Magdalena Djordjevic

Heavy Quark Radiative Energy Loss in QCD Matter

Abstract Heavy quark medium induced radiative energy loss is derived to all orders in opacity, (L/λg)n. The analytic expression generalizes the GLV opacity expansion for massless quanta to heavy quarks with mass M in a QCD plasma with a gluon dispersion characterized by an asymptotic plasmon mass, m g =gT/ 2 . Remarkably, we find that the general result is obtained by simply shifting all frequencies in the GLV series by (mg2+x2M2)/(2xE). Numerical evaluation of the first order in opacity energy loss shows that both charm and bottom energy losses are much closer to the incoherent radiation limit than light partons in nuclear collisions at both RHIC and LHC energies. However, the radiation lengths of heavy quarks remain large compared to nuclear dimensions and hence high pT heavy quark production is volume rather than surface dominated.

Influence of bottom quark jet quenching on single electron tomography of Au + Au

Influence of Bottom Quark Jet Quenching on Single Electron Tomography of Au+Au Magdalena Djordjevic, 1 Miklos Gyulassy, 1 Ramona Vogt, 2 and Simon Wicks 1 Department of Physics, Columbia University, 538 West 120-th Street, New York, NY 10027 Nuclear Science Division, LBNL, Berkeley, CA 94720 and Physics Department, University of California, Davis, California 95616 (Dated: July 21, 2005) High transverse momentum single (non-photonic) electrons are shown to be sensitive to the stop- ping power of both bottom, b, and charm, c, quarks in AA collisions. We apply the DGLV theory of radiative energy loss to predict c and b quark jet quenching and compare the FONLL and PYTHIA heavy flavor fragmentation and decay schemes. We show that single electrons in the p T = 5 − 10 GeV range are dominated by the decay of b quarks rather than the more strongly quenched c quarks in Au+Au collisions at s = 200 AGeV. The smaller b quark energy loss, even for extreme opacities with gluon rapidity densities up to 3500, is predicted to limit the nuclear modification factor, R AA , of single electrons to the range R AA ∼ 0.5−0.6, in contrast to previous predictions of R AA 3 GeV in pp collisions. In this letter, we show that jet quenching further amplifies the b contribution to the lepton spectrum and strongly limits the nuclear modification factor of electrons in AA collisions. The preliminary electron data [24]-[25] are so surpris- ing that novel jet energy loss mechanisms may have to be postulated [28]-[31]. The elliptic flow of high p T heavy quarks can be accounted for, e.g., if the elastic cross sec- tions of all partons, including bottom, are assumed to be anomalously enhanced to > 20 mb, far in excess of per- turbative QCD predictions, up to at least p T ∼ 10 GeV. While these enhanced cross sections could lead to heavy flavor elliptic flow at the pion level even at high p T , they may greatly overestimate the attenuation of light and heavy flavored hadrons [31]-[33]. Given the critical role that single electron tomography of the sQGP may play in the near future, it is especially important to scrutinize the theoretical uncertainties and robustness of current predictions. This is the aim of this letter. Theoretical framework. The calculation of the lepton spectrum includes initial

Open Charm and Beauty at Ultrarelativistic Heavy Ion Colliders

Important goals of BNL RHIC and CERN LHC experiments with ion beams include the creation and study of new forms of matter, such as the quark gluon plasma. Heavy quark production and attenuation provide unique tomographic probes of that matter. We predict the suppression pattern of open charm and beauty in Au+Au collisions at RHIC and LHC energies based on the DGLV formalism of radiative energy loss. A cancellation between effects due to the sqrt[s] energy dependence of the high p(T) slope and heavy quark energy loss is predicted to lead to surprising similarity of heavy quark suppression at RHIC and LHC.

Where is the charm quark energy loss at RHIC

Abstract Heavy quark energy loss in a hot QCD plasma is computed taking into account the competing effects due to suppression of zeroth order gluon radiation below the plasma frequency and the enhancement of gluon radiation due to first order medium induced bremsstrahlung. The results suggest a surprising degree of cancellation between the two medium effects for charm quarks and provides a possible explanation for the null effect observed by PHENIX in the prompt electron spectrum in Au+Au at s =130 A GeV.

Ter-Mikayelian effect on QCD radiative energy loss

The color dielectric modification of the gluon dispersion relation in a dense QCD medium suppresses both the soft and collinear gluon radiation associated with jet production. We compute the longitudinal and transverse plasmon contributions to the zeroth order in opacity radiative energy loss in the one-loop hard thermal loop approximation. This is QCD analog of the Ter-Mikayelian effect in QED and leads to

Heavy flavor puzzle at LHC: a serendipitous interplay of jet suppression and fragmentation.

ensuremath{sim}30%

Charm Quark Suppression and Elliptic Flow at RHIC

reduction of the energy loss of high transverse momentum charm quarks produced in a QCD plasma with a characteristic Debye mass

Heavy quark radiative energy loss—applications to RHIC

ensuremath{mu}ensuremath{sim}0.5mathrm{GeV}.

Heavy Quark Tomography of A+A Including Elastic and Inelastic Energy Loss

Both charged hadrons and D mesons are considered to be excellent probes of QCD matter created in ultrarelativistic heavy ion collisions. Surprisingly, recent experimental observations at LHC show the same jet suppression for these two probes, which--contrary to pQCD expectations--may suggest similar energy losses for light quarks and gluons in the QCD medium. We here use our recently developed energy loss formalism in a finite-size dynamical QCD medium to analyze this phenomenon that we denote as the heavy flavor puzzle at LHC. We show that this puzzle is a consequence of an unusual combination of the suppression and fragmentation patterns and, in fact, does not require invoking the same energy loss for light partons. Furthermore, we show that this combination leads to a simple relationship between the suppressions of charged hadrons and D mesons and the corresponding bare quark suppressions. Consequently, a coincidental matching of jet suppression and fragmentation allows considerably simplifying the interpretation of the corresponding experimental data.