Characteristics of scattering of Λ hyperons from nuclei within the potential model

The characteristics of bound states of hypernuclei were calculated in [1] in a wide range of mass numbers within the potential model for three different potentials. In this study, the phase shifts and low-energy parameters for scattering of Λ hyperons from core nuclei, considered in [1], have been calculated for the same potentials. The calculated scattering lengths and effective radii are compared with their values found in [1] on the basis of the data on the binding energies and vertex constants of hypernuclei.     

Differentiability of the energy surfaces of even–even nuclei

The expansion of even–even nucleus energy in power series of deviations from the given values of neutron and proton numbers. The calculation of the expansion parameters up to the sixth order shows that the values of parameters are sensible to the choice of the group of nuclei used for the calculation. This indicates that the nuclear energy surface is not sufficiently smooth (or completely differentiable). It is shown that the expression proposed earlier by the authors for the pairing energy of an odd nucleus in a definite quantum state does not need to be refined and can be used for the subsequent analysis of pairing energies.     

Correlation femtoscopy of Λ hyperons in the SELEX experiment

Study of the correlations of two identical particles with a small relative difference in their 4-momenta can provide information on the space-time behavior of a source and the shape of the potential between the particles. Our study of correlations is based on the SELEX experimental data. From a set of events involving Λ pairs, we selected the approximately ∼2600 such events with the best kinematical parameters, on the basis of which the preliminary results from our analysis of ΛΛ system correlations are presented.     

Spin correlations of Λ hyperons in the SELEX experiment

Two-particle correlations of the pairs of identical Λ hyperons in Σ⁻ A interactions were studied based on the statistical data obtained in the SELEX experiment performed using the Tevatron collider at FNAL in 1996–1997. The preliminary results from the investigations of spin correlations of ΛΛ pairs are presented, and the dimension of the region of ΛΛ generation is estimated. The results are in good agreement with the world data and the result obtained using correlation function analysis.     

A measurement of the lifetimes of Ξ0 and Λ hyperons

The mean lifetimes of the Λ and Ξ⁰ hyperons have been measured in a short neutral beam at the CERN Proton Synchrotron. Λ and Ξ⁰ decays have been identified by measuring their decay products in a magnetic spectrometer and in a lead glass hodoscope. The experimental results, based on 53 000 Λ decays and 6300 Ξ⁰ decays are

From the result for τ_Ξ⁰ together with existing data on τ_Ξ^? we obtain a violation of the $\text{ΔI =}\text{1}\text{2}$ rule in non-leptonic Ξ decays.     

Correlations of Λ hyperons with a small relative momentum in the SELEX experiment

The information on the shape of the potential between two baryons at small distances can be obtained by studying the baryon correlations at a small relative momentum in the creation reactions of high-energy hadron collisions. We have physically analyzed the SELEX experimental data and identified more than 20 × 10³ events with creation of two Λ hyperons, which substantially exceeds the world statistical data. The obtained results are preliminary analyzed.     

Nonaxial shapes of even–even lantanide and actinide nuclei in excited collective states

Quadrupole-type excited states of even–even nuclei are studied on the basis of arbitrary-triaxiality model. It is shown that the inclusion of high-order terms in the expansion of the rotational-energy operator in the variable γ improves substantially agreement between our theoretical results and respective experimental data. The proposed model makes it possible to explain the intricate character of the spectrum of excited states of even–even lanthanide and actinide nuclei.     

Phonon–particle coupling effects in odd–even mass differences of semi-magic nuclei

A method to evaluate the particle–phonon coupling (PC) corrections to the single-particle energies in semi-magic nuclei, based on a direct solving the Dyson equation with PC corrected mass operator, is used for finding the odd–even mass difference between 18 even Pb isotopes and their odd-proton neighbors. The Fayans energy density functional (EDF) DF3-a is used which gives rather high accuracy of the predictions for these mass differences already on the mean-field level, with the average deviation from the existing experimental data equal to 0.389 MeV. It is only a bit worse than the corresponding value of 0.333 MeV for the Skyrme EDF HFB-17, which belongs to a family of Skyrme EDFs with the highest overall accuracy in describing the nuclear masses. Account for the PC corrections induced by the low-laying phonons 2 ₁ ⁺ and 3 ₁ ^- significantly diminishes the deviation of the theory from the data till 0.218 MeV.     

Phonon–particle coupling effects in odd–even double mass differences of magic nuclei

It has been proposed to use the formation of a magnetized plasma of laser-accelerated ions and electrons at the irradiation of the curved surface of the inner cavity of the target by a petawatt laser pulse to initiate a neutronless nuclear reaction of protons with boron nuclei. The possibility of an additional increase in the intensity of the reaction owing to the compression of the plasma at the irradiation of the outer surface of the target by a second terawatt laser pulse synchronized in time with the plasma-forming pulse has been discussed. The parameters of laser pulses and a target have been determined at which the ignition of a pB plasma occurs; i.e., the energy released in reactions is equal to the energy of the plasma.     

Phonon–particle coupling effects in odd–even double mass differences of semi-magic nuclei

A method is developed to consider the particle–phonon coupling (PC) effects in the calculation of the odd–even double mass differences (DMD) in semi-magic nuclei starting from the free NN potential. The PC correction δΣ^PC to the mass operator Σ is found in g _L ²-approximation, g _L being the vertex of creating the L-phonon. The tadpole term of the operator δΣ^PC is taken into account. The method is based on a direct, without any use of the perturbation theory, solution of the Dyson equation with the mass operator Σ(ε) = Σ₀ + δΣ^PC(ε) for finding the single-particle energies and Z-factors. In its turn, they are used as an input for finding different PC corrections to the DMD values. Results for a chain of even semi-magic nuclei ^200?206Pb show that the inclusion of the PC corrections makes agreement with the experimental data significantly better.     

Effects of the spin–orbit coupling on the vacancy-induced magnetism on the honeycomb lattice

The local magnetism induced by vacancies in the presence of the spin–orbit interaction is investigated based on the half-filled Kane–Mele–Hubbard model on the honeycomb lattice. Using a self-consistent mean-field theory, we find that the spin–orbit coupling will enhance the localization of the spin moments near a single vacancy. We further study the magnetic structures along the zigzag edges formed by a chain of vacancies. We find that the spin–orbit coupling tends to suppress the counter-polarized ferrimagnetic order on the upper and lower edges, because of the open of the spin–orbit gap. As a result, in the case of the balance number of sublattices, it will suppress completely this kind of ferrimagnetic order. But, for the imbalance case, a ferrimagnetic order along both edges exists because additional zero modes will not be affected by the spin–orbit coupling.     

A systematic study on the binding energy of Λ hypernuclei

We calculate the binding energy per baryon of the Λ hypernuclei systematically, using the relativistic mean field theory (RMF) in a static frame. Some similar properties are found for most of the Λ hypernuclei confirmed by experiments. The data show that a Λ hypernucleus will be more stable if it is made by adding a Λ hyperon to a stable normal nuclear core, or by replacing a neutron by a Λ hyperon to a stable normal nuclear core. According to our calculations, the existence of some new Λ hypernuclei are predicted under the frame of RMF.     

Features of carbon-carbon interactions at a momentum of 4.2 GeV/c per nucleon that are accompanied by the production of Λ hyperons and K S 0 mesons versus the degree of nuclei collision centrality

Experiemntal data obtained by using the 2-m propane bubble chamber of the Joint Institute for Nuclear Research (JINR, Dubna) are used to study the effect collision centrality on the spectra of Λ hyperons and K _S ⁰ mesons produced in carbon-carbon interactions at 4.2 A GeV/c. The multiplicity of participant protons having momenta in excess of 300 MeV/c is taken to be a measure of collision centrality. The features of pions and protons accompanying strange-particle production are also presented. The experimental data in question are compared with the prediction of a modified version of the FRITIOF model. It is shown that strange particles are predominantly produced in central and semicentral collisions. The average kinematical features of K _S ⁰ mesons are found to be indepedent of collision centrality. At the same time, the average transverse momentum of Λ hyperons and the average value of their emission angle increase slowly with increasing degree of collision centrality. The anisotropy of the angular distributions of both Λ hypersons and K _S/0 mesons in the c.m. frame of nucleon-nucleon collisions decreases with increasing collision centrality. The average transverse momentum of K _S ⁰ mesons is approximately 1.6 times higher than the average transverse momentum of π ^? mesons.     

Effects of thermal fluctuations on the Kerr–Newman–NUT–AdS black hole

This paper is devoted to studying the impact of thermal fluctuations on thermodynamics of rotating as well as charged anti-de Sitter black holes with the Newman–Unti–Tamburino(NUT)parameter. To this end, we derive the analytic expression of thermodynamic variables, namely the Hawking temperature, volume, angular velocity, and entropy within the limits of extended phase space. These variables meet the first law of thermodynamics as well as the Smarr relation in the presence of new NUT charge. To analyze the effects of quantum fluctuations, we derive the exact expression of corrected entropy, which yields modification in other thermodynamical equations of state. The local stability and phase transition of the considered black hole are also examined through specific heat. It is found that the NUT parameter increases the stability of small black holes, while the logarithmic corrections induce instability in the system.     

Effects of configuration mixing on predominantlyf 7 2/n states inA=52–55 nuclei

Extensive shell-model calculations are performed onf _7/2 nuclei withA=52–55. The model space includes the excitation of onef _7/2 nucleon to thep _3/2,f _5/2 orp _1/2 orbit. Spectra, electromagnetic properties (M1,E2,E4) andβ-decay are studied. It is found that almost all observables calculated in the enlarged space are in much better agreement with experiment than those of the simplef ₇ ^2/n space.     

Influence of proton-skin thickness on the α decays of heavy nuclei

We investigate the effect of proton-skin thickness on the α decay process. We consider 188 neutrondeficient nuclei belonging to the isotopic chains from Te(Z = 52) to Pb(Z = 82). The calculations of the half-life are carried out in the framework of the preformed cluster model, with the Wentzel-Kramers-Brillouin penetration probability and assault frequency. It is shown that the proton-skin thickness(?p) of the daughter nucleus gives rise to a total α-daughter nucleus interaction potential of relatively wide deep internal pocket and a thinner Coulomb barrier of less height. This increases the penetration probability but decreases the assault frequency. The overall impact of the proton-skin thickness appears as a decrease in the decay half-life. The proton-skin thickness decreases the stability of the nucleus. The half-lives of the proton-skinned isotopes along the isotopic chain decrease exponentially with increasing the proton-skin thickness, whereas the Qα-value increases with ?p. α-decay manifests itself as the second favorite decay mode of neutron-deficient nuclei, next to the β+-decay and before proton-decay. It is indicated as main, competing, and minor decay mode, at 21%, 7%, and 57%, respectively, of the investigated nuclei.