Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium

G.M. Huber; H.P. Blok; C. Butuceanu; D. Gaskell; T. Horn; D.J. Mack; D. Abbott; K. Aniol; H. Anklin; C. Armstrong; J. Arrington; K. Assamagan; S. Avery; O.K. Baker; B. Barrett; E.J. Beise; C. Bochna; W. Boeglin; E.J. Brash; H. Breuer; C.C. Chang; N. Chant; M.E. Christy; J. Dunne; T. Eden; R. Ent; H. Fenker; E.F. Gibson; R. Gilman; K. Gustafsson; W. IIinton; R.J. IIolt; I.I. Jackson; S. Jin; M.K. Jones; C.E. Keppel; P.H. Kim; W. Kim; P.M. King; A. Klein; D. Koltenuk; V. Kovaltchouk; M. Liang; J. Liu; G.J. Lolos; A. Lung; D.J. Margaziotis; P. Markowitz; A. Matsumura; D. Mckee; D. Meekins; J. Mitchell; T. Miyoshi; H. Mkrtchyan; B. Mueller; G. Niculescu; I. Niculescu; Y. Okayasu; L. Pentchev; C. Perdrisat; D. Pitz; D. Potterveld; V. Punjabi; L.M. Qin; P.E. Reimer; J. Reinhold; J. Roche; P.G. Roos; A. Sarty; I.K. Shin; G.R. Smith; S. Stepanyan; L.G. Tang; V. Tadevosyan; V. Tvaskis; R.L.J. Van der Meer; K. Vansyoc; D. Van Westrum; S. Vidakovic; J. Volmer; W. Vulcan; G. Warren; S.A. Wood; C. Xu; C. Yan; W.-. Zhao; X. Zheng; B. Zihlmann

doi:10.1103/PhysRevC.91.015202

Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium

G.M. Huber, H.P. Blok, C. Butuceanu, D. Gaskell, T. Horn, D.J. Mack, D. Abbott, K. Aniol, H. Anklin, C. Armstrong, J. Arrington, K. Assamagan, S. Avery, O.K. Baker, B. Barrett, E.J. Beise, C. Bochna, W. Boeglin, E.J. Brash, H. BreuerC.C. Chang, N. Chant, M.E. Christy, J. Dunne, T. Eden, R. Ent, H. Fenker, E.F. Gibson, R. Gilman, K. Gustafsson, W. IIinton, R.J. IIolt, I.I. Jackson, S. Jin, M.K. Jones, C.E. Keppel, P.H. Kim, W. Kim, P.M. King, A. Klein, D. Koltenuk, V. Kovaltchouk, M. Liang, J. Liu, G.J. Lolos, A. Lung, D.J. Margaziotis, P. Markowitz, A. Matsumura, D. Mckee, D. Meekins, J. Mitchell, T. Miyoshi, H. Mkrtchyan, B. Mueller, G. Niculescu, I. Niculescu, Y. Okayasu, L. Pentchev, C. Perdrisat, D. Pitz, D. Potterveld, V. Punjabi, L.M. Qin, P.E. Reimer, J. Reinhold, J. Roche, P.G. Roos, A. Sarty, I.K. Shin, G.R. Smith, S. Stepanyan, L.G. Tang, V. Tadevosyan, V. Tvaskis, R.L.J. Van der Meer, K. Vansyoc, D. Van Westrum, S. Vidakovic, J. Volmer, W. Vulcan, G. Warren, S.A. Wood, C. Xu, C. Yan, W.-. Zhao, X. Zheng, B. Zihlmann

Student Lab and Education

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, Q2, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in π- and π+ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Purpose: We perform the first complete separation of the four unpolarized electromagnetic structure functions L/T/LT/TT in forward, exclusive π± electroproduction on deuterium above the dominant resonances. Method: Data were acquired with 2.6-5.2-GeV electron beams and the HMS+SOS spectrometers in Jefferson Lab Hall C at central Q2 values of 0.6, 1.0, and 1.6 GeV2 at W=1.95 GeV, and Q2=2.45 GeV2 at W=2.22 GeV. There was significant coverage in φ and ε, which allowed separation of σL,T,LT,TT. Results: σL shows a clear signature of the pion pole, with a sharp rise at small -t. In contrast, σT is much flatter versus t. The longitudinal/transverse ratios evolve with Q2 and t and at the highest Q2=2.45 GeV2 show a slight enhancement for π- production compared to π+. The π-/π+ ratio for transverse photons exhibits only a small Q2 dependence, following a nearly universal curve with t, with a steep transition to a value of about 0.25, consistent with s-channel quark knockout. The σTT/σT ratio also drops rapidly with Q2, qualitatively consistent with s-channel helicity conservation. The π-/π+ ratio for longitudinal photons indicates a small isoscalar contamination at W=1.95 GeV, consistent with what was observed in our earlier determination of the pion form factor at these kinematics. Conclusions: The separated cross sections are compared to a variety of theoretical models, which generally describe σL but have varying success with σT. Further theoretical input is required to provide a more profound insight into the relevant reaction mechanisms for longitudinal and transverse photons, such as whether the observed transverse ratio is indeed attributable to a transition from pion to quark knockout mechanisms and provide useful information regarding the twist-3 transversity generalized parton distribution, HT.

Original language	English
Pages (from-to)	015202-015202
Journal	Physical Review C
Volume	91
Issue number	1
DOIs	https://doi.org/10.1103/PhysRevC.91.015202
Publication status	Published - 2015

Bibliographical note

PT: J; NR: 42; TC: 0; J9: PHYS REV C; PG: 23; GA: AZ9YA; UT: WOS:000348569100003

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1103/PhysRevC.91.015202

Persistent URL (handle)

Persistent link

Cite this

Huber, G. M., Blok, H. P., Butuceanu, C., Gaskell, D., Horn, T., Mack, D. J., Abbott, D., Aniol, K., Anklin, H., Armstrong, C., Arrington, J., Assamagan, K., Avery, S., Baker, O. K., Barrett, B., Beise, E. J., Bochna, C., Boeglin, W., Brash, E. J., ... Zihlmann, B. (2015). Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium. Physical Review C, 91(1), 015202-015202. https://doi.org/10.1103/PhysRevC.91.015202

@article{955be6d064a145aabff14f9abd0c8e75,

title = "Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium",

abstract = "Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, Q2, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in π- and π+ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Purpose: We perform the first complete separation of the four unpolarized electromagnetic structure functions L/T/LT/TT in forward, exclusive π± electroproduction on deuterium above the dominant resonances. Method: Data were acquired with 2.6-5.2-GeV electron beams and the HMS+SOS spectrometers in Jefferson Lab Hall C at central Q2 values of 0.6, 1.0, and 1.6 GeV2 at W=1.95 GeV, and Q2=2.45 GeV2 at W=2.22 GeV. There was significant coverage in φ and ε, which allowed separation of σL,T,LT,TT. Results: σL shows a clear signature of the pion pole, with a sharp rise at small -t. In contrast, σT is much flatter versus t. The longitudinal/transverse ratios evolve with Q2 and t and at the highest Q2=2.45 GeV2 show a slight enhancement for π- production compared to π+. The π-/π+ ratio for transverse photons exhibits only a small Q2 dependence, following a nearly universal curve with t, with a steep transition to a value of about 0.25, consistent with s-channel quark knockout. The σTT/σT ratio also drops rapidly with Q2, qualitatively consistent with s-channel helicity conservation. The π-/π+ ratio for longitudinal photons indicates a small isoscalar contamination at W=1.95 GeV, consistent with what was observed in our earlier determination of the pion form factor at these kinematics. Conclusions: The separated cross sections are compared to a variety of theoretical models, which generally describe σL but have varying success with σT. Further theoretical input is required to provide a more profound insight into the relevant reaction mechanisms for longitudinal and transverse photons, such as whether the observed transverse ratio is indeed attributable to a transition from pion to quark knockout mechanisms and provide useful information regarding the twist-3 transversity generalized parton distribution, HT.",

author = "G.M. Huber and H.P. Blok and C. Butuceanu and D. Gaskell and T. Horn and D.J. Mack and D. Abbott and K. Aniol and H. Anklin and C. Armstrong and J. Arrington and K. Assamagan and S. Avery and O.K. Baker and B. Barrett and E.J. Beise and C. Bochna and W. Boeglin and E.J. Brash and H. Breuer and C.C. Chang and N. Chant and M.E. Christy and J. Dunne and T. Eden and R. Ent and H. Fenker and E.F. Gibson and R. Gilman and K. Gustafsson and W. IIinton and R.J. IIolt and I.I. Jackson and S. Jin and M.K. Jones and C.E. Keppel and P.H. Kim and W. Kim and P.M. King and A. Klein and D. Koltenuk and V. Kovaltchouk and M. Liang and J. Liu and G.J. Lolos and A. Lung and D.J. Margaziotis and P. Markowitz and A. Matsumura and D. Mckee and D. Meekins and J. Mitchell and T. Miyoshi and H. Mkrtchyan and B. Mueller and G. Niculescu and I. Niculescu and Y. Okayasu and L. Pentchev and C. Perdrisat and D. Pitz and D. Potterveld and V. Punjabi and L.M. Qin and P.E. Reimer and J. Reinhold and J. Roche and P.G. Roos and A. Sarty and I.K. Shin and G.R. Smith and S. Stepanyan and L.G. Tang and V. Tadevosyan and V. Tvaskis and {Van der Meer}, R.L.J. and K. Vansyoc and {Van Westrum}, D. and S. Vidakovic and J. Volmer and W. Vulcan and G. Warren and S.A. Wood and C. Xu and C. Yan and W.-. Zhao and X. Zheng and B. Zihlmann",

note = "PT: J; NR: 42; TC: 0; J9: PHYS REV C; PG: 23; GA: AZ9YA; UT: WOS:000348569100003",

year = "2015",

doi = "10.1103/PhysRevC.91.015202",

language = "English",

volume = "91",

pages = "015202--015202",

journal = "Physical Review C",

issn = "0556-2813",

publisher = "American Physical Society",

number = "1",

}

Huber, GM, Blok, HP, Butuceanu, C, Gaskell, D, Horn, T, Mack, DJ, Abbott, D, Aniol, K, Anklin, H, Armstrong, C, Arrington, J, Assamagan, K, Avery, S, Baker, OK, Barrett, B, Beise, EJ, Bochna, C, Boeglin, W, Brash, EJ, Breuer, H, Chang, CC, Chant, N, Christy, ME, Dunne, J, Eden, T, Ent, R, Fenker, H, Gibson, EF, Gilman, R, Gustafsson, K, IIinton, W, IIolt, RJ, Jackson, II, Jin, S, Jones, MK, Keppel, CE, Kim, PH, Kim, W, King, PM, Klein, A, Koltenuk, D, Kovaltchouk, V, Liang, M, Liu, J, Lolos, GJ, Lung, A, Margaziotis, DJ, Markowitz, P, Matsumura, A, Mckee, D, Meekins, D, Mitchell, J, Miyoshi, T, Mkrtchyan, H, Mueller, B, Niculescu, G, Niculescu, I, Okayasu, Y, Pentchev, L, Perdrisat, C, Pitz, D, Potterveld, D, Punjabi, V, Qin, LM, Reimer, PE, Reinhold, J, Roche, J, Roos, PG, Sarty, A, Shin, IK, Smith, GR, Stepanyan, S, Tang, LG, Tadevosyan, V, Tvaskis, V, Van der Meer, RLJ, Vansyoc, K, Van Westrum, D, Vidakovic, S, Volmer, J, Vulcan, W, Warren, G, Wood, SA, Xu, C, Yan, C, Zhao, W, Zheng, X & Zihlmann, B 2015, 'Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium', Physical Review C, vol. 91, no. 1, pp. 015202-015202. https://doi.org/10.1103/PhysRevC.91.015202

TY - JOUR

T1 - Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium

AU - Huber, G.M.

AU - Blok, H.P.

AU - Butuceanu, C.

AU - Gaskell, D.

AU - Horn, T.

AU - Mack, D.J.

AU - Abbott, D.

AU - Aniol, K.

AU - Anklin, H.

AU - Armstrong, C.

AU - Arrington, J.

AU - Assamagan, K.

AU - Avery, S.

AU - Baker, O.K.

AU - Barrett, B.

AU - Beise, E.J.

AU - Bochna, C.

AU - Boeglin, W.

AU - Brash, E.J.

AU - Breuer, H.

AU - Chang, C.C.

AU - Chant, N.

AU - Christy, M.E.

AU - Dunne, J.

AU - Eden, T.

AU - Ent, R.

AU - Fenker, H.

AU - Gibson, E.F.

AU - Gilman, R.

AU - Gustafsson, K.

AU - IIinton, W.

AU - IIolt, R.J.

AU - Jackson, I.I.

AU - Jin, S.

AU - Jones, M.K.

AU - Keppel, C.E.

AU - Kim, P.H.

AU - Kim, W.

AU - King, P.M.

AU - Klein, A.

AU - Koltenuk, D.

AU - Kovaltchouk, V.

AU - Liang, M.

AU - Liu, J.

AU - Lolos, G.J.

AU - Lung, A.

AU - Margaziotis, D.J.

AU - Markowitz, P.

AU - Matsumura, A.

AU - Mckee, D.

AU - Meekins, D.

AU - Mitchell, J.

AU - Miyoshi, T.

AU - Mkrtchyan, H.

AU - Mueller, B.

AU - Niculescu, G.

AU - Niculescu, I.

AU - Okayasu, Y.

AU - Pentchev, L.

AU - Perdrisat, C.

AU - Pitz, D.

AU - Potterveld, D.

AU - Punjabi, V.

AU - Qin, L.M.

AU - Reimer, P.E.

AU - Reinhold, J.

AU - Roche, J.

AU - Roos, P.G.

AU - Sarty, A.

AU - Shin, I.K.

AU - Smith, G.R.

AU - Stepanyan, S.

AU - Tang, L.G.

AU - Tadevosyan, V.

AU - Tvaskis, V.

AU - Van der Meer, R.L.J.

AU - Vansyoc, K.

AU - Van Westrum, D.

AU - Vidakovic, S.

AU - Volmer, J.

AU - Vulcan, W.

AU - Warren, G.

AU - Wood, S.A.

AU - Xu, C.

AU - Yan, C.

AU - Zhao, W.-.

AU - Zheng, X.

AU - Zihlmann, B.

N1 - PT: J; NR: 42; TC: 0; J9: PHYS REV C; PG: 23; GA: AZ9YA; UT: WOS:000348569100003

PY - 2015

Y1 - 2015

N2 - Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, Q2, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in π- and π+ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Purpose: We perform the first complete separation of the four unpolarized electromagnetic structure functions L/T/LT/TT in forward, exclusive π± electroproduction on deuterium above the dominant resonances. Method: Data were acquired with 2.6-5.2-GeV electron beams and the HMS+SOS spectrometers in Jefferson Lab Hall C at central Q2 values of 0.6, 1.0, and 1.6 GeV2 at W=1.95 GeV, and Q2=2.45 GeV2 at W=2.22 GeV. There was significant coverage in φ and ε, which allowed separation of σL,T,LT,TT. Results: σL shows a clear signature of the pion pole, with a sharp rise at small -t. In contrast, σT is much flatter versus t. The longitudinal/transverse ratios evolve with Q2 and t and at the highest Q2=2.45 GeV2 show a slight enhancement for π- production compared to π+. The π-/π+ ratio for transverse photons exhibits only a small Q2 dependence, following a nearly universal curve with t, with a steep transition to a value of about 0.25, consistent with s-channel quark knockout. The σTT/σT ratio also drops rapidly with Q2, qualitatively consistent with s-channel helicity conservation. The π-/π+ ratio for longitudinal photons indicates a small isoscalar contamination at W=1.95 GeV, consistent with what was observed in our earlier determination of the pion form factor at these kinematics. Conclusions: The separated cross sections are compared to a variety of theoretical models, which generally describe σL but have varying success with σT. Further theoretical input is required to provide a more profound insight into the relevant reaction mechanisms for longitudinal and transverse photons, such as whether the observed transverse ratio is indeed attributable to a transition from pion to quark knockout mechanisms and provide useful information regarding the twist-3 transversity generalized parton distribution, HT.

AB - Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, Q2, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in π- and π+ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Purpose: We perform the first complete separation of the four unpolarized electromagnetic structure functions L/T/LT/TT in forward, exclusive π± electroproduction on deuterium above the dominant resonances. Method: Data were acquired with 2.6-5.2-GeV electron beams and the HMS+SOS spectrometers in Jefferson Lab Hall C at central Q2 values of 0.6, 1.0, and 1.6 GeV2 at W=1.95 GeV, and Q2=2.45 GeV2 at W=2.22 GeV. There was significant coverage in φ and ε, which allowed separation of σL,T,LT,TT. Results: σL shows a clear signature of the pion pole, with a sharp rise at small -t. In contrast, σT is much flatter versus t. The longitudinal/transverse ratios evolve with Q2 and t and at the highest Q2=2.45 GeV2 show a slight enhancement for π- production compared to π+. The π-/π+ ratio for transverse photons exhibits only a small Q2 dependence, following a nearly universal curve with t, with a steep transition to a value of about 0.25, consistent with s-channel quark knockout. The σTT/σT ratio also drops rapidly with Q2, qualitatively consistent with s-channel helicity conservation. The π-/π+ ratio for longitudinal photons indicates a small isoscalar contamination at W=1.95 GeV, consistent with what was observed in our earlier determination of the pion form factor at these kinematics. Conclusions: The separated cross sections are compared to a variety of theoretical models, which generally describe σL but have varying success with σT. Further theoretical input is required to provide a more profound insight into the relevant reaction mechanisms for longitudinal and transverse photons, such as whether the observed transverse ratio is indeed attributable to a transition from pion to quark knockout mechanisms and provide useful information regarding the twist-3 transversity generalized parton distribution, HT.

U2 - 10.1103/PhysRevC.91.015202

DO - 10.1103/PhysRevC.91.015202

M3 - Article

SN - 0556-2813

VL - 91

SP - 15202

EP - 15202

JO - Physical Review C

JF - Physical Review C

IS - 1

ER -

Separated response functions in exclusive, forward pi(+/-) electroproduction on deuterium

Abstract

Bibliographical note

UN SDGs

Access to Document

Persistent URL (handle)

Fingerprint

Cite this