43 research outputs found
Singlet-doublet fermion and triplet scalar dark matter with radiative neutrino masses
We present a detailed study of a combined singlet-doublet fermion and triplet
scalar model for dark matter. These models have only been studied separately in
the past. Together, they form a simple extension of the Standard Model that can
account for dark matter and explain the existence of neutrino masses, which are
generated radiatively. This holds even if singlet-doublet fermions and triplet
scalars never contribute simultaneously to the dark matter abundance. However,
this also implies the existence of lepton flavour violating processes. In
addition, this particular model allows for gauge coupling unification. The new
fields are odd under a new symmetry to stabilise the dark matter
candidate. We analyse the dark matter, neutrino mass and lepton flavour
violation aspects both separately and in conjunction, exploring the viable
parameter space of the model. This is done using a numerical random scan
imposing successively the neutrino mass and mixing, relic density, Higgs mass,
direct detection, collider and lepton flavour violation constraints. We find
that dark matter in this model is fermionic for masses below about 1 TeV and
scalar above. The narrow mass regions found previously for the two separate
models are enlarged by their coupling. While coannihilations of the weak
isospin partners are sizeable, this is not the case for fermions and scalars
despite their often similar masses due to the relatively small coupling of the
two sectors, imposed by the small neutrino masses. We observe a high degree of
complementarity between direct detection and lepton flavour violation
experiments, which should soon allow to fully probe the fermionic dark matter
sector and at least partially the scalar dark matter sector.Comment: 24 pages, 12 figures; version accepted by and published in JHE
Singlet-doublet/triplet dark matter and neutrino masses
In these proceedings, we present a study of a combined singlet--doublet
fermion and triplet scalar model for dark matter (DM). Together, these models
form a simple extension of the Standard Model (SM) that can account for DM and
explain the existence of neutrino masses, which are generated radiatively.
However, this also implies the existence of lepton flavour violating (LFV)
processes. In addition, this particular model allows for gauge coupling
unification. The new fields are odd under a new symmetry to
stabilise the DM candidate. We analyse the DM, neutrino mass and LFV aspects,
exploring the viable parameter space of the model. This is done using a
numerical random scan imposing successively the neutrino mass and mixing, relic
density, Higgs mass, direct detection, collider and LFV constraints. We find
that DM in this model is fermionic for masses below about 1 TeV and scalar
above. We observe a high degree of complementarity between direct detection and
LFV experiments, which should soon allow to fully probe the fermionic DM sector
and at least partially the scalar DM sector.Comment: 4 pages, 1 figure; contribution to the 2019 EW session of the 54th
Rencontres de Moriond (summary of arXiv:1812.11133
Photon-induced contributions to di-lepton production at the LHC Run II
We report on recent studies of photon-induced (PI) contributions to di-lepton
production and their implications for Beyond Standard Model (BSM)
-bosons searches at the LHC.Comment: Proceedings of XXV International Workshop on Deep-Inelastic
Scattering and Related Subjects, 3-7 April 2017, University of Birmingham, U
Real and virtual photons effects in di-lepton production at the LHC
We show the SM prediction of di-lepton production at the LHC where to the
usual Drell-Yan production we add the contribution from Photon-Initiated
processes. We discuss the effects of the inclusion of photon interactions in
the high invariant mass region (TeV region) and their consequences on BSM heavy
Z'-boson searches.Comment: 7 pages, 6 figures, Proceeding of Les Rencontres de Physique de la
Vall\'ee d'Aoste, La Thuile 201
The effect of real and virtual photons in the di-lepton channel at the LHC
We present a study of di-lepton production at the CERN Large Hadron Collider
with a particular focus on the contribution resulting from both real and
virtual photons in the initial state. We discuss the region of phase space in
which the invariant mass of the lepton pair is of the order of several TeV,
where searches for new physics phenomena yielding a di-lepton signature are
presently carried out. We study both the yield and associated uncertainties for
all possible topologies in photon-induced di-lepton production and compare
these with what is expected in the standard Drell-Yan channel, where
quark-antiquark pairs are responsible for the production of lepton pairs. We
analyse the impact of these QED contributions on the expected Standard Model
background and on searches for new physics. In this latter case, we use the
production of an extra heavy -boson predicted by the Sequential
Standard Model (SSM) as a benchmark process.Comment: 9 pages, 5 figure
Complementarity of Forward-Backward Asymmetry for discovery of Z' bosons at the Large Hadron Collider
The Forward-Backward Asymmetry (AFB) in Z' physics is commonly only thought
of as an observable which possibly allows one to profiling a Z' signal by
distinguishing different models embedding such (heavy) spin-1 bosons. In this
brief review, we examine the potential of AFB in setting bounds on or even
discovering a Z' at the Large Hadron Collider (LHC) and proof that it might be
a powerful tool for this purpose. We analyse two different scenarios: Z's with
a narrow and wide width, respectively. We find that, in both cases, AFB can
complement the conventional searches in accessing Z' signals traditionally
based on cross section measurements only.Comment: arXiv admin note: substantial text overlap with arXiv:1504.0316