Event shape dependent pion femtoscopy of proton-proton collisions at 7 TeV center-of-mass energy

doctoral thesis

• Title (croatian): Pionska femtoskopija sudara protona i protona na energiji 7 TeV u centru mase u ovisnosti o obliku događaja
• Author: Goran Simatović
• Mentor: Mirko Planinić (mentor)
• Committee member: Davor Horvatić (predsjednik povjerenstva)
• Committee member: Adam Kisiel (član povjerenstva); strani drzavljanin: Nije dostupno
• Committee member: Mirko Planinić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2015-06-08, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

We present a measurement of event shape dependent two-particle momentum space correlations for identical pions in pp collisions at √s = 7 TeV obtained by the ALICE detector. Homogeneity radii are extracted and studied as a function of pair kT = | p1T+ p2T | /2 in a wide range of event multiplicities for spherical and jet-like events. Spherical or jet-free events show a large reduction in (non-femtoscopic) background contributions to two-particle correlations which expands the kT range of the analysis and allows for a bias-free data driven femtoscopic analysis. For jet-like events the non-femtoscopic contributions are measured to be several times larger than the observed Bose-Einstein signal. By comparing ALICE measurements to PYTHIA and PHOJET generated data, a background signal removal method is developed and in-jet HBT radii are obtained. For both spherical and jet-like events, the extracted 1D homogeneity radii show a diminished kT dependence, differing to previously observed behavior in minimum bias events. After constraining the λ parameter, spherical event radii continue to have no kT dependence, which suggests a lack of radial flow, while jet-like event radii develop a clear kT and multiplicity dependence similar to the one observed in published sphericity integrated results.

Abstract (croatian)

Prikazana su mjerenja dvočestičnih korelacija impulsa za identične pione u protonskim sudarima na energiji od 7 TeV u centru mase sa ALICE detektorom. Određena je ovisnost radijusa homogenosti o srednjem transverzalnom valnom vektoru para kT = | p1T+ p2T | /2 za širok spektar multipliciteta sudara visoke i niske sferičnosti. Sferični sudari pokazuju smanjenje nefemtoskopskih doprinosa dvočestičnim korelacijama što dopušta analizu podataka, znatno šireg dosega u kT, bez potrebe za dodatnim pretpostavkama. Za sudare sa mlazovima, nefemtoskopski doprinosi sadržavaju signal višestruko veći od oni induciranih Bose-Einsteinovim korelacijama. Usporedbom mjerenja ALICE detektora te PYTHIA i PHOJET generatora razvijena je metoda uklanjanja pozadinskih signala te su izmjereni HBT radijusi unutar mlazova. Korištene su Gausova i eksponencijalna funkcija prilagodbe te su prokomentirane razlike. Izmjereni 1D radijusi homogenosti za obje ekstremne vrijednost sferičnosti pokazuju nisku ovisnost o kT. Nakon ograničavanja λ parametra, sferični događaji i dalje ne pokazuju kT ovisnost, što sugerira manjak radijalnog toka čestica, dok događaji sa mlazovima pokazuju jasnu ovisnost o kT i multiplicitetu, vrlo slično već objavljenim rezultatima.

• Keywords: ALICE; femtoscopy; HBT; transverse sphericity; quark-gluon plasma; hydrodinamic collectivity; hadronization length; proton collisions at √s = 7 TeV
• Keywords (croatian): ALICE; femtoskopija; HBT; transverzalna sferičnost; kvark gluonska plazma; hidrodinamička kolektivnost; hadronizacijska duljina; protonski sudari sa √s = 7 TeV
• Language: english
• URN:NBN: urn:nbn:hr:217:411364
• Study programme: Title: Physics; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
• Type of resource: Text
• Extent: 143 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-08-22 09:09:47