1,443 research outputs found
Topological Discrete Algebra, Ground State Degeneracy, and Quark Confinement in QCD
Based on the permutation group formalism, we present a discrete symmetry
algebra in QCD. The discrete algebra is hidden symmetry in QCD, which is
manifest only on a space-manifold with non-trivial topology. Quark confinement
in the presence of the dynamical quarks is discussed in terms of the discrete
symmetry algebra. It is shown that the quark deconfinement phase has the ground
state degeneracy depending on the topology of the space, which gives a
gauge-invariant distinction between the confinement and deconfinement phases.
We also point out that new quantum numbers relating to the fractional quantum
Hall effect exist in the deconfinement phase.Comment: 11 pages, 1 figur
Action and Hamiltonian for eternal black holes
We present the Hamiltonian, quasilocal energy, and angular momentum for a
spacetime region spatially bounded by two timelike surfaces. The results are
applied to the particular case of a spacetime representing an eternal black
hole. It is shown that in the case when the boundaries are located in two
different wedges of the Kruskal diagram, the Hamiltonian is of the form , where and are the Hamiltonian functions for the right
and left wedges respectively. The application of the obtained results to the
thermofield dynamics description of quantum effects in black holes is briefly
discussed.Comment: 24 pages, Revtex, 5 figures (available upon request
Maximum Entanglement in Squeezed Boson and Fermion States
A class of squeezed boson and fermion states is studied with particular
emphasis on the nature of entanglement. We first investigate the case of
bosons, considering two-mode squeezed states. Then we construct the fermion
version to show that such states are maximum entangled, for both bosons and
fermions. To achieve these results, we demonstrate some relations involving
squeezed boson states. The generalization to the case of fermions is made by
using Grassmann variables.Comment: 4 page
Finite temperature amplitudes and reaction rates in Thermofield dynamics
We propose a method for calculating the reaction rates and transition
amplitudes of generic process taking place in a many body system in
equilibrium. The relationship of the scattering and decay amplitudes as
calculated in Thermo Field Dynamics the conventional techniques is established.
It is shown that in many cases the calculations are relatively easy in TFD.Comment: 32 pages, RevTex, 2 PS figures, to appear in Phys. Rev.
Spectra of Quarkonia at Finite Temperature
Finite-temperature spectra of heavy quarkonia are calculated by combining
potential model and thermofield dynamics formalisms. The mass spectra of the
heavy quarkonia with various quark contents are calculated. It is found that
binding mass of the quarkonium decreases as temperature increases.Comment: 12 pages, 1 figure. To appear Mod.Phys.Lett.
Influence of modal loss on the quantum state generation via cross-Kerr nonlinearity
In this work we investigate an influence of decoherence effects on quantum
states generated as a result of the cross-Kerr nonlinear interaction between
two modes. For Markovian losses (both photon loss and dephasing), a region of
parameters when losses still do not lead to destruction of non-classicality is
identified. We emphasize the difference in impact of losses in the process of
state generation as opposed to those occurring in propagation channel. We show
moreover, that correlated losses in modern realizations of schemes of large
cross-Kerr nonlinearity might lead to enhancement of non-classicality.Comment: To appear in PR
QED symmetries in real-time thermal field theory
We study the discrete and gauge symmetries of Quantum Electrodynamics at
finite temperature within the real-time formalism.
The gauge invariance of the complete generating functional leads to the
finite temperature Ward identities. These Ward identities relate the eight
vertex functions to the elements of the self-energy matrix. Combining the
relations obtained from the and the gauge symmetries of the theory we
find that only one out of eight longitudinal vertex functions is independent.
As a consequence of the Ward identities it is shown that some elements of the
vertex function are singular when the photon momentum goes to zero.Comment: New version as it will appear in Phys RevD 19 pages, RevTex, 1figur
Placenta growth factor induces melanoma resistance to temozolomide through a mechanism that involves the activation of the transcription factor NF-κB
Placenta growth factor (PlGF) and its receptor vascular endothelial growth factor receptor-1 (VEGFR-1) are co-expressed in a large number of human melanoma cell lines. Moreover, a correlation between in vivo PlGF production and melanoma progression has been suggested. To investigate whether PlGF might have a role in protecting melanoma cells from the cytotoxic effects of the anticancer agent temozolomide (TMZ), which is used for the treatment of this malignancy, we stably transfected a doxycycline-inducible PlGF antisense mRNA into a human melanoma cell clone that secretes VEGF-A and PlGF and expresses receptors for both growth factors. Induction of PlGF antisense mRNA in the transfected cells (13443/ASP3 subclone) halved TMZ IC(50), and exogenous addition of PlGF to the culture medium 24 h before TMZ treatment, partially restored IC(50) values to that of control cells. The increased sensitivity of 13443/ASP3 cells upon PlGF antisense mRNA expression was not due to down-regulation of O6-methylguanine-DNA methyltransferase, a DNA repair protein that represents the main mechanism of resistance to TMZ. Since the activity of the transcription factor nuclear factor-κB (NF-κB) has been correlated to melanoma chemoresistance, we investigated whether NF-κB was involved in PlGF-induced melanoma cell resistance to TMZ. Induction of PlGF antisense mRNA in 13443/ASP3 cells halved the levels of active NF-κB and the specific inhibition of this transcription factor increased sensitivity of 13443/ASP3 cells to TMZ. In conclusion, our data strongly suggest that PlGF plays a role in melanoma cell resistance to TMZ through a pathway that involves NF-κB activation
Field theory of massive and massless vector particles in the Duffin - Kemmer - Petiau formalism
Field theory of massive and massless vector particles is considered in the
first-order formalism. The Hamiltonian form of equations is obtained after the
exclusion of non-dynamical components. We obtain the canonical and symmetrical
Belinfante energy-momentum tensors and their nonzero traces. We note that the
dilatation symmetry is broken in the massive case but in the massless case the
modified dilatation current is conserved. The canonical quantization is
performed and the propagator of the massive fields is found in the Duffin -
Kemmer - Petiau formalism.Comment: 20 pages, typos corrected, a reference added, journal version,
accepted in Int.J.Mod.Phys.
PP-Wave Light-Cone Free String Field Theory at Finite Temperature
In this paper, a real-time formulation of light-cone pp-wave string field
theory at finite temperature is presented. This is achieved by developing the
thermo field dynamics (TFD) formalism in a second quantized string scenario.
The equilibrirum thermodynamic quantities for a pp-wave ideal string gas are
derived directly from expectation values on the second quantized string thermal
vacuum. Also, we derive the real-time thermal pp-wave closed string propagator.
In the flat space limit it is shown that this propagator can be written in
terms of Theta functions, exactly as the zero temperature one. At the end, we
show how supestrings interactions can be introduced, making this approach
suitable to study the BMN dictionary at finite temperature.Comment: 27 pages, revtex
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