Revisiting B->phi pi Decays in the Standard Model

In the standard model (SM), we re-investigate the rare decay $B\to \phi\pi$, which has been viewed as an ideal probe to detect the new physics signals beyond the SM. Contributions in the naive factorization method, the radiative corrections, the long-distance contributions, and the contributions due to the $\omega$-$\phi$ mixing are taken into account. We find that the tiny branching ratio in the naive factorization can be dramatically enhanced by the radiative corrections and the $\omega$-$\phi$ mixing effect, while the long-distance contributions are negligibly small. Assuming the Cabibbo-Kobayashi-Maskawa angle $\gamma=(58.6\pm 10)^\circ$ and the mixing angle $\theta= -(3.0\pm 1.0)^\circ$, we obtain the branching ratios of $B\to \phi\pi$ as ${\rm Br}(B^\pm\to \phi \pi^\pm)= (3.2 ^{+0.8-1.2}_{-0.7+1.8}) \times 10^{-8}$ and ${\rm Br}(B^0 \to \phi \pi^0) = (6.8 ^{+0.3-0.7}_{-0.3+1.0}) \times 10^{-9}$. If the future experiment reports a branching ratio of order $10^{-7}$ for $B^-\to \phi \pi^-$ decay, it may not be a clear signal for any new physics scenario. In order to discriminate the large new physics contributions and those due to the $\omega$-$\phi$ mixing, we propose to measure the ratio of branching fractions of the charged and neutral B decay channel. We also study the direct CP asymmetries of these two channels, and the results are about $(-8.0^{+0.9+1.5}_{-1.0-0.1})$ and $(-6.3^{-0.5+2.5}_{+0.7-2.5})$ for $B^\pm\to \phi \pi^\pm$ and $B^0 \to \phi \pi^0$, respectively.Comment: 11 pages, 5 figure

Unveiling the Secrets of Collaboration on Video-Sharing Platforms

In online video platforms, collaborative content creation gains popularity as vloggers exchange social capital to boost content’s appeal and personal visibility. However, existing research lacks rigorous verification of collaboration efficacy in this context. This study investigates the benefits of collaboration on vlogger influence within the online video domain. Utilizing a staggered difference-in-differences approach, we found that collaboration indeed generates positive impact on vloggers’ influence, as evidenced by the significant increases of their fan and like numbers among the audience. However, managing collaboration activities with suitable intensity is vital, as the marginal utility of collaborations diminishes with increased collaboration numbers. Furthermore, vloggers should avoid excessive non-core activities (e.g., uploading photo albums, audios, and articles) post-collaboration, as these peripheral activities negatively affect collaboration benefits in online video contexts. We believe that the findings of our study will provide helpful guidelines for designing more effective collaboration strategies on video sharing platforms