Backward production of a spin parity 1+ϱπ enhancement at 1.04 GeV

Gavillet, Ph.; Bergé, P.; Ferrando, A.; Hemingway, R. J.; Holmgren, S. O.; Losty, M. J.; Marin, J. C.; Montanet, L.; Pagiola, E.; Yamdagni, N.; Blokzijl, R.; Jongejans, B.; Kluyver, J.C.; Massaro, G.; Engeler, J.; Kittel, W.; Vergeest, Joris S. M.; Walle, Rik Van de; Foster, B.; Grossman, Pinhas; Lamb, P. R.; McDowell, W.L.

doi:10.1016/0370-2693(77)90148-4

Cited by 50 publications

(3 citation statements)

References 18 publications

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“…Depending on the analyzed process and the employed parametrizations, the values of the a 1 ð1260Þ parameters differ substantially [94]. The measurements listed by the PDG cover a wide range of mass values from 1041 AE 13 MeV=c 2 [95] Fig. 9, but for the study, in which the a 1 ð1420Þ resonance was also included in the 1 þþ 0 þ ρð770ÞπS and 1 þþ 0 þ f 2 ð1270ÞπP waves.…”

mentioning

confidence: 99%

Light isovector resonances in π−p→π−π−π+p at
Aghasyan¹,
Alexeev²,
Alexeev³
et al. 2018
Phys. Rev. D
73
7
97
0
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We have performed the most comprehensive resonance-model fit of π − π − π þ states using the results of our previously published partial-wave analysis (PWA) of a large data set of diffractive-dissociation events from the reaction π − þ p → π − π − π þ þ p recoil with a 190 GeV=c pion beam. The PWA results, which were obtained in 100 bins of three-pion mass, 0.5 < m 3π < 2.5 GeV=c 2 , and simultaneously in 11 bins of the reduced four-momentum transfer squared, 0.1 < t 0 < 1.0 ðGeV=cÞ 2 , are subjected to a resonance-model fit using Breit-Wigner amplitudes to simultaneously describe a subset of 14 selected waves using 11 isovector light-meson states with J PC ¼ 0 −þ , 1 þþ , 2 þþ , 2 −þ , 4 þþ , and spin-exotic 1 −þ quantum numbers. The model contains the well-known resonances πð1800Þ, a 1 ð1260Þ, a 2 ð1320Þ, π 2 ð1670Þ, π 2 ð1880Þ, and a 4 ð2040Þ. In addition, it includes the disputed π 1 ð1600Þ, the excited states a 1 ð1640Þ, a 2 ð1700Þ, and π 2 ð2005Þ, as well as the resonancelike a 1 ð1420Þ. We measure the resonance parameters mass and width of these objects by combining the information from the PWA results obtained in the 11 t 0 bins. We extract the relative branching fractions of the ρð770Þπ and f 2 ð1270Þπ decays of a 2 ð1320Þ and a 4 ð2040Þ, where the former one is measured for the first time. In a novel approach, we extract the t 0 dependence of the intensity of the resonances and of their phases. The t 0 dependence of the intensities of most resonances differs distinctly from the t 0 dependence of the nonresonant components. For the first time, we determine the t 0 dependence of the phases of the production amplitudes and confirm that the production mechanism of the Pomeron exchange is common to all resonances. We have performed extensive systematic studies on the model dependence and correlations of the measured physical parameters.

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mentioning

confidence: 99%

Light isovector resonances in π−p→π−π−π+p at
Aghasyan¹,
Alexeev²,
Alexeev³
et al. 2018
Phys. Rev. D
73
7
97
0
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“…± 3 (sys.) MeV/c 2 [219]; the values for the a 1 (1260) width range from 230 ± 50 MeV/c 2 [218] to 814 ± 36 (stat.) ± 13 (sys.)…”

Section: Resultsmentioning

confidence: 97%

“…Depending on the analyzed process and the employed parameterizations, the measured values of the a 1 (1260) parameters differ substantially [217]. The reported values for the a 1 (1260) mass cover a wide range from 1041 ± 13 MeV/c 2 [218] to 1331 ± 10 (stat.) ± 3 (sys.)…”

Section: Resultsmentioning

confidence: 99%

Light-Meson Spectroscopy with COMPASS

Ketzer,

Grube,

Ryabchikov

2019

Preprint

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Despite decades of research, we still lack a detailed quantitative understanding of the way quantum chromodynamics (QCD) generates the spectrum of hadrons. Precise experimental studies of the hadron excitation spectrum and the dynamics of hadrons help to improve models and to test effective theories and lattice QCD simulations. In addition, QCD seems to allow hadrons beyond the three-quark and quark-antiquark configurations of the constituent-quark model. These so-called exotic hadrons contain additional constituent (anti)quarks or excited gluonic fields that contribute to the quantum numbers of the hadron. Hadron spectroscopy is currently one of the most active fields of research in hadron physics. The COMPASS experiment at the CERN SPS is studying the excitation spectrum of light mesons, which are composed of up, down, and strange quarks. The excited mesons are produced via the strong interaction, i.e. by Pomeron exchange, by scattering a 190 GeV/c pion beam off proton or nuclear targets. On heavy nuclear targets, in addition the electromagnetic interaction contributes in the form of quasi-real photon exchange at very low four-momentum transfer squared. COMPASS has performed the most comprehensive analyses to date of isovector resonances decaying into ηπ, η π, or π − π − π + final states. In this review, we give a general and pedagogical introduction into scattering theory and the employed partial-wave analysis techniques. We also describe novel methods developed for the high-precision COMPASS data. The COMPASS results are summarized and compared to previous measurements. In addition, we discuss possible signals for exotic mesons and conclude that COMPASS data provide solid evidence for the existence of the manifestly exotic π 1 (1600), which has quantum numbers forbidden for a quark-model state, and of the a 1 (1420), which does not fit into the quark-model spectrum. By isolating the contributions from quasi-real photon exchange, COMPASS has measured the radiative widths of the a 2 (1320) and, for the first time, that of the π 2 (1670) and has tested predictions of chiral perturbation theory for the process π − + γ → π − π − π + .

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Three-Body Phenomenology for Elementary Particle Systems

Aaron

1978

Lecture Notes in Physics

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Backward production of a spin parity 1+ϱπ enhancement at 1.04 GeV

Cited by 50 publications

References 18 publications

Light isovector resonances in π−p→π−π−π+p at
Aghasyan¹,
Alexeev²,
Alexeev³
et al. 2018
Phys. Rev. D
73
7
97
0
View full text Add to dashboard Cite

Light isovector resonances in π−p→π−π−π+p at
Aghasyan¹,
Alexeev²,
Alexeev³
et al. 2018
Phys. Rev. D
73
7
97
0
View full text Add to dashboard Cite

Light-Meson Spectroscopy with COMPASS

Three-Body Phenomenology for Elementary Particle Systems

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Backward production of a spin parity 1+ϱπ enhancement at 1.04 GeV

Cited by 50 publications

References 18 publications

Light isovector resonances in π−p→π−π−π+p at Aghasyan1, Alexeev2, Alexeev3 et al. 2018Phys. Rev. D737970View full textAdd to dashboardCite

Light isovector resonances in π−p→π−π−π+p at Aghasyan1, Alexeev2, Alexeev3 et al. 2018Phys. Rev. D737970View full textAdd to dashboardCite

Light-Meson Spectroscopy with COMPASS

Three-Body Phenomenology for Elementary Particle Systems

Contact Info

Product

Resources

About

Light isovector resonances in π−p→π−π−π+p at
Aghasyan¹,
Alexeev²,
Alexeev³
et al. 2018
Phys. Rev. D
73
7
97
0
View full text Add to dashboard Cite

Light isovector resonances in π−p→π−π−π+p at
Aghasyan¹,
Alexeev²,
Alexeev³
et al. 2018
Phys. Rev. D
73
7
97
0
View full text Add to dashboard Cite