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 125 毫秒
1.
The recent observation of higher quark combinations, tetraquarks and pentaquarks, is a strong indication of more exotic hadrons. Using Z_2 and Z_3 symmetries and standard model data, a general quark combination producing new hadronic states is proposed in terms of polygon geometries according to the Dynkin diagrams of ?_n affine Lie algebras. It has been shown that Z_(2,3) invariance is crucial in the determination of the mesonic or the baryonic nature of these states. The hexagonal geometry is considered in some details producing both mesonic and baryonic states. A general class of this family is also presented.  相似文献   

2.
The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons.Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks,pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. It is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimental and theoretical issues concerning heavy exotic hadrons is presented.  相似文献   

3.
This paper proposes an algorithm for the Lie symmetries investigation in the case of a 2D Hamiltonian system. General Lie operators are deduced firstly and, in the the next step, the associated Lie invariants are derived. The 2D Yang-Mills mechanical model is chosen as a test model for this method. PACS: 05.45.-a; 02.30.Ik  相似文献   

4.
Beyond‐the‐standard‐model interactions mediated by an exchange of virtual “new” bosons result in a finite set of possible effective interaction potentials between standard‐model particles such as electrons and nucleons. The classification of such potentials is discussed and recent experiments searching for such exotic interactions at spatial scales from sub‐nanometers to tens of thousand kilometers are briefly reviewed.  相似文献   

5.
Nonlinear PDE’s having given conditional symmetries are constructed. They are obtained starting from the invariants of the conditional symmetry generator and imposing the extra condition given by the characteristic of the symmetry. Series of examples starting from the Boussinesq and including non-autonomous Korteweg–de Vries like equations are given to show and clarify the methodology introduced.  相似文献   

6.
The Ishimori equation is one of the most important(2+1)-dimensional integrable models,which is an integrable generalization of(1+1)-dimensional classical continuous Heisenberg ferromagnetic spin equations.Based on importance of Lie symmetries in analysis of differential equations,in this paper,we derive Lie symmetries for the Ishimori equation by Hirota's direct method.  相似文献   

7.
Symmetries of spacetime manifolds which are given by Killing vectors are compared with the symmetries of the Lagrangians of the respective spacetimes. We find the point generators of the one parameter Lie groups of transformations that leave invariant the action integral corresponding to the Lagrangian (Noether symmetries). In the examples considered, it is shown that the Noether symmetries obtained by considering the Larangians provide additional symmetries which are not provided by the Killing vectors. It is conjectured that these symmetries would always provide a larger Lie algebra of which the KV symmetres will form a subalgebra. PACS: 04.25.-g, 02.20.Sv, 11.30.-j  相似文献   

8.
Ernest Ma 《Pramana》1998,51(1-2):45-50
Given the particle content of the standard model without and with a right-handed neutrino, the requirement that all anomalies cancel singles out a set of possible global symmetries which can be gauged. I review this topic and propose a new gauge symmetryB — 3L T in the context of the minimal standard model consisting of the usual three families of quarks and leptons plus just onev R. The many interesting phenomenological consequences of this hypothesis are briefly discussed.  相似文献   

9.
From a consideration of extended hadron structure in the microlocal anisotropic space-time, the mesonic and baryonic states with their internal quantum numbers such as strangeness, hypercharge, baryon number are constructed. The SU 3 baryonic multiplets of baryons with spin (j + ) are generated from the SU 3 mesonic multiplets of mesons with spin j. The meson–baryon mass differences are also derived here. The composite particle field of hadrons for the macroscopic space-time are obtained. In particular, the meson field and one particle meson state are considered here. These one particle hadron states of the macroscopic space-time also possess the quantum numbers (strangeness, hypercharge, etc.) which are regarded as the manifestations of the anisotropic nature of the microlocal space-time. The composite fields constructed here are usable in the reduction formulae of the S-matrix approach for strong interaction.  相似文献   

10.
We study prompt hadroproduction of the charged bottomonium-like states Zb± (10610) and Zb±(10650), and the charged eharmonium-like states Zc± (3900) and Zc± (4020), at the Tevatron and the LHC, provided that these states are S-wave hadronic molecules. Using two Monte Carlo event generators, Herwig and Pythia, to simulate the production of heavy meson pairs, we derive an order-of-magnitude estimate of the production rates for these four particles. Our estimates yield a cross section at the nb level for the Zb(10610) and Zb(10650). The results for the Zc(3900) and Zc (4020) are larger by a factor of 2~30. These cross sections are large enough to be observed, and measurements at hadron colliders in the future will supplement the study using electron-positron collisions, and therefore allow to explore the mysterious nature of these exotic states.  相似文献   

11.
In this paper a three-dimensional system with five parameters is considered. For some particular values of these parameters, one finds known dynamical systems. The purpose of this work is to study some symmetries of the considered system, such as Lie-point symmetries, conformal symmetries, master symmetries and variational symmetries. In order to present these symmetries we give constants of motion. Using Lie group theory, Hamiltonian and bi-Hamiltonian structures are given. Also, symplectic realizations of Hamiltonian structures are presented. We have generalized some known results and we have established other new results. Our unitary presentation allows the study of these classes of dynamical systems from other points of view, e.g. stability problems, existence of periodic orbits, homoclinic and heteroclinic orbits.  相似文献   

12.
In these lectures the relations between symmetries, Lie algebras, Killing vectors and Noether's theorem are reviewed. A generalisation of the basic ideas to include velocity-dependent co-ordinate transformations naturally leads to the concept of Killing tensors. Via their Poisson brackets these tensors generate an a priori infinite-dimensional Lie algebra. The nature of such infinite algebras is clarified using the example of flat space-time. Next the formalism is extended to spinning space, which in addition to the standard real co-ordinates is parametrised also by Grassmann-valued vector variables. The equations for extremal trajectories (“geodesics”) of these spaces describe the pseudo-classical mechanics of a Dirac fermion. We apply the formalism to solve for the motion of a pseudo-classical electron in Schwarzschild space-time.  相似文献   

13.
It is argued that quantum mechanics follows naturally from the assumptions that there are no fundamental causal laws but only probabilities for physical processes that are constrained by symmetries, and reality is relational in the sense that an object is real only in relation to another object that it is interacting with. The first assumption makes it natural to include in the action for a gauge theory all terms that are allowed by the symmetries, enabling cancellation of infinities, with only the terms in the standard model observable at the energies at which we presently do our experiments. In this approach, it is also natural to have an infinite number of fundamental interactions.  相似文献   

14.
We describe a new class of single spin measures on then-dimensional sphereS r n of radiusr (n 4) for which Lebowitz-type [J. Lebowitz,J. Stat. Phys. 16:463 (1977)] inequalities hold. This is achieved by an appropriate parametrization ofS r n . The above class includes the uniform measures onxs Rn ¦x¦ r for any 0 p r. The second topic of this paper is an abstract formulation of the first Griffiths inequality [R. B. Griffiths,J. Math. Phys. 8:478 (1967)] and the underlying symmetry property.  相似文献   

15.
Mass measurements of the N=Z nuclei 80Zr, 76Sr, 68Se were performed for the first time and a new measurement was obtained for 80Y, using the second cyclotron CSS2 of GANIL as a high-resolution spectrometer. Ions around N=Z were produced by fusion-evaporation in the inverse 58Ni (4.32MeVA) + 24Mg and 12C reactions. New masses were measured by a time-of-flight method, with a precision of 2⋅10−6, by using well-known masses as references. Study of the double binding energy difference δV np is then performed leading to a strong N=Z Wigner effect around N=Z=40. Knowledge of new masses in this region also plays a crucial role in the modelling of the astrophysical rp process. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
We propose definitions of generalized parity (P), time-reversal (T) and charge-conjugation (C) operators such, that any diagonalizable pseudo-Hermitian Hamiltonian is invariant under the involutory symmetries C, TP, and CPT. We inquire about the peculiarities of such symmetries showing that these constitute the P-unitary and P-antiunitary symmetry generators. Moreover, we give a necessary and sufficient condition for diagonalizable pseudo-Hermitian Hamiltonians to admit P-pseudounitary and P-pseudoantiunitary symmetries.  相似文献   

17.
In this paper, the squared eigenfunction symmetries for the BTL and CTL hierarchies are explicitly constructed with the suitable modification of the ones for the TL hierarchy, by considering the BTL and CTL constraints. Also the connections with the corresponding additional symmetries are investigated: the squared eigenfunction symmetry generated by the wave function can be viewed as the generating function for the additional symmetries.  相似文献   

18.
The symmetries of a (2+1)-dimensional shallow water wave system, which is newly constructed through applying variation principle of analytic mechanics, are researched in this paper. The Lie symmetries and the corresponding reductions are obtained by means of classical Lie group approach. The (1+1) dimensional displacement shallow water wave equation can be derived from the reductions when special symmetry parameters are chosen.  相似文献   

19.
With the hypothesis that all independent degrees of freedom of basic building blocks should be treated equally on the same footing and correlated by a possible maximal symmetry, we arrive at a 4-dimensional space-time unification model. In this model the basic building blocks are Majorana fermions in the spinor repre- sentation of 14-dimensional quantum space-time with a gauge symmetry GM4D = SO(1,3)×SU(32)×U(1)A×SU(3)F. The model leads to new physics including mirror particles of the standard model. It enables us to issue some fundamental questions that include: why our living space-time is 4-dimensional, why parity is not con- served in our world, how the stability of proton is, what the origin of CP violation is and what the dark matter can be.  相似文献   

20.
葛伟宽  张毅  薛纭 《物理学报》2010,59(7):4434-4436
Rosenberg问题是一个典型而不太复杂的非完整系统问题.本文利用非完整系统的Noether对称性理论来求这个非完整力学问题的守恒量,进而得到问题的最终解.  相似文献   

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