Semileptonic decays of D(s) mesons

Abstract

A symmetry-preserving continuum approach to meson bound states in quantum field theory, employed elsewhere to describe numerous πand K-meson electroweak processes, is used to analyze leptonic and semileptonic decays of D ðsÞ mesons. Each semileptonic transition is conventionally characterized by the value of the dominant form factor at t ¼ 0 and the following results are obtained herein: f D s →K þ ð0Þ ¼ 0.673ð40Þ; f D→π þ ð0Þ ¼ 0.618ð31Þ and f D→K þ ð0Þ ¼ 0.756ð36Þ. Working with the computed t-dependence of these form factors and standard averaged values for jV cd j, jV cs j, one arrives at the following predictions for the associated branching fractions: B D þ s →K 0 e þ ν e ¼ 3.31ð33Þ × 10 −3 , B D 0 →π − e þ ν e ¼ 2.73ð22Þ × 10 −3 , and B D 0 →K − e þ ν e ¼ 3.83ð28Þ%: Alternatively, using the calculated t-dependence, agreement with contemporary empirical results for these branching fractions requires jV cd j ¼ 0.221ð9Þ, jV us j ¼ 0.953ð34Þ. With all D ðsÞ transition form factors in hand, the nature of SU(3)-flavor symmetry breaking in this array of processes can be analysed; and just as in the π-K sector, the magnitude of such effects is found to be determined by the scales associated with emergent mass generation in the Standard Model, not those originating with the Higgs mechanism.

High-Pressure Melt Curve and Phase Diagram of Lithium

“…The observed peaks are shown in Figure 4, and may be fitted to either the oC88 or oC40 phases known experimentally [8]. They are also compatible with the C2 phase predicted by theory [4,28]. Compression at 360 K and 400 K resulted in the sudden loss of fcc diffraction at 32 GPa and 28 GPa, respectively.…”

“…If this is the case, it implies that the intermediate phase between cI16 and the melt is not oC88 and is a new, uncharacterised, phase of lithium. The angles of the observed peaks at 53 GPa and 255 K and 275 K, as well as those of cI16, oC88 and two phases predicted by theory, C2 [4,28] and Pbca [3,4] are shown in Figure 3.…”

“…Reflections observed are not compatible with cI16, while oC88 has a very large number of potential reflections which makes indexing ambiguous. Two candidates from theoretical studies, C2 [4,28] and Pbca [3,4] are also shown. Pbca shows the best fit of all structures tried.…”

In pursuit of new physics with Bd0→J/ψK0 and Bs0→J/ψϕ decays at the high-precision Frontier

“…Lattice QCD [27] and other non-perturbative methods [52][53][54] have illustrated that the flavour symmetries are broken. The ratios between the kaon and pion decay constants, or between the D s and D meson decay constants show that the SU(3) flavour symmetry, which is relevant here, is generically broken at the 20% level.…”

Nucleon elastic form factors at accessible large spacelike momenta

“…This approach was first exploited in Ref. [47], which extended the range of predictions for nucleon-to-Roper-resonance transition form factors out to x ¼ 12, and has since been used to analyze vector-meson elastic form factors and the domain of validity of vector meson dominance models [81] and the semileptonic decays of D ðsÞ mesons [82]. To introduce the approach, suppose that one has N pairs, D ¼ fðx i ; y i ¼ fðx i ÞÞg, being the values of some smooth function, fðxÞ, at a given set of discrete points.…”