共查询到20条相似文献,搜索用时 15 毫秒
1.
D. Arnaudon N. Crampé A. Doikou L. Frappat É. Ragoucy J. Avan 《Czechoslovak Journal of Physics》2004,54(11):1153-1158
We consider open spin chains based on osp(M2n) Yangians and solve the reflection equations for some classes of reflection matrices, including the diagonal ones. Having then integrable open spin chains, we write the analytical Bethe Ansatz equations. More details and references can be found in D. Arnaudon et al.: Nucl. Phys B 668 (2003) 469 and 687 (2004) 257. 相似文献
2.
The structure of the nucleon charge-exchange process n + p → p + n is investigated basing on the isotopic invariance of the nucleon-nucleon scattering. Using the operator of permutation of
the spin projections of the neutron and proton, the connection between the spin matrices, describing the amplitude of the
nucleon charge-exchange process at zero angle and the amplitude of the elastic scattering of the neutron on the proton in
the “backward” direction, has been considered. Due to the optical theorem, the spin-independent part of the differential cross
section of the process n + p → p + n at zero angle for unpolarized particles is expressed through the difference of total cross sections of unpolarized proton-proton
and neutron-proton scattering. Meantime, the spin-dependent part of this cross section is proportional to the differential
cross section of the deuteron charge-exchange breakup d + p → (pp) + n at zero angle at the deuteron momentum k
d
= 2 k
n
(k
n
is the initial neutron momentum). Analysis shows that, assuming the real part of the spin-independent term of the “forward”
amplitude of the process n + p → p + n to be smaller or of the same order as compared with the imaginary part, in the wide range of neutron laboratory momenta k
n
> 700 MeV/c the main contribution into the differential cross section of the process n + p → p + n at zero angle is provided namely by the spin-dependent term. 相似文献
3.
S. G. Petrosyan A. M. Khanbekyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2017,52(3):281-285
The photocurrent induced by the local excitation of the light beam focused up to 0.17 μm on the surface of a semiconductor element in the planar structure with two p–n junctions, that is, with the use of the so-called scanning laser microscopy technique, has been studied experimentally. The linear dependence of the photocurrent on the coordinate of the beam center is obtained. The high sensitivity of the structure enables to detect the displacement of the order of tens nanometers. 相似文献
4.
5.
We establish some general theorems for the existence and nonexistence of ground state solutions of steady-state N coupled nonlinear Schrödinger equations. The sign of coupling constants β ij ’s is crucial for the existence of ground state solutions. When all β ij ’s are positive and the matrix Σ is positively definite, there exists a ground state solution which is radially symmetric. However, if all β ij ’s are negative, or one of β ij ’s is negative and the matrix Σ is positively definite, there is no ground state solution. Furthermore, we find a bound state solution which is non-radially symmetric when N=3. 相似文献
6.
7.
Xiang Liu Zheng-Tao Wei Xue-Qian Li 《The European Physical Journal C - Particles and Fields》2009,59(3):683-689
To test the validity of perturbative QCD (pQCD) and investigate its range of application, one should look for a suitable process.
B→J/ψ
D is a promising candidate. The linear momentum of the products is relatively small, so that there may exist a region where
exchanged gluons are soft and the perturbative treatment may fail, so that the non-perturbative effect would be significant.
We attribute such non-perturbative QCD effects to the long-distance final-state interaction (FSI) which is estimated in this
work. We find that the contribution from the FSI to the branching ratio is indeed sizable and may span the rather wide range
of 10−6∼10−5 and cover a region where the pQCD prediction is of the same order. A more accurate measurement of its branching ratio may
provide important information about the application region of pQCD and help to clarify the picture of inelastic rescattering
(i.e. FSI), which is generally believed to play an important role in B decays. 相似文献
8.
B. Song Y. Yong J. Hou P. He 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,59(3):399-406
Density-functional theory with generalized gradient approximation for the exchange-correlation potential has been used to
calculate the structural and electronic properties of
Si
n
C
n
(n = 10–15) clusters. We find that the Si
n
C
n
clusters prefer cagelike structures. An extensive isomer search shows that the lowest-energy arrangements are those in which
the silicon atoms and the carbon atoms form two distinct subunits. It is found that the carbon atoms favor to form fullerene-like
structure due to the
sp
2-like bond. The silicon atoms are trying to cope with an unfavorable
sp
2 environment, but distorted tetrahedra still show up somewhere of the cagelike structures. On the basis of the lowest-energy
geometries obtained, the binding energy, HOMO–LUMO gap, Mulliken charge, ionization potential and electron affinity of the
clusters have been computed and analyzed. An electronic charge transfer from the Si-populated to the C-populated regions is
observed. 相似文献
9.
The process γ*γ → σ is investigated in the framework of the SU(2)×SU(2) chiral NJL model. The form factor of the process is derived for arbitrary virtuality of γ* in the Euclidean kinematic domain. The asymptotic behavior of this form factor resembles the asymptotic behavior of the γ*γ → π form factor. 相似文献
10.
Bastian Kubis Sebastian P. Schneider 《The European Physical Journal C - Particles and Fields》2009,62(3):511-523
Strong final-state interactions create a pronounced cusp in η′→η
π
0
π
0 decays. We adapt and generalize the non-relativistic effective field theory framework developed for the extraction of π
π scattering lengths from K→3π decays to this case. The cusp effect is predicted to have an effect of more than 8% on the decay spectrum below the π
+
π
− threshold. 相似文献
11.
In the present paper we propose a further modification of f(R, T)-gravity (where T is trace of the energy-momentum tensor) by introducing higher derivatives matter fields. We discuss stability conditions in the proposed theory and find restrictions for the parameters to prevent appearance of main type of instabilities, such as ghost-like and tachyon-like instabilities. We derive cosmological equations for a few representations of the theory and discuss main differences with conventional f(R, T)-gravity without higher derivatives. It is demonstrated that in the theory presented inflationary scenarios appear quite naturally even in the dust-filled Universe without any additional matter sources. Finally, we construct an inflationary model in one of the simplest representation of the theory, calculate the main inflationary parameters and find that it may be in quite good agreement with observations. 相似文献
12.
The aim of this paper is to analyze the nature of anisotropic spherically symmetric relativistic star models in the framework of f(R, T) gravity. To discuss the features of compact stars, we consider that in the interior of the stellar system, the fluid distribution is influenced by MIT bag model equation of state. We construct the field equations by employing Krori–Barua solutions and obtain the values of unknown constants with the help of observational data of Her X-1, SAX J 1808.4-3658, RXJ 1856-37 and 4U1820-30 star models. For a viable f(R, T) model, we study the behavior of energy density, transverse as well as radial pressure and anisotropic factor in the interior of these stars for a specific value of the bag constant. We check the physical viability of our proposed model and stability of stellar structure through energy conditions, causality condition and adiabatic index. It is concluded that our model satisfies the stability criteria as well as other physical requirements, and the value of bag constant is in well agreement with the experimental value which highlights the viability of our considered model. 相似文献
13.
14.
K. Saaidi S. W. Rabiei A. Aghamohammadi 《International Journal of Theoretical Physics》2011,50(8):2514-2519
We study spherically symmetric static empty space solutions in R+ε/R model of f(R) gravity. We show that the Schwarzschild metric is an exact solution of the resulted field equations and consequently there
are general solutions which are perturbed Schwarzschild metric and viable for solar system. Our results for large scale contains
a logarithmic term with a coefficient producing a repulsive gravity force which is in agreement with the positive acceleration
of the universe. 相似文献
15.
16.
Bochao?Liu Markus?Büscher Feng-Kun?Guo Christoph?Hanhart Ulf-G.?Mei?ner 《The European Physical Journal C - Particles and Fields》2009,63(1):93-99
We investigate the interplay between crossed channel final state interactions and the constraints from two-particle unitarity
for the reactions J/ψ→V
π
π and
VK[`(K)]VK\bar{K}
, where V is either ω or φ. Using a model where the parameters are largely constrained by other sources, we find that, although small, crossed channel
final state interaction can influence the amplitudes considerably, in special areas of phase space. These results cast doubt
on the inapplicability of unitarity constraints on production amplitudes as recently claimed in the literature. 相似文献
17.
The rare decay \(B\rightarrow {K^{*}}\ell ^+\ell ^-\) is a very significant mode to search for physics beyond the Standard Model (SM). The mode provides a very rich spectrum of observables obtained from the angular distribution of its decay products. The recent LHCb measured values of these observables are used to conclude an evidence of right-handed currents at the kinematic endpoint of this decay mode. As the conclusion is drawn at the maximum dilepton invariant mass square (\(q^2\)) kinematic endpoint, it relies only on heavy quark symmetries where it is valid without significant corrections. 相似文献
18.
In the context of the so-called Gauss–Bonnet gravity, where the gravitational action includes function of the Gauss–Bonnet
invariant, we study cosmological solutions, especially the well-known ΛCDM model. It is shown that the dark energy contribution and even the inflationary epoch can be explained in the frame of
this kind of theories with no need of any other kind of component. Other cosmological solutions are constructed and the rich
properties that this kind of theories provide are explored. 相似文献
19.
Two-and three-body decays of γ(5S) into BB, BB*, B*B*, B
s
B
s
, B
s
B
s
*, and BB*π, B*B*π are evaluated using the theory developed earlier for dipion-bottomonium transitions. The theory contains only two parameters—vertex
masses M
br
and M
ω—known from the dipion spectra and width. Predicted values of Γtot(5S) and six partial widths Γ
k
(5S), k = BB, BB*, ... are in agreement with the experiment. The decay widths Γ5S
(πBB*) and Γ5S
(πB*B*) are also calculated and found to be on the order of 10 keV.
The text was submitted by the authors in English. 相似文献
20.
M. Farasat Shamir 《International Journal of Theoretical Physics》2011,50(3):637-643
The main purpose of this paper is to study the exact solution of Bianchi type III spacetime in the context of metric f(R) gravity. The field equations are solved by taking expansion scalar θ proportional to shear scalar σ which gives C=A
n
, where A and C are the metric coefficients. The physical behavior of the solution has been discussed using some physical quantities. Also,
the function of the Ricci scalar is evaluated. 相似文献