A coupled-channel analysis of BESIII data on radiative J/ψ decays into ππ, KK¯, ηη and ωϕ has been performed. The partial-wave amplitude is constrained by a large number of further data. The analysis ...finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar scalar states are observed with significant yields only in the 1500-2100MeV mass region. Singlet scalar mesons are produced over a wide mass range but their yield peaks in the same mass region. The peak is interpreted as scalar glueball. Its mass and width are determined to M=1865±25−30+10MeV and Γ=370±50−20+30MeV, its yield in radiative J/ψ decays to (5.8±1.0)10−3.
Properties of nucleon and
Δ
resonances are derived from a multichannel partial wave analysis of pion and photo-induced reactions off protons. This paper summarizes the latest results on masses, ...widths, and decay properties of nucleon and
Δ
resonances.
Hyperon II: Properties of excited hyperons Sarantsev, A. V.; Matveev, M.; Nikonov, V. A. ...
The European physical journal. A, Hadrons and nuclei,
10/2019, Letnik:
55, Številka:
10
Journal Article
Recenzirano
Odprti dostop
.
We report properties of
Λ
and
Σ
hyperon resonances formed in
K
-
induced reactions. Special emphasis is laid on the analysis of the three-body final states
2
π
0
Λ
and
2
π
0
Σ
and of the ...quasi-two-body final states
π
Λ
(
1520
)
,
K
¯
Δ
(
1232
)
,
π
Σ
(
1385
)
,
K
¯
*
N
, and
ω
Λ
. We give pole positions of
Λ
and
Σ
hyperon resonances and transition residues from the
K
-
p
initial to various final states as well as Breit-Wigner masses and widths and decay branching ratios. Twenty resonances and “bumps” reported in the Review of Particle Physics are not required in our fits, evidence for five new resonances is reported. The observed mass spectrum is compared to the spectrum calculated in the Bonn quark model. Three spin doublets, six
Λ
hyperons, are tentatively assigned to the
SU
(3) singlet system.
Branching ratios for the decay of hadrons with large width or near thresholds depend on their definition. We test different definitions and show that rather different branching ratios can be ...obtained. For wide resonances and for sequential decays with wide intermediate resonances, integration over the spectral functions is mandatory. The tests are performed exploiting the latest solution of the Bonn-Gatchina multi-channel analysis and published values for residues of light scalar mesons. For a resonance overlapping with a threshold, in case its pole lies in a non-adjacent sheet, we show how the total width, needed for the branching ratios, does not correspond to the imaginary part of the pole position. We use the Madrid-Krakow dispersive parameterizations to illustrate this situation with the f0(980).
Proton-η′ interactions at threshold Anisovich, A.V.; Burkert, V.; Dugger, M. ...
Physics letters. B,
10/2018, Letnik:
785, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Recent data on photoproduction of η′ mesons off protons have been included in the data base for the Bonn–Gatchina partial wave analysis. The real and imaginary parts of the S-wave η′p→η′p scattering ...amplitude in the threshold region were fit to yield the η′p scattering length and the interaction range. This new analysis found |aη′p|=(0.403±0.015±0.060) fm and a phase ϕ=(87±2)∘, while the range parameter is not well-constrained. The striking behavior of the GRAAL data on the beam asymmetry in the threshold region suggests that a narrow proton-η′ resonance might exist. However, the scattering length was found to be relatively insensitive to the possible existence of this narrow resonance.
Λ and Σ Excitations and the Quark Model Klempt, E.; Burkert, V.; Thoma, U. ...
The European physical journal. A, Hadrons and nuclei,
2020/10, Letnik:
56, Številka:
10
Journal Article
Recenzirano
Odprti dostop
The spectrum of
Λ
and
Σ
excitations is reviewed taking into account (nearly) all hyperon resonances which were seen in early analyses or in one of the recent partial-wave analyses. The spectrum is ...compared with the old Isgur–Karl model and the Bonn model. These models allows us to discuss the SU(3) structure of the observed resonances. The SU(3) decomposition is compared with SU(6) relations between the different decay modes. Seven
Λ
states are proposed to be classified as SU(3) singlet states. The hyperon spectrum is compared with the spectrum of
N
and
Δ
resonances.
A study of the partial-wave content of the γp→η′p reaction in the fourth resonance region is presented, which has been prompted by new measurements of polarization observables for that process. Using ...the Bonn–Gatchina partial-wave formalism, the incorporation of new data indicates that the N(1895)1/2−, N(1900)3/2+, N(2100)1/2+, and N(2120)3/2− are the most significant contributors to the photoproduction process. New results for the branching ratios of the decays of these more prominent resonances to Nη′ final states are provided; such branches have not been indicated in the most recent edition of the Review of Particle Properties. Based on the analysis performed here, predictions for the helicity asymmetry E for the γp→η′p reaction are presented.
Data on the reaction γp→ωp with ω→π0γ, taken with unpolarized or polarized beams in combination with an unpolarized or polarized proton-target, were analyzed within the Bonn–Gatchina (BnGa) partial ...wave analysis. Differential cross sections, several spin density matrix elements, the beam asymmetry Σ, the normalized helicity difference E, and the correlation G between linear photon and longitudinal target polarization were included in a large data base on pion and photo-induced reactions. The data on ω photoproduction are used to determine twelve N⁎→Nω branching ratios; most of these are determined for the first time.
.
Early data on
K
-
induced reactions off protons are collected and used in a coupled-channel partial-wave analysis (PWA). Data that had been published in the form of Legendre coefficients are ...included in the PWA. In a
primary
fit using
3
*
and
4
*
resonances only, we observe some significant discrepancies with the data. In a systematic search for new
Λ
and
Σ
hyperon resonances, additional candidates are found. The significance of the known and of the additional resonances is evaluated. Seventeen resonances listed with
1
*
or
2
*
and one resonance listed with
3
*
in the Review of Particle Physics cannot be confirmed, five new hyperons are suggested. The partial-wave amplitudes deduced in this analysis are compared to those from other analyses.
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