The everpresent eta-problem: knowledge of all hidden sectors required

We argue that the eta-problem in supergravity inflation cannot be solved without knowledge of the ground state of hidden sectors that are gravitationally coupled to the inflaton. If the hidden sector breaks supersymmetry independently, its fields cannot be stabilized during cosmological evolution of the inflaton. We show that both the subsequent dynamical mixing between sectors as well as the lightest mass of the hidden sector are set by the scale of supersymmetry breaking in the hidden sector. The true cosmological eta-parameter arises from a linear combination of the lightest mode of the hidden sector with the inflaton. Generically, either the true eta deviates considerably from the na\"ive eta implied by the inflaton sector alone, or one has to consider a multifield model. Only if the lightest mass in the hidden sector is much larger than the inflaton mass and if the inflaton mass is much larger than the scale of hidden sector supersymmetry breaking, is the effect of the hidden sector on the slow-roll dynamics of the inflaton negligible.Comment: 27 pages, 6 figures; v2, published version, minor adjustments to the introduction, minor corrections to section 2.2 for improved clarity, references adde

Computing the temperature dependence of effective CP violation in the standard model

Brauner T, Taanila O, Tranberg A, Vuorinen A. Computing the temperature dependence of effective CP violation in the standard model. JHEP. 2012;2012(11): 76.CP violation in the standard model originates from theCabibbo-Kobayashi-Maskawa mixing matrix. Upon integrating all fermions out ofthe theory, its effects are captured by a series of effective nonrenormalizableoperators for the bosonic gauge and Higgs fields. We compute the CP-violatingpart of the effective action to the leading nontrivial, sixth order in thecovariant gradient expansion as a function of temperature. In the limit of zerotemperature, our result addresses the discrepancy between two independentcalculations existing in the literature [1,2]. We find that CP violation in thestandard model is strongly suppressed at high temperature, but that at T<1GeVit may be relevant for certain scenarios of baryogenesis. We also identify aselected class of operators at the next, eighth order and discuss theconvergence of the covariant gradient expansion