49 research outputs found
Phenomenology of flavorful composite vector bosons in light of anomalies
We analyze the flavor structure of composite vector bosons arising in a model
of vectorlike technicolor, often called hypercolor (HC), with eight flavors
that form a one-family content of HC fermions. Dynamics of the composite vector
bosons, referred to as HC rho in this paper, are formulated together with HC
pions by the hidden local symmetry (HLS), in a way analogous to QCD vector
mesons. Then coupling properties to the standard model (SM) fermions, which
respect the HLS gauge symmetry, are described in a way that couplings of the HC
rhos to the left-handed SM quarks and leptons are given by a well-defined setup
as taking the flavor mixing structures into account. Under the present
scenario, we discuss significant bounds on the model from electroweak precision
tests, flavor physics, and collider physics. We also try to address B anomalies
in processes such as B -> K(*) mu+ mu- and B -> D(*) tau nu, recently reported
by LHCb, Belle, (ATLAS, and CMS in part.) Then we find that the present model
can account for the anomaly in B -> K(*) mu+ mu- consistently with the other
constraints while it predicts no significant deviations in B -> D(*) tau nu
from the SM, which can be examined in the future Belle II experiment. The
former is archived with the form C9 = -C10 of the Wilson coefficients for
effective operators of b -> s mu+ mu-, which has been favored by the recent
experimental data. We also investigate current and future experimental limits
at the Large Hadron Collider (LHC) and see that possible collider signals come
from dijet and ditau, or dimuon resonant searches for the present scenario with
TeV mass range. To conclude, the present b -> s mu+ mu- anomaly is likely to
imply discovery of new vector bosons in the ditau or dimuon channel in the
context of the HC rho model. Our model can be considered as a UV completion of
conventional U(1)' model.Comment: 62 pages, 8 figures, 3 tables, typos modified, published versio
Constraint on Universal Extra Dimensions from scalar boson searches
We show the bounds on five- and six-dimensional Universal Extra Dimension
models from the result of the Higgs boson searches at the Large Hadron Collider
and electroweak precision measurement. The latest data released by the ATLAS
and the CMS gives the lower bounds on Kaluza-Klein scale which are from 650 GeV
to 1350 GeV depending on models from Higgs to diboson/diphoton decay signal.
The Higgs production cross section can be enhanced by factor 1.5 in crude
estimation, diphoton decay signal is suppressed about 10%. Electroweak
precision measurement also gives the lower bounds as from 700 GeV to 1500 GeV.Comment: 4 pages, 1 figure, 1 table, Proceedings of the conference "Rencontres
de Moriond EW 2013", La Thuile, Italy, 2-9 Mar. 201
Tau longitudinal polarization in B -> D tau nu and its role in the search for charged Higgs boson
We study the longitudinal polarization of the tau lepton in B -> D tau nu
decay. After discussing possible sensitivities of tau decay modes to the tau
polarization, we examine the effect of charged Higgs boson on the tau
polarization in B -> D tau nu. We find a relation between the decay rate and
the tau polarization, and clarify the role of the tau polarization measurement
in the search for the charged Higgs boson.Comment: 17 pages, 3 figures. Tau -> l nu nu is included in Sec. II.
Accordingly the title is changed. References are adde
Universal extra dimensions after Higgs discovery
We show bounds on five- and six-dimensional universal extra dimension (UED)
models from the latest results of the Higgs searches at the LHC and from the
electroweak precision data for the S and T parameters. We consider the minimal
UED model in five dimensions and the ones in six dimensions. The highest
possible ultraviolet cutoff scale for each UED model is evaluated from the
electroweak vacuum stability by solving the renormalization group equation of
the Higgs self-coupling. This scale turns out to be lower than the conventional
one obtained from the perturbativity of the gauge coupling. The resultant 95%
C.L. lower bounds on the first Kaluza-Klein scale from the LHC results and from
the S, T analysis are 600 and 700 GeV in the minimal UED model, while those in
the six-dimensional UED models are 800-1300 GeV and 900-1500 GeV, respectively.Comment: 37 pages, 9 figures, 7 tables (v1); 38 pages, 9 figures, 7 tables,
with minor modifications, typos fixed, references added (v2); 37 pages, 10
figures, 7 tables, published version in PRD, figures modified, a figure
added, typos fixed, a reference added (v3
Global fit to anomalies 2022 mid-autumn
Recently, the LHCb collaboration announced a preliminary result of the test
of lepton flavor universality (LFU) in semi-leptonic decays:
and based on the LHC Run 1 data. This is the first result of
for the LHCb experiment, and its precision is comparable to the other
-factory data. Interestingly, those data prefer the violation of the LFU
again. A new world average of the data from the BaBar, Belle, and LHCb
collaborations is and . Including this new data, we update a circumstance of the measurements and their implications for new physics.
Incorporating recent developments for the form factors in
the Standard Model (SM), we observe a deviation from the SM
predictions. Our updates also include; model-independent new physics (NP)
formulae for the related observables; and the global fittings of parameters for
leptoquark scenarios as well as single NP operator scenarios. Furthermore, we
show future potential to indirectly distinguish different new physics scenarios
with the use of the precise measurements of the polarization observables in
at the Belle II and the high-
flavored-tail searches at the LHC. We also discuss an impact on the LFU
violation in .Comment: 38 pages, 5 figures, 6 Tables; v2: references adde