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Dmitri Kharzeev

Publications and source records attributed to Dmitri Kharzeev.

47 records · Page 3Linked to original sources
arXiv2004

Nuclear Modification Factor in d+Au Collisions: Onset of Suppression in the Color Glass Condensate

We perform a quantitative analysis of the nuclear modification factor in deuteron--gold collisions R(dAu) within the Color Glass Condensate approach, and compare our results with the recent data from RHIC experiments. Our model leads to Cronin enhancement at mid-rapidity, while at forward rapidities it predicts strong suppression of R(dAu) at all pT due to low-x evolution. We demonstrate that our results are consistent with the data for dAu charged hadron spectra, R(dAu) and R(CP) recently reported for rapidities in the interval eta=0--3.2 by the BRAHMS experiment at RHIC. We also make a prediction for R(pA) at mid-rapidity in pA collisions at the LHC.

hep-ph↗
arXiv2004

Jet Azimuthal Correlations and Parton Saturation in the Color Glass Condensate

We consider the influence of parton saturation in the Color Glass Condensate on the back-to-back azimuthal correlations of high $p_T$ hadrons in $pA$ (or $dA$) collisions. When both near--side and away--side hadrons are detected at mid-rapidity at RHIC energy, the effects of parton saturation are constrained to transverse momenta below the saturation scale $p_T \leq Q_s$; in this case the back-to-back correlations do not disappear but exhibit broadening. However when near-side and away-side hadrons are separated by several units of rapidity, quantum evolution effects lead to the depletion of back-to-back correlations as a function of rapidity interval between the detected hadrons (at fixed $p_T$). This applies to both $pp$ and $pA$ (or $dA$) collisions; however, due to the initial conditions provided by the Color Glass Condensate, the depletion of the back-to-back correlations is significantly stronger in the $pA$ case. An experimental study of this effect would thus help to clarify the origin of the high $p_T$ hadron suppression at forward rapidities observed recently at RHIC.

hep-ph↗
arXiv2003

Cronin Effect and High-p_T Suppression in pA Collisions

We review the predictions of the theory of Color Glass Condensate for gluon production cross section in p(d)A collisions. We demonstrate that at moderate energies, when the gluon production cross section can be calculated in the framework of McLerran-Venugopalan model, it has only partonic level Cronin effect in it. At higher energies/rapidities corresponding to smaller values of Bjorken x quantum evolution becomes important. The effect of quantum evolution at higher energies/rapidities is to introduce suppression of high-p_T gluons slightly decreasing the Cronin enhancement. At still higher energies/rapidities quantum evolution leads to suppression of produced gluons at all values of p_T.

hep-ph↗
arXiv2002

Generalized scaling of the transverse mass spectrum at the Relativistic Heavy-Ion Collider

We argue that the transverse mass spectra of identified hadrons as measured in gold-gold collisions at BNL's Relativistic Heavy-Ion Collider (RHIC) follows a generalized scaling law. Such a scaling behavior is motivated by the idea of a Color Glass Condensate, or more generally, saturation of the gluon density. In particular, we describe the shapes of transverse mass spectra as a function of centrality. This scaling of the transverse mass spectrum is shown to be consistent with previously observed scaling of multiplicity with centrality.

nucl-th↗
arXiv1999

Pionic Measures of Parity and CP Violation in High Energy Nuclear Collisions

The collisions of large nuclei at high energies could produce metastable vacua which are odd under parity, P, charge conjugation, C, and/or CP. Using only the three-momenta of charged pions (or kaons), we show how to construct global observables which are odd under P, C, and CP, and which can be measured on an event by event basis. Model dependent estimates of the P-odd observables are on the order of 10^(-3).

hep-ph↗
arXiv1998

The Glueball Filter in Central Production and Broken Scale Invariance

We propose a possible explanation of the kinematical dependence of the central production of the scalar glueball candidate observed recently by the WA91 and WA102 Collaborations, and discussed by Close and Kirk, in the context of the broken scale invariance of QCD. The dependences of glueball production on the transverse momenta and azimuthal angles of the final-state protons may be related to the structure of the trace anomaly in QCD.

hep-ph↗
arXiv1998

Observation of Partial U_A(1) Restoration from Two-Pion Bose-Einstein Correlations

The effective intercept parameter of the two-pion Bose-Einstein correlation function, lambda_*, is found to be sensitive to the partial restoration of U_A(1) symmetry in ultra-relativistic nuclear collisions. An increase in the yield of the eta' meson, proposed earlier as a signal of partial U_A(1) restoration, is shown to create a ``hole'' in the low p_t region of lambda_*. A comparison with NA44 data from central S+Pb collisions at 200 AGeV is made and implications for future heavy ion experiments are discussed.

nucl-th↗
arXiv1995

The Proton Spin Puzzle and $Λ$ Polarization in Deep--Inelastic Scattering

We point out that measurements of longitudinal $Λ$ polarization in the target fragmentation region of deep--inelastic $ν\,N$ and $μ\,N$ or $e \, N$ scattering may test dynamical mechanisms invoked to explain the proton spin puzzle. A previously-proposed model for polarized $\bar s s$ pairs in the proton wave function reproduces successfully the negative $Λ$ polarization found in the WA59 $\bar ν\, N$ experiment, and makes predictions that could be tested in future $μ\, N$ and $e \, N$ experiments.

hep-ph↗