共查询到20条相似文献,搜索用时 31 毫秒
1.
Abhijit Bhattacharyya Sanjay K. Ghosh Ritam Mallick Sibaji Raha 《Indian Journal of Physics》2010,84(12):1759-1763
We have studied the v+ $
\bar \nu
$
\bar \nu
→ e
+ + e
− energy deposition rate near a rotating compact star which is important for the study of gamma ray bursts (GRB). The General
relativistic (GR) and rotational effects increase the efficiency of the process immensely. The rotational effect also brings
about an asymmetry in the deposition rate of the star. 相似文献
2.
This paper considers the $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
-symmetric extensions of the equations examined by Cooper, Shepard and Sodano. From the scaling properties of the $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
-symmetric equations a general theorem relating the energy, momentum and velocity of any solitarywave solution of the generalized
KdV equation is derived. We also discuss the stability of the compacton solution as a function of the parameters affecting
the nonlinearities. 相似文献
3.
A. V. Kotikov 《Physics of Particles and Nuclei》2010,41(6):951-953
We show results for the universal anomalous dimension γuni(j) of Wilson twist-2 operators in the $
\mathcal{N}
$
\mathcal{N}
= 4 Supersymmetric Yang-Mills theory in the first three orders of perturbation theory. These expressions are obtained by
extracting the most complicated contributions from the corresponding anomalous dimensions in QCD. 相似文献
4.
Yu. S. Surovtsev T. Branz T. Gutsche V. E. Lyubovitskij 《Physics of Particles and Nuclei》2010,41(6):990-993
In a model-independent approach the data on ππ → ππ, K
$
\bar K
$
\bar K
, ηη, ηη′ in the I
G
J
PC
= 0+0++ channel and on the Kπ scattering in the $
I\left( {J^P } \right) = \frac{1}
{2}\left( {0^ + } \right)
$
I\left( {J^P } \right) = \frac{1}
{2}\left( {0^ + } \right)
channel are analyzed jointly for studying the status and QCD nature of the f
0- and the K*0-mesons. It is shown that in the 1500-MeV region, there are two states, wide (interpreted as a glueball) and narrow (q
$
\bar q
$
\bar q
). In the Kπ-scattering data analysis, the proof for the K*0(900) is given. 相似文献
5.
Jian-Yuan Cheng 《International Journal of Theoretical Physics》2011,50(1):228-232
Parity-time (PT)(\mathcal {P}\mathcal {T}) symmetric Klein-Gordon oscillator is presented using PT\mathcal {P}\mathcal {T}-symmetric minimal substitution. It is shown that wave equation is exactly solvable, and energy spectrum is the same as that
of Hermitian Klein-Gordon oscillator presented by Bruce and Minning. Landau problem of PT\mathcal {P}\mathcal {T}-symmetric Klein-Gordon oscillator is discussed. 相似文献
6.
R. N. Kyutt M. P. Shcheglov V. V. Ratnikov A. E. Nikolaev 《Physics of the Solid State》2009,51(9):1789-1795
The structural state of GaN epitaxial layers grown on r-plane sapphire through metal-organic vapor phase epitaxy has been investigated using X-ray diffraction. The interplanar spacings
in two directions in the (11$
\bar 2
$
\bar 2
0) plane of the interface and in the direction perpendicular to it, as well as the diffraction peaks in the ϑ and ϑ-2ϑ scan
modes in the Bragg and Laue geometries, are measured on double- and triple-crystal diffractometers. The intensity distribution
maps for asymmetric Bragg reflections are constructed for two azimuthal positions of the sample. An analysis of the data obtained
has demonstrated that the elastic strain is anisotropic and that the X-ray diffraction pattern parallel to the interface plane
is broadened. The layers are contracted in the [1$
\bar 1
$
\bar 1
00] direction and unstrained in the [0001] direction. The broadening of the Bragg reflections in the [1$
\bar 1
$
\bar 1
00] direction is considerably larger than that in the [0001] direction. It is shown using the Williamson-Hall plots for the
Bragg and Laue reflections that these broadenings are not related to different degrees of mosaicity but are determined by
the local dilatations and misorientations around defects. The data obtained are analyzed, and the conclusions regarding the
dislocation structure of the samples are drawn. 相似文献
7.
N. Bili C. A. Dominguez B. Guberina 《The European Physical Journal C - Particles and Fields》2005,39(3):351-358
We calculate theB parameter for
mixing in the framework of QCD sum rules for a three-point function involving pseudoscalar currents, and contrast our results
with other calculations. We findB=0.5±0.1±0.2, where the first error reflects uncertainties in the various QCD parameters and the second one is an estimate
of uncalculated three-loop radiative and higher order quark mass corrections. 相似文献
8.
The channels of disorder-order phase transitions through which there can arise orthorhombic (space group Pbcn) β′-W2C, rhombohedral (space group P
$
\bar 3
$
\bar 3
m1)β″-W2C, and trigonal (space group P
$
\bar 3
$
\bar 3
1m)ɛ-W2C superstructures of the disordered lower hexagonal carbide β-W2C have been determined. The distribution functions of carbon atoms in the superstructures under consideration have been calculated,
and the physically admissible sequence of transformations associated with the ordering of the lower carbide β-W2C that occur with a decrease in the temperature has been established. 相似文献
9.
Natural coir fibers, subjectd to thermal treatments in the range of 0°C to 200°C and alkali treatment with 5% to 30% concentration
w/w, have been used in the present investigation to determine the interlayer variability of the cellulose planes (020), (110)
and (1$
\bar 1
$
\bar 1
0). Among the equatorial reflections (110), (1$
\bar 1
$
\bar 1
0) and (020), the extent of variability is found to be more with the proportion of such affected planes less for (020) reflection
in the native cellulose at lower temperature while at higher temperature (110) and (1$
\bar 1
$
\bar 1
0) become more affected by variability defect. (110) and (1$
\bar 1
$
\bar 1
0) planes are more affected also with alkali treatment. 相似文献
10.
Properties of neutral charmed mesons in <Emphasis Type="Italic">pA</Emphasis> interactions at 70 GeV
V. N. Ryadovikov 《Physics of Atomic Nuclei》2011,74(2):324-331
The results of data handling for the E-184 experiment involving the irradiation of the active target, consisting of carbon,
silicon, and lead plates by a 70-GeV proton beam are presented. When the two-prong neutral charmed meson decay signal was
selected and the cross section for charm production at a near-threshold energy was estimated (σ(c
$
\bar c
$
\bar c
) = 7.1 ± 2.4(stat.) ± 1.4(syst.) μb/nucleon), some properties of D
0 and $
\bar D^0
$
\bar D^0
were investigated. These include the atomic-weight dependence of the cross section on the target mass number (its A dependence); the differential cross sections dσ/dp
t
2 and dσ/dx
F; and the dependence of the parameter α on x
F, p
t
2, and p
lab. The experimental results are compared with the predictions of the FRITIOF7.02 program. 相似文献
11.
Yu. V. Solov’eva S. V. Starenchenko V. A. Starenchenko 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(2):202-206
The creep in Ni3Ge alloy single crystals with strain axis orientations of [001], [$
\bar 1
$
\bar 1
39], [$
\bar 2
$
\bar 2
34], and [$
\bar 1
$
\bar 1
22] was investigated. It was found that changes in strain axis orientation that lead to cubic slip increase the creep resistance
of Ni3Ge alloy single crystals. 相似文献
12.
Multiplicity distributions of secondary hadrons produced in p
$
\bar p
$
\bar p
and collisions are very different. There are three types of inelastic processes in p
$
\bar p
$
\bar p
scattering. The first one is the production of a shower of secondary hadrons in gluon string decay. The second one is the
shower produced from the decay of two quark strings, and the third one is the shower produced from the decay of three quark
strings. At the same time, there are just two types of inelastic processes for pp scattering: the shower from the gluon string and the shower from two quark strings. The multiplicity distribution and the
average multiplicity of charged hadrons for an energy of 14 TeV are predicted. 相似文献
13.
Utilizing the Baym-Kadanoff formalism with the polarization function calculated in the random phase approximation, the dynamics
of the ν = 0 quantum Hall state in bilayer graphene is analyzed. Two phases with nonzero energy gap, the ferromagnetic and
layer asymmetric ones, are found. The phase diagram in the plane ($
\bar \Delta _0
$
\bar \Delta _0
, B), where $
\bar \Delta _0
$
\bar \Delta _0
is a top-bottom gates voltage imbalance, is described. It is shown that the energy gap scales linearly, ΔE ∼ 14B [T] K, with magnetic field. 相似文献
14.
The results of the calculation of electron bands of bound states that cross the edge of the continuous spectrum for the (001)
fcc copper monolayer are presented for the first time. The calculations are performed in the local approximation for the exchange
and correlations using the film variant of the Green’s function technique. Symmetry of electron states near the edge of the
continuous spectrum is explored. It is found that there are bound states along the $
\bar \sum
$
\bar \sum
direction of the two-dimensional Brillouin zone of the Cu(001) monolayer that are embedded in the continuum of delocalized
states of the continuous spectrum. Along the $
\bar \Delta
$
\bar \Delta
and $
\bar Y
$
\bar Y
directions, bands of bound states turn into resonance states after crossing the edge of the continuous spectrum. 相似文献
15.
Measuring the $
\bar \nu _e
$
\bar \nu _e
component of the cosmic diffuse supernova neutrino background (DSNB) is the next ambitious goal for low-energy neutrino astronomy.
The largest flux is expected in the lowest accessible energy bin. However, for E ≲ 15 MeV a possible signal can be mimicked by a solar $
\bar \nu _e
$
\bar \nu _e
flux that originates from the usual 8B neutrinos by spin-flavor oscillations. We show that such an interpretation is possible within the allowed range of neutrino
electromagnetic transition moments and solar turbulent field strengths and distributions. Therefore, an unambiguous detection
of the DSNB requires a significant number of events at E ≳ 15 MeV. 相似文献
16.
A. V. Anisovich V. V. Anisovich M. A. Matveev V. A. Nikonov J. Nyiri A. V. Sarantsev 《Physics of Atomic Nuclei》2010,73(7):1254-1265
We consider as an example the two-pion decay of the ρ meson, the 3
S
1
q
$
\bar q
$
\bar q
state of the constituent quarks—the decay being determined by the transition q
$
\bar q
$
\bar q
→ ππ contains information about confinement interactions. One can specify in this decay two types of transitions: (i) the bremsstrahlung
radiation of a pion q → q + π (or $
\bar q
$
\bar q
→ $
\bar q
$
\bar q
+ π) with a subsequent fusion q
$
\bar q
$
\bar q
→ π, and (ii) the direct transition q
$
\bar q
$
\bar q
→ ππ. We demonstrate how in the amplitudes of the corresponding transitions the quark singularities have to disappear, i.e., what
is the way the quark confinement at relatively short distances can be realized. We calculate and estimate the contributions
of processes with bremsstrahlung radiation of the pion and of the direct transition q
$
\bar q
$
\bar q
→ ππ. The estimates demonstrate that the processes involving the direct transition q
$
\bar q
$
\bar q
→ ππ are necessary, but they cannot be determined unambiguously by the decay ρ(775) → ππ. We conclude that for the determination of the q
$
\bar q
$
\bar q
→ ππ transition more complete data on the resonance decays into the ππ channels are needed than those available at the moment. 相似文献
17.
High-statistics Belle data on the γγ → π0η reaction have been analyzed in order to reveal the mechanism of two-photon production and the nature of the a
0(980) resonance. The solution obtained for the γγ → π0η amplitude is in agreement with the predictions of the chiral theory for the πη-scattering length; with the strong coupling
of the a
0(980) resonance with the πη, K
$
\bar K
$
\bar K
, and πη′ channels; and with the key role of the a
0(980) → (K
$
\bar K
$
\bar K
+ π0η + π0η′) → γγ rescattering mechanisms in the a
0(980) → γγ decay. This picture is much in favor of the q
2
$
\bar q
$
\bar q
2 nature of a
0(980) resonance and is consistent with the properties of its partners, σ0(600) and f
0(980) resonances, in particular, with those manifested in the γγ → ππ reactions. The important role of vector exchanges in
the formation of the nonresonant background in the γγ → π0η reaction has been revealed. Preliminary information on the π0η → π0η reaction has been obtained. 相似文献
18.
This study determined the contribution of Martian topography and the density jump at the Mohorovicic discontinuity (M) to the gravity in a quadratic approximation. It also resolved the problem of determining the possible depths of compensation
for topography harmonics of various degrees and orders. It shows that all the topography compensation is within the depth
range from 0 to 1400 km. Different topographic irregularities are most likely to be compensated at depths that correspond
to the upper crust ($
\bar d = 4.5 \pm 3.7{\text{ km}}
$
\bar d = 4.5 \pm 3.7{\text{ km}}
), crust-mantle transition layer ($
\bar d = 78 \pm 24{\text{ km}}
$
\bar d = 78 \pm 24{\text{ km}}
), lithospheric boundary ($
\bar d = 200 \pm 34{\text{ km}}
$
\bar d = 200 \pm 34{\text{ km}}
), upper-middle mantle transition layer ($
\bar d = 400 \pm 70{\text{ km}}
$
\bar d = 400 \pm 70{\text{ km}}
), or middle-lower mantle transition layer ($
\bar d = 1120 \pm 180{\text{ km}}
$
\bar d = 1120 \pm 180{\text{ km}}
). This paper presents the lateral distributions of compensation masses for these depths and the respective maps. According
to calculations, stresses in the Martian crust and mantle may be as high as 108 Pa. This paper shows that the topographic anomalies of the Tharsis volcanic plateau and the symmetric formation in the eastern
hemisphere could have originated and be dynamically maintained by two plumes of melted mantle substance enriched with fluids;
these plumes may have their origin at the boundary of the lower mantle. 相似文献
19.
《The European Physical Journal C - Particles and Fields》2007,50(2):315-328
The inclusive production cross sections of the strange vector mesons K*0, K̄*0, and φ have been measured in interactions of 920 GeV protons with C, Ti, and W targets with the HERA-B detector at the HERA
storage ring. Differential cross sections as a function of rapidity and transverse momentum have been measured in the central
rapidity region and for transverse momenta up to pT = 3.5 GeV/c. The atomic number dependence is parametrised as σpA=σpN*Aα, where σpN is the proton–nucleon cross section. Within the phase space accessible, α(K*0)=0.86±0.03, α(K̄*0)=0.87±0.03, and α(φ)=0.96±0.02. The total proton–nucleon cross sections, determined by extrapolating the differential measurements
to full phase space, are σpN→K*0=(5.06±0.54) mb, σpN→K̄*0=(4.02±0.45) mb, and σpN→φ=(1.17±0.11) mb. For all resonances the Cronin effect is observed; compared to the measurements of Cronin et al. for K± mesons, the measured values of α for φ mesons coincide with those of K+ mesons for all transverse momenta, while the enhancement for K*0/K̄*0 mesons is smaller. 相似文献
20.
Using computer simulation, the failure mechanism of an fcc silver crystal under (111)〈$
\bar 2
$
\bar 2
〉 shear deformation is studied and the direction of unstable atomic displacement under the conditions of dynamic stability
violation is determined. It is shown that the most dangerous direction of atomic motion, which makes the crystal structurally
unstable, does not completely coincide with the 〈$
\bar 2
$
\bar 2
〉 direction lying in the (111) plane and has a component normal to the [111] direction. 相似文献