194 research outputs found
On the MSSM with hierarchical squark masses and a heavier Higgs boson
In the contest of supersymmetric extensions of the Standard Model, we
consider a spectrum in which the lightest Higgs boson has mass between 200 and
300 GeV and the first two generations of squarks have masses above 20 TeV,
considering the Higgs boson mass and the Supersymmetric Flavour Problem as
related naturalness problems. After the analysis of some models in which the
previous spectrum can be naturally realised, we consider the phenomenological
consequences for the LHC and for Dark Matter.Comment: 8 pages, 5 figures, proceedings of the LC10 worksho
Can New Colored Particles Illuminate the Higgs?
We analyze the behavior of Higgs to diphoton rate and Higgs gluon-gluon
production cross section in minimal extensions of the Standard Model comprising
new colored vector-like fermions that do not mix with the ordinary ones. We
compare these information with constraints coming from electroweak precision
measurements. We compute pair production cross sections for the lightest
fermion and discuss the LHC bounds. Finally, we study the phenomenology of
possible quarkonium states composed by these new colored fermions.Comment: 18 pages, 7 figures. v2: typos fixed, references added, small
improvements mad
Probing light dark scalars with future experiments
We investigate a dark sector containing a pair of light non-degenerate scalar
particles, with masses in the MeV-GeV range, coupled to the visible sector
through heavier mediators. The heaviest dark state is long-lived, and its
decays offer new testable signals. We analyze the prospects for detection with
the proposed beam-dump facility SHiP, and the proposed LHC experiments FASER
and MATHUSLA. Moreover, we consider bounds from the beam-dump experiment CHARM
and from colliders (LEP, LHC and BaBar). We present our results both in terms
of an effective field theory, where the heavy mediators have been integrated
out, and of a simplified model containing a vector boson mediator, which can be
heavy TeV, or light GeV. We show that
future experiments can test large portions of the parameter space currently
unexplored, and that they are complementary to future High-Luminosity LHC
searches.Comment: 25 pages, 2 appendices, 6 figures. v2: version accepted for
publication. Several clarifications added, Figs. 3-5 modified to take into
account the heaviest state decay length. Conclusions unchange
Can the new resonance at LHC be a CP-Odd Higgs boson?
A plausible explanation of the recent experimental indication of a resonance
in the two-photon spectrum at LHC is that it corresponds to the CP-odd Higgs
boson. We explore such a possibility in a generic framework of the two Higgs
doublet models (2HDM), and combine GeV with the known ~GeV to show that the charged Higgs boson and the other CP-even
scalar masses become bounded from bellow and from above. We show that this
possibility is also consistent with the electroweak precision data and the low
energy observables, which we test in a few leptonic and semileptonic decay
modes.Comment: 16 pages, published versio
Collider phenomenology of Hidden Valley mediators of spin 0 or 1/2 with semivisible jets
Many models of Beyond the Standard Model physics contain particles that are
charged under both Standard Model and Hidden Valley gauge groups, yet very
little effort has been put into establishing their experimental signatures. We
provide a general overview of the collider phenomenology of spin 0 or 1/2
mediators with non-trivial gauge numbers under both the Standard Model and a
single new confining group. Due to the possibility of many unconventional
signatures, the focus is on direct production with semivisible jets. For the
mediators to be able to decay, a global symmetry must be broken. This is
best done by introducing a set of operators explicitly violating this symmetry.
We find that there is only a finite number of such renormalizable operators and
that the phenomenology can be classified into five distinct categories. We show
that large regions of the parameter space are already excluded, while others
are unconstrained by current search strategies. We also discuss how searches
could be modified to better probe these unconstrained regions by exploiting
special properties of semivisible jets.Comment: 40 pages, 11 figures, published versio
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