Jackson D. Clarke

Phenomenology of a very light scalar (100 MeV < mh < 10 GeV) mixing with the SM Higgs

A bstractIn this paper we investigate the phenomenology of a very light scalar, h, with mass 100 MeV < mh  < 10 GeV, mixing with the SM Higgs. As a benchmark model we take the real singlet scalar extension of the SM. We point out apparently unresolved uncertainties in the branching ratios and lifetime of h in a crucial region of parameter space for LHC phenomenology. Bounds from LEP, meson decays and fixed target experiments are reviewed. We also examine prospects at the LHC. For mh ≲ mB the dominant production mechanism is via meson decay; our main result is the calculation of the differential pT spectrum of h scalars originating from B mesons and the subsequent prediction of up to thousands of moderate (triggerable) pT displaced dimuons possibly hiding in the existing dataset at ATLAS/CMS or at LHCb. We also demonstrate that the subdominant V h production channel has the best sensitivity for mh ≳ mB and that future bounds in this region could conceivably compete with those of LEP.

Electroweak naturalness in the three-flavor type I seesaw model and implications for leptogenesis

In the Type I see-saw model, the naturalness requirement that corrections to the electroweak

Testing radiative neutrino mass models at the LHC

\mu

Natural leptogenesis and neutrino masses with two Higgs doublets

parameter not exceed 1 TeV results in a rough bound on the lightest right-handed neutrino mass,

Mirror dark matter will be confirmed or excluded by XENON1T

M_{N_1}\lesssim 3\times 10^7

Constraining portals with displaced Higgs decay searches at the LHC

GeV. In this letter we derive generic bounds applicable in any three-flavour Type I see-saw model. We find

Naturalness made easy: two-loop naturalness bounds on minimal SM extensions

M_{N_1}\lesssim 4\times 10^7

How to avoid unnatural hierarchical thermal leptogenesis

GeV and

Plasma dark matter direct detection

M_{N_2}\lesssim 7\times 10^7

Technically natural nonsupersymmetric model of neutrino masses, baryogenesis, the strong CP problem, and dark matter

GeV. In the limit of one massless neutrino, there is no naturalness bound on