Chiral Effective Theory Methods and their Application to the Structure of Hadrons from Lattice QCD

For many years chiral effective theory (ChEFT) has enabled and supported lattice QCD calculations of hadron observables by allowing systematic effects from unphysical lattice parameters to be controlled. In the modern era of precision lattice simulations approaching the physical point, ChEFT techniques remain valuable tools. In this review we discuss the modern uses of ChEFT applied to lattice studies of hadron structure in the context of recent determinations of important and topical quantities. We consider muon g-2, strangeness in the nucleon, the proton radius, nucleon polarizabilities, and sigma terms relevant to the prediction of dark-matter-hadron interaction cross-sections, among others.Comment: Journal of Physics G: Nuclear and Particle Physics focus issue on Lattice QC

Iranian foreign policy under Rouhani

In this Lowy Institute Analysis Rodger Shanahan examines changes in Iranian foreign policy under President Rouhani. He argues that while the Iranian President has changed the tone of Iranian foreign policy, changing the substance will prove much more difficult.  Key findings Rouhani is a centrist rather than a reformist and sees the economy as the key to maximising Iranian national power. The nuclear negotiations are central to ending Iran’s international isolation and reaching a modus vivendi with the United States. But a nuclear deal will not end suspicion of Iran among its neighbours in the region and may even increase it

Commensurability classes of twist knots

In this paper we prove that if $M_K$ is the complement of a non-fibered twist knot $K$ in $\mathbb S^3$, then $M_K$ is not commensurable to a fibered knot complement in a $\mathbb Z/ 2 \mathbb Z$-homology sphere. To prove this result we derive a recursive description of the character variety of twist knots and then prove that a commensurability criterion developed by D. Calegari and N. Dunfield is satisfied for these varieties. In addition, we partially extend our results to a second infinite family of 2-bridge knots.Comment: 10 pages, 3 figure

An enumeration process for racks

Given a presentation for a rack $\mathcal R$, we define a process which systematically enumerates the elements of $\mathcal R$. The process is modeled on the systematic enumeration of cosets first given by Todd and Coxeter. This generalizes and improves the diagramming method for $n$-quandles introduced by Winker. We provide pseudocode that is similar to that given by Holt for the Todd-Coxeter process. We prove that the process terminates if and only if $\mathcal R$ is finite, in which case, the procedure outputs an operation table for the finite rack. We conclude with an application to knot theory.Comment: 23 pages, 3 figures, pseudocode included, article revised according to referees suggestions, section 5 on modifications expanded and new section 7 on python implementation and performance added. Ancillary file contains python cod