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D. Besson

Publications and source records attributed to D. Besson.

At least 91 records · Page 5Linked to original sources
arXiv2009

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↗
arXiv2009

Improved measurements of D meson semileptonic decays to pi and K mesons

Using the entire CLEO-c \psi(3770)-> D\bar{D} event sample, corresponding to an integrated luminosity of $818 pb^-1 and approximately 5.4 million D\bar{D} events, we present a study of the decays D^0 -> \pi^- e^+ \nu_e, D^0 -> K^- e^+ \nu_e, D^+ -> \pi^0 e^+ \nu_e, and D^+ -> \bar{K}^0 e^+ \nu_e. Via a tagged analysis technique, in which one D is fully reconstructed in a hadronic mode, partial rates for semileptonic decays by the other D are measured in several q^2 bins. We fit these rates using several form factor parameterizations and report the results, including form factor shape parameters and the branching fractions B(D^0 -> \pi^- e^+ \nu_e) = (0.288\pm0.008\pm0.003)%, B(D^0 -> K^- e^+ \nu_e) = (3.50\pm0.03\pm0.04)%, B(D^+ -> \pi^0 e^+ \nu_e) = (0.405\pm0.016\pm0.009)%, and B(D^+ -> \bar{K}^0 e^+ \nu_e) = (8.83\pm0.10\pm0.20)%, where the first uncertainties are statistical and the second are systematic. Taking input from lattice quantum chromodynamics (LQCD), we also find |Vcd| = 0.234\pm0.007\pm0.002\pm0.025 and |Vcs| = 0.985\pm0.009\pm0.006\pm0.103, where the third uncertainties are from LQCD.

hep-ex↗
arXiv2008

New Limits on the Ultra-high Energy Cosmic Neutrino Flux from the ANITA Experiment

We report initial results of the first flight of the Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence of a diffuse flux of cosmic neutrinos above energies of 3 EeV. ANITA-1 flew for 35 days looking for radio impulses due to the Askaryan effect in neutrino-induced electromagnetic showers within the Antarctic ice sheets. We report here on our initial analysis, which was performed as a blind search of the data. No neutrino candidates are seen, with no detected physics background. We set model-independent limits based on this result. Upper limits derived from our analysis rule out the highest cosmogenic neutrino models. In a background horizontal-polarization channel, we also detect six events consistent with radio impulses from ultra-high energy extensive air showers.

astro-ph↗
arXiv2008

The Antarctic Impulsive Transient Antenna Ultra-high Energy Neutrino Detector Design, Performance, and Sensitivity for 2006-2007 Balloon Flight

We present a detailed report on the experimental details of the Antarctic Impulsive Transient Antenna (ANITA) long duration balloon payload, including the design philosophy and realization, physics simulations, performance of the instrument during its first Antarctic flight completed in January of 2007, and expectations for the limiting neutrino detection sensitivity. Neutrino physics results will be reported separately.

astro-ph↗
arXiv2008

Simulation of a hybrid optical-radio-acoustic neutrino detector at the South Pole

With construction halfway complete, IceCube is already the most sensitive neutrino telescope ever built. A rearrangement of the final holes of IceCube with increased spacing has been discussed recently to optimize the high energy sensitivity of the detector. Extending this baseline with radio and acoustic instrumentation in the same holes could further improve the high energy response. The goal would be both to detect events and to act as a pathfinder for hybrid detection, towards a possible larger hybrid array. Simulation results for such an array are presented here.

astro-ph↗
arXiv2008

In situ radioglaciological measurements near Taylor Dome, Antarctica and implications for UHE neutrino astronomy

Radiowave detection of the Cherenkov radiation produced by neutrino-ice collisions requires an understanding of the radiofrequency (RF) response of cold polar ice. We herein report on a series of radioglaciological measurements performed approximately 10 km north of Taylor Dome Station, Antarctica from Dec. 6, 2006 - Dec. 16, 2006. Using RF signals broadcast from: a) an englacial discone, submerged to a depth of 100 meters and broadcasting to a surface dual polarization horn receiver, and b) a dual-polarization horn antenna on the surface transmitting signals which reflect off the underlying bed and back up to the surface receiver, we have made time-domain estimates of both the real (index-of-refraction) and imaginary (attenuation length) components of the complex ice dielectric constant. We have also measured the uniformity of ice response along two orthogonal axes in the horizontal plane. We observe a wavespeed asymmetry of order 0.1%, projected onto the vertical propagation axis, consistent with some previous measurements, but somewhat lower than others.

astro-ph↗
arXiv2008

Parton fragmentation in the vacuum and in the medium

We present the mini-proceedings of the workshop on ``Parton fragmentation in the vacuum and in the medium'' held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) in February 2008. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of quark and gluon fragmentation into hadrons at different accelerator facilities (LEP, B-factories, JLab, HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) light-quark and gluon fragmentation in the vacuum including theoretical (global fits analyses and MLLA) and experimental (data from e+e-, p-p, e-p collisions) aspects, (ii) strange and heavy-quark fragmentation, (iii) parton fragmentation in cold QCD matter (nuclear DIS), and (iv) medium-modified fragmentation in hot and dense QCD matter (high-energy nucleus-nucleus collisions). These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.

hep-ph↗
arXiv2006

Limits on the Transient Ultra-High Energy Neutrino Flux from Gamma-Ray Bursts (GRB) Derived from RICE Data

We present limits on ultra-high energy (UHE; E(nu)>1 PeV) neutrino fluxes from gamma-ray bursts (GRBs), based on recently presented data, limits, and simulations from the RICE experiment. We use data from five recorded transients with sufficient photon spectral shape and redshift information to derive an expected neutrino flux, assuming that the observed photons are linked to neutrino production through pion decay via the well-known 'Waxman-Bahcall' prescription. Knowing the declination of the observed burst, as well as the RICE sensitivity as a function of polar angle and the previously published non-observation of any neutrino events allows an estimate of the sensitivity to a given neutrino flux. Although several orders of magnitude weaker than the expected fluxes, our GRB neutrino flux limits are nevertheless the first in the PeV--EeV energy regime. For completeness, we also provide a listing of other bursts, recorded at times when the RICE experiment was active, but requiring some assumptions regarding luminosity and redshift to permit estimates of the neutrino flux.

astro-ph↗
arXiv2006

First Observation of Upsilon(3S) --> tau tau and Tests of Lepton Universality in Upsilon Decays

Using data collected with the CLEO-III detector at the CESR e+e- collider, we report on a first observation of the decay of the Upsilon(3S) to tau tau, and precisely measure the ratio of branching fractions of Upsilon(nS),n=1,2,3 to tau tau and mu mu final states, finding agreement with expectations from lepton universality. We derive absolute branching fractions for these decays, and also set a limit on the influence of a low mass CP-odd Higgs boson in the decay of the Upsilon(1S).

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arXiv2005

Simulation of a Hybrid Optical/Radio/Acoustic Extension to IceCube for EeV Neutrino Detection

Astrophysical neutrinos at $\sim$EeV energies promise to be an interesting source for astrophysics and particle physics. Detecting the predicted cosmogenic (``GZK'') neutrinos at 10$^{16}$ - 10$^{20}$ eV would test models of cosmic ray production at these energies and probe particle physics at $\sim$100 TeV center-of-mass energy. While IceCube could detect $\sim$1 GZK event per year, it is necessary to detect 10 or more events per year in order to study temporal, angular, and spectral distributions. The IceCube observatory may be able to achieve such event rates with an extension including optical, radio, and acoustic receivers. We present results from simulating such a hybrid detector.

astro-ph↗
arXiv2005

Measurement of the Direct Photon Momentum Spectrum in Upsilon(1S), Upsilon(2S), and Upsilon(3S) Decays

Using data taken with the CLEO III detector at the Cornell Electron Storage Ring, we have investigated the direct photon spectrum in the decays Upsilon(1S) -> gggamma, Upsilon(2S) -> gggamma, Upsilon}(3S) -> gggamma. The latter two of these are first measurements. Our analysis procedures differ from previous ones in the following ways: a) background estimates (primarily from pi^0 decays are based on isospin symmetry rather than a determination of the pi^0 spectrum, which permits measurement of the Upsilon(2S) and Upsilon(3S) direct photon spectra without explicit corrections for pi^0 backgrounds from, e.g., chi_bJ states, b) we estimate the branching fractions with a parametrized functional form (exponential) used for the background, c) we use the high-statistics sample of Upsilon(2S) -> pi+ pi- Upsilon(1S) to obtain a tagged-sample of Upsilon(1S) -> gamma + X events, for which there are no QED backgrounds. We determine values for the ratio of the inclusive direct photon decay rate to that of the dominant three-gluon decay Upsilon -> ggg (R_gamma=B(gggamma)/B(ggg)) to be: R_gamma(1S)=(2.70+/-0.01+/-0.13+/-0.24)%, R_gamma(2S)=(3.18+/-0.04+/-0.22+/-0.41)%, and R_gamma(3S)=(2.72+/-0.06+/-0.32+/-0.37)%, where the errors shown are statistical, systematic, and theoretical model-dependent, respectively. Given a value of Q^2, one can estimate a value for the strong coupling constant alpha_s(Q^2) from R_gamma.

hep-ex↗
arXiv2005

Measurement of sigma(e^+e^- --> psi(3770) --> hadrons) at E_{cm}=3773 MeV

We measure the cross section for e^+e^- -> \psi(3770) -> hadrons at Ecm=3773 MeV to be (6.38+-0.08^{+0.41}_{-0.30}) nb using the CLEO detector at the CESR e^+e^- collider. The difference between this and the e^+e^- -> \psi(3770) -> DD-bar cross section at the same energy is found to be (-0.01+-0.08^{+0.41}_{-0.30}) nb. With the observed total cross section, we extract \Gamma_ee(\psi(3770))=(0.204+-0.003^{+0.041}_{-0.027}) keV. Uncertainties shown are statistical and systematic, respectively.

hep-ex↗
arXiv2005

Radiative Decays of the Upsilon(1S) to gamma pi^0 pi^0, and gamma eta eta and gamma pi^0 eta

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into the final states gamma pi^0 pi^0, gamma eta eta and gamma pi^0 eta, using 1.13 inverse femto-barn of e^+ e^- annihilation data collected at sqrt(s)= 9.46 GeV with the CLEO III detector operating at the Cornell Electron Storage Ring. In the channel gamma pi^0 pi^0, we measure the branching ratio for the decay mode Upsilon(1S) to gamma f_2(1270) to be (10.5 \pm 1.6 (+ 1.9)(-1.8)) x 10^-5. We place upper limits on the product branching ratios for the isoscalar resonances f_0(1500) and f_0(1710) for the pi^0 pi^0 and eta-eta decay channels. We also set an upper limit on the Upsilon(1S) radiative decay into pi^0 eta.

hep-ex↗
arXiv2004

Search for $e^+e^- --> Lambda_b^0 barLambda_b^0 Near Threshold

Using the CLEO III detector at CESR we study e+e- collisions in the center-of-mass energy close to, or above, Lambda_b anti-Lambda_b production threshold. We search for evidence of Lambda_b anti-Lambda_b resonance production and set upper limits based on inclusive hadron production as a barometer of Lambda_b anti-Lambda_b production.

hep-ex↗
arXiv2004

Measurement of \cal{B}(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant $f_{D^+}$

In 60 pb-1 of data taken on the psi(3770) resonance with the CLEO-c detector, we find 8 D+ to mu+ nu event candidates that are mostly signal, containing only 1 estimated background. Using this statistically compelling sample, we measure preliminary values of B(D+ to mu+ nu) = (3.5 +- 1.4 +- 0.6)*10^{-4}, and determine f_{D+} =(201+- 41+- 17) MeV.

hep-ex↗
arXiv2003

Addendum to "Coherent radio pulses from GEANT generated electromagnetic showers in ice"

We reevaluate our published calculations of electromagnetic showers generated by GEANT 3.21 and the radio frequency pulses they produce in ice. We are prompted by a recent report showing that GEANT 3.21-modeled showers are sensitive to internal settings in the electron tracking subroutine. We report the shower and pulse characteristics obtained with different settings of GEANT 3.21 and with GEANT 4. The default setting of electron tracking in GEANT 3.21 we used in previous work speeds up the shower simulation at the cost of information near the end of the tracks. We find that settings tracking electron and positron to lower energy yield a more accurate calculation, a more intense shower, and proportionately stronger radio pulses at low frequencies. At high frequencies the relation between shower tracking algorithm and pulse spectrum is more complex. We obtain radial distributions of shower particles and phase distributions of pulses from 100 GeV showers that are consistent with our published results.

astro-ph↗
arXiv2003

Observation of a Narrow Resonance of Mass 2.46 GeV/c^2 Decaying to D_s^*+ pi^0 and Confirmation of the D_sJ^* (2317) State

Using 13.5 inverse fb of e+e- annihilation data collected with the CLEO II detector we have observed a narrow resonance in the Ds*+pi0 final state, with a mass near 2.46 GeV. The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32 GeV, the DsJ*(2317)+ that decays to Ds+pi0. Reconstructing the Ds+pi0 and Ds*+pi0 final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, dM(Dspi0)=M(Dspi0)-M(Ds) and dM(Ds*pi0)=M(Ds*pi0)-M(Ds*), both of them at values near 350 MeV. We interpret these peaks as signatures of two distinct states, the DsJ*(2317)+ plus a new state, designated as the DsJ(2463)+. Because of the similar dM values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences = 350.0 +/- 1.2 [stat] +/- 1.0 [syst] MeV for the DsJ*(2317) state, and = 351.2 +/- 1.7 [stat] +/- 1.0 [syst] MeV for the new DsJ(2463)+ state. We have also searched, but find no evidence, for decays of the two states via the channels Ds*+gamma, Ds+gamma, and Ds+pi+pi-. The observations of the two states at 2.32 and 2.46 GeV, in the Ds+pi0 and Ds*+pi0 decay channels respectively, are consistent with their interpretations as (c anti-strange) mesons with orbital angular momentum L=1, and spin-parities of 0+ and 1+.

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