Effects of neutralZ′boson inBs→φℓ

Abstract

The effects of new neutral Z ′ boson in Bs → φℓ + ℓ − , when φ is longitudinal or transverse polarized, are studied. In addition, the implications of Z ′ boson on the unpolarized and polarized CP violation asymmetries, with reference to lepton, are also presented. It is observed that the branching ratio with polarized φ are quite sensitive to the Z ′ contributions which are coming through the modification of Wilson coefficients C ef f 9 and C10. Moreover, the off-diagonal elements of the chiral Z ′ couplings contain new weak phase φ sb that provide a new source of CP violation. Keeping in view that in the FCNC transitions the CP violation asymmetries are highly suppressed in the SM, we have studied the unpolarized and polarized CP violation asymmetries in Bs → φℓ + ℓ − decays. Our results indicate that these CP violation asymmetries are remarkably significant and can attribute the any new physics coming through the Z ′ boson. It is hoped that the accurate measurements of these asymmetries will not only help us to establish NP but will also give a chance to determine the precise values of the coupling parameters of the Z ′ boson. I. INTRODUCTIONThe purpose of high energy experiments is to resolve the unanswered questions in the Standard Model (SM) through searches of new physics (NP) using complimentary approaches. The first approach is at the energy frontiers where the key representatives are the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN. The main purpose of these two detectors is to smash the particles at sufficiently large energy and then study the different particles produced after this collision. The second approach is at the rare/precision frontier where LHCb experiment at the LHC and the Belle II at the super KEKB are the names of two important experiments in regard to the flavor physics.In the precision approach the observable signature of new particles or processes can be obtained through the measurements of flavor physics reactions at lower energies and collect the evidence of any deviation from these predictions. A natural place is to investigate the flavor-changing-neutral-current (FCNC) processes in B-meson decays where one of the heavy quark makes them an ideal laboratory to test the non-perturbative aspects of the QCD and also make them a fertile hunting ground for testing the SM and probing the possible NP effects.Undoubtedly, the predictions of the SM are in good agreement with the collider data until now, however, still there exists some mysteries that are unanswered in this model. Just to name the few, they include neutrino oscillations, baryon asymmetry, dark matter, unification, the strong CP violation and the hierarchy problems. To answer these issues there exists a plethora of the NP models such as the extra dimension models, various supersymmetric models, etc. In grand unification theories such as SU (5) or string-inspired E6 models [1][2][3][4][5], one of the most pertinent is the Z ′ scenarios that include the family non-universal Z ′ [6,7] and leptophobic Z ′ ...

Implication of Z-mediated FCNC on semileptonic decays Bs→φl+l–and B+→K+l+l–

“…The semileptonic B meson decay channels and have the quark level transition . For this transition the effective Hamiltonian can be presented as [31,[36][37][38][39] √ ∑ where are four-quark operators, are dipole operators and are semileptonic electroweak operators given in [40,41].…”