Motivated by future gravitational waves observations, we perform forecasts analysis to constrain a possible time variation of the fine structure constant (α) within the context of the so-called ...runaway dilaton model. For this purpose, some gravitational-wave standard sirens mock data within the perspective of Einstein Telescope and LISA mission were considered jointly with current strong gravitational lensing systems observations. We find that future standard sirens observations can also play an important role in the search for possible variations of α within the methodology presented in this work.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
We consider extensions of the standard model (SM) with neutral scalars in multiplets of
SU
(2) larger than doublets. When those scalars acquire vacuum expectation values, the resulting ...masses of the gauge bosons
W
±
and
Z
0
are not related by
m
W
=
m
Z
cos
θ
W
. In those extensions of the SM the oblique parameters
S
and
U
, when computed at the one-loop level, turn out to be either gauge-dependent or divergent. We show that one may eliminate this problem by modifying the Feynman rules of the SM for some vertices containing the Higgs boson; the modifying factors are equal to 1 in the limit
m
W
=
m
Z
cos
θ
W
. We give the result for
S
in a model with arbitrary numbers of scalar
SU
(2) triplets with weak hypercharges either 0 or 1.
We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target ...reduced the background in the (1, 30) keV search region to (15.8±1.3) events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
A search for leptoquarks produced singly and in pairs in proton-proton collisions is presented. We consider the leptoquark (LQ) to be a scalar particle of charge −1/3e coupling to a top quark plus a ...tau lepton (tτ) or a bottom quark plus a neutrino (bν), or a vector particle of charge +2/3e, coupling to tν or bτ. These choices are motivated by models that can explain a series of anomalies observed in the measurement of B meson decays. In this analysis the signatures tτνb and tτν are probed, using data recorded by the CMS experiment at the CERN LHC at s=13 TeV and that correspond to an integrated luminosity of 137 fb−1. These signatures have not been previously explored in a dedicated search. The data are found to be in agreement with the standard model prediction. Lower limits at 95% confidence level are set on the LQ mass in the range 0.98–1.73 TeV, depending on the LQ spin and its coupling λ to a lepton and a quark, and assuming equal couplings for the two LQ decay modes considered. These are the most stringent constraints to date on the existence of leptoquarks in this scenario.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Recent deviations from the standard model (SM) predictions of the experimental results on the
R
D
(
*
)
of the
b
→
c
l
ν
̄
l
semileptonic decay suggest the intervention of new physics (NP) ...mechanisms, which would affect the decay. Motivated by this, we investigate the possible NP effects on
Ξ
b
→
Ξ
c
τ
ν
̄
τ
and
Ω
b
→
Ω
c
τ
ν
̄
τ
processes in some NP models, such as the vector leptoquark (LQ) model,
W
′ model, aligned two-Higgs-doublet model and supersymmetry without
R
-parity model. Using the NP coupling parameter values obtained from different observables, we calculate various observables, such as the differential decay rate
d
B
/
d
q
2
, the forward–backward asymmetry
A
FB
l
(
q
2
)
, the polarization fraction of final-state lepton and daughter baryon
P
L
l
(
q
2
)
as well as
P
L
Ξ
c
(
Ω
c
)
(
q
2
)
, and the convexity parameter
C
F
l
(
q
2
)
in the SM and NP models. It is found that the SM predictions are consistent with those of previous works. In addition, the differential decay rate
d
B
/
d
q
2
is quite sensitive to the contributions of some NP models. NP predictions generally show large deviations from the corresponding SM predictions. Nevertheless, the NP effects on some observables in the
W
′ model and LQ model are not sensitive, and these observables show the same variation tendency in the two NP models as in the SM.
Dark matter represents currently an outstanding problem in both cosmology and particle physics. In this review we discuss the possible explanations for dark matter and the experimental observables ...which can eventually lead to the discovery of dark matter and its nature, and demonstrate the close interplay between the cosmological properties of the early Universe and the observables used to constrain dark matter models in the context of new physics beyond the Standard Model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The status of tests of the standard electroweak model and of searches for new physics in allowed nuclear β decay and neutron decay is reviewed including both theoretical and experimental ...developments. The sensitivity and complementarity of recent and ongoing experiments are discussed with emphasis on their potential to look for new physics. Measurements are interpreted using a model-independent effective field theory approach enabling to recast the outcome of the analysis in many specific new physics models. Special attention is given to the connection that this approach establishes with high-energy physics. A new global fit of available β-decay data is performed incorporating, for the first time in a consistent way, superallowed 0+→0+ transitions, neutron decay and nuclear decays. The constraints on exotic scalar and tensor couplings involving left- or right-handed neutrinos are determined while a constraint on the pseudoscalar coupling from neutron decay data is obtained for the first time as well. The values of the vector and axial–vector couplings, which are associated within the standard model to Vud and gA respectively, are also updated. The ratio between the axial and vector couplings obtained from the fit under standard model assumptions is CA∕CV=−1.27510(66). The relevance of the various experimental inputs and error sources is critically discussed and the impact of ongoing measurements is studied. The complementarity of the obtained bounds with other low- and high-energy probes is presented including ongoing searches at the Large Hadron Collider.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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