International Journal of Modern Physics E

We briefly review the growing efforts to set up a unified framework for the description of neutrino interactions with atomic nuclei and nuclear matter, applicable in the broad kinematical region corresponding to neutrino energies ranging between few MeV and few GeV. The emerging picture suggests that the formalism of nuclear many-body theory (NMBT) can be exploited to obtain the neutrino-nucleus cross-sections needed for both the interpretation of oscillation signals and simulations of neutrino transport in compact stars.

The half-lives of even–even nuclei with proton number Z ≥ 94 are calculated by proximity potential with a new universal function, especially for superheavy nuclei. The calculation results are compared to the experimental data. It is shown that from the presently obtained universal function, the calculated half-lives of α decay can basically keep agreement with the experimental data for most of even–even nuclei. Those of superheavy nuclei are also calculated and discussed.

An expression of a wave function which describes odd–even systems in the isovector pairing case is proposed within the BCS approach. It is shown that it correctly generalizes the one used in the pairing between like-particles case. It is then projected on the good proton and neutron numbers using the Sharp-BCS (SBCS) method. The expressions of the expectation values of the particle-number operator and its square, as well as the energy, are deduced in both approaches. The formalism is applied to study the isovector pairing effect and the number projection one on the ground state energy of odd mass N ≈ Z nuclei using the single-particle energies of a deformed Woods–Saxon mean-field. It is shown that both effects on energy do not exceed 2%, however, the absolute deviations may reach several MeV. Moreover, the np pairing effect rapidly diminishes as a function of (N - Z). The deformation effect is also studied. It is shown that the np pairing effect, either before or after the projection, as well as the projection effect, when including or not the isovector pairing, depends upon the deformation. However, it seems that the predicted ground state deformation will remain the same in the four approaches.

The first search ever for the α-decay of ¹⁴⁶Nd into the first excited state of ¹⁴²Ce has been performed by using an ultra-low background High Purity Germanium (HPGe) detector and a Nd-sample with 97.20(1)% abundance of ¹⁴⁶Nd. No significant signal could be observed with a measuring time of 144 h. A lower limit on the half-life of this decay mode has been determined to be T_1/2 > 1.6 × 10¹⁸ years at 90% CL.

This paper deals with the hadronization process of quark system. A phenomenological potential is introduced to describe the interaction between a quark pair. The potential depends on the color charge of those quarks and their relative distances. Those quarks move according to classical equations of motion. Due to the color interaction, coloring quarks are separated to form color neutral clusters which are supposed to be the hadrons.

Introducing collective variables, a collective description of nuclear surface oscillations has been developed with the first-quantized language, contrary to the second-quantized one in Sunakawa's approach for a Bose system. It overcomes difficulties remaining in the traditional theories of nuclear collective motions: Collective momenta are not exact canonically conjugate to collective coordinates and are not independent. On the contrary to such a description, Tomonaga first gave the basic idea to approach elementary excitations in a one-dimensional Fermi system. The Sunakawa's approach for a Fermi system is also expected to work well for such a problem. In this paper, on the isospin space, we define a density operator and further following Tomonaga, introduce a collective momentum. We propose an exact canonically momenta approach to a one-dimensional neutron–proton (N–P) system under the use of the Grassmann variables.

We analyze the transverse momentum spectra of charged pions measured in Au + Au collisions at and in Pb + Pb collisions at using the Tsallis distribution modified to include transverse flow. All the spectra are well described by the modified Tsallis distribution in an extended transverse momentum range upto 6 GeV/c. The kinetic freeze-out temperature (T), average transverse flow (β) and degree of nonthermalization (q) are obtained as a function of system size for both the energies. With increasing system size β shows increasing trend whereas T remains constant. While the systems at RHIC and LHC energies show similar β and q, the parameter T is higher at LHC as compared to RHIC. The kinetic freeze-out temperature is also extracted using the measured charged particle multiplicity and HBT volume of the system as a function of system size and collision energies.

The angular distribution measurements for ¹⁶O ion beam elastically scattered from ¹¹B target of thickness 32.9μg/cm² at energy 22.4 MeV had been performed in the cyclotron DC-60 INP NNC RK. The previous measurements for ¹⁶O+¹¹B nuclear system at energies 27, 30, 32.5 and 35 MeV showed an increase in the differential cross-section at backward angles due to the contribution of cluster transfer. Such transfer process could not be described in terms of optical model (OM); it could be described within the framework of distorted wave Born approximation method implemented in FRESCO code. Both one (⁵Li) and two-step transfer (proton transfer followed by Alpha transfer) were taken into considerations. We have extracted the spectroscopic amplitude (SA) for the configuration ¹⁶O→¹¹B+⁵Li.

In the present paper, some results on the correlations of the nucleus–nucleus interactions, at high energy, between different particle multiplicities are reported. The correlations between the multiplicities of the different charged particles emitted in the interactions of ²²Ne and ²⁸Si nuclei with emulsion at (4.1–4.5)A GeV/c have been studied. The correlations of the compound multiplicity n_c, defined as the sum of both numbers of the shower particles n_s and grey particles n_g, have been investigated. The experimental data have been compared with the corresponding theoretical ones, calculated according to the modified cascade evaporation model (MCEM). An agreement has already been fairly obtained between the experimental values and the calculated ones. The dependence of the average compound multiplicity, on the numbers of shower, grey, black and heavy particles is obvious and the values of the slope have been found to be independent of the projectile nucleus. On the other hand, the variation of the average shower, grey, black and heavy particles is found to increase linearly with the compound particles. A strong correlation has been observed between the number of produced shower particles and the number of compound particles. Moreover, the value of the average compound multiplicity is found to increase with the increase of the projectile mass. Finally, an attempt has also been made to study the scaling of the compound multiplicity distribution showing that the compound multiplicity distribution is nearly consistent with the KNO scaling behavior.

Various aspects of the simple phenomenological model, the grand combinational model (GCM), proposed earlier for the systematic description of the center-of-mass (cm) rapidity distributions of different particles produced in high energy heavy ion collisions, were analyzed. The values of GCM parameters were extracted from fitting the cm rapidity distributions of the negative pions in ¹²C+¹²C collisions at both in the experiment and using Modified FRITIOF Model. The GCM parameters extracted for the central ¹²C+¹²C collisions were compared with those obtained in central Pb+Pb collisions at super proton synchrotron (SPS) and alternating gradient synchrotron (AGS) energies between and and in central Au+Au collisions at Relativistic heavy ion collider (RHIC) energies between and . The plausible physical interpretations for the GCM parameters were given. The initial assumption that the parameter β of GCM should be zero for symmetric systems with identical colliding nuclei was validated. The parameter γ of GCM was deduced to follow an approximate asymptotic behavior (γ → 0 as at very large cm energies, and γ ≅ 0 could possibly be related to complete dehadronization of the whole collision system, along with attaining its maximum possible energy density, in central collisions of identical nuclei. The behavior of cm energy dependence of γ suggested that it could possibly be sensitive to deconfinement phase transition.

We study the rare mesonic decays and for the search of new physics (NP) in the form of nonstandard neutrino interactions (NSIs). We calculate branching ratios (BRs) of these decays in the framework of NSIs. We try to explore the possibility for second and third generations of quarks in NSIs, exactly on the same footing as for leptonic case we have and . We show that there exist a possibility for and also from these reactions. Three other processes and are investigated with s and b quarks in the loop for NSIs instead of d quark only. Constraints on and (where q = s, b and l, l′ ≠ τ) are provided. We point out that constraints for u, c and t quarks are equal and similarly for d, s and b quarks the constraints are equal .