PARTON DISTRIBUTION FUNCTIONS AND JET CROSS SECTIONS AT HERA

2007 ◽  
Author(s):  
E. TASSI ◽  
Keyword(s):  
Cross Sections ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Jet Cross Sections

scholarly journals Determination of αs in NNLO QCD using H1 jet cross section measurements

2019 ◽  
Vol 206 ◽  
pp. 01002
Author(s):  
Vladimir Chekelian
Keyword(s):  
Strong Coupling ◽  
Cross Section ◽  
Cross Sections ◽  
Neutral Current ◽  
Distribution Functions ◽  
Boson Mass ◽  
Parton Distribution Functions ◽  
Inclusive Jet ◽  
Using Data ◽  
Jet Cross Sections

Measurements of jet cross sections in neutral current deep-inelastic scattering (NC DIS) using data taken with the H1 detector at HERA are accomplished by the precision measurement of double-differential inclusive jet, dijet and trijet cross sections at low photon virtualities 5.5 < Q2 < 80 GeV2, and by extending previous inclusive jet measurements in the range 150 < Q2 < 15000 GeV2 to low transverse jet momenta 5 < PT < 7 GeV. The strong coupling constant at the Z-boson mass, αs(mZ), is determined in next-to-next-to-leading order (NNLO) QCD using H1 inclusive jet and dijet cross section measurements. Complementary, αs(mZ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with the QCD expectations.

scholarly journals Measurement of $$W^\pm $$ boson production in Pb+Pb collisions at $$\sqrt{s_{\mathrm{NN}}} = 5.02~\text {Te}\text {V}$$ with the ATLAS detector

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Cross Sections ◽  
Parton Distribution ◽  
Production Cross ◽  
Charge Asymmetry ◽  
Distribution Functions ◽  
Boson Production ◽  
Parton Distribution Functions ◽  
Absolute Value ◽  
The Absolute ◽  
Thickness Function

AbstractA measurement of $$W^\pm $$W± boson production in Pb+Pb collisions at $$\sqrt{s_\mathrm {NN}} = 5.02~\text {Te}\text {V}$$sNN=5.02Te is reported using data recorded by the ATLAS experiment at the LHC in 2015, corresponding to a total integrated luminosity of $$0.49\;\mathrm {nb^{-1}}$$0.49nb-1. The $$W^\pm $$W± bosons are reconstructed in the electron or muon leptonic decay channels. Production yields of leptonically decaying $$W^\pm $$W± bosons, normalised by the total number of minimum-bias events and the nuclear thickness function, are measured within a fiducial region defined by the detector acceptance and the main kinematic requirements. These normalised yields are measured separately for $$W^+$$W+ and $$W^-$$W- bosons, and are presented as a function of the absolute value of pseudorapidity of the charged lepton and of the collision centrality. The lepton charge asymmetry is also measured as a function of the absolute value of lepton pseudorapidity. In addition, nuclear modification factors are calculated using the $$W^\pm $$W± boson production cross-sections measured in pp collisions. The results are compared with predictions based on next-to-leading-order calculations with CT14 parton distribution functions as well as with predictions obtained with the EPPS16 and nCTEQ15 nuclear parton distribution functions. No dependence of normalised production yields on centrality and a good agreement with predictions are observed for mid-central and central collisions. For peripheral collisions, the data agree with predictions within 1.7 (0.9) standard deviations for $$W^-$$W- ($$W^+$$W+) bosons.

scholarly journals Applications of pT-xR Variables in Describing Inclusive Cross Sections at the LHC

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 196
Author(s):  
Frank Taylor
Keyword(s):  
Cross Sections ◽  
Single Particle ◽  
Power Laws ◽  
Inclusive Cross Section ◽  
Heavy Ion ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Heavy Ion Physics ◽  
Inclusive Jets ◽  
Jet Cross Sections

Invariant inclusive single-particle/jet cross sections in p–p collisions can be factorized in terms of two separable dependences, a [pT−s] sector and an [xR−pT−s] sector. Here, we extend our earlier work by analyzing more extensive data to explore various s-dependent attributes and other systematics of inclusive jet, photon and single particle reactions. Approximate power laws in s,pT and xR are found. Physical arguments are given which relate observations to the underlying physics of parton–parton hard scattering and the parton distribution functions in the proton. We show that the A(s,pT) function, introduced in our earlier publication to describe the pT dependence of the inclusive cross section, is directly related to the underlying hard parton–parton scattering for jet production, with little influence from soft physics. In addition to the A-function, we introduce another function, the F(s,xR) function that obeys radial scaling for inclusive jets and offers another test of the underlying parton physics. An application to heavy ion physics is given, where we use our variables to determine the transparency of cold nuclear matter to penetrating heavy mesons through the lead nucleus.

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.

scholarly journals Can $$ \overline{\mathrm{MS}} $$ parton distributions be negative?

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Alessandro Candido ◽  
Stefano Forte ◽  
Felix Hekhorn
Keyword(s):  
Strong Coupling ◽  
Cross Sections ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Leading Order ◽  
Parton Distribution Functions ◽  
Parton Distributions ◽  
Factorization Scheme ◽  
Perturbative Regime

Abstract It is common lore that Parton Distribution Functions (PDFs) in the $$ \overline{\mathrm{MS}} $$ MS ¯ factorization scheme can become negative beyond leading order due to the collinear subtraction which is needed in order to define partonic cross sections. We show that this is in fact not the case and next-to-leading order (NLO) $$ \overline{\mathrm{MS}} $$ MS ¯ PDFs are actually positive in the perturbative regime. In order to prove this, we modify the subtraction prescription, and perform the collinear subtraction in such a way that partonic cross sections remain positive. This defines a factorization scheme in which PDFs are positive. We then show that positivity of the PDFs is preserved when transforming from this scheme to $$ \overline{\mathrm{MS}} $$ MS ¯ , provided only the strong coupling is in the perturbative regime, such that the NLO scheme change is smaller than the LO term.

Review of Parton Distributions and Implications for the Tevatron and the LHC

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 205-208
Author(s):  
JOEY HUSTON
Keyword(s):  
Cross Sections ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Parton Distributions ◽  
Pedagogical Guide

This talk is intended to serve as a pedagogical guide on the determination of, the proper use of, and the uncertainties of parton distribution functions and their impact on physics cross sections at the Tevatron and LHC. A longer writeup of this talk is available at .

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