Unitarity Constraints on the B and B^* Form Factors from QCD Analyticity and Heavy Meson Spin Symmetry

Abstract

A method of deriving bounds on the weak meson form factors, based on perturbative QCD, analyticity and unitarity, is generalized in order to fully exploit heavy quark spin symmetry in the ground state $(L=0)$ doublet of pseudoscalar $(B)$ and vector $(B^{\ast })$ mesons. All the relevant form factors of these mesons are taken into account in the unitarity sum. They are treated as independent functions along the timelike axis, being related by spin symmetry only near the zero recoil point. Heavy quark vacuum polarisation up to three loops in perturbative QCD and the experimental cross sections $\sigma (e^{+}{e}^{-}\to {\rm Y})$ are used as input. We obtain bounds on the charge radius of the elastic form factor of the $B$ meson, which considerably improve previous results derived in the same framework.

13 pages LaTex, 1 figure as a separate ps file

References in corpus (7)

• Heavy Quark Symmetry
• Model-Independent Extraction of |V_{cb}| Using Dispersion Relations
• Heavy Quark Vacuum Polarisation to Three Loops
• Improved Bounds for the Slope and Curvature of $\bar{B}\to D^{(\ast )}\ell \bar{\nu }$ Form Factors
• Analyticity Properties and Unitarity Constraints of Heavy Meson Form Factors
• Slope of the Isgur-Wise Function from a QSSR Constraint on the ${\rm Y}B\bar{B}$ Couplings
• Remarks on the Heavy-Quark Symmetry in the Complex Plane

Cited by in corpus (6)

• Dispersive Bounds on the Shape of B -> D^(*) l nu Form Factors
• Precision Corrections to Dispersive Bounds on Form Factors
• Lepton-flavour non-universality of $\bar{B}\to D^{\ast }\ell \bar{\nu }$ angular distributions in and beyond the Standard Model
• Constraints on the $\omega \pi$ form factor from analyticity and unitarity
• Theory of unitarity bounds and low energy form factors
• Dispersive Bounds on The Shape Of Lambda_b to Lambda_c l {\bar ν_l} Formfactors