首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Hadro-charmonium     
We argue that relatively compact charmonium states, J/ψJ/ψ, ψ(2S)ψ(2S), χcχc, can very likely be bound inside light hadronic matter, in particular inside higher resonances made from light quarks and/or gluons. The charmonium state in such binding essentially retains its properties, so that the bound system decays into light mesons and the particular charmonium resonance. Thus such bound states of a new type, which we call hadro-charmonium, may explain the properties of some of the recently observed resonant peaks, in particular of Y(4.26)Y(4.26), Y(4.32–4.36)Y(4.324.36), Y(4.66)Y(4.66), and Z(4.43)Z(4.43). We discuss further possible implications of the suggested picture for the observed states and existence of other states of hadro-charmonium and hadro-bottomonium.  相似文献   

2.
The deviation δQWδQW of the weak charge from its standard model prediction due to the mixing of the W boson with the charged bilepton Y as well as of the Z   boson with the neutral ZZ and the real part of the non-Hermitian neutral bilepton X   in the economical 3–3–1 model is established. Additional contributions to the usual δQWδQW expression in the extra U(1)U(1) models and the left–right models are obtained. Our calculations are quite different from previous analyzes in this kind of the 3–3–1 models and give the limit on mass of the ZZ boson, the Z–ZZZ and W–YWY mixing angles with the more appropriate values: MZ>564 GeVMZ>564 GeV, −0.018<sinφ<00.018<sinφ<0 and |sinθ|<0.043|sinθ|<0.043.  相似文献   

3.
Magnetic properties of the bond and crystal field dilution spin-3/2 Blume–Capel model in an external magnetic field (h)(h) on simple cubic lattice are studied by using the effective field theory. In the m−TmT plane, the degeneracy of the magnetization (m)(m) is affected by the concentration of bond or crystal field dilution at low temperature (T)(T). The magnetization curves can appear to fluctuate in certain regions of negative crystal field. In the m−hmh plane, the initial magnetization curve has an irregular behavior due to the introduction of bond dilution. The crystal field dilution has the influence on the process of magnetic domain displacement. In the χ−hχh plane, there exists one susceptibility (χ)(χ) shoulder and one step for different negative crystal field. The susceptibility curve takes on the feature of multi-peaks distribution under bond and crystal field dilution conditions.  相似文献   

4.
Bogomolny–Prasad–Sommerfield (BPS) vortices in U(N)U(N) gauge theories have two layers corresponding to non-Abelian and Abelian fluxes, whose widths depend nontrivially on the ratio of U(1)U(1) and SU(N)SU(N) gauge couplings. We find numerically and analytically that the widths differ significantly from the Compton lengths of lightest massive particles with the appropriate quantum number.  相似文献   

5.
We show that the newly measured branching ratios of vector charmonia (J/ψJ/ψ, ψψ and ψ(3770)ψ(3770)) into γP, where P   stands for light pseudoscalar mesons π0π0, η  , and ηη, can be well understood in the framework of vector meson dominance (VMD) in association with the ηc–η(η)ηcη(η) mixings due to the axial gluonic anomaly. These two mechanisms behave differently in J/ψJ/ψ and ψ→γPψγP. A coherent understanding of the branching ratio patterns observed in J/ψ(ψ)→γPJ/ψ(ψ)γP can be achieved by self-consistently including those transition mechanisms at hadronic level. The branching ratios for ψ(3770)→γPψ(3770)γP are predicted to be rather small.  相似文献   

6.
We study integrable cases of pairing BCS hamiltonians containing several types of fermions. We prove that there exist three classes of such integrable models associated with classical rational r  -matrices and Lie algebras gl(2m)gl(2m), sp(2m)sp(2m) and so(2m)so(2m) correspondingly. We diagonalize the constructed hamiltonians by means of the algebraic Bethe ansatz. In the partial case of two types of fermions (m=2m=2) the obtained models may be interpreted as N=ZN=Z proton–neutron integrable models. In particular, in the case of sp(4)sp(4) we recover the famous integrable proton–neutron model of Richardson.  相似文献   

7.
In this Letter we compute the nonplanar one-loop anomalous dimension of restricted Schur polynomials that have a bare dimension of O(N)O(N). This is achieved by mapping the restricted Schur polynomials into states of a specific U(p)U(p) irreducible representation. In this way the dilatation operator is mapped into a u(p)u(p) valued operator and, as a result, can easily be diagonalized. The resulting spectrum is reproduced by a model of springs between masses.  相似文献   

8.
We study a matrix model obtained by dimensionally reducing Chern–Simons theory on S3S3. We find that the matrix integration is decomposed into sectors classified by the representation of SU(2)SU(2). We show that the N  -block sectors reproduce SU(N)SU(N) Yang–Mills theory on S2S2 as the matrix size goes to infinity.  相似文献   

9.
To complement existing knowledge of the density matrix γF(x,y)γF(x,y) of independent fermions for N   particles in one dimension under harmonic confinement, the corresponding matrix γIB(x,y)γIB(x,y) for impenetrable bosons is given for N=2N=2 and 3 (with the N=4N=4 form available also). For fermions the momentum density is then obtained and illustrated numerically for N=10N=10. The boson momentum density is studied analytically at high momentum p  , the coefficients of the p−4p−4 and p−6p−6 terms being tabulated for N=2–5N=25 inclusive. Their dependence on powers of N   is exhibited numerically. Finally, the functional relationship between γIB(x,y)γIB(x,y) and γF(x,y)γF(x,y) is formally set out and illustrated.  相似文献   

10.
Most of the inflation models end up with non-vanishing vacuum expectation values of the inflaton fields ?   in the true vacuum, which induce, in general, non-vanishing auxiliary field G?G? for the inflaton potential in supergravity. We show that the presence of nonzero G?G? gives rise to inflaton decay into a pair of the gravitinos and are thereby severely constrained by cosmology especially if the gravitino is unstable and its mass is in a range of O(100) GeV–O(10) TeVO(100) GeVO(10) TeV. For several inflation models, we explicitly calculate the values of G?G? and find that most of them are excluded or on the verge of being excluded for the gravitino mass in that range. We conclude that an inflation model with vanishing G?G?, typically realized in a chaotic inflation, is favored in a sense that it naturally avoids the potential gravitino overproduction problem.  相似文献   

11.
We study the Quantum Regge Calculus of Einstein–Cartan theory to describe quantum dynamics of Euclidean space–time discretized as a 4-simplices complex. Tetrad field eμ(x)eμ(x) and spin-connection field ωμ(x)ωμ(x) are assigned to each 1-simplex. Applying the torsion-free Cartan structure equation to each 2-simplex, we discuss parallel transports and construct a diffeomorphism and local   gauge-invariant Einstein–Cartan action. Invariant holonomies of tetrad and spin-connection fields along large loops are also given. Quantization is defined by a bounded partition function with the measure of SO(4)SO(4)-group valued ωμ(x)ωμ(x) fields and Dirac-matrix valued eμ(x)eμ(x) fields over 4-simplices complex.  相似文献   

12.
The grand partition functions Z(T,B)Z(T,B) of the Ising model on L×LL×L triangular lattices with fully periodic boundary conditions, as a function of temperature T and magnetic field B  , are evaluated exactly for L<12L<12 (using microcanonical transfer matrix) and approximately for L?12L?12 (using Wang–Landau Monte Carlo algorithm). From Z(T,B)Z(T,B), the distributions of the partition function zeros of the triangular-lattice Ising model in the complex temperature plane for real B≠0B0 are obtained and discussed for the first time. The critical points aN(x)aN(x) and the thermal scaling exponents yt(x)yt(x) of the triangular-lattice Ising antiferromagnet, for various values of x=e−2βBx=e2βB, are estimated using the partition function zeros.  相似文献   

13.
We study the matter stability in modified teleparallel gravity or f(T)f(T) theories. We show that there is no Dolgov–Kawasaki instability in these types of modified teleparallel gravity theories. This gives for the f(T)f(T) theories a great advantage over their f(R)f(R) counterparts because from the stability point of view there isn?t any limit on the form of functions that can be chosen.  相似文献   

14.
In this Letter, we consider lattice versions of the decomposition of the Yang–Mills field a la Cho–Faddeev–Niemi, which was extended by Kondo, Shinohara and Murakami in the continuum formulation. For the SU(N)SU(N) gauge group, we propose a set of defining equations for specifying the decomposition of the gauge link variable and solve them exactly without using the ansatz adopted in the previous studies for SU(2)SU(2) and SU(3)SU(3). As a result, we obtain the general form of the decomposition for SU(N)SU(N) gauge link variables and confirm the previous results obtained for SU(2)SU(2) and SU(3)SU(3).  相似文献   

15.
We construct a natural model of the supersymmetric SU(6)SU(6) unification, in which the symmetry breaking, down to the standard model gauge group, results in the number of pseudo-Nambu–Goldstone superfields with interesting properties. Namely, besides the Higgs doublet–antidoublet pair which is responsible for the electroweak phase transition, the Nambu–Goldstone sector consists of multiplets in the anti- and fundamental representations of SU(5)SU(5). While being strictly massless in the supersymmetric limit, they acquire the weak scale masses as a result of its breaking. The color-triplet components of this light sector could, in principle, mediate an unacceptably fast proton decay; however, because of the natural TeV/MGUTTeV/MGUT suppression of the Yukawa couplings to the light quarks and leptons, their existence is compatible with the experimental bound on proton lifetime. This suppression is made further interesting, since it results in the lifetime, of the lightest of the above-mentioned colored particles from 1 s to 1 day1 day, long enough for it to appear stable in the detector. Furthermore, we argue that the accommodation of the color-triplet pseudo-Nambu–Goldstones, without fine-tuning or contradicting observations, implies SU(6)SU(6) unification.  相似文献   

16.
It is argued that the dominant contribution to the interaction of quark–gluon plasma at moderate T?TcT?Tc is given by the nonperturbative vacuum field correlators. Basing on that nonperturbative equation of state of quark–gluon plasma is computed and in the lowest approximation expressed in terms of absolute values of Polyakov lines for quarks and gluons Lfund(T),Ladj(T)=(Lfund)9/4Lfund(T),Ladj(T)=(Lfund)9/4 known from lattice and analytic calculations. Phase transition at any μ   is described as a transition due to vanishing of one of correlators, DE(x)DE(x), which implies the change of gluonic condensate ΔG2ΔG2. Resulting transition temperature Tc(μ)Tc(μ) is calculated in terms of ΔG2ΔG2 and Lfund(Tc)Lfund(Tc). The phase curve Tc(μ)Tc(μ) is in a good agreement with lattice data. In particular Tc(0)=0.27Tc(0)=0.27; 0.19; 0.17 GeV0.17 GeV for nf=0,2,3nf=0,2,3 and fixed ΔG2=0.0035 GeV4ΔG2=0.0035 GeV4.  相似文献   

17.
We use the Radial Baryon Acoustic Oscillation (RBAO) measurements, distant type Ia supernovae (SNe Ia), the observational H(z)H(z) data (OHD) and the Cosmic Microwave Background (CMB) shift parameter data to constrain cosmological parameters of ΛCDMΛCDM and XCDM cosmologies and further examine the role of OHD and SNe Ia data in cosmological constraints. We marginalize the likelihood function over h   by integrating the probability density P∝e−χ2/2Peχ2/2 to obtain the best fitting results and the confidence regions in the Ωm–ΩΛΩmΩΛ plane. With the combination analysis for both of the ΛCDMΛCDM and XCDM models, we find that the confidence regions of 68.3%, 95.4% and 99.7% levels using OHD+RBAO+CMBOHD+RBAO+CMB data are in good agreement with that of SNe Ia+RBAO+CMBIa+RBAO+CMB data which is consistent with the result of Lin et al.'s (2009) [24] work. With more data of OHD, we can probably constrain the cosmological parameters using OHD data instead of SNe Ia data in the future.  相似文献   

18.
More than four decades ago, March and Murray gave a perturbation theory of the single-particle(s) Dirac density matrix γs(r,r)γs(r,r) to all orders in a given one-body potential energy V(r)V(r). However, for density functional theory in orbital-free form, one requires the functional γs[ρ]γs[ρ] where ρ(r)ρ(r) is the ground-state electron density. Therefore, in the present study, a first-order non-linear differential equation is proposed for γsγs in terms of ρ(r)ρ(r) and ∇ρ(r)ρ(r), plus the single-particle kinetic energy. Since this latter quantity is itself known to be a functional of ρ  , the existence of such an equation for γsγs would be a significant step along the road to determining the desired functional γs[ρ]γs[ρ]. As yet, we have succeeded in giving a rigorous proof of the proposed differential equation for γs(r,r)γs(r,r) only for one- and two-level molecules. If it is subsequently proved for an arbitrary number of levels, which we believe should be possible, it would then allow γsγs to be calculated for molecules of biological interest, from experimentally measured ground-state densities ρ(r)ρ(r), as the approach is entirely orbital-free.  相似文献   

19.
A cosmological model has been constructed with Gauss–Bonnet-scalar interaction, where the Universe starts with exponential expansion but encounters infinite deceleration, q→∞q and infinite equation of state parameter, w→∞w. During evolution it subsequently passes through the stiff fluid era, q=2q=2, w=1w=1, the radiation dominated era, q=1q=1, w=1/3w=1/3 and the matter dominated era, q=1/2q=1/2, w=0w=0. Finally, deceleration halts, q=0q=0, w=−1/3w=1/3, and it then encounters a transition to the accelerating phase. Asymptotically the Universe reaches yet another inflationary phase q→−1q1, w→−1w1. Such evolution is independent of the form of the potential and the sign of the kinetic energy term, i.e., even a non-canonical kinetic energy is unable to phantomize (w<−1)(w<1) the model.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号