September 2011
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Day September 27, 2011

Can Electroweak Theory Without A Higgs Particle Be Renormalizable?

J. W. Moffat

Whether there exists a massive electroweak (EW) theory, without a Higgs spontaneous symmetry breaking mechanism, that is gauge invariant and renormalizable is investigated. A Stueckelberg formalism for massive \(W\) and \(Z\) bosons is used to derive a gauge invariant EW theory. Negative energy scalar fields that emerge from the gauge invariance of the Lagrangian are removed by invoking an indefinite metric in Hilbert space. A unitary S-matrix and a positive energy spectrum can be obtained by using the PT symmetric formulation of the pseudo-Hermitian Hamiltonian. The theory predicts that if for a system of particles the scalar boson energy \(E_s < \lambda^{1/2}M_W\), where \(\lambda\) is a gauge parameter and \(M_W\) is the \(W\) boson mass, then as \(\lambda\rightarrow\infty\) the scalar boson mass \(\mu=\lambda^{1/2}M_W\) tends to infinity. The theory is perturbatively renormalizable and does not violate longitudinally polarized \(W_L W_L\rightarrow W_L W_L\) scattering in the energy range \(E < \lambda^{1/2}M_W\) for which the scalar bosons have an undetected mass. This means that with this scenario the EW theory can only be treated as an effective renomalizable theory and not as a UV complete theory.
High Energy Physics – Phenomenology (hep-ph); High Energy Physics – Theory (hep-th)

Non-hermitian dynamics of the photosynthetic exciton

A. Thilagam

The non-hermitian quantum dynamics of excitonic energy transfer in photosynthetic systems is investigated using a dissipative two-level dimer model which incorporates radiative terms. The approach is based on the Green’s function formalism which permits consideration of decoherence and intersite transfer processes on comparable terms. The results indicate a combination of coherent and incoherent behavior at higher temperatures with the possibility of exceptional points occuring at the coherent-incoherent crossover regime at critical temperatures. When each dimer site is coupled equally to the environmental sources of dissipation, the excitonic wavepacket evolves with time with a coherent component, which can be attributed to the indistinguishability of the sources of dissipation. The time evolution characteristics of the B850 Bchls dimer system is analysed using typical estimates in photosynthetic systems.
Quantum Physics (quant-ph)

Nonlocal gap solitons in parity-time symmetric optical lattices

Huagang Li, Xiujuan Jiang, Xing Zhu, Zhiwei Shi

We numerically study the nonlocal gap solitons in parity-time (PT) symmetric optical lattices built into a nonlocal self-focusing medium. We state the existence, stability, and propagation dynamics of such PT gap solitons in detail. Simulated results show that there exist stable gap soltions. The influences of the degree of nonlocality on the soliton power, the energy flow density and the stable region of the PT gap solitons are also examined.
Optics (physics.optics)

Quantum noise and mode nonorthogonality in nonhermitian PT-symmetric optical resonators

Gwangsu Yoo, H.-S. Sim, Henning Schomerus

PT-symmetric optical resonators combine absorbing regions with active, amplifying regions. The latter are the source of radiation generated via spontaneous and stimulated emission, which embodies quantum noise and can result in lasing. We calculate the frequency-resolved output radiation intensity of such systems and relate it to a suitable measure of excess noise and mode nonorthogonality. The lineshape differs depending on whether the emission lines are isolated (as for weakly amplifying, almost hermitian systems) or overlapping (as for the almost degenerate resonances in the vicinity of exceptional points associated to spontaneous PT-symmetry breaking). The calculations are carried out in the scattering input-output formalism, and are illustrated for a quasi one-dimensional resonator set-up. In our derivations we also allow for the more general case of a resonator in which the amplifying and absorbing regions are not related by symmetry.
Optics (physics.optics)