52,888 research outputs found
Discovering SUSY with in the First LHC Physics Run
In minimal supergravity, the parameter space where the slepton is the LSP is
usually neglected, because of strong constraints on charged dark matter. When
the gravitino is the true LSP, this region avoids these constraints and offers
spectacular collider signals. We investigate this scenario for the LHC and find
that a large portion of the ignored mSugra parameter space can lead to
discovery within the first physics run, with 1-4 of data. We
find that there are regions where discovery is feasible with only 1 day of
running
New Particles Working Group Report of the Snowmass 2013 Community Summer Study
This report summarizes the work of the Energy Frontier New Physics working
group of the 2013 Community Summer Study (Snowmass)
Towards the Natural Gauge Mediation
The sweet spot supersymmetry (SUSY) solves the mu problem in the Minimal
Supersymmetric Standard Model (MSSM) with gauge mediated SUSY breaking (GMSB)
via the generalized Giudice-Masiero (GM) mechanism where only the mu-term and
soft Higgs masses are generated at the unification scale of the Grand Unified
Theory (GUT) due to the approximate PQ symmetry. Because all the other SUSY
breaking soft terms are generated via the GMSB below the GUT scale, there
exists SUSY electroweak (EW) fine-tuning problem to explain the 125 GeV Higgs
boson mass due to small trilinear soft term. Thus, to explain the Higgs boson
mass, we propose the GMSB with both the generalized GM mechanism and
Higgs-messenger interactions. The renormalization group equations are runnings
from the GUT scale down to EW scale. So the EW symmetry breaking can be
realized easier. We can keep the gauge coupling unification and solution to the
flavor problem in the GMSB, as well as solve the \mu/B_{\mu}-problem. Moreover,
there are only five free parameters in our model. So we can determine the
characteristic low energy spectra and explore its distinct phenomenology. The
low-scale fine-tuning measure can be as low as 20 with the light stop mass
below 1 TeV and gluino mass below 2 TeV. The gravitino dark matter can come
from a thermal production with the correct relic density and be consistent with
the thermal leptogenesis. Because gluino and stop can be relatively light in
our model, how to search for such GMSB at the upcoming run II of the LHC
experiment could be very interesting.Comment: 22 pages, 7 figures, Late
Signatures of sneutrino dark matter in an extension of the CMSSM
Current data (LHC direct searches, Higgs mass, dark matter-related bounds)
severely affect the constrained minimal SUSY standard model (CMSSM) with
neutralinos as dark matter candidates. But the evidence for neutrino masses
coming from oscillations requires extending the SM with at least right-handed
neutrinos with a Dirac mass term. In turn, this implies extending the CMSSM
with right-handed sneutrino superpartners, a scenario we dub CMSSM.
These additional states constitute alternative dark matter candidates of the
superWIMP type, produced via the decay of the long-lived next-to-lightest SUSY
particle (NLSP). Here we consider the interesting and likely case where the
NLSP is a : despite the modest extension with respect to the
CMSSM this scenario has the distinctive signatures of heavy, stable charged
particles. After taking into account the role played by neutrino mass bounds
and the specific cosmological bounds from the big bang nucleosynthesis in
selecting the viable parameter space, we discuss the excellent discovery
prospects for this model at the future runs of the LHC. We show that it is
possible to probe masses up to 600 GeV at the 14 TeV LHC with
fb when one considers a pair production of staus
with two or more hard jets through all SUSY processes. We also show the
complementary discovery prospects from a direct pair production,
as well as at the new experiment MoEDAL.Comment: 31 pages, 6 figures and 5 tables; v2 : discussions and references
added, conclusions unchanged. To appear in JHE
LHC Signals from Cascade Decays of Warped Vector Resonances
Recently (arXiv:1608.00526), a new framework for warped higher-dimensional
compactifications with "bulk" standard model (SM) was proposed: in addition to
the UV (Planck scale) and IR (a couple of TeV) branes, there is an intermediate
brane, taken to be around 10 TeV. The SM matter and Higgs fields propagate from
the UV brane down to this intermediate brane only, while gauge and gravity
fields propagate in the entire bulk. Such a configuration renders the lightest
gauge Kaluza-Klein (KK) states within LHC reach, simultaneously satisfying
flavor and CP constraints. In addition, the usual leading decay modes of the
lightest KK gauge bosons into top and Higgs bosons are suppressed. This effect
permits erstwhile subdominant channels to become significant. These include
flavor-universal decays to SM fermions and Higgs bosons, and a novel channel -
decay to a radion and a SM gauge boson, followed by radion decay to a pair of
SM gauge bosons. In this work, we first delineate the parameter space where the
above mentioned cascade decay of gauge KK particles dominates, and thereby can
be the discovery mode at the LHC. We then perform a detailed analysis of the
LHC signals from this model, finding that 300/fb suffices for evidence of
KK-gluon in tri-jet, jet + di-photon and jet + di-boson channels. However, KK
photon in photon + di-jet, and KK-W in leptonic W + di-jet require 3000/fb. The
crucial feature of this decay chain is a "double" resonance, i.e. 3-particle
and 2-particle invariant mass peaks, corresponding to the KK gauge boson and
the radion respectively.Comment: 50 page
Heavy Color-Octet Particles at the LHC
Many new-physics models, especially those with a color-triplet top-quark
partner, contain a heavy color-octet state. The "naturalness" argument for a
light Higgs boson requires that the color-octet state be not much heavier than
a TeV, and thus it can be pair-produced with large cross sections at
high-energy hadron colliders. It may decay preferentially to a top quark plus a
top-partner, which subsequently decays to a top quark plus a color-singlet
state. This singlet can serve as a WIMP dark-matter candidate. Such decay
chains lead to a spectacular signal of four top quarks plus missing energy. We
pursue a general categorization of the color-octet states and their decay
products according to their spin and gauge quantum numbers. We review the
current bounds on the new states at the LHC and study the expected discovery
reach at the 8-TeV and 14-TeV runs. We also present the production rates at a
future 100-TeV hadron collider, where the cross sections will be many orders of
magnitude greater than at the 14-TeV LHC. Furthermore, we explore the extent to
which one can determine the color octet's mass, spin, and chiral couplings.
Finally, we propose a test to determine whether the fermionic color octet is a
Majorana particle.Comment: 20 pages, 9 figures; journal versio
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