We aimed to define determinants of duration of treatment for acute symptomatic neonatal seizures in a contemporary multicenter observational cohort study. After adjustment for potential confounders, ...only study site and seizure etiology remained significantly associated with the chance of continuing antiseizure medication after discharge to home.
Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb{sup -1}. Charm has been tagged by reconstructing D*+, D{sup 0}, ...D{sup +} and D{sup +}{sub s} (+ c.c.) charm mesons. The charm hadrons were measured in the kinematic range p{sub T}(D*+,D{sup 0}0, D{sup +}) > 3 GeV, p{sub T}(D{sup +}{sub s}) > 2 GeV and |{eta}(D)| < 1.6 for 1.5 < Q{sup 2} < 1000 GeV{sup 2} and 0.02 < y < 0.7. The production cross sections were used to extract charm fragmentation ratios and the fraction of c quarks hadronising into a particular charm meson in the kinematic range considered. The cross sections were compared to the predictions of next-to-leading-order QCD, and extrapolated to the full kinematic region in p{sub T}(D) and {eta}(D) in order to determine the open-charm contribution, F{sub 2}{sup c}{anti c}(x, Q{sup 2}), to the proton structure function F{sub 2}.
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 132 pb
−1
collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. 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
>200 GeV
2
. The reduced cross-section
is presented in the kinematic range 200<
Q
2
<60 000 GeV
2
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.
Deep inelastic scattering and its diffractive component,
e
p
→
e
′
γ
∗
p
→
e
′
X
N
, have been studied at HERA with the ZEUS detector using an integrated luminosity of 52.4 pb
−1. The
M
X
method has ...been used to extract the diffractive contribution. A wide range in the centre-of-mass energy
W (37–245 GeV), photon virtuality
Q
2
(20–450 GeV
2) and mass
M
X
(0.28–35 GeV) is covered. The diffractive cross section for
2
<
M
X
<
15
GeV
rises strongly with
W, the rise becoming steeper as
Q
2
increases. The data are also presented in terms of the diffractive structure function,
F
2
D
(
3
)
, of the proton. For fixed
Q
2
and fixed
M
X
,
x
P
F
2
D
(
3
)
shows a strong rise as
x
P
→
0
, where
x
P
is the fraction of the proton momentum carried by the pomeron. For Bjorken-
x
<
1
×
10
−3
,
x
P
F
2
D
(
3
)
shows positive
log
Q
2
scaling violations, while for
x
⩾
5
×
10
−3
negative scaling violations are observed. The diffractive structure function is compatible with being leading twist. The data show that Regge factorisation is broken.
The production of energetic neutrons in
ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and
p
T
2
distributions were measured with a forward neutron calorimeter and ...tracker in a
40
pb
−1
sample of inclusive deep inelastic scattering (DIS) data and a
6
pb
−1
sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper
p
T
2
distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data.
The production of
D
*
±
(
2010
)
mesons in
e
±
p
scattering in the range of exchanged photon virtuality
0.05
<
Q
2
<
0.7
GeV
2
has been measured with the ZEUS detector at HERA using an integrated ...luminosity of 82 pb
−1. The decay channels
D
*
+
→
D
0
π
+
with
D
0
→
K
−
π
+
and corresponding antiparticle decay were used to identify
D
*
mesons and the ZEUS beampipe calorimeter was used to identify the scattered electron. Differential
D
*
cross sections as functions of
Q
2
, inelasticity,
y, transverse momentum of the
D
*
meson,
p
T
(
D
*
)
, and pseudorapidity of the
D
*
meson,
η
(
D
*
)
, have been measured in the kinematic region
0.02
<
y
<
0.85
,
1.5
<
p
T
(
D
*
)
<
9.0
GeV
and
|
η
(
D
*
)
|
<
1.5
. The measured differential cross sections are in agreement with two different NLO QCD calculations. The cross sections are also compared to previous ZEUS measurements in the photoproduction and DIS regimes.
Inclusive dijet and trijet production in deep inelastic
ep scattering has been measured for
10
<
Q
2
<
100
GeV
2
and low Bjorken
x,
10
−4
<
x
Bj
<
10
−2
. The data were taken at the HERA
ep collider ...with centre-of-mass energy
s
=
318
GeV
using the ZEUS detector and correspond to an integrated luminosity of
82
pb
−1
. Jets were identified in the hadronic centre-of-mass (HCM) frame using the
k
T
cluster algorithm in the longitudinally invariant inclusive mode. Measurements of dijet and trijet differential cross sections are presented as functions of
Q
2
,
x
Bj
, jet transverse energy, and jet pseudorapidity. As a further examination of low-
x
Bj
dynamics, multi-differential cross sections as functions of the jet correlations in transverse momenta, azimuthal angles, and pseudorapidity are also presented. Calculations at
O
(
α
s
3
)
generally describe the trijet data well and improve the description of the dijet data compared to the calculation at
O
(
α
s
2
)
.
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