publication . Other literature type . Article . Preprint . 2015

Observation of a new narrow axial-vector meson $a_1(1420)$

A. Magnon; Maria Liz Crespo; A. Lehmann; M. Virius; Bernhard Franz Ketzer; Bernhard Franz Ketzer; M. Slunecka; J. Pretz; J. Pretz; S. Levorato; ...
Open Access English
  • Published: 19 Aug 2015
  • Country: Italy
Abstract
The COMPASS collaboration at CERN has measured diffractive dissociation of 190 GeV/$c$ pions into the $\pi^-\pi^-\pi^+$ final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of $3\pi$ mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow $J^{PC} = 1^{++}$ signal is observed in the $f_0(980)\,\pi$ channel. We present a resonance-model study of a subset of the spin-density matrix selecting $3\pi$ states with $J^{PC} = 2^{++}$ and $4^{++}$ decaying into $\rho(770)\,\pi$ and with $J^{PC} = 1^{++}$ decaying into $f_0(980)\,\pi$. We identify a new $a_1$ mes...
Subjects
arXiv: High Energy Physics::ExperimentNuclear Experiment
free text keywords: Particle Physics - Experiment, Physics and Astronomy (all), General Physics and Astronomy, High Energy Physics - Experiment, QCD; axial vector meson, Nuclear physics, Pion, Isobar, Quantum number, Quantum chromodynamics, Spin-½, Pseudovector, Partial wave analysis, Meson, Physics
Funded by
FCT| CERN/FP/123600/2011
Project
CERN/FP/123600/2011
COLLABORATION IN THE COMPASS EXPERIMENT AT CERN
  • Funder: Fundação para a Ciência e a Tecnologia, I.P. (FCT)
  • Project Code: 123600
  • Funding stream: COMPETE
,
FCT| CERN/FP/109323/2009
Project
CERN/FP/109323/2009
COLLABORATION IN THE COMPASS EXPERIMENT AT CERN
  • Funder: Fundação para a Ciência e a Tecnologia, I.P. (FCT)
  • Project Code: 109323
  • Funding stream: 5876-PPCDTI
,
EC| HADRONPHYSICS3
Project
HADRONPHYSICS3
Study of Strongly Interacting Matter
  • Funder: European Commission (EC)
  • Project Code: 283286
  • Funding stream: FP7 | SP4 | INFRA
,
FCT| CERN/FP/116376/2010
Project
CERN/FP/116376/2010
COLLABORATION IN THE COMPASS EXPERIMENT AT CERN
  • Funder: Fundação para a Ciência e a Tecnologia, I.P. (FCT)
  • Project Code: 116376
  • Funding stream: 5876-PPCDTI
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