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Pagura, V. P., Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2017). Magnetic catalysis and inverse magnetic catalysis in nonlocal chiral quark models. Phys. Rev. D, 95(3), 034013–7pp.
Abstract: 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.
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Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2012). Form factors of radiative pion decays in nonlocal chiral quark models. Phys. Rev. D, 86(7), 074020–10pp.
Abstract: We study the radiative pion decay pi(+) -> e(+) nu(e)gamma within nonlocal chiral quark models that include wave function renormalization. In this framework we analyze the momentum dependence of the vector form factor F-V(q(2)) and the slope of the axial-vector form factor F-A(q(2)) at threshold. Our results are compared with available experimental information and with the predictions given by the Nambu-Jona-Lasinio model. In addition we calculate the low energy constants l(5) and l(6), comparing our results with the values obtained in chiral perturbation theory.
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Noguera, S., & Scopetta, S. (2012). Eta-photon transition form factor. Phys. Rev. D, 85(5), 054004–12pp.
Abstract: The eta-photon transition form factor is evaluated in a formalism based on a phenomenological description at low values of the photon virtuality, and a QCD-based description at high photon virtualities, matching at a scale Q(0)(2). The high photon virtuality description makes use of a distribution amplitude calculated in the Nambu-Jona-Lasinio model with Pauli-Villars regularization at the matching scale Q(0)(2), and QCD evolution from Q(0)(2) to higher values of Q(2). A good description of the available data is obtained. The analysis indicates that the recent data from the BABAR collaboration on pion and eta transition form factor can be well reproduced, if a small contribution of higher twist is added to the dominant twist-two contribution at the matching scale Q(0)(2).
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Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2017). eta-gamma and eta(')-gamma transition form factors in a nonlocal NJL model. Phys. Rev. D, 95(5), 054006–19pp.
Abstract: We study the eta and eta(') distribution amplitudes (DAs) in the context of a nonlocal SU(3)(L) circle times SUd(3)(R) chiral quark model. The corresponding Lagrangian allows us 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.
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Courtoy, A., Noguera, S., & Scopetta, S. (2019). Double parton distributions in the pion in the Nambu-Jona-Lasinio model. J. High Energy Phys., 12(12), 045–26pp.
Abstract: Two-parton correlations in the pion, a non perturbative information encoded in double parton distribution functions, are investigated in the Nambu-Jona-Lasinio model. It is found that double parton distribution functions expose novel dynamical information on the structure of the pion, not accessible through one-body parton distributions, as it happens in several estimates for the proton target and in a previous evaluation for the pion, in a light-cone framework. Expressions and predictions are given for double parton distributions corresponding to leading-twist Dirac operators in the quark vertices, and to different regularization methods for the Nambu-Jona-Lasinio model. These results are particularly relevant in view of forthcoming lattice data.
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