共查询到20条相似文献,搜索用时 265 毫秒
1.
2.
V. V. Sarantsev K. N. Ermakov L. M. Kochenda V. I. Medvedev V. A. Nikonov O. V. Rogachevsky A. V. Sarantsev S. G. Sherman V. A. Trofimov A. A. Vasiliev 《The European Physical Journal A - Hadrons and Nuclei》2010,43(1):11-16
A detailed investigation of the reaction np
? \rightarrow
pp
p- \pi^{{-}}_{} has been carried out using the data obtained with the continuous neutron beam produced by charge exchange scattering of protons
off the deuterium target. Partial-wave event-by-event analysis based on the maximum likelihood method was applied to determine
contributions of different partial waves to the pion production process. A combined analysis of the np
? \rightarrow
pp
p- \pi^{{-}}_{} and pp
? \rightarrow
pp
p0 \pi^{{0}}_{} data measured in the same energy region allows us to determine the contribution of isoscalar partial waves (I = 0 in the momentum range from 1.1 up to 1.8GeV/c . The decay of isoscalar partial waves into the (1
S
0)pp
p \pi channel provides us with a good tool for the determination of the pp
S -wave scalar scattering length in the final state which was found to be a
pp = - 7.5±0.3 fm. 相似文献
3.
Kh. K. Olimov S. L. Lutpullaev B. S. Yuldashev Y. H. Huseynaliyev A. K. Olimov 《The European Physical Journal A - Hadrons and Nuclei》2010,44(1):43-54
The production of D++ \Delta^{{++}}_{} and D0 \Delta^{0}_{} resonances on oxygen nuclei in 16O + p interactions at 3.25A GeV/c was investigated with 4p \pi acceptance. The masses and widths of the resonances were obtained from an analysis of the experimental and background invariant-mass
distributions of pp± \pi^{{\pm}}_{} pairs. The fractions of charged pions coming from D++ \Delta^{{++}}_{} and D0 \Delta^{0}_{} decay were estimated. The momentum, kinetic energy, and emission angle distributions of D++ \Delta^{{++}}_{} and D0 \Delta^{0}_{} resonances were reconstructed in the oxygen nucleus rest frame. The slope parameters, T0 , of the reconstructed spectra of invariant cross-sections of D++ \Delta^{{++}}_{} and D0 \Delta^{0}_{} resonances, produced on oxygen nuclei in 16O + p interactions at 3.25A GeV/c , were determined. 相似文献
4.
5.
The equation of state of symmetric nuclear matter is calculated using the relativistic Hamiltonian (HR) with potentials which have been fitted with the N -N scattering data using the relativistic two-body Hamiltonian ( [(v)\tilde]14 \tilde{{v}}_{{14}}^{} and the non-relativistic two-body Hamiltonian, i.e. the Argonne V14 interaction. The boost interaction corrections as well as the relativistic one-body and two-body kinetic energy corrections
in cluster expansion energy within the lowest-order-constrained variational method are calculated. It is shown that the relativistic
corrections reduce the binding energy by 1.5MeV for [(v)\tilde]14 \tilde{{v}}_{{14}}^{} and AV14 interactions. The symmetric nuclear-matter saturation energy is about -16.43 MeV at r \rho = 0.253 (fm-3) with [(v)\tilde]14 \tilde{{v}}_{{14}}^{} interaction plus relativistic corrections. Finally, various properties of the symmetric nuclear matter are given and a comparison
is made with the other many-body calculations. 相似文献
6.
Estimates for electroproduction of pseudoscalar mesons at small values of skewness are presented. Cross-sections and asymmetries
for these processes are calculated within the handbag approach which is based on factorization in hard parton subprocesses
and soft generalized parton distributions (GPDs). The latter are constructed from double distributions. Transversity GPDs
are taken into account; they are accompanied by twist-3 meson wave functions. For most pseudoscalar-meson channels a combination
of ˜T and [`(E)]T \bar{{E}}_{T}^{} plays a particularly prominent role. This combination of GPDs, which we constrain by moments obtained from lattice QCD, leads,
with the exception of the p+ \pi^{+}_{} and h¢ \eta^{\prime}_{} channels, to large transverse cross-sections. 相似文献
7.
The properties of asymmetric nuclear matter for a wide range of densities and asymmetric parameters are investigated within
the lowest-order-constrained variational (LOCV) method by employing the relativistic Hamiltonian with a potential which has
been fitted relativistically to N-N phase shifts ( [(v)\tilde]14 \tilde{{v}}_{{14}}^{} and to the AV14interaction. Like our previous work on symmetric nuclear matter, the boost interaction corrections as well as the relativistic
one-body and two-body kinetic corrections are calculated. The various properties of asymmetric nuclear matter such as the
symmetry energy, the saturation energy and the validity of the a2 \alpha^{2}_{} law, etc., are examined. The symmetry energy is reduced by about 7MeV when we use [(v)\tilde]14 \tilde{{v}}_{{14}}^{} instead of its non-relativistic version, i.e. the AV14interaction. The results are compared with other many-body calculations. 相似文献
8.
Using Brownian hydrodynamic simulation techniques, we study single polymers in shear. We investigate the effects of hydrodynamic
interactions, excluded volume, chain extensibility, chain length and semiflexibility. The well-known stretching behavior with
increasing shear rate [(g)\dot] \dot{{\gamma}} is only observed for low shear [(g)\dot] \dot{{\gamma}} < [(g)\dot]max \dot{{\gamma}}^{{\max}}_{} , where [(g)\dot]max \dot{{\gamma}}^{{\max}}_{} is the shear rate at maximum polymer extension. For intermediate shear rates [(g)\dot]max \dot{{\gamma}}^{{\max}}_{} < [(g)\dot] \dot{{\gamma}} < [(g)\dot]min \dot{{\gamma}}^{{\min}}_{} the radius of gyration decreases with increasing shear with minimum chain extension at [(g)\dot]min \dot{{\gamma}}^{{\min}}_{} . For even higher shear [(g)\dot]min \dot{{\gamma}}^{{\min}}_{} < [(g)\dot] \dot{{\gamma}} the chain exhibits again shear stretching. This non-monotonic stretching behavior is obtained in the presence of excluded-volume
and hydrodynamic interactions for sufficiently long and inextensible flexible polymers, while it is completely absent for
Gaussian extensible chains. We establish the heuristic scaling laws [(g)\dot]max \dot{{\gamma}}^{{\max}}_{} ∼ N
-1.4 and [(g)\dot]min \dot{{\gamma}}^{{\min}}_{} ∼ N
0.7 as a function of chain length N , which implies that the regime of shear-induced chain compression widens with increasing chain length. These scaling laws
also imply that the chain response at high shear rates is not a universal function of the Weissenberg number Wi = [(g)\dot] \dot{{\gamma}}
t \tau anymore, where t \tau is the equilibrium relaxation time. For semiflexible polymers a similar non-monotonic stretching response is obtained. By
extrapolating the simulation results to lengths corresponding to experimentally studied DNA molecules, we find that the shear
rate [(g)\dot]max \dot{{\gamma}}^{{\max}}_{} to reach the compression regime is experimentally realizable. 相似文献
9.
In this article, we study the mass spectrum of the baryon-antibaryon bound states p
[`(p)] \bar{{p}} , S \Sigma
[`(S)] \bar{{\Sigma}} , X \Xi
[`(X)] \bar{{\Xi}} , L \Lambda
[`(L)] \bar{{\Lambda}} , p
[`(N)] \bar{{N}}(1440) , S \Sigma
[`(S)] \bar{{\Sigma}}(1660) , X \Xi
[`(X)]¢ \bar{{\Xi}}^{{\prime}}_{} and L \Lambda
[`(L)] \bar{{\Lambda}}(1600) with the Bethe-Salpeter equation. The numerical results indicate that the p
[`(p)] \bar{{p}} , S \Sigma
[`(S)] \bar{{\Sigma}} , X \Xi
[`(X)] \bar{{\Xi}} , p
[`(N)] \bar{{N}}(1440) , S \Sigma
[`(S)] \bar{{\Sigma}}(1660) , X \Xi
[`(X)]¢ \bar{{\Xi}}^{{\prime}}_{} bound states maybe exist, and the new resonances X(1835) and X(2370) can be tentatively identified as the p
[`(p)] \bar{{p}} and p
[`(N)] \bar{{N}}(1440) (or N(1400)[`(p)] \bar{{p}} bound states, respectively, with some gluon constituents, and the new resonance X(2120) may be a pseudoscalar glueball. On the other hand, the Regge trajectory favors identifying the X(1835) , X(2120) and X(2370) as the excited h¢ \eta^{{\prime}}_{}(958) mesons with the radial quantum numbers n = 3 , 4 and 5, respectively. 相似文献
10.
Zhi-Gang Wang 《The European Physical Journal A - Hadrons and Nuclei》2010,45(2):267-274
In this paper, we study the
\frac12 {\frac{{1}}{{2}}}
+ doubly heavy baryon states WQQ \Omega_{{QQ}}^{} and XQQ \Xi_{{QQ}}^{} by subtracting the contributions from the corresponding
\frac12 {\frac{{1}}{{2}}}
- doubly heavy baryon states with QCD sum rules, and make reasonable predictions for their masses. Those doubly heavy baryon
states may be observed at Tevatron, LHCb and PANDA. 相似文献
11.
S. Verma J. J. Das A. Jhingan K. Kalita S. Barua K. S. Golda N. Madhavan P. Sugathan S. Nath T. Varughese J. Gehlot S. Mandal Ranjit P. K. Sahu B. John B. K. Nayak V. Jha A. Saxena S. K. Datta R. Singh 《The European Physical Journal A - Hadrons and Nuclei》2010,44(3):385-392
Quasielastic scattering angular distributions have been measured for the 7Be + 9Be system at E lab = 17 , 19 and 21MeV in the angular range $ \theta_{{cm}}^{}$ = 24° - 57° . An optical model (OM) analysis of these data has been carried out in order to extract optical potential parameters and reaction cross-sections. One-proton stripping cross-sections were also measured for this system at E lab = 19 and 21MeV. These transfer angular-distribution data were compared with the finite-range distorted-wave Born approximation (FRDWBA) calculations. For the 7Li + 9Be system quasielastic scattering angular distributions were measured and emitted light charged particles were detected at E lab = 15.75 , 24.00 and 30.00MeV in the angular range $ \theta_{{cm}}^{}$ = 7° - 70° . Fusion cross-sections were obtained by reproducing the measured $ \alpha$ -evaporation spectra from the compound nucleus at backward angles with the statistical model calculations. The ratios of the experimental fusion cross-sections to the total reaction cross-sections (obtained from OM analysis) were found to be small. This result suggests that the break-up process has a strong influence on the fusion process leading to a reduction in the fusion cross-section. 相似文献
12.
M. Tsamados 《The European physical journal. E, Soft matter》2010,32(2):165-181
Many amorphous glassy materials exhibit complex spatio-temporal mechanical response and rheology, characterized by an intermittent
stress strain response and a fluctuating velocity profile. Under quasistatic and athermal deformation protocols this heterogeneous
plastic flow was shown to be composed of plastic events of various sizes, ranging from local quadrupolar plastic rearrangements
to system spanning shear bands. In this paper, through numerical study of a 2D Lennard-Jones amorphous solid, we generalize
the study of the heterogeneous dynamics of glassy materials to the finite shear rate ( [(g)\dot] \dot{{\gamma}}
1 \neq 0 and temperature case (T
1 \neq 0 . In practice, we choose an effectively athermal limit (T ∼ 0 and focus on the influence of shear rate on the rheology of the glass. In line with previous works we find that the model
Lennard-Jones glass follows the rheological behavior of a yield stress fluid with a Herschel-Bulkley response of the form,
s \sigma = sY \sigma_{{Y}}^{} + c
1
[(g)\dot]b \dot{{\gamma}}^{{\beta}}_{} . The global mechanical response obtained through the use of Molecular Dynamics is shown to converge in the limit [(g)\dot] \dot{{\gamma}}
? \rightarrow 0 to the quasistatic limit obtained with an energy minimization protocol. The detailed analysis of the plastic deformation
at different shear rates shows that the glass follows different flow regimes. At sufficiently low shear rates the mechanical
response reaches a shear-rate-independent regime that exhibits all the characteristics of the quasistatic response (finite-size
effects, cascades of plastic rearrangements, yield stress, ...). At intermediate shear rates the rheological properties are
determined by the externally applied shear rate and the response deviates from the quasistatic limit. Finally at higher shear
the system reaches a shear-rate-independent homogeneous regime. The existence of these three regimes is also confirmed by
the detailed analysis of the atomic motion. The computation of the four-point correlation function shows that the transition
from the shear-rate-dominated to the quasistatic regime is accompanied by the growth of a dynamical cooperativity length scale
x \xi that is shown to diverge with shear rate as x \xi
μ \propto
[(g)\dot]-n \dot{{\gamma}}^{{-\nu}}_{} , with n \nu ∼ 0.2 -0.3. This scaling is compared with the prediction of a simple model that assumes the diffusive propagation of plastic
events. 相似文献
13.
By introducing the mixing of scalar mesons in the chiral SU(3) quark model, we dynamically investigate the baryon-baryon interaction. The hyperon-nucleon and nucleon-nucleon interactions
are studied by solving the resonating group method (RGM) equation in a coupled-channel calculation. In our present work, the
experimental lightest pseudoscalar p \pi, K,h \eta,h¢ \eta^{{\prime}}_{} mesons correspond exactly to the chiral nonet pseudoscalar fields p \pi, K,h \eta,h¢ \eta^{{\prime}}_{} in the chiral SU(3) quark model. The h \eta,h¢ \eta^{{\prime}}_{} mesons are considered as the mixing of singlet and octet mesons, and the mixing angle qps \theta_{{ps}}^{} is taken to be -23° . For scalar nonet mesons, we suppose that there exists a correspondence between the experimental lightest scalar f
0(600) , k \kappa , a
0(980) , f
0(980) mesons and the theoretical scalar nonet s \sigma , k \kappa , s¢ \sigma^{{\prime}}_{} , e \epsilon fields in the chiral SU(3) quark model. For scalar mesons, we consider two different mixing cases: one is the ideal mixing and another is the qs \theta_{s}^{} = 19° mixing. The masses of the s¢ \sigma^{{\prime}}_{} and e \epsilon mesons are taken to be 980MeV, which are just the masses of the experimental a
0(980) , f
0(980) mesons. The mass of the s \sigma meson is an adjustable parameter and is decided by fitting the binding energy of the deuteron, the masses of 560MeV and 644MeV
are obtained for the ideal mixing and the qs \theta_{s}^{} = 19° mixing, respectively. We find that, in order to reasonably describe the YN interactions, the mass of the k \kappa meson is near 780MeV for the ideal mixing. However, we must enhance the mass of the k \kappa meson for the qs \theta_{s}^{} = 19° mixing, the 1050MeV is favorably used in the present work. The experimental s \sigma and k \kappa scalar mesons are very strange, both have larger widths. Hence, no matter what kind of mixing is considered, all the masses
of scalar mesons we used in the present work seem to be consistent with the present PDG information. 相似文献
14.
V. Baru E. Epelbaum A. Rusetsky 《The European Physical Journal A - Hadrons and Nuclei》2009,42(1):111-120
The effect of the nucleon recoil for the antikaon-deuteron scattering is investigated in the framework of the effective field
theory. In particular, we concentrate on the calculation of the nucleon recoil effect for the double-scattering process. It
is shown that the leading correction to the static term that emerges at order x1/2 \xi^{{1/2}}_{} with x \xi = M
K/m
N vanishes due to a complete cancellation of individually large contributions. The resulting recoil effect in this process
is found to be of the order of 10-15% as compared to the static term. We also briefly discuss the application of the method
in the calculations of the multiple-scattering diagrams. 相似文献
15.
J. Haidenbauer G. Krein U. -G. Meißner L. Tolos 《The European Physical Journal A - Hadrons and Nuclei》2011,47(2):18
A model of the DN interaction is presented which is developed in close analogy to the meson-exchange [`(K)] \bar{{K}}
N potential of the Jülich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (r \rho , w \omega exchange and higher-order box diagrams involving D
*
N , D
D \Delta , and D
*
D \Delta intermediate states. The coupling of DN to the p \pi
Lc \Lambda_{c}^{} and p \pi
Sc \Sigma_{c}^{} channels is taken into account. The interaction model generates the Lc \Lambda_{c}^{}(2595) -resonance dynamically as a DN quasi-bound state. Results for DN total and differential cross sections are presented and compared with predictions of two interaction models that are based
on the leading-order Weinberg-Tomozawa term. Some features of the Lc \Lambda_{c}^{}(2595) -resonance are discussed and the role of the near-by p \pi
Sc \Sigma_{c}^{} threshold is emphasized. Selected predictions of the orginal [`(K)] \bar{{K}}
N model are reported too. Specifically, it is pointed out that the model generates two poles in the partial wave corresponding
to the L \Lambda(1405) -resonance. 相似文献
16.
B. Sitamtze Youmbi Serge Zékeng Samuel Domngang Florent Calvayrac Alain Bulou 《Ionics》2012,18(4):371-377
To date, the fastest lithium ion-conducting solid electrolytes known are the perovskite-type ABO3 oxide, with A = Li, La and B = Ti, lithium lanthanum titanate (LLTO)
Li3x La( 2 \mathord