Luisa Cifarelli

The effective experimental constraints onMSUSY andMGUT

SummaryA comprehensive analysis of the world-data on αs is reported together with its average value at the Z0 mass. The effective constraints onMSUSY andMGUT are given. The care needed to reach any conclusion onMSUSY is discussed. For example, taking for the α1, α2, α3 coupled equations a numerical solution (it should be the most reliable one) and the two standard deviation limits in the uncertainty of the αs(MZ0 world average, the expectedMSUSY values range from 100.5±0.5 GeV to 105±1 GeV,i.e. from GeV to PeV.

The Evolution of gaugino masses and the SUSY threshold

SummaryWe propose a numerical iterative method to account for the evolutions of the gaugino masses (EGM). The effect of these evolutions on the most exhaustive model of SUSY breaking is presented. From above 21 TeV, the one-σ lower bound for SUSY breaking is brought down by more than two orders of magnitude. The model without EGM needed two σ to reach the Z0-mass range. The same model with EGM needs only one σ to reach the same level. The conclusion is that the SUSY threshold can be anywhere, including within the mass range where LEP I, HERA, LEP II and other colliders are working or planning to work.

The simultaneous evolution of masses and couplings: consequences on supersymmetry spectra and thresholds

SummaryWe use the Renormalization Group Equations to work out, at the one-loop level, the simultaneous evolution of all masses and couplings and show explicitly the self-consistency of the whole scheme. A thorough examination is performed of the light Supersymmetry threshold in the Minimal Supersymmetric extension of the Standard Model (MSSM). All fundamental quantitiesαGUT,MGUT,α3(mZ),α2(mZ),α1(mZ) (consequently sin2θ(mZ)) are given in terms of the detailed spectrum of all particle and sparticle thresholds. Examples of Supersymmetry spectra are given as function ofα3(mZ) and of the other essential parameters. The results of this study, where the evolution of masses is extended to all possible masses, confirm our previous conclusions on the EGM effect for the Supersymmetry threshold lower bound. Examples of the predictive power of our method are given.

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.

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.

The convergence of the gauge couplings atEGUT and above: Consequences forα3(MZ) and SUSY breaking

SummaryWe work out an iterative solution of the evolution equations forα1,α2,α3 in the Minimal SupersymmetricSU(5) Grand Unified model with the condition that the gauge couplings should converge smoothly towardsEGUT and should not separate aboveEGUT. The work is done at two levels of theoretical accuracy: one loop and two loops. Improved accuracy favours high values ofα3(MZ) with respect to the world average.

A study of the various approaches toMGUT andαGUT

SummaryAn exhaustive study is presented of the differentMGUT andαGUT values obtained using the renormalization group equations for the evolution of the couplings, with and without the evolution of the masses, with and without light and heavy-threshold effects, using different levels of theoretical accuracy: one and two loops, simple and detailed threshold treatments. A structure of the heavy threshold with mass ratios as large as 106 and values ofα3(MZ) as high as the world average plus 2σ are needed in order to reach high values ofMGUT, which are still an order of magnitude belowMPlanck. A discussion concludes the paper.

Measurement of forward and backward mean charged-particle multiplicities in high-energy (pp) soft interactions and comparison with high-energy neutrino and antineutrino deep inelastic scattering

SummaryThe difference between forward and backward mean charged-particle multiplicities is shown to exist also in (pp) interactions, when these are analysed in analogy with the deep inelastic scattering method. The measurements reported here show that this difference, which has been observed for a long time in (vp) and (vp) deep inelastic scattering experiments, is explained in terms of the omitted correction for the leading effect in the backward hemisphere.

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.