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1.
Corrections of order α
5 and α
6 to the hyperfine structure of S- and P-wave energy levels of the muonic-helium ion are calculated. Electron-vacuum-polarization effects, corrections for the nuclear
structure, and recoil effects are taken into account. The numerical values obtained for respective hyperfine splitting, −1334.73
meV (1S), −166.64 meV (2S), −58 712.90 μeV (2P
1/2), and −24 290.69 μeV (2P
3/2), can be viewed as a reliable estimate for a comparison with experimental data, and the hyperfine-structure interval of Δ12 = 8ΔE
hfs(2S) − ΔE
hfs(1S) = 1.59 meV can be used to test QED predictions. 相似文献
2.
I. L. Drichko I. Yu. Smirnov A. V. Suslov O. A. Mironov D. R. Leadley 《Journal of Experimental and Theoretical Physics》2010,111(3):495-502
Magnetoresistivity ρ
xx
and ρ
xy
and the acoustoelectronic effects are measured in p-Si/SiGe/Si with an impurity concentration p = 1.99 × 1011 cm−2 in the temperature range 0.3–2.0 K and an tilted magnetic field up to 18 T. The dependence of the effective g factor on the angle of magnetic field tilt θ to the normal to the plane of a two-dimensional p-Si/SiGe/Si channel is determined. A first-order ferromagnet-paramagnet phase transition is observed in the magnetic fields
corresponding to a filling factor ν = 2 at θ ≈ 59°–60°. 相似文献
3.
I. V. Ovchinnikov T. A. Ivanova A. N. Turanov R. R. Garipov 《Physics of the Solid State》2009,51(10):2058-2063
Significant differences in the manifestation of spin-crossover properties of the mesogen compounds [FeL
2]X with oxysalicylidene-N′-ethyl-N-ethylenediamine ligands L and anions X = PF6− and SCH− have been found by means of electron paramagnetic resonance. The electron paramagnetic resonance data and the quantum-chemical
calculation within the density functional theory enables us to establish that the observed specific features are associated
with the incorporation of the SCH− ion into the first coordination sphere of the Fe(III) ion. The role of the transition of the material to the liquid-state
phase in the formation of a low-dimensional (two-dimensional) structure with stronger intermolecular interactions has been
revealed. 相似文献
4.
A comparative investigation of the magnetic properties of amorphous nanogranular composites (Co41Fe39B20)
x
(SiO
n
)100 − x
and (Co86Nb12Ta2)
x
(SiO
n
)100 − x
has been performed in the subpercolation region at temperatures in the range 4.2–300 K. The thermomagnetic dependences in
the range 4.2–300 K and the processes of magnetization reversal and remanent magnetization relaxation at liquid-helium temperatures
have been studied. It has been established that the average anisotropy constants of amorphous nanograins are equal to 3.6–7.0
kJ/m3 for the (Co41Fe39B20)
x
(SiO
n
)100 − x
composites and 5–8 kJ/m3 for the (Co86Nb12Ta2)
x
(SiO
n
)100 − x
composites. The fundamental differences in the concentration dependences of the anisotropy constant K
eff and the coercive force H
C
have been revealed for the two systems under investigation. It has been demonstrated that, as the concentration of the metal
phase increases, the quantities K
eff and H
C
increase for the (Co86Nb12Ta2)
x
(SiO
n
)100 − x
composites and decrease for the (Co41Fe39B20)
x
(SiO
n
)100 − x
composites. 相似文献
5.
The dielectron widths of Y(nS)(n = 1, …, 7) and vector decay constants are calculated using the relativistic string Hamiltonian with a universal interaction.
For Y(nS) (n = 1, 2, 3) the dielectron widths and their ratios are obtained in full agreement with the latest CLEO data. For Y(10580)
and Y(11020) a good agreement with experiment is reached only if the 4S-3D mixing (with a mixing angle θ = 27°± 4°) and 6S-5D mixing (with θ = 40°±5°) are taken into account. The possibility to observe higher “mixed D-wave” resonances, $
\tilde \Upsilon
$
\tilde \Upsilon
(n
3
D
1) with n = 3, 4, 5 is discussed. In particular, $
\tilde \Upsilon
$
\tilde \Upsilon
(≈11120), originating from the pure 53
D
1 state, can acquire a rather large dielectron width, ∼130 eV, so that this resonance may become manifest in the e
+
e
− experiments. On the contrary, the widths of pure D-wave states are very small, Γ
ee
(n
3
D
1)≤ 2 eV. 相似文献
6.
7.
In the Friedmann cosmology, the deceleration of the expansion q plays a fundamental role. We derive the deceleration as a function of redshift q(z) in two scenarios: ΛCDM model and modified Chaplygin gas (MCG) model. The function for the MCG model is then fitted to the cosmological data in
order to obtain the cosmological parameters that minimize χ
2. We use the Fisher matrix to construct the covariance matrix of our parameters and reconstruct the q(z) function. We use Supernovae Ia, WMAP5, and BAO measurements to obtain the observational constraints. We determined the present
acceleration as q
0 = − 0.65 ±0.19 for the MCG model using the Union2 dataset of SNeIa, BAO, and CMB and q
0 = − 0.67 ±0.17 for the Constitution dataset, BAO and CMB. The transition redshift from deceleration to acceleration was found
to be around 0.80 for both datasets. We have also determined the dark energy parameter for the MCG model: Ω
X0 = 0.81 ±0.03 for the Union2 dataset and Ω
X0 = 0.83 ±0.03 using the Constitution dataset. 相似文献
8.
Cosmological models with variable G in C-field cosmology for barotropic fluid distribution in FRW space-time are investigated. To get the deterministic model of the
universe, we have assumed that G=R
n
where R is the scale factor and n the constant. To obtain the results in terms of cosmic time t, we have assumed n=−1. We find that for n=−1, Creation field (C) and spatial volume increase with time, G and ρ (matter density) decreases with time, the model represent accelerating universe. Thus inflationary scenario exists in the
model. The model is also free from horizon. The results so obtained match with the astronomical observations. 相似文献
9.
Restricted active space (RAS) configuration interaction (CI) approach is employed to compute the P,T-odd interaction constant W
d for the ground (2Σ1/2) state of YbF molecule. The present estimate of W
d = −1.164 × 1025 Hz/e-cm is expected to provide a reliable limit on the electron’s electric dipole moment (EDM), d
e. 相似文献
10.
N. Kh. Dzhemilev S. F. Kovalenko L. F. Lifanova S. E. Maksimov Sh. T. Khozhiev 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(7):910-914
The spectra of kinetic energies of positive Si
n
O
m
+ cluster ions (n = 2–5, m = 2–7) have been measured using a double focusing ion microanalyzer with reverse geometry at instants 10−5 to 10−4 s after emission. The dissociation energies have been determined within the evaporative ensemble model and the theory of
unimolecular decay reactions. The results obtained are compared with the binding energies of neutral Si
n
O
m
clusters. 相似文献
11.
A. T. Burkov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(10):1392-1394
Results on the experimentally investigated dependence of the electrical resistivity of quasibinary alloys R
x
Y1−x
Co2, where R stands for magnetic rare earth elements, on temperature (2–300 K), composition (x = 0–1), and magnetic field (0–15 T) are presented. Non-Fermi liquid behavior of electrical resistivity in a magnetic field
was observed in paramagnetic Gd
x
Y1−x
Co2 alloys. The relative magneto-thermopower of these alloys exhibits diverging behavior with decreasing temperature, indicating
anomalous temperature variation of the thermopower in the non-Fermi liquid regime. 相似文献
12.
One of the well-known effects of the asymptotic freedom is splitting of the leading-log BFKL pomeron into a series of isolated
poles in complex angular momentum plane. Following our earlier works we explore the phenomenological consequences of the emerging
BFKL-Regge factorized expansion for the small-x charm (F
2
c
) and beauty (F
2
b
) structure functions of the proton. As we found earlier, the colordipole approach to the BFKL dynamics predicts uniquely
decoupling of subleading hard BFKL exchanges from F
2
c
at moderately large Q
2. We predicted precocious BFKL asymptotics of F
2
c
(x,Q
2) with intercept of the rightmost BFKL pole α
P(0) − 1 = ΔP ≈ 0.4. High-energy open beauty photo- and electroproduction probes the vacuum exchange at much smaller distances and detects
significant corrections to the BFKL asymptotics coming from the subleading vacuum poles. In view of the accumulation of the
experimental data on small −x
F
2
c
and F
2
b
we extended our early predictions to the kinematical domain covered by new HERA measurements. Our structure functions obtained
in 1999 agree well with the determination of both F
2
c
and F
2
b
by the H1 published in 2006 but contradict very recent (2008, preliminary)H1 results on F
2
b
. We present also comparison of our early predictions for the longitudinal structure function F
L
with recent H1 data (2008) taken at very low Bjorken x. We comment on the electromagnetic corrections to the Okun-Pomeranchuk theorem. 相似文献
13.
E. V. Bogdanov N. B. Brandt N. Ya. Minina S. S. Shirokov A. E. Yunovich 《Moscow University Physics Bulletin》2010,65(5):402-406
New experimental data are presented on the effects of uniaxial compression of up to 4 kbar along the [110] and [1$
\bar 1
$
\bar 1
0] crystallographic directions on the spectra of electroluminescence and the current-voltage characteristics of diodes based
on n-Al
x
Ga1 − x
As/GaAs
y
P1 − y
/p-Al
x
Ga1 − x
As (y = 0.84) heterostructures that were designed for injection lasers. With increasing pressure, the spectra show a shift to shorter
wavelengths, reaching 25 meV at 3 kbar; the intensity increases 2–3 times as well. Numerical calculations were carried out
on the band structure of the investigated heterostructures under compression along the [110] axis, which indicate the increase
in the effective band gap in the quantum well (QW) GaAs
y
P1 − y
, with a pressure coefficient of about 8.5 meV/kbar and reduction of the barrier height at the boundaries of the QW. The calculations
predict the possibility that light and heavy holes crossover at pressures above 4.5–5 kbar. The increase in the effective
band gap completely describes the experimental data on the shift of the electroluminescence spectra. The mixing of light and
heavy holes when approaching the band crosspoint is the probable cause of an increase in the intensity of radiation under
uniaxial compression. 相似文献
14.
M. Hamani Daouda Manuel E. Rodrigues M. J. S. Houndjo 《The European Physical Journal C - Particles and Fields》2012,72(2):1893
We develop the reconstruction of the f(T) gravity model according to the holographic dark energy. T is the torsion scalar and its initial value from the teleparallel gravity is imposed for fitting the initial value of the
function f(T). The evolutionary nature of the holographic dark energy is essentially based on two important parameters, Ω
V
and ω
V
, respectively, the dimensionless dark energy and the parameter of the equation of state, related to the holographic dark
energy. The result shows a polynomial function for f(T), and we also observe that, when Ω
V
→1 at the future time, ω
V
may cross −1 for some values of the input parameter b. Another interesting aspect of the obtained model is that it provides a unification scenario of dark matter with dark energy. 相似文献
15.
V. E. Tarasov V. V. Khabarov A. E. Kudryavtsev V. M. Weinberg 《Physics of Atomic Nuclei》2008,71(8):1410-1423
The Kd reactions are considered in the impulse approximationwithNN final-state interactions (FSI) taken into account. Realistic parameters for the KN phase shifts are used. The “quasi-elastic” energy region, in which the elementary KN interaction is predominantly elastic, is considered. The theoretical predictions are compared with the data on the K
+
d → K
+
pn, K
+
d → K0
pp, K
+
d → K
+
d, and K
+
d total cross sections. The NN FSI effect in the reaction K
+
d → K
+
pn has been found to be large. The predictions for the Kd cross sections are also given for slow kaons, produced from ϕ(1020) decays, as the functions of the isoscalar KN scattering length a
0. These predictions can be used to extract the value of a
0 from the data.
The text was submitted by the authors in English. 相似文献
16.
C. Bernal J. A. O. Rodrigues A. P. P. Guimarães A. O. Ribeiro K. T. de Oliveira H. Imasato J. R. Perussi 《Laser Physics》2011,21(1):245-249
The genus Candida includes different species that have the potential to invade and colonize the human body and C. albicans is the most common cause of skin, nail and mucous infections. The increasing resistance against antifungal drugs has renewed
the search for new treatment procedures and antimicrobial photodynamic inactivation (PDI) is a propitious candidate. Hypericin
(HY) has several wanted properties to be used as a photosensitizer in this technique including a high quantum yield of singlet
oxygen generation, a high extinction coefficient near 600 nm, and a relatively low dark toxicity. Although the phototoxicity
of HY on several tumor cells has been reported, the data concerning its photoactivity on microorganisms are scarce. The aim
of this study was to obtain the experimental parameters to achieve an acceptable selective hypericinphotoinactivation of two
species of Candida comparing with fibroblasts and epithelial cells which are the constituents of some potential host tissues, such mucosas,
skin and cavities. Microorganisms and cells were incubated with the same HY concentrations and short incubation time followed
by irradiation with equal dose of light. The best conditions to kill just Candida were very low HY concentration (0.1–0.4 μg ml−1) incubated by 10 min and irradiated with LED 590 nm with 6 J cm−2. 相似文献
17.
The conductivity of poly(N-vinylimidazole) (PVIM) and its fluoroborate salt (PVIM–HBF4) are reported here. N-vinylimidazole is polymerized by free radical method and PVIM–HBF4 is prepared by acidification of PVIM with HBF4. The polyelectrolyte so formed has been characterized by infrared, hydrogen-1 nuclear magnetic resonance, thermogravimetric
analyzer, and differential scanning calorimetry. Frequency and temperature dependence of AC conductivity has been studied
to learn about the electrical conduction behavior in the materials. The electrical conductivity of the new material is found
to be in the range of 10−5 to 10−6 S cm−1.There is about 102- to 103-fold increase in conductivity of the polyelectrolyte. The material is shown to be a predominantly ionic conductor with t
ion ≈ 0.88. Apparent activation energies are found to be 0.397 and 0.250 eV for the polymer and the polyelectrolyte, respectively. 相似文献
18.
T. B. Charikova N. G. Shelushinina G. I. Kharus O. E. Sochinskaya A. A. Ivanov 《Physics of the Solid State》2009,51(11):2229-2234
The temperature dependences of the resistivity of single-crystal films of the Nd2 − x
Ce
x
CuO4 + δ
n-type superconductors with x = 0.14 (underdoped region) and x = 0.15 (optimal doping region) and different degrees of disorder δ have been investigated in various magnetic fields (B ‖ c, J ‖ ab) in the temperature range 0.4–300 K. It has been demonstrated that there are differences in the behavior of the dependences
of the slope of the upper critical field $
(dB_{c2} /dT)_{T \to T_c }
$
(dB_{c2} /dT)_{T \to T_c }
on the disorder parameter for the underdoped samples (x = 0.14) and the samples with the optimal doping (x = 0.15). The study of the dependence of the slope of the upper critical field on the degree of disorder has made it possible
to discriminate experimentally between the superconductors with the d pairing and anisotropic s pairing. It has been revealed that the relative stability of the n-type superconductor with the optimal doping with respect to disordering is possibly due to the strong anisotropy of impurity
scattering with symmetry of the d type. 相似文献
19.
P. Castorina D. E. Miller H. Satz 《The European Physical Journal C - Particles and Fields》2011,71(6):1673
We consider deconfined matter in SU(N) gauge theory as an ideal gas of transversely polarized quasi-particle modes having a temperature-dependent mass m(T). Just above the transition temperature, the mass is assumed to be determined by the critical behavior of the energy density
and the screening length in the medium. At high temperature, it becomes proportional to T as the only remaining scale. The resulting (trace anomaly based) interaction measure Δ=(ϵ−3P)/T
4 and energy density are found to agree well with finite temperature SU(3) lattice calculations. 相似文献
20.
In this proceeding we present the nested Bethe ansatz for open spin chains of XXX-type, with arbitrary representations (i.e.
“spins”) on each site of the chain and diagonal boundary matrices (K
+(u), K
−(u)). The nested Bethe ansatz applies for a general K
−(u), but a particular form of the K
+(u) matrix. We give the eigenvalues, Bethe equations and the form of the Bethe vectors for the corresponding models. The Bethe
vectors are expressed using a trace formula 相似文献