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Sample records for nonlocal polyakov nambu jona-lasinio model

  1. Reparametrizing the Polyakov$-$Nambu$-$Jona-Lasinio model

    CERN Document Server

    Bhattacharyya, Abhijit; Maity, Soumitra; Raha, Sibaji; Ray, Rajarshi; Saha, Kinkar; Upadhaya, Sudipa

    2016-01-01

    The Polyakov$-$Nambu$-$Jona-Lasinio model has been quite successful in describing various qualitative features of observables for strongly interacting matter, that are measurable in heavy-ion collision experiments. The question still remains on the quantitative uncertainties in the model results. Such an estimation is possible only by contrasting these results with those obtained from first principles using the lattice QCD framework. Recently a variety of lattice QCD data were reported in the realistic continuum limit. Here we make a first attempt at reparametrizing the model so as to reproduce these lattice data. We find excellent quantitative agreement for the equation of state. Certain discrepancies in the charge and strangeness susceptibilities as well as baryon-charge correlation still remain. We discuss their causes and outline possible directions to remove them.

  2. Nonlocal Nambu-Jona-Lasinio model and chiral chemical potential

    CERN Document Server

    Frasca, Marco

    2016-01-01

    We derive the critical temperature in a nonlocal Nambu-Jona-Lasinio model with the presence of a chiral chemical potential. The model we consider uses a form factor derived from recent studies of the gluon propagator in Yang-Mills theory and has the property to fit in excellent way the form factor arising from the instanton liquid picture for the vacuum of the theory. Nambu-Jona-Lasinio model is derived form quantum chromodynamics providing all the constants of the theory without any need for fits. We show that the critical temperature in this case always exists and increases as the square of the chiral chemical potential. The expression we obtain for the critical temperature depends on the mass gap that naturally arises from Yang-Mills theory at low-energy as also confirmed by lattice computations.

  3. Magnetic inverse catalysis in the (2+1)-flavor Nambu--Jona-Lasinio and Polyakov--Nambu--Jona-Lasinio models

    CERN Document Server

    Ferreira, M; Lourenço, O; Frederico, T; Providência, C

    2014-01-01

    The QCD phase diagram at zero chemical potential and finite temperature subject to an external magnetic field is studied within the three flavor Nambu--Jona-Lasinio (NJL) model and the NJL model with the Polyakov loop (PNJL). A scalar coupling parameter dependent on the magnetic field intensity is considered. The scalar coupling has been fitted so that the lattice QCD pseudocritical chiral transition temperatures are reproduced and in the limit of large magnetic field decreases with the inverse of the magnetic field intensity. This dependence of the coupling allows to reproduce the lattice QCD results with respect to the quark condensates and Polyakov loop: due to the magnetic field the quark condensates are enhanced at low and high temperatures and suppressed for temperatures close to the transition temperatures and the Polyakov loop increases with the magnetic field.

  4. Weak magnetic field effects on chiral critical temperature in a nonlocal Nambu--Jona-Lasinio model

    CERN Document Server

    Loewe, M; Villavicencio, C; Zamora, R

    2014-01-01

    In this article we study the nonlocal Nambu--Jona-Lasinio model with a Gaussian regulator in the chiral limit. Finite temperature effects and the presence of a homogeneous magnetic field are considered. The magnetic evolution of the critical temperature for chiral symmetry restoration is then obtained. Here we restrict ourselves to the case of low magnetic field values, being this a complementary discussion to the exisiting analysis in nonlocal models in the strong magnetic field regime.

  5. Vector interaction strength in Polyakov-Nambu-Jona-Lasinio models from hadron-quark phase diagrams

    CERN Document Server

    Lourenço, O; Frederico, T; Delfino, A; Malheiro, M

    2012-01-01

    We estimate the vector interaction strength of the Polyakov-Nambu-Jona-Lasinio (PNJL) parametrizations, assuming that its transition curves should be as close as possible of the recently studied RMF-PNJL hadron-quark phase diagrams. Such diagrams are obtained matching relativistic mean-field hadronic models, and the PNJL quark ones. By using this method we found for the magnitude of the vector interaction, often treated as a free parameter, a range of 7.66 GeV$^{-2}\\lesssim G_V \\lesssim 16.13$ GeV$^{-2}$, or equivalently, $1.52 \\lesssim G_V/G_s \\lesssim 3.2$, with $G_s$ being the scalar coupling constant of the model. These values are compatible but restricts the range of 4 GeV$^{-2}\\lesssim G_V \\lesssim 19$ GeV$^{-2}$, recently obtained from lattice QCD data through a different mean-field model approach.

  6. Probing deconfinement in the Polyakov-loop extended Nambu-Jona-Lasinio model at imaginary chemical potential

    CERN Document Server

    Morita, Kenji; Friman, Bengt; Redlich, Krzysztof

    2011-01-01

    The phase structure of Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model is explored at imaginary chemical potential, with particular emphasis on the deconfinement transition. We point out that the statistical confinement nature of the model naturally leads to characteristic dependence of the chiral condensate $$ on $\\theta=\\mu_I/T$. We introduce a dual parameter for the deconfinement transition by making use of this dependence. By changing a four-fermion coupling constant, we tune the location of the critical endpoint of the deconfinement transition.

  7. Enforced neutrality and color-flavor unlocking in the three-flavor Polyakov-loop Nambu Jona-Lasinio model

    Science.gov (United States)

    Abuki, H.; Ciminale, M.; Gatto, R.; Nardulli, G.; Ruggieri, M.

    2008-04-01

    We study how the charge neutrality affects the phase structure of the three-flavor Polyakov-loop Nambu Jona-Lasinio (PNJL) model. We point out that, within the conventional PNJL model at finite density, the color neutrality is missing because the Wilson line serves as an external colored field coupled to dynamical quarks. In this paper we heuristically assume that the model may still be applicable. To get color neutrality, one has then to allow nonvanishing color chemical potentials. We study how the quark matter phase diagram in (T,ms2/μ)-plane is affected by imposing neutrality and by including the Polyakov-loop dynamics. Although these two effects are correlated in a nonlinear way, the impact of the Polyakov loop turns out to be significant in the T direction, while imposing neutrality brings a remarkable effect in the ms2/μ direction. In particular, we find a novel unlocking transition, when the temperature is increased, even in the chiral SU(3) limit. We clarify how and why this is possible once the dynamics of the colored Polyakov loop is taken into account. Also we succeed in giving an analytic expression for Tc for the transition from two-flavor pairing (2SC) to unpaired quark matter in the presence of the Polyakov loop.

  8. The Nambu Jona-Lasinio model with Wilson fermions

    CERN Document Server

    Rantaharju, Jarno

    2017-01-01

    We present a lattice study of a Nambu Jona-Lasinio (NJL) model using Wilson fermions. Four fermion interactions are a natural part of several extensions of the Standard Model, appearing as a low energy description of a more fundamental theory. In models of dynamical electroweak symmetry breaking they are used to endow the Standard Model fermions with masses. In infrared conformal models these interaction, when sufficiently strong, can alter the dynamics of the fixed point, turning the theory into a (near) conformal model with desirable features for model building. As a first step toward the nonperturbative study of these models, we study the phase space of the ungauged NJL model.

  9. Nonextensive Nambu-Jona-Lasinio Model of QCD matter

    Energy Technology Data Exchange (ETDEWEB)

    Rozynek, Jacek; Wilk, Grzegorz [Department of Fundamental Research, National Centre for Nuclear Research, Warsaw (Poland)

    2016-01-15

    We present a thermodynamical analysis of the nonextensive, QCD-based, Nambu-Jona-Lasinio (NJL) model of strongly interacting matter in the critical region. It is based on the nonextensive generalization of the Boltzmann-Gibbs (BG) statistical mechanics, used in the NJL model, to its nonextensive version. This can be introduced in different ways, depending on different possible choices of the form of the corresponding nonextensive entropies, which are all presented and discussed in detail. Unlike previous attempts, the present approach fulfils the basic requirements of thermodynamical consistency. The corresponding results are compared, discussed and confronted with previous findings. (orig.)

  10. Manifestation of Instabilities in Nambu-Jona-Lasinio type models

    CERN Document Server

    Hashimoto, M

    2006-01-01

    We study a Nambu-Jona-Lasinio (NJL) type model with two-flavor quark matter in $\\beta$-equilibrium. It turns out that the system develops instabilities in the dispersion relations of the diquark fields, i.e., the velocity squared $v^2$ becomes negative in a certain region of the electron chemical potential. The critical point is the same as that of the chromomagnetic instability. The results imply the existence of spatially inhomogeneous diquark condensates in the genuine vacuum. We also discuss the relation between the homogeneous gluon condensates and the inhomogeneous diquark condensates.

  11. Polyakov-Nambu-Jona-Lasinio phase diagrams and quarkyonic phase from order parameters

    CERN Document Server

    Dutra, M; Delfino, A; Frederico, T; Malheiro, M

    2013-01-01

    We show that the magnitude of the order parameters in Polyakov-Nambu-Jona-Lasinio (PNJL) model, given by the quark condensate and the Polyakov loop, can be used as a criterium to clearly identify, without ambiguities, phases and boundaries of the strongly interacting matter, namely, the broken/restored chiral symmetry, and confinement/deconfinement regions. This structure is represented by the projection of the order parameters in the temperature-chemical potential plane, which allows a clear identification of pattern changes in the phase diagram. Such a criterium also enables the emergence of a quarkyonic phase even in the two-flavor system. We still show that this new phase diminishes due to the influence of an additional vector-type interaction in the PNJL phase diagrams, and is quite sensitive to the effect of the change of the $T_0$ parameter in the Polyakov potential. Finally, we show that the phases and boundaries constructed by our method indicate that the order parameters should be more strongly corr...

  12. Finite-volume effects on phase transition in the Polyakov-loop extended Nambu-Jona-Lasinio model with a chiral chemical potential

    CERN Document Server

    Pan, Zan; Chang, Chao-Hsi; Zong, Hong-Shi

    2016-01-01

    To investigate finite-volume effects on the chiral symmetry restoration and the deconfinement transition and some impacts of possible global topological background for a quantum chromodynamics (QCD) system with $N_f=2$ (two quark flavors), we apply the Polyakov-loop extended Nambu-Jona-Lasinio model by introducing a chiral chemical potential $\\mu_5$ artificially. The final numerical results indicate that the introduced chiral chemical potential does not change the critical exponents but shifts the location of critical end point (CEP) significantly; the ratios for the chiral chemical potentials and temperatures at CEP, $\\mu_c/\\mu_{5c}$ and $T_c/T_{5c}$, are significantly affected by the system size $R$. The behavior is that $T_c$ increases slowly with $\\mu_5$ when $R$ is large and $T_c$ decreases first and then increases with $\\mu_5$ when $R$ is small. It is also found that for a fixed $\\mu_5$, there is a $R_{\\text{min}}$, where the critical end point vanishes, and the whole phase diagram becomes a crossover w...

  13. Nonextensive critical effects in the Nambu--Jona-Lasinio model

    CERN Document Server

    Rozynek, Jacek

    2009-01-01

    The critical phenomena in strongly interaction matter are generally investigated using the mean-field model and are characterized by well defined critical exponents. However, such models provide only average properties of the corresponding order parameters and neglect altogether their possible fluctuations. Also the possible long range effect are neglected in the mean field approach. Here we investigate the critical behavior in the nonextensive version of the Nambu Jona-Lasinio model (NJL). It allows to account for such effects in a phenomenological way by means of a single parameter $q$, the nonextensivity parameter. In particular, we show how the nonextensive statistics influence the region of the critical temperature and chemical potential in the NJL mean field approach.

  14. Octet Magnetic Moments with Null Instantons and Semibosonized Nambu-Jona-Lasinio Model

    CERN Document Server

    Bukina, E N

    1999-01-01

    It is shown that the difference between the magnetic moment results in the quark model with null instantons and semibosonized Nambu-Jona-Lasinio model lies in the description of the magnetic moment of the $ \\Lambda$-hyperon.

  15. Gluon fragmentation functions in the Nambu-Jona-Lasinio model

    CERN Document Server

    Yang, Dong-Jing

    2016-01-01

    We derive gluon fragmentation functions in the Nambu-Jona-Lasinio (NJL) model by treating a gluon as a pair of color lines formed by fictitious quark and anti-quark ($q\\bar q$). Gluon elementary fragmentation functions are obtained from the quark and anti-quark elementary fragmentation functions for emitting specific mesons in the NJL model under the requirement that the $q\\bar q$ pair maintains in the flavor-singlet state after meson emissions. An integral equation, which iterates the gluon elementary fragmentation functions to all orders, is then solved to yield the gluon fragmentation functions at a model scale. It is observed that these solutions are stable with respect to variation of relevant model parameters, especially after QCD evolution to a higher scale is implemented. We show that the inclusion of the gluon fragmentation functions into the theoretical predictions from only the quark fragmentation functions greatly improves the agreement with the SLD data for the pion and kaon productions in $e^+e^...

  16. Phase structure, critical points and susceptibilities in Nambu-Jona-Lasinio type models

    CERN Document Server

    De Sousa, C A; Ruivo, M C

    2008-01-01

    We investigate the chiral phase transition at finite temperature and chemical potential within SU(2) and SU(3) Nambu-Jona-Lasinio type models. The behavior of the baryon number susceptibility and the specific heat, in the vicinity of the critical end point, is studied. The class of the critical points is analyzed by calculating critical exponents.

  17. Chiral phase transition in the SU (3) Nambu and Jona-Lasinio model

    Energy Technology Data Exchange (ETDEWEB)

    Klimt, S.; Lutz, M.; Weise, W. (Regensburg Univ. (Germany, F.R.). Inst. fuer Physik 1 - Theoretische Physik)

    1990-10-25

    We calculate the thermodynamical potential of the SU(3) Nambu and Jona-Lasinio model in the mean field approximation and discuss the nature of the chiral phase transition, i.e. the mechanisms which govern chiral symmetry restoration at large temperature and/or quark densities. No evidence is found for a first order transition once realistic coupling strengths are used in the model. (orig.).

  18. Soap bubble hadronic states in a QCD-motivated Nambu-Jona-Lasinio model

    CERN Document Server

    Kutnii, Sergii

    2015-01-01

    Inhomogeneous solutions of the gap equation in the mean field approach to Nambu-Jona-Lasinio model are studied. An approximate Ginzburg-Landau-like gap equation is obtained and the domain wall solution is found. Binding of fermions to the domain wall is demonstrated. Compact domain wall with bound fermions is studied and stabilisation by fermion pressure is demonstrated which opens a possibility for existence of "soap bubble" hadronic states.

  19. Inverse Magnetic Catalysis in Nambu--Jona-Lasinio Model beyond Mean Field

    CERN Document Server

    Mao, Shijun

    2016-01-01

    We study inverse magnetic catalysis in the Nambu--Jona-Lasinio model beyond mean field approximation. The feed-down from mesons to quarks is embedded in an effective coupling constant at finite temperature and magnetic field. While the magnetic catalysis is still the dominant effect at low temperature, the meson dressed quark mass drops down with increasing magnetic field at high temperature due to the dimension reduction of the Goldstone mode in the Pauli-Villars regularization scheme.

  20. Relation Between Chiral Susceptibility and Solutions of Gap Equation in Nambu--Jona-Lasinio Model

    CERN Document Server

    Zhao, Y; Liu, Y; Yuan, W; Chang, Lei; Liu, Yu-xin; Yuan, Wei; Zhao, Yue

    2006-01-01

    We study the solutions of the gap equation, the thermodynamic potential and the chiral susceptibility in and beyond the chiral limit at finite chemical potential in the Nambu--Jona-Lasinio (NJL) model. We give an explicit relation between the chiral susceptibility and the thermodynamic potential in the NJL model. We find that the chiral susceptibility is a quantity being able to represent the furcation of the solutions of the gap equation and the concavo-convexity of the thermodynamic potential in NJL model. It indicates that the chiral susceptibility can identify the stable state and the possibility of the chiral phase transition in NJL model.

  1. Regularization dependence on phase diagram in Nambu-Jona-Lasinio model

    CERN Document Server

    Inagaki, T; Kohyama, H

    2015-01-01

    We study the regularization dependence on meson properties and the phase diagram of quark matter by using the two flavor Nambu-Jona-Lasinio model. We find that the meson properties and the phase structure do not show drastically difference depending the regularization procedures. We also find that the location or the existence of the critical end point highly depends on the regularization methods and the model parameters. Then we think that regularization and parameters are carefully considered when one investigates the QCD critical end point in the effective model studies.

  2. The Pion-Photon Transition Distribution Amplitudes in the Nambu-Jona Lasinio Model

    CERN Document Server

    Courtoy, A

    2007-01-01

    We define the pion-photon Transition Distribution Amplitudes (TDA) in a field theoretic formalism from a covariant Bethe-Salpeter approach for the determination of the bound state. We apply our formalism to the Nambu - Jona Lasinio model, as a realistic theory of the pion. The obtained vector and axial TDAs satisfy all features required by general considerations. In particular, sum rules and polynomiality condition are explicitly verified. We have numerically proved that the odd coefficients in the polynomiality expansion of the vector TDA vanish in the chiral limit. The role of PCAC and the presence of a pion pole are explicitly showed.

  3. Spin polarization and color superconductivity in the Nambu-Jona-Lasinio model at finite temperature

    CERN Document Server

    Matsuoka, Hiroaki; da Providencia, Joao; Providencia, Constancia; Yamamura, Masatoshi

    2016-01-01

    We investigate the possible existence of spin polarization and color superconductivity in the Nambu-Jona-Lasinio model with a tensor-type interaction at finite density and temperature. The thermodynamic potential is calculated by the functional integral method. Numerical results indicate that at low temperature and quark chemical potential the chiral condensed phase exists, and at intermediate chemical potential the color superconducting phase appears. In addition, depending on the magnitude of the tensor coupling, at large chemical potential and low temperature, a color superconducting phase and a spin polarized phase may coexist while at intermediate temperatures only the spin polarized phase occurs.

  4. Quark matter under strong magnetic fields in the Nambu--Jona-Lasinio Model

    CERN Document Server

    Peres-Menezes, D; Avancini, S S; Martinez, A Perez; Providência, C

    2008-01-01

    In the present work we use the large-$N_c$ approximation to investigate quark matter described by the SU(2) Nambu--Jona-Lasinio model subject to a strong magnetic field. The Landau levels are filled in such a way that usual kinks appear in the effective mass and other related quantities. $\\beta$-equilibrium is also considered and the macroscopic properties of a magnetar described by this quark matter is obtained. Our study shows that the magnetar masses and radii are larger if the magnetic field increases but only very large fields ($\\ge 10^{18}$ G) affect the EoS in a non negligible way.

  5. Structure of hybrid protoneutron stars within the Nambu--Jona-Lasinio model

    CERN Document Server

    Burgio, G F

    2007-01-01

    We investigate the structure of protoneutron stars (PNS) formed by hadronic and quark matter in $\\beta$-equilibrium described by appropriate equations of state (EOS). For the hadronic matter, we use a finite temperature EOS based on the Brueckner-Bethe-Goldstone many-body theory, with realistic two- and three-body forces. For the quark sector, we employ the Nambu--Jona-Lasinio model. We find that the maximum allowed masses are comprised in a narrow range around 1.8 solar masses, with a slight dependence on the temperature. Metastable hybrid protoneutron stars are not found.

  6. Generalized SU(3) Nambu-Jona-Lasinio model. Pt. 1; Mesonic modes

    Energy Technology Data Exchange (ETDEWEB)

    Klimt, S.; Lutz, M.; Vogl, U.; Weise, W. (Regensburg Univ. (Germany, F.R.). Inst. fuer Physik 1 - Theoretische Physik)

    1990-10-08

    We present calculations of mesonic (quark-antiquark) modes in a generalized Nambu-Jona-Lasinio model with three quark flavours. The effective interaction between quarks is symmetric under chiral SU(3){sub L}xSU(3){sub R} and incorporates a U(1){sub A}-breaking six-point interaction as suggested by 't Hooft. We coencentrate on the evaluation of masses and decay constants of pseudoscalar mesons, with special emphasis on the underlying symmetry breaking patterns. Scalar, vector and axial vector mesonic modes are also discussed. (orig.).

  7. The decay τ → K0K-ντ in the extended Nambu-Jona-Lasinio model

    Science.gov (United States)

    Volkov, M. K.; Pivovarov, A. A.

    2016-07-01

    The full and differential widths of the decay τ → K0K-ν τ are calculated in the framework of the extended Nambu-Jona-Lasinio model.The contributions of the subprocesses with the intermediate vector mesons ρ(770) and ρ(1450) are taken into account. The obtained results are in satisfactory agreement with the experimental data.

  8. Generalized Nambu-Jona-Lasinio model in flavour SU(3): Development and application. Verallgemeinertes Nambu-Jona-Lasinio-Modell in Flavour-SU(3): Entwicklung und Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Klimt, S.

    1989-12-19

    In this thesis the author tried to decribe important low-energy phenomena of the strong interactions by means of the Nambu-Jona-Lasinio model. The effective quark-quark interaction was thereby constructed in accordance with the basing symmetries and conserved currents of the QCD; the model possesses especially chiral SU(3){sub L} x SU(3){sub R} symmetry. In the framework of this approach properties of the quarks and the light mesons were studied. In the calculations for instance the Hartree-Fock approach for the quark propagator was used. Properties of the mesons were determined in the framework of a RPA calculation by solution of the Bethe-Salpeter equation for the quark-antiquark scattering matrix. All questions, which were treated here, concern aspects of the symmetry breaking of the QCD: At the one hand the explicit breaking of the chiral symmetry by finite, if also small quark current masses. Thereby was assumed that these can be described as low perturbation of the chiral limit of massless quarks; furthermore the breaking of the U(1){sub A} symmetry observed in nature. It was tried to regard this anomaly property of the QCD by an additional flavor-mixing and U(1){sub A} breaking determinant interaction. The last and most important point finally is the spontaneous breaking of the chiral symmetry and the generation of quark condensates in the QCD ground state by the interaction dynamics. (orig./HSI).

  9. Inflation from the Finite Scale Gauged Nambu-Jona-Lasinio Model

    CERN Document Server

    Inagaki, Tomohiro; Sakamoto, Hiroki

    2016-01-01

    The possibility to construct an inflationary universe scenario for the finite-scale gauged Nambu-Jona-Lasinio model is investigated. This model can be described by the Higgs-Yukawa type interaction model with the corresponding compositeness scale. Therefore, the one-loop Higgs-Yukawa effective potential is used with the compositeness condition for the study of inflationary dynamics. We evaluate the fluctuations in the cosmic microwave background for the model with a finite compositeness scale in the slow-roll approximation. We find the remarkable dependence on the gauge group and the number of fermion flavors. It is also proved that the model has similar behavior with the $\\phi^{4n}$ chaotic inflation and the Starobinsky model at the flat and steep limits, respectively. It is demonstrated that realistic inflation consistent with Planck data is possible for a range of theory parameters.

  10. Thermo-magnetic effects in quark matter: Nambu-Jona-Lasinio model constrained by lattice QCD

    CERN Document Server

    Farias, R L S; Avancini, S S; Pinto, M B; Krein, G

    2016-01-01

    The phenomenon of inverse magnetic catalysis of chiral symmetry in QCD predicted by lattice simulations can be reproduced within the Nambu-Jona-Lasinio model if the coupling G of the model decreases with the strength B of the magnetic field and temperature T. The thermo-magnetic dependence of G(B,T) is obtained by fitting recent lattice QCD predictions for the chiral transition order parameter. Different thermodynamic quantities of magnetized quark matter evaluated with a G(B, T) are compared with the ones obtained at constant coupling G. The model with a G(B,T) predicts a more dramatic chiral transition as the field intensity increases. In addition, the pressure and magnetization always increase with B for a given temperature. Being parametrized by four magnetic field dependent coefficients and having a rather simple exponential thermal dependence our accurate ansatz for the running coupling can be easily implemented to improve typical model applications to magnetized quark matter.

  11. Thermo-magnetic effects in quark matter: Nambu-Jona-Lasinio model constrained by lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Farias, Ricardo L.S. [Universidade Federal de Santa Maria, Departamento de Fisica, Santa Maria, RS (Brazil); Kent State University, Physics Department, Kent, OH (United States); Timoteo, Varese S. [Universidade Estadual de Campinas (UNICAMP), Grupo de Optica e Modelagem Numerica (GOMNI), Faculdade de Tecnologia, Limeira, SP (Brazil); Avancini, Sidney S.; Pinto, Marcus B. [Universidade Federal de Santa Catarina, Departamento de Fisica, Florianopolis, Santa Catarina (Brazil); Krein, Gastao [Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil)

    2017-05-15

    The phenomenon of inverse magnetic catalysis of chiral symmetry in QCD predicted by lattice simulations can be reproduced within the Nambu-Jona-Lasinio model if the coupling G of the model decreases with the strength B of the magnetic field and temperature T. The thermo-magnetic dependence of G(B, T) is obtained by fitting recent lattice QCD predictions for the chiral transition order parameter. Different thermodynamic quantities of magnetized quark matter evaluated with G(B, T) are compared with the ones obtained at constant coupling, G. The model with G(B, T) predicts a more dramatic chiral transition as the field intensity increases. In addition, the pressure and magnetization always increase with B for a given temperature. Being parametrized by four magnetic-field-dependent coefficients and having a rather simple exponential thermal dependence our accurate ansatz for the coupling constant can be easily implemented to improve typical model applications to magnetized quark matter. (orig.)

  12. Analysis on a Nambu--Jona-Lasinio Model of Dynamical Supersymmetry Breaking

    CERN Document Server

    Cheng, Yifan; Faisel, Gaber; Kong, Otto C W

    2016-01-01

    This is a report on our newly proposed model of dynamical supersymmetry breaking with some details of the analysis involved. The model in the simplest version has only a chiral superfield (multiplet), with a strong four-superfield interaction in the K\\"ahler potential that induces a real two-superfield composite with vacuum condensate. The latter has supersymmetry breaking parts, which we show to bear nontrivial solution following basically a standard nonperturbative analysis for a Nambu--Jona-Lasinio type model on a superfield setting. The real composite superfield has a spin one component but is otherwise quite unconventional. We discuss also the parallel analysis for the effective theory with the composite. Plausible vacuum solutions are illustrated and analyzed. The supersymmetry breaking solutions have generated soft mass(es) for the scalar avoiding the vanishing supertrace condition for the squared-masses of the superfield components. We also present some analysis of the resulted low energy effective th...

  13. Nonuniform phases in the 't Hooft extended Nambu--Jona-Lasinio Model

    CERN Document Server

    Moreira, J; Osipov, A A; Blin, A H

    2015-01-01

    The phase diagram of cold dense quark matter is studied using the 't Hooft extended Nambu--Jona-Lasinio Model applied to the light quark sector with a finite current mass for the strange quark (up and down are considered in the chiral limit). By relaxing the traditional uniformity assumptions and considering a modulated light quark condensate background we investigate the possible existence of non-uniform phases in this region of the phase diagram. The effects of changes in the coupling strengths of the model are studied and it is shown that the inclusion of flavour mixing combined with the finite current mass of the strange quark catalyses the appearance of the non-uniform phases, extending the domain for their existence.

  14. Thermodynamics and critical behavior in the Nambu-Jona-Lasinio model of QCD

    CERN Document Server

    Costa, Pedro; De Sousa, C A

    2008-01-01

    We investigate the phase diagram of strongly interacting matter as a function of temperature and baryonic density/chemical potential, within Nambu-Jona-Lasinio type models. We perform a systematic study concerning the existence, location and properties of a critical end point/tricritical point, both in SU(2) and SU(3) versions of the model. We verify that, for $m_u=m_d=0$ and up to a critical strange quark mass, there is a tricritical point, which becomes a critical end point in a world with realistic values of the current quark masses. The critical properties of physical observables as the baryon number susceptibility and the specific heat are analyzed in the vicinity of the critical end point, with special focus on their critical exponents. The behavior of mesons in the $T-\\mu_B(\\rho_B)$ plane is analyzed in connection with possible signatures of partial and effective restoration of chiral symmetry.

  15. Topological susceptibility at zero and finite temperature in the Nambu-Jona-Lasinio model

    CERN Document Server

    Ohnishi, K; Ohta, K

    2001-01-01

    We consider the three flavor Nambu-Jona-Lasinio model with the 't Hooft interaction incorporating the U(1)_A anomaly. In order to set the coupling strength of the 't Hooft term, we employ the topological susceptibility $\\chi$ instead of the eta' meson mass. The value for $\\chi$ is taken from lattice simulations. We also calculate $\\chi$ at finite temperature within the model. Comparing it with the lattice data, we extract information about the behavior of the U(1)_A anomaly at finite temperature. We conclude that within the present framework, the effective restoration of the U(1)_A symmetry does not necessarily take place even at high temperature where the chiral symmetry is restored.

  16. Thermo-magnetic properties of the strong coupling in the local Nambu--Jona-Lasinio model

    CERN Document Server

    Ayala, Alejandro; Hernandez, L A; Loewe, M; Raya, Alfredo; Rojas, J C; Villavicencio, C

    2016-01-01

    We study the thermo-magnetic behavior of the strong coupling constant and quark mass entering the Nambu-Jona-Lasinio model. The behavior of the quark condensate as function of magnetic field strength and temperature is also obtained and confronted with lattice QCD results. We find that for temperatures above the chiral/deconfinement phase transitions, where the condensate decreases monotonically with increasing field, the coupling also decreases monotonically. For temperatures below the transition temperature we find that the coupling initially grows and then decreases with increasing field strength. We consider this turnover behavior as a key element in the behavior of the quark condensate above the transition temperature. Hence, it allows for an understanding of the inverse magnetic catalysis phenomenon.

  17. Screening of the meson fields in the Nambu - Jona-Lasinio model

    Energy Technology Data Exchange (ETDEWEB)

    Florkowski, W. [Institute of Nuclear Physics, Cracow (Poland)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Friman, B.L. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik

    1993-03-01

    The spatial dependence of the finite-temperature meson correlation function in the (pseudo)scalar channel is studied in the Nambu-Jona-Lasinio model. The screening masses, obtained from the asymptotic behaviour of the static correlation function, are found to differ substantially from the dynamic masses, defined by a pole of the meson propagator. In particular, at high temperatures, the meson screening masses are large, although there are no well defined meson modes. In the high-temperature limit, the screening masses approach 2{pi}T, which corresponds to a gas of non-interacting, massless quarks. However interaction effects remain well beyond the chiral transition temperatures. The overall temperature dependence of the screening masses is in agreement with lattice results. (author). 26 refs, 5 figs.

  18. Non-uniform phases in a three-flavour 't Hooft extended Nambu-Jona--Lasinio model

    CERN Document Server

    Moreira, J; Broniowski, W; Osipov, A A; Blin, A H

    2014-01-01

    The possible existence of non-uniform phases in cold dense quark matter in the light quark sector ($u$, $d$ and $s$) is addressed using the Nambu-Jona--Lasinio Model extended to include flavour-mixing 't Hooft determinant. The effect of changes in the coupling strengths of the model is discussed. It is seen that the inclusion of the strange sector catalyses the appearance of these non-uniform phases extending the domain for their appearance.

  19. A unified composite model of inflation and dark matter in the Nambu-Jona-Lasinio theory

    CERN Document Server

    Channuie, Phongpichit

    2016-01-01

    In this work, we propose a cosmological scenario inherently based on the effective Nambu-Jona-Lasinio (NJL) model that comic inflation and dark matter can be successfully described by a single framework. On the one hand, the scalar channel of the NJL model plays a role of the composite inflaton (CI) and we show that it is viable to achieve successful inflation via a non-minimal coupling to gravity. For model of inflation, we compute the inflationary parameters and confront them with recent Planck 2015 data. We discover that the predictions of the model are in excellent agreement with the Planck analysis. We also present in our model a simple connection of physics from the high scales to low scales via renormalization group equations of the physical parameters. On the other hand, the pseudoscalar channel can be assigned as a candidate for composite dark matter (CD). For model of dark matter, we couple the pseudoscalar to the Higgs sector of the standard model with the coupling strength $\\kappa$ and estimate it...

  20. The Problem of Matter Stability in the Nambu-Jona-Lasinio Model

    CERN Document Server

    Buballa, M

    1996-01-01

    We reinvestigate the conditions for stable matter solutions in the Nambu--Jona-Lasinio (NJL) model. In mean field approximation the NJL model can be regarded as an extension of the Walecka mean field model to include negative energy fermion states. While this extension is necessary to allow for a chiral phase transition, it was found some time ago that at the same time it destroys the wanted saturation properties of the Walecka model. We reformulate this problem in terms of the thermodynamic potential and find that there is indeed a connection between these two features. We show that the minimum of the thermodynamic potential which corresponds to stable nuclear matter in the Walecka model is shifted from a finite to zero effective fermion mass in the chiral NJL model. This shift is closely related to the chiral phase transition. Under certain conditions the shifted minima may still lead to stable matter solutions but only in the chirally restored phase. We discuss a possible interpretation of these solutions ...

  1. Generalized SU(3) Nambu-Jona-Lasinio model. Pt. 2; From current to constituent quarks

    Energy Technology Data Exchange (ETDEWEB)

    Vogl, U.; Lutz, M.; Klimt, S.; Weise, W. (Regensburg Univ. (Germany, F.R.). Inst. fuer Physik 1 - Theoretische Physik)

    1990-10-08

    We investigate the properties of constituent quarks, i.e. quarks dressed by their strong interactions, in a generalized Nambu-Jona-Lasinio model with N{sub f}=3 flavours. In the Hartree-Fock approximation, the step from structureless current quarks to massive constituent quarks is made through dynamical mass generation which implies spontaneous chiral symmetry breaking. We study, in particular, the quark scalar, vector and axial vector currents within this framework. We demonstrate that, a low energy and momentum transfers, single valence quarks are strongly screened by quark-antiquark polarization effects. For the electromagnetic currents, we recover relationships familiar from the vector meson dominance model. For the axial current, screening by J{sup {pi}}=1{sup +} quark-antiquark modes leads to an effective quark axial vector constant g{sub A}<1 which satisfies the Goldberger-Treiman relation at the quark level. The spin content of the proton is also discussed in this framework. We calculate quark magnetic moments and electromagnetic form factors and discuss their related sizes. (orig.).

  2. Thermomagnetic correlation lengths of strongly interacting matter in the Nambu-Jona-Lasinio model

    Science.gov (United States)

    Ayala, Alejandro; Hernández, L. A.; Loewe, M.; Raya, Alfredo; Rojas, J. C.; Zamora, R.

    2017-08-01

    We study the correlation length between test quarks with the same electric and color charges in the Nambu-Jona-Lasinio model, considering thermal and magnetic effects. We extract the correlation length from the quark correlation function. The latter is constructed from the probability amplitude to bring a given quark into the plasma once a previous one with the same quantum numbers is placed at a given distance apart. For temperatures below the transition temperature, the correlation length starts growing as the field strength increases to then decrease for large magnetic fields. For temperatures above the pseudocritical temperature, the correlation length continues increasing as the field strength increases. We found that such behavior can be understood as a competition between the tightening induced by the classical magnetic force versus the random thermal motion. For large enough temperatures, the increase of the occupation number contributes to the screening of the interaction between the test particles. The growth of the correlation distance with the magnetic field can be understood as due to the closer proximity between one of the test quarks and the ones popped up from the vacuum, which in turn appear due to the increase of the occupation number with the temperature.

  3. Light-front Nambu--Jona-Lasinio model at finite temperature and density

    CERN Document Server

    Strauss, S; Beyer, M

    2009-01-01

    In recent years light-front quantisation has been extended to allow for a consistent treatment of systems at finite temperature and density. This is in particular interesting for an investigation of the processes in nuclear matter under extreme condition as occurring, e.g., during a heavy ion collision. Utilising a Dyson expansion to the N-point Green functions at finite temperature and density we focus on the occurrence of pionic and scalar diquark dynamics in quark matter and compute the masses and the Mott dissociation using a separable t-matrix approach. For the scalar quark-quark correlation we determine the critical temperature of colour superconductivity using the Thouless criterion. On the same footing the properties of the nucleon in a medium of quark matter are computed within a Faddeev approach. Critical lines for nucleon breakup are given. Presently, we use a light-front Nambu--Jona-Lasinio model that allows us to compare these results of this novel approach to the more traditional instant form ap...

  4. Unified composite scenario for inflation and dark matter in the Nambu-Jona-Lasinio model

    Science.gov (United States)

    Channuie, Phongpichit; Xiong, Chi

    2017-02-01

    In this work, we propose a cosmological scenario inherently based on the effective Nambu-Jona-Lasinio (NJL) model that cosmic inflation and dark matter can be successfully described by a single framework. On the one hand, the scalar channel of the NJL model plays a role of the composite inflaton (CI) and we show that it is viable to achieve successful inflation via a nonminimal coupling to gravity. For model of inflation, we compute the inflationary parameters and confront them with recent Planck 2015 data. We discover that the predictions of the model are in excellent agreement with the Planck analysis. We also present in our model a simple connection of physics from the high scales to low scales via renormalization group equations (RGEs) of the physical parameters and use them to estimate the range of relevant parameters. On the other hand, the pseudoscalar channel can be assigned as a candidate for composite dark matter (CD). For a model of dark matter, we couple the pseudoscalar to the Higgs sector of the standard model with the coupling strength κ and estimate its thermally averaged relic abundance. We discover that the CD mass is strongly sensitive to the coupling κ . We find in case of light CD, Msvalue of its mass Ms˜61 GeV for κ =0.1 . However, in this case the CD mass can be lighter when the coupling is getting larger. Moreover, in case of heavy CD, Ms>MW ,Z (or >Mh), the required relic abundance can be satisfied for value of the CD mass Ms˜410 GeV for κ =0.5 . In contradiction to the light mass case, however, the CD mass in this case can even be heavier when the coupling is getting larger.

  5. Bosonization of the generalized SU(3) Nambu-Jona-Lasinio model in the 1/N expansion; Bosonizacao do modelo de Nambu-Jona-Lasinio SU(3) generalizado na expansao 1/N

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Francisco Antonio Pena

    1995-12-31

    The present work consists in a 1/N expansion of extended version of the SU(3) Nambu-Jona-Lasinio model in the context of the Functional Integral. The gap equations, meson propagators, triangle diagram, etc, appear quite naturally as different orders in the expansion. The new features of this approach is the inclusion of high order corrections in the 1/N leading orders, which have never included in the previous one. The method also allows for the construction of a chiral Lagrangian of interacting mesons based on the SU(3) NJL model, here obtained for the first time. (author) 32 refs., 11 figs., 5 tabs.

  6. Solving the U(2)L X U(2)R symmetric Nambu--Jona-Lasinio model in 1+1 dimensions

    CERN Document Server

    Thies, Michael

    2016-01-01

    A less well known variant of the Nambu--Jona-Lasinio model with Nc colors and U(2)L X U(2)R chiral symmetry is studied in 1+1 dimensions. Using semi-classical methods appropriate for the large Nc limit, we determine the vacuum manifold, the meson spectrum, massless and massive multi-fermion bound states and the phase diagram as a function of temperature, chemical potential and isospin chemical potential. An important tool to understand soliton dynamics is the generalization of the time-dependent Hartree-Fock approach to two flavors along the lines recently developed by Takahashi in the context of unconventional fermionic superfluids and superconductors.

  7. Neutron stars: from the inner crust to the core with the (Extended) Nambu-Jona-Lasinio model

    CERN Document Server

    Pais, Helena; Providência, Constança

    2016-01-01

    We use an su(2) version of the extended Nambu-Jona-Lasinio model to describe nucleonic matter and the usual su(3) version of the NJL model with vector interaction to describe quark matter. We calculate the nuclear pasta phases that appear in the inner crust of neutron stars within the su(2) extended Nambu-Jona-Lasinio model with different parametrizations. We consider two methods for the non-homogeneous phases: the coexistence-phases approximation and the compressible liquid drop model, and we calculate the surface tension coefficient using a geometrical approach at zero temperature. The energy density and pressure are determined in the region of densities and proton fractions where the pasta shapes are expected to appear. The equation of state of stellar matter is calculated, and the mass-radius relation for several families of hadronic and hybrid stars determined. The quark phase of hybrid stars is described within the su(3) NJL model including a vector term. Masses above 2$M_{\\odot}$ have been obtained for...

  8. Shear and Bulk Viscosities of Quark Matter from Quark-Meson Fluctuations in the Nambu--Jona-Lasinio model

    CERN Document Server

    Ghosh, Sabyasachi; Roy, Victor; Serna, Fernando E; Krein, Gastão

    2015-01-01

    We have calculated the temperature dependence of shear $\\eta$ and bulk $\\zeta$ viscosities of quark matter due to quark-meson fluctuations. The quark thermal width originating from quantum fluctuations of quark-$\\pi$ and quark-$\\sigma$ loops at finite temperature is calculated with the formalism of real-time thermal field theory. Temperature-dependent constituent-quark and meson masses, and quark-meson couplings are obtained in the Nambu--Jona-Lasinio model. We found a non-trivial influence of the temperature-dependent masses and couplings on the Landau-cut structure of the quark self-energy. Our results for the ratios $\\eta/s$ and $\\zeta/s$, where $s$ is the entropy density (also determined in the Nambu--Jona-Lasinio model in the quasi-particle approximation), are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for $\\eta/s$ has a minimum very close to the conjectured AdS/CFT lower bound, $\\eta/s = 1/4\\pi$.

  9. Shear and bulk viscosities of quark matter from quark-meson fluctuations in the Nambu-Jona-Lasinio model

    Science.gov (United States)

    Ghosh, Sabyasachi; Peixoto, Thiago C.; Roy, Victor; Serna, Fernando E.; Krein, Gastão

    2016-04-01

    We have calculated the temperature dependence of shear η and bulk ζ viscosities of quark matter due to quark-meson fluctuations. The quark thermal width originating from quantum fluctuations of quark-π and quark-σ loops at finite temperature is calculated with the formalism of real-time thermal field theory. Temperature-dependent constituent-quark and meson masses and quark-meson couplings are obtained in the Nambu-Jona-Lasinio model. We found a nontrivial influence of the temperature-dependent masses and couplings on the Landau-cut structure of the quark self-energy. Our results for the ratios η /s and ζ /s , where s is the entropy density (also determined in the Nambu-Jona-Lasinio model in the quasiparticle approximation), are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for η /s has a minimum very close to the quantum lower bound, η /s =1 /4 π .

  10. Quasiparticle properties of the quarks of the Nambu-Jona-Lasinio model

    Science.gov (United States)

    Cao, Nan-Wei; Shakin, C. M.; Sun, Wei-Dong

    1992-12-01

    In spite of the apparent limitations of the model, in recent years there have been many applications of the Nambu-Jona-Lasinio (NJL) model in the study of hadron structure and in the study of the behavior of nuclear matter at finite temperature and density. A number of researchers have studied a generalized SU(3) version of the NJL model. For example, Vogl, Lutz, Klimt, and Weise [Nucl. Phys. A516 469 (1990)] have performed extensive calculations that include a calculation of a scalar form factor of a constituent quark, Fs(q2), and a calculation of a quark sigma term σq. (In their work, the latter quantity is related to the nucleon sigma term σN as in a constituent quark model: σN=3σq.) These calculations are made in what may be termed a sigma-dominance approximation. In the work reported here, we review the important role played by the nucleon sigma term in understanding the behavior of the quark condensate in the presence of matter. We make use of the original SU(2) version of the NJL model to study how various quark properties are modified when we take into account the dressing of the constituent quarks by the pion, the Goldstone boson of the model. We calculate the quark self-energy arising from emission and absorption of a pion and also show how the calculation of the scalar form factor of the quark and σq are modified due to the coupling of the quark to the pion. The correction terms considered here serve to reduce the value of σq by a small amount relative to the value obtained in the simplest version of the sigma dominance model. For example, for a Euclidean momentum cutoff, Λ=1050 MeV, the uncorrected result is σN=54.6 MeV. That value is then reduced to σN=51.5 MeV, if the corrections due to the pion ``dressing'' are included. It is also found that the residue at the quasiparticle pole of the quark propagator Z is about 0.86 when the coupling to the pion field is taken into account.

  11. Quasiparticle properties of the quarks of the Nambu--Jona-Lasinio model

    Energy Technology Data Exchange (ETDEWEB)

    Cao, N.; Shakin, C.M.; Sun, W. (Department of Physics and Center for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States))

    1992-12-01

    In spite of the apparent limitations of the model, in recent years there have been many applications of the Nambu--Jona-Lasinio (NJL) model in the study of hadron structure and in the study of the behavior of nuclear matter at finite temperature and density. A number of researchers have studied a generalized SU(3) version of the NJL model. For example, Vogl, Lutz, Klimt, and Weise (Nucl. Phys. A516 469 (1990)) have performed extensive calculations that include a calculation of a scalar form factor of a constituent quark, {ital F}{sub {ital s}}({ital q}{sup 2}), and a calculation of a quark sigma term {sigma}{sub {ital q}}. (In their work, the latter quantity is related to the nucleon sigma term {sigma}{sub {ital N}} as in a constituent quark model: {sigma}{sub {ital N}}=3{sigma}{sub {ital q}}.) These calculations are made in what may be termed a sigma-dominance approximation. In the work reported here, we review the important role played by the nucleon sigma term in understanding the behavior of the quark condensate in the presence of matter. We make use of the original SU(2) version of the NJL model to study how various quark properties are modified when we take into account the dressing of the constituent quarks by the pion, the Goldstone boson of the model. We calculate the quark self-energy arising from emission and absorption of a pion and also show how the calculation of the scalar form factor of the quark and {sigma}{sub {ital q}} are modified due to the coupling of the quark to the pion. The correction terms considered here serve to reduce the value of {sigma}{sub {ital q}} by a small amount relative to the value obtained in the simplest version of the sigma dominance model. For example, for a Euclidean momentum cutoff, {Lambda}=1050 MeV, the uncorrected result is {sigma}{sub {ital N}}=54.6 MeV.

  12. Two-solar-mass hybrid stars: a two model description with the Nambu-Jona-Lasinio quark model

    CERN Document Server

    Pereira, Renan Câmara; Providência, Constança

    2016-01-01

    Hybrid stars with a quark phase described by the Nambu$-$Jona-Lasinio model are studied. The hadron-quark model used to determine the stellar matter equation of state favors the appearance of quark matter: the coincidence of the deconfinement and chiral transitions and a low vacuum constituent quark mass. These two properties are essential to build equations of state that predict pure quark matter in the center of neutron stars. The effect of vector-isoscalar and vector-isovector terms is discussed, and it is shown that the vector-isoscalar terms are necessary to describe 2$M_\\odot$ hybrid stars, and the vector-isovector terms result in larger quark cores and a smaller deconfinement density.

  13. Neutron stars: From the inner crust to the core with the (extended) Nambu-Jona-Lasinio model

    Science.gov (United States)

    Pais, Helena; Menezes, Débora P.; Providência, Constança

    2016-06-01

    Nucleonic matter is described within an SU(2) extended Nambu-Jona-Lasinio (NJL) model. Several parametrizations with different nuclear matter saturation properties are proposed. At subsaturation, nuclear pasta phases are calculated within two methods: the coexistence-phases approximation and the compressible liquid drop model, with the surface tension coefficient determined using a geometrical approach at zero temperature. A unified equation of state of stellar matter for the inner crust, with the nuclear pasta phases, and the core is calculated. The mass and radius of neutron stars within this framework are obtained for several families of hadronic and hybrid stars. The quark phase of hybrid stars is described within the SU(3) NJL model including a vector term. Stellar macroscopic properties are in accordance with some of the recent results in the literature.

  14. Spontaneous Electromagnetic Superconductivity of Vacuum in a Strong Magnetic Field: Evidence from the Nambu-Jona-Lasinio Model

    Science.gov (United States)

    Chernodub, M. N.

    2011-04-01

    Using an extended Nambu-Jona-Lasinio model as a low-energy effective model of QCD, we show that the vacuum in a strong external magnetic field (stronger than 1016T) experiences a spontaneous phase transition to an electromagnetically superconducting state. The unexpected superconductivity of, basically, empty space is induced by emergence of quark-antiquark vector condensates with quantum numbers of electrically charged rho mesons. The superconducting phase possesses an anisotropic inhomogeneous structure similar to a periodic Abrikosov lattice in a type-II superconductor. The superconducting vacuum is made of a new type of vortices which are topological defects in the charged vector condensates. The superconductivity is realized along the axis of the magnetic field only. We argue that this effect is absent in pure QED.

  15. Decays τ → (η, η') K-ντ in the extended Nambu-Jona-Lasinio model

    Science.gov (United States)

    Volkov, M. K.; Pivovarov, A. A.

    2016-05-01

    The decays τ → (η, η') K-ντ are described in the framework of the extended Nambu-Jona-Lasinio model. Both full and differential widths of these decays are calculated. The vector and scalar channels are considered. In the vector channel, the subprocesses with the intermediate K*(892) and K*(1410) mesons play the main role. In the scalar channel, the subprocesses with the intermediate and K 0 * (800) and K 0 * (1430) mesons are taken into account. The scalar channel gives an insignificant contribution to the full width of the decay τ → η K-ντ. The obtained results are in satisfactory agreement with the experimental data. The prediction for the width of the process τ → η' K-ντ is made.

  16. Supersymmetry breaking in the Nambu - Jona-Lasinio approach

    CERN Document Server

    Peschanski, R; Peschanski, R; Savoy, C A

    1995-01-01

    Gaugino condensation in the hidden sector of supergravity models is described within a Nambu-Jona-Lasinio type of approach by minimization of a one-loop scalar potential. The essential ingredients of the mechanism are auxiliary superfields whose v.e.v. generate gaugino condensation and supersymmetry breaking, introduced through Lagrange multipliers. For phenomenologically acceptable values of the gauge couplings, gaugino condensation is disfavoured in this approach. For completeness, it is shown that supersymmetry breaking would occur for a stronger coupling, but at a scale inconsistent with the expectations.

  17. The Gross-Neveu model and the supersymmetric and non-supersymmetric Nambu - Jona-Lasinio model in a magnetic field

    CERN Document Server

    Elias, V; Miransky, V A; Shovkovy, I A

    1996-01-01

    The infrared dynamics in the (3+1)--dimensional supersymmetric and non--supersymmetric Nambu--Jona--Lasinio model in a constant magnetic field is studied. It is shown that while at strong coupling the dynamics in these two models is essentially different, the models become equivalent at weak coupling. In particular, at weak coupling, as the strength of the magnetic field goes to infinity, both the supersymmetric and non--supersymmetric Nambu--Jona--Lasinio models with N_c colors become equivalent to the (1+1)--dimensional Gross-Neveu model with the number of colors \\tilde{N}_c=N_c|eB|S/2\\pi, where S is the area in the plane perpendicular to the magnetic field {\\bf B}. The relevance of these results for cosmological models based on superymmetric dynamics is pointed out.

  18. Transport Theory from the Nambu-Jona-Lasinio Lagrangian

    CERN Document Server

    Marty, R; Bratkovskaya, E; Aichelin, J

    2015-01-01

    Starting from the (Polyakov-) Nambu-Jona-Lasinio Lagrangian, (P)NJL, we formulate a transport theory which allows for describing the expansion of a quark-antiquark plasma and the subsequent transition to the hadronic world --without adding any new parameter to the standard (P)NJL approach, whose parameters are fixed to vacuum physics. This transport theory can be used to describe ultrarelativistic heavy-ion reaction data as well as to study the (first-order) phase transition during the expansion of the plasma. (P)NJL predicts such a phase transition for finite chemical potentials. In this contribution we give an outline of the necessary steps to obtain such a transport theory and present first results.

  19. Cosmology and Quantum Field Theory II: Study of an extended Nambu-Jona-Lasinio model with a Dynamical Coupling

    CERN Document Server

    G., Leonardo Quintanar

    2015-01-01

    We study the cosmological implications of the Nambu-Jona-Lasinio (NJL model) when the coupling constant is field dependent. The NJL model has a four-fermion interaction describing two different phases due to quantum interaction effects and determined by the strength of the coupling constant g. It describes massless fermions for weak coupling and a massive fermions and strong coupling, where a fermion condensate is formed. In the original NJL model the coupling constant g is indeed constant, and in this work we consider a modified version of the NJL model by introducing a dynamical field dependent coupling motivated by string theory. The effective potential as a function of the varying coupling (aimed to implement a natural phase transition) is seen to develop a negative divergence, i.e. becomes a "bottomless well" in certain limit region. Although we explain how an lower unbounded potential is not necessarily unacceptable in a cosmological context, the divergence can be removed if we consider a mass term for ...

  20. The solitonic modulation and Lifshitz point in an external magnetic field within Nambu--Jona-Lasinio model

    CERN Document Server

    Cao, Gaoqing

    2016-01-01

    We study the inhomogeneous solitonic modulation of chiral condensate within the effective Nambu--Jona-Lasinio model when a constant external magnetic field is present. The self-consistent Pauli-Villars regularization scheme is adopted to manipulate the ultraviolet divergence encountered in the thermodynamic quantities. In order to determine the chiral restoration lines efficiently, a new kind of Ginzburg-Landau expansion approach is proposed here. At zero temperature, we find that both the upper and lower boundaries of the solitonic modulation oscillate with the magnetic field in the $\\mu$--$B$ phase diagram which is actually the de Hass-van Alphan (dHvA) oscillation. It is very interesting to find out how the tricritical Lifshitz point $(T_L,\\mu_L)$ evolves with the magnetic field: There are also dHvA oscillations in the $T_L$--$B$ and $\\mu_L$--$B$ curves, though the tricritical temperature $T_L$ increases monotonically with the magnetic field.

  1. Interplay between quark-antiquark and diquark condensates in vacuum in a two-flavor Nambu-Jona-Lasinio model

    CERN Document Server

    Bang-Rong, Z

    2007-01-01

    By means of a relativistic effective potential, we have analytically researched competition between the quark-antiquark condensates $$ and the diquark condensates $$ in vacuum in ground state of a two-flavor Nambu-Jona-Lasinio (NJL) model and obtained the $G_S-H_S$ phase diagram, where $G_S$ and $H_S$ are the respective four-fermion coupling constants in scalar quark-antiquark channel and scalar color anti-triplet diquark channel. The results show that, in the chiral limit, there is only the pure $$ phase when $G_S/H_S>2/3$, and as $G_S/H_S$ decreases to $2/3>G_S/H_S\\geq 0$ one will first have a coexistence phase of the condensates $$ and $$ and then a pure $$ phase. In non-zero bare quark mass case, the critical value of $G_S/H_S$ at which the pure $$ phase will transfer to the coexistence phase of the condensates $$ and $$ will be less than 2/3. Our theoretical results, combined with present phenomenological fact that there is no diquark condensates in the vacuum of QCD, will also impose a real restriction ...

  2. Symmetry Restoring Phase Transitions at High Density in a 4D Nambu-Jona-Lasinio Model with a Single Order Parameter

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bang-Rong

    2003-01-01

    High density phase transitions in a 4-dimensional Nambu-Jona-Lasinio model containing a single symmetry breaking order parameter coming from the fermion-antifermion condensates are researched and expounded by means of both the gap equation and the effective potential approach. The phase transitions are proven to be second-order at a high temperature T; however at T = 0 they are first- or second-order, depending on whether A/m(0), the ratio of the momentum cutoff A in the fermion-loop integrals to the dynamicalfermion mass m(0) at zero temperature, is less than 3.387 or not. The former condition cannot be satisfied in some models. The discussions further show complete effectiveness of the critical analysis based on the gap equation for second order phase transitions including determination of the condition of their occurrence.

  3. Optimized perturbation theory applied to the study of the thermodynamics and BEC-BCS crossover in the three-color Nambu-Jona-Lasinio model

    Science.gov (United States)

    Duarte, Dyana C.; Farias, R. L. S.; Manso, Pedro H. A.; Ramos, Rudnei O.

    2017-09-01

    The Nambu-Jona-Lasinio model with two flavors, three colors, and diquark interactions is analyzed in the context of optimized perturbation theory (OPT). Corrections to the thermodynamical potential that go beyond the large-Nc (LN) approximation are taken into account, and the region of the phase diagram corresponding to intermediate chemical potentials and very low temperatures is explored. The simultaneous presence of both the quark-antiquark and diquark condensates can cause the system to behave as a fluid composed of a Bose-Einstein condensate (BEC) or a color superconductor one, in the form of a Bardeen-Cooper-Schrieffer (BCS) superfluid. The BEC-BCS crossover is then studied in the nonperturbative OPT scheme. The results obtained in the context of the OPT method are then contrasted with those obtained in the LN approximation. We show that there are values for the coupling constants related to quark-quark and quark-antiquark interactions where the corrections beyond LN brought by the OPT method can influence the behavior of the diquark condensate and the effective quark mass as a function of the baryon chemical potential. These changes in the behavior of the phase structure of the model modify the location of the critical point related to the phase structure as a whole of the model. Also, when we impose the color neutrality condition, our results show that the nature of the phase transition can change as well, shifting the ratio of the quark-antiquark and quark-quark interactions to higher values in the OPT case as compared to the LN approximation.

  4. The processes e+e-→ K±(K∗∓(892),K∗∓(1410)) and e+e-→ (η,η‧(958))(ϕ(1020),ϕ(1680)) in the extended Nambu-Jona-Lasinio model

    Science.gov (United States)

    Volkov, M. K.; Pivovarov, A. A.

    2016-09-01

    The processes e+e-→ K±K∗∓(892) and e+e-→ ηϕ(1020) are calculated in the framework of the extended Nambu-Jona-Lasinio model. The intermediate vector mesons ρ(770), ω(782), ϕ(1020) and their first radially excited states are taken into account. The obtained results are in satisfactory agreement with the experimental data. The predictions for the cross-sections of the reactions e+e-→ K±K∗∓(1410), e+e-→ η‧(958)ϕ(1020) and e+e-→ ηϕ(1680) were made.

  5. The processes $e^{+}e^{-} \\rightarrow K^{\\pm} (K^{*\\mp}(892), K^{*\\mp}(1410))$ and $e^{+}e^{-} \\rightarrow (\\eta, \\eta^{'}(958)) (\\phi(1020), \\phi(1680))$ in the extended Nambu-Jona-Lasinio model

    CERN Document Server

    Volkov, M K

    2016-01-01

    The processes $e^{+}e^{-} \\rightarrow K^{\\pm} K^{*\\mp}(892)$ and $e^{+}e^{-} \\rightarrow \\eta \\phi(1020)$ are calculated in the framework of the extended Nambu-Jona-Lasinio model. The intermediate vector mesons $\\rho(770), \\omega(782), \\phi(1020)$ and their first radially-excited states are taken into account. The obtained results are in satisfactory agreement with the experimental data. The predictions for the cross sections of the reactions $e^{+}e^{-} \\rightarrow K^{\\pm} K^{*\\mp}(1410)$, $e^{+}e^{-} \\rightarrow \\eta^{'}(958) \\phi(1020)$ and $e^{+}e^{-} \\rightarrow \\eta \\phi(1680)$ were made.

  6. Phenomenological implications of a predictive formulation of the Nambu-Jona-Lasinio model having tensor couplings and isospin symmetry breaking terms

    Science.gov (United States)

    Battistel, O. A.; Pimenta, T. H.; Dallabona, G.

    2016-10-01

    In the present work we consider the phenomenological consequences of a predictive formulation of the Nambu-Jona-Lasinio (NJL) model at the one loop level of perturbative calculations. The investigation reported here can be considered as an extension of previously made ones on the same issue. In the study made in this work we have included vector and tensor couplings, simultaneously, as well as S U (2 ) isospin symmetry breaking terms. As a consequence of the last ingredient mentioned, there are different masses in the model amplitudes. In spite of this, within the context of the adopted procedure, we verify that it is possible to eliminate unphysical dependencies on the arbitrary choices for the routing of internal lines momenta as well as Ward identities violating contributions and scale ambiguous terms, from the corresponding one loop amplitudes, through the simple and universal Consistency Relations. The total content of divergence of the amplitudes is reduced to only two basic divergent objects. They are related to two inputs of the model in a way that, due to their scale properties, an unique arbitrariness remains. However, due to the critical condition found in the mechanism which generates the constituent quark mass, within our approach, this arbitrariness is also removed turning the model predictive in the sense that its phenomenological consequences is not dependent in possible choices made in intermediary steps of the calculations, as occurs in usual treatments. In this scenario, we investigate the most typical static properties of the scalar, pseudoscalar, vector and axial-vector mesons at low-energy. Special attention is given to the consequences of the S U (2 ) isospin symmetry breaking for the phenomenological predictions. The implications of the tensor couplings for the model observables, which can be considered an original contribution of the present work, at the level of the content and not only in the form, is analyzed in a detailed way. The found

  7. BCS, Nambu-Jona-Lasinio, and Han-Nambu: A sketch of Nambu's works in 1960-1965

    Science.gov (United States)

    Fujikawa, Kazuo

    2016-06-01

    The years 1960-1965 were a remarkable period for Yoichiro Nambu. Starting with a reformulation of BCS theory with emphasis on gauge invariance, he recognized the realization of spontaneous chiral symmetry breaking in particle physics as evidenced by the Goldberger-Treiman relation. A concrete model of Nambu and Jona-Lasinio illustrated the essence of the Nambu-Goldstone theorem and the idea of soft pions. After the proposal of the quark model by Gell-Mann, he together with Han constructed an alternative model of integrally charged quarks with possible non-Abelian gluons. All these remarkable works were performed during the years 1960-1965. Here I briefly review those works following the original papers of Nambu chronologically, together with a brief introduction to a formulation of Noether's theorem and the Ward-Takahashi identities using path integrals. This article is mostly based on a lecture given at the Nambu Memorial Symposium held at Osaka City University in September 2015, where Nambu started his professional career.

  8. BCS, Nambu-Jona-Lasinio, and Han-Nambu -- A sketch of Nambu's works in 1960-1965

    CERN Document Server

    Fujikawa, Kazuo

    2016-01-01

    The years of 1960-1965 were a remarkable period for Yoichiro Nambu. Starting with a reformulation of BCS theory with emphasis on gauge invariance, he recognized the realization of spontaneous chiral symmetry breaking in particle physics as is evidenced by the Goldberger-Treiman relation. A concrete model of Nambu and Jona-Lasinio illustrated the essence of the Nambu-Goldstone theorem and the idea of soft pions. After the proposal of the quark model by Gell-Mann, he together with Han constructed an alternative model of integrally charged quarks with possible non-Abelian gluons. All those remarkable works were performed during the years 1960-1965. Here I briefly review those works following the original papers of Nambu chronologically, together with a brief introduction to a formulation of Neother's theorem and Ward-Takahashi identities using path integrals. This article is mostly based on a lecture given at the Nambu Memorial Symposium held at Osaka City University in September 2015, where Nambu started his pr...

  9. Variational path-integral approach to back-reactions of composite mesons in the Nambu-Jona-Lasinio model

    Science.gov (United States)

    Blaschke, D.; Ebert, D.

    2017-08-01

    For the investigation of back-reactions of composite mesons in the NJL model, a variational path-integral treatment is formulated which yields an effective action Aeff [Dσ ,Dπ ; S ], depending on the propagators Dσ, Dπ of σ- and π-mesons and on the full quark propagator S. The stationarity conditions δAeff / δS = 0, δAeff / δDσ = 0, δAeff / δDπ = 0, then lead to coupled Schwinger-Dyson (SD) equations for the quark self-energy and the meson polarization functions. These results reproduce and extend results of the so-called ;Φ-derivable; approach and provide a functional formulation for diagrammatic resummations of 1 /Nc -corrections in the NJL model. Finally, we perform a low-momentum estimate of the quark and meson loop contributions to the polarization function of the pion and on this basis discuss the Goldstone theorem.

  10. Gauged Nambu-Jona Lasinio Studies of the Triviality of Quantum Electrodynamics

    CERN Document Server

    Kim, S; Lombardo, M P; Kogut, John B.; Lombardo, Maria-Paola

    2002-01-01

    By adding a small, irrelevant four fermi interaction to the action of noncompact lattice Quantum Electrodynamics (QED), the theory can be simulated with massless quarks in a vacuum free of lattice monopoles. The lattice theory possesses a second order chiral phase transition which we show is logarithmically trivial, with the same systematics as the Nambu-Jona Lasinio model. The irrelevance of the four fermi coupling is established numerically. The widths of the scaling windows are examined in both the coupling constant and bare fermion mass directions in parameter space. For vanishing fermion mass we find a broad scaling window in coupling. By adding a small bare fermion mass to the action we find that the width of the scaling window in the fermion mass direction is very narrow. Only when a subdominant scaling term is added to the leading term of the equation of state are adequate fits to the data possible. The failure of past studies of lattice QED to produce equation of state fits with adequate confidence l...

  11. Magnetic susceptibility of the QCD vacuum in a nonlocal SU(3) PNJL model

    CERN Document Server

    Pagura, V P; Noguera, S; Scoccola, N N

    2016-01-01

    The magnetic susceptibility of the QCD vacuum is analyzed in the framework of a nonlocal SU(3) Polyakov-Nambu-Jona-Lasinio model. Considering two different model parametrizations, we estimate the values of the $u$ and $s$-quark tensor coefficients and magnetic susceptibilities and then we extend the analysis to finite temperature systems. Our numerical results are compared to those obtained in other theoretical approaches and in lattice QCD calculations.

  12. Properties of quarks and mesons in the framework of the Nambu and Jona-Lasinio model (NJL model) for finite temperature and density; Proprietes des quarks et mesons a temperature et densite finies dans le cadre du modele NJL

    Energy Technology Data Exchange (ETDEWEB)

    Nebauer, R

    2000-09-29

    This thesis presents a detailed overview of the thermodynamical properties of the model of Nambu and Jona-Lasinio. In fact, this model can be interpreted as a low energy approximation of QCD. The NJL model has the advantage to be solvable at finite temperature and density. Comparison with QCD lattice calculations show that the NJL model reproduces correctly the feature of chiral symmetry breaking and restoration. We present the chiral phase diagram of the NJL model for three flavors and study the influence of the parameters on the order of the phase transition. The properties of the mesons in a hot and dense medium are another topic of this thesis. We discuss the behaviour of the chiral partners and the influence of the symmetries. A point of special interest are the masses of the kaons in a dense medium. We compare the masses of the kaons with other models like RMF and ChPT. The last part of the thesis is devoted to the low temperature - high density region of the QCD phase diagram. In this region, the formation of a diquark condensate and a superconducting phase are expected. We discuss the structure of the diquark condensate and present the results of the numerical calculations at finite temperature and density. (author)

  13. Molecular dynamics description of an expanding $q$/$\\bar{q}$ plasma with the Nambu--Jona-Lasinio model and applications to heavy ion collisions at RHIC and LHC energies

    CERN Document Server

    Marty, Rudy

    2012-01-01

    We present a relativistic molecular dynamics approach based on the Nambu--Jona-Lasinio Lagrangian. We derive the relativistic time evolution equations for an expanding plasma, discuss the hadronization cross section and how they act in such a scenario. We present in detail how one can transform the time evolution equation to a simulation program and apply this program to study the expansion of a plasma created in experiments at RHIC and LHC. We present first results on the centrality dependence of $v_2$ and of the transverse momentum spectra of pions and kaons and discuss in detail the hadronisation mechanism.

  14. Estrelas de quarks no modelo de Nambu-Jona-Lasinio com interações vetoriais.

    OpenAIRE

    Jaziel Goulart Coelho

    2009-01-01

    Neste trabalho estudamos o modelo de Nambu-Jona-Lasinio na versão SU(2) com acoplamento vetorial repulsivo e investigamos a estabilidade da matéria de quarks, realizando um estudo da transição de fase quiral no modelo de NJL em termos de uma análise do potencial termodinâmico do sistema. Para o estudo da estabilidade da matéria de quarks, analisamos o comportamento da pressão e da energia por partícula em função da densidade bariônica. O estado de equilíbrio é determinado como o ponto onde o ...

  15. Symmetry Restoring Phase Transitions at High Density in a 4D Nambu-Jona-Lasinio Model with a Single Order Parameter

    Institute of Scientific and Technical Information of China (English)

    ZHOUBang-Rong

    2003-01-01

    High density phase transitions in a 4-dimensional Nambu-dona-Lasinio model containing a single symmetry breaking order parameter coming from the fermion-antifermion condensates are researched and expounded by means of both the gap equation and the effective potential approach. The phase transitions are proven to be second-order at a high temperature T; however at T = 0 they are first- or second-order, depending on whether A/m(0), the ratio of the momentum cutoff A in the fermion-loop integrals to the dynamical fermion mass m(0) at zero temperature, is lessthan 3.387 or not. The former condition cannot be satisfied in some models. The discussions further show complete effectiveness of the critical analysis based on the gap equation for second order phase transitions including determination of the condition of their occurrence.

  16. Symmetry energy and neutron star properties in the saturated Nambu–Jona-Lasinio model

    Directory of Open Access Journals (Sweden)

    Si-Na Wei

    2016-12-01

    Full Text Available In this work, we adopt the Nambu–Jona-Lasinio (NJL model that ensures the nuclear matter saturation properties to study the density dependence of the symmetry energy. With the interactions constrained by the chiral symmetry, the symmetry energy shows novel characters different from those in conventional mean-field models. First, the negative symmetry energy at high densities that is absent in relativistic mean-field (RMF models can be obtained in the RMF approximation by introducing a chiral isovector–vector interaction, although it would be ruled out by the neutron star (NS stability. Second, with the inclusion of the isovector–scalar interaction the symmetry energy exhibits a general softening at high densities even for the large slope parameter of the symmetry energy. The NS properties obtained in the present NJL model can be in accord with the observations. The NS maximum mass obtained with various isovector–scalar couplings and momentum cutoffs is well above the 2M⊙, and the NS radius obtained well meets the limits extracted from recent measurements. In particular, the significant reduction of the canonical NS radius occurs with the moderate decrease of the slope of the symmetry energy.

  17. Stabilization of the linear SU(2) Nambu-Jona-Lasinio soliton via vector mesons

    Energy Technology Data Exchange (ETDEWEB)

    Arriola, E.R. (Bochum Univ. (Germany). Inst. fuer Theoretische Physik 2 Granada Univ. (Spain). Dept. de Fisica Moderna); Doering, F.; Schueren, C.; Goeke, K. (Bochum Univ. (Germany). Inst. fuer Theoretische Physik 2)

    1994-03-01

    The solitonic sector of the SU(2) NJL model with [sigma], [pi] [rho] A[sub 1] and [omega] mesons is investigated. the scalar and pseudo-scalar meson fields are not constrained to the chiral circle condition, i.e. [sigma][sup 2](r) + ''pi''[sup 2](r) ''no='' f[sub [pi

  18. Nonuniform phases in the ’t Hooft extended Nambu–Jona-Lasinio model

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, J.; Hiller, B.; Blin, A. H. [Centro de Física Computacional, Departamento de Física da Universidade de Coimbra, 3004-516 Coimbra (Portugal); Osipov, A. A. [Centro de Física Computacional, Departamento de Física da Universidade de Coimbra, 3004-516 Coimbra (Portugal); on leave from Dzhelepov Laboratory of Nuclear Problems, JINR 141980 Dubna (Russian Federation)

    2016-01-22

    The phase diagram of cold dense quark matter is studied using the ’t Hooft extended Nambu-Jona–Lasinio Model applied to the light quark sector with a finite current mass for the strange quark (up and down are considered in the chiral limit). By relaxing the traditional uniformity assumptions and considering a modulated light quark condensate background we investigate the possible existence of non-uniform phases in this region of the phase diagram. The effects of changes in the coupling strengths of the model are studied and it is shown that the inclusion of flavour mixing combined with the finite current mass of the strange quark catalyses the appearance of the non-uniform phases, extending the domain for their existence.

  19. Nonlocal quark model description of a composite Higgs particle

    CERN Document Server

    Kachanovich, Aliaksei

    2016-01-01

    We propose a description of the Higgs boson as top-antitop quark bound state within a nonlocal relativistic quark model of Nambu - Jona-Lasinio type. In contrast to model with local four-fermion interaction, the mass of the scalar bound state can be lighter than the sum of its constituents. This is achieved by adjusting the interaction range and the value of the coupling constant to experimental data, for both the top quark mass and the scalar Higgs boson mass, which can simultaneously be described.

  20. Magnetic catalysis and inverse magnetic catalysis in nonlocal chiral quark models

    Science.gov (United States)

    Pagura, V. P.; Gómez Dumm, D.; Noguera, S.; Scoccola, N. N.

    2017-02-01

    We study the behavior of strongly interacting matter under an external constant magnetic field in the context of nonlocal chiral quark models within the mean field approximation. We find that at zero temperature the behavior of the quark condensates shows the expected magnetic catalysis effect, our predictions being in good quantitative agreement with lattice QCD results. On the other hand, in contrast to what happens in the standard local Nambu-Jona-Lasinio model, when the analysis is extended to the case of finite temperature, our results show that nonlocal models naturally lead to the inverse magnetic catalysis effect.

  1. Magnetic catalysis and inverse magnetic catalysis in nonlocal chiral quark models

    CERN Document Server

    Pagura, V P; Noguera, S; Scoccola, N N

    2016-01-01

    We study the behavior of strongly interacting matter under an external constant magnetic field in the context of nonlocal chiral quark models within the mean field approximation. We find that at zero temperature the behavior of the quark condensates shows the expected magnetic catalysis effect, our predictions being in good quantitative agreement with lattice QCD results. On the other hand, in contrast to what happens in the standard local Nambu-Jona-Lasinio model, when the analysis is extended to the case of finite temperature our results show that nonlocal models naturally lead to the Inverse Magnetic Catalysis effect.

  2. Melting of the quark condensate in the NJL model with meson loops

    Energy Technology Data Exchange (ETDEWEB)

    Florkowski, W.; Broniowski, W. [Institute of Nuclear Physics, Cracow (Poland)

    1996-05-01

    Temperature dependence of the quark condensate is studied in the Nambu-Jona-Lasinio model with meson loops. Substantial differences are found compared to the results with quark loop only. (author). 13 refs, 3 figs.

  3. Universal limiting pressure for a three-flavor color superconducting PNJL model phase diagram

    CERN Document Server

    Ayriyan, A; Blaschke, D; Lastowiecki, R

    2016-01-01

    The phase diagram of a three-flavor Polyakov-loop Nambu-Jona-Lasinio model is analyzed for the case of isospin symmetric matter with color superconducting phases. The coexistence of chiral symmetry breaking and two-flavor color superconductivity (2SC phase) and a thermodynamic instability due to the implementation of a color neutrality constraint is observed. It is suggested to use a universal hadronization pressure to estimate the phase border between hadronic and quark-gluon plasma phases. Trajectories of constant entropy per baryon are analyzed for conditions appropriate for heavy-ion collisions in the NICA-FAIR energy range.

  4. Equation of state of a quark-Polyakov loop-meson mixture in the PNJL model at finite temperature

    CERN Document Server

    Torres-Rincon, Juan M

    2016-01-01

    Recent consensus on the $N_f=2+1$ equation of state at vanishing chemical potential from different lattice-QCD groups has spoiled the previous agreement with the outcome from the mean-field Polyakov-Nambu-Jona-Lasinio model. In this letter we review the thermodynamics of the PNJL model introducing two important aspects needed to describe the pressure computed in the lattice QCD. First, we consider the thermodynamics of the model beyond the mean-field approach to include pseudoscalar and scalar mesonic-like fluctuations into the grand-canonical potential. This accounts for the hadronic pressure of the system below the critical temperature. On the other hand we also implement the back reaction of quarks into the Polyakov-loop effective potential bringing a reduction of the pressure above $T_c$ from the Stefan-Boltzmann limit. We get a good agreement with lattice-QCD data at low and moderate temperatures, opening the door to a straightforward extension to finite chemical potential.

  5. Non-Local effective SU(2) Polyakov-loop models from inverse Monte-Carlo methods

    CERN Document Server

    Bahrampour, Bardiya; von Smekal, Lorenz

    2016-01-01

    The strong-coupling expansion of the lattice gauge action leads to Polyakov-loop models that effectively describe gluodynamics at low temperatures, and together with the hopping expansion of the fermion determinant provides insight into the QCD phase diagram at finite density and low temperatures, although for rather heavy quarks. At higher temperatures the strong-coupling expansion breaks down and it is expected that the interactions between Polyakov loops become non-local. Here, we therefore test how well pure SU(2) gluodynamics can be mapped onto different non-local Polyakov models with inverse Monte-Carlo methods. We take into account Polyakov loops in higher representations and gradually add interaction terms at larger distances. We are particularly interested in extrapolating the range of non-local terms in sufficiently large volumes and higher representations. We study the characteristic fall-off in strength of the non-local couplings with the interaction distance, and its dependence on the gauge coupl...

  6. Thermo-magnetic nonlocal NJL model in the real and imaginary time formalisms

    CERN Document Server

    Márquez, F

    2016-01-01

    In this article we study a nonlocal Nambu--Jona-Lasinio (nNJL) model with a Gaussian regulator in presence of a uniform magnetic field. We take a mixed approach to the incorporation of temperature in the model, and consider aspects of both real and imaginary time formalisms. We include confinement in the model through the quasiparticle interpretation of the poles of the propagator. The effect of the magnetic field in the deconfinement phase transition is then studied. It is found that, like with chiral symmetry restoration, magnetic catalysis occurs for the deconfinement phase transition. It is also found that the magnetic field enhances the thermodynamical instability of the system. We work in the weak field limit, i.e. $(eB)<5m_\\pi^2$. At this level there is no splitting of the critical temperatures for chiral and deconfinement phase transitions.

  7. Thermodynamics of the PNJL model

    Energy Technology Data Exchange (ETDEWEB)

    Ratti, C. [ECT, Villazzano (Trento) (Italy); INFN, Gruppo Collegato di Trento, Povo (Trento) (Italy); Roessner, S.; Thaler, M.A.; Weise, W. [Technische Universitaet Muenchen, Physik-Department, Garching (Germany)

    2007-01-15

    QCD thermodynamics is investigated by means of the Polyakov-loop-extended Nambu-Jona-Lasinio (PNJL) model, in which quarks couple simultaneously to the chiral condensate and to a background temporal gauge field representing Polyakov loop dynamics. The behaviour of the Polyakov loop as a function of temperature is obtained by minimising the thermodynamic potential of the system. A Taylor series expansion of the pressure is performed. Pressure difference and quark number density are then evaluated up to sixth order in the quark chemical potential and compared to the corresponding lattice data. The validity of the Taylor expansion is discussed within our model through a comparison between the full results and the truncated ones. (orig.)

  8. Light-by-Light Hadronic Corrections to the Muon G-2 Problem Within the Nonlocal Chiral Quark Model

    Science.gov (United States)

    Dorokhov, A. E.; Radzhabov, A. E.; Zhevlakov, A. S.

    2017-03-01

    Results of calculation of the light-by-light contribution from the lightest neutral pseudoscalar and scalar mesons and the dynamical quark loop to the muon anomalous magnetic moment are discussed in the framework of the nonlocal SU(3) × SU(3) chiral quark model. The model is based on four-quark interaction of the Nambu-Jona-Lasinio type and Kobayashi-Maskawa-`t Hooft six-quark interaction. The full kinematic dependence of vertices with off-shell mesons and photons in intermediate states in the light-by-light scattering amplitude is taken into account. All calculations are elaborated in explicitly gauge-invariant manner. These results complete calculations of all hadronic light-by-light scattering contributions to aμ in the leading order in the 1/Nc expansion. The final result does not allow the discrepancy between the experiment and the Standard Model to be explained.

  9. Mapping the QCD Phase Diagram with Susceptibilities of Conserved Charges within Nambu-Jonna-Lasinio Model

    CERN Document Server

    Fan, Wenkai; Zong, Hong-Shi

    2016-01-01

    Under the chemical equilibrium and electric charge neutrality conditions, we evaluate the $2$nd to $4$th order baryon, charge and strangeness susceptibilities near a chiral critical point using the Nambu--Jona--Lasinio model. Because of the considerati on of electron chemical potential, up and down quarks are no longer degenerate, but have a chemical potential difference. This isospin chemical potential does not bring new qualitative features in the QCD phase diagram. Furthermore, baryon number susce ptibilities are found to be of the greatest magnitude, offering the strongest signal. Whereas the strangeness susceptibilities have the smallest divergence dominating area, owing to the large strange quark mass.

  10. Modeling the thermodynamics of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Hell, Thomas

    2010-07-26

    Strongly interacting (QCD) matter is expected to exhibit a multifaceted phase structure: a hadron gas at low temperatures, a quark-gluon plasma at very high temperatures, nuclear matter in the low-temperature and high-density region, color superconductors at asymptotically high densities. Most of the conjectured phases cannot yet be scrutinized by experiments. Much of the present picture - particularly concerning the intermediate temperature and density area of the phase diagram of QCD matter - is based on model calculations. Further insights come from Lattice-QCD computations. The present thesis elaborates a nonlocal covariant extension of the Nambu and Jona-Lasinio (NJL) model with built-in constraints from the running coupling of QCD at high-momentum and instanton physics at low-momentum scales. We present this model for two and three quark flavors (in the latter case paying particular attention to the axial anomaly). At finite temperatures and densities, gluon dynamics is incorporated through a gluonic background field, expressed in terms of the Polyakov loop (P). The thermodynamics of this nonlocal PNJL model accounts for both chiral and deconfinement transitions. We obtain results in mean-field approximation and beyond, including additional pionic and kaonic contributions to the chiral condensate, the pressure and other thermodynamic quantities. Finally, the nonlocal PNJL model is applied to the finite-density region of the QCD phase diagram; for three quark flavors we investigate, in particular, the dependence of the critical point appearing in the models on the axial anomaly. The thesis closes with a derivation of the nonlocal PNJL model from first principles of QCD. (orig.)

  11. Phase transition of strongly interacting matter with a chemical potential dependent Polyakov loop potential

    CERN Document Server

    Shao, Guo-yun; Di Toro, Massimo; Colonna, Maria; Gao, Xue-yan; Gao, Ning

    2016-01-01

    We construct a hadron-quark two-phase model based on the Walecka-quantum hadrodynamics and the improved Polyakov-Nambu--Jona-Lasinio model with an explicit chemical potential dependence of Polyakov-loop potential ($\\mu$PNJL model). With respect to the original PNJL model, the confined-deconfined phase transition is largely affected at low temperature and large chemical potential. Using the two-phase model, we investigate the equilibrium transition between hadronic and quark matter at finite chemical potentials and temperatures. The numerical results show that the transition boundaries from nuclear to quark matter move towards smaller chemical potential (lower density) when the $\\mu$-dependent Polyakov loop potential is taken. In particular, for charge asymmetric matter, we compute the local asymmetry of $u, d$ quarks in the hadron-quark coexisting phase, and analyse the isospin-relevant observables possibly measurable in heavy-ion collision (HIC) experiments. In general new HIC data on the location and proper...

  12. Baryons in the large N limit of the massive NJL2 model

    CERN Document Server

    Boehmer, Christian; Thies, Michael

    2008-01-01

    Baryons in the massive Nambu-Jona-Lasinio model in 1+1 dimensions (the massive chiral Gross-Neveu model) are studied in the limit of an infinite number of flavors. The baryon mass is evaluated for a wide range of bare fermion masses and filling fractions, combining analytical asymptotic expansions with a full numerical Hartree-Fock calculation.

  13. Radiative decays of mesons in the NJL model

    CERN Document Server

    Epele, L N; Dumm, D G; Grunfeld, A G

    2001-01-01

    We revisit the theoretical predictions for anomalous radiative decays of pseudoscalar and vector mesons. Our analysis is performed in the framework of the Nambu-Jona-Lasinio model, introducing adequate parameters to account for the breakdown of chiral symmetry. The results are comparable with those obtained in previous approaches.

  14. Flavor dependence of baryon melting temperature in effective models of QCD

    Science.gov (United States)

    Torres-Rincon, Juan M.; Sintes, Benjamin; Aichelin, Joerg

    2015-06-01

    We apply the three-flavor (Polyakov-)Nambu-Jona-Lasinio model to generate baryons as quark-diquark bound states using many-body techniques at finite temperature. All the baryonic states belonging to the octet and decuplet flavor representations are generated in the isospin-symmetric case. For each state we extract the melting temperature at which the baryon may decay into a quark-diquark pair. We seek for an evidence of the strangeness dependence of the baryon melting temperature as suggested by the statistical thermal models and supported by lattice quantum chromodynamics results. A clear and robust signal for this claim is found, pointing to a flavor dependence of the hadronic deconfinement temperature.

  15. Dynamical CP violation of the generalized Yang-Mills model%Dynamical CP violation of the generalized Yang-Mills model

    Institute of Scientific and Technical Information of China (English)

    WANG Dian-Fu; SUN Xiao-Yu; CHANG Xiao-Jing

    2011-01-01

    Starting from the generalized Yang-Mills model which contains, besides the vector part Vμ, also a scalar part S and a pseudoscalar part P. It is shown, in terms of the Nambu-Jona-Lasinio (NJL) mechanism, that CP violation can be realized dynamically. The

  16. A New Problem and the Possible Solution in the Technicoloured Preon Model

    Science.gov (United States)

    Matumoto, K.

    1989-02-01

    A version of technicoloured preon model, giving the appropriate order of fermion mass despite the large mass scale of the preonic dynamics of the order of the axion decay constant, is presented, where the dynamics is described by the chiral symmetry breaking solution of the ladder Schwinger-Dyson-Nambu-Jona-Lasinio-hybrid equation.

  17. Dynamical Symmetry Breaking of Maximally Generalized Yang-Mills Model and Its Restoration at Finite Temperatures

    Institute of Scientific and Technical Information of China (English)

    WANG Dian-Fu

    2008-01-01

    In terms of the Nambu-Jona-Lasinio mechanism, dynamical breaking of gauge symmetry for the maximally generalized Yang-Mills model is investigated. The gauge symmetry behavior at finite temperature is also investigated and it is shown that the gauge symmetry broken dynamically at zero temperature can be restored at finite temperatures.

  18. On the critical end point of the QCD and the NJL model phase diagrams

    CERN Document Server

    Ruggieri, Marco

    2009-01-01

    In this talk I compare the knowledge on the critical end point of the QCD phase diagram grasped from lattice calculations, with that obtained from Nambu--Jona-Lasinio (NJL) model computations. The original publication is available at http://www.sif.it/SIF/en/portal/journals

  19. Confronting effective models for deconfinement in dense quark matter with lattice data

    CERN Document Server

    Andersen, Jens O; Naylor, William

    2015-01-01

    Ab initio numerical simulations of the thermodynamics of dense quark matter remain a challenge. Apart from the infamous sign problem, lattice methods have to deal with finite volume and discretization effects as well as with the necessity to introduce sources for symmetry-breaking order parameters. We study these artifacts in the Polyakov-loop-extended Nambu-Jona-Lasinio model, and compare its predictions to existing lattice data for cold and dense two-color matter with two flavors of Wilson quarks. To achieve even qualitative agreement with lattice data \\emph{requires} the introduction of two novel elements in the model: (i) explicit chiral symmetry breaking in the effective contact four-fermion interaction, referred to as the chiral twist, and (ii) renormalization of the Polyakov loop. The feedback of the dense medium to the gauge sector is modeled by a chemical-potential-dependent scale in the Polyakov-loop potential. In contrast to previously used analytical ans\\"atze, we determine its dependence on the c...

  20. Quark confinement in a constituent quark model

    Energy Technology Data Exchange (ETDEWEB)

    Langfeld, K.; Rho, M. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique

    1995-07-01

    On the level of an effective quark theory, we define confinement by the absence of quark anti-quark thresholds in correlation function. We then propose a confining Nambu-Jona-Lasinio-type model. The confinement is implemented in analogy to Anderson localization in condensed matter systems. We study the model`s phase structure as well as its behavior under extreme conditions, i.e. high temperature and/or high density.

  1. Superconducting phases of strange quark matter in the NJL model

    CERN Document Server

    Paulucci, L; Ferrer, E J; de la Incera, V

    2013-01-01

    We analyze the color-flavor-locked phase of strange quark matter modelled by the three-flavor Nambu-Jona-Lasinio (NJL) framework with and without magnetic field and discuss some additional constraints on the stability scenario when a high magnetic field is applied. We compare the results obtained by employing the MIT Bag Model and discuss the pairing gap behavior and its influence on the equation of state.

  2. Dynamical CP violation of the generalized Yang-Mills model

    Institute of Scientific and Technical Information of China (English)

    WANG Dian-Fu; SUN Xiao-Yu; CHANG Xiao-Jing

    2011-01-01

    Starting from the generalized Yang-Mills model which contains, besides the vector part Vμ, also a scalar part S and a pseudoscalar part P. It is shown, in terms of the Nambu-Jona-Lasinio (NJL) mechanism,that CP violation can be realized dynamically. The combination of the generalized Yang-MiUs model and the NJL mechanism provides a new way to explain CP violation.

  3. What can we learn from NJL-type models about dense matter?

    CERN Document Server

    Buballa, Michael

    2016-01-01

    The merits and limitations of the Nambu--Jona-Lasinio model as a model for strong interactions at nonzero density are critically discussed. We present several examples, demonstrating that, while in general the results should not be trusted quantitatively, the NJL model is a powerful theoretical tool for getting new insights and ideas about the QCD phase diagram and the dense-matter equation of state.

  4. On SU(3 Effective Models and Chiral Phase Transition

    Directory of Open Access Journals (Sweden)

    Abdel Nasser Tawfik

    2015-01-01

    Full Text Available Sensitivity of Polyakov Nambu-Jona-Lasinio (PNJL model and Polyakov linear sigma-model (PLSM has been utilized in studying QCD phase-diagram. From quasi-particle model (QPM a gluonic sector is integrated into LSM. The hadron resonance gas (HRG model is used in calculating the thermal and dense dependence of quark-antiquark condensate. We review these four models with respect to their descriptions for the chiral phase transition. We analyze the chiral order parameter, normalized net-strange condensate, and chiral phase-diagram and compare the results with recent lattice calculations. We find that PLSM chiral boundary is located in upper band of the lattice QCD calculations and agree well with the freeze-out results deduced from various high-energy experiments and thermal models. Also, we find that the chiral temperature calculated from HRG is larger than that from PLSM. This is also larger than the freeze-out temperatures calculated in lattice QCD and deduced from experiments and thermal models. The corresponding temperature and chemical potential are very similar to that of PLSM. Although the results from PNJL and QLSM keep the same behavior, their chiral temperature is higher than that of PLSM and HRG. This might be interpreted due the very heavy quark masses implemented in both models.

  5. Effective Model Approach to the Dense State of QCD Matter

    CERN Document Server

    Fukushima, Kenji

    2010-01-01

    The first-principle approach to the dense state of QCD matter, i.e. the lattice-QCD simulation at finite baryon density, is not under theoretical control for the moment. The effective model study based on QCD symmetries is a practical alternative. However the model parameters that are fixed by hadronic properties in the vacuum may have unknown dependence on the baryon chemical potential. We propose a new prescription to constrain the effective model parameters by the matching condition with the thermal Statistical Model. In the transitional region where thermal quantities blow up in the Statistical Model, deconfined quarks and gluons should smoothly take over the relevant degrees of freedom from hadrons and resonances. We use the Polyakov-loop coupled Nambu--Jona-Lasinio (PNJL) model as an effective description in the quark side and show how the matching condition is satisfied by a simple ansatz on the Polyakov loop potential. Our results favor a phase diagram with the chiral phase transition located at sligh...

  6. On SU(3) effective models and chiral phase-transition

    CERN Document Server

    Tawfik, Abdel Nasser

    2015-01-01

    The sensitivity of Polyakov Nambu-Jona-Lasinio (PNJL) model as an effective theory of quark dynamics to chiral symmetry has been utilized in studying the QCD phase-diagram. Also, Poyakov linear sigma-model (PLSM), in which information about the confining glue sector of the theory was included through Polyakov-loop potential. Furthermore, from quasi-particle model (QPM), the gluonic sector of QPM is integrated to LSM in order to reproduce recent lattice calculations. We review PLSM, QLSM, PNJL and HRG with respect to their descriptions for the chiral phase-transition. We analyse chiral order-parameter M(T), normalized net-strange condensate Delta_{q,s}(T) and chiral phase-diagram and compare the results with lattice QCD. We conclude that PLSM works perfectly in reproducing M(T) and Delta_{q,s}(T). HRG model reproduces Delta_{q,s}(T), while PNJL and QLSM seem to fail. These differences are present in QCD chiral phase-diagram. PLSM chiral boundary is located in upper band of lattice QCD calculations and agree we...

  7. Memorial volume for Y. Nambu

    CERN Document Server

    Chang, Lay Nam; Han, Moo-Young; Phua, Kok Khoo

    2016-01-01

    We have lost one of the giants of the twentieth century physics when Yoichiro Nambu passed away in July, 2015, at the age of 94. Today's Standard Model, though still incomplete in many respects, is the culmination of the most successful theory of the Universe to date, and it is built upon foundations provided by discoveries made by Nambu in the 1960s: the mechanism of spontaneously broken symmetry in Nature (with G Jona-Lasinio) and the hidden new SU(3) symmetry of quarks and gluons (with M-Y Han). In this volume honoring Nambu's memory, World Scientific Publishing presents a unique collection of papers written by his former colleagues, collaborating researchers and former students and associates, not only citing Nambu's great contributions in physics but also many personal and private reminiscences, some never told before. This volume also contains the very last scientific writing by Professor Nambu himself, discussing the development of particle physics. This book is a volume for all who benefited not on...

  8. Isospin properties of quark matter from a 3-flavor NJL model

    Science.gov (United States)

    Liu, He; Xu, Jun; Chen, Lie-Wen; Sun, Kai-Jia

    2016-09-01

    We have studied the properties of hot and dense quark matter based on the 3-flavor Nambu-Jona-Lasinio (NJL) model as well as its Polyakov-loop extension (pNJL) with scalar-isovector and vector-isovector couplings. Provided a considerable large isospin asymmetry or isospin chemical potential, isospin splittings of constituent mass, chiral phase transition boundary, and critical point for u and d quarks can be observed for positive isovector coupling constants but are suppressed for negative ones. The quark matter symmetry energy decreases with the increasing isovector coupling constant, and is mostly enhanced in the pNJL model than in the NJL model. A positive scalar-isovector coupling constant is more likely to lead to an unstable isospin asymmetric quark matter. The isovector coupling has been further found to affect particle fractions as well as the equation of state in hybrid stars. Possible effects on the isospin properties of quark matter have also been discussed if the strangeness sector is further broken among the flavor symmetry.

  9. Study of hot and dense nuclear matter in effective QCD model

    CERN Document Server

    Islam, Chowdhury Aminul

    2016-01-01

    In this thesis we use various effective QCD models to investigate hot and dense nuclear matter created in heavy ion collisions. To characterize such matter, we mainly exploit correlation functions and some of the associated spectral properties. We explore the vector meson current-current correlation function with and without the influence of vector interaction in Nambu\\textendash Jona-Lasinio (NJL) model and also in its Polyakov loop extended version (PNJL). As a spectral property we have computed the dilepton rate which is found to be enhanced in strongly interacting QGP (sQGP) as compared to the Born rate in a weakly coupled QGP. We further consider the idea of entanglement between the chiral and confinement dynamics through the entangled PNJL (EPNJL) model and re-explore the vector spectral function and the spectral property such as the dilepton production rate studied in our earlier effort. Because of the strong entanglement, the coupling strengths run with the temperature and chemical potential. The impl...

  10. Model prediction for temperature dependence of meson pole masses from lattice QCD results on meson screening masses

    CERN Document Server

    Ishii, Masahiro; Yahiro, Masanobu

    2016-01-01

    We propose a practical effective model by introducing temperature ($T$) dependence to the coupling strengths of four-quark and six-quark Kobayashi-Maskawa-'t Hooft interactions in the 2+1 flavor Polyakov-loop extended Nambu-Jona-Lasinio model. The $T$ dependence is determined from LQCD data on the renormalized chiral condensate around the pseudocritical temperature $T_c^{\\chi}$ of chiral crossover and the screening-mass difference between $\\pi$ and $a_0$ mesons in $T > 1.1T_c^\\chi$ where only the $U(1)_{\\rm A}$-symmetry breaking survives. The model well reproduces LQCD data on screening masses $M_{\\xi}^{\\rm scr}(T)$ for both scalar and pseudoscalar mesons, particularly in $T \\ge T_c^{\\chi}$. Using this effective model, we predict meson pole masses $M_{\\xi}^{\\rm pole}(T)$ for scalar and pseudoscalar mesons. For $\\eta'$ meson, the prediction is consistent with the experimental value at finite $T$ measured in heavy-ion collisions. We point out that the relation $M_{\\xi}^{\\rm scr}(T)-M_{\\xi}^{\\rm pole}(T) \\approx...

  11. The Constant-Sound-Speed parameterization for NJL models of quark matter in hybrid stars

    CERN Document Server

    Ranea-Sandoval, Ignacio F; Orsaria, Milva G; Contrera, Gustavo A; Weber, Fridolin; Alford, Mark G

    2016-01-01

    The discovery of pulsars as heavy as 2 solar masses has led astrophysicists to rethink the core compositions of neutron stars, ruling out many models for the nuclear equations of state (EoS). We explore the hybrid stars that occur when hadronic matter is treated in a relativistic mean-field approximation and quark matter is modeled by three-flavor local and non-local Nambu Jona-Lasinio (NJL) models with repulsive vector interactions. The NJL models typically yield equations of state that feature a first order transition to quark matter. Assuming that the quark-hadron surface tension is high enough to disfavour mixed phases, and restricting to EoSes that allow stars to reach 2 solar masses, we find that the appearance of the quark matter core either destabilizes the star immediately (this is typical for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (this is typical for local NJL models). Using the Constant-Sound-Speed parametrization we can see that the reason fo...

  12. Polyakov loop modeling for hot QCD

    Science.gov (United States)

    Fukushima, Kenji; Skokov, Vladimir

    2017-09-01

    We review theoretical aspects of quantum chromodynamics (QCD) at finite temperature. The most important physical variable to characterize hot QCD is the Polyakov loop, which is an approximate order parameter for quark deconfinement in a hot gluonic medium. Additionally to its role as an order parameter, the Polyakov loop has rich physical contents in both perturbative and non-perturbative sectors. This review covers a wide range of subjects associated with the Polyakov loop from topological defects in hot QCD to model building with coupling to the Polyakov loop.

  13. A Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry

    Institute of Scientific and Technical Information of China (English)

    WANG Dian-Fu; SONG He-Shan

    2005-01-01

    A generalized Yang-Mills model, which contains, besides the vector part Vμ, also a scalar part S, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of Nambu-Jona-Lasinio (NJL) mechanism, that the gauge symmetry breaking can be realized dynamically in the generalized Yang-Mills model. The combination of the generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.

  14. Generalized vector form factors of the pion in a chiral quark model

    CERN Document Server

    Broniowski, Wojciech

    2008-01-01

    Generalized vector form factors of the pion, related to the moments of the generalized parton distribution functions, are evaluated in the Nambu--Jona-Lasinio model with the Pauli-Villars regularization. The lowest moments (the electromagnetic and the gravitational form factors) are compared to recent lattice data, with fair agreement. Predictions for higher-order moments are also made. Relevant features of the generalized form factors in the chiral quark models are highlighted and the role of the QCD evolution for the higher-order GFFs is stressed.

  15. Pion Polarizability in the NJL model and Possibilities of its Experimental Studies in Coulomb Nuclear Scattering

    CERN Document Server

    Bystritskiy, Yu M; Pervushin, V N; Volkov, M K

    2009-01-01

    The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model, where the quark loops (in the mean field approximation) and the meson loops (in the $1/N_c$ approximation) are taken into account. We show that quark loop contribution dominates, because the meson loops strongly conceal each other. The sigma-pole contribution $(m^2_\\sigma-t)^{-1}$ plays the main role and contains strong t-dependence of the effective pion polarizability at the region $|t|\\geq 4M_\\pi^2$. Possibilities of experimental test of this sigma-pole effect in the reaction of Coulomb Nuclear Scattering are estimated for the COMPASS experiment.

  16. Dynamical Model of QCD Vacuum and Color Thaw at Finite Temperatures

    Institute of Scientific and Technical Information of China (English)

    WANG Dian-Fu; SONG He-Shan; MI Dong

    2004-01-01

    In terms of the Nambu-Jona-Lasinio (NJL) mechanism, the dynamical symmetry breaking of a simple localgauge model is investigated. An important relation between the vacuum expectation value of gauge fields and scalarfields is derived by solving the Euler equation for the gauge fields. Based on this relation the SU(3) gauge potential isgiven which can be used to explain the asymptotic freedom and confinement of quarks in a hadron. The confinementbehavior at finite temperatures is also investigated and it is shown that color confinement at zero temperature can bemelted away under high temperatures.

  17. Dynamical Model of QCD Vacuum and Color Thaw at Finite Temperatures

    Institute of Scientific and Technical Information of China (English)

    WANGDian-Fu; SONGHe-Shan; MIDong

    2004-01-01

    In terms of the Nambu Jona-Lasinio (NJL) mechanism, the dynamical symmetry breaking of a simple local gauge model is investigated. An important relation between the vacuum expectation value of gauge fields and scalar fields is derived by solving the Euler equation for the gauge fields. Based on this relation the SU(3) gauge potential is given which can be used to explain the asymptotic freedom and confinement of quarks in a hadron. The confinement behavior at finite temperatures is also investigated and it is shown that color confinement at zero temperature can be melted away under high temperatures.

  18. Origin of Mass - Horizons Expanding from the Nambu's Theory

    CERN Document Server

    Yamawaki, Koichi

    2016-01-01

    Origin of mass may be strong dynamics of matter in the vacuum. Since the initial proposal of Nambu for the origin of the nucleon mass, the dynamical symmetry breaking in the strongly coupled underlying theories has been expanding the horizons in the context of the modern version of the origin of mass beyond the Standard Model (SM). The Nambu-Jona-Lasinio (NJL) model is a typical strong coupling theory with the non-zero critical coupling, in sharp contrast to its precedent model, the Bardeen-Cooper-Schrieffer theory for the superconductor. The non-zero critical coupling is also hidden in the asymptotically free gauge theories including QCD and walking technicolor. As is well known, the NJL model can be cast into the SM Higgs Lagrangian. We show that the SM Higgs Lagrangian is simply rewritten into a form of the (approximately) scale-invariant nonlinear sigma model, with both the chiral symmetry and scale symmetry realized nonlinearly, with the SM Higgs being nothing but the (pseudo-) dilaton. The SM Higgs Lagr...

  19. Studies on Polyakov and Nambu-Goto random surface path integrals on QCD(SU(∞)): Interquark potential and phenomenological scattering amplitudes

    Science.gov (United States)

    Botelho, Luiz C. L.

    2017-02-01

    We present new path integral studies on the Polyakov noncritical and Nambu-Goto critical string theories and their applications to QCD(SU(∞)) interquark potential. We also evaluate the long distance asymptotic behavior of the interquark potential on the Nambu-Goto string theory with an extrinsic term in Polyakov’s string at D →∞. We also propose an alternative and a new view to covariant Polyakov’s string path integral with a fourth-order two-dimensional quantum gravity, is an effective stringy description for QCD(SU(∞)) at the deep infrared region.

  20. Emergence of gauge invariance from Nambu models

    CERN Document Server

    Urrutia, L F

    2016-01-01

    In the framework of a hamiltonian nonperturbative approach we show that after demanding current conservation together with the Gauss constraints at some initial time in a nonabelian Nambu model, we recover the corresponding Yang-Mills theory. In this way, the spontaneous Lorentz symmetry breaking present in the Nambu model becomes unobservable and the Goldstone modes can be identified with the corresponding gauge bosons.

  1. The dual quark condensate in local and nonlocal NJL models: An order parameter for deconfinement?

    Directory of Open Access Journals (Sweden)

    Federico Marquez

    2015-07-01

    Full Text Available We study the behavior of the dual quark condensate Σ1 in the Nambu–Jona-Lasinio (NJL model and its nonlocal variant. In quantum chromodynamics Σ1 can be related to the breaking of the center symmetry and is therefore an (approximate order parameter of confinement. The deconfinement transition is then signaled by a strong rise of Σ1 as a function of temperature. However, a similar behavior is also seen in the NJL model, which is known to have no confinement. Indeed, it was shown that in this model the rise of Σ1 is triggered by the chiral phase transition. In order to shed more light on this issue, we calculate Σ1 for several variants of the NJL model, some of which have been suggested to be confining. Switching between “confining” and “non-confining” models and parametrizations we find no qualitative difference in the behavior of Σ1, namely, it always rises in the region of the chiral phase transition. We conclude that without having established a relation to the center symmetry in a given model, Σ1 should not blindly be regarded as an order parameter of confinement.

  2. On the Nambu fermion-boson relations for superfluid 3He

    Science.gov (United States)

    Sauls, J. A.; Mizushima, Takeshi

    2017-03-01

    Superfluid 3He is a spin-triplet (S =1 ), p -wave (L =1 ) BCS condensate of Cooper pairs with total angular momentum J =0 in the ground state. In addition to the breaking of U(1) gauge symmetry, separate spin or orbital rotation symmetry is broken to the maximal subgroup SO (3) S×SO (3) L→SO(3 ) J . The fermions acquire mass mF≡Δ , where Δ is the BCS gap. There are also 18 bosonic excitations: 4 Nambu-Goldstone modes and 14 massive amplitude Higgs modes. The bosonic modes are labeled by the total angular momentum J ∈{0 ,1 ,2 } , and parity under particle-hole symmetry c =±1 . For each pair of angular momentum quantum numbers J ,Jz , there are two bosonic partners with c =±1 . Based on this spectrum, Nambu proposed a sum rule connecting the fermion and boson masses for BCS-type theories, which for 3He-B is MJ,+ 2+MJ,- 2=4 mF2 for each family of bosonic modes labeled by J , where MJ ,c is the mass of the bosonic mode with quantum numbers (J ,c ) . The Nambu sum rule (NSR) has recently been discussed in the context of Nambu-Jona-Lasinio models for physics beyond the standard model to speculate on possible partners to the recently discovered Higgs boson at higher energies. Here, we point out that the Nambu fermion-boson mass relations are not exact. Corrections to the bosonic masses from (i) leading-order strong-coupling corrections to BCS theory, and (ii) polarization of the parent fermionic vacuum lead to violations of the sum rule. Results for these mass corrections are given in both the T →0 and T →Tc limits. We also discuss experimental results, and theoretical analysis, for the masses of the Jc=2± Higgs modes and the magnitude of the violation of the NSR.

  3. Critical behaviors near the (tri-)critical end point of QCD within the NJL model

    CERN Document Server

    Lu, Ya; Cui, Zhu-Fang; Zong, Hong-Shi

    2015-01-01

    We investigate the dynamical chiral symmetry breaking and its restoration at finite density and temperature within the two-flavor Nambu-Jona-Lasinio model, and mainly focus on the critical behaviors near the critical end point (CEP) and tricritical point (TCP) of QCD. The co-existence region of the Wigner and Nambu phase is determined in the phase diagram for the massive and massless current quark, respectively. We use the various susceptibilities to locate the CEP/TCP and then extract the critical exponents near them. Our calculations reveal that the various susceptibilities share the same critical behaviors for the physical current quark mass, while they show different features in the chiral limit. Furthermore the critical exponent of order parameter at the TCP, $\\beta$=1/4, differs from that on the $O(4)$ line, $\\beta$=1/2, which indicates a change in the universality class.

  4. Probing deconfinement in a chiral effective model with Polyakov loop at imaginary chemical potential

    CERN Document Server

    Morita, Kenji; Friman, Bengt; Redlich, Krzysztof

    2011-01-01

    The phase structure of the two-flavor Polyakov-loop extended Nambu-Jona-Lashinio model is explored at finite temperature and imaginary chemical potential with a particular emphasis on the confinement-deconfinement transition. We point out that the confined phase is characterized by a $\\cos3\\mu_I/T$ dependence of the chiral condensate on the imaginary chemical potential while in the deconfined phase this dependence is given by $\\cos\\mu_I/T$ and accompanied by a cusp structure induced by the Z(3) transition. We demonstrate that the phase structure of the model strongly depends on the choice of the Polyakov loop potential $\\mathcal{U}$. Furthermore, we find that by changing the four fermion coupling constant $G_s$, the location of the critical endpoint of the deconfinement transition can be moved into the real chemical potential region. We propose a new parameter characterizing the confinement-deconfinement transition.

  5. The Phase Structure of the Polyakov--Quark-Meson Model

    CERN Document Server

    Schaefer, Bernd-Jochen; Wambach, Jochen

    2007-01-01

    The relation between the deconfinement and chiral phase transition is explored in the framework of an Polyakov-loop-extended two-flavor quark-meson (PQM) model. In this model the Polyakov loop dynamics is represented by a background temporal gauge field which also couples to the quarks. As a novelty an explicit quark chemical potential and N_f-dependence in the Polyakov loop potential is proposed by using renormalization group arguments. The behavior of the Polyakov loop as well as the chiral condensate as function of temperature and quark chemical potential is obtained by minimizing the grand canonical thermodynamic potential of the system. The effect of the Polyakov loop dynamics on the chiral phase diagram and on several thermodynamic bulk quantities is presented.

  6. Phase structure of the Polyakov-quark-meson model

    Science.gov (United States)

    Schaefer, B.-J.; Pawlowski, J. M.; Wambach, J.

    2007-10-01

    The relation between the deconfinement and chiral phase transition is explored in the framework of a Polyakov-loop-extended two-flavor quark-meson (PQM) model. In this model the Polyakov loop dynamics is represented by a background temporal gauge field which also couples to the quarks. As a novelty an explicit quark chemical potential and Nf-dependence in the Polyakov loop potential is proposed by using renormalization group arguments. The behavior of the Polyakov loop as well as the chiral condensate as function of temperature and quark chemical potential is obtained by minimizing the grand canonical thermodynamic potential of the system. The effect of the Polyakov loop dynamics on the chiral phase diagram and on several thermodynamic bulk quantities is presented.

  7. Baryons and baryonic matter in four-fermion interaction models

    Energy Technology Data Exchange (ETDEWEB)

    Urlichs, K.

    2007-02-23

    In this work we discuss baryons and baryonic matter in simple four-fermion interaction theories, the Gross-Neveu model and the Nambu-Jona-Lasinio model in 1+1 and 2+1 space-time dimensions. These models are designed as toy models for dynamical symmetry breaking in strong interaction physics. Pointlike interactions (''four-fermion'' interactions) between quarks replace the full gluon mediated interaction of quantum chromodynamics. We consider the limit of a large number of fermion flavors, where a mean field approach becomes exact. This method is formulated in the language of relativistic many particle theory and is equivalent to the Hartree-Fock approximation. In 1+1 dimensions, we generalize known results on the ground state to the case where chiral symmetry is broken explicitly by a bare mass term. For the Gross-Neveu model, we derive an exact self-consistent solution for the finite density ground state, consisting of a one-dimensional array of equally spaced potential wells, a baryon crystal. For the Nambu- Jona-Lasinio model we apply the derivative expansion technique to calculate the total energy in powers of derivatives of the mean field. In a picture akin to the Skyrme model of nuclear physics, the baryon emerges as a topological soliton. The solution for both the single baryon and dense baryonic matter is given in a systematic expansion in powers of the pion mass. The solution of the Hartree-Fock problem is more complicated in 2+1 dimensions. In the massless Gross-Neveu model we derive an exact self-consistent solution by extending the baryon crystal of the 1+1 dimensional model, maintaining translational invariance in one spatial direction. This one-dimensional configuration is energetically degenerate to the translationally invariant solution, a hint in favor of a possible translational symmetry breakdown by more general geometrical structures. In the Nambu-Jona-Lasinio model, topological soliton configurations induce a finite baryon

  8. The NJL Model for Quark Fragmentation Functions

    Energy Technology Data Exchange (ETDEWEB)

    T. Ito, W. Bentz, I. Cloet, A W Thomas, K. Yazaki

    2009-10-01

    A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain the reason why the elementary (lowest order) fragmentation process q → qπ is completely inadequate to describe the empirical data, although the “crossed” process π → qq describes the quark distribution functions in the pion reasonably well. Then, taking into account cascade-like processes in a modified jet-model approach, we show that the momentum and isospin sum rules can be satisfied naturally without introducing any ad-hoc parameters. We present numerical results for the Nambu-Jona-Lasinio model in the invariant mass regularization scheme, and compare the results with the empirical parametrizations. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory.

  9. The NJL Model for Quark Fragmentation Functions

    Energy Technology Data Exchange (ETDEWEB)

    T. Ito, W. Bentz, I. Cloet, A W Thomas, K. Yazaki

    2009-10-01

    A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain the reason why the elementary (lowest order) fragmentation process q → qπ is completely inadequate to describe the empirical data, although the “crossed” process π → qq describes the quark distribution functions in the pion reasonably well. Then, taking into account cascade-like processes in a modified jet-model approach, we show that the momentum and isospin sum rules can be satisfied naturally without introducing any ad-hoc parameters. We present numerical results for the Nambu-Jona-Lasinio model in the invariant mass regularization scheme, and compare the results with the empirical parametrizations. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory.

  10. Partially composite two-Higgs doublet model

    Indian Academy of Sciences (India)

    Dong-Won Jung

    2007-11-01

    In the extra dimensional scenarios with gauge fields in the bulk, the Kaluza-Klein (KK) gauge bosons can induce Nambu-Jona-Lasinio (NJL) type attractive four-fermion interactions, which can break electroweak symmetry dynamically with accompanying composite Higgs fields. We consider a possibility that electroweak symmetry breaking (EWSB) is triggered by both a fundamental Higgs and a composite Higgs arising in a dynamical symmetry breaking mechanism induced by a new strong dynamics. The resulting Higgs sector is a partially composite two-Higgs doublet model with specific boundary conditions on the coupling and mass parameters originating at a compositeness scale . The phenomenology of this model is discussed including the collider phenomenology at LHC and ILC.

  11. Consistent regularization and renormalization in models with inhomogeneous phases

    Science.gov (United States)

    Adhikari, Prabal; Andersen, Jens O.

    2017-02-01

    In many models in condensed matter and high-energy physics, one finds inhomogeneous phases at high density and low temperature. These phases are characterized by a spatially dependent condensate or order parameter. A proper calculation requires that one takes the vacuum fluctuations of the model into account. These fluctuations are ultraviolet divergent and must be regularized. We discuss different ways of consistently regularizing and renormalizing quantum fluctuations, focusing on momentum cutoff, symmetric energy cutoff, and dimensional regularization. We apply these techniques calculating the vacuum energy in the Nambu-Jona-Lasinio model in 1 +1 dimensions in the large-Nc limit and in the 3 +1 dimensional quark-meson model in the mean-field approximation both for a one-dimensional chiral-density wave.

  12. Ideal walking dynamics via a gauged NJL model

    DEFF Research Database (Denmark)

    Rantaharju, Jarno; Pica, Claudio; Sannino, Francesco

    2017-01-01

    According to the ideal walking technicolor paradigm, large mass anomalous dimensions arise in gauged Nambu-Jona-Lasinio (NJL) models when the four-fermion coupling is sufficiently strong to induce spontaneous symmetry breaking in an otherwise conformal gauge theory. We therefore study the SU(2......) gauged NJL model with two adjoint fermions using lattice simulations. The model is in an infrared conformal phase at small NJL coupling while it displays a chirally broken phase at large NJL couplings. In the infrared conformal phase, we find that the mass anomalous dimension varies with the NJL coupling......, reaching γm∼1 close to the chiral symmetry breaking transition, de facto making the present model the first explicit realization of the ideal walking scenario....

  13. Maximally Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A maximally generalized Yang-Mills model, which contains, besides the vector part Vμ, also an axial-vector part Aμ, a scalar part S, a pseudoscalar part P, and a tensor part Tμv, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of the Nambu-Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the maximally generalized Yang-Mills model. The combination of the maximally generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.

  14. Phase structure of the massive chiral Gross-Neveu model from Hartree-Fock

    CERN Document Server

    Boehmer, Christian; Kraus, Sebastian; Thies, Michael

    2008-01-01

    The phase diagram of the massive chiral Gross-Neveu model (the massive Nambu-Jona-Lasinio model in 1+1 dimensions) is constructed. In the large N limit, the Hartree-Fock approach can be used. We find numerically a chiral crystal phase separated from a massive Fermi gas phase by a 1st order transition. Using perturbation theory, we also construct the critical sheet where the homogeneous phase becomes unstable in a 2nd order transition. A tricritical curve is located. The phase diagram is mapped out as a function of fermion mass, chemical potential and temperature and compared with the one of the discrete chiral Gross-Neveu model. As a by-product, we illustrate the crystal structure of matter at zero temperature for various densities and fermion masses.

  15. A holographic study of the gauged NJL model

    Science.gov (United States)

    Clemens, Will; Evans, Nick

    2017-08-01

    The Nambu Jona-Lasinio model of chiral symmetry breaking predicts a second order chiral phase transition. If the fermions in addition have non-abelian gauge interactions then the transition is expected to become a crossover as the NJL term enhances the IR chiral symmetry breaking of the gauge theory. We study this behaviour in the holographic Dynamic AdS/QCD description of a non-abelian gauge theory with the NJL interaction included using Witten's multi-trace prescription. We study the behaviour of the mesonic spectrum as a function of the NJL coupling and the ratio of the UV cut off scale to the dynamical scale of the gauge theory.

  16. Quark-Antiquark and Diquark Condensates in Vacuum in a 2D Two-Flavor Gross-Neveu Model

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bang-Rong

    2007-01-01

    The analysis based on the renormalized effective potential indicates that, similar to in the 4D two-flavor Nambu-Jona-Lasinio (NJL) model, in a 2D two-flavor Gross-Neveu model, the interplay between the quark-antiquark and the diquark condensates in vacuum also depends on Gs/Hs, the ratio of the coupling constants in scalar quark antiquark and scalar diquark channel. Only the pure quark-antiquark condensates exist if Gs/Hs > 2/3, which is just the ratio of the color numbers of the quarks participating in the diquark and quark-antiquark condensates. The two condensates will coexist if 0 < Gs/Hs < 2/3. However, different from the 4D NJL model, the pure diquark condensates arise only at Gs/Hs = 0 and are not in a possibly finite region of Gs/Hs below 2/3.

  17. Particle formation and ordering in strongly correlated fermionic systems: Solving a model of quantum chromodynamics

    Science.gov (United States)

    Azaria, P.; Konik, R. M.; Lecheminant, P.; Pálmai, T.; Takács, G.; Tsvelik, A. M.

    2016-08-01

    In this paper we study a (1 +1 )-dimensional version of the famous Nambu-Jona-Lasinio model of quantum chromodynamics (QCD2) both at zero and at finite baryon density. We use nonperturbative techniques (non-Abelian bosonization and the truncated conformal spectrum approach). When the baryon chemical potential, μ , is zero, we describe the formation of fermion three-quark (nucleons and Δ baryons) and boson (two-quark mesons, six-quark deuterons) bound states. We also study at μ =0 the formation of a topologically nontrivial phase. When the chemical potential exceeds the critical value and a finite baryon density appears, the model has a rich phase diagram which includes phases with a density wave and superfluid quasi-long-range (QLR) order, as well as a phase of a baryon Tomonaga-Luttinger liquid (strange metal). The QLR order results in either a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).

  18. Particle Formation and Ordering in Strongly Correlated Fermionic Systems: Solving a Model of Quantum Chromodynamics

    CERN Document Server

    Azaria, P; Lecheminant, Ph; Palmai, T; Takacs, G; Tsvelik, A M

    2016-01-01

    In this paper we study a (1+1)-dimensional version of the famous Nambu-Jona-Lasinio model of Quantum Chromodynamics (QCD2) both at zero and finite matter density. We use non-perturbative techniques (non-Abelian bosonization and Truncated Conformal Space Approach). At zero density we describe a formation of fermion three-quark (nucleons and $\\Delta$-baryons) and boson (two-quark mesons, six-quark deuterons) bound states and also a formation of a topologically nontrivial phase. At finite matter density, the model has a rich phase diagram which includes phases with density wave and superfluid quasi-long-range (QLR) order and also a phase of a baryon Tomonaga-Luttinger liquid (strange metal). The QLR order results as a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).

  19. Is a generalized NJL model the effective action of massless QCD?

    CERN Document Server

    de Oca, Alejandro Cabo Montes

    2015-01-01

    A local and gauge invariant alternative version of QCD for massive fermions introduced in previous works, is considered here to just propose a theory which includes Nambu-Jona-Lasinio (NJL) terms in its defining action in a renormalizable form. The Lagrangian includes a special kind of new vertices which at first sight, look as breaking power counting renormalizability. However, these terms also modify the quark propagators, to become more decreasing that the Dirac propagator at large momenta, indicating that the theory is renormalizable. Therefore, it follows the surprising conclusion that the added NJL four fermions terms does not break renormalizability. The approach, can also be interpreted as a slightly generalized renormalization procedure for massless QCD, which seems able to incorporate the mass generating properties for the quarks of the NJL model, in a renormalizable way. The structure of the free propagator, given by the substraction between a massive and a massless Dirac one in the Lee-Wick form, ...

  20. Chiral density wave versus pion condensation in the 1+1 dimensional NJL model

    CERN Document Server

    Adhikari, Prabal

    2016-01-01

    In this paper, we study the possibility of an inhomogeneous quark condensate in the 1+1 dimensional Nambu-Jona-Lasinio model in the large-$N_c$ limit at finite temperature $T$ and quark chemical potential $\\mu$ using dimensional regularization. The phase diagram in the $\\mu$--$T$ plane is mapped out. At zero temperature, an inhomogeneous phase with a chiral-density wave exists for all values of $\\mu>\\mu_c$. Performing a Ginzburg-Landau analysis, we show that in the chiral limit, the critical point and the Lifschitz point coincide. We also consider the competition between a chiral-density wave and a constant pion condensate at finite isospin chemical potential $\\mu_I$. The phase diagram in the $\\mu_I$--$\\mu$ plane is mapped out and shows a rich phase structure.

  1. The effect of the chiral chemical potential on the chiral phase transition in the NJL model with different regularization schemes

    CERN Document Server

    Yu, Lang; Huang, Mei

    2015-01-01

    We study the chiral phase transition in the presence of the chiral chemical potential $\\mu_5$ using the two-flavor Nambu--Jona-Lasinio model. In particular, we analyze the reason why one can obtain two opposite behaviors of the chiral critical temperature as a function of $\\mu_5$ in the framework of different regularization schemes. We compare the modifications of the chiral condensate and the critical temperature due to $\\mu_5$ in different regularization schemes, analytically and numerically. Finally, we find that, for the conventional hard-cutoff regularization scheme, the increasing dependence of the critical temperature on the chiral chemical potential is an artifact, which is caused by the fact that it does not include complete contribution from the thermal fluctuations. When the thermal contribution is fully taken into account, the chiral critical temperature should decrease with $\\mu_5$.

  2. Z(3) metastable states in Polyakov Quark Meson model

    CERN Document Server

    Mishra, Hiranmaya

    2016-01-01

    We study the existence of Z(3) metastable states in the presence of the dynamical quarks within the ambit of Polyakov quark meson (PQM) model. Within the parameters of the model, it is seen that for temperatures $T_m$ greater than the chiral transition temperature $T_c$, Z(3) metastable states exist ( $T_{m} \\sim 310$ MeV at zero chemical potential). At finite chemical potential $T_m$ is larger than the same at vanishing chemical potential. We also observe a shift of ($\\sim 5^\\circ$) in the phase of the metastable vacua at zero chemical potential. The energy density difference between true and Z(3) metastable vacua is very large in this model. This indicates a strong explicit symmetry breaking effect due to quarks in PQM model. We compare this explicit symmetry breaking in PQM model with small explicit symmetry breaking as a linear term in Polyakov loop added to the Polyakov loop potential. We also study about the possibility of domain growth in a quenched transition to QGP in relativistic heavy ion collision...

  3. Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model

    CERN Document Server

    Megias, E; Salcedo, L L

    2013-01-01

    Based on first principle QCD arguments, it has been argued in arXiv:1204.2424[hep-ph] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop hep-ph/0412308, hep-ph/0607338. The existence of exotic states in the spectrum is discussed.

  4. Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model *,**

    Directory of Open Access Journals (Sweden)

    Megías E.

    2014-03-01

    Full Text Available Based on first principle QCD arguments, it has been argued in [1] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop [2, 3]. The existence of exotic states in the spectrum is discussed.

  5. The QCD phase diagram in the presence of an external magnetic field: the role of the inverse magnetic catalysis

    CERN Document Server

    Ferreira, Márcio; Providência, Constança

    2015-01-01

    The effect of an external magnetic field in QCD phase diagram, namely, in the the location of the critical end point (CEP) is investigated. Using the 2+1 flavor Nambu--Jona-Lasinio model with Polyakov loop, it is shown that when an external magnetic field is applied its effect on the CEP depends on the strength of the coupling. If the coupling depends on the magnetic field, allowing for inverse magnetic catalysis, the CEP moves to lower chemical potentials eventually disappearing, and the chiral restoration phase transition is always of first order.

  6. Critical end point in the presence of a chiral chemical potential

    Science.gov (United States)

    Cui, Z.-F.; Cloët, I. C.; Lu, Y.; Roberts, C. D.; Schmidt, S. M.; Xu, S.-S.; Zong, H.-S.

    2016-10-01

    A class of Polyakov-loop-modified Nambu-Jona-Lasinio models has been used to support a conjecture that numerical simulations of lattice-regularized QCD defined with a chiral chemical potential can provide information about the existence and location of a critical end point in the QCD phase diagram drawn in the plane spanned by baryon chemical potential and temperature. That conjecture is challenged by conflicts between the model results and analyses of the same problem using simulations of lattice-regularized QCD (lQCD) and well-constrained Dyson-Schwinger equation (DSE) studies. We find the conflict is resolved in favor of the lQCD and DSE predictions when both a physically motivated regularization is employed to suppress the contribution of high-momentum quark modes in the definition of the effective potential connected with the Polyakov-loop-modified Nambu-Jona-Lasinio models and the four-fermion coupling in those models does not react strongly to changes in the mean field that is assumed to mock-up Polyakov-loop dynamics. With the lQCD and DSE predictions thus confirmed, it seems unlikely that simulations of lQCD with μ5>0 can shed any light on a critical end point in the regular QCD phase diagram.

  7. From Chiral quark dynamics with Polyakov loop to the hadron resonance gas model

    CERN Document Server

    Arriola, E Ruiz; Salcedo, L L

    2012-01-01

    Chiral quark models with Polyakov loop at finite temperature have been often used to describe the phase transition. We show how the transition to a hadron resonance gas is realized based on the quantum and local nature of the Polyakov loop.

  8. Extended Nambu models: Their relation to gauge theories

    Science.gov (United States)

    Escobar, C. A.; Urrutia, L. F.

    2017-05-01

    Yang-Mills theories supplemented by an additional coordinate constraint, which is solved and substituted in the original Lagrangian, provide examples of the so-called Nambu models, in the case where such constraints arise from spontaneous Lorentz symmetry breaking. Some explicit calculations have shown that, after additional conditions are imposed, Nambu models are capable of reproducing the original gauge theories, thus making Lorentz violation unobservable and allowing the interpretation of the corresponding massless gauge bosons as the Goldstone bosons arising from the spontaneous symmetry breaking. A natural question posed by this approach in the realm of gauge theories is to determine under which conditions the recovery of an arbitrary gauge theory from the corresponding Nambu model, defined by a general constraint over the coordinates, becomes possible. We refer to these theories as extended Nambu models (ENM) and emphasize the fact that the defining coordinate constraint is not treated as a standard gauge fixing term. At this level, the mechanism for generating the constraint is irrelevant and the case of spontaneous Lorentz symmetry breaking is taken only as a motivation, which naturally bring this problem under consideration. Using a nonperturbative Hamiltonian analysis we prove that the ENM yields the original gauge theory after we demand current conservation for all time, together with the imposition of the Gauss laws constraints as initial conditions upon the dynamics of the ENM. The Nambu models yielding electrodynamics, Yang-Mills theories and linearized gravity are particular examples of our general approach.

  9. Chiral phase transition from string theory.

    Science.gov (United States)

    Parnachev, Andrei; Sahakyan, David A

    2006-09-15

    The low energy dynamics of a certain D-brane configuration in string theory is described at weak t'Hooft coupling by a nonlocal version of the Nambu-Jona-Lasinio model. We study this system at finite temperature and strong t'Hooft coupling, using the string theory dual. We show that for sufficiently low temperatures chiral symmetry is broken, while for temperatures larger then the critical value, it gets restored. We compute the latent heat and observe that the phase transition is of the first order.

  10. Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model ***

    Science.gov (United States)

    Megías, E.; Ruiz Arriola, E.; Salcedo, L. L.

    2014-03-01

    Based on first principle QCD arguments, it has been argued in [1] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop [2, 3]. The existence of exotic states in the spectrum is discussed. Presented by E. Megías at the International Nuclear Physics Conference INPC 2013, 2-7 June 2013, Firenze, Italy.Supported by Plan Nacional de Altas Energías (FPA2011-25948), DGI (FIS2011-24149), Junta de Andalucía grant FQM-225, Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042), Spanish MINECO's Centro de Excelencia Severo Ochoa Program grant SEV-2012-0234, and the Juan de la Cierva Program.

  11. Model of Polyakov duality: String field theory Hamiltonians from Yang-Mills theories

    Science.gov (United States)

    Periwal, Vipul

    2000-08-01

    Polyakov has conjectured that Yang-Mills theory should be equivalent to a noncritical string theory. I point out, based on the work of Marchesini, Ishibashi, Kawai and collaborators, and Jevicki and Rodrigues, that the loop operator of the Yang-Mills theory is the temporal gauge string field theory Hamiltonian of a noncritical string theory. The consistency condition of the string interpretation is the zig-zag symmetry emphasized by Polyakov. I explicitly show how this works for the one-plaquette model, providing a consistent direct string interpretation of the unitary matrix model for the first time.

  12. Vector interaction enhanced bag model for astrophysical applications

    CERN Document Server

    Klahn, Thomas

    2015-01-01

    For quark matter studies in astrophysics the thermodynamic bag model (tdBAG) has been widely used. Despite its success it fails to account for various phenomena expected from Quantum-Chromo-Dynamics (QCD). We suggest a straightforward extension of tdBAG in order to take the dynamical breaking of chiral symmetry and the influence of vector interactions explicitly into account. As for tdBAG the model mimics confinement in a phenomenological approach. It is based on an analysis of the Nambu--Jona-Lasinio (NJL) model at finite density. Furthermore, we demonstrate how NJL and bag models in this regime follow from the more general and QCD based framework of Dyson-Schwinger (DS) equations in medium by assuming a simple gluon contact interaction. Based on our simple and novel model, we construct quark hadron hybrid equations of state (EoS) and study systematically chiral and deconfinement phase transitions, the appearance of $s$-quarks and the role of vector interaction. We further study these aspects for matter in b...

  13. Particle Density in Zero Temperature Symmetry Restoring Phase Transitions in Four-Fermion Interaction Models

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bang-Rong

    2004-01-01

    By means of critical behaviors of the dynamical fermion mass in four-fermion interaction models, we show by explicit calculations that when T = 0 the particle density will have a discontinuous jumping across the critical chemical potential μc in 2D and 3D Gross-Neveu (GN) model and these physically explain the first-order feature of the corresponding symmetry restoring phase transitions. For the second-order phase transitions in the 3D GN model when T → 0 and in 4D Nambu-Jona-Lasinio (NJL) model when T = 0, it is proven that the particle density itself will be continuous across μc but its derivative over the chemical potential μ will have a discontinuous jumping. The results give a physical explanation of implications of the tricritical point (T, μ) = (0,μc) in the 3D GN model. The discussions also show effectiveness of the critical analysis approach of phase transitions.

  14. Inhomogeneous phases in the quark-meson model with vacuum fluctuations

    CERN Document Server

    Carignano, Stefano; Schaefer, Bernd-Jochen

    2014-01-01

    Inhomogeneous chiral-symmetry breaking phases at non-vanishing chemical potential and temperature are studied within a two-flavor quark-meson model in the chiral limit. The analysis is performed beyond the standard mean-field approximation by taking into account the Dirac-sea contributions of the quarks. Compared with the case where the Dirac sea is neglected, we find that the inhomogeneous phase shrinks, but in general does not disappear. It is shown within a Ginzburg-Landau analysis that the Lifshitz point of the inhomogeneous phase coincides with the tricritical point if the ratio between sigma-meson and constituent quark mass in vacuum is chosen to be $m_\\sigma/M = 2$, corresponding to the fixed mass ratio in the Nambu--Jona-Lasinio model. In the present model, however, this ratio can be varied, offering the possibility to separate the two points. This is confirmed by our numerical calculations, which demonstrate a strong sensitivity of the size of the inhomogeneous phase on $m_\\sigma$. Finally, we uncove...

  15. Quark-Antiquark and Diquark Condensates in Vacuum in Two-Flavor Four-Fermion Interaction Models with Any Color Number Nc

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bang-Rong

    2009-01-01

    The color number No-dependence of the interplay between quark-antiquark condensates and diquark condensates in vacuum in two-flavor four-fermion interaction models is researched. The results show that the Gs-Hs (the coupling constant of scalar (qq)2-scalar (qq)2 channel) phase diagrams will be qualitatively consistent with the case of Nc = 3 as Nc varies in 4D Nambu-Jona-Lasinio model and 2D Gross-Neveu (GN) model. However, in 3D GN model, the behavior of the Gs-Hp (the coupling constant of pseudoscalar (qq)2 channel) phase diagram will obviously depend on No. The known characteristic that a 3D GN model does not have the coexistence phase of the eondensates and is proven to appear only in the ease of Nc≤ 4. In all the models, the regions occupied by the phases containing the diquark condensates in corresponding phase diagrams will gradually decrease as Nc grows up and finally go to zero if Nc →∞, i.e. in this limit only the pure phase could exist.

  16. Quark-Antiquark and Diquark Condensates in Vacuum in a 2D Two-Flavor Gross-Neveu Model

    CERN Document Server

    Bang-Rong, Z

    2007-01-01

    The analysis based on the renormalized effective potential indicates that, similar to in the 4D two-flavor Nambu-Jona-Lasinio (NJL) model, in a 2D two-flavor Gross-Neveu model, the interplay between the quark-antiquark and the diquark condensates in vacuum also depends on $G_S/H_S$, the ratio of the coupling constants in scalar quark-antiquark and scalar diquark channel. Only the pure quark-antiquark condensates exist if $G_S/H_S>2/3$ which is just the ratio of the color numbers of the quarks participating in the diquark and quark-antiquark condensates. The two condensates will coexist if $0model, the pure diquark condensates arise only at $G_S/H_S=0$ and are not in a possibly finite region of $G_S/H_S$ below 2/3.

  17. Bounds on quantum gravity parameter from the $SU(2)$ NJL effective model of QCD

    CERN Document Server

    Nozari, K; Gorji, M A

    2015-01-01

    Existence of a minimal measurable length, as an effective cutoff in the ultraviolet regime, is a common feature of all approaches to the quantum gravity proposal. It is widely believed that this length scale will be of the order of the Planck length $\\lambda=\\lambda_0\\,l_{_{\\rm Pl}}$, where $\\lambda_0\\sim{\\mathcal O}(1)$ is a dimensionless parameter that should be fixed only by the experiments. This issue can be taken into account through the deformed momentum spaces with compact topologies. In this paper, we consider minimum length effects on the physical quantities related to three parameters of the $SU(2)$ Nambu-Jona-Lasinio effective model of QCD by means of the deformed measure which is defined on compact momentum space with ${\\mathbf S}^3$ topology. This measure is suggested by the doubly special relativity theories, Snyder deformed spaces, and the deformed algebra that is obtained in the light of the stability theory of Lie algebras. Using the current experimental data of the particle physics collabora...

  18. Polyakov-Quark-Meson-Diquark Model for two-color QCD

    CERN Document Server

    Strodthoff, Nils

    2013-01-01

    We present an update on the phase diagram of two-color QCD from a chiral effective model approach based on a quark-meson-diquark model using the Functional Renormalization Group (FRG). We discuss the impact of perturbative UV contributions, the inclusion of gauge field dynamics via a phenomenological Polyakov loop potential, and the impact of matter backcoupling on the gauge sector. The corresponding phase diagram including these effects is found to be in qualitative agreement with recent lattice investigations.

  19. Non-perturbative analysis of the spectrum of meson resonances in an ultraviolet-complete composite-Higgs model

    CERN Document Server

    Bizot, Nicolas; Knecht, Marc; Kneur, Jean-Loïc

    2016-01-01

    We consider a vector-like gauge theory of fermions that confines at the multi-TeV scale, and that realizes the Higgs particle as a composite Goldstone boson. The weak interactions are embedded in the unbroken subgroup $Sp(4)$ of a spontaneously broken $SU(4)$ flavour group. The meson resonances appear as poles in the two-point correlators of fermion bilinears, and include the Goldstone bosons plus a massive pseudoscalar $\\eta'$, as well as scalars, vectors and axial vectors. We compute the mass spectrum of these mesons, as well as their decay constants, in the chiral limit, in the approximation where the hypercolour $Sp(2N)$ dynamics is described by four-fermion operators. This approach generalises the Nambu-Jona Lasinio model for QCD, and it amounts to the resummation of leading diagrams in the $1/N$ expansion. We find that the spin-one states lie beyond the LHC reach, while spin-zero electroweak-singlet states may be as light as the Goldstone-boson decay constant, $f\\sim 1$ TeV. We also confront our results...

  20. Polyakov SU(3) extended linear $\\sigma$-model: Sixteen mesonic states in chiral phase-structure

    CERN Document Server

    Tawfik, Abdel Nasser

    2014-01-01

    The derivative of the grand potential in mean field approximation, non-strange and strange condensates and deconfinement phase-transition in thermal and dense hadronic medium are verified in extended SU(3) linear sigma-model (eLSM). In determining the chiral phase-transition, the chiral condensates sigma_x and sigma_y are analysed. The chiral mesonic phase-structures in temperature- and density-dependence are taken as free parameters to be fitted. These parameters are classified corresponding to scalar meson nonets; (pseudo)-scalar and (axial)-vector. For deconfinement phase-transition, effective Polyakov loop-potentials phi and phi^* are utilized. We investigated the in-medium effects on the masses of sixteen mesonic states states. The results are presented for two different forms for the effective Polyakov loop-potential and compared with other models with and without anomalous terms. The Polyakov loop potential in LSM has considerable effects on the chiral phase-transition in meson masses so that the resto...

  1. SU(3) Polyakov Linear Sigma-Model in an External Magnetic Field

    CERN Document Server

    Tawfik, Abdel Nasser

    2014-01-01

    In the present work, we analyse the effects of an external magnetic field on the chiral critical temperature $T_c$ of strongly interacting matter. In doing this, we can characterize the magnetic properties of the quantum chromodynamics (QCD) strong interacting matter, the quark-gluon plasma (QGP). We investigate this in the framework of the SU(3) Polyakov linear sigma-model (PLSM). To this end, we implement two approaches representing two systems, in which the Polyakov-loop potential added to PLMS either renormalized or non-normalized. The effects of Landau quantization on the strongly interacting matter is conjectures to reduce the electromagnetic interactions between quarks. In this case, the color interactions will be dominant and increasing, which - in turn - can be achieved by increasing of the Polyakov-loop fields. Obviously, each of them equips us with a different understanding about the critical temperature under the effect of an external magnetic field. In both systems, we obtain a paramagnetic respo...

  2. SU(3) Polyakov linear-σ model in an external magnetic field

    Science.gov (United States)

    Tawfik, Abdel Nasser; Magdy, Niseem

    2014-07-01

    In the present work, we analyze the effects of an external magnetic field on the chiral critical temperature Tc of strongly interacting matter. In doing this, we can characterize the magnetic properties of the quantum chromodynamics (QCD) strongly interacting matter, the quark-gluon plasma (QGP). We investigate this in the framework of the SU(3) Polyakov linear sigma model (PLSM). To this end, we implement two approaches representing two systems, in which the Polyakov-loop potential added to PLSM is either renormalized or non-normalized. The effects of Landau quantization on the strongly interacting matter are conjectured to reduce the electromagnetic interactions between quarks. In this case, the color interactions will be dominant and increasing, which in turn can be achieved by increasing the Polyakov-loop fields. Obviously, each of them equips us with a different understanding about the critical temperature under the effect of an external magnetic field. In both systems, we obtain a paramagnetic response. In one system, we find that Tc increases with increasing magnetic field. In the other one, Tc significantly decreases with increasing magnetic field.

  3. Z_3 Polyakov Loop Models and Inverse Monte-Carlo Methods

    CERN Document Server

    Wozar, Christian; Uhlmann, Sebastian; Wipf, Andreas; Heinzl, Thomas

    2007-01-01

    We study effective Polyakov loop models for SU(3) Yang-Mills theory at finite temperature. A comprehensive mean field analysis of the phase diagram is carried out and compared to the results obtained from Monte-Carlo simulations. We find a rich phase structure including ferromagnetic and antiferromagnetic phases. Due to the presence of a tricritical point the mean field approximation agrees very well with the numerical data. Critical exponents associated with second-order transitions coincide with those of the Z_3 Potts model. Finally, we employ inverse Monte-Carlo methods to determine the effective couplings in order to match the effective models to Yang-Mills theory.

  4. Wilson Fermions with Four Fermion Interactions

    DEFF Research Database (Denmark)

    Rantaharju, Jarno; Drach, Vincent; Hietanen, Ari;

    2015-01-01

    We present a lattice study of a four fermion theory, known as Nambu Jona-Lasinio (NJL) theory, via Wilson fermions. Four fermion interactions naturally occur in several extensions of the Standard Model as a low energy parameterisation of a more fundamental theory. In models of dynamical electrowe...

  5. Towards LHC physics with nonlocal Standard Model

    OpenAIRE

    Tirthabir Biswas; Nobuchika Okada

    2015-01-01

    We take a few steps towards constructing a string-inspired nonlocal extension of the Standard Model. We start by illustrating how quantum loop calculations can be performed in nonlocal scalar field theory. In particular, we show the potential to address the hierarchy problem in the nonlocal framework. Next, we construct a nonlocal abelian gauge model and derive modifications of the gauge interaction vertex and field propagators. We apply the modifications to a toy version of the nonlocal Stan...

  6. Momentum Dependent Vertices $\\sigma \\gamma \\gamma$, $\\sigma \\rho \\gamma$ and $\\sigma \\rho \\rho$ : The NJL Scalar Hidden by Chiral Symmetry

    OpenAIRE

    Bajc, B.; Blin, A. H.; Hiller, B.; Nemes, M. C.; Rosina, M.

    1994-01-01

    We calculate the momentum dependence of three particle vertices $\\sigma \\gamma \\gamma$, $\\sigma \\rho \\gamma$ and $\\sigma \\rho \\rho$ in the context of a Nambu Jona Lasinio type model. We show how they influence the processes $\\gamma \\gamma \\rightarrow \\sigma \\rightarrow \\pi \\pi$, $\\rho \\rightarrow \\gamma \\sigma$ and $\\gamma \\gamma \\rightarrow \\rho \\rho$ and how chiral symmetry shadows the presence of the $\\sigma$.

  7. How neutron stars constrain the nuclear equation of state

    CERN Document Server

    Thomas, Hell; Weise, Wolfram

    2013-01-01

    Recent neutron star observations set new constraints for the equation of state of baryonic matter. A chiral effective field theory approach is used for the description of neutron-dominated nuclear matter present in the outer core of neutron stars. Possible hybrid stars with quark matter in the inner core are discussed using a three-flavor Nambu--Jona-Lasinio model.

  8. Path integral approach to two-dimensional QCD in the light-front frame

    Energy Technology Data Exchange (ETDEWEB)

    Gaete, P. (Instituto de Fisica, Universidade Federal do Rio de Janeiro, C.P. 68528, BR-21945, Rio de Janeiro (Brazil)); Gamboa, J. (Fachbereich 7 Physik, Universitaet Siegen, Siegen, D-57068 (Germany)); Schmidt, I. (Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile))

    1994-05-15

    Two-dimensional quantum chromodynamics in the light-front frame is studied following Hamiltonian methods. The theory is quantized using the path integral formalism and an effective theory similar to the Nambu--Jona-Lasinio model is obtained. Confinement in two dimensions is derived by analyzing directly the constraints in the path integral.

  9. Analysis of the hadronic light-by-light contributions to the muon g - 2

    NARCIS (Netherlands)

    Bijnens, Johan; Pallante, Elisabetta; Prades, Joaquim

    1996-01-01

    We calculate the hadronic light-by-light contributions to the muon g - 2. We use both 1/Nc and chiral counting to organize the calculation. Then we calculate the leading and next-to-leading order in the 1/Nc expansion low energy contributions using the Extended Nambu-Jona-Lasinio model as hadronic m

  10. Effective action approach to dynamical generation of fermion mixing

    CERN Document Server

    Blasone, Massimo; Smaldone, Luca

    2016-01-01

    In this paper we discuss a mechanism for the dynamical generation of flavor mixing, in the framework of the Nambu--Jona Lasinio model. Our approach is illustrated both with the conventional operatorial formalism and with functional integral and ensuing one-loop effective action. The results obtained are briefly discussed.

  11. Influence of the vector interaction and an external magnetic field on the isentropes near the chiral critical end point

    CERN Document Server

    Costa, Pedro

    2016-01-01

    The location of the critical end point (CEP) and the isentropic trajectories in the QCD phase diagram are investigated. We use the (2+1) Nambu$-$Jona-Lasinio model with the Polyakov loop coupling for different scenarios, namely by imposing zero strange quark density, which is the case in the ultra relativistic heavy-ion collisions, and $\\beta$-equilibrium. The influence of strong magnetic fields and of the vector interaction on the isentropic trajectories around the CEP is discussed. It is shown that the vector interaction and the magnetic field, having opposite effects on the first-order transition, affect the isentropic trajectories differently: as the vector interaction increases, the first-order transition becomes weaker and the isentropes become smoother; when a strong magnetic field is considered, the first-order transition is strengthened and the isentropes are pushed to higher temperatures. No focusing of isentropes in region towards the CEP is seen.

  12. The Polyakov Loop of Anti-symmetric Representations as a Quantum Impurity Model

    CERN Document Server

    Mueck, Wolfgang

    2010-01-01

    The Polyakov loop of an operator in the anti-symmetric representation in N=4 SYM theory is calculated, to leading order in 1/N and at large 't Hooft coupling, by solving the saddle point equations of the corresponding quantum impurity model. Agreement is found with previous results from the supergravity dual, which is given by a D5-brane embedded in a Schwarzschild-AdS_5 x S^5 background. It is shown that the azimuth angle, at which the dual D5-brane wraps the S^5, is related to the spectral asymmetry angle in the spectral density associated with the Green's function of the impurity fermions.

  13. SU($4$) Polyakov linear-sigma model at finite temperature and density

    CERN Document Server

    Diab, Abdel Magied; Tawfik, Abdel Nasser; Dahab, Eiman Abou El

    2016-01-01

    In mean-field approximation, the SU($4$) Polyakov linear - sigma model (PLSM) is constructed in order to characterize the quark-hadron phase structure in a wide range of temperatures and densities. The chiral condensates $\\sigma_l$, $\\sigma_s$ and $\\sigma_c$ for light, strange and charm quarks, respectively, and the deconfinement order-parameters $\\phi$ and $\\phi^*$ shall be analyzed at finite temperatures and densities. We conclude that the critical temperatures corresponding to charm condensates are greater than that to strange and light ones, respectively. Thus, the charm condensates are likely not affected by the QCD phase transition. Furthermore, increasing the chemical potentials decreases the corresponding critical temperatures.

  14. Exact Solutions in Nonlocal Linear Models

    OpenAIRE

    Vernov, S. Yu.

    2008-01-01

    A general class of cosmological models driven by a nonlocal scalar field inspired by the string field theory is studied. Using the fact that the considering linear nonlocal model is equivalent to an infinite number of local models we have found an exact special solution of the nonlocal Friedmann equations. This solution describes a monotonically increasing Universe with the phantom dark energy.

  15. Thermodynamics and phase structure of the Polyakov-Quark-Meson model

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Jens [Institut fuer Kernphysik (Theoriezentrum), Technische Universitaet Darmstadt (Germany); ExtreMe Matter Institute EMMI, GSI (Germany); Fraga, Eduardo S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro (Brazil); Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany); Haas, Lisa M.; Pawlowski, Jan M. [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI (Germany); Herbst, Tina K.; Stiele, Rainer [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); Mintz, Bruno W.; Ramos, Rudnei O. [Departamento de Fisica Teorica, Universidade do Estado do Rio de Janeiro (Brazil); Mitter, Mario [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany); Schaefer, Bernd-Jochen [Institut fuer Theoretische Physik, Justus-Liebig-Universitaet Giessen (Germany); Institut fuer Physik, Karl-Franzens-Universitaet Graz (Austria); Schaffner-Bielich, Juergen [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany)

    2014-07-01

    Polyakov-loop extended chiral effective models are important tools to describe the phase structure and thermodynamics of strongly interacting matter. We show that taking into account the backreaction of quarks onto the gauge sector is crucial in such models to achieve results for the order parameters and thermodynamics that are in line with lattice calculations. Achieving a good description of lattice data at zero density, we test the reliability of those models in systems containing other control parameters besides the temperature by confronting its results with lattice data at nonzero isospin. Furthermore, we investigate the phase structure of the three-dimensional T-μ{sub isospin}-μ{sub quark} phase diagram and calculate the surface tension of the first order phase transition at small temperatures and large quark densities.

  16. Phase structure of hadronic and Polyakov-loop extended NJL model at finite isospin density

    CERN Document Server

    Cavagnoli, Rafael; Providência, Constança

    2013-01-01

    It is believed that there exists a rich phase structure of quantum chromodynamics (QCD) at finite temperature and baryon density, namely, the deconfinement process from hadron gas to quark-gluon plasma, the transition from chiral symmetry breaking phase to the symmetry restoration phase, and the color superconductivity at low temperature and high baryon density. In the present work we study the hadron-quark phase transition by investigating the binodal surface and extending it to finite temperature in order to mimic the QCD phase diagram. In order to obtain these conditions we use different models for the two possible phases, namely the quark and hadron phases. The phase separation boundary (binodal) is determined by the Gibbs criteria for phase equilibrium. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Isospin effects appear to be rather significant. The critical endpoint (CEP) and the phase structure are also studied in the Polyakov-loop ...

  17. Towards LHC physics with nonlocal Standard Model

    Directory of Open Access Journals (Sweden)

    Tirthabir Biswas

    2015-09-01

    Full Text Available We take a few steps towards constructing a string-inspired nonlocal extension of the Standard Model. We start by illustrating how quantum loop calculations can be performed in nonlocal scalar field theory. In particular, we show the potential to address the hierarchy problem in the nonlocal framework. Next, we construct a nonlocal abelian gauge model and derive modifications of the gauge interaction vertex and field propagators. We apply the modifications to a toy version of the nonlocal Standard Model and investigate collider phenomenology. We find the lower bound on the scale of nonlocality from the 8 TeV LHC data to be 2.5–3 TeV.

  18. Topological Symmetry, Spin Liquids and CFT Duals of Polyakov Model with Massless Fermions

    Energy Technology Data Exchange (ETDEWEB)

    Unsal, Mithat

    2008-04-30

    We prove the absence of a mass gap and confinement in the Polyakov model with massless complex fermions in any representation of the gauge group. A U(1){sub *} topological shift symmetry protects the masslessness of one dual photon. This symmetry emerges in the IR as a consequence of the Callias index theorem and abelian duality. For matter in the fundamental representation, the infrared limits of this class of theories interpolate between weakly and strongly coupled conformal field theory (CFT) depending on the number of flavors, and provide an infinite class of CFTs in d = 3 dimensions. The long distance physics of the model is same as certain stable spin liquids. Altering the topology of the adjoint Higgs field by turning it into a compact scalar does not change the long distance dynamics in perturbation theory, however, non-perturbative effects lead to a mass gap for the gauge fluctuations. This provides conceptual clarity to many subtle issues about compact QED{sub 3} discussed in the context of quantum magnets, spin liquids and phase fluctuation models in cuprate superconductors. These constructions also provide new insights into zero temperature gauge theory dynamics on R{sup 2,1} and R{sup 2,1} x S{sup 1}. The confined versus deconfined long distance dynamics is characterized by a discrete versus continuous topological symmetry.

  19. Emergence of Yang Mills theory from the Non-Abelian Nambu Model

    CERN Document Server

    Escobar, C A

    2016-01-01

    The equivalence between the Non-Abelian Nambu model (NANM) and Yang Mills theory is proved, after demanding the Gauss laws at some initial time to the first one. Thereby, the Lorentz violation encoded into the constraint that defines the NANM is physically unobservable. As result, the Goldstone bosons in the NANM arising from the spontaneous symmetry breaking can be identified as the standard gauge fields.

  20. A New Model of Nonlocal Modified Gravity

    CERN Document Server

    Dimitrijevic, Ivan; Grujic, Jelena; Rakic, Zoran

    2014-01-01

    We consider a new modified gravity model with nonlocal term of the form $R^{-1} \\mathcal{F}(\\Box) R. $ This kind of nonlocality is motivated by investigation of applicability of a few unusual ans\\"atze to obtain some exact cosmological solutions. In particular, we find attractive and useful quadratic ansatz $\\Box R = q R^{2}.$

  1. Experimental falsification of Leggett's nonlocal variable model.

    Science.gov (United States)

    Branciard, Cyril; Ling, Alexander; Gisin, Nicolas; Kurtsiefer, Christian; Lamas-Linares, Antia; Scarani, Valerio

    2007-11-23

    Bell's theorem guarantees that no model based on local variables can reproduce quantum correlations. Also, some models based on nonlocal variables, if subject to apparently "reasonable" constraints, may fail to reproduce quantum physics. In this Letter, we introduce a family of inequalities, which use a finite number of measurement settings, and which therefore allow testing Leggett's nonlocal model versus quantum physics. Our experimental data falsify Leggett's model and are in agreement with quantum predictions.

  2. On a Nonlocal Damping Model in Ferromagnetism

    Directory of Open Access Journals (Sweden)

    M. Moumni

    2015-01-01

    Full Text Available We consider a mathematical model describing nonlocal damping in magnetization dynamics. The model consists of a modified form of the Landau-Lifshitz-Gilbert (LLG equation for the evolution of the magnetization vector in a rigid ferromagnet. We give a global existence result and characterize the long time behaviour of the obtained solutions. The sensitivity of the model with respect to large and small nonlocal damping parameters is also discussed.

  3. Enforced neutrality and color-flavor unlocking in the three-flavor Polyakov-loop NJL model

    CERN Document Server

    Abuki, H; Gatto, R; Nardulli, G; Ruggieri, M

    2008-01-01

    We study how the charge neutrality affects the phase structure of three-flavor PNJL model. We point out that, within the conventional PNJL model at finite density the color neutrality is missing because the Wilson line serves as an external ``colored'' field coupled to dynamical quarks. In this paper we heuristically assume that the model may still be applicable. To get color neutrality one has then to allow non vanishing color chemical potentials. We study how the quark matter phase diagram in $(T,m_s^2/\\mu)$-plane is affected by imposing neutrality and by including the Polyakov loop dynamics. Although these two effects are correlated in a nonlinear way, the impact of the Polyakov loop turns out to be significant in the $T$ direction, while imposing neutrality brings a remarkable effect in the $m_s^2/\\mu$ direction. In particular, we find a novel unlocking transition, when the temperature is increased, even in the chiral SU(3) limit. We clarify how and why this is possible once the dynamics of the colored Po...

  4. Multi critical point structure for chiral phase transition induce by charge neutrality and vector interaction

    CERN Document Server

    Zhang, Zhao

    2010-01-01

    The combined effect of the repulsive vector interaction and the positive electric chemical potential on the chiral phase transition is investigated by considering neutral color superconductivity. Under the charge-neutrality constraint, the chiral condensate, diquark condensate and quark number densities are obtained in two-plus-one-flavor Nambu-Jona-Lasinio model with the so called Kobayashi-Maskawa-'t Hooft term. We demonstrate that multiple chiral critical-point structures always exist in the Nambu-Jona-Lasinio model within the self-consistent mean-field approximation, and that the number of chiral critical points can vary from zero to four, which is dependent on the magnitudes of vector interaction and the diquark coupling.

  5. Note on Strange Quarks in the Nucleon

    CERN Document Server

    Steininger, K

    1994-01-01

    Scalar matrix elements involving strange quarks are studied in several models. Apart from a critical reexamination of results obtained in the Nambu and Jona-Lasinio model we study a scenario, motivated by instanton physics, where spontaneous chiral symmetry breaking is induced by the flavor-mixing 't Hooft interaction only. We also investigate possible contributions of virtual kaon loops to the strangeness content of the nucleon.

  6. From Inverse to Delayed Magnetic Catalysis in Strong Magnetic Field

    CERN Document Server

    Mao, Shijun

    2016-01-01

    We study magnetic field effect on chiral phase transition in a Nambu--Jona-Lasinio model. In comparison with mean field approximation containing quarks only, including mesons as quantum fluctuations in the model leads to a transition from inverse to delayed magnetic catalysis at finite temperature and delays the transition at finite baryon chemical potential. The location of the critical end point depends on the the magnetic field non-monotonously.

  7. Baryon octet electromagnetic form factors in a confining NJL model

    Directory of Open Access Journals (Sweden)

    Manuel E. Carrillo-Serrano

    2016-08-01

    Full Text Available Electromagnetic form factors of the baryon octet are studied using a Nambu–Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result that rEp

  8. The effective potential of composite fields in weakly coupled QED in a uniform external magnetic field

    CERN Document Server

    Lee, D S; Ng, Y J; Shovkovy, I A

    1999-01-01

    The effective potential for the composite fields responsible for chiral symmetry breaking in weakly coupled QED in a magnetic field is derived. The global minimum of the effective potential is found to acquire a non-vanishing expectation value of the composite fields that leads to generating the dynamical fermion mass by an external magnetic field. The results are compared with those for the Nambu-Jona-Lasinio model.

  9. Meson properties at finite temperature and baryon density

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M.; Klimt, S.; Weise, W. (Inst. of Theoretical Physics, Univ. Regensburg (Germany))

    1992-06-22

    We use the generalized SU(3) version of the Nambu and Jona-Lasinio model to discuss properties of mesons, constituent quarks and vacuum structure as a function of density and temperature in compressed matter. Systematic low-density expansions are derived. In particular, we show that effects due to finite quasi-particle size are important in stabilizing the density and temperature dependence of the pion mass. (orig.).

  10. The Ideal Mixing Departure in Vector Meson Physics

    CERN Document Server

    Epele, L N; Grunfeld, A G

    2002-01-01

    In this work we study the departure for the ideal $\\phi-\\omega$ mixing angle in the frame of the Nambu-Jona-Lasinio model. We have shown that in that context, the flavour symmetry breaking is unable to produce the shifting in the mixing angle. We introduce a nonet symmetry breaking in the neutral vector sector to regulate the non-strange content of the $\\phi$ meson. The phenomenon is well reproduced by our proposal.

  11. Photons emerging as Goldstone bosons from spontaneous Lorentz symmetry breaking: The Abelian Nambu model

    CERN Document Server

    Escobar, C A

    2015-01-01

    After imposing current conservation together with the Gauss law as initial conditions on the Abelian Nambu model, we prove that the resulting theory is equivalent to standard QED in the non-linear gauge $\\left(A_{\\mu }A^{\\mu }-n^{2}M^{2}\\right)=0$, to all orders in perturbation theory. We show this by writing both models in terms of the same variables, which produce identical Feynman rules for the interactions and propagators. A crucial point is to verify that the Faddeev-Popov ghosts arising from the gauge fixing procedure in the QED sector decouple to all orders. We verify this decoupling by following a method like that employed in Yang-Mills theories when investigating the behavior of axial gauges. The equivalence between the two theories supports the idea that gauge particles can be envisaged as the Goldstone bosons originating from spontaneous Lorentz symmetry breaking.

  12. SU(3) Polyakov linear-sigma model: Conductivity and viscous properties of QCD matter in thermal medium

    CERN Document Server

    Tawfik, Abdel Nasser; Hussein, M T

    2016-01-01

    In mean field approximation, the grand canonical potential of SU(3) Polyakov linear-$\\sigma$ model (PLSM) is analysed for chiral phase-transition, $\\sigma_l$ and $\\sigma_s$ and for deconfinement order-parameters, $\\phi$ and $\\phi^*$ of light- and strange-quarks, respectively. Various PLSM parameters are determined from the assumption of global minimization of the real part of the potential. Then, we have calculated the subtracted condensates ($\\Delta_{l,s}$). All these results are compared with recent lattice QCD simulations. Accordingly, essential PLSM parameters are determined. The modelling of the relaxation time is utilized in estimating the conductivity properties of the QCD matter in thermal medium, namely electric [$\\sigma_{el}(T)$] and heat [$\\kappa(T)$] conductivities. We found that the PLSM results on the electric conductivity and on the specific heat agree well with the available lattice QCD calculations. Also, we have calculated bulk and shear viscosities normalized to the thermal entropy, $\\xi/s$...

  13. Polyakov linear SU(3) σ model: Features of higher-order moments in a dense and thermal hadronic medium

    Science.gov (United States)

    Tawfik, A.; Magdy, N.; Diab, A.

    2014-05-01

    In order to characterize the higher-order moments of particle multiplicity, we implement the linear-sigma model with Polyakov-loop correction. We first studied the critical phenomena and estimated some thermodynamic quantities. Then, we compared all these results with first-principle lattice QCD calculations. Then, the extensive study of non-normalized four-moments is followed by investigating their thermal and density dependences. We repeat this for moments normalized to temperature and chemical potential. The fluctuations of the second-order moment are used to estimate the chiral phase transition. Then, we implement all these in mapping out the chiral phase transition, which is compared with the freeze-out parameters estimated from the lattice QCD simulations, and the thermal models are compared with the chiral phase diagram.

  14. Polyakov linear SU(3) sigma model: features of higher order moments in dense and thermal hadronic medium

    CERN Document Server

    Tawfik, A; Diab, A

    2014-01-01

    In order to characterize the higher order moments of the particle multiplicity, we implement the linear-sigma model with Polyakov-loop correction. We first studied the critical phenomena and estimated some thermodynamic quantities. Then, we compared all these results with the first--principle lattice QCD calculations. Then, the extensive study of non-normalized four moments is followed by investigating their thermal and density dependence. We repeat this for moments normalized to temperature and chemical potential. The fluctuations of the second order moment is used to estimate the chiral phase--transition. Then, we implement all these in mapping out the chiral phase transition, which shall be compared with the freeze-out parameters estimated from the lattice QCD simulations and the thermal models are compared with the chiral phase--diagram.

  15. Dynamics in Nonlocal Cosmological Models Derived from String Field Theory

    OpenAIRE

    Joukovskaya, Liudmila

    2007-01-01

    A general class of nonlocal cosmological models is considered. A new method for solving nonlocal Friedmann equations is proposed, and solutions of the Friedmann equations with nonlocal operator are presented. The cosmological properties of these solutions are discussed. Especially indicated is $p$-adic cosmological model in which we have obtained nonsingular bouncing solution and string field theory tachyon model in which we have obtained full solution of nonlocal Friedmann equations with $w=...

  16. Critical endpoint in the presence of a chiral chemical potential

    CERN Document Server

    Cui, Zhu-Fang; Lu, Ya; Roberts, Craig D; Schmidt, Sebastian M; Xu, Shu-Sheng; Zong, Hong-Shi

    2016-01-01

    A class of Polyakov-loop-modified Nambu--Jona-Lasinio (PNJL) models have been used to support a conjecture that numerical simulations of lattice-regularized quantum chromodynamics (QCD) defined with a chiral chemical potential can provide information about the existence and location of a critical endpoint in the QCD phase diagram drawn in the plane spanned by baryon chemical potential and temperature. That conjecture is challenged by conflicts between the model results and analyses of the same problem using simulations of lattice-regularized QCD (lQCD) and well-constrained Dyson-Schwinger equation (DSE) studies. We find the conflict is resolved in favor of the lQCD and DSE predictions when both a physically-motivated regularization is employed to suppress the contribution of high-momentum quark modes in the definition of the effective potential connected with the PNJL models and the four-fermion coupling in those models does not react strongly to changes in the mean-field that is assumed to mock-up Polyakov l...

  17. Phases of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Roessner, Simon

    2009-04-09

    Quantum Chromodynamics (QCD) is the theory of the strong interaction within the Standard Model of elementary particles. Today's research in this area dedicates substantial resources to numeric solutions of the QCD field equations and experimental programs exploring the phases of QCD. This thesis proceeds along a complementary line - that of modelling QCD, with the aim of identifying its dominant degrees of freedom. This is possible by minimally coupling effective potentials for the Polyakov loop to Nambu-Jona-Lasinio models using temporal background fields to model chiral symmetry breaking respecting colour confinement. The fermion sign problem resulting from the minimal coupling is addressed in this work establishing a novel, systematically ordered approach. The modifications to the approximative order parameter of colour confinement, the Polyakov loop, are in direct connection with the fermion sign problem. Furthermore an effective coupling of quark densities of different flavours is induced. This mechanism, most likely also present in QCD, produces finite contributions to flavour off diagonal susceptibilities. Susceptibilities are amongst the most promising physical quantities for the experimental exploration of the phase transition at high temperatures and densities. (orig.)

  18. Nonlocal regularization of abelian models with spontaneous symmetry breaking

    OpenAIRE

    Clayton, M. A.

    2001-01-01

    We demonstrate how nonlocal regularization is applied to gauge invariant models with spontaneous symmetry breaking. Motivated by the ability to find a nonlocal BRST invariance that leads to the decoupling of longitudinal gauge bosons from physical amplitudes, we show that the original formulation of the method leads to a nontrivial relationship between the nonlocal form factors that can appear in the model.

  19. Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

    Directory of Open Access Journals (Sweden)

    Tomoya Hayata

    2015-05-01

    Full Text Available We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement of heavy quarks.

  20. Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

    Energy Technology Data Exchange (ETDEWEB)

    Hayata, Tomoya, E-mail: hayata@riken.jp [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Theoretical Research Division, Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Yamamoto, Arata [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Theoretical Research Division, Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan)

    2015-05-11

    We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement of heavy quarks.

  1. A Generalized Nonlocal Calculus with Application to the Peridynamics Model for Solid Mechanics

    OpenAIRE

    Alali, Bacim; Liu, Kuo; Gunzburger, Max

    2014-01-01

    A nonlocal vector calculus was introduced in [2] that has proved useful for the analysis of the peridynamics model of nonlocal mechanics and nonlocal diffusion models. A generalization is developed that provides a more general setting for the nonlocal vector calculus that is independent of particular nonlocal models. It is shown that general nonlocal calculus operators are integral operators with specific integral kernels. General nonlocal calculus properties are developed, including nonlocal...

  2. Classification of scalar and dyadic nonlocal optical response models

    DEFF Research Database (Denmark)

    Wubs, Martijn

    2015-01-01

    Nonlocal optical response is one of the emerging effects on the nanoscale for particles made of metals or doped semiconductors. Here we classify and compare both scalar and tensorial nonlocal response models. In the latter case the nonlocality can stem from either the longitudinal response...

  3. Nonlocal modeling of granular flows down inclines.

    Science.gov (United States)

    Kamrin, Ken; Henann, David L

    2015-01-07

    Flows of granular media down a rough inclined plane demonstrate a number of nonlocal phenomena. We apply the recently proposed nonlocal granular fluidity model to this geometry and find that the model captures many of these effects. Utilizing the model's dynamical form, we obtain a formula for the critical stopping height of a layer of grains on an inclined surface. Using an existing parameter calibration for glass beads, the theoretical result compares quantitatively to existing experimental data for glass beads. This provides a stringent test of the model, whose previous validations focused on driven steady-flow problems. For layers thicker than the stopping height, the theoretical flow profiles display a thickness-dependent shape whose features are in agreement with previous discrete particle simulations. We also address the issue of the Froude number of the flows, which has been shown experimentally to collapse as a function of the ratio of layer thickness to stopping height. While the collapse is not obvious, two explanations emerge leading to a revisiting of the history of inertial rheology, which the nonlocal model references for its homogeneous flow response.

  4. Classification of scalar and dyadic nonlocal optical response models.

    Science.gov (United States)

    Wubs, M

    2015-11-30

    Nonlocal optical response is one of the emerging effects on the nanoscale for particles made of metals or doped semiconductors. Here we classify and compare both scalar and tensorial nonlocal response models. In the latter case the nonlocality can stem from either the longitudinal response, the transverse response, or both. In phenomenological scalar models the nonlocal response is described as a smearing out of the commonly assumed infinitely localized response, as characterized by a distribution with a finite width. Here we calculate explicitly whether and how tensorial models, such as the hydrodynamic Drude model and generalized nonlocal optical response theory, follow this phenomenological description. We find considerable differences, for example that nonlocal response functions, in contrast to simple distributions, assume negative and complex values. Moreover, nonlocal response regularizes some but not all diverging optical near fields. We identify the scalar model that comes closest to the hydrodynamic model. Interestingly, for the hydrodynamic Drude model we find that actually only one third (1/3) of the free-electron response is smeared out nonlocally. In that sense, nonlocal response is stronger for transverse and scalar nonlocal response models, where the smeared-out fractions are 2/3 and 3/3, respectively. The latter two models seem to predict novel plasmonic resonances also below the plasma frequency, in contrast to the hydrodynamic model that predicts standing pressure waves only above the plasma frequency.

  5. SU(3) Polyakov linear-sigma model: bulk and shear viscosity of QCD matter in finite magnetic field

    CERN Document Server

    Tawfik, Abdel Nasser; Hussein, T M

    2016-01-01

    Due to off-center relativistic motion of the charged spectators and the local momentum-imbalance of the participants, a short-lived huge magnetic field is likely generated, especially in relativistic heavy-ion collisions. In determining the temperature dependence of bulk and shear viscosities of the QCD matter in vanishing and finite magnetic field, we utilize mean field approximation to the SU($3$) Polyakov linear-sigma model (PLSM). We compare between the results from two different approaches; Green-Kubo correlation and Boltzmann master equation with Chapman-Enskog expansion. We find that both approaches have almost identical results, especially in the hadron phase. In the temperature dependence of bulk and shear viscosities relative to thermal entropy at the critical temperature, there is a rapid decrease in the chiral phase-transition and in the critical temperature with increasing magnetic field. As the magnetic field strength increases, a peak appears at the critical temperature ($T_c$). This can be und...

  6. Effect of four-fermion operators on the mass of the composite particles

    CERN Document Server

    Foadi, Roshan

    2016-01-01

    We propose a theoretical framework for evaluating the effect of four-fermion operators on the mass of composite particles in confining strongly-coupled gauge theories. The confining sector is modelled by a non-local Nambu-Jona Lasinio action, whereas the four-fermion operators, arising from a different sector, are local. In order to illustrate the method, we investigate a simple toy model with a global $SU(2)_L\\times SU(2)_R\\to SU(2)_V$ symmetry breaking, and a four-fermion operator breaking $SU(2)_L\\times SU(2)_R$ but preserving $SU(2)_V$. In the particle spectrum we only include the pseudoscalar isospin triplet, that is the pseudo-Nambu-Goldstone bosons associated with chiral symmetry breaking, and the lightest scalar singlet. After checking that the nonlocal model successfully accounts for the experimental results in two-flavour QCD, we investigate the mass spectrum as a function of the four-fermion coupling. For our specific choice of four-fermion operator, we find that the mass of the pseudoscalar triple...

  7. Nonlocal Crowd Dynamics Models for several Populations

    CERN Document Server

    Colombo, Rinaldo M

    2011-01-01

    This paper develops the basic analytical theory related to some recently introduced crowd dynamics models. Where well posedness was known only locally in time, it is here extended to all of $\\reali^+$. The results on the stability with respect to the equations are improved. Moreover, here the case of several populations is considered, obtaining the well posedness of systems of multi-D non-local conservation laws. The basic analytical tools are provided by the classical Kruzkov theory of scalar conservation laws in several space dimensions.

  8. NONLOCAL CROWD DYNAMICS MODELS FOR SEVERAL POPULATIONS

    Institute of Scientific and Technical Information of China (English)

    Rinaldo M. Colombo; Magali Lécureux-Mercier

    2012-01-01

    This paper develops the basic analytical theory related to some recently introduced crowd dynamics models.Where well posedness was known only locally in time,it is here extended to all of R+.The results on the stability with respect to the equations are improved.Moreover,here the case of several populations is considered,obtaining the well posedness of systems of multi-D non-local conservation laws.The basic analytical tools are provided by the classical Kru(z)kov theory of scalar conservation laws in several space dimensions.

  9. A Nonlocal Model for Carbon Nanotubes under Axial Loads

    Directory of Open Access Journals (Sweden)

    Raffaele Barretta

    2013-01-01

    Full Text Available Various beam theories are formulated in literature using the nonlocal differential constitutive relation proposed by Eringen. A new variational framework is derived in the present paper by following a consistent thermodynamic approach based on a nonlocal constitutive law of gradient-type. Contrary to the results obtained by Eringen, the new model exhibits the nonlocality effect also for constant axial load distributions. The treatment can be adopted to get new benchmarks for numerical analyses.

  10. Non-local models for ductile failure

    Science.gov (United States)

    César de Sá, José; Azinpour, Erfan; Santos, Abel

    2016-08-01

    Ductile damage can be dealt with continuous descriptions of material, resorting, for example, to continuous damage mechanic descriptions or micromechanical constitutive models. When it comes to describe material behaviour near and beyond fracture these approaches are no longer sufficient or valid and continuous/discontinuous approaches can be adopted to track fracture initiation and propagation. Apart from more pragmatic solutions like element erosion or remeshing techniques more advanced approaches based on the X-FEM concept, in particular associated with non-local formulations, may be adopted to numerically model these problems. Nevertheless, very often, for practical reasons, some important aspects are somewhat left behind, specially energetic requirements to promote the necessary transition of energy release associated with material damage and fracture energy associated to a crack creation and evolution. Phase-field methods may combine advantages of regularised continuous models by providing a similar description to non-local thermodynamical continuous damage mechanics, as well as, a "continuous" approach to numerically follow crack evolution and branching

  11. Determination of hadron-quark phase transition line from lattice QCD and two-solar-mass neutron star observations

    CERN Document Server

    Sugano, Junpei; Yahiro, Masahiro

    2016-01-01

    We aim at drawing the hadron-quark phase transition line in the QCD phase diagram by using the two phase model (TPM) in which the entanglement Polyakov-loop extended Nambu--Jona-Lasinio (EPNJL) model with vector-type four-quark interaction is used for the quark phase and the relativistic mean field (RMF) model is for the hadron phase. Reasonable TPM is constructed by using lattice QCD data and neutron star observations as reliable constraints. For the EPNJL model, we determine the strength of vector-type four-quark interaction at zero quark chemical potential from lattice QCD data on quark number density normalized by its Stefan-Boltzmann limit. For the hadron phase, we consider three RMF models, NL3, TM1 and model proposed by Maruyama, Tatsumi, Endo and Chiba (MTEC). We find that MTEC is most consistent with the neutron star observations and TM1 is the second best. Assuming that the hadron-quark phase transition occurs in the core of neutron star, we explore the density-dependence of vector-type four-quark i...

  12. Phase diagram of QCD in a magnetic field: A review

    CERN Document Server

    Andersen, Jens O; Tranberg, Anders

    2014-01-01

    We review in detail recent advances in our understanding of the phase structure and the phase transitions of hadronic matter in strong magnetic fields $B$ and zero quark chemical potentials $\\mu_f$. Many aspects of QCD are described using low-energy effective theories and models such as the MIT bag model, the hadron resonance gas model, chiral perturbation theory, the Nambu-Jona-Lasinio (NJL) model, the quark-meson (QM) model and Polyakov-loop extended versions of the NJL and QM models. We critically examine their properties and applications. This includes mean-field calculations as well as approaches beyond the mean-field approximation such as the functional renormalization group (FRG). Renormalization issues are discussed and the influence of the vacuum fluctuations on the chiral phase transition is pointed out. Magnetic catalysis at $T=0$ is covered as well. We discuss recent lattice results for the thermodynamics of nonabelian gauge theories with emphasis on $SU(2)_c$ and $SU(3)_c$. In particular, we focu...

  13. Modulational instability in the nonlocal chi(2)-model

    DEFF Research Database (Denmark)

    Wyller, John Andreas; Krolikowski, Wieslaw; Bang, Ole

    2007-01-01

    We investigate in detail the linear regime of the modulational instability (MI) properties of the plane waves of the nonlocal model for chi((2))- media formulated in Nikolov et al. [N.I. Nikolov, D. Neshev, O. Bang, W.Z. Krolikowski, Quadratic solitons as nonlocal solitons, Phys. Rev. E 68 (2003...... in the parameter space for which a fundamental gain band exists, and regions for which higher order gain bands and modulational stability exist. We also show that the MI analysis for the nonlocal model is applicable in the finite walk-off case. Finally, we show that the plane waves of the nonlocal chi((2))-model...... of the nonlocal chi((2))-model, by using the singular perturbational approach. The other branch of the plane waves (i.e. the nonadiabatic branch or the optical branch) is always modulationally unstable. We compare the MI results for the adiabatic branch with the predictions obtained from the full chi((2))-model...

  14. A nonlocal spatial model for Lyme disease

    Science.gov (United States)

    Yu, Xiao; Zhao, Xiao-Qiang

    2016-07-01

    This paper is devoted to the study of a nonlocal and time-delayed reaction-diffusion model for Lyme disease with a spatially heterogeneous structure. In the case of a bounded domain, we first prove the existence of the positive steady state and a threshold type result for the disease-free system, and then establish the global dynamics for the model system in terms of the basic reproduction number. In the case of an unbound domain, we obtain the existence of the disease spreading speed and its coincidence with the minimal wave speed. At last, we use numerical simulations to verify our analytic results and investigate the influence of model parameters and spatial heterogeneity on the disease infection risk.

  15. A simple nonlocal model for exchange.

    Science.gov (United States)

    Janesko, Benjamin G

    2009-12-21

    This work presents a new nonlocal model for the exchange energy density. The model is obtained from the product of the Kohn-Sham one-particle density matrix used to construct exact [Hartree-Fock-like (HF)] exchange, and an approximate density matrix used to construct local spin-density approximation (LSDA) exchange. The proposed exchange energy density has useful formal properties, including correct spin and coordinate scaling and the correct uniform limit. It can readily be evaluated in finite basis sets, with a computational scaling intermediate between HF exchange and semilocal quantities such as the noninteracting kinetic energy density. Applications to representative systems indicate that its properties are typically intermediate between HF and LSDA exchange, and often similar to global hybrids of HF and LSDA exchange. The model is proposed as a novel "Rung 3.5" ingredient for constructing approximate exchange-correlation functionals.

  16. Influence of pions on the hadron-quark phase transition

    CERN Document Server

    Lourenço, O; Frederico, T; Delfino, A; Malheiro, M

    2013-01-01

    In this work we present the features of the hadron-quark phase transition diagrams in which the pions are included in the system. To construct such diagrams we use two different models in the description of the hadronic and quark sectors. At the quark level, we consider two distinct parametrizations of the Polyakov-Nambu-Jona-Lasinio (PNJL) models. In the hadronic side, we use a well known relativistic mean-field (RMF) nonlinear Walecka model. We show that the effect of the pions on the hadron-quark phase diagrams is to move the critical end point (CEP) of the transitions lines. Such an effect also depends on the value of the critical temperature (T_0) in the pure gauge sector used to parametrize the PNJL models. Here we treat the phase transitions using two values for T_0, namely, T_0 = 270 MeV and T_0 = 190 MeV. The last value is used to reproduce lattice QCD data for the transition temperature at zero chemical potential.

  17. Probing the hadron-quark mixed phase at high isospin and baryon density. Sensitive observables

    Energy Technology Data Exchange (ETDEWEB)

    Di Toro, Massimo; Greco, Vincenzo [INFN-Laboratori Nazionali del Sud, Catania (Italy); University of Catania, Physics and Astronomy Dept., Catania (Italy); Colonna, Maria [INFN-Laboratori Nazionali del Sud, Catania (Italy); Shao, Guo-Yun [Xi' an Jiaotong University, Department of Applied Physics, Xi' an (China)

    2016-08-15

    We discuss the isospin effect on the possible phase transition from hadronic to quark matter at high baryon density and finite temperatures. The two-Equation of State (Two-EoS) model is adopted to describe the hadron-quark phase transition in dense matter formed in heavy-ion collisions. For the hadron sector we use Relativistic Mean-Field (RMF) effective models, already tested on heavy-ion collision (HIC). For the quark phase we consider various effective models, the MIT-Bag static picture, the Nambu-Jona-Lasinio (NJL) approach with chiral dynamics and finally the NJL coupled to the Polyakov-loop field (PNJL), which includes both chiral and (de)confinement dynamics. The idea is to extract mixed phase properties which appear robust with respect to the model differences. In particular we focus on the phase transitions of isospin asymmetric matter, with two main results: (i) an earlier transition to a mixed hadron-quark phase, at lower baryon density/chemical potential with respect to symmetric matter; (ii) an ''Isospin Distillation'' to the quark component of the mixed phase, with predicted effects on the final hadron production. Possible observation signals are suggested to probe in heavy-ion collision experiments at intermediate energies, in the range of the NICA program. (orig.)

  18. Influence of pions on the hadron-quark phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, O.; Dutra, M.; Frederico, T.; Malheiro, M. [Departamento de Fisica, Instituto Tecnologico de Aeronautica-CTA, 12228-900, Sao Jose dos Campos (Brazil); Delfino, A. [Instituto de Fisica, Universidade Federal Fluminense, Av. Litoranea s/n, 24210-150, Boa Viagem, Niteroi RJ (Brazil)

    2013-05-06

    In this work we present the features of the hadron-quark phase transition diagrams in which the pions are included in the system. To construct such diagrams we use two different models in the description of the hadronic and quark sectors. At the quark level, we consider two distinct parametrizations of the Polyakov-Nambu-Jona-Lasinio (PNJL) models. In the hadronic side, we use a well known relativistic mean-field (RMF) nonlinear Walecka model. We show that the effect of the pions on the hadron-quark phase diagrams is to move the critical end point (CEP) of the transitions lines. Such an effect also depends on the value of the critical temperature (T{sub 0}) in the pure gauge sector used to parametrize the PNJL models. Here we treat the phase transitions using two values for T{sub 0}, namely, T{sub 0}= 270 MeV and T{sub 0}= 190 MeV. The last value is used to reproduce lattice QCD data for the transition temperature at zero chemical potential.

  19. Influence of vector interactions on the hadron-quark/gluon phase transition

    CERN Document Server

    Shao, G Y; Di Toro, M; Liu, B; Matera, F

    2012-01-01

    The hadron-quark/gluon phase transition is studied in the two-phase model. As a further study of our previous work, both the isoscalar and isovector vector interactions are included in the Polyakov loop modified Nambu--Jona-Lasinio model (PNJL) for the quark phase. The relevance of the exchange (Fock) terms is stressed and suitably accounted for. The calculation shows that the isovector vector interaction delays the phase transition to higher densities and the range of the mixed phase correspondingly shrinks. Meanwhile the asymmetry parameter of quark matter in the mixed phase decreases with the strengthening of this interaction channel. This leads to some possible observation signals being weakened, although still present. We show that these can be rather general effects of a repulsion in the quark phase due to the symmetry energy. This is also confirmed by a simpler calculation with the MIT--Bag model. However, the asymmetry parameter of quark matter is slightly enhanced with the inclusion of the isoscalar ...

  20. Dynamical Generation of a Repulsive Vector Contribution to the Quark Pressure

    CERN Document Server

    Restrepo, Tulio E; Pinto, Marcus Benghi; Ferrari, Gabriel N

    2014-01-01

    Lattice QCD results for the coefficient $c_2$ appearing in the Taylor expansion of the pressure show that this quantity raises with the temperature towards the Stefan-Boltzmann limit. On the other hand, model approximations predict that when a vector repulsion, parametrized by $G_V$, is present this coefficient reaches a maximum just after $T_c$ and then deviates from the lattice predictions. Recently, this discrepancy has been used as a guide to constrain the (presently unknown) value of $G_V$ within the framework of effective models at large-$N_c$ (LN). In the present investigation we show that, due to finite $N_c$ effects, $c_2$ may also develop a maximum even when $G_V=0$ since a vector repulsive term can be dynamically generated by exchange type of radiative corrections. Here we apply the the Optimized Perturbation Theory (OPT) method to the two flavor Polyakov--Nambu--Jona-Lasinio model (at $G_V=0$) and compare the results with those furnished by lattice simulations an by the LN approximation at $G_V=0$...

  1. Isentropic thermodynamics and scalar-mesons properties near the QCD critical end point

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Pedro [University of Coimbra, CFisUC, Department of Physics, Coimbra (Portugal)

    2016-08-15

    We investigate the QCD phase diagram and the location of the critical end point (CEP) in the SU(2) Polyakov-Nambu-Jona-Lasinio model with entanglement interaction giving special attention to the π and σ -mesons properties, namely the decay widths σ→ππ, for several conditions around the CEP: we focus on the possible σ→ππ decay along the isentropic trajectories close to the CEP since the hydrodynamical expansion of a heavy-ion collision fireball nearly follows trajectories of constant entropy. It is expected that the type of transition the dense medium goes through as it expands after the thermalization determines the behavior of this decay. It is shown that no pions are produced from the sigma decay in the chirally symmetric phase if the isentropic lines approach the first-order line from chemical potentials above it. Near the CEP or above the σ→ππ decay is possible with a high decay width. (orig.)

  2. Dense baryonic matter: constraints from recent neutron star observations

    CERN Document Server

    Hell, Thomas

    2014-01-01

    Updated constraints from neutron star masses and radii impose stronger restrictions on the equation of state for baryonic matter at high densities and low temperatures. The existence of two-solar-mass neutron stars rules out many soft equations of state with prominent "exotic" compositions. The present work reviews the conditions required for the pressure as a function of baryon density in order to satisfy these new constraints. Several scenarios for sufficiently stiff equations of state are evaluated. The common starting point is a realistic description of both nuclear and neutron matter based on a chiral effective field theory approach to the nuclear many-body problem. Possible forms of hybrid matter featuring a quark core in the center of the star are discussed using a three-flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model. It is found that a conventional equation of state based on nuclear chiral dynamics meets the astrophysical constraints. Hybrid matter generally turns out to be too soft unless addition...

  3. Isentropic thermodynamics and scalar-mesons properties near the QCD critical end point

    CERN Document Server

    Costa, Pedro

    2016-01-01

    We investigate the QCD phase diagram and the location of the critical end point (CEP) in the SU(2) Polyakov$-$Nambu$-$Jona-Lasinio model with entanglement interaction giving special attention to the $\\pi$ and $\\sigma$-mesons properties, namely the decay widths $\\sigma\\rightarrow\\pi\\pi$, for several conditions around the CEP: we focus on the possible $\\sigma\\rightarrow\\pi\\pi$ decay along the isentropic trajectories close to the CEP since the hydrodynamical expansion of a heavy-ion collision fireball nearly follows trajectories of constant entropy. It is expected that the type of transition the dense medium goes through as it expands after the thermalization determines the behavior of this decay. It is shown that no pions are produced from the sigma decay in the chirally symmetric phase if the isentropic lines approach the first order line from chemical potentials above it. Near the CEP or above the $\\sigma\\rightarrow\\pi\\pi$ decay is possible with a high decay width.

  4. Influence of the inverse magnetic catalysis and the vector interaction in the location of the critical end point

    CERN Document Server

    Costa, Pedro; Menezes, Débora P; Moreira, João; Providência, Constança

    2015-01-01

    The effect of a strong magnetic field on the location of the critical end point (CEP) in the QCD phase diagram is discussed under different scenarios. In particular, we consider the contribution of the vector interaction and take into account the inverse magnetic catalysis obtained in lattice QCD calculations at zero chemical potential. The discussion is realized within the (2+1) Polyakov--Nambu--Jona-Lasinio model. It is shown that the vector interaction and the magnetic field have opposite competing effects, and that the winning effect depends strongly on the intensity of the magnetic field. The inverse magnetic catalysis at zero chemical potential has two distinct effects for magnetic fields above $\\gtrsim 0.3$ GeV$^2$: it shifts the CEP to lower chemical potentials, hinders the increase of the CEP temperature and prevents a too large increase of the baryonic density at the CEP. For fields $eB<0.1$ GeV$^2$ the competing effects between the vector contribution and the magnetic field can move the CEP to r...

  5. Perturbative Beta function in the most general four-fermion interactions model in (3+1)D

    Energy Technology Data Exchange (ETDEWEB)

    Pena, Francisco [Universidad de la Frontera (UFRO), Temuco (Chile); Nascimento, Leonardo [Instituto Federal de Educacao, Ciencia e Tecnologia do Para (IFPA), PA (Brazil); Alves, Van Sergio [Universidade Federal do Para (UFPA), Belem, PA (Brazil)

    2011-07-01

    Full text: The fundamental theory of strong interactions is described by quantum chromodynamics (QCD), which represents the interaction between quarks and gluons. This theory has two distinct limits of interest. In high energy scale the QCD presents the asymptotic freedom, so that the coupling constant is small in this regime and the perturbation theory can be used. At low energies, comparable to the mass of the lightest hadrons ({approx} 1 Gev), the theory presents non-perturbative aspects such as the confinement of quarks and gluons and chiral symmetry breaking dynamics. The fact that the coupling constant increases when the energy scale decreases makes the analytic study very complex in this regime because the perturbation theory can not be used. In this case, is natural to use effective theories as a tool to describe some properties at low-energy limit. In this context, four fermions models, like Nambu-Jona-Lasinio (NJL) model, have been used as one of the most important effective theories to describe QCD in the low-energy limit. In fact, even these models being nonrenormalizable in d {>=} 3, in the usual power counting sense, they may become physically relevant in the low energy limit. Thus, they are treated as effective theories and the energy interval where this happens the theory behaves as an usual renormalizable one. Studies on the behavior of the beta function in four fermion interactions models have some interest mainly because the fixed points of theses theories, in a certain sense, are related to chiral symmetry breaking and phase transition, which is characteristic of QCD at low energies. The purpose of this work is to study the perturbative behavior of the beta function at 1-loop order in four dimensions and analyze the structure of fixed points. We consider the most general four-fermion interactions obeying an SU(N{sub c}) x SU(N{sub f} )L x SU(N{sub f} ){sub R} symmetry, so that they form a complete basis. We treated the model as an effective

  6. Higher harmonic nonlocal polymerization driven diffusion model: generalized nonlinearities and nonlocal responses

    Science.gov (United States)

    Kelly, John V.; O'Brien, Jeff; O'Neill, Feidhlim T.; Gleeson, Michael R.; Sheridan, John T.

    2004-10-01

    Non-local and non-linear models of photopolymer materials, which include diffusion effects, have recently received much attention in the literature. The material response is non-local as it is assumed that monomers are polymerised to form polymer chains and that these chains grow away from a point of initiation. The non-locality is defined in terms of a spatial non-local material response function. The numerical method of solution typically involves retaining either two or four harmonics of the Fourier series of monomer concentration in the calculation. In this paper a general set of equations is derived which allows inclusion of higher number of harmonics for any response function. The numerical convergence for varying number of harmonics retained is investigated with special care being taken to note the effect of the; non-local material variance s, the power law degree k, and the rates of diffusion, D, and polymerisation F0. General non-linear material responses are also included.

  7. Critical Stability in Nuclei - An Old Problem Revisited

    Science.gov (United States)

    Moszkowski, S. A.

    In this paper we will focus on the nucleon-nucleon interaction in relative S-states. The 1S0 interaction is known to be close to that for critical two-body binding. We will discuss two approaches to the NN interaction, which are equivalent on-shell but not off-shell. There is a well-defined transformation between these approaches [1]. One (my preferred approach) is to minimize the tensor forces far off-shell, which leads to more rapid convergence, but at the price of significant non-locality. This approach is used in a model of relativistic tensor quenching of OPEP [2]. With non-local NN interactions it is possible to fit not only NN observables, but also the NNN ground-state energies [3]. The other approach is to maximize the role of the π and keep the interaction as local as possible [4]. This approach is also internally consistent, but requires additional NNN interactions to fit nuclear data. Also, we discuss briefly a so-called low momentum interaction [5, 6], which fits S-wave phase shifts quite well. This interaction is strongly non-local, and it can be approximated by a schematic separable interaction. Finally, we mention the Nambu-Jona-Lasinio model [7] and a good approximation, the Hulthen potential, which provides some insight into the near critical two-body binding.

  8. Discrete model of dislocations in fractional nonlocal elasticity

    National Research Council Canada - National Science Library

    Tarasov, Vasily E

    2016-01-01

    Discrete models of dislocations in fractional nonlocal materials are suggested. The proposed models are based on fractional-order differences instead of finite differences of integer orders that are usually used...

  9. Stochastic waves in a Brusselator model with nonlocal interaction.

    Science.gov (United States)

    Biancalani, Tommaso; Galla, Tobias; McKane, Alan J

    2011-08-01

    We show that intrinsic noise can induce spatiotemporal phenomena such as Turing patterns and traveling waves in a Brusselator model with nonlocal interaction terms. In order to predict and to characterize these stochastic waves we analyze the nonlocal model using a system-size expansion. The resulting theory is used to calculate the power spectra of the stochastic waves analytically and the outcome is tested successfully against simulations. We discuss the possibility that nonlocal models in other areas, such as epidemic spread or social dynamics, may contain similar stochastically induced patterns.

  10. Coupling of nonlocal and local continuum models by the Arlequinapproach

    KAUST Repository

    Han, Fei

    2011-08-09

    The objective of this work is to develop and apply the Arlequin framework to couple nonlocal and local continuum mechanical models. A mechanically-based model of nonlocal elasticity, which involves both contact and long-range forces, is used for the \\'fine scale\\' description in which nonlocal interactions are considered to have non-negligible effects. Classical continuum mechanics only involving local contact forces is introduced for the rest of the structure where these nonlocal effects can be neglected. Both models overlap in a coupling subdomain called the \\'gluing area\\' in which the total energy is separated into nonlocal and local contributions by complementary weight functions. A weak compatibility is ensured between kinematics of both models using Lagrange multipliers over the gluing area. The discrete formulation of this specific Arlequin coupling framework is derived and fully described. The validity and limits of the technique are demonstrated through two-dimensional numerical applications and results are compared against those of the fully nonlocal elasticity method. © 2011 John Wiley & Sons, Ltd.

  11. Discrete model of dislocations in fractional nonlocal elasticity

    Directory of Open Access Journals (Sweden)

    Vasily E. Tarasov

    2016-01-01

    Full Text Available Discrete models of dislocations in fractional nonlocal materials are suggested. The proposed models are based on fractional-order differences instead of finite differences of integer orders that are usually used. The fractional differences allow us to describe long-range interactions in materials. In continuous limit the suggested discrete models give continuum models of dislocations in nonlocal continua. Fractional generalization of the Frenkel–Kontorova model by using long-range interactions is suggested. We also propose a fractional generalization of interacting atomic chains (IAC model of dislocations by considering long-range interacting chains.

  12. Nonlocal Condensate Model for QCD Sum Rules

    CERN Document Server

    Hsieh, Ron-Chou

    2009-01-01

    We include effects of nonlocal quark condensates into QCD sum rules (QSR) via the K$\\ddot{\\mathrm{a}}$ll$\\acute{\\mathrm{e}}$n-Lehmann representation for a dressed fermion propagator, in which a negative spectral density function manifests their nonperturbative nature. Applying our formalism to the pion form factor as an example, QSR results are in good agreement with data for momentum transfer squared up to $Q^2 \\approx 10 $ GeV$^2$. It is observed that the nonlocal quark-condensate contribution descends like $1/Q^4$, different from the exponential decrease in $Q^2$ obtained in the literature, and contrary to the linear rise in the local-condensate approximation.

  13. Nuclear phenomena derived from quark-gluon strings

    DEFF Research Database (Denmark)

    Bohr, Henrik; Providencia, Constanca; Providencia, Joao da

    2005-01-01

    provided that the chiral fields are identified with the two-particle strings, which are natural in a QCD framework. Moreover, the model is able to reconcile qualitatively such aspects of hadronic physics as saturation density and binding energy of nuclear matter, surface density of finite nuclei, mass......, for the occurrence of the phases of nuclear matter. The model exhibits a quark deconfinement transition and chiral restoration, which are ingredients of QCD and give qualitatively correct numerics. The effective model is shown to be isomorphic to the Nambu-Jona-Lasinio model and exhibits the correct chirality...

  14. Wigner Solution to the Quark Gap Equation in the Nonzero Current Quark Mass

    Institute of Scientific and Technical Information of China (English)

    JIANG Yu; GONG Hao; SUN Wei-Min; ZONG Hong-Shi

    2012-01-01

    From the graphical representation of the Dyson-Schwinger equation for the dressed gluon propagator it is shown that the gluon propagator in the Wigner phase should be different from that in the Nambu phase.Based on this analysis,we propose a modified gluon propagator to reflect this fact.With such a modified gluon propagator,in the framework of the Nambu Jona Lasinio (NJL) model,we obtain the Wigner solution to the quark gap equation at finite current quark mass,which has not been found in literature.This provides a new point of view to study partial restoration of chiral symmetry at finite temperature and chemical potential.%From the graphical representation of the Dyson-Schwinger equation for the dressed gluon propagator it is shown that the gluon propagator in the Wigner phase should be different from that in the Nambu phase. Based on this analysis, we propose a modified gluon propagator to reflect this fact. With such a modified gluon propagator, in the framework of the Nambu-Jona-Lasinio (NJL) model, we obtain the Wigner solution to the quark gap equation at finite current quark mass, which has not been found in literature. This provides a new point of view to study partial restoration of chiral symmetry at finite temperature and chemical potential.

  15. A Nonlocal Poisson-Fermi Model for Ionic Solvent

    CERN Document Server

    Xie, Dexuan; Eisenberg, Bob; Scott, L Ridgway

    2016-01-01

    We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion size effects and polarization correlations among water molecules in the calculation of electrostatic potential. It includes the previous Poisson-Fermi models as special cases, and its solution is the convolution of a solution of the corresponding nonlocal Poisson dielectric model with a Yukawa-type kernel function. Moreover, the Fermi distribution is shown to be a set of optimal ionic concentration functions in the sense of minimizing an electrostatic potential free energy. Finally, numerical results are reported to show the difference between a Poisson-Fermi solution and a corresponding Poisson solution.

  16. Nonlocal Poisson-Fermi model for ionic solvent.

    Science.gov (United States)

    Xie, Dexuan; Liu, Jinn-Liang; Eisenberg, Bob

    2016-07-01

    We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion size effects and polarization correlations among water molecules in the calculation of electrostatic potential. It includes the previous Poisson-Fermi models as special cases, and its solution is the convolution of a solution of the corresponding nonlocal Poisson dielectric model with a Yukawa-like kernel function. The Fermi distribution is shown to be a set of optimal ionic concentration functions in the sense of minimizing an electrostatic potential free energy. Numerical results are reported to show the difference between a Poisson-Fermi solution and a corresponding Poisson solution.

  17. A Caveat on Building Nonlocal Models of Cosmology

    CERN Document Server

    Tsamis, N C

    2014-01-01

    Nonlocal models of cosmology might derive from graviton loop corrections to the effective field equations from the epoch of primordial inflation. Although the Schwinger-Keldysh formalism would automatically produce causal and conserved effective field equations, the models so far proposed have been purely phenomenological. Two techniques have been employed to generate causal and conserved field equations: either varying an invariant nonlocal effective action and then enforcing causality by the ad hoc replacement of any advanced Green's function with its retarded counterpart, or else introducing causal nonlocality into a general ansatz for the field equations and then enforcing conservation. We point out here that the two techniques access very different classes of models, and that neither one of them may represent what would actually arise from fundamental theory.

  18. Strong Local-Nonlocal Coupling for Integrated Fracture Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Littlewood, David John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silling, Stewart A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, John A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seleson, Pablo D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bond, Stephen D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parks, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, Daniel Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burnett, Damon J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ostien, Jakob [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Gunzburger, Max [Florida State Univ., Tallahassee, FL (United States)

    2015-09-01

    Peridynamics, a nonlocal extension of continuum mechanics, is unique in its ability to capture pervasive material failure. Its use in the majority of system-level analyses carried out at Sandia, however, is severely limited, due in large part to computational expense and the challenge posed by the imposition of nonlocal boundary conditions. Combined analyses in which peridynamics is em- ployed only in regions susceptible to material failure are therefore highly desirable, yet available coupling strategies have remained severely limited. This report is a summary of the Laboratory Directed Research and Development (LDRD) project "Strong Local-Nonlocal Coupling for Inte- grated Fracture Modeling," completed within the Computing and Information Sciences (CIS) In- vestment Area at Sandia National Laboratories. A number of challenges inherent to coupling local and nonlocal models are addressed. A primary result is the extension of peridynamics to facilitate a variable nonlocal length scale. This approach, termed the peridynamic partial stress, can greatly reduce the mathematical incompatibility between local and nonlocal equations through reduction of the peridynamic horizon in the vicinity of a model interface. A second result is the formulation of a blending-based coupling approach that may be applied either as the primary coupling strategy, or in combination with the peridynamic partial stress. This blending-based approach is distinct from general blending methods, such as the Arlequin approach, in that it is specific to the coupling of peridynamics and classical continuum mechanics. Facilitating the coupling of peridynamics and classical continuum mechanics has also required innovations aimed directly at peridynamic models. Specifically, the properties of peridynamic constitutive models near domain boundaries and shortcomings in available discretization strategies have been addressed. The results are a class of position-aware peridynamic constitutive laws for

  19. Modelling population growth with delayed nonlocal reaction in 2-dimensions.

    Science.gov (United States)

    Liang, Dong; Wu, Jianhong; Zhang, Fan

    2005-01-01

    In this paper, we consider the population growth of a single species living in a two-dimensional spatial domain. New reaction-difusion equation models with delayed nonlocal reaction are developed in two-dimensional bounded domains combining diferent boundary conditions. The important feature of the models is the reflection of the joint efect of the difusion dynamics and the nonlocal maturation delayed efect. We consider and ana- lyze numerical solutions of the mature population dynamics with some wellknown birth functions. In particular, we observe and study the occurrences of asymptotically stable steady state solutions and periodic waves for the two-dimensional problems with nonlocal delayed reaction. We also investigate numerically the efects of various parameters on the period, the peak and the shape of the periodic wave as well as the shape of the asymptotically stable steady state solution.

  20. Fermion Condensates and the Trivial Vacuum of Light-Cone Quantum Field Theory

    CERN Document Server

    Heinzl, T

    1996-01-01

    We discuss the definition of condensates within light-cone quantum field theory. As the vacuum state in this formulation is trivial, we suggest to abstract vacuum properties from the particle spectrum. The latter can in principle be calculated by solving the eigenvalue problem of the light-cone Hamiltonian. We focus on fermionic condensates which are order parameters of chiral symmetry breaking. As a paradigm identity we use the Gell-Mann-Oakes-Renner relation between the quark condensate and the observable pion mass. We examine the analogues of this relation in the `t~Hooft and Schwinger model, respectively. A brief discussion of the Nambu-Jona-Lasinio model is added.

  1. The influence of chiral chemical potential, parallel electric and magnetic fields on the critical temperature of QCD

    CERN Document Server

    Ruggieri, M; Peng, G X

    2016-01-01

    We study the influence of external electric, $E$, and magnetic, $B$, fields parallel to each other, and of a chiral chemical potential, $\\mu_5$, on the chiral phase transition of Quantum Chromodynamics. Our theoretical framework is a Nambu-Jona-Lasinio model with a contact interaction. Within this model we compute the critical temperature of chiral symmetry restoration, $T_c$, as a function of the chiral chemical potential and field strengths. We find that the fields inhibit and $\\mu_5$ enhances chiral symmetry breaking, in agreement with previous studies.

  2. Chiral symmetry breaking, color superconductivity and equation of state at high density a variational approach

    CERN Document Server

    Mishra, H; Mishra, Hiranmaya; Parikh, Jitendra C.

    2001-01-01

    We discuss in this note simultaneous existence of chiral symmetry breakingand color superconductivity at finite temperature and density in aNambu-Jona-Lasinio type model. The methodology involves an explicitconstruction of a variational ground state and minimisation of thethermodynamic potential. There appears to be a phase at finite densities withboth quark antiquark as well as diquark condensates for the "ground" state.Chiral symmetry breaking phase appear to catalyse the threshold for the diquarkcondensates to appear. We also compute the equation of state in this model.

  3. Chiral symmetry breaking, color superconductivity and quark matter phase diagram: a variational approach 12.38.Gc

    CERN Document Server

    Mishra, H

    2001-01-01

    We discuss in this note simultaneous existence of chiral symmetry breaking and color superconductivity at finite temperature and density in a Nambu-Jona-Lasinio type model. The methodology involves an explicit construction of a variational ground state and minimisation of the thermodynamic potential. There exist nontrivial solutions to the gap equations at finite densities with both quark-antiquark as well as diquark condensates for the 'ground' state. However, such a phase is thermodynamically unstable with the pressure being negative in this region. We also compute the equation of state, and obtain the structure of the phase diagram in the model.

  4. $f N\\piN from quarks to the pion derivative coupling

    CERN Document Server

    Bicudo, P J A

    1997-01-01

    We study the N pi N coupling, in the framework of a QCD-inspired confining Nambu-Jona-Lasinio model. A simple relativistic confining and instantaneous quark model is reviewed. The Salpeter equation for the nucleon and the boosted pion is solved. The f [n pi n] and f[n pi Delta] couplings are calculated and they turn out to be reasonably good. The sensibility of f[n pi n] and f[n pi Delta] to confinement, chiral symmetry breaking and Lorentz invariance is briefly discussed.

  5. Towards thermodynamics of the quark quasi-particles

    CERN Document Server

    Molodtsov, S V

    2011-01-01

    Some features of hot and dense gas of quarks which are considered as the quasi-particles of the model Hamiltonian with four-fermion interaction are studied. Being adapted to the Nambu-Jona-Lasinio model this approach allows us to accommodate a phase transition similar to the nuclear liquid-gas one at the proper scale and to argue an existence of the mixed phase of vacuum and normal baryonic matter as a plausible scenario of chiral symmetry (partial) restoration. Analyzing the transition layer between two phases we estimate the surface tension coefficient and discuss the possibility of quark droplet formation.

  6. Non-local modeling of materials

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2002-01-01

    Numerical studies of non-local plasticity effects on different materials and problems are carried out. Two different theories are used. One is of lower order in that it retains the structure of a conventional plasticity boundary value problem, while the other is of higher order and employs higher...... order stresses as work conjugates to higher order strains and uses higher order boundary conditions. The influence of internal material length parameters is studied, and the effects of higher order boundary conditions are analyzed. The focus of the thesis is on metal-matrix composites, and non...

  7. Comparison between the continuum threshold and the Polyakov loop as deconfinement order parameters

    CERN Document Server

    Carlomagno, J P

    2016-01-01

    We study the relation between the continuum threshold as function of the temperature $s_0(T)$ within finite energy sum rules and the trace of the Polyakov loop $\\Phi$ in the framework of a nonlocal SU(2) chiral quark model, establishing a contact between both deconfinement order parameters at finite temperature $T$ and chemical potential $\\mu$. In our analysis, we also include the order parameter for the chiral symmetry restoration, the chiral quark condensate. We found that $s_0$ and $\\Phi$ providing us the same information for the deconfinement transition, both for the zero and finite chemical potential cases. At zero density, the critical temperatures for both quantities coincide exactly and, at finite $\\mu$ both order parameters provide evidence for the appearance of a quarkyonic phase.

  8. Lorentz Invariant CPT Violating Effects for a Class of Gauge-invariant Nonlocal Thirring Models

    CERN Document Server

    Patra, Pinaki

    2013-01-01

    CPT violation and Lorentz invariance can coexist in the framework of non-local field theory. Local gauge-invariance may not hold for the few non-local interaction terms. However, the gauge-invariance for the non-local interaction term can be formulated by the inclusion of Swinger non-integrable phase factor. In this article we have proposed a class of CPT violating Lorentz invariant Nonlocal Gauge-invariant models which can be termed as non-local gauge-invariant Thirring models. The inclusion of non-locality will modify the current conservation laws. Also, the possible particle antiparticle mass-splitting in this respect is discussed.

  9. Catalysis of dynamical symmetry breaking by a magnetic field

    CERN Document Server

    Miransky, V A

    1995-01-01

    A constant magnetic field in 3+1 and 2+1 dimensions is a strong catalyst of dynamical chiral symmetry breaking, leading to the generation of a fermion mass even at the weakest attractive interaction between fermions. The essence of this effect is the dimensional reduction D/rightarrow D-2 in the dynamics of fermion pairing in a magnetic field. The effect is illustrated in the Nambu-Jona-Lasinio model and QED. Possible applications of this effect and its extension to inhomogeneous field configurations are discussed.

  10. Chiral symmetry, constituent quarks and quasi-elastic electron-nucleus scattering

    Science.gov (United States)

    Henley, E. M.; Krein, G.

    1989-11-01

    The effects of chiral symmetry breaking are examined for quasi-elastic electron scattering on nuclei. Nucleons are assumed to be composed of constituent quarks with masses that depend on density. This density dependence is determined on the basis of the Nambu-Jona-Lasinio model. It is found that the effects of chiral symmetry breaking are in the right direction and the right order of magnitude to explain the discrepancies between theory and experiment. On leave from Departamento de Fisica, Universidade Federal de Santa Maria, 97100 Santa Maria, R.S., Brazil.

  11. Thermal and Nonthermal Pion Enhancements with Chiral Symmetry Restoration

    CERN Document Server

    Zhuang, P

    2001-01-01

    The pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2pion to the lowest order in a 1/N_c expansion is calculated as a function of temperature T and chemical potential mu. The thermal and nonthermal enhancements of pions generated by the decay before and after the freeze-out present only in the crossover region of the chiral symmetry transition. The strongest nonthermal enhancement is located in the vicinity of the endpoint of the first-order transition.

  12. Spin polarization in high density quark matter

    DEFF Research Database (Denmark)

    Bohr, Henrik; Panda, Prafulla K.; Providênci, Constanca

    2013-01-01

    We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu-Jona-Lasinio model......, to which it is related through a Fierz transformation. Flavor SU(2) and flavor SU(3) quark matter are considered. A second-order phase transition is predicted at densities about 5 times the normal nuclear matter density. It is also found that in flavor SU(3) quark matter, a first-order transition from...

  13. Bose-Einstein Condensation in Strong-Coupling Quark Color Superconductor near Flavor SU(3) Limit

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Bing; REN Chun-Fu; ZHANG Yi

    2011-01-01

    Near the flavor SU(3) limit, we propose an analytical description for color-flavor-locked-type Bardeen-Cooper-Schrieffer (BCS) phase in the Nambu Jona-Lasinio (NJL) model. The diquark behaviors in light-flavor and strange-flavor-involved channels and Bose-Einstein condensation (BEC) of bound diquark states are studied. When the attractive interaction between quarks is strong enough, a BCS-BEC crossover is predicted in the environment with color-flavor-locked pairing pattern. The resulting Bose-Einstein condensed phase is found to be an intergrade phase before the emergence of the previous-predicted BEC phase in two-flavor quark superconductor.

  14. On properties of low-lying spin-1 hadron resonances

    Science.gov (United States)

    Chizhov, M. V.

    2017-03-01

    Properties of low-lying spin-1 hadron resonances are described in the review. It is shown how the Nambu-Jona-Lasinio model can be extended in the chiral invariant way by new tensor interactions. New mass formulas are obtained, which are not based on unitary symmetry groups but involve particles from different multiplets even with opposite parity. They all are in good agreement with experimental data. Dynamic properties of spin-1 mesons confirmed by the calculations performed using the QCD sum rule technique and the lattice calculations are understood and explained.

  15. Elucidating the sign problem through noise distributions

    CERN Document Server

    Nicholson, Amy N; Kaplan, David B

    2012-01-01

    Due to the presence of light pions in the theory, lattice QCD at finite densities suffers from issues with noise in both grand canonical and canonical formulations. We study two different formulations of the Nambu-Jona-Lasinio model reduced to 2+1 dimensions at large N, where N is the number of flavors. At finite chemical potential one formulation has a severe sign problem and a fermion correlator which displays a broad probability distribution with small mean. In the other we find no sign problem and a distribution amenable to the cumulant expansion techniques developed in earlier work.

  16. Chiral Symmetry Restoration with a Chiral Chemical Potential: the Role of Momentum Dependent Quark Self-energy

    CERN Document Server

    Ruggieri, M

    2016-01-01

    In this article we study restoration of chiral symmetry at finite temperature for quark matter with a chiral chemical potential, $\\mu_5$, by means of a nonlocal Nambu-Jona-Lasinio model. This model allows to introduce in the simplest way possible a Euclidean momentum, $p_E$, dependent quark mass function which decays (neglecting logarithms) as $1/p_E^2$ for large $p_E$ in agreement with asymptotic behaviour expected in presence of a nonperturbative quark condensate. We show that the momentum dependence of the quark mass function, which has been neglected in all of the previous model studies, drastically affects the dependence of the critical temperature versus $\\mu_5$. We explain this in terms of a natural removal of ultraviolet modes at $T>0$ in the gap equation, as well as of the natural addition of these modes at $T=0$ which help to catalyze chiral symmetry breaking. As a result we find that within this model the critical temperature increases with $\\mu_5$.

  17. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    CERN Document Server

    Spinella, William M; Contrera, Gustavo A; Orsaria, Milva G

    2015-01-01

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron m...

  18. High temperature quark localization by Polyakov loops

    CERN Document Server

    Kovacs, Tamas G; Bruckmann, Falk; Schierenberg, Sebastian

    2011-01-01

    We study the low eigenmodes of the overlap and staggered Dirac operator at high temperature. We show that the recently found localized quark modes obeying Poisson statistics are connected to physical gauge field objects with their size and density scaling in the continuum limit. The localized modes are also strongly correlated with large fluctuations of the Polyakov loop. Based on that we construct a random matrix model of the low Dirac modes inspired by dimensional reduction. Our model reproduces the Poisson to random matrix transition seen in the lattice Dirac spectrum.

  19. Sparse representation based image interpolation with nonlocal autoregressive modeling.

    Science.gov (United States)

    Dong, Weisheng; Zhang, Lei; Lukac, Rastislav; Shi, Guangming

    2013-04-01

    Sparse representation is proven to be a promising approach to image super-resolution, where the low-resolution (LR) image is usually modeled as the down-sampled version of its high-resolution (HR) counterpart after blurring. When the blurring kernel is the Dirac delta function, i.e., the LR image is directly down-sampled from its HR counterpart without blurring, the super-resolution problem becomes an image interpolation problem. In such cases, however, the conventional sparse representation models (SRM) become less effective, because the data fidelity term fails to constrain the image local structures. In natural images, fortunately, many nonlocal similar patches to a given patch could provide nonlocal constraint to the local structure. In this paper, we incorporate the image nonlocal self-similarity into SRM for image interpolation. More specifically, a nonlocal autoregressive model (NARM) is proposed and taken as the data fidelity term in SRM. We show that the NARM-induced sampling matrix is less coherent with the representation dictionary, and consequently makes SRM more effective for image interpolation. Our extensive experimental results demonstrate that the proposed NARM-based image interpolation method can effectively reconstruct the edge structures and suppress the jaggy/ringing artifacts, achieving the best image interpolation results so far in terms of PSNR as well as perceptual quality metrics such as SSIM and FSIM.

  20. Non-local model analysis of heat pulse propagation

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, Takuya [Interdisciplinary Graduate School of Engineering Sciences, Kyushu Univ., Kasuga, Fukuoka (Japan); Itoh, Sanae-I.; Yagi, Masatoshi

    1998-10-01

    A new theoretical model equation which includes the non-local effect in the heat flux is proposed to study the transient transport phenomena. A non-local heat flux, which is expressed in terms of the integral equation, is superimposed on the conventional form of the heat flux. This model is applied to describe the experimental results from the power switching [Stroth U, et al 1996 Plasma Phys. Control. Fusion 38 1087] and the power modulation experiments [Giannone L, et al 1992 Nucl. Fusion 32 1985] in the W7-AS stellarator. A small fraction of non-local component in the heat flux is found to be very effective in modifying the response against an external modulation. The transient feature of the transport property, which are observed in the response of heat pulse propagation, are qualitatively reproduced by the transport simulations based on this model. A possibility is discussed to determine the correlation length of the non-local effect experimentally by use of the results of transport simulations. (author)

  1. Hommage a Nambu

    CERN Document Server

    Ramond, Pierre

    2016-01-01

    Reminiscences of my intellectual and personal interactions with Professor Nambu, and discussion of his contributions to string theory. Switching to my own research, by expressing the string coordinates as bispinors, I suggest a kinematical framework for the interacting (2,0) theory on the light-cone by using chiral constrained "Viking" superfields.

  2. The Effect of Logarithmic Mesonic Potential on the Magnetic Catalysis in the Chiral Quark-Sigma Model

    CERN Document Server

    Abu-Shady, M

    2015-01-01

    The chiral symmetry breaking in the presence of external magnetic field is studied in the framework of logarithmic quark-sigma model. The effective logarithmic mesonic potential is employed and is numerically solved in the mean-field approximation. We find that the chiral symmetry breaking enhances in comparison with the original sigma model. Two sets of parameterization are investigated in the present model. We find that increasing coupling constant enhances the breaking symmetry while increasing sigma mass inhibits enhancing chiral broken vacuum state. A comparison with the Numbu-Jona-Lasinio model and the Schwinger-Dyson equation is discussed. We conclude that the logarithmic sigma model enhances the magnetic catalysis in comparison with the original sigma model and other models.

  3. Phase diagram and nucleation in the Polyakov-loop-extended Quark-Meson truncation of QCD with the unquenched Polyakov-loop potential

    CERN Document Server

    Stiele, Rainer

    2016-01-01

    Unquenching of the Polyakov-loop potential showed to be an important improvement for the description of the phase structure and thermodynamics of strongly-interacting matter at zero quark chemical potentials with Polyakov-loop extended chiral models. This work constitutes the first application of the quark backreaction on the Polyakov-loop potential at nonzero density. The observation is that it links the chiral and deconfinement phase transition also at small temperatures and large quark chemical potentials. The build up of the surface tension in the Polyakov-loop extended Quark-Meson model is explored by investigating the two and 2+1-flavour Quark-Meson model and analysing the impact of the Polyakov-loop extension. In general, the order of magnitude of the surface tension is given by the chiral phase transition. The coupling of the chiral and deconfinement transition with the unquenched Polyakov-loop potential leads to the fact that the Polyakov-loop contributes at all temperatures.

  4. Prey-predator model with a nonlocal consumption of prey.

    Science.gov (United States)

    Banerjee, M; Volpert, V

    2016-08-01

    The prey-predator model with nonlocal consumption of prey introduced in this work extends previous studies of local reaction-diffusion models. Linear stability analysis of the homogeneous in space stationary solution and numerical simulations of nonhomogeneous solutions allow us to analyze bifurcations and dynamics of stationary solutions and of travelling waves. These solutions present some new properties in comparison with the local models. They correspond to different feeding strategies of predators observed in ecology.

  5. Prey-predator model with a nonlocal consumption of prey

    Science.gov (United States)

    Banerjee, M.; Volpert, V.

    2016-08-01

    The prey-predator model with nonlocal consumption of prey introduced in this work extends previous studies of local reaction-diffusion models. Linear stability analysis of the homogeneous in space stationary solution and numerical simulations of nonhomogeneous solutions allow us to analyze bifurcations and dynamics of stationary solutions and of travelling waves. These solutions present some new properties in comparison with the local models. They correspond to different feeding strategies of predators observed in ecology.

  6. Structure formation in a nonlocally modified gravity model

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sohyun; Dodelson, Scott

    2013-01-01

    We study a nonlocally modified gravity model proposed by Deser and Woodard which gives an explanation for current cosmic acceleration. By deriving and solving the equations governing the evolution of the structure in the Universe, we show that this model predicts a pattern of growth that differs from standard general relativity (+dark energy) at the 10-30% level. These differences will be easily probed by the next generation of galaxy surveys, so the model should be tested shortly.

  7. SU(3) Polyakov Linear $\\sigma$-Model in Magnetic Field: Thermodynamics, Higher-Order Moments, Chiral Phase Structure and Meson Masses

    CERN Document Server

    Tawfik, Abdel Nasser

    2015-01-01

    Effects of external magnetic field on various properties of the quantum chromodynamics under extreme conditions of temperature and density have been analysed. To this end, we use SU(3) Polyakov linear sigma-model and assume that the external magnetic field eB adds some restrictions to the quarks energy due to the existence of free charges in the plasma phase. In doing this, we apply the Landau theory of quantization. This requires an additional temperature to drive the system through the chiral phase-transition. Accordingly, the dependence of the critical temperature of chiral and confinement phase-transitions on the magnetic field is characterized. Based on this, we have studied the thermal evolution of thermodynamic quantities and the first four higher-order moment of particle multiplicity. Having all these calculations, we have studied the effects of magnetic field on chiral phase-transition. We found that both critical temperature T_c and critical chemical potential increase with increasing the magnetic f...

  8. Two-direction nonlocal model for image denoising.

    Science.gov (United States)

    Zhang, Xuande; Feng, Xiangchu; Wang, Weiwei

    2013-01-01

    Similarities inherent in natural images have been widely exploited for image denoising and other applications. In fact, if a cluster of similar image patches is rearranged into a matrix, similarities exist both between columns and rows. Using the similarities, we present a two-directional nonlocal (TDNL) variational model for image denoising. The solution of our model consists of three components: one component is a scaled version of the original observed image and the other two components are obtained by utilizing the similarities. Specifically, by using the similarity between columns, we get a nonlocal-means-like estimation of the patch with consideration to all similar patches, while the weights are not the pairwise similarities but a set of clusterwise coefficients. Moreover, by using the similarity between rows, we also get nonlocal-autoregression-like estimations for the center pixels of the similar patches. The TDNL model leads to an alternative minimization algorithm. Experiments indicate that the model can perform on par with or better than the state-of-the-art denoising methods.

  9. Nonlocal-response diffusion model of holographic recording in photopolymer

    OpenAIRE

    Sheridan, John T.; Lawrence, Justin R.

    2000-01-01

    The standard one-dimensional diffusion equation is extended to include nonlocal temporal and spatial medium responses. How such nonlocal effects arise in a photopolymer is discussed. It is argued that assuming rapid polymer chain growth, any nonlocal temporal response can be dealt with so that the response can be completely understood in terms of a steady-state nonlocal spatial response. The resulting nonlocal diffusion equation is then solved numerically, in low-harmonic approximation, to de...

  10. Generalized non-local responses and higher harmonic retention in non-local polymerization driven diffusion model based simulations

    Science.gov (United States)

    Sheridan, J. T.; Kelly, J. V.; O'Brien, G.; Gleeson, M. R.; O'Neill, F. T.

    2004-12-01

    Non-local and non-linear models of photopolymer materials, which include diffusion effects, have recently received much attention in the literature. The material response is described as non-local as it is assumed that monomers are polymerized to form polymer chains and that these chains grow away from a point of initiation. The non-locality is defined in terms of a spatial non-local material response function. The material model is non-linear as a general non-linear material response to the incident light is included. Typically the numerical method of solution has involved retaining only up to four harmonics of the Fourier series of monomer concentration in the calculations. In this paper a general set of coupled first-order differential equations is derived which allow the inclusion of a higher number of harmonics. The resulting effect on the convergence of the algorithm, as the number of harmonics retained is increased, is investigated. Special care is taken to note the effect of physical parameters, i.e. the non-local material variance σ, the power-law degree k, and the rates of diffusion, D, and polymerization, F0.

  11. Nonlocal continuum model and molecular dynamics for free vibration of single-walled carbon nanotubes.

    Science.gov (United States)

    Hu, Yan-Gao; Liew, K M; Wang, Q

    2011-12-01

    Free transverse, longitudinal and torsional vibrations of single-walled carbon nanotubes (SWCNTs) are investigated through nonlocal beam model, nonlocal rod model and verified by molecular dynamics (MD) simulations. The nonlocal Timoshenko beam model offers a better prediction of the fundamental frequencies of shorter SWCNTs, such as a (5, 5) SWCNT shorter than 3.5 nm, than local beam models. The nonlocal rod model is employed to study the longitudinal and torsional vibrations of SWCNT and found to enable a good prediction of the MD results for shorter SWCNTs. Nonlocal and local continuum models provide a good agreement with MD results for relatively longer SWCNTs, such as (5, 5) SWCNTs longer than 3.5 nm. The scale parameter in nonlocal beam and rod models is estimated by calibrations from MD results.

  12. Spherical systems in models of nonlocally corrected gravity

    CERN Document Server

    Bronnikov, K A

    2009-01-01

    The properties of static, spherically symmetric configurations are considered in the framework of two models of nonlocally corrected gravity, suggested in S. Deser and R. Woodard., Phys. Rev. Lett. 663, 111301 (2007), and S. Capozziello et al., Phys. Lett. B 671, 193 (2009). For the first case, where the Lagrangian of nonlocal origin represents a scalar-tensor theory with two massless scalars, an explicit condition is found under which both scalars are canonical (non-phantom). If this condition does not hold, one of the fields exhibits a phantom behavior. Scalar-vacuum configurations then behave in a manner known for scalar-tensor theories. In the second case, the Lagrangian of nonlocal origin exhibits a scalar field interacting with the Gauss-Bonnet (GB) invariant and contains an arbitrary scalar field potential. It is found that the GB term, in general, leads to violation of the well-known no-go theorems valid for minimally coupled scalar fields in general relativity. It is shown, however, that some configu...

  13. Characterizing 3-qubit UPB states: violations of LHV models, preparation via nonlocal unitaries and PPT entangled nonlocal orbits

    CERN Document Server

    Altafini, C

    2004-01-01

    For the 3-qubit UPB state, i.e., the bound entangled state constructed from an Unextendable Product Basis of Bennett et al. (Phys. Rev. Lett. 82:5385, 1999), we provide a set of violations of Local Hidden Variable (LHV) models based on the particular type of reflection symmetry encoded in this state. The explicit nonlocal unitary operation needed to prepare the state from its reflected separable mixture of pure states is given, as well as a nonlocal one-parameter orbit of states with Positive Partial Transpositions (PPT) which swaps the entanglement between a state and its reflection twice during a period.

  14. Supersymmetry breaking and Nambu-Goldstone fermions in an extended Nicolai model

    CERN Document Server

    Sannomiya, Noriaki; Nakayama, Yu

    2016-01-01

    We study a model of interacting spinless fermions in a one dimensional lattice with supersymmetry (SUSY). The Hamiltonian is given by the anti-commutator of two supercharges $Q$ and $Q^\\dagger$, each of which is comprised solely of fermion operators and possesses one adjustable parameter $g$. When the parameter $g$ vanishes, the model is identical to the one studied by Nicolai [H. Nicolai, J. Phys. A: Math. Gen. \\textbf{9}, 1497 (1976)], where the zero-energy ground state is exponentially degenerate. On the other hand, in the large-$g$ limit the model reduces to the free-fermion chain with a four-fold degenerate ground state. We show that for finite chains SUSY is spontaneously broken when $g > 0$. We also rigorously prove that for sufficiently large $g$ the ground-state energy density is nonvanishing in the infinite-volume limit. We further analyze the nature of the low-energy excitations by employing various techniques such as rigorous inequalities, exact numerical diagonalization, and renormalization group...

  15. SU(3) Polyakov linear-σ model in magnetic fields: Thermodynamics, higher-order moments, chiral phase structure, and meson masses

    Science.gov (United States)

    Tawfik, Abdel Nasser; Magdy, Niseem

    2015-01-01

    Effects of an external magnetic field on various properties of quantum chromodynamics (QCD) matter under extreme conditions of temperature and density (chemical potential) have been analyzed. To this end, we use SU(3) Polyakov linear-σ model and assume that the external magnetic field (e B ) adds some restrictions to the quarks' energy due to the existence of free charges in the plasma phase. In doing this, we apply the Landau theory of quantization, which assumes that the cyclotron orbits of charged particles in a magnetic field should be quantized. This requires an additional temperature to drive the system through the chiral phase transition. Accordingly, the dependence of the critical temperature of chiral and confinement phase transitions on the magnetic field is characterized. Based on this, we have studied the thermal evolution of thermodynamic quantities (energy density and trace anomaly) and the first four higher-order moment of particle multiplicity. Having all these calculations, we have studied the effects of the magnetic field on the chiral phase transition. We found that both critical temperature Tc and critical chemical potential increase with increasing magnetic field, e B . Last but not least, the magnetic effects of the thermal evolution of four scalar and four pseudoscalar meson states are studied. We concluded that the meson masses decrease as the temperature increases up to Tc. Then, the vacuum effect becomes dominant and rapidly increases with the temperature T . At low T , the scalar meson masses normalized to the lowest Matsubara frequency rapidly decrease as T increases. Then, starting from Tc, we find that the thermal dependence almost vanishes. Furthermore, the meson masses increase with increasing magnetic field. This gives a characteristic phase diagram of T vs external magnetic field e B . At high T , we find that the masses of almost all meson states become temperature independent. It is worthwhile to highlight that the various meson

  16. Effective Field Theories for Hot and Dense Matter

    Directory of Open Access Journals (Sweden)

    Blaschke D.

    2010-10-01

    Full Text Available The lecture is divided in two parts. The first one deals with an introduction to the physics of hot, dense many-particle systems in quantum field theory [1, 2]. The basics of the path integral approach to the partition function are explained for the example of chiral quark models. The QCD phase diagram is discussed in the meanfield approximation while QCD bound states in the medium are treated in the rainbow-ladder approximation (Gaussian fluctuations. Special emphasis is devoted to the discussion of the Mott effect, i.e. the transition of bound states to unbound, but resonant scattering states in the continnum under the influence of compression and heating of the system. Three examples are given: (1 the QCD model phase diagram with chiral symmetry ¨ restoration and color superconductivity [3], (2 the Schrodinger equation for heavy-quarkonia [4], and (2 Pions [5] as well as Kaons and D-mesons in the finite-temperature Bethe-Salpeter equation [6]. We discuss recent applications of this quantum field theoretical approach to hot and dense quark matter for a description of anomalous J/ψ supression in heavy-ion collisions [7] and for the structure and cooling of compact stars with quark matter interiors [8]. The second part provides a detailed introduction to the Polyakov-loop Nambu–Jona-Lasinio model [9] for thermodynamics and mesonic correlations [10] in the phase diagram of quark matter. Important relationships of low-energy QCD like the Gell-Mann–Oakes–Renner relation are generalized to finite temperatures. The effect of including the coupling to the Polyakov-loop potential on the phase diagram and mesonic correlations is discussed. An outlook is given to effects of nonlocality of the interactions [11] and of mesonic correlations in the medium [12] which go beyond the meanfield description.

  17. Modeling elastic tensile fractures in snow using nonlocal damage mechanics

    Science.gov (United States)

    Borstad, C. P.; McClung, D. M.

    2011-12-01

    The initiation and propagation of tensile fractures in snow and ice are fundamental to numerous important physical processes in the cryosphere, from iceberg calving to ice shelf rift propagation to slab avalanche release. The heterogeneous nature of snow and ice, their proximity to the melting temperature, and the varied governing timescales typically lead to nonlinear fracture behavior which does not follow the predictions of Linear Elastic Fracture Mechanics (LEFM). Furthermore, traditional fracture mechanics is formally inapplicable for predicting crack initiation in the absence of a pre-existing flaw or stress concentration. An alternative to fracture mechanics is continuum damage mechanics, which accounts for the material degradation associated with cracking in a numerically efficient framework. However, damage models which are formulated locally (e.g. stress and strain are defined as point properties) suffer from mesh-sensitive crack trajectories, spurious localization of damage and improper fracture energy dissipation with mesh refinement. Nonlocal formulations of damage, which smear the effects of the material heterogeneity over an intrinsic length scale related to the material microstructure, overcome these difficulties and lead to numerically efficient and mesh-objective simulations of the tensile failure of heterogeneous materials. We present the results of numerical simulations of tensile fracture initiation and propagation in cohesive snow using a nonlocal damage model. Seventeen beam bending experiments, both notched and unnotched, were conducted using blocks of cohesive dry snow extracted from an alpine snowpack. Material properties and fracture parameters were calculated from the experimental data using beam theory and quasi-brittle fracture mechanics. Using these parameters, a nonlocal isotropic damage model was applied to two-dimensional finite element meshes of the same scale as the experiments. The model was capable of simulating the propagation

  18. Soft Matrix Elements in Non-local Chiral Quark Model

    CERN Document Server

    Kotko, Piotr

    2009-01-01

    Using non-local chiral quark model and currents satisfying Ward-Takahashi identities we analyze Distribution Amplitudes (DA) of photon and pion-to-photon Transition Distribution Amplitudes (TDA) in the low energy regime. Photon DA's are calculated analytically up to twist-4 and reveal several interesting features of photon structure. TDA's calculated in the present model satisfy polynomiality condition. Normalization of vector TDA is fixed by the axial anomaly. We also compute relevant form factors and compare them with existing data. Axial form factor turns out to be much lower then the vector one, what indeed is seen in the experimental data.

  19. Nonlocal order parameters for the 1D Hubbard model.

    Science.gov (United States)

    Montorsi, Arianna; Roncaglia, Marco

    2012-12-07

    We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point U(c)=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at U(c). The behavior of the parity correlators is captured by an effective free spinless fermion model.

  20. Application of nonlocal models to nano beams. Part II: Thickness length scale effect.

    Science.gov (United States)

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of the Eringen's nonlocal Euler-Bernoulli (EB) beam model. In literature, most work has taken the axial coordinate derivative in the Laplacian operator presented in nonlocal elasticity. This causes that the non-locality always makes the beam soften as compared to the local counterpart. In this paper, the thickness scale effect is solely considered to investigate if the nonlocal model can simulate stiffening effect. Taking the thickness derivative in the Laplacian operator leads to the presence of a surface stress state. The governing equation derived is compared to that of the EB model with the surface stress. The results obtained reveal that the nonlocality tends to decrease the bending moment stiffness whereas to increase the bending rigidity in the governing equation. This tendency also depends on the surface conditions.

  1. Possible formation of high temperature superconductor at an early stage of heavy-ion collisions

    Science.gov (United States)

    Liu, Hao; Yu, Lang; Chernodub, Maxim; Huang, Mei

    2016-12-01

    We investigate the effect of the inverse magnetic catalysis (IMC) on charged ρ meson condensation at finite temperature in the framework of the Nambu-Jona-Lasinio model, where mesons are calculated to the leading order of 1 /Nc expansion. The IMC for chiral condensate has been considered using three different approaches: incorporating the chiral condensate from lattice data, using the running coupling constant, and introducing the chiral chemical potential, respectively. It is observed that with no IMC effect included, the critical magnetic field e Bc for charged ρ condensation increases monotonically with the temperature. However, including IMC substantially affects the polarized charged ρ condensation around the critical temperature Tc of the chiral phase transition: first, the critical magnetic field e Bc for the charged ρ condensation decreases with the temperature, reaches its minimum value around Tc, and then increases with the temperature. It is quite surprising that the charged ρ can condense above the critical temperature of chiral phase transition with a even smaller critical magnetic field comparing its vacuum value. The Nambu-Jona-Lasinio model calculation shows that in the temperature region of 1 - 1.5 Tc , the critical magnetic field for charged ρ condensation is rather small and in the region of e Bc˜0.15 - 0.3 GeV2 , which suggests that high temperature superconductor might be created through noncentral heavy ion collisions at LHC energies.

  2. Free vibrations analysis of carbon nanotubes resting on Winkler foundations based on nonlocal models

    Energy Technology Data Exchange (ETDEWEB)

    Rahmanian, M.; Torkaman-Asadi, M.A., E-mail: torkaman-asadi@ae.sharif.edu; Firouz-Abadi, R.D.; Kouchakzadeh, M.A.

    2016-03-01

    In the present study, free vibrations of single walled carbon nanotubes (SWCNT) on an elastic foundation is investigated by nonlocal theory of elasticity with both beam and shell models. The nonlocal boundary conditions are derived explicitly and effectiveness of nonlocal parameter appearing in nonlocal boundary conditions is studied. Also it is demonstrated that the beam model is comparatively incapable of capturing size effects while shell model captures size effects more precisely. Moreover, the effects of some parameters such as mechanical properties, foundation stiffness, length and radius ratios on the natural frequencies are studied and some conclusions are drawn.

  3. Specific heat of a non-local attractive Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Calegari, E.J., E-mail: eleonir@ufsm.br [Laboratório de Teoria da Matéria Condensada, Departamento de Física, UFSM, 97105-900, Santa Maria, RS (Brazil); Lobo, C.O. [Laboratório de Teoria da Matéria Condensada, Departamento de Física, UFSM, 97105-900, Santa Maria, RS (Brazil); Magalhaes, S.G. [Instituto de Física, Universidade Federal Fluminense, Av. Litorânea s/n, 24210, 346, Niterói, Rio de Janeiro (Brazil); Chaves, C.M.; Troper, A. [Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil)

    2013-10-01

    The specific heat C(T) of an attractive (interaction G<0) non-local Hubbard model is investigated within a two-pole approximation that leads to a set of correlation functions, which play an important role as a source of anomalies as the pseudogap. For a giving range of G and n{sub T} (where n{sub T}=n{sub ↑}+n{sub ↓}), the specific heat as a function of the temperature presents a two peak structure. Nevertehelesss, the presence of a pseudogap eliminates the two peak structure. The effects of the second nearest-neighbor hopping on C(T) are also investigated.

  4. Nonlinear analysis of lipid tubules by nonlocal beam model.

    Science.gov (United States)

    Shen, Hui-Shen

    2011-05-07

    Postbuckling, nonlinear bending and nonlinear vibration analyses are presented for lipid tubules. The lipid tubule is modeled as a nonlocal micro/nano-beam which contains small scale effect. The material properties are assumed to be size-dependent. The governing equation is solved by a two-step perturbation technique. The numerical results reveal that the small scale parameter e₀a reduces the postbuckling equilibrium paths, the static large deflections and natural frequencies of lipid tubules. In contrast, it increases the nonlinear to linear frequency ratios slightly for the lipid tubule with immovable end conditions.

  5. A nonlocal, ordinary, state-based plasticity model for peridynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, John Anthony

    2011-05-01

    An implicit time integration algorithm for a non-local, state-based, peridynamics plasticity model is developed. The flow rule was proposed in [3] without an integration strategy or yield criterion. This report addresses both of these issues and thus establishes the first ordinary, state-based peridynamics plasticity model. Integration of the flow rule follows along the lines of the classical theories of rate independent J{sub 2} plasticity. It uses elastic force state relations, an additive decomposition of the deformation state, an elastic force state domain, a flow rule, loading/un-loading conditions, and a consistency condition. Just as in local theories of plasticity (LTP), state variables are required. It is shown that the resulting constitutive model does not violate the 2nd law of thermodynamics. The report also develops a useful non-local yield criterion that depends upon the yield stress and horizon for the material. The modulus state for both the ordinary elastic material and aforementioned plasticity model is also developed and presented.

  6. Equivalent bosonic theory for the massive Thirring model with non-local interaction

    OpenAIRE

    Li, Kang; Naon, Carlos

    1997-01-01

    We study, through path-integral methods, an extension of the massive Thirring model in which the interaction between currents is non-local. By examining the mass-expansion of the partition function we show that this non-local massive Thirring model is equivalent to a certain non-local extension of the sine-Gordon theory. Thus, we establish a non-local generalization of the famous Coleman's equivalence. We also discuss some possible applications of this result in the context of one-dimensional...

  7. Remarks on correlators of Polyakov Loops

    CERN Document Server

    Neuberger, Herbert

    2013-01-01

    Polyakov loop eigenvalues and their N-dependence are studied in 2 and 4 dimensional SU(N) YM theory. The connected correlation function of the single eigenvalue distributions of two separated Polyakov loops in 2D YM is calculated and is found to have a structure differing from the one of corresponding hermitian random matrix ensembles. No large $N$ non-analyticities are found for two point functions in the confining regime. Suggestions are made for situations in which large-N phase transitions involving Polyakov loops might occur.

  8. Fuzzy bags, Polyakov loop and gauge/string duality

    Directory of Open Access Journals (Sweden)

    Zuo Fen

    2014-01-01

    Full Text Available Confinement in SU(N gauge theory is due to the linear potential between colored objects. At short distances, the linear contribution could be considered as the quadratic correction to the leading Coulomb term. Recent lattice data show that such quadratic corrections also appear in the deconfined phase, in both the thermal quantities and the Polyakov loop. These contributions are studied systematically employing the gauge/string duality. “Confinement” in N${\\cal N}$ = 4 SU(N Super Yang-Mills (SYM theory could be achieved kinematically when the theory is defined on a compact space manifold. In the large-N limit, deconfinement of N${\\cal N}$ = 4 SYM on S3${{\\Bbb S}^3}$ at strong coupling is dual to the Hawking-Page phase transition in the global Anti-de Sitter spacetime. Meantime, all the thermal quantities and the Polyakov loop achieve significant quadratic contributions. Similar results can also be obtained at weak coupling. However, when confinement is induced dynamically through the local dilaton field in the gravity-dilaton system, these contributions can not be generated consistently. This is in accordance with the fact that there is no dimension-2 gauge-invariant operator in the boundary gauge theory. Based on these results, we suspect that quadratic corrections, and also confinement, should be due to global or non-local effects in the bulk spacetime.

  9. Can the particle mass spectrum be explained within the Standard Model?

    CERN Document Server

    de Oca, Alejandro Cabo Montes; Cabo-Bizet, Alejandro

    2009-01-01

    A modified version of PQCD considered in previous works is investigated here in the case of retaining only the quark condensate. The Green functions generating functional is expressed in a form in which Dirac's delta functions are now absent from the free propagators. The new expansion implements the dimensional transmutation effect through a single interaction vertex in addition to the standard ones in mass less QCD. The new vertex suggests a way for constructing an alternative to the SM in which the mass and CKM matrices could be generated by the instability of masslesss QCD under the production of the top quark and other fermions condensates, in a kind of generalized Nambu Jona Lasinio mechanism. The results of a two loop evaluation of the vacuum energy indicate that the quark condensate is dynamically generated. However, the energy as a function of the condensate parameter is again unbounded from below in this approximation. Assuming the existence of a minimum of the vacuum energy at the experimental valu...

  10. Aggregation patterns from nonlocal interactions: Discrete stochastic and continuum modeling

    KAUST Repository

    Hackett-Jones, Emily J.

    2012-04-17

    Conservation equations governed by a nonlocal interaction potential generate aggregates from an initial uniform distribution of particles. We address the evolution and formation of these aggregating steady states when the interaction potential has both attractive and repulsive singularities. Currently, no existence theory for such potentials is available. We develop and compare two complementary solution methods, a continuous pseudoinverse method and a discrete stochastic lattice approach, and formally show a connection between the two. Interesting aggregation patterns involving multiple peaks for a simple doubly singular attractive-repulsive potential are determined. For a swarming Morse potential, characteristic slow-fast dynamics in the scaled inverse energy is observed in the evolution to steady state in both the continuous and discrete approaches. The discrete approach is found to be remarkably robust to modifications in movement rules, related to the potential function. The comparable evolution dynamics and steady states of the discrete model with the continuum model suggest that the discrete stochastic approach is a promising way of probing aggregation patterns arising from two- and three-dimensional nonlocal interaction conservation equations. © 2012 American Physical Society.

  11. Dynamical nonlocality of the entangled coherent state in the phase damping model

    Institute of Scientific and Technical Information of China (English)

    Lu Huai-Xin; Li Ying-De

    2009-01-01

    This paper studies the dynamics of nonlocality for a bosonic entangled coherent state in a phase damping model. The density operator of the system is solved by using a superoperator method. The dynamics of nonlocality for the bosonic entangled coherent state is uncovered by the Bell operator based on the pseudospin operator of a light field. The dynamics of the nonlocality for this state has also been studied by other Bell operators. The result of the numerical calculations of the Bell function shows that the quantum nonlocality heavily depends on the chosen Bell operator.

  12. A straightforward approach to Eringen's nonlocal elasticity stress model and applications for nanobeams

    Science.gov (United States)

    Koutsoumaris, C. Chr.; Eptaimeros, K. G.; Zisis, T.; Tsamasphyros, G. J.

    2016-12-01

    The nonlocal theory of elasticity is widely employed to the study of nanoscale problems. The differential approach of Eringen's nonlocal beam theory has been widely used to solve problems whose size effect is substantial in structures. However, in the case of Euler-Bernoulli beam theory (EBBT), this approach reveals inconsistencies that do not allow for the energy functional formulation. To avoid these inconsistencies, an alternative route is to use the integral form of nonlocal elasticity. This study revolves around the nonlocal integral beam model for various attenuation functions with the intention to explore the static response of a beam (or a nanobeam) for different types of loadings and boundary conditions (BC).

  13. Effective Polyakov Loop Dynamics for Finite Temperature G(2) Gluodynamics

    CERN Document Server

    Wellegehausen, Bjoern H; Wozar, Christian

    2009-01-01

    Based on the strong coupling expansion we obtain effective 3-dimensional models for the Polyakov loop in finite-temperature G_2 gluodynamics. The Svetitsky-Jaffe conjecture relates the resulting continuous spin models with G_2 gluodynamics near phase transition points. In the present work we analyse the effective theory in leading order with the help of a generalised mean field approximation and with detailed Monte-Carlo simulations. In addition we derive a Potts-type discrete spin model by restricting the characters of the Polyakov loops to the three extremal points of the fundamental domain of G_2. Both the continuous and discrete effective models show a rich phase structure with a ferromagnetic, symmetric and several anti-ferromagnetic phases. The phase diagram contains first and second order transition lines and tricritical points. The modified mean field predictions compare very well with the results of our simulations.

  14. Application of Nonlocal Elasticity Shell Model for Axial Buckling of Single-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Farzad Khademolhosseini

    2009-10-01

    Full Text Available Recently, nano devices have been developed which use Carbon Nanotubes (CNTs as structural elements. To define the range of applicability of CNTs in such devices, it is important to investigate failure modes such as the axial buckling limit. Classical continuum models are inaccurate as they are unable to account for the size-effects in such devices. In this work, a modified nonlocal continuum shell model for the axial buckling of CNTs is proposed and compared with a nonlocal model for torsional buckling. This is done through modifying classical continuum models by incorporating basic concepts from nonlocal elasticity. Furthermore, molecular dynamics (MD simulations are performed on a range of nanotubes with different diameters. Compared to classical models, the modified nonlocal models provide a much better fit to MD simulation results. Using MD simulation results for axial buckling, values of the nonlocal constant and shell thickness are calculated.

  15. Nonlocal Generalized Models of Predator-Prey Systems

    CERN Document Server

    Kuehn, Christian

    2011-01-01

    The method of generalized modeling has been applied successfully in many different contexts, particularly in ecology and systems biology. It can be used to analyze the stability and bifurcations of steady-state solutions. Although many dynamical systems in mathematical biology exhibit steady-state behaviour one also wants to understand nonlocal dynamics beyond equilibrium points. In this paper we analyze predator-prey dynamical systems and extend the method of generalized models to periodic solutions. First, we adapt the equilibrium generalized modeling approach and compute the unique Floquet multiplier of the periodic solution which depends upon so-called generalized elasticity and scale functions. We prove that these functions also have to satisfy a flow on parameter (or moduli) space. Then we use Fourier analysis to provide computable conditions for stability and the moduli space flow. The final stability analysis reduces to two discrete convolutions which can be interpreted to understand when the predator...

  16. On a Nonlocal Problem Modelling Ohmic Heating in Planar Domains

    Institute of Scientific and Technical Information of China (English)

    Fei LIANG; Qi Lin LIU; Yu Xiang LI

    2013-01-01

    In this paper, we consider the nonlocal problem of the form ut-△u=λe-u/(∫Ωe-udx)2,x∈Ω,t>0 and the associated nonlocal stationary problem -△v=λe-v/(∫Ωe-vdx)2,x∈Ω, where A is a positive parameter. For Ω to be an annulus, we prove that the nonlocal stationary problem has a unique solution if and only if λ < 2|(6)Ω|2, and for A = 2|(6)Ω|2, the solution of the nonlocal parabolic problem grows up globally to infinity as t → ∞.

  17. Evolution of Bell- nonlocality of two cavity fields in the double Jaynes-Cummings model

    Institute of Scientific and Technical Information of China (English)

    Long Miao; Yunkun Jiang

    2011-01-01

    The Bell-nonlocality of two initially entangled macroscopic fields in the double Jaynes-Cummings model is investigated.Moreover,the process by which detuning between the atomic transition frequency and the field frequency affects the evolution of the Bell-nonlocality of two macroscopic fields is studied.The effect of the disparity between the two coupling strengths is discussed.

  18. Atomically informed nonlocal semi-discrete variational Peierls-Nabarro model for planar core dislocations.

    Science.gov (United States)

    Liu, Guisen; Cheng, Xi; Wang, Jian; Chen, Kaiguo; Shen, Yao

    2017-03-02

    Prediction of Peierls stress associated with dislocation glide is of fundamental concern in understanding and designing the plasticity and mechanical properties of crystalline materials. Here, we develop a nonlocal semi-discrete variational Peierls-Nabarro (SVPN) model by incorporating the nonlocal atomic interactions into the semi-discrete variational Peierls framework. The nonlocal kernel is simplified by limiting the nonlocal atomic interaction in the nearest neighbor region, and the nonlocal coefficient is directly computed from the dislocation core structure. Our model is capable of accurately predicting the displacement profile, and the Peierls stress, of planar-extended core dislocations in face-centered cubic structures. Our model could be extended to study more complicated planar-extended core dislocations, such as {111} dislocations in Al-based and Ti-based intermetallic compounds.

  19. AC-conductance of a non-local Thirring model

    Energy Technology Data Exchange (ETDEWEB)

    Trobo, Marta Liliana; Von Reichenbach, Maria Cecilia [Universidad Nacional de La Plata (UNLP) (Argentina); Barci, Daniel G. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)]|[Illinois Univ., Urbana, IL (United States); Medeiros Neto, J.F. de [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)

    2000-07-01

    Full text follows: In recent years renewed interest has arisen in the study of low dimensional field theories. In particular, research on the one dimensional (1-d) fermionic gas has been very active, mainly due to the actual nano-fabrication of the so called quantum wires and their relevance for low dimensional condensed matter physics as, for instance, the quantum Hall effect and high-T{sub c} superconductivity. Experimental and theoretical investigations of the AC-transport phenomena in nano-structures are of profound scientific interest since they provide insight into the behavior of quantum systems. In this frame, we consider a field theoretical approach that can be used to describe a system of 1-d strongly correlated particles in the low transferred momentum limit. We study a non-local and non-covariant version of the Thirring model where the fermionic densities and currents are coupled through bilocal, distance-dependent potentials which describe the forward scattering processes. We apply the functional bosonization formalism, a very useful technique to understand the non-perturbative regime of strongly correlated one-dimensional fermionic systems, to this non local Thirring like model (NLTM). We are interesting in the transport properties of the system, in particular in the AC-conductance. To this end, we consider a NLTM in the presence of an external electromagnetic field. We obtain the AC-conductance of the model in terms of non-local potentials used to describe the interactions between fermionic currents. We also analyze the transport properties in the case in which weak couplings between fermionic currents and localized impurities are taken into account. (author)

  20. A Note on a Nonlocal Nonlinear Reaction-Diffusion Model

    OpenAIRE

    Walker, Christoph

    2011-01-01

    We give an application of the Crandall-Rabinowitz theorem on local bifurcation to a system of nonlinear parabolic equations with nonlocal reaction and cross-diffusion terms as well as nonlocal initial conditions. The system arises as steady-state equations of two interacting age-structured populations.

  1. Characteristics of the chiral phase transition in nonlocal quark models

    CERN Document Server

    Dumm, D G

    2004-01-01

    The characteristics of the chiral phase transition are analyzed within the framework of chiral quark models with nonlocal interactions in the mean field approximation (MFA). In the chiral limit, we show that there is a region of low values of the chemical potential in which the transition is a second order one. In that region, it is possible to perform a Landau expansion and determine the critical exponents which, as expected, turn out to be the MFA ones. Our analysis also allows to obtain semi-analytical expressions for the transition curve and the location of the tricritical point. For the case of finite current quark masses, we study the behavior of various thermodynamical and chiral response functions across the phase transition.

  2. Generalized cavity model and nonlocal effects in nanoslit arrays

    CERN Document Server

    Dechaux, Mathieu; Ciracì, Cristian; Benedicto, Jessica; Pollès, Rémi; Centeno, Emmanuel; Smith, David R; Moreau, Antoine

    2016-01-01

    Gap-plasmon resonators are a class of nanogap-based plasmonic structures presenting unprecedented optical properties despite a size that can be smaller than the skin depth of metals. In the case of extremely narrow slit arrays, these ultra-small resonators are better described by a generalized cavity model. Moreover, such structures are sensitive to the nonlocal response of the metals arising from interactions between free electrons inside the jellium. This phenomenon actually influences the necessarily intense plasmonic slowdown (very low phase and group velocities) experienced by the gap-plasmon in such tiny cavities. Accurately describing the optical response of this class of structures requires to take all of these effects into account, and will undoubtedly be necessary to design or characterize future gap-plasmon resonators.

  3. Nambu at Work

    Science.gov (United States)

    Freund, Peter G. O.

    Yoichiro Nambu, whose life and seminal contributions to Physics we celebrate here, went in 1952 to the Institute for Advanced Study in Princeton. Shortly after his arrival there, J. Robert Oppenheimer, the Institute's director, put Yoichiro and the other new arrivals on notice that though Albert Einstein was a professor at the Institute, and therefore had an office there, nobody was to disturb the great man without first receiving special permission personally from Oppie. Most people would spend a year or two in the same building with Einstein and then spend a whole lifetime regretting not to have met him. Yoichiro decided that he will meet Einstein, no matter what Oppie says. He knew Bruria Kaufmann, Einstein's assistant at that time, and with her help got to visit the great physicist. Einstein was very friendly and visibly happy that finally one of the young people had bothered to visit him. Einstein asked Yoichiro what was going on in particle physics, and was rather skeptical about separate nucleon and meson fields for which he saw no deeper reason...

  4. Nonlocal modeling and buckling features of cracked nanobeams with von Karman nonlinearity

    Science.gov (United States)

    Akbarzadeh Khorshidi, Majid; Shaat, Mohamed; Abdelkefi, Abdessattar; Shariati, Mahmoud

    2017-01-01

    Buckling and postbuckling behaviors of cracked nanobeams made of single-crystalline nanomaterials are investigated. The nonlocal elasticity theory is used to model the nonlocal interatomic effects on the beam's performance accounting for the beam's axial stretching via von Karman nonlinear theory. The crack is then represented as torsional spring where the crack severity factor is derived accounting for the nonlocal features of the beam. By converting the beam into an equivalent infinite long plate with an edge crack subjected to a tensile stress at the far field, the crack energy release rate, intensity factor, and severity factor are derived according to the nonlocal elasticity theory. An analytical solution for the buckling and the postbuckling responses of cracked nonlocal nanobeams accounting for the beam axial stretching according to von Karman nonlinear theory of kinematics is derived. The impacts of the nonlocal parameter on the critical buckling loads and the static nonlinear postbuckling responses of cracked nonlocal nanobeams are studied. The results indicate that the buckling and postbuckling behaviors of cracked nanobeams are strongly affected by the crack location, crack depth, nonlocal parameter, and length-to-thickness ratio.

  5. Application of nonlocal models to nano beams. Part I: Axial length scale effect.

    Science.gov (United States)

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of physical implications via the similarity between a nonlocal Euler-Bernoulli (EB) beam theory and a classical Rankine-Timoshenko (RT) beam theory. The nonlocal EB beam model, Eringen's model, is briefly reviewed and the classical RT beam theory is recast by the primary variables of the EB model. A careful comparison of these two models reveals that the scale parameter used to the Eringen's model has a strike resemblance to the shear flexibility in the RT model. This implies that the nonlocal model employed in literature consider the axial length scale effect only. In addition, the paradox for a cantilevered nano-beam subjected to tip shear force is clearly explained by finding appropriate displacement prescribed boundary conditions.

  6. Cubic Matrix, Nambu Mechanics and Beyond

    OpenAIRE

    Kawamura, Y

    2002-01-01

    We propose a generalization of cubic matrix mechanics by introducing a canonical triplet and study its relation to Nambu mechanics. The generalized cubic matrix mechanics we consider can be interpreted as a “quantum” generalization of Nambu mechanics.

  7. Mass concentration in a nonlocal model of clonal selection.

    Science.gov (United States)

    Busse, J-E; Gwiazda, P; Marciniak-Czochra, A

    2016-10-01

    Self-renewal is a constitutive property of stem cells. Testing the cancer stem cell hypothesis requires investigation of the impact of self-renewal on cancer expansion. To better understand this impact, we propose a mathematical model describing the dynamics of a continuum of cell clones structured by the self-renewal potential. The model is an extension of the finite multi-compartment models of interactions between normal and cancer cells in acute leukemias. It takes a form of a system of integro-differential equations with a nonlinear and nonlocal coupling which describes regulatory feedback loops of cell proliferation and differentiation. We show that this coupling leads to mass concentration in points corresponding to the maxima of the self-renewal potential and the solutions of the model tend asymptotically to Dirac measures multiplied by positive constants. Furthermore, using a Lyapunov function constructed for the finite dimensional counterpart of the model, we prove that the total mass of the solution converges to a globally stable equilibrium. Additionally, we show stability of the model in the space of positive Radon measures equipped with the flat metric (bounded Lipschitz distance). Analytical results are illustrated by numerical simulations.

  8. A NEW COMBINED LOCAL AND NON-LOCAL PBL MODEL FOR METEOROLOGY AND AIR QUALITY MODELING

    Science.gov (United States)

    A new version of the Asymmetric Convective Model (ACM) has been developed to describe sub-grid vertical turbulent transport in both meteorology models and air quality models. The new version (ACM2) combines the non-local convective mixing of the original ACM with local eddy diff...

  9. A NEW COMBINED LOCAL AND NON-LOCAL PBL MODEL FOR METEOROLOGY AND AIR QUALITY MODELING

    Science.gov (United States)

    A new version of the Asymmetric Convective Model (ACM) has been developed to describe sub-grid vertical turbulent transport in both meteorology models and air quality models. The new version (ACM2) combines the non-local convective mixing of the original ACM with local eddy diff...

  10. Analytical solutions of nonlocal Poisson dielectric models with multiple point charges inside a dielectric sphere

    Science.gov (United States)

    Xie, Dexuan; Volkmer, Hans W.; Ying, Jinyong

    2016-04-01

    The nonlocal dielectric approach has led to new models and solvers for predicting electrostatics of proteins (or other biomolecules), but how to validate and compare them remains a challenge. To promote such a study, in this paper, two typical nonlocal dielectric models are revisited. Their analytical solutions are then found in the expressions of simple series for a dielectric sphere containing any number of point charges. As a special case, the analytical solution of the corresponding Poisson dielectric model is also derived in simple series, which significantly improves the well known Kirkwood's double series expansion. Furthermore, a convolution of one nonlocal dielectric solution with a commonly used nonlocal kernel function is obtained, along with the reaction parts of these local and nonlocal solutions. To turn these new series solutions into a valuable research tool, they are programed as a free fortran software package, which can input point charge data directly from a protein data bank file. Consequently, different validation tests can be quickly done on different proteins. Finally, a test example for a protein with 488 atomic charges is reported to demonstrate the differences between the local and nonlocal models as well as the importance of using the reaction parts to develop local and nonlocal dielectric solvers.

  11. Analytical solutions of nonlocal Poisson dielectric models with multiple point charges inside a dielectric sphere.

    Science.gov (United States)

    Xie, Dexuan; Volkmer, Hans W; Ying, Jinyong

    2016-04-01

    The nonlocal dielectric approach has led to new models and solvers for predicting electrostatics of proteins (or other biomolecules), but how to validate and compare them remains a challenge. To promote such a study, in this paper, two typical nonlocal dielectric models are revisited. Their analytical solutions are then found in the expressions of simple series for a dielectric sphere containing any number of point charges. As a special case, the analytical solution of the corresponding Poisson dielectric model is also derived in simple series, which significantly improves the well known Kirkwood's double series expansion. Furthermore, a convolution of one nonlocal dielectric solution with a commonly used nonlocal kernel function is obtained, along with the reaction parts of these local and nonlocal solutions. To turn these new series solutions into a valuable research tool, they are programed as a free fortran software package, which can input point charge data directly from a protein data bank file. Consequently, different validation tests can be quickly done on different proteins. Finally, a test example for a protein with 488 atomic charges is reported to demonstrate the differences between the local and nonlocal models as well as the importance of using the reaction parts to develop local and nonlocal dielectric solvers.

  12. A nonlocal shell model for mode transformation in single-walled carbon nanotubes.

    Science.gov (United States)

    Shi, M X; Li, Q M; Huang, Y

    2009-11-11

    A second-order strain gradient nonlocal shell model is established to study the mode transformation in single-walled carbon nanotubes (SWCNTs). Nonlocal length is calibrated carefully for SWCNTs in reference to molecular dynamics (MD) simulations through analysis of nonlocal length effects on the frequencies of the radial breathing mode (RBM) and circumferential flexural modes (CFMs) and its effects on mode transformation. All analyses show that only a negative second-order nonlocal shell model is appropriate to SWCNTs. Nonlocal length is evidently related to vibration modes and the radius-to-thickness ratio. It is found that a nonlocal length is approximately 0.1 nm in an average sense when RBM frequency is concerned. A nonlocal length of 0.122-0.259 nm is indicated for the mode transformation in a selected group of armchair SWCNTs. 2:1 and 1:1 internal resonances are found for the same SWCNT based on different models, which implies that the internal resonance mechanism depends on the model employed. Furthermore, it is shown that an effective thickness of approximately 0.1 nm is more appropriate to SWCNTs than 0.066 nm.

  13. Deformation quantization and Nambu mechanics

    CERN Document Server

    Dito, G; Sternheimer, D; Takhtajan, L A; Dito, Giuseppe; Flato, Moshe; Sternheimer, Daniel; Takhtajan, Leon

    1996-01-01

    Starting from deformation quantization (star-products), the quantization problem of Nambu Mechanics is investigated. After considering some impossibilities and pushing some analogies with field quantization, a solution to the quantization problem is presented in what we call the Zariski quantization of fields (observables, functions, in this case polynomials). This quantization is based on the factorization over {\\Bbb R} of polynomials in several real variables. We quantize the algebra of fields generated by the polynomials by defining a deformation of this algebra which is Abelian, associative and distributive. This procedure is then adapted to derivatives (needed for the Nambu brackets), which ensures the validity of the Fundamental Identity of Nambu Mechanics also at the quantum level. Our construction is in fact more general than the particular case considered here: it can be utilized for quite general defining identities and for much more general star-products.

  14. Effective potential for Polyakov loops in lattice QCD

    Science.gov (United States)

    Nemoto, Y.; RBC Collaboration

    2003-05-01

    Toward the derivation of an effective theory for Polyakov loops in lattice QCD, we examine Polyakov loop correlation functions using the multi-level algorithm which was recently developed by Luscher and Weisz.

  15. Hidden-variable models for the spin singlet: I. Non-local theories reproducing quantum mechanics

    CERN Document Server

    Di Lorenzo, Antonio

    2011-01-01

    A non-local hidden variable model reproducing the quantum mechanical probabilities for a spin singlet is presented. The non-locality is concentrated in the distribution of the hidden variables. The model otherwise satisfies both the hypothesis of outcome independence, made in the derivation of Bell inequality, and of compliance with Malus's law, made in the derivation of Leggett inequality. It is shown through the prescription of a protocol that the non-locality can be exploited to send information instantaneously provided that the hidden variables can be measured, even though they cannot be controlled.

  16. QCD topological susceptibility from the nonlocal chiral quark model

    CERN Document Server

    Nam, Seung-il

    2016-01-01

    We investigate the QCD topological susceptibility $\\chi_t$ by using the nonlocal chiral quark model (NL$\\chi$QM). This model is based on the liquid instanton QCD-vacuum configuration in which $\\mathrm{SU}(3)$ flavor symmetry is explicitly broken by the current quark mass $(m_{u,d},m_s)\\approx(5,135)$ MeV. To compute $\\chi_t$, the local topological charge density operator $Q_t(x)$ is derived from the effective partition function of NL$\\chi$QM. We take into account the contributions from the leading-order (LO) ones $\\sim\\mathcal{O}(N_c)$ in the $1/N_c$ expansion. We also verify that the analytical expression of $\\chi_t$ in NL$\\chi$QM satisfy the Witten-Veneziano (WV) and the Leutwyler-Smilga (LS) formulae. Once the average instanton size and inter-instanton distance are fixed with $\\bar{\\rho}=1/3$ fm and $\\bar{R}=1$ fm, respectively, all the associated model parameters are all determined self-consistently within the model, including the $\\eta$ and $\\eta'$ weak decay constants. We obtain the results such as $F_{...

  17. QCD topological susceptibility from the nonlocal chiral quark model

    Science.gov (United States)

    Nam, Seung-Il; Kao, Chung-Wen

    2017-06-01

    We investigate the quantum chromodynamics (QCD) topological susceptibility χ by using the semi-bosonized nonlocal chiral-quark model (SB-NLχQM) for the leading large- N c contributions. This model is based on the liquid-instanton QCD-vacuum configuration, in which SU(3) flavor symmetry is explicitly broken by the finite current-quark mass ( m u,d, m s) ≈ (5, 135) MeV. To compute χ, we derive the local topological charge-density operator Q t( x) from the effective action of SB-NLχQM. We verify that the derived expression for χ in our model satisfies the Witten- Veneziano (WV) and the Leutwyler-Smilga (LS) formulae, and the Crewther theorem in the chiral limit by construction. Once the average instanton size and the inter-instanton distance are fixed with ρ¯ = 1/3 fm and R¯ = 1 fm, respectively, all the other parameters are determined self-consistently within the model. We obtain χ = (167.67MeV)4, which is comparable with the empirical value χ = (175±5MeV)4 whereas it turns out that χ QL = (194.30MeV)4 in the quenched limit. Thus, we conclude that the value of χ will be reduced around 10 20% by the dynamical-quark contribution.

  18. Finite element analysis of nano-scale Timoshenko beams using the integral model of nonlocal elasticity

    Science.gov (United States)

    Norouzzadeh, A.; Ansari, R.

    2017-04-01

    Stress-strain relation in Eringen's nonlocal elasticity theory was originally formulated within the framework of an integral model. Due to difficulty of working with that integral model, the differential model of nonlocal constitutive equation is widely used for nanostructures. However, paradoxical results may be obtained by the differential model for some boundary and loading conditions. Presented in this article is a finite element analysis of Timoshenko nano-beams based on the integral model of nonlocal continuum theory without employing any simplification in the model. The entire procedure of deriving equations of motion is carried out in the matrix form of representation, and hence, they can be easily used in the finite element analysis. For comparison purpose, the differential counterparts of equations are also derived. To study the outcome of analysis based on the integral and differential models, some case studies are presented in which the influences of boundary conditions, nonlocal length scale parameter and loading factor are analyzed. It is concluded that, in contrast to the differential model, there is no paradox in the numerical results of developed integral model of nonlocal continuum theory for different situations of problem characteristics. So, resolving the mentioned paradoxes by means of a purely numerical approach based on the original integral form of nonlocal elasticity theory is the major contribution of present study.

  19. Contact of boundary-value problems and nonlocal problems in mathematical models of heat transfer

    Science.gov (United States)

    Lyashenko, V.; Kobilskaya, O.

    2015-10-01

    In this paper the mathematical models in the form of nonlocal problems for the two-dimensional heat equation are considered. Relation of a nonlocal problem and a boundary value problem, which describe the same physical heating process, is investigated. These problems arise in the study of the temperature distribution during annealing of the movable wire and the strip by permanent or periodically operating internal and external heat sources. The first and the second nonlocal problems in the mobile area are considered. Stability and convergence of numerical algorithms for the solution of a nonlocal problem with piecewise monotone functions in the equations and boundary conditions are investigated. Piecewise monotone functions characterize the heat sources and heat transfer conditions at the boundaries of the area that is studied. Numerous experiments are conducted and temperature distributions are plotted under conditions of internal and external heat sources operation. These experiments confirm the effectiveness of attracting non-local terms to describe the thermal processes. Expediency of applying nonlocal problems containing nonlocal conditions - thermal balance conditions - to such models is shown. This allows you to define heat and mass transfer as the parameters of the process control, in particular heat source and concentration of the substance.

  20. Nonlocal elasticity defined by Eringen's integral model: Introduction of a boundary layer method

    National Research Council Canada - National Science Library

    Abdollahi, R; Boroomand, B

    2014-01-01

    In this paper we consider a nonlocal elasticity theory defined by Eringen's integral model and introduce, for the first time, a boundary layer method by presenting the exponential basis functions (EBFs...

  1. Analysis of Stability for Gas-Kinetic Non-Local Traffic Model

    Institute of Scientific and Technical Information of China (English)

    SUN Xi-Ming; DONG Yu-Jie

    2006-01-01

    @@ The gas-kinetic non-local traffic model is improved by taking into account the relative velocity of the correlated vehicles. The stability of different relaxation time modes is analytically investigated with the perturbation method.

  2. Single quark entropy and the Polyakov loop

    CERN Document Server

    Weber, Johannes Heinrich

    2016-01-01

    We study Quantum Chromodynamics (QCD) with 2+1 flavors with almost physical quark masses using the highly improved staggered quark action (HISQ). We calculate the Polyakov loop in a wide temperature range, obtain the free energy and the entropy of a single static quark and discuss the QCD crossover region in detail. We show that the entropy has a peak close to the chiral crossover and consider the consequences for the deconfinement aspects of the crossover phenomena. We study the renormalized Polyakov loop susceptibilities and place them into the context of the crossover. We also obtain a quantitative result for the onset of weak coupling behavior at high temperatures.

  3. Vector and axial vector mesons in a nonlocal chiral quark model

    Science.gov (United States)

    Izzo Villafañe, M. F.; Gómez Dumm, D.; Scoccola, N. N.

    2016-09-01

    Basic features of nonstrange vector and axial vector mesons are analyzed in the framework of a chiral quark model that includes nonlocal four-fermion couplings. Unknown model parameters are determined from some input values of masses and decay constants, while nonlocal form factors are taken from a fit to lattice QCD results for effective quark propagators. Numerical results show a good agreement with the observed meson phenomenology.

  4. Vector and axial vector mesons in a nonlocal chiral quark model

    CERN Document Server

    Villafañe, M F Izzo; Scoccola, N N

    2016-01-01

    Basic features of nonstrange vector and axial vector mesons are analyzed in the framework of a chiral quark model that includes nonlocal four fermion couplings. Unknown model parameters are determined from some input values of masses and decay constants, while nonlocal form factors are taken from a fit to lattice QCD results for effective quark propagators. Numerical results show a good agreement with the observed meson phenomenology.

  5. Nambu bracket and M-theory

    CERN Document Server

    Ho, Pei-Ming

    2016-01-01

    Nambu proposed an extension of dynamical system through the introduction of a new bracket (Nambu bracket) in 1973. This article is a short review of the developments after his paper. Some emphasis are put on a viewpoint that the Nambu bracket naturally describes extended objects which appear in M-theory and the fluid dynamics. The latter part of the paper is devoted to a review of the studies on the Nambu bracket (Lie 3-algebra) in Bagger-Lambert-Gustavsson theory of multiple M2-branes. This paper is a contribution to the proceedings of Nambu memorial symposium (Osaka City University, September 29, 2015).

  6. Convergence of capillary fluid models: from the non-local to the local Korteweg model

    CERN Document Server

    Charve, Frédéric

    2011-01-01

    In this paper we are interested in the barotropic compressible Navier-Stokes system endowed with a non-local capillarity tensor depending on a small parameter $\\epsilon$ such that it heuristically tends to the local Korteweg system. After giving some physical motivations related to the theory of non-classical shocks (see [28]) we prove global well-posedness (in the whole space $R^d$ with $d\\geq 2$) for the non-local model and we also prove the convergence, as $\\epsilon$ goes to zero, to the solution of the local Korteweg system.

  7. Optimal Hubbard models for materials with nonlocal Coulomb interactions: graphene, silicene, and benzene.

    Science.gov (United States)

    Schüler, M; Rösner, M; Wehling, T O; Lichtenstein, A I; Katsnelson, M I

    2013-07-19

    To understand how nonlocal Coulomb interactions affect the phase diagram of correlated electron materials, we report on a method to approximate a correlated lattice model with nonlocal interactions by an effective Hubbard model with on-site interactions U(*) only. The effective model is defined by the Peierls-Feynman-Bogoliubov variational principle. We find that the local part of the interaction U is reduced according to U(*)=U-V[over ¯], where V[over ¯] is a weighted average of nonlocal interactions. For graphene, silicene, and benzene we show that the nonlocal Coulomb interaction can decrease the effective local interaction by more than a factor of 2 in a wide doping range.

  8. Chiral and deconfinement transitions in a magnetic background using the functional renormalization group with the Polyakov loop

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Jens O.; Naylor, William R. [Department of Physics, Norwegian University of Science and Technology, Høgskoleringen 5, N-7491 Trondheim (Norway); Tranberg, Anders [Faculty of Science and Technology, University of Stavanger, N-4036 Stavanger (Norway)

    2014-04-30

    We use the Polyakov loop coupled quark-meson model to approximate low energy QCD and present results for the chiral and deconfinement transitions in the presence of a constant magnetic background B at finite temperature T and baryon chemical potential μ{sub B}. We investigate effects of various gluonic potentials on the deconfinement transition with and without a fermionic backreaction at finite B. Additionally we investigate the effect of the Polyakov loop on the chiral phase transition, finding that magnetic catalysis at low μ{sub B} is present, but weakened by the Polyakov loop.

  9. A nonlocal constitutive model for trabecular bone softening in compression.

    Science.gov (United States)

    Charlebois, Mathieu; Jirásek, Milan; Zysset, Philippe K

    2010-10-01

    Using the three-dimensional morphological data provided by computed tomography, finite element (FE) models can be generated and used to compute the stiffness and strength of whole bones. Three-dimensional constitutive laws capturing the main features of bone mechanical behavior can be developed and implemented into FE software to enable simulations on complex bone structures. For this purpose, a constitutive law is proposed, which captures the compressive behavior of trabecular bone as a porous material with accumulation of irreversible strain and loss of stiffness beyond its yield point and softening beyond its ultimate point. To account for these features, a constitutive law based on damage coupled with hardening anisotropic elastoplasticity is formulated using density and fabric-based tensors. To prevent mesh dependence of the solution, a nonlocal averaging technique is adopted. The law has been implemented into a FE software and some simple simulations are first presented to illustrate its behavior. Finally, examples dealing with compression of vertebral bodies clearly show the impact of softening on the localization of the inelastic process.

  10. Variational principles for transversely vibrating multiwalled carbon nanotubes based on nonlocal Euler-Bernoulli beam model.

    Science.gov (United States)

    Adali, Sarp

    2009-05-01

    Variational principles are derived for multiwalled carbon nanotubes undergoing vibrations. Derivations are based on the continuum modeling with the Euler-Bernoulli beam representing the nanotubes and small scale effects taken into account via the nonlocal elastic theory. Hamilton's principle for multiwalled nanotubes is given and Rayleigh's quotient for the frequencies is derived for nanotubes undergoing free vibrations. Natural and geometric boundary conditions are derived which lead to a set of coupled boundary conditions due to nonlocal effects.

  11. Polyakov Loop Correlations at Large N

    CERN Document Server

    Neuberger, Herbert

    2014-01-01

    I describe a study of the two-point single-eigenvalue distribution correlation function of Polyakov loops in the confined phase of four dimensional SU(N) YM theory at large N. The reasons for the interest in this correlation function are explained. Analytical and numerical results are presented. Brief conclusions are drawn.

  12. Nonlocal beam models for buckling of nanobeams using state-space method regarding different boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sahmani, S.; Ansari, R. [University of Guilan, Rasht (Iran, Islamic Republic of)

    2011-09-15

    Buckling analysis of nanobeams is investigated using nonlocal continuum beam models of the different classical beam theories namely as Euler-Bernoulli beam theory (EBT), Timoshenko beam theory (TBT), and Levinson beam theory (LBT). To this end, Eringen's equations of nonlocal elasticity are incorporated into the classical beam theories for buckling of nanobeams with rectangular cross-section. In contrast to the classical theories, the nonlocal elastic beam models developed here have the capability to predict critical buckling loads that allowing for the inclusion of size effects. The values of critical buckling loads corresponding to four commonly used boundary conditions are obtained using state-space method. The results are presented for different geometric parameters, boundary conditions, and values of nonlocal parameter to show the effects of each of them in detail. Then the results are fitted with those of molecular dynamics simulations through a nonlinear least square fitting procedure to find the appropriate values of nonlocal parameter for the buckling analysis of nanobeams relevant to each type of nonlocal beam model and boundary conditions analysis.

  13. Moving nonradiating kinks in nonlocal φ4 and φ4-φ6 models.

    Science.gov (United States)

    Alfimov, G L; Medvedeva, E V

    2011-11-01

    We explore the existence of moving nonradiating kinks in nonlocal generalizations of φ(4) and φ(4)-φ(6) models. These models are described by nonlocal nonlinear Klein-Gordon equation, u(tt)-Lu+F(u)=0, where L is a Fourier multiplier operator of a specific form and F(u) includes either just a cubic term (φ(4) case) or cubic and quintic (φ(4)-φ(6) case) terms. The general mechanism responsible for the discretization of kink velocities in the nonlocal model is discussed. We report numerical results obtained for these models. It is shown that, contrary to the traditional φ(4) model, the nonlocal φ(4) model does not admit moving nonradiating kinks but admits solitary waves that do not exist in the local model. At the same time the nonlocal φ(4)-φ(6) model describes moving nonradiating kinks. The set of velocities allowed for these kinks is discrete with the highest possible velocity c(1). This set of velocities is unambiguously determined by the parameters of the model. Numerical simulations show that a kink launched at the velocity c higher than c(1) starts to decelerate, and its velocity settles down to the highest value of the discrete spectrum c(1).

  14. Nonlocal dispersive optical model ingredients for ${}^{40}$Ca

    CERN Document Server

    Mahzoon, M H; Dickhoff, W H; Dussan, H; Waldecker, S J

    2013-01-01

    A comprehensive description of all single-particle properties associated with the nucleus ${}^{40}$Ca has been generated by employing a nonlocal dispersive optical potential capable of simultaneously reproducing all relevant data above and below the Fermi energy. We gather all relevant functional forms and the numerical values of the parameters in this contribution.

  15. The effect of the Polyakov loop on the chiral phase transition

    Directory of Open Access Journals (Sweden)

    Szép Zs.

    2011-04-01

    Full Text Available The Polyakov loop is included in the S U(2L × S U(2R chiral quark-meson model by considering the propagation of the constituent quarks, coupled to the (σ, π meson multiplet, on the homogeneous background of a temporal gauge field, diagonal in color space. The model is solved at finite temperature and quark baryon chemical potential both in the chiral limit and for the physical value of the pion mass by using an expansion in the number of flavors Nf. Keeping the fermion propagator at its tree-level, a resummation on the pion propagator is constructed which resums infinitely many orders in 1/Nf, where O(1/Nf represents the order at which the fermions start to contribute in the pion propagator. The influence of the Polyakov loop on the tricritical or the critical point in the µq – T phase diagram is studied for various forms of the Polyakov loop potential.

  16. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Spinella, William M. [Computational Science Research Center San Diego State University, San Diego, CA (United States); San Diego State University, Department of Physics, San Diego, CA (United States); Weber, Fridolin [San Diego State University, Department of Physics, San Diego, CA (United States); University of California San Diego, Center for Astrophysics and Space Sciences, La Jolla, CA (United States); Contrera, Gustavo A. [CONICET, Buenos Aires (Argentina); CONICET - Dept. de Fisica, UNLP, IFLP, La Plata (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina); Orsaria, Milva G. [CONICET, Buenos Aires (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina)

    2016-03-15

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (

  17. Nonlocal Inflation

    CERN Document Server

    Barnaby, Neil

    2008-01-01

    We consider the possibility of realizing inflation in nonlocal field theories containing infinitely many derivatives. Such constructions arise naturally in string field theory and also in a number of toy models, such as the p-adic string. After reviewing the complications (ghosts and instabilities) that arise when working with high derivative theories we discuss the initial value problem and perturbative stability of theories with infinitely many derivatives. Next, we examine the inflationary dynamics and phenomenology of such theories. Nonlocal inflation can proceed even when the potential is naively too steep and generically predicts large nongaussianity in the Cosmic Microwave Background.

  18. Modelling of Nonlocal Effects in Electromechanical Nano-Switches

    OpenAIRE

    Toropova, M. M.

    2010-01-01

    Dielectric nano-swithes made of the materials that exhibit piezoelectric and/or flexoelectric properties with significant electro-mechanical coupling are considered. In this case, a nonuniform strain field may locally break inversion symmetry and induce polarization even in nonpiezoelectrics. At reducing dimensions to the nanoscale, the flexoelectric effect demonstrates the nonlocality of the dielectric materials and plays more significant role than piezoelectric effect. The flexoelectric eff...

  19. The charge-asymmetric nonlocally-determined local-electric (CANDLE) solvation model

    CERN Document Server

    Sundararaman, Ravishankar

    2014-01-01

    Many important applications of electronic structure methods involve molecules or solid surfaces in a solvent medium. Since explicit treatment of the solvent in such methods is usually not practical, calculations often employ continuum solvation models to approximate the effect of the solvent. Previous solvation models either involve a parametrization based on atomic radii, which limits the class of applicable solutes, or based on solute electron density, which is more general but less accurate, especially for charged systems. We develop an accurate and general solvation model that includes a cavity that is a nonlocal functional of both solute electron density and potential, local dielectric response on this nonlocally-determined cavity, and nonlocal approximations to the cavity-formation and dispersion energies. The dependence of the cavity on the solute potential enables an explicit treatment of the solvent charge asymmetry. With only three parameters per solvent, this `CANDLE' model simultaneously reproduce...

  20. Nonlocal nonlinear refractive index of gold nanoparticles synthesized by ascorbic acid reduction: comparison of fitting models.

    Science.gov (United States)

    Balbuena Ortega, A; Arroyo Carrasco, M L; Méndez Otero, M M; Gayou, V L; Delgado Macuil, R; Martínez Gutiérrez, H; Iturbe Castillo, M D

    2014-12-12

    In this paper, the nonlinear refractive index of colloidal gold nanoparticles under continuous wave illumination is investigated with the z-scan technique. Gold nanoparticles were synthesized using ascorbic acid as reductant, phosphates as stabilizer and cetyltrimethylammonium chloride (CTAC) as surfactant agent. The nanoparticle size was controlled with the CTAC concentration. Experiments changing incident power and sample concentration were done. The experimental z-scan results were fitted with three models: thermal lens, aberrant thermal lens and the nonlocal model. It is shown that the nonlocal model reproduces with exceptionally good agreement; the obtained experimental behaviour.

  1. Fragmentation functions of pions and kaons in the nonlocal chiral quark model

    Directory of Open Access Journals (Sweden)

    Kao Chung Wen

    2014-03-01

    Full Text Available We investigate the unpolarized pion and kaon fragmentation functions using the nonlocal chiral-quark model. In this model the interactions between the quarks and pseudoscalar mesons is manifested nonlocally. In addition, the explicit flavor SU(3 symmetry breaking effect is taken into account in terms of the current quark masses. The results of our model are evaluated to higher Q2 value Q2 = 4 GeV2 by the DGLAP evolution. Then we compare them with the empirical parametrizations. We find that our results are in relatively good agreement with the empirical parametrizations and the other theoretical estimations.

  2. Cosmological perturbations in SFT inspired non-local scalar field models

    Energy Technology Data Exchange (ETDEWEB)

    Koshelev, Alexey S. [Vrije Universiteit Brussel and The International Solvay Institutes, Theoretische Natuurkunde, Brussels (Belgium); Vernov, Sergey Yu. [Instituto de Ciencias del Espacio (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Bellaterra, Barcelona (Spain); Lomonosov Moscow State University, Theoretical High Energy Physics Division, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation)

    2012-10-15

    We study cosmological perturbations in models with a single non-local scalar field originating from the string field theory description of the rolling tachyon dynamics. We construct the equation for the energy density perturbations of the non-local scalar field and explicitly prove that for the free field it is identical to a system of local cosmological perturbation equations in a particular model with multiple (maybe infinitely many) local free scalar fields. We also show that vector and tensor perturbations are absent in this set-up. (orig.)

  3. Pion-to-photon transition distribution amplitudes in the non-local chiral quark model

    CERN Document Server

    Kotko, Piotr

    2008-01-01

    We apply the non-local chiral quark model to study vector and axial pion-to-photon transition amplitudes that are needed as a nonperturbative input to estimate the cross section of pion annihilation into the real and virtual photon. We use a simple form of the non-locality that allows to perform all calculations in the Minkowski space and guaranties polynomiality of the TDA's. We note only residual dependence on the precise form of the cut-off function, however vector TDA that is symmetric in skewedness parameter in the local quark model is no longer symmetric in the non-local case. We calculate also the transition form-factors and compare them with existing experimental parametrizations.

  4. Vector meson condensation in a pion superfluid

    Science.gov (United States)

    Brauner, Tomáš; Huang, Xu-Guang

    2016-11-01

    We revisit the suggestion that charged ρ -mesons undergo Bose-Einstein condensation in isospin-rich nuclear matter. Using a simple version of the Nambu-Jona-Lasinio (NJL) model, we conclude that ρ -meson condensation is either avoided or postponed to isospin chemical potentials much higher than the ρ -meson mass as a consequence of the repulsive interaction with the preformed pion condensate. In order to support our numerical results, we work out a linear sigma model for pions and ρ -mesons, showing that the two models lead to similar patterns of medium dependence of meson masses. As a byproduct, we analyze in detail the mapping between the NJL model and the linear sigma model, focusing on conditions that must be satisfied for a quantitative agreement between the models.

  5. Vector meson condensation in a pion superfluid

    CERN Document Server

    Brauner, Tomas

    2016-01-01

    We revisit the suggestion that charged rho-mesons undergo Bose-Einstein condensation in isospin-rich nuclear matter. Using a simple version of the Nambu-Jona-Lasinio (NJL) model, we conclude that rho-meson condensation is either avoided or postponed to isospin chemical potentials much higher than the rho-meson mass as a consequence of the repulsive interaction with the preformed pion condensate. In order to support our numerical results, we work out a linear sigma model for pions and rho-mesons, showing that the two models lead to similar patterns of medium dependence of meson masses. As a byproduct, we analyze in detail the mapping between the NJL model and the linear sigma model, focusing on conditions that must be satisfied for a quantitative agreement between the models.

  6. Wilson Fermions with Four Fermion Interactions

    CERN Document Server

    Rantaharju, Jarno; Hietanen, Ari; Pica, Claudio; Sannino, Francesco

    2015-01-01

    We present a lattice study of a four fermion theory, known as Nambu Jona-Lasinio (NJL) theory, via Wilson fermions. Four fermion interactions naturally occur in several extensions of the Standard Model as a low energy parameterisation of a more fundamental theory. In models of dynamical electroweak symmetry breaking these operators, at an effective level, are used to endow the Standard Model fermions with masses. Furthermore these operators, when sufficiently strong, can drastically modify the fundamental composite dynamics by, for example, turning a strongly coupled infrared conformal theory into a (near) conformal one with desirable features for model building. As first step, we study spontaneous chiral symmetry breaking for the lattice version of the NJL model.

  7. Nonlocal multi-scale traffic flow models: analysis beyond vector spaces

    Directory of Open Access Journals (Sweden)

    Peter E. Kloeden

    2016-08-01

    Full Text Available Abstract Realistic models of traffic flow are nonlinear and involve nonlocal effects in balance laws. Flow characteristics of different types of vehicles, such as cars and trucks, need to be described differently. Two alternatives are used here, $$L^p$$ L p -valued Lebesgue measurable density functions and signed Radon measures. The resulting solution spaces are metric spaces that do not have a linear structure, so the usual convenient methods of functional analysis are no longer applicable. Instead ideas from mutational analysis will be used, in particular the method of Euler compactness will be applied to establish the well-posedness of the nonlocal balance laws. This involves the concatenation of solutions of piecewise linear systems on successive time subintervals obtained by freezing the nonlinear nonlocal coefficients to their values at the start of each subinterval. Various compactness criteria lead to a convergent subsequence. Careful estimates of the linear systems are needed to implement this program.

  8. The effect of dynamical quark mass on the calculation of a strange quark star's structure

    Institute of Scientific and Technical Information of China (English)

    Gholam Hossein Bordbar; Babak Ziaei

    2012-01-01

    We discuss the dynamical behavior of strange quark matter components,in particular the effects of density dependent quark mass on the equation of state of strange quark matter.The dynamical masses of quarks are computed within the Nambu-Jona-Lasinio model,then we perform strange quark matter calculations employing the MIT bag model with these dynamical masses.For the sake of comparing dynamical mass interaction with QCD quark-quark interaction,we consider the one-gluon-exchange term as the effective interaction between quarks for the MIT bag model.Our dynamical approach illustrates an improvement in the obtained equation of state values.We also investigate the structure of the strange quark star using TolmanOppenheimer-Volkoff equations for all applied models.Our results show that dynamical mass interaction leads to lower values for gravitational mass.

  9. Nonlocal continuum-based modeling of mechanical characteristics of nanoscopic structures

    Energy Technology Data Exchange (ETDEWEB)

    Rafii-Tabar, Hashem, E-mail: rafii-tabar@nano.ipm.ac.ir [Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ghavanloo, Esmaeal, E-mail: ghavanloo@shirazu.ac.ir [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of); Fazelzadeh, S. Ahmad [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of)

    2016-06-06

    Insight into the mechanical characteristics of nanoscopic structures is of fundamental interest and indeed poses a great challenge to the research communities around the world. These structures are ultra fine in size and consequently performing standard experiments to measure their various properties is an extremely difficult and expensive endeavor. Hence, to predict the mechanical characteristics of the nanoscopic structures, different theoretical models, numerical modeling techniques, and computer-based simulation methods have been developed. Among several proposed approaches, the nonlocal continuum-based modeling is of particular significance because the results obtained from this modeling for different nanoscopic structures are in very good agreement with the data obtained from both experimental and atomistic-based studies. A review of the essentials of this model together with its applications is presented here. Our paper is a self contained presentation of the nonlocal elasticity theory and contains the analysis of the recent works employing this model within the field of nanoscopic structures. In this review, the concepts from both the classical (local) and the nonlocal elasticity theories are presented and their applications to static and dynamic behavior of nanoscopic structures with various morphologies are discussed. We first introduce the various nanoscopic structures, both carbon-based and non carbon-based types, and then after a brief review of the definitions and concepts from classical elasticity theory, and the basic assumptions underlying size-dependent continuum theories, the mathematical details of the nonlocal elasticity theory are presented. A comprehensive discussion on the nonlocal version of the beam, the plate and the shell theories that are employed in modeling of the mechanical properties and behavior of nanoscopic structures is then provided. Next, an overview of the current literature discussing the application of the nonlocal models

  10. Nonlocal continuum-based modeling of mechanical characteristics of nanoscopic structures

    Science.gov (United States)

    Rafii-Tabar, Hashem; Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad

    2016-06-01

    Insight into the mechanical characteristics of nanoscopic structures is of fundamental interest and indeed poses a great challenge to the research communities around the world. These structures are ultra fine in size and consequently performing standard experiments to measure their various properties is an extremely difficult and expensive endeavor. Hence, to predict the mechanical characteristics of the nanoscopic structures, different theoretical models, numerical modeling techniques, and computer-based simulation methods have been developed. Among several proposed approaches, the nonlocal continuum-based modeling is of particular significance because the results obtained from this modeling for different nanoscopic structures are in very good agreement with the data obtained from both experimental and atomistic-based studies. A review of the essentials of this model together with its applications is presented here. Our paper is a self contained presentation of the nonlocal elasticity theory and contains the analysis of the recent works employing this model within the field of nanoscopic structures. In this review, the concepts from both the classical (local) and the nonlocal elasticity theories are presented and their applications to static and dynamic behavior of nanoscopic structures with various morphologies are discussed. We first introduce the various nanoscopic structures, both carbon-based and non carbon-based types, and then after a brief review of the definitions and concepts from classical elasticity theory, and the basic assumptions underlying size-dependent continuum theories, the mathematical details of the nonlocal elasticity theory are presented. A comprehensive discussion on the nonlocal version of the beam, the plate and the shell theories that are employed in modeling of the mechanical properties and behavior of nanoscopic structures is then provided. Next, an overview of the current literature discussing the application of the nonlocal models

  11. A Nagumo-type model for competing populations with nonlocal coupling.

    Science.gov (United States)

    Tanzy, M C; Volpert, V A; Bayliss, A; Nehrkorn, M E

    2015-05-01

    We consider a model of two competing species with nonlocal competition for resources. The net birthrate is cubic, so that the model allows simulation of the Allee effect, whereby extinction is stable and intermediate populations promote growth, while saturation occurs via cubic competition terms. The model includes both interspecies and intraspecies nonlocal competition which enters via convolution integrals with a specified asymmetric competition kernel function. We introduce two parameters, δ, describing the extent of the coupling, with δ = 0 corresponding to local coupling, and α, describing the extent of the asymmetry, with α = 0 corresponding to symmetric nonlocal interactions. We consider the case where the local model admits a stable coexistence (populations of both species positive) equilibrium solution. We perform a linear stability analysis and show that this solution can be destabilized by sufficient nonlocality, i.e., when δ increases beyond a critical value. We then consider nonlinear patterns, far from the stability boundary. We show that nonlinear patterns consist of arrays of islands, regions of nonzero population, separated by deadzones, where the populations are essentially extinct, (with the array propagating in the case α ≠ 0). The predominant effect of the cubic model is that the islands for the two species are disjoint, so that each species lives in the deadzone of the other species. In addition, some patterns involve both hospitable and inhospitable deadzones, so that islands form in only some of the deadzones.

  12. Improved non-local electron thermal transport model for two-dimensional radiation hydrodynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Duc; Moses, Gregory [University of Wisconsin—Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Delettrez, Jacques [Laboratory for Laser Energetics of the University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

    2015-08-15

    An implicit, non-local thermal conduction algorithm based on the algorithm developed by Schurtz, Nicolai, and Busquet (SNB) [Schurtz et al., Phys. Plasmas 7, 4238 (2000)] for non-local electron transport is presented and has been implemented in the radiation-hydrodynamics code DRACO. To study the model's effect on DRACO's predictive capability, simulations of shot 60 303 from OMEGA are completed using the iSNB model, and the computed shock speed vs. time is compared to experiment. Temperature outputs from the iSNB model are compared with the non-local transport model of Goncharov et al. [Phys. Plasmas 13, 012702 (2006)]. Effects on adiabat are also examined in a polar drive surrogate simulation. Results show that the iSNB model is not only capable of flux-limitation but also preheat prediction while remaining numerically robust and sacrificing little computational speed. Additionally, the results provide strong incentive to further modify key parameters within the SNB theory, namely, the newly introduced non-local mean free path. This research was supported by the Laboratory for Laser Energetics of the University of Rochester.

  13. Nonlocal shear deformable shell model for bending buckling of microtubules embedded in an elastic medium

    Energy Technology Data Exchange (ETDEWEB)

    Shen Huishen, E-mail: hsshen@mail.sjtu.edu.c [Department of Engineering Mechanics, Shanghai Jiao Tong University, Shanghai 200030 (China); State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2010-08-30

    A nonlocal shear deformable shell model is developed for buckling of microtubules embedded in an elastic matrix of cytoplasm under bending in thermal environments. The results reveal that the lateral constraint has a significant effect on the buckling moments of a microtubule when the foundation stiffness is sufficiently large.

  14. Traveling Wave Solutions for a Delayed SIRS Infectious Disease Model with Nonlocal Diffusion and Nonlinear Incidence

    Directory of Open Access Journals (Sweden)

    Xiaohong Tian

    2014-01-01

    Full Text Available A delayed SIRS infectious disease model with nonlocal diffusion and nonlinear incidence is investigated. By constructing a pair of upper-lower solutions and using Schauder's fixed point theorem, we derive the existence of a traveling wave solution connecting the disease-free steady state and the endemic steady state.

  15. Electromagnetic superconductivity of vacuum induced by strong magnetic field

    CERN Document Server

    Chernodub, M N

    2012-01-01

    The quantum vacuum may become an electromagnetic superconductor in the presence of a strong external magnetic field of the order of 10^{16} Tesla. The magnetic field of the required strength (and even stronger) is expected to be generated for a short time in ultraperipheral collisions of heavy ions at the Large Hadron Collider. The superconducting properties of the new phase appear as a result of a magnetic-field-assisted condensation of quark-antiquark pairs with quantum numbers of electrically charged rho mesons. We discuss similarities and differences between the suggested superconducting state of the quantum vacuum, a conventional superconductivity and the Schwinger pair creation. We argue qualitatively and quantitatively why the superconducting state should be a natural ground state of the vacuum at the sufficiently strong magnetic field. We demonstrate the existence of the superconducting phase using both the Nambu-Jona-Lasinio model and an effective bosonic model based on the vector meson dominance (th...

  16. Thermodynamics of quark matter with a chiral imbalance

    Science.gov (United States)

    Farias, Ricardo L. S.; Duarte, Dyana C.; Krein, Gastão; Ramos, Rudnei O.

    2016-10-01

    We show how a scheme of rewriting a divergent momentum integral can conciliate results obtained with the Nambu-Jona-Lasinio model and recent lattice results for the chiral transition in the presence of a chiral imbalance in quark matter. Purely vacuum contributions are separated from medium-dependent regularized momentum integrals in such a way that one is left with ultraviolet divergent momentum integrals that depend on vacuum quantities only. The scheme is applicable to other commonly used effective models to study quark matter with a chiral imbalance, it allows us to identify the source of their difficulties in reproducing the qualitative features of lattice results, and enhances their predictability and uses in other applications.

  17. SU(N) affine Toda solitons and breathers from transparent Dirac potentials

    CERN Document Server

    Thies, Michael

    2016-01-01

    Transparent scalar and pseudoscalar potentials in the one-dimensional Dirac equation play an important role as self-consistent mean fields in 1+1 dimensional four-fermion theories (Gross-Neveu, Nambu-Jona Lasinio models) and quasi-one dimensional superconductors (Bogoliubov-De Gennes equation). Here, we show that they also serve as seed to generate a large class of classical multi-soliton and multi-breather solutions of su(N) affine Toda field theories, including the Lax representation and the corresponding vector. This generalizes previous findings about the relationship between real kinks in the Gross-Neveu model and classical solitons of the sinh-Gordon equation to complex twisted kinks.

  18. Spin-dependent structure functions in nuclear matter and the polarized EMC effect.

    Science.gov (United States)

    Cloët, I C; Bentz, W; Thomas, A W

    2005-07-29

    An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu--Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F2N(A)/F2N ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g1p(A), we find that the ratio g1p(A)/g1p differs significantly from unity, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which, if confirmed experimentally, will reveal much about the quark structure of nuclear matter.

  19. Isovector EMC effect and the NuTeV anomaly.

    Science.gov (United States)

    Cloët, I C; Bentz, W; Thomas, A W

    2009-06-26

    A neutron or proton excess in nuclei leads to an isovector-vector mean field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable. We show that this result leads to an additional correction to the NuTeV measurement of sin2thetaW. The sign of this correction is largely model independent and acts to reduce their result. Explicit calculation in nuclear matter within a covariant and confining Nambu-Jona-Lasinio model predicts that this vector field correction may account for a substantial fraction of the NuTeV anomaly. We are therefore led to offer a new interpretation of the NuTeV measurement, namely, that it provides further evidence for the medium modification of the bound nucleon wave function.

  20. Inverse magnetic catalysis in dense holographic matter

    CERN Document Server

    Preis, Florian; Schmitt, Andreas

    2010-01-01

    We study the chiral phase transition in a magnetic field at finite temperature and chemical potential within the Sakai-Sugimoto model, a holographic top-down approach to (large-N_c) QCD. We consider the limit of a small separation of the flavor D8-branes, which corresponds to a dual field theory comparable to a Nambu-Jona Lasinio (NJL) model. Mapping out the surface of the chiral phase transition in the parameter space of magnetic field strength, quark chemical potential, and temperature, we find that for small temperatures the addition of a magnetic field decreases the critical chemical potential for chiral symmetry restoration - in contrast to the case of vanishing chemical potential where, in accordance with the familiar phenomenon of magnetic catalysis, the magnetic field favors the chirally broken phase. This "inverse magnetic catalysis" (IMC) appears to be associated with a previously found magnetic phase transition within the chirally symmetric phase that shows an intriguing similarity to a transition ...

  1. Isospin dependence of EMC effect explains NuTeV anomaly

    Energy Technology Data Exchange (ETDEWEB)

    Cloet, Ian; Bentz, Wolfgang; Thomas, Anthony

    2009-01-01

    A neutron or proton excess in nuclei leads to an isovector-vector mean-field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable. We show that this result leads to an additional correction to the NuTeV measurement of sin^2Theta_W. The sign of this correction is largely model independent and acts to reduce the NuTeV result. Explicit calculation within a covariant and confining Nambu Jona-Lasinio model predicts that this vector field correction accounts for approximately two-thirds of the NuTeV anomaly. We are therefore led to offer a new interpretation of the NuTeV measurement, namely, that it is further evidence for the medium modification of the bound nucleon wavefunction.

  2. Hadronic molecules with a ${\\bar{D}}$ meson in a medium

    CERN Document Server

    Caramés, T F; Klein, G; Tsushima, K; Vijande, J; Valcarce, A

    2016-01-01

    We study the effect of a hot and dense medium on the binding energy of hadronic molecules with open-charm mesons. We focus on a recent chiral quark-model-based prediction of a molecular state in the $N \\bar D$ system. We analyze how the two-body thresholds and the hadron-hadron interactions are modified when quark and meson masses and quark-meson couplings change in a function of the temperature and baryon density according to predictions of the Nambu--Jona-Lasinio model. We find that in some cases the molecular binding is enhanced in medium as compared to their free-space binding. We discuss the consequences of our findings for the search for exotic hadrons in high-energy heavy-ion collisions as well as in the forthcoming facilities FAIR or J-PARC.

  3. Interacting fermions in rotation: chiral symmetry restoration, moment of inertia and thermodynamics

    CERN Document Server

    Chernodub, M N

    2016-01-01

    We study rotating fermionic matter at finite temperature in the framework of the Nambu-Jona-Lasinio model. In order to respect causality the rigidly rotating system must be bound by a cylindrical boundary with appropriate boundary conditions that confine the fermions inside the cylinder. We show the finite geometry with the MIT boundary conditions affects strongly the phase structure of the model leading to three distinct regions characterized by explicitly broken (gapped), partially restored (nearly gapless) and spontaneously broken (gapped) phases at, respectively, small, moderate and large radius of the cylinder. The presence of the boundary leads to specific steplike irregularities of the chiral condensate as functions of coupling constant, temperature and angular frequency. These steplike features have the same nature as the Shubnikov-de Haas oscillations with the crucial difference that they occur in the absence of both external magnetic field and Fermi surface. At finite temperature the rotation leads ...

  4. Estimating transport coefficients in hot and dense quark matter

    CERN Document Server

    Deb, Paramita; Mishra, Hiranmaya

    2016-01-01

    We compute the transport coefficients-- namely, coefficients of shear and bulk viscosity as well as thermal conductivity for hot and dense quark matter. The calculations are performed within the Nambu Jona Lasinio (NJL) model. The estimation of the transport coefficients is made using a quasi particle approach of solving Boltzmann kinetic equation within the relaxation time approximation. The transition rates are calculated in a manifestly covariant manner to estimate the thermal averaged cross sections for quark quark as well as quark anti-quark scattering. The calculations are performed for finite chemical potential also. Within the parameters of the model, the ratio of shear viscosity to entropy density has a minimum at the Mott transition temperature. At vanishing chemical potential, the ratio of bulk viscosity to entropy density, on the other hand, decrease with temperature with a sharp decrease near the critical temperature and vanishes beyond it. At finite chemical potential, however, it increases slow...

  5. Chiral symmetry and scalar meson in hadron and nuclear physics

    CERN Document Server

    Kunihiro, T

    1995-01-01

    After giving a short introduction to the Nambu-Jona-Lasinio model with an anomaly term, we show the importance of the scalar-scalar correlation in the low-energy hadron dynamics, which correlation may be summarized by a scalar-isoscalar meson, the sigma meson. The discussion is based on the chiral quark model with the sigma-meson degrees of freedom. Possible experiments are proposed to produce the elusive meson in a nucleus and detect it. In relation to a precursory soft mode for the chiral transition, the reason is clarified why the dynamic properties of the superconductor may be described by the diffusive time-dependent Ginzburg-Landau (TDGL) equation. We indicate the chiral symmetry plays a significant role also in nuclei; one may say that the stability of nuclei is due to the chiral symmetry of QCD.

  6. The composite Nambu-Goldstone-Higgs

    CERN Document Server

    Panico, Giuliano

    2015-01-01

    The Hierarchy Problem is arguably the most important guiding principle concerning the extension to high-energy scales of the Standard Model (SM) of Fundamental Interactions. Every scenario for addressing this issue unavoidably predicts new physics in the TeV energy range, which is currently being probed directly by the LHC experimental program. Among the possible solutions to the Hierarchy Problem, the scenario of a composite Higgs boson is a very simple idea and a rather plausible picture has emerged over the years by combining the following ingredients: First, the Higgs must be a (pseudo-) Nambu-Goldstone boson, rather than a generic hadron of the new strong sector. Second, through the so-called ‘partial compositeness’, SM particles mix with strong sector resonances with suitable quantum numbers, so that they become a linear combination of elementary and composite degrees of freedom. Recently, general descriptions of the Composite Higgs Scenario were developed which successfully capture the relevant fea...

  7. Hydrodynamic Nambu Brackets derived by Geometric Constraints

    CERN Document Server

    Blender, Richard

    2015-01-01

    A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fractional Poisson equations for the stream-function are also included as results from the derivation. The formalism is extended to a hydrodynamic system coupled to a second degree of freedom, with the Rayleigh-B\\'{e}nard convection as an example. This system is reformulated in terms of constitutive conservation laws with two additive brackets which represent individual processes: a first representing inviscid 2D hydrodynamics, and a second representing the coupling between hydrodynamics and thermodynamics. The results can b...

  8. Spin polarization in high density quark matter under a strong external magnetic field

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; Da Providência, João; Providência, Constança

    2016-01-01

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor......-type interaction under the strong external magnetic field, it is shown that a quark spin polarized phase is realized in all regions of the quark chemical potential under consideration within the lowest Landau level approximation. In the axial-vector-type interaction, it is also shown that the quark spin polarized...... phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs....

  9. Spin polarization in high density quark matter under a strong external magnetic field

    CERN Document Server

    Tsue, Yasuhiko; Providencia, Constanca; Yamamura, Masatoshi; Bohr, Henrik

    2016-01-01

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the Nambu-Jona-Lasinio model with axial vector-type four-point interaction or tensor-type four-point interaction between quarks. In the axial vector-type interaction, it is shown that a quark spin polarized phase is realized in all region of the quark chemical potential under a strong external magnetic field within the lowest Landau level approximation. Each phase is characterized by the chiral condensate or dynamical quark mass. On the other hand, in the tensor-type interaction, it is also shown that the quark spin polarized phase does not appear even if there exists the strong external magnetic field. However, if the anomalous magnetic moment of quark is taken into account, it may be possible to realize the quark spin polarized phase.

  10. Chiral phase transition and Schwinger mechanism in a pure electric field

    CERN Document Server

    Cao, Gaoqing

    2016-01-01

    We systematically study the chiral symmetry breaking and restoration in the presence of a pure electric field in the Nambu--Jona-Lasinio (NJL) model at finite temperature and baryon chemical potential. In addition, we also study the effect of the chiral phase transition on the charged pair production due to the Schwinger mechanism. For these purposes, a general formalism for parallel electric and magnetic fields is developed at finite temperature and chemical potential for the first time. In the pure electric field limit $B\\rightarrow0$, we compute the order parameter, the transverse-to-longitudinal ratio of the Goldstone mode velocities, and the Schwinger pair production rate as functions of the electric field. The inverse catalysis effect of the electric field to chiral symmetry breaking is recovered. And the Goldstone mode is find to disperse anisotropically such that the transverse velocity is always smaller than the longitudinal one, especially at nonzero temperature and baryon chemical potential. As exp...

  11. Relativistic Many-Body Hamiltonian Approach to Mesons

    CERN Document Server

    Llanes-Estrada, F J; Llanes-Estrada, Felipe J.; Cotanch, Stephen R.

    2002-01-01

    We represent QCD at the hadronic scale by means of an effective Hamiltonian, $H$, formulated in the Coulomb gauge. As in the Nambu-Jona-Lasinio model, chiral symmetry is explicity broken, however our approach is renormalizable and also includes confinement through a linear potential with slope specified by lattice gauge theory. This interaction generates an infrared integrable singularity and we detail the computationally intensive procedure necessary for numerical solution. We focus upon applications for the $u, d, s$ and $c$ quark flavors and compute the mass spectrum for the pseudoscalar, scalar and vector mesons. We also perform a comparative study of alternative many-body techniques for approximately diagonalizing $H$: BCS for the vacuum ground state; TDA and RPA for the excited hadron states. The Dirac structure of the field theoretical Hamiltonian naturally generates spin-dependent interactions, including tensor, spin-orbit and hyperfine, and we clarify the degree of level splitting due to both spin an...

  12. Baryon formation and dissociation in dense hadronic and quark matter

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jincheng [Interdisciplinary Center for Theoretical Study and Department of Modern Physics, University of Science and Technology of China, Anhui 230026 (China); Institute for Theoretical Physics, Johann Wolfgang Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Wang Qun, E-mail: qunwang@ustc.edu.cn [Interdisciplinary Center for Theoretical Study and Department of Modern Physics, University of Science and Technology of China, Anhui 230026 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences, Beijing 100049 (China); Rischke, Dirk H. [Institute for Theoretical Physics, Johann Wolfgang Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany)

    2011-10-19

    We study the formation of baryons as composed of quarks and diquarks in hot and dense hadronic matter in a Nambu-Jona-Lasinio (NJL)-type model. We first solve the Dyson-Schwinger equation for the diquark propagator and then use this to solve the Dyson-Schwinger equation for the baryon propagator. We find that stable baryon resonances exist only in the phase of broken chiral symmetry. In the chirally symmetric phase, we do not find a pole in the baryon propagator. In the color-superconducting phase, there is a pole, but it has a large decay width. The diquark does not need to be stable in order to form a stable baryon, a feature typical for so-called Borromean states. Varying the strength of the diquark coupling constant, we also find similarities to the properties of an Efimov state.

  13. $\\pi_0$ pole mass calculation in a strong magnetic field and lattice constraints

    CERN Document Server

    Avancini, Sidney S; Pinto, Marcus Benghi; Tavares, William R; Timóteo, Varese S

    2016-01-01

    The $\\pi_0$ neutral meson pole mass is calculated in a strongly magnetized medium using the SU(2) Nambu-Jona-Lasinio model within the random phase approximation (RPA) at zero temperature and zero baryonic density. We employ a magnetic field dependent coupling $G(eB)$ fitted to reproduce lattice QCD results for the quark condensates. Divergent quantities are handled with a magnetic field independent regularization scheme in order to avoid unphysical oscillations. A comparison between the running and the fixed couplings reveals that the former produces results much closer to the predictions from recent lattice calculations. In particular, we find that the $\\pi_0$ meson mass systematically decreases when the magnetic field increases while the scalar mass remains almost constant. We also investigate how the magnetic background influences other mesonic properties such as $f_{{\\pi}_0}$ and $g_{\\pi_0 q q}$.

  14. Restoration of UA(1) symmetry and meson spectrum in hot or dense matter

    Science.gov (United States)

    Costa, P.; Ruivo, M. C.; de Sousa, C. A.; Kalinovsky, Yu. L.

    2005-06-01

    We explore the effects of breaking and restoration of chiral and axial symmetries using an extended three-flavor Nambu-Jona-Lasinio model that incorporates explicitly the axial anomaly through the 't Hooft interaction. We implement a temperature (density) dependence of the anomaly coefficient motivated by lattice results for the topological susceptibility. The spectrum of scalar and pseudoscalar mesons is analyzed bearing in mind the identification of chiral partners and the study of its convergence. We also concentrate on the behavior of the mixing angles that give us relevant information on the issue under discussion. The results suggest that the axial part of the symmetry is restored before the possible restoration of the full U(3)⊗U(3) chiral symmetry might occur.

  15. Restoration of U$_A$(1) symmetry and meson spectrum in hot or dense matter

    CERN Document Server

    Costa, P; De Sousa, C A; Kalinovskii, Yu L; Costa, Pedro; Kalinovsky, Yu. L.

    2005-01-01

    We explore the effects of breaking and restoration of chiral and axial symmetries using an extended three-flavor Nambu-Jona-Lasinio model that incorporates explicitly the axial anomaly through the 't Hooft interaction. We implement a temperature (density) dependence of the anomaly coefficient motivated by lattice results for the topological susceptibility. The spectrum of scalar and pseudoscalar mesons is analyzed bearing in mind the identification of chiral partners and the study of its convergence. We also concentrate on the behavior of the mixing angles that give us relevant information on the issue under discussion. The results suggest that the axial part of the symmetry is restored before the possible restoration of the full U(3)$\\otimes$U(3) chiral symmetry might occur.

  16. Chiral Relaxation Time at the Chiral Crossover of Quantum Chromodynamics

    CERN Document Server

    Ruggieri, M; Chernodub, M

    2016-01-01

    We study microscopic processes responsible for chirality flips in the thermal bath of Quantum Chromodynamics at finite temperature and zero baryon chemical potential. We focus on the temperature range where the crossover from chirally broken phase to quark-gluon plasma takes place, namely $T \\simeq (150, 200)$ MeV. The processes we consider are quark-quark scatterings mediated by collective excitations with the quantum number of pions and $\\sigma$-meson, hence we refer to these processes simply as \\sugg{to} one-pion (one-$\\sigma$) exchange\\sugg{s}. We use a Nambu-Jona-Lasinio model to compute equilibrium properties of the thermal bath, as well as the relevant scattering kernel to be used in the collision integral to estimate the chiral relaxation time $\\tau$. We find $\\tau\\simeq 0.1 \\div 1$ fm/c around the chiral crossover.

  17. Neutrino emissivities and bulk viscosity in neutral two-flavor quark matter

    Science.gov (United States)

    Berdermann, J.; Blaschke, D.; Fischer, T.; Kachanovich, A.

    2016-12-01

    We study thermodynamic and transport properties for the isotropic color-spin-locking (iso-CSL) phase of two-flavor superconducting quark matter under compact star constraints within a Nambu-Jona-Lasinio-type chiral quark model. Chiral symmetry breaking and the phase transition to superconducting quark matter leads to a density dependent change of quark masses, chemical potentials, and diquark gap. A self-consistent treatment of these physical quantities influences the microscopic calculations of transport properties. We present results for the iso-CSL direct URCA emissivities and bulk viscosities, which fulfil the constraints on quark matter derived from cooling and rotational evolution of compact stars. We compare our results with the phenomenologically successful, but yet heuristic 2 SC +X phase. We show that the microscopically founded iso-CSL phase can replace the purely phenomenological 2 SC +X phase in modern simulations of the cooling evolution for compact stars with color-superconducting quark matter interior.

  18. Effects of rotation and boundaries on chiral symmetry breaking of relativistic fermions

    Science.gov (United States)

    Chernodub, M. N.; Gongyo, Shinya

    2017-05-01

    In order to avoid unphysical causality-violating effects, any rigidly rotating system must be bounded in directions transverse to the axis of rotation. We demonstrate that this requirement implies substantial dependence of properties of the relativistically rotating system on the boundary conditions. We consider a system of interacting fermions described by the Nambu-Jona-Lasinio model in a space bounded by the cylindrical surface of the finite radius. In order to confine the fermions inside the cylinder, we impose "chiral" MIT boundary conditions on its surface. These boundary conditions are parametrized by a continuous chiral angle Θ . We find that, at any value of Θ , the chiral restoration temperature Tc decreases as a quadratic function of the angular frequency Ω . However, the position and the slope of the critical curve Tc=Tc(Ω ) in the phase diagram depend noticeably on the value of the chiral angle.

  19. Influence of the nuclear equation of state on the hadron-quark phase transition in neutron stars

    Institute of Scientific and Technical Information of China (English)

    YANG Fang; SHEN Hong

    2008-01-01

    We study the hadron-quark phase transition in the interior of neutron stars, and examine the influence of the nuclear equation of state on the phase transition and neutron star properties. The relativistic mean field theory with several parameter sets is used to construct the nuclear equation of state, while the Nambu-Jona-Lasinio model is used for the description of the deconfined quark phase. Our results show that a harder nuclear equation of state leads to an earlier onset of a mixed phase of hadronic and quark matter. We find that a massive neutron star possesses a mixed phase core, but it is not dense enough to possess a pure quark core.

  20. Possible formation of high temperature superconductor at early stage of heavy-ion collisions

    CERN Document Server

    Liu, Hao; Chernodub, Maxim; Huang, Mei

    2016-01-01

    We investigate the effect of the inverse magnetic catalysis (IMC) on the charged $\\rho$ meson condensation at finite temperature in the framework of the Nambu--Jona-Lasinio model, where mesons are calculated to the leading order of $1/N_c$ expansion by summing up infinity quark-loops. IMC for chiral condensate has been considered in three different ways, i.e. fitting Lattice data, using the running coupling constant and introducing the chiral chemical potential, respectively. It is observed that, with no IMC effect included, the critical magnetic field $eB_c$ for charged $\\rho$ condensation increases monotonically with the temperature. However, including IMC substantially affects the polarized charged $\\rho$ condensation around the critical temperature $T_c$ of chiral phase transition, the critical magnetic field $eB_c$ for charged $\\rho$ condensation decreases with the temperature firstly, reaches to a minimum value around $T_c$, then increases with the temperature. Our calculation indicates that the charged...

  1. Nonviolent nonlocality

    CERN Document Server

    Giddings, Steven B

    2012-01-01

    If quantum mechanics governs nature, black holes must evolve unitarily, providing a powerful constraint on the dynamics of quantum gravity. Such evolution apparently must in particular be nonlocal, when described from the usual semiclassical geometric picture, in order to transfer quantum information into the outgoing state. While such transfer from a disintegrating black hole has the dangerous potential to be violent to generic infalling observers, this paper proposes the existence of a more innocuous form of information transfer, to relatively soft modes in the black hole atmosphere. Simplified models for such nonlocal transfer are described and parameterized, within a possibly more basic framework of a Hilbert tensor network. Sufficiently sensitive measurements by infalling observers may detect departures from Hawking's predictions, and in generic models black holes decay more rapidly. Constraints of consistency -- internally and with known and expected features of physics -- restrict the form of informati...

  2. Non-local approach to kinetic effects on parallel transport in fluid models of the scrape-off layer

    CERN Document Server

    Omotani, John

    2013-01-01

    By using a non-local model, fluid simulations can capture kinetic effects in the parallel electron heat-flux better than is possible using flux limiters in the usual diffusive models. Non-local and diffusive models are compared using a test case representative of an ELM crash in the JET SOL, simulated in one dimension. The non-local model shows substantially enhanced electron temperature gradients, which cannot be achieved using a flux limiter. The performance of the implementation, in the BOUT++ framework, is also analysed to demonstrate its suitability for application in three-dimensional simulations of turbulent transport in the SOL.

  3. Plastic deformation modelling of tempered martensite steel block structure by a nonlocal crystal plasticity model

    Directory of Open Access Journals (Sweden)

    Martin Boeff

    2014-01-01

    Full Text Available The plastic deformations of tempered martensite steel representative volume elements with different martensite block structures have been investigated by using a nonlocal crystal plasticity model which considers isotropic and kinematic hardening produced by plastic strain gradients. It was found that pronounced strain gradients occur in the grain boundary region even under homogeneous loading. The isotropic hardening of strain gradients strongly influences the global stress–strain diagram while the kinematic hardening of strain gradients influences the local deformation behaviour. It is found that the additional strain gradient hardening is not only dependent on the block width but also on the misorientations or the deformation incompatibilities in adjacent blocks.

  4. A semi-nonlocal numerical approach for modeling of temperature-dependent crack-wave interaction

    Science.gov (United States)

    Martowicz, Adam; Kijanka, Piotr; Staszewski, Wieslaw J.

    2016-04-01

    Numerical tools, which are used to simulate complex phenomena for models of complicated shapes suffer from either long computational time or accuracy. Hence, new modeling and simulation tools, which could offer reliable results within reasonable time periods, are highly demanded. Among other approaches, the nonlocal methods have appeared to fulfill these requirements quite efficiently and opened new perspectives for accurate simulations based on crude meshes of the model's degrees of freedom. In the paper, the preliminary results are shown for simulations of the phenomenon of temperature-dependent crack-wave interaction for elastic wave propagation in a model of an aluminum plate. Semi-nonlocal finite differences are considered to solve the problem of thermoelasticity - based on the discretization schemes, which were already proposed by the authors and taken from the previously published work. Numerical modeling is used to examine wave propagation primarily in the vicinity of a notch. Both displacement and temperature fields are sought in the investigated case study.

  5. Space-Time Quantization and Nonlocal Field Theory -Relativistic Second Quantization of Matrix Model

    CERN Document Server

    Tanaka, S

    2000-01-01

    We propose relativistic second quantization of matrix model of D particles in a general framework of nonlocal field theory based on Snyder-Yang's quantized space-time. Second-quantized nonlocal field is in general noncommutative with quantized space-time, but conjectured to become commutative with light cone time $X^+$. This conjecture enables us to find second-quantized Hamiltonian of D particle system and Heisenberg's equation of motion of second-quantized {\\bf D} field in close contact with Hamiltonian given in matrix model. We propose Hamilton's principle of Lorentz-invariant action of {\\bf D} field and investigate what conditions or approximations are needed to reproduce the above Heisenberg's equation given in light cone time. Both noncommutativities appearing in position coordinates of D particles in matrix model and in quantized space-time will be eventually unified through second quantization of matrix model.

  6. Travelling wave and convergence in stage-structured reaction-diffusion competitive models with nonlocal delays

    Energy Technology Data Exchange (ETDEWEB)

    Xu Rui [Department of Applied Mathematics, Xi' an Jiaotong University, Xi' an 710049 (China)]. E-mail: rxu88@yahoo.com.cn; Chaplain, M.A.J. [Department of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); Davidson, F.A. [Department of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom)

    2006-11-15

    In this paper, we first investigate a stage-structured competitive model with time delays, harvesting, and nonlocal spatial effect. By using an iterative technique recently developed by Wu and Zou (Wu J, Zou X. Travelling wave fronts of reaction-diffusion systems with delay. J Dynam Differen Equat 2001;13:651-87), sufficient conditions are established for the existence of travelling front solution connecting the two boundary equilibria in the case when there is no positive equilibrium. The travelling wave front corresponds to an invasion by a stronger species which drives the weaker species to extinction. Secondly, we consider a stage-structured competitive model with time delays and nonlocal spatial effect when the domain is finite. We prove the global stability of each of the nonnegative equilibria and demonstrate that the more complex model studied here admits three possible long term behaviors: coexistence, bistability and dominance as is the case for the standard Lotka-Voltera competitive model.

  7. Professor Nambu, String Theory and Moonshine Phenomenon

    CERN Document Server

    Eguchi, Tohru

    2016-01-01

    I first recall the last occasion of meeting the late Professor Yoichiro Nambu in a hospital in Osaka. I then present a brief introduction to the moonshine phenomenon in string theory which is under recent investigations.

  8. Nonlocal gravity

    CERN Document Server

    Mashhoon, Bahram

    2017-01-01

    Relativity theory is based on a postulate of locality, which means that the past history of the observer is not directly taken into account. This book argues that the past history should be taken into account. In this way, nonlocality---in the sense of history dependence---is introduced into relativity theory. The deep connection between inertia and gravitation suggests that gravity could be nonlocal, and in nonlocal gravity the fading gravitational memory of past events must then be taken into account. Along this line of thought, a classical nonlocal generalization of Einstein's theory of gravitation has recently been developed. A significant consequence of this theory is that the nonlocal aspect of gravity appears to simulate dark matter. According to nonlocal gravity theory, what astronomers attribute to dark matter should instead be due to the nonlocality of gravitation. Nonlocality dominates on the scale of galaxies and beyond. Memory fades with time; therefore, the nonlocal aspect of gravity becomes wea...

  9. A mixed SOC-turbulence model for nonlocal transport and Lévy-fractional Fokker–Planck equation

    Energy Technology Data Exchange (ETDEWEB)

    Milovanov, Alexander V. [ENEA National Laboratory, Centro Ricerche Frascati, I-00044 Frascati, Rome (Italy); Department of Space Plasma Physics, Space Research Institute, Russian Academy of Sciences, 117997 Moscow (Russian Federation); Juul Rasmussen, Jens [Physics Department, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2014-04-01

    The phenomena of nonlocal transport in magnetically confined plasma are theoretically analyzed. A hybrid model is proposed, which brings together the notion of inverse energy cascade, typical of drift-wave- and two-dimensional fluid turbulence, and the ideas of avalanching behavior, associable with self-organized critical (SOC) behavior. Using statistical arguments, it is shown that an amplification mechanism is needed to introduce nonlocality into dynamics. We obtain a consistent derivation of nonlocal Fokker–Planck equation with space-fractional derivatives from a stochastic Markov process with the transition probabilities defined in reciprocal space. The hybrid model observes the Sparre Andersen universality and defines a new universality class of SOC.

  10. A hybridizable discontinuous Galerkin method for solving nonlocal optical response models

    CERN Document Server

    Li, Liang; Mortensen, N Asger; Wubs, Martijn

    2016-01-01

    We propose Hybridizable Discontinuous Galerkin (HDG) methods for solving the frequency-domain Maxwell's equations coupled to the Nonlocal Hydrodynamic Drude (NHD) and Generalized Nonlocal Optical Response (GNOR) models, which are employed to describe the optical properties of nano-plasmonic scatterers and waveguides. Brief derivations for both the NHD model and the GNOR model are presented. The formulations of the HDG method are given, in which we introduce two hybrid variables living only on the skeleton of the mesh. The local field solutions are expressed in terms of the hybrid variables in each element. Two conservativity conditions are globally enforced to make the problem solvable and to guarantee the continuity of the tangential component of the electric field and the normal component of the current density. Numerical results show that the proposed HDG methods converge at optimal rate. We benchmark our implementation and demonstrate that the HDG method has the potential to solve complex nanophotonic pro...

  11. Reduced entropic model for studies of multidimensional nonlocal transport in high-energy-density plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Del Sorbo, D.; Feugeas, J.-L.; Nicolaï, Ph.; Olazabal-Loumé, M.; Dubroca, B.; Guisset, S.; Touati, M.; Tikhonchuk, V. [Centre Lasers Intenses et Applications, Université de Bordeaux-CNRS-CEA, UMR 5107, F-33405 Talence (France)

    2015-08-15

    Hydrodynamic simulations of high-energy-density plasmas require a detailed description of energy fluxes. For low and intermediate atomic number materials, the leading mechanism is the electron transport, which may be a nonlocal phenomenon requiring a kinetic modeling. In this paper, we present and test the results of a nonlocal model based on the first angular moments of a simplified Fokker-Planck equation. This multidimensional model is closed thanks to an entropic relation (the Boltzman H-theorem). It provides a better description of the electron distribution function, thus enabling studies of small scale kinetic effects within the hydrodynamic framework. Examples of instabilities of electron plasma and ion-acoustic waves, driven by the heat flux, are presented and compared with the classical formula.

  12. Reduced entropic model for studies of multidimensional nonlocal transport in high-energy-density plasmas

    Science.gov (United States)

    Del Sorbo, D.; Feugeas, J.-L.; Nicolaï, Ph.; Olazabal-Loumé, M.; Dubroca, B.; Guisset, S.; Touati, M.; Tikhonchuk, V.

    2015-08-01

    Hydrodynamic simulations of high-energy-density plasmas require a detailed description of energy fluxes. For low and intermediate atomic number materials, the leading mechanism is the electron transport, which may be a nonlocal phenomenon requiring a kinetic modeling. In this paper, we present and test the results of a nonlocal model based on the first angular moments of a simplified Fokker-Planck equation. This multidimensional model is closed thanks to an entropic relation (the Boltzman H-theorem). It provides a better description of the electron distribution function, thus enabling studies of small scale kinetic effects within the hydrodynamic framework. Examples of instabilities of electron plasma and ion-acoustic waves, driven by the heat flux, are presented and compared with the classical formula.

  13. New fractional derivatives with nonlocal and non-singular kernel: Theory and application to heat transfer model

    Directory of Open Access Journals (Sweden)

    Atangana Abdon

    2016-01-01

    Full Text Available In this manuscript we proposed a new fractional derivative with non-local and no-singular kernel. We presented some useful properties of the new derivative and applied it to solve the fractional heat transfer model.

  14. Pattern formation in a model of competing populations with nonlocal interactions

    Science.gov (United States)

    Segal, B. L.; Volpert, V. A.; Bayliss, A.

    2013-06-01

    We analyze and compute an extension of a previously developed population model based on the well-known diffusive logistic equation with nonlocal interaction, to a system involving competing species. Our model involves a system of nonlinear integro-differential equations, with the nonlocal interaction characterized by convolution integrals of the population densities against specified kernel functions. The extent of the nonlocal coupling is characterized by a parameter δ so that when δ→0 the problem becomes local. We consider critical points of the model, i.e., spatially homogeneous equilibrium solutions. There is generally one critical point in the first quadrant (i.e., both population densities positive), denoting coexistence of the two species. We show that this solution can be destabilized by the nonlocal coupling and obtain general conditions for stability of this critical point as a function of δ, the specific kernel function and parameters of the model. We study the nonlinear behavior of the model and show that the populations can evolve to localized cells, or islands. We find that the stability transition is supercritical. Near the stability boundary solutions are small amplitude, nearly sinusoidal oscillations, however, when δ increases large amplitude, nonlinear states are found. We find a multiplicity of stable, steady state patterns. We further show that with a stepfunction kernel function the structure of these islands, a highly nonlinear phenomenon, can be described analytically. Finally, we analyze the role of the kernel function and show that for some choices of kernel function the resulting population islands can exhibit tip-splitting behavior and island amplitude modulation.

  15. Enhancing the Trace Norm and Bures Norm Measurement-Induced Nonlocality in the Heisenberg XYZ Model

    Science.gov (United States)

    Xie, Yu-Xia; Liu, Jing; Ma, Hong

    2016-11-01

    Nonlocality is one unique characteristic of quantum mechanics and an essential resource for quantum communication and computation. We investigate two measures of the well-defined geometric measurement-induced nonlocality (MIN) in the Heisenberg XYZ model, and found that considerable enhancement of the MINs can be achieved by tuning strength of the anisotropic parameter, the J z coupling, and the Dzyaloshinsky-Moriya (DM) interaction of the model. Particularly, the maxima of the two MINs can be obtained when the strength of the J z coupling or the DM interaction approaches infinity. We have also demonstrated the singular behaviors of the two MINs such as the nonunique states ordering and the sudden change behaviors.

  16. He I lines in B stars - Comparison of non-local thermodynamic equilibrium models with observations

    Science.gov (United States)

    Heasley, J. N.; Timothy, J. G.; Wolff, S. C.

    1982-01-01

    Profiles of He gamma-gamma 4026, 4387, 4471, 4713, 5876, and 6678 have been obtained in 17 stars of spectral type B0-B5. Parameters of the nonlocal thermodynamic equilibrium models appropriate to each star are determined from the Stromgren index and fits to H-alpha line profiles. These parameters yield generally good fits to the observed He I line profiles, with the best fits being found for the blue He I lines where departures from local thermodynamic equilibrium are relatively small. For the two red lines it is found that, in the early B stars and in stars with log g less than 3.5, both lines are systematically stronger than predicted by the nonlocal thermodynamic equilibrium models.

  17. Wave propagation in magneto-electro-elastic nanobeams via two nonlocal beam models

    Science.gov (United States)

    Ma, Li-Hong; Ke, Liao-Liang; Wang, Yi-Ze; Wang, Yue-Sheng

    2017-02-01

    This paper makes the first attempt to investigate the dispersion behavior of waves in magneto-electro-elastic (MEE) nanobeams. The Euler nanobeam model and Timoshenko nanobeam model are developed in the formulation based on the nonlocal theory. By using the Hamilton's principle, we derive the governing equations which are then solved analytically to obtain the dispersion relations of MEE nanobeams. Results are presented to highlight the influences of the thermo-electro-magnetic loadings and nonlocal parameter on the wave propagation characteristics of MEE nanobeams. It is found that the thermo-electro-magnetic loadings can lead to the occurrence of the cut-off wave number below which the wave can't propagate in MEE nanobeams.

  18. An investigation of a nonlocal hyperbolic model for self-organization of biological groups.

    Science.gov (United States)

    Fetecau, Razvan C; Eftimie, Raluca

    2010-10-01

    In this article, we introduce and study a new nonlocal hyperbolic model for the formation and movement of animal aggregations. We assume that the nonlocal attractive, repulsive, and alignment interactions between individuals can influence both the speed and the turning rates of group members. We use analytical and numerical techniques to investigate the effect of these nonlocal interactions on the long-time behavior of the patterns exhibited by the model. We establish the local existence and uniqueness and show that the nonlinear hyperbolic system does not develop shock solutions (gradient blow-up). Depending on the relative magnitudes of attraction and repulsion, we show that the solutions of the model either exist globally in time or may exhibit finite-time amplitude blow-up. We illustrate numerically the various patterns displayed by the model: dispersive aggregations, finite-size groups and blow-up patterns, the latter corresponding to aggregations which may collapse to a point. The transition from finite-size to blow-up patterns is governed by the magnitude of the social interactions and the random turning rates. The presence of these types of patterns and the absence of shocks are consequences of the biologically relevant assumptions regarding the form of the speed and the turning rate functions, as well as of the kernels describing the social interactions.

  19. Multigrid Nonlocal Gaussian Mixture Model for Segmentation of Brain Tissues in Magnetic Resonance Images.

    Science.gov (United States)

    Chen, Yunjie; Zhan, Tianming; Zhang, Ji; Wang, Hongyuan

    2016-01-01

    We propose a novel segmentation method based on regional and nonlocal information to overcome the impact of image intensity inhomogeneities and noise in human brain magnetic resonance images. With the consideration of the spatial distribution of different tissues in brain images, our method does not need preestimation or precorrection procedures for intensity inhomogeneities and noise. A nonlocal information based Gaussian mixture model (NGMM) is proposed to reduce the effect of noise. To reduce the effect of intensity inhomogeneity, the multigrid nonlocal Gaussian mixture model (MNGMM) is proposed to segment brain MR images in each nonoverlapping multigrid generated by using a new multigrid generation method. Therefore the proposed model can simultaneously overcome the impact of noise and intensity inhomogeneity and automatically classify 2D and 3D MR data into tissues of white matter, gray matter, and cerebral spinal fluid. To maintain the statistical reliability and spatial continuity of the segmentation, a fusion strategy is adopted to integrate the clustering results from different grid. The experiments on synthetic and clinical brain MR images demonstrate the superior performance of the proposed model comparing with several state-of-the-art algorithms.

  20. 高阶非局部变分模型%Higher-order nonlocal variational model

    Institute of Scientific and Technical Information of China (English)

    李亚峰; 冯象初

    2012-01-01

    To describe the nonlocal structure of images better and remove noise, this paper proposes a higher-order nonlocal variational model by defining a new weighted function. Theoretical analysis and numerical experiments are presented to demonstrate the performance of the proposed model, which is better than the original in terms of both PSNR and visual perception. As a result, the new model keeps the advantages of the nonlocal variational model, while it can preserve image features better.%为了更好地描述图像的非局部结构并抑制噪声,通过定义新的权函数,提出了一个高阶非局部变分模型.理论分析和实验结果表明,相比于非局部平均去噪算子和非局部变分模型,提出的高阶非局部变分模型在去噪结果上有更高的信噪比和更好的视觉效果.因此,新模型保持了非局部变分模型的优点,同时能够更好地保留图像特征.

  1. A mixed SOC-turbulence model for nonlocal transport and space-fractional Fokker-Planck equation

    CERN Document Server

    Milovanov, Alexander V

    2013-01-01

    The phenomena of nonlocal transport in magnetically confined plasma are theoretically analyzed. A hybrid model is proposed, which brings together the notion of inverse energy cascade, typical of drift-wave- and two-dimensional fluid turbulence, and the ideas of avalanching behavior, associable with self-organized critical (SOC) behavior. Using statistical arguments, it is shown that an amplification mechanism is needed to introduce nonlocality into dynamics. We obtain a consistent derivation of nonlocal Fokker-Planck equation with space-fractional derivatives from a stochastic Markovian process with the transition probabilities defined in reciprocal space.

  2. An Inhomogeneous Space-Time Patching Model Based on a Nonlocal and Nonlinear Schrodinger Equation

    CERN Document Server

    Dantas, Christine C

    2016-01-01

    We consider an integrable, nonlocal and nonlinear, Schr\\"odinger equation (NNSE) as a model for building space-time patchings in inhomogeneous loop quantum cosmology (LQC). We briefly review exact solutions of the NNSE, specially those obtained through "geometric equivalence" methods. Furthemore, we argue that the integrability of the NNSE could be linked to consistency conditions derived from LQC, under the assumption that the patchwork dynamics behaves as an integrable many-body system.

  3. Simulation Evidence for Nonlocal Interface Models: Two Correlation Lengths Describe Complete Wetting

    Science.gov (United States)

    Pang, Lijun; Landau, D. P.; Binder, K.

    2011-06-01

    Monte Carlo simulations of (fluctuating) interfaces in Ising models confined between competing walls at temperatures above the wetting transition are presented and various correlation functions probing the interfacial fluctuation are computed. Evidence for the nonlocal interface Hamiltonian approach of A. O. Parry et al. [Phys. Rev. Lett. 93, 086104 (2004)PRLTAO0031-900710.1103/PhysRevLett.93.086104] is given. In particular, we show that two correlation lengths exist with different dependence on the distance D between the walls.

  4. Simulation evidence for nonlocal interface models: two correlation lengths describe complete wetting.

    Science.gov (United States)

    Pang, Lijun; Landau, D P; Binder, K

    2011-06-10

    Monte Carlo simulations of (fluctuating) interfaces in Ising models confined between competing walls at temperatures above the wetting transition are presented and various correlation functions probing the interfacial fluctuation are computed. Evidence for the nonlocal interface Hamiltonian approach of A. O. Parry et al. [Phys. Rev. Lett. 93, 086104 (2004)] is given. In particular, we show that two correlation lengths exist with different dependence on the distance D between the walls.

  5. Possible detection of causality violation in a non-local scalar model

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Asrarul; Joglekar, Satish D [Department of Physics, IIT Kanpur, Kanpur 208016 (India)], E-mail: ahaque@iitk.ac.in, E-mail: sdj@iitk.ac.in

    2009-02-13

    We consider the possibility that there may be causality violation detectable at higher energies. We take a scalar non-local theory containing a mass scale {lambda} as a model example and make a preliminary study of how the causality violation can be observed. We show how to formulate an observable whose detection would signal causality violation. We study the range of energies (relative to {lambda}) and couplings to which the observable can be used.

  6. Effective lattice Polyakov loop theory vs. full SU(3) Yang-Mills at finite temperature

    CERN Document Server

    Bergner, Georg; Philipsen, Owe

    2013-01-01

    A three-dimensional effective theory of Polyakov loops has recently been derived from Wilson's Yang-Mills lattice action by means of a strong coupling expansion. It is valid in the confined phase up to the deconfinement phase transition, for which it predicts the correct order and gives quantitative estimates for the critical coupling. In this work we study its predictive power for further observables like correlation functions and the equation of state. We find that the effective theory correctly reproduces qualitative features and symmetries of the full theory as the continuum is approached. Regarding quantitative predictions, we identify two classes of observables by numerical comparison as well as analytic calculations: correlation functions and their associated mass scales cannot be described accurately from a truncated effective theory, due to its inherently non-local nature involving long-range couplings. On the other hand, phase transitions and bulk thermodynamic quantities are accurately reproduced b...

  7. Spectral analysis of approximations of Dirichlet-Neumann operators and nonlocal shallow water wave models

    Science.gov (United States)

    Vargas-Magaña, Rosa; Panayotaros, Panayotis

    2015-11-01

    We study the problem of wave propagation in a long-wave asymptotic regime over variable bottom of an ideal irrotational fluid in the framework of the Hamiltonian formulation in which the non-local Dirichlet-Neumann (DtN) operator appears explicitly in the Hamiltonian. We propose a non-local Hamiltonian model for bidirectional wave propagation in shallow water that involves pseudodifferential operators that approximate the DtN operator for variable depth. These models generalize the Boussinesq system as they include the exact dispersion relation in the case of constant depth. We present results for the normal modes and eigenfrequencies of the linearized problem. We see that variable topography introduces effects such as steepening of normal modes with increasing variation of depth, as well as amplitude modulation of the normal modes in certain wavelength ranges. Numerical integration shows that the constant depth nonlocal Boussinesq model with quadratic nonlinearity can capture the evolution obtained with higher order approximations of the DtN operator. In the case of variable depth we observe certain oscillations in width of the crest and also some interesting textures in the evolution of wave crests during the passage from obstacles.

  8. Power-counting theorem for non-local matrix models and renormalisation

    CERN Document Server

    Grosse, H; Grosse, Harald; Wulkenhaar, Raimar

    2003-01-01

    Solving the exact renormalisation group equation a la Wilson-Polchinski perturbatively, we derive a power-counting theorem for general matrix models with arbitrarily non-local propagators. The power-counting degree is determined by three different scaling dimensions of the cut-off propagator and various topological data of ribbon graphs. The main application is the renormalisation problem of field theories on noncommutative R^D written in matrix formulation. It turns out that the propagator for the real scalar field has anomalous scaling dimensions, which for D>2 result in arbitrarily high power-counting degrees of divergence. This feature is known as UV/IR-mixing, which we conclude to emerge in any non-local matrix model with anomalous scaling dimensions of the propagator. Models in which the propagator has regular scaling dimensions are for D=2,4 power-counting renormalisable but acquire due to non-locality an infinite number of relevant or marginal interactions. By a reduction-of-couplings mechanism it is ...

  9. Internal noise-driven generalized Langevin equation from a nonlocal continuum model.

    Science.gov (United States)

    Sarkar, Saikat; Chowdhury, Shubhankar Roy; Roy, Debasish; Vasu, Ram Mohan

    2015-08-01

    Starting with a micropolar formulation, known to account for nonlocal microstructural effects at the continuum level, a generalized Langevin equation (GLE) for a particle, describing the predominant motion of a localized region through a single displacement degree of freedom, is derived. The GLE features a memory-dependent multiplicative or internal noise, which appears upon recognizing that the microrotation variables possess randomness owing to an uncertainty principle. Unlike its classical version, the present GLE qualitatively reproduces the experimentally measured fluctuations in the steady-state mean square displacement of scattering centers in a polyvinyl alcohol slab. The origin of the fluctuations is traced to nonlocal spatial interactions within the continuum, a phenomenon that is ubiquitous across a broad class of response regimes in solids and fluids. This renders the proposed GLE a potentially useful model in such cases.

  10. $\\eta$-$\\gamma$ and $\\eta'$-$\\gamma$ transition form factors in a nonlocal NJL model

    CERN Document Server

    Dumm, D Gomez; Scoccola, N N

    2016-01-01

    We study the $\\eta$ and $\\eta'$ distribution amplitudes (DAs) in the context of a nonlocal SU(3)_L x SU(3)_R chiral quark model. The corresponding Lagrangian allows to reproduce the phenomenological values of pseudoscalar meson masses and decay constants, as well as the momentum dependence of the quark propagator arising from lattice calculations. It is found that the obtained DAs have two symmetric maxima, which arise from new contributions generated by the nonlocal character of the interactions. These DAs are then applied to the calculation of the $\\eta$-$\\gamma$ and $\\eta'$-$\\gamma$ transition form factors. Implications of our results regarding higher twist corrections and/or contributions to the transition form factors originated by gluon-gluon components in the $\\eta$ and $\\eta'$ mesons are discussed.

  11. Critical dynamics of a nonlocal model and critical behavior of perovskite manganites.

    Science.gov (United States)

    Singh, Rohit; Dutta, Kishore; Nandy, Malay K

    2016-05-01

    We investigate the nonconserved critical dynamics of a nonlocal model Hamiltonian incorporating screened long-range interactions in the quartic term. Employing dynamic renormalization group analysis at one-loop order, we calculate the dynamic critical exponent z=2+εf_{1}(σ,κ,n)+O(ε^{2}) and the linewidth exponent w=-σ+εf_{2}(σ,κ,n)+O(ε^{2}) in the leading order of ε, where ε=4-d+2σ, with d the space dimension, n the number of components in the order parameter, and σ and κ the parameters coming from the nonlocal interaction term. The resulting values of linewidth exponent w for a wide range of σ is found to be in good agreement with the existing experimental estimates from spin relaxation measurements in perovskite manganite samples.

  12. Nonlocal Coulomb interaction in the two-dimensional spin-1/2 Falicov–Kimball model

    Indian Academy of Sciences (India)

    S K Bhowmick; N K Ghosh

    2012-02-01

    The two-dimensional (2D) extended Falicov–Kimball model has been studied to observe the role of nonlocal Coulomb interaction (nc) using an exact diagonalization technique. The f-state occupation ($n^f$), the f–d intersite correlation function (fd), the specific heat (), entropy () and the specific heat coefficient () have been examined. Nonlocal Coulomb interaction-induced discontinuous insulator-to-metal transition occurs at a critical f-level energy. More ordered state is obtained with the increase of nc. In the specific heat curves, two-peak structure as well as a singlepeak structure appears. At low-temperature region, a sharp rise in the specific heat coefficient is observed. The peak value of shifts to the higher temperature region with nc.

  13. Propagation of a Laguerre-Gaussian correlated Schell-model beam in strongly nonlocal nonlinear media

    Science.gov (United States)

    Qiu, Yunli; Chen, Zhaoxi; He, Yingji

    2017-04-01

    Analytical expressions for the cross-spectral density function and the second-order moments of the Wigner distribution function of a Laguerre-Gaussian correlated Schell-model (LGCSM) beam propagating in strongly nonlocal nonlinear media are derived. The propagation properties, such as beam irradiance, beam width, the spectral degree of coherence and the propagation factor of a LGCSM beam inside the media are investigated in detail. The effect of the beam parameters and the input power on the evolution properties of a LGCSM is illustrated numerically. It is found that the beam width varies periodically or keeps invariant for a certain proper input power. And both the beam irradiance and the spectral degree of coherence of the LGCSM beam change periodically with the propagation distance for the arbitrary input power which however has no influence on the propagation factor. The coherent length and the mode order mainly affect the evolution speed of the LGCSM beam in strongly nonlocal nonlinear media.

  14. Renormalization of Polyakov loops in fundamental and higher representations

    CERN Document Server

    Kaczmarek, O; Hübner, K

    2007-01-01

    We compare two renormalization procedures, one based on the short distance behavior of heavy quark-antiquark free energies and the other by using bare Polyakov loops at different temporal entent of the lattice and find that both prescriptions are equivalent, resulting in renormalization constants that depend on the bare coupling. Furthermore these renormalization constants show Casimir scaling for higher representations of the Polyakov loops. The analysis of Polyakov loops in different representations of the color SU(3) group indicates that a simple perturbative inspired relation in terms of the quadratic Casimir operator is realized to a good approximation at temperatures $T \\gsim T_c$ for renormalized as well as bare loops. In contrast to a vanishing Polyakov loop in representations with non-zero triality in the confined phase, the adjoint loops are small but non-zero even for temperatures below the critical one. The adjoint quark-antiquark pairs exhibit screening. This behavior can be related to the bindin...

  15. VARIATIONAL PRINCIPLES FOR NONLOCAL CONTINUUM MODEL OF ORTHOTROPIC GRAPHENE SHEETS EMBEDDED IN AN ELASTIC MEDIUM

    Institute of Scientific and Technical Information of China (English)

    Sarp Adali

    2012-01-01

    Equations governing the vibrations and buckling of multilayered orthotropic graphene sheets can be expressed as a system of n partial differential equations where n refers to the number of sheets.This description is based on the continuum model of the graphene sheets which can also take the small scale effects into account by employing a nonlocal theory.In the present article a variational principle is derived for the nonlocal elastic theory of rectangular graphene sheets embedded in an elastic medium and undergoing transverse vibrations.Moreover the graphene sheets are subject to biaxial compression.Rayleigh quotients are obtained for the frequencies of freely vibrating graphene sheets and for the buckling load. The influence of small scale effects on the frequencies and the buckling load can be observed qualiatively from the expressions of the Rayleigh quotients.Elastic medium is modeled as a combination of Winkler and Pasternak foundations acting on the top and bottom layers of the mutilayered nano-structure.Natural boundary conditions of the problem are derived using the variational principle formulated in the study.It is observed that free boundaries lead to coupled boundary conditions due to nonlocal theory used in the continuum formulation while the local (classical) elasticity theory leads to uncoupled boundary conditions.The mathematical methods used in the study involve calculus of variations and the semi-inverse method for deriving the variational integrals.

  16. Quantum Nonlocality and Reality

    Science.gov (United States)

    Bell, Mary; Gao, Shan

    2016-09-01

    Preface; Part I. John Stewart Bell: The Physicist: 1. John Bell: the Irish connection Andrew Whitaker; 2. Recollections of John Bell Michael Nauenberg; 3. John Bell: recollections of a great scientist and a great man Gian-Carlo Ghirardi; Part II. Bell's Theorem: 4. What did Bell really prove? Jean Bricmont; 5. The assumptions of Bell's proof Roderich Tumulka; 6. Bell on Bell's theorem: the changing face of nonlocality Harvey R. Brown and Christopher G. Timpson; 7. Experimental tests of Bell inequalities Marco Genovese; 8. Bell's theorem without inequalities: on the inception and scope of the GHZ theorem Olival Freire, Jr and Osvaldo Pessoa, Jr; 9. Strengthening Bell's theorem: removing the hidden-variable assumption Henry P. Stapp; Part III. Nonlocality: Illusions or Reality?: 10. Is any theory compatible with the quantum predictions necessarily nonlocal? Bernard d'Espagnat; 11. Local causality, probability and explanation Richard A. Healey; 12. Bell inequality and many-worlds interpretation Lev Vaidman; 13. Quantum solipsism and non-locality Travis Norsen; 14. Lessons of Bell's theorem: nonlocality, yes; action at a distance, not necessarily Wayne C. Myrvold; 15. Bell non-locality, Hardy's paradox and hyperplane dependence Gordon N. Fleming; 16. Some thoughts on quantum nonlocality and its apparent incompatibility with relativity Shan Gao; 17. A reasonable thing that just might work Daniel Rohrlich; 18. Weak values and quantum nonlocality Yakir Aharonov and Eliahu Cohen; Part IV. Nonlocal Realistic Theories: 19. Local beables and the foundations of physics Tim Maudlin; 20. John Bell's varying interpretations of quantum mechanics: memories and comments H. Dieter Zeh; 21. Some personal reflections on quantum non-locality and the contributions of John Bell Basil J. Hiley; 22. Bell on Bohm Sheldon Goldstein; 23. Interactions and inequality Philip Pearle; 24. Gravitation and the noise needed in objective reduction models Stephen L. Adler; 25. Towards an objective

  17. Polyakov loop and heavy quark entropy in strong magnetic fields from holographic black hole engineering

    CERN Document Server

    Critelli, Renato; Finazzo, Stefano I; Noronha, Jorge

    2016-01-01

    We investigate the temperature and magnetic field dependence of the Polyakov loop and heavy quark entropy in a bottom-up Einstein-Maxwell-dilaton (EMD) holographic model for the strongly coupled quark-gluon plasma (QGP) that quantitatively matches lattice data for the $(2+1)$-flavor QCD equation of state at finite magnetic field and physical quark masses. We compare the holographic EMD model results for the Polyakov loop at zero and nonzero magnetic fields and the heavy quark entropy at vanishing magnetic field with the latest lattice data available for these observables and find good agreement for temperatures $T\\gtrsim 150$ MeV and magnetic fields $eB\\lesssim 1$ GeV$^2$. Predictions for the behavior of the heavy quark entropy at nonzero magnetic fields are made that could be readily tested on the lattice.

  18. Polyakov loop and spin correlators on finite lattices a study beyond the mass gap

    CERN Document Server

    Engels, J; Neuhaus, T; Engels, J; Mitrjushkin, V K; Neuhaus, T

    1995-01-01

    We derive an analytic expression for point-to-point correlation functions of the Polyakov loop based on the transfer matrix formalism. For the 2d Ising model we show that the results deduced from point-point spin correlators are coinciding with those from zero momentum correlators. We investigate the contributions from eigenvalues of the transfer matrix beyond the mass gap and discuss the limitations and possibilities of such an analysis. The finite size behaviour of the obtained 2d Ising model matrix elements is examined. The point-to-point correlator formula is then applied to Polyakov loop data in finite temperature SU(2) gauge theory. The leading matrix element shows all expected scaling properties. Just above the critical point we find a Debye screening mass ~\\mu_D/T\\approx4~, independent of the volume.

  19. INVESTIGATION ON GRADIENT-DEPENDENT NONLOCAL CONSTITUTIVE MODELS FOR ELASTO-PLASTICITY COUPLED WITH DAMAGE

    Institute of Scientific and Technical Information of China (English)

    SHEN Xin-pu; SHEN Guo-xiao; CHEN Li-xin; YANG Lu

    2005-01-01

    Firstly, typical gradient-dependent nonlocal inelastic models were briefly gradient-dependent constitutive model for plasticity coupled with isotropic damage was presented in the framework of continuum thermodynamics. Numerical scheme for calculation of Laplacian term of damage field with the numerical results obtained by FEM calculation was proposed. Equations have been presented on the basis of Taylor series for both 2-dimensional and 3-dimensional cases, respectively. Numerical results have indicated the validity of the proposed gradient-dependent model and corresponding numerical scheme.

  20. Generalized Ginzburg–Landau approach to inhomogeneous phases in nonlocal chiral quark models

    Energy Technology Data Exchange (ETDEWEB)

    Carlomagno, J.P. [IFLP, CONICET – Dpto. de Física, FCE, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Gómez Dumm, D., E-mail: dumm@fisica.unlp.edu.ar [IFLP, CONICET – Dpto. de Física, FCE, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Scoccola, N.N. [CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Physics Department, Comisión Nacional de Energía Atómica, Av. Libertador 8250, 1429 Buenos Aires (Argentina); Universidad Favaloro, Solís 453, 1078 Buenos Aires (Argentina)

    2015-05-18

    We analyze the presence of inhomogeneous phases in the QCD phase diagram within the framework of nonlocal chiral quark models. We concentrate in particular in the positions of the tricritical (TCP) and Lifshitz (LP) points, which are studied in a general context using a generalized Ginzburg–Landau approach. We find that for all the phenomenologically acceptable model parametrizations considered the TCP is located at a higher temperature and a lower chemical potential in comparison with the LP. Consequently, these models seem to favor a scenario in which the onset of the first order transition between homogeneous phases is not covered by an inhomogeneous, energetically favored phase.

  1. Hydrodynamics of the Polyakov Line in SU$(N_c)$ Yang-Mills

    CERN Document Server

    Liu, Yizhuang; Zahed, Ismail

    2015-01-01

    We discuss a hydrodynamical description of the eigenvalues of the Polyakov line at large but finite $N_c$ for Yang-Mills theory in even and odd space-time dimensions. The hydro-static solutions for the eigenvalue densities are shown to interpolate between a uniform distribution in the confined phase and a localized distribution in the de-confined phase. The resulting critical temperatures are in overall agreement with those measured on the lattice over a broad range of $N_c$, and are consistent with the string model results at $N_c=\\infty$. The stochastic relaxation of the eigenvalues of the Polyakov line out of equilibrium is captured by a hydrodynamical instanton. An estimate of the probability of formation of a Z(N$_c)$ bubble using a piece-wise sound wave is suggested.

  2. Nambu mechanics for stochastic magnetization dynamics

    CERN Document Server

    Thibaudeau, Pascal; Nicolis, Stam

    2016-01-01

    The Landau-Lifshitz-Gilbert (LLG) equation describes the dynamics of a damped magnetization vector that can be understood as a generalization of Larmor spin precession. The LLG equation cannot be deduced from the Hamiltonian framework, by introducing a coupling to a usual bath, but requires the introduction of additional constraints. It is shown that these constraints can be formulated elegantly and consistently in the framework of dissipative Nambu mechanics. This has many consequences for both the variational principle and for topological aspects of hidden symmetries that control conserved quantities. We particularly study how the damping terms of dissipative Nambu mechanics affect the consistent interaction of magnetic systems with stochastic reservoirs and derive a master equation for the magnetization. The proposals are supported by numerical studies using symplectic integrators that preserve the topological structure of Nambu equations. These results are compared to computations performed by direct samp...

  3. Nonlocal continuum-based modeling of a nanoplate subjected to a moving nanoparticle. Part I: Theoretical formulations

    Science.gov (United States)

    Kiani, Keivan

    2011-10-01

    The potential applications of nanoplates in energy storage, chemical and biological sensors, solar cells, field emission, and transporting of nanocars have been attracted the attentions of the nanotechnology community to them during recent years. Herein, the later application of nanoplates from nonlocal elastodynamic point of view is of interest. To this end, dynamic response of a nanoplate subjected to a moving nanoparticle is examined within the context of nonlocal continuum theory of Eringen. The fully simply supported nanoplate is modeled based on the nonlocal Kirchhoff, Mindlin, and higher-order plate theories. The non-dimensional equations of motion of the nonlocal plate models are established. The effects of moving nanoparticle's weight and existing friction between the surfaces of the moving nanoparticle and nanoplate on the in-plane and out-of-plane vibrations of the nanoplate are incorporated into the formulations of the proposed models. The eigen function expansion and the Laplace transform methods are employed for discretization of the governing equations in the spatial and the time domains, respectively. The analytical expressions of the dynamic deformation field associated with each nonlocal plate theory are obtained when the moving nanoparticle traverses the nanoplate on an arbitrary straight path (an opened path) as well as an ellipse path (a closed path). The dynamic in-plane forces and moments of each nonlocal plate model are also derived. Furthermore, the critical velocity and the critical angular velocity of the moving nanoparticle for the proposed models are expressed analytically for the aforementioned paths. Part II of this work consists in a comprehensive parametric study where the effects of influential parameters on dynamic response of the proposed nonlocal plate models are scrutinized in some detail.

  4. Traveling waves in a nonlocal, piecewise linear reaction-diffusion population model

    Science.gov (United States)

    Autry, E. A.; Bayliss, A.; Volpert, V. A.

    2017-08-01

    We consider an analytically tractable switching model that is a simplification of a nonlocal, nonlinear reaction-diffusion model of population growth where we take the source term to be piecewise linear. The form of this source term allows us to consider both the monostable and bistable versions of the problem. By transforming to a traveling frame and choosing specific kernel functions, we are able to reduce the problem to a system of algebraic equations. We construct solutions and examine the propagation speed and monotonicity of the resulting waves.

  5. Local hidden-variable model for a recent experimental test of quantum nonlocality and local contextuality

    Science.gov (United States)

    La Cour, Brian R.

    2017-07-01

    An experiment has recently been performed to demonstrate quantum nonlocality by establishing contextuality in one of a pair of photons encoding four qubits; however, low detection efficiencies and use of the fair-sampling hypothesis leave these results open to possible criticism due to the detection loophole. In this Letter, a physically motivated local hidden-variable model is considered as a possible mechanism for explaining the experimentally observed results. The model, though not intrinsically contextual, acquires this quality upon post-selection of coincident detections.

  6. Particle model for nonlocal heat transport in fusion plasmas.

    Science.gov (United States)

    Bufferand, H; Ciraolo, G; Ghendrih, Ph; Lepri, S; Livi, R

    2013-02-01

    We present a simple stochastic, one-dimensional model for heat transfer in weakly collisional media as fusion plasmas. Energies of plasma particles are treated as lattice random variables interacting with a rate inversely proportional to their energy schematizing a screened Coulomb interaction. We consider both the equilibrium (microcanonical) and nonequilibrium case in which the system is in contact with heat baths at different temperatures. The model exhibits a characteristic length of thermalization that can be associated with an interaction mean free path and one observes a transition from ballistic to diffusive regime depending on the average energy of the system. A mean-field expression for heat flux is deduced from system heat transport properties. Finally, it is shown that the nonequilibrium steady state is characterized by long-range correlations.

  7. Physical properties of Polyakov loop geometrical clusters in SU(2) gluodynamics

    CERN Document Server

    Ivanytsky, A I; Nikonov, E G; Ilgenfritz, E -M; Oliinychenko, D R; Sagun, V V; Mishustin, I N; Petrov, V K; Zinovjev, G M

    2016-01-01

    We apply the liquid droplet model to analyze the clustering phenomenon of SU(2) gluodynamics in the vicinity of the deconfinement phase transition, in particular, size distributions of clusters formed by the Polyakov loops of the same sign. Within such an approach the phase transition in SU(2) gluodynamics can be considered as the transition between two types of liquids where one of the liquids (the largest droplet of a certain Polyakov loop sign) experiences a condensation, while the other one (the next to largest droplet of opposite Polyakov loop sign) evaporates. The clusters of smaller sizes form two accompanying gases, and their size distributions are described by the liquid droplet parameterization. By fitting the lattice data we have extracted the value of Fisher exponent $\\tau =$ 1.806 $\\pm$ 0.008. Also we found that the temperature dependences of the surface tension of both gaseous clusters are entirely different below and above phase transition and, hence, they can serve as an order parameter. The c...

  8. Wave propagation in double-walled carbon nanotubes on a novel analytically nonlocal Timoshenko-beam model

    Science.gov (United States)

    Yang, Yang; Zhang, Lixiang; Lim, C. W.

    2011-04-01

    This paper is concerned with the characteristics of wave propagation in double-walled carbon nanotubes (DWCNTs). The DWCNTs is simulated with a Timoshenko beam model based on the nonlocal continuum elasticity theory, referred to as an analytically nonlocal Timoshenko-beam (ANT) model. The governing equations of the DWCNTs beam consist of a set of four equations that are derived from the variational principle of the beam with high-order boundary conditions at the both ends, in which the effects of the nano-scale nonlocality and the van der Waals interaction between inner and outer tubes are inclusive. The characteristics of the wave propagation in the DWCNTs beam were analyzed with the new ANT model proposed and the comparisons with the partially nonlocal Timoshenko-beam (PNT) models in publication were made in details. The results show that the nonlocal effects of the ANT model proposed in the present study on the wave propagations are more significant because it is in stronger stiffness enhancement to the DWCNTs beam.

  9. Microscopic Description of the Granular Fluidity Field in Nonlocal Flow Modeling

    Science.gov (United States)

    Zhang, Qiong; Kamrin, Ken

    2017-02-01

    A recent granular rheology based on an implicit "granular fluidity" field has been shown to quantitatively predict many nonlocal phenomena. However, the physical nature of the field has not been identified. Here, the granular fluidity is found to be a kinematic variable given by the velocity fluctuation and packing fraction. This is verified with many discrete element simulations, which show that the operational fluidity definition, solutions of the fluidity model, and the proposed microscopic formula all agree. Kinetic theoretical and Eyring-like explanations shed insight into the obtained form.

  10. Nonlocal correlations and spectral properties of the Falicov-Kimball model

    Science.gov (United States)

    Ribic, T.; Rohringer, G.; Held, K.

    2016-05-01

    We derive an analytical expression for the local two-particle vertex of the Falicov-Kimball model, including its dependence on all three frequencies, the full vertex, and all reducible vertices. This allows us to calculate the self-energy in diagrammatic extensions of dynamical mean field theory, specifically in the dual fermion and the one-particle irreducible approach. Nonlocal correlations are thence included and originate here from charge-density wave fluctuations. At low temperatures and in two dimensions, they lead to a larger self-energy contribution at low frequencies and a more insulating spectrum.

  11. A convergent scheme for a non-local coupled system modelling dislocations densities dynamics

    Science.gov (United States)

    Hajj, A. El; Forcadel, N.

    2008-06-01

    In this paper, we study a non-local coupled system that arises in the theory of dislocations densities dynamics. Within the framework of viscosity solutions, we prove a long time existence and uniqueness result for the solution of this model. We also propose a convergent numerical scheme and we prove a Crandall-Lions type error estimate between the continuous solution and the numerical one. As far as we know, this is the first error estimate of Crandall-Lions type for Hamilton-Jacobi systems. We also provide some numerical simulations.

  12. Microscopic Description of the Granular Fluidity Field in Nonlocal Flow Modeling.

    Science.gov (United States)

    Zhang, Qiong; Kamrin, Ken

    2017-02-03

    A recent granular rheology based on an implicit "granular fluidity" field has been shown to quantitatively predict many nonlocal phenomena. However, the physical nature of the field has not been identified. Here, the granular fluidity is found to be a kinematic variable given by the velocity fluctuation and packing fraction. This is verified with many discrete element simulations, which show that the operational fluidity definition, solutions of the fluidity model, and the proposed microscopic formula all agree. Kinetic theoretical and Eyring-like explanations shed insight into the obtained form.

  13. Equivalence between a bosonic theory and a massive non-local Thirring model at Finite Temperature

    CERN Document Server

    Manias, M V

    1998-01-01

    Using the path-integral bosonization procedure at Finite Temperature we study the equivalence between a massive Thirring model with non-local interaction between currents (NLMT) and a non-local extension of the sine-Gordon theory (NLSG). To this end we make a perturbative expansion in the mass parameter of the NLMT model and in the cosine term of the NLSG theory in order to obtain explicit expressions for the corresponding partition functions. We conclude that for certain relationship between NLMT and NLSG potentials both the fermionic and bosonic expansions are equal term by term. This result constitutes a generalization of Coleman's equivalence at T=0, when considering a Thirring model with bilocal potentials in the interaction term at Finite Temperature. The study of this model is relevant in connection with the physics of strongly correlated systems in one spatial dimension. Indeed, in the language of many-body non-relativistic systems, the relativistic mass term can be shown to represent the introduction...

  14. Three-state Potts model on non-local directed small-world lattices

    Science.gov (United States)

    Ferraz, Carlos Handrey Araujo; Lima, José Luiz Sousa

    2017-10-01

    In this paper, we study the non-local directed Small-World (NLDSW) disorder effects in the three-state Potts model as a form to capture the essential features shared by real complex systems where non-locality effects play a important role in the behavior of these systems. Using Monte Carlo techniques and finite-size scaling analysis, we estimate the infinite lattice critical temperatures and the leading critical exponents in this model. In particular, we investigate the first- to second-order phase transition crossover when NLDSW links are inserted. A cluster-flip algorithm was used to reduce the critical slowing down effect in our simulations. We find that for a NLDSW disorder densities p model exhibits a continuous phase transition falling into a new universality class, which continuously depends on the value of p, while for p∗ ⩽ p ⩽ 1 . 0, the model presents a weak first-order phase transition.

  15. On Nambu-Lie 3-algebra representations

    CERN Document Server

    Sochichiu, Corneliu

    2008-01-01

    We propose a recipe to construct matrix representations of Nambu--Lie 3-algebras in terms of irreducible representations of underlying Lie algebra. The case of Euclidean four-dimensional 3-algebra is considered in details. We find that representations of this 3-algebra are not possible in terms of only Hermitian matrices in spite of its Euclidean nature.

  16. The Composite Nambu-Goldstone Higgs

    CERN Document Server

    Panico, Giuliano

    2015-01-01

    The composite Higgs scenario, in which the Higgs emerges as a composite pseudo-Nambu-Goldstone boson, is extensively reviewed in these Notes. The material is presented in a pedagogical fashion, with great emphasis on the conceptual and technical foundations of the construction. A comprehensive summary of the flavor, collider and electroweak precision phenomenology is also presented.

  17. Nambu a foreteller of modern physics

    CERN Document Server

    Han, M Y

    2014-01-01

    Coming into the 21st century, developments in three major areas of elementary particle physics - the electroweak theory with the Higgs mechanism, quantum chromodynamics, and string theory began to yield more and more concrete and successful results. Seeds of all these developments in contemporary particle physics were sowed by Nambu in prophetic lectures and papers from the 1960s 70s. The discovery of the Higgs-like scalar particle at the Large Hadron Collider in July 2012 was the climax for the idea of spontaneous symmetry breaking that Nambu had laid down at the beginning of the 1960s. In this book, we collect what we consider to be the most prophetic of Nambu's papers for the benefit of current and future generations of particle physicists of the world and made them easily accessible for all. It also contains articles never published before in a book form. This text is not only of historical value but also provides a window to the mind of a man many refer to as "Nambu the seer." A must-have book for fu...

  18. Nonlocal correlations in the vicinity of the $\\alpha$-$\\gamma$ phase transition in iron within a DMFT plus spin-fermion model approach

    OpenAIRE

    Katanin, A. A.; Belozerov, A. S.; Anisimov, V. I.

    2016-01-01

    We consider nonlocal correlations in iron in the vicinity of the $\\alpha$-$\\gamma$ phase transition within the spin-rotationally-invariant dynamical mean-field theory (DMFT) approach, combined with the recently proposed spin-fermion model of iron. The obtained nonlocal corrections to DMFT yield a decrease of the Curie temperature of the $\\alpha$ phase, leading to an agreement with its experimental value. We show that the corresponding nonlocal corrections to the energy of the $\\alpha$ phase a...

  19. Nonlocal shear deformable shell model for postbuckling of axially compressed microtubules embedded in an elastic medium.

    Science.gov (United States)

    Shen, Hui-Shen

    2010-06-01

    Buckling and postbuckling analysis is presented for axially compressed microtubules (MTs) embedded in an elastic matrix of cytoplasm. The microtubule is modeled as a nonlocal shear deformable cylindrical shell which contains small scale effects. The surrounding elastic medium is modeled as a Pasternak foundation. The governing equations are based on higher order shear deformation shell theory with a von Kármán-Donnell-type of kinematic nonlinearity and include the extension-twist and flexural-twist couplings. The thermal effects are also included and the material properties are assumed to be temperature-dependent. The small scale parameter e (0) a is estimated by matching the buckling load from their vibrational behavior of MTs with the numerical results obtained from the nonlocal shear deformable shell model. The numerical results show that buckling load and postbuckling behavior of MTs are very sensitive to the small scale parameter e (0) a. The results reveal that the MTs under axial compressive loading condition have an unstable postbuckling path, and the lateral constraint has a significant effect on the postbuckling response of a microtubule when the foundation stiffness is sufficiently large.

  20. Nonlocal theory of curved rods. 2-D, high order, Timoshenko’s and Euler-Bernoulli models

    Directory of Open Access Journals (Sweden)

    Zozulya V.V.

    2017-09-01

    Full Text Available New models for plane curved rods based on linear nonlocal theory of elasticity have been developed. The 2-D theory is developed from general 2-D equations of linear nonlocal elasticity using a special curvilinear system of coordinates related to the middle line of the rod along with special hypothesis based on assumptions that take into account the fact that the rod is thin. High order theory is based on the expansion of the equations of the theory of elasticity into Fourier series in terms of Legendre polynomials. First, stress and strain tensors, vectors of displacements and body forces have been expanded into Fourier series in terms of Legendre polynomials with respect to a thickness coordinate. Thereby, all equations of elasticity including nonlocal constitutive relations have been transformed to the corresponding equations for Fourier coefficients. Then, in the same way as in the theory of local elasticity, a system of differential equations in terms of displacements for Fourier coefficients has been obtained. First and second order approximations have been considered in detail. Timoshenko’s and Euler-Bernoulli theories are based on the classical hypothesis and the 2-D equations of linear nonlocal theory of elasticity which are considered in a special curvilinear system of coordinates related to the middle line of the rod. The obtained equations can be used to calculate stress-strain and to model thin walled structures in micro- and nanoscales when taking into account size dependent and nonlocal effects.

  1. A non-local evolution equation model of cell-cell adhesion in higher dimensional space.

    Science.gov (United States)

    Dyson, Janet; Gourley, Stephen A; Webb, Glenn F

    2013-01-01

    A model for cell-cell adhesion, based on an equation originally proposed by Armstrong et al. [A continuum approach to modelling cell-cell adhesion, J. Theor. Biol. 243 (2006), pp. 98-113], is considered. The model consists of a nonlinear partial differential equation for the cell density in an N-dimensional infinite domain. It has a non-local flux term which models the component of cell motion attributable to cells having formed bonds with other nearby cells. Using the theory of fractional powers of analytic semigroup generators and working in spaces with bounded uniformly continuous derivatives, the local existence of classical solutions is proved. Positivity and boundedness of solutions is then established, leading to global existence of solutions. Finally, the asymptotic behaviour of solutions about the spatially uniform state is considered. The model is illustrated by simulations that can be applied to in vitro wound closure experiments.

  2. Non-local first-order modelling of crowd dynamics: a multidimensional framework with applications

    CERN Document Server

    Bruno, Luca; Tricerri, Paolo; Venuti, Fiammetta

    2010-01-01

    In this work a physical modelling framework is presented, describing the intelligent, non-local, and anisotropic behaviour of pedestrians. Its phenomenological basics and constitutive elements are detailed, and a qualitative analysis is provided. Within this common framework, two first-order mathematical models, along with related numerical solution techniques, are derived. The models are oriented to specific real world applications: a one-dimensional model of crowd-structure interaction in footbridges and a two-dimensional model of pedestrian flow in an underground station with several obstacles and exits. The noticeable heterogeneity of the applications demonstrates the significance of the physical framework and its versatility in addressing different engineering problems. The results of the simulations point out the key role played by the physiological and psychological features of human perception on the overall crowd dynamics.

  3. Buckling and postbuckling of radially loaded microtubules by nonlocal shear deformable shell model.

    Science.gov (United States)

    Shen, Hui-Shen

    2010-05-21

    This paper presents an investigation on the buckling and postbuckling of microtubules (MTs) subjected to a uniform external radial pressure in thermal environments. The microtubule is modeled as a nonlocal shear deformable cylindrical shell which contains small scale effects. The governing equations are based on higher order shear deformation shell theory with a von Kármán-Donnell-type of kinematic nonlinearity and include the extension-twist and flexural-twist couplings. The thermal effects are also included and the material properties are assumed to be temperature-dependent. A singular perturbation technique is employed to determine the buckling pressure and postbuckling equilibrium paths. The small scale parameter e(0)a is estimated by matching the buckling pressure of MTs measured from the experiments with the numerical results obtained from the nonlocal shear deformable shell model. The numerical results show that buckling pressure and postbuckling behavior of MTs are very sensitive to the small scale parameter e(0)a. The results reveal that the 13_3 microtubule has a stable postbuckling path, whereas the 13_2 microtubule has an unstable postbuckling behavior due to the presence of skew angles.

  4. A mixed SOC-turbulence model for nonlocal transport and Lévy-fractional Fokker–Planck equation

    DEFF Research Database (Denmark)

    Juul Rasmussen, Jens; Milovanov, Alexander V.

    2014-01-01

    The phenomena of nonlocal transport in magnetically confined plasma are theoretically analyzed. A hybrid model is proposed, which brings together the notion of inverse energy cascade, typical of drift-wave- and two-dimensional fluid turbulence, and the ideas of avalanching behavior, associable...... with self-organized critical (SOC) behavior. Using statistical arguments, it is shown that an amplification mechanism is needed to introduce nonlocality into dynamics. We obtain a consistent derivation of nonlocal Fokker-Planck equation with space-fractional derivatives from a stochastic Markov process...... with the transition probabilities defined in reciprocal space. The hybrid model observes the Sparre Andersen universality and defines a new universality class of SOC. (C) 2014 Elsevier B.V. All rights reserved....

  5. Nonlocal optical response in metallic nanostructures.

    Science.gov (United States)

    Raza, Søren; Bozhevolnyi, Sergey I; Wubs, Martijn; Asger Mortensen, N

    2015-05-13

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future work on nonlocal response, including experimental setups that may unveil further effects of nonlocal response.

  6. Nonlocal optical response in metallic nanostructures

    DEFF Research Database (Denmark)

    Raza, Søren; Bozhevolnyi, Sergey I.; Wubs, Martijn

    2015-01-01

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response...... on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future work on nonlocal response, including experimental setups that may unveil further effects of nonlocal response....

  7. Supporting the search for the CEP location with nonlocal PNJL models constrained by lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Contrera, Gustavo A. [IFLP, UNLP, CONICET, Facultad de Ciencias Exactas, La Plata (Argentina); Gravitation, Astrophysics and Cosmology Group, FCAyG, UNLP, La Plata (Argentina); CONICET, Buenos Aires (Argentina); Grunfeld, A.G. [CONICET, Buenos Aires (Argentina); Comision Nacional de Energia Atomica, Departamento de Fisica, Buenos Aires (Argentina); Blaschke, David [University of Wroclaw, Institute of Theoretical Physics, Wroclaw (Poland); Joint Institute for Nuclear Research, Moscow Region (Russian Federation); National Research Nuclear University (MEPhI), Moscow (Russian Federation)

    2016-08-15

    We investigate the possible location of the critical endpoint in the QCD phase diagram based on nonlocal covariant PNJL models including a vector interaction channel. The form factors of the covariant interaction are constrained by lattice QCD data for the quark propagator. The comparison of our results for the pressure including the pion contribution and the scaled pressure shift Δ P/T {sup 4} vs. T/T{sub c} with lattice QCD results shows a better agreement when Lorentzian form factors for the nonlocal interactions and the wave function renormalization are considered. The strength of the vector coupling is used as a free parameter which influences results at finite baryochemical potential. It is used to adjust the slope of the pseudocritical temperature of the chiral phase transition at low baryochemical potential and the scaled pressure shift accessible in lattice QCD simulations. Our study, albeit presently performed at the mean-field level, supports the very existence of a critical point and favors its location within a region that is accessible in experiments at the NICA accelerator complex. (orig.)

  8. Nonlocal sparse model with adaptive structural clustering for feature extraction of aero-engine bearings

    Science.gov (United States)

    Zhang, Han; Chen, Xuefeng; Du, Zhaohui; Li, Xiang; Yan, Ruqiang

    2016-04-01

    Fault information of aero-engine bearings presents two particular phenomena, i.e., waveform distortion and impulsive feature frequency band dispersion, which leads to a challenging problem for current techniques of bearing fault diagnosis. Moreover, although many progresses of sparse representation theory have been made in feature extraction of fault information, the theory also confronts inevitable performance degradation due to the fact that relatively weak fault information has not sufficiently prominent and sparse representations. Therefore, a novel nonlocal sparse model (coined NLSM) and its algorithm framework has been proposed in this paper, which goes beyond simple sparsity by introducing more intrinsic structures of feature information. This work adequately exploits the underlying prior information that feature information exhibits nonlocal self-similarity through clustering similar signal fragments and stacking them together into groups. Within this framework, the prior information is transformed into a regularization term and a sparse optimization problem, which could be solved through block coordinate descent method (BCD), is formulated. Additionally, the adaptive structural clustering sparse dictionary learning technique, which utilizes k-Nearest-Neighbor (kNN) clustering and principal component analysis (PCA) learning, is adopted to further enable sufficient sparsity of feature information. Moreover, the selection rule of regularization parameter and computational complexity are described in detail. The performance of the proposed framework is evaluated through numerical experiment and its superiority with respect to the state-of-the-art method in the field is demonstrated through the vibration signals of experimental rig of aircraft engine bearings.

  9. Searching for the CEP location with nonlocal PNJL models constrained by Lattice QCD

    CERN Document Server

    Contrera, Gustavo A; Blaschke, David

    2016-01-01

    We investigate the possible location of the critical end point in the QCD phase diagram based on nonlocal covariant PNJL models including a vector interaction channel. The form factors of the covariant interaction are constrained by lattice QCD data for the quark propagator. The comparison of our results for the pressure including the pion contribution and the scaled pressure shift $\\Delta P / T^4$ vs $T/T_c$ with lattice QCD results shows a better agreement when Lorentzian formfactors for the nonlocal interactions and the wave function renormalization are considered. The strength of the vector coupling is used as a free parameter which influences on results at finite baryochemical potential. It is used to adjust the slope of the pseudocritical temperature of the chiral phase transition at low baryochemical potential and the scaled pressure shift accessible in lattice QCD simulations. Our study supports the existence of a critical point and favors for its location the region $69.9~{\\rm MeV}\\le T_{\\rm CEP} \\le...

  10. Variational Principles for Buckling of Microtubules Modeled as Nonlocal Orthotropic Shells

    Directory of Open Access Journals (Sweden)

    Sarp Adali

    2014-01-01

    Full Text Available A variational principle for microtubules subject to a buckling load is derived by semi-inverse method. The microtubule is modeled as an orthotropic shell with the constitutive equations based on nonlocal elastic theory and the effect of filament network taken into account as an elastic surrounding. Microtubules can carry large compressive forces by virtue of the mechanical coupling between the microtubules and the surrounding elastic filament network. The equations governing the buckling of the microtubule are given by a system of three partial differential equations. The problem studied in the present work involves the derivation of the variational formulation for microtubule buckling. The Rayleigh quotient for the buckling load as well as the natural and geometric boundary conditions of the problem is obtained from this variational formulation. It is observed that the boundary conditions are coupled as a result of nonlocal formulation. It is noted that the analytic solution of the buckling problem for microtubules is usually a difficult task. The variational formulation of the problem provides the basis for a number of approximate and numerical methods of solutions and furthermore variational principles can provide physical insight into the problem.

  11. Derivation of a non-local interfacial model for 3D wetting in an external field

    Energy Technology Data Exchange (ETDEWEB)

    Bernardino, N R [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Parry, A O [Department of Mathematics, Imperial College London, London SW7 2BZ (United Kingdom); Rascon, C [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, E-28911 Leganes, Madrid (Spain); Romero-Enrique, J M [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Apartado de Correos 1065, E-41080 Seville (Spain)

    2009-11-18

    We extend recent studies of 3D short-ranged wetting transitions by deriving an interfacial Hamiltonian in the presence of an arbitrary external field. The binding potential functional, describing the interaction of the interface and the substrate, can still be written in a diagrammatic form, but now includes new classes of diagrams due to the coupling to the external potential, which are determined exactly. Applications to systems with long-ranged (algebraically decaying) and short-ranged (exponentially decaying) external potentials are considered at length. We show how the familiar 'sharp-kink' approximation to the binding potential emerges, and determine the corrections to this arising from interactions between bulk-like fluctuations and the external field. A connection is made with earlier local effective interfacial Hamiltonian approaches. It is shown that, for the case of an exponentially decaying potential, non-local effects have a particularly strong influence on the approach to the critical regime at second-order wetting transitions, even when they appear to be sub-dominant. This is confirmed by Monte Carlo simulation studies of a discretized version of a non-local interfacial model.

  12. Spinodal Instabilities of Baryon-Rich Quark-gluon Plasma in the PNJL Model

    CERN Document Server

    Li, Feng

    2016-01-01

    Using the Polyakov-Nambu-Jona-Lasinia (PNJL) model, we study the spinodal instability of a baryon-rich quark-gluon plasma in the linear response theory. We find that the spinodal unstable region in the temperature and density plane shrinks with increasing wave number of the unstable mode and is also reduced if the effect of Polyakov loop is not included. In the small wave number or long wavelength limit, the spinodal boundaries in both cases of with and without the Polyakov loop coincide with those determined from the isothermal spinodal instability in the thermodynamic approach. Also, the vector interactions among quarks is found to suppress unstable modes of all wave numbers. Moreover, the growth rate of unstable modes initially increases with the wave number but is reduced when the wave number becomes large. Including the collisional effect from quark scattering via the linearized Boltzmann equation, we further find that it decreases the growth rate of unstable modes of all wave numbers. Relevance of these...

  13. A nonlocal model for fluid-structure interaction with applications in hydraulic fracturing

    CERN Document Server

    Turner, Daniel Z

    2012-01-01

    Modeling important engineering problems related to flow-induced damage (in the context of hydraulic fracturing among others) depends critically on characterizing the interaction of porous media and interstitial fluid flow. This work presents a new formulation for incorporating the effects of pore pressure in a nonlocal representation of solid mechanics. The result is a framework for modeling fluid-structure interaction problems with the discontinuity capturing advantages of an integral based formulation. A number of numerical examples are used to show that the proposed formulation can be applied to measure the effect of leak-off during hydraulic fracturing as well as modeling consolidation of fluid saturated rock and surface subsidence caused by fluid extraction from a geologic reservoir. The formulation incorporates the effect of pore pressure in the constitutive description of the porous material in a way that is appropriate for nonlinear materials, easily implemented in existing codes, straightforward in i...

  14. Power-Counting Theorem for Non-Local Matrix Models and Renormalisation

    Science.gov (United States)

    Grosse, Harald; Wulkenhaar, Raimar

    2005-02-01

    Solving the exact renormalisation group equation à la Wilson-Polchinski perturbatively, we derive a power-counting theorem for general matrix models with arbitrarily non-local propagators. The power-counting degree is determined by two scaling dimensions of the cut-off propagator and various topological data of ribbon graphs. As a necessary condition for the renormalisability of a model, the two scaling dimensions have to be large enough relative to the dimension of the underlying space. In order to have a renormalisable model one needs additional locality properties—typically arising from orthogonal polynomials—which relate the relevant and marginal interaction coefficients to a finite number of base couplings. The main application of our power-counting theorem is the renormalisation of field theories on noncommutative RD in matrix formulation.

  15. Quantum Entanglement and Nonlocality Properties of Two-Mode Squeezed Thermal States in a Common-Reservoir Model

    Institute of Scientific and Technical Information of China (English)

    XIANG Shao-Hua; SONG Ke-Hui; WEN Wei; SHI Zhen-Gang

    2011-01-01

    We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general, explicit, and exact solutions to its master equation by means of the characteristic function method. We analyze the entanglement dynamics of two-mode squeezed thermal state in this model and show that its entanglement dynamics is strongly determined by the two-mode squeezing parameter and the purity. In particular, we find that two-mode squeezed thermal state with the squeezing parameter r ≤ -(1/2) In (V)u is extremely fragile and almost does not survive in a common vacuum environment. We investigate the time evolution of nonlocality for two-mode squeezed thermal state in such an environment. It is found that the evolved state loses its nonlocality in the beginning of the evolution, but after a time, the revival of nonlocality can occur.

  16. Dynamical Breaking of Generalized Yang-Mills Theory

    Institute of Scientific and Technical Information of China (English)

    WANGDian-Fu; SONGHe-Shan

    2004-01-01

    The dynamical breaking of a generalized Yang-Mills theory is discussed. It is shown, in terms of the Nambu Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the generalized Yang-Mills theory. The combination of the generalized Yang-Mills theory and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.

  17. Dynamical Breaking of Generalized Yang-Mills Theory

    Institute of Scientific and Technical Information of China (English)

    WANG Dian-Fu; SONG He-Shah

    2004-01-01

    The dynamical breaking of a generalized Yang-Mills theory is discussed. It is shown, in terms of the Nambu-Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the generalized Yang-Mills theory. The combination of the generalized Yang-Mills theory and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.

  18. Fermionic cosmologies with Yukawa type interactions

    CERN Document Server

    Ribas, Marlos O; Kremer, Gilberto M

    2010-01-01

    In this work we discuss if fermionic sources could be responsible for accelerated periods in a Friedmann-Robertson-Walker spatially flat universe, including a usual self-interaction potential of the Nambu-Jona-Lasinio type together with a fermion-scalar interaction potential of the Yukawa type. The results show that the combination of these potentials could promote an initially accelerated period, going through a middle decelerated era, with a final eternal accelerated period, where the self-interaction contribution dominates.

  19. A simple nonlocal damage model for predicting failure of notched laminates

    Science.gov (United States)

    Kennedy, T. C.; Nahan, M. F.

    1995-01-01

    The ability to predict failure loads in notched composite laminates is a requirement in a variety of structural design circumstances. A complicating factor is the development of a zone of damaged material around the notch tip. The objective of this study was to develop a computational technique that simulates progressive damage growth around a notch in a manner that allows the prediction of failure over a wide range of notch sizes. This was accomplished through the use of a relatively simple, nonlocal damage model that incorporates strain-softening. This model was implemented in a two-dimensional finite element program. Calculations were performed for two different laminates with various notch sizes under tensile loading, and the calculations were found to correlate well with experimental results.

  20. Velocity selection at large undercooling in a two-dimensional nonlocal model of solidification

    Science.gov (United States)

    Barbieri, Angelo

    1987-01-01

    The formation of needle-crystal dendrites from an undercooled melt is investigated analytically, applying the method of Caroli et al. (1986) to Langer's (1980) symmetric two-dimensional nonlocal model of solidification with finite anisotropy in the limit of large undercooling. A solution based on the WKB approximation is obtained, and a saddle-point evaluation is performed. It is shown that needle-crystal solutions exist only if the capillary anisotropy is nonzero, in which case a particular value of the growth velocity can be selected. This finding and the expression for the dependence of the selected velocity on the singular perturbation parameter and the strength of the anisotropy are found to be in complete agreement with the results of a boundary-layer model (Langer and Hong, 1986).

  1. Non-local convergence coupling in a simple stochastic convection model

    Science.gov (United States)

    Brenowitz, N. D.; Frenkel, Y.; Majda, A. J.

    2016-06-01

    Observational studies show a strong correlation between large-scale wind convergence and precipitation. However, using this as a convective closure assumption to determine the total precipitation in a numerical model typically leads to deleterious wave-CISK behavior such as grid-scale noise. The quasi-equilibrium (QE) schemes ameliorate this issue and smooth the precipitation field, but still inadequately represent the intermittent and organized nature of tropical convection. However, recent observational evidence highlights that the large-scale convergence field primarily affects precipitation by increasing the overall convective cloud fraction rather than the energetics of individual convective elements. In this article, the dynamical consequences of this diagnostic observation are studied using a simple one baroclinic mode stochastic model for convectively coupled waves. A version of this model is implemented which couples the stochastic formation of convective elements to the wind convergence. Linearized analysis shows that using the local convergence results in a classic wave-CISK standing instability where the growth rate increases with the wavenumber. However, using a large-scale averaged convergence restricts the instability to physically plausible scales. Convergence coupling is interpreted as a surrogate for the non-local effects of gregarious convection. In nonlinear stochastic simulations with a non-uniform imposed sea surface temperature (SST) field, the non-local convergence coupling introduces desirable intermittent variability on intraseasonal time scales. Convergence coupling leads to a circulation with a similar mean but higher variability than the equivalent parameterization without convergence coupling. Finally, the model is shown to retain these features on fine and coarse mesh sizes.

  2. Integro-differential equations of fractional order with nonlocal fractional boundary conditions associated with financial asset model

    Directory of Open Access Journals (Sweden)

    Bashir Ahmad

    2013-02-01

    Full Text Available In this article, we discuss the existence of solutions for a boundary-value problem of integro-differential equations of fractional order with nonlocal fractional boundary conditions by means of some standard tools of fixed point theory. Our problem describes a more general form of fractional stochastic dynamic model for financial asset. An illustrative example is also presented.

  3. Nambu quantum mechanics on discrete 3-tori

    Energy Technology Data Exchange (ETDEWEB)

    Axenides, M [National Research Center ' Demokritos' , 15310 Aghia Paraskevi, Athens (Greece); Floratos, E G [Nuclear and Particle Physics Section, University of Athens, 15771 Athens (Greece); Nicolis, S [CNRS-Laboratoire de Mathematiques et Physique Theorique (UMR 6083) Federation Denis Poisson (FR 9164) Universite de Tours ' Francois Rabelais' , Parc Grandmont, 37200 Tours (France)], E-mail: axenides@inp.demokritos.gr, E-mail: mflorato@physics.uoa.gr, E-mail: Stam.Nicolis@lmpt.univ-tours.fr

    2009-07-10

    We propose a quantization of linear, volume preserving, maps on the discrete and finite 3-torus T{sub N}{sup 3} represented by elements of the group SL(3,Z{sub N}). These flows can be considered as special motions of the Nambu dynamics (linear Nambu flows) in the three-dimensional toroidal phase space and are characterized by invariant vectors a of T{sub N}{sup 3}. We quantize all such flows, which are necessarily restricted on a planar two-dimensional phase space, embedded in the 3-torus, transverse to the vector a. The corresponding maps belong to the little group of a element of SL(3,Z{sub N}), which is an SL(2,Z{sub N}) subgroup. The associated linear Nambu maps are generated by a pair of linear and quadratic Hamiltonians (Clebsch-Monge potentials of the flow) and the corresponding quantum maps realize the metaplectic representation of SL(3,Z{sub N}) on the discrete group of three-dimensional magnetic translations, i.e. the non-commutative 3-torus with a deformation parameter the Nth root of unity. Other potential applications of our construction are related to the quantization of deterministic chaos in turbulent maps as well as to quantum tomography of three-dimensional objects.

  4. New non-local lattice models for the description of wave dispersion in concrete

    Science.gov (United States)

    Iliopoulos, Sokratis N.; Polyzos, Demosthenes; Aggelis, Dimitrios G.

    2015-03-01

    The propagation of longitudinal waves through concrete materials is strongly affected by dispersion. This is clearly indicated experimentally from the increase of phase velocity at low frequencies whereas many attempts have been made to explain this behavior analytically. Since the classical elastic theory for bulk media is by default non-dispersive, enhanced theories have been developed. The most commonly used higher order theory is the dipolar gradient elastic theory which takes into account the microstructural effects in heterogeneous media like concrete. The microstructural effects are described by two internal length scale parameters (g and h) which correspond to the micro-stiffness and micro-inertia respectively. In the current paper, this simplest possible version of the general gradient elastic theory proposed by Mindlin is reproduced through non-local lattice models consisting of discrete springs and masses. The masses simulate the aggregates of the concrete specimen whereas the springs are the mechanical similitude of the concrete matrix. The springs in these models are connecting the closest masses between them as well as the second or third closest to each other masses creating a non-local system of links. These non-neighboring interactions are represented by massless springs of constant stiffness while on the other hand one cannot neglect the significant mass of the springs connecting neighboring masses as this is responsible for the micro-inertia term. The major advantage of the presented lattice models is the fact that the considered microstructural effects can be accurately expressed as a function of the size and the mechanical properties of the microstructure.

  5. Nonlocal regularization for active appearance model: Application to medial temporal lobe segmentation.

    Science.gov (United States)

    Hu, Shiyan; Coupé, Pierrick; Pruessner, Jens C; Collins, D Louis

    2014-02-01

    The human medial temporal lobe (MTL) is an important part of the limbic system, and its substructures play key roles in learning, memory, and neurodegeneration. The MTL includes the hippocampus (HC), amygdala (AG), parahippocampal cortex (PHC), entorhinal cortex, and perirhinal cortex--structures that are complex in shape and have low between-structure intensity contrast, making them difficult to segment manually in magnetic resonance images. This article presents a new segmentation method that combines active appearance modeling and patch-based local refinement to automatically segment specific substructures of the MTL including HC, AG, PHC, and entorhinal/perirhinal cortex from MRI data. Appearance modeling, relying on eigen-decomposition to analyze statistical variations in image intensity and shape information in study population, is used to capture global shape characteristics of each structure of interest with a generative model. Patch-based local refinement, using nonlocal means to compare the image local intensity properties, is applied to locally refine the segmentation results along the structure borders to improve structure delimitation. In this manner, nonlocal regularization and global shape constraints could allow more accurate segmentations of structures. Validation experiments against manually defined labels demonstrate that this new segmentation method is computationally efficient, robust, and accurate. In a leave-one-out validation on 54 normal young adults, the method yielded a mean Dice κ of 0.87 for the HC, 0.81 for the AG, 0.73 for the anterior parts of the parahippocampal gyrus (entorhinal and perirhinal cortex), and 0.73 for the posterior parahippocampal gyrus.

  6. Nonlocal optical response in metallic nanostructures

    OpenAIRE

    Raza, Søren; Bozhevolnyi, Sergey I.; Wubs, Martijn; Mortensen, N. Asger

    2014-01-01

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future w...

  7. Acausality in Nonlocal Gravity Theory

    CERN Document Server

    Zhang, Ying-li; Sasaki, Misao; Zhao, Gong-Bo

    2016-01-01

    We investigate the nonlocal gravity theory by deriving nonlocal equations of motion using the traditional variation principle in a homogeneous background. We focus on a class of models with a linear nonlocal modification term in the action. It is found that the resulting equations of motion contain the advanced Green's function, implying that there is an acausality problem. As a consequence, a divergence arises in the solutions due to contributions from the future infinity unless the Universe will go back to the radiation dominated era or become the Minkowski spacetime in the future. We also discuss the relation between the original nonlocal equations and its biscalar-tensor representation and identify the auxiliary fields with the corresponding original nonlocal terms. Finally, we show that the acusality problem cannot be avoided by any function of nonlocal terms in the action.

  8. Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model

    Science.gov (United States)

    Farkašovský, Pavol

    2017-04-01

    We study the combined effects of local and nonlocal hybridization on the formation and condensation of the excitonic bound states in the extended Falicov-Kimball model by the density-matrix-renormalization-group (DMRG) method. Analysing the resultant behaviours of the excitonic momentum distribution N(q) we found, that unlike the local hybridization V, which supports the formation of the q=0 momentum condensate, the nonlocal hybridization Vn supports the formation of the q = π momentum condensate. The combined effect of local and nonlocal hybridization further enhances the excitonic correlations in q=0 as well as q = π state, especially for V and Vn values from the charge-density-wave (CDW) region. Strong effects of local and nonlocal hybridization are observed also for other ground-state quantities of the model such as the f-electron density, or the density of unbound d-electrons, which are generally enhanced with increasing V and Vn. The same calculations performed for nonzero values of f-level energy Ef revealed that this model can yield a reasonable explanation for the pressure-induced resistivity anomaly observed experimentally in TmSe0.45Te0.55 compound.

  9. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images

    Science.gov (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian

    2014-06-01

    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16 dB with a small 5.4% loss of similarity.

  10. Natural frequencies and buckling of pressurized nanotubes using shear deformable nonlocal shell model

    Energy Technology Data Exchange (ETDEWEB)

    Firouz-Abadi, R. D.; Fotouhi, M. M.; Permoon, M. R.; Haddadpour, H. [Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2012-02-15

    The small-scale effect on the natural frequencies and buckling of pressurized nanotubes is investigated in this study. Based on the firstorder shear deformable shell theory, the nonlocal theory of elasticity is used to account for the small-scale effect and the governing equations of motion are obtained. Applying modal analysis technique and based on Galerkin's method a procedure is proposed to obtain natural frequencies of vibrations. For the case of nanotubes with simply supported boundary conditions, explicit expressions are obtained which establish the dependency of the natural frequencies and buckling loads of the nanotube on the small-scale parameter and natural frequencies obtained by local continuum mechanics. The obtained solutions generalize the results of nano-bar and -beam models and are verified by the literature. Based on several numerical studies some conclusions are drawn about the small-scale effect on the natural frequencies and buckling pressure of the nanotubes.

  11. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images.

    Science.gov (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian

    2014-06-01

    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16  dB with a small 5.4% loss of similarity.

  12. A fast collocation method for a variable-coefficient nonlocal diffusion model

    Science.gov (United States)

    Wang, Che; Wang, Hong

    2017-02-01

    We develop a fast collocation scheme for a variable-coefficient nonlocal diffusion model, for which a numerical discretization would yield a dense stiffness matrix. The development of the fast method is achieved by carefully handling the variable coefficients appearing inside the singular integral operator and exploiting the structure of the dense stiffness matrix. The resulting fast method reduces the computational work from O (N3) required by a commonly used direct solver to O (Nlog ⁡ N) per iteration and the memory requirement from O (N2) to O (N). Furthermore, the fast method reduces the computational work of assembling the stiffness matrix from O (N2) to O (N). Numerical results are presented to show the utility of the fast method.

  13. Numerical corrections to the strong coupling effective Polyakov-line action for finite T Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Bergner, G. [Universität Bern, Institut für Theoretische Physik,Länggasse, 3012 Bern (Switzerland); Langelage, J.; Philipsen, O. [Institut für Theoretische Physik, Goethe-Universität Frankfurt,Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)

    2015-11-04

    We consider a three-dimensional effective theory of Polyakov lines derived previously from lattice Yang-Mills theory and QCD by means of a resummed strong coupling expansion. The effective theory is useful for investigations of the phase structure, with a sign problem mild enough to allow simulations also at finite density. In this work we present a numerical method to determine improved values for the effective couplings directly from correlators of 4d Yang-Mills theory. For values of the gauge coupling up to the vicinity of the phase transition, the dominant short range effective coupling are well described by their corresponding strong coupling series. We provide numerical results also for the longer range interactions, Polyakov lines in higher representations as well as four-point interactions, and discuss the growing significance of non-local contributions as the lattice gets finer. Within this approach the critical Yang-Mills coupling β{sub c} is reproduced to better than one percent from a one-coupling effective theory on N{sub τ}=4 lattices while up to five couplings are needed on N{sub τ}=8 for the same accuracy.

  14. A non-local, ordinary-state-based viscoelasticity model for peridynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, John Anthony

    2011-10-01

    A non-local, ordinary-state-based, peridynamics viscoelasticity model is developed. In this model, viscous effects are added to deviatoric deformations and the bulk response remains elastic. The model uses internal state variables and is conceptually similar to linearized isotropic viscolelasticity in the local theory. The modulus state, which is used to form the Jacobian matrix in Newton-Raphson algorithms, is presented. The model is shown to satisfy the 2nd law of thermodynamics and is applicable to problems in solid continuum mechanics where fracture and rate effects are important; it inherits all the advantages for modeling fracture associated with peridynamics. By combining this work with the previously published ordinary-state-based plasticity model, the model may be amenable to viscoplasticity problems where plasticity and rate effects are simultaneously important. Also, the model may be extended to include viscous effects for spherical deformations as well. The later two extensions are not presented and may be the subject of further work.

  15. Exploring the renormalization of quantum discord and Bell non-locality in the one-dimensional transverse Ising model

    Science.gov (United States)

    Liu, Cheng-cheng; Shi, Jia-dong; Ding, Zhi-yong; Ye, Liu

    2016-08-01

    In this paper, the effect of external magnet field g on the relationship among the quantum discord, Bell non-locality and quantum phase transition by employing quantum renormalization-group (QRG) method in the one-dimensional transverse Ising model is investigated. In our model, external magnet field g can influence the phase diagrams. The results have shown that both the two quantum correlation measures can develop two saturated values, which are associated with two distinct phases: long-ranged ordered Ising phase and the paramagnetic phase with the number of QRG iterations increasing. Additionally, quantum non-locality always existent in the long-ranged ordered Ising phase no matter whatever the value of g is and what times QRG steps are carried out and we conclude that the quantum non-locality always exists not only suitable for the two sites of block, but for nearest-neighbor blocks in the long-ranged ordered Ising phase. However, the block-block correlation in the paramagnetic phase is not strong enough to violate the Bell-CHSH inequality as the size of system becomes large. Furthermore, when the system violates the CHSH inequality, i.e., satisfies quantum non-locality, it needs to be entangled. On the other way, if the system obeys the CHSH inequality, it may be entangled or not. To gain further insight, the non-analytic and scaling behavior of QD and Bell non-locality have also been analyzed in detail and this phenomenon indicates that the behavior of the correlation can perfectly help one to observe the quantum critical properties of the model.

  16. Pre-buckling responses of Timoshenko nanobeams based on the integral and differential models of nonlocal elasticity: an isogeometric approach

    Science.gov (United States)

    Norouzzadeh, A.; Ansari, R.; Rouhi, H.

    2017-05-01

    Differential form of Eringen's nonlocal elasticity theory is widely employed to capture the small-scale effects on the behavior of nanostructures. However, paradoxical results are obtained via the differential nonlocal constitutive relations in some cases such as in the vibration and bending analysis of cantilevers, and recourse must be made to the integral (original) form of Eringen's theory. Motivated by this consideration, a novel nonlocal formulation is developed herein based on the original formulation of Eringen's theory to study the buckling behavior of nanobeams. The governing equations are derived according to the Timoshenko beam theory, and are represented in a suitable vector-matrix form which is applicable to the finite-element analysis. In addition, an isogeometric analysis (IGA) is conducted for the solution of buckling problem. Construction of exact geometry using non-uniform rational B-splines and easy implementation of geometry refinement tools are the main advantages of IGA. A comparison study is performed between the predictions of integral and differential nonlocal models for nanobeams under different kinds of end conditions.

  17. A coupled interface-body nonlocal damage model for the analysis of FRP strengthening detachment from cohesive material

    Directory of Open Access Journals (Sweden)

    J. Toti

    2011-10-01

    Full Text Available In the present work, a new model of the FRP-concrete or masonry interface, which accounts for the coupling occurring between the degradation of the cohesive material and the FRP detachment, is presented; in particular, a coupled interface-body nonlocal damage model is proposed. A nonlocal damage and plasticity model is developed for the quasi-brittle material. For the interface, a model which accounts for the mode I, mode II and mixed mode of damage and for the unilateral contact and friction effects is developed. Two different ways of performing the coupling between the body damage and the interface damage are proposed and compared. Some numerical applications are carried out in order to assess the performances of the proposed model in reproducing the mechanical behavior of the masonry elements strengthened with external FRP reinforcements.

  18. Existence Results for a Michaud Fractional, Nonlocal, and Randomly Position Structured Fragmentation Model

    Directory of Open Access Journals (Sweden)

    Emile Franc Doungmo Goufo

    2014-01-01

    Full Text Available Until now, classical models of clusters’ fission remain unable to fully explain strange phenomena like the phenomenon of shattering (Ziff and McGrady, 1987 and the sudden appearance of infinitely many particles in some systems having initial finite number of particles. That is why there is a need to extend classical models to models with fractional derivative order and use new and various techniques to analyze them. In this paper, we prove the existence of strongly continuous solution operators for nonlocal fragmentation models with Michaud time derivative of fractional order (Samko et al., 1993. We focus on the case where the splitting rate is dependent on size and position and where new particles generating from fragmentation are distributed in space randomly according to some probability density. In the analysis, we make use of the substochastic semigroup theory, the subordination principle for differential equations of fractional order (Prüss, 1993, Bazhlekova, 2000, the analogy of Hille-Yosida theorem for fractional model (Prüss, 1993, and useful properties of Mittag-Leffler relaxation function (Berberan-Santos, 2005. We are then able to show that the solution operator to the full model is positive and contractive.

  19. Image Denoising via Bandwise Adaptive Modeling and Regularization Exploiting Nonlocal Similarity.

    Science.gov (United States)

    Xiong, Ruiqin; Liu, Hangfan; Zhang, Xinfeng; Zhang, Jian; Ma, Siwei; Wu, Feng; Gao, Wen

    2016-09-27

    This paper proposes a new image denoising algorithm based on adaptive signal modeling and regularization. It improves the quality of images by regularizing each image patch using bandwise distribution modeling in transform domain. Instead of using a global model for all the patches in an image, it employs content-dependent adaptive models to address the non-stationarity of image signals and also the diversity among different transform bands. The distribution model is adaptively estimated for each patch individually. It varies from one patch location to another and also varies for different bands. In particular, we consider the estimated distribution to have non-zero expectation. To estimate the expectation and variance parameters for every band of a particular patch, we exploit the nonlocal correlation in image to collect a set of highly similar patches as the data samples to form the distribution. Irrelevant patches are excluded so that such adaptively-learned model is more accurate than a global one. The image is ultimately restored via bandwise adaptive soft-thresholding, based on a Laplacian approximation of the distribution of similar-patch group transform coefficients. Experimental results demonstrate that the proposed scheme outperforms several state-of-the-art denoising methods in both the objective and the perceptual qualities.

  20. An improved and fully implicit multi-group non-local electron transport model and its validations

    Science.gov (United States)

    Sijoy, C. D.; Mishra, V.; Chaurasia, S.

    2017-09-01

    The combined effect of thermal flux inhibition and non-local electron heat flux in the radiation hydrodynamics (RHD) simulation of laser-driven systems can be accurately predicted by using non-local electron transport (NLET) models. These models can avoid commonly used space and time-independent ad-hoc flux-limiting procedures. However, the use of classical electron collision frequency in these models is rigorously valid for high temperature non-degenerate plasmas. In laser-driven systems, the electron thermal energy transport is important in regions between the critical density and ablation surface where the plasma is partially degenerate. Therefore, an improved model for electron collision frequency in this regime is required to accurately predict the thermal energy transport. Previously, we have reported an improved single group non-local electron transport model by using a wide-range electron collision frequency model valid from warm-dense matter (WDM) to fully ionized plasmas. In this work, we have extended this idea into a two-dimensional multi-group non-local electron transport (MG-NLET) model. Moreover, we have used a fully implicit numerical integration scheme in which the models for multi-group thermal radiation transport, laser absorption, electron-ion thermal energy relaxation and ion heat conduction are included in a single step. The performance of this improved MG-NLET model has been assessed by comparing the simulated foil trajectories with the reported experimental data for laser-driven plastic foils. The results indicate that the improved model yields results that are in better agreement with the experimental data.

  1. Non-local Closure Models for Large Eddy Simulations using the Mori-Zwanzig Formalism

    CERN Document Server

    Parish, Eric J

    2016-01-01

    This work uses the Mori-Zwanzig (M-Z) formalism, a concept originating from non-equilibrium statistical mechanics, as a basis for the development of coarse-grained models of turbulence. The mechanics of the generalized Langevin equation (GLE) are considered and a methodology for approximating the orthogonal (unresolved) dynamics equation is presented. Insight gained from the GLE is used as a starting point for model development. A class of sub-grid models is considered which represent non-local behavior via a finite memory approximation (Stinis, 2012), the length of which is determined using a heuristic that is related to the spectral radius of the Jacobian of the resolved variables. The resulting models are intimately tied to the underlying numerical resolution and are capable of approximating non-Markovian effects. Numerical experiments on the Burgers equation demonstrate that the M-Z based models can accurately predict the temporal evolution of the total kinetic energy and the total dissipation rate at var...

  2. UV completion of the Starobinsky model, tensor-to-scalar ratio, and constraints on non-locality

    CERN Document Server

    Edholm, James

    2016-01-01

    In this paper, we build upon the successes of the ultraviolet (UV) completion of the Starobinsky model of inflation. This involves an extension of the Einstein-Hilbert term by an infinite covariant derivative theory of gravity, which is quadratic in curvature. It has been shown that such a theory can potentially resolve the cosmological singularity for a flat, homogeneous and isotropic geometry, and now it can also provide a successful cosmological inflation model, which in the infrared matches all the predictions of the Starobinsky model of inflation. The aim of this note is to show that the tensor-to-scalar ratio is modified by the scale of non-locality, and in general a wider range of tensor-to-scalar ratios can be obtained in this class of model, which can put a lower bound on the scale of non-locality for the first time as large as the O$(10^{14})$ GeV.

  3. Modeling the Dynamic Failure of Railroad Tank Cars Using a Physically Motivated Internal State Variable Plasticity/Damage Nonlocal Model

    Directory of Open Access Journals (Sweden)

    Fazle R. Ahad

    2013-01-01

    Full Text Available We used a physically motivated internal state variable plasticity/damage model containing a mathematical length scale to idealize the material response in finite element simulations of a large-scale boundary value problem. The problem consists of a moving striker colliding against a stationary hazmat tank car. The motivations are (1 to reproduce with high fidelity finite deformation and temperature histories, damage, and high rate phenomena that may arise during the impact accident and (2 to address the material postbifurcation regime pathological mesh size issues. We introduce the mathematical length scale in the model by adopting a nonlocal evolution equation for the damage, as suggested by Pijaudier-Cabot and Bazant in the context of concrete. We implement this evolution equation into existing finite element subroutines of the plasticity/failure model. The results of the simulations, carried out with the aid of Abaqus/Explicit finite element code, show that the material model, accounting for temperature histories and nonlocal damage effects, satisfactorily predicts the damage progression during the tank car impact accident and significantly reduces the pathological mesh size effects.

  4. Local and Nonlocal Impacts of Soil Moisture Initialization on AGCM Seasonal Forecasts: A Model Sensitivity Study.

    Science.gov (United States)

    Zhang, H.; Frederiksen, C. S.

    2003-07-01

    Using a version of the Australian Bureau of Meteorology Research Centre (BMRC) atmospheric general circulation model, this study investigates the model's sensitivity to different soil moisture initial conditions in its dynamically extended seasonal forecasts of June-August 1998 climate anomalies, with focus on the south and northeast China regions where severe floods occurred. The authors' primary aim is to understand the model's responses to different soil moisture initial conditions in terms of the physical and dynamical processes involved. Due to a lack of observed global soil moisture data, the efficacy of using soil moisture anomalies derived from the NCEP-NCAR reanalysis is assessed. Results show that by imposing soil moisture percentile anomalies derived from the reanalysis data into the BMRC model initial condition, the regional features of the model's simulation of seasonal precipitation and temperature anomalies are modulated. Further analyses reveal that the impacts of soil moisture conditions on the model's surface temperature forecasts are mainly from localized interactions between land surface and the overlying atmosphere. In contrast, the model's sensitivity in its forecasts of rainfall anomalies is mainly due to the nonlocal impacts of the soil moisture conditions. Over the monsoon-dominated east Asian region, the contribution from local water recycling, through surface evaporation, to the model simulation of precipitation is limited. Rather, it is the horizontal moisture transport by the regional atmospheric circulation that is the dominant factor in controlling the model rainfall. The influence of different soil moisture conditions on the model forecasts of rainfall anomalies is the result of the response of regional circulation to the anomalous soil moisture condition imposed. Results from the BMRC model sensitivity study support similar findings from other model studies that have appeared in recent years and emphasize the importance of improving

  5. TRAVELING WAVES IN A BIOLOGICAL REACTION-DIFFUSION MODEL WITH STRONG GENERIC DELAY KERNEL AND NON-LOCAL EFFECT

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,we consider the reaction diffusion equations with strong generic delay kernel and non-local effect,which models the microbial growth in a flow reactor.The existence of traveling waves is established for this model.More precisely,using the geometric singular perturbation theory,we show that traveling wave solutions exist provided that the delay is sufficiently small with the strong generic delay kernel.

  6. An approach for the modeling of interface-body coupled nonlocal damage

    Directory of Open Access Journals (Sweden)

    J. Toti

    2010-04-01

    Full Text Available Fiber Reinforced Plastic (FRP can be used for strengthening concrete or masonry constructions. One of the main problem in the use of FRP is the possible detachment of the reinforcement from the support material. This paper deals with the modeling of the FRP-concrete or masonry damage interface, accounting for the coupling occurring between the degradation of the cohesive material and the FRP detachment. To this end, a damage model is considered for the quasi-brittle material. In order to prevent strain localization and strong mesh sensitivity of the solution, an integral-type of nonlocal model based on the weighted spatial averaging of a strain-like quantity is developed. Regarding the interface, the damage is governed by the relative displacement occurring at bond. A suitable interface model which accounts for the mode I, mode II and mixed mode of damage is developed. The coupling between the body damage and the interface damage is performed computing the body damage on the bond surface. Numerical examples are presented.

  7. Algebraic and group structure for bipartite anisotropic Ising model on a non-local basis

    Science.gov (United States)

    Delgado, Francisco

    2015-01-01

    Entanglement is considered a basic physical resource for modern quantum applications as Quantum Information and Quantum Computation. Interactions based on specific physical systems able to generate and sustain entanglement are subject to deep research to get understanding and control on it. Atoms, ions or quantum dots are considered key pieces in quantum applications because they are elements in the development toward a scalable spin-based quantum computer through universal and basic quantum operations. Ising model is a type of interaction generating entanglement in quantum systems based on matter. In this work, a general bipartite anisotropic Ising model including an inhomogeneous magnetic field is analyzed in a non-local basis. This model summarizes several particular models presented in literature. When evolution is expressed in the Bell basis, it shows a regular block structure suggesting a SU(2) decomposition. Then, their algebraic properties are analyzed in terms of a set of physical parameters which define their group structure. In particular, finite products of pulses in this interaction are analyzed in terms of SU(4) covering. Thus, evolution denotes remarkable properties, in particular those related potentially with entanglement and control, which give a fruitful arena for further quantum developments and generalization.

  8. A nonlocal and periodic reaction-diffusion-advection model of a single phytoplankton species.

    Science.gov (United States)

    Peng, Rui; Zhao, Xiao-Qiang

    2016-02-01

    In this article, we are concerned with a nonlocal reaction-diffusion-advection model which describes the evolution of a single phytoplankton species in a eutrophic vertical water column where the species relies solely on light for its metabolism. The new feature of our modeling equation lies in that the incident light intensity and the death rate are assumed to be time periodic with a common period. We first establish a threshold type result on the global dynamics of this model in terms of the basic reproduction number R0. Then we derive various characterizations of R0 with respect to the vertical turbulent diffusion rate, the sinking or buoyant rate and the water column depth, respectively, which in turn give rather precise conditions to determine whether the phytoplankton persist or become extinct. Our theoretical results not only extend the existing ones for the time-independent case, but also reveal new interesting effects of the modeling parameters and the time-periodic heterogeneous environment on persistence and extinction of the phytoplankton species, and thereby suggest important implications for phytoplankton growth control.

  9. Evaluating London Dispersion Interactions in DFT: A Nonlocal Anisotropic Buckingham-Hirshfeld Model.

    Science.gov (United States)

    Krishtal, A; Geldof, D; Vanommeslaeghe, K; Alsenoy, C Van; Geerlings, P

    2012-01-10

    In this work, we present a novel model, referred to as BH-DFT-D, for the evaluation of London dispersion, with the purpose to correct the performance of local DFT exchange-correlation functionals for the description of van der Waals interactions. The new BH-DFT-D model combines the equations originally derived by Buckingham [Buckingham, A. D. Adv. Chem. Phys1967, 12, 107] with the definition of distributed multipole polarizability tensors within the Hirshfeld method [Hirshfeld, F.L. Theor. Chim. Acta1977, 44, 129], resulting in nonlocal, fully anisotropic expressions. Since no damping function has been introduced yet into the model, it is suitable in its present form for the evaluation of dispersion interactions in van der Waals dimers with no or negligible overlap. The new method is tested for an extended collection of van der Waals dimers against high-level data, where it is found to reproduce interaction energies at the BH-B3LYP-D/aug-cc-pVTZ level with a mean average error (MAE) of 0.20 kcal/mol. Next, development steps of the model will consist of adding a damping function, analytical gradients, and generalization to a supramolecular system.

  10. Dynamical role of Polyakov loops in the QCD thermodynamics

    CERN Document Server

    Agasian, N O; Simonov, Yu A

    2016-01-01

    Polyakov loops $L_a(T), a=3,8,...$ are shown to give the most important nonperturbative contribution to the thermodynamic potentials. Derived from the gluonic field correlators they enter as factors into free energy. It is shown in the SU(3) case that $L_a (T)$ define to a large extent the behavior of the free energy and the trace anomaly $I(T)$ in the SU(3) case, most sensitive to nonperturbative effects.

  11. Numerical solution of nonlocal hydrodynamic Drude model for arbitrary shaped nano-plasmonic structures using finite elements method

    CERN Document Server

    Hiremath, Kirankumar R; Schmidt, Frank

    2012-01-01

    Nonlocal material response distinctively changes the optical properties of nano-plasmonic scatterers and waveguides. It is described by the nonlocal hydrodynamic Drude model, which -- in frequency domain -- is given by a coupled system of equations for the electric field and an additional polarization current of the electron gas modeled analogous to a hydrodynamic flow. Recent works encountered difficulties in dealing with the grad-div operator appearing in the governing equation of the hydrodynamic current. Therefore, in these studies the model has been simplified with the curl-free hydrodynamic current approximation; but this causes spurious resonances. In this paper we present a rigorous weak formulation in the Sobolev spaces $H(\\mathrm{curl})$ for the electric field and $H(\\mathrm{div})$ for the hydrodynamic current, which directly leads to a consistent discretization based on N\\'ed\\'elec's finite element spaces. Comparisons with the Mie theory results agree well. We also demonstrate the capability of the...

  12. Nonlocal quantum fluctuations and fermionic superfluidity in the imbalanced attractive Hubbard model.

    Science.gov (United States)

    Heikkinen, M O J; Kim, D-H; Troyer, M; Törmä, P

    2014-10-31

    We study fermionic superfluidity in strongly anisotropic optical lattices with attractive interactions utilizing the cluster dynamical mean-field theory method, and focusing in particular on the role of nonlocal quantum fluctuations. We show that nonlocal quantum fluctuations impact the BCS superfluid transition dramatically. Moreover, we show that exotic superfluid states with a delicate order parameter structure, such as the Fulde-Ferrell-Larkin-Ovchinnikov phase driven by spin population imbalance, can emerge even in the presence of such strong fluctuations.

  13. A Nonlocal Peridynamic Plasticity Model for the Dynamic Flow and Fracture of Concrete.

    Energy Technology Data Exchange (ETDEWEB)

    Vogler, Tracy; Lammi, Christopher James

    2014-10-01

    A nonlocal, ordinary peridynamic constitutive model is formulated to numerically simulate the pressure-dependent flow and fracture of heterogeneous, quasi-brittle ma- terials, such as concrete. Classical mechanics and traditional computational modeling methods do not accurately model the distributed fracture observed within this family of materials. The peridynamic horizon, or range of influence, provides a characteristic length to the continuum and limits localization of fracture. Scaling laws are derived to relate the parameters of peridynamic constitutive model to the parameters of the classical Drucker-Prager plasticity model. Thermodynamic analysis of associated and non-associated plastic flow is performed. An implicit integration algorithm is formu- lated to calculate the accumulated plastic bond extension and force state. The gov- erning equations are linearized and the simulation of the quasi-static compression of a cylinder is compared to the classical theory. A dissipation-based peridynamic bond failure criteria is implemented to model fracture and the splitting of a concrete cylinder is numerically simulated. Finally, calculation of the impact and spallation of a con- crete structure is performed to assess the suitability of the material and failure models for simulating concrete during dynamic loadings. The peridynamic model is found to accurately simulate the inelastic deformation and fracture behavior of concrete during compression, splitting, and dynamically induced spall. The work expands the types of materials that can be modeled using peridynamics. A multi-scale methodology for simulating concrete to be used in conjunction with the plasticity model is presented. The work was funded by LDRD 158806.

  14. Pseudo Nambu-Goldstone modes in neutron stars

    CERN Document Server

    Kojo, Toru

    2016-01-01

    If quarks and gluons are either gapped or confined in neutron stars (NSs), the most relevant light modes are Nambu-Goldstone (NG) modes. We study NG modes within a schematic quark model whose parameters at high density are constrained by the two-solar mass constraint. Our model has the color-flavor-locked phase at high density, with the effective couplings as strong as in hadron physics. We find that strong coupling effects make NG modes more massive than in weak coupling predictions, and would erase several phenomena caused by the stressed pairings in mismatched Fermi surfaces. For instance, we found that charged kaons, which are dominated by diquark and anti-diquark components, are not light enough to condense at strong coupling. Implications for gravitational wave signals for NS-NS mergers are also briefly discussed.

  15. Nonlocal diffusion and applications

    CERN Document Server

    Bucur, Claudia

    2016-01-01

    Working in the fractional Laplace framework, this book provides models and theorems related to nonlocal diffusion phenomena. In addition to a simple probabilistic interpretation, some applications to water waves, crystal dislocations, nonlocal phase transitions, nonlocal minimal surfaces and Schrödinger equations are given. Furthermore, an example of an s-harmonic function, its harmonic extension and some insight into a fractional version of a classical conjecture due to De Giorgi are presented. Although the aim is primarily to gather some introductory material concerning applications of the fractional Laplacian, some of the proofs and results are new. The work is entirely self-contained, and readers who wish to pursue related subjects of interest are invited to consult the rich bibliography for guidance.

  16. Effective-Range Expansion of Neutron-Deuteron Scattering Studied by a Quark-Model Nonlocal Gaussian Potential

    Science.gov (United States)

    Fukukawa, K.; Fujiwara, Y.

    2011-05-01

    The S-wave effective-range parameters of the neutron-deuteron (nd) scattering are calculated in the Faddeev formalism using a nonlocal Gaussian potential based on the quark-model baryon-baryon interaction fss2. The spin-doublet low-energy eigenphase shift is sufficiently attractive to reproduce predictions by the AV18 plus Urbana three-body force, yielding almost correct values of the scattering length and the triton binding energy without the three-nucleon force. This feature is due to the strong distortion effect of the deuteron in this spin channel, which is very sensitive to the nonlocal description of the short-range repulsion in the quark-model nucleon-nucleon interaction. We incorporate the Coulomb force by extending the framework of the Coulomb externally corrected approximation and calculate the differential cross sections of the pd scattering.

  17. Nonlocal and quasilocal field theories

    Science.gov (United States)

    Tomboulis, E. T.

    2015-12-01

    We investigate nonlocal field theories, a subject that has attracted some renewed interest in connection with nonlocal gravity models. We study, in particular, scalar theories of interacting delocalized fields, the delocalization being specified by nonlocal integral kernels. We distinguish between strictly nonlocal and quasilocal (compact support) kernels and impose conditions on them to insure UV finiteness and unitarity of amplitudes. We study the classical initial value problem for the partial integro-differential equations of motion in detail. We give rigorous proofs of the existence but accompanying loss of uniqueness of solutions due to the presence of future, as well as past, "delays," a manifestation of acausality. In the quantum theory we derive a generalization of the Bogoliubov causality condition equation for amplitudes, which explicitly exhibits the corrections due to nonlocality. One finds that, remarkably, for quasilocal kernels all acausal effects are confined within the compact support regions. We briefly discuss the extension to other types of fields and prospects of such theories.

  18. Cosmology with ultralight pseudo Nambu-Goldstone bosons

    Energy Technology Data Exchange (ETDEWEB)

    Frieman, J.A.; Hill, C.T.; Stebbins, A.; Waga, I. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)]|[Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637 (United States)]|[Theoretical Physics Department, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)]|[Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21943 (Brazil)

    1995-09-11

    We explore the cosmological implications of an ultralight pseudo Nambu-Goldstone boson. With global spontaneous symmetry breaking scale {ital f}{congruent}10{sup 18} GeV and explicit breaking scale comparable to Mikheyev-Smirnov-Wolfenstein neutrino masses, {ital M}{similar_to}10{sup {minus}3}eV, such a field, which acquires a mass {ital m}{sub {phi}}{similar_to}{ital M}{sup 2}/{ital f}{similar_to}{ital H}{sub 0}, would currently dominate the energy density of the Universe. The field acts as an effective cosmological constant before relaxing into a condensate of nonrelativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, {Omega}{sub {ital m}}{similar_to}0.2, with a spatially flat universe, yielding {ital H}{sub 0}{ital t}{sub 0}{congruent}1 consistent with limits from gravitational lens statistics.

  19. Pairing Nambu-Goldstone modes within nuclear density functional theory

    CERN Document Server

    Hinohara, Nobuo

    2016-01-01

    We show that the Nambu-Goldstone formalism of the broken gauge symmetry in the presence of the $T=1$ pairing condensate offers a quantitative description of the binding energy differences of open-shell superfluid nuclei. We conclude that the pairing rotational moments of inertia are excellent pairing indicators, which are free from ambiguities attributed to odd-mass systems. We offer a new, unified interpretation of the binding-energy differences traditionally viewed in the shell model picture as signatures of the valence nucleon properties. We present the first systematic analysis of the off-diagonal pairing rotational moments of inertia, and demonstrate the mixing of the neutron and proton pairing rotational modes in the ground states of even-even nuclei. Finally, we discuss the importance of mass measurements of neutron-rich nuclei for constraining the pairing energy density functional.

  20. Four Loop Scattering in the Nambu-Goto Theory

    CERN Document Server

    Conkey, Peter

    2016-01-01

    We initiate the study of multiloop scattering amplitudes in the Nambu-Goto theory on the worldsheet of a non-critical string. We start with a brute force calculation of two loop four particle scattering. Somewhat surprisingly, even though non-trivial UV counterterms are present at this order, on-shell amplitudes remain polynomial in the momenta of colliding particles. We show that this can be understood as a consequence of existence of certain close by (semi)integrable models. Furthermore, these arguments can be extended to obtain the answer for three and four loop scattering, bypassing the brute force calculation. The resulting amplitudes develop non-polynomial (logarithmic) dependence on the momenta starting at three loops.