12,410 research outputs found
Fermion Systems in Discrete Space-Time
Fermion systems in discrete space-time are introduced as a model for physics
on the Planck scale. We set up a variational principle which describes a
non-local interaction of all fermions. This variational principle is symmetric
under permutations of the discrete space-time points. We explain how for
minimizers of the variational principle, the fermions spontaneously break this
permutation symmetry and induce on space-time a discrete causal structure.Comment: 8 pages, LaTeX, few typos corrected (published version
Does IT standardization help to boost cost and profit efficiency? Empirical evidence from German savings banks
This paper investigates the impact of IT standardization on bank performance based on a panel of 457 German savings banks over the period from 1996 to 2006. We measure IT standardization as the fraction of IT expenses for centralized services over banks' total IT expenses. Bank efficiency, in turn, is measured by traditional accounting performance indicators as well as by cost and profit efficiencies that are estimated by a stochastic frontier approach. Our results suggest that IT standardization is conducive to cost efficiency. The relation is positive and robust for small and medium-sized banks but vanishes for very large banks. Furthermore, our study confirms the often cited computer paradox by showing that total IT expenditures negatively impact cost efficiency and have no influence on bank profits. To the best of our knowledge, this paper is first to empirically explore whether IT standardization enhances efficiency by employing genuine data of banks' IT expenditures. JEL Classification: C23, G21 Keywords: IT standardization, cost and profit efficiency, savings bank
The Nonequilibrium Thermodynamics of Small Systems
The interactions of tiny objects with their environment are dominated by
thermal fluctuations. Guided by theory and assisted by micromanipulation tools,
scientists have begun to study such interactions in detail.Comment: PDF file, 13 pages. Long version of the paper published in Physics
Toda
Dynamical AC study of the critical behavior in Heisenberg spin glasses
We present some numerical results for the Heisenberg spin-glass model with
Gaussian interactions, in a three dimensional cubic lattice. We measure the AC
susceptibility as a function of temperature and determine an apparent finite
temperature transition which is compatible with the chiral-glass temperature
transition for this model. The relaxation time diverges like a power law
with and . Although our
data indicates that the spin-glass transition occurs at the same temperature as
the chiral glass transition, we cannot exclude the possibility of a chiral-spin
coupling scenario for the lowest frequencies investigated.Comment: 7 pages, 4 figure
Timescales in the quench dynamics of many-body quantum systems: Participation ratio vs out-of-time ordered correlator
We study quench dynamics in the many-body Hilbert space using two isolated
systems with a finite number of interacting particles: a paradigmatic model of
randomly interacting bosons and a dynamical (clean) model of interacting
spins-. For both systems in the region of strong quantum chaos, the number
of components of the evolving wave function, defined through the number of
principal components (or participation ratio), was recently found to
increase exponentially fast in time [Phys. Rev. E 99, 010101R (2019)]. Here, we
ask whether the out-of-time ordered correlator (OTOC), which is nowadays widely
used to quantify instability in quantum systems, can manifest analogous
time-dependence. We show that can be formally expressed as the inverse
of the sum of all OTOC's for projection operators. While none of the individual
projection-OTOC's shows an exponential behavior, their sum decreases
exponentially fast in time. The comparison between the behavior of the OTOC
with that of the helps us better understand wave packet dynamics in
the many-body Hilbert space, in close connection with the problems of
thermalization and information scrambling.Comment: 11 pages, 7 figure
Recommended from our members
A Universal Live Cell Barcoding-Platform for Multiplexed Human Single Cell Analysis.
Single-cell barcoding enables the combined processing and acquisition of multiple individual samples as one. This maximizes assay efficiency and eliminates technical variability in both sample preparation and analysis. Remaining challenges are the barcoding of live, unprocessed cells to increase downstream assay performance combined with the flexibility of the approach towards a broad range of cell types. To that end, we developed a novel antibody-based platform that allows the robust barcoding of live human cells for mass cytometry (CyTOF). By targeting both the MHC class I complex (beta-2-microglobulin) and a broadly expressed sodium-potassium ATPase-subunit (CD298) with platinum-conjugated antibodies, human immune cells, stem cells as well as tumor cells could be multiplexed in the same single-cell assay. In addition, we present a novel palladium-based covalent viability reagent compatible with this barcoding strategy. Altogether, this platform enables mass cytometry-based, live-cell barcoding across a multitude of human sample types and provides a scheme for multiplexed barcoding of human single-cell assays in general
Universal dual amplitudes and asymptotic expansions for and in four dimensions
Though the one-loop amplitudes of the Higgs boson to massless gauge bosons
are finite because there is no direct interaction at tree-level in the Standard
Model, a well-defined regularization scheme is still required for their correct
evaluation. We reanalyze these amplitudes in the framework of the
four-dimensional unsubtraction and the loop-tree duality (FDU/LTD), and show
how a local renormalization solves potential regularization ambiguities. The
Higgs boson interactions are also used to illustrate new additional advantages
of this formalism. We show that LTD naturally leads to very compact integrand
expressions in four space-time dimensions of the one-loop amplitude with
virtual electroweak gauge bosons. They exhibit the same functional form as the
amplitudes with top quarks and charged scalars, thus opening further
possibilities for simplifications in higher-order computations. Another
outstanding application is the straightforward implementation of asymptotic
expansions by using dual amplitudes. One of the main benefits of the LTD
representation is that it is supported in a Euclidean space. This
characteristic feature naturally leads to simpler asymptotic expansions.Comment: 11 pages, no figures. Minor modifications, discussion improved. Final
version published in EPJ
- …