102 research outputs found
Dark-Photon searches via Higgs-boson production at the LHC
Dark photons mediating long-range forces in a dark sector are
predicted by various new physics scenarios, and are being intensively searched
for in experiments. We extend a previous study of a new discovery process for
dark photons proceedings via Higgs-boson production at the LHC. Thanks to the
non-decoupling properties of the Higgs boson, BR()
values up to a few percent are possible for a massless dark photon, even for
heavy dark-sector scenarios. The corresponding signature consists (for a Higgs
boson at rest) of a striking monochromatic photon with energy , and similar amount of missing energy. We perform a model independent
analysis at the LHC of both the gluon-fusion and VBF Higgs production
mechanisms at 14 TeV, including parton-shower effects, and updating our
previous parton-level analysis at 8 TeV in the gluon-fusion channel by a more
realistic background modeling. We find that a sensitivity can be
reached in the gluon-fusion channel for BR(0.1% with an integrated luminosity of . The corresponding VBF reach is instead restricted to 1%. Such decay
rates can be naturally obtained in dark-photon scenarios arising from unbroken
models explaining the origin and hierarchy of the Yukawa couplings,
strongly motivating the search for this exotic Higgs decay at the LHC.Comment: 8 pages, 3 figure
Observational Properties of Feebly Coupled Dark Matter
We show that decoupled hidden sectors can have observational consequences. As
a representative model example, we study dark matter production in the Higgs
portal model with one real singlet scalar coupled to the Standard Model
Higgs via and demonstrate how the
combination of non-observation of cosmological isocurvature perturbations and
astrophysical limits on dark matter self-interactions imply stringent bounds on
the magnitude of the scalar self-coupling . For example,
for dark matter mass MeV and Hubble scale during cosmic
inflation GeV, we find .Comment: 4 pages, 1 figure. Prepared for the proceedings of the ICHEP2016
conference, 3-10 August 2016, Chicago, United State
Evidence for Dark Matter Self-Interactions via Collisionless Shocks in Cluster Mergers
While dark matter self-interactions may solve several problems with structure
formation, so far only the effects of two-body scatterings of dark matter
particles have been considered. We show that, if a subdominant component of
dark matter is charged under an unbroken gauge group, collective dark
plasma effects need to be taken into account to understand its dynamics. Plasma
instabilities can lead to collisionless dark matter shocks in galaxy cluster
mergers which might have been already observed in the Abell 3827 and 520
clusters. As a concrete model we propose a thermally produced dark pair plasma
of vectorlike fermions. In this scenario the interacting dark matter component
is expected to be separated from the stars and the non-interacting dark matter
halos in cluster collisions. In addition, the missing satellite problem is
softened, while constraints from all other astrophysical and cosmological
observations are avoided.Comment: Matches the version to be published in Physics Letters
Higgs-boson production in association with a Dark Photon in collisions
We study the production of a Higgs boson recoiling from a massless invisible
system in collisions. This is a quite distinctive signature that
can arise when the Higgs boson is produced in association with a massless dark
photon, which can happen in BSM scenarios foreseeing an extra unbroken
gauge group. Dark photons can indeed acquire effective couplings to the Higgs
boson as occurs in models recently proposed to generate exponentially-spread
Yukawa couplings. We analyze the signal and corresponding backgrounds for , and estimate ILC and FCC-ee sensitivities in a model-independent
way.Comment: 25 pages, 12 figures; Conclusion Section expandend, to appear in
JHEP; v5: typographical errors correcte
Flavor constraints in a Bosonic Technicolor model
Flavor constraints in a bosonic Technicolor model are considered. We
illustrate different sources for their origin, and emphasize in particular the
role played by the vector states present in the Technicolor model. This feature
is the essential difference in comparison to an analogous model with two
fundamental Higgs scalar doublets.Comment: 16 pages, 13 figure
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