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Search Results: 1 - 10 of 209314 matches for " Dian L "
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Analysis of $B\to K^*_J (\to K π) μ^+μ^-$ in the higher kaon resonance region
Cai-Dian Lü,Wei Wang
Physics , 2011, DOI: 10.1103/PhysRevD.85.034014
Abstract: We study the resonant contributions in the process $\bar{B}^0\to K^- \pi^+\mu^+\mu^-$ with the $K^-\pi^+$ invariant mass square $m_{K\pi}^2\in [1, 5] {\rm GeV}^2$. Width effects of the involved strange mesons, $K^*(1410), K_0^*(1430), K_2^*(1430), K^*(1680), K_3^*(1780)$ and $K_4^*(2045)$, are incorporated. In terms of the helicity amplitudes, we derive a compact form for the full angular distributions, through which the branching ratios, forward-backward asymmetries and polarizations are attained. We propose that the uncertainties in the $B\to K^*_J$ form factors can be pinned down by the measurements of a set of SU(3)-related processes. Using results from the large energy limit, we derive the dependence of branching fractions on the $m_{K\pi}$, and find that the $K^*_2(1430)$ resonance has a clear signature, in particular, in the transverse polarizations.
Distinguishing two kinds of scalar mesons from heavy meson decays
Wei Wang,Cai-Dian Lü
Physics , 2009, DOI: 10.1103/PhysRevD.82.034016
Abstract: In the SU(3) symmetry limit, semileptonic $D^+\to Sl^+\nu$ and $B^-\to Sl^-\bar\nu$ decays, with $S=a_0(980)$, $f_0(980)$ and $f_0(600)$, are found to obey different sum rules in the $\bar qq$ and the tetra-quark descriptions for scalar mesons. Thus these sum rules can distinguish the two scenarios for light scalar mesons model-independently. This method also applies to the $\bar B^0\to J/\psi(\eta_c) S$ decays. Two kinds of SU(3) symmetry breaking effects are found to be under control, which will not spoil our method. The branching fractions of the $D^+\to Sl^+\nu$, $B^-\to Sl^-\bar\nu$ and $\bar B^0\to J/\psi(\eta_c) S$ decays roughly have the order $10^{-4}$, $10^{-5}$ and $10^{-6}$, respectively. The ongoing BES-III and the forthcoming Super B experiments are able to measure these channels and accordingly to provide detailed information of the scalar meson inner structure.
Constraint on the CKM angle alpha from the experimental measurements of CP violation in B_d^0 --> pi^+ pi^- decay
Cai-Dian Lü,Zhenjun Xiao
Physics , 2002, DOI: 10.1103/PhysRevD.66.074011
Abstract: In this paper, we study and try to find the constraint on the CKM angle alpha from the experimental measurements of CP violation in B_d^0 --> pi^+ pi^- decay, as reported very recently by BaBar and Belle Collaborations. After considering uncertainties of the data and the ratio r of penguin over tree amplitude, we found that strong constraint on both the CKM angle alpha and the strong phase delta can be obtained from the measured CP asymmetries S_{pi pi} and A_{pi pi}: (a) the ranges of 87 degrees <= alpha <= 131 degrees and 36 degrees <= delta <= 144 degrees are allowed by 1 sigma of the averaged data for r = 0.31; (b) for Belle's result alone, the limits on alpha and delta are 104 degrees <= alpha <= 139 degrees and 42 degrees <= delta <= 138 degrees for 0.32 <= r <= 0.41; and (c) the angle alpha larger than 90 degrees is preferred.
Trends in Extremes of Surface Humidity, Temperature, and Summertime Heat Stress in China
Julian XL Wang,Dian J Gaffen,
Julian X.L. Wang
,Dian J. Gaffen

大气科学进展 , 2001,
Abstract: In the past half century, the mean summertime temperature in China has increased, with nights warm ing more than days. Using surface station observations, we show that the frequency of extreme heat-stress events in China, caused by extremely hot and humid days as well as by heatwaves lasting for a few days, has increased over the period from 1951 to 1994. When humidity is high, hot weather can cause heat stress in humans. The increased heat-stress trend may pose a public health problem.
Laryngo-tracheo-oesophageal clefts
Nicolas Leboulanger, Eréa-No?l Garabédian
Orphanet Journal of Rare Diseases , 2011, DOI: 10.1186/1750-1172-6-81
Abstract: The first reported clinical case of laryngo-tracheo-oesophageal cleft was made by Richter in 1792 in a newborn presenting with recurrent aspiration [1]. The first successful surgical reconstruction was performed in 1955 [2], and the first reliable classification system was proposed in 1965 after a review of all available literature [3]. The first large and well documented series, illustrating the guidelines of diagnostic and therapeutic strategies, was proposed in 1983 [4]. Since then, numerous manuscripts have been published regarding laryngo-tracheo-oesophageal clefts and their management.. A laryngeal-tracheo-oesophageal cleft (commonly termed laryngeal cleft, LC) is a congenital malformation of the posterior part of the larynx, possibly extended to the trachea, creating an abnormal communication between the laryngo-tracheal axis and the pharyngo-oesophageal axis (Figure 1). Thus, the physiological separation between the airway and the digestive tract is lost, leading to chronic cough, aspiration, respiratory distress, pneumonia.... The severity of a LC is directly correlated to the downward extension of the cleft. This disease is registered in both Orphanet (ORPHA2004) and OMIM (#215800) databases [5].Recent advances in knowledge, diagnosis and, above all, the treatment of LC, have led to significant improvements in survival and quality of life of these patients.Over the past 50 years, many classifications of LC have been proposed, all based on the downward extension of the cleft: Petterson (1955), Armitage (1984), Evans (1985), Benjamin (1989), Meyer (1990), DuBois (1990), and Sandu (2006) [6]. All have a threefold interest:- Descriptive; allowing the comparison of a series of patients in the literature;- Therapeutic; influencing the choice of a reconstructive technique and surgical approach- Prognostic; as success and survival rates are highly correlated to the extension of the LC.To date, the Benjamin and Inglis classification [7], modified by Sandu in 2006 [
Study of W-Exchange Mode D0 → ФK0
DU Dong-Sheng,LI Ying,Lü Cai-Dian
中国物理快报 , 2006,
Abstract: We calculate the branching ratio of rare decay D^0→ФK using the perturbative QCD factorization approach based on kT factorization. Our result shows this branching ratio is (8.7 ± 1.4) x 10^-3, which is consistent with experimental data. We hope that the CLEO-C and BES-Ⅲ can measure it more accurately, which will help us to understand QCD dynamics and D meson weak decays.
Covariant Light-Front Approach for $B_c$ transition form factors
Wang, Wei;Shen, Yue-Long;Lü, Cai-Dian
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.79.054012
Abstract: In the covariant light-front quark model, we investigate the form factors of $B_c$ decays into $D, D^*, D_s, D_s^*, \eta_c, J/\psi, B, B^*, B_s, B_s^*$ mesons. The form factors in the spacelike region $q^2<0$ are directly evaluated. To extrapolate the form factors to the full kinematic region, we fit the form factors by adopting a three-parameter form from the spacelike region. $b\to u,d,s$ transition form factors at maximally recoiling point ($q^2=0$) are smaller than $b\to c$ and $c\to d,s$ transition form factors, while the $b\to d,s,c$ form factors at zero recoiling point are close to each other. In the fitting procedure, we find the parameters for the form factors $A_2(B_c\to B^*)$ and $A_2(B_c\to B^*_s)$ strongly depend on the decay constants of $B^*$ and $B_s^*$ mesons. Fortunately, the semileptonic and nonleptonic $B_c$ decays are not sensitive to these form factors. With the form factors, we also investigate the branching fractions, polarizations of the semileptonic $B_c\to Ml\nu$ decays. Semileptonic $B_c\to (\eta_c,J/\psi)l\nu$ and $B_c\to (B_s,B_s^*)l\nu$ decays have much larger branching fractions than $B_c\to (D,D^*,B,B^*)l\nu$. In the three kinds of $B_c\to Vl\nu$ decays, contributions from the longitudinal polarized vector is comparable with those from the transversely polarized vector. These predictions will be tested at the ongoing and forthcoming hadron colliders.
Constraints on the R-parity violating couplings using the newest measurement of the decay $B_s^0 \rightarrow \mu^+ \mu^-$
Li, Cheng;Lü, Cai-Dian;Gao, Xiang-Dong
High Energy Physics - Phenomenology , 2013,
Abstract: Recently, the LHCb collaboration reported the first evidence for the decay $B_s^0 \rightarrow \mu^+ \mu^-$. A branching ratio of $\mathcal{B}(B_s^0 \rightarrow \mu^+ \mu^-) = (3.2^{+1.5}_{-1.2}) \times 10^{-9}$ is given. Using the newest data, and together with the most precise predictions of the Standard Model contributions to the decay, we derive the constraints on the combinations of the R-parity violating parameters. Our results are several orders of magnitudes stronger than the constraints in the previous literature. We also update the constraints on the relevant parameters using the upper limit of $\mathcal{B}(B_d^0 \rightarrow \mu^+ \mu^-)$.
Pure annihilation type $ D\to PP(V)$ decays in the perturbative QCD approach
Zou, Zhi-Tian;Li, Cheng;Lü, Cai-Dian
High Energy Physics - Phenomenology , 2013,
Abstract: The annihilation type diagrams are difficult to calculate in any kind of models or method. Encouraged by the the successful calculation of pure annihilation type B decays in the perturbative QCD factorization approach, we calculate the pure annihilation type $D\to PP(V)$ decays in the perturbative QCD approach based on the $k_T$ factorization. Although the expansion parameter $1/m_D$ is not very small, our leading order numerical results agree with the existing experiment data for most channels. We expect the more accurate observation from experiments, which can help us learn about the dynamics of $D$ meson weak decays.
Radiative charmless B_{(s)}\to V \gamma and B_{(s)}\to A \gamma decays in pQCD approach
Wang, Wei;Li, Run-Hui;Lü, Cai-Dian
High Energy Physics - Phenomenology , 2007,
Abstract: We study the radiative charmless $B_{(s)}\to V(A)\gamma $ decays in perturbative QCD (pQCD) approach to the leading order in $\alpha_s$ (here $V$ and $A$ denotes vector mesons and two kinds of axial-vector mesons: $^3P_1$ and $^1P_1$ states, respectively.). Our predictions of branching ratios are consistent with the current available experimental data. We update all $B_{(s)}\to V$ form factors and give the predictions for $B\to A$ form factors using the recent hadronic inputs. In addition to the dominant factorizable spectator diagrams, which is form factor like, we also calculate the so-called ``power suppressed'' annihilation type diagrams, the gluonic penguin, charming penguin, and two photon diagrams. These diagrams give the main contributions to direct CP asymmetries, mixing-induced CP asymmetry variables, the isospin asymmetry and U-spin asymmetry variables. Unlike the branching ratios, these ratios or observables possess higher theoretical precision in our pQCD calculation, since they do not depend on the input hadronic parameters too much. Most of the results still need experimental tests in the on-going and forthcoming experiments.
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