118421849
Tau physics from LEP
We briefly review recent analysis on the tau lepton by four LEP experiments, ALEPH, DELPHI, L3 and OPAL, based on data samples generated at the Z peak. Intrinsic properties of the tau lepton as well as applications to various physics topics are treated from an experimental point of view. The summarized analysis subjects include lifetime, leptonic branching ratios, hadronic decay structures, dipole moments, related electroweak and QCD properties, and the mass of the tau neutrino.
118099621
A measurement of the polarization asymmetry of the tau lepton using the L3 detector at LEP
With a data sample of e e events collected in the L detector at LEP during we did a measurement of the polarization of leptons as a function of the production polar angle with respect to the incident e beam direction We used the following prong decay channels e e and a As the result we obtained the asymmetries A and Ae Combining this with the previous data measurement by L we ob tained A and Ae These asymmetries gave the ratio of vector to axial vector weak neutral coupling con stants for electrons as g V g e A and for taus as g V g A The numbers are consistent with the hypothesis of e lepton universality Assuming the e neutral current universality the e ective electroweak mixing angle is calculated as sin e w Advisor Professor Aihud Pevsner
15045352
A review of charm semileptonic decays
Several high energy experiments have been actively pursuing the analyzes of semileptonic decays of charm mesons, resulting in numerous new results and publications. In this report, we summarize the recent efforts on the topics of pseudoscalar and vector charm semileptonic decays, especially in the area of branching fractions and form factor measurements.
119679827
RECENT FOCUS RESULTS ON CHARM MIXING
We present the recent result on CP mixing based on a high statistics photoproduced charm sample collected by the FOCUS experiment. We compare the lifetimes of two neutral D meson decays: D0→K- π+ and D0→K-K+. A mixing parameter for the neutral D system (yCP) is obtained under the assumption that K-π+ is an equal mixture of CP odd and even eigenstates.
197461838
A measurement of tau polarization at LEP
With a data sample of 86000 tau pairs collected in 1990 - 1993 the authors have measured the polarization of tau-leptons as a function of the production polar angle. They obtain for the ratio of vector to axial-vector weak neutral couplings for electrons g{sub Ve}/g{sub Ae}=0.0791{+-}0.0099(stat) {+-}0.0025 (syst) and taus g{sub V{tau}}/g{sub A{tau}} = 0.0752 {+-}0.063(stat){+-}0.0045(syst) consistent with the hypothesis of e - {tau} universality. Assuming universality of the e-{tau} neutral current the authors determine the effective electroweak mixing angle to be sin{sup 2}{theta}{sub W}{sup eff}=0.2309{+-}0.0016.
5633838
Recent Results on CP Lifetime Differences of Neutral D Mesons
The mixing parameter y_cp for the neutral D system can be obtained by comparing the lifetimes of CP eigenstate decays of the D mesons. Recent results on the lifetime differences from the Belle, CLEO, FOCUS(E831) experiments are summarized in this article. The neutral D decay modes analyzed by the experiments are: The D0->Kpi mode with the assumption that it is an equal mixture of CP even and odd eigenstates, and the CP even modes D0->KK and D0->pipi.
117090485
Parity Violation in Elastic Scattering of Polarized Electrons from CARBON-12 at Q = 150 Mev/c
119183444
Gravitational Self-force in a Radiation Gauge
In this, the first of two companion papers, we present a method for finding the gravitational self-force in a modified radiation gauge for a particle moving on a geodesic in a Schwarzschild or Kerr spacetime. An extension of an earlier result by Wald is used to show the spin weight ±2 perturbed Weyl scalar (ψ 0 or ψ 4 ) determines the metric perturbation outside the particle up to a gauge transformation and an infinitesimal change in mass and angular momentum. A Hertz potential is used to construct the part of the retarded metric perturbation that involves no change in mass or angular momentum from ψ 0 in a radiation gauge. The metric perturbation is completed by adding changes in the mass and angular momentum of the background spacetime outside the radial coordinate r 0 of the particle in any convenient gauge. The resulting metric perturbation is singular only on the trajectory of the particle. A mode-sum method is then used to renormalize the self-force. Gralla shows that the renormalized self-force can be used to find the correction to a geodesic orbit in a gauge for which the leading, O(ρ -1 ), term in the metric perturbation has spatial components even under a parity transformation orthogonal to the particle trajectory, and we verify that the metric perturbation in a radiation gauge satisfies that condition. We show that the singular behavior of the metric perturbation and the expression for the bare self-force have the same power-law behavior in L = l + 1/2 as in a Lorenz gauge (with different coefficients). We explicitly compute the singular Weyl scalar and its mode-sum decomposition to subleading order in L for a particle in circular orbit in a Schwarzschild geometry and obtain the renormalized field. Because the singular field can be defined as this mode sum, the coefficients of each angular harmonic in the sum must agree with the large L limit of the corresponding coefficients of the retarded field. One may therefore compute the singular field by numerically matching the retarded field to a power series in L. To check the accuracy of the numerical method, we analytically compute leading and subleading terms in the singular expansion of ψ 0 and compare the numerical and analytic values of the renormalization constants, finding agreement to high precision. Details of the numerical computation of the perturbed metric, the self-force, and the quantity h αβ u a u β (gauge invariant under helically symmetric gauge transformations) are presented for this test case in the companion paper.
55215566
Non-Resonance Searches with Lepton
In this contribution, results on non-resonance search with lepton are presented. The searches looking for a single lepton, dilepton, trileptons and quarks as well have been performed and their possible interpretations for each channel are given. The discussion is limited to very recent results presented by ATLAS and CMS collaboration in this symposium.
117312767
Light Higgs Scenario in BMSSM and LEP Precision Data
In this Letter we consider very light Higgs fields in BMSSM(Beyond MSSM). The spectrum below TeV scale is the same as the MSSM but the Higgs potential is modified and is well described in terms of effective dimension five and six operators. A correction from the BMSSM operators allows us to consider new parameter space of Higgs sector which is not allowed in the MSSM. It can be regarded as a constrained version of general 2 Higgs doublet model (2HDM) as long as Higgs sector is concerned. We focus on the possibility that CP odd Higgs (A) mass is about 7 or 8 GeV and charged Higgs mass is comparable to W mass. At the same time one of the CP even Higgs (h) is light enough such that h and A production at the Z pole is kinematically allowed. The tension between forward backward asymmetry of bottom quark Ab_FB measured at LEP and the Standard Model prediction can be ameliorated if bottom quark pair produced from light CP even Higgs is taken into account.
118350917
Pseudo scalar contributions to light-by-light correction of muon g−2 in AdS/QCD
Abstract We have performed a holographic calculation of the hadronic contributions to the anomalous magnetic moment of the muon, using the gauge/gravity duality. As a gravity dual model of QCD with three light flavors, we study a U ( 3 ) L × U ( 3 ) R flavor gauge theory in the five-dimensional AdS background with a hard-wall cutoff. The anomalous (electromagnetic) form factors for the pseudo scalars, π 0 , η and η ′ , are obtained from the 5D Chern–Simons term of the gravity dual, which correctly reproduce the asymptotic behavior of the form factor, dictated by QCD. We find the total light-by-light contributions of pseudo scalars to the muon anomalous magnetic moment, a μ PS = 10.7 × 10 − 10 , which is consistent with previous estimates, based on other approaches.