214 research outputs found
Monte Carlo event generation of photon-photon collisions at colliders
In addition to being interesting in itself, the photon-photon interactions
will be an inevitable background for the future electron-positron colliders.
Thus to be able to quantify the potential of future electron-positron colliders
it is important to have an accurate description of these collisions. Here we
present our ongoing work to implement the photon-photon collisions in the
Pythia 8 event generator. First we introduce photon PDFs in general and then
discuss in more detail one particular set we have used in our studies. Then we
will discuss how the parton-shower algorithm in Pythia 8 is modified in case of
photon beams and how the beam remnants are constructed. Finally a brief outlook
on future developments is given.Comment: Talk presented at PHOTON2015 conference, June 15 - 19, 2015, Budker
Institute of Nuclear Physics (BINP), Siberian Branch of Russian Academy of
Science, Novosibirsk, Russi
Electron-Ion Physics with the LHeC
The Large Hadron Electron Collider (LHeC) project is the proposal to use the
existing LHC proton/ion beams and construct a new electron beam line to perform
high-energy electron-proton/ion collisions. In this talk, we consider some of
the physics topics that could be studied in the electron-ion mode. In
particular, we estimate how much the current nuclear parton distribution fits
could be improved with the deeply inelastic scattering measurements at the LHeC
by including pseudodata into a global analysis. In addition, we discuss briefly
other topics that would help to better understand some aspects of heavy-ion
collisions, namely small- physics and hadron production with a nuclear
target.Comment: Talk presented at DIS2015 conference, April 27 - May 1, 2015,
Southern Methodist University, Dallas, Texas. v2: Updated reference lis
nPDF constraints from the Large Hadron Electron Collider
An updated analysis regarding the expected nuclear PDF constraints from the
future Large Hadron Electron Collider (LHeC) experiment is presented. The new
study is based on a more flexible small- parametrization which provides less
biased uncertainty estimates in the region where there are currently no data
constraints. The effect of the LHeC is quantified by directly including a
sample of pseudodata according to the expected precision of this planned
experiment. As a result, a significant reduction of the small- uncertainties
in sea quarks and gluons is observed.Comment: Talk presented at DIS2016 conference, April 11 - April 15, 2016,
DESY, Hamburg, German
Recent Pythia 8 developments: Hard diffraction, Colour reconnection and collisions
An overview of recent developments in \pythia~8 is given. First the new hard
diffraction model, which is implemented as a part of the multiparton
interactions (MPI) framework, is discussed. Then the new colour reconnection
model, which includes beyond leading colour effects that can become important
when MPI are present, is briefly reviewed. As a last topic an introduction is
given to our implementation of photon-photon collisions. In particular photon
PDFs, required modifications for the initial state radiation algorithm and beam
remnant handling with photon beams is discussed.Comment: Contribution to proceedings of 7th International Workshop on Multiple
Partonic Interactions at the LHC, 23 - 27 November 2015, Miramare, Trieste,
Ital
Hadroproduction of open heavy flavour for PDF analyses
Due to the large masses of the charm and bottom quarks, their production cross sections are calculable within the perturbative QCD. This makes the heavy-quark mesons important observables in high-energy collisions of protons and nuclei. However, the available calculations for heavy-flavored-meson hadroproduction have been somewhat problematic in reliably describing the cross sections across the full kinematic range from zero to very high pT. This has put some question marks on the robustness of LHC heavy-flavored-meson measurements in studying the partonic structure of the colliding hadrons and nuclei. Here, we introduce SACOT-mT - a novel scheme for open heavy-flavour hadroproduction within the general-mass variable-flavour-number formalism that solves this problem. The introduced scheme is an analogue of the SACOT-χ scheme often used for deeply-inelastic scattering in global analyses of PDFs.Peer reviewe
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