SU(3)-flavor anatomy of nonleptonic charm decays

Abstract

We perform a comprehensive SU (3)-flavor analysis of charmed mesons decaying to two pseudoscalar SU (3)-octet mesons. Taking into account SU (3)-breaking effects induced by the splitting of the quark masses, ms = m u,d , we find that existing data can be described by SU (3)-breaking of the order 30%. The requisite penguin enhancement to accommodate all data on CP violation tends to be even larger than the one extracted from ∆aalone, strengthening explanations beyond the standard model. Despite the large number of matrix elements, correlations between CP asymmetries allow potentially to differentiate between different scenarios for the underlying dynamics, as well as between the standard model and various extensions characterized by SU (3) symmetry and its subgroups. We investigate how improved measurements of the direct CP asymmetries in singly-Cabibbo-suppressed decays can further substantiate the interpretation of the data. We show that particularly informative are the asymmetries in

Implications of LHCb measurements and future prospects

“…In fact, there is consensus that a SM explanation for a dir CP would have to proceed via dynamical enhancement of the long-distance "penguin contraction" contributions to the penguin amplitudes, i.e., penguins with s and d quarks inside the "loops". Research addressing the direct CP asymmetry in the SM has largely fallen into one of two categories: (i) flavour SU(3) f or U-spin fits to the D decay rates, to check that an enhanced penguin amplitude can be accommodated [457][458][459][460][461][462][463] (this, by itself, would not mean that a dir CP is due to SM dynamics); (ii) rough estimates of the magnitudes of certain contributions to the long-distance penguin contractions [461,[464][465][466], to check if, in fact, it is reasonable that SM dynamics could yield the enhanced penguin amplitudes returned by the SU(3) f or U-spin fits.…”

Measurement of the time-integrated CP asymmetry in D 0 → K S 0 K S 0 decays

“…Although measurements of the time-integrated CP asymmetry in D 0 decays to pairs of charged mesons showed hints of CP asymmetry at the level of 0.7 %, the combined results are not yet conclusive [1][2][3][4][5]. Of particular interest, both for the search of New Physics and for the understanding of penguin contributions, are decays of D 0 mesons into a pair of neutral mesons, such as the decay D 0 → K 0 S K 0 S [6,7]. 1 If the CP asymmetry in D 0 decays to charged mesons is confirmed and assuming moderate breaking of the SU(3) flavour symmetry, the CP asymmetry of this mode could be of O(1 %) or even larger [6].…”

“…Of particular interest, both for the search of New Physics and for the understanding of penguin contributions, are decays of D 0 mesons into a pair of neutral mesons, such as the decay D 0 → K 0 S K 0 S [6,7]. 1 If the CP asymmetry in D 0 decays to charged mesons is confirmed and assuming moderate breaking of the SU(3) flavour symmetry, the CP asymmetry of this mode could be of O(1 %) or even larger [6]. From a more recent Standard Model based analysis of the contributing amplitudes, a 95 % confidence level upper limit of 1.1 % for direct CP violation in the decay D 0 → K 0 S K 0 S has been derived [7].…”

B decays to two pseudoscalars and a generalized ΔI=12 rule

“…can be attained with only a "mild" enhancement of F and G relative to the other reduced matrix elements of about an order of magnitude [14][15][16][17][18][19]. The enhancement in F and G is similar to that of the ∆I = 1/2 rule in that it appears in matrix elements of the smallest SU (3)-representation of the Hamiltonian.…”