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Exclusive photoproduction cross sections have been measured for the process $gamma p rightarrow ppi^0(e^+e^-(gamma))$ with the Dalitz decay final state using tagged photon energies in the range of $E_{gamma} = 1.275-5.425$ GeV. The complete angular distribution of the final state $pi^0$, for the entire photon energy range up to large values of $t$ and $u$, has been measured for the first time. The data obtained show that the cross section $dsigma/dt$, at mid to large angles, decreases with energy as $s^{-6.89pm 0.26} $. This is in agreement with the perturbative QCD quark counting rule prediction of $s^{-7} $. Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD based Generalized Parton Distribution mechanism at highest available invariant energy $s=11$ GeV$^2$. At the same time, the Regge exchange based models for $pi^0$ photoproduction are more consistent with experimental data.
Exclusive photoproduction of $rho^0(770)$ mesons is studied using the H1 detector at the $ep$ collider HERA. A sample of about 900000 events is used to measure single- and double-differential cross sections for the reaction $gamma p to pi^{+}pi^{-}Y$
Exclusive $pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $phi_pi$, in the $Q^2$
Exclusive neutral-pion electroproduction ($epto e^prime p^prime pi^0$) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4sigma/dtdQ^2dx_Bdphi_pi$ and structure functions $sigma_T+epsilo
A search for charmless three-body decays of $B^0$ and $B_{s}^0$ mesons with a $K_{rm S}^0$ meson in the final state is performed using the $pp$ collision data, corresponding to an integrated luminosity of $1.0,mbox{fb}^{-1}$, collected at a centre-of
We report the first measurement of the $T$-odd moments in the decay $D^{0} rightarrow K_{S}^{0} pi^{+} pi^{-} pi^{0}$ from a data sample corresponding to an integrated luminosity of $966,{rm fb}^{-1}$ collected by the Belle experiment at the KEKB asy