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<b><span style="font-size:28.0pt;font-family:"Times New Roman",serif"><o:p> </o:p></span></b></p>
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<b><span style="font-size:28.0pt;font-family:"Times New Roman",serif">Virtual Physics Division Seminar<o:p> </o:p></span></b></p>
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<span class="value"><b><span style="font-size:28.0pt;font-family:"Times New Roman",serif">The MARATHON Marathon<o:p> </o:p></span></b></span></p>
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<span class="value"><b><span style="font-size:20.0pt;font-family:"Times New Roman",serif">Hanjie Liu, Christopher Cocuzza, Efrain Segarra<o:p> </o:p></span></b></span></p>
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<span class="value"><b><span style="font-size:14.0pt;font-family:"Times New Roman",serif">University of Massachusetts Amherst, Temple University, Massachusetts Institute of Technology<o:p> </o:p></span></b></span></p>
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<b>The recently released MARATHON results have generated considerable interest with two derivative papers already on the arXiv. This Friday we will have a MARATHON Marathon with Hanjie Li (Univ. of Mass. Amherst), Christopher Cocuzza (Temple), and Efrain Segarra
(MIT) presenting these new results. We will loosely follow an APS invited session format with each presenter having thirty minutes to present though we have allow considerably more time for questions and discussions.<o:p> </o:p></b></p>
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<b><span style="font-size:14.0pt;font-family:"Times New Roman",serif">Friday, April 30, 2021<o:p> </o:p></span></b></p>
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<b><span style="font-size:14.0pt;font-family:"Times New Roman",serif">12:00 pm – 2:30 pm<o:p> </o:p></span></b></p>
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<a href="https://bluejeans.com/245615984" title="https://bluejeans.com/245615984"><span style="font-size:14.0pt;font-family:"Times New Roman",serif">https://bluejeans.com/245615984</span></a><b><span style="font-size:14.0pt;font-family:"Times New Roman",serif"><o:p> </o:p></span></b></p>
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<b><span style="font-size:18.0pt;mso-fareast-font-family:"Times New Roman"">Abstracts:<o:p> </o:p></span></b></p>
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<b><span style="color:black">The Measurement of the Nucleon F2n/F2p Structure Function Ratio from the MARATHON Experiment</span></b><o:p> </o:p></p>
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<span style="color:black">Hanjie Liu (Univ. of Mass. Amherst)</span><o:p> </o:p></p>
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<i><span style="color:black">The ratio of neutron structure function to that of proton F2n/F2p is one of the best methods to extract d/u quark ratio. While the F2n/F2p extracted from deuteron deep inelastic scattering data has large systematic uncertainty
at high x (x>0.7) from model dependent nuclear corrections, the MARATHON experiment, which ran in spring 2018, uses a novel method. It performed deep inelastic electron scattering off tritium and helium-3 mirror nuclei to measure F2n/F2p over the range x=0.195
to x=0.825. Since tritium and helium-3 are mirror nuclei, theoretical uncertainties are expected to be largely canceled out in the ratio. The results of F2n/F2p from the MARATHON experiment was recently posted in arxiv. An overview of the MARATHON experiments
and the results will be presented.<o:p> </o:p></span></i></p>
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<b><span style="color:black">First Evidence of Isovector EMC effect from Global QCD Analysis with MARATHON Data</span></b><o:p> </o:p></p>
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<span style="color:black">Christopher Cocuzza (Temple)</span><o:p> </o:p></p>
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<i><span style="color:black">I will report the results of a Monte Carlo global QCD analysis of unpolarized parton distribution functions (PDFs), including for the first time constraints from ratios of 3He to 3H structure functions recently obtained by the MARATHON
experiment at Jefferson Lab. This simultaneous analysis of nucleon PDFs and nuclear effects in A=2 and A=3 nuclei reveals the first indication for an isovector nuclear EMC effect in light nuclei. Thus, while the MARATHON data yield relatively weak constraints
on the F2n/F2p neutron to proton structure function ratio and the d/u PDF ratio, the data suggest a strongly enhanced nuclear effect on the d-quark PDF in the bound proton.</span><o:p> </o:p></i></p>
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<b><span style="color:black">Nucleon Off-shell Structure and the Free Neutron Valence Structure from A=3 Inclusive Electron Scattering
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<span style="color:black">Efrain Segarra (MIT)</span><o:p> </o:p></p>
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<span style="color:black;background:white">While there are large amounts of proton structure measurements, data on the structure of the neutron is
<i>much more spars as experiments typically extract the structure of neutrons from measurements of light atomic nuclei using model-dependent corrections for nuclear effects.
</i></span><i><span style="color:black"> <span style="background:white">Here we evaluate the model dependence of this extraction by examining a wide range of models including the effect of using instant-form and light-cone nuclear wave functions and several
different parameterizations of nucleon modification effects, including those with and without isospin dependence. We find that, while the data cannot differentiate among the different models of nuclear structure and nucleon modification, they consistently
prefer a neutron-to-proton structure function ratio of at </span><span style="border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">xB→1</span><span style="background:white"> of </span></span></i><i><span style="font-family:"Cambria Math",serif;mso-bidi-font-family:"Cambria Math";color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">∼</span><span style="color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">0.4</span><span style="color:black;background:white"> with
a typical uncertainty (</span><span style="color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">1σ</span><span style="color:black;background:white">) of </span></i><i><span style="font-family:"Cambria Math",serif;mso-bidi-font-family:"Cambria Math";color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">∼</span><span style="color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">0.05</span><span style="color:black;background:white"> and </span></i><i><span style="font-family:"Cambria Math",serif;mso-bidi-font-family:"Cambria Math";color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">∼</span><span style="color:black;border:none windowtext 1.0pt;mso-border-alt:none windowtext 0in;padding:0in">0.10</span><span style="color:black;background:white"> for
isospin-independent and isospin-dependent modification models, respectively. While strongly favoring SU(6) symmetry breaking models based on perturbative QCD and the Schwinger-Dyson equation calculation, the MARATHON data do not completely rule out the scalar
di-quark models if an isospin-dependent modification exist.</span><o:p> </o:p></i></p>
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<b><span style="font-size:18.0pt;font-family:"Times New Roman",serif">Friday, April 30, 2021<o:p> </o:p></span></b></p>
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<b><span style="font-size:18.0pt;font-family:"Times New Roman",serif">12:00 pm – 2:30 pm<o:p> </o:p></span></b></p>
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<a href="https://bluejeans.com/245615984" title="https://bluejeans.com/245615984"><span style="font-size:20.0pt;font-family:"Times New Roman",serif">https://bluejeans.com/245615984</span></a><b><span style="font-size:20.0pt;font-family:"Times New Roman",serif"><o:p> </o:p></span></b></p>
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