770 research outputs found
One-loop analysis of the interactions between charmed mesons and Goldstone bosons
We derive the scattering amplitude for Goldstone bosons of chiral symmetry
off the pseudoscalar charmed mesons up to leading one-loop order in a covariant
chiral effective field theory, using the so-called extended-on-mass-shell
renormalization scheme. Then we use unitarized chiral perturbation theory to
fit to the available lattice data of the S-wave scattering lengths. The lattice
data are well described. However, most of the low-energy constants determined
from the fit bear large uncertainties. Lattice simulations in more channels are
necessary to pin down these values which can then be used to make predictions
in other processes related by chiral and heavy quark symmetries.Comment: 34 pages, 7 figures, 7 tables, the final version to be published in
JHE
Study of open-charm states in unitarized chiral effective theory with one-loop potentials
Chiral potentials are derived for the interactions between Goldstone bosons
and pseudoscalar charmed mesons up to next-to-next-to-leading order in a
covariant chiral effective field theory with explicit vector charmed-meson
degrees of freedom. Using the extended-on-mass-shell scheme, we demonstrate
that the ultraviolet divergences and the so-called power counting breaking
terms can be properly absorbed by the low-energy constants of the chiral
Lagrangians. We calculate the scattering lengths by unitarizing the one-loop
potentials and fit them to the data extracted from lattice QCD. The obtained
results are compared to the ones without an explicit contribution of vector
charmed mesons given previously. It is found that the difference is negligible
for -wave scattering in the threshold region. This validates the use of
-less one-loop potentials in the study of the pertinent scattering
lengths. We search for dynamically generated open-charm states with
as poles of the -matrix on various Riemann sheets. The trajectories of those
poles for varying pion masses are presented as well.Comment: 25 pages, 6 figures and 5 table
Scalar form factors of semi-leptonic transitions with coupled-channel effects
Coupled-channel effects are taken into account for the study of scalar form
factors in semi-leptonic and decays, by solving the Muskhelishvili-Omn\`es
integral equations. As inputs, we employ the unitarized amplitudes taken from
chiral effective theory for the region not far away from thresholds, while, at
higher energies of the Goldstone bosons, proper asymptotic conditions are
employed. Within Muskhelishvili-Omn\`es formalism, the scalar form factors are
represented in terms of Omn\`es matrix multiplied by a vector of polynomials.
We reduce the number of subtraction constants by matching to the scalar form
factors derived in chiral perturbation theory up to next-to-leading order. The
recent lattice QCD data by ETM collaboration for and
scalar form factors are simultaneously well described. The
scalar form factors for , and
transitions are predicted in their whole kinematical regions. Using our fitting
parameters, we also extract the following Cabibbo-Kobayashi-Maskawa elements:
and
. The
approach used in this work can be straightforwardly extended to the
semileptonic decays.Comment: 7 pages, 3 figures, 3 tables. XVII International Conference on Hadron
Spectroscopy and Structure - Hadron2017, University of Salamanca, Salamanca,
Spai
Reconciling experimental and lattice data of in a - coupled-channel analysis
We study the and coupled-channel system within a
covariant framework. The and invariant-mass
distributions measured at 4.23~GeV and 4.26~GeV by BESIII and the finite-volume
energy levels from recent lattice QCD simulations are simultaneously fitted.
Phase shifts and inelasticities of the and scattering
are predicted using the resulting amplitudes. Poles corresponding to the
state are found in the complex energy plane and their couplings
with and are determined. Our results indicate that
the current lattice data do not preclude the existence of a physical
state.Comment: 22 pages, 4 figure
Towards a new paradigm for heavy-light meson spectroscopy
Since 2003 many new hadrons, including the lowest-lying positive-parity
charm-strange mesons and , were observed
that do not conform with quark model expectations. It was recently demonstrated
that various puzzles in the charm meson spectrum find a natural resolution, if
the SU(3) multiplets for the lightest scalar and axial-vector states, amongst
them the and the , owe their existence to
the nonperturbative dynamics of Goldstone-Boson scattering off and
mesons. Most importantly the ordering of the lightest strange and
nonstrange scalars becomes natural. In this work we demonstrate for the first
time that this mechanism is strongly supported by the recent high quality data
on the provided by the LHCb experiment. This implies
that the lowest quark-model positive-parity charm mesons, together with their
bottom counterparts, if realized in nature, do not form the ground-state
multiplet. This is similar to the pattern that has been established for the
scalar mesons made from light up, down and strange quarks, where the lowest
multiplet is considered to be made of states not described by the quark model.
In a broader view, the hadron spectrum must be viewed as more than a collection
of quark model states.Comment: 8 pages, 5 figures. Discussion significantly extended, suggestion for
lattice and more comparison with LHCb data added; version accepted for
publication in PR
Optical and Gamma-Ray Variability Behaviors of 3C 454.3 from 2006 to 2011
We present our photometric monitoring of a flat spectrum radio quasar (FSRQ)
3C 454.3 at Yunnan observatories from 2006 to 2011. We find that the optical
color of 3C 454.3 shows obvious redder-when-brighter trend, which reaches a
saturation stage when the source is brighter than 15.15 mag at V band. We
perform a simulation with multiple values of disk luminosity and spectral index
to reproduce the magnitude-color diagram. The results show that the
contamination caused by the disk radiation alone is difficult to produce the
observed color variability. The variability properties during the outburst in
December 2009 are also compared with -ray data derived from Fermi
-ray space telescope. The flux variation of these two bands follow a
linear relation with , which provides an
observational evidence for external Compton process in 3C 454.3. Meanwhile,
this flux correlation indicates that electron injection is the main mechanism
for variability origin. We also explore the variation of the flux ratio
and the detailed structures in the lightcurves, and discuss
some possible origins for the detailed variability behaviors.Comment: accepted for publication in The Astrophysical Journal, 5 figures, 2
table
Complete mitochondrial genome sequence and phylogenetic analysis of Procambarus clarkii and Cambaroides dauricus from China
To enhance the management and protection of crayfish genetic diversity and germplasm resources in Cambaroides dauricus (C. dauricus), a common species of Procambarus clarkii (P. clarkii) was used as a control group to compare the whole mitochondrial genome sequence using Illumina sequencing technology. This study found that the mitochondrial genome of C. dauricus is 15580 bp in length, with a base composition of A (31.84%), G (17.66%), C (9.42%), and T (41.08%) and a C + G content of 27.08%. The C + G in the D-loop is rich in 17.06%, indicating a significant preference. The mitochondrial genome of C. dauricus contains 13 protein-coding genes, 22 tRNA genes, and 2 rRNA genes, with most of the genes labeled in the negative direction, except for a few genes that are labeled in the positive direction. The start codons of the ten coding sequences are ATG, and the quintessential TAA and TAG are the stop codons. This study also found that the Ka/Ks ratios of most protein-coding genes in the mitochondria of both shrimps are lower than 1, indicating weak natural selection, except for nad 2, nad 5, and cox 1. The Ka/Ks ratio of cox 3 is the lowest (less than 0.1), indicating that this protein-coding gene bears strong natural selection pressure and functional constraint in the process of mitochondrial genetic evolution of both shrimps. Furthermore, we constructed phylogenetic analyses based on the entire sequence, which effectively distinguishes the high body from other shrimp species of the genus based on the mitochondrial genome. This study provides molecular genetic data for the diversity investigation and protection of fishery resources with Chinese characteristics and a scientific reference for the evolutionary study of Procambarus.This research was funded by the Natural Science Foundation of Heilongjiang Province
(NO. LH2023C058) and the Central Public-interest Scientific Institution Basal Research Fund, Chinese
Academy of Fishery Sciences (NO. 2020TD56)info:eu-repo/semantics/publishedVersio
Implications of C1q/TNF-related protein superfamily in patients with coronary artery disease.
The C1q complement/TNF-related protein superfamily (CTRPs) displays differential effects on the regulation of metabolic homeostasis, governing cardiovascular function. However, whether and how they may serve as predictor/pro-diagnosis factors for assessing the risks of coronary artery disease (CAD) remains controversial. Therefore, we performed a clinical study to elaborate on the implication of CTRPs (CTRP1, CTRP5, CTRP7, and CTRP15) in CAD. CTRP1 were significantly increased, whereas CTRP7 and CTRP15 levels were decreased in CAD patients compared to the non-CAD group. Significant differences in CTRP1 levels were discovered between the single- and triple-vascular-vessel lesion groups. ROC analysis revealed that CTRP7 and CTRP15 may serve as CAD markers, while CTRP1 may serve as a marker for the single-vessel lesion of CAD. CTRP1 and CTRP5 can serve as markers for the triple-vessel lesion. CTRP1 may serve as an independent risk predictor for triple-vessel lesion, whereas CTRP15 alteration may serve for a single-vessel lesion of CAD. CTRP1 may serve as a novel superior biomarker for diagnosis of severity of vessel-lesion of CAD patients. CTRP7, CTRP15 may serve as more suitable biomarker for the diagnosis of CAD patients, whereas CTRP5 may serve as an independent predictor for CAD. These findings suggest CTRPs may be the superior predictive factors for the vascular lesion of CAD and represent novel therapeutic targets against CAD
1,3-Dihydroxy-2-(hydroxymethyl)propan-2-aminium formate
The title compound, C4H12NO3
+·CHO2
−, was obtained from 1,3-dihydroxy-2-(hydroxymethyl)propan-2-aminium acetate and ethyl formate. In the crystal, the cations and anions are held together by intermolecular N—H⋯O and O—H⋯O hydrogen bonds
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