Lorentz violation in neutron and allowed nuclear beta decay

We explore the possibility that the weak interaction violates Lorentz, and in particular rotational, invariance in neutron and allowed nuclear beta decay. A broad class of Lorentz-violating effects is considered, in which the standard propagator of the W-boson acquires an additional Lorentz-violating tensor. The general decay rate for allowed beta decay that incorporates such a modified propagator is derived. The resulting Lorentz-violating signals are discussed for the different types of beta-decay transitions, Fermi, Gamow-Teller, and mixed. We study the implications of our formalism for dedicated beta-decay experiments. We give a short overview of the few relevant experiments that have been performed or are ongoing.Comment: 23 pages; added reference

The Status of the Pion-Nucleon Coupling Constant

A review is given of the various determinations of the different piNN coupling constants in analyses of the low-energy pp, np, pbarp, and pi-p scattering data. The most accurate determinations are in the energy-dependent partial-wave analyses of the NN data. The recommended value is f^2 = 0.075 . A recent determination of f^2 by the Uppsala group from backward np cross sections is shown to be model dependent and inaccurate, and therefore completely uninteresting. We also argue that an accurate determination of f^2 using pp forward dispersion relations is not a realistic option.Comment: 19 pages, latex2e with a4wide.sty, more information is available at http://NN-OnLine.sci.kun.nl . Invited talk at FBXV, Groningen, The Netherlands, July 22-26, 1997. Invited talk at MENU97, Vancouver, B.C., Canada, July 28 - August 1, 199

Nuclear beta decay with Lorentz violation

We consider the possibility of Lorentz-invariance violation in weak-decay processes. We present a general approach that entails modifying the W-boson propagator by adding a Lorentz-violating tensor to it. We describe the effects of Lorentz violation on nuclear beta decay in this scenario. In particular we show the expression for a first-forbidden transition with a spin change of two. Using data from an old experiment on the rotational invariance of yttrium-90, we derive several bounds on the Lorentz-violating parameters of the order of 10^(-6)-10^(-8).Comment: 4 pages; presented at the Sixth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 17-21, 2013; Added reference

Partial-Wave Analyses of all Proton-Proton and Neutron-Proton Data Below 500 MeV

In 1993 the Nijmegen group published the results of energy-dependent partial-wave analyses (PWAs) of the nucleon-nucleon (NN) scattering data for laboratory kinetic energies below Tlab=350 MeV (PWA93). In this talk some general aspects, but also the newest developments on the Nijmegen NN PWAs are reported. We have almost finished a new energy-dependent PWA and will discuss some typical aspects of this new PWA; where it differs from PWA93, but also what future developments might be, or should be.Comment: Presentation at the 19th European Conference on Few-Body Problems in Physics, Groningen, The Netherlands, 23-27 August 2004. 4 pages REVTeX4, no figure

Zero sound in a single component fermion - Bose Einstein Condensate mixture

The resonant dynamics of mediated interactions supports zero-sound in a cold atom degenerate mixture of a single component fermion gas and a Bose-Einstein condensate (BEC). We characterize the onset of instability in the phase separation of an unstable mixture and we find a rich collective mode structure for stable mixtures with one undamped mode that exhibits an avoided crossing and a Landau-damped mode that terminates.Comment: 4 pages, 2 figure

Deuteron Magnetic Quadrupole Moment From Chiral Effective Field Theory

We calculate the magnetic quadrupole moment (MQM) of the deuteron at leading order in the systematic expansion provided by chiral effective field theory. We take into account parity and time-reversal violation which, at the quark-gluon level, results from the QCD vacuum angle and dimension-six operators that originate from physics beyond the Standard Model. We show that the deuteron MQM can be expressed in terms of five low-energy constants that appear in the parity- and time-reversal-violating nuclear potential and electromagnetic current, four of which also contribute to the electric dipole moments of light nuclei. We conclude that the deuteron MQM has an enhanced sensitivity to the QCD vacuum angle and that its measurement would be complementary to the proposed measurements of light-nuclear EDMs

Exploration of Lorentz violation in neutral-kaon decay

The KLOE collaboration recently reported bounds on the directional dependence of the lifetime of the short-lived neutral kaon $K^0_S$ with respect to the dipole anisotropy of the cosmic microwave background. We interpret their results in an effective field theory framework developed to probe the violation of Lorentz invariance in the weak interaction and previously applied to semileptonic processes, in particular $\beta$ decay. In this approach a general Lorentz-violating tensor $\chi^{\mu\nu}$ is added to the standard propagator of the $W$ boson. We perform an exploratory study of the prospects to search for Lorentz violation in nonleptonic decays. For the kaon, we find that the sensitivity to Lorentz violation is limited by the velocity of the kaons and by the extent to which hadronic effects can be calculated. In a simple model we derive the $K^0_S$ decay rate and calculate the asymmetry for the lifetime. Using the KLOE data, limits on the values of $\chi^{\mu\nu}$ are determined.Comment: accepted for publication in Physics Letters

Comment on piNN Coupling from High Precision np Charge Exchange at 162 MeV

In this updated and expanded version of our delayed Comment we show that the np backward cross section, as presented by the Uppsala group, is seriously flawed (more than 25 sd.). The main reason is the incorrect normalization of the data. We show also that their extrapolation method, used to determine the charged piNN coupling constant, is a factor of about 10 less accurate than claimed by Ericson et al. The large extrapolation error makes the determination of the coupling constant by the Uppsala group totally uninteresting.Comment: 5 pages, latex2e with a4wide.sty. This is an updated and extended version of the Comment published in Phys. Rev. Letters 81, 5253 (1998

Schiff Theorem and the Electric Dipole Moments of Hydrogen-Like Atoms

The Schiff theorem is revisited in this work and the residual $P$- and $T$-odd electron--nucleus interaction, after the shielding takes effect, is completely specified. An application is made to the electric dipole moments of hydrogen-like atoms, whose qualitative features and systematics have important implication for realistic paramagnetic atoms.Comment: 3 pages. Contribution to PANIC05, Particles and Nuclei International Conference, Santa Fe, New Mexico, Oct. 24-28, 200