122604041
NEUTRINOS FROM PROTONEUTRON STARS
We performed numerical simulations of the quasistatic evolution of protoneutron star with neutrino transfer using multigroup flux limited diffusion scheme. The second half of the supernova neutrinos are emitted in this stage. We found 1) the flux decays rapidly and its mean energy falls below j/e's mean energy at the late stage, 2) Pe's carry out energy of about 24% of the total energy emitted in this cooling phase, and 3) the time-integrated energy spectra of u^s and v^s can be roughly fitted by the Fermi-Dirac spectra with positive chemical potentials while those of the other neutrinos can be fitted by MaxwellBoltzmann spectra. These results suggest that the total energy of the neutrino burst from SN1987A was overestimated if one assumed that the Pe's spectrum is the Fermi-Dirac one with a vanishing chemical potential and that all species of neutrinos contribute equally.
115605822
Supernova neutrinos - multigroup simulations of neutrinos from protoneutron star.
121630149
Constraints on oscillation parameters through the MSW effect of supernova neutrinos
We try to constrain the neutrino oscillation parameters by studying the MSW matter effect on supernova neutrinos. Using an implicit Lagrangian code for general relativistic spherical hydrodynamics (Yamada, 1997), we calculate the propagation of shock waves passing through the stellar envelopes over dozens of seconds, which is based on modeling the adiabatic collapse of iron core. We study how quantitatively the influence of the shock propagation appears in the deformation of neutrino energy spectrum. In addition, we are able to examine the θ13 dependence of time evolution of the neutrino detection rates at SK. Using our supernova model, we found that the MSW effect appears, at first, from low-energy region and moves toward high-energy region as the shock wave propagates. We find that the shock propagation has strong influence on the supernova neutrino oscillation through the evolution of density profile induced by the shock propagation.
14724846
An approach toward the successful supernova explosion by physics of unstable nuclei
We study the explosion mechanism of collapse-driven supernovae by numerical simulations with a new nuclear EOS based on unstable nuclei. We report new results of simulations of general relativistic hydrodynamics together with the Boltzmann neutrino-transport in spherical symmetry. We adopt the new data set of relativistic EOS and the conventional set of EOS (Lattimer-Swesty EOS) to examine the influence on dynamics of core-collapse, bounce and shock propagation. We follow the behavior of stalled shock more than 500 ms after the bounce and compare the evolutions of supernova core.
118715119
EFFECTS OF RESISTIVITY ON MAGNETIZED CORE-COLLAPSE SUPERNOVAE
We studied the role of turbulent resistivity in the core-collapse of a strongly magnetized massive star, carrying out two-dimensional resistive-MHD simulations. Three cases with different initial strengths of magnetic field and rotation are investigated: (1) a strongly magnetized rotating core, (2) a moderately magnetized rotating core, and (3) a very strongly magnetized non-rotating core. In each case, one ideal-MHD model and two resistive-MHD models are computed. As a result of these computations, each model shows an eruption of matter assisted by magnetic acceleration (and also by centrifugal acceleration in the rotating cases). We found that resistivity attenuates the explosion in cases 1 and 2, while it enhances the explosion in case 3. We also found that in the rotating cases, the main mechanisms for the amplification of a magnetic field in the post-bounce phase are an outward advection of the magnetic field and a twisting of poloidal magnetic field lines by differential rotation, which are somewhat dampened down with the presence of resistivity. Although magnetorotational instability seems to occur in the rotating models, it plays only a minor role in magnetic field amplification. Another impact of resistivity is that on the aspect ratio. In the rotating cases, a large aspect ratio of the ejected matter, >2.5, attained in an ideal-MHD model is reduced to some extent in a resistive model. These results indicate that resistivity possibly plays an important role in the dynamics of strongly magnetized supernovae.
122761303
Energy–momentum tensor from the Yang–Mills gradient flow
119833545
NEUTRINOS FROM SUPERNOVA EXPLOSION AND THE MIKHEYEV-SMIRNOV-WOLFENSTEIN EFFECT
It is shown that by taking the effect of the Earth into account the possible observation of electron neutrinos from the supernova SN1987A at the Kamiokande II is compatible with the solution of the solar neutrino puzzle by the Mikheyev-Smirnov-Wolfenstein mechanism. Our scenario requires relatively large mixing angles sin2 2θ ≳ 0.3 and, most probably, ∆m2 of the order of 10−6 ~ 10−5(eV)2. The implications of possible observation in other neutrino detectors are briefly discussed.
17038219
Observing quantum tunneling in perturbation series
Abstract We apply Borel resummation to the conventional perturbation series of ground state energy in a metastable potential, V(x) = x 2 2 − gx 4 4 . We observe numerically that the discontinuity of the Borel transform reproduces the imaginary part of the energy eigenvalue, i.e., the total decay width due to quantum tunneling. The agreement with the exact numerical value is remarkable in the whole tunneling regime 0 g ≲ 0.7.
119431748
Duality in potential curve crossing: Application to quantum coherence
A field dependent $su(2)$ gauge transformation connects between the adiabatic and diabatic pictures in the (Landau-Zener-Stueckelberg) potential curve crossing problem. It is pointed out that weak and strong potential curve crossing interactions are interchanged under this transformation, and thus realizing a naive strong and weak duality. A reliable perturbation theory should thus be formulated in the both limits of weak and strong interactions. In fact, main characteristics of the potential crossing phenomena such as the Landau-Zener formula including its numerical coefficient are well-described by simple (time-independent) perturbation theory without referring to Stokes phenomena. We also show that quantum coherence in a double well potential is generally suppressed by the effect of potential curve crossing, which is analogous to the effect of Ohmic dissipation on quantum coherence.
16618542
Renormalon's contribution to effective couplings
When an asymptotically non-free theory possesses a mass parameter independent of the Λ parameter, the uv renormalon gives rise to nonperturbative contributions, to dimension-four operators and dimensionless couplings, thus has a "dual" effect of the instanton. We illustrate this phenomenon in O(N) symmetric massive λϕ4 model in the 1/N expansion. This effect of uv renormalon is briefly compared with nonperturbative corrections in the magnetic picture of the Seiberg–Witten theory.