Inclusive jet, dijet and trijet differential cross sections are measured in neutral current deep-inelastic scattering for exchanged boson virtualities
150
<
Q
2
<
15
000
GeV
2
using the H1 detector ...at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of
351
pb
-
1
. Double differential Jet cross sections are obtained using a regularised unfolding procedure. They are presented as a function of
Q
2
and the transverse momentum of the jet,
P
T
jet
, and as a function of
Q
2
and the proton’s longitudinal momentum fraction,
ξ
, carried by the parton participating in the hard interaction. In addition normalised double differential jet cross sections are measured as the ratio of the jet cross sections to the inclusive neutral current cross sections in the respective
Q
2
bins of the jet measurements. Compared to earlier work, the measurements benefit from an improved reconstruction and calibration of the hadronic final state. The cross sections are compared to perturbative QCD calculations in next-to-leading order and are used to determine the running coupling and the value of the strong coupling constant as
α
s
(
M
Z
)
=
0.1165
(
8
)
exp
(
38
)
pdf
,
theo
.
A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current
e
±
p
scattering for zero beam ...polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb
-
1
and span six orders of magnitude in negative four-momentum-transfer squared,
Q
2
, and Bjorken
x
. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in
α
s
(
M
Z
2
)
=
0.1183
±
0.0009
(
exp
)
±
0.0005
(
model
/
parameterisation
)
±
0.0012
(
hadronisation
)
-
0.0030
+
0.0037
(
scale
)
. An extraction of
x
F
3
γ
Z
and results on electroweak unification and scaling violations are also presented.
A measurement of the derivative (∂ lnF2/∂ lnx)Q2≡−λ(x,Q2) of the proton structure function F2 is presented in the low x domain of deeply inelastic positron–proton scattering. For 5×10−5⩽x⩽0.01 and ...Q2⩾1.5GeV2, λ(x,Q2) is found to be independent of x and to increase linearly with lnQ2.
The inclusive photoproduction of
D
∗
mesons and of
D
∗
-tagged dijets is investigated with the H1 detector at the
ep
collider HERA. The kinematic region covers small photon virtualities
Q
2
<2 GeV
2
...and photon–proton centre-of-mass energies of 100<
W
γp
<285 GeV. Inclusive
D
∗
meson differential cross sections are measured for central rapidities |
η
(
D
∗
)|<1.5 and transverse momenta
p
T
(
D
∗
)>1.8 GeV. The heavy quark production process is further investigated in events with at least two jets with transverse momentum
p
T
(jet)>3.5 GeV each, one containing the
D
∗
meson. Differential cross sections for
D
∗
-tagged dijet production and for correlations between the jets are measured in the range |
η
(
D
∗
)|<1.5 and
p
T
(
D
∗
)>2.1 GeV. The results are compared with predictions from Monte Carlo simulations and next-to-leading order perturbative QCD calculations.
Deep-inelastic ep scattering data taken with the H1 detector at HERA and corresponding to an integrated luminosity of 106 pb-1 are used to study the differential distributions of event shape ...variables. These include thrust, jet broadening, jet mass and the C-parameter. The four-momentum transfer Q is taken to be the relevant energy scale and ranges between 14 GeV and 200 GeV. The event shape distributions are compared with perturbative QCD predictions, which include resummed contributions and analytical power law corrections, the latter accounting for non-perturbative hadronisation effects. The data clearly exhibit the running of the strong coupling αs(Q) and are consistent with a universal power correction parameter α0 for all event shape variables. A combined QCD fit using all event shape variables yields αs(mZ)=0.1198±0.0013 +0.0056-0.0043 and α0=0.476±0.008 +0.018-0.059.
Inclusive
e
p
double differential cross sections for neutral current deep inelastic scattering are measured with the H1 detector at HERA. The data were taken with a lepton beam energy of
27.6
GeV ...and two proton beam energies of
E
p
=
460
and 575 GeV corresponding to centre-of-mass energies of 225 and 252 GeV, respectively. The measurements cover the region of
6.5
×
10
-
4
≤
x
≤
0.65
for
35
≤
Q
2
≤
800
GeV
2
up to
y
=
0.85
. The measurements are used together with previously published H1 data at
E
p
=
920
GeV and lower
Q
2
data at
E
p
=
460
,
575
and
920
GeV to extract the longitudinal proton structure function
F
L
in the region
1.5
≤
Q
2
≤
800
GeV
2
.
A
BSTRACT
Inclusive
e
±
p
single and double differential cross sections for neutral and charged current deep inelastic scattering processes are measured with the H1 detector at HERA. The data were ...taken at a centre-of-mass energy of
$ \sqrt {s} = {319} $
GeV with a total integrated luminosity of 333.7 pb
−1
shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of negative four-momentum transfer squared,
Q
2
, between 60 and 50 000 GeV
2
, and Bjorken
x
between 0
.
0008 and 0
.
65. The measurements are combined with earlier published unpolarised H1 data to improve statistical precision and used to determine the structure function
$ xF_{3}^{{\gamma Z}} $
. Ameasurementoftheneutralcurrentparityviolating structure function
$ F_{2}^{{\gamma Z}} $
is presented for the first time. The polarisation dependence of the charged current total cross section is also measured. The new measurements are well described by a next-to-leading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.
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