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51.
Amarian M Auerbach L Averett T Berthot J Bertin P Bertozzi W Black T Brash E Brown D Burtin E Calarco J Cates G Chai Z Chen JP Choi S Chudakov E Cisbani E de Jager CW Deur A DiSalvo R Dieterich S Djawotho P Finn JM Fissum K Fonvieille H Frullani S Gao H Gao J Garibaldi F Gasparian A Gilad S Gilman R Glamazdin A Glashausser C Goldberg E Gomez J Gorbenko V Hansen JO Hersman B Holmes R Huber GM Hughes E Humensky B Incerti S Iodice M Jensen S Jiang X Jones C Jones G Jones M Jutier C Ketikyan A 《Physical review letters》2004,93(15):152301
The generalized forward spin polarizabilities gamma(0) and delta(LT) of the neutron have been extracted for the first time in a Q2 range from 0.1 to 0.9 GeV2. Since gamma(0) is sensitive to nucleon resonances and delta(LT) is insensitive to the Delta resonance, it is expected that the pair of forward spin polarizabilities should provide benchmark tests of the current understanding of the chiral dynamics of QCD. The new results on delta(LT) show significant disagreement with chiral perturbation theory calculations, while the data for gamma(0) at low Q2 are in good agreement with a next-to-leading-order relativistic baryon chiral perturbation theory calculation. The data show good agreement with the phenomenological MAID model. 相似文献
52.
R. S. Garibaldi 《Commentarii Mathematici Helvetici》2001,76(4):684-711
For G a simple simply connected algebraic group defined over a field F, Rost has shown that there exists a canonical map . This includes the Arason invariant for quadratic forms and Rost's mod 3 invariant for exceptional Jordan algebras as special
cases. We show that R
G
has trivial kernel if G is quasi-split of type E
6 or E
7. A case-by-case analysis shows that it has trivial kernel whenever G is quasi-split of low rank.
Received: November 1, 2000 相似文献
53.
Meziane M Brash EJ Gilman R Jones MK Luo W Pentchev L Perdrisat CF Puckett AJ Punjabi V Wesselmann FR Ahmidouch A Albayrak I Aniol KA Arrington J Asaturyan A Ates O Baghdasaryan H Benmokhtar F Bertozzi W Bimbot L Bosted P Boeglin W Butuceanu C Carter P Chernenko S Christy E Commisso M Cornejo JC Covrig S Danagoulian S Daniel A Davidenko A Day D Dhamija S Dutta D Ent R Frullani S Fenker H Frlez E Garibaldi F Gaskell D Gilad S Goncharenko Y Hafidi K Hamilton D Higinbotham DW Hinton W Horn T Hu B 《Physical review letters》2011,106(13):132501
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 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(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5 GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals μ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(?) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε. 相似文献
54.
S. Turck-Chieze P. Barreau M. Bernheim P. Bradu Z.E. Meziani J. Morgenstern A. Bussière G.P. Capitani E. De Sanctis S. Frullani F. Garibaldi J. Mougey 《Physics letters. [Part B]》1984,142(3):145-148
We have determined the 2H(e, e′p)n cross section for neutron recoil momenta between 295 and 500 MeV/c. In this region the 3D1 state contribution is predominant in the deuteron wave function. The high excitation energy (Ecmnp = 179 MeV) and the small momentum transferred (|;qcm|;2 = 1.66 fm?) emphasize the influence of isobar configurations (IC). Experimental data are compared with calculations including isobar contributions, mesonic exchange currents and final state interactions. 相似文献
55.
Barreau P. Bernheim E. Bradu P. Fournier G. Gerard A. Magnon A. Marchand C. Meziani Z. E. Miller J. Morgenstern J. Mougey J. Picard J. Reffay D. Saghai B. Turck-Chieze S. Vernin P. Bussiere de Nergy A. Brussel M. K. Dunn P. Capitani G. P. de Sanctis E. Frullani S. Garibaldi F. 《Czechoslovak Journal of Physics》1986,36(2):296-299
Czechoslovak Journal of Physics - 相似文献
56.
Oakley MT Barthel D Bykov Y Garibaldi JM Burke EK Krasnogor N Hirst JD 《Current protein & peptide science》2008,9(3):260-274
Optimisation problems pervade structural bioinformatics. In this review, we describe recent work addressing a selection of bioinformatics challenges. We begin with a discussion of research into protein structure comparison, and highlight the utility of Kolmogorov complexity as a measure of structural similarity. We then turn to research into de novo protein structure prediction, in which structures are generated from first principles. In this endeavour, there is a compromise between the detail of the model and the extent to which the conformational space of the protein can be sampled. We discuss some developments in this area, including off-lattice structure prediction using the great deluge algorithm. One strategy to reduce the size of the search space is to restrict the protein chain to sites on a regular lattice. In this context, we highlight the use of memetic algorithms, which combine genetic algorithms with local optimisation, to the study of simple protein models on the two-dimensional square lattice and the face-centred cubic lattice. 相似文献
57.
Ron G Glister J Lee B Allada K Armstrong W Arrington J Beck A Benmokhtar F Berman BL Boeglin W Brash E Camsonne A Calarco J Chen JP Choi S Chudakov E Coman L Craver B Cusanno F Dumas J Dutta C Feuerbach R Freyberger A Frullani S Garibaldi F Gilman R Hansen O Higinbotham DW Holmstrom T Hyde CE Ibrahim H Ilieva Y de Jager CW Jiang X Jones MK Kang H Kelleher A Khrosinkova E Kuchina E Kumbartzki G LeRose JJ Lindgren R Markowitz P May-Tal Beck S McCullough E Meekins D Meziane M Meziani ZE Michaels R 《Physical review letters》2007,99(20):202002
High-precision measurements of the proton elastic form-factor ratio, mu pG p E/G p M, have been made at four-momentum transfer, Q2, values between 0.2 and 0.5 GeV2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q2 range the deviation from unity is primarily due to G p E being smaller than expected. 相似文献
58.
Riordan S Abrahamyan S Craver B Kelleher A Kolarkar A Miller J Cates GD Liyanage N Wojtsekhowski B Acha A Allada K Anderson B Aniol KA Annand JR Arrington J Averett T Beck A Bellis M Boeglin W Breuer H Calarco JR Camsonne A Chen JP Chudakov E Coman L Crowe B Cusanno F Day D Degtyarenko P Dolph PA Dutta C Ferdi C Fernández-Ramírez C Feuerbach R Fraile LM Franklin G Frullani S Fuchs S Garibaldi F Gevorgyan N Gilman R Glamazdin A Gomez J Grimm K Hansen JO Herraiz JL Higinbotham DW Holmes R 《Physical review letters》2010,105(26):262302
The electric form factor of the neutron was determined from studies of the reaction 3He(e,e'n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find G(E)(n)=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q(2)=1.72, 2.48, and 3.41 GeV2, respectively. 相似文献
59.
Slifer K Amarian M Auerbach L Averett T Berthot J Bertin P Bertozzi B Black T Brash E Brown D Burtin E Calarco J Cates G Chai Z Chen JP Choi S Chudakov E Ciofi Degli Atti C Cisbani E de Jager CW Deur A DiSalvo R Dieterich S Djawotho P Finn M Fissum K Fonvieille H Frullani S Gao H Gao J Garibaldi F Gasparian A Gilad S Gilman R Glamazdin A Glashausser C Glöckle W Golak J Goldberg E Gomez J Gorbenko V Hansen JO Hersman B Holmes R Huber GM Hughes E Humensky B Incerti S Iodice M Jensen S Jiang X 《Physical review letters》2008,101(2):022303
We present a measurement of the spin-dependent cross sections for the 3He over -->(e over -->,e')X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1< or =Q2< or =0.9 GeV2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region. 相似文献
60.