اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStudy of $chi_{bJ}(nP) rightarrow omega Upsilon(1S)$ at Belle
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We report results from a study of hadronic transitions of the $chi_{bJ}(nP)$ states of bottomonium at Belle. The $P$-wave states are reconstructed in transitions to the $Upsilon(1S)$ with the emission of an $omega$ meson. The transitions of the $n=2$ triplet states provide a unique laboratory in which to study nonrelativistic quantum chromodynamics, as the kinematic threshold for production of an $omega$ and $Upsilon(1S)$ lies between the $J=0$ and $J=1$ states. A search for the $chi_{bJ}(3P)$ states is also reported.
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We report a study of radiative decays of chi_{bJ}(1P)(J=0,1,2) mesons into 74 hadronic final states comprising charged and neutral pions, kaons, protons; out of these, 41 modes are observed with at least 5 standard deviation significance. Our measure
ments not only improve the previous measurements by the CLEO Collaboration but also lead to first observations in many new modes. The large sample allows us to probe the total decay width of the chi_{b0}(1P). In the absence of a statistically significant result, a 90% confidence-level upper limit is set on the width at Gamma_{total}< 2.4 MeV. Our results are based on 24.7 fb^{-1} of e+e- collision data recorded by the Belle detector at the Upsilon(2S) resonance, corresponding to (157.8pm3.6)times10^6 Upsilon(2S) decays.
The $e^+e^- to pi^+ pi^- pi^0 chi_{bJ}$ ($J=0,~1,~2$) processes are studied using a 118~fb$^{-1}$ data sample collected at a center-of-mass energy of 10.867 GeV, in the $Upsilon(10860)$ energy range, with the Belle detector. The $pi^+ pi^- pi^0 chi_{
b1}$, $pi^+pi^-pi^0chi_{b2}$, $omegachi_{b1}$ signals and the evidence of $omegachi_{b2}$ are observed for the first time and the cross sections are measured. No significant $pi^+pi^-pi^0chi_{b0}$ or $omegachi_{b0}$ signal is observed and 90% confidence level upper limits on the cross sections for these two processes are obtained. In the $pi^+pi^-pi^0$ invariant mass spectrum, significant non-$omega$ signals are also observed. We search for the $X(3872)$-like state with a hidden $bbar{b}$ component (named $X_b$) decaying into $omega Upsilon(1S)$; no significant signal is observed with a mass between $10.55$ and $10.65$ GeV/$c^2$.
Using data samples of $102times10^6$ $Upsilon(1S)$ and $158times10^6$ $Upsilon(2S)$ events collected with the Belle detector, a first experimental search has been made for double-charmonium production in the exclusive decays $Upsilon(1S,2S)rightarrow
J/psi(psi)+X$, where $X=eta_c$, $chi_{cJ} (J=~0,~1,~2)$, $eta_c(2S)$, $X(3940)$, and $X(4160)$. No significant signal is observed in the spectra of the mass recoiling against the reconstructed $J/psi$ or $psi$ except for the evidence of $chi_{c1}$ production with a significance of $4.6sigma$ for $Upsilon(1S)rightarrow J/psi+chi_{c1}$. The measured branching fraction $BR(Upsilon(1S)rightarrow J/psi+chi_{c1})$ is $(3.90pm1.21(rm stat.)pm0.23 (rm syst.))times10^{-6}$. The $90%$ confidence level upper limits on the branching fractions of the other modes having a significance of less than $3sigma$ are determined. These results are consistent with theoretical calculations using the nonrelativistic QCD factorization approach.
We report the first observation of the radiative decay of the $Upsilon(1S)$ into a charmonium state. The statistical significance of the observed signal of $Upsilon(1S) to gamma chi_{c1}$ is 6.3 standard deviations including systematics. The branchin
g fraction is calculated to be Br($Upsilon(1S) to gamma chi_{c1}$) = (4.7^{+2.4}_{-1.8} (stat) ^{+0.4}_{-0.5} (sys)) * 10^{-5}. We also searched for $Upsilon(1S)$ radiative decays into $chi_{c0,2}$ and $eta_c(1S,2S)$ and set upper limits on their branching fractions. These results are obtained from a 24.9 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider at a center-of-mass energy equal to the $Upsilon(2S)$ mass using $Upsilon(1S)$ tagging by the $Upsilon(2S) to Upsilon(1S) pi^+pi^-$ transitions.
A study of $chi_{b}$ meson production at LHCb is performed on proton-proton collision data, corresponding to 3.0fb$^{-1}$ of integrated luminosity collected at centre-of-mass energies $sqrt{s}=7$ and 8TeV. The fraction of $Upsilon(nS)$ mesons origina
ting from $chi_{b}$ decays is measured as a function of the $Upsilon$ transverse momentum in the rapidity range $2.0 < y^{Upsilon} < 4.5$. The radiative transition of the $chi_{b}(3P)$ meson to $Upsilon(3S)$ is observed for the first time. The $chi_{b1}(3P)$ mass is determined to be $$m(chi_{b1}(3P)) = 10,511.3 pm 1.7 pm 2.5 MeV/c^2,$$ where the first uncertainty is statistical and the second is systematic.
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