Nikolai Uraltsev

Nonperturbative corrections to inclusive beauty and charm decays. QCD versus phenomenological models

Abstract We present a self-consistent method for treating nonperturbative effects in inclusive nonleptonic and semileptonic decays of heavy flavour hadrons. These effects give rise to powerlike corrections ∝ 1 m Q n with n ⩾ 2. The leading correction to the semileptonic branching ratio occurs for n = 2. It is expressed in terms of the vector-pseudoscalar mass splitting: δ BR sl BR sl ≅ BR nl · 6 [ (M v 2 −M p 2 ) m Q 2 ](c + 2 −c − 2 ) 2N c and yields a reduction of BR sl . This nonperturbative correction contributes to the nonleptonic width with a sign opposite to that of the perturbative terms that are non-leading in 1 N c . In beauty decays the former reduces the latter by 20% whereas in charm decays they more or less cancel. This leads to a reduction of BR sl by no more than 10% in beauty decays and by a factor of roughly two in charm decays. Phenomenological models of heavy flavour decays are unable to mimic these leading corrections by a specific choice of quark masses or by invoking Fermi motion.We present a selfconsistent method for treating nonperturbative effects in inclusive nonleptonic and semileptonic decays of heavy flavour hadrons. These effects give rise to powerlike corrections

Pole mass of the heavy quark: Perturbation theory and beyond.

\propto 1/m_Q^n\,

On the motion of heavy quarks inside hadrons: Universal distributions and inclusive decays

,

Sum rules for heavy flavor transitions in the small velocity limit

n \ge 2

Moments of semileptonic B decay distributionsin the 1/m b expansion

with

Inclusive semileptonic B decays and the determination of |Vub|

m_Q

Perturbative corrections to semileptonic b decay distributions

denoting the heavy quark mass.The leading correction to the semileptonic branching ratio occurs for n=2. It is expressed in terms of the vector-pseudoscalar mass splitting:

Gluonic enhancements in non-spectator beauty decays—an inclusive mirage though an exclusive possibility

\delta BR\ind{sl}/BR\ind{sl} \simeq BR\ind{nl}\, \cdot \,6\,(\,(M_V^2-M_P^2)/m_Q^2)\cdot (c_+^2 - c_-^2)/2N_c

Weak annihilation and the end-point spectrum in semileptonic B decays

and yields a {\it reduction} of

High power n of m b in b -flavored widths and n = 5 → ∞ limit

BR\ind{sl}