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.
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.
14652153
Neutron–neutron fusion
Abstract The neutron–neutron fusion process, n n → d e ν , at very low neutron energies is studied in the framework of pionless effective field theory that incorporates dibaryon fields. The cross section and electron energy spectrum for this process are calculated up to next-to-leading order. We include the radiative corrections of O ( α ) calculated for the one-body transition amplitude. The precision of our theoretical estimates is found to be governed essentially by the accuracy with which the empirical values of the neutron–neutron scattering length and effective range are currently known. Also discussed is the precision of theoretical estimates of the transition rates of related electroweak processes in few-nucleon systems.
118594879
Renormalization-group analysis for low-energy scattering of charged particles
The low-energy scattering of two charged particles is analyzed using a renormalization group approach based on dimensional regularization with power-divergence subtraction. A nontrivial solution with a marginally unstable direction is found, corresponding to a system with a bound state at zero energy. For purely energy-dependent perturbations around this solution, the power counting agrees with that from Wilsonian methods. These terms in the effective potential are in direct correspondence with the the terms in the Coulomb-distorted effective-range expansion. We also study perturbations that depend on off-shell momenta as well as energy, and we show that these affect only the off-shell form of the scattering matrix. These terms are of higher order than the corresponding energy-dependent ones and so terms in the potential that depend only on the off-shell momenta do not have definite orders in power counting.
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.
15665946
Cosmic Star Formation History and the Future Observation of Supernova Relic Neutrinos
We investigate the flux and event rate of supernova relic neutrinos (SRNs) and discuss their implications for the cosmic star formation rate. Since SRNs are diffuse neutrino background emitted from past core-collapse supernova explosions, they contain fruitful information on the supernova rate in the past and present universe, as well as on the supernova neutrino spectrum itself. As reference models, we adopt the supernova rate model based on recent observations and the supernova neutrino spectrum numerically calculated by several groups. In the detection energy range Ee > 10 MeV, which will possibly be a background-free region in the near future, the SRN event rate is found to be 1-2 yr-1 at a water Cerenkov detector with a fiducial volume of 22.5 kton, depending on the adopted neutrino spectrum. We also simulate the expected signal with one set of the reference models by using the Monte Carlo method and then analyze these pseudodata with several free parameters, obtaining the distribution of the best-fit values for them. In particular, we use a parameterization such that RSN(z) = R(1 + z)α, where RSN(z) is the comoving supernova rate density at redshift z and R and α are free parameters, assuming that the supernova neutrino spectrum and luminosity are well understood by way of a future Galactic supernova neutrino burst or the future development of numerical supernova simulations. The obtained 1 σ errors for these two parameters are found to be δα/α = 30% (7.8%) and δR/R = 28% (7.7%) for a detector with an effective volume of 22.5 kton × 5 yr (440 kton × 5 yr), where one of the parameters is fixed. On the other hand, if we fix neither of the values for these two parameters, the expected errors become rather large, δα/α = 37% and δR/R = 55%, even with an effective volume of 440 kton × 5 yr.
121733919
Neutrino Burst from Supernovae and the Implications for Neutrino Oscillation Parameters
It was shown that neutrinos have finite masses and convert each other from the solar and atmospheric neutrino observations. The time profile and energy spectrum of neutrino burst from supernovae should be greatly modifiedby this effect. We review how this conversion happens in a supernova mantle and how the burst will be detected by SK (Super-Kamiokande) and SNO (Sudbury Neutrino Observatory). We show that implications for neutrino parameters (mass hierarchy and the mixing angle between mass eigenstate v 1 , v 3 ), are obtained if a supernova appears at Galactic Center. We also discuss effects of neutrino oscillation on the supernova relic neutrino observations.
11622261
Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of the cosmic gamma-ray background
The origin of the cosmic gamma-ray background (CGB) is a longstanding mystery in high-energy astrophysics. Possible candidates include ordinary astrophysical objects such as unresolved blazars, as well as more exotic processes such as dark matter annihilation. While it would be difficult to distinguish them from the mean intensity data alone, one can use anisotropy data instead. We investigate the CGB anisotropy both from unresolved blazars and dark matter annihilation (including contributions from dark matter substructures), and we find that the angular power spectra from these sources are very different. We then focus on detectability of dark matter annihilation signals using the anisotropy data by treating the unresolved blazar component as a known background. We find that the dark matter signature should be detectable in the angular power spectrum of the CGB from two-year all-sky observations with the Gamma Ray Large Area Space Telescope (GLAST), as long as the dark matter annihilation contributes to a reasonable fraction, e.g., >~0.3, of the CGB at around 10 GeV. We conclude that the anisotropy measurement of the CGB with GLAST should be a powerful tool for revealing the CGB origin, and potentially for the first detection of dark matter annihilation.
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.
119121510
Power spectrum tomography of dark matter annihilation with local galaxy distribution
Cross-correlating the gamma-ray background with local galaxy catalogs potentially gives stringent constraints on dark matter annihilation. We provide updated theoretical estimates of sensitivities to the annihilation cross section from gamma-ray data with Fermi telescope and 2MASS galaxy catalogs, by elaborating the galaxy power spectrum and astrophysical backgrounds, and adopting the Markov-Chain Monte Carlo simulations. In particular, we show that taking tomographic approach by dividing the galaxy catalogs into more than one redshift slice will improve the sensitivity by a factor of a few to several. If dark matter halos contain lots of bright substructures, yielding a large annihilation boost (e.g., a factor of ~100 for galaxy-size halos), then one may be able to probe the canonical annihilation cross section for thermal production mechanism up to masses of ~700 GeV. Even with modest substructure boost (e.g., a factor of ~10 for galaxy-size halos), on the other hand, the sensitivities could still reach a factor of three larger than the canonical cross section for dark matter masses of tens to a few hundreds of GeV.