35946336
Minijet scale and energy loss at relativistic energies in event generator models
Author(s): Pop, V. Topor; Gyulassy, M.; Barrette, J.; Gale, C.; Wang, X.N.; Xu, N.; Filimonov, K.
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.
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.
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.
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.
119949182
Systematic study for grey particles in relativistic nucleus + emulsion (Ag) interactions
The hadronic and string cascade model and the corresponding event generator LUCIAE are used to study systematically the production of the grey particles in (14.6, 60 and 200A GeV)0 + Em, (2004 GeV)Si + Em, (200A GeV)S + Em and (11.6A GeV)Au + Em reactions. The dependences of the mean multiplicity, the multiplicity distributions and the polar angular distributions of the grey particles on the incident energy, the projectile mass and the collision centrality observed in emulsion experiments, respectively, are all reproduced by LUCIAE calculations. In addition the effects of the rescattering on the grey particle production are also investigated.
5502533
A trick to improve the efficiency of generating unweighted Bc events from BCVEGPY
In the present paper, we provide an addendum to improve the efficiency of generating unweighted events within PYTHIA environment for the generator BCVEGPY2.1 [C.H. Chang, J.X. Wang, X.G. Wu, Comput. Phys. Commun. 174 (2006) 241]. This trick is helpful for experimental simulation. Moreover, the BCVEGPY output has also been improved, i.e. one Les Houches Event common block has been added so as to generate a standard Les Houches Event file that contains the information of the generated Bc meson and the accompanying partons, which can be more conveniently used for further simulation.
119185233
Study on the temperature dependence of BGO light yield
The temperature dependence of BGO coupled with photomultiplier tube R5610A-01 was studied in the range of −30–30°C. The temperature coefficient of the BGO and R5610A as a whole was tested to be −1.82%/°C. And the temperature coefficient of the gain of the R5610A is −0.44%/°C which was tested in the same situation using a blue LED. Thus the temperature coefficient of BGO’s light yield can be evaluated as −1.38%/°C.
198138925
Oscillations of moments in high-energy nucleus-nucleus collisions
The definitions of density function and moment of multiplicity distribution are introduced, and the method of moment analysis in e+e- and proton-proton (pp) interactions is extended into nucleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and calculate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hqon incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e+ e-, pp and AA interactions, and the comparison and analysis are carried out between experimental data and QCD prediction. The latest results are given in this paper.
118555345
Alternate proof of the Rowe-Rosensteel proposition and seniority conservation
In this thesis the properties of unbound nuclei like 12,13Li are studiedby extending the multistep shell model to the complex energy plane. Thenuclei 12Li and 13Li are described starting from the one-particle states in 10Liand two-particle states in 11Li. The ground state of 12Li is found to be anantibound state. No bound or antibound state is found in 13Li. It is alsoshown that the odd proton plays a minor role in these nuclei.This framework is also applied to study the recently proposed spin-alignedproton-neutron pair coupling scheme. For this the MSM is extended to theproton-neutron space as well as the isospin space. In the model, a nonorthogonalbasis is introduced, which allows us to identify simultaneously theroles played by all configurations. The four-particle, six-particle and eightparticlenuclei in the heaviest N = Z region are evaluated using the MSMbasis within the space spanned by the single 0g9/2 hole shell.A novel Monte Carlo representation in the complex energy plane is alsodeveloped for studying nuclear excitations in the continuum. The calculationson realistic potentials show a stable performance and high accuracy in the oneparticleand two-particle cases. This will provide a convenient tool to studyopen systems with many nucleons in the continuum.