共查询到20条相似文献,搜索用时 125 毫秒
1.
The influences on the neutrino energy loss rates in iron group nuclei
at the same density are investigated in the presence of strong
electron screening and in the absence of electron screening. The
results show that at a temperature of $15\ti10^9$\,K, the neutrino
energy loss rates which come from the electron capture process for
most iron group nuclei decrease no more than 2 orders of magnitude
but for the others (such as $^{53,55,56,57,58,59,60}$Co,
$^{56,59}$Ni) they can decrease about 3 orders of magnitude due to
strong electron screening (SES), whereas, at a temperature of $10^9K$
the neutrino energy loss rates of the most iron group nuclei can be
diminished greatly due to the SES. For example, $^{61}$Fe, $^{60}$Fe,
and $^{62}$Ni the neutrino energy loss rates decrease about 4, 15 and
16 orders of magnitude and for $^{57}$Cr, $^{58}$Cr, and $^{60}$Cr
decrease about 18, 12, and 10 orders of magnitude respectively.
According to our calculations the neutrino energy loss rates of
nuclei $^{58}$Mn, $^{59}$Mn, $^{60}$Mn, and $^{62}$Mn may decrease
about 13 orders of magnitude at a temperature of $10^9$\,K due to the
SES. 相似文献
2.
Neutrino Energy Loss by Electron Capture on Nucleus ^56Mn, ^56Fe, ^56Co and ^56Ni in Strong Electron Screening 下载免费PDF全文
Based on the p-f shell model, the neutrino energy loss rates for nucleus ^56Mn, ^56Fe, ^56Co and ^56Ni in the electron capture process are canvassed in and not in a strong electron screening. The results show that the neutrino energy loss rates for ^56Mn, ^56Fe, ^56Co and ^56Ni decrease about 15%, 10%, 60% and i order of magnitude correspondingly at the temperature T9 = 15 and even debase 2 orders of magnitude at the temperature T9 = 1. 相似文献
3.
LIU Jing-Jing 《中国物理C(英文版)》2009,33(10)
Based on the Weinberg-Salam theory, the plasma neutrino energy loss rates of vector and axialvector contributions are studied.A ratable factor of the rates from the axial-vector current relative to those of the total neutrino energy loss rates is accurately calculated.The results show that the ratable factor will reach a maximum of 0.95 or even more at relatively higher temperature and lower density (such as P/μe< 10~7 g/cm~3).Thus the rates of the axial-vector contribution cannot be neglected.On the other hand, the rates of the axialvector contribution are on the order of~0.01% of the total vector contribution, which is in good agreement with Itoh's at relatively high density (such as p/μe>10~7 g/cm~3) and a temperature of T≤10~(11) K. 相似文献
4.
Based on the p-f shell model,the effect of strong magnetic field on neutrino energy loss rates by electron capture is investigated.The calculations show that the magnetic field has only a slight effect on the neutrino energy loss rates in the range of 108-1013 G on the surfaces of most neutron stars.But for some magnetars,the range of the magnetic field is 1013-1018 G,and the neutrino energy loss rates are greatly reduced,even by more than four orders of magnitude due to the strong magnetic field. 相似文献
5.
Based on the p-f shell model, the effect of strong magnetic field on neutrino energy loss rates by electron capture is investigated. The calculations show that the magnetic field has only a slight effect on the neutrino energy loss rates in the range of 108—1013G on the surfaces of most neutron stars. But for some magnetars, the range of the magnetic field is 1013—1018G, and the neutrino energy loss rates are greatly reduced, even by more than four orders of magnitude due to the strong magnetic field. 相似文献
6.
7.
Based on the Weinberg-Salam theory, the competition of the Neutrino Energy Loss (NEL) rates due to the pair, photo-and plasma process are canvassed. The ratio factor C1, C2 and C3 which correspond the different contributions of the pair, photo-and plasma neutrino process to those of the total NEL rates are accurately taken into account. The ratio factors are very sensitive to the temperature and density. The ratio factor C2 always is lower than the ratio factor C1 and C3. The pair NEL process is the dominant contribution before the crossed point 0(C1 = C3 = 0.45) and the plasma NEL process will be the main dominant contribution after the crossed point O. With increasing temperature, the crossed point O will move to the direction of higher density. 相似文献
8.
研究了超强磁场对中子星外壳层核素56Fe,56Co,56Ni,56Mn和56Cr电子俘获过程中微子能量损失的影响.结果表明,就大部分中子星表面的磁场B<1013G,超强磁场对中微子能量损失率的影响很小.对于一些磁场范围为1013—1015G的超磁星,超强磁场可使中微子能量损失率大大降低,甚至超过5个数量级. 相似文献
9.
LIU Jing-Jing 《中国物理C(英文版)》2009,33(1):15-19
Based on the Weinberg-Salam theory,the competition of the Neutrino Energy Loss (NEL) rates due to the pair,photo- and plasma process are canvassed.The ratio factor C1,C2 and C3 which correspond the different contributions of the pair,photo- and plasma neutrino process to those of the total NEL rates are accurately taken into account.The ratio factors are very sensitive to the temperature and density.The ratio factor C2 always is lower than the ratio factor C1 and C3.The pair NEL process is the dominant contribution before the crossed point O(C1=C3=0.45) and the plasma NEL process will be the main dominant contribution after the crossed point O.With increasing temperature,the crossed point O will move to the direction of higher density. 相似文献
10.
We constrain energy spectra of supernova neutrinos through the avoidance of an overproduction of the 11B abundance during Galactic chemical evolution. In supernova nucleosynthesis calculations with a parametrized neutrino spectrum as a function of temperature of nu(mu,tau) and nu(mu,tau) and total neutrino energy, we find a strong neutrino temperature dependence of the 11B yield. When the yield is combined with observed abundances, the acceptable range of the nu(mu,tau) and nu(mu,tau) temperature is found to be 4.8 to 6.6 MeV. Nonzero neutrino chemical potentials would reduce this temperature range by about 10% for a degeneracy parameter eta(nu) = mu(nu)/kT(nu) smaller than 3. 相似文献
11.
A. Odrzywołek 《The European Physical Journal C - Particles and Fields》2007,52(2):425-434
The spectrum of the neutrinos produced in the massive photon and longitudinal plasmon decay process has been computed with
four levels of approximation for the dispersion relations. Some analytical formulae in the limit cases are derived. Interesting
conclusions related to previous calculations of the energy loss in stars are presented. The high energy tail of the neutrino
spectrum is shown to be proportional to exp(-E/kT), where E is the neutrino energy and kT is the temperature of the plasma.
PACS 97.90.+j; 97.60.-s; 95.55.Vj; 52.27.Ep 相似文献
12.
13.
LIU Jing-Jing KANG Xiao-Ping HE Zhong HUANG Huai-Ren SHI Huan-Yu HUANG Hong-Chao ZHONG Shan FENG Hao LI Chang-Wei 《中国物理C(英文版)》2011,35(3)
Gaussian modifications of the neutrino energy loss (NEL) by electron capture on the strongly screening nuclides 55Co and 56Ni are investigated. The results show that in strong electron screening (SES),the NEL rates decrease without modifying the Gamow-Teller (G-T) resonance transition. For instance, the NEL rates of 55Co and 56Ni decrease more than two and three orders of magnitude for ρ7 = 5.86, T9≤ 5,Ye = 0.47, △ = 6.3, respectively. In contrast, due to Gaussian modification, the NEL rates increase about two orders of magnitude in SES. Due to SES, the maximum values of the C-factor (in %) on NEL of 55Co, 56Ni are of the order of 99.80%, 99.56% at ρ7 = 5.86 Ye = 0.47 and 99.60%, 99.65% at ρ7 = 106 Ye = 0.43, respectively. 相似文献
14.
Ahn MH Aoki S Bhang H Boyd S Casper D Choi JH Fukuda S Fukuda Y Gajewski W Hara T Hasegawa M Hasegawa T Hayato Y Hill J Ichikawa AK Ikeda A Inagaki T Ishida T Ishii T Ishitsuka M Itow Y Iwashita T Jang HI Jang JS Jeon EJ Jung CK Kajita T Kameda J Kaneyuki K Kato I Kearns E Kibayashi A Kielczewska D Kobayashi K Kim BJ Kim CO Kim JY Kim SB Kobayashi T Kohama M Koshio Y Kropp WR Learned JG Lim SH Lim IT Maesaka H Martens K Maruyama T Matsuno S Mauger C McGrew C Mine S Miura M Miyano K Moriyama S 《Physical review letters》2003,90(4):041801
The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%. 相似文献
15.
We investigate a model in which tiny neutrino masses are generated at the two-loop level by using scalar leptoquark and diquark multiplets. The diquark can be singly produced at the LHC, and it can decay into a pair of leptoquarks through the lepton number violating interaction. Subsequent decays of the two leptoquarks can provide a clear signature of the lepton number violation, namely two QCD jets and a pair of same-signed charged leptons without missing energy. We show that the signal process is not suppressed while neutrino masses are appropriately suppressed. 相似文献
16.
Theories involving extra dimensions, a low (TeV) string scale and bulk singlet neutrinos will produce an effective neutrino magnetic moment which may be large (10−11μB). The effective magnetic moment increases with neutrino energy, and therefore high energy reactions are most useful for limiting the allowed number of extra dimensions. We examine constraints from both neutrino-electron scattering and also astrophysical environments. We find that supernova energy loss considerations require a number of extra dimensions, n≥2, for an electron neutrino-bulk neutrino Yukawa coupling of order 1. 相似文献
17.
The stellar energy loss rate due to the production of neutrino pairs by Bremsstrahlung is calculated for neutron stars in the presence of a strong magnetic field (B ? 1012 G) and the Coulomb field of the positive ions. The calculated energy loss rates are applied to nonrelativistic electrons at low densities ? 105 gm/cm3 and relatively low temperatures T ? 109 K. 相似文献
18.
P. A. Eminov 《Journal of Experimental and Theoretical Physics》2016,122(1):63-77
The total energy shift of a polarized massive Dirac neutrino in an electron–positron plasma in a constant magnetic field is investigated. The calculation in the Feynman gauge is performed for the first time by using the Matsubara temperature Green functions. The dependence of the dispersion relation and the anomalous magnetic moment of the neutrino on the magnetic field strength, spin, energy, direction of motion, neutrino mass, and the plasma parameters is analyzed. The results of investigations for the massive neutrino in the limiting case are compared with those obtained earlier by other authors for the massless left neutrino. 相似文献
19.
A bilinear R-parity breaking SUSY model for neutrino mass and mixing predicts the lightest superparticle to decay mainly into a pair of tau leptons or b quarks along with a neutrino for relatively light SUSY spectra. This leads to a distinctive triple bang signature of SUSY events at ultrahigh energy neutrino telescopes like IceCube or Antares. While the expected signal size is only marginal at IceCube, it will be promising for a future multi-km3 size neutrino telescope. 相似文献
20.
Stellar energy loss rates associated with photoneutrino processes in the minimal extension of the standard model 下载免费PDF全文
C. Ayd?n 《中国物理C(英文版)》2023,47(4):043104-043104-7
Using the minimal extension of the standard model and considering the charge radius and the anapole moments of a neutrino, we derive analytical expressions for the stellar energy loss rates associated with the production of a neutrino pair \begin{document}$ e^- + \gamma \rightarrow e^- + \nu_e +\overline{\nu_e} $\end{document} ![]()
![]()
in hot plasma under three limiting regimes (nondegenerate, intermediate, and degenerate electrons) of the temperature, electron chemical potential, and plasma energy. The obtained results reveal the presence of an extra contribution of approximately \begin{document}$10$\end{document} ![]()
![]()
% based on the considered calculations. 相似文献