arXiv subjects

Yu. A. Simonov

Publications and source records attributed to Yu. A. Simonov.

At least 91 records · Page 5Linked to original sources

arXiv2011

Hadron interaction with heavy quarkonia

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). It is also shown, that the recently observed by Belle two peaks Z_b(10610) and Z_b(10650) are in agreement with the proposed theory. It is demonstrated, that theory predicts peaks at the BB*, B*B* thresholds in all available pi Upsilon(nS) channels. Analytic nature of these peaks is investigated, and shown to be due to a common multichannel resonance poles close to the BB*, B*B* thresholds. The general mechanism of these hadro-quarkonium resonances does not assume any molecular or four-quark (tetraquark) dynamics.

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arXiv2011

Pattern of fermion masses from high-scale evolution

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 $m_ν, m_τ, m_t, m_b$ in the third generation. The smallness of neutrino mass, $ν_3\sim 10^{-12} m_{t}$, naturally arises in the solution.

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arXiv2011

Relativistic theory of string breaking in QCD

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. The dominant scalar term is in good agreement with the $^3P_0$ model and experimental data.

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arXiv2011

Gluelumps and Confinement in QCD

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.

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arXiv2011

Heavy quark bound states above deconfinement

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.

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arXiv2011

Binding Energies and Melting Temperatures of Heavy Hadrons in Quark-Gluon Plasma

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.

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arXiv2010

Spontaneous SU(2) symmetry violation in the $SU(2)_L \times SU(2)_R\times SU(4)$ electroweak model

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.

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arXiv2010

Asymptotic freedom and IR freezing in QCD: the role of gluon paramagnetism

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.

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arXiv2010

Dynamical origin and the pole structure of X(3872)

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. A similar analysis, applied to the $n=2$, $^3P_2$, $^1P_1$, $^3P_0$, allows us to associate the first one with the observed $Z(3930)$ J=2 and explains the destiny of $^3P_0$.

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arXiv2010

Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts

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. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partial-wave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of $P$-matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G-matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determine the natural scale of the density for a possible phase transition into the MQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernova models. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.

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arXiv2010

Coherent mixing in three and four quark generations

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.

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arXiv2010

Channel coupling in heavy quarkonia: energy levels, mixing, widths and new states

The mechanism of channel coupling via decay products is used to study energy shifts, level mixing as well as the possibility of new near-threshold resonances in $c\bar c, b\bar b$ systems. The Weinberg eigenvalue method is formulated in the multichannel problems, which allows to describe coupled-channel resonances and wave functions in a unitary way, and to predict new states due to channel coupling. Realistic wave functions for all single-channel states and decay matrix elements computed earlier are exploited, and no new fitting parameters are involved. Examples of level shifts, widths and mixings are presented; the dynamical origin of X(3872) and the destiny of the single-channel $2^3P_1(c\bar c)$ state are clarified. As a result a sharp and narrow peak in the state with quantum numbers $J^{PC}=1^{++}$ is found at 3.872 GeV, while the single-channel resonance originally around 3.940 GeV, becomes increasingly broad and disappears with growing coupling to open channels.

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arXiv2010

J/ψand Upsilon at high temperature

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.

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arXiv2009

On dynamics of fermion generations

The hierarchy of fermion masses and EW symmetry breaking without elementary Higgs is studied on the basis of strong gauge field distributions governing the EW dynamics. The mechanism of symmetry breaking due to quark bilinears condensation is generalized to the case, when higher field correlators are present in the EW vacuum. Resulting wave functional yields several minima of quark bilinears, giving masses of three (or more) generations. Mixing is suggested to be due to kink solutions of the same wave functional. For a special form of this mixing ("coherent mixing") a realistic hierarhy of masses and of CKM coefficients is obtained and arguments in favor of the fourth generation are given. Possible important role of topological charges for CP violating phases and small masses of the first generation is stressed.

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arXiv2009

Diquark and triquark correlations in the deconfined phase of QCD

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.

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arXiv2009

Quarks and baryons in QCD at finite density

The mechanism of string creation for light quarks developed earlier is considered for nonzero quark chemical potential. A strong modification of the confining string due to finite quark density (chemical quark potential $μ$) is observed. As a surprising result in a multiquark system with a common string junction an attractive well appears of radius $μ/σ$ and of an average depth equal to $μ$, which induces formation of multiquark hadrons. Preliminary estimates predict a new phase transition to multiquark hadron phase at rather high densities (in heavy ion collisions or in neutron stars) when neutron matter is compressed to 3-4 normal nuclear densities.

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arXiv2009

Confinement Mechanism in the Field Correlator Method

Confinement in QCD is caused by vacuum fluctuations of gluon fields. There are two numerically different scales, characterizing nonperturbative QCD vacuum dynamics: a "small" scale, corresponding to gluon condensate, critical temperature etc, which is about 0.2-0.3 GeV, and a "large" one, given by inverse confining string width, glueball and gluelump masses etc, which is about 1.5-2.5 GeV. We discuss this mismatch in a picture where confinement is ensured by two-point gauge-invariant field strength correlator of special type. It supports most of perturbative and nonperturbative dynamics, while contribution of other terms is argued to be small. This object, on the other hand, can be expressed via gluelump Green's function, whose dynamics is defined in terms of the same correlator. In this way one obtains a self-consistent scheme of mean-field type leading to permanent confinement at temperatures less than the critical one.

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arXiv2009

Deconfinement and quark-gluon plasma

The theory of confinement and deconfinement is discussed as based on the properties of the QCD vacuum. The latter are described by field correlators of colour-electric and colour-magnetic fields in the vacuum, which can be calculated analytically and on the lattice. As a result one obtains a self-consistent theory of the confined region in the (mu,T) plane with realistic hadron properties. At the boundary of the confining region, the colour-electric confining correlator vanishes, and the remaining correlators describe strong nonperturbative dynamics in the deconfined region with (weakly) bound states. Resulting equation of state for mu=0, p(T), (epsilon-3P)/T are in good agreement with lattice data. Phase transition occurs due to evaporation of a part of the colour-electric gluon condensate, and the resulting critical temperatures T_c(mu) for different n_f are in good correspondence with available data.

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