Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session EF: Mini-symposium on Studying Quantum Chromodynamics at an Electron-Ion Collider II |
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Chair: Phiala Shanahan, MIT Room: Hilton King's 2 |
Thursday, October 25, 2018 7:00PM - 7:15PM |
EF.00001: Large Transverse Momentum in Semi-Inclusive Deeply Inelastic Scattering Nobuo Sato We examine existing large transverse momentum fixed order perturbative QCD calculations at leading and next-to-leading order in light of current experimental measurements. Large discrepancies are found between the data and certain measurements, even in regions of kinematics where fixed order calculations are expected to be accurate. Possible interpretations are suggested. |
Thursday, October 25, 2018 7:15PM - 7:30PM |
EF.00002: Hadron multiplicities in SIDID for an iso-scalar target measured in COMPASS Takahiro Iwata Multiplicities of hadrons in Semi-Inclusive DIS are related to the parton distribution functions of nucleon and fragmentation functions of hadrorons. The COMPASS data on the pion multiplicity sum show effectively independence of x as expected. COMPASS collected as many as 620 data of Kaon multiplicity according to x and z. The COMPASS data at high z (0.8<z<0.95) show unexpectedly low Kaon multiplicity ratios(K-/K+). |
Thursday, October 25, 2018 7:30PM - 7:45PM |
EF.00003: Collinear factorization with non-zero quark virtuality in a spectator model Juan V Guerrero
In perturbative QCD, the masses of the hadrons involved in high energy reactions can usually be neglected. However, in the case of production of Kaons in electron-proton collisions at low (and not so low) beam energies this may not be a good approximation. In particular, a recent proposal to include hadron masses in theoretical calculations shows how these Hadron Mass Corrections can explain a large discrepancy observed in measurements performed at the HERMES and COMPASS experiments. In this talk, I will present some preliminary spectator model calculations designed to test the range of validity of the approximations needed in the proposed factorization scheme. |
Thursday, October 25, 2018 7:45PM - 8:00PM |
EF.00004: Unambiguous Observation of Initial-State Energy Loss in Cold Nuclear Matter at E906 SeaQuest Alexander Wickes Partonic energy loss is an essential probe of the nuclear medium properties in fixed target and heavy ion collisions, yet remains imprecisely determined up to now. The E906 SeaQuest spectrometer at Fermilab measures charmonium and Drell-Yan dimuon production in p+A collisions with fixed targets H, D, C, Fe, and W, at $\sqrt{s_{NN}} = 15$ GeV ($E_{\text{beam}} = 120$ GeV). The experiment provides an ideal phase space with minimal shadowing for measuring unambiguous signals of initial-state energy loss in cold nuclear matter. We observe a clear suppression in the nuclear modification in good agreement with theoretical predictions. These measurements will put new constraints on the partonic stopping power, radiation length, and transport coefficient. |
Thursday, October 25, 2018 8:00PM - 8:15PM |
EF.00005: Highlight of Fragmentation Studies in CLAS Lamiaa El Fassi, Sereres Clair Johnston, Md Latiful Kabir Over the last few decades several studies have probed color propagation and hadron production from hard interactions in nuclei, related to one of the basic phenomenon of quantum chromodynamics (QCD). The process referred to as hadronization or fragmentation, in which the energetic struck quark transforms to color-neutral hadrons, is an effective way to probe the confinement dynamics and test its characteristic time-scales. This talk will highlight ongoing efforts to study, for the first time, the semi-inclusive deep inelastic production of Λ0 hyperon in the current and target fragmentation regions using the 6 GeV CLAS EG2 data. The analysis results of this baryon channel combined with other meson production in the same data sets will improve our understanding of the space-time evolution of hadrons at intermediate energy, and would manifest a good boost for the upcoming extension of this hadronization program with the upgraded Jefferson Lab 12 GeV beam-energy and CLAS12. |
Thursday, October 25, 2018 8:15PM - 8:30PM |
EF.00006: Study of Forward and Backward Fragmentation Processes in Λ0 Leptoproduction Sereres Clair Johnston, Lamiaa El Fassi Fracture functions are akin to fragmentation functions but describe hadron production in the target remnant rather than current fragmentation region, factorizing and evolving in a predictable way. Like structure functions, fracture functions extracted from an experiment in one kinematic regime can be used to compute reactions at different scales. Recent theoretical predictions have acknowledged the leptoproduction of Λ0 hyperon as the best probe to study the fracture functions in semi-inclusive deep-inelastic scattering. Λ0 production off deuterium in datasets which can be finely binned in variables such as Q2, xB and ν provide valuable experimental input for the first extraction of fracture functions using electron triggered processes. This talk will describe the ongoing Λ0 analysis from 6 GeV CLAS EG2 data-sets with a discussion of both forward and backward fragmentation processes. |
Thursday, October 25, 2018 8:30PM - 8:45PM |
EF.00007: Probing the shape of jets, the strong coupling, and QCD using angularities Guido Bell, Christopher Lee, Jim Talbert We predict the angularity spectra of hadrons produced in e+e- collisions to NNLL' accuracy in resummed perturbation theory with 2-loop fixed-order matching. Angularities are event shapes dependent on a continuously adjustable parameter a < 2, changing the sensitivity to radiation close to or far away from the thrust axis. They probe the dependence of hadronic jet structure on the running strong coupling alpha_s, and on nonperturbative corrections due to hadronization. The leading nonperturbative shift to the first moment of angularities is universal, dependent on a single universal parameter times 1/Q and 1/(1-a). We use soft-collinear effective theory (SCET) and Event2 to predict resummed spectra matched to fixed-order QCD, along with renormalon subtractions removing ambiguities in the perturbative and nonperturbative parts and improving perturbative convergence. We compare our final predictions to analysis from LEP and find excellent agreement. This is a strong test not only of perturbative QCD but also the prediction of nonperturbative universality in angularities. |
Thursday, October 25, 2018 8:45PM - 9:00PM |
EF.00008: Parton pseudo-distributions and their evolution Anatoly V Radyushkin We study evolution of parton pseudo-distributions using the data of exploratory lattice calculations |
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