Complete Measurement of the Λ Electromagnetic Form Factors

(BESIII Collaboration)

doi:10.1103/PhysRevLett.123.122003

Complete Measurement of the Λ Electromagnetic Form Factors

(BESIII Collaboration)

Physics and Astronomy (Twin Cities)

Research output: Contribution to journal › Article › peer-review

60 Scopus citations

Abstract

The exclusive process e^{+}e^{-}→ΛΛ[over ¯], with Λ→pπ^{-} and Λ[over ¯]→p[over ¯]π^{+}, has been studied at sqrt[s]=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, G_{E} and G_{M}. A data sample, corresponding to an integrated luminosity of 66.9 pb^{-1}, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|G_{E}/G_{M}| and, for the first time for any baryon, the relative phase ΔΦ=Φ_{E}-Φ_{M}. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter α_{Λ}=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst) pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.

Original language	English (US)
Article number	122003
Journal	Physical review letters
Volume	123
Issue number	12
DOIs	https://doi.org/10.1103/PhysRevLett.123.122003
State	Published - Sep 20 2019

Bibliographical note

Publisher Copyright:
© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP.

PubMed: MeSH publication types

Journal Article

Publisher link

10.1103/PhysRevLett.123.122003

Find It

Find It at U of M Libraries

Cite this

@article{4e8d4979c66f42e88933c049de6785ae,

title = "Complete Measurement of the Λ Electromagnetic Form Factors",

abstract = "The exclusive process e^{+}e^{-}→ΛΛ[over ¯], with Λ→pπ^{-} and Λ[over ¯]→p[over ¯]π^{+}, has been studied at sqrt[s]=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, G_{E} and G_{M}. A data sample, corresponding to an integrated luminosity of 66.9 pb^{-1}, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|G_{E}/G_{M}| and, for the first time for any baryon, the relative phase ΔΦ=Φ_{E}-Φ_{M}. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter α_{Λ}=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst) pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.",

author = "{(BESIII Collaboration)} and M. Ablikim and Achasov, {M. N.} and P. Adlarson and S. Ahmed and M. Albrecht and M. Alekseev and A. Amoroso and An, {F. F.} and Q. An and Y. Bai and O. Bakina and {Baldini Ferroli}, R. and Y. Ban and K. Begzsuren and Bennett, {J. V.} and N. Berger and M. Bertani and D. Bettoni and F. Bianchi and J. Biernat and J. Bloms and I. Boyko and Briere, {R. A.} and H. Cai and X. Cai and A. Calcaterra and Cao, {G. F.} and N. Cao and Cetin, {S. A.} and J. Chai and Chang, {J. F.} and Chang, {W. L.} and G. Chelkov and Chen, {D. Y.} and G. Chen and Chen, {H. S.} and Chen, {J. C.} and Chen, {M. L.} and Chen, {S. J.} and Chen, {Y. B.} and W. Cheng and G. Cibinetto and F. Cossio and Cui, {X. F.} and Dai, {H. L.} and Dai, {J. P.} and Dai, {X. C.} and A. Dbeyssi and Deng, {Z. Y.} and H. Muramatsu",

note = "Publisher Copyright: {\textcopyright} 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP.",

year = "2019",

month = sep,

day = "20",

doi = "10.1103/PhysRevLett.123.122003",

language = "English (US)",

volume = "123",

journal = "Physical review letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "12",

}

TY - JOUR

T1 - Complete Measurement of the Λ Electromagnetic Form Factors

AU - (BESIII Collaboration)

AU - Ablikim, M.

AU - Achasov, M. N.

AU - Adlarson, P.

AU - Ahmed, S.

AU - Albrecht, M.

AU - Alekseev, M.

AU - Amoroso, A.

AU - An, F. F.

AU - An, Q.

AU - Bai, Y.

AU - Bakina, O.

AU - Baldini Ferroli, R.

AU - Ban, Y.

AU - Begzsuren, K.

AU - Bennett, J. V.

AU - Berger, N.

AU - Bertani, M.

AU - Bettoni, D.

AU - Bianchi, F.

AU - Biernat, J.

AU - Bloms, J.

AU - Boyko, I.

AU - Briere, R. A.

AU - Cai, H.

AU - Cai, X.

AU - Calcaterra, A.

AU - Cao, G. F.

AU - Cao, N.

AU - Cetin, S. A.

AU - Chai, J.

AU - Chang, J. F.

AU - Chang, W. L.

AU - Chelkov, G.

AU - Chen, D. Y.

AU - Chen, G.

AU - Chen, H. S.

AU - Chen, J. C.

AU - Chen, M. L.

AU - Chen, S. J.

AU - Chen, Y. B.

AU - Cheng, W.

AU - Cibinetto, G.

AU - Cossio, F.

AU - Cui, X. F.

AU - Dai, H. L.

AU - Dai, J. P.

AU - Dai, X. C.

AU - Dbeyssi, A.

AU - Deng, Z. Y.

AU - Muramatsu, H.

N1 - Publisher Copyright: © 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP.

PY - 2019/9/20

Y1 - 2019/9/20

N2 - The exclusive process e^{+}e^{-}→ΛΛ[over ¯], with Λ→pπ^{-} and Λ[over ¯]→p[over ¯]π^{+}, has been studied at sqrt[s]=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, G_{E} and G_{M}. A data sample, corresponding to an integrated luminosity of 66.9 pb^{-1}, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|G_{E}/G_{M}| and, for the first time for any baryon, the relative phase ΔΦ=Φ_{E}-Φ_{M}. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter α_{Λ}=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst) pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.

AB - The exclusive process e^{+}e^{-}→ΛΛ[over ¯], with Λ→pπ^{-} and Λ[over ¯]→p[over ¯]π^{+}, has been studied at sqrt[s]=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, G_{E} and G_{M}. A data sample, corresponding to an integrated luminosity of 66.9 pb^{-1}, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|G_{E}/G_{M}| and, for the first time for any baryon, the relative phase ΔΦ=Φ_{E}-Φ_{M}. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter α_{Λ}=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst) pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.

UR - http://www.scopus.com/inward/record.url?scp=85072785332&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85072785332&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.123.122003

DO - 10.1103/PhysRevLett.123.122003

M3 - Article

C2 - 31633986

AN - SCOPUS:85072785332

SN - 0031-9007

VL - 123

JO - Physical review letters

JF - Physical review letters

IS - 12

M1 - 122003

ER -

Complete Measurement of the Λ Electromagnetic Form Factors

Abstract

Bibliographical note

PubMed: MeSH publication types

Publisher link

Find It

Other files and links

Fingerprint

Cite this