scholarly journals Neutral Meson and Direct Photon Measurements with the ALICE Experiment

2019 ◽  
Vol 64 (7) ◽  
pp. 602
Author(s):  
O. Kovalenko
Keyword(s):  
Parton Distribution ◽  
Heavy Ion ◽  
Distribution Functions ◽  
Direct Photon ◽  
Neutral Meson ◽  
Parton Distribution Functions ◽  
Alice Experiment ◽  
Neutral Mesons ◽  
Wide Range ◽  
Aa Collisions

The ALICE experiment is designed to study the properties of the matter created in proton-proton and heavy-ion collisions at the LHC. Neutral mesons can be reconstructed in ALICE in a wide range of transverse momenta via two-photon decays. Neutral meson measurements in pp collisions give an opportunity to validate the NLO or NNLO pQCD calculations and to constrain the parton distribution functions and the parton fragmentation functions. Neutral meson spectra measured in pA and AA collisions allow us to test a modification of the parton distribution functions in nuclei and the parton energy loss in the hot matter created in AA collisions. The recent results from ALICE on direct photon measurements in the Pb–Pb, neutral pion and n meson productions in pp, p-Pb, and Pb–Pb collisions are presented.

Transverse momentum dependent (TMD) parton distribution functions generated in the modified DGLAP formalism based on the valence-like distributions

2017 ◽  
Vol 32 (19n20) ◽  
pp. 1750121 ◽  
Author(s):  
H. Hosseinkhani ◽  
M. Modarres ◽  
N. Olanj
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Dynamical Variable ◽  
Distribution Functions ◽  
Present Calculation ◽  
Leading Order ◽  
Parton Distribution Functions ◽  
Transverse Momentum Dependent ◽  
Longitudinal Structure Function ◽  
Wide Range

Transverse momentum dependent (TMD) parton distributions, also referred to as unintegrated parton distribution functions (UPDFs), are produced via the Kimber–Martin–Ryskin (KMR) prescription. The GJR08 set of parton distribution functions (PDFs) which are based on the valence-like distributions is used, at the leading order (LO) and the next-to-leading order (NLO) approximations, as inputs of the KMR formalism. The general and the relative behaviors of the generated TMD PDFs at LO and NLO and their ratios in a wide range of the transverse momentum values, i.e. [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are investigated. It is shown that the properties of the parent valence-like PDFs are imprinted on the daughter TMD PDFs. Imposing the angular ordering constraint (AOC) leads to the dynamical variable limits on the integrals which in turn increase the contributions from the lower scales at lower [Formula: see text]. The results are compared with our previous studies based on the MSTW2008 input PDFs and it is shown that the present calculation gives flatter TMD PDFs. Finally, a comparison of longitudinal structure function [Formula: see text] is made by using the produced TMD PDFs and those that were generated through the MSTW2008-LO PDF from our previous work and the corresponding data from H1 and ZEUS collaborations and a reasonable agreement is found.

scholarly journals Achievements and Open Issues in the Determination of Polarized Parton Distribution Functions

2016 ◽  
Vol 40 ◽  
pp. 1660016 ◽  
Author(s):  
Emanuele R. Nocera
Keyword(s):  
Parton Distribution ◽  
Polarized Light ◽  
Heavy Ion ◽  
Distribution Functions ◽  
Current Status ◽  
Relativistic Heavy Ion Collider ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
Open Issues

I review the current status of the determination of helicity-dependent, or polarized, parton distribution functions from a comprehensive analysis of experimental data in perturbative quantum chromodynamics. I illustrate the latest achievements driven by new measurements in polarized proton-proton collisions at the Relativistic Heavy Ion Collider, namely the first evidence of a sizable polarized light sea quark asymmetry and of a positive polarized gluon distribution in the proton. I discuss which are the open issues in the determination of polarized distributions, and how these may be addressed in the future by ongoing, planned and proposed experimental programs.

scholarly journals Lepton-quark fusion at Hadron colliders, precisely

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Admir Greljo ◽  
Nudžeim Selimović
Keyword(s):  
Cross Section ◽  
Parton Distribution ◽  
Opposite Sign ◽  
Production Cross ◽  
Hadron Collider ◽  
Distribution Functions ◽  
Hadron Colliders ◽  
Parton Distribution Functions ◽  
Scalar Leptoquark ◽  
Wide Range

Abstract When a TeV-scale leptoquark has a sizeable Yukawa coupling, its dominant production mechanism at hadron colliders is the partonic-level lepton-quark fusion. Even though the parton distribution functions for leptons inside the proton are minuscule, they get compensated by the resonant enhancement. We present the first computation of higher order radiative corrections to the resonant leptoquark production cross section at the Large Hadron Collider (LHC). Next-to-leading (NLO) QCD and QED corrections are similar in size but come with the opposite sign. We compute NLO K-factors for a wide range of scalar leptoquark masses, as well as, all possible combinations of quark and lepton flavors and leptoquark charges. Theoretical uncertainties due to the renormalisation and factorisation scale variations and the limited knowledge of parton distribution functions are quantified. We finally discuss how to disentangle the flavor structure of leptoquark interactions by exploiting the interplay between different production channels.

scholarly journals Hadron interactions for arbitrary energies and species, with applications to cosmic rays

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Torbjörn Sjöstrand ◽  
Marius Utheim
Keyword(s):  
Cosmic Rays ◽  
Nuclear Matter ◽  
Cross Sections ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Simplified Model ◽  
Event Generator ◽  
Parton Distribution Functions ◽  
Wide Range ◽  
Detector Material

AbstractThe Pythia event generator is used in several contexts to study hadron and lepton interactions, notably $$\mathrm{p}\mathrm{p}$$ p p and $$\mathrm{p}{\bar{\mathrm{p}}}$$ p p ¯ collisions. In this article we extend the hadronic modelling to encompass the collision of a wide range of hadrons h with either a proton or a neutron, or with a simplified model of nuclear matter. To this end we model $$h\mathrm{p}$$ h p total and partial cross sections as a function of energy, and introduce new parton distribution functions for a wide range of hadrons, as required for a proper modelling of multiparton interactions. The potential usefulness of the framework is illustrated by a simple study of the evolution of cosmic rays in the atmosphere, and by an even simpler one of shower evolution in a solid detector material. The new code will be made available for future applications.

PARTON DISTRIBUTION FUNCTIONS AND THE QCD-IMPROVED PARTON MODEL — AN OVERVIEW

1987 ◽  
Vol 02 (04) ◽  
pp. 1369-1387 ◽  
Author(s):  
Wu-Ki Tung
Keyword(s):  
Parton Distribution ◽  
Particle Production ◽  
Heavy Particle ◽  
Parton Model ◽  
Distribution Functions ◽  
Collider Physics ◽  
Parton Distribution Functions ◽  
Parton Distributions ◽  
First Order ◽  
Small X

Some non-trivial features of the QCD-improved parton model relevant to applications on heavy particle production and semi-hard (small-x) processes of interest to collider physics are reviewed. The underlying ideas are illustrated by a simple example. Limitations of the naive parton formula as well as first order corrections and subtractions to it are dis-cussed in a quantitative way. The behavior of parton distribution functions at small x and for heavy quarks are discussed. Recent work on possible impact of unconventional small-x behavior of the parton distributions on small-x physics at SSC and Tevatron are summarized. The Drell-Yan process is found to be particularly sensitive to the small x dependence of parton distributions. Measurements of this process at the Tevatron can provide powerful constraints on the expected rates of semi-hard processes at the SSC.

scholarly journals PDFFlow: Parton distribution functions on GPU

2021 ◽  
Vol 264 ◽  
pp. 107995
Author(s):  
Stefano Carrazza ◽  
Juan M. Cruz-Martinez ◽  
Marco Rossi
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions

scholarly journals Delineating the Polarized and Unpolarized Parton Structure of the Nucleon

2015 ◽  
Vol 37 ◽  
pp. 1560053
Author(s):  
Pedro Jimenez-Delgado
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Distribution Analysis ◽  
Coupling Constant ◽  
Parton Distribution Functions ◽  
Careful Treatment ◽  
Future Data ◽  
The Impact

Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.

scholarly journals ON THE $\bar{d}/\bar{u}$ ASYMMETRY AND PARTON DISTRIBUTIONS

2002 ◽  
Vol 17 (02) ◽  
pp. 269-278
Author(s):  
ALEJANDRO DALEO ◽  
CARLOS A. GARCIA CANAL ◽  
GABRIELA A. NAVARRO ◽  
RODOLFO SASSOT
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Parton Distributions ◽  
The Impact

We discuss the impact of different measurements of the [Formula: see text] asymmetry in the extraction of parametrizations of parton distribution functions.

Sign in / Sign up

Export Citation Format

Share Document