Production of $\chi_c$ pairs in $k_T$-factorization
Abstract
We calculate the production of pairs of $\chi_c(J)$ mesons with all possible combinations of $J=0,1,2$. The leading order production mechanism is the crossed-channel gluon exchange in the gluon-gluon fusion reaction. The building blocks are the vertices $g^* g^* \to \chi_c(J)$ for off shell gluons. We stick to the color-singlet model and calculate the gluon fusion vertices in the limit of heavy quarks with nonrelativistic motion in the bound state. These vertices are used to construct the $g^* g^* \to \chi_c(J_1) \chi_c(J_2)$ amplitudes. We then calculate hadron-level cross sections using the $k_T$-factorization approach. In our numerical predictions, we use the KMR-type unintegrated gluon distributions. Several differential distributions at the $pp$ center of mass energy $\sqrt{s} = 8 \, {\rm TeV}$ are shown. The salient feature of the $t$ and $u$-channel gluon exchange are the broad distributions in rapidity difference $\Delta y$ between $\chi_c$ mesons.
- Publication:
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arXiv e-prints
- Pub Date:
- November 2017
- DOI:
- 10.48550/arXiv.1711.07366
- arXiv:
- arXiv:1711.07366
- Bibcode:
- 2017arXiv171107366C
- Keywords:
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- High Energy Physics - Phenomenology
- E-Print:
- 15 pages, 8 figures