τpolarization asymmetry inB→Xsτ

Abstract

Rare B decays provide an opportunity to probe for new physics beyond the standard model. The effective Hamiltonian for the decay b→sl ϩ l Ϫ predicts the characteristic polarization for the final state lepton. Lepton polarization has, in addition to a longitudinal component P L , two orthogonal components P T and P N lying in and perpendicular to the decay plane. In this article we perform a study of the -polarization asymmetry in the case of SUSY models with large tan ␤ in the inclusive decay B→X s ϩ Ϫ . ͓S0556-2821͑99͒06221-9͔ PACS number͑s͒: 12.60. Jv, 13.25.Hw Recent progress in experiment and theory has made flavor changing neutral current ͑FCNC͒ B decays a stringent test of the standard model ͑SM͒ and a powerful probe of physics beyond the standard model. The first observations ͓1͔ of the inclusive and exclusive radiative decays B→X s ␥ and B →K*␥ have placed the study of rare B decays on a new footing. The observation of b→s␥ by CLEO puts very strong constraints on various new physics beyond the standard model. In the case of B→X s ␥ CLEO Observations give very strong constraints on the charged Higgs boson mass in the two Higgs doublet model. But in minimal supersymmetric standard model ͑MSSM͒ these constraints becomes a bit relaxed because of various cancellations between different superparticle contributions. It is therefore important to study the sensitivity of other FCNC processes to SUSY.Recently the inclusive decay of B→X s l ϩ l Ϫ ͓2,3͔ received considerable attention as a testing ground of SM and new physics. The experimental situations of these decays is very promising with e ϩ e Ϫ and hadronic colliders closing on the observation of exclusive models with lϭ and e final states, respectively. In this decay we can observe various kinematical distributions associated with a final state lepton pair such as lepton pair invariant mass spectrum, lepton pair forward backward asymmetry, etc. Recently another observable, polarization asymmetry, for the B→X s ϩ Ϫ mode has also been proposed by Hewett ͓4͔ which can again be used for more strict checking of effective Hamiltonian governing the decay. In another work ͓5͔ attention has been drawn to the fact that apart from longitudinal polarization of lepton there can be two other orthogonal components of polarizations which are proportional to m l /m b and hence are important for . These components of polarizations, namely, the component in the decay plane ( P T , transverse polarization͒ and the component normal to decay plane ( P N , normal polarization͒. 1 In this paper we will try to examine the sensitivity of these observables with respect to new physics, i.e., MSSM.Among models for physics beyond standard model supersymmetry ͑SUSY͒ is considered to be the most promising candidate. The minimal extension of the standard model ͑MSSM͒ involves chiral superfields Q, U c , D c , L, E c , H 1 , and H 2 which transforms under SU(3) c ϫSU(2) L ϫU(1) Y as Qϵ͑3,2,1/2͒,

Lepton polarization asymmetry in radiative dileptonicB-meson decays in the minimal supersymmetric standard model

“…As we have pointed out earlier [9] that for the inclusive process B → X s ℓ + ℓ − there is not much deviation from SM results in mSUGRA model. But in radiative dileptonic decay mode, mSUGRA predictions also show large deviations (at least of P L and P T ) from SM results, making it possible to use polarization asymmetries to test mSUGRA model.…”

“…It has been well emphasized in many works [6,9,10] that it is not necessary to have a common mass for all the scalars at the GUT scale. To have required suppression in K 0 −K 0 mixing, it is sufficient to have common masses of all the squarks at the GUT scale.…”

“…So we only consider the cases when the photon is hooked to initial quark lines and final lepton lines. To start off, the effective Hamiltonian relevant for b → sℓ + ℓ − is [2,3,4,6,7,8,9] :…”

“…This is because in MSSM the scalar and pseudoscalar Higgs coupling to the leptons is proportional to m ℓ tanβ and thus can be large for ℓ = µ, τ and for large tanβ . The effect of NHBs has been studied in great detail in various leptonic decay modes [2,3,4,5,6,7,8,9,11,15]. The effect of NHBs on radiative mode B s → ℓ + ℓ − γ has also been studied in 2HDM [2] and SUSY [7].…”

“…Studies of rare B decays can give precise information about various fundamental parameters of SM like Cabbibo-Kobayashi-Maskawa (CKM) matrix elements, leptonic decay constants etc. In addition to this, rare B decays can also give information about various extensions of SM like two Higgs doublet model (2HDM) [2,3,4,5] , Minimal Supersymmetric Standard Model (MSSM) [6,7,8,9,10,11,12,13] etc. After the first observation of the penguin induced decay B → X s γ and the corresponding exclusive decay channel B → K * γ by CLEO [14] , rare decays have begun to play an important role in particle physics phenomenology.…”