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1.
Recent research shows that Hawking radiation from black hole horizon can be treated as a quantum tunneling process, and fermions
tunneling method can successfully recover Hawking temperature. In this tunneling framework, choosing a set of appropriate
matrices γ
μ
is an important technique for fermions tunneling method. In this paper, motivated by Kerner and Man’s fermions tunneling
method of 4 dimension black holes, we further improve the analysis to investigate Hawking tunneling radiation from the non-extremal
black hole in D = 5, SO(6) gauged supergravity by constructing a set of appropriate matrices γ
μ
for general covariant Dirac equation. Finally, the expected Hawking temperature of the black hole is correctly recovered,
which takes the same form as that obtained by other methods. 相似文献
2.
We investigate the effects of accretion of phantom energy onto primordial black holes. Since Hawking radiation and phantom
energy accretion contribute to a decrease of the mass of the black hole, the primordial black hole that would be expected to decay now due to the Hawking process would
decay earlier due to the inclusion of the phantom energy. Equivalently, to have the primordial black hole decay now it would have to be
more massive initially. We find that the effect of the phantom energy is substantial and the black holes decaying now would
be much more massive—over ten orders of magnitude! This effect will be relevant for determining the time of production and hence
the number of evaporating black holes expected in a universe accelerating due to phantom energy. 相似文献
3.
on behalf of the ATLAS Collaboration N. Grau 《The European Physical Journal C - Particles and Fields》2009,62(1):191-196
Full jet reconstruction in relativistic heavy ion collisions provides new and unique insights to the physics of parton energy
loss. Because of the large underlying event multiplicity in A+A collisions, random and correlated fluctuations in the background can result in the reconstruction of fake jets. These fake
jets must be identified and rejected to obtain the purest jet sample possible. A large but reducible fake rate of jets reconstructed
using an iterative cone algorithm on HIJING events is observed. The absolute rate of fake jets exceeds the binary-scaled p+p jet rate below 50 GeV and is not negligible until 100 GeV. The variable Σj
T
, the sum of the jet constituent’s E
T
perpendicular to the jet axis, is introduced to identify and reject fake jets at by a factor of 100 making it negligible.
This variable is shown to not strongly depend on jet energy profiles modified by energy loss. By studying azimuthal correlations
of reconstructed di-jets, the fake jet rate can be evaluated in data.
All results presented use modified versions of ATLAS software and should be considered “ATLAS preliminary”. 相似文献
4.
Gamma-ray pulses are calculated from 2D numerical simulations of upward atmospheric discharge in a self-consistent electric
field using the multigroup approach to the kinetics of relativistic runaway electrons. Thecalculated numbers and spectra of
γ-rays are consistent with the data on terrestrial γ-ray flashes observed aboard spacecraft. The calculated runaway electron
flux is concentrated mainly within the domain of the blue jet fluorescence. This proves that exactly this domain is a source
of the γ-ray flashes. One γ-ray flash generates ∼1014-1015 photonuclear neutrons.
The text was submitted by the authors in English 相似文献
5.
In this paper, by using well-known Eddington–Finkelstein coordinates instead of Painlevè coordinates, we study the tunneling
effect of black holes. As examples of special static black holes, we calculate the tunneling rates of Gibbon–Maeda black holes.
The result obtained by adopting Eddington–Finkelstein coordinates is in agreement with the Parikh’s standard result, Γ∼exp (−2Im S), which adopts the Painlevè coordinates. In addition, we discuss carefully the condition that the coordinates system in which
we study the tunneling process should satisfy. In our opinion, the terms of the tunneling effect are not as strict as ones
in Parikh’s paper and could be softened properly. 相似文献
6.
G. V. Valsky A. M. Gagarski I. S. Guseva D. O. Krinitsin G. A. Petrov Yu. S. Pleva V. E. Sokolov V. I. Petrova T. A. Zavarukhina T. E. Kuzmina 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):767-771
The angular dependence of the γ-ray asymmetry relative to the plane formed by the directions of fission-fragment separation
and longitudinal polarization of the thermal neutrons inducing 235U(n, f) fission was investigated. The results obtained confirm the existence of γ-ray emission asymmetry and the dependence of its
coefficient on the angle between the axes of the fission-fragment and γ-ray detectors, revealed for the first time by the
ITEP group at the FRM-II reactor in Munich. The observed T-odd effect of around ∼2 × 10−4 can be explained by the angular anisotropy of the γ-ray emission from fission fragments with large angular momenta oriented
relative to the fission axis. 相似文献
7.
Kerner and Mann’s recent research shows that, for an uncharged and non-rotating black hole, its Hawking temperature and tunneling
rate can be exactly obtained by the fermion tunneling method from its event horizon. In this paper, considering the tunneling
charged particles with spin 1/2, we extend Kerner and Mann’s method to the generalized spherical symmetric evaporating charged
black hole which is non-stationary. In order to investigate the fermion tunneling through the event horizon, we choose a set
of appropriate matrices γ
μ
. As a result, the tunneling probability and truly effective temperature are well recovered by charged fermions tunneling
from the black hole. 相似文献
8.
D.C. Biswas B.K. Nayak M. Cinausero B. Fornal G. Viesti D. Bazzacco M. DePoli D. Fabris E. Fioretto M. Lunardon D.R. Napoli G. Nebbia G. Prete C.A. Ur G. Vedovato 《The European Physical Journal A - Hadrons and Nuclei》1999,4(4):343-348
The high energy γ-ray emission accompanying the spontaneous fission of 252Cf has been measured in coincidence with individual fission fragments selected by discrete γ-ray transitions. The enhancement
of the γ-ray emission probability in the energy range Eγ= 3–8 MeV has been observed for the fission fragments in the region of nearly symmetric mass splitting, confirming results
reported in previous investigations. The γ-γ coincidence technique employed in the present work clearly demonstrate that the
major contribution to this enhancement is caused by the fission channels where one fragment is near to the N= 82 or Z= 50 shell closures. The high energy γ-ray emission probability does not show any significant dependence on the number of
neutrons emitted in the fission process, supporting the hypothesis that high energy γ-rays are mainly emitted from the fragments
after the neutron evaporation.
Received: 22 December 1998 相似文献
9.
X.H. Zhou Y. Zheng Y.H. Zhang Z. Liu Q.Y. Pan Z.G. Gan T. Hayakawa M. Oshima T. Toh T. Shizuma J. Katakura Y. Hatsukawa M. Matsuda H. Kusakari M. Sugawara K. Furuno T. Komatsubara 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):253-255
The high-spin states of 145Tb have been studied in the 118Sn(32S, 1p4n) reaction at 32S energies from 161 to 175 MeV using techniques of in-beam γ-ray spectroscopy. Measurements of γ-ray excitation functions
and γ-γ-t coincidences were performed with 12 BGO(AC)HPGe detectors. Based on the measured results of γ-γ coincidences, γ-ray anisotropies
and DCO ratios, a level scheme for 145Tb was established for the first time. The observed excited states show typical irregular pattern in a spherical nucleus,
and the low-lying levels have been interpreted qualitatively with a particle-core coupling.
Received: 21 September 2001 / Accepted: 9 November 2001 相似文献
10.
A. A. Belyanin V. V. Kocharovsky VI. V. Kocharovsky 《Radiophysics and Quantum Electronics》1996,41(1):22-27
It is believed that the detection of gamma-ray bursts from evaporating primordial black holes is highly improbable in the
near future since the expected photon flux, consisting mainly of photons with energies ≳ GeV, is too low. Contrary to this
point of view, we show that a large fraction of the black hole power at the final stage of evaporation (the last 103 s) can be liberated as a burst of soft γ-ray emission of duration 10−1–103 s and luminosity 1028–1031 erg/s in the energy range 0.1–1 MeV. According to our calculations of the black hole evaporation rate (within the Standard
Model of elementary particles), when the black hole temperature exceeds approximately 10 GeV, the charged particle outflow
from a black hole forms a well-defined plasma and can be described in the hydrodynamic approximation. In this case more than
half of the rest energy of a black hole can be converted into soft gamma-rays due to the presence of the magnetic field with
energy density comparable to that of charged particles. We consider various mechanisms leading to such transformation and
estimate their efficiency. It is shown that, at least, some of the gamma-ray bursts detected by BATSE can be associated with
evaporating black holes.
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Radiofizika, Vol. 41, No. 1, pp. 36–45, January, 1998. 相似文献
11.
Xavier Calmet Dionysios Fragkakis Nina Gausmann 《The European Physical Journal C - Particles and Fields》2011,71(11):1781
We develop an effective field theory to describe the coupling of non-thermal quantum black holes to particles such as those
of the Standard Model. The effective Lagrangian is determined by imposing that the production cross section of a non-thermal
quantum black hole be given by the usual geometrical cross section. Having determined the effective Lagrangian, we estimate
the contribution of a virtual hole to the anomalous magnetic moment of the muon, μ→eγ transition and to the electric dipole moment of the neutron. We obtain surprisingly weak bounds on the Planck mass due to
a chiral suppression factor in the calculated low energy observables. The tightest bounds come from μ→eγ and the limit on the neutron electric dipole moment. These bounds are in the few TeV region. 相似文献
12.
Bičák Jiří 《Pramana》2000,55(4):481-496
The work on black holes immersed in external fields is reviewed in both test-field approximation and within exact solutions.
In particular we pay attention to the effect of the expulsion of the flux of external fields across charged and rotating black
holes which are approaching extremal states. Recently this effect has been shown to occur for black hole solutions in string
theory. We also discuss black holes surrounded by rings and disks and rotating black holes accelerated by strings.
The content corresponds to the lecture given at ICGC 2000 in Kharagpur. Sections 2–6 are based on the text of the lecture
on ‘Electromagnetic fields around black holes and Meissner effect’ given at the 3rd ICRA workshop in Pescara 1999 (to be published
with T Ledvinka in Nuovo Cimento). 相似文献
13.
As is well known, the distribution of the number of cosmic γ-ray bursts (CGBs) as a function of their duration has two maxima.
In the present letter it is suggested that the longer-duration but less powerful CGBs arise when two neutron stars merge and
a magnetic field is generated, as examined below, and the shorter-duration CGBs can arise as a result of collisions of a black
hole either with a neutron star or another black hole.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 7, 417–421 (10 October 1999) 相似文献
14.
A detailed analysis is presented for a novel scenario in which gamma-ray bursts are of intergalactic origin and arise from
the induced collapse of an isolated neutron star triggered by a primordial black hole. The energy released from the phase
transition of accreted nucleon matter into a quark-gluon plasma is transferred by degenerate neutrinos to the star’s surface,
where neutrinos annihilate into an electron-positron plasma and produce an inverted temperature layer that preserves a fire-ball
from undue baryonic pollution. Possible observational tests include the absence of apparent cosmological time dilation, the
location of γ-ray bursts primarily outside of galaxies, a specific shape of the log N-log S curve, with a large peak near red shift z∼10, the emission of ∼10−3 of the total energy in the form of 100-GeV photons, a bimodal distribution of durations, a very weak accompanying pulse of
gravitational radiation, etc.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 10, 642–647 (25 November 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
15.
Shen Shuifa Fang Keming Gu Jiahui Liu Qingcheng Xu Furong 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):149-158
The decay of 95Ru has been investigated by means of γ-ray spectroscopy. The 95Ru nuclei were produced by the reaction 92Mo( α, n) 95Ru at a beam energy of 17MeV. High-purity Ge detectors have been used singly and in coincidence to study γ-rays in the decay of 95Ru to 95Tc. 132 γ-rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of 95Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed
from calculated log ft values, measured γ-ray branching ratios, and in-beam experiment results of the daughter nucleus 95Tc. Combining with the high-spin states observed by in-beam γ-ray spectroscopy of previous decay works, the structure of the excited states of 95Tc is discussed in the framework of the projected shell model. 相似文献
16.
Measurement of the heavy neutral MSSM Higgs bosons H and A production in the process γγ → A/H → b
at the Photon Linear Collider [1,2] has been considered in two independent analyses for the parameter range corresponding
to the so-called ‘LHC wedge’. Significantly different conclusions were obtained; signal-to-background ratio 36 vs. 2. Here
assumptions and results of these two analyses are compared. We have found that differences in the final results are mainly
due to different assumptions on γγ-luminosity spectra, jet definitions and selection cuts.
相似文献
17.
Zheng Yong Zhou Xiaohong Zhang Yuhu Guo Yingxiang Lei Xiangguo Liu Zhong Liu Minliang Luo Wanju Wen Shuxian Zhu Lihua Yang Chunxiang 《中国科学G辑(英文版)》2003,46(2):131-136
The high-spin states of157Yb have been studied via the reaction of144Sm(16O, 3n) at16O energy of 90 MeV using techniques of in-beam γ-ray spectroscopy. Measurement of γ-γ-t coincidences was performed with 11 BGO(AC)HPGe detectors. Based on the γ-γ coincidence relationships and the measured results
of γ-ray anisotropies and DCO ratios, the level scheme for157Yb was established. The shape co-existence and structural evolution of thevi13/2 band with increasing angular momentum in157Yb have been discussed. The systematics of thevi13/2 bands in theN=87 odd-A isotones have been compared. 相似文献
18.
Y. Zheng X.H. Zhou Y.H. Zhang Y.X. Guo X.G. Lei Z. Liu J.J. He M.L. Liu W.J. Luo S.X. Wen L.H. Zhu C.X. Yang 《The European Physical Journal A - Hadrons and Nuclei》2002,14(2):133-136
The high-spin states of 157Yb have been studied via the 144Sm(16O, 3n) reaction at 16O energy of 90 MeV using techniques of in-beam γ-ray spectroscopy. Measurement of γ-γ-t coincidences was performed with 11 BGO(AC)HPGe detectors. Based on the measured results of γ-γ coincidences, γ-ray anisotropies
and DCO ratios, the level scheme for 157Yb was established. The shape co-existence and structural evolution of the νi
13/2 band with increasing angular momentum in 157Yb have been discussed. The systematics of the νi
13/2 bands in the N = 87 odd-A isotones have been compared.
Received: 7 January 2002 / Accepted: 10 April 2002 相似文献
19.
Néstor Armesto Carlos Pajares Paloma Quiroga-Arias 《The European Physical Journal C - Particles and Fields》2009,62(1):151-157
We study the medium dependence of the multiplicity distributions in the modified leading logarithmic approximation. We focus
in the enhancement in the number of branchings as the partons travel trough a dense medium created in a heavy-ion collision.
We study the effect of a higher number of splittings in some jet observables by introducing the medium as a constant (f
med) in the splitting functions. Having as our ansatz for the quark and gluon jets mean multiplicities 〈n
G
〉=e
γ
y
and 〈n
Q
〉=r
−1e
γ
y
, we study in an analytic approach the dependence with the medium (f
med) of the anomalous dimension (γ), the multiplicity ratio (r), and so the mean multiplicities. We also obtain the higher-order moments of the multiplicity distribution, what allows us
to study its dispersion. 相似文献
20.
V.G. Alpatov Yu.D. Bayukov A.V. Davydov Yu.N. Isaev G.R. Kartashov M.M. Korotkov V.E. Rad'ko A.A. Sadovsky V.M. Samoylov 《Hyperfine Interactions》1997,107(1-4):231-246
The temperature dependence of the 109Ag γ-ray self-absorption was investigated for the horizontal and vertical directions of emission. The source was a single-crystal
silver plate containing atoms of parent radionuclide 109Cd. Gamma-radiation of this γ-source and that of the monitoring γ-source, 57Co, were registered by a pair of Ge(Li)-detectors. As a result of cooling the source from 77 K to ~12 K a relative decrease
was observed of the intensity of the horizontally emitted γ-rays equal to 0.00064±0.00044. For the vertical direction the
corresponding intensity change turned out to be -0.00047±0.00051. Although these data, as one would see, give some evidence
for the possible effect of the gravitation on the resonant γ-ray absorption, future measurements must show if these results
aren’t a consequence of any apparatus effect. The ways for developments in this study are discussed and some hindrances are
considered.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献