Related papers: Two Photon Distribution Amplitudes
We develop an impact representation for the generalized distribution amplitude which describes the exclusive hadronization of a quark-antiquark pair to a pair of mesons. Experiments such as gamma^* gamma -> pi pi and gamma^* N -> pi pi N'…
We describe the physical relativity of light and matter quantum subsystems, their correlations, and energy exchanges. We examine the most commonly adopted definitions of atoms and photons, noting the significant difference in their…
Using methods from soft-collinear and heavy-quark effective theory, a systematic factorization analysis is performed for the $\bar B\to X_s\gamma$ photon spectrum in the endpoint region $m_b-2E_\gamma={\cal O}(\Lambda_{\rm QCD})$. It is…
We report on a recent calculation of the generalized parton distributions (GPDs) of the photon when the momentum transfer in the transverse direction is non-zero. We use an overlap representation of the photon GPDs in terms of the photon…
We generalise the factorization of abelian gauge theory amplitudes to next-to-leading power (NLP) in a soft scale expansion, following a recent generalisation for Yukawa theory. From an all-order power counting analysis of leading and…
We present a next-to-leading order calculation of jet production in gamma^*gamma collisions from e+e- scattering in a region where the virtuality Q^2 of the probing virtual photon is small compared to the transverse jet energy. The…
The theory of linear acceleration emission is developed for a large amplitude electrostatic wave in which all particles become highly relativistic in much less than a wave period. An Airy integral approximation is shown to apply near the…
Forward scattering amplitude of the virtual longitudinal photon at zero energy on electron in QED in the limit of small photon virtualities is calculated. The first radiation corrections are taken into account. Two terms in the expansion…
We discuss in detail the photon structure function beyond the leading logarithm approximation. Of special concern is the factorization scheme and the hadronic input; we show how to naturally absorb large terms due to the MSbar factorization…
We derive factorization relations for the transverse helicity amplitudes in the rare decays B-> K\pi l+l- at leading order in Lambda/m_b, in the kinematical region with an energetic kaon and a soft pion. We identify and compute a new…
For one-mode light described by the Wigner function of generic Gaussian form the photon distribution function is obtained explicitly and expressed in terms of Hermite polynomials of two variables.The mean values and dispersions of photon…
The theorem is proved, determining the forward scatterring amplitude of virtual longitudinal photon at zero energy on any hadronic target in the limit of small photon virtualities $Q^2$. The theorem is strict, based only on Lorenz and gauge…
The subject of cosmological hydrogen recombination has received much attention recently because of its importance to predictions for and cosmological constraints from CMB observations. While the central role of the two-photon decay 2s->1s…
We show how the parton distributions in the photon can be accurately measured in the photoproduction of large-pt jets at HERA. A short review is given of the beyond Leading Logarithm formalism for the photon structure function, with a…
The organization of finite order QCD approximations to $F_2^{\gamma}(x,Q^2)$ based on the separation of pure QED contribution from those of genuine QCD nature is discussed.
The ability to harness light-matter interactions at the few-photon level plays a pivotal role in quantum technologies. Single photons - the most elementary states of light - can be generated on-demand in atomic and solid state emitters.…
We consider two simple covariant models for pions (one with scalar and the other with spin-1/2 constituents). Pion generalized parton distributions are derived by integration over the light-cone energy. The model distributions are…
We present a short overview over the different contributions to high energy photon photon scattering and explore the possibilities of tuning the sizes of the scattered objects by changing the virtuality of the photons. We compare the…
Higher (2nd)-order Wigner distribution function in quantum phase space for entangled bi-modal coherent states, a representative of higher (2nd)-order optical-polarization, is introduced by generalizing kernel (transiting) operator in…
We lay out the basis of factorization at the amplitude level for processes involving the entire Standard Model. The factorization appears in a generalized eikonal approximation in which we expand around a quasi-soft limit for massive gauge…