Probing new physics effects in Λb → Λ(→pπ−)ℓ+ℓ− decay via model-independent approach. (7th October 2021)

• Record Type: Journal Article
• Authors: Nasrullah, Aqsa; Ahmed, Ishtiaq; Aslam, M Jamil; Asghar, Z; Shafaq, Saba
• Is Part Of: Physica scripta. Volume 96:Number 12(2021)
• Publication Date: 2021-10-07
• Subjects: new physics -- model independent analysis -- un-polarized Λb decay; Physics -- Periodicals; 530.05
• DOI: 10.1088/1402-4896/ac1c16
• Languages: English
• ISSNs: 0031-8949

Abstract

Abstract: In the last few decades, the FCNC transitions played a pivotal role in the ongoing efforts to test the Standard Model (SM) parameters. These transitions are also in the limelight to constrain the various New Physics (NP) scenarios. Regarding this, both the rare meson and baryon decays are pertinent as they occur through FCNC transitions and contain information about the heavy to light quark transition sector, where the SM has not yet examined totally. Therefore, it is interesting to analyze a phenomenological rich four-body decay channel Λ b → Λ ( → p π − ) ℓ + ℓ − . Here, we incorporate the NP through a model-independent approach, which modifies both the SM Wilson coefficients (WCs), and introduces the new vector, axial-vector, scalar, pseudo-scalar, and tensor operators. To check the SM and to explore the possibilities of the NP, several physical observables such as the branching ratio d  / ds, forward-backward asymmetries A FB ℓ, A FB Λ and A FB ℓ Λ, longitudinal (transverse) polarization fractions F L ( F T ), asymmetry parameters α i ′ s, the angular moments, and some other angular observables, extracted from certain foldings, have been examined to compare our results with LHCb. To see which new coupling among VA, SP, and T can accommodate the available experimental data, we have examined the influence of these couplings separately to the values of these observables. For the angular moments, most of the LHCb observations lie close to the SM, and the current constraints on new VA couplings do not change the SM results significantly. For angular coefficients, K 1 ss, K 2 ss and K 4 s the agreement with the experimental measurement gets improved if we invoke the tensor couplings along with SM WCs. We hope that when experimental measurements become more accurate, together with B meson decays, the Λ b → Λ μ + μ − will help us to put constraints on the parametric space of these WCs.