We present the first lattice QCD calculation of the distribution amplitudes of longitudinally and transversely polarized vector mesons $K^{*}$ and $\varphi$ using large momentum effective theory. We use the clover fermion action on three ensembles with $2+1+1$ flavors of highly improved staggered quarks action, generated by the MIMD Lattice Computation Collaboration, at physical pion mass and $\{0.06,0.09,0.12\}\mathrm{fm}$ lattice spacings and choose three different hadron momenta $P_z=\{1.29,1.72,2.15\}\mathrm{GeV}$. The resulting lattice matrix elements are nonperturbatively renormalized in a recently proposed hybrid scheme. An extrapolation to the continuum and infinite momentum limit is carried out. We find that, while the longitudinal distribution amplitudes tend to be close to the asymptotic form, the transverse ones deviate rather significantly from the asymptotic form. Our final results provide crucial ab initio theory inputs for analyzing pertinent exclusive processes.

We calculate the soft function using lattice QCD in the framework of large momentum effective theory incorporating the one-loop perturbative contributions. The soft function is a crucial ingredient in the lattice determination of light cone objects using transverse-momentum-dependent (TMD) factorization. It consists of a rapidity-independent part called intrinsic soft function and a rapidity-dependent part called Collins-Soper kernel. We have adopted appropriate normalization when constructing the pseudoscalar meson form factor that is needed in the determination of the intrinsic part and applied Fierz rearrangement to suppress the higher-twist effects. In the calculation of CS kernel we consider a CLS ensemble other than the MILC ensemble used in a previous study. We have also compared the applicability of determining the CS kernel using quasi TMDWFs and quasi TMDPDFs. As an example, the determined soft function is used to obtain the physical TMD wave functions (WFs) of pion and unpolarized iso-vector TMD parton distribution functions (PDFs) of proton.

We present a lattice QCD calculation of the transverse-momentum-dependent wave function (TMDWF) of the pion using large-momentum effective theory. Numerical simulations are based on one ensemble with $2+1+1$ flavors of highly improved staggered quarks with lattice spacing $a=0.121\mathrm{fm}$ from the MILC collaboration, and one with $2+1$ flavor clover fermions and tree-level Symanzik gauge action generated by the CLS collaboration with $a=0.098\mathrm{fm}$. As a key ingredient, the soft function is first obtained by incorporating the one-loop perturbative contributions and a proper normalization. Based on this and the equal-time quasi-TMDWF simulated on the lattice, we extract the TMDWF. The results for both lattice ensembles are compatible and a comparison with a phenomenological parametrization is made. Our studies provide a first attempt of ab initio calculation of TMDWFs which will eventually lead to crucial theory inputs for making predictions for exclusive processes under QCD factorization.

Based on the flavor structure of four-quark effective operators, we develop an automatic computation program to calculate hadronic two-body $B$ meson decay amplitudes, and apply it to their global analysis in the perturbative QCD (PQCD) approach. Fitting the PQCD factorization formulas for $B\to PP,VP$ decays at leading order in the strong coupling ${\alpha }_s$ to measured branching ratios and direct $CP$ asymmetries, we determine the Gegenbauer moments in light meson light cone distribution amplitudes (LCDAs). It is found that most of the fitted Gegenbauer moments of the twist-2 and twist-3 LCDAs for the pseudoscalar meson $P$ ($P=\pi$, $K$) and vector meson $V$ ($V=\rho$, $K^{*}$) agree with those derived in QCD sum rules. The shape parameter for the $B_s$ meson distribution amplitude and the weak phase ${\varphi }_3(\gamma )=(75.2\pm 2.9)°$ consistent with the value in Particle Data Group are also obtained. It is straightforward to extend our analysis to higher orders and higher powers, when the corresponding subleading contributions are available in the PQCD approach, and to the global determination of LCDAs for other hadrons.

We calculate the leading-twist light cone distribution amplitudes of the Λ ( u d s ) baryon using lattice QCD methods within the framework of large-momentum effective theory. Our numerical computations are carried out with N f = 2 + 1 stout smeared clover fermions and a Symanzik gauge action on a lattice with spacing a = 0.077 fm and a pion mass of 303 MeV. To approach the large-momentum region, we simulate the equal-time correlations with the hadron momentum P z = { 2.52 , 3.02 , 3.52 } GeV . We investigate the analytic properties of the baryon quasidistribution amplitude in coordinate space and validate them through our lattice calculations. After renormalization and extrapolation, we present results for the three-dimensional distribution in momentum fractions of the two light quarks. Based on these findings, we briefly discuss the phenomenological impact on weak decays of Λ b and outline potential systematic uncertainties that can be improved in the future. This work lays the theoretical foundation for accessing baryon light cone distribution amplitudes from lattice QCD. Published by the American Physical Society 2025

We perform a global analysis of three-body charmless hadronic decays $B\to V{P}_3\to P_1{P}_2{P}_3$ in the perturbative QCD (PQCD) approach, where $V$ denotes an intermediate vector resonance, and $P_i$, $i=1$, 2, 3 denote final-state pseudoscalar mesons. Fitting the PQCD factorization formulas at leading order in the strong coupling ${\alpha }_s$ to measured branching ratios and direct $CP$ asymmetries, we determine the Gegenbauer moments in the two-meson distribution amplitudes (DAs) for the meson pairs $P_1{P}_2=\pi \pi ,K\pi ,KK$. The fitted Gegenbauer moments are then employed to make predictions for those observables, whose data are excluded in the fit due to larger experimental uncertainties. A general consistency between our predictions and data is achieved, which hints at the validity of the PQCD formalism for the above three-body $B$-meson decays and the universality of the nonperturbative two-meson DAs. The obtained two-meson DAs can be applied to PQCD studies of other multi-body $B$-meson decays involving the same meson pairs. We also attempt to determine the dependence of the Gegenbauer moments on the meson-pair invariant mass, and demonstrate that this determination is promising, when data become more precise.