Study of theK+π+π−final state inB+→J/ψK

Abstract

Using 535 Â 10 6 B-meson pairs collected by the Belle detector at the KEKB e þ e À collider, we measure branching fractions of ð7:16 AE 0:10ðstatÞ AE 0:60ðsystÞ Â 10 À4 for B þ ! J=c K þ þ À and ð4:31 AE 0:20ðstatÞ AE 0:50ðsystÞÞ Â 10 À4 for B þ ! c 0 K þ þ À . We perform amplitude analyses to determine the resonant structure of theis a prominent component of both decay modes. There is significant interference among the different intermediate states, which leads, in particular, to a striking distortion of the line shape due to the !. Based on the results of the fit to the B þ ! J=c K þ þ À data, the relative decay fractions of the K 1 ð1270Þ to K , K!, and K Ã ð892Þ are consistent with previous measurements, but the decay fraction to K Ã 0 ð1430Þ is significantly smaller. Finally, by floating the mass and width of the K 1 ð1270Þ in an additional fit of the B þ ! J=c K þ þ À data, we measure a mass of ð1248:1 AE 3:3ðstatÞ AE 1:4ðsystÞÞ MeV=c 2 and a width of ð119:5 AE 5:2ðstatÞ AE 6:7ðsystÞÞ MeV=c 2 for the K 1 ð1270Þ.

Testing the standard model with D(s)→K1(→Kππ)

“…as δ ρ = −(43.8 ± 4.0 ± 7.3) • [22]. A similar value was found in the reanalysis of the ACCMOR data [26] by the Babar collaboration, as δ ρ = (−31 ± 1) • [27].…”

“…Specifically, black, red, green and magenta lines correspond to ξ K 1 (1400) = 0, +0.5, +1 and −1, respectively, for fixed ξ K 1 (1270) = 1. The blue curve refers to only the K 1 (1400) being present, with The measured invariant mass m Kππ spectrum in B + → K + π + π − γ decays [22][23][24] exhibits the dominant K 1 (1270)-peak along with a K 1 (1400)-shoulder, plus higher resonances. For our model, these measurements suggest a value of ξ K 1 (1400) /ξ K 1 (1270) around +1, see Fig.…”

First observations of the rare decays B + → K + π + π − μ + μ − and B +→ ϕK + μ + μ −

“…The K + π + π − system in the final state of the B + →K + π + π − µ + µ − decay can result from the decay of several strange resonances. Its composition was studied by the Belle collaboration for the tree-level decay B + → J/ψ (→ µ + µ − )K + π + π − [5], where the K 1 (1270) + meson was found to have a prominent contribution. The K 1 (1270) + and the K 1 (1400) + mesons are the mass eigenstates that result from mixing of the P -wave axial vector mesons 3 P 1 (K 1A ) and 1 P 1 (K 1B ) with the mixing angle θ K 1 [6].…”

Future prospects for the determination of the Wilson coefficient $ C_{{^{{7\gamma }}}}^{\prime } $

“…It must be emphasized that in our study [19] we used the hadronic model only for the illustration and demonstration of the DDLR method. These systematic uncertainties can be significantly reduced by an accurate, model-independent, partial wave analysis of the K 1 -decays, in particular using the B → J/ψK 1 's decays observed by the Belle collaboration [44].…”