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

The CLAS collaboration Battaglieri, M. ; De Vita, R. ; Szczepaniak, A.P. ; et al.
Phys.Rev.D 80 (2009) 072005, 2009.
Inspire Record 825040 DOI 10.17182/hepdata.74824

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.

198 data tables

Moments YLM(LM=00) of the di-pion angular distribution for -T.

Moments YLM(LM=00) of the di-pion angular distribution for -T.

Moments YLM(LM=00) of the di-pion angular distribution for -T.

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Observation of the Selective Coupling of $K^*$ States to the $K^- \eta$ Channel

Aston, D. ; Awaji, N. ; Bienz, T. ; et al.
Phys.Lett.B 201 (1988) 169-175, 1988.
Inspire Record 250272 DOI 10.17182/hepdata.30009

The K − η effective mass spectrum in the reaction K − p→K − π + π − π 0 p at 11 GeV/ c has a prominent peak at ≈1.75 GeV/ c 2 , which is shown to be due to the K 3 ∗ (1780) by a spherical harmonic moments analysis and amplitude decomposition; there is no significant signal for K 2 ∗ (1430). The measured branching fractions for the leading L =1 and L =2 K ∗, s, [BF(K 2 ∗ (1430)→Kη) <0.45% at the 95% CL and BF ( K 3 ∗ (1780)→ Kη )=9.4±3.4%] confirm the SU(3) prediction that the Kη channel couples preferentially to odd spin K *, s.

2 data tables

Numerical data of acceptance corrected spherical harmonic moments requested from authors.

Including systematic error.


Observation of the Leading $K^*$ L Excitation Series From $J P=1$- Through 5- in the Reaction $K^- p \to K^- \pi^+ n$ at 11 GeV/$c$

Aston, D. ; Awaji, N. ; D'Amore, J. ; et al.
Phys.Lett.B 180 (1986) 308, 1987.
Inspire Record 231083 DOI 10.17182/hepdata.6544

High statistics data for the reaction K − p→K − π + n at 11 GeV / c have been obtained in the LASS spectrometer at SLAC. A spherical harmonic moments analysis provides clear evidence for the production of the complete leading orbitally excited K ∗ series up through J P = 5 − . New measurements are made of the masses and widths of the 1 − K ∗ (892), 2 + K ∗ (1430 ), 3 − K ∗ (1780), and 4 + K ∗ (2060), and evidence is presented for the production of a new K ∗ state at 2382 MeV / c 2 with spin-parity 5 − .

21 data tables

Unnormalised acceptance corrected spherical moments.

Correlation matrices.

Correlation matrices.

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F0 (1270) Production in the Reaction pi- p --> pi+ pi- n at 12-GeV/c and 15-GeV/c

Alexander, G. ; Dagan, S. ; Gnat, Y. ; et al.
Nucl.Phys.B 131 (1977) 365-385, 1977.
Inspire Record 127448 DOI 10.17182/hepdata.35193

The production of the f 0 (1270) has been studied in the reaction π − p → π + π − n at 12 and 15 GeV/ c in the momentum transfer range 0.02 to 0.80 GeV 2 . Differential and total cross sections for the reaction π − p → f 0 n have been determined. The f 0 decay density matrix elements have been evaluated requiring all the matrix eigenvalues to be non-negative. The relative unnatural and natural parity exchange contributions to the f 0 production have been studied. The results are compared with a Regge exchange model formulated in terms of the pion and A 2 exchanges including cut contributions.

7 data tables

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