Isospin asymmetries in $B\to (K^{\ast },\rho )\gamma /l^{+}{l}^{-}$ and $B\to K{l}^{+}{l}^{-}$ in and beyond the Standard Model

Abstract

We compute the isospin asymmetries in $B\to (K^{\ast },\rho )\gamma$ and $B\to (K,K^{\ast },\rho )l^{+}{l}^{-}$ for low lepton pair invariant mass $q^2$, within the Standard Model (SM) and beyond the SM (BSM) in a generic dimension six operator basis. Within the SM the CP-averaged isospin asymmetries for $B\to (K,K^{\ast },\rho )ll$, between $1{\mathrm{GeV}}^2\le q^2\le 4m_c^2$, are predicted to be small (below 1.5%) though with significant cancellation. In the SM the non-CP averaged asymmetries for $B\to \rho ll$ deviate by $\approx \pm 5$ from the CP-averaged ones. We provide physical arguments, based on resonances, of why isospin asymmetries have to decrease for large $q^2$ (towards the endpoint). Two types of isospin violating effects are computed: ultraviolet (UV) isospin violation due to differences between operators coupling to up and down quarks, and infrared (IR) isospin violation where a photon is emitted from the spectator quark and is hence proportional to the difference between the up- and down-quark charges. These isospin violating processes may be subdivided into weak annihilation (WA), quark loop spectator scattering (QLSS) and a chromomagnetic contribution. Furthermore we discuss generic selection rules based on parity and angular momentum for the $B\to Kll$ transition as well as specific selection rules valid for WA at leading order in the strong coupling constant. We clarify that the relation between the $K$ and the longitudinal part of the $K^{\ast }$ only holds for leading twist and for left-handed currents. In general the $B\to \rho ll$ and $B\to K^{\ast }ll$ isospin asymmetries are structurally different yet the closeness of ${\alpha }_{\mathrm{CKM}}$ to ninety degrees allows us to construct a (quasi) null test for the SM out of the respective isospin symmetries. We provide an update on $\mathcal{B}(B^0\to K^{\ast 0}\gamma )/\mathcal{B}(B_s\to \varphi \gamma )$ which is sensitive to WA.

38p main text (67p total), 11 figures, 11 tables, v2 additional plot on isospin-asymmetry in longitudinal part of K*, v3 included bounds on phases of Wilson coefficients in section 7 - reference added

References in corpus (17)

• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of summer 2016
• Measurement of the Differential Branching Fraction and Forward-Backword Asymmetry for B->K(*)l+l-
• SuperIso: A program for calculating the isospin asymmetry of B -> K* gamma in the MSSM
• Branching fractions, polarisation and asymmetries of B -> VV decays
• B->V gamma Beyond QCD Factorisation
• Differential branching fraction and angular analysis of the decay $B_s^0\to \varphi {\mu }^{+}{\mu }^{-}$
• Cornering New Physics in b --> s Transitions
• Measurement of the isospin asymmetry in $B\to K^{(\ast )}{\mu }^{+}{\mu }^{-}$ decays
• First observation of the decay $B_c^{+}\to J/\psi K^{+}$
• Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) and the direct CP asymmetry in B0 -> K*0 gamma
• First observation of the decay $B^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$
• Goldstone Bosons in Effective Theories with Spontaneously Broken Flavour Symmetry
• Electromagnetic Corrections in Partially Quenched Chiral Perturbation Theory
• Testing the Standard Model and searching for New Physics with $B_d\to \pi \pi$ and $B_s\to KK$ decays
• Nonperturbative Charming Penguin Contributions to Isospin Asymmetries in Radiative B decays
• Effective Valence Quark Model and a Possible Dip in $dBr(B\to K\ell \bar{\ell })/d{q}^2$
• Status of the B -> pi K puzzle and its relation to B_s -> phi pi and B_s -> phi rho decays

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