Recently, the Wang Wei's group of LPC collaboration has systematically calculated the quasi-DA of vector mesons K* and ϕ containing a light quark and a strange quark using the quantum chromodynamics (QCD) on the lattice, and obtained a first-principles prediction for the LCDA based on large momentum and continuous extrapolation. This study is the only result so far in LaMET based on lattice QCD calculations with multiple lattice distances with physical quark mass parameters and continuous extrapolation with analytic calculations. The research paper has been recently published in Phys. Rev. Lett.

The most fundamental particles that make up our world include quarks, leptons and gauge bosons. The Standard Model has been the most successful theory for describing the physical properties of fundamental particles over the last few decades. With the increasing accuracy of high-energy particle collision experiments internationally, the precise testing of the Standard Model and the search for new physics beyond the Standard Model have become the main research directions in high-energy physics experiments and theory. In the Standard Model, the flavour-altering neutral process is strongly depressed and is the ideal decay channel for finding new physics signals. Among them, the B→K*l+l- and Bs→ϕl+l- processes have been focused on by the Belle and LHCb experimental groups in recent years, these anomalies between experimentally measurements and theoretical predictions have attracted widespread attention. Various new theoretical explanations have also been attempted to address these anomalies, but a reliable understanding of the light-cone wave functions (LCDA) for K* and ϕ is still lacking.

Recently, using the lattice quantum chromodynamics (QCD) method and based on the large momentum effective theory (LaMET) framework, the Wang Wei's group of LPC Collaboration  has systematically calculated the quasi-DA of vector mesons K* and ϕ containing a light quark and a strange quark on three lattice spacings of the MILC Collaboration with physical quark mass parameters (maximum size 96³x192). A first-principles prediction for LCDA is obtained based on large-momentum and continuum extrapolation with analytic calculations. The LCDA of transversely polarized K* meson has a significant asymmetry due to the mass difference between light and strange quarks (left panel); however, a similar asymmetry is not observed in the LCDA of longitudinally polarized K* mesons (right panel). This study is the only result in LaMET based on lattice QCD calculations with multiple lattice distances with physical quark mass parameters and with continuous extrapolation. The research paper has been recently published in Phys. Rev. Lett.

Jun Hua, a postdoctoral fellow at Shanghai Jiao Tong University, is the first author of the paper, with co-corresponding authors Professor Wei Wang of Shanghai Jiao Tong University and Professor Peng Sun of Nanjing Normal University. The research on high precision lattice QCD is based on the numerical algorithms with efficient implementation on super computers. For propagator calculations of physical quark masses, the geometric multiple lattice algorithm can be more than ten times faster than ordinary CG algorithms. Relying on the sub-project XDC01040100 of the Strategic Pioneer Project of the Chinese Academy of Sciences, Associate Researcher Yibo Yang of the Institute of Theoretical Physics of the Chinese Academy of Sciences and Professor Peng Sun of Nanjing Normal University have spent more than a year to port tens of thousands lines of code of the geometric multigrid algorithm to the CSCP-1, achieving efficient parallelism at the scale of ten million cores. The design and implementation of the research was guided by Associate Researcher Yibo Yang the spokesperson of the LPC Collaboration, and Professor Jianhui Zhang of Beijing Normal University led the analytical calculations required for the research.

The numerical calculations for this research were mainly done on CSC Pioneer 1, with software debugging and part of calculations done on the pi2.0 computing platform at the High Performance Computing Centre of Shanghai Jiao Tong University.

The research has been supported by the National Natural Science Foundation of China (Key Project and Sino-German Cooperation) and the CAS Pioneer Special Project and Incubation Project.