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.
17667065
Review of Charm Semileptonic Decays and QCD
In this paper, we review recent progress in the field of semileptonic decays of charm mesons, including topics on the relative branching ratio and the form factors. The comparison between the experimental form factor measurements and the Lattice QCD calculations is emphasized.
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.
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
119805142
Recent FOCUS results on charm mixing and CP violation
We summarize recent results on CP violation and mixing based on a high statistics photo-produced 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. In addition, we searched for a CP width asymmetry in D+ → K−K+π+, D0 → K−K+ and D0 → π−π+. We found no evidence for CP violation by comparing the decay rates for the particle and antiparticle.
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.
118190331
RADIATION REACTION IN CURVED SPACETIME
122541104
Progress report on the Bates parity experiment
We are performing an experiment at the MIT Bates Linear Accelerator Center to measure the parity‐violating asymmetry in the elastic scattering of polarized electrons from carbon. The asymmetry, which is due to the isoscalar piece of the neutral weak current, is predicted to be about one part per million for our experimental conditions. We have recently obtained preliminary data with polarized electrons. This paper discusses the status of the experiment, with emphasis on our understanding of the most important systematic errors.
118459937
Using energy peaks to count dark matter particles in decays
Abstract We study the determination of the symmetry that stabilizes a dark matter (DM) candidate produced at colliders. Our question is motivated per se , and by several alternative symmetries that appear in models that provide a DM particle. To this end, we devise a strategy to determine whether a heavy mother particle decays into one visible massless particle and one or two DM particles. The counting of DM particles in these decays is relevant to distinguish the minimal choice of Z 2 from a Z 3 stabilization symmetry, under which the heavy particle and the DM are charged and the visible particle is not. Our method is novel in that it chiefly uses the peak of the energy spectrum of the visible particle and only secondarily uses the M T 2 endpoint of events in which the heavy mother particles are pair-produced. We present new theoretical results concerning the energy distribution of the decay products of a three-body decay, which are crucial for our method. To demonstrate the feasibility of our method in investigating the stabilization symmetry, we apply it in distinguishing the decay of a bottom quark partner into a b quark and one or two DM particles. The method can be applied generally to distinguish two- and three-body decays, irrespective of DM.
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.
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.