Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userKaon Interferometry: A Sensitive Probe of the QCD Equation of State?
84
0
0.0
(
0
)
Authors
Sven Soff
Ask ChatGPT about the research
No Arabic abstract
We calculate the kaon HBT radius parameters for high energy heavy ion collisions, assuming a first order phase transition from a thermalized Quark-Gluon-Plasma to a gas of hadrons. At high transverse momenta K_T ~ 1 GeV/c direct emission from the phase boundary becomes important, the emission duration signal, i.e., the R_out/R_side ratio, and its sensitivity to T_c (and thus to the latent heat of the phase transition) are enlarged. Moreover, the QGP+hadronic rescattering transport model calculations do not yield unusual large radii (R_i<9fm). Finite momentum resolution effects have a strong impact on the extracted HBT parameters (R_i and lambda) as well as on the ratio R_out/R_side.
rate research
Read More
Different orientations of $alpha$-clustered carbon nuclei colliding with heavy ions can result in a large variation in the value of anisotropic flow. Thus, photon flow observables from clustered ${rm^{12}C}$ and ${rm^{197}Au}$ collisions could be a potential probe to study the `direct photon puzzle. We calculate the transverse momentum spectra and anisotropic flow coefficients ($v_n$) of thermal photons from collisions of triangular $alpha$-clustered carbon and gold at $sqrt{s_{rm NN}}=200$ GeV at RHIC using a hydrodynamic model framework and compare the results with those obtained from unclustered carbon and gold collisions. The slope of the thermal photon spectra is found to vary moderately for different orientations of collisions. However, we find that the elliptic ($v_2$) and triangular flow ($v_3$) coefficients of direct photons for specific configurations are significantly larger and predominantly formed by the QGP radiation. A strong anti-correlation between initial spatial ellipticity and triangularity is observed in an event-by-event framework of $alpha$-clustered ${rm C+Au}$ collisions. These special features provide us an opportunity to detect the exotic nature of cluster structure inside carbon nucleus using the photon probe in the future experiments.
We study the sensitivities of the directed flow in Au+Au collisions on the equation of state (EoS), employing the transport theoretical model JAM. The EoS is modified by introducing a new collision term in order to control the pressure of a system by appropriately selecting an azimuthal angle in two-body collisions according to a given EoS. It is shown that this approach is an efficient method to modify the EoS in a transport model. The beam energy dependence of the directed flow of protons is examined with two different EoS, a first-order phase transition and crossover. It is found that our approach yields quite similar results as hydrodynamical predictions on the beam energy dependence of the directed flow; Transport theory predicts a minimum in the excitation function of the slope of proton directed flow and does indeed yield negative directed flow, if the EoS with a first-order phase transition is employed. Our result strongly suggests that the highest sensitivity for the critical point can be seen in the beam energy range of $4.7leqsrtNNleq11.5$ GeV.
We calculated the QCD equation of state using Taylor expansions that include contributions from up to sixth order in the baryon, strangeness and electric charge chemical potentials. Calculations have been performed with the Highly Improved Staggered Quark action in the temperature range $Tin [135~{rm MeV}, 330~{rm MeV}]$ using up to four different sets of lattice cut-offs corresponding to lattices of size $N_sigma^3times N_tau$ with aspect ratio $N_sigma/N_tau=4$ and $N_tau =6-16$. The strange quark mass is tuned to its physical value and we use two strange to light quark mass ratios $m_s/m_l=20$ and $27$, which in the continuum limit correspond to a pion mass of about $160$ MeV and $140$ MeV espectively. Sixth-order results for Taylor expansion coefficients are used to estimate truncation errors of the fourth-order expansion. We show that truncation errors are small for baryon chemical potentials less then twice the temperature ($mu_Ble 2T$). The fourth-order equation of state thus is suitable for the modeling of dense matter created in heavy ion collisions with center-of-mass energies down to $sqrt{s_{NN}}sim 12$ GeV. We provide a parametrization of basic thermodynamic quantities that can be readily used in hydrodynamic simulation codes. The results on up to sixth order expansion coefficients of bulk thermodynamics are used for the calculation of lines of constant pressure, energy and entropy densities in the $T$-$mu_B$ plane and are compared with the crossover line for the QCD chiral transition as well as with experimental results on freeze-out parameters in heavy ion collisions. These coefficients also provide estimates for the location of a possible critical point. We argue that results on sixth order expansion coefficients disfavor the existence of a critical point in the QCD phase diagram for $mu_B/Tle 2$ and $T/T_c(mu_B=0) > 0.9$.
In this work, we study the production of strange quarkoniums, the $phi(2170)$, also named $Y(2175)$, and the $eta(2225)$, via a kaon induced reaction on a proton target in an effective Lagrangian approach. The total and differential cross sections of the reactions $K^{-}prightarrow phi (2170)Lambda $ and $K^{-}prightarrow eta (2225)Lambda $ are calculated by the Reggeized $t $-channel Born term under an assumption that the $phi(2170)$ and $eta(2225)$ are $Lambdabar{Lambda}$ molecular states. At the center of mass energies of about 4.2 GeV, the total cross section for the $phi(2170)$ production is predicted to be about 1 $mu $b. The numerical results indicate that it is feasible to produce the $phi (2170)$ via kaon beam scattering at the best energy window near 4.2 GeV. The total cross section for the $eta(2225)$ production is smaller than that for the $phi(2170)$ production and it may reach an order of the magnitude of 0.1 $mu$b. The differential cross sections for both reactions at different center of mass energies are also presented. It is found that the Reggeized $t$ channel gives a considerable contribution at forward angles. As the energy increases, the contribution from the $t$-channel almost concentrates at extreme forward angles. From these theoretical predictions, the relevant experimental research is suggested, which could provide important information to clarify the internal structure and production mechanism of these two strange quarkoniums.
We predict that the mean transverse momentum of charged hadrons $langle p_trangle$ rises as a function of the charged-particle multiplicity in ultracentral nucleus-nucleus collisions. We explain that this phenomenon has a simple physical origin and represents an unambiguous prediction of the hydrodynamic framework of heavy-ion collisions. We argue that the relative increase of $langle p_t rangle$ is proportional to the speed of sound squared $c_s^2$ of the quark-gluon plasma. Based on the value of $c_s^2$ from lattice QCD, we expect $langle p_trangle$ to increase by approximately $18$ MeV between 1% and 0.001% centrality in Pb+Pb collisions at $sqrt{s_{rm NN}}=5.02$ TeV.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
