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Title: Meson Form Factors and Deep Exclusive Meson Production Experiments

Abstract

Pion and kaon electroproduction data play a unique role in Nature and our understanding of them is essential for explaining hadron structure. Precision longitudinaltransverse separated pion and kaon cross sections are of particular interest. They allow for the extraction of meson form factors and validation of understanding of hard exclusive and semi-inclusive reactions (π+, K+, π0, γ) towards 3D hadron imaging and potential future flavor decomposition. We review recent data and present prospects for deep exclusive pion and kaon electroproduction at the 12 GeV Jefferson Lab including the prospects to use projected charged- and neutral pion data to further determine the spin, charge-parity and flavor of GPDs, including the helicity-flip GPDs.

Authors:
 [1]
  1. The Catholic Univ. of America, Washington, DC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1362028
Report Number(s):
JLAB-PHY-16-2373; DOE/OR/23177-4153
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Journal Name: EPJ Web Conf.; Journal Volume: 137; Conference: Confinement XII, 28 Aug - 04 Sep 2016. Thessaloniki, Greece
Country of Publication:
United States
Language:
English

Citation Formats

Horn, Tanja. Meson Form Factors and Deep Exclusive Meson Production Experiments. United States: N. p., 2017. Web. doi:10.1051/epjconf/201713705005.
Horn, Tanja. Meson Form Factors and Deep Exclusive Meson Production Experiments. United States. doi:10.1051/epjconf/201713705005.
Horn, Tanja. Mon . "Meson Form Factors and Deep Exclusive Meson Production Experiments". United States. doi:10.1051/epjconf/201713705005. https://www.osti.gov/servlets/purl/1362028.
@article{osti_1362028,
title = {Meson Form Factors and Deep Exclusive Meson Production Experiments},
author = {Horn, Tanja},
abstractNote = {Pion and kaon electroproduction data play a unique role in Nature and our understanding of them is essential for explaining hadron structure. Precision longitudinaltransverse separated pion and kaon cross sections are of particular interest. They allow for the extraction of meson form factors and validation of understanding of hard exclusive and semi-inclusive reactions (π+, K+, π0, γ) towards 3D hadron imaging and potential future flavor decomposition. We review recent data and present prospects for deep exclusive pion and kaon electroproduction at the 12 GeV Jefferson Lab including the prospects to use projected charged- and neutral pion data to further determine the spin, charge-parity and flavor of GPDs, including the helicity-flip GPDs.},
doi = {10.1051/epjconf/201713705005},
journal = {EPJ Web Conf.},
number = ,
volume = 137,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Conference:
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  • We present several recent results from the BaBar collaboration in the areas of initial state radiation physics and transition form factors. An updated study of the processes e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}{sup -} and e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0} provides an improved understanding of the Y (2175) meson. A very precise study of the process e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -} improves the precision on the calculated anomalous magnetic moment of the muon and provides by far the best information on excited {rho} states. Our previous measurements of the timelike transition formmore » factors (TFF) of the {eta} and {eta}' mesons at Q{sup 2} = 112 GeV{sup 2}, combined with new measurements of the their spacelike TFFs and those of the {pi}{sup 0} and {eta}{sub c} mesons, provide powerful tests of QCD and models of the distribution amplitudes of quarks inside these mesons. The {eta}{sub c} TFF shows the expected behavior over the Q{sup 2} range 1-50 GeV{sup 2}, and we are sensitive to next-to-leading-order QCD corrections. The {eta} and {eta}' TFFs are consistent with expected behavior, but those for the {pi}{sup 0} are not. Extracting the strange and nonstrange components of the {eta} and {eta}' TFFs, we find the nonstrange component to be consistent with theoretical expectations and inconsistent with the measured {pi}{sup 0} TFF.« less
  • No abstract prepared.
  • We use rigorous QCD dispersion relations to derive model-independent bounds on the {ital {bar B}}{r_arrow}{pi}{ital l}{bar {nu}}, {ital D}{r_arrow}{pi}{ital {bar l}}{nu}, and {ital D}{r_arrow}{ital {bar K}{bar l}}{nu} form factors. These bounds are particularly restrictive when the value of the observable form factor at one or more kinematic points is assumed. With reasonable assumptions we find {ital f}{sub {ital B}}{le}195 MeV and that the shape of the form factor becomes severely constrained. These constraints are useful both for model discrimination and for model-insensitive extraction of Cabibbo-Kobayashi-Maskawa mixing parameters.
  • We show that existing data on the semileptonic decays {ital D}{r arrow}{ital Ke}{sup +}{nu}{sub {ital e}} and {ital D}{r arrow}{ital K}{sup *}{ital e}{sup +}{nu}{sub {ital e}} provide information on matrix elements relevant for the rare {ital {bar B}}-meson decays {ital {bar B}}{r arrow}{ital Ke}{sup +}{ital e}{sup {minus}}, {ital {bar B}}{r arrow}{ital K}{sup *}{ital e}{sup +}{ital e}{sup {minus}}, and {ital {bar B}}{r arrow}{ital K}{sup *}{gamma} and that future data on {ital {bar B}}{r arrow}{rho}{ital e}{bar {nu}}{sub {ital e}} and {ital {bar B}}{r arrow}{pi}{ital e}{bar {nu}}{sub {ital e}} will further constrain them. A discussion of how the form factors for these lattermore » decays are in turn determined by semileptonic {ital D} decays at the corresponding recoil momenta is also presented.« less
  • Measurements of exclusive meson production are a useful tool in the study of hadronic structure. In particular, one can discern the relevant degrees of freedom at different distance scales through these studies. In the transition region between low momentum transfer (where a description of hadronic degrees of freedom in terms of effective hadronic Lagrangians is valid) and high momentum transfer (where the degrees of freedom are quarks and gluons), the predictive power of Quantum Chromodynamics (QCD), the theory of the strong interaction, is limited due to the absence of a complete solution. Thus, one has to rely upon experimental datamore » from the non-perturbative intermediate-energy regime to thoroughly understand the onset of perturbative QCD (pQCD) as the momentum transfer is increased. This work involves two deep exclusive meson electroproduction experiments at Jefferson Lab (JLab). The p(e,e'pi+)n reaction is studied at fixed Q^2 and W of 2.5 GeV2 and 2.0 GeV, respectively, while varying the four momentum transfer to the nucleon -t from 0.2 to 2.1 GeV2 . As -t is increased, the hadronic interaction scale is reduced independently of the observation scale of the virtual photon, providing valuable information about the hard- scattering process in general. The data was taken at JLab Hall C in 2003, as a part of the experiment E01-004, Fpi-2, using the High Momentum Spectrometer (HMS) and Short Orbit Spectrometer (SOS), and in this work, the results of the differential cross section analysis are presented and compared to prior data, as well as two theoretical models. Using these results over a wide -t range, the transition from hard to soft QCD is also studied. In addition, the p(e,e'K+)Lambda(Sigma0) reactions are also studied. Despite their importance in elucidating the reaction mechanism underlying strangeness production, we still do not have complete understanding of these reactions above the resonance region. The experiment, E12- 09-011, intends to perform, for the first time, a full Rosenbluth (L/T/LT/TT) separation of p(e,e'K+)Lambda(Sigma0) cross sections above the resonance region using the newly upgraded standard equipment, Super High Momentum Spectrometer (SHMS) at JLab Hall C. The separated data will allow us to better understand the Kaon production reaction mechanism and the hard-soft QCD transition in exclusive processes. The kinematic settings being studied in the experiment ranges from Q^2 of 0.4 to 5.5 GeV2, W of 2.3 to 3.1 GeV, and -t of 0.06 to 0.53 GeV2. Here, the results from some pre-experimental studies with regards to estimations of singles rates as well as real and accidental coincidence rates are presented, using two different models. The implications of these projections on the runplan for the experiment are also discussed.« less