Abstract
The strong coupling constant
$$\alpha _\mathrm{s}$$
α
s
is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic
ep
scattering (DIS) measured at HERA by ...the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of
$$\alpha _\mathrm{s} (m_\mathrm{Z})$$
α
s
(
m
Z
)
at the
Z
-boson mass
$$m_Z$$
m
Z
are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be
$$\alpha _\mathrm{s} (m_\mathrm{Z}) =0.1157\,(20)_\mathrm{exp}\,(29)_\mathrm{th}$$
α
s
(
m
Z
)
=
0.1157
(
20
)
exp
(
29
)
th
. Complementary,
$$\alpha _\mathrm{s} (m_\mathrm{Z})$$
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
$$\alpha _\mathrm{s} (m_\mathrm{Z}) =0.1142\,(28)_\mathrm{tot}$$
α
s
(
m
Z
)
=
0.1142
(
28
)
tot
obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The strong coupling constant αs is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using ...next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of αs(mZ) at the Z-boson mass mZ are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be αs(mZ)=0.1157(20)exp(29)th. Complementary, αs(mZ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value αs(mZ)=0.1142(28)tot obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Inclusive production of D* mesons in deep-inelastic ep scattering at HERA is studied in the range 5 < Q(2) < 100 GeV2 of the photon virtuality and 0.02 < y < 0.7 of the inelasticity of the scattering ...process. The observed phase space for the D* meson is (pT) (D*) > 1.25 GeV and |eta( D*)| < 1.8. The data sample corresponds to an integrated luminosity of 348 pb(-1) collected with the H1 detector. Single and double differential cross sections are measured and the charm contribution F-2(c (c) over bar) to the proton structure function F-2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling ...variable $x > 10^{-3}$, the inelasticity $0.2< y < 0.7$ and the photon virtuality $150 < Q^2 < 15000$ GeV$^2$. The search is performed using H1 data corresponding to an integrated luminosity of ~$351$ pb$^{-1}$. No evidence for the production of QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between $1.5$~pb and $6$~pb, at $95\%$~ confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging theory predictions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The strong coupling constant
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
...\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\alpha _\mathrm{s}$$\end{document}
α
s
is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic
ep
scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\alpha _\mathrm{s} (m_\mathrm{Z})$$\end{document}
α
s
(
m
Z
)
at the
Z
-boson mass
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$m_Z$$\end{document}
m
Z
are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\alpha _\mathrm{s} (m_\mathrm{Z}) =0.1157\,(20)_\mathrm{exp}\,(29)_\mathrm{th}$$\end{document}
α
s
(
m
Z
)
=
0.1157
(
20
)
exp
(
29
)
th
. Complementary,
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\alpha _\mathrm{s} (m_\mathrm{Z})$$\end{document}
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
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\alpha _\mathrm{s} (m_\mathrm{Z}) =0.1142\,(28)_\mathrm{tot}$$\end{document}
α
s
(
m
Z
)
=
0.1142
(
28
)
tot
obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The production of jets is studied in deep-inelastic e(+) p scattering at low negative four momentum transfer squared 5 < Q(2) < 100 GeV2 and at inelasticity 0.2 < y < 0.7 using data recorded by the ...H1 detector at HERA in the years 1999 and 2000, corresponding to an integrated luminosity of 43.5 pb(-1). Inclusive jet, 2-jet and 3-jet cross sections as well as the ratio of 3-jet to 2-jet cross sections are measured as a function of Q(2) and jet transverse momentum. The 2-jet cross section is also measured as a function of the proton momentum fraction xi. The measurements are well described by perturbative quantum chromodynamics at next-to-leading order corrected for hadronisation effects and are subsequently used to extract the strong coupling as.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for physics beyond the Standard Model in neutral current deep inelastic scattering at high negative four-momentum transfer squared Q(2) is performed in e(+/-)p collisions at HERA. The ...differential cross section d sigma/dQ(2), measured using the full H1 data sample corresponding to an integrated luminosity of 446 pb(-1), is compared to the Standard Model prediction. No significant deviation is observed. Limits on various models predicting new phenomena at high Q(2) are derived. For general four-fermion eeqq contact interaction models, lower limits on the compositeness scale A are set in the range 3.6 TeV to 7.2 TeV. Leptoquarks with masses M-LQ and couplings lambda are constrained to M-LQ/lambda > 0.41-1.86 TeV and limits on squarks in R-parity violating supersymmetric models are derived. A lower limit on the gravitational scale in 4 + n dimensions of M-S > 0.9 TeV is established for low-scale quantum gravity effects in models with large extra dimensions. For the light quark radius an upper bound of R-q < 0.65 . 10(-18) m is determined. (C) 2011 Elsevier B.V. All rights reserved.
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Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling ...variable
x
>
10
-
3
, the inelasticity
0.2
<
y
<
0.7
and the photon virtuality
150
<
Q
2
<
15000
GeV
2
. The search is performed using H1 data corresponding to an integrated luminosity of 351 pb
-
1
. No evidence for the production of QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between 1.5 and 6 pb, at
95
%
confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging predictions.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A first measurement is presented of exclusive photoproduction of
ρ
0
mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a ...centre-of-mass energy of
s
=
319
GeV and correspond to an integrated luminosity of 1.16 pb
-
1
. The
ρ
0
mesons with transverse momenta
p
T
<
1
GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum,
x
L
>
0.35
, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality
Q
2
<
2
GeV
2
, the total energy of the photon–proton system
20
<
W
γ
p
<
100
GeV and the polar angle of the leading neutron
θ
n
<
0.75
mrad. The cross section of the reaction
γ
p
→
ρ
0
n
π
+
is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a
ρ
0
meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering,
σ
el
(
γ
π
+
→
ρ
0
π
+
)
, is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction
γ
p
→
ρ
0
n
π
+
.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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