Browsing by Author "Zamora, R."

Now showing 1 - 9 of 9
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    Anisotropic photon emission from gluon fusion and splitting in a strong magnetic background: The two-gluon one-photon vertex
    (2022) Ayala, Alejandro; Castano-Yepes, Jorge David; Hernandez, L. A.; Mizher, Ana Julia; Tejeda-Yeomans, Maria Elena; Zamora, R.
    Having in mind the pre-equilibrium stage in peripheral heavy-ion collisions as a possible scenario for the production of electromagnetic radiation, we compute the two-gluon one-photon vertex in the presence of an intense magnetic field at one-loop order. The quarks in the loop are taken such that two of them occupy the lowest Landau level, with the third one occupying the first excited Landau level. When the field strength is the largest of the energy (squared) scales, the tensor basis describing this vertex corresponds to two of the three-vector particles polarized in the longitudinal direction whereas the third one is polarized in the transverse direction. However, when the photon energy is of the same order as or larger than the field strength, the explicit one-loop computation contains extra tensor structures that spoil the properties of the basis compared with the case when the field strength is the largest of the energy scales, which signals that the calculation is incomplete. Nevertheless, by projecting the result onto the would-be basis, we show that the squared amplitude for processes involving two gluons and one photon exhibits the expected properties such as a preferred in-plane photon emission and a slightly decreasing strength for an increasing magnetic-field strength. We comment on possible venues to improve the one-loop calculation that include accounting for progressive occupation of the three quarks of the lowest and first-excited Landau levels such that, still working in the large field limit, a more complete description can be achieved when the photon energy increases.
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    Catalysis and inverse electric catalysis in a scalar theory
    (2022) Loewe, M.; Valenzuela, D.; Zamora, R.
    In this article we explore the phase diagram associated to the symmetry breaking of a scalar self-interacting theory, induced by temperature and the presence of an external electric field. For such purpose, first we obtain the boson propagator, in the presence of a constant external electric field, both in the weak and strong field strength limits. Novel expansions are derived for the effective potential, valid for the whole range of temperature. We found inverse electric catalysis for the weak field region, i.e., a situation where the critical temperature diminishes as function of the strength of the electric field whereas for a strong field electric catalysis emerges. These behaviors, in the weak and strong intensity sectors, are valid for all possible values of temperature.
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    Electric corrections to it-it scattering lengths in the linear sigma model
    (2024) Cadiz, R.; Loewe, M.; Zamora, R.
    In this article, we analyze the role of an external electric field, in the weak field approximation, on pi - pi scattering lengths. The discussion is presented in the frame of the linear sigma model. To achieve this, we take into account all one -loop corrections in the s , t , and u channels associated with the insertion of a Schwinger propagator for charged pions, focusing on the region characterized by small values of the electric field. Furthermore, one of the novelties of our work is the explicit calculation of box diagrams, which were previously overlooked in discussions regarding magnetic corrections. It turns out that the electric field corrections have an opposite effect with respect to magnetic corrections calculated previously in the literature.
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    Magnetic renormalons in a scalar self-interacting λφ4 theory
    (2019) Correa, M.; Loewe, M.; Valenzuela, D.; Zamora, R.
    We present an analysis of the influence of an external magnetic field on renormalons in a self-interacting theory lambda phi(4). For weak magnetic field region, using an appropriate expansion for the Schwinger propagators, we find renormalons as poles on the real axis of the Borel plane, of which the position do not depend on the magnetic field, but where the residues acquire in fact a magnetic dependence. In the strong magnetic limit, working in the lowest Landau level approximation, these new poles are no longer present. We compare the magnetic scenario with previous results in the literature concerning thermal effects on renormalons in this theory.
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    Renormalons in a scalar self-interacting theory: Thermal, thermomagnetic, and thermoelectric corrections for all values of the temperature
    (2022) Loewe, M.; Zamora, R.
    In this article we revisit the discussion of renormalons in the frame of a scalar self-interacting lambda phi(4) theory in the presence of thermomagnetic effects, i.e., magnetic and thermal effects. Our results for the evolution of the residues is now given by an explicit analytic expression, valid for all values of temperature, without the necessity of separating the discussion in a low- and a high temperature region analyses. We carry out the same discussion for the case of an external constant electric field, obtaining also in this case an analytic expression for the whole range o temperature. In both cases, the location of the poles in the Borel plane does not change with respect to the vacuum case. Their residues, however, acquire a dependence on temperature and the external field. Results are presented for the evolution of residues in the thermomagnetic and thermoelectric cases. We show a comparison with our previous results in the thermomagnetic case, presenting also in detail the mathematical techniques needed for our analytic expressions to be valid in the whole range of temperatures.
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    Thermomagnetic evolution of the QCD strong coupling
    (2018) Ayala, Alejandro; Dominguez, C. A.; Hernandez-Ortiz, Saul; Hernandez, L. A.; Loewe Lobo, Marcelo Patricio; Manreza Paret, D.; Zamora, R.
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    Thermomagnetic renormalons in a scalar self-interacting λφ4 theory
    (2021) Loewe, M.; Monje, L.; Zamora, R.
    In this article we extend a previous discussion about the influence of an external magnetic field on renormalons in a self-interacting scalar theory by including now temperature effects, in the imaginary formalism, together with an external weak external magnetic field. We show that the position of renormalons, which are poles in the Borel plane, does not change, getting their residues, however, a dependence on temperature and on the magnetic field. The effects of temperature and the magnetic field strength on the residues turn out to be opposite. We present a detailed discussion about the evolution of these residues, showing technical details involved in the calculation.
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    Weak magnetic field effects on chiral critical temperature in a nonlocal Nambu–Jona-Lasinio model
    (2015) Loewe Lobo, Marcelo Patricio; Márquez, F.; Villavicencio Reyes, Cristián Luis; Zamora, R.
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    π-π scattering lengths : thermo-magnetic corrections in the linear sigma model
    (2020) Loewe Lobo, Marcelo Patricio; Muñoz Tavera, Enrique; Zamora, R.