The 2019 International Workshop on Baryon and Lepton Number Violation (BLV2019) will be hosted by the Institute for Theoretical Physics (IFT) in Madrid, on October 21-24, 2019.
Oral contributions are by invitation only, except for PhD students: they are welcome to apply to participate in the PhD forum with a 5 min. plenary talk complemented with a poster on the same subject. Abstract submission for poster contributions is open for all participants. The deadline for abstract submission is July 15th, late submissions will be placed in a waiting list and considered if slots become available.
Partial support will be available for a limited number of young participants.
In this talk I will discuss the compatibility between the Neutrino Option, in which the electroweak scale is generated by PeV scale Majorana neutrinos, and leptogenesis. In particular, we find the Neutrino Option is consistent with resonant leptogenesis and we subsequently explore the viable parameter space.
In this talk, I will discuss some recent work on resonant leptogenesis in the context of the so-called "neutrino option". The "neutrino option" denotes the idea that the Higgs mass parameter results entirely from heavy-neutrino threshold corrections in the type-I seesaw extension of the Standard Model. This is possible for a heavy-neutrino mass scale of the order of 10^6 to 10^7 GeV, provided that the Higgs scalar potential satisfies classically scale-invariant boundary conditions at high energies. In my talk, I will describe the viable parameter space of this scenario, which is consistent with (1) the low-energy data on neutrino oscillations, (2) the observed value of the baryon asymmetry, and (3) electroweak symmetry breaking with a 125 GeV Higgs boson. In addition, I will highlight some interesting implications for high-energy flavor models and low-energy neutrino observables. This talk is based on work in collaboration with Vedran Brdar, Alexander J. Helmboldt, and Sho Iwamoto [1905.12634]. I will also refer to the closely related work by I. Brivio, K. Moffat, S. Pascoli, S.T. Petcov, and J. Turner [1905.12642].
High scale leptogenesis is notoriously difficult to probe experimentally. In this talk, I will discuss constraints on a minimal model, in which the observed baryon asymmetry is realized after the inflaton decays into the lightest sterile neutrino. Because this scenario induces a Higgs-inflation coupling at the radiative level, strong constraints come from the stability of the Higgs vacuum during pre-heating. The constraints are strongest when the sterile neutrino is thermal at production. I will show how these constraints depend on the reheat temperature, the inflaton mass, and the masses in the neutrino sector.
Recent observations of TeV blazars by Fermi identified deficits of secondary GeV cascade photons.
These observations can be explained by intergalactic magnetic fields, which may have a primordial origin.
If the magnetic fields are helical and generated in the early Universe such as before the electroweak symmetry
breaking, nontrivial interaction between (hyper)magnetic fields and other particles can cause some interesting
and non negligible phenomena in the early Universe.
In this talk, I will show that the baryon asymmetry can be generated by the chiral anomaly, and
baryon asymmetry is not completely washed out by the electroweak sphalerons.
Thus, this mechanism can be responsible for the present baryon asymmetry of the Universe.
If this mechanism is responsible for the present Universe, the BSM physics is needed for the generation
of (hyper)magnetic fields but not for the baryogenesis. I will also shortly discuss possible mechanism to generate
such helical hypermagnetic fields suitable for the baryogenesis scenario.
We present a study of the electroweak baryogenesis in composite Higgs models, with a focus on the case where the electroweak phase transition (EWPT) happens simultaneously with the confinement phase transition of the new strong sector. We show that the EWPT can naturally be strongly first order, and the scale-dependent top quark Yukawa can result in a sufficient amount of CP violation, without conflict with the current experimental constraints.
We explore the possibility that the electroweak phase transition happens at a scale much higher than the electroweak scale today. In this context, high scale CP-violating sources for electroweak baryogenesis are not constrained by low-energy experiments. We propose a scenario of high-scale electroweak baryogenesis linked to flavour physics. This scenario allows for a period of enhanced Yukawa couplings during the evolution of the universe, which source time-dependent CP violation. The electroweak symmetry is never restored after the high-scale phase transition due to negative contributions to the Higgs thermal mass squared from a large number of additional electroweak-scale neutral scalars coupling to the Higgs. As a result, the washout of the baryon asymmetry is avoided.
The Standard Model accompanied with two right-handed neutrinos with masses below the weak scale can explain the observed baryon asymmetry of the Universe. Moreover, this model is at least partially testable in the forthcoming experiments such as NA62, SHiP, and MATHUSLA. The remarkable progress in understanding of various rates entering the kinetic equations describing the asymmetry generation along with considerable improvements of the numerical procedures allow us to perform a comprehensive analysis of the parameter space of the model. We find that the region of parameters leading to successful baryogenesis is notably larger than it was previously obtained. Our results are presented in a way that they can be readily used for studies of sensitivity of various experiments searching for the right-handed neutrinos responsible for the baryon asymmetry of the Universe. We also present a detailed comparison with the studies by other groups.
Leptogenesis induced by the oscillations of GeV-scale neutrinos provides a minimal and testable explanation of the baryon asymmetry of the Universe. In this work we extend previous studies invoking only two heavy neutrinos to the case of three heavy neutrinos. We find qualitatively new behavior as a result of lepton number violating oscillations and decays, strong flavor effects in the washout and a resonant enhancement due to matter effects. An approximate global B-L symmetry (representing the difference of baryon and a generalized lepton number) can protect the light neutrino masses from large radiative corrections, while simultaneously providing the ingredients for the resonant enhancement of the lepton asymmetry due to thermal contributions to the heavy neutrino dispersion relations. This mechanism is particularly efficient for large heavy neutrino mixing angles near the current experimental limits, a regime in which leptogenesis is not feasible in the minimal scenario with two heavy neutrinos. In this new parameter regime, low-scale leptogenesis is testable by the LHC and other existing experiments.
In this talk we consider the scenario in which the Standard model is augmented by three generations of right-handed neutrinos and a scalar doublet. The newly introduced fields share an odd charge under a $\mathbb{Z}_2$ parity symmetry. We present a scenario in which the dark matter particle is at the keV-scale. Such particle is free from X-ray limits due to the unbroken parity symmetry that forbids the mixing between active and right-handed neutrinos. The active neutrino masses are radiatively generated from the new scalars and the two heavier right-handed states with $\sim \mathcal{O}(100)$ GeV masses. We demonstrate how these heavy fermions can also produce the observed baryon asymmetry of the Universe through the combination of Akhmedov-Rubakov-Smirnov mechanism and recently proposed scalar decays. We identify the parameter space where the successful leptogenesis is compatible with the observed abundance of dark matter as well as the measurements from the neutrino oscillation experiments.
In this talk, based on arXiv:1810.00880, I will present a new mechanism of Baryogenesis and dark matter production in which both the dark matter relic abundance and the baryon asymmetry arise from neutral B meson oscillations and subsequent decays.
We propose a new testable leptogenesis mechanism where the lepton asymmetry is generated from the interference of tree-level diagrams only. As a concrete example, we consider an amalgamation of the scotogenic model with an inert Higgs doublet and right-handed neutrinos, along with an electroweak-triplet scalar for a type-II seesaw. The imaginary part needed for the required CP-asymmetry comes from the trilinear coupling of the inert-doublet with the triplet. Neutrino mass is generated by both scotogenic and type-II seesaw contributions. The neutral component of the inert Higgs doublet serves as the dark matter candidate.
In this talk I will explore a simple model which naturally explains the observed BAU. The strong coupling is promoted to a dynamical quantity, evolving through the VEV of a singlet field which mixes with the Higgs. In the resulting cosmic history, QCD confinement and EWSB occur simultaneously close to the weak scale. The early confinement triggers the axion to roll toward its minimum, and the changing CP-violation is communicated to the weak sector through the eta' meson, resulting in spontaneous baryogenesis. I will identify the regions of parameter space for which the asymmetry is frozen in and relaxation to the Standard Model vacuum occurs before BBN. For these regions, I will also discuss current and future collider and cosmological constraints.