Observation of Beam Spin Asymmetries in the Process e p → e ′ π + π − X with CLAS12
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73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Engineering topics
D’Angelo, A.
Publications and source records attributed to D’Angelo, A..
Photoproduction of the f 2 ( 1270 ) Meson Using the CLAS Detector
The quark structure of the f 2 ( 1270 ) meson has, for many years, been assumed to be a pure quark-antiquark (q$\bar{q}$) resonance with quantum numbers J PC = 2 ++ . Recently, it was proposed that the f 2 ( 1270 ) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ → π + π - , whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction γp → π 0 π 0 p , using the CEBAF Large Acceptance Spectrometer detector at Jefferson Lab for incident beam energies between 3.6 and 5.4 GeV. Differential cross sections, dσ/dt , for f 2 ( 1270 ) photoproduction are extracted with good precision due to low backgrounds and are compared to theoretical calculations.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Extraction of Beam-Spin Asymmetries from the Hard Exclusive π + Channel off Protons in a Wide Range of Kinematics
We have measured beam-spin asymmetries to extract the $\sin\phi$ moment $A_{LU}^{\sin\phi}$ from the hard exclusive $\vec{e} p \to e^\prime n \pi^+$ reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center-of-mass. The $A_{LU}^{\sin\phi}$ moment has been measured up to 6.6 GeV$^{2}$ in $-t$, covering the kinematic regimes of Generalized Parton Distributions (GPD) and baryon-to-meson Transition Distribution Amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found $A_{LU}^{\sin\phi}$ to be negative, while a sign change was observed near 90$^\circ$ in the center-of-mass. The unique results presented in this paper will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
The CLAS12 Forward Tagger
This document presents the technical layout and the performance of the CLAS12 Forward Tagger (FT). The FT, composed of an electromagnetic calorimeter based on PbWO$_4$ crystals (FT-Cal), a scintillation hodoscope (FT-Hodo), and several layers of Micromegas trackers (FT-Trk), has been designed to detect electrons and photons scattered at polar angles from 2$^\circ$ to 5$^\circ$ and to meet the physics goals of the hadron spectroscopy program and other experiments running with the CLAS12 spectrometer in Hall B.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗