We review lattice results related to pion, kaon,
D
- and
B
-meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the ...determination of the light-quark masses, the form factor
f
+
(
0
)
, arising in the semileptonic
K
→
π
transition at zero momentum transfer, as well as the decay constant ratio
f
K
/
f
π
and its consequences for the CKM matrix elements
V
u
s
and
V
u
d
. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of
S
U
(
2
)
L
×
S
U
(
2
)
R
and
S
U
(
3
)
L
×
S
U
(
3
)
R
Chiral Perturbation Theory. We review the determination of the
B
K
parameter of neutral kaon mixing as well as the additional four
B
parameters that arise in theories of physics beyond the Standard Model. The latter quantities are an addition compared to the previous review. For the heavy-quark sector, we provide results for
m
c
and
m
b
(also new compared to the previous review), as well as those for
D
- and
B
-meson-decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. Finally, we review the status of lattice determinations of the strong coupling constant
α
s
.
Bs → Kℓv form factors with 2+1 flavors Liu, Yuzhi; Bailey, Jon A; Bazavov, A ...
EPJ Web of Conferences,
01/2018, Volume:
175
Conference Proceeding, Journal Article
Peer reviewed
Open access
Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors f0 and f+ for the semileptonic Bs → Kℓv decay. A total of six ensembles with lattice spacing from ≈ 0.12 ...to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass m’l is one-tenth the strange quark mass m’s. At the intermediate lattice spacing, the ratio m’l/m’s ranges from 0.05 to 0.2. The valence b quark is treated using the Sheikholeslami-Wohlert Wilson-clover action with the Fermilab interpretation. The other valence quarks use the asqtad action. When combined with (future) measurements from the LHCb and Belle II experiments, these calculations will provide an alternate determination of the CKM matrix element |Vub|.
Race to Exascale Dongarra, Jack; Gottlieb, Steven; Kramer, William T. C.
Computing in science & engineering,
2019-Jan.-Feb.-1, 2019-1-1, 20190101, Volume:
21, Issue:
1
Journal Article
Peer reviewed
Open access
Whether called leadership computing, flagship computing, or just plain exascale, over the next few years, governments around the world are planning to spend over 10 billion dollars on a handful of ...new computer systems that will strive to reach an exascale level of performance. These systems and projects reflect the widespread and expanding recognition that almost all science and engineering endeavors now are intrinsically reliant on computing power not just for modeling and simulation but for data analysis, big data, and machine learning. Scientists and engineers consider computers as “universal instruments” of insight.
Performance Portability for Advanced Architectures Doerfler, Douglas; Gottlieb, Steven; Gropp, William ...
Computing in science & engineering,
2021-Sept.-Oct.-1, 2021-9-1, Volume:
23, Issue:
5
Journal Article
Peer reviewed
Open access
The papers in this special section focus on performance portability for advanced architectures. This is a very timely topic as we continue our journey to exascale computers. The leader on the Top 500 ...list today is the Fujitsu Fugaku computer in Japan, using a modified ARM architecture and 512-bit scalable vector extension (SVE) instructions. In the USA, the National Energy Research Scientific Computing Center (NERSC) has just dedicated Perlmutter, named for the Berkeley Nobel Laureate Saul Perlmutter. Perlmutter, built by Cray/HPE, contains both CPU-only and CPU/GPU nodes. The CPUs are produced by AMD and the GPUs come from NVIDIA. Frontier at Oak Ridge National Laboratory and El Capitan at Lawrence Livermore National Laboratory will contain new AMD GPUs, and Aurora at Argonne National Laboratory will feature new GPUs from Intel. Los Alamos National Laboratory’s next-generation machine Crossroads will use Intel CPUs with high-bandwidth memory and AVX-512 vector instructions. Optimizing code for three different GPUs is a daunting challenge for application programmers. Further, there are still many computers that do not feature GPUs, and most computational scientists would not be eager to totally abandon such machines.
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