307 research outputs found
The three flavour chiral phase transition with an improved quark and gluon action in lattice QCD
The finite-temperature chiral phase transition is investigated for three
flavours of staggered quarks on a lattice of temporal extent N_t=4. In the
simulation we use an improved fermion action which reduces rotational symmetry
breaking of the quark propagator (p4-action), include fat-links to improve the
flavour symmetry and use the tree level improved (1,2) gluon action. We study
the nature of the phase transition for quark masses of ma=0.025, ma=0.05 and
ma=0.1 on lattices with spatial sizes of 8^3 and 16^3.Comment: LATTICE98(hightemp), 3 pages, 7 figures, LaTeX2e-File, espcrc2.st
String Tension and Thermodynamics with Tree Level and Tadpole Improved Actions
We calculate the string tension, deconfinement transition temperature and
bulk thermodynamic quantities of the SU(3) gauge theory using tree level and
tadpole improved actions. Finite temperature calculations have been performed
on lattices with temporal extent N_tau = 3 and 4. Compared to calculations with
the standard Wilson action on this size lattices we observe a drastic reduction
of the cut-off dependence of bulk thermodynamic observables at high
temperatures. In order to test the influence of improvement on long-distance
observables at T_c we determine the ratio T_c/sqrt(sigma). For all actions,
including the standard Wilson action, we find results which differ only little
from each other. We do, however, observe an improved asymptotic scaling
behaviour for the tadpole improved action compared to the Wilson and tree level
improved actions.Comment: 20 pages, LaTeX2e File, 8 coloured Postscript figures, new analysis
added, recent Wilson action string tension results included, figures replace
Staggered Fermion Actions with Improved Rotational Invariance
We introduce a class of improved actions for staggered fermions which to
O(p^4) and O(p^6), respectively, lead to rotationally invariant propagators. We
discuss the resulting reduction of flavour symmetry breaking in the meson
spectrum and comment on the improvement in the calculation of thermodynamic
observables.Comment: 3 pages and 4 figures, Contribution to Lattice 97 (Poster Session),
late
The string tension in SU(N) gauge theory from a careful analysis of smearing parameters
We report a method to select optimal smearing parameters before production
runs and discuss the advantages of this selection for the determination of the
string tension.Comment: Contribution to Lat97 poster session, title was 'How to measure the
string tension', 3 pages, 5 colour eps figure
QCD Thermodynamics with Improved Actions
The thermodynamics of the SU(3) gauge theory has been analyzed with tree
level and tadpole improved Symanzik actions. A comparison with the continuum
extrapolated results for the standard Wilson action shows that improved actions
lead to a drastic reduction of finite cut-off effects already on lattices with
temporal extent . Results for the pressure, the critical temperature,
surface tension and latent heat are presented. First results for the
thermodynamics of four-flavour QCD with an improved staggered action are also
presented. They indicate similarly large improvement factors for bulk
thermodynamics.Comment: Talk presented at LATTICE96(finite temperature) 4 pages, LaTeX2e
file, 6 eps-file
SU(3) Latent Heat and Surface Tension from Tree Level and Tadpole Improved Actions
We analyze the latent heat and surface tension at the SU(3) deconfinement
phase transition with tree level and tadpole improved Symanzik actions on
lattices with temporal extent and 4 and spatial extent , 6 and 8. In comparison to the standard Wilson action we do find a
drastic reduction of cut-off effects already with tree level improved actions.
On lattices with temporal extent results for the surface tension and
latent heat obtained with a tree level improved action agree well with those
obtained with a tadpole improved action. A comparison with
calculations, however, shows that results obtained with tadpole action remain
unaffected by cut-off effects even on this coarse lattice, while the tree level
action becomes sensitive to the cut-off. For the surface tension and latent
heat we find and , respectively.Comment: 11 pages, LaTeX2e File, 3 Postscript figure
An exploratory study on the role of serum fatty acids in the short-term dietary therapy of gingivitis.
A previous randomised controlled trial showed that an anti-inflammatory diet (AID) significantly reduced gingival inflammation despite constant plaque values. This exploratory study investigated the role of serum fatty acids in relation to the observed clinical effects. Therefore, data of thirty participants with gingivitis, following either a pro-inflammatory dietary pattern (PID) rich in saturated fat, omega 6 fatty acids, and refined carbohydrates or an AID for 4 weeks, were correlated with corresponding serum samples for a variety of fatty acids. Changes in the fatty acid profile and effects on clinical periodontal parameters were analysed. Results showed that the polyunsatured:saturated fatty acids ratio (PUFA:SFA ratio) and nervonic acid level were significantly higher in the AID group than in the PID group at the end of the study. Significant intragroup differences were seen only in the AID group. Diverse fatty acids showed heterogeneous relations to clinical parameters. This study demonstrated that the serum fatty acid profile was not fundamentally associated with the clinical gingivitis-lowering effects of an AID in short-term, although some fatty acids showed individual relations to clinical parameters with respect to inflammation. Hence, short-term effects of dietary therapy on gingivitis may be rather based on carbohydrate-related effects and/or micronutrients
Improved staggered quark actions with reduced flavour symmetry violations for lattice QCD
We introduce a new class of actions for staggered quarks in lattice QCD which
significantly reduce flavour symmetry violations in the pion mass spectrum. An
action introduced by the MILC collaboration for the same purpose is seen to be
a special case. We discus how such actions arise from a systematic attempt to
reduce flavour symmetry violations in the weak coupling limit. It is shown that
for quenched lattice QCD at 6/g^2=5.7, representative actions of this class
give a considerable reduction in flavour symmetry violation over the standard
staggered action, and a significant reduction over what is achieved by the MILC
action.Comment: RevTeX 18 pages with 3 postscript figure
Large FHE Gates from tensored homomorphic accumulator
The main bottleneck of all known Fully Homomorphic Encryption schemes lies in the bootstrapping procedure invented by Gentry (STOC’09). The cost of this procedure can be mitigated either using Homomorphic SIMD techniques, or by performing larger computation per bootstrapping procedure.In this work, we propose new techniques allowing to perform more operations per bootstrapping in FHEW-type schemes (EUROCRYPT’13). While maintaining the quasi-quadratic Õ(n2) complexity of the whole cycle, our new scheme allows to evaluate gates with Ω(log n) input bits, which constitutes a quasi-linear speed-up. Our scheme is also very well adapted to large threshold gates, natively admitting up to Ω(n) inputs. This could be helpful for homomorphic evaluation of neural networks.Our theoretical contribution is backed by a preliminary prototype implementation, which can perform 6-to-6 bit gates in less than 10s on a single core, as well as threshold gates over 63 input bits even faster.<p
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