259 research outputs found
CHARACTERISTICS OF THE SECONDARY PARTICLES FROM π-C INTERACTIONS AT 40 GEV/C IN DIFFERENT NUCLEAR MATTER PHASES
In this paper we have presented the angular and momentum characteristics of the secondary particles from Π–C interactions at 40 GeV/c in different phase transition regions of nuclear matter
Fragmentation of projectile nucleus
The temperature characteristics of carbon spectator fragments formed in
carbon collisions with carbon nuclei at a primary momentum of 4.2 GeV/c per
nucleon were presented and discussed on corrected experimental data. As well as
studied the multiplicities formed by the spectator protons, deuterons, and
tritons in the inelastic nucleus-nucleus interactions. We found that the
temperature absorbed by the spectator fragments is dependent on their mass.Comment: 8 pages, 5 figures, 2 table
Erratum to: Determination of the strong coupling constant {{\varvec{\alpha _{\mathrm{s}} (m_{\mathrm{Z}})}}} in next-to-next-to-leading order QCD using H1 jet cross section measurements
Unbinned Deep Learning Jet Substructure Measurement in High ep collisions at HERA
The radiation pattern within high energy quark- and gluon-initiated jets (jet
substructure) is used extensively as a precision probe of the strong force as
well as an environment for optimizing event generators with numerous
applications in high energy particle and nuclear physics. Looking at
electron-proton collisions is of particular interest as many of the
complications present at hadron colliders are absent. A detailed study of
modern jet substructure observables, jet angularities, in electron-proton
collisions is presented using data recorded using the H1 detector at HERA. The
measurement is unbinned and multi-dimensional, using machine learning to
correct for detector effects. All of the available reconstructed object
information of the respective jets is interpreted by a graph neural network,
achieving superior precision on a selected set of jet angularities. Training
these networks was enabled by the use of a large number of GPUs in the
Perlmutter supercomputer at Berkeley Lab. The particle jets are reconstructed
in the laboratory frame, using the jet clustering algorithm.
Results are reported at high transverse momentum transfer GeV,
and inelasticity . The analysis is also performed in sub-regions
of , thus probing scale dependencies of the substructure variables. The
data are compared with a variety of predictions and point towards possible
improvements of such models.Comment: 33 pages, 10 figures, 8 table
Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA
Inclusive charm and beauty cross sections are measured in e − p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q 2≤2000 GeV2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb−1. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions
Impact of jet-production data on the next-to-next-to-leading-order determination of HERAPDF2.0 parton distributions
The HERAPDF2.0 ensemble of parton distribution functions (PDFs) was introduced in 2015. The final stage is presented, a next-to-next-to-leading-order (NNLO) analysis of the HERA data on inclusive deep inelastic ep scattering together with jet data as published by the H1 and ZEUS collaborations. A perturbative QCD fit, simultaneously of αs(M2Z) and the PDFs, was performed with the result αs(M2Z)=0.1156±0.0011 (exp) +0.0001−0.0002 (model +parameterisation) ±0.0029 (scale). The PDF sets of HERAPDF2.0Jets NNLO were determined with separate fits using two fixed values of αs(M2Z), αs(M2Z)=0.1155 and 0.118, since the latter value was already chosen for the published HERAPDF2.0 NNLO analysis based on HERA inclusive DIS data only. The different sets of PDFs are presented, evaluated and compared. The consistency of the PDFs determined with and without the jet data demonstrates the consistency of HERA inclusive and jet-production cross-section data. The inclusion of the jet data reduced the uncertainty on the gluon PDF. Predictions based on the PDFs of HERAPDF2.0Jets NNLO give an excellent description of the jet-production data used as input
Study of Charm Fragmentation into D^{*\pm} Mesons in Deep-Inelastic Scattering at HERA
The process of charm quark fragmentation is studied using meson
production in deep-inelastic scattering as measured by the H1 detector at HERA.
Two different regions of phase space are investigated defined by the presence
or absence of a jet containing the meson in the event. The
parameters of fragmentation functions are extracted for QCD models based on
leading order matrix elements and DGLAP or CCFM evolution of partons together
with string fragmentation and particle decays. Additionally, they are
determined for a next-to-leading order QCD calculation in the fixed flavour
number scheme using the independent fragmentation of charm quarks to
mesons.Comment: 33 pages, submitted to EPJ
Erratum to: Determination of the integrated luminosity at HERA using elastic QED compton events
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