The production of leading neutrons, where the neutron carries a large fraction
x
L
of the incoming proton’s longitudinal momentum, is studied in deep-inelastic positron-proton scattering at HERA. The ...data were taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 122 pb
−1
. The semi-inclusive cross section is measured in the phase space defined by the photon virtuality 6<
Q
2
<100 GeV
2
, Bjorken scaling variable 1.5⋅10
−4
<
x
<3⋅10
−2
, longitudinal momentum fraction 0.32<
x
L
<0.95 and neutron transverse momentum
p
T
<0.2 GeV. The leading neutron structure function,
, and the fraction of deep-inelastic scattering events containing a leading neutron are studied as a function of
Q
2
,
x
and
x
L
. Assuming that the pion exchange mechanism dominates leading neutron production, the data provide constraints on the shape of the pion structure function.
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The measurement of the jet cross sections by the H1 collaboration had been compared to various predictions including the next-to-next-to-leading order (NNLO) QCD calculations which are corrected in ...this erratum for an implementation error in one of the components of the NNLO calculations. The jet data and the other predictions remain unchanged. Eight figures, one table and conclusions are adapted accordingly, exhibiting even better agreement between the corrected NNLO predictions and the jet data.
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A measurement of elastic deeply virtual Compton scattering γ∗p→γp using e−p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated ...luminosity of 145 pb−1. The cross section is measured as a function of the virtuality Q2 of the exchanged photon and the centre-of-mass energy W of the γ∗p system in the kinematic domain 6.5<Q2<80 GeV2, 30<W<140 GeV and |t|<1 GeV2, where t denotes the squared momentum transfer at the proton vertex. The cross section is determined differentially in t for different Q2 and W values and exponential t-slope parameters are derived. The measurements are compared to a NLO QCD calculation based on generalised parton distributions. In the context of the dipole approach, the geometric scaling property of the DVCS cross section is studied for different values of t.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
Abstract
The determination of the strong coupling constant
$$\alpha _{\mathrm{s}} (m_{\mathrm{Z}})$$
α
s
(
m
Z
)
from H1 inclusive and dijet cross section data 1 exploits perturbative QCD predictions ...in next-to-next-to-leading order (NNLO) 2–4. An implementation error in the NNLO predictions was found 4 which changes the numerical values of the predictions and the resulting values of the fits. Using the corrected NNLO predictions together with inclusive jet and dijet data, the strong coupling constant is determined to be
$$\alpha _{\mathrm{s}} (m_{\mathrm{Z}}) =0.1166\,(19)_{\mathrm{exp}}\,(24)_{\mathrm{th}}$$
α
s
(
m
Z
)
=
0.1166
(
19
)
exp
(
24
)
th
. Complementarily,
$$\alpha _{\mathrm{s}} (m_{\mathrm{Z}})$$
α
s
(
m
Z
)
is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value
$$\alpha _{\mathrm{s}} (m_{\mathrm{Z}}) =0.1147\,(25)_{\mathrm{tot}}$$
α
s
(
m
Z
)
=
0.1147
(
25
)
tot
obtained is consistent with the determination from jet data alone. Corrected figures and numerical results are provided and the discussion is adapted accordingly.
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A precision measurement of jet cross sections in neutral current deep-inelastic scattering for photon virtualities Formula omitted and inelasticities Formula omitted is presented, using data taken ...with the H1 detector at HERA, corresponding to an integrated luminosity of Formula omitted. Double-differential inclusive jet, dijet and trijet cross sections are measured simultaneously and are presented as a function of jet transverse momentum observables and as a function of Formula omitted. Jet cross sections normalised to the inclusive neutral current DIS cross section in the respective Formula omitted-interval are also determined. Previous results of inclusive jet cross sections in the range Formula omitted are extended to low transverse jet momenta Formula omitted. The data are compared to predictions from perturbative QCD in next-to-leading order in the strong coupling, in approximate next-to-next-to-leading order and in full next-to-next-to-leading order. Using also the recently published H1 jet data at high values of Formula omitted, the strong coupling constant Formula omitted is determined in next-to-leading order.
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The determination of the strong coupling constant
α
s
(
m
Z
)
from H1 inclusive and dijet cross section data
1
exploits perturbative QCD predictions in next-to-next-to-leading order (NNLO)
2
–
4
. ...An implementation error in the NNLO predictions was found
4
which changes the numerical values of the predictions and the resulting values of the fits. Using the corrected NNLO predictions together with inclusive jet and dijet data, the strong coupling constant is determined to be
α
s
(
m
Z
)
=
0.1166
(
19
)
exp
(
24
)
th
. Complementarily,
α
s
(
m
Z
)
is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value
α
s
(
m
Z
)
=
0.1147
(
25
)
tot
obtained is consistent with the determination from jet data alone. Corrected figures and numerical results are provided and the discussion is adapted accordingly.
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A measurement of the inclusive deep inelastic neutral current
e
+
p
scattering cross section is reported in the region of four-momentum transfer squared, 12 GeV
2
≤
Q
2
≤150 GeV
2
, and Bjorken
x
, ...2×10
−4
≤
x
≤0.1. The results are based on data collected by the H1 Collaboration at the
ep
collider HERA at positron and proton beam energies of
E
e
=27.6 GeV and
E
p
=920 GeV, respectively. The data are combined with previously published data, taken at
E
p
=820 GeV. The accuracy of the combined measurement is typically in the range of 1.3–2%. A QCD analysis at next-to-leading order is performed to determine the parton distributions in the proton based on H1 data.
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Abstract
Exclusive photoproduction of
$${{\rho ^0}} (770)$$
ρ
0
(
770
)
mesons is studied using the H1 detector at the
ep
collider HERA. A sample of about 900,000 events is used to measure single- ...and double-differential cross sections for the reaction
$$\gamma p \rightarrow \pi ^{+}\pi ^{-}Y$$
γ
p
→
π
+
π
-
Y
. Reactions where the proton stays intact (
$${{{m_Y}} {=}m_p}$$
m
Y
=
m
p
) are statistically separated from those where the proton dissociates to a low-mass hadronic system (
$$m_p{<}{{m_Y}} {<}10~{{\text {GeV}}} $$
m
p
<
m
Y
<
10
GeV
). The double-differential cross sections are measured as a function of the invariant mass
$$m_{\pi \pi }$$
m
π
π
of the decay pions and the squared 4-momentum transfer
t
at the proton vertex. The measurements are presented in various bins of the photon–proton collision energy
$${{W_{\gamma p}}} $$
W
γ
p
. The phase space restrictions are
$$0.5\le m_{\pi \pi } \le 2.2~{{\text {GeV}}} $$
0.5
≤
m
π
π
≤
2.2
GeV
,
$$\vert t\vert \le 1.5~{{\text {GeV}^2}} $$
|
t
|
≤
1.5
GeV
2
, and
$$20 \le W_{\gamma p} \le 80~{{\text {GeV}}} $$
20
≤
W
γ
p
≤
80
GeV
. Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the
$${m_{\pi \pi }}$$
m
π
π
dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the
$${{\rho ^0}} (770)$$
ρ
0
(
770
)
meson mass and width at
$$m_\rho = 770.8{}^{+2.6}_{-2.7}~({\text {tot.}})~{{\text {MeV}}} $$
m
ρ
=
770.8
-
2.7
+
2.6
(
tot.
)
MeV
and
$$\Gamma _\rho = 151.3 {}^{+2.7}_{-3.6}~({\text {tot.}})~{{\text {MeV}}} $$
Γ
ρ
=
151.3
-
3.6
+
2.7
(
tot.
)
MeV
, respectively. The model is used to extract the
$${{\rho ^0}} (770)$$
ρ
0
(
770
)
contribution to the
$$\pi ^{+}\pi ^{-}$$
π
+
π
-
cross sections and measure it as a function of
t
and
$${W_{\gamma p}}$$
W
γ
p
. In a Regge asymptotic limit in which one Regge trajectory
$$\alpha (t)$$
α
(
t
)
dominates, the intercept
$$\alpha (t{=}0) = 1.0654\ {}^{+0.0098}_{-0.0067}~({\text {tot.}})$$
α
(
t
=
0
)
=
1.0654
-
0.0067
+
0.0098
(
tot.
)
and the slope
$$\alpha ^\prime (t{=}0) = 0.233 {}^{+0.067 }_{-0.074 }~({\text {tot.}}) ~{{\text {GeV}^{-2}}} $$
α
′
(
t
=
0
)
=
0.233
-
0.074
+
0.067
(
tot.
)
GeV
-
2
of the
t
dependence are extracted for the case
$$m_Y{=}m_p$$
m
Y
=
m
p
.
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A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic
ep
...scattering data at a centre-of-mass energy
where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6 % for the most precise points. The combined data cover the range 2.5<
Q
2
<200 GeV
2
in photon virtuality,
in proton fractional momentum loss, 0.09<|
t
|<0.55 GeV
2
in squared four-momentum transfer at the proton vertex and 0.0018<
β
<0.816 in
, where
x
is the Bjorken scaling variable.
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Charged particle multiplicity distributions in positron-proton deep inelastic scattering at a centre-of-mass energy Formula omitted GeV are measured. The data are collected with the H1 detector at ...HERA corresponding to an integrated luminosity of 136 pb Formula omitted. Charged particle multiplicities are measured as a function of photon virtuality Formula omitted, inelasticity y and pseudorapidity Formula omitted in the laboratory and the hadronic centre-of-mass frames. Predictions from different Monte Carlo models are compared to the data. The first and second moments of the multiplicity distributions are determined and the KNO scaling behaviour is investigated. The multiplicity distributions as a function of Formula omitted and the Bjorken variable Formula omitted are converted to the hadron entropy Formula omitted, and predictions from a quantum entanglement model are tested.
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