Observation of structure in the $J/ψ$-pair mass spectrum
Creators: name: LHCb Collaboration
name: Aaij, R.
name: Beteta, C. Abellán
name: Ackernley, T.
name: Adeva, B.
name: Adinolfi, M.
name: Afsharnia, H.
name: Aidala, C. A.
name: Aiola, S.
name: Ajaltouni, Z.
name: Akar, S.
name: Albrecht, J.
name: Alessio, F.
name: Alexander, M.
name: Albero, A. Alfonso
name: Aliouche, Z.
name: Alkhazov, G.
name: Cartelle, P. Alvarez
name: Alves, A. A.
name: Amato, S.
name: Amhis, Y.
name: An, L.
name: Anderlini, L.
name: Andreassi, G.
name: Andreianov, A.
name: Andreotti, M.
name: Archilli, F.
name: Artamonov, A.
name: Artuso, M.
name: Arzymatov, K.
name: Aslanides, E.
name: Atzeni, M.
name: Audurier, B.
name: Bachmann, S.
name: Bachmayer, M.
name: Back, J. J.
name: Baker, S.
name: Rodriguez, P. Baladron
name: Balagura, V.
name: Baldini, W.
name: Leite, J. Baptista
name: Barlow, R. J.
name: Barsuk, S.
name: Barter, W.
name: Bartolini, M.
name: Baryshnikov, F.
name: Basels, J. M.
name: Bassi, G.
name: Batozskaya, V.
name: Batsukh, B.
name: Battig, A.
name: Bay, A.
name: Becker, M.
name: Bedeschi, F.
name: Bediaga, I.
name: Beiter, A.
name: Belavin, V.
name: Belin, S.
name: Bellee, V.
name: Belous, K.
name: Belyaev, I.
name: Bencivenni, G.
name: Ben-Haim, E.
name: Berezhnoy, A.
name: Bernet, R.
name: Berninghoff, D.
name: Bernstein, H. C.
name: Bertella, C.
name: Bertholet, E.
name: Bertolin, A.
name: Betancourt, C.
name: Betti, F.
name: Bettler, M. O.
name: Bezshyiko, Ia.
name: Bhasin, S.
name: Bhom, J.
name: Bian, L.
name: Bieker, M. S.
name: Bifani, S.
name: Billoir, P.
name: Birch, M.
name: Bishop, F. C. R.
name: Bizzeti, A.
name: Bjørn, M.
name: Blago, M. P.
name: Blake, T.
name: Blanc, F.
name: Blusk, S.
name: Bobulska, D.
name: Bocci, V.
name: Boelhauve, J. A.
name: Garcia, O. Boente
name: Boettcher, T.
name: Boldyrev, A.
name: Bondar, A.
name: Bondar, N.
name: Borghi, S.
name: Borisyak, M.
name: Borsato, M.
name: Borsuk, J. T.
name: Bouchiba, S. A.
name: Bowcock, T. J. V.
name: Boyer, A.
name: Bozzi, C.
name: Bradley, M. J.
name: Braun, S.
name: Rodriguez, A. Brea
name: Brodski, M.
name: Brodzicka, J.
name: Gonzalo, A. Brossa
name: Brundu, D.
name: Buchanan, E.
name: Buonaura, A.
name: Burr, C.
name: Bursche, A.
name: Butkevich, A.
name: Butter, J. S.
name: Buytaert, J.
name: Byczynski, W.
name: Cadeddu, S.
name: Cai, H.
name: Calabrese, R.
name: Diaz, L. Calero
name: Cali, S.
name: Calladine, R.
name: Calvi, M.
name: Gomez, M. Calvo
name: Magalhaes, P. Camargo
name: Camboni, A.
name: Campana, P.
name: Perez, D. H. Campora
name: Quezada, A. F. Campoverde
name: Capelli, S.
name: Capriotti, L.
name: Carbone, A.
name: Carboni, G.
name: Cardinale, R.
name: Cardini, A.
name: Carli, I.
name: Carniti, P.
name: Akiba, K. Carvalho
name: Vidal, A. Casais
name: Casse, G.
name: Cattaneo, M.
name: Cavallero, G.
name: Celani, S.
name: Cenci, R.
name: Cerasoli, J.
name: Chadwick, A. J.
name: Chapman, M. G.
name: Charles, M.
name: Charpentier, Ph.
name: Chatzikonstantinidis, G.
name: Chefdeville, M.
name: Chen, C.
name: Chen, S.
name: Chernov, A.
name: Chitic, S. -G.
name: Chobanova, V.
name: Cholak, S.
name: Chrzaszcz, M.
name: Chubykin, A.
name: Chulikov, V.
name: Ciambrone, P.
name: Cicala, M. F.
name: Vidal, X. Cid
name: Ciezarek, G.
name: Cindolo, F.
name: Clarke, P. E. L.
name: Clemencic, M.
name: Cliff, H. V.
name: Closier, J.
name: Cobbledick, J. L.
name: Coco, V.
name: Coelho, J. A. B.
name: Cogan, J.
name: Cogneras, E.
name: Cojocariu, L.
name: Collins, P.
name: Colombo, T.
name: Contu, A.
name: Cooke, N.
name: Coombs, G.
name: Coquereau, S.
name: Corti, G.
name: Sobral, C. M. Costa
name: Couturier, B.
name: Craik, D. C.
name: Crkovská, J.
name: Torres, M. Cruz
name: Currie, R.
name: Da Silva, C. L.
name: Dall'Occo, E.
name: Dalseno, J.
name: D'Ambrosio, C.
name: Danilina, A.
name: d'Argent, P.
name: Davis, A.
name: Francisco, O. De Aguiar
name: De Bruyn, K.
name: De Capua, S.
name: De Cian, M.
name: De Miranda, J. M.
name: De Paula, L.
name: De Serio, M.
name: De Simone, D.
name: De Simone, P.
name: de Vries, J. A.
name: Dean, C. T.
name: Dean, W.
name: Decamp, D.
name: Del Buono, L.
name: Delaney, B.
name: Dembinski, H. -P.
name: Dendek, A.
name: Denis, X.
name: Denysenko, V.
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name: Di Canto, A.
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name: Dordei, F.
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name: Reis, A. C. dos
name: Douglas, L.
name: Dovbnya, A.
name: Downes, A. G.
name: Dreimanis, K.
name: Dudek, M. W.
name: Dufour, L.
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name: Durham, J. M.
name: Dutta, D.
name: Dziewiecki, M.
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name: Declara, P. Fernandez
name: Prieto, A. Fernandez
name: Ferrari, F.
name: Lopes, L. Ferreira
name: Rodrigues, F. Ferreira
name: Sole, S. Ferreres
name: Ferrillo, M.
name: Ferro-Luzzi, M.
name: Filippov, S.
name: Fini, R. A.
name: Fiorini, M.
name: Firlej, M.
name: Fischer, K. M.
name: Fitzpatrick, C.
name: Fiutowski, T.
name: Fleuret, F.
name: Fontana, M.
name: Fontanelli, F.
name: Forty, R.
name: Lima, V. Franco
name: Sevilla, M. Franco
name: Frank, M.
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Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Using proton-proton collision data at centre-of-mass energies of $\sqrt{s} = 7$, $8$ and $13\mathrm{\,TeV}$ recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of $9\mathrm{\,fb}^{-1}$, the invariant mass spectrum of $J/ψ$ pairs is studied. A narrow structure around $6.9\mathrm{\,GeV/}c^2$ matching the lineshape of a resonance and a broad structure just above twice the $J/ψ$ mass are observed. The deviation of the data from nonresonant $J/ψ$-pair production is above five standard deviations in the mass region between $6.2$ and $7.4\mathrm{\,GeV/}c^2$, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow $X(6900)$ structure are measured assuming a Breit--Wigner lineshape.
description: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-011.html (LHCb public pages)