Recent data on the production of $D$ mesons and $Lambda_c^+$ baryons in heavy ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider exhibit a number of striking characteristics such as enhanced yield ratios $D_s^+/D^0$, $Lambda_c^+/D^0$ and their transverse momentum dependences. In this paper, we derive the momentum dependence of open charm mesons and singly charmed baryons produced in ultra-relativistic heavy ion collisions via the equal-velocity quark combination. We present analytic expressions and numerical results of yield ratios and compare them with the experimental data available. We make predictions for other charmed hadrons.
We develop for charmed hadron production in relativistic heavy-ion collisions a comprehensive coalescence model that includes an extensive set of $s$ and $p$-wave hadronic states as well as the strict energy-momentum conservation, which ensures the boost invariance of the coalescence probability and the thermal limit of the produced hadron spectrum. By combining our hadronization scheme with an advanced Langevin-hydrodynamics model that incorporates both elastic and inelastic energy loss of heavy quarks inside the dynamical quark-gluon plasma, we obtain a successful description of the $p_mathrm{T}$-integrated and differential $Lambda_c/D^0$ and $D_s/D^0$ ratios measured at RHIC and the LHC. We find that including the effect of radial flow of the medium is essential for describing the enhanced $Lambda_c/D^0$ ratio observed in relativistic heavy-ion collisions. We also find that the puzzling larger $Lambda_c/D^0$ ratio observed in Au+Au collisions at RHIC than in Pb+Pb collisions at the LHC is due to the interplay between the effects of the QGP radial flow and the charm quark transverse momentum spectrum at hadronization. Our study further suggests that charmed hadrons have larger sizes in medium than in vacuum.
Hadron spectroscopy provides direct physical measurements that shed light on the non-perturbative behavior of quantum chromodynamics (QCD). In particular, various exotic hadrons such as the newly observed $T_{cc}^+$ by the LHCb collaboration, offer unique insights on the QCD dynamics in hadron structures. In this letter, we demonstrate how heavy ion collisions can serve as a powerful venue for hadron spectroscopy study of doubly charmed exotic hadrons by virtue of the extremely charm-rich environment created in such collisions. The yields of $T_{cc}^+$ as well as its potential isospin partners are computed within the molecular picture for Pb-Pb collisions at center-of-mass energy $2.76~mathrm{TeV}$. We find about three-order-of-magnitude enhancement in the production of $T_{cc}^+$ in Pb-Pb collisions as compared with the yield in proton-proton collisions, with a moderately smaller enhancement in the yields of the isospin partners $T_{cc}^0$ and $T_{cc}^{++}$. The $T_{cc}^+$ yield is comparable to that of the $X(3872)$ in the most central collisions while shows a considerably stronger decrease toward peripheral collisions, due to a threshold effect of the required double charm quarks for $T_{cc}^+$. Final results for their rapidity and transverse momentum $p_T$ dependence as well as the elliptic flow coefficient are reported and can be tested by future experimental measurements.
We describe the quark gluon plasma (QGP) as a thermalized quark-gluon system, the thermalized QGP phase of QCD. The hadronization of the thermalized QGP phase is given in a way resembling a coalescence model with correlated quarks and anti-quarks. The input parameters of the approach are the spatial volumes of the hadronization. We introduce three dimensionless parameters C_M, C_B and C_bar{B} related to the spatial volumes of the production of low-lying mesons (M), baryons (B) and antibaryons (bar{B}). We show that at the temperature T= 175 MeV our predictions for the ratios of multiplicities agree good with the presently available set of hadron ratios measured for various experiments given by NA44, NA49, NA50 and WA97 Collaborations on Pb+Pb collisions at 158 GeV/nucleon, NA35 Collaboration on S+S collisions and NA38 Collaboration on O+U and S+U collisions at 200 GeV/nucleon.
A novel, unorthodox picture of the dynamics of heavy ion collisions is developed using the concept of Hagedorn states. A prescription of the bootstrap of Hagedorn states respecting the conserved quantum numbers baryon number B, strangeness S, isospin I is implememted into the GiBUU transport model. Using a strangeness saturation suppression factor suitable for nucleon-nucleon-collisions, recent experimental data for the strangeness production by the HADES collaboration in Au+Au and Ar+KCl is reasonable well described. The experimental observed exponential slopes of the energy distributions are nicely reproduced. Thus, a dynamical model using Hagedorn resonance states, supplemented by a strangeness saturation suppression factor, is able to explain essential features (multiplicities, exponential slope) of experimental data for strangeness production in nucleus-nucleus collisions close to threshold.
Recently the HAL QCD Collaboration reported the $Omega-Omega$ and $N-Omega$ interaction potentials by the lattice QCD simulations. Based on these results, $NOmega$ ($^5S_2$) and $OmegaOmega$ ($^1S_0$) bound states were predicted with the binding energy about a few MeV. In addition, $N-Omega$ HBT correlation function was also measured by the STAR Collaboration as well as the ALICE Collaboration. These results provide dynamical information whether or not $Omega$-dibaryons exist in the interaction aspects. Another necessary point for the detection of $Omega$-dibaryons is the experimental environment where the bound state could be produced and survived in the system. In this context, there are at least two necessary conditions to constrain the production probability of $Omega$-dibaryons, i.e. the one is the necessary short-range attractive interaction to form the bound state and the another is the experimental environment such as heavy-ion collision provides abundant enough strangeness and multiplicity of nucleons. In this Letter the $Omega-Omega$ and $Omega-$nucleon interaction potentials by the lattice QCD simulations were employed to obtain $OmegaOmega$ ($^1S_0$) and $NOmega$ ($^5S_2$) wave functions, and then the productions of $Omega$-dibaryons were estimated by using of a dynamical coalescence mechanism for the relativistic heavy-ion collisions at $sqrt{s_{NN}} = $ 200 GeV and 2.76 TeV.
Rui-Qin Wang
,Jun Song
,Feng-Lan Shao
.
(2019)
.
"Charmed hadron production via equal-velocity quark combination in ultra-relativistic heavy ion collisions"
.
Ruiqin Wang
هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا