15737183
Analysis of ordinary and radiative muon capture in liquid hydrogen
The experimental data on the ordinary muon capture (OMC) rate and the partial branching ratio of radiative muon capture (RMC) in liquid hydrogen are simultaneously analyzed using theoretical estimates for the atomic OMC rates obtained in chiral perturbation theory using the most recent physical constants. Since both data have been obtained in a liquid hydrogen target, we reexamine the formulas for relating the atomic OMC and RMC rates to the liquid hydrogen OMC and RMC rates, respectively. Although the analysis is influenced significantly by the ambiguity in the molecular state population, we can conclude that, while the OMC data can be reproduced, it is not possible to explain the OMC and RMC data simultaneously.
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.
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.
122375456
Renormalization group analysis of nuclear current operators
A Wilsonian renormalization group (WRG) equation for nuclear current operators in two-nucleon systems is derived. Nuclear current operators relevant to low-energy Gamow-Teller transitions are analyzed using the WRG equation. We employ the axial two-body current operators from phenomenological models and heavy-baryon chiral perturbation theory, which are quite different from one another in describing small-scale physics. After reducing the model space of the operators using the WRG equation, we find that there still remains a significant model dependence at {lambda}=200 MeV, where {lambda} is the sharp cutoff specifying the size of the model space. A model-independent effective current operator is found at a rather small cutoff value, {lambda}=70 MeV. By simulating the effective current operator at {lambda}=70 MeV, we obtain a current operator based on a pionless theory, thereby arguing that an equivalence relation exists between nuclear current operators of phenomenological models and those of effective field theories.
118343825
Angular correlations in the cosmic gamma-ray background from dark matter annihilation around intermediate-mass black holes
Dark matter (DM) annihilation could in principle contribute to the diffuse cosmic gamma-ray background. While with standard assumptions for cosmological and particle physics parameters this contribution is expected to be rather small, a number of processes could boost it, including a larger-than-expected DM annihilation cross section, or the occurrence of DM substructures such as DM minispikes around intermediate-mass black holes. We show that angular correlations of the cosmic gamma-ray background provide a tool to disentangle the signal induced by DM annihilation in minispikes from a conventional astrophysical component. Treating blazars as a known background, we study the prospects for detecting DM annihilations with the Fermi Gamma-Ray Space Telescope for different choices of DM mass and annihilation channels.
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.
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;
119403614
Decaying neutrinos and implications from the supernova relic neutrino observation
Abstract We propose that supernova relic neutrino (SRN) observation can be used to set constraints on the neutrino decay models. Because of the long distance scale from cosmological supernovae to the Earth, SRN have possibility to provide much stronger limit than the present one obtained from solar neutrino observation. Since the currently available data are only the upper limit on the flux integrated over E ν e >19.3  MeV, the decay models on which we can set constraints is quite restricted; they must satisfy specific conditions such that the daughter neutrinos are active species, the neutrino mass spectrum is quasi-degenerate, and the neutrino mass hierarchy is normal. Our numerical calculation clearly indicates that the neutrino decay model with ( τ 2 / m , τ 3 / m )≲(10 10 ,10 10 ) [s/eV], where τ i represents the lifetime of mass eigenstates ν i , appears to give the SRN flux that is larger than the current upper limit. However, since the theoretical SRN prediction contains many uncertainties concerning a supernova rate in the universe or simulation of supernova explosions, we cannot conclude that there exists the excluded parameter region of the neutrino lifetime. In the near future, further reduced upper limit is actually expected, and it will provide more severe constraints on the neutrino decay models.
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.