1,146 research outputs found
Ground state charmed meson spectra for N_f=2+1+1
We present a preliminary study of the charmed meson spectra using the
electrically neutral subset of the new Budapest-Marseille-Wuppertal N_f=2+1+1
gauge configurations that utilise the 3-HEX smeared clover action. The analysis
is performed with a focus on the hyperfine splitting.Comment: 7 pages, 5 figures; presentation given at the 33rd International
Symposium on Lattice Field Theory (Lattice 2015), 14 - 18 July 2015, Kobe,
Japa
Dynamic percolation theory for particle diffusion in a polymer network
Tracer-diffusion of small molecules through dense systems of chain polymers
is studied within an athermal lattice model, where hard core interactions are
taken into account by means of the site exclusion principle. An approximate
mapping of this problem onto dynamic percolation theory is proposed. This
method is shown to yield quantitative results for the tracer correlation factor
of the molecules as a function of density and chain length provided the
non-Poisson character of temporal renewals in the disorder configurations is
properly taken into account
Freestores: What, Why, and How
Everyone seems to generate some sort of unwanted possession over the years, whether it be clothes they no longer wear, appliances they no longer use, or books they no longer read. While throwing unwanted items like this away in the trash is convenient and simple, it adds to the amount of solid waste found in landfills and the natural environment. Furthermore, it wastes potentially valuable resources that could be used by others.
A viable alternative to disposing of unwanted possessions in the trash is to donate them to a freestore to be used by others, or if one does not already exist in your area, implementing one for the benefit of the community
Chiral anomalies and rooted staggered fermions
A popular approximation in lattice gauge theory is an extrapolation in the
number of fermion species away from the four fold degeneracy natural with the
staggered fermion formulation. I show that the extrapolation procedure
mutilates the expected continuum holomorphic behavior in the quark masses. The
conventional resolution proposes canceling the unphysical singularities with a
plethora of extra states appearing at finite lattice spacing. This unproven
conjecture requires an explicit loss of unitarity and locality. Even if
correct, the approach implies large cutoff effects in the low-energy
flavor-neutral sector.Comment: 10 pages, no figures; revision includes various clarifications, a
changed title, and an additional reference; version to appear in Physics
Letters
The ratio FK/Fpi in QCD
We determine the ratio FK/Fpi in QCD with Nf=2+1 flavors of sea quarks, based
on a series of lattice calculations with three different lattice spacings,
large volumes and a simulated pion mass reaching down to about 190 MeV. We
obtain FK/Fpi=1.192 +/- 0.007(stat) +/- 0.006(syst). This result is then used
to give an updated value of the CKM matrix element |Vus|. The unitarity
relation for the first row of this matrix is found to be well observed.Comment: 15 pages, 4 figures, 2 table
Precision computation of the kaon bag parameter
Indirect CP violation in K \rightarrow {\pi}{\pi} decays plays a central role
in constraining the flavor structure of the Standard Model (SM) and in the
search for new physics. For many years the leading uncertainty in the SM
prediction of this phenomenon was the one associated with the nonperturbative
strong interaction dynamics in this process. Here we present a fully controlled
lattice QCD calculation of these effects, which are described by the neutral
kaon mixing parameter B_K . We use a two step HEX smeared clover-improved
Wilson action, with four lattice spacings from a\approx0.054 fm to
a\approx0.093 fm and pion masses at and even below the physical value.
Nonperturbative renormalization is performed in the RI-MOM scheme, where we
find that operator mixing induced by chiral symmetry breaking is very small.
Using fully nonperturbative continuum running, we obtain our main result
B_K^{RI}(3.5GeV)=0.531(6)_{stat}(2)_{sys}. A perturbative 2-loop conversion
yields B_K^{MSbar-NDR}(2GeV)=0.564(6)_{stat}(3)_{sys}(6)_{PT}, which is in good
agreement with current results from fits to experimental data.Comment: 10 pages, 7 figures. v2: Added one reference and one figure, replaced
2 figures for better readability and updated ensembles, conclusions
unchanged. Final, published versio
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