On the effective action of the vacuum photon splitting in Lorentz violating QED through Krein space

The finding of an explicit effective action describing amplitude of photon triple splitting is investigated through Krein space quantization and quantum metric fluctuation. Using the derivative expansion method, the one-loop radiative corrections from Lorentz- and CPT- violating extended Krein QED shows that it is not possible to find a nonzero effective action

Euler-Heisenberg lagrangian through Krein regularization

The Euler-Heisenberg effective action at the one-loop for a constant electromagnetic field is derived in Krein space quantization with Ford's idea of uctuated light-cone. In this work we present a perturbative, but convergent solution of the effective action. Without using any renormalization procedure, the result coincides with the famous renormalized Euler-Heisenberg action.Comment: arXiv admin note: text overlap with arXiv:1109.269

QED effective action in Krein space quantization

The one-loop effective action of QED is calculated by the Schwinger method in Krein space quantization. We show that the effective action is naturally fnite and regularized. It also coincides with the renormalized solution which was derived by Schwinger.Comment: 15 pages, Accepted for publication in Phys.Lett.

Dual Doping of MoP with M(Mn,Fe) and S to Achieve High Hydrogen Evolution Reaction Activity in Both Acidic and Alkaline Media

Rational design of cost‐effective, high performance and stable hydrogen evolution reaction (HER) electrocatalysts in both acidic and alkaline media holds the key to the future hydrogen‐based economy. Herein, we introduce an effective approach of simultaneous non‐metal (S) and metal (Fe or Mn) doping of MoP to achieve excellent HER performance at different pH. The catalysts show remarkable overpotentials at −10 mA cm−2 of only 65 and 68 mV in 0.5 M H2SO4, and 50 and 51 mV in 1.0 M KOH, respectively, as well as much higher turnover frequencies compared to undoped MoP. Furthermore, the catalysts exhibit outstanding long‐term stability at a fixed current of −10 mA cm−2 for 40 h. The effects of both dopants, such as electronic structure modification and enhancement of the intrinsic activity, increase of the electrochemically active surface area, and formation of coordinatively unsaturated edge sites, act cooperatively to accelerate the HER at both pH media. Additionally, the presence of oxophilic Mn and Fe at the surface results in Mn or Fe oxide/hydroxide species that promote the dissociation of water molecules in alkaline electrolyte. This work introduces a facile and effective design principle that could pave the way towards engineering highly active HER catalysts for a wide pH range.Metal (Mn or Fe) and non‐metal (S) dual doped MoP catalysts were synthesiszed by reductive pyrolysis of the corresponding Mn,Mo‐ and Fe,Mo‐phosphonates precursors, in the presence of elemental S. The derived catalysts showed remarkable hydrogen evolution reaction (HER) activity in acidic and alkaline media. The dual doping process endowed MoP with proper hydrogen binding energy thus enhancing the HER in acidic media. In addition, Mn and Fe acted as surface oxides species in alkaline medium, which facilitated the water dissociation step. imageYousef Jameel Scholarship FundPeer Reviewe

Krein Regularization of \lambda\phi^4

We calculate the four-point function in \lambda\phi^4 theory by using Krein regularization and compare our result, which is finite, with the usual result in \lambda\phi^4 theory. The effective coupling constant (\lambda_\mu) is also calculated in this method