Determination of the strong coupling gB∗Bπg_{B^* B\pi} from semi-leptonic B→πℓνB\to \pi \ell \nu decay

According to heavy-meson chiral perturbation theory, the vector form factor $f_+(q^2)$ of exclusive semi-leptonic decay $B\to \pi \ell \nu$ is closely related, at least in the soft-pion region (i.e., $q^{2} \sim (m_B-m_{\pi})^2$), to the strong coupling $g_{B^* B\pi}$ or the normalized coupling $\hat g$. Combining the precisely measured $q^2$ spectrum of $B\to \pi \ell \nu$ decay by the BaBar and Belle collaborations with several parametrizations of the form factor $f_+(q^2)$, we can extract these couplings from the residue of the form factor at the $B^*$ pole, which relies on an extrapolation of the form factor from the semi-leptonic region to the unphysical point $q^2=m_{B^*}^2$. Comparing the extracted values with the other experimental and theoretical estimates, we can test these various form-factor parametrizations, which differ from each other by the amount of physical information embedded in. It is found that the extracted values based on the BK, BZ and BCL parametrizations are consistent with each other and roughly in agreement with the other theoretical and lattice estimates, while the BGL ansatz, featured by a spurious, unwanted pole at the threshold of the cut, gives a neatly larger value.Comment: 19 pages, no figure. Revise

Constraints on B--->pi,K transition form factors from exclusive semileptonic D-meson decays

According to the heavy-quark flavour symmetry, the $B\to \pi, K$ transition form factors could be related to the corresponding ones of D-meson decays near the zero recoil point. With the recent precisely measured exclusive semileptonic decays $D \to \pi \ell \nu$ and $D\to K \ell \nu$, we perform a phenomenological study of $B \to \pi, K$ transition form factors based on this symmetry. Using BK, BZ and Series Expansion parameterizations of the form factor slope, we extrapolate $B \to \pi, K$ transition form factors from $q^{2}_{max}$ to $q^{2}=0$. It is found that, although being consistent with each other within error bars, the central values of our results for $B \to \pi, K$ form factors at $q^2=0$, $f_+^{B\to \pi, K}(0)$, are much smaller than predictions of the QCD light-cone sum rules, but are in good agreements with the ones extracted from hadronic B-meson decays within the SCET framework. Moreover, smaller form factors are also favored by the QCD factorization approach for hadronic B-meson decays.Comment: 19 pages, no figure, 5 table

Serum 25-hydroxyvitamin D levels and the risk of idiopathic central precocious puberty in girls

Introduction: Prior studies have found inconsistent results regarding the relationship between vitamin D status and Idiopathic Central Precocious Puberty (ICPP). Objective: To assess the role of serum 25-hydroxyvitamin D (25 [OH]D) levels in ICPP development. Method: The authors retrospectively collected data from 221 girls with ICPP and 144 healthy girls between January 2017 and December 2019. The participants’ serum 25(OH)D levels were measured using an automatic chemiluminescence method, and the association between serum 25(OH)D levels and the risk of ICPP was assessed using multivariate logistic regression analysis. Odds Ratios (OR) with 95% Confidence Intervals (95% CI) were calculated as effect estimates. Results: Serum 25(OH)D levels in the ICPP group were significantly lower than those in healthy controls (p < 0.001). Multivariate analysis indicated that girls with insufficient vitamin D levels (OR = 0.201; 95% CI 0.094–0.428; p < 0.001) and sufficient vitamin D levels (OR = 0.141; 95% CI 0.053–0.375; p < 0.001) both had a lower risk of ICPP than girls with vitamin D deficiency. Moreover, the authors found that the height (p = 0.014), weight (p = 0.014), breast stage (p = 0.010), mother's height (p < 0.001), and luteinizing hormone/follicle-stimulating hormone ratio (p = 0.010) in girls with ICPP could be associated with levels of vitamin D. Conclusion: This study found that a low serum 25(OH)D level is an independent risk factor for ICPP, and several characteristics of girls with ICPP could be affected by their vitamin D status.

QCD Approach to B->D \pi Decays and CP Violation

The branching ratios and CP violations of the $B\to D\pi$ decays, including both the color-allowed and the color-suppressed modes, are investigated in detail within QCD framework by considering all diagrams which lead to three effective currents of two quarks. An intrinsic mass scale as a dynamical gluon mass is introduced to treat the infrared divergence caused by the soft collinear approximation in the endpoint regions, and the Cutkosky rule is adopted to deal with a physical-region singularity of the on mass-shell quark propagators. When the dynamical gluon mass $\mu_g$ is regarded as a universal scale, it is extracted to be around $\mu_g = 440$ MeV from one of the well-measured $B\to D\pi$ decay modes. The resulting predictions for all branching ratios are in agreement with the current experimental measurements. As these decays have no penguin contributions, there are no direct $CP$ asymmetries. Due to interference between the Cabibbo-suppressed and the Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the $B\to D^{\pm}\pi^{\mp}$ decays to be consistent with the experimental data at 1-$\sigma$ level. More precise measurements will be helpful to extract weak angle $2\beta+\gamma$.Comment: 21pages,5 figures,3 tables, typos corrected and numerical result for one of decay channels is improve

Transcatheter valve-in-valve implantation versus reoperative conventional aortic valve replacement: a systematic review

none6siTranscatheter valve-in-valve (VIV) implantation for degenerated aortic bioprostheses has emerged as a promising alternative to redo conventional aortic valve replacement (cAVR). However there are concerns surrounding the efficacy and safety of VIV. This systematic review aims to compare the outcomes and safety of transcatheter VIV implantation with redoes cAVR. Six databases were systematically searched. A total of 18 relevant studies (823 patients) were included. Pooled analysis demonstrated VIV achieved significant improvements in mean gradient (38 mmHg preoperatively to 15.2 mmHg postoperatively, P<0.001) and peak gradient (59.2 to 23.2 mmHg, P=0.0003). These improvements were similar to the outcomes achieved by cAVR. The incidence of moderate paravalvular leaks (PVL) were significantly higher for VIV compared to cAVR (3.3% vs. 0.4%, P=0.022). In terms of morbidity, VIV had a significantly lower incidence of stroke and bleeding compared to redo cAVR (1.9% vs. 8.8%, P=0.002 & 6.9% vs. 9.1%, P=0.014, respectively). Perioperative mortality rates were similar for VIV (7.9%) and redo cAVR (6.1%, P=0.35). In conclusion, transcatheter VIV implantation achieves similar haemodynamic outcomes, with lower risk of strokes and bleeding but higher PVL rates compared to redo cAVR. Future randomized studies and prospective registries are essential to compare the effectiveness of transcatheter VIV with cAVR, and clarify the rates of PVLs.openPhan, Kevin; Zhao, Dong-Fang; Wang, Nelson; Huo, Ya Ruth; Di Eusanio, Marco; Yan, Tristan DPhan, Kevin; Zhao, Dong-Fang; Wang, Nelson; Huo, Ya Ruth; Di Eusanio, Marco; Yan, Tristan