Renormalization Group Approachto Hot and Dense MatterVom Fachbereich Physikder Technischen Universit¨at Darmstadtzur Erlangung des Gradeseines Doktors der Naturwissenschaften(Dr. rer. nat.)genehmigteDissertationvonDipl.-Phys. Borislav Stoki´caus Olten (Schweiz)Referent: Prof. Dr. B. FrimanKorreferent: Prof. Dr. J. WambachTag der Einreichung: 01.12.2008Tag der Pru¨fung: 22.12.2008Darmstadt 2008D17iiPosveeno mojim dragim roditeƩimaiiiivAbstractThe chiral quark-meson model, being an effective low-energy realization for sponta-neous chiral symmetry breaking of QCD at intermediate momentum scales, is oftenusedtostudyvariouspropertiesofstronglyinteractingmatter. Inthisthesisweem-ploy thismodel toinvestigate the criticalbehavior ofhotanddense matterwithtwodegenerate light flavors. Using the method of the functional renormalization group,we derive the flow equation for the scale dependent thermodynamic potential atfinite temperature and chemical potential in the presence of an explicit symmetrybreaking term. We explore the scaling behavior of various observables and confrontour results with the Widom-Griffiths form ofthe equation of state. The focus ofourstudy are especially the scaling properties of the order parameter and its transverseandlongitudinalsusceptibilities forsmall, butfinitevaluesoftheexternalfieldwhenapproaching the critical point from the symmetric as well as from the broken phase.