Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session W02: Mini-Symposium on Precision Measurements with LeptonsMini-Symposium Recordings Available
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Sponsoring Units: DPF Chair: Robert Bernstein, Fermilab Room: Broadway South |
Monday, April 11, 2022 5:45PM - 6:21PM |
W02.00001: Probing for Lepton Flavor Non-Universality at LHCb Invited Speaker: Phoebe Hamilton Decays of b hadrons are a powerful probe to search for new interactions that violate Lepton Flavor Universality (LFU), |
Monday, April 11, 2022 6:21PM - 6:33PM |
W02.00002: Variations to the z-Expansion of the Form Factor Describing the Decay of B Mesons Daniel R Simons, Erik Gustafson, Yannick L Meurice We examine the decay rate of the particle decay B -> D l nu using data collected from the Belle Collaboration. We studied three parameterizations of the form factor which describe the differential decay rate, the Caprini, Lellouch, and Neubert (CLN) parametrization, the Boyd, Grinstein, and Lebed (BGL) parametrization, and the Bourrely, Caprini, and Lellouch (BCL) parameterization. The form factor is a function of the hadronic recoil variable w, and each parameterization contains unique free parameters which are the focus of this work. We test the extrapolations of the form factor by fitting many different subsets of the low w data and then compare the prediction of the fit to the high w data using a chi^2-metric. By only fitting the low w data we are able to examine the stability of extrapolations which will be informative for lattice simulations. |
Monday, April 11, 2022 6:33PM - 6:45PM |
W02.00003: Search for the rare charm meson decays D0 → h h(') l+ l- Shuaiyan Kang, Soeren A Prell Electroweak penguin quark transitions mediated by Flavor Changing Neutral Currents c → u l l (where l is an electron or muon) are forbidden at tree level in the Standard Model (SM). They proceed through an electroweak box or loop diagram in the SM and are further suppressed due to the GIM mechanism and the small quark masses in the loop. This provides a new window for probing NP models such as leptoquarks, Z' model and minimal supersymmetric standard model. Babar has observed the decay D0→ K-π+e+e- in the mass range 0.675 < m(e+e-) < 0.875 GeV where long-distance contributions dominate. LHCb has observed the decays D0→ h h(') μ+μ- (h = K, π) and gave the first full angular analysis of the π-π+μ+μ- and K-K+μ+μ- modes. We present our study of the decays D0 →h h(') l+ l-, where h = K, π and l = e, μ using 942 fb-1 of e+e- data collected at or close to the center-of-mass energy of the Υ(4S) and Υ(5S) with the Belle detector at KEK. |
Monday, April 11, 2022 6:45PM - 6:57PM |
W02.00004: Multi-Boson Production and the Muon Yukawa Coupling Yang Ma, Tao Han, Wolfgang Kilian, Nils Kreher, Juergen Reuter, Tobias Striegl, Keping Xie The Higgs boson may be regarded as, on the one hand, the capstone of the glorious arch of the SM or, on the other hand, as the portal giving access to new physics. An open question in particle physics is whether the Higgs mechanism generates the masses of all the fermions by the Yukawa interactions. We propose to study multi-boson production processes and scrutinize the muon Yukawa coupling at a high-energy muon collider. By the subtle interplay between the muon Yukawa coupling in the high-energy productions of multiple (vector and Higgs) bosons, we show that it is possible to measure the muon Yukawa coupling to an accuracy of ten percent for a 10 TeV collider and a few percent for a 30 TeV machine. |
Monday, April 11, 2022 6:57PM - 7:09PM |
W02.00005: Clustering improvements for the Run-2 and Run-3 precession frequency analysis in the Muon g-2 experiment Hannah Binney The Fermilab Muon g-2 experiment, which measures the muon anomalous magnetic moment aμ, published analysis of Run-1 data in April 2021 to a precision of 460 ppb. This result confirmed the value of aμ measured at the earlier Brookhaven experiment, and the averaged experimental value stands in tension with the Standard Model prediction to 4.2 σ. Analysis of the Run-2 and Run-3 data is now underway. As the statistical uncertainty decreases, uncertainties on systematic effects are being reduced to reach the ultimate systematic uncertainty goal of 70 ppb. When a muon decays, the resulting positron is detected by a calorimeter, where its time and energy is reconstructed. One important source of uncertainty for the Run-1 precession frequency (ωa) analysis was pileup, which occurs when two decay positron hits are reconstructed as a single positron. In this talk, I will present an improvement to the algorithm that clusters calorimeter hits in order to reconstruct the positron information. By incorporating detector time resolution information into the algorithm, pileup is reduced by a factor of four. I will present preliminary blinded ωa results and uncertainties for Run-2 and Run-3 using this improved reconstruction. |
Monday, April 11, 2022 7:09PM - 7:21PM |
W02.00006: The Mu2e fast track-trigger performance Matthew J Stortini The Mu2e experiment plans to search for neutrino-less muon to electron conversion in the field of a nucleus. Such a process violates lepton flavor conservation. To perform this search, a muon beam is focused on an aluminum target, the muons are stopped in the field of the aluminum nucleus, and electrons emitted from subsequent muon decays in orbit are measured. The endpoint energy for this process is 104.97 MeV; an excess of measured electrons at this energy signifies neutrino-less muon to electron conversion has occurred. Currently under construction at the Fermilab Muon Campus, Mu2e will stop muons on target in 3 years of running, with the goal of reaching a single event sensitivity of on the branching ratio. To reach such a sensitivity, a tracker with momentum resolution of around 180 keV/c is needed. Further, the trigger system must reconstruct conversion electron tracks with > 90% efficiency and, due to data constraints, have a trigger rate of < a few kHz and process events in < 5 ms. Processing events this quickly and efficiently represents a significant experimental challenge. The work reported on here details important aspects of the trigger, and current studies on potential ways to improve processing speeds. |
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