Quadratic Contributions of Softly Broken Supersymmetry in the Light of Loop Regularization

Loop regularization (LORE) is a novel regularization scheme in modern quantum field theories. It makes no change to the spacetime structure and respects both gauge symmetries and supersymmetry. As a result, LORE should be useful in calculating loop corrections in supersymmetry phenomenology. To demonstrate further its power, in this article we revisit in the light of LORE the old issue of the absence of quadratic contributions (quadratic divergences) in softly broken supersymmetric field theories. It is shown explicitly by Feynman diagrammatic calculations that up to two loops the Wess-Zumino model with soft supersymmetry breaking terms (WZ' model), one of the simplest models with the explicit supersymmetry breaking, is free of quadratic contributions. All the quadratic contributions cancel with each other perfectly, which is consistent with results dictated by the supergraph techniques.Comment: 25 pages, 3 figures; accepted versio

The central engines of two unusual radio-intermediate/quiet active galactic nuclei: III Zw 2 and PG 1407+265

We use the accretion disk/corona+jet model to fit the multi-band spectral energy distributions (SEDs) of two unusual radio-intermediate/quiet quasars. It is found that the optical/UV emission of III Zw 2 is probably dominated by the emission from the accretion disk. The X-ray emission should be dominated by the radiation from the jet, while the contribution of the disk corona is negligible. The optical/UV component in the SED of PG 1407+265 can be well modeled as the emission from the accretion disk, while the IR component is attributed to the thermal radiation from the dust torus with an opening angle ~ 50\circ. If the X-ray continuum emission is dominated by the synchrotron emission of the jet, the source should be a "high peak frequency blazar", which obviously deviates the normal blazar sequence. The observed SED can also be fitted quite well by the accretion disk/corona model with the viscosity parameter ? = 0:5. The spectrum of the accretion disk/corona in PG 1407+265 satisfies the weak line quasar criterion suggested in Laor & Davis.Comment: 26 pages, 5 figures, Accepted by Ap

Quantum Electroweak Symmetry Breaking Through Loop Quadratic Contributions

Based on two postulations that (i) the Higgs boson has a large bare mass $m_H \gg m_h \simeq 125$ GeV at the characteristic energy scale $M_c$ which defines the standard model (SM) in the ultraviolet region, and (ii) quadratic contributions of Feynman loop diagrams in quantum field theories are physically meaningful, we show that the SM electroweak symmetry breaking is induced by the quadratic contributions from loop effects. As the quadratic running of Higgs mass parameter leads to an additive renormalization, which distinguishes from the logarithmic running with a multiplicative renormalization, the symmetry breaking occurs once the sliding energy scale $\mu$ moves from $M_c$ down to a transition scale $\mu =\Lambda_{EW}$ at which the additive renormalized Higgs mass parameter $m^2_H(M_c/\mu)$ gets to change the sign. With the input of current experimental data, this symmetry breaking energy scale is found to be $\Lambda_{EW}\simeq 760$ GeV, which provides another basic energy scale for the SM besides $M_c$. Studying such a symmetry breaking mechanism could play an important role in understanding both the hierarchy problem and naturalness problem. It also provides a possible way to explore the experimental implications of the quadratic contributions as $\Lambda_{EW}$ lies within the probing reach of the LHC and the future Great Collider.Comment: 10 pages, 2 figures, published versio