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# Λ and K$$^0$$$$_S$$ production in Pb-Pb and pp collisions with ALICE at the LHC

Hanratty, Luke David (2014)
Ph.D. thesis, University of Birmingham.

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## Abstract

In this work, the transverse momentum spectra of Λ and K$$^0$$$$_S$$ measured with the ALICE experiment at the LHC are discussed. Measurements are presented for colliding systems of protons, at centre of mass energies 2.76 TeV and 7 TeV, and for lead ions at a centre of mass energy of 2.76 TeV per nucleon.

The spectra are discussed within a theoretical framework of a thermally equilibrated, hydrodynamically evolving system, which serves to explain the shape of the spectra for p$$_T$$ < 2 GeV/c. For p$$_T$$ > 6 GeV/c jet quenching is evident, but no evidence of particle species dependance in jet quenching is observed.

The Λ/K$$^0$$$$_S$$ ratio shows an enhancement for 2 < p$$_T$$ < 6 GeV/c, peaking at 1.5 for the 5% most central Pb–Pb collisions compared to 0.6 for pp. This is discussed in terms of a coalescence model. It cannot be explained purely by enhanced baryon production, but must also involve a redistribution of particles within p$$_T$$. This supports the hydrodynamical picture of hadron production. A brief comparison to the results presently available in p–Pb collisions at the LHC is also given.

Type of Work: Ph.D. thesis. Jones, Peter G. and Barnby, Lee Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Physics and Astronomy QB AstronomyQC Physics University of Birmingham 5311
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