Abstract
We give a comprehensive account of the flavour physics of Beyond-Standard-Model (BSM) effects in b → c overline{c} cs transitions, considering the full set of 20 four-quark operators. We discuss the leading-order structure of their RG mixing with each other as well as the QCD-penguin, dipole, and FCNC semileptonic operators they necessarily mix with, providing compact expressions. We also provide the first complete results for BSM effects in the lifetime observables ∆Γs and τ (Bs)/τ(Bd), as well as for the semileptonic CP-asymmetry {a}_{sl}^s . From a global analysis, we obtain stringent constraints on 16 of the 20 BSM operators, including the 10 operators {Q}_{1dots 10}^{cprime } involving a right-handed strange quark. Focussing on CP-conserving new physics, the constraints correspond to NP scales of order 10 TeV in most cases, always dominated by exclusive and/or radiative B-decays via RGE mixing. For the remaining four operators, including the two Standard-Model (SM) ones, larger effects are experimentally allowed, as previously noted in [1]. We extend that paper’s scope to the CP-violating case, paying attention to the impact on the decay rate and time-dependent CP-violation in Bd → J/ψKS. Contrary to common lore, we show that quantifiable constraints arise for new physics in either of the two SM operators, with the uncertain non-perturbative matrix element of the colour-suppressed (or equivalently, colour-octet) operator determined from the data. For new physics in the coefficient {C}_1^c , suppressed in the SM, we find (in addition to CP-conserving new physics) two perfectly viable, narrow bands of complex Wilson coefficients. Somewhat curiously, one of them contains a region where the fitted matrix element for the colour-suppressed operator is in agreement with naive factorization, contrarily to a widely held belief that large non- factorizable contributions to Bd → J/ψKS are implied by experimental data.
Highlights
We give a comprehensive account of the flavour physics of Beyond-StandardModel (BSM) effects in b → ccs transitions, considering the full set of 20 four-quark operators
Focussing on CP-conserving new physics, the constraints correspond to NP scales of order 10 TeV in most cases, always dominated by exclusive and/or radiative B-decays via renormalization-group equations (RGE) mixing
We show that quantifiable constraints arise for new physics in either of the two SM operators, with the uncertain non-perturbative matrix element of the colour-suppressed operator determined from the data
Summary
As emphasized in our previous work [1], operator mixing can have a dramatic impact on the radiative and semileptonic Wilson coefficients, and as a result on the contributions of the b → ccs operators to the radiative and rare semileptonic decays. The second is that part of the anomalous-dimension matrix first arises at 2-loop order To discuss both issues further, let us decompose the Wilson coefficient vector C into subcomponents, C(μ) = (Cc(μ), Cp(μ), C8g(μ), C7γ(μ), C9V (μ)). Is sufficient to bring the anomalous-dimension matrix into the form (2.11), such that the solution (2.12) applies (note that with the rescaling, γ99 → −2β0) This shows that C9V formally starts at order 1/αs when CA is nonzero (which includes the SM case). In this case, the mixing of the CBSM operators into the dipoles through γB7 and γB8 arises at one-loop order, but there is no mixing into the semileptonic coefficient C9V.
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