[ NIKHEF theory group ]

Purpose

To meet, discuss, collaborate, generate ideas, share expertise, in the context of the FOM programme "Higgs as Probe and Portal"

We hope to see you here!

Agenda 2 November 2018

Time: 10.00 - 17.00
  • 10.30 - 11.00, H320:

    Shintaro Eijima (Leiden)
    Parameter space of baryogenesis via testable right-handed neutrinos

    Abstract: The Standard Model accompanied with two right-handed neutrinos with the masses below the weak scale can explain the observed baryon asymmetry of the Universe as well as non-zero neutrino masses. 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 the 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.



  • 15.00 - 16.00, H320
    Student meeting/discussion:

    Andrew Magalich
    Lyman-alpha forest as a diagnostic for Warm Dark Matter

    Abstract: LambdaCDM paradigm is extremely successful at describing the large scale structure formation. However, there is a number of observations suggesting deviations from CDM on small scales, such as too-big-to-fail and core-cusp problems. Physically-motivated Warm Dark Matter candidates like Sterile Neutrino WDM could resolve this by introducing small-scale suppression in the Matter Power Spectrum. While the direct measurement of small-scale MPS is challenging, Lyman-alpha absorption spectra of distant quasars provide a proxy to the underlying matter distribution. Interestingly, Lyman-alpha forest Flux Power Spectrum exhibits a cut-off on the scales below ~30 km/s, that could be explained by peculiar velocities, Doppler broadening, physical size of absorbers as well as free-streaming of DM particles. We investigate the origin of the cut-off and implications for searches of DM particle.



  • 16.30 - 17.00, H320

    Iason Baldes (Brussel)
    High Scale Electroweak Baryogenesis

    Abstract: 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.



  • 17.00 Borrel