Steven Weinberg's productive scientific life teaches us many things, one of the most important of which is the power of his example. This essay contains personal reminiscences and a speculation about gravitational wave propagation based on one of his very last papers – as seems fitting, given his penchant for putting interesting physics into the essays he wrote for other luminaries over the years. (See <cross-ref refid='br0010' id='crf0040'>[1]</cross-ref> for a less personal summary of his main scientific accomplishments.)

Canada

Ireland

C.P. Burgess

Reminiscences about Steven Weinberg (this time it's personal)

Steven Weinberg was a giant of late 20th Century physics on whose shoulders we stand while groping for the science of the 21st Century. This article provides a too-brief summary of a selection of his many achievements – eight decades of superlative research, eight classic textbooks, eight best-selling forays into popular science writing and more. <cross-ref refid='fn0010' id='crf0060'><sup>1</sup></cross-ref>

United Arab Emirates

United Kingdom

F. Quevedo

Steven Weinberg: A scientific life

I am gladly sharing a few anecdotes of my interactions with Steven Weinberg during many years, from my student days to more recent times.

United States

Carlos R. Ordóñez

Steven Weinberg remembrances

The standard formulation of parton physics involves light-cone correlations of quark and gluon fields in a hadron, which leads to a widespread impression that it can only be studied through real-time Hamiltonian dynamics or light-front quantization, which are challenged by non-perturbative computations with a pertinent regulator for light-cone/rapidity divergences (or zero modes). As such, standard lattice QCD studies have been limited to indirect parton observables such as first few moments and short-distance correlations, which do not provide the x-distributions without solving the model-dependent inverse problem. Here I describe an alternative formulation of partons in terms of equal-time (or Euclidean) correlators, which allows to compute precision-controlled x-distribution through lattice QCD simulations. This approach is in accord with Weinberg's pioneering idea of effective field theory as well as Wilson's renormalization group, in which the large hadron momentum serves as a natural cut-off for light-cone/rapidity divergences and can ultimately be eliminated through a method like the “perfect action” program in lattice QCD.

Xiangdong Ji

Euclidean effective theory for partons in the spirit of Steven Weinberg

My personal recollections are presented regarding my interactions with Steven Weinberg and the impact he had in my career from when I was his graduate student until the present.

CERN

Fernando Quevedo

Personal reminiscences of Steven Weinberg

Gian Francesco Giudice

Remembering Steven Weinberg

Italy

Luciano Maiani

Steven Weinberg: Philosophy, cosmology and social writings

I review and improve on how two-index SU(N) gauge-fermion theories help access salient information about the large N vacuum and spectrum of QCD, super Yang Mills and meson-meson scattering. The interplay with recent lattice simulations will be employed to deduce the size of <math><mn>1</mn><mo>/</mo><msup><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msup></math> corrections. Through the meson-meson scattering analysis I will honor Steven Weinberg's memory by showing how two-index extrapolations naturally accommodate the appearance of tetraquarks states crucial to unitarize meson-meson scattering at low energies.

Denmark

Francesco Sannino

Two-index SU(N) theories from one flavor QCD to Steven Weinberg's Scattering Legacy

As a tribute to Steven Weinberg, we summarize the immense impact that he had on the understanding of the mechanism of spontaneous symmetry breaking and on the physics of the Higgs boson. In particular, four landmark contributions to this field are highlighted. A first one is his early work with Goldstone and Salam on spontaneously broken continuous symmetries that paved the way to the Higgs mechanism. A second towering breakthrough is his model of leptons which later became the Standard Model of particle physics and for which he was awarded the Nobel prize with Glashow and Salam. A third seminal work is the so-called Weinberg-Linde lower bound on the Higgs boson mass that was derived from the requirement of the stability of the electroweak vacuum. Finally, we summarize his important contributions in model-building of new physics with extended Higgs sectors and their possible impact in flavor physics and CP-violation. The historical aspects as well as the contemporary way of viewing these four major topics are summarized and their impact on today Higgs physics, and more generally particle physics, is highlighted.

Spain

Abdelhak Djouadi

José Ignacio Illana

Steven Weinberg and Higgs physics

A brief discussion of my interactions with Steven Weinberg and the impact of his research and those interactions on my own work.