39606345
Comment on the gauging of Dirac-Kähler fermions on lattices.
The method introduced in a recent paper for gauging Dirac-Kaa-italicu-italicm-italicl-italichler fermions on a simple cubic lattice is shown to be inadmissible. The formalism of that paper is used to reformulate the naive method of gauging these fermions.
7905729
Quantization of Gauge Theories with Anomalies
In this talk, we briefly review the basic concepts of anomalous gauge theories. It has been known for some time how theories with local anomalies can be handled. Recently it has been pointed out that global anomalies, which obstruct the quantization of certain gauge theories in the temporal gauge, get bypassed in canonical quantization.
119347706
Counting black hole microscopic states in loop quantum gravity
Counting of microscopic states of black holes is performed within the framework of loop quantum gravity. This is the first calculation of the pure horizon states using statistical methods, which reveals the possibility of additional states missed in the earlier calculations, leading to an increase of entropy. Also for the first time a microcanonical temperature is introduced within the framework.
17603490
Scalar field entropy in brane world black holes
A semiclassical calculation of entropy of a scalar field in the background of a class of brane world black holes (BWBH) is carried out in the presence of a brick wall cutoff when the 5D-bulk induced "tidal charge" has generic or extreme values.
120593680
Physical solution of chiral Schwinger model with new regularization
Abstract A recently proposed version of the chiral Schwinger model is solved in this paper. The exact fermion propagator is derived in a path integral approach. The operator equations of motion of the bosonised theory are solved. Finally, the operator solution of the fermionic form of the theory is constructed.
9159427
Poincaré invariance of anomalous gauge theories.
We establish the Poincare invariance of anomalous gauge theories in two dimensions, for both the Abelian and non-Abelian cases, in the canonical Hamiltonian formalism. It is shown that, despite the noncovariant appearance of the constraints of these theories, Poincare generators can be constructed which obey the correct algebra and yield the correct transformations in the constrained space.
18249187
Off-shell rho - omega mixing through quark loops with a nonperturbative meson vertex and quark mass functions.
The momentum dependence of the off-shell {rho}-{omega} mixing amplitude is calculated through a two-quark loop diagram, using nonperturbative meson-quark vertex functions for the {rho} and {omega} mesons, as well as nonperturbative quark propagators. Both these quantities are generated self-consistently through an interlinked Bethe-Salpeter equation (BSE) cum Schwinger- Dyson equation (SDE) approach with a 3D support for the BSE kernel with two basic constants that are prechecked against a wide cross section of both meson and baryon spectra within a common structural framework for their respective 3D BSE`s. With the precalibration, the on-shell strength works out at {minus}2.434 {delta}({ital m}{sub {ital q}}{sup 2}) in units of the change in ``constituent mass squared,`` which is consistent with the {ital e}{sup +}{ital e}{sup {minus}} to {pi}{sup +}{pi}{sup {minus}} data for a {ital u}-{ital d} mass difference of 4 MeV, while the relative off-shell strength (0.99{plus_minus}0.01) lies midway between quark-loop and QCD-SR results. We also calculate the photon-mediated {rho}-{omega} propagator whose off-shell structure has an additional pole at {ital q}{sup 2}=0. The implications of these results vis-a-vis related investigations are discussed.
34793795
From light to heavy quarkonia: An integrated Bethe-Salpeter view.
A modification in the (harmonic) kernel of a QCD-oriented Bethe-Salpeter equation known for good fits to q-italicq-bar and q-italicq-italicq-italic spectroscopy gives a comprehensive description of q-italicq-bar, Q-italicq-bar, and Q-italicQ-bar systems. The new assumptions are (i) proportionality of the ''reduced'' spring constant omega-tilde/sup 2/ to ..cap alpha../sub s-italic/ (omega-tilde/sup 2/ = ..omega../sub 0//sup 2/..cap alpha../sub s/) and (ii) the replacement r-italic/sup 2/..-->..r/sup 2//(1+A/sub 0/m/sub 1/m/sub 2/r/sup 2/ )/sup 1/2/-c/sub 0//..omega../sub 0//sup 2/. These provide a more direct QCD motivation for confinement and effect a smooth transition from harmonic (q-italicq-bar) to linear (Q-italicQ-bar) confinement.
30997914
Null-plane Bethe-Salpeter dynamics: Mass spectra, decay constants of pseudoscalar mesons, and the pion form factor.
A new relativistic definition of the reduced mass ({mu}{sub 12}) of a {ital q{bar q}} pair, so as to be in conformity with the standard Wightman-Garding definition of its relative four-momenta {ital q}{sub {mu}}, is introduced into the kernel of an ongoing Bethe-Salpeter (BS) program on a two-tier basis. The new definition of {mu}{sub 12} (involving the hadron mass {ital M}) is found to produce a natural Regge asymptotic behavior ({ital M}{sup 2}{approximately}{ital N}) in the hadron mass spectra, while retaining the property of an asymptotically linear ({approximately}{ital r}) confinement in the three-dimensional structure of the BS kernel. The relativistic structure of {mu}{sub 12} is responsible for a significant improvement in the fits to the ground-state masses of {ital q{bar q}} and {ital Q{bar q}} mesons as compared to its nonrelativistic definition {ital m}{sub 1}{ital m}{sub 2}/({ital m}{sub 1}+{ital m}{sub 2}). The leptonic decay constants {ital f}{sub {ital p}} and the charge radii thus calculated are also in excellent agreement with data ({pi},{ital k}) where available, while {ital f}{sub {ital p}} predictions for {ital Q{bar q}} mesons have good overlap with recent lattice predictions. Further, the scaling property ({approximately}{ital k}{sub {mu}}{sup {minus}2}) of the hadron's electromagnetic form factor at largemore » {ital k}{sup 2} is a consequence of the on-shell'' form of its null-plane wave function. All these results (which are indicated in the barest outline) are preceded by a perspective summary of the theoretical premises and practical working of the BS equation with a four-fermion interaction kernel as a necessary background on a two-tier basis.« less
33172464
Khalfin's theorem and a proposed test of time-reversal invariance.
A theorem closely related to one stated by Khalfin requires that, if the (time-dependent) rate for transitions a\ensuremath{\rightarrow}b is a constant multiple of the rate for the inverse transitions b\ensuremath{\rightarrow}a, the only possible value of that constant is unity, viz., reciprocity must hold. We consider a more general situation in which the two rates can be approximately, although not exactly, proportional. The application of similar arguments to the corresponding generalized situation shows that an earlier prediction of departure from reciprocity in ${\mathit{K}}^{0\ensuremath{\rightleftarrows}}$K${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$ transitions is not endangered by the theorem.
35025289
Hadronic transition amplitudes under null-plane Bethe-Salpeter dynamics.
A two-tier form of the Bethe-Salpeter (BS) framework is employed for the evaluation of a few typical transition amplitudes involving strong and electromagnetic decays of qq-bar hadrons with Lgreater than or equal to0. The two-tier BS framework, whose rationale has been described in some recent publications, is characterized by (i) a three-dimensional reduction of the BS equation under the null-plane ansatz to make a first contact with mass spectral data and (ii) a reconstructed four-dimensional BS wave function to restore the virtual qq-bar effects (higher Fock states) for the evaluation of hadronic transition amplitudes through the lowest-order Feynman (quark-triangle) diagrams. The processes explicitly considered are the pion form factor F/sub ..pi../(k/sup 2/), (..omega..,a/sub 2/)..--> gamma pi.., (rho,f/sub 2/)->..pi pi.., (a/sub 1/,a/sub 2/)..-->..rho..pi.., and b/sub 1/..--> omega pi... These illustrate the different types of coupling structures that are generally encountered in such a composite-hadron model. The agreement with the data on almost all these amplitudes is excellent, using the same basic constants (..omega../sub 0/,C/sub 0/,m/sub u//sub d/) as employed recently for a successful description of the mass spectra of qq-bar and qqq hadrons, as well as of some pionic amplitudes.