Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for a narrow sigma(770) resonance and its suppression in pipi
  scattering from measurements of pi(-)p->pi(-)pi(+)n on polarized target at
  17.2 GeV/c   We present a new model independent amplitude analysis of reaction
pi(-)p->pi(-) pi(+)n measured at CERN at 17.2 GeV/c on polarized target using a
Monte Carlo method for dipion mass 580-1080 MeV. The two solutions for measured
moduli |Sbar|^2 and |S|^2 of the two S-wave transversity amplitudes Sbar and S
show res onant behaviour below 800 MeV corresponding to a scalar resonance
sigma(770). Simultaneous fits to |Sbar|^2 and |S|^2 include f_0(980). The CERN
data on polar ized target supplemented by the assumption of analyticity of
production amplitud es in dipion mass allow to determine the helicity
amplitudes S_0 (a_1 exchange) and S_1 (pi exchange) from fitted transversity
amplitudes. The sign ambiguity in sigma(770) contribution leads to 2 solutions.
In the "down" solution sigma(770) is suppressed in the helicity flip amplitude
S_1 and thus also in pi(-)pi(+)-> pi(-)pi(+) scattering. Most contribution of
sigma(770) to pion production is in the nonflip amplitude S_0, or in
pi(-)a_1(+)->pi(-)pi(+) scattering. In the "up" solution the situation is
reversed. The "up" solution is excluded by unitarity in pipi scattering. The
"down" solution, and thus the evidence for sigma(770), is in agreement with
unitarity in both pi(-)pi(+)->pi(-)pi(+) and pi(-)a_1(+)-> pi(-)pi(+)
scattering. There are 4 "down" solutions (1, 1bar), (2, 1bar), (1, 2bar) and
(2, 2bar). The sigma(770) resonance manifests itself as a broad resonant
structure at ~ 720 MeV in the flip amplitude |S_1|^2 in solutions (1, 1bar) and
(2, 1bar). The contribution of sigma(770) to |S_1|^2 is small in solutions (1,
2bar) and (2, 2bar). The metamorphosis of a narrow sigma(770) in the nonflip
amplitude S_0 into a broad resonant structure in the flip amplitude S_1 is a
new phenomenon related to breaking of scale and chiral symmetry in QCD.

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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: astro-ph
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The categories of this paper are: cs