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G. Bonvicini

Publications and source records attributed to G. Bonvicini.

At least 325 records · Page 18Linked to original sources
arXiv2010

Measurement of the eta_b(1S) mass and the branching fraction for Upsilon(3S) --> gamma eta_b(1S)

We report evidence for the ground state of bottomonium, eta_b(1S), in the radiative decay Upsilon(3S) --> gamma eta_b in e^+e^- annihilation data taken with the CLEO III detector. Using 6 million Upsilon(3S) decays, and assuming Gamma(eta_b) = 10 MeV/c^2, we obtain B(Upsilon(3S) --> gamma eta_b) = (7.1 +- 1.8 +- 1.1) X 10^{-4}, where the first error is statistical and the second is systematic. The statistical significance is about 4 sigma. The mass is determined to be M(eta_b) = 9391.8 +- 6.6 +- 2.0 MeV/c^2, which corresponds to the hyperfine splitting Delta M_{hf}(1S)_b = 68.5 +- 6.6 +- 2.0 MeV/c^2. Using 9 million Upsilon(2S) decays, we place an upper limit on the corresponding Y(2S) decay, B(Y(2S) --> gamma eta_b) < 8.4 X 10^{-4} at 90 % confidence level.

hep-ex↗
arXiv2008

Dalitz plot analysis of the D^+ -> K^-pi^+pi^+ decay

We perform a Dalitz plot analysis of D^+ -> K^-pi^+pi^+ decay with the CLEO-c data set of 572 pb^-1 of e^+e^- collisions accumulated at the psi(3770). This corresponds to 1.6 million D^+D^- pairs from which we select 140793 candidate events with a small background of 1.1%. We compare our results with previous measurements using the isobar model. We modify the isobar model with improved description of some of the contributing resonances, and get better agreement with our data. We also consider a quasi-model-independent approach and measure the magnitude and phase of the contributing K pi S wave in the range of invariant masses from the threshold to the maximum in this decay. This gives an improved descriptions of our data over the isobar model. Finally we allow for an isospin-two pi^+pi^+ S-wave contribution, and find that adding this to both the isobar model and quasi-model-independent approach gives the best description of our data.

hep-ex↗
arXiv2008

Absolute Branching Fractions of Cabibbo-Suppressed D --> K Kbar Decays

Using 281/pb of data collected with the CLEO-c detector at the psi(3770) resonance, we have studied Cabibbo-suppressed decays of D mesons to final states with two kaons. We present results for the absolute branching fractions of the modes D^0 --> K^+ K^-, D^0 --> K^0_S K^0_S, and D^+ --> K^+ K^0_S. We measure B(D^0 --> K^+ K^-) = (4.08 +- 0.08 +- 0.09) x 10^-3, B(D^0 --> K^0_S K^0_S) = (1.46 +- 0.32 +- 0.09) x 10^-4, and B(D^+ --> K^+ K^0_S) = (3.14 +- 0.09 +- 0.08) x 10^-3. We also determine the ratio B(D^0 --> K^+ K^-)/B(D^0 --> pi^+ pi^-) = 2.89 +- 0.05 +- 0.06. For each measurement, the first uncertainty is statistical and the second uncertainty is systematic.

hep-ex↗
arXiv2007

Dalitz plot analysis of the D+ -> K- pi+ pi+ decay

We present a Dalitz plot analysis of the decay D+ -> K- pi+ pi+ based on 281 pb-1 of e+e- collision data produced at the psi(3770) by CESR and observed with the CLEO-c detector. We select 67086 candidate events with a small, ~1.1%, background for this analysis. When using a simple isobar model our results are consistent with the previous measurements done by E791. Since our sample is considerably larger we can explore alternative models. We find better agreement with data when we include an isospin-two pi+pi+ S-wave contribution. We apply a quasi model-independent partial wave analysis and measure the amplitude and phase of the K pi and pi+pi+ S waves in the range of invariant masses from the threshold to the maximum in this decay.

hep-ex↗
arXiv2007

Dalitz Plot Analysis of the D+ --> pi- pi+ pi+ Decay

Using 281 pb^{-1} of data recorded by the CLEO-c detector in e^+e^- collisions at the psi(3770), corresponding to 0.78 million D^+D^- pairs, we investigate the substructure of the decay D^+ to pi^- pi^+ pi^+ using the Dalitz plot technique. We find that our data are consistent with the following intermediate states: rho(770)pi^+, f_2(1270)pi^+, f_0(1370)pi^+, f_0(1500)pi^+, f_0(980) pi^+, and sigma pi^+. We confirm large S wave contributions at low pi pi mass. We set upper limits on contributions of other possible intermediate states. We consider three models of the pi pi S wave and find that all of them adequately describe our data.

hep-ex↗
arXiv2006

Dalitz Analysis of D^+ to pi^+ pi^- pi^+

Using 281/pb of data recorded by the CLEO-c detector observing e+e- collisions at the psi(3770), corresponding to 1.8 million D Dbar pairs, the substructure of the decay D+ to pi+ pi- pi+ is investigated using the Dalitz plot technique. The results presented in this document are preliminary.

hep-ex↗
arXiv2006

Observation of B_s Production at the Upsilon(5S) Resonance

Using the CLEO detector at the Cornell Electron Storage Ring, we have observed the Bs meson in e+e- annihilation at the Upsilon(5S) resonance. We find 14 candidates consistent with Bs decays into final states with a J/psi or a Ds(*)-. The probability that we have observed a background fluctuation is less than 8x10e-10. We have established that at the energy of the Upsilon(5S) resonance Bs meson production proceeds predominantly through the creation of Bs*Bs* pairs. We find sigma(e+e- -> Bs*Bs*) = [0.11 (+0.04-0.03)(stat.)+/-0.02(syst.)] nb, and set the following limits: sigma(e+e- -> BsBs) / sigma(e+e- -> Bs*Bs*) < 0.16 and sigma(e+e- -> BsBs*) / sigma(e+e- -> Bs*Bs*) < 0.16 at the 90% confidence level. The mass of the Bs* meson is measured to be M(Bs*) = [5.414 +/- 0.001(stat.) +/- 0.003(syst.)] GeV.

hep-ex↗
arXiv2004

Measuring cal B(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant f_D^+

In 60 inverse-pb of data taken on the psi(3770) resonance with the CLEO-c detector, we find 8 D+ -> mu+ nu decay candidates that are mostly signal, containing only 1 estimated background. Using this statistically compelling sample, we measure a value of B(D+ -> mu+ nu) = (3.5 +/- 1.4 +/- 0.6) x10^(-4), and determine fD+=(202 +/- 41 +/-17) MeV.

hep-ex↗
arXiv2004

Negative Ion Drift and Diffusion in a TPC near 1 Bar

Drift velocity and longitudinal diffusion measurements are reported for a Negative Ion TPC (NITPC) operating with Helium + carbon disulfide gas mixtures at total pressures from 160 to 700 torr. Longitudinal diffusion at the thermal-limit was observed for drift fields up to at least 700 V/cm in all gas mixtures tested. The results are of particular interest in connection with mechanical simplification of Dark Matter searches such as DRIFT, and for high energy physics experiments in which a low-Z, low density, gaseous tracking detector with no appreciable Lorentz drift is needed for operation in very high magnetic fields.

physics.ins-det↗
arXiv2004

First Observation of a Upsilon(1D) State

We present the first evidence for the production of Upsilon(1D) states in the four-photon cascade, Upsilon(3S)-->gamma chib(2P), chib(2P)-->gamma Upsilon(1D), Upsilon(1D)-->gamma chib(1P), chib(1P)-->gamma Upsilon(1S), followed by the Upsilon(1S) annihilation into e+e- or mu+mu-. The signal has a significance of 10.2 standard deviations. The measured product branching ratio for these five decays, (2.5+-0.5+-0.5)x10^(-5), is consistent with the theoretical estimates. The data are dominated by the production of one Upsilon(1D) state consistent with the J=2 assignment. Its mass is determined to be (10161.1+-0.6+-1.6) MeV, which is consistent with the predictions from potential models and lattice QCD calculations. We also searched for Upsilon(3S)-->gammachib(2P), chib(2P)-->gammaUpsilon(1D), followed by either Upsilon(1D)-->eta Upsilon(1S) or Upsilon(1D)-->pi+pi- Upsilon(1S). We find no evidence for such decays and set upper limits on the product branching ratios.

hep-ex↗
arXiv2003

GEM Operation in Negative Ion Drift Gas Mixtures

The first operation of GEM gas gain elements in negative ion gas mixtures is reported. Gains up to several thousand were obtained from single-stage GEMs in carbon disulfide vapor at low pressure, and in mixtures of carbon disulfide with Argon and Helium, some near 1 bar total pressure.

physics.ins-det↗
arXiv2003

The chemical history of $^{14}{\rm C}$ in deep oilfields

14C is an overwhelming background in low-background underground experiments, to the point where the observation of the all-important (pp) neutrinos from the Sun can not be observed in carbon-containing experiments. This paper shows that 14C purity can be improved by four orders of magnitude by a careful selection of the gas field. Two large reduction factors are at work: the low chemical affinity of methane to single carbon, and the migration of natural gas away from nitrogen-bearing kerogen during as the oilfield matures.

hep-ex↗
arXiv2003

Beamstrahlung at the NLC

The detection of beamstrahlung visible light, divided in its polarization components, effectively images the beam-beam collision (BBC). Monitoring and correction of drifts are reviewed. Monitoring of beam jitter is also possible. The properties of coherent beamstrahlung in the microwave part of the spectrum (and its usage) are introduced.

hep-ex↗
arXiv2003

Study of the Charmless Inclusive B -> eta' X Decay

Based on a measurement of high momentum eta' production in B decays, we determine the charmless inclusive B -> eta'X_(nc) branching fraction in the lab-frame momentum interval 2.0 eta'X_(nc)) = (4.6 +- 1.1 +- 0.4 +- 0.5)x 10^(-4) in the 2.0<P_(eta')<2.7 GeV/c momentum range, where the uncertainties are statistical, systematic, and from subtraction of background from B decays to charm, respectively.

hep-ex↗
arXiv2002

Cosmogenesis Backgrounds, Experiment Depth and the Solar Neutrino TPC

A Time Projection Chamber (TPC) is one of the promising candidates to perform unique measurements in solar neutrino physics. Its features will enable it to work at depths of the order of 2000 mwe. This paper describes an estimation of the expected cosmogenic background at different depths including also the background due to fission activation of the TPC material above ground.

hep-ex↗
arXiv2001

Search for CP Violation in τ-> Kπν_τDecays

We search and find no evidence for CP violation in tau decays into the K pi nu final state. We provide confidence limits on the imaginary part of the coupling constant Lambda, describing a relative contribution of the CP violating processes with respect to the Standard Model, to be -0.155 < Im(Lambda) < 0.047 at 90% C.L.

hep-ex↗
arXiv2001

A Preliminary Look at the Physics Reach of a Solar Neutrino TPC: Time-Independent Two Neutrino Oscillations

This paper will discuss the physics reach of a solar neutrino TPC containing many tons of He4 under high pressure. Particular attention is given to the LMA and SMA solutions, which are allowed by current data, and which are characterized by a lack of time-dependent phenomena (either summer-winter or day-night asymmetries). In this case, the physics of neutrino masses and mixing is all contained in the energy dependence of the electron neutrino survival probability, (or in its reciprocal, the electron neutrino disappearance probability).

hep-ph↗