Semiinclusive hadronicBdecays as null tests of the standard model

Abstract

We propose a new set of observables that can be used as experimental null tests of the Standard Model in charged and neutral B decays. The CP asymmetries in hadronic decays of charged B mesons into inclusive final states containing at least one of the following mesons: KS,L, η ′ , cc bound states or neutral K * or D mesons, for all of which a U-spin rotation is equivalent to a CP conjugation, are CKM suppressed and furthermore vanish in the exact U-spin limit. We show how this reduces the theoretical error by using Soft Collinear Effective Theory to calculate the CP asymmetries for KS,LX s+d , K * X s+d and η ′ X s+d final states in the endpoint region. For these CP asymmetries only the flavor and not the charge of the decaying B meson needs to be tagged up to corrections of NLO in 1/m b , making the measurements more accessible experimentally.

U-spin breaking in CP asymmetries in B decays

“…Consequently the asymmetry relations (25) are violated by first order U-spin breaking corrections in a form analogous to Eq. (17). Using arguments similar to those associated with Eqs.…”

“…Other decays involving one or two vector mesons in the final state have been discussed in the framework of U-spin in Refs. [16] and [17]. Well-known examples, which have been studied extensively by experiments, are the pairs [16,18,19] (B 0 → K + π − , B s → π + K − ) and [20] (B 0 → π + π − , B s → K + K − ) and two pairs of three body B + decays [21],…”

Probing electroweak physics for allB→XMdecays in the endpoint region

“…Averaging over the most recent measurements from BaBar [3] and CLEO [4] gives this branching ratio Br(B → η ′ X s ) = (420 ± 94) × 10 −6 (2) for a lower cut on η ′ energy of E η ′ > 2.218 GeV. From the theoretical side semi-inclusive hadronic decays are very interesting since they are simpler, yet can still probe many of the questions that have been raised in the context of two-body B decays such as the perturbative and nonperturbative nature of charming penguins [5] and the search for new physics signals [6]. Theoretical simplification occurs in the endpoint region, where the energy of the light meson M is relatively close to the maximal energy, so that the isolated energetic meson M and the inclusive collinear hadronic jet X go in opposite directions.…”

Model independent method for a quantitative estimation ofSU(3)flavor symmetry breaking using Dalitz plot distributions

“…states do not contribute since the parent particle B + is a U-spin singlet, and only the ∆U = 1 2 current contributes to the decay. This unique feature follows from the fact that the electroweak penguin does not violate U-spin as d and s quarks carry the same electric charge (see [34] can contribute to the decay amplitude and they correspond to anti-symmetric and symmetric contributions under K 0 ↔ π 0 respectively. The U-spin amplitudes…”