Update on the b → s anomalies Arbey, A.; Hurth, T.; Mahmoudi, F. ...
Physical review. D,
07/2019, Letnik:
100, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We present a brief update of our model-independent analyses of the b → s data presented in the articles published in Phys. Rev. D 96, 095034 (2017) and Phys. Rev. D 98, 095027 (2018) based on new ...data on RK by LHCb, on RK* by Belle, and on Bs,d → μ+μ− by ATLAS.
Recently the LHCb collaboration has confirmed the evidence for lepton flavour nonuniversality at the 3.1σ level via an updated measurement of RK. In this work we analyse this evidence within a ...model-independent approach. We make projections for future measurements which indicate that LHCb will be in the position to discover lepton nonuniversality with the Run 3 data in a single observable. We analyse other ratios based on our analysis of the present measurements of the ratios RK(⁎) and analyse if they are able to differentiate between various new physics options within the effective field theory at present or in the near future. We also compare the present deviations in the ratios with NP indications in the angular observables of exclusive b→sℓℓ transitions. Finally, we update our global analysis considering all b→sℓℓ observables altogether, including a 20-parameter fit in connection of a Wilks' test.
We use MasterCode to perform a frequentist analysis of the constraints on a phenomenological MSSM model with 11 parameters, the pMSSM11, including constraints from
∼
36
/fb of LHC data at 13 TeV and ...PICO, XENON1T and PandaX-II searches for dark matter scattering, as well as previous accelerator and astrophysical measurements, presenting fits both with and without the
(
g
-
2
)
μ
constraint. The pMSSM11 is specified by the following parameters: 3 gaugino masses
M
1
,
2
,
3
, a common mass for the first-and second-generation squarks
m
q
~
and a distinct third-generation squark mass
m
q
~
3
, a common mass for the first-and second-generation sleptons
m
ℓ
~
and a distinct third-generation slepton mass
m
τ
~
, a common trilinear mixing parameter
A
, the Higgs mixing parameter
μ
, the pseudoscalar Higgs mass
M
A
and
tan
β
. In the fit including
(
g
-
2
)
μ
, a Bino-like
χ
~
1
0
is preferred, whereas a Higgsino-like
χ
~
1
0
is mildly favoured when the
(
g
-
2
)
μ
constraint is dropped. We identify the mechanisms that operate in different regions of the pMSSM11 parameter space to bring the relic density of the lightest neutralino,
χ
~
1
0
, into the range indicated by cosmological data. In the fit including
(
g
-
2
)
μ
, coannihilations with
χ
~
2
0
and the Wino-like
χ
~
1
±
or with nearly-degenerate first- and second-generation sleptons are active, whereas coannihilations with the
χ
~
2
0
and the Higgsino-like
χ
~
1
±
or with first- and second-generation squarks may be important when the
(
g
-
2
)
μ
constraint is dropped. In the two cases, we present
χ
2
functions in two-dimensional mass planes as well as their one-dimensional profile projections and best-fit spectra. Prospects remain for discovering strongly-interacting sparticles at the LHC, in both the scenarios with and without the
(
g
-
2
)
μ
constraint, as well as for discovering electroweakly-interacting sparticles at a future linear
e
+
e
-
collider such as the ILC or CLIC.
The CMSSM and NUHM1 after LHC Run 1 Buchmueller, O.; Cavanaugh, R.; Roeck, A. De ...
The European physical journal. C, Particles and fields,
06/2014, 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.
Likelihood analysis of the minimal AMSB model Bagnaschi, E.; Borsato, M.; Sakurai, K. ...
The European physical journal. C, Particles and fields,
04/2017, Letnik:
77, Številka:
4
Journal Article
Recenzirano
Odprti dostop
We perform a likelihood analysis of the minimal anomaly-mediated supersymmetry-breaking (mAMSB) model using constraints from cosmology and accelerator experiments. We find that either a wino-like or ...a Higgsino-like neutralino LSP,
χ
~
1
0
, may provide the cold dark matter (DM), both with similar likelihoods. The upper limit on the DM density from Planck and other experiments enforces
m
χ
~
1
0
≲
3
TeV
after the inclusion of Sommerfeld enhancement in its annihilations. If most of the cold DM density is provided by the
χ
~
1
0
, the measured value of the Higgs mass favours a limited range of
tan
β
∼
5
(and also for
tan
β
∼
45
if
μ
>
0
) but the scalar mass
m
0
is poorly constrained. In the wino-LSP case,
m
3
/
2
is constrained to about
900
TeV
and
m
χ
~
1
0
to
2.9
±
0.1
TeV
, whereas in the Higgsino-LSP case
m
3
/
2
has just a lower limit
≳
650
TeV
(
≳
480
TeV
) and
m
χ
~
1
0
is constrained to
1.12
(
1.13
)
±
0.02
TeV
in the
μ
>
0
(
μ
<
0
) scenario. In neither case can the anomalous magnetic moment of the muon,
(
g
-
2
)
μ
, be improved significantly relative to its Standard Model (SM) value, nor do flavour measurements constrain the model significantly, and there are poor prospects for discovering supersymmetric particles at the LHC, though there are some prospects for direct DM detection. On the other hand, if the
χ
~
1
0
contributes only a fraction of the cold DM density, future LHC
-based searches for gluinos, squarks and heavier chargino and neutralino states as well as disappearing track searches in the wino-like LSP region will be relevant, and interference effects enable
BR
(
B
s
,
d
→
μ
+
μ
-
)
to agree with the data better than in the SM in the case of wino-like DM with
μ
>
0
.
A
bstract
This report details the capabilities of LHCb and its upgrades towards the study of kaons and hyperons. The analyses performed so far are reviewed, elaborating on the prospects for some key ...decay channels, while proposing some new measurements in LHCb to expand its strangeness research program.
We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale
M
in
below the ...supersymmetric grand unification scale
M
GUT
, as can occur in mirage mediation and other models. In addition to
M
in
, such ‘sub-GUT’ models have the 4 parameters of the CMSSM, namely a common gaugino mass
m
1
/
2
, a common soft supersymmetry-breaking scalar mass
m
0
, a common trilinear mixing parameter
A
and the ratio of MSSM Higgs vevs
tan
β
, assuming that the Higgs mixing parameter
μ
>
0
. We take into account constraints on strongly- and electroweakly-interacting sparticles from
∼
36
/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for
M
in
∼
10
5
to
10
9
GeV
, with
M
in
∼
M
GUT
disfavoured by
Δ
χ
2
∼
3
due to the
BR
(
B
s
,
d
→
μ
+
μ
-
)
constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with
m
χ
~
1
0
∼
1
TeV
, with annihilation via heavy Higgs bosons
H
/
A
and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the
(
g
-
2
)
μ
constraint, finding similar results whether or not it is included.
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.
Higgs and supersymmetry Buchmueller, O.; Cavanaugh, R.; De Roeck, A. ...
The European physical journal. C, Particles and fields,
06/2012, Letnik:
72, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Global frequentist fits to the CMSSM and NUHM1 using the MasterCode framework predicted
M
h
≃119 GeV in fits incorporating the (
g
−2)
μ
constraint and ≃126 GeV without it. Recent results by ATLAS ...and CMS could be compatible with a Standard Model-like Higgs boson around
M
h
≃125 GeV. We use the previous MasterCode analysis to calculate the likelihood for a measurement of any nominal Higgs mass within the range of 115 to 130 GeV. Assuming a Higgs mass measurement at
M
h
≃125 GeV, we display updated global likelihood contours in the (
m
0
,
m
1/2
) and other parameter planes of the CMSSM and NUHM1, and present updated likelihood functions for
, BR(
B
s
→
μ
+
μ
−
) and the spin-independent dark matter cross section
. The implications of dropping (
g
−2)
μ
from the fits are also discussed. We furthermore comment on a hypothetical measurement of
M
h
≃119 GeV.
Supersymmetry in light of 1/fb of LHC data Buchmueller, O.; Cavanaugh, R.; De Roeck, A. ...
The European physical journal. C, Particles and fields,
02/2012, Letnik:
72, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We update previous frequentist analyses of the CMSSM and NUHM1 parameter spaces to include the public results of searches for supersymmetric signals using ∼1/fb of LHC data recorded by ATLAS and CMS ...and ∼0.3/fb of data recorded by LHCb in addition to electroweak precision and B-physics observables. We also include the constraints imposed by the cosmological dark matter density and the XENON100 search for spin-independent dark matter scattering. The LHC data set includes ATLAS and CMS searches for jets +
events and for the heavier MSSM Higgs bosons, and the upper limits on BR(
B
s
→
μ
+
μ
−
) from LHCb and CMS. The absences of jets +
signals in the LHC data favour heavier mass spectra than in our previous analyses of the CMSSM and NUHM1, which may be reconciled with (
g
−2)
μ
if tan
β
∼40, a possibility that is, however, under pressure from heavy Higgs searches and the upper limits on BR(
B
s
→
μ
+
μ
−
). As a result, the
p
-value for the CMSSM fit is reduced to ∼15(38)%, and that for the NUHM1 to ∼16(38)%, to be compared with ∼9(49)% for the Standard Model limit of the CMSSM for the same set of observables (dropping (
g
−2)
μ
), ignoring the dark matter relic density. We discuss the sensitivities of the fits to the (
g
−2)
μ
and BR(
b
→
sγ
) constraints, contrasting fits with and without the (
g
−2)
μ
constraint, and combining the theoretical and experimental errors for BR(
b
→
sγ
) linearly or in quadrature. We present predictions for
, BR(
B
s
→
μ
+
μ
−
),
M
h
and
M
A
, and update predictions for spin-independent dark matter scattering, incorporating the uncertainty in the
π
-nucleon
σ
term
Σ
πN
. Finally, we present predictions based on our fits for the likely thresholds for sparticle pair production in
e
+
e
−
collisions in the CMSSM and NUHM1.
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