Constraining the Unitarity Triangle with B -> V gamma

Abstract

We discuss the exclusive radiative decays $B\to K^{\ast }\gamma$, $B\to \rho \gamma$, and $B\to \omega \gamma$ in QCD factorization within the Standard Model. The analysis is based on the heavy-quark limit of QCD. Our results for these decays are complete to next-to-leading order in QCD and to leading order in the heavy-quark limit. Special emphasis is placed on constraining the CKM-unitarity triangle from these observables. We propose a theoretically clean method to determine CKM parameters from the ratio of the $B\to \rho l\nu$ decay spectrum to the branching fraction of $B\to \rho \gamma$. The method is based on the cancellation of soft hadronic form factors in the large energy limit, which occurs in a suitable region of phase space. The ratio of the $B\to \rho \gamma$ and $B\to K^{\ast }\gamma$ branching fractions determines the side $R_t$ of the standard unitarity triangle with reduced hadronic uncertainties. The recent Babar bound on $B(B^0\to {\rho }^0\gamma )$ implies $R_t<0.81(\xi /1.3)$, with the limiting uncertainty coming only from the SU(3) breaking form factor ratio $\xi$. This constraint is already getting competitive with the constraint from $B_s$-${\bar{B}}_s$ mixing. Phenomenological implications from isospin-breaking effects are briefly discussed.

23 pages, 8 figures

References in corpus (6)

• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• CP Violation and the CKM Matrix: Assessing the Impact of the Asymmetric B Factories
• The CKM Matrix and the Unitarity Triangle
• Implication of the $B\to (\rho ,\omega )\gamma$ Branching Ratios for the CKM Phenomenology
• Exclusive Radiative Decays of B Mesons in QCD Factorization
• QCD Sum Rules on the Light-Cone, Factorisation and SCET

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• Heavy-to-light B meson form factors at large recoil energy -- spectator-scattering corrections
• |V_td/V_ts| from B-> V gamma
• Precision calculations of $B\to V$ form factors in QCD
• Radiative and Electroweak Penguin Decays of B Mesons
• New Physics at a Super Flavor Factory
• Time-dependent CP Asymmetry in B->K* gamma as a (Quasi) Null Test of the Standard Model
• Towards $B\to V\gamma$ Decays at NNLO in SCET
• Data for Polarization in Charmless B -> phi K^*: A Signal for New Physics?
• Precision Flavour Physics with $B\to K\nu \bar{\nu }$ and $B\to K{l}^{+}{l}^{-}$
• Exclusive radiative B-meson decays within the aligned two-Higgs-doublet model
• Factorization in B->V gamma Decays
• An estimate of the B-->K*gamma form factor
• Rare radiative charm decays within the standard model and beyond
• New constraints on supersymmetric models from b -> s gamma
• Theoretical and experimental status of rare charm decays
• Determining the photon polarization of the b --> s gamma using the B --> K1(1270) gamma --> (K pi pi) gamma decay
• Branching Fraction Measurements of B+ -> rho+ gamma, B0 -> rho0 gamma, and B0 -> omega gamma
• Precision flavour physics with $B\to K\nu \bar{\nu }$ and $B\to K{l}^{+}{l}^{-}$
• Exclusive radiative B-meson decays within minimal flavour violating 2HDMs
• Investigating The Physics Case of Running a B-Factory at the Y(5S) Resonance
• Study on pure annihilation type B to V gamma decays
• Theory Review of Exclusive Rare Radiative Decays
• |V_td/V_ts| from QCD Sum Rules on the Light-Cone
• Non-leptonic B-decays in and beyond QCD Factorisation
• Effects from Hadronic Structure of Photon on $B\to \varphi \gamma$ and $B_s\to ({\rho }^0,\omega )\gamma$ Decays