scholarly journals Search for lepton-flavor violation in different-flavor, high-mass final states in pp collisions at s=13  TeV with the ATLAS detector

2018 ◽  
Vol 98 (9) ◽  
Author(s):  
M. Aaboud ◽  
G. Aad ◽  
B. Abbott ◽  
O. Abdinov ◽  
B. Abeloos ◽  
...  
Keyword(s):  
Atlas Detector ◽  
High Mass ◽  
Final States ◽  
Lepton Flavor Violation ◽  
Pp Collisions ◽  
Lepton Flavor ◽  
Flavor Violation

scholarly journals Test of lepton flavor universality and search for lepton flavor violation in B → Kℓℓ decays

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
S. Choudhury ◽  
◽  
S. Sandilya ◽  
K. Trabelsi ◽  
A. Giri ◽  
...  
Keyword(s):  
Branching Fraction ◽  
Branching Fractions ◽  
Final States ◽  
Lepton Flavor Violation ◽  
Dilepton Invariant Mass ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Belle Detector ◽  
Upper Limits ◽  
Theoretical Predictions

Abstract We present measurements of the branching fractions for the decays B → Kμ+μ− and B → Ke+e−, and their ratio (RK), using a data sample of 711 fb−1 that contains 772 × 106$$ B\overline{B} $$ B B ¯ events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The ratio RK is measured in five bins of dilepton invariant-mass-squared (q2): q2 ∈ (0.1, 4.0), (4.00, 8.12), (1.0, 6.0), (10.2, 12.8) and (> 14.18) GeV2/c4, along with the whole q2 region. The RK value for q2 ∈ (1.0, 6.0) GeV2/c4 is $$ {1.03}_{-0.24}^{+0.28} $$ 1.03 − 0.24 + 0.28 ± 0.01. The first and second uncertainties listed are statistical and systematic, respectively. All results for RK are consistent with Standard Model predictions. We also measure CP-averaged isospin asymmetries in the same q2 bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the q2 ∈ (1.0, 6.0) GeV2/c4 bin in the mode with muon final states. The measured differential branching fractions, $$ d\mathrm{\mathcal{B}} $$ d ℬ /dq2, are consistent with theoretical predictions for charged B decays, while the corresponding values are below the expectations for neutral B decays. We have also searched for lepton-flavor-violating B → Kμ±e∓ decays and set 90% confidence-level upper limits on the branching fraction in the range of 10−8 for B+ → K+μ±e∓, and B0 → K0μ±e∓ modes.

scholarly journals Lepton flavor violation and dilepton tails at the LHC

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Andrei Angelescu ◽  
Darius A. Faroughy ◽  
Olcyr Sumensari
Keyword(s):  
Flavor Physics ◽  
Charm Quark ◽  
New Physics ◽  
High Mass ◽  
Lepton Flavor Violation ◽  
Leptonic Decays ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Effective Lagrangian ◽  
Effective Coefficients

Abstract Starting from a general effective Lagrangian for lepton flavor violation (LFV) in quark-lepton transitions, we derive constraints on the effective coefficients from the high-mass tails of the dilepton processes $$pp \rightarrow \ell _k \ell _l$$pp→ℓkℓl (with $$k\ne l$$k≠l). The current (projected) limits derived in this paper from LHC data with $$36~\mathrm {fb}^{-1}$$36fb-1 ($$3~\mathrm {ab}^{-1}$$3ab-1) can be applied to generic new physics scenarios, including the ones with scalar, vector and tensor effective operators. For purely left-handed operators, we explicitly compare these LHC constraints with the ones derived from flavor-physics observables, illustrating the complementarity of these different probes. While flavor physics is typically more constraining for quark-flavor violating operators, we find that LHC provides the most stringent limits on several flavor-conserving ones. Furthermore, we show that dilepton tails offer the best probes for charm-quark transitions at current luminosities and that they provide competitive limits for tauonic $$b\rightarrow d$$b→d transitions at the high-luminosity LHC phase. As a by-product, we also provide general numerical expressions for several low-energy LFV processes, such as the semi-leptonic decays $$K\rightarrow \pi \ell ^{\pm }_k \ell ^{{\mp }}_l$$K→πℓk±ℓl∓, $$B\rightarrow \pi \ell ^{\pm }_k \ell ^{{\mp }}_l$$B→πℓk±ℓl∓ and $$B\rightarrow K^{(*)} \ell ^{\pm }_k \ell ^{{\mp }}_l$$B→K(∗)ℓk±ℓl∓.

scholarly journals Search for Lepton-Flavor Violation in Z -Boson Decays with τ Leptons with the ATLAS Detector

2021 ◽  
Vol 127 (27) ◽  
Author(s):  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
K. Abeling ◽  
...  
Keyword(s):  
Z Boson ◽  
Atlas Detector ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Z Boson Decays

scholarly journals Erratum: Search for new non-resonant phenomena in high-mass dilepton final states with the ATLAS detector

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Atlas Detector ◽  
High Mass ◽  
Final States ◽  
Dilepton Final States ◽  
Resonant Phenomena

The Lagrangian in eq. (2.1) of JHEP11 (2020) 005 has an erroneous factor of 1/2. The analysis code used for the results reported in the paper does not have this factor. The results remain unchanged.

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