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Probing gluonic spin-orbit correlations in photon pair production
Jian-Wei Qiu1, Marc Schlegel, Werner Vogelsang
1Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Physical Review Letters
|September 10, 2011
Summary
We explored photon pair production in hadronic collisions. Our findings reveal new azimuthal dependencies related to gluon distributions, offering unique insights into their properties.
Area of Science:
- High Energy Physics
- Quantum Chromodynamics
- Particle Physics
Background:
- Photon pair production in hadronic collisions is a key process for probing the internal structure of hadrons.
- Factorization theorems in Quantum Chromodynamics (QCD) are crucial for relating experimental observables to partonic properties.
- Transverse-momentum dependent (TMD) parton distributions offer a more detailed picture of hadron structure than integrated distributions.
Purpose of the Study:
- To investigate azimuthal angular dependencies in the unpolarized and single transversely polarized cross sections for photon pair production.
- To explore the sensitivity of these cross sections to specific TMD parton distributions, namely the Boer-Mulders and Sivers functions.
- To assess the potential of diphoton production at the Relativistic Heavy Ion Collider (RHIC) for studying TMD gluon distributions.
Main Methods:
- Application of factorization in terms of transverse-momentum dependent parton distributions.
- Analysis of azimuthal angular dependencies in the unpolarized and single transversely polarized cross sections.
- Numerical estimation of Boer-Mulders and Sivers effects in diphoton production.
Main Results:
- The unpolarized cross section exhibits azimuthal angular dependencies driven by a gluonic Boer-Mulders function.
- The single transversely polarized cross section is sensitive to the gluon Sivers function.
- Simple numerical estimates for Boer-Mulders and Sivers effects in diphoton production at RHIC were calculated.
Conclusions:
- Diphoton production at RHIC provides a promising avenue for exploring TMD gluon distributions.
- The study highlights the importance of Boer-Mulders and Sivers functions in understanding hadron structure.
- Future experimental measurements can further constrain these fundamental gluon properties.
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