g}\mathrm{B}\mathrm{r}$ interaction at $4.5\mathrm{GeV}/c/\mathrm{nucleon}$ has been studied in detail. The data reveal scaling behavior of the void probability in the central rapidity domain which confirms the validity of the linked-pair approximation for the $N$-particle cumulant correlation functions. This scaling behavior appears to be similar to the void probability in the Perseus-Pisces supercluster region of galaxies.
120905653
NON-STATISTICAL FLUCTUATIONS OF PIONS FOR RING- AND JET-LIKE EVENTS AT CERN SPS ENERGY — AN IN-DEPTH ANALYSIS WITH FACTORIAL CORRELATOR
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.
122068137
MULTIPLICITY DISTRIBUTION AND MULTIPLICITY MOMENT OF BLACK AND GREY PARTICLES IN HIGH ENERGY NUCLEUS–NUCLEUS INTERACTIONS
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.
13886879
Constraints on supersymmetric flavor changing parameters using B ---> PP decays
We study contributions of quark-squark-gluino interactions in Minimal Supersymmetric Standard Model (MSSM) to B->PP (PP =Kpi, pipi, KK) decays using QCD improved factorization method for the evaluation of the hadronic matrix elements and taking into account renormalization group running of the Wilson coefficients from SUSY scale (~ m_{\tilde q}) to the low energy scale (= m_b) applicable to B decays. Using the most recent experimental data we obtain constraints on flavor changing Supersymmetric (SUSY) parameters (\delta_{ij})_{LL, RR}. For \Delta S = -1 processes, b-> s gamma is usually considered to give the strongest limits. We, however, find that in some part of the parameter space B-> Kpi processes give stronger bounds. Implications for B^0_s -\bar B^0_s mixing is discussed. We also study cons traints obtained from \Delta S = 0 processes B-> pipi, KK, rho gamma and B_d -\bar B_d mixing. In this case, in a large part of the parameter space B_d - \bar B_d provides the best bound, but B-> K^- K^0, rho gamma can still give interesting constraints in a complementary region of the parameter space.
59023381
Single electron signal from anomaly mediated supersymmetry breaking at a future linear collider
Understanding how Supersymmetry (SUSY) breaks in the real world from a deeper, more fundamental standpoint is a major challenge in theoretical high energy physics today. An interesting recent idea in this direction has been that of Anomaly Mediated SUSY Breaking (AMSB) [1] – [15]. AMSB occurs when, in a higher dimension, one has a Supergravity theory defined on two separated parallel 3-branes (3+1 dimensional subspaces) in a way that the Standard Model (SM) particles are localized on one of these while the SUSY breaking sector is localized on the other. There are no tree-level couplings between these two branes. Gravity propagates in the bulk and the breakdown of SUSY is communicated from the hidden sector to the visible one through the loopinduced super-Weyl anomaly. In the absence of tree-level interactions between the two 3-branes, this is the dominant contribution to the soft SUSY breaking parameters. All the masses (of gauginos and scalars) generated through this mechanism are proportional to the corresponding gauge coupling strengths. In fact, these masses become renormalization group invariant with slepton becoming tachyonic. The latter fact is the most severe problem in the AMSB scenario and there are several proposals in the literature to solve it. We shall focus here on the minimal [1] model of AMSB where the problem of tachyonic sleptons is tackled by adding a universal constant term m 0 to the expressions for squared scalar masses, i.e., m 2 0 contributes equally to the squared masses of all scalars present in the theory. One can now solve the tachyonic slepton problem through a suitably chosen m 0 making all squared slepton masses positive, the scale invariance of the expressions for scalar masses being lost. The evolution of scalar masses governed by the corresponding Renormalization Group Equations (RGEs), starting from a very high energy scale, must therefore be taken into account. However, except for the addition of an extra parameter, this is quite a feasible procedure. This model is characterized by several distinct features with important phenomenological consequences: a rather massive gravitino (∼ a few TeV) and nearly mass-degenerate left and right selectrons and smuons, while the staus split into two distinct mass eigenstates with the τ1 being the lightest charged slepton. Most importantly, the model has gauginomasses proportional to the β-functions of the gauge couplings. The latter lead to the existence of a neutral near-Wino as the Lightest Supersymmetric Particle (LSP) χ 1 and closely mass-degenerate with it a pair of charged near-Winos as the lighter charginos χ± 1 . A tiny mass difference ∆M (< 1 GeV) arises between them from loop corrections and a weak gaugino-higgsino mixing at the tree level. Because of the
118612245
R -parity violating supersymmetric explanation for the CDF W j j excess
Recently CDF has reported a 4.1 sigma excess in the distribution of the dijet invariant mass between 120-160 GeV in Wjj event sample in 7.3 fb^{-1} of data, which has generated considerable interest. We offer a possible explanation of this observation in the general framework of MSSM with R-parity violation through resonance production of tau sneutrino decaying into the LSP stau_1 and W boson. We also give the predictions of this scenario for the LHC operating at 7 TeV center of mass energy.
118491867
Ultrarelativistic sneutrinos at the LHC and sneutrino-antisneutrino oscillations
Sneutrino-antisneutrino oscillation can be a very useful probe to look for signatures of lepton number violation (ΔL = 2) at the LHC. Here, we discuss the effect of the Lorentz factor γ and the travelling distance L on the probability of the oscillation. We demonstrate that these two parameters can significantly alter the probability of the oscillation when the sneutrinos are ultrarelativistic and have a very small total decay width. We propose a scenario where these requirements are fulfilled and which produces interesting signals at the LHC even for a mass splitting Δm as small as 10 -14 GeV between the sneutrino mass eigenstates.
119238804
Sneutrino-antisneutrino oscillation at the Tevatron
Sneutrino-antisneutrino oscillation can be a very useful probe to look for signatures of lepton number violation ({Delta}L=2) at the Tevatron. Here, we discuss a scenario where the total decay width of the sneutrino is very small, producing interesting signals at the Tevatron for a mass splitting {Delta}m as small as 10{sup -14} GeV between the sneutrino mass eigenstates.