Multistage Monte Carlo simulation of jet modification in a static medium

Abstract

The modification of hard jets in an extended static medium held at a fixed temperature is studied using three different Monte-Carlo event generators (LBT, MATTER, MARTINI). Each event generator contains a different set of assumptions regarding the energy and virtuality of the partons within a jet versus the energy scale of the medium, and hence, applies to a different epoch in the space-time history of the jet evolution. For the first time, modeling is developed where a jet may sequentially transition from one generator to the next, on a parton-by-parton level, providing a detailed simulation of the space-time evolution of medium modified jets over a much broader dynamic range than has been attempted previously in a single calculation. Comparisons are carried out for different observables sensitive to jet quenching, including the parton fragmentation function and the azimuthal distribution of jet energy around the jet axis. The effect of varying the boundary between different generators is studied and a theoretically motivated criterion for the location of this boundary is proposed. The importance of such an approach with coupled generators to the modeling of jet quenching is discussed.

Drag induced radiation and multi-stage effects in heavy-flavor energy loss

“…These extra contributions lead to an enhancement of the radiative loss rate, compensating for the reduction due to the dead-cone effect. Future improvements on this formalism will require calculations to be done within a multi-stage Monte-Carlo event generator as developed by the JETSCAPE collaboration [11], where the medium modified DGLAP stage, the Gunion-Bertsch and BDMPS phases can be applied over each path travelled by the hard quark.…”

“…Such a multi-stage approach was recently applied to the case of light quarks and gluons in Ref. [11]. In that effort, the existence of a high virtuality and low virtuality stage in the radiation from a hard parton, allowed for a natural mechanism for the medium modified jet shape.…”

Molière scattering in quark-gluon plasma: finding point-like scatterers in a liquid

“…[26][27][28][29]. In the case of a Monte Carlo calculation in which hard two-to-two scattering is already included, for example those done within JEWEL [30][31][32][33][34][35], MARTINI [36] or LBT [37][38][39], our results can be used in a different way, namely as a benchmark against which to compare for the purpose of identifying observable consequences of large-angle scattering. The other way in which the results of our calculation will be of value is as a qualitative guide to experimentalists with which to assess how large the effects of interest may turn out to be, namely as a qualitative guide to what the probability is that a parton with a given energy in a jet could scatter by an angle θ.…”

Jets in QCD matter: Monte Carlo approaches

“…The variety of jet quenching models, which might seem surprisingly large, is a direct consequence of our theoretical uncertainty. While there is not yet a consistent picture, efforts are being made to further test and constrain MC models; (i) devising new kind of probes, (ii) continuous development of MC modelling and (iii) creation of a useful testing environment that accommodate several different models, like the recent JETSCAPE Collaboration [18]. While they cannot be used as simple black-boxes, jet quenching MC models based on theoretical results are a powerful tool to take full advantage of current (RHIC and LHC) and future accelerator data.…”