Study of Rapidity Gap Events in Hadronic Z Decays with L3 detector

Rapidity gaps have been studied in well separated completely symmetric 3 jet events from hadronic Z decays to search for colour singlet exchange. Asymmetries in particle flow and angular separation, defined with respect to the inter-jet regions, are found to be sensitive to the exchange of a colour singlet object instead of a colour octet gluon. %Comparing data from the L3 experiment with Monte Carlo predictions, %a limit is obtained on the fraction %of colour singlet exchange in data. From a comparison of the distributions observed in the L3 experiment and Monte Carlo predictions, a limit is obtained on the fraction of colour singlet exchange in data.Comment: 4 pages, 7 figures (in eps) talk given at XXXI International Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China. see http://ismd31.ccnu.edu.cn

Search for a Light Higgs Boson at BaBar

We search for evidence of a light Higgs boson (A0) in the radiative decays of the narrow Upsilon(3S) resonance: Upsilon(3S) -> gamma A0, where A0 -> invisible or A0 -> mu+mu-. Such an object appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in a sample of 122 million Upsilon(3S) decays collected by the BaBar collaboration at the PEP II B-factory, and set 90% C.L. upper limits on the product of the corresponding branching fractions. We also set a limit on the di-muon branching fraction of the recently discovered eta_b meson.Comment: 8 pages, 4 figures. To appear in the proceedings of Les Rencontres de Physique de la Valle'e d'Aoste held at La Thuile, Italy from 1-7 March 200

Lepton Flavor Violation in tau decays at BaBar

Searches for lepton flavor violating tau -> l gamma, tau -> lll and tau -> lhh decays at the BaBar experiment are presented. Upper limits on the branching ratios are obtained at the level of 10^{-7} at 90% confidence level.Comment: To appear in the proceedings of XII Lomonosov Conference on Elementary Particle Physics, Moscow, Russia (25 - 31 August 2005

Ascertaining the spin for new resonances decaying into tau+ tau- at Hadron Colliders

Evidence of a new particle with mass ~125 GeV decaying into a pair of tau leptons at the Large Hadron Collider spurs interest in ascertaining its spin in this channel. Here we present a comparative study between spin-0 and spin-2 nature of this new particle, using spin correlations and decay product directions. The TauSpinner algorithm is used to re-weight distributions from qqbar -> gamma/Z -> tau+ tau- sample to simulate a spin-2 state exchange. The method is based on supplementing the Standard Model matrix elements with those arising from presence of a new interaction. Studies with simulated samples demonstrate the discrimination power between these spin hypotheses based on data collected at the Large Hadron Collider.Comment: 17 pages, 16 encapsulated postscript figure

K-Long Identification Efficiency of the KLM Detector in the Belle II Experiment Using sPlot

Long-lived neutral kaon mesons (neutral K-longs) are identified by energy deposits in the KLM detector of the Belle II experiment. However, various other particles can also deposit energy in the KLM detector. A statistical method known as sPlot can be utilized to distinguish between the energy deposit patterns of neutral K-longs vs. other backgrounds. This technique, currently developed with Monte-Carlo events, allows for a more robust determination of K-long identification efficiency in the KLM detector, which can eventually be applied on real data