125763688
Observation of the decays D(s)- ---> phi e- anti-neutrino and D- ---> K*0 e- anti-neutrino
120906561
Tau decays into K* mesons
AbstractUsing the ARGUS detector at the storage ring DORIS II we have measured τ decays into three charged mesons containingK* mesons. Exploiting the good particle identification capabilities of the detector we have determined the following branching ratios:
$$Br\left( {\tau ^ - \to \overline {K^{*0} } \pi ^ - v_\tau } \right) = \left( {0.25 \pm 0.10 \pm 0.05} \right)\% $$
,Br(τ−→K*0K−vτ)= (0.20±0.05±0.04)%, andBr(τ−→K*−X0vτ) =(1.15±0.15−0.18+0.13)%.
122042804
A Model independent determination of the inclusive semileptonic decay fraction of B mesons
Abstract With the ARGUS detector at the e + e - storage ring DORIS II, we have determined decay fraction and electron momentum spectrum of the inclusive decay mode B → eν X. Usinng lepton tags from the second B meson. in 209 000 γ(4 S ) → B B decays, we could determine the spectrum for all electron momenta p e > 0.6 GeV/ c . Including the small extrapolation to p e > 0, we find the model-independent decay fraction B (B → eν X) = (9.6 ± 0.5 ± 0.4)%. Adding D meson tags, our result is (9.7 ± 0.5 ± 0.4)%.
117873551
ICARUS at FNAL
The INFN and the ICARUS collaboration originally developed the technology of the LAr-TPC. Located the underground LNGS Hall-B, the ICARUS T600 detector has been performed over three years with remarkable detection efficiency featuring a smooth operation, high live time, and high reliability. About 3000 CNGS neutrino events have been collected and are being actively analyzed. ICARUS will now be moved to CERN for an extensive RD the T150 will be located at ~150 m. The T600 will also receive >10^4 nu_e events/year from the off-axis NUMI beam peaked around 1 GeV and exploitable to prepare for the LBNE experiment. The ICARUS teams are also interested in extending the participation to other short baseline neutrino activities collaborating with existing FNAL groups.
209962993
Search for neutrinoless tau decays
125577598
Measurement of the decay B- ---> D*0 l- anti-neutrino
Abstract Using the ARGUS detector at the e + e − storage ring DORIS II at DESY we have studied the decay B − → D ∗0 l − λ , where l − = e − or μ − , using the D 0 γ and D 0 π 0 decay modes of the D ∗0 meson. B mesons were produced in 209 000 decays of γ (4S). Assuming electron-muon universality, we obtain a value for the branching ratio of BR ( B − → D ∗0 l − λ )= (5.8 ± 1.4 ± 1.3)% .
118595631
Charm semileptonic decays and|Vcs(d) from heavy clover quarks and 2+1 flavor asqtad staggered ensembles
By combining experimentally measured partial branching fractions for the semileptonic decays D→Klν and D→ πlν with lattice calculations of the form factors f D→K + (q2) and f D→π + (q2), one can extract the CKM matrix elements |Vcs| and |Vcd |. We are calculating the form factors by using Fermilab charm and asqtad staggered light and strange quarks on 2+1 flavor asqtad staggered ensembles generated by the MILC Collaboration. We vary the light valence quark masses from 0.4ms to 0.05ms (ms is the strange sea-quark mass), and the lattice spacings, from about 0.12 fm to about 0.045 fm. We extrapolate to the physical light-quark mass and the continuum limit using heavy-light meson staggered chiral perturbation theory about the SU(2) and SU(3) limits, compare the resulting (preliminary) form factor shapes with experiment, and discuss our errors.
117853743
$B \to D^* \ell \nu$ and $B \to D \ell \nu$ form factors in staggered chiral perturbation theory.
We calculate the B {yields} D and B {yields} D* form factors at zero recoil in Staggered Chiral Perturbation Theory. We consider heavy-light mesons in which only the light (u, d, or s) quark is staggered; current lattice simulations generally use a highly improved action such as the Fermilab or NRQCD action for the heavy (b or c) quark. We work to lowest order in the heavy quark expansion and to next-to-leading order in the chiral expansion. We present results for a partially quenched theory with three sea quarks in which there are no mass degeneracies (the ''1+1+1'' theory) and for a partially quenched theory in which the u and d sea quark masses are equal (the ''2+1'' theory). We also present results for full (2+1) QCD, along with a numerical estimate of the size of staggered discretization errors. Finally, we calculate the finite volume corrections to the form factors and estimate their numerical size in current lattice simulations.
59427655
B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks
We calculate the B-meson decay constants fB, fBs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as Mπ ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(αsa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain fB0 = 196.2(15.7) MeV, fB+ = 195.4(15.8) MeV, fBs =more » 235.4(12.2) MeV, fBs/fB0 = 1.193(59), and fBs/fB+ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.« less
118573725
Lessons for new physics from CKM studies
We perform a global fit to the CKM unitarity triangle using the latest experimental and theoretical constraints. We present results for three different sets of constraints: the standard inputs used by CKMfitter and UTFit, the standard inputs minus |Vub|, and the standard inputs minus both |Vub| and |Vcb|. For the required nonperturbative weak matrix elements, we use three-flavor lattice QCD averages from www.latticeaverages.org; these have been updated to reflect all available lattice calculations as of the "End of 2010". Given current theoretical and experimental inputs, we observe an approximately 3{\sigma} tension in the CKM unitarity triangle that can be interpreted as sign of physics beyond the standard model in the flavor sector. Using a model-independent parameterization of new physics effects, we test the compatibility of new physics in kaon mixing, in B-mixing, or in B \rightarrow {\tau} {\nu} decay with the current data. Although the tension could be accommodated with each hypothesis, the scenarios with new physics in B-mixing or, to a lesser extent, in B \rightarrow {\tau} {\nu} decay are strongly preferred. Finally, we interpret these results in terms contributions to \Delta S = 2 and \Delta B = 2 four-fermion operators. We find that the preferred scale of new physics (with Standard Model like couplings) is in the few hundred GeV range.
7429466
Light pseudoscalar meson masses and decay constants from mixed action lattice QCD
We calculate the light pseudoscalar decay constants, f_pi and f_K, and their ratio using domain wall valence quarks and 2+1 flavors of dynamical staggered quarks. Use of the MILC gauge configurations allows us to simulate at several sea quark masses and spatial volumes, and with two lattice spacings. We study how well our numerical lattice data for light decay constants and meson masses is described by next-to-leading order SU(3) mixed action chiral perturbation theory and explain our strategy for the chiral and continuum extrapolation. Combining our result for f_K/f_pi with experimental measurements of pion and kaon leptonic decays allows a model-independent determination of |V_us|/|V_ud|; we find a preliminary value of |V_us|/|V_ud| = 0.2315(45)(7).