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Register a new userHeavy-flavor photo- and electroproduction at NLO
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Authors
I. Schienbein
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We review one-particle inclusive production of heavy-flavored hadrons in a framework which resums the large collinear logarithms through the evolution of the FFs and PDFs and, at the same time, retains the full dependence on the heavy-quark mass without additional theoretical assumptions. The main focus is on the production of D^* mesons in deep inelastic electron--proton scattering at HERA. We show results, neglecting for the time being the heavy-quark mass terms, for deep inelastic D^* meson production at finite transverse momenta. Work to implement this process in the above mentioned massive QCD framework is in progress.
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We compute the exclusive electroproduction, $gamma^* p rightarrow V p$, of heavy quarkonia $V$ to NLO in the collinear factorisation scheme, which has been formally proven for this process. The inclusion of an off-shell virtuality $Q^2$ carried by the photon extends the photoproduction phase space of the exclusive heavy quarkonia observable to electroproduction kinematics. This process is relevant for diffractive scattering at HERA and the upcoming EIC, as well as at the proposed LHeC and FCC.
The relativistic amplitudes of pion photo- and electroproduction are calculated by dispersion relations at constant t. Several sum rules and low-energy theorems for the threshold amplitudes are investigated within this technique. The continuation of the amplitudes to sub-threshold kinematics is shown to provide a unique framework to derive the low-energy constants of chiral perturbation theory by global properties of the excitation spectrum.
We discuss the extended on-mass-shell scheme for manifestly Lorentz-invariant baryon chiral perturbation theory. We present a calculation of pion photo- and electroproduction up to and including order $q^4$. The low-energy constants have been fixed by fitting experimental data in all available reaction channels. Our results can be accessed via a web interface, the so-called chiral MAID (http://www.kph.uni-mainz.de/MAID/chiralmaid/). We explain how our program works and how it can be used for further analysis.
An exact expression is derived for the meson production current off the nucleon for real and virtual photons which cleanly separates, in a model-independent manner, a tree-level expression that manifestly preserves local gauge invariance in terms of a generalized Ward-Takahashi identity from transverse final-state-interaction (FSI) terms. As discussed in some detail, this exact formulation is particularly well suited for implementing approximation schemes of exchange-current and FSI contributions (which in practice generally will be necessary) at any level of sophistication without violating local gauge invariance.
The process of exclusive electroproduction of vector quarkonium (EEQ), $e pto epV$, is per se an interesting topic in studies of quarkonium production mechanism, QCD description of diffractive interaction and nucleon structure. We investigate this process in the framework of nonrelativistic QCD and QCD collinear factorization at the next-to-leading order QCD accuracy. The perturbative convergence behavior is discussed in a large range of photon virtuality $Q^2$. The $J/psi$ large-$Q^2$ electroproduction data at HERA can be well explained, and the $Upsilon$ differential production rate is predicted. The uncertainties in theoretical predictions with radiative corrections are greatly reduced. Notice the EEQ process is extremely sensitive to the gluon distribution in nucleon, the generalized parton distribution, our results will constraint the gluon density with high precision while confronting to the future experimental data. For the sake of comparing convenience, the analytic expressions are provided.
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