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تسجيل مستخدم جديدSpin correlations in polarizations of P-wave charmonia $chi_{cJ}$ and impact on $J/psi$ polarization
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Based on a general form of the effective vertex functions for the decays of P-wave charmonia $chicj$, angular distribution formulas for the subsequent decays $chicjrightarrow jpsi gamma$ and $jpsi to mu^+mu^-$ are derived. The formulas are the same as those obtained in a different approach in the literature. Our formulas are expressed in a more general form, including parity violation effects and the full angular dependence of $jpsi$ and muon in the cascade decay $chicjtojpsigammatomu^+mu^-gamma$. The $chicj$ polarization observables are expressed in terms of rational functions of the spin density matrix elements of $chicj$ production. Generalized rotation-invariant relations for arbitrary integer-spin particles are also derived and their expressions in terms of observable angular distribution parameters are given in the $chi_{c1}$ and $chi_{c2}$. To complement our previous direct-$jpsi$ polarization result, we also discuss the impact on the observable prompt-$jpsi$ polarization. As an illustrative application of our angular distribution formulas, we present the angular distributions in terms of the tree-level spin density matrix elements of $chi_{c1}$ and $chi_{c2}$ production in several different frames at the Large Hadron Collider. Moreover, a reweighting method is also proposed to determine the entire set of the production spin density matrix elements of the $chi_{c2}$, some of which disappear or are suppressed for vanishing higher-order multipole effects making the complete extraction difficult experimentally.
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Using $4.479 times 10^{8}$ $psi(3686)$ events collected with the BESIII detector, we search for the decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$. The decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0
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We compute fragmentation corrections to hadroproduction of the quarkonium states $J/psi$, $chi_{cJ}$, and $psi(2S)$ at leading power in $m_c^2/p_T^2$, where $m_c$ is the charm-quark mass and $p_T$ is the quarkonium transverse momentum. The computatio
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, and $J/psi to$ anything distributions, including distributions of the number of charged tracks, electromagnetic calorimeter showers, and $pi^0$s, and to compare them with distributions obtained from the BESIII Monte Carlo simulation. Information from each Monte Carlo simulated decay event is used to construct matrices connecting the detected distributions to the input predetection produced distributions. Assuming these matrices also apply to data, they are used to predict the analogous produced distributions of the decay events. Using these, the charged particle multiplicities are compared with results from MARK I. Further, comparison of the distributions of the number of photons in data with those in Monte Carlo simulation indicates that G-parity conservation should be taken into consideration in the simulation.
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er (NLO) level in $alpha_s$, within the nonrelativistic QCD framework. It is found that the $mathcal O (alpha^3alpha_s)$-order terms that represent the tree-level interference are comparable with the usual NLO QCD corrections, especially for the $chi_{c1}$ and $chi_{c2}$ cases. To explore the effect of the higher-order terms, namely $mathcal O (alpha^3alpha_s^2)$, we perform the QCD corrections to these $mathcal O (alpha^3alpha_s)$-order terms for the first time, which are found to be able to significantly influence the $mathcal O (alpha^3alpha_s)$-order results. In particular, in the case of $chi_{c1}$ and $chi_{c2}$, the newly calculated $mathcal O (alpha^3alpha_s^2)$-order terms can to a large extent counteract the $mathcal O (alpha^3alpha_s)$ contributions, evidently indicating the indispensability of the corrections. In addition, we find that, as the collision energy rises, the percentage of the interference effect in the total cross section will increase rapidly, especially for the $chi_{c1}$ case.
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