K0 S meson production in inelastic P+P Interactions at 158 GeV/c beam momentum measured by NA61/SHINE at the CERN SPS

[M. Ćirković]

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Fizika - Eksperimentalna fizika visokih energija / Physics Research area: Experimental high energy physics

NA61/SHINE je multifunkcionalan eksperiment sa fiksnom metom na CERN-ovom Super Proton Sinhrotron ubrzavaˇcu. Glavni ciljevi NA61/SHINE eksperimenta su otkri´ce kritiˇcne taˇcke jakih interakcija i izuˇcavanje svojstva zarobljenosti kvarkova i faznog prelaska hadronskog gasa u kvark-gluon pla- zmu (QGP). Radi ostvarivanja ovih ciljeva izuˇcava se produkcija hadrona u jezgro+jezgro, proton+proton i proton+jezgro interakcijama u zavisnosti od energije projektila i veliˇcine jezgara koja uˇcestvuju u reakciji, sa posebnom paˇznjom na prouˇcavanje produkcije “stranih” hadrona. Jedan od predvid¯enih signala nastanka QGP jeste pove´canje stranosti u sudarima jezgro+jezgro u odnosu na sudare proton+proton na identiˇcnim energijama. Analiza produkcije K0 S mezona u proton+proton sudarima nam pomaˇze u boljem razumevanju ove pojave. Kako je reˇc o elektro-neutralnoj ˇcestici, njena detekcija nije jednostavna. Detekcija K0 S mezona je mogu´ca samo analizom njenih produkata raspada koji su naelektrisani. Glavni cilj ove teze je izraˇcunavanje K0 S -prinosa i K0 S multipliciteta u pro- ton+proton sudarima na energiji od 158 GeV-a na podacima kolektovanim pomo´cu NA61/SHINE eksperimenta tokom 2009., 2010. i 2011. godine. U re- zultatima teze se nalaze i izraˇcunati spektri ( d2n dydpT ) i ( dn dy ), zatim zavisnost inverznog parametra nagiba u funkciji rapiditeta, kao i ukupni K0 S multiplici- tet ekstrapoliran na 4π geometriju.

NA61/SHINE is a multi-purpose fixed-target experiment at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE strong-inter- action programme are to discover the critical point of strongly interacting matter as well as study the properties of the onset of deconfinement and tran- sition between hadronic matter and QGP. In order to reach these goals, a study of hadron production properties is performed in nucleus+nucleus, pro- ton+proton and proton+nucleus interactions as a function of collision energy and size of the colliding nuclei with a special effort on a study the properties of the strange-hadron production. One of the key experimental evidence of existing the QGP is strangeness enhancement. The study of K0 S production in proton+proton interaction help us to understand better strangeness enhancement. K0 S is electrically neutral particle, so it is not easy to detect it directly. It’s detection is possible only via analysing it’s charged decay products. The main aim of this thesis is to calculate K0 S -yields and K0 S mean mul- tiplicity for proton+proton interactions at 158 GeV/c with the use of the NA61/SHINE data acquired in 2009, 2010 and 2011. The procedure was em- ployed in order to calculate double-differential spectra ( d2n dydpT ), single differen- tial distribution ( dn dy ), and inverse slope parameter T dependence on y, as well as mean K0 S multiplicity extrapolated to 4π for proton+proton at 158 GeV/c

NA61/SHINE, CERN, jake interakcije, kvark-gluon plazma, stra- nost, K0 S .

NA61/SHINE, CERN, strong interactions, quark-gluon plasma, strangeness, K0 S .

539.120.812(043.3)

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