<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif; "><div><div><div>Dear Hall A and SBS Collaborators,</div><div><br></div><div> As you've heard already, our SBS+BB SIDIS Delta-q proposal (PR12-14-008) has been DEFERRED at PAC42.</div><div><br></div><div> From the closeout and PAC42 feedbacks we understand that: w<span class="Apple-style-span" style="font-family: Calibri; font-size: medium; ">e did not succeed in convincing the PAC that the Hall A pol 3He with SBS+BB option has a "Significantly Higher Impact" than the already approved "high-impact" CLAS12 NH3+ND3 experiment (E12-09-007), although we've presented to the Committee a detailed bin-by-bin comparison showing that we are at least three to four times better off in determining neutron SIDIS asymmetry than CLAS12.</span></div><div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">We will resubmit this proposal again to the next PAC, with the following improvements in mind:</span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">1. Clearly show the bin-by-bin comparison of CLAS12 neutron asymmetry (deuteron - proton) vs the Hall A 3He case, under the same kinematic cuts.</span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">2. Emphasis that Hall A SBS+BB combination can measure spin-dependent SIDIS cross sections, and show the projected precision of measuring SIDIS multiplicities as well as the double-spin asymmetries. Expected precisions on \pi+ - \pi- flavor non-singlet asymmetries vs z. </span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">3. Make a convincing case that our higher-Q2 coverage in Hall A would help to better understand the behavior SIDIS asymmetries and multiplicities, and reduce interpretation systematics.</span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">4. Expand the physics impact discussion to cover more TMD physics for valence quarks at high-x and high-Q2, with single-spin asymmetries A_UL sin(2\phi_h) etc, and double-spin asymmetries. Layout the impacts to Transversity measurement in separating Longitudinal/Transverse SSA, and better understanding of higher-twist terms. </span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">5. A more complete impact study from NLO QCD global fit, to illustrate the power of precision neutron (3He) data</span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">6. The urgency to produce SIDIS asymmetry data on neutron, to pin down a possible non-zero dbar polarization, given the expected release of RHIC STAR and PHENIX's W asymmetry data. </span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="font-family: Calibri; ">Thank you very much for your supports, </span></div></div><div><br></div><div><br></div><div><div><div><div><div>Xiaodong</div><div><br></div><div>------------------------------------------------------------------------------</div><div> Xiaodong Jiang</div><div> P25 group, MS H846, Tel. 505 606 0437 </div><div> Los Alamos National Laboratory</div><div> Los Alamos, NM 87545</div><div>------------------------------------------------------------------------------</div></div></div><div><br></div><div><br></div></div></div></div></div></body></html>