Λ and K\(^0\)\(_S\) production in Pb-Pb and pp collisions with ALICE at the LHC

Hanratty, Luke David (2014). Λ and K\(^0\)\(_S\) production in Pb-Pb and pp collisions with ALICE at the LHC. University of Birmingham. Ph.D.

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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:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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