A measurement is presented of the inclusive neutral current e±p scattering cross section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam energies Ep ...of 920, 575, and 460 GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5 GeV2<Q2<120 GeV2, small values of Bjorken x, 2.9⋅10−5<x<0.01, and extends to high inelasticity up to y=0.85. The structure function FL is measured by combining the new results with previously published H1 data at Ep=920 GeV and Ep=820 GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q2 and low x kinematic domain.
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Diffractive electroproduction of ρ and ϕ mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb
−1
. ...About 10500 ρ and 2000 φ events are analysed in the kinematic range of squared photon virtuality 2.5 ≤
Q
2
≤ 60 GeV
2
, photon-proton centre of mass energy 35 ≤
W
≤ 180 GeV and squared four-momentum transfer to the proton |
t
| ≤ 3 GeV
2
. The total, longitudinal and transverse cross sections are measured as a function of
Q
2
,
W
and |
t
|. The measurements show a transition to a dominantly “hard” behaviour, typical of high gluon densities and small
dipoles, for
Q
2
larger than 10 to 20 GeV
2
. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (
Q
2
+
M
2
V
)/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables. The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal dipole cross sections.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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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A measurement of elastic deeply virtual Compton scattering γ∗p→γp using e+p and e−p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an ...integrated luminosity of 306 pb−1, almost equally shared between both beam charges. 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. Using e+p and e−p data samples, a beam charge asymmetry is extracted for the first time in the low Bjorken x kinematic domain. The observed asymmetry is attributed to the interference between Bethe–Heitler and deeply virtual Compton scattering processes. Experimental results are discussed in the context of two different models, one based on generalised parton distributions and one based on the dipole approach.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
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 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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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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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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The diffractive process
ep
→
eXY
, where
Y
denotes a proton or its low mass excitation with
M
Y
<1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space ...region of the photon virtuality 3 ≤
Q
2
≤ 1600 GeV
2
, the square of the four-momentum transfer at the proton vertex |
t
|< 1.0 GeV
2
and the longitudinal momentum fraction of the incident proton carried by the colourless exchange
x
ℙ
<0.05.
\printthanks
Triple differential cross sections are measured as a function of
x
ℙ
,
Q
2
and
β
=
x
/
x
ℙ
where
x
is the Bjorken scaling variable. These measurements are made after selecting diffractive events by demanding a large empty rapidity interval separating the final state hadronic systems
X
and
Y
. High statistics measurements covering the data taking periods 1999–2000 and 2004–2007 are combined with previously published results in order to provide a single set of diffractive cross sections from the H1 experiment using the large rapidity gap selection method. The combined data represent a factor between three and thirty increase in statistics with respect to the previously published results. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities and from a dipole model. The proton vertex factorisation hypothesis is tested.
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The parameters of the electroweak theory are determined in a combined electroweak and QCD analysis using all deep-inelastic Formula omitted and Formula omitted neutral current and charged current ...scattering cross sections published by the H1 Collaboration, including data with longitudinally polarised lepton beams. Various fits to Standard Model parameters in the on-shell scheme are performed. The mass of the W boson is determined as Formula omitted. The axial-vector and vector couplings of the light quarks to the Z boson are also determined. Both results improve the precision of previous H1 determinations based on HERA-I data by about a factor of two. Possible scale dependence of the weak coupling parameters in both neutral and charged current interactions beyond the Standard Model is also studied. All results are found to be consistent with the Standard Model expectations.
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