Non-Abelian Bremsstrahlung and Azimuthal Asymmetries in High Energy p+A Reactions

We apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute the all-order in nuclear opacity non-abelian gluon bremsstrahlung of event-by-event fluctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, $v_n^M\{1\}$, and even number $2\ell$ gluon, $v_n^M\{2\ell\}$ inclusive distributions in high energy p+A reactions as a function of harmonic $n$, %independent target recoil cluster number, $M$, and gluon number, $2\ell$, at RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form Color Scintillation Antenna (CSA) arrays that lead to characteristic boost non-invariant trapezoidal rapidity distributions in asymmetric $B+A$ nuclear collisions. The scaling of intrinsically azimuthally anisotropic and long range in $\eta$ nature of the non-abelian \br leads to $v_n$ moments that are similar to results from hydrodynamic models, but due entirely to non-abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic non-flow solutions are similar to recent numerical saturation model predictions but differ by predicting a simple power-law hierarchy of both even and odd $v_n$ without invoking $k_T$ factorization. A test of CSA mechanism is the predicted nearly linear $\eta$ rapidity dependence of the $v_n(k_T,\eta)$. Non-abelian beam jet \br may thus provide a simple analytic solution to Beam Energy Scan (BES) puzzle of the near $\sqrt{s}$ independence of $v_n(p_T)$ moments observed down to 10 AGeV where large $x$ valence quark beam jets dominate inelastic dynamics. Recoil \br from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of $v_n$ in $p(D)+A$ and non-central $A+A$ at same $dN/d\eta$ multiplicity as observed at RHIC and LHC.Comment: 16 pages, 10 figure

Jet Tomography of Au+Au Reactions Including Multi-gluon Fluctuations

Jet tomography is the analysis of the attenuation pattern of high transverse momentum hadrons to determine certain line integral transforms of the density profile of the QCD matter produced in ultra-relativistic nuclear collisions. In this letter, we calculate the distortion of jet tomography due to multi-gluon fluctuations within the GLV radiative energy loss formalism. We find that fluctuations of the average gluon number, ~ 3 for RHIC initial conditions, reduce the attenuation of pions by approximately a factor Z ~ 0.4-0.5. Therefore the plasma density inferred from jet tomography without fluctuations must be enhanced by a factor 1/Z ~ 2.Comment: 6 pages, 4 .eps figures, uses REVTEX and bbox.st

Discovery of Jet Quenching at RHIC and the Opacity of the Produced Gluon Plasma

The predicted quenching of jets in A+A at RHIC energies has been discovered by STAR and PHENIX in preliminary data reported at this conference. We apply the GLV theory of QCD radiative energy loss to estimate the opacity, L/\lambda_g, of the gluon plasma produced in Au+Au collisions at 130 AGeV. We show that (in contrast to the factor of two Cronin enhancement of \pi^0 found at the SPS by WA98) the factor of 5-8 suppression of p_T \sim 2-4 GeV \pi^0 reported by PHENIX can be accounted for with an effective static plasma opacity L/\lambda_g \approx 3-4.Comment: Talk at the conference Quark Matter'2001, 4 pages in Latex, 4 EPS figures, to appear in Nuclear Physics

Jet quenching in relativistic heavy ion collisions

Parton propagation in dense nuclear matter results in elastic, inelastic and coherent multiple soft scattering with the in-medium color charges. Such scattering leads to calculable modifications of the hadron production cross section that is evaluated in the framework of the perturbative QCD factorization approach. Final state medium-induced gluon bremsstrahlung is arguably the most efficient way of suppressing large transverse momentum particle production in nucleus-nucleus collisions. The observed hadronic attenuation, known as jet quenching, can be related to the properties of the medium, such as density and temperature, and carries valuable information about the early stages of heavy ion reactions. Non-Abelian energy loss in the quark-gluon plasma can be studied in much greater detail through the modification of the two particle back-to-back correlations. Perturbative calculations give good description of the redistribution of the lost energy in lower transverse momentum particles and predict significant increase of the correlation width of away-side di-hadrons. In contrast, energy loss in cold nuclear matter was found to be small but for large values of Feynman-x is expected to complement the dynamical higher twist shadowing in experimentally observable forward rapidity hadron suppression.Comment: Invited plenary talk at the V-th international conference on the physics and astrophysics of the quark-gluon plasma. 8 pages, 4 figure

Neutral Pions with Large Transverse Momentum in d+Au and Au+Au Collisions

Measurements of transverse-momentum p_T spectra of neutral pions in Au+Au and d+Au collisions at sqrt{s_NN}=200 GeV and 62.4 GeV by the PHENIX experiment at RHIC in comparison to p+p reference spectra at the same sqrt{s_NN} are presented. In central Au+Au collisions at sqrt{s_NN}=200 GeV a factor 4-5 suppression for neutral pions and charged hadrons with p_T > 5 GeV/c is found relative to the p+p reference scaled by the nuclear overlap function . In contrast, such a suppression of high-p_T particles is absent in d+Au collisions independent of the centrality of the collision. To study the sqrt{s_NN} dependence of the suppression Au+Au collisions at sqrt{s_NN}=200 GeV and 62.4 GeV are compared.Comment: 7 pages, 5 figures, presented at Hot Quarks 2004, Taos, N

Gajenje karaša (Carassius carassius) u ribnjacima

Uzgoj juvenilnih jedinki karaša (C. carassius) analiziran je u pet ribnjačkih objekata veličine 100 m2. Karaš je gajen u monokulturi u dva, dok je sa linjakom gajen u bikulturi u tri ribnjačka jezera. Stopa preživljavanja karaša u monokulturi iznosila je 21.15±6.86 %, a u bikulturi 47.07±16.86%. Kod linjaka je zabeležena veca stopa preživljavanja (69.33±16.76) i brži rast u odnosu na karaša. Iako je prema dobijenim rezultatima teško proceniti razlike između uzgoja u monokulturi i bikulturi, može se zaključiti da linjak nije značajan kompetitor karašu

Pauli equation and the method of supersymmetric factorization

We consider different variants of factorization of a 2x2 matrix Schroedinger/Pauli operator in two spatial dimensions. They allow to relate its spectrum to the sum of spectra of two scalar Schroedinger operators, in a manner similar to one-dimensional Darboux transformations. We consider both the case when such factorization is reduced to the ordinary 2-dimensional SUSY QM quasifactorization and a more general case which involves covariant derivatives. The admissible classes of electromagnetic fields are described and some illustrative examples are given.Comment: 18 pages, Late

Are High-pT Pions Suppressed in Pb+Pb Collisions at sqrt(sNN) = 17.3 GeV?

Transverse momentum spectra of neutral pions in the range 0.7 < pT < 3.2 GeV/c have been measured at 2.3 < eta < 3.0 by the WA98 experiment in p+C and p+Pb collisions at sqrt(sNN) = 17.3 GeV. Scaled by the number of nucleon-nucleon collisions (Ncoll) the pi^0 yields in p+C and p+Pb at pT ~ 2.0 - 2.5 GeV/c are higher than the respective yields in central Pb+Pb collisions with Npart > 300. This observation is qualitatively consistent with expectations from parton energy loss.Comment: 4 pages, 3 figures, To appear in the proceedings of the Quark Matter 2006 conference, Shanghai, China, 14-20 Nov 200