# Rencontre de Physique des Particules 2015

15-16 January 2015
Institut Henri Poincaré
Europe/Paris timezone

## J/psi-Pair Production at Large Momenta: Indications for Double-Parton Scatterings and Large alpha_s^5 Contributions

15 Jan 2015, 10:07
14m
Chair: Sébastien Descotes-Genon, Amphi Hermite (Institut Henri Poincaré)

### Chair: Sébastien Descotes-Genon, Amphi Hermite

#### Institut Henri Poincaré

11, rue Pierre et Marie Curie 75005 Paris

### Speaker

Dr Hua-Sheng Shao (CERN)

### Description

The recent observations of prompt $J/\psi$-pair production by CMS at the LHC and by D0 at the Tevatron reveal the presence of different production mechanisms in different kinematical regions. We find out that next-to-leading-order single-parton-scattering contributions at $\alpha_s^5$ dominate the yield at large transverse momenta of the pair. Our analysis further emphasises the importance of double-parton-scatterings --which are expected to dominate the yield at large rapidity differences-- at large invariant masses of the pair in the CMS acceptance. In addition, we provide the first exact --gauge-invariant and infrared-safe-- evaluation of a class of leading-$P_T$ next-to-next-to-leading-order contributions, which are dominant in the region of large sub-leading transverse momenta, precisely where the colour-octet contributions can be non-negligible. Finally, we discuss the contribution from decays of excited charmonium states within both single- and double-parton scatterings and suggest measurements to distinguish them.

### Primary authors

Dr Hua-Sheng Shao (CERN) Dr Jean-Philippe Lansberg (IPNO - Paris-Sud U. - CNRS/IN2P3)

### Presentation Materials

 Transparents