By looking at the pseudoscalar-vector meson spectra in the $bar{B}to J/psi rhobar{K}$ and $bar{B}to J/psi bar{K}^*pi$ weak decays, we theoretically investigate the double-pole structure of the $K_1(1270)$ resonance by using the Chiral Unitary approach to account for the final state interactions between the pseudoscalar and vector mesons. The $K_1(1270)$ resonance appears as dynamically generated through these interactions in coupled channels and influence the shape of the invariant mass distributions under consideration. We show how those shapes are affected by the $K_1(1270)$ double-pole structure to confront the results from our model with future experiments that might investigate the $PV$ spectra in these decays.
We study the decay processes of $bar{B}^0 to J/psi bar{K}^{*0} K^0$ and $bar{B}^0 to J/psi f_1(1285)$ to analyse the $f_1(1285)$ resonance. By the calculation within chiral unitary approach where $f_1(1285)$ resonance is dynamically generated from the $K^*bar{K}-c.c.$ interaction, we find that the $bar{K}^{*0} K^0$ invariant mass distribution has a clear broad peak. Such broad peak has been understood as the signal of the $f_1(1285)$. Finally, we obtain a theoretical result $R_t=Gamma_{bar{B}^0 to J/psi bar{K}^{*0} K^0}/Gamma_{bar{B}^0 to J/psi f_1(1285)}$ which is expected to be compared with the experimental data.
We demonstrate that dispersion theory allows one to deduce crucial information on $pieta$ scattering from the final-state interactions of the light mesons visible in the spectral distributions of the decays $bar{B}^0_d to J/psi(pi^0eta,K^+K^-,K^0bar{K}^0)$. Thus high-quality measurements of these differential observables are highly desired. The corresponding rates are predicted to be of the same order of magnitude as those for $bar{B}^0_d to J/psipi^+pi^-$ measured recently at LHCb, letting the corresponding measurement appear feasible.
Based on a $J/psi$ data sample of $7.8 times 10^6$ events at BESI, the decay of $ J/psi to bar{K}^*(892)^0 K^+ pi^-$ is studied and a low mass enhancement, which is believed not coming from the phase space effect or background, is visible in the $K^+ pi^-$ invariant mass spectrum recoiling against $bar{K}^*(892)^0$. Partial wave analysis of this channel favors this low mass enhancement being a broad $0^{+}$ resonance with the mass and width of $771^{+164}_{-221}pm 55$ MeV/c$^2$ and $220^{+225}_{-169} pm 97$ MeV/c$^2$, respectively.
An amplitude analysis of flavour-untagged $B_s^0 to J/psi p bar{p}$ decays is performed using a sample of $797pm31$ decays reconstructed with the LHCb detector. The data, collected in proton-proton collisions between 2011 and 2018, correspond to an integrated luminosity of 9 $text{fb}^{-1}$. Evidence for a new structure in the $J/psi p$ and $J/psi bar{p}$ systems with a mass of $4337 ^{+7}_{-4} ^{+2}_{-2}~text{MeV}$ and a width of $29 ^{+26}_{-12} ^{+14}_{-14}~text{MeV}$ is found, where the first uncertainty is statistical and the second systematic, with a significance in the range of 3.1 to 3.7 $sigma$, depending on the assigned $J^P$ hypothesis.
The $B^0$--$bar B^0$ oscillation frequency $Delta m_d$ is measured by the LHCb experiment using a dataset corresponding to an integrated luminosity of $1.0,$fb$^{-1}$ of proton-proton collisions at $sqrt{s} = 7,$TeV, and is found to be $Delta m_d = 0.5156 pm 0.0051,($stat.$) pm 0.0033,($syst.$),$ps$^{-1}$. The measurement is based on results from analyses of the decays $B^0 to D^- pi^+$ ($D^- to K^+ pi^- pi^-$) and $B^0 to J/ psi K^{*0}$ ($ J/ psi to mu^+ mu^-$, $K^{*0} to K^+ pi^-$) and their charge conjugated modes.
J. M. Dias
,G. Toledo
,L. Roca
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(2021)
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"Unveiling the $K_1(1270)$ double-pole structure in the $bar{B}to J/psi rhobar{K}$ and $bar{B}to J/psi bar{K}^*pi$ decays"
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Jorgivan Dias Ph.D.
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