<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Revised version now on the arXiv.<br class=""><div class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""> Cheers,<br class=""> Douglas<br class=""><br class="">26-415 M.I.T. Tel: +1 (617) 258-7199<br class="">77 Massachusetts Avenue Fax: +1 (617) 258-5440<br class="">Cambridge, MA 02139, USA E-mail: <a href="mailto:hasell@mit.edu" class="">hasell@mit.edu</a><br class=""><br class=""><br class=""><div style="color: rgb(0, 0, 0); font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-family: Helvetica; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""></div></div></div></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">
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<div style=""><br class=""><blockquote type="cite" class=""><div class="">Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><<a href="mailto:e-prints@arxiv.org" class="">e-prints@arxiv.org</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">arXiv Replacement -> 1611.04685 in nucl-ex from <a href="mailto:hasell@mit.edu" class="">hasell@mit.edu</a></b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">December 20, 2016 at 20:12:02 EST<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><<a href="mailto:hasell@mit.edu" class="">hasell@mit.edu</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Reply-To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><<a href="mailto:help@arxiv.org" class="">help@arxiv.org</a>><br class=""></span></div><br class=""><div class=""><div class="">Your replacement of 1611.04685 by submission submit/1756935 has<br class="">been published and is available at:<br class=""><br class=""><a href="http://arxiv.org/abs/1611.04685" class="">http://arxiv.org/abs/1611.04685</a><br class=""><br class=""><br class="">The paper password for this article is: pacub<br class="">Please share this with your co-authors. They may use it to claim<br class="">ownership.<br class=""><br class=""><br class="">Abstract will appear in today's mailing as:<br class="">------------------------------------------------------------------------------<br class="">\\<br class="">arXiv:1611.04685<br class="">From: Douglas Hasell <hasell@mit.edu><br class="">Date: Tue, 15 Nov 2016 03:14:35 GMT (187kb,D)<br class="">Date (revised v2): Tue, 20 Dec 2016 02:32:11 GMT (265kb,D)<br class=""><br class="">Title: Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering:<br class=""> Determined by the OLYMPUS Experiment<br class="">Authors: B.S. Henderson and L.D. Ice and D. Khaneft and C. O'Connor and R.<br class=""> Russell and A. Schmidt and J.C. Bernauer and M. Kohl and N. Akopov and R.<br class=""> Alarcon and O. Ates and A. Avetisyan and R. Beck and S. Belostotski and J.<br class=""> Bessuille and F. Brinker and J.R. Calarco and V. Carassiti and E. Cisbani and<br class=""> G. Ciullo and M. Contalbrigo and R. De Leo and J. Diefenbach and T.W.<br class=""> Donnelly and K. Dow and G. Elbakian and P.D. Eversheim and S. Frullani and<br class=""> Ch. Funke and G. Gavrilov and B. Gl\"aser and N. G\"orrissen and D.K. Hasell<br class=""> and J. Hauschildt and Ph. Hoffmeister and Y. Holler and E. Ihloff and A.<br class=""> Izotov and R. Kaiser and G. Karyan and J. Kelsey and A. Kiselev and P.<br class=""> Klassen and A. Krivshich and I. Lehmann and P. Lenisa and D. Lenz and S.<br class=""> Lumsden and Y. Ma and F. Maas and H. Marukyan and O. Miklukho and R.G. Milner<br class=""> and A. Movsisyan and M. Murray and Y. Naryshkin and R. Perez Benito and R.<br class=""> Perrino and R.P. Redwine and D. Rodr\'iguez Pi\~neiro and G. Rosner and U.<br class=""> Schneekloth and B. Seitz and M. Statera and A. Thiel and H. Vardanyan and D.<br class=""> Veretennikov and C. Vidal and A. Winnebeck and V. Yeganov<br class="">Categories: nucl-ex<br class="">Comments: 5 pages, 3 figures, 2 tables<br class="">License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/<br class="">\\<br class=""> The OLYMPUS collaboration reports on a precision measurement of the<br class="">positron-proton to electron-proton elastic cross section ratio, $R_{2\gamma}$,<br class="">a direct measure of the contribution of hard two-photon exchange to the elastic<br class="">cross section. In the OLYMPUS measurement, 2.01~GeV electron and positron beams<br class="">were directed through a hydrogen gas target internal to the DORIS storage ring<br class="">at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and<br class="">time-of-flight scintillators detected elastically scattered leptons in<br class="">coincidence with recoiling protons over a scattering angle range of $\approx<br class="">20\degree$ to $80\degree$. The relative luminosity between the two beam species<br class="">was monitored using tracking telescopes of interleaved GEM and MWPC detectors<br class="">at $12\degree$, as well as symmetric M{\o}ller/Bhabha calorimeters at<br class="">$1.29\degree$. A total integrated luminosity of 4.5~fb$^{-1}$ was collected. In<br class="">the extraction of $R_{2\gamma}$, radiative effects were taken into account<br class="">using a Monte Carlo generator to simulate the convolutions of internal<br class="">bremsstrahlung with experiment-specific conditions such as detector acceptance<br class="">and reconstruction efficiency. The resulting values of $R_{2\gamma}$, presented<br class="">here for a wide range of virtual photon polarization $0.456<\epsilon<0.978$,<br class="">are smaller than some hadronic two-photon exchange calculations predict, but<br class="">are in reasonable agreement with a subtracted dispersion model and a<br class="">phenomenological fit to the form factor data.<br class="">\\<br class=""><br class=""><br class="">Contains:<br class=""> diffblunden.pdf: 73474 bytes<br class=""> r2gamma_1mot.pdf: 90948 bytes<br class=""> rad_corr_compare.pdf: 94440 bytes<br class=""> tpeprl.bbl: 23347 bytes<br class=""> tpeprl.tex: 29074 bytes<br class=""><br class=""><br class=""></div></div></blockquote></div><br class=""></body></html>