Hadron Physics: The Essence of Matter

Dynamical chiral symmetry breaking (DCSB) is a remarkably effective mass generating mechanism. It is also, amongst other things, the foundation for a successful application of chiral effective field theories, the origin of constituent-quark masses, and intimately connected with confinement in QCD. Using the Dyson-Schwinger equations (DSEs), we explain the origin and nature of DCSB, and elucidate some of its consequences, e.g.: a model-independent result for the pion susceptibility; the generation of a quark anomalous chromomagnetic moment, which may explain the longstanding puzzle of the a_1-rho mass splitting; its impact on the behaviour of the electromagnetic pion form factor -- thereby illustrating how data can be used to chart the momentum-dependence of the dressed-quark mass function; in the form of the pion and kaon valence-quark parton distribution functions, and the relation between them; and aspects of the neutron's electromagnetic form factors, in particular F_1^u/F_1^d and G_M^n. We argue that in solving QCD, a constructive feedback between theory and extant and forthcoming experiments will most rapidly enable constraints to be placed on the infrared behaviour of QCD's \beta-function, the nonperturbative quantity at the core of hadron physics; and emphasise throughout the role played by confrontation with data as a means of verifying our understanding of Nature.Comment: 24 pages, 6 figures, 3 tables. Contribution to the proceedings of the XII Mexican Workshop on Particles and Fields, based on presentations by C.D.Roberts at the Workshop (9-14 Nov. 2009, Mazatlan, Mexico) and at the preceding Mini-School (5-8 Nov. 2009, Culiacan, Mexico)

Empirically Charting Dynamical Chiral Symmetry Breaking

We provide a snapshot of recent progress in hadron physics made using QCD's Dyson-Schwinger equations, reviewing the generation of a quark anomalous chromomagnetic moment, which may explain the longstanding puzzle of the $a_1$-$\rho$ mass splitting, and the form of the pion and kaon valence-quark parton distribution functions.Comment: 6 pages, 1 figure, 1 table. Contribution to the proceedings of "Achievements and New Directions in Subatomic Physics: Workshop in Honour of Tony Thomas' 60th Birthday," Special Centre for the Subatomic Structure of Matter, Adelaide, South Australia, February 15 - February 19, 2010

[Review of] Jo Ann Robinson. The Montgomery Bus Boycott and the Women Who Started It: The Memoirs of Jo Ann Gibson Robinson

Jo Ann Robinson, a major organizer of the Montgomery bus boycott, offers a new and convincing account of the origins of the protest that triggered the entire civil rights movement and launched the career of Martin Luther King, Jr. In an absorbing, first-hand narrative, the dignified and unassuming Robinson focuses on the role of the Women\u27s Political Council (WPC) and details the WPC\u27s plans to engineer a boycott months before the heralded arrest of Rosa Parks

[Review of] Adam Fairclough. To Redeem the Soul of America: The Southern Christian Leadership Conference and Martin Luther King, Jr.

Following David J. Garrow\u27s 1986 Pulitzer Prize-winning biography, Bearing the Cross, Adam Fairclough makes extensive use of information gleaned from FBI wiretaps as well as other sources in an effort to peruse the soul of the Southern Christian Leadership Conference (SCLC) and its president, Martin Luther King, Jr. Fairclough\u27s subtitle is no accident, for he focuses at least as much on the SCLC as he does on King. Significantly, this emphasis causes him to add a chapter about the SCLC after King\u27s death, a postscript not available in other books about King

Why weak patents? Rational ignorance or pro-"customer" Tilt?

The issuance of weak patents is widely viewed as a fundamental problem in the current US patent system. Reasons that have been offered for the granting of weak patents by the US Patent and Trademark Office (USPTO) include examiners’ “rational ignorance” of the patentability of applications and pro-“customer” rules and institutions that create incentives for examiners to grant patents of dubious validity to their “customers”- applicants. In this paper, we study whether US examiners’ behavior in prior art search betrays their assessment of applications’ patentability. For a sample of US patents for which applications were also filed at the European Patent Office (EPO), we construct a measure of the fraction of prior art that is missed by US examiners. We find that this measure significantly explains the probability of receiving a patent at the EPO. The results are robust to different empirical specifications. US examiners’ prior art searches indicate that they are, on average, not “rationally ignorant”. On the contrary, they identify and dedicate more search effort to those applications that seem more problematic, because they bear the burden of proof of non-patentability. Our study offers empirical evidence that a systematic problem of weak patents likely exists, and suggests that the problem may be more strongly attributable to the pro-applicant rules and policies than to examiners’ ignorance. The current prevalence of weak patents does not appear to be caused at the margin by lack of resources at the USPTO.Weak patents, Rational ignorance, cited prior art, missed prior art, Industrial Organization, Institutional and Behavioral Economics, Research and Development/Tech Change/Emerging Technologies,

Multi-chip module interconnections at microwave frequencies: electromagnetic simulation and material characterisation

In this work both the interconnections and materials used in multi-chip modules (MCMs) at microwave frequencies have been investigated. The electrical behaviour of the interconnections was studied using commercially available 2.SD and 3D electromagnetic simulators (HFSSTM, MDSTM and Momentum™). State-of-the-art conductive and dielectric film materials used in the fabrication of multi-layer MCM structures were characterized using microstrip/wave guide resonator techniques. The models chosen for simulation of interconnections are commensurate with those in current use in MCM technology. Crosstalk between microstrip conductors in multi-layer MCM structures was simulated and new knowledge leading to new design rules was obtained.Typical elements in MCM interconnect structures, such as vias, bends and airbridges were also investigated. The principal features of these elements were simulated and the results were obtained in S-parameter form. Based on the simulated results, these parasitic elements were modelled in terms of their equivalent circuits which can be used in circuit simulators to aid more rigorous MCM circuit design. A microstrip ring resonator, fabricated using the newly developed conductive material from Heraeus, was employed to measure the line loss. New techniques have been developed to measure the permittivity and loss tangent of thin dielectric films. In the previous methods for the measurement of these films, the accuracy in measuring the relative permittivity is limited and there is no available technique to measure the loss tangent. A novel cavity perturbation method was developed to accurately measure both the relative permittivity and loss tangent of the films deposited on a supporting substrate. An additional independent technique, derived from transmission line theory, for measuring the relative permittivity of dielectric film was also established. A particular feature of the new teclmiques, which led to high accuracy in measuring dielectric constant and loss tangent was the positioning of the dielectric film in the region of maximum electric field strength, thereby ensuring maximum interaction between the electric field and the film material. A rigorous error analysis was performed on the new techniques, which led to the establishment of practical measurement correction factors. A simple and rigorous method has also been developed to accurately measure the loss tangent of dielectrics with known dielectric constant using a resonant cavity. The novel method eliminates the need for any physical measurement of the dielectric sample. The new technique should permit the development of techniques for very high frequency characterisation of dielectric materials

Multi-chip module interconnections at microwave frequencies: electromagnetic simulation and material characterisation

In this work both the interconnections and materials used in multi-chip modules (MCMs) at microwave frequencies have been investigated. The electrical behaviour of the interconnections was studied using commercially available 2.SD and 3D electromagnetic simulators (HFSSTM, MDSTM and Momentum™). State-of-the-art conductive and dielectric film materials used in the fabrication of multi-layer MCM structures were characterized using microstrip/waveguide resonator techniques. The models chosen for simulation of interconnections are commensurate with those in current use in MCM technology. Crosstalk between microstrip conductors in multi-layer MCM structures was simulated and new knowledge leading to new design rules was obtained.Typical elements in MCM interconnect structures, such as vias, bends and airbridges were also investigated. The principal features of these elements were simulated and the results were obtained in S-parameter form. Based on the simulated results, these parasitic elements were modelled in terms of their equivalent circuits which can be used in circuit simulators to aid more rigorous MCM circuit design. A microstrip ring resonator, fabricated using the newly developed conductive material from Heraeus, was employed to measure the line loss. New techniques have been developed to measure the permittivity and loss tangent of thin dielectric films. In the previous methods for the measurement of these films, the accuracy in measuring the relative permittivity is limited and there is no available technique to measure the loss tangent. A novel cavity perturbation method was developed to accurately measure both the relative permittivity and loss tangent of the films deposited on a supporting substrate. An additional independent technique, derived from transmission line theory, for measuring the relative permittivity of dielectric film was also established. A particular feature of the new techniques, which led to high accuracy in measuring dielectric constant and loss tangent was the positioning of the dielectric film in the region of maximum electric field strength, thereby ensuring maximum interaction between the electric field and the film material. A rigorous error analysis was performed on the new techniques, which led to the establishment of practical measurement correction factors. A simple and rigorous method has also been developed to accurately measure the loss tangent of dielectrics with known dielectric constant using a resonant cavity. The novel method eliminates the need for any physical measurement of the dielectric sample. The new technique should permit the development of techniques for very high frequency characterisation of dielectric materials

Tracing masses of ground-state light-quark mesons

We describe a symmetry-preserving calculation of the meson spectrum, which combines a description of pion properties with reasonable estimates of the masses of heavier light-quark mesons, including axial-vector states. The kernels used in formulating the problem are essentially nonperturbative. They incorporate effects of dynamical chiral symmetry breaking (DCSB) that were not previously possible to express. Our analysis clarifies a causal connection between DCSB and the splitting between vector and axial-vector mesons, and exposes a key role played by the anomalous chromomagnetic moment of dressed-quarks in forming the spectrum.Comment: 5 pages, 2 figures, 1 table. To appear in Phys. Rev. C (Rapid Comm.