Rare decayB→K*γ: A more precise calculation

Abstract

Efforts to predict the rare exclusive decay B -t K'y from the well-known inclusive decay b + sy are frustrated by the effect of the large recoil momentum. We show how to reduce the large uncertainty in calculating this decay by relating B -+ K*y to the semileptonic process B + pep using the heavy-quark symmetry in B decays and SU(3) flavor symmetry. A direct measurement of the q 2 spectrum for the semileptonic decay can provide accurate information for the exclusive rare decay. PACS number(s): 13.40. Hq, 11.30.Hv, 13.20.Jf The inclusive rare decay B + X , y is now well understood in the context of the standard model [ l ] and the experimental upper bound [2] of 8.4 x 10W4 for the branching ratio is already playing a n important role [3] in constraining the parameters of models other than the standard model. On the other hand, the most likelv experimental observation t o be made will be the exclusive decay B + K * y . The recent limit from the CLEO Collaboration [4] of the branching ratio for this mode is 0.92 x It is this exclusive rare decay B -+ K ' y , however, which is the least well known theoretically due

Semileptonic and exclusive rare B decays

“…(6) suggested in [4] to supply a better way to measure the exclusive rare decay B → K * γ. This ratio is free of uncertainties in the wave function in the BSW model in the SU(3) flavor symmetry.…”

“…To avoid this O'Donnell and Tung [4] studied instead the q 2 -spectrum of the semileptonic decay B → ρeν. In this case…”

“…However, the relation is only valid at a single point in the Dalitz plot, a point where the semileptonic decay vanishes, so that there would still be a large uncertainty in such a measurement. In a recent paper [4] O'Donnell and Tung studied the possibility of relating the decay B → K * γ to the q 2 -spectrum of the semileptonic decay B → ρeν. They showed that the ratio I (to be defined below), which relates the two decays at q 2 = 0, is quite insensitive to different models and the wave functions.…”

Semileptonic charmedBmeson decays in universal extra dimension model

“…which are usually absorbed into the effective Wilson coefficient C ef f 9 (µ) and can be written as [24][25][26][27][28][29][30] C ef f…”

Analysis of charge asymmetry in rare dileptonBdecays

“…The choice of a negative a 2 is in consistence with Breit-Wigner phase ϕ = 0 [22]. However, consequences of assuming a different phase for a 2 can be derived without any difficulty in principle.…”