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Title: Photoproduction of the f1(1285) meson

The $$f_1(1285)$$ meson with mass $$1281.0 \pm 0.8$$ MeV/$c^2$ and width $$18.4 \pm 1.4$$ MeV (FWHM) was measured for the first time in photoproduction from a proton target using CLAS at Jefferson Lab. Differential cross sections were obtained via the $$\eta\pi^{+}\pi^{-}$$, $$K^+\bar{K}^0\pi^-$$, and $$K^-K^0\pi^+$$ decay channels from threshold up to a center-of-mass energy of 2.8 GeV. The mass, width, and an amplitude analysis of the $$\eta\pi^{+}\pi^{-}$$ final-state Dalitz distribution are consistent with the axial-vector $J^P=1^+$ $$f_1(1285)$$ identity, rather than the pseudoscalar $0^-$ $$\eta(1295)$$. The production mechanism is more consistent with $s$-channel decay of a high-mass $N^*$ state, and not with $t$-channel meson exchange. Decays to $$\eta\pi\pi$$ go dominantly via the intermediate $$a_0^\pm(980)\pi^\mp$$ states, with the branching ratio $$\Gamma(a_0\pi \text{ (no} \bar{K} K\text{)}) / \Gamma(\eta\pi\pi \text{(all)}) = 0.74\pm0.09$$. The branching ratios $$\Gamma(K \bar{K} \pi)/\Gamma(\eta\pi\pi) = 0.216\pm0.033$$ and $$\Gamma(\gamma\rho^0)/\Gamma(\eta\pi\pi) = 0.047\pm0.018$$ were also obtained. The first is in agreement with previous data for the $$f_1(1285)$$, while the latter is lower than the world average.
Authors:
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  1. Carnegie Mellon Univ., Pittsburgh, PA (United States)
Publication Date:
OSTI Identifier:
1256692
Report Number(s):
JLAB-PHY-16-2270; DOE/OR/23177-3815; arXiv:1604.07425
Journal ID: ISSN 2469-9985; PRVCAN
DOE Contract Number:
FG02-87ER40315; AC05-06OR23177; ST/J000175
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C; Journal Volume: 93; Journal Issue: 6
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE; USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Orgs:
CLAS Collaboration
Country of Publication:
United States
Language:
English