Next-to-next-to-leading order prediction for the photon-to-pion transition form factor

We evaluate the next-to-next-to-leading order corrections to the hard-scattering amplitude of the photon-to-pion transition form factor. Our approach is based on the predictive power of the conformal operator product expansion, which is valid for a vanishing $\beta$-function in the so-called conformal scheme. The Wilson--coefficients appearing in the non-forward kinematics are then entirely determined from those of the polarized deep-inelastic scattering known to next-to-next-to-leading accuracy. We propose different schemes to include explicitly also the conformal symmetry breaking term proportional to the $\beta$-function, and discuss numerical predictions calculated in different kinematical regions. It is demonstrated that the photon-to-pion transition form factor can provide a fundamental testing ground for our QCD understanding of exclusive reactions.Comment: 62 pages LaTeX, 2 figures, 9 tables; typos corrected, some references added, to appear in Phys. Rev.

Next Steps for Hydrogen - physics, technology and the future

Hydrogen has been proposed as a future energy carrier for more than 40 years. In recent decades, impetus has been given by the need to reduce global greenhouse gas emissions from vehicles. In addition, hydrogen has the potential to facilitate the large-scale deployment of variable renewables in the electricity system. Despite such drivers, the long-anticipated hydrogen economy is proving to be slow to emerge. This report stresses the role that physics and physics-based technology could play in accelerating the large-scale deployment of hydrogen in the energy system. Emphasis is given to the potential of cryogenic liquid hydrogen and the opportunities afforded by developments in nanoscience for hydrogen storage and use. The use of low-temperature liquid hydrogen opens up a technological opportunity separate from, but complementary with, energy applications. The new opportunity is the ability to cool novel materials into the superconducting state without the need to use significant quantities of expensive liquid helium. Two of the authors have previously coined the term “hydrogen cryomagnetics” for when liquid hydrogen is utilised in high-field and high-efficiency magnets. The opportunity for liquid hydrogen to displace liquid helium may be a relatively small business opportunity compared to global transport energy demands, but it potentially affords an opportunity to kick-start the wider commercial use of hydrogen. The report considers various important factors shaping the future for hydrogen, such as competing production methods and the importance of safety, but throughout it is clear that science and engineering are of central importance to hydrogen innovation and physics has an important role to play

Next time must be different. CEPS Commentaries, 4 November 2009

In signing the Lisbon Treaty on November 3rd, Czech President Václav Klaus brought to an anti-climatic close years of protracted and often acrimonious negotiations to overhaul the European Union’s institutional infrastructure. The EU's reform treaty is now fully ratified and is expected to enter into force on 1 December 2009. However frustrating and bruising the ratification experience may have been, it is hoped that the whole saga will have the unintended (but finally, positive) consequence of strengthening the determination of those wishing to ensure that the next round of treaty change can enter into force even if one or more member countries is not willing or able to agree to it

Creating a National Network of Energy Discovery-Innovation Institutes: A Step Toward America's Energy Sustainability

Draft 1.1http://deepblue.lib.umich.edu/bitstream/2027.42/88576/1/2008_NREN_Draft_1.2.pd

Perturbative heavy quarkonium spectrum at next-to-next-to-next-to-leading order

We compute the energy levels of some of the lower-lying heavy quarkonium states perturbatively up to O(alpha_s^5*m) and O(alpha_s^5*m*log[alpha_s]). Stability of the predictions depends crucially on the unknown 4-loop pole-MSbar mass relation. We discuss the current status of the predictions with respect to the observed bottomonium spectrum.Comment: Short review on non-perturbative contributions included at the end; version to appear in Phys.Lett.; 7 pages, 2 figure

The two-nucleon system at next-to-next-to-next-to-leading order

We consider the two-nucleon system at next-to-next-to-next-to-leading order (N^3LO) in chiral effective field theory. The two-nucleon potential at N^3LO consists of one-, two- and three-pion exchanges and a set of contact interactions with zero, two and four derivatives. In addition, one has to take into account various isospin-breaking and relativistic corrections. We employ spectral function regularization for the multi-pion exchanges. Within this framework, it is shown that the three-pion exchange contribution is negligibly small. The low-energy constants (LECs) related to pion-nucleon vertices are taken consistently from studies of pion-nucleon scattering in chiral perturbation theory. The total of 26 four-nucleon LECs has been determined by a combined fit to some np and pp phase shifts from the Nijmegen analysis together with the nn scattering length. The description of nucleon-nucleon scattering and the deuteron observables at N^3LO is improved compared to the one at NLO and NNLO. The theoretical uncertainties in observables are estimated based on the variation of the cut-offs in the spectral function representation of the potential and in the regulator utilized in the Lippmann-Schwinger equation.Comment: 62 pp, 13 fig