arXiv subjects

Yu. S. Surovtsev

Publications and source records attributed to Yu. S. Surovtsev.

28 records · Page 2Linked to original sources

arXiv2000

Model-Independent Confirmation of the $σ$-Meson below 1 GeV and Indication for the $f_0(1500)$ Glueball

In the model-independent approach consisting in the immediate application to the analysis of experimental data of such general principles as analyticity and unitarity, a confirmation of the $σ$-meson at $\sim$ 665 MeV and an indication for the glueball nature of the $f_0(1500)$ state are obtained on the basis of a simultaneous description of the isoscalar s-wave channel of the $ππ$ scattering (from the threshold up to 1.9 GeV) and of the $ππ\to K\bar{K}$ process (from the threshold to $\sim$ 1.4 GeV where the 2-channel unitarity is valid). A parameterless description of the $ππ$ background is first given by allowance for the left-hand branch-point in the proper uniformizing variable. It is shown that the large $ππ$-background, usually obtained, combines, in reality, the influence of the left-hand branch-point and the contribution of a very wide resonance at $\sim$ 665 MeV. The coupling constants of the observed states with the $ππ$ and $K\bar{K}$ systems and lengths of the $ππ$ and $K\bar{K}$ scattering are obtained.

hep-ph↗

arXiv2000

Existence of the $σ$-meson below 1 GeV and $f_0(1500)$ glueball

On the basis of a simultaneous description of the isoscalar s-wave channel of the $ππ$ scattering (from the threshold up to 1.9 GeV) and of the $ππ\to K\bar{K}$ process (from the threshold to $\sim$ 1.4 GeV) in the model-independent approach, a confirmation of the $σ$-meson at $\sim$ 665 MeV and an indication for the glueball nature of the $f_0(1500)$ state are obtained. It is shown that the large $ππ$-background, usually obtained, combines, in reality, the influence of the left-hand branch-point and the contribution of a very wide resonance at $\sim$ 665 MeV. The coupling constants of the observed states with the $ππ$ and $K\bar{K}$ systems and lengths of the $ππ$ and $K\bar{K}$ scattering are obtained.

hep-ph↗

arXiv2000

Confirmation of the $σ$-Meson below 1 GeV and Indication for the $f_0(1500)$ Glueball

hep-ph↗

arXiv1998

Nucleon structure from the quasithreshold inverse pion electroproduction

The process $πN\to e^+e^- N$ (IPE), being a natural and unique laboratory for studying the hadron electromagnetic structure in the sub-$N\bar{N}$-threshold time-like region of the virtual-photon ``mass'' $λ^2$, turns out to be also very useful for investigating the nucleon weak structure. A theoretical basis of the methods for extracting practically model-independent values of the electromagnetic hadron form factors in the time-like region and for determining the weak structure of the nucleon in the space-like region from experimental data on IPE at low energies is outlined. The results of extracting, by those methods, the electromagnetic $F_1^v(λ^2)$ and pseudoscalar $G_P(t)$ form-factors of a nucleon are presented, where an indication of the existence of the state $π^\p$ in the range 500-800 MeV (possibly the first radial excitation of pion) is obtained, and the coupling constant of this new state with the nucleon is estimated.

hep-ph↗

arXiv1998

The relativistic particle with curvature and torsion of world trajectory

Local symmetries of the action for a relativistic particle with curvature and torsion of its world curve in the (2+1)-dimensional space-time are studied. With the help of the method, worked out recently by the authors (Phys.Rev., D56, 1135, 1142 (1997)), first the local-symmetry transformations are obtained both in the phase and configuration space. At the classical level, the dependence of the particle mass on the parameters of curvature and torsion and the Regge trajectory are obtained. It is shown that the tachyonic sector can be removed by a proper gauge choice.

hep-th↗

arXiv1997

The Ostrogradsky Method for Local Symmetries. Constrained Theories with Higher Derivatives

In the generalized Hamiltonian formalism by Dirac, the method of constructing the generator of local-symmetry transformations for systems with first- and second-class constraints (without restrictions on the algebra of constraints) is obtained from the requirement for them to map the solutions of the Hamiltonian equations of motion into the solutions of the same equations. It is proved that second-class constraints do not contribute to the transformation law of the local symmetry entirely stipulated by all the first-class constraints (and only by them). A mechanism of occurrence of higher derivatives of coordinates and group parameters in the symmetry transformation law in the Noether second theorem is elucidated. It is shown that the obtained transformations of symmetry are canonical in the extended (by Ostrogradsky) phase space. An application of the method in theories with higher derivatives is demonstrated with an example of the spinor Christ -- Lee model.

hep-th↗

arXiv1997

Quasigroup of Local-Symmetry Transformations in Constrained Theories

In the framework of the generalized Hamiltonian formalism by Dirac, the local symmetries of dynamical systems with first- and second-class constraints are investigated in the general case without restrictions on the algebra of constraints. The method of constructing the generator of local-symmetry transformations is obtained from the requirement for them to map the solutions of the Hamiltonian equations of motion into the solutions of the same equations. It is proved that second-class constraints do not contribute to the transformation law of the local symmetry entirely stipulated by all the first-class constraints (and only by them) of an equivalent set passing to which from the initial constraint set is always possible and is presented. A mechanism of occurrence of higher derivatives of coordinates and group parameters in the symmetry transformation law in the Noether second theorem is elucidated. In the latter case it is shown that the obtained transformations of symmetry are canonical in the extended (by Ostrogradsky) phase space. It is thereby shown in the general case that the degeneracy of theories with the first- and second-class constraints is due to their invariance under local-symmetry transformations. It is also shown in the general case that the action functional and the corresponding Hamiltonian equations of motion are invariant under the same quasigroup of local-symmetry transformations.

hep-th↗

arXiv1997

Second-Class Constraints and Local Symmetries

In the framework of the generalized Hamiltonian formalism by Dirac, the local symmetries of dynamical systems with first- and second-class constraints are investigated. For theories with an algebra of constraints of special form (to which a majority of the physically interesting theories belongs) the method of constructing the generator of local-symmetry transformations is obtained from the requirement of the quasi-invariance of an action. It is proved that second-class constraints do not contribute to the transformation law of the local symmetry which entirely is stipulated by all the first-class constraints. It is thereby shown that degeneracy of special form theories with the first- and second-class constraints is due to their quasi-invariance under local-symmetry transformations.

hep-th↗

arXiv1997

Constrained Dynamical Systems: Separation of Constraints into First and Second Classes

In the Dirac approach to the generalized Hamiltonian formalism, dynamical systems with first- and second-class constraints are investigated. The classification and separation of constraints into the first- and second-class ones are presented with the help of passing to an equivalent canonical set of constraints. The general structure of second-class constraints is clarified.

hep-th↗

arXiv1996

Dynamical Systems with First- and Second-Class Constraints and the Second Noether Theorem

Dynamical systems, described by Lagrangians with first- and second-class constraints, are investigated. In the Dirac approach to the generalized Hamiltonian formalism, the classification and separation of the first- and second-class constraints are presented with the help of passing to an equivalent canonical set of constraints. The general structure of second-class constraints is clarified. The method of constructing the generator of symmetry transformations in the second Noether theorem is given. It is proved that second-class constraints do not contribute to the transformation law of the local symmetry which entirely is entirely stipulated by all the first-class constraints.

hep-th↗