In this work, we study electrical conductivity and Hall conductivity in the presence of electromagnetic field using Relativistic Boltzmann Transport Equation with Relaxation Time Approximation. We evaluate these transport coefficients for a strongly interacting system consisting of nearly massless particles which is similar to Quark-Gluon Plasma and is likely to be formed in heavy-ion collision experiments. We explicitly include the effects of magnetic field in the calculation of relaxation time. The values of magnetic field are obtained for all the centrality classes of Au+Au collisions at $sqrt {s_{rm NN}} =$ 200 GeV and Pb+Pb collisions at $sqrt {s_{rm NN}} =$ 2.76 TeV. We consider the three lightest quark flavors and their corresponding antiparticles in this study. We estimate the temperature dependence of the electrical conductivity and Hall conductivity for different strengths of magnetic field. We observe a significant dependence of temperature on electrical and Hall conductivity in the presence of magnetic field.
The experimental data from the RHIC and LHC experiments of invariant pT spectra in A+A and p + p collisions are analysed with Tsallis distributions in different approaches. The information about the freeze-out surface in terms of freeze-out volume, temperature, chemical potential and radial flow velocity for different particle species are obtained. Further, these parameters are studied as a function of the mass of the secondary particles. A mass-dependent differential freeze-out is observed which does not seem to distinguish between particles and their antiparticles. Further a mass-hierarchy in the radial flow is observed, meaning heavier particles suffer lower radial flow. Tsallis distribution function at finite chemical potential is used to study the mass dependence of chemical potential. The peripheral heavy-ion and proton-proton collisions at the same energies seem to be equivalent in terms of the extracted thermodynamic parameters.
Recently, transport coefficients viz. shear viscosity, electrical conductivity etc. of strongly interacting matter produced in heavy-ion collisions have drawn considerable interest. We study the normalised electrical conductivity ($sigma_{rm el}$/T) of hot QCD matter as a function of temperature (T) using the Color String Percolation Model (CSPM). We also study the temperature dependence of shear viscosity and its ratio with electrical conductivity for the QCD matter. We compare CSPM estimations with various existing results and lattice Quantum Chromodynamics (lQCD) predictions with (2+1) dynamical flavours. We find that $sigma_{rm el}$/T in CSPM has a very weak dependence on the temperature. We compare CSPM results with those obtained in Boltzmann Approach to Multi-Parton Scatterings (BAMPS) model. A good agreement is found between CSPM results and predictions of BAMPS with fixed strong coupling constant.
We present the mini-proceedings of the workshop on ``Photoproduction at collider energies: from RHIC and HERA to the LHC held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) from January 15 to 19, 2007. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of high-energy photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) small-$x$ QCD in photoproduction studies with protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus collisions, (ii) hard diffraction physics at hadron colliders, and (iii) photon-photon collisions at very high energies: electroweak and beyond the Standard Model processes. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.
The ratio of nuclear modification factors of high-$p_T$ heavy-flavored mesons tolight-flavored hadrons (heavy-to-light ratio) is shown to be a sensitive tool to test medium-induced energy loss at RHIC and LHC energies. Heavy-to-light ratios of $D$ mesons at RHIC in the region $7<p_T<12$ GeV, and of $D$ and $B$ mesons at the LHC in the region $10<p_T<20$ GeV, are proposed for such a test. Finally, the different contributions to the nuclear modification factor for electrons at RHIC are analyzed. Preliminary PHENIX and STAR data are compatible with radiative energy loss provided the contribution of electrons from beauty decays is small compared to that from charm.
A study of the charged-particle density (number density) in the transverse region of the di-hadron correlations exploiting the existing pp and p$bar{rm p}$ data from RHIC to LHC energies is reported. This region has contributions from the Underlying Event (UE) as well as from Initial- and Final-State Radiation (ISR-FSR). Based on the data, a two-component model is built. This has the functional form $propto s^{0.27}+0.14log(s)$, where the logarithmic (power-law) term describes the component more sensitive to the ISR-FSR (UE) contribution. The model describes the data from RHIC to LHC energies, the extrapolation to higher energies indicates that at around $sqrt{s} approx 100$ TeV the number density associated to UE will match that from ISR-FSR. Although this behaviour is not predicted by PYTHIA~8.244, the power-law behaviour of the UE contribution is consistent with the energy dependence of the parameter that regulates Multiparton Interactions. Using simulations, KNO-like scaling properties of the multiplicity distributions in the regions sensitive to either UE or ISR-FSR are also discussed. The results presented here can be helpful to constrain QCD-inspired Monte Carlo models at the Future Circular Collider energies, as well as to characterize the UE-based event classifiers which are currently used at the LHC.
Bhaswar Chatterjee
,Rutuparna Rath
,Golam Sarwar
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(2019)
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"Centrality dependence of Electrical and Hall conductivity at RHIC and LHC energies for a Conformal System"
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Raghunath Sahoo
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