Modern Physics Letters A

In this brief review, we summarize the current theoretical knowledge in supersymmetry on the lattice, with special emphasis on recent results in the framework of N=1 supersymmetric Yang–Mills theory, Wess–Zumino model and Yang–Mills theory with extended supersymmetries.

We study the properties of the color triplet quark cluster when flavor symmetry is broken. The relevance of such a cluster for some models of pentaquarks is then examined in the light of recent experimental signals.

A singular metric arising in some brane models can substantially influence the behavior of Green's functions. We show that the quantum scalar field defined by a restriction of the Green's function to the brane can behave as a canonical quantum field living on the lower dimensional submanifold.

There exists a recursive algorithm for constructing BPST-type multi-instantons on commutative ℝ⁴. When deformed noncommutatively, however, it becomes difficult to write down non-singular instanton configurations with topological charge greater than one in explicit form. We circumvent this difficulty by allowing for the translational instanton moduli to become noncommutative as well. Such a scenario is natural in the self-dual Yang–Mills hierarchy of integrable equations where the moduli of solutions are seen as extended spacetime coordinates associated with higher flows. By judicious adjustment of the moduli-noncommutativity we achieve the ADHM construction of generalized 't Hooft multi-instanton solutions with everywhere self-dual field strengths on noncommutative ℝ⁴.

During the last couple of years astronomers and astrophysicists have been debating on the fact whether the so-called "strange stars" — stars made up of strange quark matter, have been discovered with the candidates like SAX J1808.4–3658, 4U 1728–34, RX J1856.5–3754, etc. The main contention has been the estimation of radius of the star for an assumed mass of ~ 1.4 M_⊙ and to see whether the point overlaps with the graphs for the neutron star equation of state or whether it goes to the region of stars made of strange matter equation of state. Using the well-established formulae from general relativity for the gravitational redshift and the "lensing effect" due to bending of photon trajectories, we, in this letter, relate the parameters M and R with the observable parameters, the redshift z and the radiation radius R_∞, thus constraining both M and R for specific ranges, without any other arbitrariness. With the required inputs from observations, one ought to incorporate the effects of self-lensing of the compact stars which has been otherwise ignored in all of the estimations done so far. Nonetheless, these effects of self-lensing make a marked difference for constraints on the M–R relation.

The results for the nuclear-matter properties in a chiral hadronic model have been compared with those in the nonlinear Walecka model. It has been found that the scalar and the vector potentials and binding energies per nucleon for nuclear matter in the chiral hadronic model are very close to those of the RBHF. Two-proton halo in ²⁷S and one-proton halo in ²⁶P are predicted when the chiral hadronic model is extended to study proton halos in light proton-rich nuclei. Comparison between the results obtained in the chiral hadronic model and in the nonlinear Walecka model has been made, it has been shown that the chiral hadronic model can also be used to describe the properties of light proton-rich nuclei.

Chiral cosmic strings are naturally produced at the end of D-term inflation and they present very interesting cosmological consequences. In this work, we investigate the formation and evolution of wakes by a chiral string. We show that, for cold dark matter, the mechanism of forming wakes by a chiral string is similar to the mechanism by an ordinary string.