F. Palmonari

The time-like electromagnetic form factors of the charged pseudoscalar mesons from 1.44 to 9.0 GeV2

Abstract The study of 620 hadron pairs produced in the s -range (1.44−9.0) GeV 2 , has yielded 110 collinear hadronic events. Their identification in terms of π and K mesons allows the determination of the time-like electromagnetic from factors of these pseudoscalar mesons in the above time-like range. The total number of (e + e − ) events observed in the same experimental conditions is 18 048.

A large-area modular electromagnetic shower detector for the CERN intersecting storage rings

Abstract We describe the design and performances of a large-area (13 m 2 ) shower detector built for an experiment at the CERN ISR to detect electrons and gamma rays with energies up to 4 GeV. The main characteristics of the detector are: a) linearity of the energy response from 0.5 to 4 GeV; b) good energy, time and space resolutions; c) modularity of the mechanical assembly; d) low cost of construction.

e+e− Annihilation into two hadrons in the energy interval 1400–2400 MeV

Abstract The proof is given for the existence of the reaction e + e − → h ± h ∓ in the energy range 1400–2400 MeV, and its energy dependence is compared with that of e + e − → e ± e ∓ , in the same experimental conditions of observation. The exponent of the s -dependence of the ratio α = (e + e − → h ± h ∓ )/ (e + e − → e ± e ∓ ) is measured to be n = 2.08 ± 0.45, in the s -range (1.96 − 5.76) GeV 2 , on the basis of 51 e + e − → h ± h ∓ events and 8918 e + e − → e ± e ∓ events observed.

Direct check of QED in e+e− interactions at highq2-values

SummaryA study of 1824 e+e−→e±e∓ events in the total centre-of-mass energy range from 1.6 GeV to 2.0 GeV, allows one to establish that production angular distributions, a collinearity and acoplanarity distributions, and absolute value of the cross-sections and their energy-dependence, follow QED predictions including first-order radiative corrections. In particular, the absolute value of the cross-section and the power of its energy-dependence agree with theoretical expectations within ±6% and ±2%, respectively. The inadequacy of the peaking approximation in our experimental conditions of observations has been measured to be (2.8±0.4)%.RiassuntoSono state studiate 1824 interazioni e+e−→e±e∓ con valori dellenergia totale compresi nellintervallo (1.6÷2.0) GeV. I valori assoluti delle sezioni durto, la loro dipendenza dallenergia, le distribuzioni angolari e le distribuzioni di acollinearità e di acoplanarità delle particelle prodotte sono in accordo con le previsioni della elettrodinamica quantica. Tali previsioni sono state calcolate tenendo conto delle correzioni radiative al primo ordine. Laccordo tra previsioni teoriche e risultati sperimentali è di ±6% per il valore assoluto della sezione durto, e di ±2% per la sua dipendenza esponenziale dallenergia. È stato inoltre stabilito che la «peaking approximation» devia del (2.8±0.4)% nelle correzioni radiative al primo ordine.РезюмеИсследование 1824 событий e+e−→e±e∓ в области полной энергии в системе центра масс от 1.6 ГэВ до 2.0 ГэВ позволяет нам уастановить, что утловые распределения рождения, распределения коллинеарности и компланарности, абсолютные значения поперечных сечений и их энергетическая зависимость следуют предсказаниям квантовой электродинамики, включая радиационные поправки первого порядка.

Experimental proof of the inadequacy of the peaking approximation in radiative corrections

Abstract 49 e+e− non-collinear, non-coplanar events have been observed in a study of 1824 e+e− interactions at total centre-of-mass energies from 1.6 GeV to 2.0 GeV. The inadequacy of the peaking approximation in radiative corrections is measured to be (2.8 ± 0.4)%, in these experimental conditions of observation.

The leading effect explains the charged-particle multiplicity distributions observed at the cern pp collider

SummaryThe assumption that the leading effect, and the charged-particle multiplicity distributions, measured at the ISR, scale with energy, and that the mean charged multiplicity, measured at the ISR, can be extrapolated up to Collider energy using the leading subtraction method, allows a prediction of the charged multiplicity distribution at the CERN pp Collider. This prediction is found to be in excellent agreement with the experimental data obtained at the Collider by the UA5 group.

Universality Features in (pp), (e+e−), and Deep Inelastic Scattering Processes

SummaryThe use of the correct variables in (pp), (e+e−), and deep-inelastic scattering (DIS) processes allows universality features to be established in these—so far considered—different ways of producing multihadronic states.RiassuntoLuso delle variabili corrette, nei processi (pp), (e+e−) e scattering inelastico profondo (DIS), permette di mettere in evidenza lesistenza di caratteristiche universali in tali interazioni, considerate sinora modi molto differenti di produrre stati multiadronici.РезюмеИспользование правильных переменных в (p, p), (e+e−) и процессах глубоко неупругого рассеяния позволяет установить универсальные особенности в этих реаксиях.

Search for fractionally charged particles produced in proton-proton collisions at the highest ISR energy

SummaryThe results of an experiment to search for quarks at the CERN ISR, at a total centre-of-mass energy √s=62.2 GeV, are reported. The experiment was sensitive to fractionally charged particles with 0.035e≤|Q|≤0.67e, β=v/c≥0.1 and masses up to 26 GeV/c2. The 90% confidence level on the ratio «quark flux/charged flux» is 1.78·10−9 forQ=+(1/3)e and 1.05·10−9 forQ=−(1/3)e. These values hold true for production processes with transverse momentap⊥≃0.4 GeV/c.RiassuntoSi presentano i risultati di un esperimento per la ricerca di quarks presso gli ISR del CERN, ad un valore dellenergia totale nel centro di massa √s=62.2 GeV. Lesperimento era sensibile a particelle con carica frazionaria nellintervallo 0.035e≤|Q|≤0.67e, con β=v/c≧0.1 e masse fino a 26 GeV/c2. Il valore del rapporto «flusso di quarks/flusso di particelle cariche», con un livello di confidenza del 90%, è 1.78·10−9 perQ=+(1/3)e, e 1.05·10−9 perQ=−(1/3)e. Questi valori si applicano a processi di produzione con impulsi trasversip⊥≃0.4 GeV/c.

A check of quantum electrodynamics and of electron-muon equivalence

SummaryA study of the timelike reaction e+e-→μ∓μ± and of its comparison with the spacelike dominated reaction e+e−→e±e± allows us to establish the validity of QED in terms of production angular distributions, absolute rates, energy dependence and angular correlations between the pair of final-state leptons, in two very different ranges of invariant four-momentum transfer. No sign of QED break is detected in the electromagnetic interaction of leptons and the muon behaves like a heavy electron, within the accuracy of the present investigation.RiassuntoSi è compiuto uno studio della reazione «timelike» e+e-→μ∓μ± ed un confronto di questa con la reazione e+e−→e±e± nella quale la parte «spacelike» è dominante. Si sono studiate le distribuzioni angolari delle particelle prodotte, la loro dipendenza dallenergia, le correlazioni geometriche fra le coppie di leptoni nello stato finale, i valori assoluti delle sezioni durto, al fine di stabilire la validità dellelettrodinamica quantica in due intervalli diversi di quadrimomento trasferito. Entro gli errori sperimentali (±8%) non si trova alcuna evidenza di violazione della elettrodinamica quantica nellinterazione elettromagnetica dei leptoni, ed il muone si comporta come un elettrone pesante.РезюмеИсследование времениподобной реакции e+e-→μ∓μ± и ее сравнение с пространственноподобной доминирующей реакцией e+e−→e±e± позволяет нам установить справедливость квантовой электродинамики в терминах угловых распределений рождения, авсолютных интенсивностей, энергетической зависимости и углобых корреляций между парами лептонов в конечном состоянии, в двух очень различиых областях инвариантного четырехмерного передаваемого импульса. Не определен знак нарушения квантовой электродинамики и мюон ведет себя подобно тяжелому электрону в пределах точности настоящего исследования.

Proof of comparable K-pair and π-pair production from time-like photons of 1.5, 1.6, and 1.7 GeV and determination of the K-meson electromagnetic form factor☆

Abstract The observation of 21 K + K − pairs in 38 hadron pair events produced at 1.5, 1.6, and 1.7 GeV total centre-of-mass energies in e + e − annihilations, establishes that time-like photons produce K pairs and π pairs with comparable rates in this energy range. The K-meson electromagnetic form factor at a mean s -value of 2.4 GeV 2 is measured to be | F K | = 0.50±0.08. The number of e + e − pairs observed in the same angular and energy range is 5148.