A
bstract
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,
E
T
miss
, is very low. Performing two-dimensional parameter scans and focusing on the hadronic
H
→
b
b
¯
decay giving a
b
b
¯
b
b
¯
+
E
T
miss
final state we explore the sensitivity of a current LHC general-purpose jets +
E
T
miss
analysis to such scenarios.
Supersymmetric dark matter after LHC run 1 Bagnaschi, E. A.; Buchmueller, O.; Cavanaugh, R. ...
The European physical journal. C, Particles and fields,
10/2015, Letnik:
75, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Different mechanisms operate in various regions of the MSSM parameter space to bring the relic density of the lightest neutralino,
χ
~
1
0
, assumed here to be the lightest SUSY particle (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 such as the lighter stau
τ
~
1
, stop
t
~
1
or chargino
χ
~
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
τ
~
1
coannihilation regions of the CMSSM, NUHM1, NUHM2 can largely be explored at the LHC via searches for
/
E
T
events and long-lived charged particles, whereas their
H
/
A
funnel, focus-point and
χ
~
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
χ
~
1
±
coannihilation: parts of its parameter space can be explored by the LHC, and a larger portion by future direct DM searches.
The CMSSM and NUHM1 after LHC Run 1 Buchmueller, O.; Cavanaugh, R.; Roeck, A. De ...
The European physical journal. C, Particles and fields,
2014/6, Letnik:
74, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We analyze the impact of data from the full Run 1 of the LHC at 7 and 8 TeV on the CMSSM with
μ
>
0
and
<
0
and the NUHM1 with
μ
>
0
, incorporating the constraints imposed by other experiments such ...as precision electroweak measurements, flavour measurements, the cosmological density of cold dark matter and the direct search for the scattering of dark matter particles in the LUX experiment. We use the following results from the LHC experiments: ATLAS searches for events with
E
/
T
accompanied by jets with the full 7 and 8 TeV data, the ATLAS and CMS measurements of the mass of the Higgs boson, the CMS searches for heavy neutral Higgs bosons and a combination of the LHCb and CMS measurements of
BR
(
B
s
→
μ
+
μ
-
)
and
BR
(
B
d
→
μ
+
μ
-
)
. Our results are based on samplings of the parameter spaces of the CMSSM for both
μ
>
0
and
μ
<
0
and of the NUHM1 for
μ
>
0
with 6.8
×
10
6
, 6.2
×
10
6
and 1.6
×
10
7
points, respectively, obtained using the MultiNest tool. The impact of the Higgs-mass constraint is assessed using FeynHiggs 2.10.0, which provides an improved prediction for the masses of the MSSM Higgs bosons in the region of heavy squark masses. It yields in general larger values of
M
h
than previous versions of FeynHiggs, reducing the pressure on the CMSSM and NUHM1. We find that the global
χ
2
functions for the supersymmetric models vary slowly over most of the parameter spaces allowed by the Higgs-mass and the
E
/
T
searches, with best-fit values that are comparable to the
χ
2
/
dof
for the best Standard Model fit. We provide 95 % CL lower limits on the masses of various sparticles and assess the prospects for observing them during Run 2 of the LHC.
The pMSSM10 after LHC run 1 de Vries, K. J.; Bagnaschi, E. A.; Buchmueller, O. ...
The European physical journal. C, Particles and fields,
09/2015, Letnik:
75, Številka:
9
Journal Article
Recenzirano
Odprti dostop
We present a frequentist analysis of the parameter space of the pMSSM10, in which the following ten soft SUSY-breaking parameters are specified independently at the mean scalar top mass scale
M
SUSY
...≡
m
t
~
1
m
t
~
2
: the gaugino masses
M
1
,
2
,
3
, the first-and second-generation squark masses
m
q
~
1
=
m
q
~
2
, the third-generation squark mass
m
q
~
3
, a common slepton mass
m
ℓ
~
and a common trilinear mixing parameter
A
, as well as the Higgs mixing parameter
μ
, the pseudoscalar Higgs mass
M
A
and
tan
β
, the ratio of the two Higgs vacuum expectation values. We use the MultiNest sampling algorithm with
∼
1.2
×
10
9
points to sample the pMSSM10 parameter space. A dedicated study shows that the sensitivities to strongly interacting sparticle masses of ATLAS and CMS searches for jets, leptons
+
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 electroweakly 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 of
BR
(
B
s
→
μ
+
μ
-
)
by LHCb and CMS, other
B
-physics observables, electroweak precision observables, the cold dark matter density and the XENON100 and LUX searches for spin-independent dark matter scattering, assuming that the cold dark matter is mainly provided by the lightest neutralino
χ
~
1
0
. We show that the pMSSM10 is able to provide a supersymmetric interpretation of
(
g
-
2
)
μ
, unlike the CMSSM, NUHM1 and NUHM2. As a result, we find (omitting Higgs rates) that the minimum
χ
2
=
20.5
with 18 degrees of freedom (d.o.f.) in the pMSSM10, corresponding to a
χ
2
probability of 30.8 %, to be compared with
χ
2
/
d
.
o
.
f
.
=
32.8
/
24
(
31.1
/
23
)
(
30.3
/
22
)
in the CMSSM (NUHM1) (NUHM2). We display the one-dimensional likelihood functions for sparticle masses, and we show that they may be significantly lighter in the pMSSM10 than in the other models, e.g., the gluino may be as light as
∼
1250
GeV
at the 68 % CL, and squarks, stops, electroweak gauginos and sleptons may be much lighter than in the CMSSM, NUHM1 and NUHM2. We discuss the discovery potential of future LHC runs,
e
+
e
-
colliders and direct detection experiments.
The NUHM2 after LHC Run 1 Buchmueller, O.; Cavanaugh, R.; Citron, M. ...
The European physical journal. C, Particles and fields,
2014/12, Letnik:
74, Številka:
12
Journal Article
Recenzirano
Odprti dostop
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,
m
H
u
,
d
2
, vary ...independently from the universal soft SUSY-breaking contributions
m
0
2
to the masses of squarks and sleptons. Our analysis uses the MultiNest sampling algorithm with over
4
×
10
8
points to sample the NUHM2 parameter space. It includes the ATLAS and CMS Higgs mass measurements as well as the ATLAS search for supersymmetric jets +
/
E
T
signals using the full LHC Run 1 data, the measurements of
BR
(
B
s
→
μ
+
μ
-
)
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 at the GUT scale for squarks and sleptons,
m
0
2
<
0
, as well as
m
H
u
2
<
m
H
d
2
<
0
. The tension present in the CMSSM and NUHM1 between the supersymmetric interpretation of
(
g
-
2
)
μ
and the absence to date of SUSY at the LHC is not significantly alleviated in the NUHM2. We find that the minimum
χ
2
=
32.5
with 21 degrees of freedom (dof) in the NUHM2, to be compared with
χ
2
/
dof
=
35.0
/
23
in the CMSSM, and
χ
2
/
dof
=
32.7
/
22
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.
On the basis of frequentist analyses of experimental constraints from electroweak precision data, (
g
−2)
μ
,
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
χ
2
likelihood functions for the masses of supersymmetric particles and Higgs bosons, as well as BR(
b
→
s
γ
), BR(
B
s
→
μ
+
μ
−
) and the spin-independent dark-matter scattering cross section,
σ
p
SI
. 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 favored over the focus-point region at about the 3-
σ
level, largely but not exclusively because of (
g
−2)
μ
. 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, though high-luminosity running would be needed to cover the regions allowed at the 3-
σ
levels. 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
β
) plane. In the CMSSM, the likelihood function for BR(
B
s
→
μ
+
μ
−
) is peaked close to the Standard Model value, but much larger values are possible in the NUHM1. We find that values of
σ
p
SI
>10
−10
pb are preferred in both the CMSSM and the NUHM1. We study the effects of dropping the (
g
−2)
μ
, BR(
b
→
s
γ
),
Ω
χ
h
2
and
M
h
constraints, demonstrating that they are not in tension with the other constraints.
We make frequentist analyses of the CMSSM, NUHM1, VCMSSM and mSUGRA parameter spaces taking into account all the public results of searches for supersymmetry using data from the 2010 LHC run and the ...XENON100 direct search for dark matter scattering. The LHC data set includes ATLAS and CMS searches for
events (with or without leptons) and for the heavier MSSM Higgs bosons, and the upper limit on BR(
B
s
→
μ
+
μ
−
) including data from LHCb as well as CDF and DØ. The absence of signals in the LHC data favours somewhat heavier mass spectra than in our previous analyses of the CMSSM, NUHM1 and VCMSSM, and somewhat smaller dark matter scattering cross sections, all close to or within the pre-LHC 68% CL ranges, but does not impact significantly the favoured regions of the mSUGRA parameter space. We also discuss the impact of the XENON100 constraint on spin-independent dark matter scattering, stressing the importance of taking into account the uncertainty in the
π
-nucleon
σ
term
Σ
πN
, which affects the spin-independent scattering matrix element, and we make predictions for spin-dependent dark matter scattering. Finally, we discuss briefly the potential impact of the updated predictions for sparticle masses in the CMSSM, NUHM1, VCMSSM and mSUGRA on future
e
+
e
−
colliders.
The CMS and ATLAS Collaborations have recently published the results of initial direct LHC searches for supersymmetry analyzing ∼35/pb of data taken at 7 TeV in the centre of mass. We incorporate ...these results into a frequentist analysis of the probable ranges of parameters of simple versions of the minimal supersymmetric extension of the Standard Model (MSSM), namely the constrained MSSM (CMSSM), a model with common non-universal Higgs masses (NUHM1), the very constrained MSSM (VCMSSM) and minimal supergravity (mSUGRA). We present updated predictions for the gluino mass,
, the light-Higgs boson mass,
M
h
, BR(
B
s
→
μ
+
μ
−
) and the spin-independent dark matter scattering cross section,
. The CMS and ATLAS data make inroads into the CMSSM, NUHM1 and VCMSSM (but not mSUGRA) parameter spaces, thereby strengthening previous lower limits on sparticle masses and upper limits on
in the CMSSM and VCMSSM. The favoured ranges of BR(
B
s
→
μ
+
μ
−
) in the CMSSM, VCMSSM and mSUGRA are close to the Standard Model, but considerably larger values of BR(
B
s
→
μ
+
μ
−
) are possible in the NUHM1. Applying the CMS and ATLAS constraints improves the consistency of the model predictions for
M
h
with the LEP exclusion limits.
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.
The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak ...unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package,
Gfitter
, allowing for flexible and efficient model testing in high-energy physics, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plug-ins, and a statistical analysis of the fit results using toy Monte Carlo techniques. The state-of-the-art electroweak Standard Model is fully implemented, as well as generic extensions to it. Theoretical uncertainties are explicitly included in the fit through scale parameters varying within given error ranges.
This paper introduces the Gfitter project, and presents state-of-the-art results for the global electroweak fit in the Standard Model (SM), and for a model with an extended Higgs sector (2HDM). Numerical and graphical results for fits with and without including the constraints from the direct Higgs searches at LEP and Tevatron are given. Perspectives for future colliders are analysed and discussed.
In the SM fit including the direct Higgs searches, we find
M
H
=116.4
−1.3
+18.3
GeV, and the 2
σ
and 3
σ
allowed regions 114,145 GeV and 113,168 and 180,225 GeV, respectively. For the strong coupling strength at fourth perturbative order we obtain
α
S
(
M
Z
2
)=0.1193
−0.0027
+0.0028
(exp )±0.0001 (theo). Finally, for the mass of the top quark, excluding the direct measurements, we find
m
t
=178.2
−4.2
+9.8
GeV. In the 2HDM we exclude a charged-Higgs mass below 240 GeV at 95% confidence level. This limit increases towards larger tan
β
, e.g.,
is excluded for tan
β
=70.
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