全国粒子物理会 桂林 2019/1/14 Implications of the scalar meson structure from B SP decays within PQCD approach Yuelong Shen IHEP, CAS In collaboration with C. D. Lu , W. Wang… 2019/1/14 高能物理学会第七届年会@桂林

Outline Motivation Scalar meson production in B decays 全国粒子物理会 桂林 2019/1/14 Outline Motivation Scalar meson production in B decays Numerical results and discussions Conclusion and outlook References: W. Wang, YLS, Y. Li and C. D. Lu, hep-ph/0609082; YLS, W. Wang, J. Zhu and C. D. Lu, hep-ph/0610380. 2019/1/14 高能物理学会第七届年会@桂林

Motivation Problems in scalar meson spectroscopy The advantages in study scalar meson in B decays Annihilation diagrams: Why we use PQCD approach 2019/1/14 高能物理学会第七届年会@桂林

Problems in scalar meson spectroscopy Classification of the multiplets and exotic states One nonet below and one above 1 GeV The low mass nonet is more likely formed by the states one nonet above or close to 1 GeV are not physical state The existence of glueballs Lattice results: the mass of the scalar glueball lies in (1500-1800)MeV 2019/1/14 高能物理学会第七届年会@桂林

Advantages in study scalar meson in B decays The larger phase space, S wave dominant New source of glueballs 2019/1/14 高能物理学会第七届年会@桂林

is regarded as mixing of and in our calculation : Experimental data The earlier study PQCD QCDF, Cheng et al PRD 71,054020(2005), PRD73, 014017(2006) Generalized factorization +new physics, A. Giri, et al, hep-ph/0608088. 2019/1/14 高能物理学会第七届年会@桂林

, and are assumed to be mixing of qark-antiquark and glueball states The mixing scheme is still under controversy Cheng et al Close and Zhao The decays have been measured in but not in BKpipi 2019/1/14 高能物理学会第七届年会@桂林

Large branching ratios of The upper limits of branching ratios for is very small. 2019/1/14 高能物理学会第七届年会@桂林

Annihilation contributions: the reason for employing PQCD In QCDF, cancels most contribution from , and the predicted branching ratio is much smaller than the experiment To fit the data, large annihilation contribution are needed. Too large annihilation contribution will overshoot the data 2019/1/14 高能物理学会第七届年会@桂林

An introduction to PQCD approach 2019/1/14 高能物理学会第七届年会@桂林

Scalar meson decay constant and distribution amplitude Definition of the decay constant Definition of the distribution amplitude normalization 2019/1/14 高能物理学会第七届年会@桂林

Hard kernel diagrams contribution Only the twist-3 wave function contribute to the factorizable emission diagram There is enhancement rather than cancellation between the two nonfactorizable diagrams contribution 2019/1/14 高能物理学会第七届年会@桂林

contribution 2019/1/14 高能物理学会第七届年会@桂林

Numerical results for For : the larger decay constant leads to larger amplitudes. For : The nonfactorizable emission diagrams and annihilation diagrams give the dominant contribution , which comes from the Gegenbauer moments of the twist 2 LCDA. 2019/1/14 高能物理学会第七届年会@桂林

Numerical results for The perturbative calculation suffices to explain the data, the FSI or new physics is not essential. 2019/1/14 高能物理学会第七届年会@桂林

Numerical results for Scenario II Scenario I The qqbar ground state with the mass at about 1500 MeV is favored 2019/1/14 高能物理学会第七届年会@桂林

and The branching ratios 2019/1/14 高能物理学会第七届年会@桂林

Conclusion and outlook Within PQCD approach, decays are consistent with the experiment The results of and indicate that scenario II is more preferable. If we regard as , it being a ground state is more favored. We need more precise nonperturbative parameters, such as the twist-3 distribution amplitudes etc. The glueball contribution should be included. More channels should be considered to constrain the scalar meson structure. 2019/1/14 高能物理学会第七届年会@桂林

Thank you for your patience ! 2019/1/14 高能物理学会第七届年会@桂林