The Electromagnetic Decays of Bc±(2S)B^{\pm}_c(2S)

We calculate the electromagnetic (EM) decay widths of the $B^{\pm}_c(2S)$ meson, which is observed recently by the ATLAS Collaboration. The main EM decay channels of this particle are $1{^3S_1}\gamma$ and $1{P}\gamma$, which, in literature, are estimated to have the branching ratio of about $1/10$. In this work, we get the partial decay widths: $\Gamma(2{^1S_0}\rightarrow 1{^3S_1}\gamma)=0.192$ keV, $\Gamma(2{^1S_0}\rightarrow 1{P_1}\gamma) = 2.24$ keV and $\Gamma(2{^1S_0}\rightarrow 1{P_1^\prime}\gamma) = 11.4$ keV. In the calculation, the instantaneous approximated Bethe-Salpeter method is used. For the $P$-wave $B_c$ mesons, the wave functions are given by mixing the $^3P_1$ and $^1P_1$ states. Within the Mandelstam formalism, the decay amplitude is given, which includes the relativistic corrections.Comment: 9 pages, 3 figures, 3 table

Study of the excited 1−1^- charm and charm-strange mesons

We give a systematical study on the recently reported excited charm and charm-strange mesons with potential $1^-$ spin-parity, including the $D^*_{s1}(2700)^+$, $D^*_{s1}(2860)^+$, $D^*(2600)^0$, $D^*(2650)^0$, $D^*_1(2680)^0$ and $D^*_1(2760)^0$. The main strong decay properties are obtained by the framework of Bethe-Salpeter (BS) methods. Our results reveal that the two $1^-$ charm-strange mesons can be well described by the further $2^3\!S_1$-$1^3\!D_1$ mixing scheme with a mixing angle of $8.7^{+3.9}_{-3.2}$ degrees. The predicted decay ratio $\frac{\mathcal{B}(D^*K)}{\mathcal{B}(D~K)}$ for $D^*_{s1}(2860)$ is $0.62^{+0.22}_{-0.12}$.~$D^*(2600)^0$ can also be explained as the $2^3\!S_1$ predominant state with a mixing angle of $-(7.5^{+4.0}_{-3.3})$ degrees. Considering the mass range, $D^*(2650)^0$ and $D^*_1(2680)^0$ are more likely to be the $2^3\!S_1$ predominant states, although the total widths under both the $2^3\!S_1$ and $1^3\!D_1$ assignments have no great conflict with the current experimental data. The calculated width for LHCb $D^*_1(2760)^0$ seems about 100 \si{MeV} larger than experimental measurement if taking it as $1^3\!D_1$ or $1^3\!D_1$ dominant state $c\bar u$. The comparisons with other calculations and several important decay ratios are also present. For the identification of these $1^-$ charm mesons, further experimental information, such as $\frac{\mathcal{B}(D\pi)}{\mathcal{B}(D^*\pi)}$ are necessary.Comment: 18 pages, 3 figure

Why Do Customers Buy Products on Social Commerce Platform? A Study from Affordance Theory

This study examines the influence mechanism of the factors of influencing live streaming shopping which is a new social commerce mode for customer purchase based on the affordance theory. Our research examines how visibility affordance, metavoicing affordance and guidance shopping affordance which are three main affordances in live streaming shopping influence the customers’ purchase intention. The results show that visibility affordance, metavoicing affordance and guidance shopping affordance will positively impact customer purchase intention. And our research is of great help in live streaming shopping research in social commerce research field. Also, our research provides some advices for social commerce operators

Antioxidant and antibacterial activity of Toddalia asiatica (Linn) Lam root extracts

Background: Toddalia asiatica (Linn) Lam is a woody vine that is used medicinally in China, India, and East Africa. The aim of the present study was to examine the antioxidant and antibacterial activity of the roots of Toddalia asiatica (Linn) Lam (TA).Materials and Methods: The antioxidant capacity of TA roots was determined using 1,1 iphenyl-2-picrylhydrazyl (DPPH), 2,2´-azino-bis (3-ethylbenzo-thiazoline-6-sulfonicacid) (ABTS), and the ferric reducing antioxidant potential (FRAP) assay. The antimicrobial activity of TA against Staphylococcus aureus (SA), methicillin-resistant S. aureus (MRSA), and extended spectrum β-lactamase positive S. aureus (ESBLs-SA) was screened.Results: Methanol and ethyl acetate extracts of TA exhibited strong antioxidant activity. The methanol extract had the highest antioxidant activity (DPPH, IC50=41.45 μg/mL; ABTS, IC50=8.34 μg/mL; FRAP=1304.8 ± 60.38 μmol Trolox equivalent (TE)/g), which was close to that of the positive control, butylated hydroxytoluene (BHT). The petroleum ether extract of TA showed the highest antimicrobial activity (SA, minimum inhibitory concentration (MIC) = 250 μg/disc; MRSA, MIC=125 μg/disc) when compared with that of ethyl acetate extract (SA, MIC=250 μg/disc) and methanol extract.Conclusions: Investigation of methanol, petroleum ether, and ethyl acetate extracts of TA root revealed robust antioxidant activity in methanol extracts and strong antimicrobial activity against SA and MRSA in petroleum ether extracts.Keywords: Toddalia asiatica (Linn) Lam; antioxidant; antibacteria