Yu. A. Simonov - Institute of Theoretical and Experimental Physics, Moscow, Russia

Yu. A. Simonov
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Name
Yu. A. Simonov
Affiliation
Institute of Theoretical and Experimental Physics, Moscow, Russia
City
Moscow
Country
Russia

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High Energy Physics - Phenomenology (50)
 
High Energy Physics - Lattice (10)
 
Nuclear Theory (6)
 
High Energy Physics - Experiment (5)
 
High Energy Physics - Theory (4)
 
Physics - Atomic Physics (2)
 
High Energy Astrophysical Phenomena (1)

Publications Authored By Yu. A. Simonov

Nonperturbative effects in the quark-gluon thermodynamics are studied in the framework of Vacuum Correlator Method. It is shown, that two correlators: colorelectric $D_1^E(x)$ and colormagnetic $D^H(x)$, provide the Polyakov line and the colormagnetic confinement in the spatial planes respectively. As a result both effects produce the realistic behavior of $P(T)$ and $s(T)$, being in good agreement with numerical lattice data. Read More

The $SU(3)$ equation of state ($P(T),\,s(T),\,I(T)$) are calculated within the Field Correlator Method both in the confined and the deconfined phases. The basic dynamics in our approach is contained in the vacuum correlators, both of the colorelectric (CE) and colormagnetic (CM) types, which ensure CE and CM confinement below $T_c$ and CM confinement and Polyakov loops above $T_c$. The resulting values of $T_c$ and $P(T),\,I(T)$, $s(T)$ are in good agreement with lattice measurements. Read More

Spectra of $q \bar q$ mesons are investigated in the framework of the Hamiltonian obtained from the relativistic path integral in external homogeneous magnetic field. The spectra of all 12 spin-isospin s-wave states generated by $\pi$- and $\rho$-mesons with different spin projections, are studied analytically as functions of the field strength. Three types of behavior with characteristic splittings are found. Read More

Spectra of $q \bar{q}$ hadrons are investigated in the framework of the Hamiltonian obtained from the relativistic path integral in external homogeneous magnetic field. The spectra of all 12 spin-isospin s-wave states, generated by $\pi$ and $\rho$ mesons with different spin projections, are studied both analytically and numerically on the lattice as functions of (magnetic field) $eB$. Results are in agreement and demonstrate three types of behavior, with characteristic splittings predicted by the theory. Read More

The influence of electric stochastic fields on the relativistic charged particles is investigated in the gauge invariant path integral formalism. Using the cumulant expansion one finds the exponential relaxation of the charge Green's function both for spinless and Dirac charges. Read More

Perturbation theory of thermodynamic potentials in QCD at $T>T_c$ is considered with the nonperturbative background vacuum taken into account. It is shown that the magnetic confinement in the QCD vacuum prevents the infrared catastrophe of the perturbation theory present in the case of the free vacuum (the "Linde problem"). A short discussion is given of the applicability of the nonperturbative formalism at large $T$ and of the relation with the HTL theory. Read More

2016Mar
Authors: Yu. A. Simonov1
Affiliations: 1State Research Center Institute of Theoretical and Experimental Physics

The standard $SU(2) \times U(1)$ fields are considered in 4D plus one extra compact dimension. As a result two basic effects are obtained. First, four Goldstone-like scalars are produced, three of them are used to create longitudinal modes of the $W,Z$ fields, while the fourth becomes the Higgs-like scalar. Read More

2015Sep
Authors: Yu. A. Simonov1
Affiliations: 1State Research Center, Institute of Theoretical and Experimental Physics

The effective chiral Lagrangian in both nonlocal form $L_{ECCL}$ and standard local form $L_{ECL}$ are derived in QCD using the confining kernel, obtained in the vacuum correlator formalism. As a result all coefficients of $L_{ECL}$ can be computed via $q\bar q$ Green's functions. In the $p^2$ order of $L_{ECL}$ one obtains GOR relations and quark decay constants $f_a$ are calculated $a=1,. Read More

2015Jun
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

The nonperturbative parton distributions, obtained from the Lorentz contracted wave functions, are analyzed in the formalism of many-particle Fock components and their properties are compared to the standard perturbative distributions. We show that the collinear and IR divergencies specific for perturbative evolution treatment are absent in the nonperturbative version, however for large momenta< $ \vep^2_i \gg \sigma$ (string tension), the bremsstrahlung kinematics is restored. A preliminary discussion of possible nonperturbative effects in DIS and high energy scattering is given, including in particular a possible role of multihybrid states in creating ridge-type effects. Read More

Hadron decay widths are shown to increase in strong magnetic fields as $\Gamma (eB) \sim \frac{eB}{\kappa} \Gamma(0)$. The same mechanism is shown to be present in the production of the sea quark pair inside the confining string, which decreases the string tension with the growing $eB$ parallel to the string . On the other hand, the average energy of the $q\bar q$ holes in the string world sheet increases, when the direction of $\mathbf{B}$ is perpendicular to the sheet. Read More

Decay constants of the charged and neutral pions in magnetic field are considered in the framework of the effective quark-antiquark lagrangian respecting Gell-Mann--Oakes--Renner (GOR) relations at zero field. The $\sqrt{\frac{e_qB}{\sigma}}$ dependence is found in strong fields $e_qB\gg \sigma$ for the neutral pion, while the charged pion constant decreases as $\sqrt{\frac{\sigma}{e_qB}}$. Read More

2015Feb
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

A theory of lepton decay constants based on the path-integral formalism is given for chiral and vector mesons. Decay constants of the pseudoscalar and vector mesons are calculated and compared to other existing results. Read More

Radiative decays of $X(3872)$ are studied in single-channel approximation (SCA) and in the coupled-channel (CC) approach, where the decay channels $D\bar D^*$ are described with the string breaking mechanism. In SCA the transition rate $\tilde{\Gamma}_2=\Gamma(2\,{}^3P_1 \rightarrow \psi\gamma)=71.8$~keV and large $\tilde{\Gamma}_1=\Gamma(2\,{}^3P_1\rightarrow J/\psi\gamma)=85. Read More

2014Nov
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

The Lorentz contracted form of the static wave functions is used to calculate the valence parton distributions for mesons and baryons, boosting the rest frame solutions of the path integral Hamiltonian. It is argued that nonperturbative parton densities are due to excited multigluon baryon states. A simple model is proposed for these states ensuring realistic behavior of valence and sea quarks and gluon parton densities at $Q^2= 10 (GeV/c)^2$. Read More

2014Sep
Authors: Yu. A. Simonov1
Affiliations: 1State Research Center Institute of Theoretical and Experimental Physics, Moscow, Russia

Wave functions and energy eigenvalues of the path integral Hamiltonian are studied in Lorentz frame moving with velocity $v$. The instantaneous interaction produced by the Wilson loop is shown to be reduced by an overall factor $\sqrt{1-(\frac{v}{c})^2}$. As a result one obtains the boosted energy eigenvalues in the Lorentz covariant form $E= \sqrt{\veP^2+M^2_0}$, where $M_0$ is the c. Read More

Magnetic susceptibility of the quark matter in QCD is calculated in a closed form for an arbitrary chemical potential \mu. For small \mu, \mu< T^2, the oscillations as functions of eB occur, characteristic of the de Haas-van Alphen effect. Read More

Magnetic susceptibility in the deconfined phase of QCD is calculated in a closed form using a recent general expression for the quark gas pressure in magnetic field. Quark selfenergies are entering the result via Polyakov line factors and ensure the total paramagnetic effect, increasing with temperature. A generalized form of magnetic susceptibility in nonzero magnetic field suitable for experimental and lattice measurements is derived, showing a good agreement with available lattice data. Read More

Relativistic Hamiltonians, derived from the path integrals, are known to provide a simple and useful formalism for hadrons spectroscopy in QCD. The accuracy of this approach is tested using the QED systems, and the calculated spectrum is shown to reproduce exactly that of the Dirac hydrogen atom, while the Breit-Fermi nonrelativistic expansion is obtained using Foldy-Wouthuizen transformation. Calculated positronium spectrum, including spin-dependent terms, coincides with the standard QED perturbation theory to the considered order O(alpha^s). Read More

Vacuum energy of quarks participates in the pressure balance at the temperature transition T_c and defines the dependence of T_c on m_q. We first check this dependence in absence of magnetic fields eB vs known lattice data, and then take into account the known strong dependence of the quark condensate on eB. The resulting function T_c(eB, m_q) is valid for all eB, m_q< \sqrt\sigma and explains the corresponding lattice data. Read More

Relativistic world-line Hamiltonian for strongly interacting 3q systems in magnetic field is derived from the path integral for the corresponding Green's function. The neutral baryon Hamiltonian in magnetic field obeys the pseudomomentum conservation and allows a factorization of the c.m. Read More

Nonperturbative treatment of quark-hadron transition at nonzero temperature T and chemical potential mu in the framework of Field Correlator Method is generalized to the case of nonzero magnetic field B. A compact form of the quark pressure for arbitrary B, mu, T is derived. As a result the transition temperature is found as a function of B and mu, which depends on only parameters: vacuum gluonic condensate G_2 and the field correlator D_1^E(x), which defines the Polyakov loops and it is known both analytically and on the lattice. Read More

2013Aug
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

Processes with oppositely charged spinor particles in initial and/or final states in homogeneous magnetic field B are subject to focusing effects in their relative motion, which yield the amplifying factors in probabilities growing as $eB$. In addition the increasing energy of some Landau levels influences the phase space. As a result some processes in the proper spin states can be enlarged as $\sim \frac{eB}{\kappa^2}$, where $\kappa^2$ is the characteristic 2d phase space factor available without magnetic field. Read More

We study the q \bar q structure embedded in chiral mesons in response to external magnetic fields, using the chiral Lagrangian with q \bar q degrees of freedom derived earlier. We show that GMOR relations hold true for neutral chiral mesons, while they are violated for the charged ones for eB>sigma=0.2 GeV^2. Read More

We find a new correction to the hydrogen atom ground state hyperfine energy levels splitting in magnetic field. It can be interpreted as magnetic focusing of the wave function at the origin. The effect might be within the reach of experiment. Read More

We study the relativistic quark-antiquark system embedded in magnetic field. The Hamiltonian containing confinement, one gluon exchange and spin-spin interaction is derived. We analytically follow the evolution of the lowest meson states as a functions of MF strength. Read More

2013Apr
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

Spin interactions in relativistic quark-antiquark system in magnetic field is considered in the framework of the relativistic Hamiltonian, derived from the QCD path integral. The formalism allows to separate spin-dependent terms from the basic spin-independent interaction, contained in the Wilson loop, and producing confining and gluon exchange interaction. As a result one obtains relativistic spin-spin interaction $V_{ss}$, generalizing its nonrelativistic analog. Read More

2013Mar
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

The proper-time 4d path integral is used as a starting point to derive the new explicit parametric form of the quark-antiquark Green's function in gluonic and QED fields, entering as a common Wilson loop. The subsequent vacuum averaging of the latter allows to derive the instantaneous Hamiltonian. The explicit form and solutions are given in the case of the $q\bar q$ mesons in magnetic field. Read More

2012Dec
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

Strong magnetic fields in the range $ eB\gg m^2_\pi $ effectively probe internal quark structure of chiral mesons and test basic parameters of chiral theory, such as $\lan\bar q q\ran, f_\pi$. We argue on general grounds that $\lan\bar q q\ran$ should grow linearly with $eB$ when charged quark degrees of freedom come into play. To make explicit estimates we extend previously formulated chiral theory, including quark degrees of freedom, to the case of strong magnetic fields and show that the quark condensate $|\lan \bar q q\ran|_{u,d}$ grows quadratically with $eB$ for $eB\la 0. Read More

Perturbative gluon exchange interaction between quark and antiquark, or in a 3q system, is enhanced in magnetic field and may cause vanishing of the total q\bar q or 3q mass, and even unlimited decrease of it - recently called the magnetic collapse of QCD. The analysis of the one-loop correction below shows a considerable softening of this phenomenon due to q\bar q loop contribution, similarly to the Coulomb case of QED, leading to approximately logarithmic dumping of gluon exchange interaction at large magnetic field. Read More

2012Nov
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

Neutral systems containing two identical particles, in homogeneous magnetic field are shown to obey exact factorizable solutions both in nonrelativistic and relativistic formalism, similarly to the neutral two-body systems. Concrete examples of the helium atom and the neutron as a (ddu) system are considered. Read More

2012Nov
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia, 2Institute of Theoretical and Experimental Physics, Moscow, Russia

Magnetic moments of charged and neutral mesons are calculated with the use of the relativistic Hamiltonian derived from the path integral form of the $q_1\bar q_2$ Green's function. The magnetic moments are shown to be expressed via the average quark energies which are defined by the fundamental quantities: the string tension $\sigma$, the current quark masses, and the strong coupling constant $\alpha_s$. Resulting values for vector, axial, and tensor light and $K$ mesons agree well with all available lattice data. Read More

Theory of strong decays defines in addition to decay widths, also the channel coupling and the mass shifts of the levels above the decay thresholds. In the standard decay models of the 3P0 type the decay vertex is taken to be a phenomenological constant "gamma" and such a choice leads to large mass shifts of all meson levels due to real and virtual decays, the latter giving a divergent contribution. Here we show that taking the microscopic details of decay vertex into account, one obtains new string width coefficient, which strongly suppresses virtual decay contribution. Read More

We study the relativistic quark-antiquark system embedded in magnetic field (MF). The Hamiltonian containing confinement, color Coulomb and spin-spin interaction is derived. We analytically follow the evolution of the lowest neutral meson state as a function of MF strength. Read More

2012May
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

The meson spectrum of QCD is studied in the framework of nonperturbative QCD as a function of varying quark masses $m_q$. It is shown, that the total spectrum consists of two branches: 1) the standard one, which may be called the flux-tube spectrum, depending approximately linearly on $m_q$ and 2) the chiral symmetry breaking (CSB) spectrum for pseudoscalar flavor nonsinglet (PS) mesons, with mass dependence $\sqrt{m_q}$. The formalism for PS mesons is derived from the QCD Lagrangian with $m_q$ corrections, and a unified form of the PS propagator was derived. Read More

2012Mar
Authors: Yu. A. Simonov1
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia

The QCD-like gauge theory with adjoint fermions is considered in the field correlator formalism and the total spectrum of mesons and glueballs is obtained in agreement with available lattice data. A new state of a white fermion appears, as a bound state of the adjoint fermion and gluon with the mass close to that of glueball. It is shown, that the main features of spectra and thermodynamics of adjoint fermions can be explained by this new bound state. Read More

2012Feb
Affiliations: 1Institute of Theoretical and Experimental Physics, Moscow, Russia, 2Institute of Theoretical and Experimental Physics, Moscow, Russia, 3Institute of Theoretical and Experimental Physics, Moscow, Russia, 4Dept.of Physics and Astronomy, Vrije Universiteit, Amsterdam, The Netherlands

Radiative decays of X(3872) with $J^{PC}=1^{++}$ are studied in the coupled-channel approach, where the $c\bar c$ states are described by relativistic string Hamiltonian, while for the decay channels $DD^*$ a string breaking mechanism is used. Within this method a sharp peak and correct mass shift of the $2 {}^3P_1$ charmonium state just to the $D^0D^{*0}$ threshold was already obtained for a prescribed channel coupling to the $DD^*$ decay channels. For the same value of coupling the normalized wave function (w. Read More

A new mechanism of baryon-antibaryon production via nonperturbative double pair creation in intermediate mesons is proposed and the theory contains no fitting parameters. It is shown, that near-threshold resonances are responsible for enhancements in electroproduction cross sections: $\psi(4S)$ for $\Lambda^+_c \Lambda^-_c, \Upsilon (6S)$ for $\Lambda_b \bar \Lambda_b$. An admixture of intermediate $D$- wave resonances produces angular dependence in differential cross section and can explain unusual behavior of the ratio $G_E/G_M$ for the proton. Read More

The nonperturbative mechanism of baryon-antibaryon production due to double quark pair $(q\bar q)$($q\bar q)$ generation inside a hadron is considered and the amplitude is calculated as matrix element of the vertex operator between initial and final hadron wave functions. The vertex operator is expressed solely in terms of first principle input: current quark masses, string tension $\sigma$ and $\alpha_s$. In contrast to meson-meson production via single pair generation, in baryon case a new entity appears in the vertex: the vacuum correlation length $\lambda $, which was computed before through string tension $\sigma$. Read More

Dynamical equations for fermion masses are derived using high scale universal mass generation and consequent mass evolution due to $SU(3), SU(2)$, and U(1$ gauge interaction. Assuming mass generation at the GUT scale $M=10^{14}$ GeV, one obtains hierarchy and a large spread in fermion masses with roughly correct values of $m_\nu, m_\tau, m_t, m_b$ in the third generation. The smallness of neutrino mass, $\nu_3\sim 10^{-12} m_{t}$, naturally arises in the solution. Read More

Dynamics of hadro-quarkonium system is formulated, based on the channel coupling of a light hadron (h) and heavy quarkonium (Q\bar{Q}) to intermediate open-flavor heavy-light mesons (Q\bar{q}, \bar{Q}q). The resulting effective interaction is defined by overlap integrals of meson wavefunctions and (hq\bar q) coupling, where h is pi, rho, omega, phi, without fitting parameters. Equations for hadro-quarkonium amplitudes and resonance positions are written explicitly, and numerically calculated for the special case of pi Upsilon(nS) (n=1,2,3). Read More

The QCD string breaking due to quark pair creation in the vacuum confining field, possibly accompanied by vector, scalar or Nambu-Goldstone bosons, is studied nonperturbatively. The scalar light pair creation vertex occurs due to chiral symmetry breaking and has a confining form, which is computed explicitly together with subleading vector contributions. Dependence on light quark mass and flavor is specifically studied. Read More

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/\psi and Upsilon disintegration cross sections via the gluon absorption. Read More

A new approach to EW composite scalars is developed, starting from the fundamental gauge interaction on high scale. The latter is assumed to have the group structure $SU(2)_L \times SU(2)_R\times SU(4)$ where SU(4) is the Pati-Salam color-lepton group. The topological EW vacuum filled by instantons is explicitly constructed and the resulting equations for fermion masses exhibit spontaneous SU(2) flavor symmetry violation with possibility of very large mass ratios. Read More

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 $J/\psi$, $\Upsilon$ and $\Omega_{bbb}$ binding energies and melting temperatures in the deconfined phase of the full 2-flavors QCD. Read More

Paramagnetism of gluons is shown to play the basic role in establishing main properties of QCD: IR freezing and asymptotic freedom (AF). Starting with Polyakov background field approach the first terms of background perturbation theory are calculated and shown to ensure not only the classical result of AF but also IR freezing. For the latter only the confining property of the background is needed, and the effective mass entering the IR freezing logarithms is calculated in good agreement with phenomenology and lattice data. Read More

Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Read More

The dynamical mechanism of channel coupling with the decay channels is applied to the case of coupled charmonium - $DD^*$ states with $J^{PC}=1^{++}$. A pole analysis is done and the $DD^*$ production cross section is calculated in qualitative agreement with experiment. The sharp peak at the $D_0D^*_0$ threshold and flat background are shown to be due to Breit-Wigner resonance, shifted by channel coupling from the original position of 3954 MeV for the $2^3P_1$, $Q\bar Q$ state. Read More

New dynamical mechanism of quark mass generations and mixing is demonstrated in the examples of three and four generations. In the framework of the new mixing pattern, called the coherent mixing, the CKM elements are predicted compatible with experimental data for three generations, and are strongly constrained for four generations. Read More

Confinement is explained via field correlators, and the latter are calculated via gluelumps. Behavior of gluelump Green's function at small and large distances yields gluonic condensate and vacuum correlation length respectively and allows to check the consistency of the whole picture. Read More