arXiv subjects
Publications and source records attributed to Rimantas Lazauskas.
Time reversal invariance violating parity conserving effects for low energy elastic neutron deuteron scattering are calculated for meson exchange and EFT-type of potentials in a Distorted Wave Born Approximation, using realistic hadronic wave functions, obtained by solving three-body Faddeev equations in configuration space.
Time reversal invariance violating parity conserving (TVPC) effects are calculated for elastic proton deuteron scattering with proton energies up to $2~$MeV. Distorted Wave Born Approximation is employed to estimate TVPC matrix elements, based on hadronic wave functions, obtained by solving three-body Faddeev-Merkuriev equations in configuration space with realistic potentials.
A formalism based on the complex-scaling method is presented to solve the few particle scattering problem in configuration space using bound state techniques with trivial boundary conditions. Several applications to A=3,4 systems are presented to demonstrate the efficiency of the method in computing elastic as well as break-up reactions with Hamiltonians including both short and long-range interaction.
Nuclear electric dipole moments of $^{3}He$ and $^{3}H$ are calculated using Time Reversal Invariance Violating (TRIV) potentials based on the meson exchange theory, as well as the ones derived by using pionless and pionful effective field theories, with nuclear wave functions obtained by solving Faddeev equations in configuration space for the complete Hamiltonians comprising both TRIV and realistic strong interactions. The obtained results are compared with the previous calculations of $^{3}He$ EDM and with time reversal invariance violating effects in neutron-deuteron scattering.
We propose applications of Radioactive Ion Beam facilities to investigate physics beyond the Standard Model. In particular, we focus on the possible measurement of coherent neutrino-nucleus scattering and on a search for sterile neutrinos, by means of a low energy beta-beam with a Lorentz boost factor $γ\approx 1$. In the considered setup the collected radioactive ions are sent inside a 4$π$ detector. For the first application we provide the number of events associated with neutrino-nucleus coherent scattering, when the detector is filled in with a noble liquid. For the sterile search we consider that the spherical detector is filled in with a liquid scintillator, and that the neutrino detection channel is inverse-beta decay. We provide the exclusion curves for the sterile neutrino mixing parameters, based upon the 3+1 formalism, depending upon the achievable ion intensity. Our results are obtained both from total rates, and including spectral information with binning in energy and in distance. The proposed experiment represents a possible alternative to clarify the current anomalies observed in neutrino experiments.
Parity violating (PV) effects in neutron-deuteron radiative capture are studied using Desplanques, Donoghue, and Holstein (DDH) and effective field theory weak potentials. The values of PV effects are calculated using wave functions, obtained by solving three-body Faddeev equations in configuration space for phenomenological strong potentials. The relations between physical observables and low-energy constants are presented, and dependencies of the calculated PV effects on strong and weak potentials are discussed. The presented analysis shows the possible reason for the existing discrepancy in PV nuclear data analysis using the DDH approach and reveals a new opportunity to study short range interactions in nuclei.
We present some recent applications of the Faddeev--Yakubovsky equations in describing atomic bound and scattering problems. We consider the scattering of a charged particle $X$ by atomic hydrogen with special interest in $X=p,e^{\pm}$, systems of cold bosonic molecules and the bound and scattering properties of N=3 and N=4 atomic $^4$He multimers.
Time reversal invariance violating (TRIV) effects for low energy elastic neutron deuteron scattering are calculated for meson exchange and EFT-type of TRIV potentials in a Distorted Wave Born Approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The relation between TRIV and parity violating observables are discussed.
Formalism based on complex-scaling method is developed for solving the few particle scattering problem by employing only trivial boundary conditions. Several applications are presented proving efficiency of the method in describing elastic and three-body break-up reactions for Hamiltonians which may include both short and long-range interaction.
The cross section for radiative thermal neutron capture on ${}^{3}He$ ($\He3 +n \to \He4 +γ$; known as the $hen$ reaction) is calculated based on heavy-baryon chiral perturbation theory. The relevant M1 operators are derived up to next-to-next-to-next-to-leading order (N${}^3$LO). The initial and final nuclear wave functions are obtained from the rigorous Faddeev-Yakubovski equations for five sets of realistic nuclear interactions. Up to N${}^3$LO, the M1 operators contain two low-energy constants, which appear as the coefficients of non-derivative two-nucleon contact terms. After determining these two constants using the experimental values of the magnetic moments of the triton and ${}^3 He$, we carry out a parameter-free calculation of the $hen$ cross section. The results are in good agreement with the data.
Parity violating effects for low energy elastic neutron deuteron scattering are calculated for DDH and EFT-type of weak potentials in a Distorted Wave Born Approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The results of relation between physical observables and low energy constants can be used to fix low energy constants from experiments. Potential model dependencies of parity violating effects are discussed.
Elastic proton scattering on ${}^{3}{H}$ nucleus is studied inbetween p-% ${}^{3}{H}$ and n-${}^{3}{He}$ thresholds, in the energy region where $α$-particles first excited state is inbeded in the continuum. For this aim Faddeev-Yakubovski equations are solved in configuration space, fully considering effects due to the isospin breaking as well as rigorously treating Coulomb interaction. Different realistic nuclear Hamiltonians are tested, elucidating open problems in nuclear interaction description.
We explore the possibility to observe the effects of electron neutrinos from past galactic supernovae, through a geochemical measurement of the amount of Technetium 97 produced by neutrino-induced reactions in a Molybdenum ore. The calculations we present take into account the recent advances in our knowledge of neutrino interactions, of neutrino oscillations inside a supernova, of the solar neutrino flux at Earth and of possible failed supernovae. The predicted Technetium 97 abundance is of the order of 10^7 atoms per 10 kilotons of ore, which is close to the current geochemical experimental sensitivity. Of this, 10-20% is from supernovae. Considering the comparable size of uncertainties, more precision in the modeling of neutrino fluxes as well as of neutrino cross sections is required for a meaningful measurement.
M1 properties, comprising magnetic moments and radiative capture of thermal neutron observables, are studied in two- and three-nucleon systems. We utilize meson exchange current derived up to N$^3$LO using heavy baryon chiral perturbation theory a la Weinberg. Calculations have been performed for several qualitatively different realistic nuclear Hamiltonians, which permits us to analyze model dependence of our results. Our results are found to be strongly correlated with the effective range parameters such as binding energies and the scattering lengths. Taking into account such correlation, the results are in good agreement with the experimental data with small model-dependence.
In this article an efficient method to calculate the matrix elements of three-nucleon force is presented. The new method is improved version of partial-wave decomposition presented in Few-Body Syst. 22 (1997) 107, which simplifies expression to be evaluated and permits to reduce computational effort as much as six times. Proposed method naturally applies to Faddeev-type calculations but also can be used by any method relaying on partial-wave decomposition.
The magnetic moments of ${}^2{H}$, ${}^3{He}$ and ${}^3{H}$ as well as the thermal neutron capture rate on the proton are calculated using heavy baryon chiral perturbation theory {\it à la} Weinberg. The M1 operators have been derived up to {N$^3$LO}. The nuclear matrix elements are evaluated with the use of wave functions obtained by carrying out variational Monte Carlo calculations for a realistic nuclear Hamiltonian involving high-precision phenomenological potentials like Argonne Av18 and Urbana IX tri-nucleon interactions. We discuss the potential- and cutoff-dependence of the results.
The Faddeev-Yakubovski equations are solved in configuration space for the $% α$-particle and n-$^3$H continuum states. We test the ability of nonlocal nucleon-nucleon interaction models to describe 3N and 4N systems.
A new state of the H$_2^+$ molecular ion with binding energy of 1.09$\times10^{-9}$ a.u. below the first dissociation limit is predicted, using highly accurate numerical nonrelativistic quantum calculations. It is the first L=0 excited state, antisymmetric with respect to the exchange of the two protons. It manifests itself as a huge p-H scattering length of $a=750\pm 5$ Bohr radii.