In this master’s thesis the width of the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> meson is studied as a function of temperature. We consider a background medium consisting of a pion gas and assume a vanishing net baryon chemical potential. The width is obtained in the framework of large <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?N_%7Bc%7D" /> chiral perturbation theory and we consider terms up to next-to-leading order in the effective Lagrangian. We use a low-density approximation to calculate the width increase due to scattering with pions from the heat bath. The results suggest that the in-medium width for the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> may become of considerable size: at a temperature <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?T%5Capprox%2075" /> MeV we find a width increase of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5CDelta%5CGamma%5Capprox%203-4" /> MeV, comparable to the inverse lifetime of the fireball created in a heavy-ion collision. The <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> is of particular interested since it is intimately connected to the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?U(1)_%7BA%7D" /> anomaly of Quantum Chromodynamics (QCD). It has been speculated that <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?U(1)_%7BA%7D" /> may become a symmetry of QCD at high temperatures and studies of the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> could indicate if that is the case. Depending on for how large temperatures the results from large <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?N_%7Bc%7D" /> can be trusted, they indicate that the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> may be possible to study experimentally in heavy-ion collisions due to its sizable in-medium width.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-210687 |
| Date | January 2013 |
| Creators | Niblaeus, Carl |
| Publisher | Uppsala universitet, Kärnfysik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | FYSAST ; FYSMAS1014 |
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