1,120 research outputs found
Heavy Pseudoscalar Twist-3 Distribution Amplitudes within QCD Theory in Background Fields
In this paper, we study the properties of the twist-3 distribution amplitude
(DA) of the heavy pseudo-scalars such as , and . New sum
rules for the twist-3 DA moments \left_{\rm HP} and
\left_{\rm HP} up to sixth orders and up to dimension-six
condensates are deduced under the framework of the background field theory.
Based on the sum rules for the twist-3 DA moments, we construct a new model for
the two twist-3 DAs of the heavy pseudo-scalar with the help of the
Brodsky-Huang-Lepage prescription. Furthermore, we apply them to the
transition form factor () within the
light-cone sum rules approach, and the results are comparable with other
approaches. It has been found that the twist-3 DAs and
are important for a reliable prediction of
. For example, at the maximum recoil region, we have
, in which those two twist-3 terms
provide and contributions. Also we calculate the
branching ratio of the semi-leptonic decay as .Comment: 12 pages, 16 figure
Crystal structure of 3-methyl-2,3-dihydro-2-thioxoquinazolin-4(1H)-one, C9H8N2OS
Abstract
C9H8N2OS, monoclinic, C2/c (no. 15), a = 24.273(5) Å, b = 9.026(2) Å, c = 8.2852(19) Å, β = 108.818(4)°, V = 1718.2(7) Å3, Z = 8, R
gt(F) = 0.0438, wR
ref(F
2) = 0.1190, T = 296(2) K
Fermionic symmetry-protected topological state in strained graphene
The low-energy physics of graphene is described by relativistic Dirac
fermions with spin and valley degrees of freedom. Mechanical strain can be used
to create a pseudo magnetic field pointing to opposite directions in the two
valleys. We study interacting electrons in graphene exposed to both an external
real magnetic field and a strain-induced pseudo magnetic field. For a certain
ratio between these two fields, it is proposed that a fermionic
symmetry-protected topological state can be realized. The state is
characterized in detail using model wave functions, Chern-Simons field theory,
and numerical calculations. Our paper suggests that graphene with artificial
gauge fields may host a rich set of topological states.Comment: 8 pages, 4 figure
Revisiting the Pion Leading-Twist Distribution Amplitude within the QCD Background Field Theory
We study the pion leading-twist distribution amplitude (DA) within the
framework of SVZ sum rules under the background field theory. To improve the
accuracy of the sum rules, we expand both the quark propagator and the vertex
(z\cdot \tensor{D})^n of the correlator up to dimension-six operators in the
background field theory. The sum rules for the pion DA moments are obtained, in
which all condensates up to dimension-six have been taken into consideration.
Using the sum rules, we obtain \left|_{\rm 1\;GeV} = 0.338 \pm
0.032, \left|_{\rm 1\;GeV} = 0.211 \pm 0.030 and
\left|_{\rm 1\;GeV} = 0.163 \pm 0.030. It is shown that the
dimension-six condensates shall provide sizable contributions to the pion DA
moments. We show that the first Gegenbauer moment of the pion leading-twist DA
is , which is consistent with those
obtained in the literature within errors but prefers a larger central value as
indicated by lattice QCD predictions.Comment: 13 pages, 7 figure
Like-sign Di-lepton Signals in Higgsless Models at the LHC
We study the potential LHC discovery of the Z1 KK gauge boson unitarizing
longitudinal W+W- scattering amplitude. In particular, we explore the decay
mode Z1->t tbar along with Z1-> W+W- without specifying the branching
fractions. We propose to exploit the associated production pp-> W Z1, and
select the final state of like-sign dileptons plus multijets and large missing
energy. We conclude that it is possible to observe the Z1 resonance at a 5
sigma level with an integrated luminosity of 100 inverse fb at the LHC upto 650
GeV for a dominant WW channel, and 560 GeV for a dominant ttbar channel.Comment: 13 pages, 7 figure
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