Factorization Formalism Of Nonrelativistic Quantum Chromodynamics Research Articles

NLO QCD corrections to the Bc -pair hadroproduction

The Bc meson pair, including pairs of pseudoscalar states and vector states, productions in proton-proton collisions are investigated at the next-to-leading order (NLO) accuracy in the nonrelativistic quantum chromodynamics factorization formalism. The corresponding cross sections at the Large Hadron Collider (LHC) with s=14 TeV are evaluated. Numerical results indicate that the NLO corrections are substantial, and even dominate over the leading order contributions. Considering the predicted cross sections are sizable, the Bc-pair production is expected to be observable at the high-luminosity LHC experiment. Published by the American Physical Society 2024

Unraveling gluon jet quenching through [formula omitted] production in heavy-ion collisions

Jet quenching has long been regarded as one of the key signatures for the formation of quark-gluon plasma in heavy-ion collisions. Despite significant efforts, the separate identification of quark and gluon jet quenching has remained as a challenge. Here we show that J/ψ in high transverse momentum (pT) region provides a uniquely sensitive probe of in-medium gluon energy loss since its production at high pT is particularly dominated by gluon fragmentation. Such gluon-dominance is first demonstrated for the baseline of proton-proton collisions within the framework of leading power non-relativistic quantum chromodynamics factorization formalism. We then use the linear Boltzmann transport model combined with hydrodynamics for the simulation of jet-medium interaction in nucleus-nucleus collisions. The satisfactory description of experimental data on both nuclear modification factor RAA and elliptic flow v2 reveals, for the first time, that the gluon jet quenching is the driving force for high pTJ/ψ suppression. This novel finding is further confirmed by the data-driven Bayesian analyses of relevant experimental measurements, from which we also obtain the first quantitative extraction of the gluon energy loss distribution in the quark-gluon plasma.

Complete study on polarization of hadroproduction at QCD next-to-leading order * *The work were achieved by using the HPC Cluster of ITP-CAS. This work was supported in part by the National Natural Science Foundation of China (11905292, 11535002, 11675239, 11745006, 11821505, 11947302, 11975242). It was also supported by Key Research Program of Frontier Sciences, CAS, Grant No. QYZDY-SSW-SYS006 and Y7292610K1

By applying the nonrelativistic quantum chromodynamics factorization formalism to hadroproduction, a complete analysis of the polarization parameters , , and for the production is presented at QCD next-to-leading order. With the long-distance matrix elements extracted from experimental data for the production rate and polarization parameter of hadroproduction, our results provide a good description of the measured parameters and in both the helicity and Collins-Soper frames. In our calculations, the frame invariant parameter is consistent in the two frames. Finally, we mention that there are discrepancies between the available experimental data and corresponding theoretical predictions for .

Remaining parts of the long-standing J/ψ polarization puzzle

Based on the non-relativistic quantum chromodynamics factorization formalism, the polarization parameters $\lambda_{\theta\phi}$ and $\lambda_{\phi}$ of $J/\psi$ hadroproduction are analyzed in helicity frame and calculated at QCD next-to-leading order for the first time. For prompt $J/\psi$ production, we take into account the feeddown contributions from $\chi_{cJ}$ and $\psi(2S)$ decays. The theoretical predictions for the polarization parameters $\lambda_{\theta\phi}$ and $\lambda_{\phi}$ of $J/\psi$ are presented. With the theoretical results we have done the fit to the experimental measurements on yield and polarization for $J/\psi$ hadroproduction simultaneously, and found that the results are coincide with the experimental measurements at the LHC quite well.

NLO QCD corrections forχcJinclusive production atBfactories

The next-to-leading-order quantum chromodynamics (QCD) corrections for ${\ensuremath{\chi}}_{cJ}({^{3}P}_{J}^{[1]},{^{3}S}_{1}^{[8]})$ $P$-wave charmonium-inclusive production at $B$ factories are calculated utilizing the nonrelativistic QCD factorization formalism. Large next-to-leading-order corrections are found, especially for the ${^{3}P}_{0}^{[1]}$ and ${^{3}S}_{1}^{[8]}$ configurations. Numerical evaluation indicates that the total cross sections of ${\ensuremath{\chi}}_{cJ}$-inclusive production processes are of the order of 10 fb, which is accessible in the BELLE II (super-B) experiment.

Relativistic corrections to the semi-inclusive decay ofψandΥ

In the framework of the nonrelativistic quantum chromodynamics factorization formalism, we study the processes of $\psi(nS)$ and $\Upsilon(nS)$ decay into a lepton pair or a charm pair associated with two jets up to the next-to-leading order in velocity expansion. We present the analytic expressions for the differential decay rate to the invariant mass of the lepton pair or charm pair. We find that the ratio of the next-to-leading order short-distance coefficient to the leading order one is in the range from -5.5 to -12.4. The relativistic corrections are so large that they modify the leading order prediction significantly. Utilizing the analytic expressions, we also investigate the relativistic corrections in different kinematic regions and their dependence on the masses of the initial-state quarkonium and the final-state fermion. In addition, we study the momentum distribution of $D^{*+}$ in the process $\Upsilon(1S)\to c\bar{c}gg\to D^{*+}X$.

Relativistic corrections to the exclusive decays ofC-even bottomonia intoS-wave charmonium pairs

Within the nonrelativistic quantum chromodynamics (NRQCD) factorization formalism, we compute the relativistic corrections to the exclusive decays of bottomonia with even charge conjugation parity into $S$-wave charmonium pairs at leading order in the strong coupling constant. Relativistic corrections are resummed for a class of color-singlet contributions to all orders in the charm-quark velocity $v_c$ in the charmonium rest frame. Almost every process that we consider in this work has negative relativistic corrections ranging from -20 to -35,%. Among the various processes, the relativistic corrections of the next-to-leading order in $v_c$ to the decay rate for $\chi_{b2}\to \eta_c(mS)+\eta_c(nS)$ with $m,$ $n=1$ or 2 are very large. In every case, the resummation of the relativistic corrections enhances the rate in comparison with the next-to-leading-order results. We compare our results with available predictions based on the NRQCD factorization formalism. The NRQCD predictions are significantly smaller than those based on the light-cone formalism by an or two orders of magnitudes.