Reheating mechanism of Curvaton with Nonminimal Derivative Coupling to Gravity

In this paper, we continue our study on the curvaton model with nonminimal derivative coupling (NDC) to Einstein gravity proposed in our previous work, focusing on the reheating mechanism. We found that according to whether the curvaton has dominated the background after the end of inflation, it will have two different behaviors of evolution, which should be the general property of curvaton with nonminimal couplings. This will cause diffferent rates of particle creation, which goes on via the parametric resonance process. The reheating temperature is estimated for both cases in which reheating completes before and after curvaton domination, and the constraints are quite loose compared to that of overproduction of gravitino. Finally we investigated the evolution of curvature perturbation during reheating. We have shown both analytically and numerically that the curvature perturbation will not blow up during the resonance process.Comment: 10 pages, 8 figures. corrections are made to match the published versio

IR Divergence in Inflationary Tensor Perturbations from Fermion Loops

We estimate fermion loop corrections to the two-point correlation function of primordial tensor perturbations in a slow-roll inflationary background. We particularly compute an explicit term of one-loop correction from a massless fermion, and then extend to the complete Interaction Hamiltonian. After that, we study one-loop corrections contributed by a massive fermion to primordial tensor fluctuations. The loop correction arisen from a massless fermion field contains logarithms and thus may constrain the validity of perturbation theory in inflationary cosmology, but the situation could be relaxed once the fermion's mass is taken into account. Another one-loop diagram for a massive fermion which involves one vertex is constrained by a UV cutoff as expected by quantum field theory. Our result shows that loop corrections of a fermion field have the same sign as those of a scalar field, and thus implies that the inclusion of fermion loop corrections may not help to alleviate the issue of IR divergence in inflationary cosmology.Comment: 12 page

SF method for removing small skin melanocytic nevus

BackgroundThe most prevalent benign skin tumor is a melanocytic nevus, which can potentially turn cancerous and frequently impair a patient's appearance.ObjectiveTo find a standardized surgical procedure for the removal of tiny skin pigmented nevis and to look into the effectiveness of the SF technique for doing so.MethodsA retrospective study was conducted on 723 patients with small-sized pigmented nevi between June 2022 and June 2023. The nevi were removed using the SF method, and the patients' overall health and the duration of the procedure were recorded. Three months following the procedure, the patients completed a questionnaire to assess the effectiveness, recurrence, complications, and degree of satisfaction with the surgical outcome.ResultsCompared with the normal method, SF method had shorter operation time, higher effective rate, no recurrence and other postoperative complications after 6 months, less scar hyperplasia, and good evaluation satisfaction of all patients. No patient was rated as average or poor. No recurrence.ConclusionThe standardized surgical approaches for the small-size excision of melanocytic nevuses may be easily mastered by primary practitioners using the SF method, making it a valuable tool for practical use