18094401
Solar-neutrino reactions on deuteron in effective field theory
Abstract The cross sections for low-energy neutrino–deuteron reactions are calculated within heavy-baryon chiral perturbation theory employing a cut-off regularization scheme. The transition operators are derived up to next-to-next-to-next-to-leading order in the Weinberg counting rules, while the nuclear matrix elements are evaluated using the wave functions generated by a high-quality phenomenological NN potential. With the adoption of the axial-current-four-nucleon coupling constant fixed from the tritium beta decay data, our calculation is free from unknown low-energy constants. Our results exhibit a high degree of stability against different choices of the cutoff parameter, a feature which indicates that, apart from radiative corrections, the uncertainties in the calculated cross sections are less than 1%.
14614656
Radiative muon capture in heavy baryon chiral perturbation theory
Abstract The radiative muon capture (RMC) on a proton is analyzed by means of heavy baryon chiral perturbation theory. The emitted photon energy spectrum is calculated and compared with the experimental data by taking the spin sum on the muonic atom states. We find that one-loop order corrections to the tree order amplitude modify the photon spectrum by less than five percent. This calculation supports that the theory is under a quantitative control as far as the chiral perturbation expansion is concerned and indicates that the discrepancy between the pseudo-scalar coupling constant required by the RMC experiment and the one deduced from ordinary muon capture, the value of which is also supported by chiral perturbation calculations, will remain unexplained from the theoretical side.
16520608
Parity-violating nucleon-nucleon interaction from different approaches
Two-pion exchange parity-violating nucleon-nucleon interactions from recent effective field theories and earlier fully covariant approaches are investigated. The potentials are compared with the goal of obtaining better insight into the role of low-energy constants appearing in the effective field theory approach and its convergence in terms of a perturbative series. The results are illustrated by considering the longitudinal asymmetry of polarized protons scattering off protons, p-vector+p{yields}p+p, and the asymmetry of the photon emission in radiative capture of polarized neutrons by protons, n-vector+p{yields}d+{gamma}.
55936228
Effective field theory of 3He
We examine the effects of the long range Coulomb force on the three-body contact interaction in a pionless effective theory of 3He. The corresponding interaction in 3H exhibits limit-cycle behavior and we show that this is not altered by the 1/r singularity of the potential.
639846
Neutrino-deuteron reactions at solar neutrino energies
Abstract In interpreting the SNO experiments, accurate estimates of the νd reaction cross sections are of great importance. We improve the previous estimates of our group by updating some of its inputs and by taking into account the results of a recent effective-field-theoretical calculation. The new cross sections are slightly (∼1%) larger than the previously reported values. It is shown to be reasonable to assign 1% uncertainty to the νd cross sections reported here; this error estimate does not include radiative corrections, for which we refer to the literature.
118449544
Spin Observables in the Two-Nucleon Capture and Dissociation Processes at Low Energies
Spin observables in radiative neutron capture on a proton and its inverse process, photodisintegration of the deuteron are calculated using a pionless effective field theory with di-baryon fields. Good agreement with the results of existing standard nuclear physics approach (SNPA) is obtained at very low energies. As energy increases, however, the discrepancy between the effective field theory and the SNPA becomes substantial. We discuss the origin of the difference.
1356531
Nonlinear evolution of anisotropic cosmological power.
There has been growing interest in the possibility of testing more precisely the assumption of statistical isotropy of primordial density perturbations. If it is to be tested with galaxy surveys at distance scales < or = 10 Mpc, then nonlinear evolution of anisotropic power must be understood. To this end, we calculate the angular dependence of the power spectrum to third order in perturbation theory for a primordial power spectrum with a quadrupole dependence on the wave vector direction. Our results suggest that primordial power anisotropies will be suppressed by < or = 7% in the quasilinear regime. We also show that the skewness in the statistically anisotropic theory differs by no more than 1% from that in the isotropic theory.
34444060
Asymmetric neutrino emission due to neutrino-nucleon scatterings in supernova magnetic fields
We derive the cross section of neutrino-nucleon scatterings in supernova magnetic fields, including weak-magnetism and recoil corrections. Since the weak interaction violates the parity, the scattering cross section asymmetrically depends on the directions of the neutrino momenta to the magnetic field; the origin of pulsar kicks may be explained by the mechanism. An asymmetric neutrino emission (a drift flux) due to neutrino-nucleon scatterings is absent at the leading level of $\mathcal O(\mu_BB/T)$, where $\mu_B$ is the nucleon magneton, $B$ is the magnetic field strength, and $T$ is the matter temperature at a neutrinosphere. This is because at this level the drift flux of the neutrinos are exactly canceled by that of the antineutrinos. Hence, the relevant asymmetry in the neutrino emission is suppressed by much smaller coefficient of $\mathcal O(\mu_BB/m)$, where $m$ is the nucleon mass; detailed form of the relevant drift flux is also derived from the scattering cross section, using a simple diffusion approximation. It appears that the asymmetric neutrino emission is too small to induce the observed pulsar kicks. However, we note the fact that the drift flux is proportional to the deviation of the neutrino distribution function from the value of thermal equilibrium at neutrinosphere. Since the deviation can be large for non-electron neutrinos, it is expected that there occurs cancellation between the deviation and the small suppression factor of $\mathcal O(\mu_BB/m)$. Using a simple parameterization, we show that the drift flux due to neutrino-nucleon scatterings may be comparable to the leading term due to beta processes with nucleons, which has been estimated to give a relevant kick velocity when the magnetic field is sufficiently strong as $10^{15}$--$10^{16}$ G.
118631068
Determination of intergalactic magnetic fields from gamma ray data
We report a measurement of intergalactic magnetic fields using combined data from Atmospheric Cherenkov 
Telescopes and Fermi Gamma-Ray Space Telescope, based on the spectral data alone. If blazars are assumed to produce both gamma rays and cosmic rays, the observed spectra are not sensitive to the intrinsic spectrum of the source, because, for a distant blazar, secondary photons produced along the line of sight dominate the signal. In this case, we set a limit 1 x 10^(-17) G < B < 3 x 10^(-14) G. If one excludes the cosmic-ray component, the 10^(-17) G lower limit remains, but the upper limit depends on the spectral properties of the source. We present the allowed ranges for a variety of model parameters.
119396432
Resonant spin flavor conversion of supernova neutrinos: Dependence on presupernova models and future prospects
We study the resonant spin-flavor (RSF) conversion of supernova neutrinos, which is induced by the interaction between the nonzero neutrino magnetic moment and the supernova magnetic fields, and its dependence on presupernova models. As the presupernova models, we adopt the latest ones by Woosley, Heger, and Weaver, and, further, models with both solar and zero metallicity are investigated. Since the $(1\ensuremath{-}{2Y}_{e})$ profile of the new presupernova models, which is responsible for the RSF conversion, suddenly drops at the resonance region, the completely adiabatic RSF conversion is not realized, even if ${\ensuremath{\mu}}_{\ensuremath{\nu}}{B}_{0}{=(10}^{\ensuremath{-}12}{\ensuremath{\mu}}_{B}{)(10}^{10}\mathrm{G}),$ where ${B}_{0}$ is the strength of the magnetic field at the surface of the iron core. In particular for the model with zero metallicity, the conversion is highly nonadiabatic in the high energy region, reflecting the $(1\ensuremath{-}{2Y}_{e})$ profile of the model. In calculating the flavor conversion, we find that the shock wave propagation, which changes density profiles drastically, is a much more severe problem than it is for the pure Mikheyev-Smirnov-Wolfenstein (MSW) conversion case. This is because the RSF effect occurs at a far deeper region than the MSW effect. To avoid the uncertainty concerning the shock propagation, we restrict our discussion to 0.5 s after the core bounce (and for more conservative discussion, 0.25 s), during which the shock wave is not expected to affect the RSF region. We also evaluate the energy spectrum at the Super-Kamiokande detector for various models using the calculated conversion probabilities, and find that it is very difficult to obtain useful information on the supernova metallicities and magnetic fields or on the neutrino magnetic moment from the supernova neutrino observation. Future prospects are also discussed.
15443198
SUPERNOVA NEUTRINOS AND THEIR IMPLICATIONS FOR NEUTRINO PARAMETERS
We perform a detailed study of the Earth matter effects on supernova neutrinos with neutrino oscillation parameter LMA and small θ13. The Earth effects show significant dependences on the neutrino path length inside the Earth and the value of ∆m12. We investigate rather optimistically a possibility that we can probe the value of ∆m12 by the Earth effects. We assume that θ12 and the direction of the supernova are known with enough accuracy and that the resonance that occurs at higher density in supernova envelope is completely nonadiabatic. Further the neutrino spectra before neutrinos go through the Earth are assumed to be known. Then we show that making use of these dependences, we can obtain implication for the value of ∆m12 by comparing the observed energy spectrum to the predicted one. When SK detects neutrinos from supernova at 10kpc which traveled through the Earth (nadir angle < 80 degree), ∆m12 can be determined with an accuracy of ∼ 10%. In much of the neutrino-detection-time-∆m12 plane, ∆m12 might be determined with an accuracy equal to or better than ±0.5 × 10eV. PACS : 14.60.Pq; 14.60.Lm; 96.40.Tv; 97.60.Bw;