Xi and AntiXi production in Pb+Pb collisions at 40 AGeV at CERN SPS

First results on the production of Xi and AntiXi hyperons in Pb+Pb interactions at 40 AGeV are presented. The AntiXi/Xi ratio at midrapidity is studied as a function of collision centrality. The ratio shows no significant centrality dependence within statistical errors; it ranges from 0.07 to 0.15. The AntiXi/Xi ratio for central Pb+Pb collisions increases strongly with the collision energy.Comment: 6 pages, 6 figures, proceedings of SQM03, to be published in Journal of Physics G; V2: changes in table 1 and figure

Graviton production with 2 jets at the LHC in large extra dimensions

We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plus missing transverse momentum signatures at the LHC. We make predictions for both the signal and the dominant Zjj and Wjj backgrounds, where we introduce missing P_T-dependent jet selection cuts that ensure the smallness of the 2-jet rate over the 1-jet rate. With the same jet selection cuts, the distributions of the two jets and their correlation with the missing transverse momentum provide additional evidence for the production of an invisible massive object.Comment: 8 pages, 10 figures, 1 table; Version to be printed in JHE

Lepton Polarization Asymmetry in B\to\ell^{+}\ell^{-} decay Beyond the Standard Model

The lepton polarization asymmetry in the B\to\ell^{+}\ell^{-} decay, when one of the leptons is polarized, is investigated using the most general form of the effective Hamiltonian. The sensitivity of the asymmetry to the new Wilson coefficients is studied.Moreover, correlations between the lepton polarization asymmetry and the branching ratio is studied. It is observed that, there are not exist such regions of new Wilson coefficients, which the value of branching ratio coincides with SM result while the lepton polarization does not, i.e new physics effects can be established by studying lepton polarization only.Comment: 9 pages,4 figure

Omega and AntiOmega production in Pb+Pb and p+p collisions at 30, 40 and 158 AGeV

We report preliminary results on Omega and AntiOmega production in central Pb+Pb collisions at 30, 40 and 158 AGeV and p + p interactions at 158 GeV. The midrapidity AntiOmega/Omega ratio is estimated to be 0.45 +- 0.05 and 0.41 +- 0.18 for central Pb+Pb collisions at 158 and 40 AGeV, respectively. The corresponding value for 158 GeV p+p interactions is 0.67 +- 0.62. For central Pb+Pb collisions at 158 AGeV fully corrected distributions are obtained. The inverse slope parameters of the transverse mass spectrum and total yields are T(Omega) = 276 +- 23 MeV, = 0.47 +- 0.07 and T(AntiOmega) = 285 +- 39 MeV, = 0.15 +- 0.02.Comment: Contribution to the proceedings of "Strangeness in Quark Matter 2003" (March 2003, Atlantic Beach NC, USA), to be published in Journal of Physics G., 6 pages, 6 figure

Experimental Precision Tests for the Electroweak Standard Model

This paper contains a review of recent precision measurements of electroweak observables and resulting tests of the electroweak Standard Model.Comment: 78 page

Leptonic CP violation: zero, maximal or between the two extremes

Discovery of the CP-violation in the lepton sector is one of the challenges of the particle physics. We search for possible principles, symmetries and phenomenological relations that can lead to particular values of the CP-violating Dirac phase, $\delta$. In this connection we discuss two extreme cases: the zero phase, $\delta = 0$, and the maximal CP-violation, $\delta = \pm \pi/2$, and relate them to the peculiar pattern of the neutrino mixing. The maximal CP-violation can be related to the $\nu_\mu - \nu_\tau$ reflection symmetry. We study various aspects of this symmetry and introduce a generalized reflection symmetry that can lead to an arbitrary phase that depends on the parameter of the symmetry transformation. The generalized reflection symmetry predicts a simple relation between the Dirac and Majorana phases. We also consider the possibility of certain relations between the CP-violating phases in the quark and lepton sectors.Comment: 34 pages, no figures; v3: version appeared in JHE

Neutrino Physics, Superbeams, and the Neutrino Factory

We summarize what has been learned about the neutrino mass spectrum and neutrino mixing, identify interesting open questions that can be answered by accelerator neutrino facilities of the future, and discuss the importance and physics of answering them.Comment: To appear in the Proceedings of the 4th International Workshop on Neutrino Factories (Nu Fact 02). LaTeX, 10 pages, 1 eps figur

Effects to Scalar Meson Decays of Strong Mixing between Low and High Mass Scalar Mesons

We analyze the mass spectroscopy of low and high mass scalar mesons and get the result that the coupling strengths of the mixing between low and high mass scalar mesons are very strong and the strengths of mixing for $I=1, 1/2$ scalar mesons and those of I=0 scalar mesons are almost same. Next, we analyze the decay widths and decay ratios of these mesons and get the results that the coupling constants $A'$ for $I=1, 1/2$ which represents the coupling of high mass scalar meson $N'$ -> two pseudoscalar mesons $PP$ are almost same as the coupling $A'$ for the I=0. On the other hand, the coupling constant $A$ for $I=1, I=1/2$ which represents the low mass scalar meson $N$ -> $PP$ are far from the coupling constant $A$ for I=0. We consider a resolution for this discrepancy. Coupling constant $A''$ for glueball $G$ -> $PP$ is smaller than the coupling $A'$. $\theta_P$ is $40^\circ \sim 50^\circ$.Comment: 15 pages, 6 figure

A "Littlest Higgs" Model with Custodial SU(2) Symmetry

In this note, a ``littlest higgs'' model is presented which has an approximate custodial SU(2) symmetry. The model is based on the coset space $SO(9)/(SO(5)\times SO(4))$. The light pseudo-goldstone bosons of the theory include a {\it single} higgs doublet below a TeV and a set of three $SU(2)_W$ triplets and an electroweak singlet in the TeV range. All of these scalars obtain approximately custodial SU(2) preserving vacuum expectation values. This model addresses a defect in the earlier $SO(5)\times SU(2)\times U(1)$ moose model, with the only extra complication being an extended top sector. Some of the precision electroweak observables are computed and do not deviate appreciably from Standard Model predictions. In an S-T oblique analysis, the dominant non-Standard Model contributions are the extended top sector and higgs doublet contributions. In conclusion, a wide range of higgs masses is allowed in a large region of parameter space consistent with naturalness, where large higgs masses requires some mild custodial SU(2) violation from the extended top sector.Comment: 22 pages + 8 figures; JHEP style, added references and extra discussion on size of T contributions, as well as some other minor clarifications. Version to appear in JHE

Closed-flavor pi + J/psi and pi + Upsilon Cross Sections at Low Energies from Dipion Decays

The scale of low energy c-cbar and b-bbar cross sections on light hadrons is of great importance to searches for the quark gluon plasma using the heavy-quarkonium suppression signature. Unfortunately, little is known about these near-threshold cross sections at present, and recent theoretical estimates span many orders of magnitude. Here we use experimental data on the four observed closed-flavor heavy quarkonium hadronic decays psi' -> pi pi J/psi, Upsilon' -> pi pi Upsilon, Upsilon'' -> pi pi Upsilon and Upsilon'' -> pi pi Upsilon', combined with simple models of the transition amplitudes, to estimate the pion scattering cross sections of c-cbar and b-bbar mesons near threshold. Specifically we consider the closed-flavor reactions pi J/psi -> pi psi', pi Upsilon -> pi Upsilon', pi Upsilon -> pi Upsilon'' and pi Upsilon' -> pi Upsilon'' and their time-reversed analogues. Our results may be useful in constraining theoretical models of the strong interactions of heavy quarkonia, and can be systematically improved through future detailed studies of dipion decays, notably psi' -> pi pi J/psi and Upsilon'' -> pi pi Upsilon.Comment: 6 pages, 6 figure