-
T. R. Edgecock,
O. Caretta,
T. Davenne,
C. Densham,
M. Fitton,
D. Kelliher,
P. Loveridge,
S. Machida,
C. Prior,
C. Rogers, [......],
A. Bogacz,
J. S. Berg,
D. Stratakis,
H. Witte,
P. Snopok,
N. Bliss,
M. Cordwell,
A. Moss,
S. Pattalwar,
M. Apollonio
[show abstract]
[hide abstract]
ABSTRACT: The EUROnu project has studied three possible options for future, high
intensity neutrino oscillation facilities in Europe. The first is a Super Beam,
in which the neutrinos come from the decay of pions created by bombarding
targets with a 4 MW proton beam from the CERN High Power Superconducting Proton
Linac. The far detector for this facility is the 500 kt MEMPHYS water
Cherenkov, located in the Fr\'ejus tunnel. The second facility is the Neutrino
Factory, in which the neutrinos come from the decay of {\mu}+ and {\mu}- beams
in a storage ring. The far detector in this case is a 100 kt Magnetised Iron
Neutrino Detector at a baseline of 2000 km. The third option is a Beta Beam, in
which the neutrinos come from the decay of beta emitting isotopes, in
particular 6He and 18Ne, also stored in a ring. The far detector is also the
MEMPHYS detector in the Fr\'ejus tunnel. EUROnu has undertaken conceptual
designs of these facilities and studied the performance of the detectors. Based
on this, it has determined the physics reach of each facility, in particular
for the measurement of CP violation in the lepton sector, and estimated the
cost of construction. These have demonstrated that the best facility to build
is the Neutrino Factory. However, if a powerful proton driver is constructed
for another purpose or if the MEMPHYS detector is built for astroparticle
physics, the Super Beam also becomes very attractive.
05/2013;
-
K. Abe,
N. Abgrall,
H. Aihara,
T. Akiri,
J. B. Albert,
C. Andreopoulos,
S. Aoki,
A. Ariga,
T. Ariga,
S. Assylbekov, [......],
N. Yershov,
M. Yokoyama,
Ì T. Yuan,
A. Zalewska,
L. Zambelli,
K. Zaremba,
M. Ziembicki,
E. D. Zimmerman,
M. Zito,
and J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: T2K has performed the first measurement of \nu{\mu} inclusive charged current
interactions on carbon at neutrino energies of ~1 GeV where the measurement is
reported as a flux-averaged double differential cross section in muon momentum
and angle. The flux is predicted by the beam Monte Carlo and external data,
including the results from the NA61/SHINE experiment. The data used for this
measurement were taken in 2010 and 2011, with a total of 10.8 x 10^{19}
protons-on-target. The analysis is performed on 4485 inclusive charged current
interaction candidates selected in the most upstream fine-grained scintillator
detector of the near detector.
The flux-averaged total cross section is <\sigma_CC>_\phi =(6.91 +/- 0.13
(stat) +/- 0.84 (syst)) x10^{-39} cm^2/nucleon for a mean neutrino energy of
0.85 GeV.
02/2013;
-
N. Agafonov,
A. Aleksandrov,
O. Altinok,
M. Ambrosio,
A. Anokhina,
S Aoki,
A. Ariga,
T Ariga,
D. Autiero,
A. Badertscher, [......],
G. Wilqueta,
B. Wonsak,
V. Yakushev,
C.S. Yoona,
J Yoshida,
T Yoshioka,
Y. Zaitsev,
S. Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) has been designed to perform the first detection of neutrino oscillations in direct appearance mode through the study of the $\nu_\mu\rightarrow\nu_\tau$ channel. The hybrid apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2008 and 2009. After a brief description of the beam, the experimental setup and the procedures used for the analysis of the neutrino events, we describe the topology and kinematics of a first candidate $\nu_\tau$ charged-current event satisfying the kinematical selection criteria. The background calculations and their cross-check are explained in detail and the significance of the event is assessed.
Physics Letters B 12/2012; · 3.95 Impact Factor
-
N. Agafonova,
A. Aleksandrov,
O. Altinok,
A. Anokhina,
S Aoki,
A. Ariga,
T Ariga,
D. Autiero,
A. Badertscher,
A Bagulya, [......],
G Wilquet,
B. Wonsak,
V. Yakushev,
C S Yoon,
T Yoshioka,
J Yoshida,
Y. Zaitsev,
S. Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA experiment is based on a hybrid technology combining electronic detectors and nuclear emulsions. OPERA collected muon-neutrino interactions during the 2008 and 2009 physics runs of the CNGS neutrino beam, produced at CERN with an energy range of about 5-35 GeV. A total of $5.3 \times 10^{19}$ protons on target equivalent luminosity has been analysed with the OPERA electronic detectors: scintillator strips target trackers and magnetic muon spectrometers equipped with resistive plate gas chambers and drift tubes, allowing a detailed reconstruction of muon-neutrino interactions. Charged Current (CC) and Neutral Current (NC) interactions are identified, using the measurements in the electronic detectors, and the NC/CC ratio is computed. The momentum distribution and the charge of the muon tracks produced in CC interactions are analysed. Calorimetric measurements of the visible energy are performed for both the CC and NC samples. For CC events the Bjorken-$y$ distribution and the hadronic shower profile are computed. The results are compared to a detailed Monte Carlo simulation of the electronic detectors' response.
New Journal of Physics 12/2012; 13:053051. · 4.18 Impact Factor
-
The OPERA Collaboration,
T. Adam,
N. Agafonova,
A. Aleksandrov,
A. Anokhina,
S. Aoki,
A. Ariga,
T. Ariga,
D. Autiero,
A. Badertscher, [......],
J. L. Vuilleumier,
G. Wilquet,
B. Wonsak,
J. Wurtz,
C. S. Yoon,
J. Yoshida,
Y. Zaitsev,
S. Zemskova,
A. Zghiche,
R. Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: In spring 2012 CERN provided two weeks of a short bunch proton beam dedicated
to the neutrino velocity measurement over a distance of 730 km. The OPERA
neutrino experiment at the underground Gran Sasso Laboratory used an upgraded
setup compared to the 2011 measurements, improving the measurement time
accuracy. An independent timing system based on the Resistive Plate Chambers
was exploited providing a time accuracy of $\sim$1 ns. Neutrino and
anti-neutrino contributions were separated using the information provided by
the OPERA magnetic spectrometers. The new analysis profited from the precision
geodesy measurements of the neutrino baseline and of the CNGS/LNGS clock
synchronization. The neutrino arrival time with respect to the one computed
assuming the speed of light in vacuum is found to be $\delta t_\nu \equiv TOF_c
- TOF_\nu= (0.6 \pm 0.4\ (stat.) \pm 3.0\ (syst.))$ ns and $\delta
t_{\bar{\nu}} \equiv TOF_c - TOF_{\bar{\nu}} = (1.7 \pm 1.4\ (stat.) \pm 3.1\
(syst.))$ ns for $\nu_{\mu}$ and $\bar{\nu}_{\mu}$, respectively. This
corresponds to a limit on the muon neutrino velocity with respect to the speed
of light of $-1.8 \times 10^{-6} < (v_{\nu}-c)/c < 2.3 \times 10^{-6}$ at 90%
C.L. This new measurement confirms with higher accuracy the revised OPERA
result.
12/2012;
-
E. Baussan,
J. Bielski,
C. Bobeth,
E. Bouquerel,
O. Caretta,
P. Cupial,
T. Davenne,
C. Densham,
M. Dracos,
M. Fitton, [......],
M. Rooney,
B. Skoczen,
B. Szybinski,
A. Ustrzycka,
N. Vassilopoulos,
D. Wilcox,
A. Wroblewski,
J. Wurtz,
V. Zeter,
M. Zito
[show abstract]
[hide abstract]
ABSTRACT: The EUROnu Super Beam work package has studied a neutrino beam based on SPL
at CERN and aimed at MEMPHYS, a large water Cherenkov detector, proposed for
the Laboratoire Souterrain de Modane (Fr\'ejus tunnel, France), with a baseline
of 130 km. The aim of this proposed experiment is to study the CP violation in
the neutrino sector.
In the study reported here, we have developed the conceptual design of the
neutrino beam, especially the target and the magnetic focusing device. Indeed,
this beam present several unprecedented challenges, like the high primary
proton beam power (4 MW), the high repetition rate (50 Hz) and the low energy
of the protons (4.5 GeV). The design is completed by a study of all the main
component of the system, starting from the transport system to guide the beam
to the target up to the beam dump.
12/2012;
-
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
C. Alexa,
V. Andreev,
S. Antonelli,
P. Antonioli,
A. Antonov, [......],
W. Zeuner,
Z. Zhang,
B. O. Zhautykov,
N. Zhmak,
A. Zichichi,
R. Žlebčík,
H. Zohrabyan,
Z. Zolkapli,
F. Zomer,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Measurements of open charm production cross sections in deep-inelastic ep
scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced
cross sections sigma_red^{c\bar{c}} for charm production are obtained in the
kinematic range of photon virtuality 2.5<Q2<2000 GeV2 and Bjorken scaling
variable 0.00003<x<0.05. The combination method accounts for the correlations
of the systematic uncertainties among the different data sets. The combined
charm data together with the combined inclusive deep-inelastic scattering cross
sections from HERA are used as input for a detailed NLO QCD analysis to study
the influence of different heavy flavour schemes on the parton distribution
functions. The optimal values of the charm mass as a parameter in these
different schemes are obtained. The implications on the NLO predictions for
W^{\pm} and Z production cross sections at the LHC are investigated. Using the
fixed flavour number scheme, the running mass of the charm quark is determined.
11/2012;
-
Collaboration,
K. Abe,
N. Abgrall,
H. Aihara,
T. Akiri,
J. B. Albert,
C. Andreopoulos,
S. Aoki,
A. Ariga,
T. Ariga, [......],
N. Yershov,
M. Yokoyama,
T. Yuan,
A. Zalewska,
L. Zambelli,
K. Zaremba,
M. Ziembicki,
E. D. Zimmerman,
M. Zito,
J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: The Tokai-to-Kamioka (T2K) experiment studies neutrino oscillations using an
off-axis muon neutrino beam with a peak energy of about 0.6 GeV that originates
at the J-PARC accelerator facility. Interactions of the neutrinos are observed
at near detectors placed at 280 m from the production target and at the far
detector -- Super-Kamiokande (SK) -- located 295 km away. The flux prediction
is an essential part of the successful prediction of neutrino interaction rates
at the T2K detectors and is an important input to T2K neutrino oscillation and
cross section measurements. A FLUKA and GEANT3 based simulation models the
physical processes involved in the neutrino production, from the interaction of
primary beam protons in the T2K target, to the decay of hadrons and muons that
produce neutrinos. The simulation uses proton beam monitor measurements as
inputs. The modeling of hadronic interactions is re-weighted using thin target
hadron production data, including recent charged pion and kaon measurements
from the NA61/SHINE experiment. For the first T2K analyses the uncertainties on
the flux prediction are evaluated to be below 15% near the flux peak. The
uncertainty on the ratio of the flux predictions at the far and near detectors
is less than 2% near the flux peak.
11/2012;
-
ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
O. Zabiegalov,
A. F. Żarnecki,
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
A. Zichichi,
Z. Zolkapli,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: The production of Z0 bosons in the reaction ep -> eZ0p*, where p* stands for
a proton or a low-mass nucleon resonance, has been studied in ep collisions at
HERA using the ZEUS detector. The analysis is based on a data sample collected
between 1996 and 2007, amounting to 496 pb-1 of integrated luminosity. The Z0
was measured in the hadronic decay mode. The elasticity of the events was
ensured by a cut on eta_max < 3.0, where eta_max is the maximum pseudorapidity
of energy deposits in the calorimeter defined with respect to the proton beam
direction. A signal was observed at the Z0 mass. The cross section of the
reaction ep -> eZ0p* was measured to be sigma(ep -> eZ0p*) = 0.13 +/- 0.06
(stat.) +/- 0.01 (syst.) pb, in agreement with the Standard Model prediction of
0.16 pb. This is the first measurement of Z0 production in ep collisions.
10/2012;
-
ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
M. Zolko,
D. S. Zotkin
-
[show abstract]
[hide abstract]
ABSTRACT: The large value of theta(13) recently measured by rector and accelerator
experiments opens unprecedented opportunities for precision oscillation
physics. In this paper, we reconsider the physics reach of medium baseline
superbeams. For theta(13) ~ 9 degree we show that facilities at medium
baselines -- i.e. L ~ O(1000 km) -- remain optimal for the study of CP
violation in the leptonic sector, although their ultimate precision strongly
depends on experimental systematics. This is demonstrated in particular for
facilities of practical interest in Europe: a CERN to Gran Sasso and CERN to
Phyasalmi nu_mu beam based on the present SPS and on new high power 50 GeV
proton driver. Due to the large value of theta(13), spectral information can be
employed at medium baselines to resolve the sign ambiguity and determine the
neutrino mass hierarchy. However, longer baselines, where matter effects
dominate the nu_mu->nu_e transition, can achieve much stronger sensitivity to
sign(Delta m^2) even at moderate exposures.
09/2012;
-
M. Antonello,
D. Bagliani,
B. Baibussinov,
H. Bilokon,
F. Boffelli,
M. Bonesini,
E. Calligarich,
N. Canci,
S. Centro,
A. Cesana, [......],
S. Simone,
M. Sioli,
G. Sirri,
M. Spurio,
L. Stanco,
A. Surdo,
M. Tenti,
V. Togo,
M. Ventura,
M. Zago
[show abstract]
[hide abstract]
ABSTRACT: A new experiment with an intense ~2 GeV neutrino beam at CERN SPS is proposed
in order to definitely clarify the possible existence of additional neutrino
states, as pointed out by neutrino calibration source experiments, reactor and
accelerator experiments and measure the corresponding oscillation parameters.
The experiment is based on two identical LAr-TPCs complemented by magnetized
spectrometers detecting electron and muon neutrino events at Far and Near
positions, 1600 m and 300 m from the proton target, respectively. The ICARUS
T600 detector, the largest LAr-TPC ever built with a size of about 600 ton of
imaging mass, now running in the LNGS underground laboratory, will be moved at
the CERN Far position. An additional 1/4 of the T600 detector (T150) will be
constructed and located in the Near position. Two large area spectrometers will
be placed downstream of the two LAr-TPC detectors to perform charge
identification and muon momentum measurements from sub-GeV to several GeV
energy range, greatly complementing the physics capabilities. This experiment
will offer remarkable discovery potentialities, collecting a very large number
of unbiased events both in the neutrino and antineutrino channels, largely
adequate to definitely settle the origin of the observed neutrino-related
anomalies.
08/2012;
-
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo,
O. Arslan, [......],
A. F. Żarnecki,
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003–2007 using an integrated luminosity of 366 pb-1. Final states with an electron and jets or with missing transverse momentum and jets were analyzed, searching for resonances or other deviations from the standard model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of 498 pb-1. Limits on the Yukawa coupling, λ, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmüller-Rückl-Wyler model. Leptoquarks with a coupling λ=0.3 are excluded for masses up to 699 GeV.
Phys. Rev. D. 07/2012; 86(1).
-
N. Yu. Agafonova,
P. Antonioli,
V. V. Ashikhmin,
G. Bari,
E. Bressan,
L. Evans,
M. Garbini,
P. Giusti,
A. S. Malguin,
R. Persiani, [......],
M. Spinetti,
L. Stanco,
M. Stipcevic,
M. Tenti,
F. Terranova,
V. Tioukov,
B. Wonsak,
V. Yakushev,
Y. Zaitsev,
S. Zemskova
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this work is to report the measurement of a time-shift in the
OPERA set-up in a totally independent way from Time Of Flight (TOF)
measurements of CNGS neutrino events. The LVD and OPERA experiments are both
installed in the same laboratory: LNGS. The relative position of the two
detectors, separated by an average distance of ~ 160 m, allows the use of very
high energy horizontal muons to cross-calibrate the timing systems of the two
detectors, using a TOF technique which is totally independent from TOF of CNGS
neutrino events. Indeed, the OPERA-LVD direction lies along the so-called
"Teramo anomaly", a region in the Gran Sasso massif where LVD has established,
many years ago, the existence of an anomaly in the mountain structure, which
exhibits a low m. w. e. thickness for horizontal directions. The "abundant"
high-energy horizontal muons (nearly 100 per year) going through LVD and OPERA
exist because of this anomaly in the mountain orography. The total live time of
the data in coincidence correspond to 1200 days from mid 2007 until March 2012.
The time coincidence study of LVD and OPERA detectors is based on 306 cosmic
horizontal muon events and shows the existence of a negative time shift in the
OPERA set-up of the order of deltaT(AB) = - (73 \pm 9) ns when two calendar
periods, A and B, are compared. This result shows a systematic effect in the
OPERA timing system from August 2008 until December 2011. The size of the
effect is comparable with the neutrino velocity excess recently measured by
OPERA. It is probably interesting not to forget that with the MRPC technology
developed by the ALICE Bologna group the TOF world record accuracy of 20 ps was
reached. That technology can be implemented at LNGS for a high precision
determination of TOF with the CNGS neutrino beams of an order of magnitude
smaller than the value of the OPERA systematic effect.
06/2012;
-
ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
A. F. Zarnecki,
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Inclusive-jet cross sections have been measured in the reaction ep->e+jet+X
for photon virtuality Q2 < 1 GeV2 and gamma-p centre-of-mass energies in the
region 142 < W(gamma-p) < 293 GeV with the ZEUS detector at HERA using an
integrated luminosity of 300 pb-1. Jets were identified using the kT, anti-kT
or SIScone jet algorithms in the laboratory frame. Single-differential cross
sections are presented as functions of the jet transverse energy, ETjet, and
pseudorapidity, etajet, for jets with ETjet > 17 GeV and -1 < etajet < 2.5. In
addition, measurements of double-differential inclusive-jet cross sections are
presented as functions of ETjet in different regions of etajet.
Next-to-leading-order QCD calculations give a good description of the
measurements, except for jets with low ETjet and high etajet. The influence of
non-perturbative effects not related to hadronisation was studied. Measurements
of the ratios of cross sections using different jet algorithms are also
presented; the measured ratios are well described by calculations including up
to O(alphas2) terms. Values of alphas(Mz) were extracted from the measurements
and the energy-scale dependence of the coupling was determined. The value of
alphas(Mz) extracted from the measurements based on the kT jet algorithm is
alphas(Mz) = 0.1206 +0.0023 -0.0022 (exp.) +0.0042 -0.0035 (th.); the results
from the anti-kT and SIScone algorithms are compatible with this value and have
a similar precision.
05/2012;
-
S. Chekanov,
M. Derrick,
S. Magill,
S. Miglioranzi,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M.C.K. Mattingly,
N. Pavel, [......],
S. Bhadra,
C.D. Catterall,
Y. Cui,
G. Hartner,
S. Menary,
U. Noor,
M. Soares,
J. Standage,
J. Whyte,
The ZEUS Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A search for stop production in R-parity-violating supersymmetry has been performed in e+p interactions with the ZEUS detector at HERA, using an integrated luminosity of 65pb-1. At HERA, the R-parity-violating coupling λ’ allows resonant squark production, e+d®[(q)\tilde]e^+d\to\tilde{q}. Since the lowest-mass squark state in most supersymmetry models is the light stop, [(t)\tilde]\tilde{t}, this search concentrated on production of [(t)\tilde]\tilde{t}, followed either by a direct R-parity-violating decay, or by the gauge decay to b[(c)\tilde]+1b\tilde{\chi}^+_{1}. No evidence for stop production was found and limits were set on λ’131 as a function of the stop mass in the framework of the minimal supersymmetric standard model. The results have also been
interpreted in terms of constraints on the parameters of the minimal supergravity model.
European Physical Journal C 04/2012; 50(2):269-281. · 3.63 Impact Factor
-
The ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: Measurements of the cross sections for charged current deep inelastic scattering in e
+
p collisions with a longitudinally polarised positron beam are presented. The measurements are based on a data sample with
an integrated luminosity of 132pb−1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318GeV. The total cross section is presented at positive
and negative values of the longitudinal polarisation of the positron beams. The single-differential cross-sections dσ/dQ
2, dσ/dx and dσ/dy are presented for Q
2>200GeV2. The reduced cross-section [(s)\tilde]\tilde{\sigma} is presented in the kinematic range 200<Q
2<60 000GeV2 and 0.006<x<0.562. The measurements agree well with the predictions of the Standard Model. The results are used to determine a lower
limit on the mass of a hypothetical right-handed W boson.
European Physical Journal C 04/2012; 70(4):945-963. · 3.63 Impact Factor
-
ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
E. Brownson,
D. D. Reeder,
A. A. Savin,
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
G. Hartner,
U. Noor,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: The proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb−1. The cross section is presented as a function of the photon-proton centre-of-mass energy and of the squared four-momentum
transfer at the proton vertex. The results are compared to perturbative QCD calculations.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(5):1-36. · 5.83 Impact Factor
-
The ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been
measured with the ZEUS detector at HERA using an integrated luminosity of 114pb−1. The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of
the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality,
Q
2>2GeV2, and inelasticity, 0.05<y<0.7, with the requirement of a muon and a jet. Total and differential cross sections are presented and compared to QCD predictions.
The beauty contribution to the structure function F
2 was extracted and is compared to theoretical predictions.
European Physical Journal C 04/2012; 69(3):347-360. · 3.63 Impact Factor
-
ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
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ABSTRACT: Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity
of 120 pb−1. The hadronic decay channels D
+ → K
S
0
π
+, Λ
c
+ → pK
S
0 and Λ
c
+ → Λπ
+, and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the
combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range
is 0 < p
T
(D
+, Λ
c
+) < 10 GeV, |η(D
+, Λ
c
+)| < 1.6, 1.5 < Q
2 < 1000 GeV2 and 0.02 < y < 0.7. Inclusive and differential cross sections for the production of D
+ mesons are compared to next-to-leading-order QCD predictions. The fraction of c quarks hadronising into Λ
c
+ baryons is extracted.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(11):1-27. · 5.83 Impact Factor
