Abstract This chapter tackles the concept of quarks beyond those found in the familiar protons, neutrons, and pions. A strange baryon consists of three quarks at least one of which is a strange quark, while a strange meson contains either a strange quark or a strange antiquark. The properties of the variety of strange particles led theorists to invent the concept of strangeness. The chapter explains how processes were favoured or disfavoured by computing how much strangeness each of the participating particles carried. It also considers the heavier charm bottom and top quarks and the three varieties of neutrino, which have exceedingly small masses compared to electron mass.

Abstract This chapter covers the development of cosmic and man-made accelerators. It explains that electrically charged particles are accelerated by electric forces, and how applying enough electric force to an electron will allow that electron to go faster and faster in a straight line. The idea of creating a ring-shaped accelerator originated with Ernest Lawrence, who used a magnetic field to bend the particles into a circular orbit. The chapter then details the function of the Large Hadron Collider, Stanford Linear Accelerator, Cosmotron, and cyclotron. It notes how the difference between matter and antimatter resulted in the interest in the properties of strange particles and antiparticles called kaons.

Abstract Particle Physics: A Very Short Introduction takes a journey into the atom and presents an overview of the fundamental particles and forces that make up the universe. The VSI discusses the features and functions of particles such as quarks, electrons, and neutrinos, and of gluons and bosons. It includes the key role and significance of the Higgs boson in moulding these foundational elements and giving structure to matter. It highlights how discoveries in particle physics were made and have radically changed understanding of the material universe. The book concludes by considering the implications of the discovery of the Higgs boson, and asks whether massive neutrinos might be key to resolving the mystery surrounding the absence of antimatter.

D.Barberis,W .Beusch,F.G.Binon,A.M .Blick,F.E.Close,K.M .Danielsen, A.V.Dolgopolov,S.V.Donskov,B.C.Earl,D.Evans,B.R.French,T.Hino,S.Inaba, A.V.Inyakin,T.Ishida,A.Jacholkowski,T.Jacobsen,G.T Jones,G.V.Khaustov, T.Kinashi,J.B.Kinson,A.Kirk,W .Klem pt,V.Kolosov,A.A.Kondashov, A.A.Lednev,V.Lenti,S.M aljukov,P.M artinengo,I.M inashvili,T.Nakagawa, K.L.Norm an,J.P.Peigneux,S.A.Polovnikov,V.A.Polyakov,V.Rom anovsky, H.Rotscheidt,V.Rum yantsev,N.Russakovich,V.D.Sam oylenko,A.Sem enov,M .Sen e, R.Sen e,P.M .Shagin,H.Shim izu,A.V.Singovsky,A.Sobol,A.Solovjev, M .Stassinaki,J.P.Stroot,V.P.Sugonyaev,K.Takam atsu,G.Tchlatchidze,T.Tsuru, M .Venables,O.VillalobosBaillie,M .F.Votruba,Y.Yasu.

In response to Margaret Harris’ review “A critical mass of secrets” (February 2020) of Frank Close’s latest book Trinity: the Treachery and Pursuit of the Most Dangerous Spy in History, which tells the story of physicist and committed communist Klaus Fuchs.

In reply to Matin Durrani's editorial on "Tasty physics" (November p19) in which he stated that "particle physicists achieve many things, but tackling the world's obesity crisis is not something they can ever hope to address".

LHCb measurements of B-d,B-s -> J/psi + X are shown to be consistent with historical data on scalar and axial mesons below 2 GeV. This is in contrast to some recent interpretations of these data. Further tests of our hypotheses in other B-u,B-d,B-s -> J/psi + X decay modes are suggested.

Charm meson molecule $(c\overline{n})(n\overline{c})$ assignments for the supercharmonium state1 Z(4475) are considered, both on general grounds and in the context of specific pion-exchange models. Two possible charm molecule assignments for the ${\mathrm{J}}^{\mathrm{P}}={1}^{+}$ Z(4475) are considered here, involving respectively a radially and an orbitally excited charm meson. In each assignment, a lower-mass isosinglet charm molecule state is predicted. For both the Z(4475) and the Y(4260), measurement of the ratios of the branching fractions to $\mathrm{D}\overline{\mathrm{D}}$ plus $n$ pions is recommended as a test of the nature of these states.

a conclusion borne out by remarks by Professor Gan in his preface to the Book Series. Having briefly surveyed the scope of Chinese activities in archaeology and science, he observes that it ‘is not advisable to carry out studies behind closed doors ... We must face the external world ... in order to let China be known and understood by the world and thereby acquire an international right to speak.’ If this volume is an exemplar of how China will speak to the world, then the world will be ready to listen. The book is unusual, particularly as an edited volume, in being very personal. There is one obvious factor in this respect: 11 of the book’s 20 chapters have been authored by Professor Gan himself. This is highly appropriate since he has a personal link with the early developments of modern optics in China. In the early decades of the twentieth century, many Chinese scientists were enabled to gain research experience abroad – particularly in Europe and the US. As he began his scientific activities, Professor Gan came to know many of those working in optics and shares his knowledge of their personalities and activities with us. One striking feature of many of these pioneers is their longevity – typically living into their 80s and 90s – thereby enhancing their influence as optics activities developed in China. Professor Gan follows in that tradition. In addition to the refreshingly personal accounts included here, there is an honesty about the impact of various changes in China and elsewhere on scientific progress. Here, acknowledgement is made of the effect of the ‘Cultural Revolution’ in delaying appreciation of laser technologies. Conversely, the ‘Strategic Defence Initiative’ of US President Reagan led to the so-called 863 programme in China which led to a more industrially focused use of laser technologies including optical fibre communications. Of course Charles Kuen Kao receives a roll call in that respect, as does Dr. Tingye Li of Bell Labs. Although the focus of this book is twentieth century optics and optoelectronics, the reader is given a brief overview of the historical context. Moreover, the book includes considerations of astronomical optical instruments, atomic clocks and laser fusion. A number of contributors tell us their life stories in optics. As such, this is an extremely accessible volume which ‘informs, educates and enlightens’. One hopes that other volumes in this series, when they appear, will similarly excite their target readers. Finally, one must note that even on publication, the editors of this book signal that there are gaps in the coverage which will be rectified in a future edition. One suspects that some of those gaps will be filled by researchers who are inspired by the achievements of their predecessors.

‘Making and breaking nuclei’ describes the process by which the atomic elements came to be in the early universe. The heat energy in the big bang, some 13.7 billion years ago, converted into counterbalanced particles of matter and antimatter. The seeds of atomic nuclei were initially the simplest constituents: quarks. During the last 5 billion years, the majority of elements found on earth were formed inside a long-dead star, where they were all cooked from protons, which were synthesised within the first second of the universe. The processes of stellar nucleosynthesis, the CNO cycle, supernovae nucleosynthesis, and cosmic spallation are explained along with the dating of the age of the Earth.

Beautiful though it is, symmetry is not half as intriguing as the alternative. Physicist Frank Close tours the cosmos to show us why

This proposal presents our plan to make a precision measurement of the charged pion polarizability απ − βπ through measurements of γγ → π+π− cross sections using the GlueX detector in Hall D. The accuracy of the proposed measurement is estimated at 10%, with an absolute error in α−β of ±0.6× 10−4fm3. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. A measurement of the pion polarizability tests fundamental symmetries in the intrinsic even-parity sector of QCD.

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in γ p collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic J^PC, corresponding to qq̅ states (q=u, d, or s) coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and ±1, and both isoscalar members, |ss̅ > and |uu̅ > + |dd̅ >, for each predicted hybrid combination of J^PC, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. Detailed studies of the performance of the detector have indicated that identification of particular final states with kaons is possible using the baseline detector configuration. The efficiency of kaon detection coupled with the relatively lower production cross section for particles containing hidden strangeness will require a high intensity run in order for analyses of such states to be feasible. We propose to collect a total of 200 days of physics analysis data at an average intensity of 5× 10^7 tagged photons on target per second. This data sample will provide an order of magnitude statistical improvement over the initial GlueX running, which will allow us to begin a program of studying mesons and baryons containing strange quarks. In addition, the increased intensity will permit us to study reactions that may have been statistically limited in the initial phases of GlueX. Overall, this will lead to a significant increase in the potential for to make key experimental advances in our knowledge of hybrid mesons and excited Ξ baryons.

The announced discovery of the Higgs boson at CERN's Large Hadron Collider on July 4 is described, put into context, and its implications assessed.

Frank Close enjoys the life of Hans Bethe, a Manhattan Project veteran who probed the hearts of stars.