Inclusive production of phi, K*0, and K*0BAR mesons has been measured in gammap, pi+/-p and K+/-p collisions at beam energies of 65 GeV < E(gamma) < 175 GeV and E(pi/K) = 80 and 140 GeV. Cross sections have been determined over the range 0 < x(F) < 1.0 and 0 < p(t) < 1.8 GeV/c. Emphasis is put on the comparison of cross sections for different projectiles as a function of x(F) so as to study the effects of common quarks between the beam particle and the detected phi, K*0 or K*0BAR. The data are compared with a parton fusion model. Many features of the data are well explained. In detail the strange quark appears to carry a large fraction of the kaon momentum and the contribution of the valence quarks from the proton is small.

Inclusive production of ϕ,K*0, and <img src="/fulltext-image.asp?format=htmlnonpaginated&src=G60HU8N725243626_html\10052_2005_Article_BF01413177_TeX2GIFIE2.gif" border="0" alt=" $$\overline {K*^0 } $$ " /> mesons has been measured in γp, π±p andK± p collisions at beam energies of 65 GeVEγEπ/K =80 and 140 GeV. Cross sections have been determined over the range 0xFPTxF so as to study the effects of common quarks between the beam particle and the detected ϕ,K*0 or <img src="/fulltext-image.asp?format=htmlnonpaginated&src=G60HU8N725243626_html\10052_2005_Article_BF01413177_TeX2GIFIE3.gif" border="0" alt=" $$\overline {K*^0 } $$ " />. The data are compared with a parton fusion model. Many features of the data are well explained. In detail the strange quark appears to carry a large fraction of the kaon momentum and the contribution of the valence quarks from the proton is small.

Inclusive production of ϕ,K*0, and\(\overline {K*^0 } \) mesons has been measured in γp, π±p andK± p collisions at beam energies of 65 GeV<Eγ<175 GeV andEπ/K =80 and 140 GeV. Cross sections have been determined over the range 0<xF<1.0 and 0<PT<1.8 GeV/c. Emphasis is put on the comparison of cross sections for different projectiles as a function ofxF so as to study the effects of common quarks between the beam particle and the detected ϕ,K*0 or\(\overline {K*^0 } \). The data are compared with a parton fusion model. Many features of the data are well explained. In detail the strange quark appears to carry a large fraction of the kaon momentum and the contribution of the valence quarks from the proton is small.

Measurements are reported of inclusivef2(1270) andf0(975) production in ?p, p±p andK±p collisions at photon beam energies of 65 to 175 GeV and hadron beam energies of 80 and 140 GeV. Thef2 andf0 mesons were found at masses of 1.250 GeV and 0.961 GeV respectively. Inclusivef2 production at lowxF was found to have a similarpT dependence for each beam type, whereas an additional pion-exchange contribution was found for production by pions at highxF. Cross sections are compared with those for ?0 production and give no indication of a non-q <img src="/fulltext-image.asp?format=htmlnonpaginated&src=N1121682G127528P_html\10052_2005_Article_BF01555513_TeX2GIFIE1.gif" border="0" alt=" $$\bar q$$ " /> component in eitherf-meson state.

Measurements are reported of inclusivef2(1270) andf0(975) production in γp, π±p andK±p collisions at photon beam energies of 65 to 175 GeV and hadron beam energies of 80 and 140 GeV. Thef2 andf0 mesons were found at masses of 1.250 GeV and 0.961 GeV respectively. Inclusivef2 production at lowxF was found to have a similarpT dependence for each beam type, whereas an additional pion-exchange contribution was found for production by pions at highxF. Cross sections are compared with those for ρ0 production and give no indication of a non-q\(\bar q\) component in eitherf-meson state.

The inclusive production of ρ0 mesons was measured in γp andh±p collisions at beam energies of 65 GeV≦Eγ≦175 GeV andE h =80, 140 GeV, respectively, whereh is π orK. Cross sections were determined for all beams and energies as functions ofxF (−0.1≦xF≦1.0),pT (0≦pT≦3.5 GeV/c) and the polar decay angle of the ρ0 by fitting the ρ0 signal in π+π- mass distributions. The ρ0 line shape is found to be distorted from a pure Breit-Wigner distribution throughout most of thexF−pT plane for both photon and hadron beams and a simple explanation is suggested. Throughout the paper emphasis is put on the comparison of photon and hadron beam data. The comparison of cross sections of γp andhp data provides a measure of the Vector Meson Dominance factor throughout thexF−pT range of the ρ0. The ρ0 production at lowpT can be described for both photon and hadron beams by a triple regge model at largexF. Similarly central production is well described by the quark-antiquark fusion model. At largepT there is an excess of ρ0 photoproduction which is consistent with the expected onset of pointlike photon interactions.

Measurements are reported of inclusive production of η-mesons in the beam fragmentation region in γp, πp andKp collisions. Results include a small but significant departure from VMD, and a pronounced rise in theη/π0 ratio with increasingp T .

Measurements are reported of inclusive production of pi-0-mesons in the beam fragmentation region in gamma-p, pi-p and Kp collisions. Results include the ratio of pi-0 production in Kp and pi-p collisions, showing reduced production from fragmentation of the K-meson, and the ratio of pi-0 production in photon and hadron collisions which shows agreement with modified Vector Meson Dominance at low p(T), and departures at higher p(T) signalling the onset of direct photon reactions. The pattern of departure from Feynman scaling at high p(T) points to a contribution of hard parton-parton collisions in both gamma-p and pi-p collisions.

Measurements are reported of inclusive production of π0-mesons in the beam fragmentation region in γp, πp andKp collisions. Results include the ratio of π0 production inKp and πp collisions, showing reduced production from fragmentation of theK-meson, and the ratio of π0 production in photon and hadron collisions which shows agreement with modified Vector Meson Dominance at lowP T , and departures at higherP T signalling the onset of direct photon reactions. The pattern of departure from Feynman scaling at highP T points to a contribution of hard parton-parton collisions in both γp and πp collisions.

Photo- and hadroproduction data in the beam energy range 65–175 GeV have been studied with a view to isolating higher-twist processes in photoproduction from other point-like and hadron-like contributions. With selection of charged tracks havingp T >2 GeV/c and 0.28<x F <0.84 indications of a higher twist contribution have been found at a level that is consistent with QCD expectations.

The charged particle asymmetry, (n+−n−)/(n++n−), in inclusive photoproduction of charged particles on protons has been studied as a function ofx F andp T in the rangesx F >0 and 0<p T <2 GeV/c and for photon energies in the range 65<Eγ<175 GeV. The asymmetry is found to be positive and decreasing withEγ. Asymmetries of π's and K's in the final state have been obtained separately. Data from a carbon target show a significantly lower asymmetry. These results have been compared with a parton, recombination model which provides a qualitative explanation for the asymmetry and itsx F andEγ dependences. The model also gives a qualitative understanding of the lower asymmetry seen with the nuclear target.

Energy-flow distributions for charged hadrons from interactions of photons, pions and kaons on hydrogen are presented as functions of Σp T 2 in the event plane. Data cover the range 0.0<Σp T in 2 <10.0(GeV/c)2 and 0.0<x F <1.0 for beam momenta from 65 to 170 GeV/c. The comparisons between photon-and hadron-induced data show an excess of events with larger Σp T in 2 for the photon-induced data. Using the hadron-induced data to parameterise the hadronic behaviour of the photon, the differences between cross sections are used to measure the contribution of the point-like photon interactions. Quantitative calculations of the point-like photon interactions using the Lund Monte-Carlo program LUCIFER, based on QCD, are in agreement with the data.