Inclusive-jet cross sections have been measured in the reaction ep→e+jet+X for photon virtuality Q2<1 GeV2 and γp centre-of-mass energies in the region 142<Wγp<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, ηjet, for jets with ETjet>17 GeV and −1<ηjet<2.5. In addition, measurements of double-differential inclusive-jet cross sections are presented as functions of ETjet in different regions of ηjet. Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low ETjet and high ηjet. 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(αs2) terms. Values of αs(MZ) were extracted from the measurements and the energy-scale dependence of the coupling was determined. The value of αs(MZ) extracted from the measurements based on the kT jet algorithm is αs(MZ)=0.1206−0.0022+0.0023(exp.)−0.0035+0.0042(th.); the results from the anti-kT and SIScone algorithms are compatible with this value and have a similar precision.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The exclusive electroproduction of
J/
ψ mesons,
ep→
epJ/
ψ, has been studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the ranges
0.15<Q
2<0.8
GeV
2
and
2<Q
2<100
GeV
...2
using integrated luminosities of 69 and
83
pb
−1
, respectively. The photon–proton centre-of-mass energy was in the range
30<W<220
GeV
and the squared four-momentum transfer at the proton vertex
|t|<1
GeV
2
. The cross sections and decay angular distributions are presented as functions of
Q
2,
W and
t. The effective parameters of the pomeron trajectory are in agreement with those found in
J/
ψ photoproduction. The spin-density matrix elements, calculated from the decay angular distributions, are consistent with the hypothesis of
s-channel helicity conservation. The ratio of the longitudinal to transverse cross sections,
σ
L
/
σ
T
, grows with
Q
2, whilst no dependence on
W or
t is observed. The results are in agreement with perturbative QCD calculations and exhibit a strong sensitivity to the gluon distribution in the proton.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The photoproduction of isolated photons has been measured in diffractive events recorded by the ZEUS detector at HERA. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ...ranges 5<ETγ<15 GeV and −0.7<ηγ<0.9, inclusively, and also with a jet with transverse energy and pseudorapidity in the ranges 4<ETjet<35 GeV and −1.5<ηjet<1.8, using a total integrated electron-proton luminosity of 456 pb−1. A number of kinematic variables were studied and compared to predictions from the rapgap Monte Carlo model. An excess of data is observed above the rapgap predictions for zPmeas>0.9, where zPmeas is the fraction of the longitudinal momentum of the colorless “Pomeron” exchange that is transferred to the photon-jet final state, giving evidence for direct Pomeron interactions.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The photoproduction of isolated photons, both inclusive and together with a jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 374 pb−1. Differential cross ...sections are presented in the isolated-photon transverse-energy and pseudorapidity ranges 6<ETγ<15 GeV and −0.7<ηγ<0.9, and for jet transverse-energy and pseudorapidity ranges 4<ETjet<35 GeV and −1.5<ηjet<1.8, for exchanged-photon virtualities Q2<1 GeV2. Differential cross sections are also presented for inclusive isolated-photon production as functions of the transverse energy and pseudorapidity of the photon. Higher-order theoretical calculations are compared to the results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e + and e- beams, together with differential cross-section data on inclusive jet ...production in e + p scattering and dijet production in \(\gamma p\) scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet-production data constrains the gluon and allows an accurate extraction of \(\alpha_s(M_Z)\) at NLO; \(\alpha _{s} {\left( {M_{Z} } \right)} = 0.1183 \pm 0.0028{\left( {\exp .} \right)} \pm 0.0008{\left( {{\text{model}}} \right)}.\) An additional uncertainty from the choice of scales is estimated as \(\pm 0.005\). This is the first extraction of \(\alpha_s(M_Z)\) from HERA data alone.
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DOBA, FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this study was to characterize ion conductances and carrier mechanisms of isolated in vitro perfused rabbit colonic crypts. Crypts were isolated from rabbit colon mucosa and mounted on a ...pipette system which allowed controlled perfusion of the lumen. In non-stimulated conditions basolateral membrane voltage (Vbl) was -65 +/- 1 mV (n = 240). Bath Ba2+ (1 mmol/l) and verapamil (0.1 mmol/l) depolarized Vbl by 21 +/- 2 mV (n = 7) and 31 +/- 1 (n = 4), respectively. Lowering of bath Cl- concentration hyperpolarized Vbl from -69 +/- 3 to -75 +/- 3 mV (n = 9). Lowering of luminal Cl- concentration did not change Vbl. Basolateral application of loop diuretics (furosemide, piretanide, bumetanide) had no influence on Vbl in non-stimulated crypts. Forskolin (10(-6) mol/l) in the bath depolarized Vbl by 29 +/- 2 mV (n = 54) and decreased luminal membrane resistance. In one-third of the experiments a spontaneous partial repolarization of Vbl was seen in the presence of forskolin. During forskolin-induced depolarization basolateral application of loop diuretics hyperpolarized Vbl significantly and concentration dependently with a potency sequence of bumetanide > piretanide > or = furosemide. Lowering bath Cl- concentration hyperpolarized Vbl. Lowering of luminal Cl- concentration from 120 to 32 mmol/l during forskolin-induced depolarization led to a further depolarization of Vbl by 7 +/- 2 mV (n = 10). We conclude that Vbl of rabbit colonic crypt cells is dominated by a K+ conductance. Stimulation of the cells by forskolin opens a luminal Cl- conductance. Basolateral uptake of Cl- occurs via a basolateral Na+:2Cl-:K+ cotransport system.
Production of exclusive dijets in diffractive deep inelastic Formula omitted scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb Formula omitted. The ...measurement was performed for Formula omitted-p centre-of-mass energies in the range Formula omitted and for photon virtualities Formula omitted. Energy flows around the jet axis are presented. The cross section is presented as a function of Formula omitted and Formula omitted, where Formula omitted, x is the Bjorken variable and Formula omitted is the proton fractional longitudinal momentum loss. The angle Formula omitted is defined by the Formula omitted-dijet plane and the Formula omitted- Formula omitted plane in the rest frame of the diffractive final state. The Formula omitted cross section is measured in bins of Formula omitted. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.
Exclusive electroproduction of
ϕ mesons has been studied in
e
±
p
collisions at
s
=
318
GeV
with the ZEUS detector at HERA using an integrated luminosity of
65.1
pb
−1
. The
γ
∗
p
cross section ...is presented in the kinematic range
2
GeV
2
<
Q
2
<
70
GeV
2
,
35
GeV
<
W
<
145
GeV
and
|
t
|
<
0.6
GeV
2
. The cross sections as functions of
Q
2
,
W,
t and helicity angle
θ
h
are compared to cross sections for other vector mesons. The ratios
R of the cross sections for longitudinally and transversely polarized virtual photons are presented as functions of
Q
2
and
W. The data are also compared to predictions from theoretical models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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