arXiv subjects
Publications and source records attributed to A. I. Veselov.
The correction to the string junction three-quark potential in a baryon due to the proper moment of inertia of the QCD string is calculated. The magnitudes of the string corrections in P-wave heavy baryons are estimated.
A comprehensive study of the color singlet heavy quark states above T_c is given, using the Field Correlator Method (FCM) for nonperturbative Q{\bar Q} potentials and the screened Coulomb potential with the T-dependent Debye radius. Using these potentials we calculate binding energies and melting temperatures of heavy mesons and baryons in the deconfined phase of quark-gluon plasma and the J/ψand Upsilon disintegration cross sections via the gluon absorption.
We analyze the static potential of a quark-antiquark pair at $T\,\geq\,T_c$, where $T_c$ is a temperature of a deconfinement phase transition in QCD. We discuss the possibility that the non-perturbative part of this potential can be studied through the modification of the correlation functions, which define the quadratic field correlators of the nonperturbative vaccuum fields. We use the non-perturbative quark-antiquark potential derived in this way and the screened one-gluon-exchange potential with $T$-dependent Debye screening mass to calculate $J/ψ$, $Υ$ and $Ω_{bbb}$ binding energies and melting temperatures in the deconfined phase of the full 2-flavors QCD.
We use the screened Coulomb potential with $r$-dependent coupling constant and the non--perturbative quark--antiquark potential derived within Field Correlator Method (FCM) to calculate $J/ψ$ and $Υ$ binding energies and melting temperatures in the deconfined phase of quark-gluon plasma.
We use the non-perturbative Q\bar Q potential at finite temperatures derived in the Field Correlator Method to obtain binding energies for the lowest eigenstates in the Q\bar Q and QQQ systems (Q=c,b). The three--quark problem is solved by the hyperspherical method. The solution provides an estimate of the melting temperature and the radii for the different diquark and triquark bound states. In particular we find that J/ψand $ccc$ ground states survive up to T \sim 1.3 T_c, where T_c is the critical temperature, while the corresponding bottomonium states survive even up to higher temperature, T \sim 2.2 T_c.
The main objective of this presentation is to point out that the Upper bound on the cutoff in lattice Electroweak theory is still unknown. The consideration of the continuum theory is based on the perturbation expansion around trivial vacuum. The internal structure of the lattice Weinberg - Salam model may appear to be more complicated especially in the region of the phase diagram close to the phase transition between the physical Higgs phase and the unphysical symmetric phase of the lattice model, where the continuum physics is to be approached. We represent the results of our numerical investigation of the quenched model at infinite bare scalar self coupling $λ$. These results demonstrate that at $λ= \infty$ the upper bound on the cutoff is around $\fracπ{a} = 1.4$ Tev. The preliminary results for finite $λ$ are also presented. Basing on these results we cannot yet make a definite conclusion on the maximal value of the cutoff admitted in the lattice model, although we have found that the cutoff cannot exceed the value around $1.4 \pm 0.2$ Tev for a certain particular choice of the couplings ($λ= 0.009$, $β= 12$, $θ_W = 30^o$) for the lattices of sizes up to $12^3\times16$. We also observe that the topological defects, which are to be identified with quantum Nambu monopoles, dominate in vacuum in the vicinity of the transition. This indicates that the vacuum of the model is different from the trivial one. In addition we remind the results of the previous numerical investigations of the SU(2) gauge - Higgs model, where the maximal reported value of the cutoff was around 1.5 Tev.
The ground and $P$-wave excited states of $nnn$, $nns$ and $ssn$ baryons are studied in the framework of the field correlator method using the running strong coupling constant in the Coulomb-like part of the three-quark potential. The string correction for the confinement potential of the orbitally excited baryons, which is the leading contribution of the proper inertia of the rotating strings, is estimated.
We considered the lattice electroweak theory at realistic values of $α$ and $θ_W$ and for large values of the Higgs mass. We investigated numerically the properties of topological objects that are identified with quantum Nambu monopoles. We have found that the action density near the Nambu monopole worldlines exceeds the density averaged over the lattice in the physical region of the phase diagram. Moreover, their percolation probability is found to be an order parameter for the transition between the symmetric and the broken phases. Therefore, these monopoles indeed appear as real physical objects. However, we have found that their density on the lattice increases with increasing ultraviolet cutoff. Thus we conclude, that the conventional lattice electroweak theory is not able to predict the density of Nambu monopoles. This means that the description of Nambu monopole physics based on the lattice Weinberg - Salam model with finite ultraviolet cutoff is incomplete. We expect that the correct description may be obtained only within the lattice theory that involves the description of TeV - scale physics.
The ground and P-wave excited states of nnn, nns and ssn baryons are studied in the framework of the Field Correlator Method using the running strong coupling constant in the Coulomb-like part of the three-quark potential. The running coupling is calculated up to two loops in the background perturbation theory. The three-quark problem has been solved using the hyperspherical functions method. The masses of the S- and P-wave baryons are presented. Our approach reproduces and improves the previous results for the baryon masses obtained for the freezing value of the coupling constant. The string correction for the confinement potential of the orbitally excited baryons, which is the leading contribution of the proper inertia of the rotating strings, is estimated.
The $η$ production in the $(n,n')$ bottomonium transitions $Υ(n) \to Υ(n') η, $ is studied in the method used before for dipion heavy quarkonia transitions. The widths $Γ_η(n,n')$ are calculated without fitting parameters for $n=2,3,4,5, n'=1$. Resulting $Γ_η(4,1)$ is found to be large in agreement with recent data. Multipole expansion method is shown to be inadequate for large size systems considered.
We provide a check of the accuracy of the auxiliary field formalism used to derive the Effective Hamiltonian for baryons in the Field Correlator Method. To this end we compare the solutions for the Effective Hamiltonian with those obtained from the solution of the Salpeter equation. Comparing these results gives a first estimate of the systematic uncertainty due to the use of the auxiliary field formalism for baryons.
We investigate numerically lattice Weinberg - Salam model without fermions for realistic values of the fine structure constant and the Weinberg angle. We also analyze the data of the previous numerical investigations of lattice Electroweak theory. We have found that moving along the line of constant physics when the lattice spacing $a$ is decreased, one should leave the physical Higgs phase of the theory at a certain value of $a$. Our estimate of the minimal value of the lattice spacing is $a_c = [430\pm 40 {\rm Gev}]^{-1}$.
QCD string model formulated in the framework of the Field Correlator Method (FCM) in QCD is employed to calculate the masses of $Σ_c$, $Ξ_c$ and recently observed at Tevatron $Σ_b$, $Ξ_b$ baryons and their orbital excitations. The auxiliary field formalism allows one to write a simple local form of the effective Hamiltonian for the three quark system, which comprises both confinement and relativistic effects, and contains only universal parameters: the string tension $σ$, the strong coupling constant $α_s$, and the bare (current) quark masses $m_i$. We calculate the hyperfine splitting with account of the both perturbative and non--perturbative spin-spin forces between quarks in a baryon. For the orbital excitations we estimate the string correction for the confinement potential - the leading correction to the contribution of the proper inertia of the rotating string. This correction lowers the masses of the P-states by 50 MeV. We find our numerical results to be in good agreement with experimental data.
Dipion transitions of $Υ(nS)$ with $n=5, n'=1,2,3$ are studied using the Field Correlator Method, applied previously to dipion transitions with $n=2,3,4$ The only two parameters of effective Lagrangian were fixed in that earlier study, and total widths $Γ_{ππ} (5, n')$ as well as pionless decay widths $Γ_{BB} (5S), Γ_{BB^*} (5S), Γ_{B^*B^*}(5S)$ and $Γ_{KK} (5, n')$ were calculated and are in a reasonable agreement with experiment. The experimental $ππ$ spectra for $(5,1)$ and (5,2) transitions are well reproduced taking into account FSI in the $ππ$.
There exist several types of monopole - like topological defects in Electroweak theory. We investigate properties of these objects using lattice numerical methods. The intimate connection between them and the dynamics of the theory is established. We find that the density of Nambu monopoles cannot be predicted by the choice of the initial parameters of Electroweak theory and should be considered as the new external parameter of the theory. We also investigate the difference between the versions of Electroweak theory with the gauge groups $SU(2)\otimes U(1)$ and $SU(2)\otimes U(1)/Z_2$. We do not detect any difference at $α\sim {1/128}$. However, such a difference appears in the unphysical region of large coupling constant $α> 0.1$.
Dipion transitions of the subthreshold bottomonium levels $Υ(nS)\to Υ(n'S) ππ$ with $n>n', n=2,3,4, n'=1,2$ are studied in the framework of the chiral decay Lagrangian, derived earlier. The channels $B\bar B, B\bar B^*+ c.c, B^* \bar B^*$ are considered in the intermediate state and realistic wave functions of $Υ(n S),B$ and $B^*$ are used in the overlap matrix elements. Imposing the Adler zero requirement on the transition matrix element, one obtains 2d and 1d dipion spectra in reasonable agreement with experiment.
The $η$ production in the $(n,n')$ bottomonium transitions $Υ(n) \to Υ(n') η, $ is studied in the method used before for dipion heavy quarkonia transitions. The widths $Γ_η(n,n')$ are calculated without fitting parameters for $n=2,3,4,5, n'=1$.Resulting $Γ_η(4,1)$ is found to be large in agreement with recent data.
Two- and three-body decays of $Υ(5S)$ into $BB, $$ BB^*, $ $ B^*B^*,$ $ B_sB_s, $ $B_sB_s^*, $ $B_s^* B_s^*$ and $BB^*π, B^*B^*π$ are evaluated using the theory, developed earlier for dipion bottomonium transitions. The theory contains only two parameters, vertex masses $M_{br}$ and $M_ω$, known from dipion spectra and width. Predicted values of $Γ_{tot}(5S)$ and six partial widths $Γ_k(5S), k=BB, BB^*,...$ are in agreement with experiment. The decay widths $Γ_{5S}(πBB^*)$ and $Γ_{5S}(πB^*B^*)$ are also calculated and found to be of the order of 10 keV.