5 research outputs found
Mass effect and coherence in medium-induced QCD radiation off a antenna
The medium-induced one-gluon radiation spectrum off a massive quark-antiquark
() antenna traversing a colored QCD medium is calculated in this
contribution. The gluon spectrum off the antenna computed at first order in the
opacity expansion is collinear finite but infrared divergent, which is
different from the result obtained from an independent emitter which is both
infrared and collinear finite. The interference between emitters dominates the
soft gluon radiation when the antenna opening angle is small and the emitted
gluon is soft, whereas the antenna behaves like a superposition of independent
emitters when the opening angle is large and the radiated gluon is hard. As a
phenomenological consequence, we investigate the energy lost by the projectiles
due to the radiation. In general, the size of the mass effects is similar in
both cases.Comment: 4 pages, 1 figure, Proceedings of Quark Matter 2011, Annecy, Franc
The physics potential of proton-nucleus collisions at the TeV scale
The LHC brings nuclear collisions to the TeV scale for the first time and the
first data show the qualitative differences of this new regime. The
corresponding phase-space available encompasses completely uncharted regions of
QCD in which high-density or high-temperature domains can be identified.
Proton-nucleus runs are essential for a complete interpretation of the data and
for the study of new regimes dominated by large occupation numbers in the
hadronic wave function. I comment here the physics opportunities for p+Pb runs
at the LHC and d+Au runs at RHIC and the corresponding needs in view of the new
Pb+Pb data from the LHC.Comment: Proceedings of the conference Quark Matter 2011, Annecy (France) May
201
Jet Quenching via Jet Collimation
The ATLAS Collaboration recently reported strong modifications of dijet
properties in heavy ion collisions. In this work, we discuss to what extent
these first data constrain already the microscopic mechanism underlying jet
quenching. Simple kinematic arguments lead us to identify a frequency
collimation mechanism via which the medium efficiently trims away the soft
components of the jet parton shower. Through this mechanism, the observed dijet
asymmetry can be accomodated with values of that lie in the
expected order of magnitude.Comment: 6 pages, 4 figure