Mr
Juan Cruz-Martinez
(University of Milano)
7/15/19, 2:00 PM
PDFs/alpha_S/Soft
We show recent developments on new methodologies for the determination of Parton Distribution Functions in the context of the NNPDF collaboration.
We study different models and architectures in a systematic way which allows as to assess the quality of the fit: overtraining, model complexity, hyperparameter setup, optimization algorithm...
We show a fully automatized pipeline to achieve...
Pavel Nadolsky
(SMU)
7/15/19, 2:25 PM
PDFs/alpha_S/Soft
I summarize results of a new global QCD analysis CT18 that includes a large number of new LHC experiments.
Dr
Thomas Cridge
(Univeristy College London)
7/15/19, 2:50 PM
PDFs/alpha_S/Soft
We discuss updates to the MMHT2014 and 2016 PDFs ahead of a new release of PDF sets. These updates include the addition of further data, largely from the LHC, as well as a consequent extension of our PDF parametrisation. We also summarise the results of our inclusion of QED effects in parton distributions.
Claire Gwenlan
(Oxford)
7/15/19, 3:15 PM
PDFs/alpha_S/Soft
NNLO predictions for jet production in Deep Inelastic Scattering have recently become available. These are used to extend the QCD HERAPDF2.0Jets fits, that were made to extract PDFs from inclusive HERA data and HERA jet data, from NLO to NNLO. In addition new jet data sets have become available since the publication of HERAPDF2.0 and these are also considered.
Dr
Antonio Sbrizzi
(INFN Bologna)
7/15/19, 3:40 PM
Inclusive single diffractive dissociation (pp->pX) is studied using data collected by the ATLAS experiment
at the LHC. The intact proton is reconstructed and measured in the ALFA forward spectrometer,
while charged particles from the dissociative system (X) are reconstructed and measured using
the ATLAS inner tracking detector and calorimeters. Differential cross sections are presented
as...
Mr
Christopher Schwan
(Universita degli Studi di Milano)
7/15/19, 4:30 PM
PDFs/alpha_S/Soft
Storing theoretical predictions for collider observables independent
from PDFs is a worthwhile goal from at least two different perspectives:
As a theorist producing the theoretical predictions this enables one to
quickly change the PDF set and thereby to assess possible differences of
the PDF sets. From the perspective of someone fitting a new PDF set, the
PDF-independent theoretical...
Riccardo Nagar
(DESY)
7/15/19, 4:55 PM
PDFs/alpha_S/Soft
We present an efficient implementation of the solution of the DGLAP equations for single and double parton distributions (PDFs and DPDs). The implemented algorithm is based on the Chebyshev interpolation of these functions. For PDF evolution, our method allows for a higher numerical accuracy using a considerably smaller amount of grid points compared to existing methods. As a consequence of...
Klaus Rabbertz
(ETP, KIT, Karlsruhe, Germany)
7/15/19, 5:20 PM
PDFs/alpha_S/Soft
The technique of interpolation grids as implemented in the APPLgrid or fastNLO
packages provides a fast and flexible way to reproduce the results of perturbative
QCD cross section calculations with any input PDF, choice of scales, or strong coupling
constant. Recent developments in the APPLfast interface between the NNLOJET QCD calculation with both packages are reported. As an example...
Svenja Pflitsch
(Deutsches Elektronen Synchrotron (DESY))
7/15/19, 5:45 PM
PDFs/alpha_S/Soft
Experimental constraints on collinear PDFs at 7, 8, 13 TeV (W, Z, jet production) by CMS are presented.
33.
Determination of proton parton distribution functions and extraction of alpha_S using ATLAS data
Claire Gwenlan
(Oxford)
7/15/19, 6:10 PM
We present fits to determine parton distribution functions (PDFs) using top-antitop, inclusive W/Z-boson,
as well as W+ and W− boson production measurements in association with jets from ATLAS, in combination
with deep-inelastic scattering data from HERA. The ATLAS W and Z boson data exhibit sensitivity to
the valence quark distributions and the light quark sea composition, whereas the...
Dr
Juska Pekkanen
(SUNY Buffalo)
7/16/19, 4:30 PM
The measurement of the QCD coupling constant by CMS is presented.
Claire Gwenlan
(Oxford)
7/16/19, 4:55 PM
PDFs/alpha_S/Soft
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams to achieve centre-of-mass energies 1.3-3.5 TeV and luminosities ~10^34 cm-2s-1. These three configurations will extend the kinematic plane by more than one order of magnitude towards smaller x and larger Q2 than HERA....
Carl Schmidt
(Michigan State University)
7/16/19, 5:20 PM
PDFs/alpha_S/Soft
We present a a software package, ePump (error PDF Updating Method Package), that can be used to update or optimize a set of PDFs, including the best-fit and Hessian eigenvector pairs of PDF sets, and also to update any other set of observables, in the Hessian approach. After validating the program with a comparison against a full global analysis, we use ePump to estimate the impact of several...
Dr
Timothy Hobbs
(CTEQ at SMU)
7/16/19, 6:10 PM
PDFs/alpha_S/Soft
With the conclusion of Run 2 in 2018, the LHC has now recorded a wealth of data well exceeding 100 fb$^{-1}$. In conjunction with the substantial output from other recent experiments at facilities like HERA and FNAL, these LHC data are an opportunity, as well as a challenge, for particle phenomenology. Incorporating new measurements into QCD global analyses of nucleon PDFs is difficult due to...
Diego Stocco
(Subatech)
7/18/19, 4:30 PM
PDFs/alpha_S/Soft
W and Z bosons are created in the hard scattering processes occurring in the initial stage of heavy-ion collisions and they are insensitive to the presence of a strongly-interactive medium. This makes them a clean probe of the initial-state effects of the collision, such as the nuclear modification of the parton distribution functions (PDFs).
The measurement of the electroweak boson...
Mr
Maxim Pieters
(University of Antwerp)
7/18/19, 4:55 PM
Double parton scattering measurements by CMS are presented.
Claire Gwenlan
(Oxford)
7/18/19, 5:45 PM
PDFs/alpha_S/Soft
Recent developments for the APPLgrid project are presented.
These include the ability to reproduce hadron-hadron interaction
cross sections with independent parton distributions for each
incoming hadron to facilitate QCD analysis of heavy ion data
including that from proton-heavy ion collisions.
Additional changes to allow the inclusion of a photon density
within incident hadrons to...