Light-cone behavior of the pion Bethe-Salpeter wave function in the ladder model

The Bethe-Salpeter wave function χ(q^ν+P^ν, q^ν) for two spin-½ quarks bound by the exchange of a scalar meson is examined in the ladder model. We seek the behavior of χ as the squared momentum, (q+P)^2, on one leg becomes infinite while the squared momentum, q^2, on the other leg remains fixed. This behavior is investigated by making a Wick rotation, expanding χ in partial-wave amplitudes χ^i_J(q^2) of the group O(4), and then looking for the rightmost poles of χ^i_J(q^2) in the complex J plane. Our results verify (in the ladder model) the useful hypothesis that the locations of these poles are independent of q^2 and can thus be computed in the q^2→∞ limit by using conformal invariance

Large-Q^2 behavior of the pion electromagnetic form factor

We study the large-Q^2 behavior of the electromagnetic form factor of the pion, which is viewed as a quark-antiquark bound state in a (nongauge) quantum field theory. When the pion's Bethe-Salpeter wave function is expanded in O(4) partial waves, it is found that the information needed about the partial-wave amplitudes is their scaling behavior at large momentum and the locations of their poles in the complex J plane. This information is determined by using the operator-product expansion, conformal invariance at short distances, and a regularity property that holds at least in the ladder model. The resulting behavior of the form factor is roughly F(Q^2)~(Q^2)^(-1), with corrections due to anomalous dimensions

Next-to-leading order QCD calculations with parton showers II: soft singularities

Programs that calculate observables in quantum chromodynamics at next-to-leading order typically generate events that consist of partons rather than hadrons -- and just a few partons at that. These programs would be much more useful if the few partons were turned into parton showers, which could be given to one of the Monte Carlo event generators to produce hadron showers. In a previous paper, we have seen how to generate parton showers related to the final state collinear singularities of the perturbative calculation for the example of e+ + e- --> 3 jets. This paper discusses the treatment of the soft singularities.Comment: 26 pages with 5 figures. This version is close to the version to be publishe

Biomolecular self-assembly under extreme Martian mimetic conditions

The recent discovery of subsurface water on Mars has challenged our understanding of the natural limits of life. The presence of magnesium perchlorate (Mg(ClO4)2) on the Martian surface raises the possibility that it may also be present in this subsurface lake. Given that the subsurface lakes on Earth, such as Lake Vostok and Lake Whillans, are capable of harbouring surprising amounts of life, these new findings raise interesting possibilities for how biomolecules might self-assemble in this environment on Mars. Here we investigate the self-association and hydration of the amino acid glycine in aqueous Mg(ClO4)2 at 25°C and −20°C using neutron diffraction with hydrogen isotope substitution and subsequent analysis with empirical potential structure refinement to yield a simulated box of atoms consistent with the scattering data. We find that although the highly chaotropic properties of Mg(ClO4)2 disrupt the hydration and hydrogen bonding ability of the amino acid, as well as the bulk water structure, glycine molecules are nonetheless still able to self-associate. This occurs more readily at lower temperature, where clusters of up to three molecules are observed, allowing us to speculate that the formation of biological molecules is possible in the Martian environment

Identifying Relevant Socio-Theoretic Foundations for Supporting Multi-Issue IT Cloudsourcing Negotiations

Service level agreement (SLA) negotiations involving cloud-based information technology (IT) service providers and customers are now commonplace. Although historical research on negotiation has often relied on economic foundations, the important nature of IT service levels to organizations’ operational effectiveness suggests that negotiation complexities in the context of cloud-based outsourcing (or cloudsourcing) cannot be well understood by relying on economic perspectives alone. To that end, this paper reports on experiments designed to determine the relevance of competing sociotheoretic frameworks as they pertain to IT cloudsourcing negotiations. Contributions include a rigorous examination of hypotheses derived from social exchange theory, equity theory, learning theory, and the win–win theories of negotiation. Additional contributions include the development of methodological constructs (using the Euclidean geometry) that reflect the complex nature of IT cloudsourcing SLAs, i.e., that they are composed of numerous service category contract clauses where negotiation tradeoffs within a service category as well as across service categories are possible. We find strong support for the relevance of the social exchange theory to IT cloudsourcing negotiations, as well as moderate support for the win-win theories of negotiation. Our conclusions provide clear directions for extending our work into the realm of negotiation support systems, and we rely on our findings to conjecture that IT cloudsourcing negotiation is a unique context for sociotheoretic negotiation research due to the inherent importance of information technologies to organizations’ operational effectiveness

Three Newly Recovered Leaves From The ‘Winchester Anthology’*

This note reports the recovery of three folios missing from the late-fifteenth-century miscellany known as the ‘Winchester Anthology’ (British Library, MS Additional 60577) within the collections of the Bodleian Library, inside one of the eighteenth-century notebooks of the antiquarian Thomas Hearne (MS Hearne's Diaries 42). An account is given of the material composition of the leaves as well as their textual content; as part of this discussion, a suggestion is offered as to where precisely these leaves were originally situated inside the ‘Winchester Anthology’.I wish finally to thank the Arts and Humanities Research Council for supporting this work in the form of funding for a Master of Studies degree (2013-14)

Partons and Jets at the LHC

I review some issues related to short distance QCD and its relation to the experimental program of the Large Hadron Collider (LHC) now under construction in Geneva.Comment: Talk at the conference QCD2002 at IIT Kanpur, India, November 2002. Ten pages with 12 figure