Kinematical higher-twist corrections in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>γ</mml:mi><mml:mo>*</mml:mo></mml:msup><mml:mi>γ</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>M</mml:mi><mml:mover accent="true"><mml:mi>M</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover></mml:math>

نویسندگان

چکیده

We estimate kinematical higher-twist (up to twist 4) corrections the ${\ensuremath{\gamma}}^{*}({q}_{1})\ensuremath{\gamma}({q}_{2})\ensuremath{\rightarrow}M({p}_{1})\overline{M}({p}_{2})$ amplitudes at large ${Q}^{2}=\ensuremath{-}{q}_{1}^{2}$ and small $s=({q}_{1}+{q}_{2}{)}^{2}$, where $M$ is a scalar or pseudoscalar meson. This process known factorize leading into perturbatively calculable coefficient function generalized distribution (GDAs). The contributions of order $s/{Q}^{2}$ ${m}^{2}/{Q}^{2}$ turn out be important in cross section, considering kinematics accessible Belle II. present numerical estimates for section ${\ensuremath{\gamma}}^{*}\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ with $\ensuremath{\pi}\ensuremath{\pi}$ GDA extracted from measurements asymptotic as inputs study magnitude corrections. To see how target mass affect we also perform calculation ${\ensuremath{\gamma}}^{*}\ensuremath{\gamma}\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\eta}$ by using model $\ensuremath{\eta}\ensuremath{\eta}$ GDA. In range $s&gt;1\text{ }\text{ }{\mathrm{GeV}}^{2}$, account $\ensuremath{\sim}15%$ total an effect which not negligible. Since GDAs are best way access pion energy-momentum tensor (EMT), our demonstrates that accurate evaluation EMT form factors requires inclusion contributions.

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ژورنال

عنوان ژورنال: Physical review

سال: 2022

ISSN: ['0556-2813', '1538-4497', '1089-490X']

DOI: https://doi.org/10.1103/physrevd.106.094030