Hilbert series for leptonic flavor invariants in the minimal seesaw model

In this paper, we examine the leptonic flavor invariants in the minimal see-saw model (MSM), in which only two right-handed neutrino singlets are added into the Standard Model in order to accommodate tiny neutrino masses and explain cosmological matter-antimatter asymmetry via leptogenesis mechanism. For the first time, we calculate the Hilbert series (HS) for the leptonic flavor invariants in the MSM. With the HS we demonstrate that there are totally 38 basic flavor invariants, among which 18 invariants are CP-odd and the others are CP-even. Moreover, we explicitly construct these basic invariants, and any other flavor invariants in the MSM can be decomposed into the polynomials of them. Interestingly, we find that any flavor invariants in the effective theory at the low-energy scale can be expressed as rational functions of those in the full MSM at the high-energy scale. Practical applications to the phenomenological studies of the MSM, such as the sufficient and necessary conditions for CP conservation and CP asymmetries in leptogenesis, are also briefly discussed.

Particle–Antiparticle Asymmetry in Relativistic Deformed Kinematics

Relativistic deformed kinematics are usually considered a way to capture the residual effects of a fundamental quantum gravity theory. These kinematics present a non-commutative addition law for the momenta so that the total momentum of a multi-particle system depends on the specific ordering in which the momenta are composed. We explore in the present work how this property may be used to generate an asymmetry between particles and antiparticles through a particular ordering prescription, resulting in a violation of CPT symmetry. We study its consequences for muon decay, obtaining a difference in the lifetimes of the particle and the antiparticle as a function of the new high-energy scale, parameterizing such relativistic deformed kinematics.

Perturbative unitarity in quasi-single field inflation

We study implications of perturbative unitarity for quasi-single field inflation with the inflaton and one massive scalar. Analyzing high energy scattering, we show that non-Gaussianities with |fNL| ≳ 1 cannot be realized without turning on interactions which violate unitarity at a high energy scale. Then, we provide a relation between fNL and the scale of new physics that is required for UV completion. In particular we find that for the Hubble scale H ≳ × 109 GeV, Planck suppressed operators can easily generate too large non-Gaussanities and so it is hard to realize successful quasi-single field inflation without introducing a mechanism to suppress quantum gravity corrections. Also we generalize the analysis to the regime where the isocurvature mode is heavy and the inflationary dynamics is captured by the inflaton effective theory. Requiring perturbative unitarity of the two-scalar UV models with the inflaton and one heavy scalar, we clarify the parameter space of the P(X, ϕ) model which is UV completable by a single heavy scalar.

Thermal, trapped and chromo-natural inflation in light of the swampland criteria and the trans-Planckian censorship conjecture

We consider thermal, trapped and chromo-natural inflation in light of the swampland criteria and the Trans-Planckian Censorship Conjecture (TCC). Since thermal inflation occurs at energies low compared to those of Grand Unification, it is consistent with the TCC, and it is also consistent with the refined swampland conditions. Trapped and chromo-natural inflation are candidates for primordial (high energy scale) inflation. Since in both of these scenarios there are effective damping terms in the scalar field equation of motion, the models can easily be consistent with the swampland criteria. The TCC, on the other hand, constrains these scenarios to only take place at low energies.

Bounds on Relativistic Deformed Kinematics from the Physics of the Universe Transparency

We analyze the kinematics of electron-positron production in a photon-photon interaction when one has a modification of the special relativistic kinematics as a power expansion in the inverse of a new high-energy scale. We derive the equation for the threshold energy of this reaction to first order in this expansion, including the effects due to a modification of the energy-momentum conservation equation. In contrast with the Lorentz invariance violation case, a scale of the order of a few TeV is found to be compatible with the observations of very high-energy cosmic gamma rays in the case of a modification compatible with the relativity principle.

Probing ALP-sterile neutrino couplings at the LHC

In this work, prospects to probe an overlooked facet of axion-like particles (ALPs) — their potential couplings to sterile neutrinos — are presented. We found that mono-photon searches have the potential to constrain ALP couplings to sterile neutrinos when a new heavy scalar boosts the ALP decay yields. Working within an effective field theory (EFT) approach, we scan the parameters space to establish the reach of the 13 TeV LHC to probe such couplings. We found regions of the parameters space evading several experimental constraints that can be probed at the LHC. Moreover, a complementary role between the LHC and various experiments that search for axions and ALPs can be anticipated for models where ALPs interact with sterile neutrinos. We also present the UV realization of a model having an axion-like particle, a heavy scalar and sterile neutrinos whose parameters are spanned by our EFT approach. The proposed model contains a type of seesaw mechanism for generating masses for the active neutrinos along with sterile neutrinos involving the high energy scale of the spontaneous breaking of the global symmetry associated to the ALP. Some benchmark points of this model can be discovered at the 13 TeV LHC with 300 fb−1.

Cosmological Probes of Supersymmetric Field Theory Models at Superhigh Energy Scales

The lack of positive results in searches for supersymmetric (SUSY) particles at the Large Hadron Collider (LHC) and in direct searches for Weakly Interacting Massive Particles (WIMPs) in the underground experiments may hint to a super-high energy scale of SUSY phenomena beyond the reach of direct experimental probes. At such scales the supergravity models based on Starobinsky inflation can provide the mechanisms for both inflation and superheavy dark matter. However, it makes the indirect methods the only way of testing the SUSY models, so that cosmological probes acquire the special role in this context. Such probes can rely on the nontrivial effects of SUSY physics in the early Universe, which are all model-dependent and thus can provide discrimination of the models and their parameters. The nonstandard cosmological features like Primordial Black Holes (PBHs) or antimatter domains in a baryon-asymmetric universe are discussed as possible probes for high energy scale SUSY physics.

Lorentz Violation, Möller Scattering, and Finite Temperature

Lorentz and CPT symmetries may be violated in new physics that emerges at very high energy scale, that is, at the Planck scale. The differential cross section of the Möller scattering due to Lorentz violation at finite temperature is calculated. Lorentz-violating effects emerge from an interaction vertex due to a CPT-odd nonminimal coupling in the covariant derivative. The finite temperature effects are determined using the Thermo Field Dynamics (TFD) formalism.