Center for Theoretical Physics

About: Center for Theoretical Physics is a facility organization based out in Warsaw, Poland. It is known for research contribution in the topics: Gamma-ray burst & Accretion (astrophysics). The organization has 68 authors who have published 112 publications receiving 1086 citations. The organization is also known as: Centrum Fizyki Teoretycznej PAN & Centrum Fizyki Teoretycznej Polskiej Akademii Nauk.

Photon as a quantum particle

Abstract: Center for Theoretical Physics, Polish Academy of SciencesLotnikow 32/46, 02-668 Warsaw, PolandandInstitute of Theoretical Physics, Warsaw UniversityHoza 69, 00-681 Warsaw, Polandbirula@cft.edu.pl(Received January 17, 2006)Our present understanding of the nature of photons significantly differsfrom what has been known years ago when the concept of a photon has onlybeen emerging. Unfortunately, very little of this knowledge trickles to thosestudents who do not specialize in theoretical physics. In this lecture, inaddition to giving a historical perspective on the “problem of the photon”,I shall say something about the description of the photon as a quantummechanical particle. In addition, I shall show how the quantum descriptionmerges with the classical description of the electromagnetic field.PACS numbers: 03.65.–w, 03.50.De, 42.50.–p

Slim Accretion Disks: Theory and Observational Consequences

Abstract: The concept of slim accretion disks emerged over 30 years ago as an answer to several unsolved problems. Since that time there has been a tremendous increase in the amount of observational data where this model applies. However, many critical issues on the theoretical side remain unsolved, as they are inherently difficult. This is the issue of the disk stability under radiation pressure, the role of the magnetic field in the energy transfer inside the disk, the formation (or not) of a warm corona, and outflows. Thus the progress has to be done both through further developments of the model and through careful comparison with the observational data.

Cosmology With Non-Minimally Coupled K-Field

Abstract: We consider non-minimally coupled (with gravity) scalar field with non-canonical kinetic energy. The form of the kinetic term is of Dirac-Born-Infeld (DBI) form.We study the early evolution of the universe when it is sourced only by the k-field, as well as late time evolution when both the matter and k-field are present. For the k-field, we have considered constant potential as well as potential inspired from Boundary String Field Theory (B-SFT). We show that it is possible to have inflationary solution in early time as well as late time accelerating phase. The solutions also exhibit attractor property in a sense that it does not depend on the initial conditions for a certain values of the parameters.

Microphysics in the gamma ray burst central engine

Abstract: We calculate the structure and evolution of a gamma ray burst central engine where an accreting torus has formed around the newly born black hole. We study the general relativistic,MHD models and we self-consistently incorporate the nuclear equation of state. The latter accounts for the degeneracy of relativistic electrons, protons, and neutrons, and is used in the dynamical simulation, instead of a standard polytropic -law. The EOS provides the conditions for the nuclear pressure in the function of density and temperature, which evolve with time according to the conservative MHD scheme. We analyze the structure of the torus and outflowing winds, and compute the neutrino flux emitted through the nuclear reactions balance in the dense and hot matter. We also estimate the rate of transfer of the black hole rotational energy to the bipolar jets. Finally, we elaborate on the nucleosynthesis of heavy elements in the accretion flow and the wind, through computations of the thermonuclear reaction network. We discuss the possible signatures of the radioactive elements decay in the accretion flow. We suggest that further detailed modeling of the accretion flow in GRB engine, together with its microphysics, may be a valuable tool to constrain the black hole mass and spin. It can be complementary to the gravitational wave analysis, if the waves are detected with an electromagnetic counterpart.

Self-intersection number of BPS junctions in backgrounds of three and seven-branes

Abstract: In a recent paper De Wolfe et al. have shown how to use the self-intersection number of junctions to constrain the BPS spectrum of = 2, D = 4 theories with ADE flavor symmetry arising on a single D3-brane probe in a 7-brane background. Motivated by the existence of more general = 2, D = 4 theories arising on the worldvolume of multiple D3-brane probes we show how to compute the self-intersection number of junctions in the presence of 7-branes and multiple D3-branes.