共查询到20条相似文献,搜索用时 15 毫秒
1.
In this article, we study the Λ
c
and Λ
b
baryons in the nuclear matter using the QCD sum rules, and obtain the in-medium masses
M\varLambda c*=2.335 GeVM_{\varLambda _{c}}^{*}=2.335~\mathrm{GeV},
M\varLambda b*=5.678 GeVM_{\varLambda _{b}}^{*}=5.678~\mathrm{GeV}, the in-medium vector self-energies
\varSigma \varLambda cv=34 MeV\varSigma ^{\varLambda _{c}}_{v}=34~\mathrm{MeV},
\varSigma \varLambda bv=32 MeV\varSigma ^{\varLambda _{b}}_{v}=32~\mathrm {MeV}, and the in-medium pole residues
l\varLambda c*=0.021 GeV3\lambda_{\varLambda _{c}}^{*}=0.021~\mathrm{GeV}^{3},
l\varLambda b*=0.026 GeV3\lambda_{\varLambda _{b}}^{*}=0.026~\mathrm{GeV}^{3}. The mass-shifts are
M\varLambda c*-M\varLambda c=51 MeVM_{\varLambda _{c}}^{*}-M_{\varLambda _{c}}=51~\mathrm{MeV} and
M\varLambda b*-M\varLambda b=60 MeVM_{\varLambda _{b}}^{*}-M_{\varLambda _{b}}=60~\mathrm{MeV}, respectively. 相似文献
2.
The polarization of the recoil proton from the reactionp
0
p has been measured for photon energies between 900–1,350 MeV and pion c.m. angles between 70° and 150°. There are significant deviations from recent analysis. 相似文献
3.
4.
5.
Recently experiments and theories show that the tunnel magnetoresistance (TMR) does not only depend on the ferromagnetic metal electrodes but also on the insulator. Considering the rough-scattering effect and spin-flip effect in the insulator, this paper investigates the TMR ratio in a ferromagnet/insulator/ferromagnet (FM/I/FM) tunnelling junction by using Slonczewsik's model. A more general expression of TMR ratio as a function of barrier height, interface roughness and spin-flip effect is obtained. In lower barrier case, it shows that the TMR ratio depends on the roughscattering effect and spin-flip effect. 相似文献
6.
7.
E. S. Konobeevski Yu. M. Burmistrov S. V. Zuyev M. V. Mordovskoy S. I. Potashev 《Physics of Atomic Nuclei》2010,73(8):1302-1308
The first results are obtained in a kinematically complete experiment devoted to measuring the n + d → p + n + n reaction yield at energies in the range E
n
= 40−60 MeV and various angles of divergence of two neutrons (Δθ = 4°, 6°, and 8°) in the geometry of neutron-neutron final-state interaction. The 1
S
0 neutron-neutron scattering length a
nn
is determined by comparing the experimental energy dependence of the reaction yield with the results of a simulation in the
Watson-Migdal approximation, which depend on a
nn
. For E
n
= 40 MeV and Δθ = 6° (the best statistics in the experiment), the value a
nn
= −17.9 ± 1.0 fm was obtained. A further improvement of the experimental accuracy will make it possible to remove the existing
disagreement of the results from different experiments. 相似文献
8.
Effect of the annealing temperature on the long-term thermal stability of Pt/Si/Ta/Ti/4H–SiC contacts
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《中国物理 B》2015,(10)
The Pt/Si/Ta/Ti multilayer metal contacts on 4H–Si C are annealed in Ar atmosphere at 600°C–1100°C by a rapid thermal processor(RTP). The long-term thermal stability is evaluated by aging the annealed contact at 600°C in air. The contact's properties are determined by current–voltage measurement, and the specific contact resistance is calculated based on the transmission line model(TLM). Transmission electron microscope(TEM) and energy-dispersive x-ray spectrometry(EDX) are used to characterize the interface morphology, thickness, and composition. The results reveal that a higher annealing temperature is favorable for the formation of an Ohmic contact with a lower specific contact resistance, and causes the rapid degradation of the Ohmic contact in the aging process. 相似文献
9.
S. Senyukov 《The European Physical Journal C - Particles and Fields》2009,62(1):229-235
Heavy quarks, such as charm, are produced in hard scatterings in the early stages of high energy nucleus-nucleus collisions
and are expected to be a powerful tool to investigate the properties of the quark gluon plasma (QGP). The tracking detectors
of the ALICE apparatus will allow to track and identify particles in central rapidity range down to low P
t
. Among D mesons it would be particularly interesting to measure D
s
yield via an exclusive hadronic decay channel because it could help to disentangle different hadronization mechanisms. The
possibility of reconstructing the D
s
meson through its D
s
+→K
+
K
−
π
+ decay channel in the central barrel was studied. The problem considered is characterized by the comparatively low yield of
the D
s
mesons against the huge amount of combinatorial background. Different kinematic and topological cuts have been studied in
order to increase the signal-to-background ratio and the statistical significance. In addition, D
s
mesons preferentially decay through intermediate resonant states and this fact can improve the separation of signal from
background. Results of cut parameters tuning and values of significance for an analysis performed on simulated data are presented. 相似文献
10.
Ning Tang Bo Shen Kui Han Xiao-Wei He Chun-Ming Yin Zhi-Jian Yang Zhi-Xin Qin Guo-Yi Zhang Tie Lin Wen-Zheng Zhou Li-Yan Shang Jun-Hao Chu 《Applied Physics A: Materials Science & Processing》2009,96(4):953-957
The subband structure and occupation in the triangular quantum well at Al
x
Ga1−x
N/GaN heterointerfaces have been investigated by means of temperature dependent Shubnikov–de Haas (SdH) measurements at low
temperatures and high magnetic fields under illumination. After the illumination of the heterostructures, the total two-dimensional
electron gas concentration increases, and the SdH oscillation amplitudes are enhanced when there is no additional subband
occupation. It is also found that the energy separation between the subbands decreases after the illumination. We suggest
that the illumination decreases the electric field and thus weakens the quantum confinement of the triangular quantum well
at Al
x
Ga1−x
N/GaN heterointerfaces. The GaN layer is thought to be the primary contributor of the excited electrons by the illumination. 相似文献
11.
An analysis of effects induced by new neutral gauge Z′ bosons was performed on the basis of data from the OPAL, DELPHI, ALEPH, and L3 experiments devoted to measuring differential
cross sections for the process of the annihilation production of pairs of charged gauge W
± bosons at the LEP2 collider. By using these experimental data, constraints on the Z′-boson mass and on the angle of Z-Z′ mixing were obtained for a number of extended gauge models. 相似文献
12.
The quasi-classical trajectory(QCT) method is employed to calculate the stereodynamics of the abstraction reactions H/D+HS/DS based on an accurate potential energy surface [L S J,Zhang P Y,Han K L and He G Z 2012 J.Chem.Phys.136 094308].The reaction cross sections of the title reaction are computed,and the vector correlations for different collision energies and different initial vibrational states are presented.The influences of the collision energy and reagent vibration on the product polarization are studied,and the product polarizations of the title reactions are found to be distinctly different,which arises from the different mass factors,collision energies,and reagent vibrational states. 相似文献
13.
A. E. Dorokhov 《JETP Letters》2010,91(4):163-169
Measuring the lepton anomalous magnetic moments (g − 2) and the rare decays of light pseudoscalar mesons into lepton pairs P → l
+
l
−, serve as important tests of the Standard Model. To reduce the theoretical uncertainty in the standard model predictions,
the data on the charge and transition form factors of the light pseudoscalar mesons play a significant role. Recently, new
data on the behavior of the transition form factors P → γγ* at large momentum transfer were supplied by the BABAR collaboration. There are several problems with the theoretical
interpretation of these data: (1) An unexpectedly slow decrease of the pion transition form factor at high momenta, (2) the
qualitative difference in the behavior of the pion form factor and the η and η′ form factors at high momenta, (3) the inconsistency
of the measured ratio of the η and η′ form factors with the predicted one. We comment on the influence of the new BABAR data
on the rare decay branchings. 相似文献
14.
15.
Geoffrey DuxburyAlexander Alijah 《Journal of Molecular Spectroscopy》2002,211(1):31-57
The extended stretch-bender Hamiltonian, incorporating spin-orbit coupling and overall rotation, has been used to calculate the spin-vibronic structure of the rovibronic energies in the region where the vibronic states of the excited Ã2A1 electronic state of NH2 interact with near-resonant high-lying levels of the X?2B1 state of NH2. A detailed comparison has been made with the experimental measurements which were made of these rovibronic states, the majority of which are due to Ramsay, Vervloet, and their collaborators. We have shown that, as in our study of the vibronic levels of the X?2B1 state below the barrier to linearity, in order to fit the variation of the effective vibronic spin-orbit coupling constant over the whole of this energy regime, the effective linear molecule spin-orbit coupling constant, ASO must be increased from the earlier value of 50 cm−1 of Ch. Jungen, K.-E. J. Hallin, and A. Merer (Mol. Phys.40, 65-94 (1980)) to 61.6 cm−1. The impact of Fermi resonance, in both the Ã2A1 and X?2B1 states, on the observed rovibronic structure has been assessed. The pattern of calculated spin-rovibronic levels, including the effects of spin uncoupling, is in good agreement with that measured experimentally. 相似文献
16.
In the study of complex networks,it is commonly believed that the eigenratio λ2/λ N of the Laplacian matrix of a network represents the network synchronizability,especially for symmetric networks.This paper gives two counterexamples to show that this is not true for the case where the network has a disconnected synchronized region.Consequently,a simple answer is presented to the question of when the eigenratio λ2/λ N does represent the network synchronizability. 相似文献
17.
V. I. Sharov A. A. Morozov R. A. Shindin E. V. Chernykh A. A. Nomofilov L. N. Strunov 《Physics of Atomic Nuclei》2009,72(6):1021-1025
Our new experimental results (see, e.g., Preprint JINR no. E1-2008-61 (Dubna, 2008)) on ratio R
dp
of the quasielastic charge-exchange yield at the proton emitting angle θ
p,lab = 0° for the nd → p(nn) reaction to the elastic np → pn charge-exchange yield were presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory
of High Energies of the JINR (Dubna) at the neutron-beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8, and 2.0 GeV. In
this paper the comparison of the experimental R
dp
data with the obtained R
dp
calculations within the impulse approximation by using the invariant-amplitude sets from the GW/VPI phase-shift analysis
is made. The R
dp
values calculated using the set of invariant amplitude data for the elastic np → pn charge exchange at θ
p,CM = 0°, agree with the experimental data. This confirmed the nd → p(nn) process yield at θ
p,CM = 0° is caused by the contribution of the spin-dependent part of the elastic np → pn charge-exchange reaction. Thus, it has been shown that the obtained experimental R
dp
results can be used for the Delta-Sigma experimental program to reduce the total ambiguity in the extraction of the amplitude
real parts.
The text was submitted by the authors in English. 相似文献
18.
We study the possibility of searching the η→e+e- rare decay on the Cooling Storage Ring (CSR) at Lanzhou. The main features of the proposed Internal Target Experiment (ITE) and External Target Facility (ETF) are included in the Monte Carlo simulation. Both the beam condition at the CSR and the major physics backgrounds are carefully taken into account. We conclude that the ITE is more suitable for such a study due to better detector acceptance and higher beam density. At the maximum designed luminosity (1034 cm-2s-1), η→e+e- events can be collected every ~400 seconds at the CSR. With a mass resolution of 1 MeV, the expected signal-to-background (S/B) ratio is around 1. 相似文献
19.
We study the possibility of searching the η→e+e- rare decay on the Cooling Storage Ring (CSR) at Lanzhou. The main features of the proposed Internal Target Experiment (ITE) and External Target Facility (ETF) are included in the Monte Carlo simulation. Both the beam condition at the CSR and the major physics backgrounds are carefully taken into account. We conclude that the ITE is more suitable for such a study due to better detector acceptance and higher beam density. At the maximum designed luminosity (1034cm-2s-1 ), η→e+e- events can be collected every~400 seconds at the CSR. With a mass resolution of 1 MeV, the expected signal-to-background (S/B) ratio is around 1. 相似文献
20.
We study the polarization observables of J/ψ hadroproduction at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics. We complete the present knowledge of the relativistic corrections by also providing the contribution due to the intermediate (3)P(J)([8]) color-octet states at this order, which turns out to be quite significant. Exploiting the color-octet long-distance matrix elements previously extracted through a global fit to experimental data of unpolarized J/ψ production, we provide theoretical predictions in the helicity and Collins-Soper frames and compare them with data taken by CDF at Fermilab Tevatron I and II and by ALICE at CERN LHC. The notorious CDF J/ψ polarization anomaly familiar from leading-order analyses persists at the quantum level, while the situation looks promising for the LHC, which is bound to bring final clarification. 相似文献