Browsing by Author "Loewe, M."

Now showing 1 - 6 of 6
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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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    Finite Temperature QCD Sum Rules: A Review
    (2017) Ayala, Alejandro; Dominguez, C. A.; Loewe, M.
    The method of QCD sum rules at finite temperature is reviewed, with emphasis on recent results. These include predictions forthe survival of charmonium and bottonium states, at and beyond the critical temperature for deconfinement, as later confirmed by lattice QCD simulations. Also included are determinations in the light-quark vector and axial-vector channels, allowing analysing the Weinberg sum rules and predicting the dimuon spectrum in heavy-ion collisions in the region of the rho-meson. Also, in this sector, the determination of the temperature behaviour of the up-down quark mass, together with the pion decay constant, will be described. Finally, an extension of the QCD sum rule method to incorporate finite baryon chemical potential is reviewed.
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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 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.