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.
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.
43932193
Using energy peaks to measure new particle masses
A bstractWe discussed in arXiv:1209.0772 that the laboratory frame distribution of the energy of a massless particle from a two-body decay at a hadron collider has a peak whose location is identical to the value of this daughter’s (fixed) energy in the rest frame of the corresponding mother particle. For that result to hold we assumed that the mother is unpolarized and has a generic boost distribution in the laboratory frame. In this work we discuss how this observation can be applied for determination of masses of new particles, without requiring a full reconstruction of their decay chains or information about the rest of the event. We focus on a two-step cascade decay of a massive particle that has one invisible particle in the final state: C → Bb → Aab, where C, B and A are new particles of which A is invisible and a, b are visible particles. Combining the measurements of the peaks of energy distributions of a and b with that of the edge in their invariant mass distribution, we demonstrate that it is in principle possible to determine separately all three masses of the new particles, in particular, without using any measurement of missing transverse momentum. Furthermore, we show how the use of the peaks in an inclusive energy distribution is generically less affected (as compared to other mass measurement strategies) by combinatorial issues. For some simplified, yet interesting, scenarios we find that these combinatorial issues are absent altogether. As an example of this general strategy, we study SUSY models where gluino decays to an invisible lightest neutralino via an on-shell bottom squark. Taking into account the dominant backgrounds, we show how the mass of the bottom squark, the gluino and (for some class of spectra) that of the neutralino can be determined using this technique.
117044003
Parity violation in electron scattering from carbon: A progress report
An experiment is being performed at the MIT Bates Linear Accelerator Center to measure the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons from Carbon. The asymmetry, which is due to the isoscalar component of the neutral weak current, is predicted to be about 0.6{times}10{sup {minus}6}. We have recently obtained preliminary data with polarized electrons. The status of the experiment is discussed.
116971722
Polarized electrons at the Bates Linear Accelerator Center
A beam of polarized electrons have successfully been injected into the MIT Bates Linear Accelerator and accelerated it to 250 MeV. The intense beam was produced by photoemission from a GaAs crystal. The electron polarization at full energy, as measured by a brief test based on Moller scattering from a magnetized foil, was in excess of 30%. The peak intensity for the 15 ..mu..sec long pulses during the first test was about 2mA, representing about a third of the design value. The pulse rate of the accelerator was reduced to 60 Hz to minimize the total beam on the iron target. In a subsequent test, in which the beam hit a thick carbon target, the facility operated successfully at the full rate of 600 Hz. Under this condition, the average current on target was about 10 ..mu..A.
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.
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.