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.
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.
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.
The LHCb measurements of certain ratios of decay modes testing lepton flavor nonuniversality might open an exciting world of new physics beyond the standard model. The latest LHCb measurements of RK* ...offer some new insight beyond the previous measurement of RK. We work out the present significance for nonuniversality, and argue that claims of 5σ deviations from the standard model based on all present b→sℓ+ℓ− data including the ratios are misleading and are at present still based on guesstimates of hadronic power corrections in the b→sℓ+ℓ− angular observables. We demonstrate that only a small part of the luminosity of 50 fb−1 foreseen to be accumulated by the LHCb will be needed to offer soon a definite answer to the present question of whether we see a very small glimpse of lepton flavor nonuniversal new physics or not. We also present new predictions for other ratios based on our analysis of the present measurements of the ratios RK(*) and analyze if they are able to differentiate between various new physics options within the effective field theory at present or in the near future.
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.
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.
A
bstract
The well-known problem of the unknown power corrections within QCD improved factorisation leaves the interpretation of the so-called LHCb anomalies in the angular observables of
B
→
K
∗
μ
+
...μ
−
as an open problem. In order to contribute to the question whether they represent a first sign for new physics beyond the Standard Model or a consequence of underestimated hadronic power corrections, we present a direct comparison of two global fits to the data based on the two different assumptions. In addition, we summarise the possible options to resolve this puzzle in the future.
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.
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
.
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