4,600 research outputs found
Quantum Geometric Tensor in -Symmetric Quantum Mechanics
A series of geometric concepts are formulated for -symmetric
quantum mechanics and they are further unified into one entity, i.e., an
extended quantum geometric tensor (QGT). The imaginary part of the extended QGT
gives a Berry curvature whereas the real part induces a metric tensor on
system's parameter manifold. This results in a unified conceptual framework to
understand and explore physical properties of -symmetric systems
from a geometric perspective. To illustrate the usefulness of the extended QGT,
we show how its real part, i.e., the metric tensor, can be exploited as a tool
to detect quantum phase transitions as well as spontaneous
-symmetry breaking in -symmetric systems.Comment: main text of 5 pages, plus supplementary material of 8 page
Analytic decay width of the Higgs boson to massive bottom quarks at next-to-next-to-leading order in QCD
The Higgs boson decay to a massive bottom quark pair provides the dominant
contribution to the Higgs boson width. We present an exact result for such a
decay induced by the bottom quark Yukawa coupling with next-to-next-to-leading
order (NNLO) QCD corrections. We have adopted the canonical differential
equations in the calculation and obtained the result in terms of multiple
polylogarithms. We also compute the contribution from the decay to four bottom
quarks which consist of complete elliptic integrals or their one-fold
integrals. The small bottom quark mass limit coincides with the previous
calculation using the large momentum expansion. The threshold expansion
exhibits power divergent terms in the bottom quark velocity, which has a
structure different from that in but can be reproduced by
computing the corresponding Coulomb Green function. The NNLO corrections
significantly reduce the uncertainties from both the renormalization scale and
the renormalization scheme of the bottom quark Yukawa coupling. Our result can
be applied to a heavy scalar decay to a top quark pair.Comment: 29 pages, 11 figure
Giant negative magnetoresistance induced by the chiral anomaly in individual Cd3As2 nanowires
Cd3As2 is a newly booming Dirac semimetal with linear dispersion along all
three momentum directions and can be viewed as 3D analog of graphene. As
breaking of either time reversal symmetry or spatial inversion symmetry, the
Dirac semimetal is believed to transform into Weyl semimetal with exotic chiral
anomaly effect, while the experimental evidence of the chiral anomaly is still
missing in Cd3As2. Here we report the magneto-transport properties of
individual Cd3As2 nanowires. Large negative magnetoresistance (MR) with
magnitude of -63% at 60 K and -11% at 300 K are observed when the magnetic
field is parallel with the electric field direction, giving the evidence of the
chiral magnetic effect in Cd3As2 nanowires. In addition, the critical magnetic
field BC, where there is an extremum of the negative MR, increases with
increasing temperature. As the first observation of chiral anomaly induced
negative MR in Cd3As2 nanowires, it may offer valuable insights for low
dimensional physics in Dirac semimetals.Comment: 4 figure
A model for the primary school students’ mathematical modeling competency: a grounded theory analysis
Multiple positive solutions for functional dynamic equations on time scales
AbstractIn this paper, we study the following functional dynamic equation on time scales: {[Φ(uΔ(t))]∇+a(t)f(u(t),u(μ(t)))=0,t∈(0,T)T,u(t)=φ(t),t∈[−r,0)T,u(0)−B0(uΔ(0))=0,uΔ(T)=0, where Φ:R→R is an increasing homeomorphism and a positive homomorphism and Φ(0)=0. By using the well-known Leggett–Williams fixed point theorem, existence criteria for multiple positive solutions are established. An example is also given to illustrate the main results
A -ray Quasi-Periodic modulation in the Blazar PKS 0301243?
We report a nominally high-confidence -ray quasi-periodic modulation
in the blazar PKS 0301243. For this target, we analyze its \emph{Fermi}-LAT
Pass 8 data covering from 2008 August to 2017 May. Two techniques, i.e., the
maximum likelihood optimization and the exposure-weighted aperture photometry,
are used to build the -ray light curves. Then both the Lomb-Scargle
Periodogram and the Weighted Wavelet Z-transform are applied to the light
curves to search for period signals. A quasi-periodicity with a period of
yr appears at the significance level of , although it
should be noted that this putative quasi-period variability is seen in a data
set barely four times longer. We speculate that this -ray
quasi-periodic modulation might be evidence of a binary supermassive black
hole.Comment: 9 pages, 8 figures; Accepted for publication in Ap
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