We consider momentum broadening and energy loss of high momentum partons in a hot non-Abelian plasma due to collisions. We solve the coupled system of Wong-Yang-Mills equations on a lattice in real time, including binary hard elastic collisions among the partons. The collision kernel is constructed such that the total collisional energy loss and momentum broadening are lattice spacing independent. We find that the transport coefficient $hat{q}$ corresponding to transverse momentum broadening receives sizable contributions from a power-law tail in the $p_perp$-distribution of high-momentum partons. We establish the scaling of $hat{q}$ and of $dE/dx$ with density, temperature and energy in the weak-coupling regime. We also estimate the nuclear modification factor $R_{AA}$ due to elastic energy loss of a jet in a classical Yang-Mills field.
We perform numerical simulations of the QCD Boltzmann-Vlasov equation including both hard elastic particle collisions and soft interactions mediated by classical Yang-Mills fields. We provide an estimate of the coupling of jets to a hot plasma which is independent of infrared cutoffs. For weakly-coupled anisotropic plasmas the local rotational symmetry in momentum space is broken. The fields develop unstable modes, forming configurations where B_t>E_t and E_z>B_z. This provides a possible explanation for the experimental observation that high-energy jets traversing the plasma perpendicular to the beam axis experience much stronger broadening in rapidity than in azimuth.
We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include 2<->2 scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.
We study the impact of transverse-momentum dependent parton distributions on detailed features of multi-jet final states, focusing on angular jet correlations in DIS data.
This talk discusses recent results for next-to-next-to-leading order (NNLO) QCD corrections to jet cross sections and transverse momentum distributions. The results are obtained in the NNLOJET code framework, which provides an implementation of the antenna subtraction method for the handling of infrared singular contributions at NNLO. We briefly describe the NNLOJET implementation, with particular emphasis on the construction of the real radiation phase space, which is tailored to ensure stability in all infrared sensitive regions.
Heavy ion collisions at high energies can be used as an interesting way to recreate and study the medium of the quark-gluon plasma (QGP). We particularly investigate the jets produced in hard binary collisions and their interactions with a tentative medium. These jets were obtained numerically from the Monte-Carlo simulations of hard collisions using the KATIE-algorithm [1], where parton momenta within the colliding nucleons were describe by means of unintegrated parton distribution functions (uPDF). We evolved these jets within a medium that contains both, transverse kicks (yielding a broadening in momentum transvers to the jet-axis) as well as medium induced radiation within the MINCAS-algorithm [2] following the works of [3,4]. We produce qualitative results for the decorrelation of dijets. In particular, we study deviations from a transverse momentum broadening that follows a Gaussian distribution. [1] A. van Hameren, Comput.Phys.Commun. 224 (2018) 371-380 [2] K. Kutak, W. P{l}aczek, R. Straka, Eur.Phys.J. C79 (2019) no.4, 317 [3] J.-P. Blaizot, F. Dominguez, E. Iancu, Y. Mehtar-Tani, JHEP 1301 (2013) 143 [4] J.-P. Blaizot, F. Dominguez, E. Iancu, Y. Mehtar-Tani, JHEP 1406 (2014) 075
Bjoern Schenke
,Michael Strickland
,Adrian Dumitru
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(2009)
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"Transverse momentum diffusion and jet energy loss in non-Abelian plasmas"
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Bj\\\"orn Schenke
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