Bulletin of the American Physical Society
2017 Fall Meeting of the APS Division of Nuclear Physics
Volume 62, Number 11
Wednesday–Saturday, October 25–28, 2017; Pittsburgh, Pennsylvania
Session CF: Meson Structure |
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Chair: William Briscoe, The George Washington University Room: Salon 6 |
Thursday, October 26, 2017 8:30AM - 8:42AM |
CF.00001: Pion and Kaon structure function measurements at Jefferson Lab 12 GeV and the Electron-Ion Collider Andres Vargas, Tanja Horn, Richard Trotta The lightest mesons, Pions and Kaons play a fundamental role in the understanding of hadronic mass. The 12 GeV JLab will address some questions, but to ultimately understand the role of sea quarks and gluons in pion and kaon masses the wide kinematic reach in the longitudinal momentum fraction as well as in the four-momentum transfer, as enabled by the Electron-Ion Collider (EIC) is needed. In this talk, we present the current status of and projections for measurements of pion and kaon structure functions in the Jefferson Laboratory 12 GeV era and at the EIC. [Preview Abstract] |
Thursday, October 26, 2017 8:42AM - 8:54AM |
CF.00002: ABSTRACT WITHDRAWN |
Thursday, October 26, 2017 8:54AM - 9:06AM |
CF.00003: Hadron Mass Effects for Kaon Production on deuteron Juan Guerrero The spin-independent cross section for semi-inclusive lepton-nucleon scattering are derived in the framework of collinear factorization, including the effects of the target and produced hadron masses at small momentum transfer squared $Q^2$. At leading order, the cross section factorizes into products of parton distributions and fragmentation functions evaluated in terms of new, mass-dependent scaling variables. This talk focuses on Kaon production at HERMES and COMPASS kinematics. In particular, hadron mass corrections for integrated kaon multiplicities measured by the two collaborations are shown to sizeably reduce the apparent large discrepancy between the results for both experiments. [Preview Abstract] |
Thursday, October 26, 2017 9:06AM - 9:18AM |
CF.00004: Studies of L-T Separated Kaon Electroproduction Richard Trotta, Tanja Horn, Andres Vargas QCD is characterized by two emergent phenomena: confinement and dynamical chiral symmetry breaking (DCSB). Pion and kaon form factors are of particular interest as they are connected to the Goldstone modes of DCSB. The flavor degrees of freedom of the produced meson selectively probe aspects of the reaction mechanism and the transition from hadronic to partonic degrees of freedom. There has been significant progress in the theoretical description of the nucleon structure in terms of QCD degrees of freedom, in particular through Generalized Parton Distributions (GPDs).The last decade saw a dramatic improvement in precision of charged pion form factor data and new results have become available on the pion transition form factor. The kaon provides an interesting way to expand these studies, opening the possibility to access the production mechanism involving strangeness. Kaon data at larger virtual photon mass allow one to search for the onset of the partonic picture. In this regime, hard and soft physics have been shown to factorize and GPDs provide the most complete description of the non-perturbative physics. The lack of necessary experimental facilities has left a gap in L-T separated data for exclusive K$+$ production from the proton above the resonance region.The newly upgraded 12 GeV beam energy at Jlab, in addition to the recently built SHMS spectrometer for Hall C, has provided an opportunity to expand the kaon data. Recent kaon form factor and cross section results will be discussed showing the impact of E12-09-011, the running Jlab 12 GeV kaon experiment. [Preview Abstract] |
Thursday, October 26, 2017 9:18AM - 9:30AM |
CF.00005: Kaon transverse charge density from space- and time-like data Nicholas A Mecholsky, Johann Meija-Ott, Marco Carmignotto, Tanja Horn, Gerald A Miller, Ian L. Pegg, Lorenzo Resca Measurements of electromagnetic form factors play an important role in our understanding of the structure and interactions of hadrons based on the principles of QCD. Transverse charge densities provide a framework for the interpretation of these form factors in terms of the physical charge and magnetization densities. They are obtained as two-dimensional Fourier transforms of the elastic form factors and describe the distribution of charge and magnetization in the plane transverse to the propagation direction of a fast moving nucleon. They are related to the Generalized Parton Distributions (GPDs), which are expected to provide a universal (process-independent) description of the nucleon. The simplest hadronic system that also includes a heavier strange quark is the kaon, whose valence structure is a bound state of a quark and an antiquark. Its elastic electromagnetic structure is parameterized by a single form factor. Recent calculations suggest that strange quarks play a large role in, e.g., the shape of the parton distribution amplitude, making studies of the kaon's internal structure of the kaon even more important. I will present the first extraction of the kaon transverse charge density from timelike and spacelike data including new data at high center of mass energies. [Preview Abstract] |
Thursday, October 26, 2017 9:30AM - 9:42AM |
CF.00006: Exploring the Hadron Structure through Meson Electroproduction Salina Ali, Marco Carmignotto, Tanja Horn Meson form factors play an important role in our understanding of the lightest mesons on the basis of Quantum Chromodynamics (QCD). They provide a scale independent measurement of the transition from non-perturbative to perturbative degrees of freedom. The pion form factor is well known up to Q$^{\mathrm{2}}=$ 0.3 GeV$^{\mathrm{2}}$ through elastic scattering. However, to get to larger Q$^{\mathrm{2}}$ values, one needs to use the pion electroproduction method. The E12-09-011 experiment at 12 GeV Jefferson Lab aims to test the expected approach of the hard scattering regime through precision measurements and the relative contributions and kinematic dependencies of the longitudinal and transverse cross sections. Although E12-09-011 is a designated kaon experiment, the setup will also allow for detecting pions in parallel. Extracting the pion form factor from E12-09-011 would allow for consistency checks of the electroproduction method at low Q$^{\mathrm{2\thinspace }}$and experimental checks of the reaction mechanism. This can also allow one to obtain a real pion rate from kinematics that currently rely on models for estimating uncertainties. In my talk, I will present the current status and discuss the outlook on future studies of light quarks with pion production, particle identification requirements, systematic uncertainties and potential pion form factor extractions at 12 GeV Jefferson Lab. [Preview Abstract] |
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