scholarly journals Trijets in $$k_\mathrm{T}$$-factorisation: matrix elements vs parton shower

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
H. Van Haevermaet ◽  
A. Van Hameren ◽  
P. Kotko ◽  
K. Kutak ◽  
P. Van Mechelen
Keyword(s):  
Cross Sections ◽  
Azimuthal Angle ◽  
Distribution Functions ◽  
Matrix Elements ◽  
Parton Distribution Functions ◽  
Initial State ◽  
Final State ◽  
Proton Proton ◽  
Shell Matrix ◽  
State Radiation

Abstract We study 3-jet event topologies in proton-proton collisions at a centre-of-mass energy of $$\sqrt{s} = 13 \mathrm{\ TeV}$$s=13TeV in a configuration, where one jet is present in the central pseudorapidity region ($$|\eta | < 2.0$$|η|<2.0) while two other jets are in a more forward (same hemisphere) area ($$|\eta | > 2.0$$|η|>2.0). We compare various parton level predictions using: collinear factorisation, $$k_\mathrm{T}$$kT-factorisation with fully off-shell matrix elements and the hybrid framework. We study the influence of different parton distribution functions, initial state radiation, final state radiation, and hadronisation. We focus on differential cross sections as a function of azimuthal angle difference between the leading dijet system and the third jet, which is found to have excellent sensitivity to the physical effects under study.

scholarly journals STRUCTURE FUNCTIONS

2009 ◽  
Vol 24 (06) ◽  
pp. 1069-1086 ◽  
Author(s):  
CRISTINEL DIACONU
Keyword(s):  
Cross Sections ◽  
Structure Functions ◽  
Distribution Functions ◽  
Final States ◽  
Parton Distribution Functions ◽  
Proton Antiproton ◽  
Proton Proton ◽  
Proton Collisions ◽  
Bjorken X ◽  
Proton Proton Collisions

Recent progress in the understanding of the nucleon is presented. The unpolarized structure functions are obtained with unprecedented precision from the combined H1 and ZEUS data and are used to extract proton parton distribution functions via NLO QCD fits. The obtained parametrization displays an improved precision, in particular at low Bjorken x, and leads to precise predictions of cross-sections for LHC phenomena. Recent data from proton–antiproton collisions at Tevatron indicate further precise constraints at large Bjorken x. The flavor content of the proton is further studied using final states with charm and beauty in DIS ep and [Formula: see text] collisions. Data from polarized DIS or proton–proton collisions are used to test the spin structure of the proton and to constrain the polarized parton distributions.

scholarly journals Measurement of the cross-section and charge asymmetry of W bosons produced in proton–proton collisions at $$\sqrt{s}=8~\text {TeV}$$ with the ATLAS detector

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
O. Abdinov ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Charge Asymmetry ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
Proton Collisions ◽  
The Cross ◽  
Proton Proton Collisions ◽  
Integrated Luminosity

Abstract This paper presents measurements of the $$W^+ \rightarrow \mu ^+\nu $$W+→μ+ν and $$W^- \rightarrow \mu ^-\nu $$W-→μ-ν cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton–proton collisions at a centre-of-mass energy of 8 $$\text {TeV}$$TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of $$20.2~\text{ fb }^{-1}$$20.2fb-1. The precision of the cross-section measurements varies between 0.8 and 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.

scholarly journals SQUARK AND GLUINO HADROPRODUCTION

2011 ◽  
Vol 26 (16) ◽  
pp. 2637-2664 ◽  
Author(s):  
WIM BEENAKKER ◽  
SILJA BRENSING ◽  
MICHAEL KRÄMER ◽  
ANNA KULESZA ◽  
ERIC LAENEN ◽  
...  
Keyword(s):  
Cross Sections ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
Proton Collisions ◽  
Numerical Predictions ◽  
Theoretical Status ◽  
Higher Order Corrections ◽  
The Impact ◽  
Proton Proton Collisions

We review the theoretical status of squark and gluino hadroproduction and provide numerical predictions for all squark and gluino pair-production processes at the Tevatron and at the LHC, with a particular emphasis on proton–proton collisions at 7 TeV. Our predictions include next-to-leading order supersymmetric QCD corrections and the resummation of soft gluon emission at next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order corrections on total cross-sections, and provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions.

Investigating the impact of the partonic structure on the description of hadronic collisions at high energies

2020 ◽  
Vol 35 (22) ◽  
pp. 2050127
Author(s):  
M. Broilo ◽  
V. P. Gonçalves ◽  
P. V. R. G. Silva
Keyword(s):  
Cross Sections ◽  
High Energy ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
High Energies ◽  
High Energy Behavior ◽  
Energy Behavior ◽  
The Impact ◽  
Hadronic Collisions

The impact of the partonic structure on the description of the hadronic cross-sections is investigated considering a multichannel eikonal model based on the Good–Walker approach. The total, elastic and single diffractive cross-sections are estimated considering different parametrizations for the parton distribution functions and the predictions are compared with the experimental data for proton–proton [Formula: see text] and antiproton–proton [Formula: see text] collisions. We show that the description of the high-energy behavior of the hadronic cross-sections is sensitive to the partonic structure.

scholarly journals Double Heavy Quark-Antiquark Pair Production in Double Parton Scattering Processes at the LHC

2017 ◽  
Vol 45 ◽  
pp. 1760065
Author(s):  
Cristiano B. Mariotto ◽  
Rafael P. da Silva
Keyword(s):  
Heavy Quark ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Proton Collision ◽  
Parton Distribution Functions ◽  
Initial State ◽  
Proton Proton ◽  
Double Parton Scattering ◽  
Proton Proton Collision ◽  
Parton Scattering

The high gluon density in the initial state of hadronic collisions at LHC energies implies that the probability of multiple parton interactions within one proton-proton collision increases. In particular, this motivates one to investigate the importance of Double Parton Scattering (DPS) processes at the LHC. In a DPS process one can have, from one proton-proton collision, two interacting partons coming from each colliding hadron. In this context, the relation between the double parton distribution functions (dPDF) and the usual parton distribution functions (PDF) is discussed, and some formulae for the DPS cross section are compared. Our results focus on the production of different final states related to two heavy quark-antiquark pairs. Those include [Formula: see text], which is called the golden channel of DPS, [Formula: see text] and [Formula: see text].

scholarly journals Higher-order corrections for tW production at high-energy hadron colliders

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Nikolaos Kidonakis ◽  
Nodoka Yamanaka
Keyword(s):  
Cross Sections ◽  
Top Quark ◽  
High Energy ◽  
Higher Order ◽  
Distribution Functions ◽  
Soft Gluon ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
Rapidity Distributions ◽  
Higher Order Corrections

Abstract We discuss cross sections for tW production in proton-proton collisions at the LHC and at higher-energy colliders with energies of up to 100 TeV. We find that, remarkably, the soft-gluon corrections are numerically dominant even at very high collider energies. We present results with soft-gluon corrections at approximate NNLO and approximate N3LO matched to complete NLO results. These higher-order corrections are large and need to be included for better theoretical accuracy and smaller scale dependence. Total cross sections as well as top-quark and W-boson transverse-momentum and rapidity distributions are presented using various recent sets of parton distribution functions.

Hard Scattering Formalism

2018 ◽  
Author(s):  
John Campbell ◽  
Joey Huston ◽  
Frank Krauss
Keyword(s):  
Form Factor ◽  
Cross Sections ◽  
W Boson ◽  
Production Cross ◽  
Distribution Functions ◽  
Hard Scattering ◽  
Parton Distribution Functions ◽  
Sudakov Form Factor ◽  
State Radiation ◽  
Characteristic Features

The hard scattering formalism is introduced, starting from a physical picture based on the idea of equivalent quanta borrowed from QED, and the notion of characteristic times. Contact to the standard QCD treatment is made after discussing the running coupling and the Altarelli–Parisi equations for the evolution of parton distribution functions, both for QED and QCD. This allows a development of a space-time picture for hard interactions in hadron collisions, integrating hard production cross sections, initial and final state radiation, hadronization, and multiple parton scattering. The production of a W boson at leading and next-to leading order in QCD is used to exemplify characteristic features of fixed-order perturbation theory, and the results are used for some first phenomenological considerations. After that, the analytic resummation of the W boson transverse momentum is introduced, giving rise to the notion of a Sudakov form factor. The probabilistic interpretation of the Sudakov form factor is used to discuss patterns in jet production in electron-positron annihilation.

scholarly journals TWO-PHOTON COLLISIONS AT LEP

2003 ◽  
Vol 18 (08) ◽  
pp. 1421-1424
Author(s):  
HSIANG-NAN LI
Keyword(s):  
Parton Distribution ◽  
Radiation Effect ◽  
Distribution Functions ◽  
Initial State Radiation ◽  
Kinematic Range ◽  
Parton Distribution Functions ◽  
Initial State ◽  
Two Photon ◽  
State Radiation ◽  
Photon Collision

We study the effect of initial-state radiation in the double-tagged process ee → ee + hadrons by introducing the parton distribution functions associated with an electron, a positron, and a photon, which satisfy a set of Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. It is observed that the radiation effect is not essential in most of the kinematic range. This observation applies to the subprocess of two-photon collision via quark exchange and via onium scattering. The deviation of the LEP data from the prediction for quark exchange at large rapidity may be regarded as a sign of new mechanism, such as the Balitskii-Fadin-Kuraev-Lipatov mechanism.

scholarly journals Charmed and bottomed hadronic cross sections from a statistical model

2020 ◽  
Vol 56 (9) ◽  
Author(s):  
Gábor Balassa ◽  
György Wolf
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Cross Sections ◽  
Heavy Quarks ◽  
Open Charm ◽  
Low Energy ◽  
Final State ◽  
Proton Antiproton ◽  
Proton Proton

Abstract In this work, we extended our statistical model with charmed and bottomed hadrons, and fit the quark creational probabilities for the heavy quarks, using low energy inclusive charmonium and bottomonium data. With the finalized fit for all the relevant types of quarks (up, down, strange, charm, bottom) at the energy range from a few GeV up to a few tens of GeV’s, the model is now considered complete. Some examples are also given for proton–proton, pion–proton, and proton–antiproton collisions with charmonium, bottomonium, and open charm hadrons in the final state.

scholarly journals Collinear expansion for color singlet cross sections

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Markus A. Ebert ◽  
Bernhard Mistlberger ◽  
Gherardo Vita
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross ◽  
Gluon Fusion ◽  
Building Blocks ◽  
Color Singlet ◽  
Final State ◽  
Beam Function ◽  
Kinematic Limit ◽  
State Radiation

Abstract We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate how this technique is used to extract universal building blocks of scattering cross section like the N-jettiness and transverse momentum beam function at NNLO.

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