B. Esposito

EVIDENCE FOR THE EXISTENCE OF A NEW VECTOR MESON OF MASS 1.82 GeV OBSERVED IN e+e- ANNIHILATIONS AT ADONE

Evidence is presented for the occurrence in e+e− annihilation of a new vector meson of mass 1821 ± 16 MeV and Γ = 31 ± 15 MeV.

Momentum analysis of kaon and pion pairs produced from time-like photons at 1.6 GeV energy

We present results for the total cross section of e+e− annihilation into two hadrons at 1.6 GeV: σππ = σKK = (1.8 ± 1.1) × 10-33 cm2.From these values we obtain the time-like electromagnetic form factors these mesons: |Fπ|2 = 0.24 ± 0.14 and |FK|2 = 0.46 ± 0.26.

Search for narrow resonances in e+e− annihilation into hadrons at adone

Abstract A search for narrow resonances in the reaction e + e − → hadrons in the mass regions 1915–2345 MeV and 2970–3090 MeV has been perforned at ADONE, the Frascati storage ring. With 90% confidence level our data exclude the production of narrow resonances with integrated cross section larger than 20% of the integrated cross section for production of the J/Ψ (3100 MeV).

Search for narrow resonances in e+e− annihilation into hadrons at adone in the mass region 2.5–3.0 GeV/c2

Abstract The mass region 2.5 to 3.0 GeV/ c 2 has been searched for evidence of ψ-like narrow resonance in e + e − annihilation into hadrons. No evidence for new narrow resonances has been found with a sensitivity of about the 10% of the integrated cross section of the J/ ψ (3100).

Measurement of the J/ψ(3100) decay widths into e + e − and Μ + Μ − at adone

W e r e p o r t t h e e x p e r i m e n t a l r e su l t s o b t a i n e d a t A d o n e b y t he M E A Group on t he J /+(3100) decay in to l ep ton pai rs . P r e l i m i n a r y resu l t s on t h e i n t e g r a t e d crosssec t ions for t h e c h a n n e l s c + e ~ h a d r o n s , ~+~-, e+e h a v e been r e p o r t e d (i). I n th i s p a p e r we give r e su l t s on t he e+c a n d ~+~pa i r a n g u l a r d i s t r i b u t i o n s a n d on t h e p a r t i a l decay w id th s . These r e su l t s t u r n ou t to be co inpa t ib l e w i t h a j ~ e = 1-a s s i g n m e n t (2) for t h e J /+(3100) .

Angular distributions for single neutral pion photoproduction from neutrons at 450–800 MeV

Abstract Differential cross sections for single photoproduction of neutral pion on neutron have been measured at different c.m. angles for photon energies, between 450–800 MeV. The results are compared with the existing theories and seem to favour the hypothesis of an appreciable presence of the P 11 (1470) in the neutron photoexcitation.

Hadronic cross-section in e+e- annihilation from 1.45 to 1.80 GeV

Measurements of the hadronic cross section in e+e- annihilation from 1.45 to 1.80 GeV are presented

Resonant K*(892) Production in Multihadron e+e - Annihilation.

Preliminary results on resonant K*(892) production in multihadron e+e- annihilation are presented

Neutral-pion photoproduction on proton from deuterium in the energy range (400÷800) MeV

The differential cross-section for react ion (1) has been measured by detec t ing bo th the pro ton and the forward emi t t ed photon f rom the ~:0 decay, in the energy range of the incident photon E v ( 4 0 0 : 8 0 0 ) M e V , at three different angles in the centre-of-mass sys tem (c.m.s.) 0* = 60 ~ , 90 ~ and 135 ~ As far as react ion (2) is concerned, we have man ta ined the same exper imenta l condi t ions chosen for the react ion (1) only refilling the same target wi th deu te r ium ins tead of hydrogen. In this case the specta tor neut ron (n,,) was not detected. The main purpose of this exper iment is to compare the cross-section for process (2) wi th the cross-section for a free pro ton , i . e . process (1). This comparison is essental ly a test on the val id i ty of the (~ impulse approx imat ion ,~ by which people general ly analyse the pho toproduc t ion on deuter ium. Actual ly , the exper imenta l s i tuat ion on the impulse approx imat ion is not comple te ly clear due to the l a ck of exper imenta l data, expecial ly for the r: ~ photoproduct ion (1). For the r:+ pho toproduc t ion the exper imenta l da ta show a deviat ion f rom the impulse approx imat ion predict ions of the order of (5 -10 )% (2). Our results show that , s t icking to the specta tor model, sensible discrepancies appear in the n ~ pho toproduc t ion on bound pro ton in deuter ium. The exper imenta l set up is shown in Fig. I.

Measurement onp+ p- p0 p0+−00,p+ p- p+ p- p0+−+−0,p+ p- p+ p- p0 p0+−+−00,p+ p- p+ p- p+ p-+−+−+−production cross-sections in e+e− annihilation at (1.45÷1.80) GeV c.m. Energyproduction cross-sections in e+e− annihilation at (1.45÷1.80) GeV c.m. Energy

Measurement on π+ π- π0 π0, π+ π- π+ π- π0, π+ π- π+ π- π0 π0, π+ π- π+ π- π+ π- production cross-sections in e+e− annihilation at (1.45÷1.80) GeV c.m. energy are presented