(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A first measurement is presented of exclusive photoproduction of ... 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 ... GeV and correspond to an integrated luminosity of 1.16 pb... The ... mesons with transverse momenta ... GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, ..., are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality ... GeV..., the total energy of the photon-proton system ... GeV and the polar angle of the leading neutron ... mrad. The cross section of the reaction ... 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 ... meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, ..., is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction ...
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PLB 844 (2023) 138101 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 $k_{\mathrm{T}}$ jet clustering algorithm.
Results are reported at high transverse momentum transfer $Q^2>150$ GeV^2$,
and inelasticity $0.2 < y < 0.7$. The analysis is also performed in sub-regions
of $Q^2$, 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.
Charged particle production in deep-inelastic
ep
scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5<
Q
2
<100 GeV
2
, and small ...values of Bjorken-
x
, 10
−4
<
x
<10
−2
. The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity (
η
∗
) and transverse momentum (
) in the range 0<
η
∗
<5 and
in bins of
x
and
Q
2
. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Inclusive ... 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 ... GeV and two proton beam energies of ... and 575 GeV corresponding to centre-of-mass energies of 225 and 252 GeV, respectively. The measurements cover the region of ... for ... GeV... up to ... The measurements are used together with previously published H1 data at ... GeV and lower ... data at ..., ... and ... GeV to extract the longitudinal proton structure function ... in the region ... GeV...
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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 \(\alpha_s(M_Z^2)\) and and the PDFs, was performed with the result \(\alpha_s(M_Z^2) = 0.1156 \pm 0.0011~{\rm (exp)}~ ^{+0.0001}_{-0.0002}~ {\rm (model}\) \({\rm +~parameterisation)}~ \pm 0.0029~{\rm (scale)}\). The PDF sets of HERAPDF2.0Jets NNLO were determined with separate fits using two fixed values of \(\alpha_s(M_Z^2)\), \(\alpha_s(M_Z^2)=0.1155\) 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.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to ...the proton beam direction in deep-inelastic ... scattering at HERA are presented as a function of the Feynman variable ... and of the centre-of-mass energy of the virtual photon-proton system ... The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of ... The measurement is restricted to photons and neutrons in the pseudorapidity range ... and covers the range of negative four momentum transfer squared at the positron vertex ... GeV..., of inelasticity ... and of ...GeV. To test the Feynman scaling hypothesis the ... dependence of the ... dependent cross sections is investigated. Predictions of deep-inelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Cross sections for elastic and proton-dissociative photoproduction of J/ψ mesons are measured with the H1 detector in ...positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies ... and ..., corresponding to integrated luminosities of ... and ..., respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25<W ^sub γp^<110 GeV. Differential cross sections dσ/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range |t|<1.2 GeV^sup 2^ for the elastic process and |t|<8 GeV^sup 2^ for proton dissociation. The results are compared to other measurements. The W ^sub γp^ and t-dependences are parametrised using phenomenological fits.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Inclusive ... 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 ... GeV and two proton beam energies of ... and 575 GeV corresponding to centre-of-mass energies of 225 and 252 GeV, respectively. The measurements cover the region of ... for ... GeV... up to ... The measurements are used together with previously published H1 data at ... GeV and lower ... data at ..., ... and ... GeV to extract the longitudinal proton structure function ... in the region ... GeV...
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This contribution proposes a new formulation to efficiently compute directional derivatives of order one to fourth. The formulation is based on automatic differentiation implemented with dual ...numbers. Directional derivatives are particular cases of symmetric multilinear forms; therefore, using their symmetric properties and their coordinate representation, we implement functions to calculate mixed partial derivatives. Moreover, with directional derivatives, we deduce concise formulas for the velocity, acceleration, jerk, and jounce/snap vectors. The utility of our formulation is proved with three examples. The first example presents a comparison against the forward mode of finite differences to compute the fourth-order directional derivative of a scalar function. To this end, we have coded the finite differences method to calculate partial derivatives until the fourth order, to any order of approximation. The second example presents efficient computations of the velocity, acceleration, jerk, and jounce/snap. Finally, the third example is related to the computation of some partial derivatives. The implemented code of the proposed formulation and the finite differences method is proportioned as additional material to this article.
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