Modern Physics Letters A

We review a recently developed framework employing computable Renormalization Group (RG) decimations for gauge theories in the lattice regularization. They provide upper and lower bounds at every scale for free energies and some order parameters. By interpolating between these bounds representations of the exact quantities are obtained at progressively longer scales (coarser lattices). In the case of the SU(2) gauge theory in four dimensions RG flow to the confining strongly coupled regime is obtained for any initial coupling; whereas for the U(1) theory a fixed point is reached for small initial coupling.

We incorporate the parameters of the gauge group G into the gauge theory of interactions through a nonlinear partial-trace σ-model Lagrangian on G/H. The minimal coupling of the new (Goldstone-like) scalar bosons provides mass terms to those intermediate vector bosons associated with the quotient G/H, without spoiling gauge invariance, while the H-vector potentials remain massless. The main virtue of a partial trace on G/H, rather than on the entire G, is that we can find an infinite-dimensional symmetry, with nontrivial Noether invariants, which ensures quantum integrability in a non-canonical quantization scheme. The present formalism is explicitly applied to the case G = SU(2)× U(1), as a Higgsless alternative to the Standard Model of electroweak interactions, although it can also be used in low-energy phenomenological models for strong interactions.

The unknown neutrino parameters may leave detectable signatures in the supernova (SN) neutrino flux. However, even the contribution from the MSW flavor transition alone could cause ambiguity in the interpretation to the neutrino signals because of the uncertain local density profile of the SN matter and the model-dependent SN neutrino spectral parameters. A specific parametrization to the unknown local density profile is proposed in this work, and the contribution from the standard MSW effect is investigated through a multi-detector analysis of the SN neutrinos. In establishing the model-independent scheme, results based on the existing spectral models are included. The limitation of the analysis is also discussed.

We show that the coupled two-fluid gravitating system (e.g. stiff matter and "vacuum energy") could trap nonlinear gravitational waves (e.g. Einstein–Rosen waves). The gravitational wave amplitude varies harmonically in time transferring the energy coherently to the stiff matter wave, and then the process goes to the backward direction. This process mimics the behavior of trapped electromagnetic waves in two-level media. We have defined the limits for the frequency of this energy transfer oscillations.

It is shown that when the stress–energy tensor of a spacetime is diagonal and is written in the mixed form, its collineations admit infinite dimensional Lie algebras except possibly in the case when the tensor depends on all the spacetime coordinates. The result can be extended for more general second rank tensors.

The energy distributions for a black hole solution resulting from coupling electrodynamics and gravity in (2+1) dimensions are obtained. This solution considers the correction for a (2+1) static charged black hole from the first contribution of the weak field limit of one-loop QED in (2+1) dimensions. The Einstein and Møller energy–momentum prescriptions are used to evaluate the energy distributions associated with the mentioned (2+1)-dimensional black hole and other (2+1) black hole solutions coupled with nonlinear electrodynamics. A relation that connects the coefficients of both prescriptions is established.

We assume the bosonic string is a composite object of the relativistic particles. The behavior of the relativistic particles in a curve enables us to obtain the Nambu–Goto and the Polyakov actions of the bosonic string. We observe that the particles of these strings move with non-constant speeds along them.