Upper bounds on rare K and B decays from minimal flavour violation

Abstract

We study the branching ratios of rare K and B decays in models with minimal flavour violation, using the presently available information from the universal unitarity triangle analysis and from the measurements of Br(B → X s γ), Br(B → X s l + l − ) and Br(K + → π + νν). We find the following upper bounds: Br(K + → π + νν) < 11.9 × 10 −11 ,at 95% probability. We analyze in detail various possible scenarios with positive or negative interference of Standard Model and New Physics contributions, and show how an improvement of experimental data corresponding to the projected 2010 B factory integrated luminosities will allow to disentangle and test these different possibilities. Finally, anticipating that subsequently the leading role in constraining this kind of new physics will be taken over by the rare decays K + → π + νν, K L → π 0 νν and B s,d → µ + µ − , that are dominated by the Z 0 -penguin function C, we also present plots for several branching ratios as functions of C. We point out an interesting triple correlation between K + → π + νν, B → X s γ and B → X s l + l − present in MFV models.Recently, great experimental progress has been made in the study of Flavour Changing Neutral Current (FCNC) decays, leading not only to an impressive accuracy in the extraction of CKM parameters from the Unitarity Triangle (UT) analysis [1,2], but also to stringent constraints on models with extra sources of flavour and CP violation, although an accidental agreement of the UT analysis with the Standard Model (SM) cannot yet be excluded [3,4].One is then naturally led to consider models with Minimal Flavour Violation (MFV) [5], in which flavour and CP violation is governed entirely by the CKM matrix [6,7] and the relevant operators in effective Hamiltonians for weak decays are the same as in the SM.As pointed out in [5], there exists a universal unitarity triangle (UUT) valid in all these models, that can be constructed independently of the parameters specific to a given model. Moreover, there exist several relations between various branching ratios that allow straightforward tests of these models. A review has been given in [8].This formulation of MFV agrees with the one of [9, 10] except for the case of models with two Higgs doublets at large tan β, where also additional operators, strongly suppressed in the SM, can contribute significantly and the relations in question are not necessarily satisfied. In the present paper, MFV will be defined as in [5,8].As reviewed in [8], this class of models can be formulated to a very good approximation in terms of eleven parameters: four parameters of the CKM matrix and seven values of the universal master functions F i (v) that parametrize the short distance contributions to rare decays with v denoting symbolically the parameters of a given MFV model. However, as argued in [8], the new physics contributions to the functions S(v), C(v), D ′ (v), (1.1)

Beyond Standard Model Collider Phenomenology of Higgs Physics and Supersymmetry

“…However, stringent limits have been placed on flavour changing neutral currents from K, D and B meson studies setting tight limits on the possible contribution to FCNC from new physics [147][148][149]. In order to explain why flavour violation is so small in the MSSM, the Minimal Flavour Violation (MFV) framework [150][151][152] has been developed. It proposes that the quark and squark mass matrix are simultaneously diagnoalisable at a certain energy scale.…”

K1(1270)−K1(1400)mixing angle and new-physics effects inHatanaka1, Yang2 2008Phys. Rev. D390190View full textAdd to dashboardCite

“…[38]. The sign of Re(c eff 7 ) can also be flipped in supersymmetric models with non-minimal flavor violation via gluino-down-squark loops.…”

Up sector of minimal flavor violation: top quark properties and direct D meson CP violation

“…The tensor operator does, however, give a significant contribution to the renormalization group running of the scalar coefficients. The details of this running are described in appendix B, while the estimation of the relevant hadronic matrix element ratios are performed in appendix C. In terms of the low-energy operator, the direct CP asymmetry is given by 8) where δ V 2 and δ S2 are the strong phases of the matrix elements of O V 2 and O S2 . One has a similar expansion for A π CP by replacing λ s by λ d .…”