Nuclear Schiff moment and soft vibrational modes

The atomic electric dipole moment (EDM) currently searched by a number of experimental groups requires that both parity and time-reversal invariance be violated. According to current theoretical understanding, the EDM is induced by the nuclear Schiff moment. The enhancement of the Schiff moment by the combination of static quadrupole and octupole deformation was predicted earlier. Here we study a further idea of the possible enhancement in the absence of static deformation but in a nuclear system with soft collective vibrations of two types. Both analytical approximation and numerical solution of the simplified problem confirm the presence of the enhancement. We discuss related aspects of nuclear structure which should be studied beyond mean-field and random phase approximations.Comment: 14 pages, 4 figure

Thermodynamics of pairing in mesoscopic systems

Using numerical and analytical methods implemented for different models we conduct a systematic study of thermodynamic properties of pairing correlation in mesoscopic nuclear systems. Various quantities are calculated and analyzed using the exact solution of pairing. An in-depth comparison of canonical, grand canonical, and microcanonical ensemble is conducted. The nature of the pairing phase transition in a small system is of a particular interest. We discuss the onset of discontinuity in the thermodynamic variables, fluctuations, and evolution of zeros of the canonical and grand canonical partition functions in the complex plane. The behavior of the Invariant Correlational Entropy is also studied in the transitional region of interest. The change in the character of the phase transition due to the presence of magnetic field is discussed along with studies of superconducting thermodynamics.Comment: 19 pages, 24 figure

Constraints on Electroweak Contact Interactions from LEP and Tevatron Data

A complete set of dimension-6 effective contact interactions involving Higgs, gauge bosons and quarks is studied. Limits on the coefficients of these new operators are obtained from the experimental values of the $Z$ and $W$ gauge bosons widths.Comment: 14 pages, ReVTe

The dependence of nonadiabatic couplings on the origin of electron coordinates

It is shown both analytically and numerically for a number of examples that both radial and rotational nonadiabatic couplings within the standard adiabatic approach depend on the origin of the light-particle coordinates and the ambiguity in the nonadiabatic couplings does not lead to ambiguity in the coupled channel equations. The examples considered are the nH, nD, npμ−npμ− quasimolecules, for which the nonadiabatic couplings can be calculated analytically, and the HeH molecule, for which ab initio calculations are carried out. Analytical formulas for couplings calculated with the shifted origin are derived. The coupled equations take their simplest form in Jacobi coordinates for which many nonadiabatic couplings are nonzero, even for such noninteracting systems as nH, nD, and npμ−.npμ−. These couplings are a fundamental feature of the adiabatic approach.Physic

Resonant nuclear transition in the d-mu-Li6 muonic molecule

The reaction rate of the nuclear fusion d+Li6 ----> Be8*(2+,0) is estimated in the case where the nuclei are confined to each other by a muon. For the description of nuclear transitions, a method which is analogous to the Linear Combination of Atomic Orbitals has been used. Using the complex coordinate rotation method, we found that a molecular d-mu-Li6 state exists with energy (-20.3084-i0.0066) eV and |\Psi_{m}(0)|=0.44x10^{-7} fm^-3/2. The nuclear wave functions needed, were constructed in the form of antisymmetrized products of harmonic-oscillator functions for the three-cluster approximation, (dd\alpha), to the five-body (NNNN\alpha) problem. It was found that the reaction rate \lambda is strongly dependent on the energy gap between the d-Li6 threshold and the energy of the final Be8^* resonant state. The value of \lambda obtained by averaging over the width of this resonance, is 0.183x10^10 sec^{-1}.Comment: REVTEX, 63K, no postscripts, 21 pages, submitted to Phys.Rev.

Torsion Constraints in the Randall--Sundrum Scenario

Torsion appears due to fermions coupled to gravity and leads to the strongest particle physics bounds on flat extra dimensions. In this work, we consider torsion constraints in the case of a warped extra dimension with brane and bulk fermions. From current data we obtain a 3-sigma bound on the TeV--brane mass scale scale \Lambda_\pi > 2.2 (10) TeV for the AdS curvature k=1 (0.01) in (reduced) Planck units. If Dirac or light sterile neutrinos reside on the brane, the bound increases to 17 (78) TeV.Comment: typos corrected, matches the Phys. Rev. D versio

Flavour SU(3) Symmetry in Charmless B Decays

QCD sum rules are used to estimate the flavour SU(3)-symmetry violation in two-body B decays to pions and kaons. In the factorizable amplitudes the SU(3)-violation manifests itself in the ratio of the decay constants f_K/f_pi and in the differences between the B->K, B_s->K and B->pi form factors. These effects are calculated from the QCD two-point and light-cone sum rules, respectively, in terms of the strange quark mass and the ratio of the strange and nonstrange quark-condensate densities. Importantly, QCD sum rules predict that SU(3) breaking in the heavy-to-light form factors can be substantial and does not vanish in the heavy-quark mass limit. Furthermore, we investigate the strange-quark mass dependence of nonfactorizable effects in the B->K pi decay amplitudes. Taking into account these effects we estimate the accuracy of several SU(3)-symmetry relations between charmless B-decay amplitudes.Comment: Two references added, version to be published in Phys.Rev.D, 21 pages, 12 postscript figure

Predictions on B→πlˉνlB \to \pi \bar{l} \nu_l, D→πlˉνlD \to \pi \bar{l} \nu_l and D→KlˉνlD\to K \bar{l} \nu_l from QCD Light-Cone Sum Rules

The $f^+$ form factors of the $B\to \pi$, $D\to \pi$ and $D\to K$ transitions are calculated from QCD light-cone sum rules (LCSR) and used to predict the widths and differential distributions of the exclusive semileptonic decays $B\to \pi \bar{l}\nu_l$, $D \to\pi \bar{l}\nu_l$ and $D \to K \bar{l}\nu_l$, where $l=e,\mu$. The current theoretical uncertainties are estimated. The LCSR results are found to agree with the results of lattice QCD calculations and with experimental data on exclusive semileptonic D decays. Comparison of the LCSR prediction on $B\to \pi \bar{l} \nu_l$ with the CLEO measurement yields a value of |V_{ub}| in agreement with other determinations.Comment: 24 pages, 12 figures, Latex, epsfig, some additional remarks on the two-pole parameterization, prediction on the $B\to K$ form factor added, version to appear in Phys. Rev.

Hydrodynamic Modes in a Trapped Strongly Interacting Fermi Gases of Atoms

The zero-temperature properties of a dilute two-component Fermi gas in the BCS-BEC crossover are investigated. On the basis of a generalization of the variational Schwinger method, we construct approximate semi-analytical formulae for collective frequencies of the radial and the axial breathing modes of the Fermi gas under harmonic confinement in the framework of the hydrodynamic theory. It is shown that the method gives nearly exact solutions.Comment: 11 page