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.
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.
Likelihood analysis of supersymmetric SU(5) GUTs Bagnaschi, E.; Costa, J. C.; Sakurai, K. ...
The European physical journal. C, Particles and fields,
2017/2, Letnik:
77, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We perform a likelihood analysis of the constraints from accelerator experiments and astrophysical observations on supersymmetric (SUSY) models with SU(5) boundary conditions on soft SUSY-breaking ...parameters at the GUT scale. The parameter space of the models studied has seven parameters: a universal gaugino mass
m
1
/
2
, distinct masses for the scalar partners of matter fermions in five- and ten-dimensional representations of SU(5),
m
5
and
m
10
, and for the
5
and
5
¯
Higgs representations
m
H
u
and
m
H
d
, a universal trilinear soft SUSY-breaking parameter
A
0
, and the ratio of Higgs vevs
tan
β
. In addition to previous constraints from direct sparticle searches, low-energy and flavour observables, we incorporate constraints based on preliminary results from 13 TeV LHC searches for jets +
events and long-lived particles, as well as the latest PandaX-II and LUX searches for direct Dark Matter detection. In addition to previously identified mechanisms for bringing the supersymmetric relic density into the range allowed by cosmology, we identify a novel
u
~
R
/
c
~
R
-
χ
~
1
0
coannihilation mechanism that appears in the supersymmetric SU(5) GUT model and discuss the role of
ν
~
τ
coannihilation. We find complementarity between the prospects for direct Dark Matter detection and SUSY searches at the LHC.
We report the analysis of the three-body e^{+}e^{-}→BBover ¯π^{±}, BBover ¯^{*}π^{±}, and B^{*}Bover ¯^{*}π^{±} processes, including the first observations of the Z_{b}^{±}(10610)→BBover ...¯^{*}+c.c.^{±} and Z_{b}^{±}(10650)→B^{*}Bover ¯^{*}^{±} transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ(e^{+}e^{-}→BBover ¯^{*}+c.c.^{±}π^{∓})=17.4±1.6(stat)±1.9(syst) pb and σ(e^{+}e^{-}→B^{*}Bover ¯^{*}^{±}π^{∓})=8.75±1.15(stat)±1.04(syst) pb and set a 90% C.L. upper limit of σ(e^{+}e^{-}→BBover ¯^{±}π^{∓})<2.9 pb. The results are based on a 121.4 fb^{-1} data sample collected with the Belle detector at a center-of-mass energy near the ϒ(10860) peak.
We report the results of a high-statistics search for H dibaryon production in inclusive Υ(1S) and Υ(2S) decays. No indication of an H dibaryon with a mass near the M(H)=2m(Λ) threshold is seen in ...either the H→Λpπ(-) or ΛΛ decay channels and 90% confidence level branching-fraction upper limits are set that are between one and two orders of magnitude below the measured branching fractions for inclusive Υ(1S) and Υ(2S) decays to antideuterons. Since Υ(1S,2S) decays produce flavor-SU(3)-symmetric final states, these results put stringent constraints on H dibaryon properties. The results are based on analyses of 102 million Υ(1S) and 158 million Υ(2S) events collected with the Belle detector at the KEKB e(+)e(-) collider.
We report measurements of B→χ(c1)γK and χ(c2)γK decays using 772×10(6) BBover ¯ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. ...Evidence of a new resonance in the χ(c1)γ final state is found with a statistical significance of 3.8σ. This state has a mass of 3823.1±1.8(stat)±0.7(syst) MeV/c(2), a value that is consistent with theoretical expectations for the previously unseen 1(3)D(2) ccover ¯ meson. We find no other narrow resonance and set upper limits on the branching fractions of the X(3872)→χ(c1)γ and χ(c2)γ decays.
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