Related papers: Kaon Decays and Vus
The determination of $|V_{us}|$ from kaon semileptonic decays requires the value of the form factor $f_+(q^2=0)$ which can be calculated precisely on the lattice. We provide the one-loop partially quenched chiral perturbation theory…
The matrix element Vud of the CKM matrix can be determined by two independent measurements on neutron decay: the neutron lifetime tau and the ratio of coupling constants lambda, which is most precisely determined by measurements of the beta…
Precision tests of the CKM mechanism and searches for new physics in the flavour sector require dedicated QCD calculations of decay widths and spectra. Significant progress has been achieved in recent years in computing inclusive B decay…
Hadronic matrix elements of local four-quark operators play a central role in non-leptonic kaon decays, while vacuum matrix elements involving the same kind of operators appear in inclusive dispersion relations, such as those relevant in…
The rate of the semileptonic decay b to c l v is calculated with order alphas^2 accuracy, as an expansion around the limit of equal masses of the b and c quarks. Recent results obtained around the limit of the c-quark much lighter than b…
We review recent work to determine the strange quark mass m_s as well as the proposal to determine |V_{us}| using hadronic tau decay data. The recent update of the strange spectral function by OPAL and their moments of the invariant mass…
If the CKM matrix element $V_{ud}$, that can be derived from superallowed nuclear decays, neutron decay and pion beta decay, is used for a precision test of the unitarity of the CKM matrix, the combination of the present world data seems to…
A search for pair-produced vector-like quarks decaying into a $Z$ boson and a third generation quark using 2015 and 2016 $pp$ collision data at $\sqrt{s}~=~13~$TeV collected by the ATLAS experiment at the Large Hadron Collider,…
Using HISQ $N_f=2+1+1$ MILC ensembles with five different values of the lattice spacing, including four ensembles with physical quark masses, we have performed the most precise computation to date of the $K\to\pi\ell\nu$ vector form factor…
A recent model of hadron states is extended to include meson decays. We find that the overall success of the model is quite good. Possible improvements to the model are suggested.
High-precision determinations of Cabibbo-Kobayashi-Maskawa (CKM) matrix elements are essential probes of physics Beyond the Standard Model (BSM). Current precision tests show a deficit in the first row unitarity relation. At the current…
Based on a series of lattice calculations we determine the ratio FK/Fpi in QCD. With experimental data from kaon decay and nuclear double beta decay, we obtain a precise determination of |Vus|. Our simulation includes 2+1 flavours of sea…
We present work in progress on the computation of the K-meson vector and tensor decay constants, as well as the B-parameter in Kaon oscillations. Our simulations are performed in a partially quenched setup, with two dynamical (sea) Wilson…
From a sample of about 10^9 Phi mesons produced at DAFNE, we have selected KL mesons tagged by observing KS->pi+pi- decays. We present results on the major KL branching ratios, including those of the semileptonic decays needed for the…
We use the modified quark-meson coupling (MQMC) model to study the composition profile of neutron star matter and compare the results with those calculated by quantum hadrodynamics (QHD). Both MQMC and QHD model parameters are adjusted to…
All ALEPH measurements of branching ratios of tau decays involving kaons are summarized including a combination of results obtained with K^0_S and K^0_L detection. The decay dynamics are studied, leading to the determination of…
Heavy-meson semileptonic decays calculations on the lattice are reviewed. The focus is upon obtaining reliable matrix elements. Errors that depend upon the lattice spacing, $a$, are an important source of systematic error. Full $O(a)$…
A very precise determination of V_us can be obtained from the semi-inclusive hadronic decay width of the tau lepton into final states with strangeness. The ratio of the Cabibbo-suppressed and Cabibbo-allowed tau decay widths directly…
Since the degree of polarization of the vector particle in semileptonic decay strongly influences the decay width of the particles, it can be used as a measure of CKM matrix elements. We show that |V_{cb}| can be determined from the…
SU(5) $\otimes$ SU(5) provides a minimal grand unification scheme for fermions and gauge forces if there are vector-like quarks and leptons in nature. We explore the gauge coupling unification in a non-supersymmetric model of this type, and…