G. Aad, E. Aakvaag, B. Abbott, S. Abdelhameed, K. Abeling, N. J. Abicht, S. H. Abidi, M. Aboelela, A. Aboulhorma, H. Abramowicz, Y. Abulaiti, B. S. Acharya, A. Ackermann, C. Adam Bourdarios, L. Adamczyk, S. V. Addepalli, M. J. Addison, J. Adelman, A. Adiguzel, T. Adye, A. A. Affolder, Y. Afik, M. N. Agaras, A. Aggarwal, C. Agheorghiesei, F. Ahmadov, S. Ahuja, S. Ahuja, X. Ai, G. Aielli, A. Aikot, M. Ait Tamlihat, B. Aitbenchikh, M. Akbiyik, T. P. A. Åkesson, A. V. Akimov, D. Akiyama, N. N. Akolkar, S. Aktas, G. L. Alberghi, J. Albert, U. Alberti, P. Albicocco, G. L. Albouy, S. Alderweireldt, Z. L. Alegria, M. Aleksa, I. N. Aleksandrov, C. Alexa, T. Alexopoulos, F. Alfonsi, M. Algren, M. Alhroob, B. Ali, H. M. J. Ali, S. Ali, S. W. Alibocus, M. Aliev, G. Alimonti, W. Alkakhi, C. Allaire, B. M. M. Allbrooke, D. R. Allen, J. S. Allen, J. F. Allen, P. P. Allport, A. Aloisio, F. Alonso, C. Alpigiani, Z. M. K. Alsolami, A. Alvarez Fernandez, M. Alves Cardoso, M. G. Alviggi, M. Aly, Y. Amaral Coutinho, A. Ambler, C. Amelung, M. Amerl, C. G. Ames, T. Amezza, D. Amidei, B. Amini, K. Amirie, A. Amirkhanov, S. P. Amor Dos Santos, K. R. Amos, D. Amperiadou, S. An, C. Anastopoulos, T. Andeen, J. K. Anders, A. C. Anderson, A. Andreazza, S. Angelidakis, A. Angerami, A. V. Anisenkov, A. Annovi, C. Antel, E. Antipov, M. Antonelli
A search for resonant structures in the J / ψ + ψ ( 2 S ) mass spectrum is performed using proton-proton collision data at s = 13 TeV , corresponding to an integrated luminosity of 140 fb − 1 , recorded by the ATLAS experiment at the LHC. The decay channels of J / ψ + ψ ( 2 S ) → 4 μ and J / ψ + ψ ( 2 S ) → 4 μ + 2 π are analyzed. An excess near 6.9 GeV is observed in both channels with a combined significance of 8.9 σ . No significant signal is observed near 7.2 GeV, and an upper limit on its yield relative to X ( 6900 ) is provided. A simultaneous fit with the di- J / ψ channel is carried out under assumptions regarding the resonance interferences, yielding a ratio of the partial decay widths between the J / ψ + ψ ( 2 S ) and di- J / ψ channels of 1.08 ± 0.2 0 − 0.17 + 0.40 for the resonance near 6.9 GeV.