A portfolio of photochemical transformations found in a variety areas can be rationalized through consideration either gain 4nπ-electron aromaticity or relief (4n+2) π-electron antiaromaticity excited states ππ* character. These back-of-an-envelope tools provided by Baird's rule serve as compass for excursions electronically states. More information the Review H. Ottosson and co-workers (DOI: 1...

We present estimates of the charming penguin contribution to B → Kπ, ππ,Kη,Kη decays due to intermediate charmed meson states. We find that this contribution is indeed significant for B → Kπ decays, and its inclusion, together with the tree and penguin terms, produces large branching ratios in agreement with data, though the analysis is affected by large theoretical uncertainties. On the other ...

We discuss strategies to determine hadronic decay couplings from lattice studies. As an application, we explore the decay of a vector meson to two pseudoscalar mesons with Nf = 2 flavours of sea quark. Although we are working with quark masses that do not allow a physical decay, we show how the transition rate can be evaluated from the amplitude for ρ→ ππ and from the annihilation component of ...

The σ resonance was observed as a conspicuous ππ peak in hadronic decays like J/ψ → ππω or D → πππ. The phase of the σ → ππ amplitude, extracted from production data within the conventional isobar model, is assumed to coincide with that in ππ elastic scattering. We check the validity of this assumption by using Lehmann-Symanzik-Zimmermann (LSZ) reduction and unitarity. The rescattering effects ...

The all–important consequence of Chiral Dynamics for ππ scattering is the Adler zero, which forces ππ amplitudes to grow asymptotically. The continuation of this subthreshold zero into the physical regions requires a P –wave resonance, to be identified with the ρ. It is a feature of ππ scattering that convergent dispersive integrals for the I = 1 channel are essentially saturated by the ρ–reson...

We explore the decay of a vector meson to two pseudoscalar mesons on the lattice with N f = 2 flavours of sea quark. Although we are working with quark masses that do not allow a physical decay, we show how the transition rate can be evaluated from the amplitude for ρ → ππ and from the annihilation component of ππ → ππ. We explore the decay amplitude for two different pion momenta and find cons...

I calculate the leading logarithmic contributions up to two-loop order of the octet part of the K0 → ππ amplitude. This sector of the weak chiral Lagrangian is believed to be the main source of the enhancement of the I = 0 relative to the I = 2 K0 → ππ amplitude, the so-called ∆I = 1/2 rule. I discuss the procedure of chiral extrapolations of lattice data specific to K → ππ decays and study the...

We present a method of determining the CKM-angle α by performing simultaneous measurements of the mixing-induced CP asymmetries of the decays Bd → ππ and Bd → KK̄. The accuracy of our approach is limited by SU(3)-breaking effects originating from b̄ → d̄ss̄ QCD-penguin diagrams. Using plausible power-counting arguments we show that these uncertainties are expected to be of the same order as those a...