Speaker
Tapan Nayak
(Department of Atomic Energy (IN))
Description
Experiments at RHIC and LHC are on the quest to unearth the nature of
the QCD phase transition and to get a glimpse of how matter behaves at
such extreme conditions. Phase transitions are governed by a set of
thermodynamic parameters, like, temperature ($T$), pressure, entropy,
and energy density ($E$), and can be further characterized by their
response functions, like, specific heat,
compressibility, and susceptibility. In thermodynamics, the heat
capacity ($C$) is defined in terms of the ratio of the event-by-event
fluctuations of the energy of a part of a finite system in thermal
equilibrium to the energy ${(\Delta E^2)} = {T^2}C(T)$. This can be
applied for a locally thermalized system produced during the evolution
of heavy-ion collisions. But for a system at freeze-out, specific heat
can expressed in terms of the event-by-event fluctuations in temperature
of the system where volume is fixed: $ \frac{1}{C} = \frac{(\langle T^2
\rangle - \langle T \rangle ^2 )}{\langle T \rangle ^2}$. We define the
specific heat as the heat capacity per pion multiplicity within the experimentally available phase space in rapidity
and azimuth. For a system in equilibrium, the mean values of temperature
and energy density are related by an equation of state. However, the
fluctuations in energy and temperature have quite different behavior.
Energy being an extensive quantity, its fluctuations have a component
arising from the volume fluctuations, and not directly suited for
obtaining the heat capacity.
Here, we obtain the specific heat for heavy-ion
collisions at SPS, RHIC beam energy scan energies and for LHC energy.
Experimental results from NA49, STAR, PHENIX, PHOBOS and ALICE are
combined to obtain the specific heat as a function of beam energy. The
results are compared to results from AMPT event generator, HRG model and
lattice calculations. We also present local hot spot search at LHC
energy for better understanding the collision dynamics.
| On behalf of collaboration: | NONE |
|---|
Primary author
Mr
Sumit BASU
(VECC, Department of Atomic Energy (IN))
Co-authors
Prof.
Basanta K NANDI
(IIT- Indian Institute of Technology (IN))
Dr
Rupa CHATTERJEE
(Variable Energy Cyclotron Centre)
Dr
Sandeep CHATTERJEE
(Variable Energy Cyclotron Centre)
Tapan Nayak
(Department of Atomic Energy (IN))
