Related papers: New QCD Effects at Large x
We calculate production by vector and axial currents of heavy quark pairs ($c\bar{c}$, $b\bar{b}$, $t\bar{t}$) close to threshold. We take into account strong interaction contributions (including radiative corrections and leading…
A new formula for the heavy quark-antiquark spin dependent potential is given by using the techniques developed in the heavy quark effective theory. The leading logarithmic quark mass terms emerging from the loop contributions are…
The heavy meson light-cone distribution amplitude (LCDA), as defined in full QCD, plays a key role in the collinear factorization for exclusive heavy meson production and in lattice computations of the LCDA within heavy-quark effective…
We investigate QCD amplitudes with massive quarks computed in the four-dimensional helicity scheme (FDH) and dimensional reduction at NNLO and describe how they are related to the corresponding amplitudes computed in conventional…
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 investigate the effect of a strong magnetic field on dynamical chiral symmetry breaking in quenched and unquenched QCD. To this end we apply the Ritus formalism to the coupled set of (truncated) Dyson-Schwinger equations for the quark…
I review recent theoretical progress on the description of heavy quark, jet and gauge boson production at colliders within perturbative QCD. Particular emphasis is put on the improved understanding of fragmentation phenomena, resummation of…
We investigate the impact of quark production on bottom-up thermalization in heavy-ion collisions. First, we extend the parametric estimates of bottom-up thermalization in pure gluon systems by incorporating quark production in the…
We present a perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum $p_T$ at collider energies, which includes both the leading power (LP) and next-to-leading power (NLP) contributions to…
We review on the calculation of the heavy-quark photo-production vector form factors, with the full dependence on the mass of the heavy-quark. The Feynman diagrams are evaluated within the dimensional regularization scheme and expressed in…
We study the drag force of a relativistic heavy quark using a holographic QCD model with conformal invariance broken by a background dilaton. We analyze the effects of chemical potential and confining scale on this quantity, respectively.…
The QCD running coupling $\alpha_s(Q^2)$ sets the strength of the interactions of quarks and gluons as a function of the momentum transfer $Q$. The $Q^2$ dependence of the coupling is required to describe hadronic interactions at both large…
It is becoming increasingly clear that initial state effects inherent to collisions of nuclei play an important role in the interpretation of data from heavy ion collisions at RHIC and the LHC. Such effects are more apparent in kinematic…
We summarize the results of a recent study of heavy quark production and attenuation in cold nuclear matter. In p+p collisions, we investigate the relative contribution of partonic sub-processes to $D$ meson production and $D$…
QCD, the theory of the strong interactions, involves quarks interacting with non-Abelian gluon fields. This theory has many features that are difficult to impossible to see in conventional diagrammatic perturbation theory. This includes…
In the infinite mass limit for a heavy quark its spin decouples from the QCD dynamics, which leads to the heavy-quark spin symmetry. After a short discussion of spin symmetry some applications are considered.
Interactions of heavy quarks, in particular of top quarks, with electroweak gauge bosons are expected to be very sensitive to new physics effects related to electroweak symmetry breaking. These interactions are described by the so-called…
Effects of heavy sea quarks on the low energy physics are described by an effective theory where the expansion parameter is the inverse quark mass, 1/$M$. At leading order in 1/$M$ (and neglecting light quark masses) the dependence of any…
We compute, in the large N limit, the quark potential for ${\cal N}=4$ supersymmetric SU(N) Yang-Mills theory broken to $SU(N_1) \times SU(N_2)$. At short distances the quarks see only the unbroken gauge symmetry and have an attractive…
We study the effect of the resummation of logarithms for t\bar{t} production near threshold and inclusive electromagnetic decays of heavy quarkonium. This analysis is complete at next-to-next-to-leading order and includes the full…