Measurement of the cross section for hard exclusive π0 muoproduction on the proton

The COMPASS Collaboration

doi:10.1016/j.physletb.2020.135454

Measurement of the cross section for hard exclusive π⁰ muoproduction on the proton

The COMPASS Collaboration

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

Abstract

We report on a measurement of hard exclusive π⁰ muoproduction on the proton by COMPASS using 160 GeV/c polarised μ⁺ and μ⁻ beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured μ⁺ and μ⁻ cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range 0.08(GeV/c)²<|t|<0.64(GeV/c)². The average kinematics of the measurement are 〈Q²〉=2.0(GeV/c)², 〈ν〉=12.8GeV, 〈x_Bj〉=0.093 and 〈−t〉=0.256(GeV/c)². Fitting the azimuthal dependence reveals a combined contribution by transversely and longitudinally polarised photons of (8.2±0.9_stat _−1.2 ^+1.2|_sys)nb/(GeV/c)², as well as transverse-transverse and longitudinal-transverse interference contributions of (−6.1±1.3_stat _−0.7 ^+0.7|_sys)nb/(GeV/c)² and (1.5±0.5_stat _−0.2 ^+0.3|_sys)nb/(GeV/c)², respectively. Our results provide important input for modelling Generalised Parton Distributions. In the context of the phenomenological Goloskokov-Kroll model, the statistically significant transverse-transverse interference contribution constitutes clear experimental evidence for the chiral-odd GPD E‾_T.

Original language	English (US)
Article number	135454
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	805
DOIs	https://doi.org/10.1016/j.physletb.2020.135454
State	Published - Jun 10 2020

Keywords

COMPASS
Generalised Parton Distributions
Hard exclusive meson production
Muoproduction
Quantum chromodynamics

ASJC Scopus subject areas

Nuclear and High Energy Physics

Online availability

10.1016/j.physletb.2020.135454License: CC BY

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Cite this

@article{e5700604e3874f8d8ec15c7496ad7319,

title = "Measurement of the cross section for hard exclusive π0 muoproduction on the proton",

abstract = "We report on a measurement of hard exclusive π0 muoproduction on the proton by COMPASS using 160 GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured μ+ and μ− cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range 0.08(GeV/c)2<|t|<0.64(GeV/c)2. The average kinematics of the measurement are 〈Q2〉=2.0(GeV/c)2, 〈ν〉=12.8GeV, 〈xBj〉=0.093 and 〈−t〉=0.256(GeV/c)2. Fitting the azimuthal dependence reveals a combined contribution by transversely and longitudinally polarised photons of (8.2±0.9stat −1.2 +1.2|sys)nb/(GeV/c)2, as well as transverse-transverse and longitudinal-transverse interference contributions of (−6.1±1.3stat −0.7 +0.7|sys)nb/(GeV/c)2 and (1.5±0.5stat −0.2 +0.3|sys)nb/(GeV/c)2, respectively. Our results provide important input for modelling Generalised Parton Distributions. In the context of the phenomenological Goloskokov-Kroll model, the statistically significant transverse-transverse interference contribution constitutes clear experimental evidence for the chiral-odd GPD E‾T.",

keywords = "COMPASS, Generalised Parton Distributions, Hard exclusive meson production, Muoproduction, Quantum chromodynamics",

author = "{The COMPASS Collaboration} and Alexeev, {M. G.} and Alexeev, {G. D.} and A. Amoroso and V. Andrieux and Anfimov, {N. V.} and V. Anosov and A. Antoshkin and K. Augsten and W. Augustyniak and Azevedo, {C. D.R.} and B. Bade{\l}ek and F. Balestra and M. Ball and J. Barth and R. Beck and Y. Bedfer and J. Bernhard and M. Bodlak and P. Bordalo and F. Bradamante and A. Bressan and M. B{\"u}chele and Burtsev, {V. E.} and Chang, {W. C.} and C. Chatterjee and M. Chiosso and Chumakov, {A. G.} and Chung, {S. U.} and A. Cicuttin and Crespo, {M. L.} and {Dalla Torre}, S. and Dasgupta, {S. S.} and S. Dasgupta and Denisov, {O. Yu} and L. Dhara and Donskov, {S. V.} and N. Doshita and Ch Dreisbach and W. D{\"u}nnweber and Dusaev, {R. R.} and A. Efremov and Eversheim, {P. D.} and M. Faessler and A. Ferrero and M. Finger and H. Fischer and {Grosse Perdekamp}, M. and N. Makins and Peng, {J. C.} and C. Riedl",

note = "Publisher Copyright: {\textcopyright} 2020 The Author(s)",

year = "2020",

month = jun,

day = "10",

doi = "10.1016/j.physletb.2020.135454",

language = "English (US)",

volume = "805",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Measurement of the cross section for hard exclusive π0 muoproduction on the proton

AU - The COMPASS Collaboration

AU - Alexeev, M. G.

AU - Alexeev, G. D.

AU - Amoroso, A.

AU - Andrieux, V.

AU - Anfimov, N. V.

AU - Anosov, V.

AU - Antoshkin, A.

AU - Augsten, K.

AU - Augustyniak, W.

AU - Azevedo, C. D.R.

AU - Badełek, B.

AU - Balestra, F.

AU - Ball, M.

AU - Barth, J.

AU - Beck, R.

AU - Bedfer, Y.

AU - Bernhard, J.

AU - Bodlak, M.

AU - Bordalo, P.

AU - Bradamante, F.

AU - Bressan, A.

AU - Büchele, M.

AU - Burtsev, V. E.

AU - Chang, W. C.

AU - Chatterjee, C.

AU - Chiosso, M.

AU - Chumakov, A. G.

AU - Chung, S. U.

AU - Cicuttin, A.

AU - Crespo, M. L.

AU - Dalla Torre, S.

AU - Dasgupta, S. S.

AU - Dasgupta, S.

AU - Denisov, O. Yu

AU - Dhara, L.

AU - Donskov, S. V.

AU - Doshita, N.

AU - Dreisbach, Ch

AU - Dünnweber, W.

AU - Dusaev, R. R.

AU - Efremov, A.

AU - Eversheim, P. D.

AU - Faessler, M.

AU - Ferrero, A.

AU - Finger, M.

AU - Fischer, H.

AU - Grosse Perdekamp, M.

AU - Makins, N.

AU - Peng, J. C.

AU - Riedl, C.

PY - 2020/6/10

Y1 - 2020/6/10

N2 - We report on a measurement of hard exclusive π0 muoproduction on the proton by COMPASS using 160 GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured μ+ and μ− cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range 0.08(GeV/c)2<|t|<0.64(GeV/c)2. The average kinematics of the measurement are 〈Q2〉=2.0(GeV/c)2, 〈ν〉=12.8GeV, 〈xBj〉=0.093 and 〈−t〉=0.256(GeV/c)2. Fitting the azimuthal dependence reveals a combined contribution by transversely and longitudinally polarised photons of (8.2±0.9stat −1.2 +1.2|sys)nb/(GeV/c)2, as well as transverse-transverse and longitudinal-transverse interference contributions of (−6.1±1.3stat −0.7 +0.7|sys)nb/(GeV/c)2 and (1.5±0.5stat −0.2 +0.3|sys)nb/(GeV/c)2, respectively. Our results provide important input for modelling Generalised Parton Distributions. In the context of the phenomenological Goloskokov-Kroll model, the statistically significant transverse-transverse interference contribution constitutes clear experimental evidence for the chiral-odd GPD E‾T.

AB - We report on a measurement of hard exclusive π0 muoproduction on the proton by COMPASS using 160 GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured μ+ and μ− cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range 0.08(GeV/c)2<|t|<0.64(GeV/c)2. The average kinematics of the measurement are 〈Q2〉=2.0(GeV/c)2, 〈ν〉=12.8GeV, 〈xBj〉=0.093 and 〈−t〉=0.256(GeV/c)2. Fitting the azimuthal dependence reveals a combined contribution by transversely and longitudinally polarised photons of (8.2±0.9stat −1.2 +1.2|sys)nb/(GeV/c)2, as well as transverse-transverse and longitudinal-transverse interference contributions of (−6.1±1.3stat −0.7 +0.7|sys)nb/(GeV/c)2 and (1.5±0.5stat −0.2 +0.3|sys)nb/(GeV/c)2, respectively. Our results provide important input for modelling Generalised Parton Distributions. In the context of the phenomenological Goloskokov-Kroll model, the statistically significant transverse-transverse interference contribution constitutes clear experimental evidence for the chiral-odd GPD E‾T.

KW - COMPASS

KW - Generalised Parton Distributions

KW - Hard exclusive meson production

KW - Muoproduction

KW - Quantum chromodynamics

UR - http://www.scopus.com/inward/record.url?scp=85084498386&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85084498386&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2020.135454

DO - 10.1016/j.physletb.2020.135454

M3 - Article

AN - SCOPUS:85084498386

SN - 0370-2693

VL - 805

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

M1 - 135454

ER -