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 A MODEL CONSTRUCTION OF SELF-SIMILARITY BASED DOUBLE PARTON DISTRIBUTION FUNCTIONS FOR PROTON–PROTON COLLISION AT LHC

2013 ◽  
Vol 28 (17) ◽  
pp. 1350079 ◽  
Author(s):  
D. K. CHOUDHURY ◽  
AKBARI JAHAN
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Model Construction ◽  
Proton Collision ◽  
Self Similarity ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
Construction Of Self ◽  
Small X ◽  
Proton Proton Collision

We construct a model for double parton distribution functions (dPDFs) based on the notion of self-similarity, pursued earlier for small x physics at HERA. The most general form of dPDFs contains total 13 parameters to be fitted from data of proton–proton collision at LHC. It is shown that the constructed dPDF does not factorize into two single PDFs in conformity with QCD expectation, and it satisfies the condition that at the kinematic boundary x1+x2 = 1 (where x1 and x2 are the longitudinal fractional momenta of two partons), the dPDF vanishes.

Color Entanglement in Hadronic Processes for Transverse Momentum Dependent Parton Distribution Functions

2015 ◽  
Vol 37 ◽  
pp. 1560022
Author(s):  
M. G. A. Buffing ◽  
P. J. Mulders
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Initial State ◽  
Color Flow ◽  
Transverse Momentum Dependent ◽  
Gauge Link ◽  
Azimuthal Asymmetries ◽  
Different Parts

In the description of protons, we go beyond the ordinary collinear parton distribution functions (PDFs), by including transverse momentum dependent PDFs (TMDs). As such, we become sensitive to polarization modes of the partons and protons that one cannot probe without accounting for transverse momenta of partons, in particular when looking at azimuthal asymmetries. Hadronic processes require the inclusion of gluon contributions forming the gauge links, which are path-ordered exponentials tracing the color flow. In processes with two hadrons in the initial state, such as Drell-Yan (DY), the gauge links from different parts of the process get entangled. We show that in color disentangling this gauge link structure, one becomes sensitive to this color flow. After disentanglement, particular combinations of TMDs will require a different numerical color factor than one naively might have expected. Such color factors will even play a role for azimuthal asymmetries in the simplest hadronic processes such as DY.

scholarly journals Measurement of the W boson mass

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
◽  
R. Aaij ◽  
A. S. W. Abdelmotteleb ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
...  
Keyword(s):  
Distribution Function ◽  
Parton Distribution ◽  
W Boson ◽  
Parton Distribution Function ◽  
Boson Mass ◽  
Proton Collision ◽  
Proton Proton ◽  
Lhcb Experiment ◽  
Proton Proton Collision ◽  
Pm 10

Abstract The W boson mass is measured using proton-proton collision data at $$ \sqrt{s} $$ s = 13 TeV corresponding to an integrated luminosity of 1.7 fb−1 recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q/pT distribution of a sample of W → μν decays and the ϕ* distribution of a sample of Z → μμ decays the W boson mass is determined to be$$ {m}_w=80354\pm {23}_{\mathrm{stat}}\pm {10}_{\mathrm{exp}}\pm {17}_{\mathrm{theory}}\pm {9}_{\mathrm{PDF}}\mathrm{MeV}, $$ m w = 80354 ± 23 stat ± 10 exp ± 17 theory ± 9 PDF MeV , where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.

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 Production of massless charm jets in pp collisions at next-to-leading order of QCD

2015 ◽  
Vol 30 (18n19) ◽  
pp. 1550111 ◽  
Author(s):  
Isabella Bierenbaum ◽  
Gustav Kramer
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Inclusive Production ◽  
Leading Order ◽  
Parton Distribution Functions ◽  
Proton Proton ◽  
Proton Collisions ◽  
Intrinsic Charm ◽  
Proton Proton Collisions

We present predictions for the inclusive production of charm jets in proton–proton collisions at 7 TeV. Several CTEQ parton distribution functions (PDFs) of the CTEQ6.6M type are employed, where two of the CTEQ6.6 PDFs have intrinsic charm. At large enough jet transverse momentum and large jet rapidity, the intrinsic charm content can be tested.

scholarly journals Study of Z boson plus jets events using variables sensitive to double-parton scattering in pp collisions at 13 TeV

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
◽  
A. Tumasyan ◽  
W. Adam ◽  
J. W. Andrejkovic ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Cross Sections ◽  
Z Boson ◽  
Proton Collision ◽  
Proton Proton ◽  
Double Parton Scattering ◽  
Important Input ◽  
Momentum Imbalance ◽  
Simulation Parameters ◽  
Parton Scattering

Abstract Double-parton scattering is investigated using events with a Z boson and jets. The Z boson is reconstructed using only the dimuon channel. The measurements are performed with proton-proton collision data recorded by the CMS experiment at the LHC at $$ \sqrt{s} $$ s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1 collected in the year 2016. Differential cross sections of Z+ ≥1 jet and Z+ ≥2 jets are measured with transverse momentum of the jets above 20 GeV and pseudorapidity |η| < 2.4. Several distributions with sensitivity to double-parton scattering effects are measured as functions of the angle and the transverse momentum imbalance between the Z boson and the jets. The measured distributions are compared with predictions from several event generators with different hadronization models and different parameter settings for multiparton interactions. The measured distributions show a dependence on the hadronization and multiparton interaction simulation parameters, and are important input for future improvements of the simulations.

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