Evaluation ofS,T, U parameters, triple gauge boson vertices and some oblique corrections in extraU(1) superstring inspired model

Sahu, R.; Sharma, Neetika; Singh, Sardar; Nagawat, Ashok K.; Saxena, Pranav

doi:10.1007/bf02831492

Cited by 1 publication

(9 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is in good agreement with SLD collaborations data on the measured left-right symmetry parameter A LR [13]. The top quark mass measurements data can also be accommodated in this model [9][10][11][12]. In the present paper we have reexamined the low energy theorems and the unitarity bounds in the four well-known extra U1 superstring inspired E 6 -, , and models.…”

Section: Introductionsupporting

confidence: 83%

“…2), and therefore, for the case s M 2 W , this is given by [2,8] [9][10][11][12]. This model gives reasonable negative values of S, T, U parameters [12]. It is in good agreement with SLD collaborations data on the measured left-right symmetry parameter A LR [13].…”

Section: Introductionsupporting

confidence: 64%

“…At low energy, the theorems for the gauge boson scattering amplitudes remain valid, but the high-energy amplitudes do not seem to satisfy the relation given by Eq. (12) consistently with the requirement of present day high energy phenomenology. In Sec.…”

Section: Introductionsupporting

confidence: 57%

“…2), and therefore, for the case s M 2 W , this is given by [2,8] [9][10][11][12]. This model gives reasonable negative values of S, T, U parameters [12].…”

Section: Introductionmentioning

confidence: 88%

“…If the new U1 0 results from Wilson-loop breaking mechanism directly to the rank 5 subgroup in string context, then new U1 0 is indeed U1 model, which has been of our primary interest [9][10][11][12]. Our main emphasis has been to establish its viability as one of the suitable models for doing physics beyond SM, when such a need arises.…”

Section: Low Energy Theorems In the Extra U(1) Modelsmentioning

confidence: 97%

See 4 more Smart Citations

Low energy theorems and the unitarity bounds in the extraU(1)superstring inspiredE6models

et al. 2005

Self Cite

View full text Add to dashboard Cite

The conventional method using low energy theorems derived by Chanowitz et al. [Phys. Rev. Lett. 57, 2344;] does not seem to lead to an explicit unitarity limit in the scattering processes of longitudinally polarized gauge bosons for the high energy case in the extra U1 superstring inspired models, commonly known as model, emanating from E 6 group of superstring theory. We have made use of an alternative procedure given by Durand & Lopez [Phys. Lett. B 217, 463 (1989);], which is applicable to supersymmetric grand unified theories. Explicit unitarity bounds on the superpotential couplings (identified as Yukawa couplings) are obtained from both using unitarity constraints as well as using renormalization group equations (RGE) analysis at one-loop level utilizing critical couplings concepts implying divergence of scalar coupling at M G . These are found to be consistent with finiteness over the entire range M Z s p M G i.e. from grand unification scale to weak scale. For completeness, the similar approach has been made use of in other models i.e., , , and models emanating from E 6 and it has been noticed that at weak scale, the unitarity bounds on Yukawa couplings do not differ among E 6 extra U1 models significantly except for the case of model in 16 representations. For the case of the E 6 -model E 9:64, the analysis using the unitarity constraints leads to the following bounds on various parameters: tmax: M Z 1:294, bmax: M Z 1:278, Hmax: M Z 0:955, Dmax: M Z 1:312. The analytical analysis of RGE at the one-loop level provides the following critical bounds on superpotential couplings: t;c M Z 1:295, b;c M Z 1:279, H;c M Z 0:968, D;c M Z 1:315. Thus superpotential coupling values obtained by both the approaches are in good agreement. Theoretically we have obtained bounds on physical mass parameters using the unitarity constrained superpotential couplings. The bounds are as follows: (i) Absolute upper bound on top quark mass m t 225 GeV, (ii) the upper bound on the lightest neutral Higgs boson mass at the tree level is m tree H 0 2 169 GeV, and after the inclusion of the one-loop radiative correction it is m H 0 2 229 GeV when t Þ b at the grand unified theory scale. On the other hand, these are m tree H 0 2 159 GeV, m H 0 2 222 GeV, respectively, when t b at the grand unified theory scale. A plausible range on D-quark mass as a function of mass scale M Z 2 is m D O3 TeV for M Z 2 O1 TeV for the favored values of tan 1. The bounds on aforesaid physical parameters in the case of , , and models in the 27 representation are almost identical with those of model and are consistent with the present day experimental precision measurements.

show abstract

Section: Introductionsupporting

confidence: 83%

Section: Introductionsupporting

confidence: 64%

Section: Introductionsupporting

confidence: 57%

“…2), and therefore, for the case s M 2 W , this is given by [2,8] [9][10][11][12]. This model gives reasonable negative values of S, T, U parameters [12].…”

Section: Introductionmentioning

confidence: 88%