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Search Results: 1 - 10 of 208443 matches for " L. Bimbot "
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Phenomenological insight into JLab proton polarization data puzzle by deuteron impulse approximation
Adamuscin, C.;Bimbot, L.;Dubnicka, S.;Dubnickova, A. Z.;Tomasi-Gustafsson, E.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevC.78.025202
Abstract: The non-relativistic impulse approximation of deuteron electromagnetic form factors is used to investigate the space-like region behavior of the proton electric form factor in regard of the two contradictory experimental results extracted either from Rosenbluth separation method or from recoil proton JLab polarization data.
Observation of coherent $π^0$ electroproduction on deuterons at large momentum transfer
E. Tomasi-Gustafsson,L. Bimbot,S. Danagoulian,K. Gustafsson,D. Mack,H. Mrktchyan,M. P. Rekalo
Physics , 2003, DOI: 10.1134/1.1634323
Abstract: The first experimental results for coherent $\pi^0$-electroproduction on the deuteron, $e+d\to e+d +\pi^0$, at large momentum transfer, are reported. The experiment was performed at Jefferson Laboratory at an incident electron energy of 4.05 GeV. A large pion production yield has been observed in a kinematical region for 1.1$
G$^0$ Electronics and Data Acquisition (Forward-Angle Measurements)
D. Marchand,J. Arvieux,L. Bimbot,A. Biselli,J. Bouvier,H. Breuer,R. Clark,J. -C. Cuzon,M. Engrand,R. Foglio,C. Furget,X. Grave,B. Guillon,H. Guler,P. M. King,S. Kox,J. Kuhn,Y. Ky,J. Lachniet,J. Lenoble,E. Liatard,J. Liu,E. Munoz,J. Pouxe,G. Quéméner,B. Quinn,J. -S. Réal,O. Rossetto,R. Sellem
Physics , 2007, DOI: 10.1016/j.nima.2007.11.028
Abstract: The G$^0$ parity-violation experiment at Jefferson Lab (Newport News, VA) is designed to determine the contribution of strange/anti-strange quark pairs to the intrinsic properties of the proton. In the forward-angle part of the experiment, the asymmetry in the cross section was measured for $\vec{e}p$ elastic scattering by counting the recoil protons corresponding to the two beam-helicity states. Due to the high accuracy required on the asymmetry, the G$^0$ experiment was based on a custom experimental setup with its own associated electronics and data acquisition (DAQ) system. Highly specialized time-encoding electronics provided time-of-flight spectra for each detector for each helicity state. More conventional electronics was used for monitoring (mainly FastBus). The time-encoding electronics and the DAQ system have been designed to handle events at a mean rate of 2 MHz per detector with low deadtime and to minimize helicity-correlated systematic errors. In this paper, we outline the general architecture and the main features of the electronics and the DAQ system dedicated to G$^0$ forward-angle measurements.
Well-posedness of the permutation problem in sparse filter estimation with lp minimization
Alexis Benichoux,Prasad Sudhakar,Frédéric Bimbot,Rémi Gribonval
Mathematics , 2011,
Abstract: Convolutive source separation is often done in two stages: 1) estimation of the mixing filters and 2) estimation of the sources. Traditional approaches suffer from the ambiguities of arbitrary permutations and scaling in each frequency bin of the estimated filters and/or the sources, and they are usually corrected by taking into account some special properties of the filters/sources. This paper focusses on the filter permutation problem in the absence of scaling, investigating the possible use of the temporal sparsity of the filters as a property enabling permutation correction. Theoretical and experimental results highlight the potential as well as the limits of sparsity as an hypothesis to obtain a well-posed permutation problem.
Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio to Q^2 = 8.5 GeV^2
A. J. R. Puckett,E. J. Brash,M. K. Jones,W. Luo,M. Meziane,L. Pentchev,C. F. Perdrisat,V. Punjabi,F. R. Wesselmann,A. Ahmidouch,I. Albayrak,K. A. Aniol,J. Arrington,A. Asaturyan,H. Baghdasaryan,F. Benmokhtar,W. Bertozzi,L. Bimbot,P. Bosted,W. Boeglin,C. Butuceanu,P. Carter,S. Chernenko,E. Christy,M. Commisso,J. C. Cornejo,S. Covrig,S. Danagoulian,A. Daniel,A. Davidenko,D. Day,S. Dhamija,D. Dutta,R. Ent,S. Frullani,H. Fenker,E. Frlez,F. Garibaldi,D. Gaskell,S. Gilad,R. Gilman,Y. Goncharenko,K. Hafidi,D. Hamilton,D. W. Higinbotham,W. Hinton,T. Horn,B. Hu,J. Huang,G. M. Huber,E. Jensen,C. Keppel,M. Khandaker,P. King,D. Kirillov,M. Kohl,V. Kravtsov,G. Kumbartzki,Y. Li,V. Mamyan,D. J. Margaziotis,A. Marsh,Y. Matulenko,J. Maxwell,G. Mbianda,D. Meekins,Y. Melnik,J. Miller,A. Mkrtchyan,H. Mkrtchyan,B. Moffit,O. Moreno,J. Mulholland,A. Narayan,S. Nedev,Nuruzzaman,E. Piasetzky,W. Pierce,N. M. Piskunov,Y. Prok,R. D. Ransome,D. S. Razin,P. Reimer,J. Reinhold,O. Rondon,M. Shabestari,A. Shahinyan,K. Shestermanov,S. Sirca,I. Sitnik,L. Smykov,G. Smith,L. Solovyev,P. Solvignon,R. Subedi,E. Tomasi-Gustafsson,A. Vasiliev,M. Veilleux,B. B. Wojtsekhowski,S. Wood,Z. Ye,Y. Zanevsky,X. Zhang,Y. Zhang,X. Zheng,L. Zhu
Physics , 2010, DOI: 10.1103/PhysRevLett.104.242301
Abstract: Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6.7, and 8.5 GeV2. By extending the range of Q2 for which GEp is accurately determined by more than 50%, these measurements will provide significant constraints on models of nucleon structure in the non-perturbative regime.
Polarization components in $π^{0}$ photoproduction at photon energies up to 5.6 GeV
W. Luo,E. J. Brash,R. Gilman,M. K. Jones,M. Meziane,L. Pentchev,C. F. Perdrisat,A. J. R. Puckett,V. Punjabi,F. R. Wesselmann,A. Ahmidouch,I. Albayrak,K. A. Aniol,J. Arrington,A. Asaturyan,O. Ates,H. Baghdasaryan,F. Benmokhtar,W. Bertozzi,L. Bimbot,P. Bosted,W. Boeglin,C. Butuceanu,P. Carter,S. Chernenko,M. E. Christy,M. Commisso,J. C. Cornejo,S. Covrig,S. Danagoulian,A. Daniel,A. Davidenko,D. Day,S. Dhamija,D. Dutta,R. Ent,S. Frullani,H. Fenker,E. Frlez,F. Garibaldi,D. Gaskell,S. Gilad,Y. Goncharenko,K. Hafidi,D. Hamilton,D. W. Higinbotham,W. Hinton,T. Horn,B. Hu,J. Huang,G. M. Huber,E. Jensen,H. Kang,C. Keppel,M. Khandaker,P. King,D. Kirillov,M. Kohl,V. Kravtsov,G. Kumbartzki,Y. Li,V. Mamyan,D. J. Margaziotis,P. Markowitz,A. Marsh,Y. Matulenko,J. Maxwell,G. Mbianda,D. Meekins,Y. Melnik,J. Miller,A. Mkrtchyan,H. Mkrtchyan,B. Moffit,O. Moreno,J. Mulholland,A. Narayan,Nuruzzaman,S. Nedev,E. Piasetzky,W. Pierce,N. M. Piskunov,Y. Prok,R. D. Ransome,D. S. Razin,P. E. Reimer,J. Reinhold,O. Rondon,M. Shabestari,A. Shahinyan,K. Shestermanov,S. Sirca,I. Sitnik,L. Smykov,G. Smith,L. Solovyev,P. Solvignon,I. I. Strakovsky,R. Subedi,R. Suleiman,E. Tomasi-Gustafsson,A. Vasiliev,M. Veilleux,S. Wood,Z. Ye,Y. Zanevsky,X. Zhang,Y. Zhang,X. Zheng,L. Zhu
Physics , 2011, DOI: 10.1103/PhysRevLett.108.222004
Abstract: We present new data for the polarization observables of the final state proton in the $^{1}H(\vec{\gamma},\vec{p})\pi^{0}$ reaction. These data can be used to test predictions based on hadron helicity conservation (HHC) and perturbative QCD (pQCD). These data have both small statistical and systematic uncertainties, and were obtained with beam energies between 1.8 and 5.6 GeV and for $\pi^{0}$ scattering angles larger than 75$^{\circ}$ in center-of-mass (c.m.) frame. The data extend the polarization measurements data base for neutral pion photoproduction up to $E_{\gamma}=5.6 GeV$. The results show non-zero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and $\pi^{0}$ scattering angle in c.m. frame. This indicates that HHC does not hold and that the pQCD limit is still not reached in the energy regime of this experiment.
Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasi-elastic Electron-Deuteron Scattering
The G0 Collaboration,D. Androi?,D. S. Armstrong,J. Arvieux,S. L. Bailey,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,P. Bosted,H. Breuer,C. L. Capuano,Y. -C. Chao,A. Coppens,C. A. Davis,C. Ellis,G. Flores,G. Franklin,C. Furget,D. Gaskell,M. T. W. Gericke,J. Grames,G. Guillard,J. Hansknecht,T. Horn,M. K. Jones,P. M. King,W. Korsch,S. Kox,L. Lee,J. Liu,A. Lung,J. Mammei,J. W. Martin,R. D. McKeown,A. Micherdzinska,M. Mihovilovic,H. Mkrtchyan,M. Muether,S. A. Page,V. Papavassiliou,S. F. Pate,10 S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,B. Quinn,W. D. Ramsay,J. -S. Real,J. Roche,P. Roos,J. Schaub,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,M. Stutzman,R. Suleiman,V. Tadevosyan,W. T. H. van Oers,M. Versteegen,E. Voutier,W. Vulcan,S. P. Wells,S. E. Williamson,S. A. Wood,B. Pasquini,M. Vanderhaeghen
Physics , 2011, DOI: 10.1103/PhysRevLett.107.022501
Abstract: We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasi-elastic scattering on the deuteron, at backward angles (lab scattering angle of 108 degrees) for Q2 = 0.22 GeV^2/c^2 and 0.63 GeV^2/c^2 at beam energies of 362 MeV and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (piN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasi-static deuterium approximation, and is also in agreement with theory.
First Measurement of the Neutral Current Excitation of the Delta Resonance on a Proton Target
G0 Collaboration,D. Androic,D. S. Armstrong,J. Arvieux,S. L. Bailey,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,P. Bosted,H. Breuer,C. L. Capuano,Y. -C. Chao,A. Coppens,C. A. Davis,C. Ellis,G. Flores,G. Franklin,C. Furget,D. Gaskell,J. Grames,M. T. W. Gericke,G. Guillard,J. Hansknecht,T. Horn,M. K. Jones,P. M. King,W. Korsch,S. Kox,L. Lee,J. Liu,A. Lung,J. Mammei,J. W. Martin,R. D. McKeown,A. Micherdzinska,M. Mihovilovic,H. Mkrtchyan,M. Muether,S. A. Page,V. Papavassiliou,S. F. Pate,S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,B. Quinn,W. D. Ramsay,J. -S. Real,J. Roche,P. Roos,J. Schaub,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,M. Stutzman,R. Suleiman,V. Tadevosyan,W. T. H. van Oers,M. Versteegen,E. Voutier,W. Vulcan,S. P. Wells,S. E. Williamson,S. A. Wood
Physics , 2012,
Abstract: The parity-violating asymmetry arising from inelastic electron-nucleon scattering at backward angle (~95 degrees) near the Delta(1232) resonance has been measured using a hydrogen target. From this asymmetry, we extracted the axial transition form factor G^A_{N\Delta}, a function of the axial Adler form factors C^A_i. Though G^A_{N\Delta} has been previously studied using charged current reactions, this is the first measurement of the weak neutral current excitation of the Delta using a proton target. For Q^2 = 0.34 (GeV/c)^2 and W = 1.18 GeV, the asymmetry was measured to be -33.4 \pm (5.3)_{stat} \pm (5.1)_{sys} ppm. The value of G^A_{N\Delta} determined from the hydrogen asymmetry was -0.05 \pm (0.35)_{stat} \pm (0.34)_{sys} \pm (0.06)_{theory}. These findings agree within errors with theoretical predictions for both the total asymmetry and the form factor. In addition to the hydrogen measurement, the asymmetry was measured at the same kinematics using a deuterium target. The asymmetry for deuterium was determined to be -43.6 \pm (14.6)_{stat} \pm (6.2)_{sys} ppm.
Measurement of the parity-violating asymmetry in inclusive electroproduction of $π^-$ near the $Δ^0$ resonance
G0 Collaboration,D. Androi?,D. S. Armstrong,J. Arvieux,S. L. Bailey,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,P. Bosted,H. Breuer,C. L. Capuano,Y. -C. Chao,A. Coppens,C. A. Davis,C. Ellis,G. Flores,G. Franklin,C. Furget,D. Gaskell,M. T. W. Gericke,J. Grames,G. Guillard,J. Hansknecht,T. Horn,M. K. Jones,P. M. King,W. Korsch,S. Kox,L. Lee,J. Liu,A. Lung,J. Mammei,J. W. Martin,R. D. McKeown,A. Micherdzinska,M. Mihovilovic,H. Mkrtchyan,M. Muether,S. A. Page,V. Papavassiliou,S. F. Pate,S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,B. Quinn,W. D. Ramsay,J. -S. Real,J. Roche,P. Roos,J. Schaub,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,M. Stutzman,R. Suleiman,V. Tadevosyan,W. T. H. van Oers,M. Versteegen,E. Voutier,W. Vulcan,S. P. Wells,S. E. Williamson,S. A. Wood
Physics , 2011, DOI: 10.1103/PhysRevLett.108.122002
Abstract: The parity-violating (PV) asymmetry of inclusive $\pi^-$ production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasi-free photoproduction off the neutron via the $\Delta^0$ resonance. In the context of heavy-baryon chiral perturbation theory (HB$\chi$PT), this asymmetry is related to a low energy constant $d_\Delta^-$ that characterizes the parity-violating $\gamma$N$\Delta$ coupling. Zhu et al. calculated $d_\Delta^-$ in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from $A_\gamma^-=-5.2$ to $+5.2$ ppm. The measurement performed in this work leads to $A_\gamma^-=-0.36\pm 1.06\pm 0.37\pm 0.03$ ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to $V_{ud}/V_{us}$. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the $N-\Delta$ axial transition form-factors using PV electron scattering.
Search for effects beyond the Born approximation in polarization transfer observables in $\vec{e}p$ elastic scattering
M. Meziane,E. J. Brash,R. Gilman,M. K. Jones,W. Luo,L. Pentchev,C. F. Perdrisat,A. J. R. Puckett,V. Punjabi,F. R. Wesselmann,A. Ahmidouch,I. Albayrak,K. A. Aniol,J. Arrington,A. Asaturyan,O. Ates,H. Baghdasaryan,F. Benmokhtar,W. Bertozzi,L. Bimbot,P. Bosted,W. Boeglin,C. Butuceanu,P. Carter,S. Chernenko,E. Christy,M. Commisso,J. C. Cornejo,S. Covrig,S. Danagoulian,A. Daniel,A. Davidenko,D. Day,S. Dhamija,D. Dutta,R. Ent,S. Frullani,H. Fenker,E. Frlez,F. Garibaldi,D. Gaskell,S. Gilad,Y. Goncharenko,K. Hafidi,D. Hamilton,D. W. Higinbotham,W. Hinton,T. Horn,B. Hu,J. Huang,G. M. Huber,E. Jensen,H. Kang,C. Keppel,M. Khandaker,P. King,D. Kirillov,M. Kohl,V. Kravtsov,G. Kumbartzki,Y. Li,V. Mamyan,D. J. Margaziotis,P. Markowitz,A. Marsh,Y. Matulenko,J. Maxwell,G. Mbianda,D. Meekins,Y. Melnik,J. Miller,A. Mkrtchyan,H. Mkrtchyan,B. Moffit,O. Moreno,J. Mulholland,A. Narayan,Nuruzzaman,S. Nedev,E. Piasetzky,W. Pierce,N. M. Piskunov,Y. Prok,R. D. Ransome,D. S. Razin,P. E. Reimer,J. Reinhold,O. Rondon,M. Shabestari,A. Shahinyan,K. Shestermanov,S. Sirca,I. Sitnik,L. Smykov,G. Smith,L. Solovyev,P. Solvignon,R. Subedi,R. Suleiman,E. Tomasi-Gustafsson,A. Vasiliev,M. Vanderhaeghen,M. Veilleux,B. B. Wojtsekhowski,S. Wood,Z. Ye,Y. Zanevsky,X. Zhang,Y. Zhang,X. Zheng,L. Zhu
Statistics , 2010, DOI: 10.1103/PhysRevLett.106.132501
Abstract: Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_{E}/G_{M}$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $H(\vec{e},e'\vec{p})$ reaction for three different beam energies at a fixed squared momentum transfer $Q^2 = 2.5$ GeV$^2$, spanning a wide range of the virtual photon polarization parameter, $\epsilon$. From these measured polarization observables, we have obtained separately the ratio $R$, which equals $\mu_p G_{E}/G_{M}$ in the Born approximation, and the longitudinal polarization transfer component $P_\ell$, with statistical and systematic uncertainties of $\Delta R \approx \pm 0.01 \mbox{(stat)} \pm 0.013 \mbox{(syst)}$ and $\Delta P_\ell/P^{Born}_{\ell} \approx \pm 0.006 \mbox{(stat)}\pm 0.01 \mbox{(syst)}$. The ratio $R$ is found to be independent of $\epsilon$ at the 1.5% level, while the $\epsilon$ dependence of $P_\ell$ shows an enhancement of $(2.3 \pm 0.6) %$ relative to the Born approximation at large $\epsilon$.
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