Analyzing b -%26gt; u transitions in semileptonic (B)over-bar(s) -%26gt; K*(+) (-%26gt; K pi)l(-)(nu)over-bar(l) decays

作者：Feldmann Thorsten; Mueller Bastian; van Dyk Danny

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2015, 92(3): 034013.

DOI：10.1103/PhysRevD.92.034013

We study the semileptonic decay (B) over bar (s) -> K*(+)l(-)(nu) over bar (l), which is induced by b -> ul(-)(nu) over bar (l) transitions at the quark level. We take into account the standard model (SM) operator from W-boson exchange as well as possible extensions from physics beyond the SM. The secondary decay K*(+) -> K pi can be used to study a number of angular observables, which are worked out in terms of short-distance Wilson coefficients and hadronic form factors. Our analysis allows for an independent extraction of the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-ub vertical bar and for the determination of certain ratios of (B) over bar (s) -> K* form factors. Moreover, a future precision measurement of the forward-backward asymmetry in the (B) over bar (s) -> K*(+)l(-)(nu) over bar (l) decay can be used to unambiguously verify the left-handed nature of the transition operator as predicted by the SM. We provide numerical estimates for the relevant angular observables and the resulting decay distributions on the basis of available form-factor information from lattice and sum-rule estimates. In addition, we pay particular attention to suitable combinations of angular observables in the decays (B) over bar s -> K*(+)(-> K pi)l(-)(nu) over bar (l) and (B) over bar -> K*(0) (-> K pi)l(+)l(-), and find that they provide complementary constraints on the relevant b. s short-distance coefficients. As a by-product, we perform a SM fit on the basis of selected experimental decay rates in both inclusive and exclusive channels, and hadronic input functions. We find vertical bar V-ub vertical bar= (4.07 +/- 0.20) x 10(-3).

• 出版日期2015-8-14