The first phase of a heavy quark program based on twisted mass valence quarks has been presented at last year's lattice conference. The CLS $N_f=2+1$ ensembles were used for their fine lattice spacing, while twisting the masses is expected to reduce discretisation errors even further and allow for a fully relativistic calculation. In this poster, we present our first preliminary results on...
Using the infinite volume reconstruction method, we present a lattice QCD calculation of neutrinoless double beta decay $\pi^-\to \pi^+ ee$ with only exponentially suppressed finite volume effects. We compare these results with the conventional $QED_L$ method. Our calculation can provide the low-energy constants for chiral perturbation theory. Besides, combining with our previous study on...
Proton decay matrix elements in QCD are indispensable quantities to constrain GUT models through the lower bound of the proton lifetime measured in the current and future underground experiments. Results obtained with lattice QCD so far have largest systematic uncertainty on the chiral extrapolation. We report on the relevant form factors of the dominant decay processes: a proton to a...
The major decay rates of the charged pion and kaon mesons are to the end state of a muon and neutrino. This mode contributes over 99.9 percent to the pion decay, and about 64 percent to the kaon decay.
Analysing this decay on the lattice could lead to improved values for the meson decay constants and the parameters in the CKM matrix. High accuracy predictions will need to have QED effects...
We establish the conformal nature of an SU(3) gauge theory with twelve
fundamental flavors by presenting final results for our gradient flow
step-scaling calculation of the renormalization group beta function using domain wall fermions. The
continuum limit of the $s=2$ step scaling function exhibits a sign change (infra-red
fixed point) around $g_c^2 \sim 5.5$ in the $c=0.25$ scheme....
The conventional method to calculate $\pi\to\gamma\gamma$ decay width is to study the momentum dependence of the pion form factor $F_{\pi\gamma\gamma}(p^2,q^2)$ with $p$, $q$ the momenta of two photons and perform an extrapolation to the on-shell limit, $p^2,q^2=0$. In alternative, we propose a novel, simple approach to determine the decay width directly from the hadronic function in Euclidean...
We employ the chirally rotated Schroedinger functional ($\chi$SF) to study two-point fermion bilinear correlation functions used in determination of $Z_{A,V,S,P,T}$, on a series of well-tuned ensembles generated using the Schroedinger Functional (SF) and which span renormalisation scales from 4 to 70 GeV. We carry out a detailed comparison with the expectations from one-loop perturbation theory.
We report recent progress in determining $\varepsilon_K$, the indirect
CP violation parameter in neutral kaons, calculated using lattice QCD
inputs including $\hat{B}_K$, $\xi_0$, $\xi_2$, $|V_{us}|$,
$|V_{cb}|$, and $m_c(m_c)$. Recently Belle has updated results for
exclusive $|V_{cb}|$ using both CLN and BGL method. They are used in
this analysis.
The NEC SX-Aurora Tsubasa is a novel PCI-Express accelerator design available
since 2018. The vector architecture supports vector lengths of 16,384 bits and
delivers up to 2.45 TFlop/s peak in double precision. It features outstanding
memory throughput of up to 1.2 TB/s. In this contribution we discuss
key aspects of the SX-Aurora Tsubasa, comment on integrating the architecture
into the...
We present recent progress in the lattice calculation of leptonic decay constants for $B_{(s)}$ and $D_{(s)}$ mesons using the Oktay-Kronfeld (OK) action for the charm and bottom quarks. We use MILC HISQ ensembles and the HISQ action for the light spectator quark. Results for spectrum of $B_{(s)}$, $D_{(s)}$, $B^\ast_{(s)}$, $D^\ast_{(s)}$ mesons with the nonperturbatively tuned heavy quark...
We present recent progress in lattice calculations of semileptonic decays $B_{(s)} \to D_{(s)}\ell\nu$ form factors using the Oktay-Kronfeld (OK) action for the charm and bottom quarks. Data on four MILC HISQ ensembles: a12m310, a12m220, a09m310, a09m220 has been generated using the coherent sequential source to increase the statistics cost effectively. The excited states are controlled with...
We present our nonperturbative Lattice QCD calculation to determine semileptonic form factors for exclusive $B_s \to K \ell \nu$ and $B_s \to D_s \ell \nu$ decays. Our calculation is based on RBC-UKQCD's set of 2+1 dynamical flavor gauge field ensembles and in the valence sector we use domain wall fermions for up/down, strange, and charm quarks, whereas bottom quarks are simulated with the...
In lattice gauge theory, understanding contributions from excited states is imperative for achieving high precision calculations. A variety of methods are available to extract excited states, such as fitting to multiple exponentials, Prony’s method, and Matrix Prony, correlator matrices, and generalized eigenvalue problems. A generic problem faced by all these methods is that the resulting...
Eleven years after its inception, the QUDA library for Lattice QCD on NVIDIA GPUs has achieved a historic 1.0 release. In this span QUDA has evolved into an open-source framework for full QCD simulations. The library has been fully re-written in a new highly optimized C++11 framework, superseding python-generated routines and ushering in a new age of rapid algorithm prototyping and...
We present an novel calculation of the static force directly from the lattice. Compared to the usual approach of taking derivatives of static potential, a direct measurement of the force resolves the ambiguities related to integration constants when comparing to pNRQCD expansion. We have performed a set of SU(3) pure gauge simulations using the multilevel algorithm to test out
this procedure.
We report on the ongoing study of Riemann Manifold Hybrid Monte Carlo (RMHMC) for Lattice QCD. The effect of Fourier acceleration with RMHMC are studied
on both quenched and 2+1-flavor dynamical ensembles by measuring autocorrelations on topological charge and wilson flow scales, as well as topological diffusion coefficients.
We have initiated a program to compute the Compton amplitude with the Feynman-Hellman method. This amplitude is related to the structure function via a Fredholm integral equation of the first kind. It is known that these types of equations are inherently ill-posed - they are, e.g., extremly sensitive to perturbations of the system. We discuss some methods which are candidates to handle these...
Brambilla et al. have derived an effective description of quarkonium with two parameters: a momentum diffusion term which has been widely explored within the community, and a real self-energy term. We derive a relation between the self-energy term and Euclidean electric field correlators along a Polyakov line, which can directly be studied on the lattice without the need for analytical...
The long term goal of our current project is to provide a high-order Taylor expansion of the grand canonical partition function of QCD, at non vanishing chemical potential.
For our study we use (2+1)-flavor of highly improved staggered quarks
(HISQ) with physical light and strange quark masses.
In order to achieve that goal, we are further advancing the numerical
tools that allow for the...
Quarkonium suppression in quark-gluon plasma has been investigated since original work by Matsui and Satz [1]. This topic remains actual due to the need of quark-gluon plasma diagnostics. In fact, both quarkonium suppression in quark-gluon plasma and recombination during hadronisation remain to be key open questions [2]. The bound state of quarkonium is theoretically well investigated in...
We describe progress during the last year on extending the range of applicability of the model-independent three-particle quantization condition and in implementing it in practice. Results include the extension of the formalism to allow subchannel resonances, which has been achieve in two different ways, and the inclusion of d-wave two- and three-particle interactions in practical...
We explore the phase structure of a four dimensional SO(4) invariant lattice Higgs-Yukawa model
comprising four reduced staggered fermions interacting with a real scalar field. The fermions belong
to the fundamental representation of the symmetry group while the three scalar field components
transform in the self-dual representation of SO(4). The model is a generalization of a four...
I will present lattice investigations of the Berenstein--Maldacena--Nastase deformation of maximally supersymmetric Yang--Mills quantum mechanics, focusing on its phase diagram in the plane of the temperature $T$ and deformation parameter $\mu$. By considering values of the dimensionless coupling $g = \lambda / \mu^3$ spanning more than two orders of magnitude, we find results for the...
Quantifying the structure of mesons in terms of their fundamental constituents is a major goal of hadron research. In the last decades extensive progress has been made in the calculation of quark structure, however very little is understood about the gluonic equivalent. One way of quantifying how quarks and gluons make up mesons is via the generalized parton distribution functions (GPDs). This...
EQCD is a 3D bosonic theory containing SU(3) and an adjoint scalar,
which efficiently describes the infrared, nonperturbative sector of
hot QCD and which is highly amenable to lattice study. We improve
the matching between lattice and continuum EQCD by determining the
final unknown coefficient in the $\mathcal{O}(a)$ matching, an additive
scalar mass renormalization. We do this...
"Applying lattice field theory to curved Riemannian manifolds opens up the doors to investigating some highly interesting physical systems, including the cylindrical manifolds of radial quantization $R$ $\times$ $S^{D-1}$. Substantial effort has already produced results on $R$ $\times$ $S^2$ and we would like to take a step towards higher dimensions. We tessellate the tetrahedral cells of...
We present the unpolaried parton distribution functions of $\Delta^+$ baryon in lattice simulation based on large momentum effective theory. We use $N_f=2+1+1$ twist mass fermion with colver term and pion mass is 260 MeV. The simulation is done using fixed sink sequential inversion method with Gaussian-momentum-smeared source while the largest baryon momentum is 1.2GeV .By comparing the...
There are several ways of distinguishing would-be zero modes of staggered fermions from non-zero modes of them. An intuitive approach is observing the taste symmetry on eigenvalue spectrum, but this fails in many cases and does not give much physical information.We are also able to identify those zero modes by measuring their chiralities, which has a better resolution for the identification...
We explore the profiles of the flux tube connecting a quark and an antiquark in high temperature SU(3) lattice gauge theory in close vicinity to the critical temperature of the phase transition. In this work, we consider the more realistic case of the flux tube with dynamical quarks, extending the previous study to SU(3) gauge group and making use of the Gradient flow method in smoothing...
We explore the S- and P-states for bottomonia at high temperatures, above the critical temperature $T_c$, using non-relativistic QCD (NRQCD). We extract the spectrum as a function of temperature using smeared source correlators. We push to the limit of NRQCD for $N_ \tau = 12$ which allows us to find the bottomonium spectrum up to a temperature of 334MeV.
We study the meson properties at fine temperature using the quenched simulations with truncated overlap fermion formalism. We explore the screening masses in rather heavy mass regions. We observe the tendency that the screening masses in all the channels are degenerate at high temperature.
I present an overview of the implementation of the HISQ RHMC using the Grid framework and report performance of key kernels on recent CPU and GPU architectures.
