Ratios of helicity amplitudes for exclusive ρ0 electroproduction on transversely polarized protons: The HERMES Collaboration

A. Airapetian; N. Akopov; Z. Akopov; E. C. Aschenauer; W. Augustyniak; S. Belostotski; H. P. Blok; A. Borissov; V. Bryzgalov; G. P. Capitani; G. Ciullo; M. Contalbrigo; W. Deconinck; R. De Leo; E. De Sanctis; M. Düren; G. Elbakian; F. Ellinghaus; L. Felawka; S. Frullani; F. Garibaldi; G. Gavrilov; V. Gharibyan; S. V. Goloskokov; Y. Holler; A. Ivanilov; H. E. Jackson; S. Joosten; R. Kaiser; G. Karyan; A. Kisselev; V. Korotkov; V. Kozlov; P. Kravchenko; P. Kroll; L. Lagamba; L. Lapikás; I. Lehmann; P. Lenisa; W. Lorenzon; S. I. Manaenkov; B. Marianski; H. Marukyan; Y. Miyachi; A. Movsisyan; V. Muccifora; A. Nass; W. D. Nowak; L. L. Pappalardo; A. Petrosyan; P. E. Reimer; A. R. Reolon; C. Riedl; K. Rith; G. Rosner; A. Rostomyan; D. Ryckbosch; Y. Salomatin; A. Schäfer; G. Schnell; B. Seitz; T. A. Shibata; V. Shutov; M. Statera; A. Terkulov; R. Truty; A. Trzcinski; M. Tytgat; Y. Van Haarlem; C. Van Hulse; D. Veretennikov; V. Vikhrov; I. Vilardi; S. Yaschenko; B. Zihlmann; P. Zupranski

doi:10.1140/epjc/s10052-017-4899-1

Ratios of helicity amplitudes for exclusive ρ⁰ electroproduction on transversely polarized protons: The HERMES Collaboration

A. Airapetian, N. Akopov, Z. Akopov, E. C. Aschenauer, W. Augustyniak, S. Belostotski, H. P. Blok, A. Borissov, V. Bryzgalov, G. P. Capitani, G. Ciullo, M. Contalbrigo, W. Deconinck, R. De Leo, E. De Sanctis, M. Düren, G. Elbakian, F. Ellinghaus, L. Felawka, S. FrullaniF. Garibaldi, G. Gavrilov, V. Gharibyan, S. V. Goloskokov, Y. Holler, A. Ivanilov, H. E. Jackson, S. Joosten, R. Kaiser, G. Karyan, A. Kisselev, V. Korotkov, V. Kozlov, P. Kravchenko, P. Kroll, L. Lagamba, L. Lapikás, I. Lehmann, P. Lenisa, W. Lorenzon, S. I. Manaenkov, B. Marianski, H. Marukyan, Y. Miyachi, A. Movsisyan, V. Muccifora, A. Nass, W. D. Nowak, L. L. Pappalardo, A. Petrosyan, P. E. Reimer, A. R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, D. Ryckbosch, Y. Salomatin, A. Schäfer, G. Schnell^*, B. Seitz, T. A. Shibata, V. Shutov, M. Statera, A. Terkulov, R. Truty, A. Trzcinski, M. Tytgat, Y. Van Haarlem, C. Van Hulse, D. Veretennikov, V. Vikhrov, I. Vilardi, S. Yaschenko, B. Zihlmann, P. Zupranski

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Abstract

Exclusive ρ⁰-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV²< Q²< 7.0 GeV², 3.0 GeV < W< 6.3 GeV, and - t^′< 0.4 GeV². Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing ρ⁰-meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude F012012, which describes the production of a longitudinal ρ⁰-meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to F012012. Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the π- ρ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 ρ⁰ spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.

Original language	English
Article number	378
Journal	European Physical Journal C
Volume	77
Issue number	6
DOIs	https://doi.org/10.1140/epjc/s10052-017-4899-1
Publication status	Published - 1 Jun 2017

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Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Belostotski, S., Blok, H. P., Borissov, A., Bryzgalov, V., Capitani, G. P., Ciullo, G., Contalbrigo, M., Deconinck, W., De Leo, R., De Sanctis, E., Düren, M., Elbakian, G., Ellinghaus, F., Felawka, L., ... Zupranski, P. (2017). Ratios of helicity amplitudes for exclusive ρ⁰ electroproduction on transversely polarized protons: The HERMES Collaboration. European Physical Journal C, 77(6), Article 378. https://doi.org/10.1140/epjc/s10052-017-4899-1

@article{c48f4c9018e64ca9b8057602e219adbe,

title = "Ratios of helicity amplitudes for exclusive ρ0 electroproduction on transversely polarized protons: The HERMES Collaboration",

abstract = "Exclusive ρ0-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV2< Q2< 7.0 GeV2, 3.0 GeV < W< 6.3 GeV, and - t′< 0.4 GeV2. Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing ρ0-meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude F012012, which describes the production of a longitudinal ρ0-meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to F012012. Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the π- ρ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 ρ0 spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.",

author = "A. Airapetian and N. Akopov and Z. Akopov and Aschenauer, {E. C.} and W. Augustyniak and S. Belostotski and Blok, {H. P.} and A. Borissov and V. Bryzgalov and Capitani, {G. P.} and G. Ciullo and M. Contalbrigo and W. Deconinck and {De Leo}, R. and {De Sanctis}, E. and M. D{\"u}ren and G. Elbakian and F. Ellinghaus and L. Felawka and S. Frullani and F. Garibaldi and G. Gavrilov and V. Gharibyan and Goloskokov, {S. V.} and Y. Holler and A. Ivanilov and Jackson, {H. E.} and S. Joosten and R. Kaiser and G. Karyan and A. Kisselev and V. Korotkov and V. Kozlov and P. Kravchenko and P. Kroll and L. Lagamba and L. Lapik{\'a}s and I. Lehmann and P. Lenisa and W. Lorenzon and Manaenkov, {S. I.} and B. Marianski and H. Marukyan and Y. Miyachi and A. Movsisyan and V. Muccifora and A. Nass and Nowak, {W. D.} and Pappalardo, {L. L.} and A. Petrosyan and Reimer, {P. E.} and Reolon, {A. R.} and C. Riedl and K. Rith and G. Rosner and A. Rostomyan and D. Ryckbosch and Y. Salomatin and A. Sch{\"a}fer and G. Schnell and B. Seitz and Shibata, {T. A.} and V. Shutov and M. Statera and A. Terkulov and R. Truty and A. Trzcinski and M. Tytgat and {Van Haarlem}, Y. and {Van Hulse}, C. and D. Veretennikov and V. Vikhrov and I. Vilardi and S. Yaschenko and B. Zihlmann and P. Zupranski",

year = "2017",

month = jun,

day = "1",

doi = "10.1140/epjc/s10052-017-4899-1",

language = "English",

volume = "77",

journal = "European Physical Journal C",

issn = "1434-6044",

publisher = "Springer New York",

number = "6",

}

Airapetian, A, Akopov, N, Akopov, Z, Aschenauer, EC, Augustyniak, W, Belostotski, S, Blok, HP, Borissov, A, Bryzgalov, V, Capitani, GP, Ciullo, G, Contalbrigo, M, Deconinck, W, De Leo, R, De Sanctis, E, Düren, M, Elbakian, G, Ellinghaus, F, Felawka, L, Frullani, S, Garibaldi, F, Gavrilov, G, Gharibyan, V, Goloskokov, SV, Holler, Y, Ivanilov, A, Jackson, HE, Joosten, S, Kaiser, R, Karyan, G, Kisselev, A, Korotkov, V, Kozlov, V, Kravchenko, P, Kroll, P, Lagamba, L, Lapikás, L, Lehmann, I, Lenisa, P, Lorenzon, W, Manaenkov, SI, Marianski, B, Marukyan, H, Miyachi, Y, Movsisyan, A, Muccifora, V, Nass, A, Nowak, WD, Pappalardo, LL, Petrosyan, A, Reimer, PE, Reolon, AR, Riedl, C, Rith, K, Rosner, G, Rostomyan, A, Ryckbosch, D, Salomatin, Y, Schäfer, A, Schnell, G, Seitz, B, Shibata, TA, Shutov, V, Statera, M, Terkulov, A, Truty, R, Trzcinski, A, Tytgat, M, Van Haarlem, Y, Van Hulse, C, Veretennikov, D, Vikhrov, V, Vilardi, I, Yaschenko, S, Zihlmann, B & Zupranski, P 2017, 'Ratios of helicity amplitudes for exclusive ρ⁰ electroproduction on transversely polarized protons: The HERMES Collaboration', European Physical Journal C, vol. 77, no. 6, 378. https://doi.org/10.1140/epjc/s10052-017-4899-1

TY - JOUR

T1 - Ratios of helicity amplitudes for exclusive ρ0 electroproduction on transversely polarized protons

T2 - The HERMES Collaboration

AU - Airapetian, A.

AU - Akopov, N.

AU - Akopov, Z.

AU - Aschenauer, E. C.

AU - Augustyniak, W.

AU - Belostotski, S.

AU - Blok, H. P.

AU - Borissov, A.

AU - Bryzgalov, V.

AU - Capitani, G. P.

AU - Ciullo, G.

AU - Contalbrigo, M.

AU - Deconinck, W.

AU - De Leo, R.

AU - De Sanctis, E.

AU - Düren, M.

AU - Elbakian, G.

AU - Ellinghaus, F.

AU - Felawka, L.

AU - Frullani, S.

AU - Garibaldi, F.

AU - Gavrilov, G.

AU - Gharibyan, V.

AU - Goloskokov, S. V.

AU - Holler, Y.

AU - Ivanilov, A.

AU - Jackson, H. E.

AU - Joosten, S.

AU - Kaiser, R.

AU - Karyan, G.

AU - Kisselev, A.

AU - Korotkov, V.

AU - Kozlov, V.

AU - Kravchenko, P.

AU - Kroll, P.

AU - Lagamba, L.

AU - Lapikás, L.

AU - Lehmann, I.

AU - Lenisa, P.

AU - Lorenzon, W.

AU - Manaenkov, S. I.

AU - Marianski, B.

AU - Marukyan, H.

AU - Miyachi, Y.

AU - Movsisyan, A.

AU - Muccifora, V.

AU - Nass, A.

AU - Nowak, W. D.

AU - Pappalardo, L. L.

AU - Petrosyan, A.

AU - Reimer, P. E.

AU - Reolon, A. R.

AU - Riedl, C.

AU - Rith, K.

AU - Rosner, G.

AU - Rostomyan, A.

AU - Ryckbosch, D.

AU - Salomatin, Y.

AU - Schäfer, A.

AU - Schnell, G.

AU - Seitz, B.

AU - Shibata, T. A.

AU - Shutov, V.

AU - Statera, M.

AU - Terkulov, A.

AU - Truty, R.

AU - Trzcinski, A.

AU - Tytgat, M.

AU - Van Haarlem, Y.

AU - Van Hulse, C.

AU - Veretennikov, D.

AU - Vikhrov, V.

AU - Vilardi, I.

AU - Yaschenko, S.

AU - Zihlmann, B.

AU - Zupranski, P.

PY - 2017/6/1

Y1 - 2017/6/1

N2 - Exclusive ρ0-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV2< Q2< 7.0 GeV2, 3.0 GeV < W< 6.3 GeV, and - t′< 0.4 GeV2. Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing ρ0-meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude F012012, which describes the production of a longitudinal ρ0-meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to F012012. Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the π- ρ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 ρ0 spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.

AB - Exclusive ρ0-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV2< Q2< 7.0 GeV2, 3.0 GeV < W< 6.3 GeV, and - t′< 0.4 GeV2. Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing ρ0-meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude F012012, which describes the production of a longitudinal ρ0-meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to F012012. Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the π- ρ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 ρ0 spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.

UR - http://www.scopus.com/inward/record.url?scp=85020636930&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85020636930&partnerID=8YFLogxK

U2 - 10.1140/epjc/s10052-017-4899-1

DO - 10.1140/epjc/s10052-017-4899-1

M3 - Article

AN - SCOPUS:85020636930

SN - 1434-6044

VL - 77

JO - European Physical Journal C

JF - European Physical Journal C

IS - 6

M1 - 378

ER -

Ratios of helicity amplitudes for exclusive ρ⁰ electroproduction on transversely polarized protons: The HERMES Collaboration

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