相关论文: Chiral-odd distribution functions in the chiral qu…
We introduce chiral-even and chiral-odd meson wave functions as vacuum-to-meson matrix elements of bilocal quark operators with well-defined (geometric) twist. Thereby, we achieve a Lorentz invariant classification of these distributions…
In the framework of light-cone QCD sum rules, we study the valence quark distribution function $q(x_B)$ of a pion for moderate $x_B$. The sum rule with the leading twist-2 wave function gives $q(x_B)=\varphi_\pi(x_B)$. Twist-4 wave…
The chiral-odd distribution function $h_1$ is discussed in the framework of the renormalon approach. Using a bag-model calculation for $h_1$, we calculate its intrinsic uncertainty due to renormalon poles. The result is given as a function…
Transverse momentum dependent parton distribution functions are a key ingredient in the description of spin and azimuthal asymmetries in deep-inelastic scattering processes. Recent results from non-perturbative calculations in effective…
A global analysis of the experimental data on azimuthal asymmetries in semi-inclusive deep inelastic scattering (SIDIS), from the HERMES and COMPASS Collaborations, and in e+e- --> h1 h2 X processes, from the BELLE Collaboration, is…
Approximate relations among transverse momentum dependent quark distribution functions are established in the framework of the QCD parton model. The validity of such results survives QCD evolution effects, owing to the Politzer theorem on…
We study the azimuthal asymmetries in proton-proton Drell-Yan processes with one incident proton being transversely or longitudinally polarized. We consider particularly the asymmetries contributed by the leading-twist chiral-odd quark…
A formula for the single transverse spin asymmetry in the large-$p_T$ pion production in the nucleon-nucleon collision is derived. We focuss on the chiral-odd contribution where the transversity distribution and the chiral-odd…
We show how quark-hadron duality can emerge for valence spin averaged structure functions, and for the non-forward distributions of Deeply Virtual Compton Scattering. Novel factorisations of the non-forward amplitudes are proposed. Some…
I present some results about transverse momentum dependent distribution and fragmentation functions. Firstly I illustrate a simple model, with predictive power about the energy behavior, for T-odd, chiral odd functions. Moreover I propose a…
We propose new method which allows determination of the strange-sea quark spin distribution in the nucleon through measurement of various inclusive and semi-inclusive polarized deep inelastic electron- or muon-proton reactions. It is shown,…
The photon is a very interesting object for QCD studies since it has both a pointlike coupling to quarks, which yields a perturbative part of photon's wave function, and a non-perturbative coupling related to the magnetic susceptibility of…
We present a study on the beam single spin asymmetries $A_{LU}^{\sin\phi_h}$ of $\pi^+$, $\pi^-$ and $\pi^0$ production in semi-inclusive deep inelastic scattering process, by considering Collins effect and the $g^\perp D_1$ term…
We study the single-transverse spin asymmetry in semi-inclusive hadron production in deep inelastic scattering. We derive the leading contribution to the asymmetry at moderate transverse momentum $P_{h\perp}$ of the produced hadron in terms…
The transverse single-spin asymmetry for $\rho^0$ production in semi-inclusive deep inelastic scattering was recently reported by the COMPASS Collaboration. Using the Sivers functions extracted from pion and kaon productions, we perform a…
Various issues surrounding a recently proposed inequality among twist-two quark distributions in the nucleon are discussed. We provide a rigorous derivation of the inequality in QCD, including radiative corrections and scale dependence. We…
Generalized parton distributions describe the distribution of partons in the transverse plane. For transversely polarized quarks and/or nucleons, these impact parameter dependent parton distributions are not axially symmetric. These…
The COMPASS Collaboration is measuring the asymmetries in the azimuthal distributions of positive and negative hadrons produced in Deep Inelastic Scattering (DIS) on unpolarized protons. The data have been collected in 2016 and 2017 with a…
We study the Wigner functions of the nucleon which provide multidimensional images of the quark distributions in phase space and combine in a single picture all the information contained in the generalized parton distributions (GPDs) and…
We define twist-two and twist-three quark fragmentation functions in Quantum Chromodynamics (QCD) and study their physical implications. Using this formalism we show how the nucleon's transversity distribution can be measured in single pion…