Theorem on vanishing multiloop radiative corrections tosin2θWin grand unified theories at high mass scales

1992 ◽  
Vol 68 (6) ◽  
pp. 754-756 ◽  
Author(s):  
M. K. Parida ◽  
P. K. Patra
2017 ◽  
Vol 32 (33) ◽  
pp. 1745005
Author(s):  
Fei Wang ◽  
Wenyu Wang ◽  
Lei Wu ◽  
Jin Min Yang ◽  
Mengchao Zhang

In this work, we investigate the degenerate heavy Higgs bosons in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) by introducing vector-like particles. Such an extension is well motivated from the top-down view since some grand unified theories usually predict the existence of singlet scalars and vector-like particles at weak scale. Under the constraints from the Large Hadron Collider (LHC) and dark matter experiments, we find that (1) the null results of searching for high mass resonances have tightly constrained the parameter space; (2) two degenerate heavy singlet Higgs bosons [Formula: see text] and [Formula: see text] can sizably decay to [Formula: see text] invisibly. Therefore, search for the monojet events through the process [Formula: see text] may further test our scenario at the future LHC.


Author(s):  
Steven E. Vigdor

Chapter 4 deals with the stability of the proton, hence of hydrogen, and how to reconcile that stability with the baryon number nonconservation (or baryon conservation) needed to establish a matter–antimatter imbalance in the infant universe. Sakharov’s three conditions for establishing a matter–antimatter imbalance are presented. Grand unified theories and experimental searches for proton decay are described. The concept of spontaneous symmetry breaking is introduced in describing the electroweak phase transition in the infant universe. That transition is treated as the potential site for introducing the imbalance between quarks and antiquarks, via either baryogenesis or leptogenesis models. The up–down quark mass difference is presented as essential for providing the stability of hydrogen and of the deuteron, which serves as a crucial stepping stone in stellar hydrogen-burning reactions that generate the energy and elements needed for life. Constraints on quark masses from lattice QCD calculations and violations of chiral symmetry are discussed.


2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Luca Di Luzio

Abstract An accidental U(1) Peccei-Quinn (PQ) symmetry automatically arises in a class of SO(10) unified theories upon gauging the SU(3)f flavour group. The PQ symmetry is protected by the ℤ4 × ℤ3 center of SO(10) × SU(3)f up to effective operators of canonical dimension six. However, high-scale contributions to the axion potential posing a PQ quality problem arise only at d = 9. In the pre-inflationary PQ breaking scenario the axion mass window is predicted to be ma ∈ [7 × 10−8, 10−3] eV, where the lower end is bounded by the seesaw scale and the upper end by iso-curvature fluctuations. A high-quality axion, that is immune to the PQ quality problem, is obtained for ma ≳ 2 0.02 eV. We finally offer a general perspective on the PQ quality problem in grand unified theories.


1982 ◽  
Vol 26 (9) ◽  
pp. 2396-2419 ◽  
Author(s):  
R. W. Robinett ◽  
Jonathan L. Rosner

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