-
J. Ashman,
B. Badelek,
G. Baum,
J. Beaufays,
C. P. Bee,
C. Benchouk,
I. G. Bird,
S. C. Brown,
M. C. Caputo,
H. W. K. Cheung, [......],
L. Urban,
H. Wahlen,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
J. Womersley,
K. Ziemons
[show abstract]
[hide abstract]
ABSTRACT: Final data measured with the EMC forward spectrometer are presented on the production of forward charged hadrons in p and d scattering at incident beam energies between 100 and 280 GeV. The large statistic of 373 000 events allows a study of the semi-inclusive hadron production as a function ofz,p
T
2
and p
T
2
in smallQ
2,x
Bj
andW bins. Charge multiplicity ratios and differences as a function ofz andx
Bj
are given forp, d andn-targets. From the differences of charge multiplicities the ratio of the valence quark distributions of the protond
v
(x)/u
v
(x) is determined for the first time in charged lepton scattering. The Gronau et al. sum rule is tested, the measured sum being 0.310.06 stat. 0.05 syst., compared with the theoretical expectation of 2/70.286. The measured sum corresponds to an absolute value of the ratio of thed andu quark charge of 0.440.10 stat.0.08 syst.
Zeitschrift für Physik C 08/1991; 52(3):361-387.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
J. Bedełek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: The general charge properties of the hadronic final state produced in
+
p and
+
d interactions at 280 GeV are investigated. Quark charge retention and local charge compensation is observed. The ratioF
2
n
/F
2
p
of the neutron to proton structure function is derived from the measurement of the average hadronic charge in d interactions.
Zeitschrift für Physik C 08/1988; 40(3):347-355.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: A comparison is made between the properties of the final state hadrons produced in 280 GeV p interactions and ine
+
e
– annihilation. The Lund model of hadroproduction is used as an aid in understanding the differences observed. The hadron distributions from p ande
+
e
– interactions are consistent with the quark parton model assumption of environmental independence, provided that the differences in heavy quark production and hard QCD effects in the two processes are taken into account. A comparison with aK
+
p experiment is also made. Values are also determined for the Lund model parameters q = 0.410 0.002 0.020 GeV and = 0.29
–0.15 –0.13
+0.09+0.10
GeV, controlling the transverse momenta in fragmentation and intrinsic transverse momenta of the struck quark respectively.
Zeitschrift für Physik C 11/1987; 35(4):417-431.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf,
K. Ziemons
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a study of deep inelastic 280 GeV muon-nucleon interactions on the transverse momenta and jet properties of the final state hadrons. The results are analysed in a way which attempts to separate the contributions of hard and soft QCD effects from those that arise from the fragmentation process. The fragmentation models with which the data are compared are the Lund string model, the independent jet model, the QCD parton shower model including soft gluon interference effects, and the firestring model. The discrimination between these models is discussed. Various methods of analysis of the data in terms of hard QCD processes are presented. From a study of the properties of the jet profiles a value of
s
, to leading order, is determined using the Lund string model, namely
s
=0.290.01 (stat.) 0.02 (syst.), forQ
220 GeV2.
Zeitschrift für Physik C 11/1987; 36(4):527-543.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badełek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: The multiplicity distributions of charged hadrons produced in the deep inelastic muon-proton scattering at 280 GeV are analysed in various rapidity intervals, as a function of the total hadronic centre of mass energy W ranging from 4–20 GeV. Multiplicity distributions for the backward and forward hemispheres are also analysed separately. The data can be well parameterized by binomial distributions, extending their range of applicability to the case of lepton-proton scattering. The energy and the rapidity dependence of the parameters is presented and a smooth transition from the negative binomial distribution via Poissonian to the ordinary binomial is observed.
Zeitschrift für Physik C 08/1987; 35(3):335-345.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
J. C. Thompson,
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders
[show abstract]
[hide abstract]
ABSTRACT: The production of strange particles has been studied in a 280 GeV muon nucleon scattering experiment with acceptance and particle identification over a large kinematical range. The data show that at large values ofx
Bj
the interactions take place mostly on au valence quark in agreement with the basic quarkparton model predictions. This feature results in a strong forward-backward asymmetry in the distribution of strangeness along the rapidity axis. The data are compatible with a strange to non-strange quark suppression factor of 0.3 and with a strong suppression of strange diquarks. The distributions ofK
+
K
– pairs show that the two kaons are preferentially produced at neighbouring values of rapidity.
Zeitschrift für Physik C 08/1987; 34(3):283-291.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blurn, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: Correlations between charged hadrons are investigated in a 280 GeV muon-proton scattering experiment. Although most of the observed particles are decay products it is shown that the correlations found originate in the fragmentation process and are not due simply to resonance production. Correlations are demonstrated between hadrons close in rapidity with respect to their charges and to the directions of their momentum components perpendicular to the virtual photon axis. Such short range correlations are predicted by the standard hadronization models.
Zeitschrift für Physik C 08/1986; 31(3):333-340.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: Inclusive distributions of 0 and mesons have been measured in deep inelastic -p interactions at 280 GeV/c. A comparison of the 0 cross sections with other leptoproduction experiments is presented. The results represent the first observation of this inclusive channel in high energy leptoproduction. The 0 and yields are found to be equal as may be expected from the available density of states in isospin space. This contrasts with spin angular momentum where the vector to pseudoscalar meson ratio is suppressed relative to the available number of spin states.
Zeitschrift für Physik C 05/1986; 33(2):167-173.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: The Bose-Einstein correlation has been observed for pions in deep inelastic p interactions at 280 GeV. The importance of non-interference correlations in the sample of like charge pion pairs and in the sample used for reference is discussed. The pion emission region is found to be roughly spherical in the pair rest frame with a radius of 0.46–0.84 fm and the chaos factor is 0.60–1.08.
Zeitschrift für Physik C 01/1986; 32(1):1-9.
-
M. Arneodo,
A. Arvidson,
J. J. Aubert,
B. Badelek,
J. Beaufays,
C. P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W. S. C. Williams,
S. J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: TheW andQ
2 dependence of the fragmentation functions and of the average multiplicity of charged pions is investigated, using data from the NA9 experiment at the CERN SPS on muon-proton scattering at 280 GeV. A significant increase of pion production with increasingW is observed at fixedQ
2, leading to a rise of the average charged pion multiplicity, linear in lnW
2, and of the pion fragmentation function in the central region, i.e. at small |x
F
|. This increase can be understood from the kinematic widening of the cms rapidity range proportional to lnW
2 and the observedW independent height of the rapidity distribution. At fixedW, a rise of the average charged pion multiplicity withQ
2 is observed. This rise appears to be weaker than that observed for all charged hadrons implying a stronger rise withQ
2 for kaons and protons.
Zeitschrift für Physik C 01/1986; 31(1):1-12.
-
A. Arvidson,
J. J. Aubert,
G. Bassompierre,
K. H. Becks,
C. Benchouk,
C. Best,
E. Böhm,
X. de Bouard,
F. W. Brasse,
C. Broll, [......],
J. M. Thénard,
J. C. Thompson,
L. Urban,
M. Villers,
H. Wahlen, M. Whalley,
D. Williams,
W. S. C. Williams,
J. Williamson,
S. J. Wimpenny
[show abstract]
[hide abstract]
ABSTRACT: The measurements of the z and pT2 distribution of
hadrons produced in the interactions of 200 GeV muons with copper and
carbon nuclei are shown in different xBj and virtual photon
energy intervals. Effects of the jet scattering are seen at the lowest
virtual photon energies while for energies above 70 GeV there is no
evidence of these effects. Comparison with a theoretical model indicates
that at high jet energies the parton fragmentation distance is greater
than the nuclear radius and that the parton absorption cross section is
less than 10 mb.
Nuclear Physics B 10/1984; 246:381-407. · 4.66 Impact Factor
-
J. J. Aubert,
G. Bassompierre,
K. H. Becks,
C. Benchouk,
C. Best,
E. Böhm,
X. de Bouard,
F. W. Brasse,
C. Broll,
S. Brown, [......],
J. M. Thénard,
J. C. Thompson,
L. Urban,
M. Villers,
H. Wahlen, M. Whalley,
D. Williams,
W. S. C. Williams,
J. Williamson,
S. J. Wimpenny
[show abstract]
[hide abstract]
ABSTRACT: Using a lead glass detector installed in the EMC forward spectrometer radiative photons have been measured in 200 GeV muon-hydrogen collisions. The results are compared with the standard QED one photon emission theory of Mo and Tsai and also with the more recent predictions of a multiphoton emission theory of Chahine. We conclude that there is no evidence for any deviation from the standard theory, in terms of the yield and angular distribution of photons with fractional energy,z>0.7.
Zeitschrift für Physik C 01/1984; 22(4):341-344.
-
J.J. Aubert,
G. Bassompierre,
K.H. Becks,
C. Best,
E. Böhm,
X. de Bouard,
F.W. Brasse,
C. Broll,
S. Brown,
J. Carr, [......],
J.M. Thénard,
J.C. Thompson,
L. Urban,
M. Villers,
H. Wahlen, M. Whalley,
D. Williams,
W.S.C. Williams,
J. Williamson,
S.J. Wimpenny
[show abstract]
[hide abstract]
ABSTRACT: Using the data on deep inelastic muon scattering on iron and deuterium the ratio of the nucleon structure functions F2N(Fe)/F2N(D) is presented. The observed x-dependence of this ratio is in disagreement with existing theoretical predictions.
Physics Letters B. 123:275-278.
-
M. Arneodo,
A. Arvidson,
J.J. Aubert,
B. Badelek,
J. Beaufays,
C.P. Bee,
C. Benchouk,
G. Berghoff,
I. Bird,
D. Blum, [......],
A. de la Torre,
J. Toth,
L. Urban,
W. Wallucks, M. Whalley,
S. Wheeler,
W.S.C. Williams,
S.J. Wimpenny,
R. Windmolders,
G. Wolf
[show abstract]
[hide abstract]
ABSTRACT: Measurements are presented of the variation with Q2 (scaling violation) of the hadron multiplicity in deep inelastic muon-proton scattering. An increase in the average multiplicity of both the charged hadrons and K0 mesons is observed with increasing Q2 or xBj for fixed centre-of-mass energy W. The study of the shape of the effective fragmentation function Dh (z, W, Q2) shows that the increase of the particle yield with Q2 takes place for low z particles. The variation of the hadron distributions with Q2 is also studied in the current fragmentation region where a decrease in multiplicity is observed. Such effects are expected from QCD.
Physics Letters B.
-
J.J. Aubert,
G. Bassompierre,
K.H. Becks,
C. Benchouk,
C. Best,
E. Böhm,
X. de Bouard,
F.W. Brasse,
C. Broll,
S. Brown, [......],
J.M. Thénard,
J.C. Thompson,
L. Urban,
M. Villers,
H. Wahlen, M. Whalley,
D. Williams,
W.S.C. Williams,
J. Williamson,
S. Wimpenny
[show abstract]
[hide abstract]
ABSTRACT: Exclusive ϱ0 production has been measured in 120, 200 and 280 GeV muon-proton interactions at high Q2 (1 GeV2 < Q2 < 25 GeV2) and W (6 GeV < W < 19 GeV). The photoproduction cross section decreases as 1/Q4. A shallow t distribution, typical of a hard scattering process is observed and the ϱ0 is found to be dominantly in the helicity zero spin state. The ϱ0s are mainly produced by transverse photons and s-channel helicity conservation seems to be invalid. The data cannot be described by the vector meson dominance model. These data show that at high Q2 even exclusive ϱ0 muoproduction is a hard scattering process and that the soft hadron-like properties of the photon have disappeared.
Physics Letters B.
-
J.J. Aubert,
G. Bassompierre,
K.H. Becks,
C. Best,
E. Böhm,
X. de Bouard,
F.W. Brasse,
C. Broll,
S. Brown,
J. Carr, [......],
J.M. Thénard,
J.C. Thompson,
L. Urban,
M. Villers,
H. Wahlen, M. Whalley,
D. Williams,
W.S.C. Williams,
J. Williamson,
S.J. Wimpenny
[show abstract]
[hide abstract]
ABSTRACT: Charm production has been studied through multimuon events produced in 250 GeV μ+-interactions. The measured dimuon cross section is in agreement with the photon gluon fusion model at low values of Bjorken x within statistical and systematic errors. At larger values of xBi the data do not support the magnitude of intrinsic charm used to explain hadro-production of charm. Upper limits on the intrinsic charm content of the nucleon are derived from the data.
Physics Letters B.
-
J. J. Aubert,
G. Bassompierre,
K. H. Becks,
C. Best,
E. Böhm,
X. de Bouard,
F. W. Brasse,
C. Broll,
S. C. Brown,
J. Carr, [......],
H. E. Stier,
W. Stockhausen,
J. M. Thénard,
J. C. Thompson,
L. Urban,
H. Wahlen, M. Whalley,
W. S. C. Williams,
J. Williamson,
S. J. Wimpenny
Nuclear Physics B 293:740-786. · 4.66 Impact Factor
-
Jean-Jacques Aubert,
Gabriel Bassompierre,
K H Becks,
C Best,
E Böhm,
X de Bouard,
F W Brasse,
C Broll,
S Brown,
J Carr, [......],
J M Thénard,
J C Thompson,
L Urbàn,
M Villers,
H Wahlen, M Whalley,
D Williams,
W S C Williams,
J Williamson,
S J Wimpenny
-
Jean-Jacques Aubert,
Gabriel Bassompierre,
K H Becks,
C Best,
E Böhm,
X de Bouard,
F W Brasse,
C Broll,
S Brown,
J Carr, [......],
J M Thénard,
J C Thompson,
L Urbàn,
M Villers,
H Wahlen, M Whalley,
D Williams,
W S C Williams,
J Williamson,
S J Wimpenny
-
Jean-Jacques Aubert,
Gabriel Bassompierre,
K H Becks,
C Best,
E Böhm,
X de Bouard,
F W Brasse,
C Broll,
S Brown,
J Carr, [......],
H E Stier,
W S Stockhausen,
J M Thénard,
J C Thompson,
L Urbàn,
H Wahlen, M Whalley,
W S C Williams,
J Williamson,
S J Wimpenny
