Percorrer por autor "COMPASS collaboration (207 authors)"
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- Odd and even partial waves of $ηπ^−$ and $η′π^−$ in $π^−p → η^{(′)}π^−p$ at 191 GeV/cPublication . COMPASS collaboration (207 authors); Bordalo, P.; Franco, C.; Nunes, Ana Sofia; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.Exclusive production of ηπ− and η′π− has been studied with a 191 GeV/c π− beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum ( L ) characteristics in the inspected invariant mass range up to 3 GeV/c2 . A striking similarity between the two systems is observed for the L=2,4,6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a2(1320) and a4(2040) are in line with this similarity. In contrast, a strong enhancement of η′π− over ηπ− is found for the L=1,3,5 waves, which carry non- qq¯ quantum numbers. The L=1 intensity peaks at 1.7 GeV/c2 in η′π− and at 1.4 GeV/c2 in ηπ− , the corresponding phase motions with respect to L=2 are different.
- Study of $\Sigma(1385)$ and $\Xi(1321)$ hyperon and antihyperon production in deep inelastic muon scatteringPublication . COMPASS collaboration (207 authors); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.Large samples of \Lambda, \Sigma(1385) and \Xi(1321) hyperons produced in deep-inelastic muon scattering off a ^6LiD target were collected with the COMPASS experimental setup at CERN. The relative yields of \Sigma(1385)^+, \Sigma(1385)^-, \bar{\Sigma}(1385)^-, \bar{\Sigma}(1385)^+, \Xi(1321)^-, and \bar{\Xi}(1321)^+ hyperons decaying into \Lambda(\bar{\Lambda})\pi were measured. The heavy hyperon to \Lambda and heavy antihyperon to \bar{\Lambda} yield ratios were found to be in the range 3.8% to 5.6% with a relative uncertainty of about 10%. They were used to tune the parameters relevant for strange particle production of the LEPTO Monte Carlo generator.