618 research outputs found
DMRG Study of Critical Behavior of the Spin-1/2 Alternating Heisenberg Chain
We investigate the critical behavior of the S=1/2 alternating Heisenberg
chain using the density matrix renormalization group (DMRG). The ground-state
energy per spin and singlet-triplet energy gap are determined for a range of
alternations. Our results for the approach of the ground-state energy to the
uniform chain limit are well described by a power law with exponent p=1.45. The
singlet-triplet gap is also well described by a power law, with a critical
exponent of p=0.73, half of the ground-state energy exponent. The
renormalization group predictions of power laws with logarithmic corrections
can also accurately describe our data provided that a surprisingly large scale
parameter is present in the logarithm.Comment: 6 pages, 4 eps-figure
âEngage the Worldâ: examining conflicts of engagement in public museums
Public engagement has become a central theme in the mission statements of many cultural institutions, and in scholarly research into museums and heritage. Engagement has emerged as the go-to-it-word for generating, improving or repairing relations between museums and society at large. But engagement is frequently an unexamined term that might embed assumptions and ignore power relationships. This article describes and examines the implications of conflicting and misleading uses of âengagementâ in relation to institutional dealings with contested questions about culture and heritage. It considers the development of an exhibition on the Dead Sea Scrolls by the Royal Ontario Museum, Toronto in 2009 within the new institutional goal to âEngage the Worldâ. The chapter analyses the motivations, processes and decisions deployed by management and staff to âEngage the Worldâ, and the degree to which the museum was able to re-think its strategies of public engagement, especially in relation to subjects,issues and publics that were more controversial in nature
Bibbia, cristianesimo e letteratura italiana: uno sguardo d'assieme.
L'A. ripercorre la presenza della Bibbia nella letteratura italiana dalle origini ai giorni nostri, sottolineando la persistenza della ripresa del Sacro testo sia nella poesia che nella prosa
Meson and tetra-quark mixing
The mixing between q-qbar meson and qqbar-qqbar tetra-quark states is
examined within an effective QCD Coulomb gauge Hamiltonian model. Mixing matrix
elements of the Hamiltonian are computed and then diagonalized yielding an
improved prediction for the low-lying J^{PC} = 0^{+/- +}, 1^{--} isoscalar
spectra. Mixing effects were found significant for the scalar hadrons but not
for the 1^{--} states, which is consistent with the ideal mixing of vector
mesons. A perturbative assessment of the exact QCD kernel is also reported.Comment: 7 pages, 6 figure
Instantons and Scalar Multiquark States: From Small to Large N_c
We study scalar quark-anti-quark and two-quark-two-anti-quark correlation
functions in the instanton liquid model. We show that the instanton liquid
supports a light scalar-isoscalar (sigma) meson, and that this state is
strongly coupled to both and . The scalar-isovector
meson, on the other hand, is heavy. We also show that these properties
are specific to QCD with three colors. In the large limit the
scalar-isoscalar meson is not light, and it is mainly coupled to .Comment: 24 page
Low Energy Theory for 2 flavors at High Density QCD
We construct the effective Lagrangian describing the low energy excitations
for Quantum Chromodynamics with two flavors at high density. The non-linear
realization framework is employed to properly construct the low energy
effective theory. The light degrees of freedom, as required by 't Hooft anomaly
conditions, contain massless fermions which we properly include in the
effective Lagrangian. We also provide a discussion of the linearly realized
Lagrangian.Comment: 17 pages, RevTeX format, references added. To appear in Phys. Rev.
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Brookhaven Fastbus/Unibus Interface
A typical high energy physics experiment requires both a high speed data acquisition and processing system, for data collection and reduction; and a general purpose computer to handle further reduction, bookkeeping and mass storage. Broad differences in architecture, format or technology, will often exist between these two systems, and interface design can become a formidable task. The PDP-11 series minicomputer is widely used in physics research, and the Brookhaven FASTBUS is the only standard high speed data acquisition system which is fully implemented in a current high energy physics experiment. This paper will describe the design and operation of an interface between these two systems. The major issues are elucidated by a preliminary discussion on the basic principles of Bus Systems, and their application to Brookhaven FASTBUS and UNIBUS
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Brookhaven Segment Interconnect
We have performed a high energy physics experiment using a multisegment Brookhaven FASTBUS system. The system was composed of three crate segments and two cable segments. We discuss the segment interconnect module which permits communication between the various segments
Is there anybody out there? Occupancy of the carnivore guild in a temperate archipelago
Carnivores are important components of ecological communities with wide-ranging effects that vary with carnivore size, natural history, and hunting tactics. Researchers and managers should strive to understand both the presence and distribution of carnivores within their local environment. We studied the carnivore guild in the Apostle Islands, where the distribution and occupancy of carnivores was largely unknown. We monitored 19 islands with 160 functioning camera traps from 2014-2017, from which we collected 203,385 photographs across 49,280 trap nights. We documented 7,291 total wildlife events with 1,970 carnivore events, and detected 10 of the 12 terrestrial carnivores found in Wisconsin. Detection rates for species were generally higher in summer than winter, except for coyotes (Canis latrans) and red foxes (Vulpes vulpes). Finitesample occupancy estimates for carnivores varied across islands, with mean estimated occupancy across islands varying from a high of 0.73 for black bears to a low of 0.21 for gray wolves. Of the potential island biogeography explanatory variables for carnivore occupancy we considered, island size was the most important, followed by distance to the mainland, and then interisland distance. We estimated that terrestrial carnivore species varied in the number of islands they were detected on from 1 island for gray wolves to 13 islands for black bears. Estimated carnivore richness across islands (i.e., the number of carnivores occupying an island) also varied substantively from 1 species on Michigan Island to 10 species on Stockton Island. Island size and connectivity between islands appear important for the persistence of the carnivore community in the Apostle Islands
Meson-Meson Scattering in the Quark Model: Spin Dependence and Exotic Channels
We apply a quark interchange model to spin-dependent and exotic meson-meson
scattering. The model includes the complete set of standard quark model forces,
including OGE spin-orbit and tensor and scalar confinement spin-orbit.
Scattering amplitudes derived assuming SHO and Coulomb plus linear plus
hyperfine meson wavefunctions are compared. In I=2 pi pi we find approximate
agreement with the S-wave phase shift from threshold to 1.5 GeV, where we
predict an extremum that is supported by the data. Near threshold we find rapid
energy dependence that may reconcile theoretical estimates of small scattering
lengths with experimental indications of larger ones based on extrapolation of
measurements at moderate kpi^2. In PsV scattering we find that the quark-quark
L*S and T forces map into L*S and T meson-meson interactions, and the P-wave
L*S force is large. Finally we consider scattering in J^PC-exotic channels, and
note that some of the Deck effect mechanisms suggested as possible nonresonant
origins of the pi_1(1400) signal are not viable in this model.Comment: 51 pages, 10 figures, uses epsf.sty epsfig.st
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