120560046
Measurement of exclusive one-prong and inclusive three-prong branching ratios of the τ lepton
AbstractUsing the ARGUS detector at the DORIS II storage ring, we have studied τ decays with one or three charged particles in the final state, obtaining the following values for the branching ratios: BR(τ−→e−
$$\bar v_e v_\tau $$
)=(17.3±0.4±0.5)% BR(τ−→μ−
$$\bar v_\mu v_\tau $$
)=(17.2±0.4±0.5)%,BR(τ−→π−vπ)+BR(τ−→K−vπ)=(11.7±0.6±0.8)% and BR(π−→3-prong)=(13.3±0.3±0.8)%. These measurements confirm the present world averages with a precision, in each case, comparable to the error on the combination of all previous results.
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
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)%.
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)% .
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)%.
73560048
B-physics with dynamical domain-wall light quarks and relativistic b-quarks
The study of B-meson physics on the lattice is of special phenomenological interest becauseit allows one to obtain constraints on the CKM unitarity triangle. In the standard global unitaritytriangle ﬁt, the apex of the CKM unitarity triangle is constrained using lattice input for neutralB-meson mixing. Experimentally, B
117705778
Flavor Physics in the LHC era: the role of the lattice
We discuss the present status of global fits to the CKM unitary triangle using the latest experimental and theoretical constraints. For the required nonperturbative weak matrix elements, we use three-flavor lattice QCD averages from www.latticeaverages.org; these have been updated from Ref. [1] to reflect all available lattice calculations as of the "End of 2011". Because of the greater than 3 sigma disagreement between the extraction of |Vub| from inclusive and exclusive semileptonic b -> u l nu (l = e,mu) decays, particular emphasis is given to a clean fit in which we remove the information from these decays. Given current theoretical and experimental inputs, we observe an approximately 3 sigma tension in the CKM unitarity triangle that may indicate the presence of new physics in the quark-flavor sector. Using a model-independent parameterization of new-physics effects, we test the compatibility of the data with scenarios in which the new physics is in kaon mixing, in B-mixing, or in B -> tau nu decay. We find that scenarios with new physics in B -> tau nu decay or in B-mixing are approximately equally 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.
67766094
Pseudoscalar decay constants, light-quark masses, and $B_K$ from mixed-action lattice QCD
We present updated results for the leptonic decay constants fp and fK, the light u, d, and s-quark masses, and the neutral kaon mixing parameter BK from mixed-action lattice simulations with staggered sea quarks and domain-wall valence quarks. We use the publicly-available 2+1 flavor MILC asqtad-improved staggered gauge configurations with multiple light sea-quark masses and three lattice spacings, and compute the kaon mixing matrix element with several partiallyquenched valence-quark masses. We then extrapolate to the physical light-quark masses and the continuum using partially-quenched chiral perturbation theory formulated for mixed-action lattice simulations. For BK we match the lattice four-fermion operator to the continuum using the nonperturbative method of Rome-Southampton. Our new results benefit from two significant improvements over our published work: (1) we have added a third lattice spacing of a 0.06 fm to better control the continuum extrapolation, and (2) we have implemented a new lattice renormalization scheme (the RI/SMOMgm scheme developed by Sturm et al.) that suppresses chiralsymmetry breaking and other infrared effects and, in practice, also shrinks the size of the 1-loop perturbative coefficient needed to match to the continuum MS scheme. When combined with the use of volume-averaged momentum sources and twisted-boundary conditions, this significantly reduces the systematic uncertainty in the renormalization factor ZBK .
118622813
The B -> pi l nu form factor from unquenched lattice QCD with domain-wall light quarks and relativistic b-quarks
We report on a lattice-QCD calculation of the B to pi l nu form factor with domain-wall light quarks and relativistic b-quarks using the 2 + 1 flavor domain-wall fermion and Iwasaki gauge-field ensembles generated by the RBC and UKQCD Collaborations. We present initial results obtained from the coarser (a ~ 0.11 fm) 24^3 lattices and some of the finer (a ~ 0.086 fm) 32^3 lattices.
119188484
Lattice QCD inputs to the CKM unitarity triangle analysis
We perform a global fit to the Cabibbo-Kobayashi-Maskawa unitarity triangle using the latest experimental and theoretical constraints. Our emphasis is on the hadronic weak matrix elements that enter the analysis, which must be computed using lattice QCD or other nonperturbative methods. Realistic lattice QCD calculations which include the effects of the dynamical up, down, and strange quarks are now available for all of the standard inputs to the global fit. We therefore present lattice averages for all of the necessary hadronic weak matrix elements. We attempt to account for correlations between lattice QCD results in a reasonable but conservative manner: whenever there are reasons to believe that an error is correlated between two lattice calculations, we take the degree of correlation to be 100%. These averages are suitable for use as inputs both in the global Cabibbo-Kobayashi-Maskawa unitarity triangle fit and other phenomenological analyses. In order to illustrate the impact of the lattice averages, we make standard model predictions for the parameters B-circumflex{sub K}, |V{sub cb}|, and |V{sub ub}|/|V{sub cb}|. We find a (2-3){sigma} tension in the unitarity triangle, depending upon whether we use the inclusive or exclusive determination of |V{sub cb}|. If we interpret the tension as a signmore » of new physics in either neutral kaon or B mixing, we find that the scenario with new physics in kaon mixing is preferred by present data.« less