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.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Exclusive photoproduction of ρ0(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 γp→π+π-Y. Reactions where the proton stays intact (mY=mp) are statistically separated from those where the proton dissociates to a low-mass hadronic system (mp<mY<10GeV). The double-differential cross sections are measured as a function of the invariant mass mππ 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 Wγp. The phase space restrictions are 0.5≤mππ≤2.2GeV, |t|≤1.5GeV2, and 20≤Wγp≤80GeV. Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the mππ dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the ρ0(770) meson mass and width at mρ=770.8-2.7+2.6(tot.)MeV and Γρ=151.3-3.6+2.7(tot.)MeV, respectively. The model is used to extract the ρ0(770) contribution to the π+π- cross sections and measure it as a function of t and Wγp. In a Regge asymptotic limit in which one Regge trajectory α(t) dominates, the intercept α(t=0)=1.0654-0.0067+0.0098(tot.) and the slope α′(t=0)=0.233-0.074+0.067(tot.)GeV-2 of the t dependence are extracted for the case mY=mp.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Exclusive photoproduction of
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
γ
p
→
π
+
π
-
Y
. Reactions where the proton stays intact (
m
Y
=
m
p
) are statistically separated from those where the proton dissociates to a low-mass hadronic system (
m
p
<
m
Y
<
10
GeV
). The double-differential cross sections are measured as a function of the invariant mass
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
γ
p
. The phase space restrictions are
0.5
≤
m
π
π
≤
2.2
GeV
,
|
t
|
≤
1.5
GeV
2
, and
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
π
π
dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the
ρ
0
(
770
)
meson mass and width at
m
ρ
=
770.8
-
2.7
+
2.6
(
tot.
)
MeV
and
Γ
ρ
=
151.3
-
3.6
+
2.7
(
tot.
)
MeV
, respectively. The model is used to extract the
ρ
0
(
770
)
contribution to the
π
+
π
-
cross sections and measure it as a function of
t
and
W
γ
p
. In a Regge asymptotic limit in which one Regge trajectory
α
(
t
)
dominates, the intercept
α
(
t
=
0
)
=
1.0654
-
0.0067
+
0.0098
(
tot.
)
and the slope
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
.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A measurement is presented of inelastic photo- and electroproduction of
J
/
ψ
mesons in
ep
scattering at HERA. The data were recorded with the H1 detector in the period from 2004 to 2007. Single and ...double differential cross sections are determined and the helicity distributions of the
J
/
ψ
mesons are analysed. The results are compared to theoretical predictions in the colour singlet model and in the framework of non-relativistic QCD. Calculations in the colour singlet model using a
k
T
factorisation ansatz are able to give a good description of the data, while colour singlet model calculations to next-to-leading order in collinear factorisation underestimate the data.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The cross section of diffractive deep-inelastic scattering
ep
→
eXp
is measured, where the system
X
contains at least two jets and the leading final state proton is detected in the H1 Forward Proton ...Spectrometer. The measurement is performed for fractional proton longitudinal momentum loss
x
ℙ
<0.1 and covers the range 0.1<|
t
|<0.7 GeV
2
in squared four-momentum transfer at the proton vertex and 4<
Q
2
<110 GeV
2
in photon virtuality. The differential cross sections extrapolated to |
t
|<1 GeV
2
are in agreement with next-to-leading order QCD predictions based on diffractive parton distribution functions extracted from measurements of inclusive and dijet cross sections in diffractive deep-inelastic scattering. The data are also compared with leading order Monte Carlo models.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for first generation scalar and vector leptoquarks produced in ep collisions is performed by the H1 experiment at HERA. The full H1 data sample is used in the analysis, corresponding to an ...integrated luminosity of 446 pb−1. No evidence for the production of leptoquarks is observed in final states with a large transverse momentum electron or with large missing transverse momentum, and constraints on leptoquark models are derived. For leptoquark couplings of electromagnetic strength λ=0.3, first generation leptoquarks with masses up to 800 GeV are excluded at 95% confidence level.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
Measurements of
D
∗
(
2010
)
meson production in diffractive deep inelastic scattering
(
5
<
Q
2
<
100
GeV
2
)
are presented which are based on HERA data recorded at a centre-of-mass energy
s
=
319
...GeV
with an integrated luminosity of 287 pb
-
1
. The reaction
e
p
→
e
X
Y
is studied, where the system
X
, containing at least one
D
∗
(
2010
)
meson, is separated from a leading low-mass proton dissociative system
Y
by a large rapidity gap. The kinematics of
D
∗
candidates are reconstructed in the
D
∗
→
K
π
π
decay channel. The measured cross sections compare favourably with next-to-leading order QCD predictions, where charm quarks are produced via boson-gluon fusion. The charm quarks are then independently fragmented to the
D
∗
mesons. The calculations rely on the collinear factorisation theorem and are based on diffractive parton densities previously obtained by H1 from fits to inclusive diffractive cross sections. The data are further used to determine the diffractive to inclusive
D
∗
production ratio in deep inelastic scattering.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A model-independent search for deviations from the Standard Model prediction is performed using the full e±p data sample collected by the H1 experiment at HERA. All event topologies involving ...isolated electrons, photons, muons, neutrinos and jets with transverse momenta above 20 GeV are investigated in a single analysis. Events are assigned to exclusive classes according to their final state. A dedicated algorithm is used to search for deviations from the Standard Model in the distributions of the scalar sum of transverse momenta or the invariant mass of final state particles and to quantify their significance. Variables related to angular distributions and energy sharing between final state particles are also introduced to study the final state topologies. No significant deviation from the Standard Model expectation is observed in the phase space covered by this analysis.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
A measurement is presented of elastic deeply virtual Compton scattering e++p→e++γ+p at HERA using data taken with the H1 detector. The cross section is measured as a function of the photon ...virtuality, Q2, and the invariant mass, W, of the γp system, in the kinematic range 2<Q2<20GeV2, 30<W<120GeV and |t|<1GeV2, where t is the squared momentum transfer to the proton. The measurement is compared to QCD based calculations.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
PDF
