From jpoudel at jlab.org Wed Dec 3 17:39:26 2025 From: jpoudel at jlab.org (Jiwan Poudel) Date: Wed, 3 Dec 2025 22:39:26 +0000 Subject: [Genrp] GEn-RP analysis meeting at noon tomorrow Message-ID: Dear All, There will be GEn-RP Analysis meeting at noon (EST) tomorrow via Zoom: https://jlab-org.zoomgov.com/j/1607998122?pwd=VWZxMGNRWUgwMzlZTHdkUDIyRS96QT09 . I requested William Tireman to moderate tomorrow?s meeting. Thank you, Jiwan -------------- next part -------------- An HTML attachment was scrubbed... URL: From kohlm at jlab.org Thu Dec 4 13:36:51 2025 From: kohlm at jlab.org (Michael Kohl) Date: Thu, 4 Dec 2025 18:36:51 +0000 Subject: [Genrp] Fwd: FOM "weighted" vs "unweighted" examples from GEp-III/GEp-2gamma References: Message-ID: <809784F2-1CA9-4F90-AB45-999C99EE1D29@jlab.org> Dear all, I am sharing here Andrew?s follow-up message with the mailing list as this is very useful information. Thank you Andrew! ?Michael ============================== Dr. Michael Kohl Interim Chair Joint Professor and Staff Research Scientist Physics Department, Hampton University, Hampton, VA 23668, USA Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606, USA Phone: +1-757-727-5153 (HU office) Email: kohlm at jlab.org ============================== Begin forwarded message: From: Andrew Puckett > Subject: FOM "weighted" vs "unweighted" examples from GEp-III/GEp-2gamma Date: December 4, 2025 at 1:32:25 PM EST To: Michael Kohl > Following up today?s meeting discussion: https://inspirehep.net/literature/1613323 Focus on Figs. 9,10, Table V, Fig. 12, and Table XI. The main variables on which the asymmetry depends are the polar scattering angle in the FPP and the spin precession variation within the acceptance. We should focus on the 2.5 GeV^2 and 8.5 GeV^2 kinematics, since these have precession angles close to 90 deg (270 deg) respectively, so the effect of spin precession on the acceptance-averaged azimuthal asymmetry is minimal. The acceptance-averaged focal-plane asymmetries are shown in Tab. V, with all events passing all the selection criteria. The ratio c/s is a proxy for PT/PL which is a proxy for GE/GM. If I take the weighted average of FPP1 and FPP2 asymmetries in Tab. V for, e.g., the high-epsilon, 2.5 GeV^2, and then form the ratio, the implied relative statistical uncertainty in the FF ratio is about 1.03%. On the other hand, if I go to Table XI, the fractional uncertainty in the final FF ratio from the unbinned ML extraction is 0.85%. So the effect of weighting events by analyzing power (parametrization and distribution shown in Fig. 14 and Tab. VII) and spin transport matrix elements event-by-event (see e.g. Fig. 12) for this kinematics is about a 17% reduction of the error bar. The reduction for 5.2 GeV^2 is obviously much bigger. In SBS the spin precession angle (for protons anyway) is roughly constant within the acceptance (not sure about neutron precession). So the main effect will be the Ay variation within the acceptance. If the Ay distribution is constant, then there would be effectively no difference in FOM between an unbinned ML extraction and extracting the acceptance-average azimuthal asymmetry a la Tab. V and Figs. 9,10. Cheers, Andrew Andrew Puckett Professor, Physics Department University of Connecticut 196 Auditorium Road, Unit 3046 Storrs, CT 06269-3046 Office phone: (860) 486-7137 https://puckett.physics.uconn.edu puckett at jlab.org -------------- next part -------------- An HTML attachment was scrubbed... URL: From jpoudel at jlab.org Thu Dec 11 09:43:35 2025 From: jpoudel at jlab.org (Jiwan Poudel) Date: Thu, 11 Dec 2025 14:43:35 +0000 Subject: [Genrp] No GEn-RP analysis meeting today Message-ID: <81F51C06-32ED-4518-BD1E-B09FA804130A@jlab.org> Dear All, There will be no GEn-RP analysis meeting today. Thank you, Jiwan