PHYSICAL REVIEW C VOLUME 48, NUMBER 5 NOVEMBER 1993 Evidence for short-range correlations from high Q (e, e') reactions L. L. Frankfurt Department of Physics, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel M. I. Strikman Department of Physics, Pennsylvania State University, State College, Pennsylvania 16802 D. B. Day Institute of Nuclear and Particle Physics, University of Virginia, Charlottesville, Virginia gg901 M. Sargsyan Yerevan Physical Institute, Yerevan, Armenia (Received 20 April 1992) We argue that the ratio of cross sections of quasielastic electron scattering for heavy and light nuclei at z ) 1 and Q ) 1 (GeV jc) should exhibit simple scaling relations which are ultimately expressed through the ratio of the light-cone nucleon distributions in nuclei. We extract these cross section ratios from existing data in a practically model independent way. The results are found to be in reasonable agreement with our x-scaling relations for the region of 2 ) x ) 1. 4 where the contribution of two-nucleon short-range correlations are expected to dominate. The ratios exhibit scaling in the light-cone fraction, n, of the struck nucleon for the range 2 ) x ) 0.9. The o. scaling is in agreement with the expectations of the light-cone quantum mechanics of nuclei, providing further evidence for the dominance of short-range correlations in nuclei at h ) 0.3 GeV jc. An extension of this analysis to the interpretation of color transparency experiments is discussed. PACS number(s): 25.30. Fj I. INTRODUCTION For many years now short-range correlations (SRC) in nuclei have been considered as an essential feature of the nuclear wave function. However, at medium energies the inQuence of SRC is hidden by the effects of multistep processes dominated by the soft (low momentum) com- ponents of the wave function. The situation improves significantly at high energies which allow one to select processes in which (a) the scattering from low momen- tum nucleons is kinematically suppressed and (b) the en- ergy transfer exceeds the characteristic kinetic energies of correlated nucleons in the nucleus. One of the simplest reactions which satisfies both these requirements is A(e, e') at 2 Q ) 1(GeV/c) and x = ) 1, 2mqo 1 GeV & qo & 300 400 MeV, where m = mN and qo is the energy transfer. These reactions have been intensively investigated during the last decade or so at SLAC on both light and heavy nuclei [1 — 5]. In this paper we argue for the existence of simple scaling relations between the cross sections of light and heavy nuclei in the kinematics where electron scattering off SRC should dominate. We present ratios extracted. from data which demonstrate that these relations are reasonably well satisfied and which emphasize the dom- inance of two-nucleon SRC in the spectral function for A: ) 0. 3 GeV/c. This paper is organized as follows. In Sec. II we ex- plain the specifics of the space-time evolution of the final states in the A(e, e') reactions in the kinematics given by Eq. (1), which helps us account for the final state interac- tion (fsi). In Sec. III we use the nonrelativistic impulse approximation to deduce the scaling relations between cross sections of the A(e, e') reaction on difFerent nuclei. Therein we explain how, within our model, the fsi cancels in the ratios of the cross secticns, though it contributes to the individual cross sections. In Sec. IV we describe the procedure we developed for extracting the ratios &om existing experimental data and demonstrate that the ex- tracted ratios agree with the scaling relations. In Sec. V we explain why and how relativistic kinematics leads to the light-cone dynamics of the process. We generalize the scaling relations for relativistic kinematics and calculate the ratios of the cross sections in terms of the light-cone quantum mechanics of nuclei. We also explain in Sec. V how the extracted ratios could be used to improve anal- yses of A(e, e'p) experiments at large Q2 undertaken to investigate color transparency phenomena. In the Ap- pendix we discuss the fsi of the struck nucleon with the slow nucleons of the nucleus. The physics of quasielastic processes [which doininates the cross section in the kinematics of Eq. (1)] has been discussed in detail in the analyses [6,7], so that here we only outline the ideas leading to basic formulas. 0556-2813/93/48(5)/2451(11)/$06. 00 48 2451 1993 The American Physical Society