Fractional charges and the renormalization group in the SU(4)×O(4) string model

Leontaris, GK; Tracas, ND

dc.contributor.author	Leontaris, GK	en
dc.contributor.author	Tracas, ND	en
dc.date.accessioned	2014-03-01T01:08:48Z
dc.date.available	2014-03-01T01:08:48Z
dc.date.issued	1992	en
dc.identifier.issn	0170-9739	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/10705
dc.subject	Gauge Symmetry	en
dc.subject	Low Energy	en
dc.subject	Renormalization Group	en
dc.subject	Spectrum	en
dc.subject	Top Quark	en
dc.subject	Renormalization Group Equation	en
dc.subject.classification	Physics, Particles & Fields	en
dc.subject.other	3-GENERATION SUPERSTRING MODEL	en
dc.subject.other	NONRENORMALIZABLE TERMS	en
dc.subject.other	THRESHOLD CORRECTIONS	en
dc.subject.other	HETEROTIC STRINGS	en
dc.subject.other	GAUGE	en
dc.subject.other	UNIFICATION	en
dc.subject.other	CONSTRUCTION	en
dc.subject.other	FORMULATION	en
dc.subject.other	CONSTRAINTS	en
dc.subject.other	DIMENSIONS	en
dc.title	Fractional charges and the renormalization group in the SU(4)×O(4) string model	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/BF01565959	en
heal.identifier.secondary	http://dx.doi.org/10.1007/BF01565959	en
heal.language	English	en
heal.publicationDate	1992	en
heal.abstract	We study the renormalization group equations of the gauge couplings in the SU(4) x O(4) approximately SU(4) x SU(2)L x SU(2)R string model, derived in the context of the free fermionic formulation of the four dimensional superstring. We calculate the effective string unification scale taking into account string threshold corrections and we consider the consequences of the n(L) and n(R) fractionally charged states, sitting in the (1, 2, 1) and (1, 1, 2) representations correspondingly, of the gauge symmetry of the model. Some of these states become massive at a very high scale, when a number of singlet fields acquire vev's. However, many of them (the precise number depends on the specific choice of the flat direction) remain in the massless spectrum. We consider various cases and find that, for specific choices of flat directions, the physical parameters of the model, like the grand unification scale and the low energy parameters sin2 theta(W) and alpha(3), depend only on the difference n- = n(L) - n(R). We study more general cases where remnants of the exotic doublets remain below the SU(4) breaking scale. We also solve the coupled differential system of the renormalization group equations for the gauge and the Yukawa couplings and estimate the range of the top quark mass which is found to lie in the range 140 GeV < m(t) < 190 GeV.	en
heal.publisher	Springer-Verlag	en
heal.journalName	Zeitschrift für Physik C Particles and Fields	en
dc.identifier.doi	10.1007/BF01565959	en
dc.identifier.isi	ISI:A1992JZ07900019	en
dc.identifier.volume	56	en
dc.identifier.issue	3	en
dc.identifier.spage	479	en
dc.identifier.epage	485	en