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N N Scoccola - One of the best experts on this subject based on the ideXlab platform.
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neutral meson properties under an external magnetic field in nonlocal chiral Quark Models
Physical Review D, 2018Co-Authors: N N Scoccola, Gomez D Dumm, M Izzo F VillafaneAbstract:Fil: Gomez Dumm, Daniel Alberto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto de Fisica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Fisica La Plata; Argentina
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magnetic catalysis and inverse magnetic catalysis in nonlocal chiral Quark Models
Physical Review D, 2017Co-Authors: V P Pagura, S Noguera, Gomez D Dumm, N N ScoccolaAbstract:Fil: Pagura, Valeria Paula. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Consejo Superior de Investigaciones Cientificas; Espana
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deconfinement and chiral restoration in nonlocal su 3 chiral Quark Models
Physical Review D, 2013Co-Authors: N N Scoccola, Gomez D Dumm, J P CarlomagnoAbstract:We study the features of nonlocal SU(3) chiral Quark Models with wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. In this context we analyze the characteristics of the deconfinement and chiral restoration transitions at finite temperature, introducing the couplings of fermions to the Polyakov loop. We analyze the results obtained for various thermodynamical quantities considering different Polyakov loop potentials and nonlocal form factors, in comparison with data obtained from lattice QCD calculations.
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pion radiative weak decays in nonlocal chiral Quark Models
Physics Letters B, 2011Co-Authors: N N Scoccola, Gomez D Dumm, Santiago NogueraAbstract:Abstract We analyze the radiative pion decay π + → e + ν e γ within nonlocal chiral Quark Models that include wave function renormalization. In this framework we calculate the vector and axial-vector form factors F V and F A at q 2 = 0 — where q 2 is the e + ν e squared invariant mass — and the slope a of F V ( q 2 ) at q 2 → 0 . The calculations are carried out considering different nonlocal form factors, in particular those taken from lattice QCD evaluations, showing a reasonable agreement with the corresponding experimental data. The comparison of our results with those obtained in the (local) NJL model and the relation of F V and a with the form factor in π 0 → γ ⁎ γ decays are discussed.
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nonlocal chiral Quark Models with wavefunction renormalization sigma properties and pi pi scattering parameters
Physical Review D, 2008Co-Authors: S Noguera, N N ScoccolaAbstract:We analyze the sigma meson mass and width together with the pion-pion scattering parameters in the context of nonlocal chiral Quark Models with wave function renormalization (WFR). We consider both nonlocal interactions based on the frequently used exponential form factor, and on fits to the Quark mass and renormalization functions obtained in lattice calculations. In the case of the sigma properties, we obtain results which are less dependent on the parametrization than in the standard local Nambu-Jona-Lasinio model, and which are in reasonable agreement with the recently reported empirical values. We also show that the inclusion of the WFR tend to improve the description of the $\ensuremath{\pi}\mathrm{\text{\ensuremath{-}}}\ensuremath{\pi}$ scattering parameters, with the lattice inspired parametrization providing the best overall results. Finally, we analyze the connection of the nonlocal Quark Models discussed here with chiral perturbation theory, and present the model predictions for the low-energy constants relevant for $\ensuremath{\pi}\mathrm{\text{\ensuremath{-}}}\ensuremath{\pi}$ scattering to $O(4)$ in the chiral expansion.
Gomez D Dumm - One of the best experts on this subject based on the ideXlab platform.
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neutral meson properties under an external magnetic field in nonlocal chiral Quark Models
Physical Review D, 2018Co-Authors: N N Scoccola, Gomez D Dumm, M Izzo F VillafaneAbstract:Fil: Gomez Dumm, Daniel Alberto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto de Fisica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Fisica La Plata; Argentina
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magnetic catalysis and inverse magnetic catalysis in nonlocal chiral Quark Models
Physical Review D, 2017Co-Authors: V P Pagura, S Noguera, Gomez D Dumm, N N ScoccolaAbstract:Fil: Pagura, Valeria Paula. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Consejo Superior de Investigaciones Cientificas; Espana
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deconfinement and chiral restoration in nonlocal su 3 chiral Quark Models
Physical Review D, 2013Co-Authors: N N Scoccola, Gomez D Dumm, J P CarlomagnoAbstract:We study the features of nonlocal SU(3) chiral Quark Models with wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. In this context we analyze the characteristics of the deconfinement and chiral restoration transitions at finite temperature, introducing the couplings of fermions to the Polyakov loop. We analyze the results obtained for various thermodynamical quantities considering different Polyakov loop potentials and nonlocal form factors, in comparison with data obtained from lattice QCD calculations.
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pion radiative weak decays in nonlocal chiral Quark Models
Physics Letters B, 2011Co-Authors: N N Scoccola, Gomez D Dumm, Santiago NogueraAbstract:Abstract We analyze the radiative pion decay π + → e + ν e γ within nonlocal chiral Quark Models that include wave function renormalization. In this framework we calculate the vector and axial-vector form factors F V and F A at q 2 = 0 — where q 2 is the e + ν e squared invariant mass — and the slope a of F V ( q 2 ) at q 2 → 0 . The calculations are carried out considering different nonlocal form factors, in particular those taken from lattice QCD evaluations, showing a reasonable agreement with the corresponding experimental data. The comparison of our results with those obtained in the (local) NJL model and the relation of F V and a with the form factor in π 0 → γ ⁎ γ decays are discussed.
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covariant nonlocal chiral Quark Models with separable interactions
Physical Review D, 2006Co-Authors: Gomez D Dumm, A G Grunfeld, N N ScoccolaAbstract:We present a comparative analysis of chiral Quark Models which include nonlocal covariant four-fermion couplings. We consider two alternative ways of introducing the nonlocality, as well as various shapes for the momentum-dependent form factors governing the effective interactions. In all cases we study the behavior of model parameters and analyze numerical results for constituent Quark masses and Quark propagator poles. Advantages of these covariant nonlocal schemes over instantaneous nonlocal schemes and the standard NJL model are pointed out.
Wojciech Broniowski - One of the best experts on this subject based on the ideXlab platform.
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double parton distribution of valence Quarks in the pion in chiral Quark Models
Physical Review D, 2020Co-Authors: Wojciech Broniowski, Enrique Ruiz ArriolaAbstract:The valence double parton distribution of the pion is analyzed in the framework of chiral Quark Models, where in the chiral limit factorization between the longitudinal and transverse degrees of freedom occurs. This feature leads, at the Quark-model scale, to a particularly simple distribution of the form $D({x}_{1},{x}_{2},\mathbit{q})=\ensuremath{\delta}(1\ensuremath{-}{x}_{1}\ensuremath{-}{x}_{2})F(\mathbit{q})$, where ${x}_{1,2}$ are the longitudinal momentum fractions carried by the valence Quark and antiQuark and $\mathbit{q}$ is their relative transverse momentum. For $\mathbit{q}=\mathbf{0}$ this result complies immediately with the Gaunt-Sterling sum rules. The Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution to higher scales is carried out in terms of the Mellin moments. We then explore its role on the longitudinal correlation quantified with the ratio of the double distribution to the product of single distributions, $D({x}_{1},{x}_{2},\mathbit{q}=\mathbf{0})/D({x}_{1})D({x}_{2})$. We point out that the ratios of moments $⟨{x}_{1}^{n}{x}_{2}^{m}⟩/⟨{x}_{1}^{n}⟩⟨{x}_{2}^{m}⟩$ are independent of the evolution, providing particularly suitable measures to be tested in the upcoming lattice simulations. The transverse form factor $F(\mathbit{q})$ and its Fourier conjugate in the relative transverse coordinate $\mathbit{b}$ are obtained in variants of the Nambu--Jona-Lasinio model with the spectral and Pauli-Villars regularizations. The results are valid in the soft-momentum domain. Interestingly, with the spectral regularization of the model, the effective cross section for the double parton scattering of pions is exactly equal to the geometric cross section, ${\ensuremath{\sigma}}_{\mathrm{eff}}=\ensuremath{\pi}⟨{\mathbit{b}}^{2}⟩$, and yields about 20 mb.
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nonperturbative partonic quasidistributions of the pion from chiral Quark Models
Physics Letters B, 2017Co-Authors: Wojciech Broniowski, Enrique Ruiz ArriolaAbstract:Abstract We evaluate nonperturbatively the Quark quasidistribution amplitude and the valence Quark quasidistribution function of the pion in the framework of chiral Quark Models, namely the Nambu–Jona-Lasinio model and the Spectral Quark Model. We arrive at simple analytic expressions, where the nonperturbative dependence on the longitudinal momentum of the pion can be explicitly assessed. The model results for the Quark quasidistribution amplitude of the pion compare favorably to the data obtained from the Euclidean lattice simulations. The Quark distribution amplitude, arising in the limit of infinite longitudinal momentum of the pion, agrees, after suitable QCD evolution, to the recent data extracted from Euclidean lattices, as well as to the old data from transverse lattice simulations.
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transversity form factors of the pion in chiral Quark Models
Physical Review D, 2010Co-Authors: Wojciech Broniowski, A E Dorokhov, Enrique Ruiz ArriolaAbstract:The transversity form factors of the pion, involving matrix elements of bilocal tensor currents, are evaluated in chiral Quark Models, both in the local Nambu-Jona-Lasinio with the Pauli-Villars regularization, as well as in nonlocal Models involving momentum-dependent Quark mass. After suitable QCD evolution, the agreement with recent lattice calculations is very good, in accordance to the fact that the spontaneously broken chiral symmetry governs the dynamics of the pion. Meson dominance of form factors with expected meson masses also works properly, conforming to the parton-hadron duality in the considered process.
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gravitational and higher order form factors of the pion in chiral Quark Models
Physical Review D, 2008Co-Authors: Wojciech Broniowski, Enrique Ruiz ArriolaAbstract:The gravitational form factor of the pion is evaluated in two chiral Quark Models and confronted with the recent full-QCD lattice data. We find good agreement for the case of the spectral Quark model, which builds in the vector-meson dominance for the charge form factor. We derive a simple relation between the gravitational and electromagnetic form factors, holding in the considered Quark Models in the chiral limit. The relation implies that the gravitational mean squared radius is half the electromagnetic one. We also analyze higher-order Quark generalized form factors of the pion, related to higher moments in the symmetric Bjorken X variable of the generalized parton distribution functions, and discuss their perturbative QCD evolution, which is needed to relate the Quark-model predictions to the lattice data. The values of the higher-order Quark form factors at t=0, computed on the lattice, also agree with our Quark-model results within the statistical and method uncertainties.
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generalized parton distributions of the pion in chiral Quark Models and their qcd evolution
Physical Review D, 2008Co-Authors: Wojciech Broniowski, Enrique Ruiz Arriola, Krzysztof J GolecbiernatAbstract:We evaluate Generalized Parton Distributions of the pion in two chiral Quark Models: the Spectral Quark Model and the Nambu-Jona-Lasinio model with a Pauli-Villars regularization. We proceed by the evaluation of double distributions through the use of a manifestly covariant calculation based on the alpha representation of propagators. As a result polynomiality is incorporated automatically and calculations become simple. In addition, positivity and normalization constraints, sum rules and soft pion theorems are fulfilled. We obtain explicit formulas, holding at the low-energy Quark-model scale. The expressions exhibit no factorization in the t-dependence. The QCD evolution of those parton distributions is carried out to experimentally or lattice accessible scales. We argue for the need of evolution by comparing the Parton Distribution Function and the Parton Distribution Amplitude of the pion to the available experimental and lattice data, and confirm that the Quark-model scale is low, about 320 MeV.
Enrique Ruiz Arriola - One of the best experts on this subject based on the ideXlab platform.
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double parton distribution of valence Quarks in the pion in chiral Quark Models
Physical Review D, 2020Co-Authors: Wojciech Broniowski, Enrique Ruiz ArriolaAbstract:The valence double parton distribution of the pion is analyzed in the framework of chiral Quark Models, where in the chiral limit factorization between the longitudinal and transverse degrees of freedom occurs. This feature leads, at the Quark-model scale, to a particularly simple distribution of the form $D({x}_{1},{x}_{2},\mathbit{q})=\ensuremath{\delta}(1\ensuremath{-}{x}_{1}\ensuremath{-}{x}_{2})F(\mathbit{q})$, where ${x}_{1,2}$ are the longitudinal momentum fractions carried by the valence Quark and antiQuark and $\mathbit{q}$ is their relative transverse momentum. For $\mathbit{q}=\mathbf{0}$ this result complies immediately with the Gaunt-Sterling sum rules. The Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution to higher scales is carried out in terms of the Mellin moments. We then explore its role on the longitudinal correlation quantified with the ratio of the double distribution to the product of single distributions, $D({x}_{1},{x}_{2},\mathbit{q}=\mathbf{0})/D({x}_{1})D({x}_{2})$. We point out that the ratios of moments $⟨{x}_{1}^{n}{x}_{2}^{m}⟩/⟨{x}_{1}^{n}⟩⟨{x}_{2}^{m}⟩$ are independent of the evolution, providing particularly suitable measures to be tested in the upcoming lattice simulations. The transverse form factor $F(\mathbit{q})$ and its Fourier conjugate in the relative transverse coordinate $\mathbit{b}$ are obtained in variants of the Nambu--Jona-Lasinio model with the spectral and Pauli-Villars regularizations. The results are valid in the soft-momentum domain. Interestingly, with the spectral regularization of the model, the effective cross section for the double parton scattering of pions is exactly equal to the geometric cross section, ${\ensuremath{\sigma}}_{\mathrm{eff}}=\ensuremath{\pi}⟨{\mathbit{b}}^{2}⟩$, and yields about 20 mb.
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nonperturbative partonic quasidistributions of the pion from chiral Quark Models
Physics Letters B, 2017Co-Authors: Wojciech Broniowski, Enrique Ruiz ArriolaAbstract:Abstract We evaluate nonperturbatively the Quark quasidistribution amplitude and the valence Quark quasidistribution function of the pion in the framework of chiral Quark Models, namely the Nambu–Jona-Lasinio model and the Spectral Quark Model. We arrive at simple analytic expressions, where the nonperturbative dependence on the longitudinal momentum of the pion can be explicitly assessed. The model results for the Quark quasidistribution amplitude of the pion compare favorably to the data obtained from the Euclidean lattice simulations. The Quark distribution amplitude, arising in the limit of infinite longitudinal momentum of the pion, agrees, after suitable QCD evolution, to the recent data extracted from Euclidean lattices, as well as to the old data from transverse lattice simulations.
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transversity form factors of the pion in chiral Quark Models
Physical Review D, 2010Co-Authors: Wojciech Broniowski, A E Dorokhov, Enrique Ruiz ArriolaAbstract:The transversity form factors of the pion, involving matrix elements of bilocal tensor currents, are evaluated in chiral Quark Models, both in the local Nambu-Jona-Lasinio with the Pauli-Villars regularization, as well as in nonlocal Models involving momentum-dependent Quark mass. After suitable QCD evolution, the agreement with recent lattice calculations is very good, in accordance to the fact that the spontaneously broken chiral symmetry governs the dynamics of the pion. Meson dominance of form factors with expected meson masses also works properly, conforming to the parton-hadron duality in the considered process.
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gravitational and higher order form factors of the pion in chiral Quark Models
Physical Review D, 2008Co-Authors: Wojciech Broniowski, Enrique Ruiz ArriolaAbstract:The gravitational form factor of the pion is evaluated in two chiral Quark Models and confronted with the recent full-QCD lattice data. We find good agreement for the case of the spectral Quark model, which builds in the vector-meson dominance for the charge form factor. We derive a simple relation between the gravitational and electromagnetic form factors, holding in the considered Quark Models in the chiral limit. The relation implies that the gravitational mean squared radius is half the electromagnetic one. We also analyze higher-order Quark generalized form factors of the pion, related to higher moments in the symmetric Bjorken X variable of the generalized parton distribution functions, and discuss their perturbative QCD evolution, which is needed to relate the Quark-model predictions to the lattice data. The values of the higher-order Quark form factors at t=0, computed on the lattice, also agree with our Quark-model results within the statistical and method uncertainties.
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generalized parton distributions of the pion in chiral Quark Models and their qcd evolution
Physical Review D, 2008Co-Authors: Wojciech Broniowski, Enrique Ruiz Arriola, Krzysztof J GolecbiernatAbstract:We evaluate Generalized Parton Distributions of the pion in two chiral Quark Models: the Spectral Quark Model and the Nambu-Jona-Lasinio model with a Pauli-Villars regularization. We proceed by the evaluation of double distributions through the use of a manifestly covariant calculation based on the alpha representation of propagators. As a result polynomiality is incorporated automatically and calculations become simple. In addition, positivity and normalization constraints, sum rules and soft pion theorems are fulfilled. We obtain explicit formulas, holding at the low-energy Quark-model scale. The expressions exhibit no factorization in the t-dependence. The QCD evolution of those parton distributions is carried out to experimentally or lattice accessible scales. We argue for the need of evolution by comparing the Parton Distribution Function and the Parton Distribution Amplitude of the pion to the available experimental and lattice data, and confirm that the Quark-model scale is low, about 320 MeV.
H R Petry - One of the best experts on this subject based on the ideXlab platform.
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the light baryon spectrum in a relativistic Quark model with instanton induced Quark forces the strange baryon spectrum
European Physical Journal A, 2001Co-Authors: U Loring, Ch B Metsch, H R PetryAbstract:This is the third of a series of papers treating light baryon resonances up to 3 GeV within a relativistically covariant Quark model based on the Bethe-Salpeter equation with instantaneous two- and three-body forces. In this last paper we extend our previous work on non-strange baryons to a prediction of the complete strange baryon spectrum and a detailed comparison with experiment. We apply our covariant Salpeter framework to specific Quark Models as introduced in the two preceding papers. Quark confinement is realized by linearly rising three-body string potentials with appropriate Dirac structures; to describe the hyperfine structure of the baryon spectrum we adopt 't Hooft's two-Quark residual interaction based on QCD instanton effects. The investigation of instanton-induced effects in the baryon mass spectrum plays a central role in this work. We demonstrate that several prominent features of the excited strange mass spectrum, e.g. the low positions of the strange partners of the Roper resonance or the appearance of approximate ''parity doublets'' in the Lambda-spectrum, find a natural, uniform explanation in our relativistic Quark model with instanton-induced forces.
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the light baryon spectrum in a relativistic Quark model with instanton induced Quark forces
European Physical Journal A, 2001Co-Authors: U Loring, Ch B Metsch, H R PetryAbstract:This is the third of a series of papers treating light-baryon resonances up to 3 GeV within a relativistically covariant Quark model based on the Bethe-Salpeter equation with instantaneous two- and three-body forces. In this last paper we extend our previous work (U. Loring, B.Ch. Metsch, H.R. Petry, this issue, p. 395) on non-strange baryons to a prediction of the complete strange-baryon spectrum and a detailed comparison with experiment. We apply the covariant Salpeter framework, which we developed in the first paper (U. Loring, K. Kretzschmar, B.Ch. Metsch, H.R. Petry, Eur. Phys. J. A 10, 309 (2001)), to the specific Quark Models introduced in our work published in this issue. Quark confinement is realized by linearly rising three-body string potentials with appropriate Dirac structures; to describe the hyperfine structure of the baryon spectrum we adopt 't Hooft's two-Quark residual interaction based on QCD instanton effects. The investigation of instanton-induced effects in the baryon mass spectrum plays a central role in this work. We demonstrate that several prominent features of the excited strange mass spectrum, e.g. the low positions of the strange partners of the Roper resonance or the appearance of approximate “parity doublets” in the Λ spectrum, find a natural, uniform explanation in our relativistic Quark model with instanton-induced forces.
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relativistic Quark Models of baryons with instantaneous forces
European Physical Journal A, 2001Co-Authors: U Loring, Ch B Metsch, Klaus Kretzschmar, H R PetryAbstract:This is the first of a series of three papers treating light baryon resonances (up to 3 GeV) within a relativistically covariant Quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In this paper we give a unified description of the theoretical background and demonstrate how to solve the Bethe-Salpeter equation by a reduction to the Salpeter equation. The specific new features of our covariant Salpeter model with respect to the usual nonrelativistic Quark model are discussed in detail. The purely theoretical results obtained in this paper will be applied numerically to explicit Quark Models for light baryons in two subsequent papers.