相关论文: Order-$v^2$ relativistic corrections to heavy-quar…

I present new results on the quark distribution in an on-shell heavy quark in perturbative QCD and explore its all-order relations with heavy-quark fragmentation. I first compute the momentum distribution function to all orders in the…

Dimensional regularization is incompatible with the standard covariant projection methods that are used to calculate the short-distance coefficients in inclusive heavy quarkonium production and annihilation rates. A new method is developed…

Hadronic annihilation decay rates of P-wave heavy quarkonia are given to next-to-leading order in both $\alpha_s$ and $v^2$. They include ten nonperturbative parameters, which can be rigorously defined as the matrix elements of…

We present a calculation of the rates for Higgs-boson decays to a vector heavy-quarkonium state plus a photon, where the heavy quarkonium states are the J/psi and the Upsilon(nS) states, with n=1, 2, or 3. The calculation is carried out in…

We present two methods for computing dimensionally-regulated NRQCD heavy-quarkonium matrix elements that are related to the second derivative of the heavy-quarkonium wave function at the origin. The first method makes use of a hard-cutoff…

We present and discuss the release of novel sets of collinear, variable-flavor-number-scheme fragmentation functions for axial-vector, fully heavy $T_{4c}(1^{+-})$ and $T_{4b}(1^{+-})$ tetraquarks. Working within the single-parton…

Bound states of heavy $\bar{q}q$ quarks are reviewed within the context of QCD. First of all, we consider the calculations which can be performed {\sl ab initio}, which includes $\bar{t}t$ with principal quantum number $n$ up to four,…

We improve the pNRQCD approach to annihilation processes of heavy quarkonium and make first pNRQCD predictions for exclusive electromagnetic production of heavy quarkonium. We consider strongly coupled quarkonia, i.e., quarkonia that are…

We investigate the inclusive hadroproduction of pseudoscalar heavy quarkonia, $\eta_c$ and $\eta_b$ mesons, in high-energy proton collisions. Our framework bases on the single-parton collinear fragmentation within a variable-flavor number…

We study perturbative and non-perturbative aspects of heavy-quark fragmentation into hadrons, emphasizing the large-x region, where x is the energy fraction of the detected hadron. We first prove that when the moment index N and the quark…

The perturbative QCD calculation of heavy quark fragmentation into a heavy meson is extended to predict fragmentation into heavy flavor baryons. This is accomplished by implementing the quark-diquark model of the baryons. Several diquark…

We compute S-wave and P-wave electromagnetic quarkonium decays at order v^7 in the heavy-quark velocity expansion. In the S-wave case, our calculation confirms and completes previous findings. In the P-wave case, our results are in…

We study inclusive processes involving two heavy quarkonia in nonrelativisitic QCD (NRQCD) and demonstrate that, in the presence of two P-wave Fock states, NRQCD factorization breaks down, leaving uncanceled infrared singularities. As…

In the framework of the nonrelativistic QCD and a quark-diquark model of baryons we have obtained the fragmentation functions for heavy quark to split into spin-1/2 and spin-3/2 double heavy baryons. It was predicted the production rates as…

The variational method and the Hamiltonian formalism of QCD are used to derive relativistic, momentum space integral equations for a quark-antiquark system with an arbitrary number of gluons present. As a first step, the resulting infinite…

Perturbative QCD has made significant progress over the last few decades. In the first part, we present an introductory overview of perturbative QCD as seen from a modern viewpoint. We explain the relation between purely perturbative…

We report on calculations of the charmonium and bottomonium spectrum in lattice QCD. We use ensembles of gauge fields with three flavors of sea quarks, simulated with the asqtad improved action for staggered fermions. For the heavy quarks…

It is well known that in perturbation theory existence of quasi-degenerate states can rearrange the order counting. For a heavy quarkonium system, naively, enhanced effects ($l$-changing mixing effects) could contribute already to the…

The failure of observing the $e^+ e^- \to J/\psi+J/\psi$ events at $B$ factories to date is often attributed to the significant negative order-$\alpha_s$ correction. In this work we compute the ${\cal O}(\alpha^2_s)$ correction to this…

For weakly bound quarkonia, we rederive the next-to-leading order cross sections of quarkonium dissociation by partons that include the hard thermal loop (HTL) resummation. Our results calculated with an effective vertex from the…