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Stanislaw Mrowczynski

Publications and source records attributed to Stanislaw Mrowczynski.

At least 55 records · Page 3Linked to original sources
arXiv2013

Parton Energy Loss in the Extremely Prolate Quark-Gluon Plasma

The energy loss per unit path length of a highly energetic parton scattering elastically in a weakly coupled quark-gluon plasma is studied as an initial value problem. The approach is designed to study unstable plasmas but in the case of an equilibrium plasma the well known result is reproduced. As an example of an unstable system, an extremely prolate plasma, where the momentum distribution is infinitely elongated along one direction, is considered here. The energy loss is shown to be strongly time and directionally dependent and its magnitude can much exceed the energy loss in equilibrium plasma.

hep-ph↗
arXiv2013

Wigner functional of fermionic fields

The Wigner function, which provides a phase-space description of quantum systems, has various applications in quantum mechanics, quantum kinetic theory, quantum optics, radiation transport and others. The concept of Wigner function has been extended to quantum fields, scalar and electromagnetic. Then, one deals with the Wigner functional which gives a distribution of field and its conjugate momentum. We introduce here the Wigner functional of fermionic fields of the values in a Grassmann algebra. Properties of the functional are discussed and its equation of motion, which is of the Liouville's form, is derived.

hep-th↗
arXiv2011

Parton Energy Loss in an Unstable Quark-Gluon Plasma

The energy loss of a fast parton scattering elastically in a weakly coupled quark-gluon plasma is formulated as an initial value problem. The approach is designed to study an unstable plasma, but it reproduces the well known result in the case of an equilibrium plasma. Contributions to the energy loss due to unstable modes are shown to exponentially grow in time. An unstable two-stream system is considered as an example.

hep-ph↗
arXiv2011

Supersymmetric QED Plasma

We systematically compare the N=1 SUSY QED plasma to its non-supersymmetric counterpart which is QED plasma of electrons, positrons and photons. Collective excitations and collisional processes in the two systems are confronted to each other in a regime of small coupling. The collective and collisional characteristics of supersymmetric plasma are both very similar to those of QED plasma.

hep-th↗
arXiv2011

Collisional Processes in Supersymmetric Plasma

Collisional processes in ultrarelativistic N=1 SUSY QED plasma are studied and compared to those in an electromagnetic plasma of electrons, positrons and photons. Cross sections of all binary interactions which occur in the supersymmetric plasma at the order of e^4 are computed. Some processes, in particular the Compton scattering on selectrons, appear to be independent of momentum transfer and thus they are qualitatively different from processes in an electromagnetic plasma. It suggests that transport properties of the SUSY plasma are different than those of its non-supersymmetric counterpart. Energy loss and momentum broadening of a particle traversing the supersymmetric plasma are discussed in detail and the characteristics are shown to be surprisingly similar to those of QED plasma.

hep-th↗
arXiv2011

Deciphering Azimuthal Correlations in Relativistic Heavy-Ion Collisions

We discuss various sources of azimuthal correlations in relativistic heavy-ion collisions. The integral measure Phi is applied to quantify the correlations. We first consider separately the correlations caused by the elliptic flow, resonance decays, jets and transverse momentum conservation. An effect of randomly lost particles is also discussed. Using the PYTHIA and HIJING event generators we produce a sample of events which mimic experimental data. By means of kinematic cuts and particle's selection criteria, the data are analyzed to identify a dominant source of correlations.

nucl-th↗
arXiv2011

Collective Excitations of Supersymmetric Plasma

Collective excitations of N = 1 supersymmetric electromagnetic plasma are studied. Since the Keldysh-Schwinger approach is used, not only equilibrium but also non-equilibrium plasma, which is assumed to be ultrarelativistic, is under consideration. The dispersion equations of photon, photino, electron and selectron modes are written down and the self-energies, which enter the equations, are computed in the Hard Loop Approximation. The self-energies are discussed in the context of effective action which is also given. The photon modes and electron ones appear to be the same as in the usual ultrarelativistic plasma of electrons, positrons and photons. The photino modes coincide with the electron ones and the selectron modes are as of free relativistic massive particle.

hep-th↗
arXiv2010

Quasi-linear transport approach to equilibration of quark-gluon plasmas

We derive the transport equations of quark-gluon plasma in the quasi-linear approximation. The equations are either of the Balescu-Lenard or Fokker-Planck form. The plasma's dynamics is assumed to be governed by longitudinal chromoelectric fields. The isotropic plasma, which is stable, and the two-stream system, which is unstable, are considered in detail. A process of equilibration is briefly discussed in both cases. The peaks of the two-stream distribution are shown to rapidly dissolve in time.

hep-ph↗
arXiv2009

On the Dynamics of Unstable Quark-Gluon Plasma

Since the quark-gluon plasma, which is unstable due to anisotropic momentum distribution, evolves fast in time, plasma's characteristics have to be studied as initial value problems. The chromodynamic fluctuations and the momentum broadening of a fast parton traversing the plasma are discussed here. The two quantities are shown to exponentially grow in time.

nucl-th↗
arXiv2009

Coulomb Effects in Femtoscopy

The correlation function of two identical particles - pions or kaons - interacting via Coulomb potential is computed. The particles are emitted from an anisotropic particle's source of finite lifetime. In the case of pions, the effect of halo is taken into account as an additional particle's source of large spatial extension. The relativistic effects are discussed in detail. The Bowler-Sinyukov procedure to remove the Coulomb interaction is carefully tested. In the absence of halo the procedure is shown to work very well even for an extremely anisotropic source. When the halo is taken into account the free correlation function, which is extracted by means of the Bowler-Sinyukov procedure, is distorted at small relative momenta but the source parameters are still correctly reproduced.

nucl-th↗
arXiv2009

Overview of event-by-event fluctuations

Overview of event-by-event studies on relativistic heavy-ion collisions is given. I focus on fluctuation measurements and on theoretical ideas which appeared experimentally fruitful.

nucl-th↗
arXiv2008

Unstable Quark-Gluon Plasma at LHC

Coupling of the quark-gluon plasma from the early stage of heavy-ion collisions is argued to be weaker at LHC than at RHIC. For this reason, the role of instabilities - the pre-equilibrium plasma is unstable with respect to chromomagnetic modes - will be enhanced. The instabilities isotropize the system and speed up the process of equilibration. A possibility to observe direct signals of the instabilities is considered.

nucl-th↗
arXiv2008

Chromodynamic Fluctuations in Quark-Gluon Plasma

Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.

hep-ph↗
arXiv2008

Plasma Electromagnetic Fluctuations as an Initial Value Problem

Fluctuations of electric and magnetic fields in the collisionless plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average stationary and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum obtained from the fluctuation-dissipation relation. Fluctuations in the unstable two-stream system are also discussed.

physics.plasm-ph↗
arXiv2007

Evolution of Anisotropy of Parton System from Relativistic Heavy-Ion Collisions

Evolution of anisotropy in momentum and coordinate space of the parton system produced in relativistic heavy-ion collisions is discussed within the free-streaming approximation. The momentum distribution evolves from the prolate shape - elongated along the beam - to the oblate one - squeezed along the beam. At the same time the eccentricity in the coordinate space, which occurs at finite values of impact parameter, decreases. It is argued that the parton system reaches local thermodynamic equilibrium before the momentum distribution becomes oblate.

nucl-th↗