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.
124377961
A neutrino burst and gravitational wave from supernova explosions
125701625
Gamma-ray burst neutrino background and star formation history in the universe
Abstract We estimate the flux of the GRB neutrino background and compute the event rate at SK and TITAND in the collapsar model, assuming that GRB formation rate is proportional to the star formation rate. We find that the predicted background neutrino flux is highly sensitive to unknown model parameters, mainly to the mass accretion rate, to the fraction of disk energy emitted in thermal neutrinos (as opposed to emission through electromagnetic processes), and to the fraction of collapsar events leading to GRBs. The predicted neutrino flux varies over many orders of magnitude as the values of unknown model parameters are varied. We investigate the detection possibility of thermal neutrinos from collapsars which lead to GRBs by TITAND. We find that the GRB neutrino background might be detected by TITAND within ∼ 10 yrs only for the optimistic cases in which the average mass-accretion rate is high (≥ a few M ⊙ s −1 ), and the probability that one collapsar generates a GRB is high ( φ = 0.5 − 1.0).
216052179
Constraints on the annihilation cross section of dark matter particles from anisotropies in the diffuse gamma-ray background measured with Fermi-LAT
Annihilation of dark matter particles in cosmological halos (including the halo of the Milky Way) contributes to the diffuse gamma-ray background (DGRB). As this contribution will appear anisotropic in the sky, one can use the angular power spectrum of anisotropies in the DGRB to constrain the properties of dark matter particles. By comparing the updated analytic model of the angular power spectrum of the DGRB from dark matter annihilation with the power spectrum recently measured from the 22-month data of the Fermi Large Area Telescope (LAT), we place upper limits on the annihilation cross section of dark matter particles as a function of dark matter masses. We find that the current data exclude (σv)≳10−25  cm3 s−1 for annihilation into bb¯ at the dark matter mass of 10 GeV, which is a factor of 3 times larger than the canonical cross section. The limits are weaker for larger dark matter masses. The limits can be improved further with more Fermi-LAT data as well as by using the power spectrum at lower multipoles (l≲150), which are currently not used due to a potential Galactic foreground contamination.
43135563
High-energy neutrinos from reverse shocks in choked and successful relativistic jets
Highly relativistic jets are a key element of current gamma-ray burst models, where the jet kinetic energy is converted to radiation energy at optically thin shocks. High-energy neutrinos are also expected, from interactions of protons accelerated in the same shocks. Here we revisit the early evolution of a relativistic jet, while the jet is still inside the star, and investigate its neutrino emission. In particular we study propagation of mildly relativistic and ultrarelativistic jets through a type Ib progenitor, and follow reverse shocks as the jets cross the star. We show that protons can be accelerated to 10^4–10^5 GeV at reverse shocks, and efficiently produce mesons. The mesons experience significant cooling, suppressing subsequent neutrino emission. We show, however, that the neutrino yield from the reverse shock is still reasonably large, especially for low-luminosity and long-duration jets, where meson cooling is less severe. We discuss implications of our results in the context of neutrinos from choked jets, which are completely shock heated and do not break out of the star. From a choked jet with isotropic equivalent energy of 10^53 erg at 10 Mpc, we expect ~20 neutrino events at IceCube.
119067583
Supernova Relic Neutrinos and Observational Implications for Neutrino Oscillation
We investigate the flux and the event rate of supernova relic neutrinos (SRN) at the Super-Kamiokande (SK) detector for various neutrino oscillation models with parameters inferred from recent experimental results. We discuss the detectability of SRN at SK, comparing this SRN flux with other background neutrinos in more detail than previous studies, and it is found that in the energy range 17–25 MeV, ten-year observation might enable us to detect SRN signal (at one sigma level). We also set 90% C.L. upper limit on the SRN flux for various oscillation models using the recently released observational result by SK. In addition, we propose that the SRN observation can be used to set strong 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. In the near future, further reduced upper limit is actually expected, when the current SK data are reanalyzed using some technique to reduce background events against the SRN signals. It is expected that the reduced upper limit is sufficient to provide useful implications for neutrino oscillation and decaying neutrinos.
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.
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.
16224074
Proton-proton fusion in pionless effective theory
Abstract The proton–proton fusion reaction, p p → d e + ν , is studied in pionless effective field theory (EFT) with di-baryon fields up to next-to leading order. With the aid of the di-baryon fields, the effective range corrections are naturally resummed up to the infinite order and thus the calculation is greatly simplified. Furthermore, the low-energy constant which appears in the axial-current-di-baryon–di-baryon contact vertex is fixed through the ratio of two- and one-body matrix elements which reproduces the tritium lifetime very precisely. As a result we can perform a parameter free calculation for the process. We compare our numerical result with those from the accurate potential model and previous pionless EFT calculations, and find a good agreement within the accuracy better than 1%.
119111184
Effective range corrections from effective field theory with di-baryon fields and perturbative pions
Contributions of perturbative pions around a non-trivial fixed point are studied by utilizing di-baryon fields. We calculate ${}^1S_0$ and ${}^3S_1$ phase shifts for the $np$ scattering at low energies up to one-pion-exchange contributions. We also calculate effective range parameters, $v_2$, $v_3$ and $v_4$ in the higher order of the effective range expansion, and obtain corrections of the effective range to the expressions previously reported by Cohen and Hansen. After the scattering length and the effective range are renormalized, we study the role of renormailzation scale parameter $\mu$ and discuss the range of validity of the theory.
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.