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

^*Corresponding author for this work

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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

Funding

We gratefully acknowledge the DESY management for its support and the staff at DESY as well as the collaborating institutions for their significant effort. This work was supported by the State Committee of Science of the Republic of Armenia, Grant No. 15T-1C401; the FWO-Flanders and IWT, Belgium; the Natural Sciences and Engineering Research Council of Canada; the Alexander von Humboldt Stiftung, the German Bundesministerium f?r Bildung und Forschung (BMBF), and the Deutsche Forschungsgemeinschaft (DFG); the Italian Istituto Nazionale di Fisica Nucleare (INFN); the MEXT, JSPS, and G-COE of Japan; the Dutch Foundation for Fundamenteel Onderzoek der Materie (FOM); the Russian Academy of Science and the Russian Federal Agency for Science and Innovations; the Basque Foundation for Science (IKERBASQUE) and MINECO (Juan de la Cierva), Spain; the U.K. Engineering and Physical Sciences Research Council, the Science and Technology Facilities Council, and the Scottish Universities Physics Alliance; as well as the U.S. Department of Energy (DOE) and the National Science Foundation (NSF).

Funders	Funder number
Dutch Foundation for Fundamenteel Onderzoek der Materie
FWO-Flanders
German Bundesministerium für Bildung und Forschung
Russian Federal Agency for Science and Innovations
State Committee of Science of the Republic of Armenia	15T-1C401
National Science Foundation
U.S. Department of Energy
Alexander von Humboldt-Stiftung
Natural Sciences and Engineering Research Council of Canada
Engineering and Physical Sciences Research Council
Science and Technology Facilities Council
Scottish Universities Physics Alliance
Deutsche Forschungsgemeinschaft
Japan Society for the Promotion of Science
Ministry of Education, Culture, Sports, Science and Technology
Stichting voor Fundamenteel Onderzoek der Materie
Bundesministerium für Bildung und Forschung
Russian Academy of Sciences
Agentschap voor Innovatie door Wetenschap en Technologie
Ministerio de Economía y Competitividad
Ikerbasque, Basque Foundation for Science
Instituto Nazionale di Fisica Nucleare
Istituto Nazionale di Fisica Nucleare

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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 -