Breached pairing in trapped three-color atomic Fermi gases

We introduce an exactly solvable model for trapped three-color atom gases. Applications to a cigar-shaped trapped cold fermions reveal a complex structure of breached pairing phases. We find two competing superfluid phases at weak and intermediate couplings, each one with two color pair condensates, that can be distinguished from density profile measurements.Comment: 4 pages, 5 figure

Exotic behavior and crystal structures of calcium under pressure

Experimental studies established that calcium undergoes several counterintuitive transitions under pressure: fcc \rightarrow bcc \rightarrow simple cubic \rightarrow Ca-IV \rightarrow Ca-V, and becomes a good superconductor in the simple cubic and higher-pressure phases. Here, using ab initio evolutionary simulations, we explore the behavior of Ca under pressure and find a number of new phases. Our structural sequence differs from the traditional picture for Ca, but is similar to that for Sr. The {\beta}-tin (I41/amd) structure, rather than simple cubic, is predicted to be the theoretical ground state at 0 K and 33-71 GPa. This structure can be represented as a large distortion of the simple cubic structure, just as the higher-pressure phases stable between 71 and 134 GPa. The structure of Ca-V, stable above 134 GPa, is a complex host-guest structure. According to our calculations, the predicted phases are superconductors with Tc increasing under pressure and reaching ~20 K at 120 GPa, in good agreement with experiment

Anharmonic phonon spectra of PbTe and SnTe in the self-consistent harmonic approximation

At room temperature, PbTe and SnTe are efficient thermoelectrics with a cubic structure. At low temperature, SnTe undergoes a ferroelectric transition with a critical temperature strongly dependent on the hole concentration, while PbTe is an incipient ferroelectric. By using the stochastic self-consistent harmonic approximation, we investigate the anharmonic phonon spectra and the occurrence of a ferroelectric transition in both systems. We find that vibrational spectra strongly depends on the approximation used for the exchange-correlation kernel in density functional theory. If gradient corrections and the theoretical volume are employed, then the calculation of the free energy Hessian leads to phonon spectra in good agreement with experimental data for both systems. In PbTe, we reproduce the transverse optical mode phonon satellite detected in inelastic neutron scattering and the crossing between the transverse optical and the longitudinal acoustic modes along the $\Gamma$X direction. In the case of SnTe, we describe the occurrence of a ferroelectric transition from the high temperature Fm$\overline{3}$m structure to the low temperature R3m one.Comment: 12 pages, 15 Picture

Exact solution of the spin-isospin proton-neutron pairing Hamiltonian

The exact solution of proton-neutron isoscalar-isovector (T=0,1) pairing Hamiltonian with non-degenerate single-particle orbits and equal pairing strengths (g_{T=1}= g_{T=0}) is presented for the first time. The Hamiltonian is a particular case of a family of integrable SO(8) Richardson-Gaudin (RG) models. The exact solution of the T=0,1 pairing Hamiltonian is reduced to a problem of 4 sets of coupled non linear equations that determine the spectral parameters of the complete set of eigenstates. The microscopic structure of individual eigenstates is analyzed in terms of evolution of the spectral parameters in the complex plane for system of A=80 nucleons. The spectroscopic trends of the exact solutions are discussed in terms of generalized rotations in isospace.Comment: 4 pages, 2 figure

Aggregation effects in proton collisions with water dimers

Charge transfer cross sections in proton collisions with water dimers are calculated using an ab initio method based on molecular orbitals of the system. Results are compared with their counterpart in proton-water collisions to gauge the importance of intermolecular interactions in the cross sectionsThis work has been supported by the project ENE2007-62934 of the Secretaría de Estado de Investigación, Desarrollo e Innovación (Spain). Allocation of computational time at the CCC of the Universidad Autónoma de Madrid is gratefully acknowledge

Mapping quantitative trait Loci associated with graft (In)compatibility in apricot (Prunus armeniaca L.)

Graft incompatibility (GI) between the most popular Prunus rootstocks and apricot cultivars is one of the major problems for rootstock usage and improvement. Failure in producing long-leaving healthy grafts greatly affects the range of available Prunus rootstocks for apricot cultivation. Despite recent advances related to the molecular mechanisms of a graft-union formation between rootstock and scion, information on genetic control of this trait in woody plants is essentially missing because of a lack of hybrid crosses, segregating for the trait. In this study, we have employed the next-generation sequencing technology to generate the single-nucleotide polymorphism (SNP) markers and construct parental linkage maps for an apricot F1 population “Moniqui (Mo)” × “Paviot (Pa)” segregating for ability to form successful grafts with universal Prunus rootstock “Marianna 2624”. To localize genomic regions associated with this trait, we genotyped 138 individuals from the “Mo × Pa” cross and constructed medium-saturated genetic maps. The female “Mo” and male “Pa” maps were composed of 557 and 501 SNPs and organized in eight linkage groups that covered 780.2 and 690.4 cM of genetic distance, respectively. Parental maps were aligned to the Prunus persica v2.0 genome and revealed a high colinearity with the Prunus reference map. Two-year phenotypic data for characters associated with unsuccessful grafting such as necrotic line (NL), bark and wood discontinuities (BD and WD), and an overall estimate of graft (in)compatibility (GI) were collected for mapping quantitative trait loci (QTLs) on both parental maps. On the map of the graft-compatible parent “Pa”, two genomic regions on LG5 (44.9–60.8 cM) and LG8 (33.2–39.2 cM) were associated with graft (in)compatibility characters at different significance level, depending on phenotypic dataset. Of these, the LG8 QTL interval was most consistent between the years and supported by two significant and two putative QTLs. To our best knowledge, this is the first report on QTLs for graft (in)compatibility in woody plants. Results of this work will provide a valuable genomic resource for apricot breeding programs and facilitate future efforts focused on candidate genes discovery for graft (in)compatibility in apricot and other Prunus species

Comment on “Classical description of H(1s) andH∗(n=2) for cross-section calculations relevant to charge-exchange diagnostics”

Cariatore et al. [Phys. Rev. A 91, 042709 (2015)] have introduced a modification of the classical trajectory Monte Carlo (CTMC) method, specially conceived to provide an accurate representation of charge-exchange processes between highly charged ions and H(1s), H ∗ (n=2) . We point out that this new CTMC treatment is based on nonstable initial distributions for H ∗ (n=2) targets and an improper description of the H(1s) targetThis work has been partially supported by Ministerio de Economía y Competitividad (Spain) (Projects No. ENE2011-28200 and No. ENE2014-5432-R

Application of a grid numerical method to calculate state-selective cross sections for electron capture in Be4+ + H(1s) collisions

Charge-transfer n partial cross sections have been calculated for collisions of Be4+ with H(1s) by means of a versatile lattice method that is applicable in a wide energy range (between 1 and 500 keV/u). The cross sections, which include up to the high-lying n = 8 level, are compared to existing semiclassical calculations in order to quantify the accuracy of the results. The reliability of the lattice method at high impact energies is confirmed by comparison with classical trajectory Monte Carlo calculations. It is found that the n partial cross sections larger than 10−18 cm2, calculated using the lattice method, agree with differences smaller than 15% with those from the method considered the most accurate at each energy. The calculation yields as well accurate total electron capture cross sections, which are studied in detail at E = 100 keV/u to obtain a converged valueThis work has been partially supported by the Ministerio de Economía y Competitividad (Spain) (Projects No. ENE2011-28200 and No. ENE2014-52432-R). with financial support from the Red Española de Supercomputación (RES; Grants No. FI-2012-2-0016, ´ No. FI-2013-1-0020, and No. FI2013-2-0006

Exactly-solvable models of proton and neutron interacting bosons

We describe a class of exactly-solvable models of interacting bosons based on the algebra SO(3,2). Each copy of the algebra represents a system of neutron and proton bosons in a given bosonic level interacting via a pairing interaction. The model that includes s and d bosons is a specific realization of the IBM2, restricted to the transition regime between vibrational and gamma-soft nuclei. By including additional copies of the algebra, we can generate proton-neutron boson models involving other boson degrees of freedom, while still maintaining exact solvability. In each of these models, we can study not only the states of maximal symmetry, but also those of mixed symmetry, albeit still in the vibrational to gamma-soft transition regime. Furthermore, in each of these models we can study some features of F-spin symmetry breaking. We report systematic calculations as a function of the pairing strength for models based on s, d, and g bosons and on s, d, and f bosons. The formalism of exactly-solvable models based on the SO(3,2) algebra is not limited to systems of proton and neutron bosons, however, but can also be applied to other scenarios that involve two species of interacting bosons.Comment: 8 pages, 3 figures. Submitted to Phys.Rev.

State-selective electron capture in collisions of ground and metastable N2+ ions with H(1s)

9 págs.; 12 figs.; 1 tab.; PACS number(s): 34.70.1e, 34.10.1xA calculation of the electron capture (EC) cross sections for collisions of metastable and ground states of nitrogen2+ ions with H(1s) was presented. The double translational energy spectroscopy technique facilitated the energy change spectrum in EC to be measured for an incident pure beam of ground state ions. It was found that the nuclear wave functions were derived by solving numerically the system of differential equations. It was observed that for impact energies 1 KeV, the impact parameter method was employed, where the nuclei followed straightline trajectories with constant relative velocity V and impact parameter b (R=b+vt). ©2004 The American Physical SocietyI.R. is grateful to the Spanish MCyT for a “Contrato Ramón y Cajal.” This work has been partially supported by DGICYT Projects No. BFM2000-0025 and FTN2000-0911.Peer Reviewe