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A suggestion for investigating electron-muon and electron-pion scattering with electron-positron colliding beams

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HAL Id: jpa-00215547

https://hal.archives-ouvertes.fr/jpa-00215547

Submitted on 1 Jan 1974

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A suggestion for investigating electron-muon and electron-pion scattering with electron-positron colliding

beams

C. Carimalo, P. Kessler, J. Parisi

To cite this version:

C. Carimalo, P. Kessler, J. Parisi. A suggestion for investigating electron-muon and electron-pion

scattering with electron-positron colliding beams. Journal de Physique Colloques, 1974, 35 (C2),

pp.C2-124-C2-125. �10.1051/jphyscol:1974237�. �jpa-00215547�

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C2- 124 CONTRIBUTIONS

(where X is any C

=

+ state) or amplitudes ; subtractions have then been fixed impos- p + p + X 1 + y * + X 2 + y * - + X 1 + ing off-mass-shell current algebra limits both for one

+

x2

+

y +

+ p-

and two massless external mesons. Predictions on the S wave amplitudes have also been derived from (where XI,

'2

are hadron states) is reviewed in Some the recent analysis of meson-meson scattering by detail. Both the theoretical aspects and the experi- Protopopescu ol

mental feasibility of various processes are discussed especially for experimentalists' convenience.

The equivalent polarised-photon approximation Absorption of high-energy cosmic photons through

double pair production in photon-photon collisions R. W. BROWN and K. 0 . MIKAELIAN

Department of Physics, Case Western Reserve University,

Cleveland, Ohio 44106, USA and

Department of Physics, University of California at San Diego,

La Jolla, California 92037, USA Abstract.

-

At photon energies above

absorption by y + y'

+

2 ef + 2 e- dominates that from the lower-order process y + y'

+

ef + e- for high-energy photons traversing a 2.8 K blackbody photon gas. Existence of the 2 e f , 2 e- process and the cosmic blackbody radiation thus guarantees that the universe is opaque for all photon energies above l o t 4 eV. The question of single-pair production in collisions with cosmic radio-wave photons is discussed, and the uncertainty in our knowledge of the important low-frequency end of the radio spectrum is emphasized.

Other processes (y + y'

+

muons, hadrons, etc.) are discussed briefly, and it is concluded that they are of minor importance.

A treatment of meson pair production in yy collisions including inelasticity

and current algebra P. GENSINI

Istituto di Fisica dell'Universit8, Lecce Abstract.

-

We have considered two problems posed by dispersive approaches to yy

-, ~ T C

and yy

+

K K amplitudes, namely the introduction of inelastic unitarity and the ambiguity in partial wave dispersion relation subtractions. Introducing an (R, 9) representation for nn amplitudes, we have transformed inelastic unitarity into an inhomogeneous Hilbert- Riemann problem, completely defined by one subtrac- tion and by the knowledge of meson-meson partial

C. J. BROWN and D. H. LYTH University of Lancaster,

Department of Physics, Lancaster, U K

Abstract.

-

The equivalent photon approximation is studied for the case where the scattered electron is detected. The equivalent photon is then polarised.

The region of validity is found t o depend on the virtual photon scattering angle, rather than on the electron scattering angle, and this distinction is important. A discrepancy concerning the dependence on beam energy of the total cross section for ee

+

e e +

hadrons which was noted by Bonneau et al. is resolved.

Particular cases of particle production in inelastic lepton

(anti) lepton scattering G. BONNEAU and F. MARTIN Laboratoire de Physique ThCorique et des Hautes Energies, Paris, France

Abstract.

-

As in a previous paper we consider the inclusive reactions e + e

-+

e + e + anything in the two photon exchange approximation. We present the complete calculation of the differential cross section da/d W2 for the production of a state of effective mass Wand we give the expression of the total cross section.

We apply this to the muon pair and the pseudoscalar meson (no, q and q ' ) productions.

A suggestion for investigating electron-muon and electron-pion scattering with electron-positron colliding beams C. CARIMALO, P. KESSLER and J. PARISI

Laboratoire de Physique Atomique, Colli.ge de France, Paris, France

Abstract.

-

We show that it is possible, in principle, to study the scattering between an

((

almost real

))

muon or pion and an electron in an e- e f colliding beam experiment where one large-angle electron and one large-angle muon or pion would be measured

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1974237

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CONTRIBUTIONS C2- 1 25

in the final state. In the muon case, the counting rate should be high enough to allow this experiment to be performed with electron-positron storage rings of the next generation.

Nuclei as generators of quasi-real photons C. CARIMALO, G. COCHARD, P. KESSLER,

J. PARISI and B. ROEHNER Laboratoire de Physique Corpusculaire,

College de France, Paris, France

Abstract. - An equivalent photon approximation is tested for the inelastic scattering of high-energy

non-hadronic particles (leptons and photons) in the

electromagnetic field of nuclei. Coherent, incoherent

elastic and incoherent inelastic contributions are

included. As for the coherent (Coulomb) term, various

nuclei (92U235, 27C059, 6 C 1 2 ) with different types of

form factors are considered. Four processes are

considered

:

a ) photoproduction of muon pairs

;

6 ) muon bremsstrahlung

;

c) muon trident produc-

ion (term with the time-like photon only) ; d ) neutri-

noproduction of a vector boson. The comparison of the

approximation with the exact calculation is made for

da/dW, where W is the invariant mass of the non-

hadronic system produced. The approximation works

well in general. As an application, we show the full

calculation of the muon trident process (except for the

correction due to the Pauli principle).

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