Gomez Dumm, D., Izzo Villafañe, M. F., Noguera, S., Pagura, V. P., & Scoccola, N. N. (2017). Strong magnetic fields in nonlocal chiral quark models. Phys. Rev. D, 96(11), 114012–19pp.
Abstract: We study the behavior of strongly interacting matter under a uniform intense external magnetic field in the context of nonlocal extensions of the Polyakov-Nambu-Jona-Lasinio model. A detailed description of the formalism is presented, considering the cases of zero and finite temperature. In particular, we analyze the effect of the magnetic field on the chiral restoration and deconfinement transitions, which are found to occur at approximately the same critical temperatures. Our results show that these models offer a natural framework to account for the phenomenon of inverse magnetic catalysis found in lattice QCD calculations.
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Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2011). Pion radiative weak decays in nonlocal chiral quark models. Phys. Lett. B, 698(3), 236–242.
Abstract: We analyze the radiative pion decay pi(+) -> e(+) nu(e)gamma 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(+) nu(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 pi(0) -> gamma*gamma decays are discussed.
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Gomez Dumm, D., Noguera, S., Scoccola, N. N., & Scopetta, S. (2014). Pion distribution amplitude and the pion-photon transition form factor in a nonlocal chiral quark model. Phys. Rev. D, 89(5), 054031–14pp.
Abstract: We study the pion distribution amplitude (pi DA) in the context of a nonlocal chiral quark model. The corresponding Lagrangian reproduces the phenomenological values of the pion mass and decay constant, as well as the momentum dependence of the quark propagator obtained in lattice calculations. It is found that the obtained pi DA has two symmetric maxima, which arise from the new contributions generated by the nonlocal character of the interactions. This pi DA is applied to leading order and next-to-leading order calculations of the pion-photon transition form factor. Implications of the results are discussed.
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Gomez Dumm, D., Roig, P., Pich, A., & Portoles, J. (2010). tau -> pi pi pi nu(tau) decays and the a(1)(1260) off-shell width revisited. Phys. Lett. B, 685(2-3), 158–164.
Abstract: The tau -> pi pi pi nu(tau) decay is driven by the hadronization of the axial-vector current. Within the resonance chiral theory, and considering the large-N-C expansion, this process has been studied in Ref. [1] (D. Gomez Dumm, A. Pich, J. Portoles, 2004). In the light of later developments we revise here this previous work by including a new off-shell width for the lightest a(1) resonance that provides a good description of the tau -> pi pi pi nu(tau) spectrum and branching ratio. We also consider the role of the rho(1450) resonance in these observables. Thus we bring in an overall description of the tau -> pi pi pi nu(tau) process in excellent agreement with our present experimental knowledge.
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Coppola, M., Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2019). Pion-to-vacuum vector and axial vector amplitudes and weak decays of pions in a magnetic field. Phys. Rev. D, 99(5), 054031–18pp.
Abstract: We propose a model-independent parametrization for the one-pion-to-vacuum matrix elements of the vector and axial vector hadronic currents in the presence of an external uniform magnetic field. It is shown that, in general, these hadronic matrix elements can be written in terms of several gauge covariant Lorentz structures and form factors. Within this framework we obtain a general expression for the weak decay pi(- )-> l(nu)over bar(l) and discuss the corresponding limits of strong and weak external magnetic fields.
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