Physical results from 2+1 flavor domain wall QCD Page: 4 of 9
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
1. Introduction
Due to computer and algorithmic constraints we are not able to simulate directly at the physical
light quark mass. This necessitates performing a chiral extrapolation. There are various ways that
this extrapolation can be done. We found that applying SU(2) partially quenched chiral perturbation
theory (PQChPT) is working more reliable at next-to-leading order (NLO) compared to SU(3)
PQChPT [1, 2]. The reason is that the strange quark mass is already too heavy to be described
by the NLO terms in SU(3) ChPT. To be able to also extract quantities from the kaon sector, we
introduced the SU(2) ChPT for kaon physics in [1, 2]. Recently other collaborations made similar
observations about the limitations of NLO-SU(3) ChPT and also successfully applied (kaon) SU(2)
ChPT in their analyses, e.g. [3].
We simulated QCD using Nj = 2+ 1 flavors of Domain Wall fermions. Currently the mass
of the heavy single flavor mA is kept fixed at a value close to the physical strange quark mass. We
generated ensembles at multiple values for the mass m, of the two (degenerate) light quark flavors.
Here we will focus on the extraction of the light quark masses, the pion and kaon decay
constants and the low energy constants (LECs) of the SU(2) chiral Lagrangian. For a discussion
of the treatment of the kaon bag parameter we refer to [2, 4] and [5] for recent developments.
The remainder is organized as follows: in Sec. 2 we briefly describe our method to extract the
physical results and estimate the systematic error and quote the results obtained at the ensembles
with a lattice cut-off 1/a = 1.73GeV. Before we conclude, we briefly present preliminary results
obtained at a finer lattice spacing in Sec. 3.
For any unexplained notation and further details, we refer to [2]; especially App. A therein
contains an overview of the conventions followed here as well.
2. Physical results at 1/a = 1.73GeV
To obtain physical results on the 243 x 64, L, = 16 lattices (generated using the Iwasaki gauge
action at # = 2.13), we only used the ensembles with the two lightest dynamical light quark masses,
mi = 0.005 and 0.01, which correspond to pion masses of 331 and 419 MeV, respectively. In
the subsequent analysis, partially quenched (valence) masses mX,y e {0.001,0.005, 0.01,0.02,0.03,
0.04} have been used as well. The lattice scale I/a = 1.729(28)GeV (a = 0.1141(18)fm), the
physical average light and strange quark masses are fixed by the masses of the S2--baryon, the pion,
and the kaon. In case of the S2--baryon this procedure includes an extrapolation in the dynamical
light quark mass to the physical average up- and down-quark mass and a (valence) interpolation
in the heavy dynamical mass to the point of the physical strange quark mass, cf. [2] for details.
The residual mass parameter, measuring the remaining breaking of the chiral symmetry, turned out
to be mres = 0.00315(2). In the following we will briefly describe our fit strategy and how the
extrapolations in the pion and kaon sectors were performed and how the systematic errors were
estimated.
2.1 PQChPT fits
As we already discussed extensively in [1, 2], fitting to SU(3) NLO PQChPT including the
physical strange quark mass is problematic. As shown for example in the left panel of Fig. 1, the
decay constant receives large NLO-contributions (around 60-70%) when extrapolated from pion2
Enno E. Scholz
Physical results from 2+1 flavor Domain Wall QCD
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Scholz,E.E. Physical results from 2+1 flavor domain wall QCD, article, July 14, 2008; United States. (https://digital.library.unt.edu/ark:/67531/metadc894401/m1/4/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.