Quaero@H1: An Interface to High-pT HERA Event Data

Distributions from high-pT HERA event data analyzed in a general search for new physics at H1 have been incorporated into Quaero, an algorithm designed to automate tests of specific hypotheses with high energy collider data. The use of Quaero@H1 to search for leptoquarks, R-parity violating supersymmetry, and excited quarks provides examples to develop intuition for the algorithm's performance.Comment: Submitted to Eur. Phys. J.

Transverse momentum fluctuations in nuclear collisions at 158 AGeV

Results are presented on event-by-event fluctuations in transverse momentum of charged particles, produced at forward rapidities in p+p, C+C, Si+Si and Pb+Pb collisions at 158 AGeV. Three different characteristics are discussed: the average transverse momentum of the event, the Phi_pT fluctuation measure and two-particle transverse momentum correlations. In the kinematic region explored, the dynamical fluctuations are found to be small. However, a significant system size dependence of Phi_pT is observed, with the largest value measured in peripheral Pb+Pb interactions. The data are compared with predictions of several models. PACS numbers: 14.20.Jn, 13.75.Cs, 12.39.-

Lambda and Antilambda reconstruction in central Pb C Pb collisions using

The large acceptance time projection chambers of the NA49 experiment are used to record the trajectory of charged particles from Pb + Pb collisions at 158 GeV per nucleon. Neutral strange hadrons have been reconstructed from their charged decay products. To obtain distributions of Λ, and Ks0 in discrete bins of rapidity, y, and transverse momentum, pT, calculations have been performed to determine the acceptance of the detector and the efficiency of the reconstruction software as a function of both variables. The lifetime distributions obtained give values of cτ = 7.8 ± 0.6 cm for Λ and cτ = 2.5 ± 0.3 cm for Ks0, consistent with data book values

A new Coulomb correction method for Bose-Einstein correlations, based on the Pi+ Pi- correlation measurements

We present the measured correlation functions for pi+ pi-, pi- pi- and pi+ pi+ pairs in central S+Ag collisions at 200 GeV per nucleon. The Gamov function, which has been traditionally used to correct the correlation functions of charged pions for the Coulomb interaction, is found to be inconsistent with all measured correlation functions. Certain problems which have been dominating the systematic uncertainty of the correlation analysis are related to this inconsistency. It is demonstrated that a new Coulomb correction method, based exclusively on the measured correlation function for pi+ pi- pairs, may solve the problem

Improved description of Bose-Einstein Correlation function

The L3 data on Bose-Einstein correlations of equally charged pion pairs produced in hadronic Z decays are analyzed in terms of various parametrizations. Preliminary results are presented here.Comment: Presented at the RHIC School 04, 4th Budapest Winter School on Heavy Ion Physics, Budapest, Hungary, December 1-3, 2004. To be published in Acta Physica Hungarica Heavy Ion Physic

Strange Particle Production in p+p, p+Pb and Pb+Pb Interactions from NA49

Recent NA49 results on Lambda, Antilambda, Xi- and Antixi+ production in minimum bias p+p and centrality selected p+Pb collisions at 158 GeV/c, and the results on Lambda, Antilambda, K+ and K- production in central Pb+Pb collisions at 40, 80 and 158 A GeV are discussed and compared with other available data. By comparing the energy dependence of Lambda and Antilambda production at mid-rapidity a striking similarity is observed between p+p and A+A data. This is also seen in the energy dependence of the Lambda/pi ratio. K+/pi at mid-rapidity is affected in a similar way, due to the associated production of K+ together with Lambda particles. The observed yields increase faster than the number of wounded nucleons when comparing p+Pb to p+p. As already observed in A+A collisions, the increase is larger for multistrange than for strange baryons and for baryons than for anti-baryons.Comment: 8 pages, 10 figures, To appear in proceedings of Strange Quark in Matter 2001-A Flavourspace Odyssey, Frankfurt am Main, Germany, 24-29. Sept. 200

Resolved photon and multi-component model for γ∗\gamma^*p and γ∗γ∗\gamma^* \gamma^* scattering at high energies

We generalize our previous model for $\gamma^* p$ scattering to $\gamma \gamma$ scattering. In the latter case the number of components naturally grows. When using the model parameters from our previous $\gamma^* p$ analysis the model cross section for $\gamma \gamma$ scattering is larger than the corresponding LEP2 experimental data by more than a factor of two. However, performing a new simultaneous fit to $\gamma^* p$ and $\gamma \gamma$ total cross section we can find an optimal set of parameters to describe both processes. We propose new measures of factorization breaking for $\gamma^* \gamma^*$ collisions and present results for our new model.Comment: 23 pages, 10 figure

Decay rate asymmetry for B→XsγB \to X_s \gamma in SUSY model

We discuss a rate asymmetry for the radiative $B$-meson decay $B \to X_s \gamma$ within the framework of the supersymmetric standard model based on N=1 supergravity. This model contains new sources of CP violation. In spite of severe experimental constraints on the electric dipole moment of the neutron, a new CP-violating phase may not be suppressed, leading to a sizable enhancement of the decay rate asymmetry. The magnitude of the asymmetry is predicted to be larger than that by the standard model in wide parameter regions where the branching ratio is consistent with its experimental bounds. A possible maximal magnitude is about 0.1, which will be well accessible at B factories.Comment: 4 pages, Talk presented at the UK Phenomenology Workshop on Heavy Flavour and CP Violation, 17 - 22, September 2000, St John's College, Durha