Hiroyuki Yokomi

Some statistical and kinematical comments on high-energy jets

SummarySome statistical and kinematical problems necessary for the analysis of high-energy jets using fire-ball models are studied. The laboratory integral angular distributions of secondaries emitted from the fire ball are calculated. In the rest system of the fire ball, some types of energy and angular distributions are assumed and effects of relatively small velocities of secondaries compared to the velocity of the centre of energy of the fire ball in the laboratory system are investigated. The following statistical tests are made in order to see, between the two-fire-ball model and Hasegawa’s model, which one is more favourable to explain the experimental data: 1) we test the hypothesis that the two-fire-ball model is justified in each event; 2) it is examined whether the massive object observed by Hasegawa (H-quantum) decays isotropically or in the angular distribution of sin2 θ* type in its rest system; 3) we cheek, the position and width of characteristic peaks in the frequency distribution of the Lorentz factor of H-quanta by the method ofk- statistics (momentum method). It is concluded that the two-fire-ball model in its original form can be rejected statistically. Hasegawa’s model seems to be more favourable than the two-fire-ball model if we consider the accumulated data.RiassuntoSi studiano alcuni problemi di statistica e cinematica necessari per l’analisi di getti di alta energia con 1’uso di modelli a palla di fuoco. Si caloolano le distribuzioni angolari integrali nel sistema del laboratorio. Nel sistema di quiete della palla di fuoco, in base ad alouni tipi di distribuzione dell’energia ed angolari, si studiano gli effetti di velocità dei secondari relativamente piccole rispetto alla velocità del centro d’energia della palla di fuoco nel sistema del laboratorio. Si sono eseguite le seguenti verifiche per vedere quale dei due, il modello a due palle di fuooo e quello di Hasegawa, è più adatto a spiegare i dati sperimentali: 1) verifichiamo l’ipotesi che il modello a due palle di fuoco sia giustificato in in ogni evento; 2) si esamina se l’oggetto massivo osservato da Hasegawa (quanto H) deoada isotropicamente o con una distribuzione angolare del tipo sin2 θ* nel sistema di quiete; 3) controlliamo la posizione e l’ampiezza dei caratteristici picchi della distribuzione di frequenze del fattore di Lorentz dei quanti H col metodo della statisticak (metodo dell’impulso). Si conclude che il modello a due palle di fuoco nella sua forma originale puÒ essere rigettato in base alle statistiche. Il modello di Hasegawa sembra più adatto del modello a due palle di fuoco se prendiamo in considerazione i dati raccolti sinora.

Effects of the Pion-Pion Interaction on Photonuclear Reactions

>Various effects of the pion-pion interaction on the photonuclear reactions through the phenomenological gamma -3 pi interaction are investigated. Processes discussed here are pion photoproduction, double pion photoproduction, and electromagnetic properties of the deuteron. The following problems are investigated in detail: angular distribution, polari-zation of the recoil proton, photopion with polarized gamma rays, for neutral pion photoproduction; and plus- minus ratio of charged pion photoproduction, double pion photoproduction. For the electromagnetic properties of the deutei on, magnetic moment, electric quadrupole moment, and photodisintegration are studied. The effective gamma -3 pi hamiltonian is given, and appropriate approximation is made for the I = J = 1 pion-pion resonance in the matrix elements of photoprocesses. These approximations of en lead to overestimation of the effects, as is criticized. (auth)

A Semi-Phenomenological Approach to Multiple Meson Production

A theoretical approach to the fire ball model in multiple meson production is made in this paper. Assuming that two fire balls are produced in a peripheral nucleon-nucleon collision and that the fire balls can be regarded as unstable spinless bosons, we have field-theoretically calculated various quantities concerning their production process, such as angular and energy distributions and transverse momentum of the fire ball and inelasticity. Nius relation is also checked. Finally, the calculations are carried out for two cases: the cases in which the boson interacts with (i) nucleon or (ii) pion. In either case, the results are not inconsistent with the general features of the experimental data.