π−p→π0n differential cross-sections have been measured in the region of small 4-momentum transfer at 40 GeV/c incident momentum. The experiment performed at the IHEP 70 GeV accelerator makes use of a hodoscope γ-spectrometer. Thet- dependence of the cross-section points to a dominance of the spin-flip amplitude.
No description provided.
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No description provided.
In a high-statistics experiment (200 events/nanobarn) performed at the 70 GeV IHEP accelerator, a new dipion resonance has been observed in π−p collisions at 38 GeV/c momentum. The gamma-rays in reaction π−p → M0n, M0 → π0π0 → 4γ have been detected in the hodoscope spectrometer GAMS-2000. The new meson, r(2510), has a mass (2510±30) MeV/c2, a width (240±60) MeV/c2 and spin-parityJPC=6++. The production cross-section of the f, h and r mesons decreases exponentially with spin like exp [−0.9J].
No description provided.
η′η pair production in the charge exchange reaction π−p→η′ηn has been observed and studied in a search for glueballs with the 38 GeV/c pion beam of the 70 GeV IHEP accelerator. The γ-rays from the decay η′η→4γ were detected with the hodoscope spectrometer GAMS-2000. The η′η events in the mass range from threshold up to 1.8 GeV are decays of the scalar G(1590)-meson which has been already observed in its ηη decay mode. The measured ratio of the partial widths of the G→η′η and the G → ηη decay channels is 2.7±0.8 in agreement with the value expected for glueballs.
No description provided.
The production of K 0 s, Λs and Λ s has been studied in a 280 GeV muon-proton scattering experiment with almost complete coverage of all kinematic regions. A study is made of the dependence of the multiplicities on the hadronic centre of mass energy, W , and of the Feynman x distributions. It is found that K 0 and Λ production is mostly central and increases strongly with W , whereas Λ production comes mainly from the remnant target system and is only weakly W dependent.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
Results are presented on the transverse momentum distributions of charged hadrons in 280 GeV muon-proton deep inelastic interactions. The transverse momenta are defined relative to the accurately measured virtual photon direction and the experiment has almost complete angular acceptance for the final state hadrons. Significantly larger values of the average transverse momentum squared are found for the forward going hadrons than for the target remnants. This result, combined with a study of the rapidity region over which the transverse momentum is compensated, can be explained by a significant contribution from soft gluon radiation, but not by a large value of the primordial transverse momentum of the struck quark.
Errors given are statistical only.
Errors are statistical only.
Errors are statistical only.
None
Backward Multiplicity.
Forward Multiplicity.
No description provided.
Properties of the hadron multiplicity distributions in 280 GeV/c μ<sup loc="post">+</sup>p interactions have been investigated. The c.m. energy dependence in the range from 4 to 20 GeV of the total charged multiplicities are presented. No variation faster than logarithmic is seen in the energy range of this experiment. Comparison with νp and <math altimg="si1.gif"><ovl type="bar" style="s">ν</ovl><rm>p</rm></math> data at lower energy has been made and shows good agreement between μ<sup loc="post">+</sup>p and <math altimg="si1.gif"><ovl type="bar" style="s">ν</ovl><rm>p</rm></math> total charged multiplicities. It has been found that the average forward multiplicity (charged hadrons with xF > 0) exceeds the average backward multiplicity (charged hadrons with xF < 0) in the whole energy range and presents a different energy variation. The average forward multiplicity has been compared to e<sup loc="post">+</sup>e<sup loc="post">−</sup> data and shows a similar dependence on energy. Little correlation was observed between the forward and backward multiplicities indicating that the current and target regions fragment almost independently.
No description provided.
No description provided.
No description provided.
Measurements are presented of the variation with Q 2 (scaling violation) of the hadron multiplicity in deep inelastic muon-proton scattering. An increase in the average multiplicity of both the charged hadrons and K 0 mesons is observed with increasing Q 2 or x Bj for fixed centre-of-mass energy W . The study of the shape of the effective fragmentation function D h ( z , W , Q 2 ) shows that the increase of the particle yield with Q 2 takes place for low z particles. The variation of the hadron distributions with Q 2 is also studied in the current fragmentation region where a decrease in multiplicity is observed. Such effects are expected from QCD.
No description provided.
No description provided.
Inclusive production of the Δ (1232) resonance has been measured in 280 GeV/ c muon-proton interactions. The production of the Δ ++ as a function of the variables χ BJ , W , Q 2 , χ F and p T 2 is investigated. The average Δ ++ multiplicity is found to be smaller, by a factor of 6.2 ± 1.2, than the average multiplicity of protons. An upper limit for Δ 0 production is obtained. The net hadronic charge distribution for events with a Δ ++ is presented. The results are compared to the predictions of the Lund and Fire string models.
No description provided.
No description provided.
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