Conveners
Quark and lepton flavor physics
- Steven Gottlieb (Indiana University)
Quark and lepton flavor physics
- Andrew Lytle
Quark and lepton flavor physics
- Francesco Sanfilippo (INFN Roma Tre)
Quark and lepton flavor physics
- Teseo San Jose (University of Edinburgh)
Quark and lepton flavor physics
- Alejandro Vaquero Avilés-Casco (University of Zaragoza)
We present results for $f_K/f_{\pi}$ in pure QCD with $N_f=2+1$ flavors, along with a determination of $|V_{us}|$ and a study on the unitarity of the first row of the Cabibbo-Kobayashi-Maskawa (CKM) matrix after introducing strong isospin-breaking and QED effects.
The results obtained are based on a combination of a Wilson unitary action and a mixed action setup using Wilson twisted mass...
The precision of current lattice QCD calculations of the direct CP-violating parameter $\varepsilon’$ now requires the inclusion of $\Delta I = \frac{1}{2}$ rule-enhanced, isospin-breaking effects. Here we give an update on the program to include electromagnetism and quark mass differences in a first-principles calculation of $\varepsilon’$. We combine finite-volume hadronic matrix elements...
Current precision tests of the Standard Model (SM) show a deficit in the first row unitarity of the CKM matrix. At the current level of precision, the only relevant CKM matrix elements that contribute to first row unitarity are $|V_{ud}|$ and $|V_{us}|$. Without resorting on nuclear inputs, those can be extracted from the experimental decay width of kaon and pion leptonic decays along with the...
Hadronic decays of the $\tau$ lepton provide an independent avenue for determining the CKM matrix elements $V_{us}$ and $V_{ud}$. This is particularly relevant given the persistent tensions with CKM unitarity observed when these elements are extracted from leptonic and semileptonic decays of light mesons, as well as from nuclear beta decays. A recent lattice QCD calculation by the ETM...
First-principles prediction of inclusive heavy-particle decay is key to interpreting experimental data and testing the Standard Model. However, lattice QCD data requires ill-posed analytic continuation before such predictions can be made. Bergamaschi, et al. proposed using Nevanlinna-Pick interpolation to address this inverse problem which provides rigorous bounds on the continued results. ...
The SU(2) gauge symmetry of the weak sector implies that the Higgs vacuum expectation value has to be gauge variant and hence cannot be a physical observable, even though it is generally regarded as such. The standard perturbative expansion, therefore, has a conceptual flaw that can be resolved using the Fröhlich-Morchio-Strocchi mechanism. In this presentation, we explore the mechanism on the...
Many hadronic observables are nowadays computed in lattice QCD with a sub-percent precision which requires the inclusion of isospin-breaking and electromagnetic effects. Most of the methods that implement the photon propagator in finite-volume lead to power-law suppressed finite size effects. These are due to the long-range nature of electromagnetism and make reliable predictions...
We discuss the calculation of the inclusive semileptonic decay for the process $B_s \to X_c \, l\nu_l$ using lattice QCD, which could be decisive in understanding the long-standing tension between inclusive and exclusive determinations of the CKM matrix element, $|V_{cb}|$. In this talk, we investigate the main sources of systematic uncertainty in these decays, including the impact of Jacobi...
The unitarity of the CKM matrix is a fundamental property of the Standard Model, and leptonic decays of pseudoscalar mesons $P \to \ell\nu(\gamma)$ are an important avenue to probe this experimentally. The theoretical prediction of the decay rate depends on a number of form factors, which can be calculated using lattice QCD. We present an approach to compute them using a JLQCD domain-wall...
A first-principles computation of the inclusive semi-leptonic decay rates of heavy mesons from lattice QCD has a great phenomenological relevance since the comparisons of the theoretical results with the corresponding experimental data allows for stringent Standard Model tests in the sector of Flavour physics. In this talk we present the first fully non-perturbative computation of the $D_s \to...
We discuss the extraction of form factors for heavy-light pseudo-scalar to light pseudo-scalar decay form factors from finite time correlation functions. Particular emphasis is placed on controlling the contamination from excited-states using also the information from chiral perturbation theory to isolate the ground-state contribution. The analysis is performed on CLS ensembles with $N_f =...
The R-ratio is a phenomenological observable of great relevance, both in itself and in applications such as the dispersive approach to the muon anomalous magnetic moment. It can be investigated from first-principles in lattice QCD by introducing an arbitrary smearing kernel and employing the well-known Hansen-Lupo-Tantalo method to perform spectral reconstruction with controlled statistical...
We present the first lattice QCD determination of the Λ→N vector and axial-vector form factors, which are essential inputs for studying the semileptonic decay Λ→pℓνˉ. This channel provides a clean, theoretically controlled avenue for extracting the CKM matrix element ∣Vus∣ from the baryon sector. Our analysis uses a gauge ensemble with physical light, strange, and charm quark masses and yields...
We present new results on semileptonic decays of B-mesons using the highly improved staggered quark (HISQ) action for both valence and 2+1+1 sea quarks. Our calculation uses lattice spacings ranging from 0.12 fm down to 0.03 fm, including several ensembles with physical-mass pions. The focus on the talk will be on the vector and scalar form factors for the decay $B\to\pi\ell\nu$.
We present a calculation of the form factors for $B_{(s)} \to D_{(s)} \ell \nu$ decay using the highly improved staggered quark action for both valence and sea quarks on the MILC collaboration’s $2+1+1$-flavor ensembles with lattice spacings ranging from 0.09fm to 0.03fm, many with physical pion masses. On our finest ensembles, we can compute the form factors directly at the physical $b$-quark...
Semileptonic $B_{(s)}$ decays are of great phenomenological interest because they allow to determine e.g. CKM matrix elements or test lepton flavour universality.
Taking advantage of already existing lattice data, we demonstrate the analysis steps to extract the four form factors describing exclusive semileptonic
$B_s\to D_s^*\ell\nu_\ell$
decays using the narrow width approximation....
Theoretical predictions for heavy meson lifetimes require high-precision determinations of the matrix elements involving four-quark operators using non-perturbative methods.
While similar operators relevant for neutral meson mixing have become standard for lattice QCD calculations, these lifetime operators suffer from complications in renormalisation where the dimension-six operators of...
In this talk I will review the status of a calculation of the form factors of the most relevant heavy-to-heavy decay channels. Using seven N_f=2+1+1 HISQ ensembles, with lattice spacings ranging from 0.15 fm down to 0.06 fm, we calculate the form factors of the $B_{(s)}\to D_{(s)}^{(\ast)}\ell\nu$ decays, including correlations among them. More than half of our ensembles feature physical pion...
We present our recent calculation of radiative leptonic decay
rates of the kaon, based on twisted clover simulations at the physical
point carried out by ETM collaboration. The calculation improves
substantially our previous estimate, by improving the stastistcs,
including electrounquenched diagrams, carrying out the continuum
extrapolation on three different lattice spacings and...
We present an update of the ongoing computation of the isospin-breaking effects in the Pion Decay Constant from the BMW Collaboration. The calculation is carried out with N$_f$=2+1+1 staggered quarks with a near-physical pion mass and QED$_L$. We present some preliminary results of the valence-valence contribution to the axial-pseudoscalar correlator for different volumes $L=4.2, 6.3, 8.4$ fm...
We propose a new and simple method for determining the renormalized quark masses from lattice simulations. Renormalized quark masses are an important input to many phenomenological applications, including searching/modeling physics beyond the Standard Model. The non-perturbative renormalization is performed using gradient flow combined with the short-flow-time expansion that is improved by...
