Photoproduction of $$\pi^+ \pi^-$$ meson pairs on the proton

Journal Article · Thu Oct 01 04:00:00 EDT 2009 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.80.072005· OSTI ID:980905

DeVita, Raffaella ^[1]; Szczepaniak, Adam P. ^[2]

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1. Istituto Nazionale di Fisica Nucleare (INFN) - Sezione di Genova
2. Indiana Univ., Bloomington, IN (United States)

The exclusive reaction $$\gamma p \to p \pi^+ \pi^-$$ was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range $0.4<-t<1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was about 20 pb$$^{-1}$$. The reaction was isolated by detecting the $$\pi^+$$ and proton in CLAS, and reconstructing the $$\pi^-$$ via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the $$S$$, $$P$$, and $$D$$-waves in the $$M_{\pi^+\pi^-}$$ mass range $0.4-1.4$ GeV were derived performing a partial wave expansion of the extracted moments. Besides the dominant contribution of the $$\rho(770)$$ meson in the $$P$$-wave, evidence for the $$f_0(980)$$ and the $$f_2(1270)$$ mesons was found in the $$S$$ and $$D$$-waves, respectively. The differential production cross sections $$d\sigma/dt$$ for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the $$f_0(980)$$ has been measured in a photoproduction experiment.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
• Contributing Organization: CLAS Collaboration
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 980905
• Report Number(s): JLAB-PHY-09-1040; DOE/OR/23177-0925
• Journal Information: Physical Review D, Journal Name: Physical Review D Journal Issue: 7 Vol. 80
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
CEBAF ACCELERATOR
CROSS SECTIONS
D WAVES
DATA
DECAY
DIFFERENTIAL CROSS SECTIONS
ENERGY RANGE
EXPANSION
LUMINOSITY
MASS
MESONS
MISSING MASS
MOMENTUM TRANSFER
PARTIAL WAVES
PHOTONS
PHOTOPRODUCTION
PROTONS
RANGE
YIELDS