Objective
To review our experience with laparoscopic ureterolithotomy.
Patients and methods
Since 1993, we have performed laparoscopic ureterolithotomy in 14 patients with ureteric stones. ...Laparoscopy was carried out in nine patients as a salvage procedure after failed ureteroscopy (six), shock wave lithotripsy (two), or both (one), and in five patients as a primary procedure for large stones (mean 27.2 mm, range 18–40). Patients in the former group had already undergone a mean of 1.88 procedures (range 1–4). Laparoscopic ureterolithotomy was carried out via a transperitoneal approach. Associated ureteric strictures were incised at the time of ureterotomy.
Results
All procedures were completed laparoscopically and all patients were rendered stone‐free after a single procedure. The mean operative duration was 105 min. Ureteric strictures were incised in three patients, in two of whom dilatation was subsequently required; all three had a successful result. There were three minor complications.
Conclusions
Laparoscopic ureterolithotomy can be a safe and effective procedure; it should be considered as a primary procedure for large mid‐ and upper ureteric stones.
The exclusive photoproduction reaction γp→ϒp has been studied with the ZEUS experiment in ep collisions at HERA using an integrated luminosity of 468 pb−1. The measurement covers the kinematic range ...60<W<220 GeV and Q2<1 GeV2, where W is the photon–proton centre-of-mass energy and Q2 is the photon virtuality. These results, which represent the analysis of the full ZEUS data sample for this channel, are compared to predictions based on perturbative QCD.
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.
Isolated photon production in deep inelastic ep scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 320 pb−1. Measurements were made in the isolated-photon ...transverse-energy and pseudorapidity ranges 4<ETγ<15 GeV and −0.7<ηγ<0.9 for exchanged photon virtualities, Q2, in the range 10<Q2<350 GeV2 and for invariant masses of the hadronic system WX>5 GeV. Differential cross sections are presented for inclusive isolated photon production as functions of Q2, x, ETγ and ηγ. Leading-logarithm parton-shower Monte Carlo simulations and perturbative QCD predictions give a reasonable description of the data over most of the kinematic range.
For the first time, differential inclusive-jet cross sections have been measured in neutral current deep inelastic ep scattering using the anti-kT and SIScone algorithms. The measurements were made ...for boson virtualities Q2>125 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 82 pb−1 and the jets were identified in the Breit frame. The performance and suitability of the jet algorithms for their use in hadron-like reactions were investigated by comparing the measurements to those performed with the kT algorithm. Next-to-leading-order QCD calculations give a good description of the measurements. 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(αs3) terms. Values of αs(MZ) were extracted from the data; the results are compatible with and have similar precision to the value extracted from the kT analysis.
The production of charm and beauty quarks in
ep
interactions has been measured with the ZEUS detector at HERA for squared four-momentum exchange
Q
2
>20 GeV
2
, using an integrated luminosity of ...126 pb
−1
. Charm and beauty quarks were identified through their decays into muons. Differential cross sections were measured for muon transverse momenta
and pseudorapidities −1.6<
η
μ
<2.3, as a function of
,
η
μ
,
Q
2
and Bjorken
x
. The charm and beauty contributions to the proton structure function
F
2
were also extracted. The results agree with previous measurements based on independent techniques and are well described by QCD predictions.
The exclusive photoproduction reaction γp→ϒ(1S)p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468 pb−1. The measurement covers the kinematic ...range 60<W<220 GeV and Q2<1 GeV2, where W is the photon–proton centre-of-mass energy and Q2 is the photon virtuality. The exponential slope, b, of the t dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured, yielding b=4.3−1.3+2.0(stat.)−0.6+0.5(syst.) GeV−2. This constitutes the first measurement of the t dependence of the γp→ϒ(1S)p cross section.
The production of dijets in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 61 pb-1. The dijet cross section has been measured ...for virtualities of the exchanged virtual photon, 5 < Q2 < 100 GeV2, and γ*p centre-of-mass energies, 100 < W < 250 GeV. The jets, identified using the inclusive kT algorithm in the γ*p frame, were required to have a transverse energy E*T,jet > 4 GeV and the jet with the highest transverse energy was required to have E*T,jet > 5 GeV. All jets were required to be in the pseudorapidity range -3.5<η*jet<0. The differential cross sections are compared to leading-order predictions and next-to-leading-order QCD calculations based on recent diffractive parton densities extracted from inclusive diffractive deep inelastic scattering data.
Exclusive electroproduction of two pions at HERA Abramowicz, H.; Aggarwal, R.; Antonov, A. ...
The European physical journal. C, Particles and fields,
01/2012, Letnik:
72, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The exclusive electroproduction of two pions in the mass range 0.4<
M
ππ
<2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb
−1
. The analysis was carried ...out in the kinematic range of 2<
Q
2
<80 GeV
2
, 32<
W
<180 GeV and |
t
|<0.6 GeV
2
, where
Q
2
is the photon virtuality,
W
is the photon-proton centre-of-mass energy and
t
is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, |
F
(
M
ππ
)|, assuming that the studied mass range includes the contributions of the
ρ
,
ρ
′ and
ρ
′′ vector-meson states. The masses and widths of the resonances were obtained and the
Q
2
dependence of the cross-section ratios
σ
(
ρ
′→
ππ
)/
σ
(
ρ
) and
σ
(
ρ
′′→
ππ
)/
σ
(
ρ
) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in
e
+
e
−
→
π
+
π
−
.
A
bstract
The production of
D
*±
mesons in deep inelastic
ep
scattering has been measured for exchanged photon virtualities 5 <
Q
2
< 1000 GeV
2
, using an integrated luminosity of 363 pb
−1
with ...the ZEUS detector at HERA. Differential cross sections have been measured and compared to next-to-leading-order QCD calculations. The cross-sections are used to extract the charm contribution to the proton structure functions, expressed in terms of the reduced charm cross section,
. Theoretical calculations based on fits to inclusive HERA data are compared to the results.
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