Leading Twist Light-cone Distribution Amplitudes Research Articles

Lightcone and quasi distribution amplitudes for light octet and decuplet baryons

We present a comprehensive investigation of leading-twist lightcone distribution amplitudes (LCDAs) and quasi distribution amplitudes (quasi-DAs) for light octet and decuplet baryons within large momentum effective theory. In LaMET, LCDAs can be factorized in terms of a hard kernel and quasi-DAs that are defined as spatial correlators and calculable on Lattice QCD. To renormalize quasi-DAs and eliminate the singular terms ln(μ2zi2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mu}^2{z}_i^2 $$\\end{document}) in them, which undermine the efficacy in perturbative expansion, we adopt a hybrid renormalization scheme that combines the self-renormalization and ratio scheme. Through self-renormalization, we eliminate UV divergences and linear divergences at large spatial separations in quasi distribution amplitudes without introducing additional nonperturbative effects. By taking a ratio with respect to the zero-momentum matrix element, we effectively remove UV divergences at small spatial separations. Under the hybrid renormalization scheme, we calculate the hard kernels up to one-loop accuracy. It turns out that only four different hard kernels are needed for all leading-twist LCDAs of octet and decuplet baryons. These results are crucial for the lattice-based exploration of the LCDAs of a light baryon from the first principle of QCD.

Exclusive production of double light neutral mesons at the e+e− colliders

In this work we investigate the exclusive production of a pair of light neutral mesons in e+e− annihilation, where the final state bears an even C-parity. The production processes can be initiated via the photon fragmentation or the nonfragmentation mechanism. While the fragmentation contribution can be rigorously accounted, the nonfragmentation contributions are calculated within the framework of collinear factorization, where only the leading-twist light-cone distribution amplitudes (LCDAs) of mesons are considered. Mediately solely by the nonfragmentation mechanism, the production rates of double light neutral pseudoscalar mesons are too small to be observed at the commissioning e+e− facilities. In contrast, the production rates of a pair of light neutral vector mesons are greatly amplified owing to the significant kinematic enhancement brought by the fragmentation mechanism. It is found that, at s=3.77 GeV, after including the destructive interference between the nonfragmentation and fragmentation contributions, the production rates for e+e−→ρ0ρ0 and ρ0ω can be lowered by about 10% and 30% relative to the fragmentation predictions. Future precise measurement of these exclusive double neutral vector meson production channels at BESIII experiment may provide useful constraints on the LCDAs of light vector mesons. Published by the American Physical Society 2024

Searching for a 0(980)-meson parton distribution function

In this paper, we calculate the scalar a 0(980)-meson leading-twist wave function by using the light-cone harmonic oscillator model (LCHO), where the model parameters are determined by fitting the ξ-moments of its light-cone distribution amplitudes. Then, the a 0(980)-meson leading-twist light-cone distribution amplitudes with three different scales ζ = (1.0, 2.0, 5.2)GeV are given. After constructing the relationship between the a 0(980)-meson leading-twist parton distribution functions/valence quark distribution function and its LCHO wave function, we exhibit the and with different scales. Furthermore, we also calculate the Mellin moments of the a 0(980)-meson’s valence quark distribution function with n = (1, 2, 3), i.e. , and . Finally, the scale evolution for the ratio of the Mellin moments are presented.

Weak radiative decay Lambda _{c}^{+}rightarrow Sigma ^{+}gamma using light-cone sum rules

We calculate the decay width of the Lambda _{c}^{+}rightarrow Sigma ^{+}gamma using light-cone sum rules. For the initial quark radiation an effective Hamiltonian is constructed, where the internal quark line shrinks to a point. The final quark radiation is studied within the full theory. The leading twist light-cone distribution amplitudes of the Sigma ^+ serve as the non-perturbative input for the sum rules calculation, and the perturbative kernel is calculated at leading order. The branching fraction we obtain is mathcal{B}(Lambda _{c}^{+}rightarrow Sigma ^{+}gamma )=1.03pm 0.36 times 10^{-4}, which is below the recent upper limits <2.6 times 10^{-4} and <4.4 times 10^{-4} given by the Belle collaboration and the BESIII collaboration, respectively.

Light-cone distribution amplitudes of heavy mesons with QED effects

We discuss the QED-generalized leading-twist light-cone distribution amplitudes of heavy mesons, that appear in QCD QED factorization theorems for exclusive two-body B decays. In the presence of electrically charged particles, these functions should be more appropriately regarded as soft functions for heavy-meson decays into two back-to-back particles. In this paper, we derive the one-loop anomalous dimension of these soft functions and study their behaviour under renormalization-scale evolution, obtaining an exact solution in Laplace space. In addition, we provide numerical solutions for the soft functions and analytical solutions to all orders in the strong and to first order in the electromagnetic coupling. For the inverse (and inverse-logarithmic) moments, we obtain an all-order solution in both couplings. We further provide numerical estimates for QED corrections to the inverse moments.

Light-cone sum rules analysis of Xi _{QQ^{prime }q}rightarrow Lambda _{Q^{prime }} weak decays

We analyze the weak decay of doubly-heavy baryon decays into anti-triplets Lambda _Q with light-cone sum rules. To calculate the decay form factors, both bottom and charmed anti-triplets Lambda _b and Lambda _c are described by the same set of leading twist light-cone distribution amplitudes. With the obtained form factors, we perform a phenomenology study on the corresponding semi-leptonic decays. The decay widths are calculated and the branching ratios given in this work are expected to be tested by future experimental data, which will help us to understand the underlying dynamics in doubly-heavy baryon decays.

Radiative leptonic decay B \u2192 \u03b3\u2113\u03bd\u2113 with subleading power corrections

We reconsider the QCD predictions for the radiative decay B → γℓνℓ with an energetic photon in the final state by taking into account the 1/Eγ, 1/mb power-suppressed hard-collinear and soft corrections from higher-twist B-meson light-cone distribution amplitudes (LCDAs). The soft contribution is estimated through a dispersion relation and light-cone QCD sum rules. The analysis of theoretical uncertainties and the dependence of the decay form factors on the leading-twist LCDA ϕ+(ω) shows that the latter dominates. The radiative leptonic decay is therefore well suited to constrain the parameters of ϕ+(ω), including the first inverse moment, 1/λB, from the expected high-statistics data of the BELLE II experiment.

Light-cone distribution amplitudes of vector meson in a large momentum effective theory

We investigate the leading twist light-cone distribution amplitudes (LCDAs) of vector meson in the framework of large momentum effective theory. We derive the matching equation for the LCDAs and quasi distribution amplitudes. The matching coefficients are determined to one loop accuracy, both in the ultraviolet cut-off and dimensional regularization schemes. This calculation provides the possibility of studying the full $x$ behavior of LCDAs and extracting LCDAs of vector mesons from lattice simulations.

The leading twist light-cone distribution amplitudes for the S-wave and P-wave Bc mesons

The light-cone distribution amplitudes (LCDAs) serve as important non-perturbative inputs for the study of hard exclusive processes. In this paper, we calculate ten LCDAs at twist-2 for the S-wave and P-wave $B_c$ mesons up to the next-to-leading order (NLO) of the strong coupling $\alpha_s$ and leading order of the velocity expansion. Each one of these ten LCDAs is expressed as a product of a perturbatively calculable distribution and a universal NRQCD matrix-element. By use of the spin symmetry, only two NRQCD matrix-elements will be involved. The reduction of the number of non-perturbative inputs will improve the predictive power of collinear factorization.

The leading twist light-cone distribution amplitudes for the S-wave and P-wave quarkonia and their applications in single quarkonium exclusive productions

In this paper, we calculate twist-2 light-cone distribution amplitudes (LCDAs) of the S-wave and P-wave quarkonia (namely $^1S_0$ state $\eta_{Q}$, $^3S_1$ state $J/\psi(\Upsilon)$, $^1P_1$ state $h_{Q}$ and $^3P_J$ states $\chi_{QJ}$ with $J=0,1,2$ and $Q=c,b$) to the next-leading order of the strong coupling $\alpha_s$ and leading order of the velocity expansion $v$ in the non-relativistic QCD (NRQCD). We apply these LCDAs to some single quarkonium exclusive productions at large center-of-mass energy, such as $\gamma^*\to \eta_Q\gamma, \chi_{QJ}\gamma~(J=0,1,2)$, $Z\to \eta_Q\gamma, \chi_{QJ}\gamma~(J=0,1,2), J/\psi (\Upsilon)\gamma, h_Q\gamma$ and $h\to J/\psi \gamma$, by adopting the collinear factorization. The asymptotic behaviors of those processes obtained in NRQCD factorization are reproduced.

Study of light-cone distribution amplitudes forp-wave heavy mesons

In this paper, a study of light-cone distribution amplitudes for p-wave heavy mesons is presented in both general and heavy quark frameworks. Within the light-front approach, the leading twist light-cone distribution amplitudes, \phi_M(u) and their relevant decay constants of heavy scalar, axial-vector and tensor mesons, f_M, are formulated. The relations of some decay constants can be simplified when the heavy quark limit is taken into account. After fixing the parameters which appear in a Gaussian wave function, the corresponding decay constants are calculated and compared with those of other theoretical approaches. The curves and the first six \xi moments of \phi_M(u) are plotted and estimated. These results all endorse the requirements of heavy quark symmetry.

Analyses of decay constants and light-cone distribution amplitudes fors-wave heavy meson

In this paper, a study of light-cone distribution amplitudes (LCDAs) for $s$-wave heavy meson are presented in both general and heavy quark frameworks. Within the light-front approach, the leading twist light-cone distribution amplitudes, ${\ensuremath{\phi}}_{M}(u)$, and their relevant decay constants of heavy pseudoscalar and vector mesons, ${f}_{M}$, have simple relations. These relations can be further simplified when the heavy quark limit is taken into consideration. After fixing the parameters that appear in both Gaussian and power-law wave functions, the corresponding decay constants are calculated and compared with those of other theoretical approaches. The curves and the first six $\ensuremath{\xi}$-moments of ${\ensuremath{\phi}}_{M}(u)$ are plotted and estimated. A conclusion is drawn from these results: Even though the values of the decay constants of the distinct mesons are almost equal, the curves of their LCDAs may have quite large differences, and vice versa. Additionally, in the heavy quark limit, the leading twist LCDAs, ${\ensuremath{\Phi}}_{Qq}(\ensuremath{\omega})$ and ${\ensuremath{\Phi}}_{Qq}(\ensuremath{\omega})$, are compared with the $B$-meson LCDAs, ${\ensuremath{\psi}}_{+}(\ensuremath{\omega})$, suggested by the other theoretical groups.

Leading-twist pion and kaon distribution amplitudes in the gauge-invariant nonlocal chiral quark model from the instanton vacuum

We investigate the leading-twist light-cone distribution amplitudes for the pion and kaon based on the gauge-invariant nonlocal chiral quark model from the instanton vacuum in the presence of external axial-vector currents. We find that the nonlocal contribution from the gauge invariance has much effects on the pion distribution amplitudes, while it changes mildly the kaon ones. We also study the Gegenbauer moments of the distribution amplitudes and compare them with the empirical analysis of the CLEO data.

Leading-twist pion and kaon distribution amplitudes from the QCD instanton vacuum

We investigate the leading-twist light-cone distribution amplitudes for the pion and kaon, based on the nonlocal chiral quark model from the instanton vacuum. Effects of explicit flavor SU(3)-symmetry breaking are taken into account. The Gegenbauer moments are computed, analyzed and compared with those of other models. The one-loop QCD evolution of the moments is briefly discussed. The transverse momentum distributions are also discussed for the pion and kaon light-cone wave functions.

Charmless hadronicBdecays involving scalar mesons: Implications on the nature of light scalar mesons

The hadronic charmless $B$ decays into a scalar meson and a pseudoscalar meson are studied within the framework of QCD factorization. Based on the QCD sum rule method, we have derived the leading-twist light-cone distribution amplitudes of scalar mesons and their decay constants. Although the light scalar mesons ${f}_{0}(980)$ and ${a}_{0}(980)$ are widely perceived as primarily the four-quark bound states, in practice it is difficult to make quantitative predictions based on the four-quark picture for light scalars. Hence, predictions are made in the 2-quark model for the scalar mesons. The short-distance approach suffices to explain the observed large rates of ${f}_{0}(980){K}^{\ensuremath{-}}$ and ${f}_{0}(980){\overline{K}}^{0}$ that receive major penguin contributions from the $b\ensuremath{\rightarrow}ss\overline{s}$ process. When ${f}_{0}(980)$ is assigned as a four-quark bound state, there exist extra diagrams contributing to $B\ensuremath{\rightarrow}{f}_{0}(980)K$. Therefore, a priori the ${f}_{0}(980)K$ rate is not necessarily suppressed for a four-quark state ${f}_{0}(980)$. The predicted ${\overline{B}}^{0}\ensuremath{\rightarrow}{a}_{0}^{\ifmmode\pm\else\textpm\fi{}}(980){\ensuremath{\pi}}^{\ensuremath{\mp}}$ and ${a}_{0}^{+}(980){K}^{\ensuremath{-}}$ rates exceed the current experimental limits, favoring a four-quark nature for ${a}_{0}(980)$. The penguin-dominated modes ${a}_{0}(980)K$ and ${a}_{0}(1450)K$ receive predominant weak annihilation contributions. There exists a twofold experimental ambiguity in extracting the branching ratio of ${B}^{\ensuremath{-}}\ensuremath{\rightarrow}{\overline{K}}_{0}^{*0}(1430){\ensuremath{\pi}}^{\ensuremath{-}}$, which can be resolved by measuring other ${K}_{0}^{*}(1430)\ensuremath{\pi}$ modes in conjunction with the isospin symmetry consideration. Large weak annihilation contributions are needed to explain the ${K}_{0}^{*}(1430)\ensuremath{\pi}$ data. The decay ${\overline{B}}^{0}\ensuremath{\rightarrow}{\ensuremath{\kappa}}^{+}{K}^{\ensuremath{-}}$ provides a nice ground for testing the 4-quark and 2-quark nature of the $\ensuremath{\kappa}$ meson. It can proceed through $W$-exchange and hence is quite suppressed if $\ensuremath{\kappa}$ is made of two quarks, while it receives a tree contribution if $\ensuremath{\kappa}$ is predominately a four-quark state. Hence, an observation of this channel at the level of $\ensuremath{\gtrsim}{10}^{\ensuremath{-}7}$ may imply a four-quark assignment for the $\ensuremath{\kappa}$. Mixing-induced $CP$ asymmetries in penguin-dominated modes are studied and their deviations from $\mathrm{sin}2\ensuremath{\beta}$ are found to be tiny.

Light-cone distribution amplitudes for the light 11P1mesons

We present a study of light-cone distribution amplitudes of the light $1^1P_1$ mesons. The first few Gegenbauer moments of leading twist light-cone distribution amplitudes are calculated by using the QCD sum rule technique.

B→f0(980)Kdecays and subleading corrections

The decay $B\to f_0(980)K is studied within the framework of QCD factorization and the two-quark scenario for $f_0(980)$. There are two distinct penguin contributions and their interference depends on the unknown mixing angle $\theta$ of strange and nonstrange quark contents of $f_0(980)$: destructive for $0<\theta<\pi/2$ and constructive for $\pi/2<\theta<\pi$. The QCD sum rule method is applied to evaluate the leading-twist light-cone distribution amplitudes and the scalar decay constant of $f_0$. We conclude that the short-distance approach is not adequate to explain the observed large rates of $f_0K^-$ and $f_0\ov K^0$. Among many possible subleading corrections, we study and estimate the contributions from the three-parton Fock states of the $f_0$ and from the intrinsic gluon inside the $B$ meson. It is found that the spectator gluon of the $B$ meson may play an eminent role for the enhancement of $f_0(980)K$. We point out that if $f_0(980)$ is a four-quark state as widely perceived, there will exist extra diagrams contributing to $B\to f_0(980)K$. However, in practice it is difficult to make quantitative predictions based on the four-quark picture for $f_0(980)$ as it involves additional nonfactorizable contributions that are difficult to estimate and the calculations of the decay constant and form factors of $f_0(980)$ are beyond the conventional quark model.

SU(3) breaking inKandK*distribution amplitudes

We calculate the decay couplings and first two Gegenbauer moments of the leading twist light-cone distribution amplitudes of K and ${K}^{*}$ from QCD sum rules, including NLO perturbative effects.