Conveners
Session 2c: Test of fundamental symmetries with tau lepton
- Radovan Dermisek
Session 2c: Test of fundamental symmetries with tau lepton
- Matheus Hostert (University of Minnesota / Perimeter Institute)
Lepton flavor is not an exact symmetry of nature as indicated by neutrino oscillations. Moreover, the hints for discrepancy between the measured data and the theoretical prediction of numerous observables related to the ratio between events containing electrons to those containing muons, e.g. R_D(*) and R_K, points towards new physics exhibiting lepton non-universality. These examples also...
Leptoquarks (LQ) are predicted by many new physics theories to describe the similarities between the lepton and quark sectors of the Standard Model and offer an attractive potential explanation for the lepton flavour anomalies observed at LHCb and flavour factories. The ATLAS experiment has a broad program of direct searches for leptoquarks, coupling to the first-, second- or third-generation...
We report on a precision measurement of the ratio R^Υ(3S)_τμ = B[Υ(3S) → τ+τ−] / B[Υ(3S) → μ+μ−] using data collected with the BaBar detector at the SLAC PEP-II e+e− collider. The measurement is based on a 28 fb−1 data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million Υ(3S) mesons. The ratio is measured to be R^Υ(3S)_τμ = 0.966 ± 0.008 (stat) ±...
$L\to\ell\chi$ decays (with $\chi$ a boson associated to this lepton flavor violation, LFV) have not been described satisfactorily so far for light spin-one $m_\chi$. In particular, observables exhibited an unphysical divergence in the limit of massless $\chi$, associated to its longitudinal polarizations. Based on gauge symmetry, we show how to correct this issue. To this end, we consider two...
The Belle II experiment at SuperKEKB, an asymmetric e+e- collider, aims at a total integrated luminosity of 50 ab-1, to pursue a rich program of Standard Model and Beyond the Standard Model physics. In its first year of operation, approximately 10 fb-1 were collected at the Upsilon(4S) resonance, with about 100 fb-1 expected by the end of 2020. This results in a sizeable sample of tau pairs,...
Many models of dark matter and hidden sectors predict new particles with masses below the electroweak scale. Low-energy electron-positron colliders such as BABAR are ideally suited to discover these hidden-sector particles. We present two recent BABAR searches for low-mass hidden-sector particles, including new searches for prompt and long-lived leptonically decaying hidden scalars produced in...
Using about 200 fb-1 of data from electron-positron annihilations, we present searches for dark leptophilic scalars produced in association with tau-pair decays at the Belle II experiment. The goal of this analysis is to discover dark matter or find upper limits of the dark coupling constant as a function of the dark scalar mass.
