-
A. Bazan,
F. Bellachia,
A. Blondel,
J. Colas,
M. Citterio,
M.D. Gomez,
L. Fayard,
G. Ionescu,
M. Kado,
A. Karev, [......],
L. Poggioli,
J. Prast,
H. Przysiezniak,
I.R. Dachs,
S. Simion,
W. Sippach,
A. Straessner,
G. Unal,
H. Wilkens, I. Wingerter
[show abstract]
[hide abstract]
ABSTRACT: The Liquid Argon calorimeters play a central role in the ATLAS experiment. The environment at the LHC collider imposes challenging tasks to their read-out system. To achieve measurements of particles and trigger signals at high precision, the detector signals are processed at various stages before reaching the Data Acquisition system (DAQ). Signals from the calorimeter cells are received by front-end boards, which digitize and sample the incoming pulse. Read-out Driver (ROD) boards further process the data at a trigger rate of up to 75 kHz. An optimal filtering procedure is applied to optimize the signal-to-noise ratio. The ROD boards calculate precise energy, time and quality of the detector pulse, which are then sent to the DAQ. In addition, the RODs perform a monitoring of the data. The architecture of the ATLAS Liquid Argon detector read-out is discussed, in particular the design and functionality of the ROD board. Performance results obtained with ROD prototypes as well as experience from complete test setups with final production boards are reported.
IEEE Transactions on Nuclear Science 07/2006; · 1.45 Impact Factor
-
A Lai,
D Marras,
R Batley,
A Bevan,
R S Dosanjh,
T J Gershon,
G E Kalmus,
D J Munday,
E Olaiya,
M A Parker, [......],
S Wronka,
H Dibon,
G Fischer,
M Jeitler,
M Markytan,
I Mikulec,
G Neuhofer,
M Pernicka,
A Taurok,
L Widhalm
[show abstract]
[hide abstract]
ABSTRACT: A search for the decay KS → π0γγ has been made using the NA48 detector at the CERN SPS. Using data collected in 1999 during a 40-hour run with a high-intensity KS beam, an upper limit for the branching ratio BR(KS → π0γγ, z ≥ 0.2) < 3.3 x 10-7 has been obtained at 90% confidence level, where z = m2 γγ/mKO 2. © 2003 Published by Elsevier Science B.V.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. 01/2003; 556(3-4):105-113.
-
P. D. Acton,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
S. Arcelli,
P. Ashton,
A. Astbury,
D. Axen,
G. Azuelos, [......],
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
M. Yurko,
I. Zacharov,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: We present an analysis of multiplicity distributions of charged particles produced inZ
0 hadronic decays. The results are based on the analysis of 82941 events collected within 100 MeV of theZ
0 peak energy with the OPAL detector at LEP. The charged particle multiplicity distribution, corrected for initial-state radiation and for detector acceptance and resolution, was found to have a mean n
ch=21.400.02(stat.)0.43(syst.) and a dispersionD=6.490.02(stat.)0.20(syst.). The shape is well described by the Lognormal and Gamma distributions. A negative binomial parameterisation was found to describe the shape of the multiplicity distribution less well. A comparison with results obtained at lower energies confirms the validity of KNO(-G) scaling up to LEP energies. A separate analysis of events with low sphericity, typically associated with two-jet final states, shows the presence of features expected for models based on a stochastic production mechanism for particles. In all cases, the features observed in the data are well described by the Lund parton shower model JETSET.
Zeitschrift für Physik C 11/1992; 53(4):539-554.
-
P. D. Acton,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
S. Arcelli,
P. Ashton,
A. Astbury,
D. Axen,
G. Azuelos, [......],
T. Wlodek,
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
M. Yurko,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: The value of the strong coupling constant,
as (MZ0 )\alpha _s (M_{Z^0 } )
, is determined from a study of 15 different observables in hadronicZ
0 and as (MZ0 ) = 0.122 - 0.005 + 0.006\alpha _s (M_{Z^0 } ) = 0.122_{ - 0.005}^{ + 0.006}
in. The error is dominated by the theoretical uncertainties. Application of recent calculations which include the resummation of leading and next-to-leading logarithms to all orders for some observables confirm this result with a reduced sensitivity to renormalization scale variations. TheZ
0 line shapes and as (MZ0 ) = 0.148 ±0.021\alpha _s (M_{Z^0 } ) = 0.148 \pm 0.021
and
as (MZ0 ) = 0.123 - 0.007 + 0.006\alpha _s (M_{Z^0 } ) = 0.123_{ - 0.007}^{ + 0.006}
, respectively, in. These measurements and their uncertainties are entirely independent of each other and from event shape and jet observables; the good agreement of the resulting s values thus constitutes an important consistency check of the reliability of perturbative QCD.
Zeitschrift für Physik C 02/1992; 55(1):1-24.
-
P. D. Acton,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
S. Arcelli,
P. Ashton,
A. Astbury,
D. Axen,
G. Azuelos, [......],
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
M. Yurko,
I. Zacharov,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: From a sample of approximately 135 000 hadronic Z0 decays
recorded with the OPAL detector, 1 536 events were selected with two
lepton candidates, either electrons or muons. A signal for
B0-B0 mixing was observed using the sign of the
lepton charge to tag the charge of the b quark in decaying b-flavoured
hadrons. A flavour discriminating variable was constructed from the
lepton momentum and its component perpendicular to the jet axis. By
fitting the fraction of events in which the two lepton charges are of
the same sign, as a function of this variable, the average mixing
parameter was measured to be χ =
0.145+0.041-0.035 +/- 0.018, where the first error
is statistical and the second is systematic.
Physics Letters B 01/1992; 276:379-392. · 3.95 Impact Factor
-
P. D. Acton,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
S. Arcelli,
P. Ashton,
A. Astbury,
D. Axen,
G. Azuelos, [......],
T. Wlodek,
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
M. Yurko,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: The production rate of electrons with momentump>4 GeV/c and large momentum transverse to the jet containing the electron has been measured in 136000 hadronic decays of theZ
0 recorded with the OPAL detector at LEP in 1990. The dominant source of these electrons is the semileptonic decay of hadrons containingb quarks. If we assume that the semileptonic branching fraction ofb hadrons produced on theZ
0 resonance is the same as the branching fraction measured at the Gb[`(b)] = 394 ±13 ±32\Gamma _{b\bar b} = 394 \pm 13 \pm 32
MeV, where the first error is statistical and the second error is systematic. The sensitivity of the result to this assumption is discussed. We have reduced the dependence of our result on the model ofb hadron semileptonic decay by taking into account the correlation between the model dependence of the branching fractions measured at the (4S) and of our kinematic acceptance for electrons.
Zeitschrift für Physik C 01/1992; 55(2):191-207.
-
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
S. Arcelli,
J. C. Armitage,
P. Ashton,
A. Astbury,
D. Axen,
G. Azuelos, [......],
V. -H. Winterer,
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
I. Zacharov,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: Three-jet variables constructed from multi-hadronic events produced byZ
0 decays are compared to theoretical calculations assuming a vector gluon or a hypothetical scalar gluon. The data yield conclusive direct evidence for the former case. The distributions of the reduced energy of the second-most energetic jet and of the cosine of the Ellis-Karliner angle are chosen to demonstrate this effect.
Zeitschrift für Physik C 11/1991; 52(4):543-550.
-
M. Z. Akrawy,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
J. C. Armitage,
G. T. J. Arnison,
P. Ashton,
G. Azuelos,
J. T. M. Baines, [......],
V. -H. Winterer,
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
T. Yoshida,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: The OPAL detector at LEP is used to measure the branching ratio of theZ
0 into invisible particles by measuring the cross section of single photon events ine
+
e
– collisions at centre-of-mass energies near theZ
0 resonance. In a data sample of 5.3 pb–1, we observe 73 events with single photons depositing more than 1.5 GeV in the electromagnetic calorimeter, with an expected background of 82 events not associated with invisibleZ
0 decay. With this data we determine theZ
0 invisible width to be 0.500.070.03 GeV, where the first error is statistical and the second systematic. This corresponds to 3.00.40.2 light neutrino generations in the Standard Model.
Zeitschrift für Physik C 08/1991; 50(3):373-384.
-
M. Z. Akrawy,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
J. C. Armitage,
G. T. J. Arnison,
P. Ashton,
G. Azuelos,
J. T. M. Baines, [......],
N. C. Wood,
S. Wotton,
B. Wuensch,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
T. Yoshida,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: Jet production rates in hadronicZ
0 decays are studied using four different recombination schemes to define resolvable jets. The strong coupling constant MZ0 M_{Z^0 }
) is determined in fits of the correspondingO(MZ0 M_{Z^0 }
), leading to a final result of
as (MZ0 ) = 0.118 ±0.008.\alpha _s (M_{Z^0 } ) = 0.118 \pm 0.008.
.The error includes the experimental uncertainties (0.003), uncertainties of hadronisation corrections and of the degree of parton virtualities to which the data are corrected, as well as the uncertainty of choosing the renormalisation scale.
Zeitschrift für Physik C 08/1991; 49(3):375-384.
-
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
S. Arcelli,
J. C. Armitage,
P. Ashton,
A. Astbury,
D. Axen,
G. Azuelos, [......],
V. H. Winterer,
N. C. Wood,
S. Wotton,
T. R. Wyatt,
R. Yaari,
Y. Yangh,
G. Yekutieli,
I. Zacharov,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: We report on an improved measurement of the mass of theZ
0 boson, its total width and its partial decay widths into hadrons and leptons, as well as the effective axial vector and vector couplings to charged leptons. These measurements are based on a data set of approximately 160 000 hadronicZ
0 decays and 18 000 decays into electrons, muons and taus, recorded by the OPAL experiment at centre of mass energies near the mass of theZ
0. The total width and the partial widths to visible final states, derived from the measured cross sections, are used to extract the invisible width. The effective couplings of theZ
0 to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at the different centre of mass energy points of theZ
0 scan. The implications of our results in the context of the Standard Model are discussed.
Zeitschrift für Physik C 05/1991; 52(2):175-207.
-
M. Z. Akrawy,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
J. C. Armitage,
G. T. J. Arnison,
P. Ashton,
G. Azuelos,
J. T. M. Baines, [......],
N. C. Wood,
S. Wotton,
B. Wuensch,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
T. Yoshida,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: Four-jet final states of hadronicZ
0 decays, observed ine
+
e
– annihilation around 91 GeV centre of mass energy, are analysed in terms of observables that are sensitive to the non-abelian gauge structure of QCD. After correction for detector resolution and fragmentation effects, the data are compared to QCD and also to predictions of the Abelian vector gluon gauge theory. The theoretical expectations are calculated in both second order and leading logarithmic approximation of perturbation theory. The data are compatible with QCD but cannot be described by the predictions of the Abelian vector gluon models. From the measured topological distributions, upper limits for the relative production rates of
q[`(q)]q[`(q)]q\bar qq\bar q
final states are derived.
Zeitschrift für Physik C 02/1991; 49(1):49-57.
-
M. Z. Akrawy,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
J. C. Armitage,
G. T. J. Arnison,
P. Ashton,
G. Azuelos,
J. T. M. Baines, [......],
N. C. Wood,
S. Wotton,
B. Wuensch,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
T. Yoshida,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: A search for minimal standard model (MSM) and minimal supersymmetric model (MSSM), Higgs bosons with masses larger than 3 GeV/c2 has been performed by the OPAL collaboration one
+
e
– data from LEP corresponding to an integrated luminosity of 1.24 pb–1. The limits for MSM Higgs bosons have been obtained using the channelsZ
0[`(v)]\bar v
ore
+
e
– or +, –. The search for MSSM Higgs bosons has been performed using the channelsZ
0[`(v)]\bar v
ore
+
e
– or +–),h
0 [`(q)]\bar q
andZ
0mH0 m_{H^0 }
2 at the 95% confidence level; limits on the masses of the two lightest neutral MSSM Higgs bosons are obtained forh
0 mases up to 40.5 GeV/c2.
Zeitschrift für Physik C 01/1991; 49(1):1-15.
-
M. Z. Akrawy,
G. Alexander,
J. Allison,
P. P. Allport,
K. J. Anderson,
J. C. Armitage,
G. T. J. Arnison,
P. Ashton,
G. Azuelos,
J. T. M. Baines, [......],
N. C. Wood,
S. Wotton,
B. Wuensch,
T. R. Wyatt,
R. Yaari,
Y. Yang,
G. Yekutieli,
T. Yoshida,
W. Zeuner,
G. T. Zorn
[show abstract]
[hide abstract]
ABSTRACT: We present measurements of global event shape distributions in the hadronic decays of theZ
0. The data sample, corresponding to an integrated luminosity of about 1.3 pb–1, was collected with the OPAL detector at LEP. Most of the experimental distributions we present are unfolded for the finite acceptance and resolution of the OPAL detector. Through comparison with our unfolded data, we tune the parameter values of several Monte Carlo computer programs which simulate perturbative QCD and the hadronization of partons. Jetset version 7.2, Herwig version 3.4 and Ariadne version 3.1 all provide good descriptions of the experimental distributions. They in addition describe lower energy data with the parameter values adjusted at theZ
0 energy. A complete second order matrix element Monte Carlo program with a modified perturbation scale is also compared to our 91 GeV data and its parameter values are adjusted. We obtained an unfolded value for the mean charged multiplicity of 21.280.040.84, where the first error is statistical and the second is systematic.
Zeitschrift für Physik C 11/1990; 47(4):505-521.
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
G. Arnison,
A. Astbury,
B. Aubert,
T. Axon,
C. Bacci,
T. Bacon,
N. Bains, [......], I. Wingerter,
S. J. Wimpenny,
X. Wu,
C. E. Wulz,
T. Wyatt,
M. Yvert,
I. Zacharov,
N. Zaganidis,
L. Zanello,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: An extensive study of production and decay properties of charged and neutral Intermediate Vector Bosons (IVB) at the CERN proton-antiproton collider is presented. Intermediate Vector Bosons were detected in the electron, muon, and tau decay modes at centre-of-mass energies of 0.546 and 0.630 TeV. This paper is a summary, based on all the available data from the UA1 experiment from the running periods 1982–1985. Results are presented and compared with expectations of the Standard Eletroweak Model and QCD-improved Drell-Yan annihilation processes. The general conclusion is that there is an excellent agreement between the predictions of the Standard Model and our measurements.
Zeitschrift für Physik C 01/1989; 44(1):15-61.
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
A. Astbury,
B. Aubert,
T. Axon,
C. Bacci,
T. Bacon,
N. Bains,
J. R. Batley, [......],
S. J. Wimpenny,
X. Wu,
C. -E. Wulz,
T. Wyatt,
M. Yvert,
C. Zaccardelli,
I. Zacharov,
N. Zaganidis,
L. Zanello,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for new heavy quarks using data collected by the UA1 experiment during 1983, 1984 and 1985 at the CERN proton-antiproton collider, corresponding to an integrated luminosity of approximately 700 nb–1. Studying events with a muon or an isolated electron, accompanied by one or more jets, we find good agreement between our data and Monte Carlo predictions for the production of charm and beauty, without the need for a new quark. A top quark model, involving the decayW[`(b)]\bar b
and directt
[`(t)]\bar t
production via the strong interaction, is used to determine our detection efficiency for top. This allows us to place an upper limit on the cross section for producing top quarks as a function of the top quark mass. Our analysis is not sensitive to theW[`(b)]\bar b
process alone. By comparing our limit with a calculation of thet
[`(t)]\bar t
cross section, added to theW[`(b)]\bar b
cross section derived from our own measurements ofW mtop > 44GeV/c2 ( 95% c.l. ).m_{top} > 44GeV/c^2 \left( {95\% c.l.} \right).
Including an estimate of the next higher order (mtop > 56GeV/c2 ( 95% c.l. ).m_{top} > 56GeV/c^2 \left( {95\% c.l.} \right).
A search has also been made for a fourth generation, charge 1/3 quark (b'). Assuming that theb' mass is smaller than that of the top quark and that it can-not be produced inW decays, the mass limits, using the above procedures, are respectivelym
b'
>32 GeV/c2 andm
b'
>44 GeV/c2, both at 95% confidence level.
Zeitschrift für Physik C 11/1988; 37(4):505-525.
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
A. Astbury,
B. Aubert,
T. Axon,
C. Bacci,
T. Bacon,
N. Bains,
J. R. Batley, [......],
S. J. Wimpenny,
X. Wu,
C. -E. Wulz,
T. Wyatt,
M. Yvert,
C. Zaccardelli,
I. Zacharov,
N. Zaganidis,
L. Zanello,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: We present a study of heavy flavour (charm and beauty) production using data collected with the UA1 detector at the CERN Proton-Antiproton collider at a centre-of-mass energy of 630 GeV for an integrated luminosity of 556 nb–1. This follows our earlier study ofb
[`(b)]\bar b
andc
[`(c)]\bar c
production in dimuon events and the evidence for mixing betweenB
0 and
[`(B)]0\bar B^0
states. Properties of an inclusive sample of events containing a muon withp
T
>6 GeV/c are compared with QCD predictions for heavy flavour production, using the ISAJET Monte Carlo program. The predicted largep
T
muon yield from heavy flavour production and decay agrees with the data to within 30%. For events with a muon ofp
T
>10 GeV/c and at least one jet withE
T
>10 GeV, we measure the ratio charm/(charm+beauty) to be (2489)%. We also show that the correlations observed between the two heavy quark jets expected by flavour conservation are consistent with the mixture of lowest and higher order QCD processes. We study in detail the topological and kinematic properties of a subsample of events containing a highp
T
muon and one or more jets. The good agreement of the theoretical predictions with our data in a region dominated by the production of charm and beauty shows that one of the main background sources to a new heavy quark signature is well understood.
Zeitschrift für Physik C 11/1988; 37(4):489-503.
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
A. Astbury,
B. Aubert,
T. Axon,
C. Bacci,
T. Bacon,
N. Bains,
J. R. Batley, [......],
S. J. Wimpenny,
X. Wu,
C.-E. Wulz,
T. Wyatt,
M. Yvert,
C. Zaccardelli,
I. Zacharov,
N. Zaganidis,
L. Zanello,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: The production of transverse energy clusters in minimum bias
proton-antiproton collisions at the CERN SPS Collider is studied with
the UA1 detector over a new range of centre of mass energies (√s =
0.2-0.9 TeV). This study is intended to investigate how low in
transverse momentum perturbative QCD is able to describe the dynamics of
hadron collisions. We observe that clusters with transverse energy in
excess of a few GeV exhibit properties in agreement with QCD
expectations for parton scattering, supporting their interpretation in
terms of jet production. We find that the jet-event rate represents a
sizeable fraction of the inelastic rate and is increasing with √s
over the measured energy range.
Nuclear Physics B 10/1988; 309:405-425. · 4.66 Impact Factor
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
G. Arnison,
A. Astbury,
B. Aubert,
T. J. Axon,
C. Bacci,
T. Bacon,
N. Bains, [......],
S. J. Wimpenny,
X. Wu,
C. -E. Wulz,
T. Wyatt,
M. Yvert,
C. Zaccardelli,
I. Zacharov,
N. Zaganidis,
L. Zanello,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: This is the first full solid angle analysis of large transverse energy events in
p[`(p)]p\bar p
collisions at the CERN collider. Events with transverse energies in excess of 200 GeV at
Ös = 630 GeV\sqrt s = 630 GeV
are studied for any non-standard physics and quantitatively compared with expectations from perturbative QCD Monte Carlo models. A corrected differential cross section is presented. A detailed examination is made of jet profiles, event jet multiplicities and the fraction of the transverse energy carried by the two jets with the highest transverse jet energies. There is good agreement with standard theory for events with transverse energies up to the largest observed values
( » Ö{s/2} )( \approx \sqrt {s/2} )
and the analysis shows no evidence for any non-QCD mechanism to account for the event characteristics.
Zeitschrift für Physik C 02/1987; 36(1):33-43.
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
G. Arnison,
A. Astbury,
B. Aubert,
T. Axon,
C. Bacci,
T. Bacon,
N. Bains, [......],
S. J. Wimpenny,
X. Wu,
C.-E. Wulz,
T. Wyatt,
M. Yvert,
C. Zaccardelli,
I. Zacharov,
N. Zaganidis,
L. Zanello,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for B0↔B oscillations
(mixing) using events with two identified muons from data collected at
the CERN p¯p collider. In the absence of
B0↔B oscillations, dimuons coming directly
from decays of beauty-antibeauty paris must have opposite signs.
Like-sign dimuons are expected from events where one muon arises from
beauty decay and the other from the charm decay of the associated
beauty-charm cascade. Taking these processes into account, together with
the contribution from charm production, the predicted ratio of like-sign
to unlike-sign muon pairs is 0.26±0.03. Experimentally we measure
0.42±0.07±0.03. A natural explanation for the excess of
like-sign events is the existence of a significant amount of
B0↔B transitions. The fraction of beauty
particles that produce first-generation decay muons with the opposite
electric charge from that expected without mixing is deduced to be:
χ = 0.121±0.047. Combined with the null result from searches
for B0↔B oscillations at
e+e- colliders, our results are consistent
with transitions inthe B0s system, as favoured
theoretically.
Physics Letters B 02/1987; 186:247-254. · 3.95 Impact Factor
-
G. Arnison,
M. G. Albrow,
O. C. Allkofer,
A. Astbury,
B. Aubert,
C. Bacci,
J. R. Batley,
G. Bauer,
A. Bézaguet,
R. K. Bock, [......],
V. Vuillemin,
H. D. Wahl,
P. Watkins,
R. Wilke,
J. Wilson, I. Wingerter,
C.-E. Wulz,
T. Wyatt,
M. Yvert,
L. Zanello
[show abstract]
[hide abstract]
ABSTRACT: A sample of two-jet events from the UA1 experiment at the CERN pp¯
Collider has been used to study the fragmentation of high-energy quark
and gluon jets into charged hadrons. Compared with lower-energy jets
observed in e+e- and pp collisions, the
fragmentation function measured in the present experiment is softer
(i.e. peaked to smaller values of z) and the mean internal transverse
momentum is larger, mainly because of the effects of the QCD scaling
violations. Using our knowledge of the quark and gluon structure
functions in the proton, together with the QCD matrix elements, a
statistical separation of quark and gluon jets is achieved within the
present experiment. The fragmentation function for the gluon jets is
found to be softer, and the angular spread of the fragmentation products
larger, than is the case for quark jets.
Nuclear Physics B 09/1986; 276:253-271. · 4.66 Impact Factor
