We study parton suppression effects in heavy-ion collisions within the Parton Quenching Model (PQM). After a brief summary of the main features of the model, we present comparisons of calculations for the nuclear modification and the away-side suppression factor to data in Au+Au and Cu+Cu collisions at √ sNN = 200 GeV. We discuss properties of light hadron probes and their sensitivity to the me...

We study parton suppression effects in heavy-ion collisions within the Parton Quenching Model (PQM). After a brief summary of the main features of the model, we present comparisons of calculations for the nuclear modification and the away-side suppression factor to data in Au+Au and Cu+Cu collisions at √ sNN = 200 GeV. We discuss properties of light hadron probes and their sensitivity to the me...

It has been suggested that parton distributions in coordinate space, so called Ioffe-time distributions, provide a more natural object for non-perturbative methods compared to the usual momentum distributions. In this paper we argue that the shape of experimentally determined Ioffe-time distributions of quarks in a nucleon target clearly indicates separation of longitudinal scales, which is not...

has inspired much theoretical and experimental effort to understand the internal spin structure of the nucleon [ 1]. A key issue [ 2] is the role of the axial anomaly in the transition from parton to constituent quark degrees of freedom in low energy QCD. In this paper I explain why some fraction of proton’s spin may be carried by gluon topology. The topological contribution has support only at...

Modified Altarelli–Parisi splitting functions were lately proposed to model multi-parton radiation in a dense medium and describe jet quenching, one of most striking features of heavy-ion collisions. We implement mediummodified splitting functions in the HERWIG parton shower algorithm, which satisfies the angular ordering prescription, and present a few partonlevel results, such as transverse m...

In the Bjorken limit of the present theory of deep inelastic scattering (DIS) the structure functions (up to anomalous dimensions and perturbative QCD corrections) are described by the parton model. However the current operator in the parton model does not properly commute with the representation operators corresponding to the Lorentz group, space reflection and time reversal. To investigate th...

We discuss two topics in this talk. One is a brief overview of nuclear parton distributions, and the other is SU(2)-flavor-symmetry breaking in nuclear antiquark distributions. First, we show that nuclear structure functions F 2 (x) could be explained in a Q rescaling model with parton recombination effects. Then, nuclear gluon distributions are discussed in this parton model. We point out othe...

Parton distributions contain factorizable final state interaction effects originating from the fast-moving jet, produced by the highly virtual probe which strikes the active parton in the hadron, interacting with the target spectators. We show that these interactions lead to gauge-invariant transverse momentum-dependent parton distributions in deeply inelastic scattering. As compared to previou...

The space and time evolution of initial parton production in ultrarelativistic heavy ion collisions is investigated within the framework of perturbative QCD which includes both initial and final state radiations. Uncertainty principle is used to relate the life time of a radiating parton to its virtuality and momentum. The interaction time of each hard or semihard parton scattering is also take...