9,233 research outputs found
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 of = 1.96
TeV 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 A collection of unpublished letters at the Getty Research Center in Los Angeles offers a new perspective on the making of this major public monument.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 (with internal symmetry
) is described by a *defect network*: a -symmetric
network of defects in a topological phase with internal symmetry
. 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
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
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
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
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