Search for Chargino-Neutralino Pair Production at CDF

We present the results of a search for associated production of the lightest chargino and next-to-lightest neutralino using 1 fb$^{-1}$ of $\sqrt s$ = 1.96 TeV p$\rm \bar p$ data collected with the CDF detector at the Tevatron. We combine the results of several multi-lepton final states to set upper limits on the cross section times branching ratio for chargino-neutralino production as a function of the chargino mass.Comment: Submitted for the SUSY07 proceedings, 3 pages, LaTeX, 6 eps figure

\u27La Maggior Porcheria Del Mondo\u27: Documents for Ammannati\u27s Neptune Fountain

The story of the creation of the Neptune Fountain on the Piazza della Signoria in Florence is long and tortuous. Scholars have drawn on a wealth of documentary material regarding the competition for the commission, the various phases of the fountain\u27s construction, and the critical reception of its colossus, both political and aesthetic. A collection of unpublished letters at the Getty Research Center in Los Angeles offers a new perspective on the making of this major public monument. Sent by Bartolomeo Ammannati to the prvveditore of Pisa, they chronicle the artist\u27s involvement in the procurement and transportation of marble from Carrara and Seravezza for the chariot and basin of the fountain during the years 1565-73. The correspondence, excerpts from which are published here, shows that Ammannati faced numerous delays and mishaps, and continual pressure from his patrons during this second phase of the fountain\u27s construction. The letters provide further insight into the personality of one of the most important artists at the court of Duke Cosimo I, whose role required the skills of a project manager and negotiator. The commission for a grandiose fountain in Florence\u27s main square took much longer to complete than had been expected and taxed the artist\u27s patience, persistence and resourcefulness. [excerpt

Crystalline topological phases as defect networks

A crystalline topological phase is a topological phase with spatial symmetries. In this work, we give a very general physical picture of such phases: a topological phase with spatial symmetry $G$ (with internal symmetry $G_{\mathrm{int}} \leq G$) is described by a *defect network*: a $G$-symmetric network of defects in a topological phase with internal symmetry $G_{\mathrm{int}}$. The defect network picture works both for symmetry-protected topological (SPT) and symmetry-enriched topological (SET) phases, in systems of either bosons or fermions. We derive this picture both by physical arguments, and by a mathematical derivation from the general framework of [Thorngren and Else, Phys. Rev. X 8, 011040 (2018)]. In the case of crystalline SPT phases, the defect network picture reduces to a previously studied dimensional reduction picture, thus establishing the equivalence of this picture with the general framework of Thorngren and Else applied to crystalline SPTs.Comment: 13 pages + 2 pages of appendices. v3 published version, with better justification of the equivalence relatio

Pre-thermal phases of matter protected by time-translation symmetry

In a periodically driven (Floquet) system, there is the possibility for new phases of matter, not present in stationary systems, protected by discrete time-translation symmetry. This includes topological phases protected in part by time-translation symmetry, as well as phases distinguished by the spontaneous breaking of this symmetry, dubbed "Floquet time crystals". We show that such phases of matter can exist in the pre-thermal regime of periodically-driven systems, which exists generically for sufficiently large drive frequency, thereby eliminating the need for integrability or strong quenched disorder that limited previous constructions. We prove a theorem that states that such a pre-thermal regime persists until times that are nearly exponentially-long in the ratio of certain couplings to the drive frequency. By similar techniques, we can also construct stationary systems which spontaneously break *continuous* time-translation symmetry. We argue furthermore that for driven systems coupled to a cold bath, the pre-thermal regime could potentially persist to infinite time.Comment: Published version, with new title and introductio

The "Building Blocks" of Stellar Halos

The stellar halos of galaxies encode their accretion histories. In particular, the median metallicity of a halo is determined primarily by the mass of the most massive accreted object. We use hydrodynamical cosmological simulations from the APOSTLE project to study the connection between the stellar mass, the metallicity distribution, and the stellar age distribution of a halo and the identity of its most massive progenitor. We find that the stellar populations in an accreted halo typically resemble the old stellar populations in a present-day dwarf galaxy with a stellar mass $\sim 0.2-0.5$ dex greater than that of the stellar halo. This suggest that had they not been accreted, the primary progenitors of stellar halos would have evolved to resemble typical nearby dwarf irregulars.Comment: 7 pages, 3 figures, published in the proceedings of "On the Origin (and Evolution) of Baryonic Galaxy Halos", Puerto Ayora, Ecuador, March 13-17 2017, Eds. Duncan A. Forbes and Ericson D. Lope

Bursting the bubble or opening the door? Appraising the impact of austerity on playwork and playwork practitioners in the UK

Introductory essay for special issue on 'Playwork in Times of Austerity

Chemical enrichment in very low-metallicity environments: Bootes I

We present different chemical evolution models for the ultrafaint dwarf galaxy Bootes I. We either assume that the galaxy accretes its mass through smooth infall of gas of primordial chemical composition (classical models) or adopt mass accretion histories derived from the combination of merger trees with semi-analytical modelling (cosmologically-motivated models). Furthermore, we consider models with and without taking into account inhomogeneous mixing in the ISM within the galaxy. The theoretical predictions are then compared to each other and to the body of the available data. From this analysis, we confirm previous findings that Bootes I has formed stars with very low efficiency but, at variance with previous studies, we do not find a clear-cut indication that supernova explosions have sustained long-lasting galactic-scale outflows in this galaxy. Therefore, we suggest that external mechanisms such as ram pressure stripping and tidal stripping are needed to explain the absence of neutral gas in Bootes I today.Comment: 13 pages, 11 figures, accepted for publication in MNRA