Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E20: Weak Decays and Charged Lepton PropertiesLive
|
Hide Abstracts |
Sponsoring Units: DPF Chair: Robert Bernstein, Fermilab |
Saturday, April 17, 2021 3:45PM - 3:57PM Live |
E20.00001: Measurement of ${\cal{B}}(\Xi_c^0 \rightarrow \pi^- \Lambda_c^+)$ Michael Wilkinson The $\Xi_c^0$ baryon is unstable and usually decays into charmless final states by the $c \to s u\overline{d}$ transition. It can, however, also disintegrate into a $\pi^-$ meson and a $\Lambda_c^+$ baryon via $s$-quark decay or via $cs\to d c$ weak scattering. The interplay between the latter two processes governs the size of the branching fraction ${\cal{B}}(\Xi_c^0 \rightarrow \pi^- \Lambda_c^+)$. We here present the first measurement of ${\cal{B}}(\Xi_c^0 \rightarrow \pi^- \Lambda_c^+) = (0.55\pm 0.02 \pm 0.18)$\%, where the first uncertainty is statistical and second systematic, published 12 October 2020 in PRD. It is compatible with the larger of the theoretical predictions that connect models of hyperon decays using partially conserved axial currents and SU(3) symmetry with those involving the heavy-quark expansion and heavy-quark symmetry. In addition, we present the second measurement of the branching fraction of the normalization channel, ${\cal{B}}(\Xi_c^+ \rightarrow p K^- \pi^+) = (1.135 \pm 0.002 \pm 0.387)$\%. [Preview Abstract] |
Saturday, April 17, 2021 3:57PM - 4:09PM Live |
E20.00002: Optimizing Event Selection for Muon-to-Positron Conversion Search via Machine Learning Methods Xiaohe Shen The high-precision Mu2e experiment at Fermilab will search for the lepton-flavor violating process of neutrinoless muon-to-electron conversion, and the lepton-number violating muon-to-positron conversion. The selection of events of interest relies on machine- learning Multivariate Analysis (MVA) methods to distinguish signals from various backgrounds. Aiming to optimize the signal selection and to compute an estimated sensitivity for the muon-to-positron conversion process, we investigate the performance of several MVA methods in Toolkit for Multivariate Analysis (TMVA). We use the output of the major reconstruction algorithms with their corresponding Monte Carlo Truth information as training and testing data sets. We compare the performance of various machine-learning methods to get their optimal configurations for the signal selection. Then we compare the performance of different methods. We apply the event selection to the dominant background processes of the Radiative Muon Capture (RMC) and the cosmic ray induced events. We then estimate the sensitivity of Mu2e to the electron-to-positron conversion process. [Preview Abstract] |
Saturday, April 17, 2021 4:09PM - 4:21PM Live |
E20.00003: Preliminary Analysis of $D^*$-tagged $D^0 \rightarrow \pi^+ \pi^- \pi^0$ Decays in Early Belle II Data Emma Oxford, Roy Briere The Belle II collaboration uses the asymmetric SuperKEKB collider run at the $\Upsilon(4S)$ resonance to study Standard Model and new physics at the intensity frontier. One major area of study is charge-parity violation (CPV), especially in the $c$-quark sector. The LHCb collaboration published the first observation of CPV in $D$ meson decays in 2019,\footnote{R. Aaij et al., \textbf{Phys. Rev. Lett.} 122, 211803} and the search for CPV in other decay modes continues to be a major area of interest in particle physics. To that end, we will perform a Dalitz analysis of the singly Cabibbo suppressed (SCS) decay $D^0 \rightarrow \pi^+ \pi^- \pi^0$, using $D^*$-tagged $D^0$ and $\overline{D}^0$ mesons. This presentation will show a preliminary analysis of this mode with 72fb$^{-1}$ of Belle II data. [Preview Abstract] |
Saturday, April 17, 2021 4:21PM - 4:33PM Live |
E20.00004: Search for the rare charm meson decays $D^0 \rightarrow K^- \pi^+ l^{\pm} l^{\mp}$ Shuaiyan Kang, Soeren Prell \\ Electroweak penguin quark transitions mediated by Flavor Changing Neutral Currents $c\rightarrow u l^+ l^-$ (where $l^\pm$ 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. Recently, Babar has observed the decay $D^0\rightarrow K^-\pi^+e^+e^-$ in the mass range 0.675 $<$ $m_{e^+e^-}$ $<$ 0.875 GeV/$c^2$ where long-distance contributions dominate. LHCb has observed the decays $D^0\rightarrow K^-\pi^+\mu^+\mu^-$, $\pi^-\pi^+\mu^+\mu^-$ and $K^-K^+\mu^+\mu^-$. We present our study of the decays $D^0 \rightarrow K^-\pi^+l^{\pm}l^{\mp}$, where $l^\pm = e,\mu$ using 942fb$^{-1}$ of $e^+e^-$ data collected at or close to the center-of-mass energy of the $\Upsilon{(4S)}$ and $\Upsilon{(5S)}$ with the Belle detector at KEK. [Preview Abstract] |
Saturday, April 17, 2021 4:33PM - 4:45PM Live |
E20.00005: Light flavour mistag calibration for ATLAS $b$-jet identification algorithms Angela Burger Many analyses in ATLAS rely on the identification of jets containing $b$-hadrons ($b$-jets) with high efficiency while rejecting more than 99\% of non-$b$-jets. Identification algorithms, called $b$-taggers, exploit $b$-hadron properties like their long lifetime. Recently developed ATLAS $b$-taggers using neural networks outperform previous $b$-taggers by a factor of two in terms of light jet rejection. Nevertheless, contributions from light jet mistags can be non-negligible in certain analyses phase spaces and a precise measurement of the light jet mistag rate in data and simulation to correct the rate in simulation is important. Due to the high light jet rejection of the $b$-taggers, the mistag rate cannot be measured directly but rather by means of a modified tagger, designed to decrease the $b$-jet efficiency while leaving the light jet response unchanged. This so-called "negative tag method" has been improved recently: uncertainties are reduced by constraining non-light flavour contribution with a data-driven method and the dominant systematic uncertainty has been reduced from 10-60\% to 5-20\% due to improved inner detector modeling. The method and a selection of results released recently to the ATLAS collaboration using $pp$ collisions at $\sqrt{s}=$ 13 TeV are presented. [Preview Abstract] |
Saturday, April 17, 2021 4:45PM - 4:57PM Live |
E20.00006: A Precision Measurement of the $K_{L}\to 3\pi^{0}$ Dalitz Branching Ratio Michael Farrington Over the course of recent runs, the KOTO Experiment has collected 1.8 million $K_{L}\to 3\pi^{0}$ decay events yielding an incredible amount of virtually background-free $\pi^{0}$decay data. This offers an opportunity to study $\pi^{0}$decay to make a precision measurement of the $\pi ^{0}\thinspace $Dalitz decay branching ratio. The E14 KOTO detector provides an excellent means of identifying $\pi^{0}\thinspace $Dalitz decay with a 2576 crystal CsI calorimeter covered by a plastic scintillator charged particle detector. To identify $\pi^{0}\thinspace $Dalitz decay I will study 6 cluster decay events with energy deposits on the charged particle detector and compare them with a dataset of simulated $K_{L}\to 3\pi^{0}$ events using Geant4 to perform a measurement of the branching ratio. [Preview Abstract] |
Saturday, April 17, 2021 4:57PM - 5:09PM Live |
E20.00007: The Pitch and Electric Field Corrections to the Anomalous Muon Spin Precession Frequency for the Muon $g-2$ Experiment Tyler Barrett, Antoine Chapelain, David Rubin, Joshua Fagin, James Mott The Muon $g-2$ Experiment (Fermilab E989) aims to measure the muon's anomalous magnetic moment, $a_\mu = (g_\mu-2)/2$, to a precision of 140 parts-per-billion (ppb). The measurement is performed by observing the anomalous spin precession frequency $\omega_a$ of a muon ensemble within a magnetic storage ring. The measured precession frequency is directly proportional to $a_\mu$, up to perturbations from two primary beam dynamics effects which must be corrected. One effect arises from vertical oscillations within a vertically focusing electric quadrupole field, called the pitch correction. Another arises from the quadrupoles' radial electric field, called the electric field correction. Both effects can perturb $\omega_a$ by hundreds of ppb, and must be carefully determined in order to reach the target precision for $a_\mu$. Here we present the methodology and results for the pitch and electric field corrections from the experiment's Run-1 measurement period. [Preview Abstract] |
Saturday, April 17, 2021 5:09PM - 5:21PM Live |
E20.00008: In situ monitoring of the stopped muon flux at Mu2e Bastiano Vitali Mu2e searches for the neutrino-less coherent $\mu^-\rightarrow e^-$ conversion in aluminum nucleus field. The number of stopped muons (cardinal for the normalization) is proportional to the number of protons on target, which depends on the extraction system for the proton beam. Mu2e will use a resonant extraction characterized by intensity fluctuations on the time scale of milliseconds with non-trivial impacts on the performance of the apparatus. The apparatus includes two detectors developed to measure the normalization but encounter limitations when trying to monitor the flux at the millisecond timescales: the goal of my Thesis was to try filling this gap. The method is based on counting the number of muons captured in the stopping target by counting the number of protons produced by the nuclear muon capture. Cardinal task of this study has been to tailor the reconstruction routines to protons. An event is everything which happens in a $1.7\ \mu$s window between two consecutive proton pulses (time needed for the $\pi$ to decay and $\mu$): the reconstruction will be performed in a crowded environment. Our results are satisfactory since the number of reconstructed protons is significant (few per event), and show that a monitor on the timescale of milliseconds is indeed possible. [Preview Abstract] |
Saturday, April 17, 2021 5:21PM - 5:33PM Live |
E20.00009: Mu2e Online DAQ and Slow Controls Interface Antonio Gioiosa, Simone Donati, Luca Morescalchi, Elena Pedreschi, Franco Spinella, Glenn Horton-Smith, Gianantonio Pezzullo, Eric Flumerfelt, Vivian O'Dell, Ryan Rivera The muon campus program at Fermilab includes the Mu2e experiment that will search for a charged-lepton flavor violating processes where a negative muon converts into an electron in the field of an aluminum nucleus, improving by four orders of magnitude the search sensitivity reached so far. Mu2e’s Trigger and Data Acquisition System (TDAQ) uses {\it otsdaq} as its solution. Developed at Fermilab, {\it otsdaq} uses the {\it artdaq} DAQ framework and {\it art} analysis framework, under-the-hood, for event transfer, filtering, and processing. {\it otsdaq} is an online DAQ software suite with a focus on flexibility and scalability, while providing a multi-user, web-based, interface accessible through the Chrome or Firefox web browser. The detector Read Out Controller (ROC), from the tracker and calorimeter, stream out zero-suppressed data continuously to the Data Transfer Controller (DTC). Data is then read by a software filter algorithm that selects events considering data flux that comes from a Cosmic Ray Veto System (CRV). A Detector Control System (DCS) for monitoring, controlling, alarming, and archiving has been developed using the Experimental Physics and Industrial Control System (EPICS) Open Source Platform. The DCS System has also been itegrated into {\it otsdaq}. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700