The proton and deuteron structure functions F p 2 and F d 2 were measured in the kinematic range 0.006 < x < 0.6 and 0.5 < Q < 75 GeV, by inclusive deep inelastic muon scattering at 90, 120, 200 and 280 GeV. The measurements are in good agreement with earlier high precision results. The present and earlier results together have been parametrised to give descriptions of the proton and deuteron structure functions F2 and their uncertainties over the range 0.006 < x < 0.9.

Results are presented for F2d/F2p and Rd-Rp from simultaneous measurements of deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120, 200 and 280 GeV. The difference Rd-Rp, determined in the range 0.0020.1 the ratio decreases with Q^2.

Results are presented for F~/FP2 and R d-R p from simultaneous measurements of deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120, 200 and 280 GeV. The difference R d-R p, determined in the range 0.002 < x < 0.4 at an average Q2 of 5 GeV 2, is compatible with zero. The x and Q2 dependence of Fd/FP 2 was measured in the kinematic range 0.001 < x < 0.8 and 0.1 < Q2 < 145 GeV 2 with small statistical and systematic errors. For x > 0.1 the ratio decreases with Q2.

Results are presented for six nuclei from Be to Pb on the structure function ratios F-2(A)/F-2(C)(X) and their A dependence in deep inelastic muon scattering at 200 GeV incident: muon energy. The data cover the kinematic range 0.01 < x < 0.8 with Q(2) ranging from 2 to 70 GeV2. The A dependence of nuclear structure function ratios is parametrised and compared to various models.

The Q(2) dependence of the structure function ratio F-2(Sn)/F-2(C) for 0.01 < x < 0.75 and 1 < Q(2) < 140 GeV2 is reported. For x < 0.1 the size of shadowing decreases linearly with In Q(2) and the maximum rate is about 0.04 at x = 0.01. The rate decreases with x and is compatible with zero for x greater than or equal to 0.1. The difference R(Sn) - R(C), where R is the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, is also given. No dependence on x is seen and the average value is 0.040 +/- 0.021 (stat.) +/- 0.026 (syst.) at a mean Q(2) of 10 GeV2.

We present a re-evaluation of the structure function ratios F2(He)/F2(D), F2(C)/F2(D) and F2(Ca)/F2(D) measured in deep inelastic muon-nucleus scattering at an incident muon momentum of 200 GeV. We also present the ratios F2(C)/F2(Li), F2(Ca)/F2(Li) and F2(Ca)/F2(C) measured at 90 GeV. The results are based on data already published by NMC; the main difference in the analysis is a correction for the masses of the deuterium targets and an improvement in the radiative corrections. The kinematic range covered is 0.0035 < x < 0.65, 0.5 < Q^2 <90 GeV^2 for the He/D, C/D and Ca/D data and 0.0085 < x < 0.6, 0.84 < Q^2 < 17 GeV^2 for the Li/C/Ca ones.

We present the structure function ratios F2(Li)/F2(D) and F2(C)/F2(D) measured in deep inelastic muon-nucleus scattering at a nominal incident muon energy of 200 GeV. The kinematic range 0.0001 < x < 0.7 and 0.01< Q^2 < 70 GeV^2 is covered. For values of x less than 0.002 both ratios indicate saturation of shadowing at values compatible with photoabsorption results.

We present the structure function ratios F-2(Li)/F-2(D) and F-2(C)/F-2(D) measured in deep inelastic muon-nucleus scattering at a nominal incident muon energy of 200 GeV. The kinematic range 10(-4) < x < 0.7 and 0.01 < Q(2) < 70 GeV2 is covered. For values of x less than 0.002 both ratios indicate saturation of shadowing at values compatible with photoabsorption results.

The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q(2) < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full data set collected by the New Muon Collaboration, including the data taken with a small angle trigger. The extracted values of the structure functions F-2(p) and F-2(d) are in good agreement with those from other experiments. The data cover a sufficient range of y to allow the determination of the ratio of the longitudinally to transversely polarised virtual photon absorption cross sections, R = sigma(L)/sigma(T), for 0.002 < x < 0.12. The values of R are compatible with a perturbative QCD prediction; they agree with earlier measurements and extend to smaller x.

We present a new determination of the nonsinglet structure function F2p - F2n at Q2 = 4 GeV2 using recently measured values of Fd2 and F2n/F2p. A new evaluation of the Gottfried sum is given, which remains below the simple quark-parton model value of 1/3.

Quasielastic production of J/psi mesons has been measured in muon interactions with hydrogen, deuterium, carbon and tin targets at incident muon energies of 200 and 280 GeV. The hydrogen and deuterium data were used to study the transverse momentum distribution of the J/psi's. These data have been analysed together with previously published rho0 data in the framework of the vector meson dominance model. The radii of the J/psi and the rho0 as well as the total J/psi-N and rho0-N cross sections were deduced. From the tin and carbon data the ratio of the quasielastic J/psi production cross sections, R(qe)(Sn/C), has been extracted and found to be less than unity. In the Glauber approach this suppression can be related to the J/psi absorption probability in nuclei. The suppression is also compared to those predicted by various colour transparency models.

Exclusive rho(0) and phi muoproduction on deuterium, carbon and calcium has been studied in the kinematic range 2 < Q(2) < 25 GeV2 and 40 < nu < 180 GeV. We discuss the Q(2) dependence of the cross sections, the transverse momentum distributions for the vector mesons, the decay angular distributions and, in the case of the rho(0), nuclear effects. The data for rho(0) production are compatible with a diffractive mechanism. The distinct features of phi production are a smaller cross section and less steep p(t)(2) distributions than those for the rho(0) mesons.

The Q2 dependence of the structure functions F2p and F2d recently measured by the NMC is compared with the predictions of perturbative QCD at next-to-leading order. Good agreement is observed, leading to accurate determinations of the quark and gluon distributions in the range 0.008 ⩽ × ⩽ 0.5. The strong coupling constant is measured from the low x data; the result agrees with previous determinations.

The structure functions F2p and F2d measured by deep inelastic muon scattering at incident energies of 90 and 280 GeV are presented. These measurements cover a large kinematic range, 0.006 less-than-or-equal-to x less-than-or-equal-to 0.6 and 0.5 less-than-or-equal-to Q2 less-than-or-equal-to 55 GeV2, and include the first precise data at small x, where large scaling violations are observed. The data agree with earlier results from SLAC and BCDMS but exhibit differences with respect to those of EMC-NA2. Extrapolations to small x of recent phenomenological parton distributions are shown to disagree with the present results.

Results are presented on the difference in R, the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, for the deuteron and the proton. They are obtained by comparing the ratio of cross sections for the deep inelastic scattering of muons from deuterium and hydrogen targets at 90 and 280 GeV incident energy. The results cover the range x = 0.01 -0.30, at an average Q2 of 9 GeV2. The measured difference R(d)-R(p) shows no significant x dependence and is compatible with zero, as well as with expectations from perturbative QCD. We use the same method to obtain the difference R(Ca)-R(C) from cross section ratios measured on carbon and calcium targets at 90 and 200 GeV incident energy.

Exclusive p°and q~muoproductionon deuterium,carbonand calciumhasbeen studiedin the kinematic range2 < Q2 <25GeV2 and40 < ii < 180GeV.We discussthe Q2 dependence of the crosssections,the transversemomentumdistributions for the vectormesons,the decayangular distributions and, in the caseof the p°,nucleareffects.The datafor p°productionarecompatible with a diffractive mechanism.The distinct featuresof q5 productionare a smallercrosssection and less steepp~distributions thanthosefor the p°mesons.