4,748 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
Anisotropic Dielectric Breakdown Strength of Single Crystal Hexagonal Boron Nitride
Dielectric breakdown has historically been of great interest from the
perspectives of fundamental physics and electrical reliability. However, to
date, the anisotropy in the dielectric breakdown has not been discussed. Here,
we report an anisotropic dielectric breakdown strength (EBD) for h-BN, which is
used as an ideal substrate for two-dimensional (2D) material devices. Under a
well-controlled relative humidity, EBD values in the directions both normal and
parallel to the c axis (EBD+c & EBD//c) were measured to be 3 and 12 MV/cm,
respectively. When the crystal structure is changed from sp3 of cubic-BN (c-BN)
to sp2 of h-BN, EBD+c for h-BN becomes smaller than that for c-BN, while EBD//c
for h-BN drastically increases. Therefore, h-BN can possess a relatively high
EBD concentrated only in the direction parallel to the c axis by conceding a
weak bonding direction in the highly anisotropic crystal structure. This
explains why the EBD//c for h-BN is higher than that for diamond. Moreover, the
presented EBD value obtained from the high quality bulk h-BN crystal can be
regarded as the standard for qualifying the crystallinity of h-BN layers grown
via chemical vapor deposition for future electronic applications
Microscopic Study of Nuclear "Pasta" by Quantum Molecular Dynamics
Structure of cold dense stellar matter at subnuclear densities is
investigated with quantum molecular dynamics (QMD). We succeeded in showing
that the phases with slab-like and rod-like nuclei etc. can be formed
dynamically without any assumptions on the nuclear shape. Our result suggests
the existence of these kinds of phases in neutron star crusts.Comment: to appear in Proceedings of YKIS01 "Physics of Unstable Nuclei",
Kyoto, December, 2001 (supplement volume of Prog. Theor. Phys.
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