Measurement of the ratio of prompt $\chi_{c}$ to $J/\psi$ production in $pp$ collisions at $\sqrt{s}=7$ TeV
R. Aaij
,
S. Barsuk
(1)
,
O. Callot
(1)
,
J. He
(1)
,
B. Jean-Marie
(1)
,
J. Lefrançois
(1)
,
F. Machefert
(1)
,
A. Martin Sanchez
(1)
,
M. Nicol
(1)
,
P. Robbe
(1)
,
M.-H. Schune
(1)
,
B. Viaud
(1)
,
I. Videau
(1)
,
E. Ben-Haim
(2)
,
M. Benayoun
(2)
,
P. David
(2)
,
L. del Buono
(2)
,
A. Martens
(2)
,
Ziad Zj Ajaltouni
(3)
,
O. Deschamps
(3)
,
Pierre Henrard
(3)
,
Marwa Jahjah-Hussein
(3)
,
R. Lefèvre
(3)
,
L. Li Gioi
(3)
,
S. Monteil
(3)
,
V. Niess
(3)
,
Pascal Perret
(3)
,
Diego Alejandro Roa Romero
(3)
,
Krzysztof Grzegorz Sobczak
(3)
,
I. de Bonis
(4)
,
D. Decamp
(4)
,
P. Ghez
(4)
,
P. Hopchev
(4)
,
J.P. Lees
(4)
,
I. Machikhiliyan
(4)
,
M.N. Minard
(4)
,
B. Pietrzyk
(4)
,
S. t'Jampens
(4)
,
V. Tisserand
(4)
,
E. Tournefier
(4)
,
C. Adrover
(5)
,
E. Aslanides
(5)
,
J. Cogan
(5)
,
B. Khanji
(5)
,
R. Legac
(5)
,
O. Leroy
(5)
,
G. Mancinelli
(5)
,
E. Maurice
(5)
,
M. Perrin-Terrin
(5)
,
M. Sapunov
(5)
,
J. Serrano
(5)
,
A. Tsaregorodtsev
(5)
R. Aaij
- Function : Author
J. He
- Function : Author
- PersonId : 756138
- ORCID : 0000-0001-8179-417X
L. del Buono
- Function : Author
- PersonId : 742055
- IdHAL : luigi-del-buono
- ORCID : 0000-0003-4774-2194
- IdRef : 253135834
A. Martens
- Function : Author
- PersonId : 738690
- IdHAL : aurelien-martens
Ziad Zj Ajaltouni
- Function : Author
- PersonId : 903794
O. Deschamps
- Function : Author
- PersonId : 12089
- IdHAL : olivier-deschamps
- ORCID : 0000-0002-7047-6042
- IdRef : 161447368
Pierre Henrard
- Function : Author
- PersonId : 829303
Pascal Perret
- Function : Author
- PersonId : 739797
- IdHAL : pascal-perret
- ORCID : 0000-0002-5732-4343
Diego Alejandro Roa Romero
- Function : Author
- PersonId : 769524
- IdRef : 172096839
S. t'Jampens
- Function : Author
- PersonId : 736045
- IdHAL : stephane-tjampens
- ORCID : 0000-0003-4249-6641
J. Cogan
- Function : Author
- PersonId : 750510
- IdHAL : julien-cogan
- ORCID : 0000-0001-7194-7566
- IdRef : 078779014
O. Leroy
- Function : Author
- PersonId : 171866
- IdHAL : olivier-leroy
- ORCID : 0000-0002-2589-240X
- IdRef : 169871835
M. Perrin-Terrin
- Function : Author
- PersonId : 741779
- IdHAL : perrin-terrin
- ORCID : 0000-0002-3568-1956
- IdRef : 179269666
J. Serrano
- Function : Author
- PersonId : 175327
- IdHAL : justine-serrano
- ORCID : 0000-0003-2489-7812
- IdRef : 127525521
Abstract
The prompt production of charmonium $\chi_{c}$ and $J/\psi$ states is studied in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV at the Large Hadron Collider. The $\chi_{c}$ and $J/\psi$ mesons are identified through their decays $\chi_{c}\rightarrow J/\psi \gamma$ and $J/\psi\rightarrow \mu^+\mu^-$ using 36 pb$^{-1}$ of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for $\chi_{c}$ and $J/\psi$, $\sigma (\chi_{c}\rightarrow J/\psi \gamma)/ \sigma (J/\psi)$, is determined as a function of the $J/\psi$ transverse momentum in the range $2 < p_{\mathrm T}^{J/\psi} < 15$ GeV/$c$. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low $p_{\mathrm T}^{J/\psi}$ region.