39 research outputs found
Scherk-Schwarz Supersymmetry Breaking in 4D
Using the techniques of dimensional deconstruction, we present 4D models that
fully reproduce the physics of 5D supersymmetric theories compactified on an
S^1/Z_2 orbifold with general Scherk-Schwarz supersymmetry breaking (SSSB)
boundary conditions. In contrast to previous approaches, our deconstruction
involves only soft supersymmetry breaking. Deconstruction preserves many of the
attractive features of SSSB without the cumbersome architecture of a full fifth
dimension, ambiguity of the ultraviolet completion, or challenges associated
with stabilizing a large radius of compactification. We proceed to deconstruct
various five-dimensional models featuring Scherk-Schwarz boundary conditions,
including folded supersymmetry.Comment: 21 pages with appendices, 6 figure
Semi-visible Jets: Dark Matter Undercover at the LHC
The dark matter may be a composite particle that is accessible via a weakly
coupled portal. If these hidden-sector states are produced at the Large Hadron
Collider (LHC), they would undergo a QCD-like shower. This would result in a
spray of stable invisible dark matter along with unstable states that decay
back to the Standard Model. Such "semi-visible" jets arise, for example, when
their production and decay are driven by a leptophobic resonance; the
resulting signature is characterized by significant missing energy aligned
along the direction of one of the jets. These events are vetoed by the current
suite of searches employed by the LHC, resulting in low acceptance. This Letter
will demonstrate that the transverse mass---computed using the final-state jets
and the missing energy---provides a powerful discriminator between the signal
and the QCD background. Assuming that the couples to the Standard Model
quarks with the same strength as the , the proposed search can discover
(exclude) masses up to 2.5 TeV (3.5 TeV) with 100 fb of 14 TeV data
at the LHC.Comment: 5 pages, 3 figures. v3: Supplementary material and references added.
Model changed from scalar to fermionic dark quarks and figures updated
accordingly. Conclusions unchange
Nuclear Structure of Bound States of Asymmetric Dark Matter
Models of Asymmetric Dark Matter (ADM) with a sufficiently attractive and
long-range force gives rise to stable bound objects, analogous to nuclei in the
Standard Model, called nuggets. We study the properties of these nuggets and
compute their profiles and binding energies. Our approach, applicable to both
elementary and composite fermionic ADM, utilizes relativistic mean field
theory, and allows a more systematic computation of nugget properties, over a
wider range of sizes and force mediator masses, compared to previous
literature. We identify three separate regimes of nugget property behavior
corresponding to (1) non-relativistic and (2) relativistic constituents in a
Coulomb-like limit, and (3) saturation in an anti-Coulomb limit when the
nuggets are large compared to the force range. We provide analytical
descriptions for nuggets in each regime. Through numerical calculations, we are
able to confirm our analytic descriptions and also obtain smooth transitions
for the nugget profiles between all three regimes. We also find that over a
wide range of parameter space, the binding energy in the saturation limit is an
fraction of the constituent's mass, significantly larger than
expectations in the non-relativistic case. In a companion paper, we apply our
results to synthesis of ADM nuggets in the early Universe.Comment: 20 pages, 8 figures, 1 appendi
Making Asymmetric Dark Matter Gold: Early Universe Synthesis of Nuggets
We compute the mass function of bound states of Asymmetric Dark
Matter--nuggets--synthesized in the early Universe. We apply our results for
the nugget density and binding energy computed from a nuclear model to obtain
analytic estimates of the typical nugget size exiting synthesis. We numerically
solve the Boltzmann equation for synthesis including two-to-two fusion
reactions, estimating the impact of bottlenecks on the mass function exiting
synthesis. These results provide the basis for studying the late Universe
cosmology of nuggets in a future companion paper.Comment: 27 pages, 11 figures, modified discussions in Section I
LHC limits on axion-like particles from heavy-ion collisions
In these proceedings we use recent LHC heavy-ion data to set a limit on
axion-like particles coupling to electromagnetism with mass in the range 10-100
GeV. We recast ATLAS data as per the strategy proposed in 1607.06083, and find
results in-line with the projections given there.Comment: 4 pages, 3 figures, conference proceeding for PHOTON201
Data Driven Search in the Displaced Pair Channel for a Higgs Boson Decaying to Long-Lived Neutral Particles
This article presents a proposal for a new search channel for the Higgs boson
decaying to two long-lived neutral particles, each of which decays to
at a displaced vertex. The decay length considered is such that the decay takes
place within the LHC beampipe. We present a new data-driven analysis using jet
substructure and properties of the tracks from the highly-displaced vertices.
We consider a model with a 125 GeV Higgs boson with a significant branching
fraction to decay via this mode, with the long-lived neutral particle having a
mass in the range of 15--40 GeV and a decay length commensurate with the beam
pipe radius.
Such a signal can be readily observed with an integrated luminosity of 19.5
fb at 8TeV at the LHC.Comment: 16 pages, 8 figures, Submitted to JHE
Jet Substructure by Accident
We propose a new search strategy for high-multiplicity hadronic final states.
When new particles are produced at threshold, the distribution of their decay
products is approximately isotropic. If there are many partons in the final
state, it is likely that several will be clustered into the same large-radius
jet. The resulting jet exhibits substructure, even though the parent states are
not boosted. This "accidental" substructure is a powerful discriminant against
background because it is more pronounced for high-multiplicity signals than for
QCD multijets. We demonstrate how to take advantage of accidental substructure
to reduce backgrounds without relying on the presence of missing energy. As an
example, we present the expected limits for several R-parity violating gluino
decay topologies. This approach allows for the determination of QCD backgrounds
using data-driven methods, which is crucial for the feasibility of any search
that targets signatures with many jets and suppressed missing energy.Comment: 20 + 7 pages, 8 figures; v2: references added, minor changes, journal
versio