In this paper we promote the use of Support Vector Machines (SVM) as a machine learning tool for searches in high-energy physics. As an example for a new-physics search we discuss the popular case of ...Supersymmetry at the Large Hadron Collider. We demonstrate that the SVM is a valuable tool and show that an automated discovery-significance based optimization of the SVM hyper-parameters is a highly efficient way to prepare an SVM for such applications.
If new phenomena beyond the Standard Model will be discovered at the LHC, the properties of the new particles could be determined with data from the High-Luminosity LHC and from a future linear ...collider like the ILC. We discuss the possible interplay between measurements at the two accelerators in a concrete example, namely a full SUSY model which features a small
τ
~
1
-LSP mass difference. Various channels have been studied using the Snowmass 2013 combined LHC detector implementation in the Delphes simulation package, as well as simulations of the ILD detector concept from the Technical Design Report. We investigate both the LHC and the ILC capabilities for discovery, separation and identification of various parts of the spectrum. While some parts would be discovered at the LHC, there is substantial room for further discoveries at the ILC. We finally highlight examples where the precise knowledge about the lower part of the mass spectrum which could be acquired at the ILC would enable a more in-depth analysis of the LHC data with respect to the heavier states.
Measurements of open charm production cross sections in deep-inelastic
ep
scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections
for charm production are obtained ...in the kinematic range of photon virtuality 2.5≤
Q
2
≤2000 GeV
2
and Bjorken scaling variable 3⋅10
−5
≤
x
≤5⋅10
−2
. The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for
W
±
and
Z
production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.
ZEUS inclusive diffractive-cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet ...production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data.
A
bstract
The production of
D
0
,
D
*
+
,
D
+
,
and
charm hadrons and their antiparticles in
ep
scattering at HERA has been studied with the ZEUS detector, using a total integrated luminosity of 372 ...pb
−1
. The fractions of charm quarks hadronising into a particular charm hadron were derived. In addition, the ratio of neutral to charged
D
-meson production rates, the fraction of charged
D
mesons produced in a vector state, and the stangeness-suppression factor have been determined. The measurements have been performed in the photoproduction regime. The charm hadrons were reconstructed in the range of transverse momentum
p
T
>
3
.
8 GeV and pseudorapidity |
η
|
<
1
.
6. The charm fragmentation fractions are compared to previous results from HERA and from
e
+
e
−
experiments. The data support the hypothesis that fragmentation is independent of the production process.
The dissociation of virtual photons,
γ
⋆
p
→
X
p
, in events with a large rapidity gap between
X and the outgoing proton, as well as in events in which the leading proton was directly measured, has ...been studied with the ZEUS detector at HERA. The data cover photon virtualities
Q
2
>
2
GeV
2
and
γ
⋆
p
centre-of-mass energies
40
<
W
<
240
GeV
, with
M
X
>
2
GeV
, where
M
X
is the mass of the hadronic final state,
X. Leading protons were detected in the ZEUS leading proton spectrometer. The cross section is presented as a function of
t, the squared four-momentum transfer at the proton vertex and
Φ, the azimuthal angle between the positron scattering plane and the proton scattering plane. It is also shown as a function of
Q
2
and
x
P
, the fraction of the proton's momentum carried by the diffractive exchange, as well as
β, the Bjorken variable defined with respect to the diffractive exchange.
The production of isolated high-energy photons accompanied by jets has been measured in deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 326 pb−1. ...Measurements were made for exchanged photon virtualities, Q2, in the range 10 to 350 GeV2. The photons were measured in the transverse-energy and pseudorapidity ranges 4<ETγ<15 GeV and −0.7<ηγ<0.9, and the jets were measured in the transverse-energy and pseudorapidity ranges 2.5<ETjet<35 GeV and −1.5<ηjet<1.8. Differential cross sections are presented as functions of these quantities. Perturbative QCD predictions give a reasonable description of the shape of the measured cross sections over most of the kinematic range, but the absolute normalisation is typically in disagreement by 20–30%.
Inclusive-jet and dijet differential cross sections have been measured in neutral current deep inelastic
ep scattering for exchanged boson virtualities
Q
2
>
125
GeV
2
with the ZEUS detector at ...HERA using an integrated luminosity of 82 pb
−1. Jets were identified in the Breit frame using the
k
T
cluster algorithm. Jet cross sections are presented as functions of several kinematic and jet variables. The results are also presented in different regions of
Q
2
. Next-to-leading-order QCD calculations describe the measurements well. Regions of phase space where the theoretical uncertainties are small have been identified. Measurements in these regions have the potential to constrain the gluon density in the proton when used as inputs to global fits of the proton parton distribution functions.
Mean values and differential distributions of event-shape variables have been studied in neutral current deep inelastic scattering using an integrated luminosity of 82.2 pb
−1 collected with the ZEUS ...detector at HERA. The kinematic range is
80
<
Q
2
<
20
480
GeV
2
and
0.0024
<
x
<
0.6
, where
Q
2
is the virtuality of the exchanged boson and
x is the Bjorken variable. The data are compared with a model based on a combination of next-to-leading-order QCD calculations with next-to-leading-logarithm corrections and the Dokshitzer–Webber non-perturbative power corrections. The power-correction method provides a reasonable description of the data for all event-shape variables studied. Nevertheless, the lack of consistency of the determination of
α
s
and of the non-perturbative parameter of the model,
α
0
¯
, suggests the importance of higher-order processes that are not yet included in the model.
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