Search results for "parton"
showing 10 items of 552 documents
"Table 171" of "Measurements of $t\bar{t}$ differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in $pp$ col…
2019
Statistical correlation matrix for the absolute differential cross-section of all 15 variables at parton level. The observables are arranged as follows: random top pT - ${p_{{T}}}^{t}$ [bins 1-8], random top rapidity - $|y^{t}|$ [bins 9-16], leading top pT - ${p_{{T}}}^{t,1}$ [bins 17-24], leading top rapidity - $|y^{t,1}|$ [bins 25-32], subleading top pT - ${p_{{T}}}^{t,2}$ [bins 33-39], subleading top rapidity - $|y^{t,2}|$ [bins 40-46], ttbar mass - $m^{t\bar{t}}$ [bins 48-57], ttbar pT - ${p_{{T}}}^{t\bar{t}}$ [bins 58-63], ttbar rapidity - $|y^{t\bar{t}}|$ [bins 66-71], chi ttbar ${\chi}^{t\bar{t}}$ - [bins 74-80], delta phi ttbar - ${\Delta\phi}(t_1,t_2)$ [bins 81-84], ttbar out of pl…
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations
2015
Laskettaessa suuren liikemäärävaihdon hadronisten prosessien sirontatodennäköisyyksiä häiriöteoreettisesti kvanttiväridynamiikan (QCD) avulla joudumme parametrisoimaan tietämättömyyttämme hadronien rakenteesta nk. partonijakaumafunktioihin (PDF). Vaikka nämä partonijakaumat eivät ole johdettavissa häiriöteoreettisesti, voidaan niiden skaalaevoluutiota määrittävät Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) -yhtälöt löytää analyyttisellä laskulla. Tarkastelemalla syvästi epäelastista leptoni–hadroni sirontaa (DIS) näemme massattoman QCD:n tuottavan kollineaarisia divergenssejä. Näiden divergenttien termien sisällyttäminen partonijakaumien määritelmään johtaa fysikaalisesti äärellisiin…
Study of very forward energy and its correlation with particle production at midrapidity in pp and p-Pb collisions at the LHC
2022
Journal of high energy physics 08(8), 86 (2022). doi:10.1007/JHEP08(2022)086
Orbital angular momentum parton distributions in quark models
1999
At the low energy, {\sl hadronic}, scale we calculate Orbital Angular Momentum (OAM) twist-two parton distributions for the relativistic MIT bag model and for non-relativistic quark models. We reach the scale of the data by leading order evolution in perturbative QCD. We confirm that the contribution of quarks and gluons OAM to the nucleon spin grows with $Q^2$, and it can be relevant at the experimental scale, even if it is negligible at the hadronic scale, irrespective of the model used. The sign and shape of the quark OAM distribution at high $Q^2$ may depend strongly on the relative size of the OAM and spin distributions at the hadronic scale. Sizeable quark OAM distributions at the had…
Review of proton and nuclear shape fluctuations at high energy
2020
Determining the inner structure of protons and nuclei in terms of their fundamental constituents has been one of the main tasks of high energy nuclear and particle physics experiments. This quest started as a mapping of the (average) parton densities as a function of longitudinal momentum fraction and resolution scale. Recently, the field has progressed to more differential imaging, where one important development is the description of the event-by-event quantum fluctuations in the wave function of the colliding hadron. In this Review, recent developments on the extraction of proton and nuclear transverse geometry with event-by-event fluctuations from collider experiments at high energy is …
Suora fotonituotto suurienergiaisissa ydintörmäyksissä sähkömagneettisen ja vahvan vuorovaikutuksen kertaluvussa O(α _em α_S)
2013
Eikonal minijet model for proton-proton collisions
2017
Tässä tutkielmassa johdettiin minijettimalli suurienergiaisille protoni-protoni -törmäyksille eikonaaliformalismissa. Mallia testattiin numeerisen laskennan keinoin kokeellisilla tuloksilla protoni-protoni -törmäyksien elastisista, epäelastisista ja kokonaisvaikutusaloista keskeisliikemääräkoordinaatiston energiaskaalassa sqrt(s)=0.1..100 TeV. Myös viimeisimpiä CERN-LHC -kiihdyttimen mittaustuloksia tarkasteltiin. Numeerisen analyysin yhtenä osana tutkittiin myös yhden efektiivisen aliprosessin approksimaatiota, joka osoittautui tutkituilla energioilla hyvin tarkaksi. Lisäksi tarkasteltiin moninkertaisen kaksijettituoton roolia protoni-protoni -törmäysten epäelastisessa vaikutusalassa. An e…
Minijet initial state of heavy-ion collisions from next-to-leading order perturbative QCD
2014
Jet fragmentation transverse momentum distributions in pp and p-Pb collisions at √s, √sNN = 5.02 TeV
2021
Jet fragmentation transverse momentum (jT) distributions are measured in proton-proton (pp) and proton-lead (p-Pb) collisions at √sNN = 5.02 TeV with the ALICE experiment at the LHC. Jets are reconstructed with the ALICE tracking detectors and electromagnetic calorimeter using the anti-kT algorithm with resolution parameter R = 0.4 in the pseudorapidity range |η| < 0.25. The jT values are calculated for charged particles inside a fixed cone with a radius R = 0.4 around the reconstructed jet axis. The measured jT distributions are compared with a variety of parton-shower models. Herwig and Pythia 8 based models describe the data well for the higher jT region, while they underestimate the low…
Charged jet cross sections and properties in proton-proton collisions at $\sqrt{s}=7$ TeV
2015
The differential charged jet cross sections, jet fragmentation distributions, and jet shapes are measured in minimum bias proton-proton collisions at centre-of-mass energy $\sqrt{s}=7$ TeV using the ALICE detector at the LHC. Jets are reconstructed from charged particle momenta in the mid-rapidity region using the sequential recombination $k_{\rm T}$ and anti-$k_{\rm T}$ as well as the SISCone jet finding algorithms with several resolution parameters in the range $R=0.2$ to $0.6$. Differential jet production cross sections measured with the three jet finders are in agreement in the transverse momentum ($p_{\rm T}$) interval $20<p_{\rm T}^{\rm jet,ch}<100$ GeV/$c$. They are also consistent w…