Measuring the Inflaton Coupling in the CMBDrewes, Marco
doi: 10.48550/arXiv.1903.09599pmid: N/A
Abstract: We study the perspectives to extract information about the microphysical parameters that govern the reheating process after cosmic inflation from CMB data. We identify conditions under which the inflaton coupling to other fields can be constrained for a given model of inflation without having to specify the details of the particle physics theory within which this model is realised. This is possible when the effective potential during reheating is approximately parabolic, and when the coupling constants are smaller than an upper bound that is determined by the ratios between the inflaton mass and the Planck mass or the scale of inflation. We consider scalar, Yukawa, and axion-like interactions and estimate that these conditions can be fulfilled if the inflaton coupling is comparable to the electron Yukawa coupling or smaller, and if the inflaton mass is larger than $10^5$ GeV. Pinning down the order of magnitude of the coupling constant requires measuring the scalar-to-tensor ratio at the level of $10^{-3}$, which is possible with future CMB observatories. This would provide an important clue to understand how a given model of inflation may be embedded into a more fundamental theory of nature.
Measuring the Inflaton Coupling in the CMBDrewes, Marco
doi: 10.1088/1475-7516/2022/09/069pmid: N/A
Abstract: We study the perspectives to extract information about the microphysical parameters that governed the reheating process after cosmic inflation from CMB data. We identify conditions under which the inflaton coupling to other fields can be constrained for a given model of inflation without having to specify the details of the particle physics theory within which this model is realised. This is possible when the effective potential during reheating is approximately parabolic, and when the coupling constants are smaller than an upper bound that is determined by the ratios between the inflaton mass and the Planck mass or the scale of inflation. We consider scalar, Yukawa, and axion-like interactions and estimate that these conditions can be fulfilled if the inflaton coupling is comparable to the electron Yukawa coupling or smaller, and if the inflaton mass is larger than $10^5$ GeV. Constraining the order of magnitude of the coupling constant requires measuring the scalar-to-tensor ratio at the level of $10^{-3}$, which is possible with future CMB observatories. Such a measurement would provide an important clue to understand how a given model of inflation may be embedded into a more fundamental theory of nature.
Flavour-alignment in an $S_3$-symmetric Higgs sector and its RG-behaviourChakrabarty, Nabarun;Chakraborty, Indrani
doi: 10.48550/arXiv.1903.09388pmid: N/A
Abstract: A three Higgs-doublet model admitting an $S_3$-symmetry can predict the observed pattern of the quark masses and their mixings. However the same symmetry also introduces potential flavour-changing neutral currents at the tree level. We assume in this work that the scalar potential contains appropriate \emph{soft} $S_3$-breaking terms in order to keep the choices of the scalar masses flexible. We identify the parameters in the Yukawa Lagrangian in the quark sector responsible for such FCNCs and constrain them using data from some of the flavour physics observables like meson-decays and meson-mixings. We also validate the corresponding model parameter space with renormalisation group (RG) evaluation.
Resolving phase transitions with Discontinuous Galerkin methodsGrossi, Eduardo;Wink, Nicolas
doi: 10.48550/arXiv.1903.09503pmid: N/A
Abstract: We demonstrate the applicability and advantages of Discontinuous Galerkin (DG) schemes in the context of the Functional Renormalization Group (FRG). We investigate the $O(N)$-model in the large $N$ limit. It is shown that the flow equation for the effective potential can be cast into a conservative form. We discuss results for the Riemann problem, as well as initial conditions leading to a first and second order phase transition. In particular, we unravel the mechanism underlying first order phase transitions, based on the formation of a shock in the derivative of the effective potential.
Revisiting Quantum Stabilization of the Radion in Randall-Sundrum ModelHaba, Naoyuki;Yamada, Toshifumi
doi: N/Apmid: N/A
Abstract: We study the stabilization of the radion in Randall-Sundrum-1 model by the Casimir energy of a bulk gauge field. The Casimir energy is proportional to a divergent, infinite summation over the zeros of a Wronskian of Bessel functions that implicitly depends on the radion vacuum expectation value, and its regularization and renormalization is the central issue. We carry out the correct regularization and renormalization by noting that analytic continuation must be performed only on functions that are independent of the radion vacuum expectation value. Thereby we find that the 1-loop effective potential of the radion generated by the Casimir energy can be renormalized with the boundary tensions, and we correctly obtain the renormalized effective potential. It is shown that a bulk gauge field satisfying Dirichlet condition at the positive (UV) boundary and Dirichlet condition at the negative (IR) boundary gives rise to an appropriate radion potential that stabilizes the radion vacuum expectation value in a way that a large hierarchy of the warp factor is generated naturally.