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1.
Using the linear mass spectrum of anSU (4) meson hexadecuplet, we derive the Gell-Mann-Okubo mass formula for the charmed mesons, in good agreement with experiment. The possible generalization of this method to a higher symmetry group is briefly discussed. On sabbatical leave from School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Israel. Also at Department of Physics, Bar-Ilan University, Ramat-Gan, Israel.  相似文献   

2.
It is shown that one can fit the available data on thea o(980),f o(1300) andK o * (1430) mesons as a distorted 0++ nonet using very few (5–6) parameters and an improved version of the unitarized quark model. This includes all light two-pseudoscalar thresholds, constraints from Adler zeroes, flavour symmetric couplings, unitarity and physically acceptable analyticity. The parameters include a bare or mass, an over-all coupling constant, a cutoff and a strange quark mass of 100 MeV, which is in accord with expectations from the quark model. It is found that in particular for thea 0(980) andf 0(980) the component, in the wave function is large, i.e., for a large fraction of the time the state is transformed into a virtual pair. This component, together with a similar component of for thea 0(980), and , and components for thef 0(980), causes the substantial shift to a lower mass than what is naively expected from the component alone. Mass, width and mixing parameters, including sheet and pole positions, of the four resonances are given, with a detailed pedagogical discussion of their meaning.  相似文献   

3.
Mass formulae for light meson multiplets derived by means of the exotic commutator technique are written for complex masses and considered as complex mass sum rules (CMSR). The real parts of the CMSR give the well known mass formulae for real masses (Gell-Mann-Okubo, Schwinger and ideal mixing ones) and the imaginary parts of CMSR give appropriate sum rules for the total hadronic widths - width sum rules (WSR). Most of the observed meson nonets satisfy the Schwinger mass formula (S nonets). The CMSR predict for the S nonet that the points form a rectilinear stitch (RS) on the complex mass plane. For low-mass nonets the WSR are strongly violated due to "kinematical" suppression of the particle decays, but the violation decreases as the mass increases and disappears above GeV. The slope ks of the RS is not predicted, but the data show that it is negative for all S nonets and its numerical values are concentrated in the vicinity of the value -0.5. If ks is known for a nonet, we can evaluate "kinematical" suppressions of its individual particles. The masses and the widths of the S nonet mesons submit to some rules of ordering which matter in understanding the properties of the nonet. We give the table of the S nonets indicating masses, widths, mass and width orderings. We show also mass-width diagrams for them. We suggest to recognise a few multiplets as degenerate octets. In the appendix we analyze the nonets of the 1+ mesons.Received: 6 January 2003, Revised: 19 May 2003, Published online: 20 August 2003  相似文献   

4.
We prove the uncertainty relation T V m2/c 2, which is realized on a statistical mechanical level for an ensemble of events in (1+D)-dimensional spacetime with motion parameterized by an invariant proper time , where T V is the average passage interval in for the events which pass through a small (typical) (1+D)-volume V, and m is the dispersion of mass around its on-shell value in such an ensemble. We show that a linear mass spectrum is a completely general property of a (1+D)-dimensional off-shell theory.On sabbatical leave from School of Physics and Astronomy, Tel Aviv Uniersity, Ramat Aviv, Israel. Also at Department of Physics, Bar-Ilan University, Ramat-Gan, Israel  相似文献   

5.
High energypp and data on elastic scattering and total cross sections are analyzed in a model including the pomeron, odderon and secondary reggeons. A dipole model is used for the pomeron and for the odderon. By construction, our (bare) pomeron ansatz produces a single dip, as observed experimentally. The model reproduces the logarithmically rising cross sections with a unit pomeron intercept, but better fits are obained when a small non-zero value of the parameter = p (0) is allowed for. Predictions for the future accelerators (UNK, LHC, SSC) are given.On leave of absence from the Institute for Theoretical Physics, Kiev-130, USSR  相似文献   

6.
We study quasifinite highest weight modules over the supersymmetric extension of theW 1+ algebra on the basis of the analysis by Kac and Radul. We find that the quasifiniteness of the modules is again characterized by polynomials, and obtain the differential equations for highest weights. The spectral flow, free field realization over the (B, C)-system, and the embedding into (|) are also presented.Address after April 1, 1994: Research Institute for Mathematical Sciences, Kyoto University, Kyoto 606, JapanAddress after April 1, 1994: Uji Research Center, Yukawa Institute for Theoretical Physics, Kyoto University, Uji 611, Japan  相似文献   

7.
We show that linear Regge trajectories for mesons and glueballs, and the cubic mass spectrum associated with them, determine a relation between the masses of the meson and the scalar glueball, , which implies MeV. We also discuss relations between the masses of the scalar, tensor and 3-- glueballs, , which imply MeV.  相似文献   

8.
Two thought experiments are discussed which suggest, first, a geometric interpretation of the concept of a (say, vector) potential (i.e., as a kinematic quantity associated with a transformation between moving frames of reference suitably related to the problem) and, second, that, in a quantum treatment one should extend the notion of the equivalence principle to include not only the equivalence of inertial forces with suitable real forces, but also the equivalence of potentials of such inertial forces and the potentials of suitable real forces. The two types of cancellation are physically independent of each other, because of the Aharonov-Bohm effect. Finally, we show that the latter effect itself can be understood geometrically as a kinematic effect arising upon the transformation between the two reference frames.On leave of absence from the Department of Physics, Tel-Aviv University, Israel, and the Department of Physics, Yeshiva University, New York.Supported by the NSF under Contract GP-14911.  相似文献   

9.
A systematic study of possible deuteronlike twomeson bound states,deusons, is presented. Previous arguments that many such bound states may exist are elaborated with detailed arguments and numerical calculations including, in particular, the tensor potential. This tensor potential which is crucial for the deuteron binding is shown to be very important also in the mesonic case. Especially, in the pseudoscalar3 P 0 pseudoscalar-vector and vector-vector channels the important observation is made that the centrifugal barrier from theP-wave can be overcome by the 1/r 2 and 1/r 3 terms of the tensor potential. In the heavy meson sector one-pion exchange alone is strong enough to form at least deuteronlike and composites bound by approximately 50 MeV. Composites of and states bound by pion exchange alone are expected near the thresholds, while in the light meson sector one generally needs some additional short range attraction to form bound states. The quantum numbers of these states areI=0, andJ PC=0–+, 1++ for the states andI=0,J PC=0++, O–+, 1+– and 2++ for the composites. In the states: b (10545), b1(10562) are predicted and in , one finds the states: b (10590), bQ (10582),h b(10608), b2(10602). Near the threshold the states: c (3870), c0(3870) are predicted, and near the threshold one finds the states: b0(4015), c (4015),h c(4015), c2(4015). Within the light meson sector pion exchange gives strong attraction for and systems with quantum numbers where the best non- candidates exist, although pion exchange alone is not strong enough to support such bound states. Thus, although one cannot conclude with certainty it to be the case, this fact does favour the picture that the (1440) and thef 1 (1420) are mainly composites and thef 0(1710) mainly a bound state, while thef 0(1515) andf 2(1520) could be predominantly composites. If the predicted and states are found, these would support this interpretation of the light states. In channels with exotic flavour orCP quantum numbers pion exchange is generally repulsive or quite weak. Therefore one does not expect that such deuteronlike bound states exist, althoughB*B* may be an exception.  相似文献   

10.
The relativistic momentum approximation has been used to calculate the tensor analyzing capacity F20 of the d p reaction. At high proton moments (p50 MeV/sec), the dependence of F20 of the parameters of the n vertex becomes substantial, which shows that experiments on F20 can provide information on the electromagnetic form factor of the n transition.Research performed with financial support from the Russian Fundamental Research Fund (project code 93-02-3514).Nuclear Physics Research Institute, Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 35–38, October, 1994.  相似文献   

11.
, Bi2Te3-Bi2Se3. , , , . .
Influence of ageing on change in electrical properties of semiconducting systems of Bi2Te3-Bi2Se3
The paper describes the effect of ageing observed on a semiconducting system Bi2Te3 — Bi2Se3. It is shown that the change in electrical conductivity and thermoelectric force, which takes place during ageing, is caused by the change in concentration of the free electrons. The influence of this process on the efficiency of equipment employing the Peltier effect is analyzed.
  相似文献   

12.
Using the ARGUS detector at thee + e storage ring DORIS II, we have studied nine decay modes of theD 0 meson. In addition to a higher-precision determination of the branching ratios for these modes, several new channels, the decays , and , have been observed for the first time.Supported in part by the Institute of Physics, University of Lund, Sweden  相似文献   

13.
Ground-state masses ofq 2 –2 states (true and mock baryonium) are investigated in the framework of a Bethe-Salpeter formalism motivated from QCD. The four-particle system is described by pairwise interactions betweenqq orq pairs with a spectator approximation for the non-interacting pair. The quark-quark interactions are Coulomb plus harmonic interactions; the harmonic terms have been modified to produce linear confinement for heavier quarks, in agreement with experimental spectra. The confining interaction is proportional to the strong coupling constant s. Apart from the quark masses, the confining interaction is characterized by three basic parameters: (i) a universal spring constant 0; (ii) a constantC 0/ 0 2 , which defines the vacuum structure; (iii) a constantA 0, which provides a smooth transition from quadratic to linear confinement as one goes from light to heavy quark systems. These three constants [ 0 = 0.158 GeV;C 0=0.296;A 0=0.0283] have been shown to produce excellent fits to all quarkonia states [q ,q ,Q ] as well as baryon spectra (qqq); thus our predictions forq 2 2 states contain no free parameters. In this model, theL=0 ground states occur in the range 1.8–2 GeV, 2.15–2.3 GeV and 6.72–6.75 GeV foru 2 2,s 2 2 andc 2 2 states, respectively. We discuss the prospects for these states to be seen experimentally. In the case of thes 2 2 state, this is likely to have a rather narrow width, and may correspond to theX(2.22 GeV) meson observed in radiative decays of theJ/ meson. Thec 2 2 state might also be visible as a resonance with an appreciable width.Research supported in part by the National Science Foundation under grant NSF-PHY 86-06364Research supported in part by the U.S. Department of Energy  相似文献   

14.
Giving an ultraviolet regularization and volume cut off we construct a nuclear Riemannian structure on the Hilbert manifold of gauge orbits. This permits us to define a regularized Laplace-Beltrami operator on and an associated global diffusion in governed by . This enables us to define, via a Feynman-Kac integral, a Euclidean, continuum regularized Yang-Mills process corresponding to a suitable regularization (of the kinetic term) of the classical Yang-Mills Lagrangian onT .On leave of absence from Zaragoza University (Spain)Laboratoire associé au CNRS  相似文献   

15.
In this work we study the departure from the ideal - mixing angle within the framework of the Nambu-Jona-Lasinio model. In this context we show that the flavor symmetry breaking is unable to produce the shifting of the ideal mixing. We found that a nonet symmetry breaking in the neutral vector sector is necessary to regulate the non-strange content of the meson. The phenomenology is well described by our proposal.Received: 14 November 2002, Revised: 22 April 2003, Published online: 11 July 2003  相似文献   

16.
TheSU(N) Yang-Mills equations are considered in a four-dimensional Euclidean box with periodic boundary conditions (hypertorus). Gauge-invariant twists can be introduced in these boundary conditions, to be labeled with integersn (= –n ), defined moduloN. The Pontryagin number in this space is often fractional. Whenever this number is zero there are solutions to the equationsG =0 HereG is the covariant curl. When this number is not zero we find a set of solutions to the equations , provided that the periodsa of the box satisfy certain relations.Work supported in part by the US Department of Energy under Contract No. DE-AC-03-76ER 00068 and by the Fairchild FoundationOn leave from the Institute for Theoretical Physics, University of Utrecht, P.O. Box 80.006, NL-3508 TA Utrecht, The Netherlands  相似文献   

17.
Zusammenfassung Es handelt sich um eine aus vier Rechtecken von verschiedenen Materialien bestehende Membran, die durch eine allgemeine Anfangserregung in freie Schwingungen versetzt wird. Die angewandte klassische Lösungsmethode läßt sich auf noch allgemeinere Fälle erweitern. Die theoretischen Ausführungen werden erstens am Beispiel einer homogenen Membran erklärt und zweitens auf eine durch einen Momentanimpuls zur Schwingung gebrachte vierteilige Membran angewendet.
, , . . , -, , -, , .
  相似文献   

18.
The paper deals with the possibility of the existence of 2 mixing and the question of the Gell-Mann-Okubo formula (GOF) for bosons.  相似文献   

19.
The real part of the dielectric constant , the heat capacityc p, the infrared reflectivity, and the X-ray diffraction of TlGaSe2 have been measured in the temperature range from 12 K (30K) to 300 K. Both andc p show two anomalies at about 110 K and 120 K. A study of the hysteresis loop as well as an investigation of the dielectric dispersion in the microwave region show that the phase below 110 K is ferroelectric. The crystal structure remains nearly unchanged in the course of the phase transition. The loss of the symmetry (C2/cCc) results from small positional shifts of the T1 atoms in the ab plane accompanied by a discontinuity in the axial ratios. We suggest, that the ferroelectricity is caused by the stereochemically active electron lone pair configuration of the Tl+ ion. Thus TlGaSe2 may provide the first example for ferroelectricity caused by this mechanism.  相似文献   

20.
A complete analysis of the long range part of theK L –K S mass difference in next-to-leading-order of chiral perturbation theory is presented. We find a large positive contribution from transitions via S=2 vertices and irreducible loop diagrams involving two separate weak interactions. Single-particle pole contributions are small if an approximate nonet symmetry for the couplings of the singlet 1 holds. They tend to cancel the short distance contribution from box diagrams. In total, good agreement with experiment is obtained. In a second part we study theK L K S mass difference in a phenomenological model of nonleptonic weak transitions which explains the I=1/2 rule in terms of non-perturbative quark-quark correlations. The numerical results agree well with those presented before.  相似文献   

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