16,436 research outputs found
Establishing low-lying doubly charmed baryons
We systematically study the -wave doubly charmed baryons using the method
of QCD sum rules. Our results suggest that the recently
observed by LHCb can be well identified as the -wave state of
. We study its relevant state, whose mass is
predicted to be around 3.7 GeV. We also systematically study the -wave
doubly charmed baryons, whose masses are predicted to be around 4.1 GeV.
Especially, there can be several excited doubly charmed baryons in this energy
region, and we suggest to search for them in order to study the fine structure
of the strong interaction.Comment: 6 pages, 2 figures, 1 table; A mistake was found when evaluating
decay constants of the S-wave charmed baryons. The conclusion is not change
Rapid Invasion of Spartina Alterniflora in the Coastal Zone of Mainland China: Spatiotemporal Patterns and Human Prevention
Given the extensive spread and ecological consequences of exotic Spartina alterniflora (S. alterniflora) over the coast of mainland China, monitoring its spatiotemporal invasion patterns is important for the sake of coastal ecosystem management and ecological security. In this study, Landsat series images from 1990 to 2015 were used to establish multi-temporal datasets for documenting the temporal dynamics of S. alterniflora invasion. Our observations revealed that S. alterniflora had a continuous expansion with the area increasing by 50,204 ha during the considered 25 years. The largest expansion was identified in Jiangsu Province during the period of 1990-2000, and in Zhejiang Province during the periods 2000-2010 and 2010-2015. Three noticeable hotspots for S. alterniflora invasion were Yancheng of Jiangsu, Chongming of Shanghai, and Ningbo of Zhejiang, and each had a net area increase larger than 5000 ha. Moreover, an obvious shrinkage of S. alterniflora was identified in three coastal cities including the city of Cangzhou of Hebei, Dongguan, and Jiangmen of Guangdong. S. alterniflora invaded mostly into mudflats (>93%) and shrank primarily due to aquaculture (55.5%). This study sheds light on the historical spatial patterns in S. alterniflora distribution and thus is helpful for understanding its invasion mechanism and invasive species management
P-wave charmed baryons from QCD sum rules
We study the P-wave charmed baryons using the method of QCD sum rule in the
framework of heavy quark effective theory (HQET). We consider systematically
all possible baryon currents with a derivative for internal rho- and
lambda-mode excitations. We have found a good working window for the currents
corresponding to the rho-mode excitations for Lambda_c(2595), Lambda_c(2625),
Xi_c(2790) and Xi_c(2815) which complete two SU(3) 3F_bar multiplets of
J(P)=1/2(-) and 3/2(-), while the currents corresponding to the lambda-mode
excitations seem also consistent with the data. Our results also suggest that
there are two Sigma_c(2800) states of J(P)=1/2(-) and 3/2(-) whose mass
splitting is 14 \pm 7 MeV, and two Xi_c(2980) states whose mass splitting is 12
\pm 7 MeV. They have two Omega_c partners of J(P) = 1/2(-) and 3/2(-), whose
masses are around 3.25 \pm 0.20 GeV with mass splitting 10 \pm 6 MeV. All of
them together complete two SU(3) 6F multiplets of J(P)=1/2(-) and 3/2(-). They
may also have J(P)=5/2(-) partners. Xi_c(3080) may be one of them, and the
other two are Sigma_c(5/2(-)) and Omega_c(5/2(-)), whose masses are 85 \pm 23
and 50 \pm 27 MeV larger.Comment: 20 pages, 7 figures, accepted by PR
Decay properties of -wave charmed baryons from light-cone QCD sum rules
We study decay properties of the -wave charmed baryons using the method of
light-cone QCD sum rules, including the -wave decays of the flavor
-wave charmed baryons into ground-state charmed baryons
accompanied by a pseudoscalar meson ( or ) or a vector meson ( or
), and the -wave decays of the flavor -wave charmed
baryons into ground-state charmed baryons accompanied by a pseudoscalar meson
( or ). We study both two-body and three-body decays which are
kinematically allowed. We find two mixing solutions from internal - and
-mode excitations, which can well describe both masses and decay
properties of the , , and
. We also discuss the possible interpretations of -wave charmed
baryons for the , , , and the
recently observed , , ,
, and .Comment: 44 pages, 9 figures. Version appears in Phys. Rev.
Molecular identification of Trichogramma species from South and South-East Asia and natural Wolbachia infection
Trichogramma wasps were collected from the parasitized eggs of lepidopteran pests from 21 sampling sites in East Asia and South-East Asia. Six Trichogramma species were identified based on the molecular identificationmethod using the internal transcribed spacer 2 (ITS2) region of the rDNAof Trichogramma chilonis, T. evanescens, T. ostriniae, T. embryophagum, T. dendrolimi and T. japonicum. The results of molecular identification were confirmed by morphological identification. Additionally, natural populations were screened for the prevalence of Wolbachia. Five out of 21 populations were infected by the same Wolbachia strain, which was identified by using Wolbachia wsp gene and multilocus sequencing approach. The phylogenetic analysis of Wolbachia wsp sequences revealed that the Wolbachia strain was classified in the strain wEvaA in the group of EvA of the supergroup A
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