36290076
Embedding flipped SU(5) into SO(10)
We embed the flipped SU(5) models into the SO(10) models. After the SO(10) gauge symmetry is broken down to the flipped SU(5) x U(1)(X) gauge symmetry, we can split the five/one-plets and ten-plets in the spinor 16 and 16 Higgs fields via the stable sliding singlet mechanism. As in the flipped SU(5) models, these ten-plet Higgs fields can break the flipped SU(5) gauge symmetry down to the Standard Model gauge symmetry. The doublet-triplet splitting problem can be solved naturally by the missing partner mechanism, and the Higgsino-exchange mediated proton decay can be suppressed elegantly. Moreover, we show that there exists one pair of the light Higgs doublets for the electroweak gauge symmetry breaking. Because there exist two pairs of additional vector-like particles with similar intermediate-scale masses, the SU(5) and U(1)(X) gauge couplings can be unified at the GUT scale which is reasonably (about one or two orders) higher than the SU(2)(L) x SU(3)(C) unification scale. Furthermore, we briefly discuss the simplest SO(10) model with flipped SU(5) embedding, and point out that it can not work without fine-tuning.
119152066
The Lee–Wick fields out of gravity
Abstract We study the Maxwell–Einstein theory in the framework of effective field theories. We show that the modified one-loop renormalizable Lagrangian due to quantum gravitational effects contains a Lee–Wick vector field as an extra degree of freedom in the theory. Thus gravity provides a natural mechanism for the emergence of this exotic particle.
8450139
Electrodynamics modified by some dimension-five Lorentz-violating interactions: radiative corrections
We study radiative corrections to massless quantum electrodynamics modified by two dimension-five LV interactions $$\bar{\Psi } \gamma ^{\mu } b'^{\nu } F_{\mu \nu }\Psi $$Ψ¯γμb′νFμνΨ and $$\bar{\Psi }\gamma ^{\mu }b^{\nu } \tilde{F}_{\mu \nu } \Psi $$Ψ¯γμbνF~μνΨ in the framework of effective field theories. All divergent one-particle-irreducible Feynman diagrams are calculated at one-loop order and several related issues are discussed. It is found that massless quantum electrodynamics modified by the interaction $$\bar{\Psi } \gamma ^{\mu } b'^{\nu } F_{\mu \nu }\Psi $$Ψ¯γμb′νFμνΨ alone is one-loop renormalizable and the result can be understood on the grounds of symmetry. In this context the one-loop Lorentz-violating beta function is derived and the corresponding running coefficients are obtained.
120591757
LANGEVIN DESCRIPTION OF THE EVAPORATION RESIDUE SPIN DISTRIBUTION
The recently measured spin distribution of evaporation residue cross section in the reaction 16O + 184W is studied in the framework of Langevin equations. Results show that the Langevin approach can describe this observable very well. Moreover, a pre-saddle nuclear viscosity coefficient of 5 × 1021 s-1 is extracted by comparing theoretical calculations with experimental data. We also explore the effect of the isospin of a system on the spin distribution by evaluating the evaporation residue spin distribution of nuclei 194Pb, 200Pb and 206Pb. It has been found that with increasing the isospin of the system, the sensitivity of the evaporation residue spin distribution to the nuclear viscosity is decreased significantly. This result suggests that choosing a low-isospin compound system favors an accurate determination of pre-saddle dissipation strength.
119306365
TeV scale Lee-Wick fields out of large extra dimensional gravity
We study the gravitational corrections to the Maxwell, Dirac, and Klein-Gordon theories in the large extra dimension model in which the gravitons propagate in the (4 + n)-dimensional bulk, while the gauge and matter fields are confined to the four-dimensional world. The corrections to the two-point Green's functions of the gauge and matter fields from the exchanges of virtual Kaluza-Klein gravitons are calculated in the gauge independent background field method. In the framework of effective field theory, we show that the modified one-loop renormalizable Lagrangian due to quantum gravitational effects contains a TeV scale Lee-Wick partner of every gauge and matter field as extra degrees of freedom in the theory. Thus the large extra dimension model of gravity provides a natural mechanism for the emergence of these exotic particles which were recently used to construct an extension of the standard model.
119187103
Reducing the Tension Between the BICEP2 and the Planck Measurements: A Complete Exploration of the Parameter Space
A large inflationary tensor-to-scalar ratio r0.002 = 0.20 +0.07 0.05 is reported by the BICEP2 team based on their B-mode polarization detection, which is outside of the 95% confidence level of the Planck best fit model. We explore several possible ways to red uce the tension between the two by considering a model in whichαs, nt, ns and the neutrino parameters Neff andmν are set as free parameters. Using the Markov Chain Monte Carlo (MCMC) technique to survey the complete parameter space with and without the BICEP2 data, we find that the resulting constraints on r0.002 are consistent with each other and the apparent tension seems to be relaxed. Further detailed investigations on those fittin gs suggest that Neff probably plays the most important role in reducing the tension. We also find that the results obtained from fittin g without adopting the consistency relation do not deviate much from the consistency relation. With available Planck, WMAP, BICEP2 and BAO datasets all together, we obtain r0.002 = 0.14 +0.05 0.11 , nt = 0.35 +0.28 0.47 , ns = 0.98 +0.02 0.02 , andαs = 0.0086 +0.0148 0.0189 ; if the consistency relation is adopted, we get r0.002 = 0.22 +0.05 0.06 .