Related papers: Quark fragmentation into spin-triplet $S$-wave qua…
A brief survey of the role of heavy flavors as a probe of the state of matter produced by high energy heavy ion collisions is presented. Specific examples include energy loss, initial state gluon saturation, thermalization and flow. The…
We derive the initial condition for the perturbative fragmentation function of a heavy quark through order O(alpha_s^2) in the MS-bar scheme. This initial condition is useful for computing heavy quark (or lepton, in case of QED) energy…
The observed $D^{**}$ mesons have $c\bar q$ flavor quantum numbers and spin-parity of the light degrees of freedom $s_\ell^{\pi_{\ell}} = 3/2^+$. In the $m_c \rightarrow \infty$ limit the spin of the charm quark is conserved and the $c…
We study single-flavour quark pairing ("self-pairing") in colour-superconducting phases of quark matter, paying particular attention to the difference between scenarios where all three flavours undergo single-flavour pairing, and scenarios…
Fragmentation functions for hadrons composed of heavy quarks are calculated directly from the definitions given by Collins and Soper and are compared with those calculated in another way. A new fragmentaion function for a P-wave meson is…
The longstanding problem of explaining the observed polarization of Lambda hyperons inclusively produced in the high energy collisions of unpolarized hadrons is tackled by considering spin and k_T dependent quark fragmentation functions.…
We study the properties of the colour triplet qqqbar quark cluster when flavour symmetry is broken. The relevance of such a cluster for some models of pentaquarks is then examined in the light of recent experimental signals.
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…
I review a few selected topics concerning heavy-quark fragmentation, taking particular care about bottom- and charm-quark production in $e^+e^-$ annihilation and the inclusion of non-perturbative corrections. In particular, I discuss recent…
It is shown that a perturbative QCD (pQCD) based analysis and the SU(6) quark-diquark model give significant different predictions concerning the flavor and spin structure for the quark distributions of the $\Lambda$-baryon near $x=1$.…
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,…
A summary of measurements of the fragmentation of charm quarks into a specific hadron is given. Measurements performed in photoproduction and deep inelastic scattering in $e^{\pm}p$, $pp$ and $e^+e^-$ collisions are compared, using…
The dominant mechanism to produce hadronic bound states with large transverse momentum is fragmentation, that is the splitting of a high energy parton into a hadronic state and other partons. We review the present schemes to calculate the…
Classical arguments predict that the quark and the antiquark of a pair created during string fragmentation are both transversely polarized in the direction of \hat z \times \vec q_T, where z is the direction of the pull exerted by the…
Charmonium spectroscopy with Kogut-Susskind valence quarks are carried out for quenched QCD at $\beta=6.0$ and for two-flavor full QCD at $\beta=5.7$. Results for 1P--1S mass splitting and estimates of $\alpha^{(5)}_{\overline{MS}}(m_Z)$…
Transition generalized parton distributions have emerged as a novel tool for studying the quantum chromodynamics (QCD) structure of resonances. They provide an integrated picture of the transition form factors and the transition parton…
We study the relation between the quark distribution function q(x) and the fragmentation function D_q(z) based on a general form D_q(x) = C(z)z^{alpha}q(z) for valence and sea quarks. By adopting two known parametrizations of quark…
We consider the singular behaviour of one-loop QCD matrix elements when several external partons become simultaneously parallel. We present a new factorization formula that describes the singular collinear behaviour directly in colour…
We present a calculation of the charmonium spectrum with three flavors of dynamical staggered quarks from gauge configurations that were generated by the MILC collaboration. We use the Fermilab action for the valence charm quarks. Our…
In the paper, we derive the next-to-leading order (NLO) fragmentation function for a heavy quark, either charm or bottom, into a heavy quarkonium $J/\Psi$ or $\Upsilon$. The ultra-violet divergences in the real corrections are removed…