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A. Limosani

Publications and source records attributed to A. Limosani.

12 recordsLinked to original sources
arXiv2011

Measurement of the decay $B^0\toπ^-\ell^+ν$ and determination of $|V_{ub}|$

We present a measurement of the charmless semileptonic decay $B^0\toπ^-\ell^+ν$ using a data sample containing 657$\times 10^6$ $B\bar{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider operating near the $Υ(4S)$ resonance. We determine the total branching fraction of the decay, $\mathcal{B}(B^0\toπ^-\ell^+ν)=(1.49\pm 0.04{(\mathrm{stat})}\pm 0.07{(\mathrm{syst})})\times 10^{-4}$. We also report a new precise measurement of the differential decay rate, and extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ using model-independent and -dependent approaches. From a simultaneous fit to the measured differential decay rate and lattice QCD results, we obtain $|V_{ub}|=(3.43\pm 0.33)\times 10^{-3}$, where the error includes both statistical and systematic uncertainties.

hep-ex↗
arXiv2010

Physics at Super B Factory

This report presents the results of studies that investigate the physics reach at a Super $B$ factory, an asymmetric-energy $e^+e^-$ collider with a design luminosity of $8 \times 10^{35}$ cm$^{-2}$s$^{-1}$, which is around 50 times as large as the peak luminosity achieved by the KEKB collider. The studies focus on flavor physics and CP violation measurements that could be carried out in the LHC era. The physics motivation, key observables, measurement methods and expected precisions are presented.

hep-ex↗
arXiv2010

Flavor Physics in the Quark Sector

One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of $K, D$, and $B$ mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field.

hep-ph↗
arXiv2009

Measurement of Inclusive Radiative B-meson Decays with a Photon Energy Threshold of 1.7 GeV

Using 605/fb of data collected at the Upsilon(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B to X_s gamma. For the lower photon energy thresholds of 1.7, 1.8, 1.9 and 2.0GeV, as defined in the rest frame of the B-meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7GeV threshold we obtain the partial branching fraction BF(B to X_s gamma) = (3.45 +/- 0.15 +/- 0.40) x 10^-4, where the errors are statistical and systematic.

hep-ex↗
arXiv2008

Measurement of the Moments of the Photon Energy Spectrum in B -> X_s gamma Decays and Determination of |V_cb| and m_b at Belle

Using the previous Belle measurement of the inclusive photon energy in $B\to X_sγ$ decays, we determine the first and second moments of this spectrum for minimum photon energies in the $B$ meson rest frame ranging from 1.8 to 2.3 GeV. Combining these measurements with recent Belle data on the lepton energy and hadronic mass moments in $B\to X_c\ellν$ decays, we perform fits to theoretical expressions derived in the 1S and kinetic mass schemes and extract the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{cb}$, the $b$-quark mass and other non-perturbative parameters. In the 1S scheme analysis we find $|V_{cb}|=(41.56\pm 0.68(\mathrm{fit})\pm 0.08(τ_B))\times 10^{-3}$ and $m_b^\mathrm{1S}=(4.723\pm 0.055)$ GeV. In the kinetic scheme, we obtain $|V_{cb}|=(41.58\pm 0.69(\mathrm{fit})\pm 0.08(τ_B)\pm 0.58(\mathrm{th}))\times 10^{-3}$ and $m_b^\mathrm{kin}=(4.543\pm 0.075)$ GeV.

hep-ex↗
arXiv2006

Averages of b-hadron Properties at the End of 2005

This article reports world averages for measurements on b-hadron properties obtained by the Heavy Flavor Averaging Group (HFAG) using the available results as of at the end of 2005. In the averaging, the input parameters used in the various analyses are adjusted (rescaled) to common values, and all known correlations are taken into account. The averages include lifetimes, neutral meson mixing parameters, parameters of semileptonic decays, branching fractions of B meson decays to final states with open charm, charmonium and no charm, and measurements related to CP asymmetries.

hep-ex↗
arXiv2005

Measurement of |V_ub| near the endpoint of the electron momentum spectrum from semileptonic B-meson decays

We report measurements of partial branching fractions of inclusive charmless semileptonic $B$-meson decays at the endpoint of the electron momentum spectrum. The measurements are made in six overlapping momentum intervals that have lower bounds ranging from 1.9 GeV/$c$ to 2.4 GeV/$c$ and a common upper bound of 2.6 GeV/$c$, as measured in the centre of mass frame. The results are based on a sample of 29 million $B\bar{B}$ pairs, accumulated by the Belle detector at the KEKB asymmetric $e^+e^-$ collider operating on the $Υ(4S)$ resonance. In the momentum interval ranging from 1.9 GeV/$c$ to 2.6 GeV/$c$ we measure the partial branching fraction $Δ\mathcal{B}(B\to X_u e ν_e)=(8.47 \pm 0.37 \pm 1.53)\times 10^{-4}$, where the first error is statistical and the second is systematic. A prediction of the partial rate $R=(21.69 \pm 3.62^{+ 2.18}_{- 1.98}) |V_{ub}|^2 \mathrm{ps}^{-1}$ in this momentum interval based on theory is calculated with input HQET parameters that have been derived from Belle's measurement of the $B\to X_sγ$ photon energy spectrum, where the first error is due to the uncertainty on HQET parameters and the second error is from theory. Using both $Δ\mathcal{B}(B\to X_u e ν_e)$ and $R$ we find $|V_{ub}|=(5.08 \pm 0.47 \pm 0.42^{+ 0.26}_{- 0.23})\times 10^{-3}$, where the first error is from the partial branching fraction, and the second and third errors are from uncertainties in $R$.

hep-ex↗
arXiv2003

Measurement of Vub at Belle

Results on two inclusive Vub measurements at Belle are presented. We also present a new measurement of the branching fraction for Ds->phi pi. A data sample of 78.1fb^-1 accumulated using the Belle detector at the KEKB asymmetric e^+e^- collider operating at the Upsilon(4S) resonance is used. All results are preliminary.

hep-ex↗