Observation of two JPC=0++ isoscalar resonances at 1365 and 1520 MeV

Systematics of quark–antiquark states and scalar exotic mesons

“…The method based on the extraction of leading singularities (pole, square root, logarithmic ones, and so on) in the production amplitude of a few particles was developed in the papers [33,34,35]. This method had been applied with the purpose to re-analyse the Crystal Barrel data for the reaction pp (at rest) → π 0 π 0 π 0 , and in the work performed together with the Collaboration members, the resonances f 0 (1370) and f 0 (1500) had been discovered in the region 1300-1500 MeV [2,3,4]. The data on the reactions pp → π 0 π 0 η and pp → π 0 ηη involved into combined analysis enabled us to discover a group of tensor and scalar-isovector resonances [5].…”

“…The f 0 (1300) resonance is denoted in the compilation [19] as f 0 (1370), however its mass following the most accurate determination, as is stressed above, is near 1300 MeV -so the notation f 0 (1300) is used here. The f 0 (1500) resonance had been discovered in [2,3,4], now it is a well-established state. A few years ago, there existed a strong belief that in the region around 1700 MeV a comparatively narrow state, f J (1710), was present, with J = 0 or 2.…”

“…As a result, the scalar-isoscalar resonances f 0 (1370) and f 0 (1500) have been discovered [2,3,4,5]; now these resonances are actively discussed in connection with the glueball problem. To establish the systematics of quark-antiquark states, the study of pp annihilation in flight carried out in 1999-2001 [6] was of a particular importance, for it allowed us to investigate the mass region 1900-2400 MeV: a large number of resonances discovered in this region made it possible to fix the qq trajectories on the (n, M 2 ) and (J, M 2 ) planes [1,7].…”

“…Previous analyses carried out in 1997-1998 [9,10,11] were based on the experimental data as follows: (1) GAMS data on the S-wave two-meson production in the reactions πp → π 0 π 0 n, ηηn and ηη ′ n at small nucleon momenta transferred, |t| < 0.2 (GeV/c) 2 [12,13]; (2) GAMS data on the ππ S-wave production in the reaction πp → π 0 π 0 n at large momentum transfers squared, 0.30 < |t| < 1.0 (GeV/c) 2 [12]; (3) BNL data on the reaction π − p → KKn [14]; (4) CERN-Münich data on π + π − → π + π − [15]; (5) Crystal Barrel data on pp(at rest, from liquid hydrogen)→ π 0 π 0 π 0 , π 0 π 0 η, π 0 ηη [3,5,16]. Now the experimental basis has much broadened, and additional samples of data are included into the analysis [8] of the 00 ++ wave as follows: (6) Crystal Barrel data on proton-antiproton annihilation in gas: pp(at rest, from gaseous hydrogen)→ π 0 π 0 π 0 , π 0 π 0 η [17], (7) Crystal Barrel data on proton-antiproton annihilation in liquid: pp(at rest, from liquid hydrogen)→ π + π − π 0 , [17]; (8) Crystal Barrel data on neutron-antiproton annihilation in liquid deuterium: np(at rest, from liquid deuterium)→ π 0 π 0 π − , [17]; (9) E852 Collaboration data on the ππ S-wave production in the reaction π − p → π 0 π 0 n at the nucleon momentum transfers squared 0 < |t| < 1.5 (GeV/c) 2 [18].…”

Systematics of Quark-Antiquark States: Where are the Lightest Glueballs?

“…In a situation of such a type, only a combined fitting to a large number of reactions allows one to expect reliable results. Previous analysis [6] carried out in 1997-1998 was based on the experimental data as follows: (1) GAMS data on the S-wave two-meson production in the reactions πp → π 0 π 0 n, ηηn and ηη n at small nucleon momenta transferred, |t| < 0.2 (GeV/c) 2 [9,10]; (2) GAMS data on the ππ S-wave production in the reaction πp → π 0 π 0 n at large momentum transfers squared, 0.30 < |t| < 1.0 (GeV/c) 2 [9]; (3) BNL data on the reaction π − p → KKn [11]; (4) CERN-Münich data on π + π − → π + π − [12]; (5) Crystal Barrel data on pp (at rest, from liquid H 2 )→ π 0 π 0 π 0 , π 0 π 0 η, π 0 ηη [13,14]. Now the experimental basis has much broadened, and additional samples of data are included into the analysis [5] of the 00 ++ wave as follows: (6) Crystal Barrel data on proton-antiproton annihilation in gas: pp (at rest, from gaseous H 2 ) → π 0 π 0 π 0 , π 0 π 0 η [15].…”