119296933
Probing the XYZ states through radiative decays
In this work, we have adopted the spin rearrangement scheme in the heavy quark limit and extensively investigated three classes of the radiative decays: $\mathfrak{M}\to (b\bar{b})+\gamma$, $(b\bar{b})\to \mathfrak{M}+\gamma$, $ \mathfrak{M} \to \mathfrak{M}^\prime+\gamma$, corresponding to the electromagnetic transitions between one molecular state and bottomonium, one bottomonium and molecular state, and two molecular states respectively. We also extend the same formalism to study the radiative decays of the molecular states with hidden charm. We have derived some model independent ratios when the initial or final states belong to the same spin flavor multiplet. Future experimental measurement of these ratios will test the molecular picture and explore the underlying structures of the $XYZ$ states.
13990506
Dynamics study of Z+(4430) and X(3872) in molecular picture
In this talk, we review our recent work about the dynamical studies of Z+(4430) and X(3872). Z+(4430) can not be explained as a D1′D* or D1D* molecular state only considering one pion exchange potential without the cutoff, which needs to be confirmed by introducing sigma exchange potential and adding the cutoff in the effective potential. One also excludes the possibility of X(3872) as a DD* molecular state by one pion and one sigma exchanges with the cutoff. Fortunately there exists an S‐wave BB* bound state with JPC = 1++. we suggest future experiment to search this state.
119191221
Modified DGLAP evolution for fragmentation functions in nuclei and QGP
Abstract Within the framework of generalized factorization of higher-twist contributions, including modification to splitting functions of both quark and gluon, we get and numerically resolve the medium-modified DGLAP (mDGLAP) evolution equations. With Woods-Saxon nuclear geometry and Hirano 3D ideal hydrodynamic simulations of hot medium, we study the medium modified fragmentation functions (mFF) in DIS and Au+Au collisions in RHIC. Our calculations imply that the parton density in the hot medium produced in RHIC is about 30 times larger than in a cold nucleus.
119244375
Elliptic and Triangular Flow and their Correlation in Ultrarelativistic High Multiplicity Proton Proton Collisions at 14 TeV
Abstract The spatial configuration of initial partons in high multiplicity proton–proton scatterings at 14 TeV is assumed as three randomly positioned “hot spots”. The parton momentum distribution in the hot spots is calculated by HIJING2.0 with some modifications. This initial condition causes not only large eccentricity ϵ 2 but also triangularity ϵ 3 and the correlation of ϵ 2 − ϵ 3 event-plane angles. The final elliptic flow v 2 , triangular flow v 3 , and the correlation of v 2 − v 3 event-plane angles are calculated by using the parton cascade model BAMPS to simulate the space–time parton evolution. Our results show that the v 2 − v 3 correlation is different from that of ϵ 2 − ϵ 3 . This finding indicates that translations of different Fourier components of the initial spatial asymmetry to the final flow components are not independent. A dynamical correlation between the elliptic and triangular flow appears during the collective expansion.
119298308
Suppression of high $p_T$ hadron spectra in $p+A$ collisions
Abstract Multiple hard and semi-hard parton scatterings in high-energy p + A collisions involve multi-parton correlation inside the projectile in both momentum and flavor which will lead to modification of the final hadron spectra relative to that in p + p collisions. Such modification of the final hadron transverse momentum spectra in p + A collisions is studied within HIJING 2.1 Monte Carlo model which includes nuclear shadowing of the initial parton distributions and transverse momentum broadening. Multi-parton flavor and momentum correlation inside the projectile are incorporated through flavor and momentum conservation which are shown to modify the flavor content and momentum spectra of final partons and most importantly lead to suppression of large p T hadron spectra in p + A collisions at both RHIC and LHC energies.
3066888
Global quark polarization in non-central A+A collisions
Partons produced in the early stage of non-central heavy-ion collisionscan develop a longitudinal fluid shear because of unequal local number densities of participant target and projectile nucleons. Under such fluid shear, local parton pairs with non-vanishing impact parameter have finite local relative orbital angular momentum along the direction opposite to the reaction plane. Such finite relative orbitalangular momentum among locally interacting quark pairs can lead to global quark polarization along the same direction due to spin-orbital coupling. Local longitudinal fluid shear is estimated within both Landau fireball and Bjorken scaling model of initial parton production. Quark polarization through quark-quark scatterings with the exchange of a thermal gluon is calculated beyond small-angle scattering approximation in a quark-gluon plasma. The polarization is shown to have a non-monotonic dependence on the local relative orbital angular momentum dictated by the interplay between electric and magnetic interaction. It peaks at a value of relative orbital angular momentum which scales with the magnetic mass of the exchanged gluons. With the estimated small longitudinal fluid shear in semi-peripheral Au+Au collisions at the RHIC energy, the final quark polarization is found to be small left hbar P_q right hbar <0.04 in the weak coupling limit. Possible behavior of the quark polarization in the strong coupling limit and implications on the experimental detection of such global quark polarization at RHIC and LHC are also discussed.
76655214
Hadron production in p+p, p+Pb, and Pb+Pb collisions with the HIJING 2.0 model at energies available at the CERN Large Hadron Collider
The Heavy-Ion Jet Interaction Generator (hijing) Monte Carlo model is updated with the latest parton distributions functions and a new set of the parameters in the two-component minijet model that controls the total p+p cross section and the central pseudorapity density. We study hadron spectra and multiplicity distributions using the hijing2.0 model and compare to recent experimental data from p+p collisions at the Large Hadron Collider (LHC) energies. We also give predictions of hadron production in p+p, p+Pb, and Pb+Pb collisions at the full LHC energy.