1,238 research outputs found
Exploring Sensitivity to NMSSM Signatures with Low Missing Transverse Energy at the LHC
We examine scenarios in the Next-to-Minimal Supersymmetric Standard Model
(NMSSM), where pair-produced squarks and gluinos decay via two cascades, each
ending in a stable neutralino as Lightest Supersymmetric Particle (LSP) and a
Standard Model (SM)-like Higgs boson, with mass spectra such that the missing
transverse energy, , is very small. Performing
two-dimensional parameter scans and focusing on the hadronic decay giving a final state
we explore the sensitivity of a current LHC general-purpose
jets+ analysis to such scenarios.Comment: 17 pages, 17 figures, 6 table
The NUHM2 after LHC Run 1
We make a frequentist analysis of the parameter space of the NUHM2, in which
the soft supersymmetry (SUSY)-breaking contributions to the masses of the two
Higgs multiplets, , vary independently from the universal soft
SUSY-breaking contributions to the masses of squarks and sleptons. Our
analysis uses the MultiNest sampling algorithm with over points
to sample the NUHM2 parameter space. It includes the ATLAS and CMS Higgs mass
measurements as well as their searches for supersymmetric jets + MET signals
using the full LHC Run~1 data, the measurements of by
LHCb and CMS together with other B-physics observables, electroweak precision
observables and the XENON100 and LUX searches for spin-independent dark matter
scattering. We find that the preferred regions of the NUHM2 parameter space
have negative SUSY-breaking scalar masses squared for squarks and sleptons,
, as well as . The tension present in the
CMSSM and NUHM1 between the supersymmetric interpretation of and
the absence to date of SUSY at the LHC is not significantly alleviated in the
NUHM2. We find that the minimum with 21 degrees of freedom
(dof) in the NUHM2, to be compared with in the
CMSSM, and in the NUHM1. We find that the
one-dimensional likelihood functions for sparticle masses and other observables
are similar to those found previously in the CMSSM and NUHM1.Comment: 20 pages latex, 13 figure
Supersymmetric Dark Matter after LHC Run 1
Different mechanisms operate in various regions of the MSSM parameter space
to bring the relic density of the lightest neutralino, neutralino_1, assumed
here to be the LSP and thus the Dark Matter (DM) particle, into the range
allowed by astrophysics and cosmology. These mechanisms include coannihilation
with some nearly-degenerate next-to-lightest supersymmetric particle (NLSP)
such as the lighter stau (stau_1), stop (stop_1) or chargino (chargino_1),
resonant annihilation via direct-channel heavy Higgs bosons H/A, the light
Higgs boson h or the Z boson, and enhanced annihilation via a larger Higgsino
component of the LSP in the focus-point region. These mechanisms typically
select lower-dimensional subspaces in MSSM scenarios such as the CMSSM, NUHM1,
NUHM2 and pMSSM10. We analyze how future LHC and direct DM searches can
complement each other in the exploration of the different DM mechanisms within
these scenarios. We find that the stau_1 coannihilation regions of the CMSSM,
NUHM1, NUHM2 can largely be explored at the LHC via searches for missing E_T
events and long-lived charged particles, whereas their H/A funnel, focus-point
and chargino_1 coannihilation regions can largely be explored by the LZ and
Darwin DM direct detection experiments. We find that the dominant DM mechanism
in our pMSSM10 analysis is chargino_1 coannihilation: {parts of its parameter
space can be explored by the LHC, and a larger portion by future direct DM
searches.Comment: 21 pages, 8 figure
The pMSSM10 after LHC Run 1
We present a frequentist analysis of the parameter space of the pMSSM10, in
which the following 10 soft SUSY-breaking parameters are specified
independently at the mean scalar top mass scale Msusy = Sqrt[M_stop1 M_stop2]:
the gaugino masses M_{1,2,3}, the 1st-and 2nd-generation squark masses M_squ1 =
M_squ2, the third-generation squark mass M_squ3, a common slepton mass M_slep
and a common trilinear mixing parameter A, the Higgs mixing parameter mu, the
pseudoscalar Higgs mass M_A and tan beta. We use the MultiNest sampling
algorithm with 1.2 x 10^9 points to sample the pMSSM10 parameter space. A
dedicated study shows that the sensitivities to strongly-interacting SUSY
masses of ATLAS and CMS searches for jets, leptons + MET signals depend only
weakly on many of the other pMSSM10 parameters. With the aid of the Atom and
Scorpion codes, we also implement the LHC searches for EW-interacting
sparticles and light stops, so as to confront the pMSSM10 parameter space with
all relevant SUSY searches. In addition, our analysis includes Higgs mass and
rate measurements using the HiggsSignals code, SUSY Higgs exclusion bounds, the
measurements B-physics observables, EW precision observables, the CDM density
and searches for spin-independent DM scattering. We show that the pMSSM10 is
able to provide a SUSY interpretation of (g-2)_mu, unlike the CMSSM, NUHM1 and
NUHM2. As a result, we find (omitting Higgs rates) that the minimum chi^2/dof =
20.5/18 in the pMSSM10, corresponding to a chi^2 probability of 30.8 %, to be
compared with chi^2/dof = 32.8/24 (31.1/23) (30.3/22) in the CMSSM (NUHM1)
(NUHM2). We display 1-dimensional likelihood functions for SUSY masses, and
show that they may be significantly lighter in the pMSSM10 than in the CMSSM,
NUHM1 and NUHM2. We discuss the discovery potential of future LHC runs, e+e-
colliders and direct detection experiments.Comment: 47 pages, 29 figure
Predictions for Supersymmetric Particle Masses in the CMSSM using Indirect Experimental and Cosmological Constraints
In view of the imminent start of the LHC experimental programme, we use the
available indirect experimental and cosmological information to estimate the
likely range of parameters of the constrained minimal supersymmetric extension
of the Standard Model (CMSSM), using a Markov-chain Monte Carlo (MCMC)
technique to sample the parameter space. The 95% confidence-level area in the
(m_0, m_1/2) plane of the CMSSM lies largely within the region that could be
explored with 1/fb of integrated luminosity at 14 TeV, and much of the 68%
confidence-level area lies within the region that could be explored with 50/pb
of integrated luminosity at 10 TeV. A same-sign dilepton signal could well be
visible in most of the 68% confidence-level area with 1/fb of integrated
luminosity at 14 TeV. We discuss the sensitivities of the preferred ranges to
variations in the most relevant indirect experimental and cosmological
constraints and also to deviations from the universality of the
supersymmetry-breaking contributions to the masses of the Higgs bosons.Comment: 19 pages, 7 figure
Likelihood Functions for Supersymmetric Observables in Frequentist Analyses of the CMSSM and NUHM1
On the basis of frequentist analyses of experimental constraints from
electroweak precision data, g-2, B physics and cosmological data, we
investigate the parameters of the constrained MSSM (CMSSM) with universal soft
supersymmetry-breaking mass parameters, and a model with common non-universal
Higgs masses (NUHM1). We present chi^2 likelihood functions for the masses of
supersymmetric particles and Higgs bosons, as well as b to s gamma, b to mu mu
and the spin-independent dark matter scattering cross section. In the CMSSM we
find preferences for sparticle masses that are relatively light. In the NUHM1
the best-fit values for many sparticle masses are even slightly smaller, but
with greater uncertainties. The likelihood functions for most sparticle masses
are cut off sharply at small masses, in particular by the LEP Higgs mass
constraint. Both in the CMSSM and the NUHM1, the coannihilation region is
favoured over the focus-point region at about the 3-sigma level, largely but
not exclusively because of g-2. Many sparticle masses are highly correlated in
both the CMSSM and NUHM1, and most of the regions preferred at the 95% C.L. are
accessible to early LHC running. Some slepton and chargino/neutralino masses
should be in reach at the ILC. The masses of the heavier Higgs bosons should be
accessible at the LHC and the ILC in portions of the preferred regions in the
(M_A, tan beta) plane. In the CMSSM, the likelihood function for b to mu mu is
peaked close to the Standard Model value, but much larger values are possible
in the NUHM1. We find that values of the DM cross section > 10^{-10} pb are
preferred in both the CMSSM and the NUHM1. We study the effects of dropping the
g-2, b to s gamma, relic density and M_h constraints.Comment: 34 pages, 24 figure
Simulations of events for the LUX-ZEPLIN (LZ) dark matter experiment
The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1â2)Ă10â12 pb at a WIMP mass of 40 GeV/c2. This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data
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