In this work, we systematically study the radiative decays and magnetic moments of the charmed and bottom vector mesons with chiral perturbation theory up to one-loop level. We present the results in the SU(2) and SU(3) cases with the mass splitting in loop diagrams kept and unkept, respectively. The obtained decay rates for D Ã and B Ã mesons in the SU(3) case with the mass splitting kept are ΓDÃ0 →D 0 γ ¼ 16.2 þ6.5 −6.0 keV, Γ D Ã− →D − γ ¼ 0.73 þ0.7 −0.3 keV, Γ D Ã− s →D − s γ ¼ 0.32 þ0.3 −0.3 keV, and Γ B Ãþ →B þ γ ¼ 0.58 þ0.2 −0.2 keV, Γ B Ã0 →B 0 γ ¼ 0.23 þ0.06 −0.06 keV, Γ B Ã0 s →B 0 s γ ¼ 0.04 þ0.03 −0.03 keV. The decay width for D Ã− → D − γ is consistent with the experimental measurement. As a byproduct, the full widths ofD Ã0 and D Ã− s are Γ tot ðD Ã0 Þ ≃ 77.7 þ26.7 −20.5 keV and Γ tot ðD Ã− s Þ ≃ 0.62 þ0.45 −0.50 keV, respectively. We also calculate the magnetic moments of the heavy vector mesons. The analytical chiral expressions derived in our work shall be helpful for the extrapolations of lattice QCD simulations in the future.

No abstract

We systematically calculate the isospin violating decay, D * s → Dsπ 0 , with the heavy meson chiral perturbation theory up to O(p 3 ) including the loop diagrams. The O(p 3 ) tree level amplitudes contain four undetermined LECs. We use two strategies to estimate them. With the nonanalytic dominance approximation, we get Γ[D * s → Dsπ 0 ] = (3.38 ± 0.12) eV. With the naturalness assumption, we give a possible range of the isospin violating decay width, [1.11 − 6.88] eV. We find that the contribution of the O(p 3 ) corrections might be significant.

We investigate the possible deuteron-like molecules composed of a pair of charmed spin-3 2 baryons, or one charmed baryon and one charmed antibaryon within the one-boson-exchange (OBE) model. For the spin singlet and triplet systems, we consider the couple channel effect between systems with different orbital angular momentum. Most of the systems have binding solutions. The couple channel effect plays a significant role in the formation of some loosely bound states. The possible molecular states of Ω * c Ω * c might be stable once produced.

We systematically investigate the possible molecular states composed of (1) two spin-3 2 doubly charmed baryons, and (2) a pair of spin-3 2 and spin-1 2 doubly charmed baryons. The one-boson-exchange (OBE) model is used to describe the potential between two baryons. The channel mixing effect is considered for the systems with the same quantum number (I(J P )) but different total spin (S) and orbital angular momenta (L). We also study the channel mixing effect among the systems composed of various doubly charmed baryons if they have the same quantum number. Many of the systems are good candidates of molecular states.

No abstract

Background Invasive species can threaten native diversity and alter ecosystem processes while interacting with other components of global environmental change. Invasive plants are becoming increasingly problematic and this can be stimulated by changes in the environment. However, existing studies have primarily investigated the effects of environmental change on a specific stage of plant invasion rather than the continuous invasion process. Methods A space-for-time substitution experiment was performed to investigate how warming and nitrogen deposition affects the invasion process of a plant. Specifically, different ratios of invasive Solidago canadensis L. to native Artemisia argyi Levl. et Van were employed as a proxy to represent successive levels of invasion. A total of seven treatments were applied in the experiment: ambient (CK), N addition (+ 5, + 12 g m−2 year−1), warming (+ 1.15, + 1.86 °C) and their interaction (5 g N m−2 year−1 + 1.15 °C, 12 g N m−2 year−1 + 1.86 °C). The growth performance and competitiveness of S. canadensis were investigated. Results The competitiveness of Solidago canadensis decreased linearly with its invasion degree (p < 0.05). Non-linear regression showed that S. canadensis invasion levels of 53%, 53%, 68%, 55% and 58% were the critical thresholds for shifting the direction or magnitude of chlorophyll, leaf nitrogen, leaf shape index, diameter, and root/shoot ratio, respectively. Compared with the ambient treatment (CK, no warming and no N addition), the diameter, height, biomass and relative competitiveness of S. canadensis were each limited by warming, to a certain extent, whereas these and the above parameters were significantly increased by nitrogen deposition. The interaction of increased temperature and nitrogen deposition led to significant increases in the growth and competitiveness of S. canadensis, and this effect was detected in every stage of the invasion, throughout the invasion process. Conclusions Environmental change might have a continuous, progressive, and augmentative effect on the phenotypic traits of S. canadensis. This study provides fairly robust evidence that environmental change promotes the invasion process of S. canadensis in general, not simply in specific stages. In the future, rather than focusing on specific stages, experimental studies should consider examining invasion on a broader scale.

Invasive plants threaten biodiversity and cause huge economic losses. It is thought that global change factors (GCFs) associated with climate change (including shifts in temperature, precipitation, nitrogen, and atmospheric CO2) will amplify their impacts. However, only few studies assessed mixed factors on plant invasion. We collated the literature on plant responses to GCFs to explore independent, combined, and interactive effects on performance and competitiveness of native and invasive plants. From 176 plant species, our results showed that: (1) when native and invasive plants are affected by both independent and multiple GCFs, there is an overall positive effect on plant performance, but a negative effect on plant competitiveness; (2) under increased precipitation or in combination with temperature, most invasive plants gain advantages over natives; and (3) interactions between GCFs on plant performance and competitiveness were mostly synergistic or antagonistic. Our results indicate that native and invasive plants may be affected by independent or combined GCFs, and invasive plants likely gain advantages over native plants. The interactive effects of factors on plants were non-additive, but the advantages of invasive plants may not increase indefinitely. Our findings show that inferring the impacts of climate change on plant invasion from factors individually could be misleading. More mixed factor studies are needed to predict plant invasions under global change.