Electron spin resonance in X-irradiated β-alanine

Electron spin resonance spectra of X-irradiated powder and single crystal samples of β-alanine do not exhibit any change following several recrystallizations. This negative finding is contrary to a published report.     

Relativistic extension of the electromagnetic current for composite systems

We formulate a general method for evaluating relativistic and binding energy corrections to matrix elements of the electromagnetic current for multiparticle composite systems. Application is made to the calculation of the g-factor for bound electrons and compared with recent experiments.     

QQG hybrid mesons in the MIT bag model

We suggest that hybrid (q$\text{q}$g) mesons could exist with rather light masses. The spectrum of the ground state nonets, J^PC = (0, 1, 2)^?+; 1^?? is calculated in the MIT bag model including O(α_s) energy shifts. We discuss hadronic transitions among these states, consider their possible production at LEAR and SPEAR and indicate some interesting decay signatures.     

Short and long distance effects in weak radiative decays

Flavour changing radiative decays for strange and charmed hadrons are studied in a model where the GIM weak interaction triggers the flavour change at the quark level and QCD corrections are taken into account. The amplitudes for photon emission are calculated for both non-factorisable (negligible) and factorisable contributions (dominant). We thereby achieve a “modern pole model” in which we include 56 and 70 intermediate states and normalise the amplitude in terms of the fundamental quark weak interaction.We generate large parity-violating amplitudes and explain qualitatively the relative size of all processes. We find a pattern of allowed (Λ→n + γ), (Ξ⁰→Σ⁰γ) and (Ξ⁰→Λγ), suppressed (Σ⁺→p + γ) and doubly suppressed decay $\text{(Ω}{}^{\mathrm{?}}\text{→Ξ + γ)}$ which show the complex pattern of symmetry and dynamical cancellations and enhancements.Following Shifman et al., we also show that short distance effects are negligible. Other approaches are discussed and in particular it is shown that the asymmetry in Σ⁺→p + γ poses no theoretical problem. Many predictions can be tested with the forthcoming new generation experiments.     

Achieving peak brightness in an atom laser

In this Letter we present experimental results and a simple analytic theory on the first continuous (long pulse) Raman atom laser. We analyze the flux and brightness of a generic two state atom laser with an analytic model that shows excellent agreement with our experiments. We show that, for the same source size, the brightness achievable with a Raman atom laser is at least 3 orders of magnitude greater than achievable in any other demonstrated continuously outcoupled atom laser.     

Essay review Pride and precedence in Victorian science

The announced discovery of the Higgs boson at CERN's Large Hadron Collider on July 4 is described, put into context, and its implications assessed.     

Operator algebras and a theorem of Dieudonne

LetA be aC*-algebra with second dualA″. Let (φ _n)(n=1,...) be a sequence in the dual ofA such that limφ _n(a) exists for eacha εA. In general, this does not imply that limφ _n(x) exists for eachx εA″. But if limφ _n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ _n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem.