S. M. Scarrott

Is there structure in the f0 mass region

Evidence is presented for structure in the f0-mass region in the reaction π+n→pπ+π− at a pion momentum of 11.7 GeV/c. A detailed analysis indicates that it is most unlikely that the structure is a statistical effect.

A Study of the Reactions pi+ d --> d pi+ pi- pi+ and pi+ d --> d pi+ pi- pi+ pi0 at 11.7-GeV/c

SummaryThe two coherent reactions π+d → dπ+π+π− and π+d → → dπ+π+π+π0 are studied in the 2 m DBC at the incoming momentum of 11.7 GeV/c. The production cross-sections are measured:σ=(0.37±±0.06) mb andσ=(0.24±0.05) mb respectively. The two reactions are analysed in the different LPS configurations. The dσ/dt′ distribution for the two reactions displays the same exp[−At′] shape withA⋍37 (GeV/c)−2 in both cases, thus indicating that the differential cross-sections are dominated by the deuteron form factor. The coherent inclastic interaction contains the channel π+d → θ0π+d with a cross-sectionσ==(20±5) µb and a signal for the B+-meson of about 12 µb. The four-pion masses display structures below 2 GeV/c.RiassuntoNella camera a bolle 2 m DBC del CERN esposta ad un fascio di π+ di 11.7 GeV/c si sono studiate le due interazioni coerenti π+d → π+π+π−d e π+d → π+π+π−π0d. Le sezioni d’urto di produzione sono rispettivamenteσ=(0.37±0.06) mb eσ=(0.24±0.05) mb. Si analizzano diversi aspetti dei due canali esclusivi tra cui le diverse configurazioni longitudinali più frequenti. La sezione d’urto differenziale dσ/dt′ presenta la stessa forma exp [−At′] con un valoreA⋍37 (GeV/c)−2 per entrambe le reazioni. Ciò implica la dominanza del fattore di forma del deutone su entrambi i processi in esame. La reazione coerente inelastica contiene un contributoσ=(20±5) µb del canale π+d → θ0π+d nel quale il segnale del mesone B+ è di circa 12 µb. Le masse effettive di quattro pioni mostrano strutture tipiche e significative perM∼2 GeV.РеэюмеИсследуются две когерентных реакции π+d → dπ+π−π+ и π+d → dπ+π−π+π0 в 2 м дейтериевой пуэырьковой камере при импульсе падающих частиц 11.7 ГзВ/с. Иэмеренные поперечные сечения рождения соответственно составляютσ=(0.37±±0.06))μб иσ=(0.24±0.05)μб. Исследуемые две реакции аналиэируются в раэли-чных LРS конфигурациях. Распределение dσ/dt′ для двух реакций обнаруживают ту же форму ехр [−At′] сA=37 (ГзВ/с)−2 в обоих случаях. Этот реэультат укаэы-вает, что дифференциальные поперечные сечения доминируют эа счет форм-фактора дейтрона. Когерентное неупругое вэаимодействие содержит канал π+d → ω0π+d с поперечным сечениемσ=(20±5)μб и сигнал для меэона В+ с величиной около 12μб. Эффективные массы четырех пионов обнаруживают типичную структуру дляM≼2ГзВ.

The analysis of rapidity gaps of produced particles in π + d at 5.1 and 11.7 GeV/c

SummaryAn analysis of high-multiplicity π+d reactions at 5.1 and 11.7 GeV/c is presented in terms of rapidity gaps between the final particles. The experimental data are compared with various models. The models generally underestimate the class of events corresponding to «single clusters». Characteristics of this class of events are studied.RiassttntoSi propone un’analisi delle differenze in rapidità tra le particolle prodotte in alcune reazioni π+d a 5.1 ed a 11.7 GeV/c. I dati sperimentali sono confrontati con le previsioni deducibili da vari modelli; si constata che tali previsioni in genere sottostimano il numero di eventi configurati ad ammasso singolo. Si analizzano, per concludere. talune proprietà di questo ultimo tipo di eventi.