Coherent diffractive photoproduction of ρ0 mesons on gold nuclei at 200 GeV/nucleon-pair at the Relativistic Heavy Ion Collider

STAR Collaboration

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The STAR Collaboration reports on the photoproduction of π+π- pairs in gold-gold collisions at a center-of-mass energy of 200 GeV/nucleon-pair. These pion pairs are produced when a nearly real photon emitted by one ion scatters from the other ion. We fit the π+π- invariant-mass spectrum with a combination of ρ0 and ω resonances and a direct π+π- continuum. This is the first observation of the ω in ultraperipheral collisions, and the first measurement of ρ-ω interference at energies where photoproduction is dominated by Pomeron exchange. The ω amplitude is consistent with the measured γp→ωp cross section, a classical Glauber calculation, and the ω→π+π- branching ratio. The ω phase angle is similar to that observed at much lower energies, showing that the ρ-ω phase difference does not depend significantly on photon energy. The ρ0 differential cross section dσ/dt exhibits a clear diffraction pattern, compatible with scattering from a gold nucleus, with two minima visible. The positions of the diffractive minima agree better with the predictions of a quantum Glauber calculation that does not include nuclear shadowing than with a calculation that does include shadowing.

Original languageEnglish (US)
Article number054904
JournalPhysical Review C
Volume96
Issue number5
DOIs
StatePublished - Nov 13 2017

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photoproduction
heavy ions
mesons
gold
nuclei
collisions
energy
cross sections
photons
mass spectra
center of mass
ions
pions
phase shift
diffraction patterns
continuums
interference
predictions
scattering

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

Cite this

Coherent diffractive photoproduction of ρ0 mesons on gold nuclei at 200 GeV/nucleon-pair at the Relativistic Heavy Ion Collider. / STAR Collaboration.

In: Physical Review C, Vol. 96, No. 5, 054904, 13.11.2017.

Research output: Contribution to journalArticle

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title = "Coherent diffractive photoproduction of ρ0 mesons on gold nuclei at 200 GeV/nucleon-pair at the Relativistic Heavy Ion Collider",
abstract = "The STAR Collaboration reports on the photoproduction of π+π- pairs in gold-gold collisions at a center-of-mass energy of 200 GeV/nucleon-pair. These pion pairs are produced when a nearly real photon emitted by one ion scatters from the other ion. We fit the π+π- invariant-mass spectrum with a combination of ρ0 and ω resonances and a direct π+π- continuum. This is the first observation of the ω in ultraperipheral collisions, and the first measurement of ρ-ω interference at energies where photoproduction is dominated by Pomeron exchange. The ω amplitude is consistent with the measured γp→ωp cross section, a classical Glauber calculation, and the ω→π+π- branching ratio. The ω phase angle is similar to that observed at much lower energies, showing that the ρ-ω phase difference does not depend significantly on photon energy. The ρ0 differential cross section dσ/dt exhibits a clear diffraction pattern, compatible with scattering from a gold nucleus, with two minima visible. The positions of the diffractive minima agree better with the predictions of a quantum Glauber calculation that does not include nuclear shadowing than with a calculation that does include shadowing.",
author = "{STAR Collaboration} and L. Adamczyk and Adkins, {J. K.} and G. Agakishiev and Aggarwal, {M. M.} and Z. Ahammed and Ajitanand, {N. N.} and I. Alekseev and Anderson, {D. M.} and R. Aoyama and A. Aparin and D. Arkhipkin and Aschenauer, {E. C.} and Ashraf, {M. U.} and A. Attri and Averichev, {G. S.} and X. Bai and V. Bairathi and A. Behera and R. Bellwied and A. Bhasin and Bhati, {A. K.} and P. Bhattarai and J. Bielcik and J. Bielcikova and Bland, {L. C.} and Bordyuzhin, {I. G.} and J. Bouchet and Brandenburg, {J. D.} and Brandin, {A. V.} and D. Brown and I. Bunzarov and J. Butterworth and H. Caines and {Calder{\'o}n De La Barca S{\'a}nchez}, M. and Campbell, {J. M.} and D. Cebra and I. Chakaberia and P. Chaloupka and Z. Chang and N. Chankova-Bunzarova and A. Chatterjee and S. Chattopadhyay and X. Chen and Chen, {J. H.} and X. Chen and J. Cheng and Cherney, {Michael G.} and W. Christie and G. Contin and Seger, {Janet E.}",
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AU - Agakishiev, G.

AU - Aggarwal, M. M.

AU - Ahammed, Z.

AU - Ajitanand, N. N.

AU - Alekseev, I.

AU - Anderson, D. M.

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AU - Aparin, A.

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AU - Bai, X.

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AU - Bouchet, J.

AU - Brandenburg, J. D.

AU - Brandin, A. V.

AU - Brown, D.

AU - Bunzarov, I.

AU - Butterworth, J.

AU - Caines, H.

AU - Calderón De La Barca Sánchez, M.

AU - Campbell, J. M.

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AU - Chaloupka, P.

AU - Chang, Z.

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AU - Chen, X.

AU - Chen, J. H.

AU - Chen, X.

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