Preheating in Palatini Higgs inflation on the lattice

We study preheating following Higgs inflation in the Palatini formulation of gravity. We numerically evolve perturbations of the radial mode of the Higgs field and that of three scalars modeling the gauge bosons. We compare the two non-perturbative mechanisms of growth of excitations -- parametric resonance and tachyonic instability -- and confirm that the latter plays the dominant role. Our results provide further evidence that preheating in Palatini Higgs inflation happens within a single oscillation of the Higgs field about the bottom of its potential, consistent with the approximation of an instantaneous preheating.Comment: 20 pages, 9 figures. V2: corrected an error in the Einstein frame potential of the gauge bosons (eq. 2.18), and added references. V3: appendix added, matches the published versio

Testing the low scale seesaw and leptogenesis

Abstract Heavy neutrinos with masses below the electroweak scale can simultaneously generate the light neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis. The requirement to explain these phenomena imposes constraints on the mass spectrum of the heavy neutrinos, their flavour mixing pattern and their CP properties. We first combine bounds from different experiments in the past to map the viable parameter regions in which the minimal low scale seesaw model can explain the observed neutrino oscillations, while being consistent with the negative results of past searches for physics beyond the Standard Model. We then study which additional predictions for the properties of the heavy neutrinos can be made based on the requirement to explain the observed baryon asymmetry of the universe. Finally, we comment on the perspectives to find traces of heavy neutrinos in future experimental searches at the LHC, NA62, BELLE II, T2K, SHiP or a future high energy collider, such as ILC, CEPC or FCC-ee. If any heavy neutral leptons are discovered in the future, our results can be used to assess whether these particles are indeed the common origin of the light neutrino masses and the baryon asymmetry of the universe. If the magnitude of their couplings to all Standard Model flavours can be measured individually, and if the Dirac phase in the lepton mixing matrix is determined in neutrino oscillation experiments, then all model parameters can in principle be determined from this data. This makes the low scale seesaw a fully testable model of neutrino masses and baryogenesis

Leptogenesis from oscillations of heavy neutrinos with large mixing angles

via the seesaw mechanism and the baryon asymmetry of the Universe via leptogenesis. If the mass of the heavy neutrinos is below the electroweak scale, they may be found at the LHC, BELLE II, NA62, the proposed SHiP experiment or a future high-energy collider. In this mass range, the baryon asymmetry is generated via CP -violating oscillations of the heavy neutrinos during their production. We study the generation of the baryon asymmetry of the Universe in this scenario from first principles of non-equilibrium quantum field theory, including spectator processes and feedback effects. We eliminate several uncertainties from previous calcula-tions and find that the baryon asymmetry of the Universe can be explained with larger heavy neutrino mixing angles, increasing the chance for an experimental discovery. For the limiting cases of fast and strongly overdamped oscillations of right-handed neutrinos, the generation of the baryon asymmetry can be calculated analytically up to corrections of order one

PHENOTYPIC GRAIN YIELD STABILITY OF SEVERAL SOYBEAN OSCULTIVARS

Objective of this study was to evaluate the level and stability of grain yield as well as adaptability level of several domestic soybean cultivars. The trials were conducted on three locations in the region of the eastern Croatia (Osijek, Brijest, Donji Miholjac) in the period from 1998-2002 and involved 14 soybean cultivars. Tested cultivars were created in soybean breeding programme at the Agricultural Institute Osijek. They belong to maturity groups 0, 0-I and I according to vegetation period length. Two parameters are used in the analysis of yield stability and cultivar adaptability: portion of variance of genotype x environment interaction of each genotype to total variance of genotype x environment interaction (S2 GxE) and regression coefficient (bi). Obtained results indicated significant differences in level and stability of grain yield as well as level of cultivar adaptability. Six of the 14 tested cultivars: Ika, Podravka 95, Smiljana, Kuna, Anica and Tisa had high and stable grain yield and wide-general adaptability. Other tested cultivars had unstable grain yield and narrow (specific) adaptability

Leptogenesis with GeV-Scale Right-Handed Neutrinos

We review the relation between leptogenesis and the discrete symmetry of charge-parity conjugation. The requirement of respecting the theorem of combined charge-parity-time reversal invariance at the level of the kinetic equations describing leptogenesis in the early Universe poses an interesting challenge that may most efficiently be addressed by the use of closed-time-path techniques. A byproduct of these methods is an accurate and unified description of leptogenesis from oscillations of right-handed neutrinos that applies to the regime of ultraheavy as well as GeV-scale RHNs. For the latter scenario, we discuss the mechanism on the example of the osicllatory and overdamped parametric regimes and very briefly comment on the prospect of experimental tests

The present and future status of heavy neutral leptons

The existence of nonzero neutrino masses points to the likely existence of multiple Standard Model neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as heavy neutral leptons (HNLs). In this white paper, we discuss the present experimental status of HNLs including colliders, beta decay, accelerators, as well as astrophysical and cosmological impacts. We discuss the importance of continuing to search for HNLs, and its potential impact on our understanding of key fundamental questions, and additionally we outline the future prospects for next-generation future experiments or upcoming accelerator run scenarios