-
DELPHI Collaboration,
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi, [......],
M. Winter,
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan
[show abstract]
[hide abstract]
ABSTRACT: Measurements are presented of R
b, the ratio of the
b[`(b)]{\mathrm{b}}\bar{\mathrm{b}}
cross-section to the
q[`(q)]{\mathrm{q}}\bar{\mathrm{q}}
cross-section in e+e− collisions, and the forward-backward asymmetry A
FBb at twelve energy points in the range
Ös=130\sqrt{s}=130
–207GeV. These results are found to be consistent with the Standard Model expectations. The measurements are used to set
limits on new physics scenarios involving contact interactions.
European Physical Journal C 04/2012; 60(1):1-15. · 3.63 Impact Factor
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P.P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N.I. Zimin,
A. Zintchenko,
M. Zupan,
The NA Collaboration
[show abstract]
[hide abstract]
ABSTRACT: This paper presents the final interpretation of the results from DELPHI on the searches for Higgs bosons in the minimal supersymmetric
extension of the Standard Model (MSSM). A few representative scenarios are considered, that include CP conservation and explicit
CP violation in the Higgs sector. The experimental results encompass the searches for neutral Higgs bosons at LEP1 and LEP2
in final states as expected in the MSSM, as well as LEP2 searches for charged Higgs bosons and for neutral Higgs bosons decaying
into hadrons independent of the quark flavour. The data reveal no significant excess with respect to background expectations.
The results are translated into excluded regions of the parameter space in the various scenarios. In the CP-conserving case,
these lead to limits on the masses of the lightest scalar and pseudoscalar Higgs bosons, h and A, and on tanβ. The dependence
of these limits on the top quark mass is discussed. Allowing for CP violation reduces the experimental sensitivity to Higgs
bosons. It is shown that this effect depends strongly on the values of the parameters responsible for CP violation in the
Higgs sector.
European Physical Journal C 04/2012; 54(1):1-35. · 3.63 Impact Factor
-
S. Schael,
R. Barate,
R. Brunelière,
I. De Bonis,
D. Decamp,
C. Goy,
S. Jézéquel,
J.-P. Lees,
F. Martin,
E. Merle, [......],
G.W. Wilson,
J.A. Wilson,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
S. Heinemeyer,
A. Pilaftsis,
G. Weiglein,
The LEP Working Group for Higgs Boson Searches
[show abstract]
[hide abstract]
ABSTRACT: The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by
the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined
for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no
significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper
bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number
of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large
exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses
of neutral Higgs bosons.
European Physical Journal C 04/2012; 47(3):547-587. · 3.63 Impact Factor
-
The DELPHI Collaboration,
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi, [......],
M. Winter,
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan
[show abstract]
[hide abstract]
ABSTRACT: Single top quark production via four-fermion contact interactions associated to flavour-changing neutral currents was searched
for in data taken by the DELPHI detector at LEP2. The data were accumulated at centre-of-mass energies ranging from 189 to
209 GeV, with an integrated luminosity of 598.1pb−1. No evidence for a signal was found. Limits on the energy scale Λ, were set for scalar-, vector- and tensor-like coupling scenarios.
European Physical Journal C 04/2012; 71(2):1-13. · 3.63 Impact Factor
-
The DELPHI Collaboration,
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi, [......],
M. Winter,
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan
[show abstract]
[hide abstract]
ABSTRACT: The data taken by Delphi at centre-of-mass energies between 189and 209GeV are used to place limits on the CP-conserving trilinear gauge boson couplings DgZ1\Delta g^{Z}_{1}, λ
γ
and Δκ
γ
associated to W
+
W
− and single W production at Lep2. Using data from the jj
ℓ
ν, jjjj, jjX and ℓ
X final states, where j, ℓ and X represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one
parameter is allowed to vary and the others are set to their Standard Model values of zero:
${l}\Delta g^Z_1=-0.025^{+0.033}_{-0.030},\\\noalign{\vskip6pt}\lambda_\gamma =0.002^{+0.035}_{-0.035}\qquad\mbox{and}\\\noalign{\vskip6pt}\Delta\kappa_\gamma =0.024^{+0.077}_{-0.081}.$\begin{array}{l}\Delta g^Z_1=-0.025^{+0.033}_{-0.030},\\\noalign{\vskip6pt}\lambda_\gamma =0.002^{+0.035}_{-0.035}\qquad\mbox{and}\\\noalign{\vskip6pt}\Delta\kappa_\gamma =0.024^{+0.077}_{-0.081}.\end{array}
Results are also presented when two or three parameters are allowed to vary. All observations are consistent with the predictions
of the Standard Model and supersede the previous results on these gauge coupling parameters published by Delphi.
European Physical Journal C 04/2012; 66(1):35-56. · 3.63 Impact Factor
-
The DELPHI Collaboration,
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi, [......],
M. Winter,
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan
[show abstract]
[hide abstract]
ABSTRACT: In a study of the reaction e
−
e
+→W
−
W
+ with the DELPHI detector, the probabilities of the two W particles occurring in the joint polarisation states transverse–transverse
(TT), longitudinal–transverse plus transverse–longitudinal (LT) and longitudinal–longitudinal (LL) have been determined using the final states WW®lnq[`(q)]WW{\rightarrow}l\nu q\bar{q} (l=e,μ). The two-particle joint polarisation probabilities, i.e. the spin density matrix elements ρ
TT
, ρ
LT
, ρ
LL
, are measured as functions of the W
− production angle, qW-\theta _{W^{-}}, at an average reaction energy of 198.2GeV. Averaged over all cosqW-\cos\theta_{W^{-}}, the following joint probabilities are obtained:
[`(r)]TT=(67±8)%,\bar{\rho}_{TT}=(67\pm8)\%,
[`(r)]LT=(30±8)%,\bar{\rho}_{LT}=(30\pm8)\%,
[`(r)]LL=(3±7)%.\bar{\rho}_{LL}=(3\pm7)\%.
These results are in agreement with the Standard Model predictions of 63.0%, 28.9% and 8.1%, respectively. The related polarisation
cross-sections σ
TT
, σ
LT
and σ
LL
are also presented.
European Physical Journal C 04/2012; 63(4):611-623. · 3.63 Impact Factor
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P.P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N.I. Zimin,
A. Zintchenko,
M. Zupan,
The DELPHI Collaboration
[show abstract]
[hide abstract]
ABSTRACT: In the reaction e+e-→WW→(q1q̄2)(q3q̄4) the usual hadronization models treat the colour singlets q1q̄2 and q3q̄4 coming from two W bosons independently. However, since the final state partons may coexist in space and time, cross-talk
between the two evolving hadronic systems may be possible during fragmentation through soft gluon exchange. This effect is
known as colour reconnection. In this article the results of the investigation of colour reconnection effects in fully hadronic
decays of W pairs in DELPHI at LEP are presented. Two complementary analyses were performed, studying the particle flow between
jets and W mass estimators, with negligible correlation between them, and the results were combined and compared to models.
In the framework of the SK-I model, the value for its κ parameter most compatible with the data was found to be: κSK-I=2.2+2.5
-1.3 corresponding to the probability of reconnection
P\textreco\mathcal{P}_{\text{reco}} to be in the range
0.31 < P\textreco < 0.680.31
European Physical Journal C 04/2012; 51(2):249-269. · 3.63 Impact Factor
-
The DELPHI Collaboration,
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi, [......],
M. Winter,
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan
[show abstract]
[hide abstract]
ABSTRACT: The nature of b-quark jet hadronisation has been investigated using data taken at the Zpeak by the DELPHI detector at LEP.
Two complementary methods are used to reconstruct the energy of weakly decaying b-hadrons, EBweakE_{\mathrm{B}}^{\mathrm{weak}}. The average value of xweakB = EBweak/Ebeamx^{\mathrm{weak}}_{\mathrm{B}} = E_{\mathrm{B}}^{\mathrm{weak}}/E_{\mathrm{beam}} is measured to be 0.699±0.011. The resulting xweakBx^{\mathrm{weak}}_{\mathrm{B}} distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to
Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of
b-hadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model
ansatz and corresponding values of its parameters have been determined within PYTHIA6.156 from DELPHI data:
a = 1.84+0.23-0.21and b=0.642+0.073-0.063GeV-2,a= 1.84^{+0.23}_{-0.21}\quad\mbox{and}\quad b=0.642^{+0.073}_{-0.063}~\mathrm{GeV}^{-2},
with a correlation factor ρ=92.2%.
Combining the data on the b-quark fragmentation distributions with those obtained at the Zpeak by ALEPH, OPAL and SLD, the
average value of xweakBx^{\mathrm{weak}}_{\mathrm{B}} is found to be 0.7092±0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution,
a better determination of the Lund parameters is also obtained:
a = 1.48+0.11-0.10and b=0.509+0.024-0.023GeV-2,a= 1.48^{+0.11}_{-0.10}\quad\mbox{and}\quad b=0.509^{+0.024}_{-0.023}~\mathrm{GeV}^{-2},
with a correlation factor ρ=92.6%.
European Physical Journal C 04/2012; 71(2):1-29. · 3.63 Impact Factor
-
The DELPHI Collaboration,
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi, [......],
M. Winter,
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan
[show abstract]
[hide abstract]
ABSTRACT: An analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based
on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics
(momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor
of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behavior
to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences.
However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference
is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed
linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the
jet neutral multiplicity suggest that the rate is proportional to the number of quark pairs produced in the fragmentation
process, with the neutral pairs being more effectively radiating than the charged ones.
European Physical Journal C 04/2012; 67(3):343-366. · 3.63 Impact Factor
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P.P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N.I. Zimin,
A. Zintchenko,
M. Zupan,
The DELPHI Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A measurement of the W boson mass and width has been performed by the DELPHI collaboration using the data collected during
the full LEP2 programme (1996–2000). The data sample has an integrated luminosity of 660pb-1 and was collected over a range of centre-of-mass energies from 161 to 209GeV.
Results are obtained by applying the method of direct reconstruction of the mass of the W from its decay products in both
the W+W-→ℓν̄ℓqq̄’ and W+W-→qq̄’q̄q’ channels. The W mass result for the combined data set is
MW = 80.336 ±0.055 (\textStat.) ±0.028 (\textSyst.) ±0.025 (\textFSI) ±0.009 (\textLEP) \textGeV/c2, M_W = 80.336 \pm0.055 ({\text{Stat.}}) \pm0.028 ({\text{Syst.}}) \pm0.025 ({\text{FSI}}) \pm0.009 ({\text{LEP}}) \text{GeV}/c^2, where FSI represents the uncertainty due to final state interaction effects in the qq̄’q̄q’ channel, and LEP represents that
arising from the knowledge of the collision energy of the accelerator. The combined value for the W width is
GW = 2.404 ±0.140 (\textStat.) ±0.077 (\textSyst.) ±0.065 (\textFSI) \textGeV/c2. {\Gamma_{W}} = 2.404 \pm0.140 ({\text{Stat.}}) \pm0.077 ({\text{Syst.}}) \pm0.065 ({\text{FSI}}) \text{GeV}/c^2. These results supersede all values previously published by the DELPHI collaboration.
European Physical Journal C 04/2012; 55(1):1-38. · 3.63 Impact Factor
-
W D Apel,
J C Arteaga,
F Badea,
K Bekk,
M Bertaina,
J Blümer,
H Bozdog,
I M Brancus,
M Brüggemann,
P Buchholz, [......],
M Stümpert,
G Toma,
G C Trinchero,
H Ulrich,
J van Buren,
W Walkowiak,
A Weindl,
J Wochele,
M Wommer,
J Zabierowski
[show abstract]
[hide abstract]
ABSTRACT: Predictions of the hadronic interaction model EPOS 1.61 as implemented in the air shower simulation program CORSIKA are compared to observations with the KASCADE experiment. The investigations reveal that the predictions of EPOS are not compatible with KASCADE measurements. The discrepancies seen are most likely due to use of a set of inelastic hadronic cross sections that are too high.
Journal of Physics G Nuclear and Particle Physics 02/2009; 36(3):035201. · 4.18 Impact Factor
-
T. Antoni, W. D. Apel,
F. Badea,
K. Bekk,
A. Bercuci,
H. Blümer,
H. Bozdog,
I. M. Brancus,
C. Büttner,
A. Chilingarian, [......],
G. Schatz,
H. Schieler,
J. Scholz,
T. Thouw,
H. Ulrich,
J. van Buren,
A. Vardanyan,
A. Weindl,
J. Wochele,
and J. Zabierowski
[show abstract]
[hide abstract]
ABSTRACT: The flux of cosmic-ray-induced single hadrons near sea level has been measured with the large hadron calorimeter of the KASCADE experiment. The measurement corroborates former results obtained with detectors of smaller size if the enlarged veto of the 304 m2 calorimeter surface is accounted for. The program CORSIKA/QGSJET is used to compute the cosmic-ray flux above the atmosphere. Between E0 = 300 GeV and 1 PeV the primary proton spectrum can be described with a power law parameterized as dJ/dE0 = (0.15 ± 0.03)E m-2 s-1 sr-1 TeV-1. At the lower energy end the proton flux compares well with the results from recent direct measurements.
The Astrophysical Journal 12/2008; 612(2):914. · 6.02 Impact Factor
-
T. Antoni, W. D. Apel,
A. F. Badea,
K. Bekk,
A. Bercuci,
H. Blümer,
H. Bozdog,
I. M. Brancus,
C. Büttner,
K. Daumiller, [......],
H. Schieler,
J. Scholz,
T. Thouw,
H. Ulrich,
J. van Buren,
A. Vardanyan,
A. Weindl,
J. Wochele,
J. Zabierowski,
and (The KASCADE Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A survey of the northern hemisphere for astrophysical point sources with continuous emission of high-energy cosmic rays is presented. Around 4.7 × 107 extensive air showers with primary energies above ≈300 TeV measured by the KASCADE detector field are selected for this analysis. Besides the sky survey, a search for signal excess in the regions of the Galactic plane and of selected point-source candidates has been performed. There is no evidence for any significant excess. This is valid for an analysis of all recorded showers, as well as for a data set enhanced by γ-ray-induced showers. An upper flux limit of around 3 × 10-10 m-2 s-1 for a steady point source that transits the zenith is obtained. Additionally, the distribution of the arrival directions of extensive air showers with energies above 80 PeV was studied by an autocorrelation analysis.
The Astrophysical Journal 12/2008; 608(2):865. · 6.02 Impact Factor
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan,
DELPHI Collaboration
[show abstract]
[hide abstract]
ABSTRACT: The production of two high-p
T
jets in the interactions of quasi-real photons in e
+
e
− collisions at
Ö{see}\sqrt{s_{ee}}
from 189GeV to 209GeV is studied with data corresponding to an integrated e
+
e
− luminosity of 550pb−1. The jets reconstructed by the k
⊥
-cluster algorithm are defined within the pseudo-rapidity range −1<η<1 and with jet transverse momentum, p
T
, above 3GeV/c. The differential di-jet cross-section is measured as a function of the mean transverse momentum
[`(pT)]\overline{p_{T}}
of the jets and is compared to perturbative QCD calculations.
European Physical Journal C 11/2008; 58(4):531-541. · 3.63 Impact Factor
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P. P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N. I. Zimin,
A. Zintchenko,
M. Zupan,
DELPHI Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Muon bremsstrahlung photons converted in front of the DELPHI main tracker (TPC) in dimuon events at LEP1 were studied in two
photon kinematic ranges: 0.2<E
γ
≤1GeV and transverse momentum with respect to the parent muon p
T
<40MeV/c, and 1<E
γ
≤10GeV and p
T
<80MeV/c. A good agreement of the observed photon rate with predictions from QED for the muon inner bremsstrahlung was found, contrary
to the anomalous soft photon excess that has been observed recently in hadronic Z
0 decays. The obtained ratios of the observed signal to the predicted level of the muon bremsstrahlung are 1.06±0.12±0.07 in
the photon energy range 0.2<E
γ
≤1GeV and 1.04±0.09±0.12 in the photon energy range 1<E
γ
≤10GeV. The bremsstrahlung dead cone is observed for the first time in the direct photon production at LEP.
European Physical Journal C 09/2008; 57(3):499-514. · 3.63 Impact Factor
-
J Blümer, W D Apel,
J C Arteaga,
T Asch,
J Auffenberg,
F Badea,
L Bähren,
K Bekk,
M Bertaina,
P L Biermann, [......],
M Stümpert,
G Toma,
G C Trinchero,
H Ulrich,
J van Buren,
W Walkowiak,
A Weindl,
J Wochele,
J Zabierowski,
J A Zensus
[show abstract]
[hide abstract]
ABSTRACT: LOPES is an array of 30 radio antenna co-located with the KASCADE-Grande extensive air shower detector in Karlsruhe, Germany. It is designed as a digital radio interferometer for the detection of radio emission from extensive air showers. LOPES features high bandwidth and fast data processing. A unique asset is the concurrent operation with KASCADE-Grande. We report about the progress in understanding the radio signals measured by LOPES. In addition, the status and further perspectives of LOPES and the large scale application of this novel detection technique are sketched.
Journal of Physics Conference Series 07/2008; 120(6):062012.
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P.P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N.I. Zimin,
A. Zintchenko,
M. Zupan,
The DELPHI Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A determination of the single W spin density matrix (SDM) elements in the reaction e+e-→W+W-→lνqq̄(l=e/μ) is reported at centre-of-mass energies between 189 and 209 GeV. The data sample used corresponds to an integrated
luminosity of 520 pb-1 taken by DELPHI between 1998 and 2000.
The single W SDM elements, ρττ’
W± (τ,τ’=± 1 or 0), are determined as a function of the W- production angle with respect to the e- beam direction and are obtained from measurements of the W decay products by the application of suitable projection operators,
Λττ’, which assume the V-A coupling of the W-boson to fermions.
The measured SDM elements are used to obtain the fraction of longitudinally polarised Ws, with the result:
\fracs\textLs\texttot = 24.9 ±4.5(\textstat) ±2.2(\textsyst)%\frac{\sigma_{\text{L}}}{\sigma_{{\text{tot}}}} = 24.9 \pm4.5({\text{stat}}) \pm2.2({\text{syst}})\% at a mean energy of 198 GeV. The SDM elements are also used to determine the triple gauge couplings Δg1
Z,Δκγ,λγ and g4
Z, [(k)\tilde]Z\tilde{\kappa}_{Z} and [(l)\tilde]Z\tilde{\lambda}_{Z}. For the CP-violating couplings the results of single parameter fits are: g4Z = -0.39+0.19-0.20g_4^{{Z}} = -0.39^{+0.19}_{-0.20}
[(k)\tilde]Z = -0.09+0.08-0.05\tilde{\kappa}_{{Z}} = -0.09^{+0.08}_{-0.05}
[(l)\tilde]Z = -0.08±0.07 .\tilde{\lambda}_{{Z}} = -0.08\pm0.07 . The errors are a combination of statistical and systematic errors. All results are consistent with the Standard Model.
European Physical Journal C 03/2008; 54(3):345-364. · 3.63 Impact Factor
-
J. Abdallah,
P. Abreu,
W. Adam,
P. Adzic,
T. Albrecht,
R. Alemany-Fernandez,
T. Allmendinger,
P.P. Allport,
U. Amaldi,
N. Amapane, [......],
M. Witek,
O. Yushchenko,
A. Zalewska,
P. Zalewski,
D. Zavrtanik,
V. Zhuravlov,
N.I. Zimin,
A. Zintchenko,
M. Zupan,
The DELPHI Collaboration
[show abstract]
[hide abstract]
ABSTRACT: The effect of the heavy b-quark mass on the two, three and four-jet rates is studied using LEP data collected by the DELPHI
experiment at the Z peak in 1994 and 1995. The rates of b-quark jets and light quark jets (ℓ=uds) in events with n=2, 3, and
4 jets, together with the ratio of two and four-jet rates of b-quarks with respect to light-quarks, Rn
bℓ, have been measured with a double-tag technique using the CAMBRIDGE jet-clustering algorithm. A comparison between experimental
results and theory (matrix element or Monte Carlo event generators such as PYTHIA, HERWIG and ARIADNE) is done after the hadronisation
phase.
Using the four-jet observable R4
bℓ, a measurement of the b-quark mass using massive leading-order calculations gives:
mb(MZ) = 3.76 ±0.32 (\textstat) ±0.17 (\textsyst) ±0.22 (\texthad) ±0.90 (\texttheo)\textGeV/c2.m_b(M_Z) = 3.76 \pm0.32 ({\text{stat}}) \pm0.17 ({\text{syst}}) \pm0.22 ({\text{had}}) \pm0.90 ({\text{theo}})\,\text{GeV}/c^2\,. This result is compatible with previous three-jet determinations at the MZ energy scale and with low energy mass measurements evolved to the MZ scale using QCD renormalisation group equations.
European Physical Journal C 01/2008; 55(4):525-538. · 3.63 Impact Factor
-
The KASCADE Collaboration, W D Apel,
A F Badea,
K Bekk,
J Blümer,
H Bozdog,
I M Brancus,
K Daumiller,
P Doll,
R Engel, [......],
A Risse,
M Risse,
M Roth,
G Schatz,
H Schieler,
H Ulrich,
J van Buren,
A Weindl,
J Wochele,
J Zabierowski
[show abstract]
[hide abstract]
ABSTRACT: The interpretation of extensive air shower measurements often requires a comparison with shower simulations in the atmosphere. These calculations rely on hadronic interaction models which have to extrapolate into kinematical and energy regions not explored by present-day collider experiments. The KASCADE experiment with its large hadron calorimeter and the detector array for the electromagnetic and muonic components provides experimental data to check such interaction models. For the simulations the program CORSIKA is used, which has several hadronic event generators embedded. For high-energy interactions the models DPMJET, , QGSJET and SIBYLL have been used. Low-energy interactions have been treated by GHEISHA and FLUKA. Different hadronic observables are investigated as well as their correlations with the electromagnetic and muonic shower components up to primary energies of about 40 PeV. Although the predictions of the more recent models are to a large extent compatible with the measured data within the range given by proton and iron primary particles, there are still significant differences between the individual models.
Journal of Physics G Nuclear and Particle Physics 11/2007; 34(12):2581. · 4.18 Impact Factor
-
A Haungs, W D Apel,
T Asch,
F Badea,
L Bähren,
K Bekk,
A Bercuci,
M Bertaina,
P L Biermann,
J Blümer, [......],
G Toma,
G C Trinchero,
H Ulrich,
J van Buren,
W Walkowiak,
A Weindl,
J Wochele,
J Zabierowski,
J A Zensus,
D Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: LOPES is set up at the location of the KASCADE-Grande extensive air shower experiment in Karlsruhe, Germany and aims to measure and investigate radio pulses from Extensive Air Showers. Data taken during half a year of operation of 10 LOPES antennas (LOPES-10), triggered by showers observed with KASCADE-Grande have been analyzed. We report about results of correlations found of the measured radio signals by LOPES-10 with shower parameters.
Journal of Physics Conference Series 10/2007; 81(1):012005.
