Publications (5)15.84 Total impact

Article: Status of the ZeeBabu model for neutrino mass and possible tests at a likesign linear collider
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ABSTRACT: We provide an updated scan of the allowed parameter space of the twoloop ZeeBabu model for neutrino mass. Taking into account most recent experimental data on $\mu\to e\gamma$ as well as the mixing angle $\theta_{13}$ we obtain lower bounds on the masses of the singly and doubly charged scalars of between 1 to 2 TeV, with some dependence on perturbativity and finetuning requirements. This makes the scalars difficult to observe at LHC with 14 TeV even with optimistic assumptions on the luminosity, and would require a multiTeV linear collider to see the scalar resonances. We point out, however, that a subTeV linear collider in the likesign mode may be able to observe lepton flavour violating processes such as $e^ e^ \to \mu^ \mu^$ due to contact interactions induced by the doubly charged scalar with masses up to around 10 TeV. We investigate the possibility to distinguish the ZeeBabu model from the Higgs triplet model using such processes.Nuclear Physics B 02/2014; · 3.95 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We consider a U(1)' gauge symmetry acting on three generations of righthanded neutrinos. The U(1)' symmetry is broken at the TeV scale and its remnant discrete symmetry makes one of the righthanded neutrinos stable. As a natural consequence of the anomaly cancellation, the neutrino mass matrix consists of a combination of Type I (TeV scale) seesaw and radiative correction. The stable righthanded neutrino communicates with the Standard Model via schannel exchange of the Higgs field and the U(1)' gauge boson, so that the observed relic density for dark matter is obtained in a wide range of the parameter space. The experimental signatures in collider and other experiments are briefly discussed.10/2013; 89(1). 
Article: New Production Mechanism for keV Sterile Neutrino Dark Matter by Decays of FrozenIn Scalars
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ABSTRACT: We propose a new production mechanism for keV sterile neutrino Dark Matter. In our setting, we assume the existence of a scalar singlet particle which never entered thermal equilibrium in the early Universe, since it only couples to the Standard Model fields by a really small Higgs portal interaction. For suitable values of this coupling, the scalar can undergo the socalled freezein process, and in this way be efficiently produced in the early Universe. These scalars can then decay into keV sterile neutrinos and produce the correct Dark Matter abundance. While similar settings in which the scalar does enter thermal equilibrium and then freezes out have been studied previously, the mechanism proposed here is new and represents a versatile extension of the known case. We perform a detailed numerical calculation of the DM production using a set of coupled Boltzmann equations, and we illustrate the successful regions in the parameter space. Our production mechanism notably can even work in models where activesterile mixing is completely absent.Journal of Cosmology and Astroparticle Physics 06/2013; · 5.88 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We consider an electroweak scale model for Dark Matter (DM) and radiative neutrino mass generation. Despite the leptophilic nature of DM with no direct couplings to quarks and gluons, scattering with nuclei is induced at the 1loop level through photon exchange. Effectively, there are chargecharge, dipolecharge and dipoledipole interactions. We investigate the parameter space consistent with constraints from neutrino masses and mixing, charged leptonflavour violation, perturbativity, and the thermal production of the correct DM abundance, and calculate the expected event rate in DM direct detection experiments. We show that current data from XENON100 start to constrain certain regions of the allowed parameter space, whereas future data from XENON1T has the potential to significantly probe the model.Physical review D: Particles and fields 01/2012; 85(7).  [Show abstract] [Hide abstract]
ABSTRACT: We present a scenario where neutrino masses and Dark Matter are related due to a global $U(1)_{BL}$ symmetry. Specifically we consider neutrino mass generation via the ZeeBabu twoloop mechanism, augmented by a scalar singlet whose VEV breaks the global $U(1)_{BL}$ symmetry. In order to obtain a Dark Matter candidate we introduce two Standard Model singlet fermions. They form a Dirac particle and are stable because of a remnant $Z_2$ symmetry. Hence, in this model the stability of Dark Matter follows from the global $U(1)_{BL}$ symmetry. We discuss the Dark Matter phenomenology of the model, and compare it to similar models based on gauged $U(1)_{BL}$. We argue that in contrast to the gauged versions, the model based on the global symmetry does not suffer from severe constraints from $Z'$ searches.Physics Letters B 05/2011; 705(4). · 6.02 Impact Factor
Publication Stats
45  Citations  
15.84  Total Impact Points  
Top Journals
Institutions

2011–2014

Max Planck Institute for Nuclear Physics
Heidelburg, BadenWürttemberg, Germany
