g11

Spokesperson

M. Battaglieri

Year

2009

Abstract

The exclusive reaction γp -> pπ⁺π⁻ was studied in the photon energy range 3.0-3.8 GeV and momentum transfer range 0.4 < −t < 1.0 GeV2. 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 π⁺ and proton in CLAS, and reconstructing the π⁻ 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_π⁺π⁻ mass range 0.4 − 1.4 GeV were derived performing a partial wave expansion of the extracted moments. Besides the dominant contribution of the ρ(770) meson in the P-wave, evidence for the f₀(980) and the f₂(1270) mesons was found in the S and D-waves, respectively. The differential production cross sections dσ/dt for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the f₀(980) has been measured in a photoproduction experiment.

Comment

-t variable bin width is +/- 0.5 GeV² for all measurements.

Publications

M. Battaglieri, R. De Vita, A. P. Szczepaniak, and CLAS Collaboration Photoproduction of π⁺π^- meson pairs on the proton. // PRD 80, 072005 (2009)
M. Battaglieri, R. De Vita, A. P. Szczepaniak, and CLAS Collaboration First measurement of direct f₀(980) photoproduction on the proton // PRL 102, 102001 (2009)

Quantities

dσ/dt ρ_s⁰_0,0 d²σ_s/dt dM_ππ d²σ_p/dt dM_ππ ρ_s⁰_1,0 d²σ_p-/dt dM_ππ d²σ_p0/dt dM_ππ d²σ_p+/dt dM_ππ d²σ_d/dt dM_ππ d²σ_d-/dt dM_ππ d²σ_d0/dt dM_ππ d²σ_d+/dt dM_ππ d²σ_f/dt dM_ππ d²σ_f-/dt dM_ππ d²σ_f0/dt dM_ππ d²σ_f+/dt dM_ππ ρ⁰_0,0 ρ⁰_1,0 ρ⁰_1,-1 Y₀₀ Y₁₀ Y₁₁ Y₂₀ Y₂₁ Y₂₂ Y₃₀ Y₃₁ Y₃₂ Y₃₃ Y₄₀ Y₄₁ Y₄₂ Y₄₃ Y₄₄

Measurements

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ID	Quantity	Beam	Target	Final state	W_min, GeV	W_max, GeV
E28M1	Y₀₀	γ	p	π⁺π⁻p	2.55	2.62
E28M2	Y₀₀	γ	p	π⁺π⁻p	2.62	2.69
E28M3	Y₀₀	γ	p	π⁺π⁻p	2.69	2.76
E28M4	Y₀₀	γ	p	π⁺π⁻p	2.76	2.83
E28M5	Y₁₀	γ	p	π⁺π⁻p	2.55	2.62
E28M6	Y₁₀	γ	p	π⁺π⁻p	2.62	2.69
E28M7	Y₁₀	γ	p	π⁺π⁻p	2.69	2.76
E28M8	Y₁₀	γ	p	π⁺π⁻p	2.76	2.83
E28M9	Y₁₁	γ	p	π⁺π⁻p	2.55	2.62
E28M10	Y₁₁	γ	p	π⁺π⁻p	2.62	2.69
E28M11	Y₁₁	γ	p	π⁺π⁻p	2.69	2.76
E28M12	Y₁₁	γ	p	π⁺π⁻p	2.76	2.83
E28M13	Y₂₀	γ	p	π⁺π⁻p	2.55	2.62
E28M14	Y₂₀	γ	p	π⁺π⁻p	2.62	2.69
E28M15	Y₂₀	γ	p	π⁺π⁻p	2.69	2.76
E28M16	Y₂₀	γ	p	π⁺π⁻p	2.76	2.83
E28M17	Y₂₁	γ	p	π⁺π⁻p	2.55	2.62
E28M18	Y₂₁	γ	p	π⁺π⁻p	2.62	2.69
E28M19	Y₂₁	γ	p	π⁺π⁻p	2.69	2.76
E28M20	Y₂₁	γ	p	π⁺π⁻p	2.76	2.83
E28M21	Y₂₂	γ	p	π⁺π⁻p	2.55	2.62
E28M22	Y₂₂	γ	p	π⁺π⁻p	2.55	2.62
E28M23	Y₂₂	γ	p	π⁺π⁻p	2.69	2.76
E28M24	Y₂₂	γ	p	π⁺π⁻p	2.76	2.83
E28M25	Y₃₀	γ	p	π⁺π⁻p	2.55	2.62
E28M26	Y₃₀	γ	p	π⁺π⁻p	2.62	2.69
E28M27	Y₃₀	γ	p	π⁺π⁻p	2.69	2.76
E28M28	Y₃₀	γ	p	π⁺π⁻p	2.76	2.83
E28M29	Y₃₁	γ	p	π⁺π⁻p	2.55	2.62
E28M30	Y₃₁	γ	p	π⁺π⁻p	2.62	2.69
E28M31	Y₃₁	γ	p	π⁺π⁻p	2.69	2.76
E28M32	Y₃₁	γ	p	π⁺π⁻p	2.76	2.83
E28M33	Y₃₂	γ	p	π⁺π⁻p	2.55	2.62
E28M34	Y₃₂	γ	p	π⁺π⁻p	2.62	2.69
E28M35	Y₃₂	γ	p	π⁺π⁻p	2.69	2.76
E28M36	Y₃₂	γ	p	π⁺π⁻p	2.76	2.83
E28M37	Y₃₃	γ	p	π⁺π⁻p	2.55	2.62
E28M38	Y₃₃	γ	p	π⁺π⁻p	2.62	2.69
E28M39	Y₃₃	γ	p	π⁺π⁻p	2.69	2.76
E28M40	Y₃₃	γ	p	π⁺π⁻p	2.76	2.83
E28M41	Y₄₀	γ	p	π⁺π⁻p	2.55	2.62
E28M42	Y₄₀	γ	p	π⁺π⁻p	2.62	2.69
E28M43	Y₄₀	γ	p	π⁺π⁻p	2.69	2.76
E28M44	Y₄₀	γ	p	π⁺π⁻p	2.76	2.83
E28M45	Y₄₁	γ	p	π⁺π⁻p	2.55	2.62
E28M46	Y₄₁	γ	p	π⁺π⁻p	2.62	2.69
E28M47	Y₄₁	γ	p	π⁺π⁻p	2.69	2.76
E28M48	Y₄₁	γ	p	π⁺π⁻p	2.76	2.83
E28M49	Y₄₂	γ	p	π⁺π⁻p	2.55	2.62
E28M50	Y₄₂	γ	p	π⁺π⁻p	2.62	2.69
E28M51	Y₄₂	γ	p	π⁺π⁻p	2.69	2.76
E28M52	Y₄₂	γ	p	π⁺π⁻p	2.76	2.83
E28M53	Y₄₃	γ	p	π⁺π⁻p	2.55	2.62
E28M54	Y₄₃	γ	p	π⁺π⁻p	2.62	2.69
E28M55	Y₄₃	γ	p	π⁺π⁻p	2.69	2.76
E28M56	Y₄₃	γ	p	π⁺π⁻p	2.76	2.83
E28M57	Y₄₄	γ	p	π⁺π⁻p	2.55	2.62
E28M58	Y₄₄	γ	p	π⁺π⁻p	2.62	2.69
E28M59	Y₄₄	γ	p	π⁺π⁻p	2.69	2.76
E28M60	Y₄₄	γ	p	π⁺π⁻p	2.76	2.83
E28M61	Y₀₀	γ	p	π⁺π⁻p	2.55	2.62
E28M62	Y₀₀	γ	p	π⁺π⁻p	2.62	2.69
E28M63	Y₀₀	γ	p	π⁺π⁻p	2.69	2.76
E28M64	Y₀₀	γ	p	π⁺π⁻p	2.76	2.83
E28M65	Y₁₀	γ	p	π⁺π⁻p	2.55	2.62
E28M66	Y₁₀	γ	p	π⁺π⁻p	2.62	2.69
E28M67	Y₁₀	γ	p	π⁺π⁻p	2.69	2.76
E28M68	Y₁₀	γ	p	π⁺π⁻p	2.76	2.83
E28M69	Y₁₁	γ	p	π⁺π⁻p	2.55	2.62
E28M70	Y₁₁	γ	p	π⁺π⁻p	2.62	2.69
E28M71	Y₁₁	γ	p	π⁺π⁻p	2.69	2.76
E28M72	Y₁₁	γ	p	π⁺π⁻p	2.76	2.83
E28M73	Y₂₀	γ	p	π⁺π⁻p	2.55	2.62
E28M74	Y₂₀	γ	p	π⁺π⁻p	2.62	2.69
E28M75	Y₂₀	γ	p	π⁺π⁻p	2.69	2.76
E28M76	Y₂₀	γ	p	π⁺π⁻p	2.76	2.83
E28M77	Y₂₁	γ	p	π⁺π⁻p	2.55	2.62
E28M78	Y₂₁	γ	p	π⁺π⁻p	2.62	2.69
E28M79	Y₂₁	γ	p	π⁺π⁻p	2.69	2.76
E28M80	Y₂₁	γ	p	π⁺π⁻p	2.76	2.83
E28M81	Y₂₂	γ	p	π⁺π⁻p	2.55	2.62
E28M82	Y₂₂	γ	p	π⁺π⁻p	2.62	2.69
E28M83	Y₂₂	γ	p	π⁺π⁻p	2.69	2.76
E28M84	Y₂₂	γ	p	π⁺π⁻p	2.76	2.83
E28M85	Y₃₀	γ	p	π⁺π⁻p	2.55	2.62
E28M86	Y₃₀	γ	p	π⁺π⁻p	2.62	2.69
E28M87	Y₃₀	γ	p	π⁺π⁻p	2.69	2.76
E28M88	Y₃₀	γ	p	π⁺π⁻p	2.76	2.83
E28M89	Y₃₁	γ	p	π⁺π⁻p	2.55	2.62
E28M90	Y₃₁	γ	p	π⁺π⁻p	2.62	2.69
E28M91	Y₃₁	γ	p	π⁺π⁻p	2.69	2.76
E28M92	Y₃₁	γ	p	π⁺π⁻p	2.76	2.83
E28M93	Y₃₂	γ	p	π⁺π⁻p	2.55	2.62
E28M94	Y₃₂	γ	p	π⁺π⁻p	2.62	2.69
E28M95	Y₃₂	γ	p	π⁺π⁻p	2.69	2.76
E28M96	Y₃₂	γ	p	π⁺π⁻p	2.76	2.83
E28M97	Y₄₀	γ	p	π⁺π⁻p	2.55	2.62
E28M98	Y₄₀	γ	p	π⁺π⁻p	2.62	2.69
E28M99	Y₄₀	γ	p	π⁺π⁻p	2.69	2.76
E28M100	Y₄₀	γ	p	π⁺π⁻p	2.76	2.83

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CLAS Physics Database

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Measurements