55824325
Spin alignment of vector mesons in non-central A+A collisions
We discuss the consequence of global polarization of the produced quarks in non-central heavy-ion collisions on the spin alignment of vector mesons. We show that the alignment is quite different for different hadronization scenarios. These results can be tested directly by measuring the vector mesons' alignment through angular distributions of the decay products with respect to the reaction plane. Such angular distributions will give rise to azimuthal anisotropy v{sub 2} of the decay products in the collision frame. Constraints provided by the data on the azimuthal anisotropy of hadron spectra at RHIC points to a quark recombination scenario of hadronization.
126140598
Report of the RHIC Workshop p + A subgroup
33523602
Role of multiple minijets in high-energy hadronic reactions.
The multiplicity distributions of charged particles in high-energy hadron collisions including the production of multiple minijets are considered in the framework of the eikonal formalism. Large-multiplicity events at high energies are found to be dominated by the production of many jets with 2{le}{ital P}{sub {ital T}}{le}4 GeV. The contributions from larger-{ital P}{sub {ital T}} minijets become prevailing for high-multiplicity fluctuations in narrow rapidity intervals.
17734649
Probe initial parton density and formation time via jet quenching
Medium modification of jet fragmentation function due to multiple scattering and induced gluon radiation leads directly to jet quenching or suppression of leading particle distribution from jet fragmentation. One can extract an effective total parton energy loss which can be related to the total transverse momentum broadening. For an expanding medium, both are shown to be sensitive to the initial parton density and formation time. Therefore, one can extract the initial parton density and formation time from simultaneous measurements of parton energy loss and transverse momentum broadening. Implication of the recent experimental data on effects of detailed balance in parton energy loss is also discussed.
42468399
Berry curvature and four-dimensional monopoles in the relativistic chiral kinetic equation.
We derive a relativistic chiral kinetic equation with manifest Lorentz covariance from Wigner functions of spin-1/2 massless fermions in a constant background electromagnetic field. It contains vorticity terms and a four-dimensional Euclidean Berry monopole which gives an axial anomaly. By integrating out the zeroth component of the 4-momentum p, we reproduce the previous three-dimensional results derived from the Hamiltonian approach, together with the newly derived vorticity terms. The phase space continuity equation has an anomalous source term proportional to the product of electric and magnetic fields (FσρF[over ˜]σρ∼EσBσ). This provides a unified interpretation of the chiral magnetic and vortical effects, chiral anomaly, Berry curvature, and the Berry monopole in the framework of Wigner functions.
119298211
Relics of Minijets amid Anisotropic Flows in High-energy Heavy-ion Collisions
Two dimensional low-$p_T$ dihadron correlations in azimuthal angle $\phi$ and pseudo-rapidity $\eta$ in high-energy heavy-ion collisions are investigated within both the HIJING Monte Carlo model and an event-by-event (3+1)D ideal hydrodynamic model. Without final-state interaction and collective expansion, dihadron correlations from HIJING simulations have a typical structure from minijets that contains a near-side two-dimensional peak and an away-side ridge along the $\eta$-direction. In contrast, event-by-event (3+1)D ideal hydrodynamic simulations with fluctuating initial conditions from the HIJING+AMPT model produce a strong dihadron correlation that has an away-side as well as a near-side ridge. Relics of intrinsic dihadron correlation from minijets in the initial conditions still remain as superimposed on the two ridges. By varying initial conditions from HIJING+AMPT, we study effects of minijets, non-vanishing initial flow and longitudinal fluctuation on the final state dihadron correlations. With a large rapidity gap, one can exclude near-side correlations from minijet relics and dihadron correlations can be described by the superposition of harmonic flows up to the 6th order. When long-range correlations with a large rapidity gap are subtracted from short-range correlations with a small rapidity gap, the remaining near-side dihadron correlations result solely from relics of minijets. Low transverse momentum hadron yields per trigger ($p_T^{\rm trig} <4$ GeV/$c$, $p_T^{\rm asso}<2$ GeV/$c$) in central heavy-ion collisions are significantly enhanced over that in p+p collisions while widths in azimuthal angle remain the same, in qualitative agreement with experimental data.
37119712
Heavy Flavor Production at PHENIX at RHIC
A study of heavy flavor production in different collision systems in various kinematic regions presents an opportunity to probe cold nuclear medium and hot dense matter effects. Results from the PHENIX experiment on J/ψ and open charm production in Au+Au and Cu+Cu collisions at sNN =200 GeV are presented. The data show strong J/ψ suppression in central AA collisions, similar to NA50 results, and strong suppression in high pT open charm production. The J/ψ production in Au+Au and d+Au collisions is compared to understand the cold nuclear medium effects. The data show significant cold nuclear effects in charm production in d+Au collisions at forward and backward rapidity ranges.
120048813
A criterion for the order of QGP phase transition
Based on the extended Ginzburg-Landau model, it is shown that the dependences of the scaled factorial moments ln Fq on phase space intervals are different for first- and second-order QGP phase transitions. When ln Fq are fitted to polynomials of X ≡ δ13, the relative sign between the fitted coefficients can be used to judge the order of phase transitions.
125595029
Measurement of transverse single-spin asymmetries for J/psi production in polarized p + p collisions at s**(1/2) = 200-GeV
122344772
Residual Interactions and Tilted Rotation in Odd-Odd 164Tm
High-spin spectroscopy on odd-odd {sup 164}Tm has produced new illustrations of departures from the predictions of principal-axis cranking. Among the nine strongly coupled rotational bands observed, four are assigned to the parallel and antiparallel couplings of two configurations {pi}h{sub 11/2}{nu}i{sub 13/2} and {pi}g{sub 9/2}{nu}i{sub 13/2}. This represents the first time that the high-spin properties of both couplings can be explored. We find that the measured B(M1)/B(E2) values in the K=1({up_arrow}{down_arrow}) coupling of {pi}h{sub 11/2}{nu}i{sub 13/2} are 50{percent} larger than those in the K=6 ({up_arrow}{up_arrow}) coupling, and represent the largest seen in this nucleus. Tilted-axis cranking calculations successfully explain the M1/E2 ratios in these two bands, while the particle-rotor calculations did not reproduce the full low-{ital K} enhancement. No inversion in the signatures of the K=6{pi}h{sub 11/2}{nu}i{sub 13/2} band is observed, but there is a small inversion in the K=1 coupling up to I=17{h_bar} and a large inversion in the {pi}h{sub 9/2}{nu}i{sub 13/2} band up to I=19{h_bar}. Remarkably, particle-rotor calculations with a p-n interaction included are able to reproduce these inversions. A stronger p-n interaction is needed to explain an inversion in the {pi}d{sub 3/2}{nu}i{sub 13/2} band. {copyright} {ital 1999} {ital The American Physical Society}
120209602
Longitudinal Double Spin Asymmetries in Heavy Flavor Production in Polarized p+p Collisions at s = 200 GeV
One of the main goals of the RHIC spin program is to determine the contribution of gluons to the proton spin. At RHIC energies, heavy quark (charm and beauty) production is expected to be dominated by gluon‐gluon interactions, so a measurement of the double longitudinal spin asymmetry ALL in heavy quark production in polarized p+p collisions directly probes the polarized gluon distribution inside the proton. We present the latest results on an ALL measurement for J/Ψ and open charm production measured by the PHENIX detector.