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[{"key": "dc.contributor.author", "value": "Pohjoisaho, Esko", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2012-12-14T15:19:28Z", "language": "", "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2012-12-14T15:19:28Z", "language": "", "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2012", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.other", "value": "oai:jykdok.linneanet.fi:1240515", "language": null, "element": "identifier", "qualifier": "other", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/40578", "language": "", "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "In this Master's Thesis an analysis of proton proton data measured by the ALICE (A Large Ion Collider Experiment) Collaboration at center-of-mass energies 7 TeV and 2.76 TeV is presented. The ALICE detector is located at the LHC (Large Hadron Collider) at CERN, Switzerland. The goal of this thesis was to study whether the isolation requirement can increase the sensitivity of the xT spectra (xT=2pT/sqrt(s)) to higher-twist (HT) processes. In HT processes the outgoing hadron is produced directly in the hard subprocess, rather than in the fragmentation process described by the leading-twist (LT) processes in the perturbative QCD picture. Higher-twist processes are mainly low pT phenomena, causing steeper fall-off of the cross section distributions with respect to xT. \r\n\r\nIt has been suggested that the production of isolated particles would be enhanced by the HT processes. An xT analysis was done for isolated particles to see whether a significant increase of the extracted exponent n can be observed. This also raised motivation to study the systematic effects caused by the isolation criteria such as the isolation cone size and background pT cut in the cone. The results of the ALICE data analysis were compared to PYTHIA Monte Carlo (MC) event generator. It was observed that the isolation increased the n in both real data and PYTHIA.\r\n\r\nA simple toy Monte Carlo fragmentation model was made to study the kinematic effects resulting from the isolation cut. The increase of n was observed also in the toy model, indicating a kinematic bias related to the isolation criteria. It was demonstrated that isolated particles had larger values of z, the momentum ratio of the hadron to its parent parton. The toy MC model suggested that the increase of n is due to the combination of the steepness of the parton momentum distribution and the magnitude of the mean z.\r\n\r\nIn order to study the higher-twist phenomena in real data, one would need to separate the trivial increase of n caused by the systematic effects from the HT signal. To disentangle the two, the magnitude of the Delta n resulting from the isolation itself should be calculated with a more realistic model like the NLO pQCD.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "T\u00e4ss\u00e4 pro gradu-ty\u00f6ss\u00e4 esitell\u00e4\u00e4n data-analyysi CERNin ALICE-kollaboraation mittaamasta protoni--protoni-datasta t\u00f6rm\u00e4ysenergioilla sqrt(s) = 7 TeV ja 2.76 TeV. Ty\u00f6n t\u00e4rkein p\u00e4\u00e4m\u00e4\u00e4r\u00e4 oli tutkia, onko ns. \"higher-twist\" (HT)-prosessien l\u00e4sn\u00e4olo korostunut datassa, joka on mitattu ainoastaan erist\u00e4ytyneist\u00e4 hadroneista inklusiivisten varattujen hadronien sijaan.\r\n\r\nH\u00e4iri\u00f6teoreettisessa QCD-kuvassa hadronit muodostuvat, kun t\u00f6rm\u00e4yksest\u00e4 ulostulevat partonit hadronisoituvat fragmentaation kautta. Hadronituoton todenn\u00e4k\u00f6isyyksi\u00e4 voidaan laskea ns. kollineaarifaktorisaatiolla, jonka kuvaamia prosesseja kutsutaan \"leading-twist\" (LT)-prosesseiksi. HT-prosesseissa t\u00f6rm\u00e4yksest\u00e4 ulostuleva hadroni muodostuu kuitenkin suoraan kovassa kvarkkien tai gluonien vuorovaikutuksessa, jolloin on perusteltua odottaa ett\u00e4 hadroninen aktiviteetti hiukkasen ymp\u00e4rill\u00e4 on v\u00e4h\u00e4isemp\u00e4\u00e4 kuin LT-tapauksessa. Koska LT-prosessit eiv\u00e4t yksist\u00e4\u00e4n riit\u00e4 selitt\u00e4m\u00e4\u00e4n kokeellisesti mitattuja tuloksia, on HT-prosessien osuuden kokeellinen mittaaminen ja teoreettinen kuvaaminen er\u00e4s hiukkasfysiikan nykyisist\u00e4 tutkimuskohteista.\r\n\r\nSe, onko hiukkanen erist\u00e4ytynyt vai ei, voidaan selvitt\u00e4\u00e4 kuvittelemalla tutkittavan hiukkasen ymp\u00e4rille kartio ja laskemalla yhteen kartiossa olevien hiukkasten liikem\u00e4\u00e4r\u00e4t. Mik\u00e4li t\u00e4m\u00e4 summa ylitt\u00e4\u00e4 ennalta asetetun erist\u00e4misrajan, voidaan hiukkanen julistaa erist\u00e4ytyneeksi. Erist\u00e4misen odotetaan vaimentavan LT-prosesseista per\u00e4isin olevia hiukkasia, jolloin lopputuloksena HT-prosessien osuus olisi korostunut.\r\n\r\nHigher-twist-prosessit ilmenev\u00e4t pienen poikittaisliikem\u00e4\u00e4r\u00e4 pT:n alueella, joten niiden l\u00e4sn\u00e4olon odotetaan aiheuttavan vaikutusalaspektrien jyrkkenemist\u00e4, ja sen seurauksena spektrien muodolle suuremman potenssilain eksponentin n arvoja. T\u00e4ss\u00e4 ty\u00f6ss\u00e4 mitattiin n-eksponentti xT=2pT/sqrt(s):n funktiona sek\u00e4 ALICE-datalle ett\u00e4 PYTHIA-t\u00f6rm\u00e4ysgeneraattorin Monte Carlo-simuloidulle datalle. Molemmissa tapauksissa havaittiin ett\u00e4 n oli suurempi erist\u00e4ytyneill\u00e4 hadroneilla kuin inklusiivisilla hadroneilla, kuten oli ennustettu.\r\n\r\nJotta saataisiin selville johtuiko eksponentin kasvu HT-prosesseista vai jostain muusta erist\u00e4miseen liittyneest\u00e4 systemaattisesta ilmi\u00f6st\u00e4, analyysi toistettiin viel\u00e4 yksinkertaiselle \"lelumallille\" hadronijakaumasta. T\u00e4ss\u00e4 mallissa oletettiin partonille liikem\u00e4\u00e4r\u00e4 potenssilakijakaumasta, josta luotiin hadronijakauma k\u00e4ytt\u00e4m\u00e4ll\u00e4 eksponenttimuotoista fragmentaatiofunktiota. T\u00e4ll\u00e4 haluttiin simuloida mahdollisimman yksinkertaista hadronijakaumaa, joka kuitenkin olisi mahdollisimman l\u00e4hell\u00e4 h\u00e4iri\u00f6teoreettista QCD-kuvaa. Etuna oli se, ett\u00e4 mallin kaikki parametrit tunnettiin, ja ett\u00e4 voitiin varmistua, ettei HT-prosesseja ollut l\u00e4sn\u00e4 mallissa. Eksponentti n kasvoi my\u00f6s t\u00e4ss\u00e4 mallissa, oleellisesti saman verran kuin oikean datan ja PYTHIA:n tapauksessakin.\r\n\r\nHavaittiin, ett\u00e4 erist\u00e4ytyneet hiukkaset poimivat fragmentaatiofunktiosta systemaattisesti suurempia z-arvoja kuin kaikki hiukkaset keskim\u00e4\u00e4rin. Muuttuja z kuvaa hadronin liikem\u00e4\u00e4r\u00e4n suhdetta siihen partoniin, josta kyseinen hadroni muodostui. Lis\u00e4ksi todettiin, ett\u00e4 eksponentin kasvu riippui my\u00f6s partonijakauman muodosta, joka riippui mallinnettavasta t\u00f6rm\u00e4ysenergiasta. Eksponentin n laskemiseen tarvitaan kahdella eri t\u00f6rm\u00e4ysenergialla tuotettuja jakaumia, mutta eri energioista seurasi kuitenkin erilainen todenn\u00e4k\u00f6isyys tuottaa erist\u00e4ytynyt hadroni, ja n\u00e4iden todenn\u00e4k\u00f6isyyksien ero osaltaan aiheutti n:n kasvamista.\r\n\r\nHT-prosesseja ei ole t\u00e4ysim\u00e4\u00e4r\u00e4isesti ohjelmoitu PYTHIA-simulaatioon, ja siit\u00e4 huolimatta joillain xT-alueilla erist\u00e4ytyneiden hadronien n-eksponentti oli jopa suurempi PYTHIA-simulaatiossa kuin ALICE-datassa. Sek\u00e4 t\u00e4m\u00e4n havainnon ett\u00e4 yksinkertaisen lelumallin tuloksien nojalla ty\u00f6n p\u00e4\u00e4tulos on, ett\u00e4 HT-prosesseja tutkiessa tulee ottaa huomioon eksponentin n kasvu, joka johtuu pelk\u00e4st\u00e4 erist\u00e4misehdosta ilman HT-prosessejakin. T\u00e4m\u00e4n kinematiikan muutoksen aiheuttaman eksponentin kasvun suuruus tulisi laskea tarkemmin esimerkiksi NLO pQCD-teorian avulla, jotta voitaisiin erottaa varsinaisten HT-prosessien osuus tuloksissa.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted using Plone Publishing form by Esko Pohjoisaho (esheospo) on 2012-12-14 15:19:26.809383. Form: Pro gradu -lomake (1 tekij\u00e4) (https://kirjasto.jyu.fi/julkaisut/julkaisulomakkeet/pro-gradu-lomake-1-tekijae). JyX data:", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by jyx lomake-julkaisija (jyx-julkaisija@noreply.fi) on 2012-12-14T15:19:28Z\r\nNo. of bitstreams: 2\r\nURN:NBN:fi:jyu-201212143349.pdf: 9745738 bytes, checksum: d03579ceb362f5302c82051a2baee506 (MD5)\r\nlicense.html: 5020 bytes, checksum: 0684aa50079e3a3f7d36d397db6a072f (MD5)", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2012-12-14T15:19:28Z (GMT). No. of bitstreams: 2\r\nURN:NBN:fi:jyu-201212143349.pdf: 9745738 bytes, checksum: d03579ceb362f5302c82051a2baee506 (MD5)\r\nlicense.html: 5020 bytes, checksum: 0684aa50079e3a3f7d36d397db6a072f (MD5)\r\n Previous issue date: 2012", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.format.extent", "value": "81 sivua", "language": null, "element": "format", "qualifier": "extent", "schema": "dc"}, {"key": "dc.format.mimetype", "value": "application/pdf", "language": null, "element": "format", "qualifier": "mimetype", "schema": "dc"}, {"key": "dc.language.iso", "value": "eng", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": "en", "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.subject.other", "value": "ALICE", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "isolation", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "proton-proton collisions", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.title", "value": "Study of xT scaling in proton-proton collisions measured by the ALICE experiment", "language": null, "element": "title", "qualifier": null, "schema": "dc"}, {"key": "dc.type", "value": "master thesis", "language": null, "element": "type", "qualifier": null, "schema": "dc"}, {"key": "dc.identifier.urn", "value": "URN:NBN:fi:jyu-201212143349", "language": null, "element": "identifier", "qualifier": "urn", "schema": "dc"}, {"key": "dc.type.dcmitype", "value": "Text", "language": "en", "element": "type", "qualifier": "dcmitype", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Pro gradu -tutkielma", "language": "fi", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Master\u2019s thesis", "language": "en", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Matemaattis-luonnontieteellinen tiedekunta", "language": "fi", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Faculty of Sciences", "language": "en", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Fysiikan laitos", "language": "fi", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Department of Physics", "language": "en", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "University of Jyv\u00e4skyl\u00e4", "language": "en", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "Jyv\u00e4skyl\u00e4n yliopisto", "language": "fi", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Fysiikka", "language": "fi", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Physics", "language": "en", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.date.updated", "value": "2012-12-14T15:19:28Z", "language": "", "element": "date", "qualifier": "updated", "schema": "dc"}, {"key": "dc.type.coar", "value": "http://purl.org/coar/resource_type/c_bdcc", "language": null, "element": "type", "qualifier": "coar", "schema": "dc"}, {"key": "dc.rights.accesslevel", "value": "openAccess", "language": "fi", "element": "rights", "qualifier": "accesslevel", "schema": "dc"}, {"key": "dc.type.publication", "value": "masterThesis", "language": null, "element": "type", "qualifier": "publication", "schema": "dc"}, {"key": "dc.subject.oppiainekoodi", "value": "4021", "language": null, "element": "subject", "qualifier": "oppiainekoodi", "schema": "dc"}, {"key": "dc.subject.yso", "value": "fysiikka", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "protonit", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.format.content", "value": "fulltext", "language": null, "element": "format", "qualifier": "content", "schema": "dc"}, {"key": "dc.rights.url", "value": "https://rightsstatements.org/page/InC/1.0/", "language": null, "element": "rights", "qualifier": "url", "schema": "dc"}, {"key": "dc.type.okm", "value": "G2", "language": null, "element": "type", "qualifier": "okm", "schema": "dc"}]
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