We present a lattice QCD determination of the vector and scalar form factors of the kaon semileptonic decay \(K \to \pi \ell \nu\), which is relevant for the determination of the CKM matrix element ...\(|V_{us}|\) from experimental data. Our results are based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2+1+1 dynamical fermions. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our estimate for the vector form factor at zero 4-momentum transfer is \(f_+(0) = 0.9709 (46)\), where the uncertainty is both statistical and systematic. By combining our result with the latest experimental value of \(f_+(0)|V_{us}|\) we obtain \(|V_{us}| = 0.2230 (11)\), which satisfies the unitarity constraint of the Standard Model at the permille level using the updated determination of \(|V_{ud}|\) coming from superallowed nuclear \(\beta\) decays. We present also the momentum dependence of the vector and scalar form factors in the whole range of values of the squared 4-momentum transfer measured in \(K_{\ell 3}\) decays, obtaining a good agreement with the experimental data.
Phys. Rev. D 93, 114512 (2016) We present a lattice QCD determination of the vector and scalar form factors
of the semileptonic $K \to \pi \ell \nu$ decay which are relevant for the
extraction of the ...CKM matrix element $|V_{us}|$ from experimental data. Our
results are based on the gauge configurations produced by the European Twisted
Mass Collaboration with $N_f = 2+1+1$ dynamical fermions, which include in the
sea, besides two light mass degenerate quarks, also the strange and the charm
quarks. We use data simulated at three different values of the lattice spacing
and with pion masses as small as $210$ MeV. Our final result for the vector
form factor at zero momentum transfer is $f_+(0) = 0.9709 (46)$, where the
uncertainty is both statistical and systematic combined in quadrature. Using
the latest experimental value of $f_+(0) |V_{us}|$ from $K_{\ell 3}$ decays, we
obtain $|V_{us}| = 0.2230 (11)$, which allows to test the unitarity constraint
of the Standard Model below the permille level once the determination of
$|V_{ud}|$ from superallowed nuclear $\beta$ decays is adopted. A slight
tension with unitarity at the level of $\sim 2$ standard deviations is
observed. Moreover we present our results for the semileptonic scalar
$f_0(q^2)$ and vector $f_+(q^2)$ form factors in the whole range of values of
the squared four-momentum transfer $q^2$ measured in $K_{\ell 3}$ decays,
obtaining a very good agreement with the momentum dependence of the
experimental data. We provide a set of synthetic data points representing our
results for the vector and scalar form factors at the physical point for
several selected values of $q^2$.
We present a lattice QCD determination of the vector and scalar form factors of the semileptonic decays D->\pi l \nu and D -> K l \nu which are relevant for the extraction of the CKM matrix elements ...|Vcd| and |Vcs| from experimental data. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2+1+1 dynamical fermions. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our preliminary estimates for the vector form factor at zero 4-momentum transfer are f+(D -> \pi)(0) = 0.610 (23) and f+(D -> K)(0) = 0.747 (22), where the uncertainties are only statistical. By combining our results with the experimental values of f+(D -> \pi)(0) |Vcd| and f+(D -> K)(0) |Vcs| we obtain |Vcd| = 0.2336 (93) and |Vcs| = 0.975 (30), which together with the PDG determination of |Vcb| are in agreement with the unitarity constraint of the Standard Model.
In August 1996, a 48 years old man living in Burkina Faso was referred to the Institut Pasteur in Algeria as a strongly suspected case of CL. His cutaneous lesions had appeared in July 1996, at the ...end of a one-month visit to Ouagadougou in Burkina Faso. The patient had lived in Algiers for one year before the lesions developed, and had not travelled outside the city apart from his visit to Ouagadougou. The patient had 15 cutaneous sores located on the forearms (6 lesions), legs (6) and trunk (3). All the lesions were 2-3 cm in diameter, ulcerated and covered with crusts. The diagnosis was confirmed by both detection of amastigotes on direct impression smears and culture of material obtained by puncture of a lesion on blood-agar medium. The culture became positive after 48 h incubation, and promastigotes were isoenzymatically characterized by starch gel electrophoresis using 15 enzymes according to Rioux et al. (1990). The strain (MHOM/BF/96/LIPA538) was identified as Leishmania major zymodeme MON-74. The patient was treated with meglumine antimoniate (Glucantime registered ), 6 mg Sb super(v)/kg/d for 21 d. At the end of treatment, the lesions had disappeared and both smears and culture were negative. This is the first report of L. major from Burkina Faso. The zymodeme found (MON-74) differs from L. major MON-26 in only a single enzyme, diaphorase (DIA super(90) instead of DIA super(100)).
We present precise lattice computations for the b-quark mass, the quark mass ratios mb/mc and mb/ms as well as the leptonic B-decay constants. We employ gauge configurations with four dynamical quark ...flavors, up/down, strange and charm, at three values of the lattice spacing (a ~ 0.06 - 0.09 fm) and for pion masses as low as 210 MeV. Interpolation in the heavy quark mass to the bottom quark point is performed using ratios of physical quantities computed at nearby quark masses exploiting the fact that these ratios are exactly known in the static quark mass limit. Our results are also extrapolated to the physical pion mass and to the continuum limit and read: mb(MSbar, mb) = 4.26(10) GeV, mb/mc = 4.42(8), mb/ms = 51.4(1.4), fBs = 229(5) MeV, fB = 193(6) MeV, fBs/fB = 1.184(25) and (fBs/fB)/(fK/fpi) = 0.997(17).
We present a lattice QCD calculation of the pseudoscalar decay constants f sub(K), f sub(D) and f sub(Ds) performed using the gauge configurations produced by the European Twisted Mass Collaboration ...with N sub(f) = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their values in the real world. The simulations are based on a unitary setup for the two light mass-degenerate quarks and on a mixed action approach for the strange and charm quarks. We use data simulated at three different values of the lattice spacing in the range 0.06-0.09 fm and at pion masses in the range 210-450 MeV. Our main results are f sub(K)+/f sub(phi) super(+) = 1.184(16), f sub(K) super(+) = 154.4(2.0) MeV, which incorporate the leading strong isospin breaking correction due to the up and down quark mass difference, and f sub(K) = 155.0(1.9 MeV), f sub(D) = 207.4(3.8) MeV, f sub(Ds) = 247.2(4.1) MeV, f sub(Ds)/ f sub(D) = 1.192(22) and (f sub(Ds) /f sub(D))/(f sub(K)/f sub(phi)) = 1.003(14) obtained in the isospin symmetric limit of QCD. Combined with the experimental measurements of the leptonic decay rates of kaon, pion, D and D sub(s) mesons our results lead to the following determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements: |V sub(us)| = 0.2269(29), |V sub(cd)| = 0.2221(67) and |V sub(cs)| = 1.014(24). Using the latest value of |V sub(ud)| from superallowed nuclear beta decays the unitarity of the first row of the CKM matrix is fulfilled at the per mill level.
We present a lattice QCD calculation of the pseudoscalar decay constants fK, fD and fDs performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + ...1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their values in the real world. The simulations are based on a unitary setup for the two light mass-degenerate quarks and on a mixed action approach for the strange and charm quarks. We use data simulated at three different values of the lattice spacing in the range 0.06 - 0.09 fm and at pion masses in the range 210 - 450 MeV. Our main results are: fK+ / fpi+ = 1.184 (16), fK+ = 154.4 (2.0) MeV, which incorporate the leading strong isospin breaking correction due to the up- and down-quark mass difference, and fK = 155.0 (1.9) MeV, fD = 207.4 (3.8) MeV, fDs = 247.2 (4.1) MeV, fDs / fD = 1.192 (22) and (fDs / fD) / (fK / fpi) = 1.003 (14) obtained in the isospin symmetric limit of QCD. Combined with the experimental measurements of the leptonic decay rates of kaon, pion, D- and Ds-mesons our results lead to the following determination of the CKM matrix elements: |Vus| = 0.2269 (29), |Vcd| = 0.2221 (67) and |Vcs| = 1.014 (24). Using the latest value of |Vud| from superallowed nuclear beta decays the unitarity of the first row of the CKM matrix is fulfilled at the permille level.
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