2025/10/13 by Arslan, Muhammad, Ahmed, Ishtiaq, Aslam, Muhammad Jamil +2
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2510.11564
The Lepton Flavor Universality ratio R_τ/μ,e(D(*)) poses a challenge to the Standard Model (SM), as B-factory experiments, BaBar, Belle, and the LHCb show 3.31σ deviations from their theoretical predictions. Utilizing the latest HFLAV averages and incorporating the branching ratio constraints 60%, 30% and 10% from the lifetime of the Bc meson, we determine the values of the Wilson coefficients (WCs) for different New Physics (NP) four-fermion operator with specific Lorentz structures. Our analysis finds that the WC scenario (C_SL,C_SR) is the most probable, the maximum pull from the SM, and strongly influenced by branching ratio constraints. Furthermore, we identify three degenerate solutions involving C_VL, C_VL′, C_VL′′, and C_SR′′ as the second most probable NP scenarios. We then studied the influence of these NP operators on various physical observables in Λb→Λcτντ decay by using the Lattice QCD form factors. Our results highlighted C_SL′′, C_SR, CT, (C_SL,C_SR), (C_SR,CT), and the three degenerate scenarios involving (C_SL,CT), (C_SL′,CT′) and (C_SL′′,CT′′) as strong indicators of NP. The correlation of different physical observables shows a direct correlation between dΓ/dq2 and PLτ for WC (C_SL,C_SR); and between AFB and PL^Λc for three degenerate WCs involving (C_SL,CT). We hope that the measurements of these observables in ongoing and future experiments will help us scrutinize these constraints on the various NP couplings.