共查询到20条相似文献,搜索用时 54 毫秒
1.
LIU Xiong-Wei ZENG Xiao-Xiong CHEN Shi-Wu LIN Kai YANG Shu-Zheng 《理论物理通讯》2008,50(8):541-544
in the light of Robinson and Wilczek's new idea, and motivated by Banerjee and Kulkarni's simplified method of using only the covariant anomaly to derive Hawking radiation from a black hole, we generally extend the work to Kerr-Newman black hole in dragging coordinates frame. It is shown that the flows introduced to cancel the anomaly at the event horizon are equal to the corresponding Hawking radiation in dragging coordinates frame, which supports and extends Robinson and Wilczek's opinion. 相似文献
2.
The general relativistic frame
dragging effect on the properties, such as the moments of inertia
and the radii of gyration of fast rotating neutron stars with a
uniform strong magnetic field, is calculated accurate to the first
order in the uniform angular velocity. The results show that
compared with the corresponding non-rotating static spherical
symmetric neutron star with a weaker magnetic field, a fast
rotating neutron star (millisecond pulsar) with a stronger magnetic
field has a relative smaller moment of inertia and radius of gyration. 相似文献
3.
LIU Jing-Jing LUO Zhi-Quan 《理论物理通讯》2008,49(1):239-242
The electron capture of Gamow--Teller transition on iron group nuclei is investigated in a strong magnetic. field at the crusts of neutron stars. The results show that the magnetic field has only a slight effect on the electron capture rates with the range of the magnetic fields (10^9 - 10^13 G) on surfaces of most neutron stars, whereas for some magnetars whose range of the magnetic field is 10^13 - 10^18 G, the electron capture rates of most iron group nuclei would be debased greatly and may be even decreased overrun 3 orders of magnitude by the strong magnetic field. 相似文献
4.
The influences of σ^* and Ф mesons, temperature and coupling constants of nucleons on the moment of inertia of the proto neutron star (PNS) are examined in the framework of relativistic mean field theory for the baryon octet {n, p, A, ∑^-, ∑^,∑^+,^-, ^0} system. It is found that, compared with that without considering σ^* and Ф mesons, the moment of inertia decreases. It is also found that the higher the temperature, the larger the incompressibility and symmetry energy coefficient, and the larger the moment of inertia of a PNS. The influence of temperature and coupling constants of the nucleons on the moment of inertia of a PNS is larger than that of the σ^* and Ф mesons. 相似文献
5.
The magnetic proton recoil(MPR)spectrometer is a novel diagnostic instrument with high perfor-mance for measurements of neutron spectra in inertial confinement fusion(ICF)experiments and high power fusion devices.A compact MPR-type spectrometer dedicated to the research of pulsed deuterium-tritium(DT)neutron spectroscopy of special experimental conditions is currently under design.Analyses of the main parameters and performance of the magnetic analysis system through 3-D particle transport calculations and MonteCarlo simulations and calibration of the system performance as a test using CR-39 solid track detector and α particle from 239pu and 226Ra radioactive sources are presented in this paper.The results indicate that the magnetic analysis system will achieve a detection efficiency level of 10-5-10-4 at an energy resolution of 1.5%-2.1%,and fulfills the design goals of the spectrometer. 相似文献
6.
A. Nyffeler 《中国物理 C》2010,34(6):705-711
We review recent developments concerning the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. We first discuss why fully off-shell hadronic form factors should be used for the evaluation of this contribution to the g- 2. We then reevaluate the numerically dominant pion-exchange contribution in the framework of large-No QCD, using an off-shell pion-photon-photon form factor which fulfills all QCD short-distance constraints, in particular, a new short-distance constraint on the off-shell form factor at the external vertex in g- 2, which relates the form factor to the quark condensate magnetic susceptibility in QCD. Combined with available evaluations of the other contributions to hadronic light-by-light scattering this leads to the new result αμ^LbyL;had= (116±40) × 10^-11, with a conservative error estimate in view of the many still unsolved problems. Some potential ways for further improvements are briefly discussed as well. For the electron we obtain the new estimate αe^LbyL;had= (3.9± 1.3) × 10^-14. 相似文献
7.
We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions (5) 2 to the running of the QED coupling, Δαbad^5)(MZ^2). Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV. 相似文献
8.
Michel Davier 《中国物理 C》2010,34(6):718-727
Results on the lowest-order hadronic vacuum polarization contribution to the muon magnetic anomaly are presented. They are based on the latest published experimental data used as input to the dispersion integral. Thus recent results on τ→υτππ^0 decays from Belle and on e^+e^- annihilation to π^+π^- from BABAR and KLOE are included. The new data, together with improved isospin-breaking corrections for τ decays, result into a much better consistency among the different results. A discrepancy between the Standard Model prediction and the direct g- 2 measurement is found at the level of 3σ. 相似文献
9.
Tsutomu Mibe 《中国物理 C》2010,34(6):745-748
A new measurement of the anomalous magnetic moment of the positive muon αμ is proposed with a novel technique utilizing an ultra-cold muon beam accelerated to 300 MeV/c and a 66 cm-diameter muon storage ring without focusing-electric field. This measurement will be complimentary to the previous measurement that achieved 0.54 ppm accuracy with the magic energy of 3.1 GeV in a 14 m diameter storage ring. The proposed experiment aims to achieve the sensitivity down to 0.1 ppm. 相似文献
10.
Gabriel López Castro 《中国物理 C》2010,34(6):712-717
We describe some recent results on isospin breaking corrections which are of relevance for predictions of the leading order hadronic contribution to the muon anomalous magnetic moment aμ^had.LO when using τ lepton data. When these corrections are applied to the new combined data on the π^±π^0 spectral function, the prediction for aμ^had.LO based on τ lepton data gets closer to the one obtained using e^+e^- data. 相似文献
11.
A method based on magnetic moment measurement to identify the structural transition of quenched Fe1-xGax(x=0.15-0.30) alloys
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A method based on the measurement of Fe average atomic magnetic moment to identify the structural transition caused by the increase of Ga content in quenched Fe 1-x Ga x alloys (0.15 ≤ x ≤ 0.30) is proposed.The quenched Fe 1-x Ga x alloys show a change of the Fe average atomic magnetic moment from 2.25μ B to 1.78μ B and then to 1.58μ B,which corresponds to the structural transition from A2 to D0 3 and then to B2.The relationship between the structure and the magnetostriction is clarified,and the maximum magnetostriction appears in the A2 phase.The variation tendency of the magnetostriction is well characterized,which also reflects the structural transition. 相似文献
12.
WANG Qing-Wu LEE Xi-Guo 《理论物理通讯》2008,49(4):971-976
Baryon magnetic moments of p, n, ∑^+,∑^-,Ξ^0, Ξ^- and the beta decay ratios (G A/Gv ) of n → p, ∑^-→n and Ξ^0→∑^+ are calculated in a colored quark cluster model. With SU(3) breaking, the model gives a good fit to the experimental values of those baryon magnetic moments and the beta decay ratios. Our results show that the orbital motion has a significant contribution to the spin and magnetic moments of those baryons and the strange component in nucleon is small. 相似文献
13.
After a brief review of the muon g-2 status, we discuss hypothetical errors in the Standard Model prediction that might explain the present discrepancy with the experimental value. None of them seems likely. In particular, a hypothetical increase of the hadroproduction cross section in low-energy e^+e^- collisions could bridge the muon g-2 discrepancy, but it is shown to be unlikely in view of current experimental error estimates. If, nonetheless, this turns out to be the explanation of the discrepancy, then the 95% CL upper bound on the Higgs boson mass is reduced to about 135 GeV which, in conjunction with the experimental 114.4 GeV 95% CL lower bound, leaves a narrow window for the mass of this fundamental particle. 相似文献
14.
The effect of slow rotation on the dipole magnetic field of neutron stars is studied. It is shown that the differential rotation of inertial frames produced by the effect of “dragging of inertial frames” induces an additional component of electric field outside the star. This new component, as well as the usual electromagnetic components, vanishes as in the limit of collapse of a star to its Schwarzschild radius. For typical neutron stars, the electric quadrupole moment is about half that obtainable from a flat space analysis. 相似文献
15.
16.
The equations describing the moment of inertia and the dragging of inertial frames of slowly rotating neutron stars are derived according to Rosen's bimetric theory of gravitation. Numerical calculations of the properties of neutron stars according to the bimetric theory and general relativity were made using several equations of state. The general trend found is that in the bimetric theory neutron stars with a given mass induce a smaller dragging of inertial frames than in general relativity. The moment of inertia of low-mass stars also is smaller in the bimetric theory. For high-mass stars, however, the moment of inertia is found to be larger in the bimetric theory.In partial fulfillment of the requirements for the D.Sc. degree. 相似文献
17.
Carmen Almasan T. Datta R.D. Edge E.R. Jones J.W. Cable H.M. Ledbetter 《Journal of magnetism and magnetic materials》1989,80(2-3):329-338
The low-temperature (5 K < T < 300 K) magnetic properties of a set of nine isostructural fcc Fe-Cr-Ni (Fe ≈ 68 at %, Cr ≈ 20 at%, Ni ≈ 9 at%) alloys were studied by SQUID magnetometry, neutron diffraction and ultrasonic techniques. Type-1 antiferromagnetic (AF) ordering was observed below the Néel temperature, TN. The dc susceptibility, χ(T), did not exhibit a simple Curie-Weiss dependence. Above TN, atemperature independent component χ0 was observed, i.e., χ(T) = χ0 + C / (itT + θ. TN was systematically influenced by the lattice parameter, a, decreasing from (47.9 ± 0.5) K to (35.0 ± 0.5) K as a increased by only 0.25%. The average magnetic moment of ≈ 0.6μB obtained from neutron scattering was lower than the ≈ 1 μB obtained from the SQUID data. Mean field estimates of antiferromagnetic nearest-neighbors exchange interaction (J1) and ferromagnetic second-nearest-neighbors interaction (J2) indicate that |J2/J1|≈ 1.5. We believe that this is evidence of the RKKY interaction, and self-consistently argue that only the external d electrons are responsible for the localized average moment. This may mean that s-d hybridization of the external electrons is weak in these alloys. 相似文献
18.
CHEN Yan-Jun GUO Hua 《理论物理通讯》2008,49(5):1283-1286
We have investigated the possibility of the presence of the deltas in neutron star matter and their effects on neutron stars. Δ-meson couplings of the theoretical predictions are only restricted in a region where the deltas can be present and even a first-order phase transition may take place, making the EOS sorer and the maximum mass of neutron stars smaller. The presence of the deltas leads to the rapid decrease of neutrino mean free paths. 相似文献
19.
To perform a kinematically complete measurement of the dissociation reaction for neutron-rich nuclei, a multi-neutron correlation spectrometer is proposed at Peking University. A Monte Carlo simulation code based on GEANT4 is developed for a single scintillation bar which processes not only the energy deposition but also the light propagation in the scintillator and the light collection and conversion to signal at the end of the bar in a realistic way. The simulating method is described in detail in this paper, and the timing and position resolutions and detector efficiency are studied based on the simulation and compared with the experimental results. A new method of crosstalk rejection has been demonstrated to be important for the design of the whole spectrometer. 相似文献
20.
LIU Shu-Quan Biicherl Thomas LI Hang ZOU Yu-Bin LU Yuan-Rong GUO Zhi-Yu 《中国物理C(英文版)》2013,(11):114-120
Distortions caused by the neutron spectrum and scattered neutrons are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-II in Technische Universit/it Mfinchen (TUM), Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by the neutron spectrum, and the Point Scattered Function (PSeF) simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve image quality. Good analysis results prove the sound effects of the above two corrections. 相似文献