Modern Physics Letters A

In this review we consider the distinctive phenomenology of supersymmetric models in which the scale of SUSY breaking is very low, , focusing on the Higgs sector and the process of electroweak breaking. Using an effective Lagrangian description of the interactions between the observable fields and the SUSY breaking sector, it is shown how the conventional MSSM picture can be substantially modified. For instance, the Higgs potential has non-negligible SUSY breaking quartic couplings that can modify completely the pattern of electroweak breaking and the Higgs spectrum with respect to that of the conventional MSSM-like models.

Observation of the neutrinoless double beta decay (0νββ) has established that there is lepton number violation in nature and the neutrino masses are Majorana in nature. It also gives the absolute mass of the neutrinos and discriminates between different models of neutrino masses. The allowed amount of lepton number violation puts severe constraints on some possible new physics beyond the standard model. The recent results from WMAP are consistent with the consequences of the neutrinoless double beta decay. They improve some of these constraints very marginally, which we shall summarize here. We mention the new physics which is not affected by WMAP, and which could make the limits from the neutrinoless double beta decay even consistent with much tighter future cosmological limits.

Chiral symmetry breaking at finite baryon density is usually discussed in the context of quark matter, i.e. a system of deconfined quarks. Many systems like stable nuclei and neutron stars however have quarks confined within nucleons. In this paper we construct a Fermi sea of three-quark nucleon clusters and investigate the change of the quark condensate as a function of baryon density. We study the effect of quark clustering on the in-medium quark condensate and compare results with the traditional approach of modeling hadronic matter in terms of a Fermi sea of deconfined quarks.

A mechanism of formation of a spiral galaxy is proposed. The galaxy is considered to be a cluster consisting of stars and gaseous clouds. Initially, the galaxy has elliptical geometry and slow rotational motion around one axis. The gravitational interaction between the stars has been modelled. The cluster contracted and transformed its geometry. The geometry of the initial cluster changes due to the change of the rotational velocities of the stars in accordance with the Kepler's second law and change of the relative positions of the stars. The computer simulation reveals that a spiral shaped galaxy is a result of the transformation of a cluster of non-spherical symmetry. An example of the gravitational contraction of an elliptically-shaped galaxy is presented in this paper.

A new approach treating constrained systems based on the consistency condition of constraints is proposed in this paper. This method is simpler and more rigorous in mathematics. It is not necessary to introduce the concepts of weakly equal, strongly equal, Dirac brackets and Dirac conjecture. The procedure of our method is demonstrated by using Cawley's counterexample to Dirac's conjecture.

In this paper the study of gap probability of protons has been carried out with ²⁸Si–AgBr interaction at 14.5 A GeV in emission angle space. The study reveals the scaling behaviour of the void probability which hints towards the outer space–inner space connection. This study also confirms the validity of the linked pair approximation for the N-particle cumulant correlation functions in case of protons.

Without resorting to the symplectic condition, we rigorously study the constraint structure of the topologically massive theory with one- and two-form fields in the framework of Batalin–Fradkin–Tyutin Hamiltonian embedding procedure. Through this full analysis we obtain a new type of Wess–Jumino action with novel symmetry, which is originated from the topological coupling term, as well as the Stückelberg action related to the explicit gauge breaking mass terms from the original theory.