65 research outputs found
Signals of supersymmetry with inaccessible first two families at the Large Hadron Collider
We investigate the signals of supersymmetry (SUSY) in a scenario where only
the third family squarks and sleptons can be produced at the Large Hadron
Collider (LHC), in addition to the gluino, charginos and neutralinos. The final
states in such cases are marked by a multiplicity of top and/or bottom quarks.
We study in particular, the case when the stop, sbottom and gluino masses are
near the TeV scale due to which, the final state t's and b's are very
energetic. We point out the difficulty in b-tagging and identifying energetic
tops and suggest several event selection criteria which allow the signals to
remain significantly above the standard model background. We show that such
scenarios with gluino mass up to 2 TeV can be successfully probed at the LHC.
Information on can also be obtained by looking at associated Higgs
production in the cascades of accompanying neutralinos. We also show that a
combined analysis of event rates in the different channels and the effective
mass distribution allows one to differentiate this scenario from the one where
all three sfermion families are accessible.Comment: v3: 17 pages, 8 figures, 7 table
An updated analysis of radion-higgs mixing in the light of LHC data
We explore the constraints on the parameter space of a Randall-Sundrum warped
geometry scenario, where a radion field arises out of the attempt to stabilise
the radius of the extra compact spacelike dimension, using the most recent data
from higgs searches at the Large Hadron Collider (LHC) and the Tevatron. We
calculate contributions from both the scalar mass eigenstates arising from
radion-higgs kinetic mixing in all important search channels. The most
important channel to be affected is the decay via WW*, where no invariant mass
peak can discern the two distinct physical states. Improving upon the previous
studies, we perform a full analysis in the WW* channel, taking into account the
effect of various cuts and interference when the two scalar are closely spaced.
We examine both cases where the experimentally discovered scalar is either
'higgs-like' or 'radion-like'. The implications of a relatively massive scalar
decaying into a pair of 125 GeV scalars is also included. Based on a global
analysis of the current data, including not only a single 125 GeV scalar but
also another one with mass over the range 110 to 600 GeV, we obtain the
up-to-date exclusion contours in the parameter space. Side by side, regions
agreeing with the data within 68% and 95% confidence level based on a
\chi^2-minimisation procedure, are also presented
Compressed and Split Spectra in Minimal SUSY SO(10)
The non-observation of supersymmetric signatures in searches at the Large
Hadron Collider strongly constrains minimal supersymmetric models like the
CMSSM. We explore the consequences on the SUSY particle spectrum in a minimal
SO(10) with large D-terms and non-universal gaugino masses at the GUT scale.
This changes the sparticle spectrum in a testable way and for example can
sufficiently split the coloured and non-coloured sectors. The splitting
provided by use of the SO(10) D-terms can be exploited to obtain light first
generation sleptons or third generation squarks, the latter corresponding to a
compressed spectrum scenario.Comment: 35 pages, 10 figures, published versio
Closing in on the Tip of the CMSSM Stau Coannihilation Strip
Near the tip of the stau coannihilation strip in the CMSSM with a neutralino
LSP, the astrophysical cold dark matter density constraint forces the
stau-neutralino mass difference to be small. If this mass difference is smaller
than the tau mass, the stau may decay either in the outer part of an LHC
detector - the `disappearing track' signature - or be sufficiently long-lived
to leave the detector before decaying - the long-lived massive charged-particle
signature. We combine searches for these signatures with conventional missing
transverse energy searches during LHC Run 1, identifying the small remaining
parts of the CMSSM stau coannihilation strip region that have not yet been
excluded, and discussing how they may be explored during Run 2 of the LHC.Comment: 19 pages, 6 figures. Fig. 1 and the corresponding text are changed
due to the updated ATLAS result (ref.[16]). More details of our simulation
are provided in Section 3.1. The caption of Fig. 6 and the corresponding text
are changed. Matches the published versio
CheckMATE 2: From the model to the limit
We present the latest developments to the CheckMATE program that allows
models of new physics to be easily tested against the recent LHC data. To
achieve this goal, the core of CheckMATE now contains over 60 LHC analyses of
which 12 are from the 13 TeV run. The main new feature is that CheckMATE 2 now
integrates the Monte Carlo event generation via Madgraph and Pythia 8. This
allows users to go directly from a SLHA file or UFO model to the result of
whether a model is allowed or not. In addition, the integration of the event
generation leads to a significant increase in the speed of the program. Many
other improvements have also been made, including the possibility to now
combine signal regions to give a total likelihood for a model.Comment: 53 pages, 6 figures; references updated, instructions slightly
change
The charged Higgs from the Bottom-Up: probing flavor at the LHC
We systematically study model-independent constraints on the three generic charged Higgs couplings to -quarks and up-type quarks. While existing LHC searches have focussed on the coupling, we emphasize that the LHC plays a crucial role in probing also and couplings, since constraints from flavor physics are weak. In particular we propose various new searches that can significantly extend the present reach on the parameter space by: i) looking for light charged Higgses that decay into -quarks, ii) probing charged Higgs couplings to light and top quarks using multi--jet signatures, iii) looking for single -quarks in low-mass dijet searches, iv) searching for charge asymmetries induced by charged Higgs production via couplings
The Charged Higgs from the Bottom-Up: Probing Flavor at the LHC
We systematically study model-independent constraints on the three generic
charged Higgs couplings to -quarks and up-type quarks. While existing LHC
searches have focussed on the coupling, we emphasize that the LHC plays a
crucial role in probing also and couplings, since constraints from
flavor physics are weak. In particular we propose various new searches that can
significantly extend the present reach on the parameter space by: i) looking
for light charged Higgses that decay into -quarks, ii) probing charged
Higgs couplings to light and top quarks using multi--jet signatures, iii)
looking for single -quarks in low-mass dijet searches, iv) searching for
charge asymmetries induced by charged Higgs production via couplings.Comment: 20 pages + appendices, 18 figure
Is charged lepton flavor violation a high energy phenomenon?
Searches for rare processes such as μ-> e gamma put stringent limits on lepton flavor violation expected in many beyond-the-Standard-Model physics scenarios. This usually precludes the observation of flavor violation at high energy colliders such as the LHC. We here discuss a scenario where right-handed neutrinos are produced via a Z' portal but which can only decay via small flavor violating couplings. Consequently, the process rate is unsuppressed by the small couplings and can be visible despite unobservably small μ-> e gamma rates
- …