0000000000035852
AUTHOR
Rupa Chatterjee
showing 12 related works from this author
Thermal photon v3 at LHC from fluctuating initial conditions
2014
Abstract We calculate the triangular flow parameter v 3 of thermal photons for 0–40% central collisions of Pb nuclei at LHC using an event-by-event hydrodynamic model with fluctuating initial conditions. Thermal photon v 3 with respect to the participant plane angle is found to be positive and significant compared to the elliptic flow parameter v 2 of thermal photons. In addition, photon v 3 as a function of p T shows similar qualitative nature to photon v 2 in the region 1 p T 6 GeV / c . We argue that while v 3 originates from ϵ 3 deformations of the initial state density distribution, fast buildup of radial flow due to fluctuations is the main driving mechanism for the observed large val…
Equation of state of strongly interacting matter: spectra for thermal particles and intensity correlation of thermal photons
2010
We find that an equation of state for hot hadronic matter consisting of all baryons having $M < 2$ GeV and all mesons having $M < 1.5$ GeV, along with Hagedorn resonances in thermal and chemical equilibrium, matches rather smoothly with lattice equation of state (p4 action, ${N_��}=8$) for T up to $\approx 200$ MeV, when corrected for the finite volume of hadrons. Next we construct two equations of state for strongly interacting matter; one, HHL, in which the above is matched to the lattice equation of state at $T=165$ MeV and the other, HHB, where we match it to a bag model equation of state with critical temperature $T_c=165$ MeV. We compare particle spectra, thermal photon spectra …
Beam Energy Scan of Specific Heat Through Temperature Fluctuations in Heavy Ion Collisions
2016
Temperature fluctuations may have two distinct origins, first, quantum fluctuations that are initial state fluctuations, and second, thermodynamical fluctuations. We discuss a method of extracting the thermodynamic temperature from the mean transverse momentum of pions, by using controllable parameters such as centrality of the system, and range of the transverse momenta. Event-by-event fluctuations in global temperature over a large phase space provide the specific heat of the system. We present Beam Energy Scan of specific heat from data, AMPT and HRG model prediction. Experimental results from NA49, STAR, PHENIX, PHOBOS and ALICE are combined to obtain the specific heat as a function of …
Equation of state of strongly interacting matter and intensity interferometry of thermal photons
2011
Abstract We find that an equation of state (EOS) for hot hadronic matter consisting of all mesons (baryons) having M 1.5 ( 2.0 ) GeV along with Hagedorn resonances in thermal and chemical equilibrium, matches rather smoothly with lattice EOS ( p 4 action, N τ = 8 ) for T up to ≈200 MeV, when corrections are made for the finite volume of hadrons. Two equations of state, HHL and HHB are constructed where the above is matched to the lattice and bag model EoS respectively at a critical temperature T c = 165 MeV . We find that the particle and thermal photon spectra differ only marginally for the two equations of state at both RHIC and LHC energies. The intensity interferometry results, speciall…
Centrality and initial formation time dependence of the emission of thermal photons from fluctuating initial conditions at RHIC and LHC
2013
Abstract Event-by-event fluctuating initial conditions (IC) in the ideal hydrodynamic calculation are known to enhance the production of thermal photons significantly compared to a smooth initial state averaged profile in the range p T > 1 GeV / c for 200A GeV Au+Au collisions at RHIC and 2.76A TeV Pb + Pb collisions at LHC. The ‘hotspots’ or the over-dense regions in the fluctuating IC produce more high p T photons compared to the smooth IC due to the strong temperature dependent emission of the thermal radiation. This enhancement is expected to be more pronounced for peripheral collisions, for lower beam energies, and for larger values of plasma formation time. A suitably normalized ratio…
Collision centrality andτ0dependence of the emission of thermal photons from a fluctuating initial state in an ideal hydrodynamic calculation
2012
Fluctuations in the initial QCD matter density distribution are found to enhance the production of thermal photons significantly in the range $2\ensuremath{\leqslant}{p}_{T}\ensuremath{\leqslant}4$ GeV/$c$ compared to a smooth initial state averaged profile in ideal hydrodynamic calculation for $200A$ GeV Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and $2.76A$ TeV Pb+Pb collisions at the Large Hadron Collider (LHC). The thermal emission of photons is strongly dependent on the initial temperature of the system where the presence of ``hot spots'' in the initial state translates into enhanced production of photons compared to a smooth profile. The effect of fluctuations in t…
Triangular flow of thermal photons from an event-by-event hydrodynamic model for2.76ATeV Pb + Pb collisions at the CERN Large Hadron Collider
2016
We calculate the triangular flow parameter $v_3$ of thermal photons from an event-by-event ideal hydrodynamic model for $0--40\%$ central collisions of Pb nuclei at $\sqrt{s_{NN}}$=2.76 TeV at LHC. $v_3$ determined with respect to the participant plane (PP) is found to be non-zero, positive and its $p_T$ dependence is qualitatively similar to the elliptic flow parameter $v_2$(PP) of thermal photons in the range $1 \le p_T \le 6$ GeV/$c$. In the range $p_T \, \le $ 3 GeV/$c$, $v_3$(PP) is found to be about $50--75\%$ of $v_2$(PP) and for $p_T \, >$ 3 GeV/$c$ the two anisotropy parameters become comparable. The local fluctuations in the initial density distribution as well as the initial glob…
Enhancement of thermal photon production in event-by-event hydrodynamics
2011
Thermal photon emission is widely believed to reflect properties of the earliest, hottest evolution stage of the medium created in ultra-relativistic heavy-ion collisions. Previous computations of photon emission have been carried out using a hydrodynamical medium description with smooth, averaged initial conditions. Recently, more sophisticated hydrodynamical models which calculate observables by averaging over many evolutions with event-by-event fluctuating initial conditions (IC) have been developed. Given their direct connection to the early time dynamics, thermal photon emission appears an ideal observable to probe fluctuations in the medium initial state. In this work, we demonstrate …
Thermal photons from fluctuating initial conditions
2011
Event-by-event fluctuations of initial QCD-matter density produced in heavy-ion collisions at RHIC enhance the production of thermal photons significantly in the region $2 \le p_T \le 4$ GeV/$c$ compared to a smooth initial-state averaged profile in the ideal hydrodynamic calculation. This enhancement is a an early time effect due to the presence of hotspots or over-dense regions in the fluctuating initial state. The effect of fluctuations is found to be stronger in peripheral than in central collisions.
Influence of initial state fluctuations on the production of thermal photons
2012
Inhomogeneities in the initial QCD matter density distribution increase the production of thermal photons significantly compared to a smooth initial-state-averaged profile in the region $p_T > 1$ GeV/$c$ in an ideal hydrodynamic calculation. This relative enhancement is more pronounced for peripheral collisions, for smaller size systems as well as for lower beam energies. A suitably normalized ratio of central-to-peripheral yield of thermal photons reduce the uncertainties in the hydrodynamical initial conditions and can be a useful parameter to study the density fluctuations and their size. The fluctuations in the initial density distribution also lead to a larger elliptic flow of therm…
Zeroing in on the initial state — tomography using bulk, jets and photons
2014
One of the unsolved problems in the current 'standard model' of heavy ion physics is the apparent rapid thermalization of QCD matter in the pre-equilibrium stage. While it is challenging to probe this mechanism directly, there are now several observables available which allow tomographic imaging of the initial state geometry, which is expected to carry remnant information of the equilibration mechanism. On the fluid dynamics side, scaled fluctuations in the momentum space anisotropy parameters v_n image the initial eccentricity fluctuations epsilon_n almost directly with only a weak dependence on the details of the fluid dynamical evolution. From a different direction, due to the strong non…
Triangular flow of thermal photons from an event-by-event hydrodynamic model for 2.76A TeV Pb + Pb collisions at the CERN Large Hadron Collider
2016
We calculate the triangular flow parameter v3 of thermal photons from an event-by-event ideal hydrodynamic model for 0–40% central collisions of Pb nuclei at √sNN = 2.76 TeV at the CERN Large Hadron Collider. v3 determined with respect to the participant plane (PP) is found to be nonzero and positive, and its pT dependence is qualitatively similar to the elliptic flow parameter v2(PP) of thermal photons in the range 1 pT 6 GeV/c. In the range pT 3 GeV/c, v3(PP) is found to be about 50–75% of v2(PP) and for pT > 3 GeV/c the two anisotropy parameters become comparable. The value of v3 is driven by local density fluctuations both directly via the creation of triangular geometry and indirectly …