共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhi-Gang Wang Zhi-Cheng Liu Xiao-Hong Zhang 《The European Physical Journal C - Particles and Fields》2009,64(3):373-386
In this article, we assume that there exist scalar D*[`(D)]*{D}^{\ast}{\bar {D}}^{\ast}, Ds*[`(D)]s*{D}_{s}^{\ast}{\bar{D}}_{s}^{\ast}, B*[`(B)]*{B}^{\ast}{\bar {B}}^{\ast} and Bs*[`(B)]s*{B}_{s}^{\ast}{\bar{B}}_{s}^{\ast} molecular states, and study their masses using the QCD sum rules. The numerical results indicate that the masses are about
(250–500) MeV above the corresponding D
*–[`(D)]*{\bar{D}}^{\ast}, D
s
*–[`(D)]s*{\bar {D}}_{s}^{\ast}, B
*–[`(B)]*{\bar{B}}^{\ast} and B
s
*–[`(B)]s*{\bar {B}}_{s}^{\ast} thresholds, the Y(4140) is unlikely a scalar Ds*[`(D)]s*{D}_{s}^{\ast}{\bar{D}}_{s}^{\ast} molecular state. The scalar D*[`(D)]*D^{\ast}{\bar{D}}^{\ast}, Ds*[`(D)]s*D_{s}^{\ast}{\bar{D}}_{s}^{\ast}, B*[`(B)]*B^{\ast}{\bar{B}}^{\ast} and Bs*[`(B)]s*B_{s}^{\ast}{\bar{B}}_{s}^{\ast} molecular states maybe not exist, while the scalar D¢*[`(D)]¢*{D'}^{\ast}{\bar{D}}^{\prime\ast}, Ds¢*[`(D)]s¢*{D}_{s}^{\prime\ast}{\bar{D}}_{s}^{\prime\ast}, B¢*[`(B)]¢*{B}^{\prime\ast}{\bar{B}}^{\prime\ast} and Bs¢*[`(B)]s¢*{B}_{s}^{\prime\ast}{\bar{B}}_{s}^{\prime\ast} molecular states maybe exist. 相似文献
2.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2009,63(1):115-122
In this article, we assume that there exists a scalar
Ds*[`(D)]s*D_{s}^{\ast}{\bar{D}}_{s}^{\ast}
molecular state in the J/ψ
φ invariant mass distribution, and we study its mass using the QCD sum rules. The predictions depend heavily on the two criteria
(pole dominance and convergence of the operator product expansion) of the QCD sum rules. The value of the mass is about
MDs*[`(D)]s*=(4.43±0.16)M_{D_{s}^{\ast}{\bar{D}}_{s}^{\ast}}=(4.43\pm0.16)
GeV, which is inconsistent with the experimental data. The
Ds*[`(D)]s*D_{s}^{\ast}{\bar{D}}_{s}^{\ast}
is probably a virtual state and is not related to the meson Y(4140). Another possibility, such as a hybrid charmonium, is not excluded. 相似文献
3.
The polarizations of Λ and
[`\varLambda]{\bar{\varLambda}} are thought to retain memories of the spins of their parent s quarks and [`(s)]{\bar{s}} antiquarks, and are readily measurable via the angular distributions of their daughter protons and antiprotons. Correlations between the spins of Λ and
[`\varLambda]{\bar{\varLambda}} produced at low relative momenta may therefore be used to probe the spin states of s [`(s)]s {\bar{s}} pairs produced during hadronization. We consider the possibilities that they are produced in a 3P0 state, as might result from fluctuations in the magnitude of á[`(s)] s ?\langle {\bar{s}} s \rangle, a 1S0 state, as might result from chiral fluctuations, or a 3S1 or other spin state, as might result from production by a quark–antiquark or gluon pair. We provide templates for the p [`(p)]p {\bar{p}} angular correlations that would be expected in each of these cases, and discuss how they might be used to distinguish s [`(s)]s {\bar{s}} production mechanisms in pp and heavy-ion collisions. 相似文献
4.
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
5.
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8.
Zhi Yang Xing-Gang Wu Li-Cheng Deng Jia-Wei Zhang Gu Chen 《The European Physical Journal C - Particles and Fields》2011,71(3):1563
In Deng et al. (Eur. Phys. J. C 70:113, 2010), we have dealt with the production of the two color-singlet S-wave (c[`(b)])(c\bar{b})-quarkonium states Bc(|(c[`(b)])1[1S0]?)B_{c}(|(c\bar {b})_{\mathbf{1}}[^{1}S_{0}]\rangle) and B*c(|(c[`(b)])1[3S1]?)B^{*}_{c}(|(c\bar{b})_{\mathbf{1}}[^{3}S_{1}]\rangle) through the Z
0 boson decays. As an important sequential work, we make a further discussion on the production of the more complicated P-wave excited (c[`(b)])(c\bar{b})-quarkonium states, i.e. |(c[`(b)])1[1P1]?|(c\bar{b})_{\mathbf{1}}[^{1}P_{1}]\rangle and |(c[`(b)])1[3PJ]?|(c\bar{b})_{\mathbf{1}}[^{3}P_{J}]\rangle (with J=(1,2,3)). More over, we also calculate the channel with the two color-octet quarkonium states |(c[`(b)])8[1S0]g?|(c\bar{b})_{\mathbf{8}}[^{1}S_{0}]g\rangle and |(c[`(b)])8[3S1]g?|(c\bar{b})_{\mathbf{8}}[^{3}S_{1}]g\rangle, whose contributions to the decay width maybe at the same order of magnitude as that of the color-singlet P-wave states according to the naive nonrelativistic quantum chromodynamics scaling rules. The P-wave states shall provide sizable contributions to the B
c
production, whose decay width is about 20% of the total decay width
\varGamma Z0? Bc\varGamma _{Z^{0}\to B_{c}}. After summing up all the mentioned (c[`(b)])(c\bar {b})-quarkonium states’ contributions, we obtain
\varGamma Z0? Bc=235.9+352.8-122.0\varGamma _{Z^{0}\to B_{c}}=235.9^{+352.8}_{-122.0} KeV, where the errors are caused by the main sources of uncertainty. 相似文献
9.
Percolation theory is extensively studied in statistical physics and mathematics with applications in diverse fields. However,
the research is focused on systems with only one type of links, connectivity links. We review a recently developed mathematical
framework for analyzing percolation properties of realistic scenarios of networks having links of two types, connectivity
and dependency links. This formalism was applied to study Erdős-Rényi (ER) networks that include also dependency links. For
an ER network with average degree [`(k)]\bar{k} that is composed of dependency clusters of size s, the fraction of nodes that belong to the giant component, P
∞, is given by P¥=ps-1[1-exp(-[`(k)]pP¥) ]sP_{\infty}=p^{s-1}[1-\exp{(-\bar{k}pP_{\infty})} ]^{s} where 1−p is the initial fraction of randomly removed nodes. Here, we apply the formalism to the study of random-regular (RR) networks
and find a formula for the size of the giant component in the percolation process: P
∞=p
s−1(1−r
k
)
s
where r is the solution of r=p
s
(r
k−1−1)(1−r
k
)+1, and k is the degree of the nodes. These general results coincide, for s=1, with the known equations for percolation in ER and RR networks respectively without dependency links. In contrast to s=1, where the percolation transition is second order, for s>1 it is of first order. Comparing the percolation behavior of ER and RR networks we find a remarkable difference regarding
their resilience. We show, analytically and numerically, that in ER networks with low connectivity degree or large dependency
clusters, removal of even a finite number (zero fraction) of the infinite network nodes will trigger a cascade of failures
that fragments the whole network. Specifically, for any given s there exists a critical degree value, [`(k)]min\bar{k}_{\min}, such that an ER network with [`(k)] £ [`(k)]min\bar{k}\leq \bar{k}_{\min} is unstable and collapse when removing even a single node. This result is in contrast to RR networks where such cascades
and full fragmentation can be triggered only by removal of a finite fraction of nodes in the network. 相似文献
10.
A gauge model featuring a chiral color symmetry of quarks was considered, and possible manifestations of this symmetry in
proton-antiproton and proton-proton collisions at the Tevatron and LHC energies were studied. The cross section st[`(t)]\sigma _{t\bar t} for the production of t[`(t)]t\bar t quark pairs at the Tevatron and the forward-backward asymmetry AFBp[`(p)]A_{FB}^{p\bar p} in this process were calculated and analyzed with allowance for the contributions of the G′-boson predicted by the chiral color symmetry of quarks, the G′-boson massm
G′ and the mixing angle θ
G
being treated as free parameters of the model. Limits on m
G′ versus θ
G
were studied on the basis of data from the Tevatron on st[`(t)]\sigma _{t\bar t} and AFBp[`(p)]A_{FB}^{p\bar p}, and the region compatible with these data within one standard deviation was found in the m
G′-θ
G
plane. The region ofm
G′-mass values that is appropriate for observing the G′-boson at LHC is discussed. 相似文献
11.
A model-independent analysis of anomalous gauge coupling constants of W
± bosons is presented and the corresponding restrictions on them and on the electromagnetic characteristics of W
± bosons following from the experiments on measuring the e+ e- ? W+ W- ? ( e