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.
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.
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.
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.
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.
119035411
Star-forming galaxies as the origin of diffuse high-energy backgrounds: gamma-ray and neutrino connections, and implications for starburst history
Star-forming galaxies have been predicted to contribute considerably to the diffuse gamma-ray background as they are guaranteed reservoirs of cosmic rays. Assuming that the hadronic interactions responsible for high-energy gamma rays also produce high-energy neutrinos and that (100) PeV cosmic rays can be produced and confined in starburst galaxies, we here discuss the possibility that star-forming galaxies are also the main sources of the high-energy neutrinos observed by the IceCube experiment. First, we compute the diffuse gamma-ray background from star-forming galaxies, adopting the latest Herschel PEP/HerMES luminosity function and relying on the correlation between the gamma-ray and infrared luminosities reported by Fermi observations. Then we derive the expected intensity of the diffuse high-energy neutrinos from star-forming galaxies including normal and starburst galaxies. Our results indicate that starbursts, including those with active galactic nuclei and galaxy mergers, could be the main sources of the high-energy neutrinos observed by the IceCube experiment. We find that assuming a cosmic-ray spectral index of 2.1–2.2 for all starburst-like galaxies, our predictions can be consistent with both the Fermi and IceCube data, but larger indices readily fail to explain the observed diffuse neutrino flux. Taking the starburst high-energy spectral index as free parameter, and extrapolating from GeV to PeV energies, we find that the spectra harder than E-2.15 are likely to be excluded by the IceCube data, which can be more constraining than the Fermi data for this population.
73520402
Resonant Spin-Flavor Conversion of Supernova Neutrinos
We investigate resonant spin-flavor (RSF) conversions of supernova neutrinos which are induced by the interaction of neutrino magnetic moment and supernova magnetic fields. From the formulation which includes all three-flavor neutrinos and anti-neutrinos, we give a new crossing diagram that includes not only ordinary MSW resonance but also magnetically-induced RSF effect. With the diagram, it is found that four conversions occur in supernova, two are induced by the RSF effect and two by the pure MSW. We also numerically calculate neutrino conversions in supernova matter, using neutrino mixing parameters inferred from recent experimental results and a realistic supernova progenitor model. The results indicate that until 0.5 seconds after core bounce, the RSF-induced νe ↔ ντ transition occurs efficiently (adiabatic resonance), when μν ∼ 10−12μB(B0/5 × 109G)−1, where B0 is the strength of the magnetic field at the surface of iron core. We also evaluate the energy spectrum as a function of μνB0 at the SuperKamiokande detector and the Sudbury Neutrino Observatory using the calculated conversion probabilities, and find that the spectral deformation might have possibility to provide useful information on neutrino magnetic moment as well as magnetic field strength in supernovae.1 1 Reference: S. Ando and K. Sato, Phys. Rev. D 67, 023004 (2003).
7807467
Determining the supernova direction by its neutrinos
Supernova neutrinos, which arrive at Earth earlier than light, allow for the earliest determination of the direction of the supernova. The topic of this paper is to study how accurately we can determine the supernova direction. We simulate supernova neutrino events at the SuperKamiokande detector, using a realistic supernova model and several realistic neutrino oscillation models. With the results of our simulation, we can restrict the supernova direction to be within a circle of radius 9°. In several neutrino oscillation models, this accuracy is increased to 8°. We also discuss the influence of an accident that occurred at the SuperKamiokande detector. After repair of the detector, using the remaining PMTs, the accuracy becomes about 12° for no oscillation.
67832038
Colloquium: Multimessenger astronomy with gravitationalwaves and high-energy neutrinos
Many of the astrophysical sources and violent phenomena observed in our Universe are potential 
emitters of gravitational waves and high-energy cosmic radiation, including photons, hadrons, and 
presumably also neutrinos. Both gravitational waves (GW) and high-energy neutrinos (HEN) are 
cosmic messengers that may escape much denser media than photons. They travel unaffected over 
cosmological distances, carrying information from the inner regions of the astrophysical engines from 
which they are emitted (and from which photons and charged cosmic rays cannot reach us). For the same 
reasons, such messengers could also reveal new, hidden sources that have not been observed by 
conventional photon-based astronomy. Coincident observation of GWs and HENs may thus play a 
critical role in multimessenger astronomy. This is particularly true at the present time owing to the 
advent of a new generation of dedicated detectors: the neutrino telescopes IceCube at the South Pole and 
ANTARES in the Mediterranean Sea, as well as the GW interferometers Virgo in Italy and LIGO in the 
United States. Starting from 2007, several periods of concomitant data taking involving these detectors 
have been conducted. More joint data sets are expected with the next generation of advanced detectors 
that are to be operational by 2015, with other detectors, such as KAGRA in Japan, joining in the future. 
Combining information from these independent detectors can provide origin always of constraining the 
physical processes driving the sources and also help confirm the astrophysical origin of a GW or HEN 
signal in case of coincident observation. Given the complexity of the instruments, a successful joint 
analysis of this combined GW and HEN observational data set will be possible only if the expertise and 
knowledge of the data is shared between the two communities. This Colloquium aims at providing an 
overview of both theoretical and experimental state of the art and perspectives for GW and HEN 
multimessenger astronomy.
10058011
Angular power spectrum of gamma-ray sources for GLAST: blazars and clusters of galaxies
Blazars, a beamed population of active galactic nuclei, radiate high-energy γ-rays, and thus are a good target for the Gamma Ray Large Area Space Telescope (GLAST). As the blazars trace the large-scale structure of the Universe, one may observe spatial clustering of blazars. We calculate the angular power spectrum of blazars that would be detected by GLAST. We show that we have the best chance of detecting their clustering at large angular scales, θ ≳ 10°, where shot noise is less important, and the dominant contribution to the correlation comes from relatively low redshift, z ≲ 0.1. The GLAST can detect the correlation signal, if the blazars detected by GLAST trace the distribution of low-z quasars observed by optical galaxy surveys, which have the bias of unity. If the bias of blazars is greater than 1.5, GLAST will detect the correlation signal unambiguously. We also find that GLAST may detect spatial clustering of clusters of galaxies in γ-rays. The shape of the angular power spectrum is different for blazars and clusters of galaxies; thus, we can separate these two contributions on the basis of the shape of the power spectrum.