28,477 research outputs found
String Breaking in Four Dimensional Lattice QCD
Virtual quark pair screening leads to breaking of the string between
fundamental representation quarks in QCD. For unquenched four dimensional
lattice QCD, this (so far elusive) phenomenon is studied using the recently
developed truncated determinant algorithm (TDA). The dynamical configurations
were generated on an Athlon 650 MHz PC. Quark eigenmodes up to 420 MeV are
included exactly in these TDA studies performed at low quark mass on large
coarse (but O() improved) lattices. A study of Wilson line correlators in
Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical
configurations reveals evidence for flattening of the string tension at
distances R approximately 1 fm.Comment: 16 pages, 5 figures, Latex (deleted extraneous eps figure file
Improved Pseudofermion Approach for All-Point Propagators
Quark propagators with arbitrary sources and sinks can be obtained more
efficiently using a pseudofermion method with a mode-shifted action.
Mode-shifting solves the problem of critical slowing down (for light quarks)
induced by low eigenmodes of the Dirac operator. The method allows the full
physical content of every gauge configuration to be extracted, and should be
especially helpful for unquenched QCD calculations. The method can be applied
for all the conventional quark actions: Wilson, Sheikoleslami-Wohlert,
Kogut-Susskind, as well as Ginsparg-Wilson compliant overlap actions. The
statistical properties of the method are examined and examples of physical
processes under study are presented.Comment: LateX, 26 pages, 10 eps figure
Shortcuts to Adiabaticity Assisted by Counterdiabatic Born-Oppenheimer Dynamics
Shortcuts to adiabaticity (STA) provide control protocols to guide the
dynamics of a quantum system through an adiabatic reference trajectory in an
arbitrary prescheduled time. Designing STA proves challenging in complex
quantum systems when the dynamics of the degrees of freedom span different time
scales. We introduce Counterdiabatic Born-Oppenheimer Dynamics (CBOD) as a
framework to design STA in systems with a large separation of energy scales.
CBOD exploits the Born-Oppenheimer approximation to separate the Hamiltonian
into effective fast and slow degrees of freedom and calculate the corresponding
counterdiabatic drivings for each subsystem. We show the validity of the CBOD
technique via an example of coupled harmonic oscillators, which can be solved
exactly for comparison, and further apply it to a system of two-charged
particles.Comment: 14 pages, 3 figures, published New Journal of Physic
Magnetic Properties of Pd_(0.996)Mn_(0.004) Films for High Resolution Thermometry
We have previously reported on the temperature and magnetic field dependence of the magnetic susceptibility of thin Pd_(1−x)Mn_x alloy films. Extensive new measurements on sputtered films show that a commercial quality sputtering process produces a film with the same dependence of Curie temperature on x as previously reported for bulk samples of the same material. These measurements and parameters from the Renormalization Group theory for a Heisenberg ferromagnet, yield an estimate for T_c of 1.16 ± 0.01 K when x − 0.004, consistent with previously reported bulk result
Turning up the lights - fabrication of brighter SERRS nanotags
Brighter SERRS nanotags ideal for improved SERRS imaging were prepared by the controlled addition of electrolyte producing a dimer enriched solution, which was incubated with a Raman reporter before being stabilised by a polyethylene glycol (PEG) shell
Importance of including small body spin effects in the modelling of intermediate mass-ratio inspirals. II Accurate parameter extraction of strong sources using higher-order spin effects
We improve the numerical kludge waveform model introduced in [1] in two ways.
We extend the equations of motion for spinning black hole binaries derived by
Saijo et al. [2] using spin-orbit and spin-spin couplings taken from
perturbative and post-Newtonian (PN) calculations at the highest order
available. We also include first-order conservative self-force corrections for
spin-orbit and spin-spin couplings, which are derived by comparison to PN
results. We generate the inspiral evolution using fluxes that include the most
recent calculations of small body spin corrections, spin-spin and spin-orbit
couplings and higher-order fits to solutions of the Teukolsky equation. Using a
simplified version of this model in [1], we found that small body spin effects
could be measured through gravitational wave observations from
intermediate-mass ratio inspirals (IMRIs) with mass ratio eta ~ 0.001, when
both binary components are rapidly rotating. In this paper we study in detail
how the spin of the small/big body affects parameter measurement using a
variety of mass and spin combinations for typical IMRIs sources. We find that
for IMRI events of a moderately rotating intermediate mass black hole (IMBH) of
ten thousand solar masses, and a rapidly rotating central supermassive black
hole (SMBH) of one million solar masses, gravitational wave observations made
with LISA at a fixed signal-to-noise ratio (SNR) of 1000 will be able to
determine the inspiralling IMBH mass, the central SMBH mass, the SMBH spin
magnitude, and the IMBH spin magnitude to within fractional errors of ~0.001,
0.001, 0.0001, and 9%, respectively. LISA can also determine the location of
the source in the sky and the SMBH spin orientation to within ~0.0001
steradians. We show that by including conservative corrections up to 2.5PN
order, systematic errors no longer dominate over statistical errors for IMRIs
with typical SNR ~1000.Comment: 21 pages, 7 figures. v2: three references added, edits in Sections
II-V, including additional results in Section V to address comments by the
referee. v3: mirrors version accepted to PR
Achieving Good Angular Resolution in 3D Arc Diagrams
We study a three-dimensional analogue to the well-known graph visualization
approach known as arc diagrams. We provide several algorithms that achieve good
angular resolution for 3D arc diagrams, even for cases when the arcs must
project to a given 2D straight-line drawing of the input graph. Our methods
make use of various graph coloring algorithms, including an algorithm for a new
coloring problem, which we call localized edge coloring.Comment: 12 pages, 5 figures; to appear at the 21st International Symposium on
Graph Drawing (GD 2013
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