278 research outputs found
Photonic SUSY Two-Loop Corrections to the Muon Magnetic Moment
Photonic SUSY two-loop corrections to the muon magnetic moment are
contributions from diagrams where an additional photon loop is attached to a
SUSY one-loop diagram. These photonic corrections are evaluated exactly,
extending a leading-log calculation by Degrassi and Giudice. Compact analytical
expressions are provided and the numerical behaviour is discussed. The photonic
corrections reduce the SUSY one-loop result by 7...9%. The new terms are
typically around ten times smaller than the leading logarithms, but they can be
larger and have either sign in cases with large SUSY mass splittings. We also
provide details on renormalization and regularization and on how to incorporate
the photonic corrections into a full SUSY two-loop calculation.Comment: 25 page
Implications of Improved Higgs Mass Calculations for Supersymmetric Models
We discuss the allowed parameter spaces of supersymmetric scenarios in light
of improved Higgs mass predictions provided by FeynHiggs 2.10.0. The Higgs mass
predictions combine Feynman-diagrammatic results with a resummation of leading
and subleading logarithmic corrections from the stop/top sector, which yield a
significant improvement in the region of large stop masses. Scans in the pMSSM
parameter space show that, for given values of the soft supersymmetry-breaking
parameters, the new logarithmic contributions beyond the two-loop order
implemented in FeynHiggs tend to give larger values of the light CP-even Higgs
mass, M_h, in the region of large stop masses than previous predictions that
were based on a fixed-order Feynman-diagrammatic result, though the differences
are generally consistent with the previous estimates of theoretical
uncertainties. We re-analyze the parameter spaces of the CMSSM, NUHM1 and
NUHM2, taking into account also the constraints from CMS and LHCb measurements
of B_s to \mu+\mu- and ATLAS searches for MET events using 20/fb of LHC data at
8 TeV. Within the CMSSM, the Higgs mass constraint disfavours tan beta lesssim
10, though not in the NUHM1 or NUHM2.Comment: 22 pages, 17 figure
Frequentist Analysis of the Parameter Space of Minimal Supergravity
We make a frequentist analysis of the parameter space of minimal supergravity
(mSUGRA), in which, as well as the gaugino and scalar soft
supersymmetry-breaking parameters being universal, there is a specific relation
between the trilinear, bilinear and scalar supersymmetry-breaking parameters,
A_0 = B_0 + m_0, and the gravitino mass is fixed by m_{3/2} = m_0. We also
consider a more general model, in which the gravitino mass constraint is
relaxed (the VCMSSM). We combine in the global likelihood function the
experimental constraints from low-energy electroweak precision data, the
anomalous magnetic moment of the muon, the lightest Higgs boson mass M_h, B
physics and the astrophysical cold dark matter density, assuming that the
lightest supersymmetric particle (LSP) is a neutralino. In the VCMSSM, we find
a preference for values of m_{1/2} and m_0 similar to those found previously in
frequentist analyses of the constrained MSSM (CMSSM) and a model with common
non-universal Higgs masses (NUHM1). On the other hand, in mSUGRA we find two
preferred regions: one with larger values of both m_{1/2} and m_0 than in the
VCMSSM, and one with large m_0 but small m_{1/2}. We compare the probabilities
of the frequentist fits in mSUGRA, the VCMSSM, the CMSSM and the NUHM1: the
probability that mSUGRA is consistent with the present data is significantly
less than in the other models. We also discuss the mSUGRA and VCMSSM
predictions for sparticle masses and other observables, identifying potential
signatures at the LHC and elsewhere.Comment: 18 pages 27 figure
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
Physics Opportunities at mu+mu- Higgs Factories
We update theoretical studies of the physics opportunities presented by
mu+mu- Higgs factories. Interesting measurements of the Standard Model Higgs
decays into {\bar b}b, tau+tau- and WW* may be possible if the Higgs mass is
less than about 160 GeV, as preferred by the precision electroweak data, the
mass range being extended by varying appropriately the beam energy resolution.
A suitable value of the beam energy resolution would also enable the
uncertainty in the b-quark mass to be minimized, facilitating measurements of
parameters in the MSSM at such a first mu+mu- Higgs factory. These measurements
would be sensitive to radiative corrections to the Higgs-fermion-antifermion
decay vertices, which may violate CP. Radiative corrections in the MSSM may
also induce CP violation in Higgs-mass mixing, which can be probed via various
asymmetries measurable using polarized mu+mu- beams. In addition,
Higgs-chargino couplings may be probed at a second mu+mu- Higgs factory.Comment: Report of the Higgs factory working group of the ECFA-CERN study on
Neutrino Factory & Muon Storage Rings at CERN. 28 p
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
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