LHCb CollaborationAaij, R.Adeva, B.Adinolfi, M.Affolder, A.Ajaltouni, Z.Akar, S.Albrecht, J.Alessio, F.Alexander, M.Ali, S.Alkhazov, G.Cartelle, P. AlvarezAmato, S.Amerio, S.Amhis, Y.An, L.Anderlini, L.Anderson, J.Andreotti, M.Andrews, J. E.Appleby, R. B.Gutierrez, O. AquinesArchilli, F.Artamonov, A.Artuso, M.Aslanides, E.Auriemma, G.Baalouch, M.Bachmann, S.Back, J. J.Badalov, A.Baesso, C.Baldini, W.Barlow, R. J.Barschel, C.Barsuk, S.Barter, W.Batozskaya, V.Battista, V.Bay, A.Beaucourt, L.Beddow, J.Bedeschi, F.Bediaga, I.Bel, L. J.Belyaev, I.Ben-Haim, E.Bencivenni, G.Benson, S.Benton, J.Berezhnoy, A.Bernet, R.Bertolin, A.Bettler, M. -OVan Beuzekom, M.Bien, A.Bifani, S.Bird, T.Bizzeti, A.Blake, T.Blanc, F.Blouw, J.Blusk, S.Bocci, V.Bondar, A.Bondar, N.Bonivento, W.Borghi, S.Borsato, M.Bowcock, T. J. V.Bowen, E.Bozzi, C.Braun, S.Brett, D.Britsch, M.Britton, T.Brodzicka, J.Brook, N. H.Bursche, A.Buytaert, J.Cadeddu, S.Calabrese, R.Calvi, M.Calvo Gomez, M.Campana, P.Perez, D. CamporaCapriotti, L.Carbone, A.Carboni, G.Cardinale, R.Cardini, A.Carniti, R.Carson, L.Carvalho Akiba, K.Casanova Mohr, R.Can, G.Cassina, L.Garcia, L. CastilloCattaneo, M.Cauet, Ch.Cavallero, G.Cenci, R.Charles, M.Charpentier, Ph.Chefdeville, M.Chen, S.Cheung, S. -F.Chiapolini, N.Chrzaszcz, M.Vidal, X. CidCiezarek, G.Clarke, P. E. L.Clemencic, M.Cliff, H. V.Closier, J.Coco, V.Cogan, J.Cogneras, E.Cogoni, V.Cojocariu, L.Collazuol, G.Collins, P.Comerma-Montells, A.Contu, A.Cook, A.Coombes, M.Coquereau, S.Corti, G.Corvo, M.Counts, I.Couturier, B.Cowan, G. A.Craik, D. C.Crocombe, A. C.Cruz Torres, M.Cunliffe, S.Currie, R.D'Ambrosio, C.Dalseno, J.David, P. N. Y.Davis, A.De Bruyn, K.De Capua, S.De Cian, M.De Miranda, J. M.De Paula, L.De Silva, W.De Simone, P.Dean, C. -T.Decamp, D.Deckenhoff, M.Del Buono, L.Deleage, N.Derkach, D.Deschamps, O.Dettori, F.Dey, B.Di Canto, A.Di Ruscio, F.Dijkstra, H.Donleavy, S.Dordei, F.Dorigo, M.Dosil Suarez, A.Dossett, D.Dovbnya, A.Dreimanis, K.Dujany, G.Dupertuis, F.Durante, P.Dzhelyadin, R.Dziurda, A.Dzyuba, A.Easo, S.Egede, U.Egorychev, V.Eidelman, S.Eisenhardt, S.Eitschberger, U.Ekelhof, R.Eklund, L.El Rifai, I.Elsasser, Ch.Ely, S.Esen, S.Evans, H. M.Evans, T.Falabella, A.Faerber, C.Farinelli, C.Farley, N.Farry, S.Fay, R.Ferguson, D.Albor, V. FernandezFerrari, F.Ferreira Rodrigues, F.Ferro-Luzzi, M.Filippov, S.Fiore, M.Fiorini, M.Firlej, M.Fitzpatrick, C.Fiutowski, T.Fol, P.Fontana, M.Fontanelli, F.Forty, R.Francisco, O.Frank, M.Frei, C.Frosini, M.Fu, J.Furfaro, E.Gallas Torreira, A.Galli, D.Gallorini, S.Gambetta, S.Gandelman, M.Gandini, P.Gao, Y.Garcia Pardinas, J.Garofoli, J.Tico, J. 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M.Karodia, S.Kelsey, M.Kenyon, I. R.Kenzie, M.Ketel, T.Khanji, B.Khurewathanakul, C.Klaver, S.Klimaszewski, K.Kochebina, O.Kolpin, M.Komarov, I.Koopman, R. F.Koppenburg, P.Korolev, M.Kravchuk, L.Kreplin, K.Kreps, M.Krocker, G.Krokovny, P.Kruse, E.Kucewicz, W.Kucharczyk, M.Kudryavtsev, V.Kurek, K.Kvaratskheliya, T.La Thi, V. N.Lacarrere, D.Lafferty, G.Lai, A.Lambert, D.Lambert, R. W.Lanfranchi, G.Langenbruch, C.Langhans, B.Latham, T.Lazzeroni, C.Le Gac, R.Van Leerdam, J.Lees, J. -P.Lefevre, R.Leflat, A.Lefrancois, J.Leroy, O.Lesiak, T.Leverington, B.Li, Y.Likhomanenko, T.Liles, M.Lindner, R.Linn, C.Lionetto, F.Liu, B.Lohn, S.Longstaff, I.Lopes, J. H.Lowdon, P.Lucchesi, D.Luo, H.Lupato, A.Luppi, E.Lupton, O.Machefert, F.Maciuc, F.Maev, O.Malde, S.Malinin, A.Manca, G.Mancinelli, G.Manning, P.Mapelli, A.Maratas, J.Marchand, J. F.Marconi, U.Mann Benito, C.Marino, P.Maerki, R.Marks, J.Martellotti, G.Martinelli, M.Santos, D. MartinezMartinez Vidal, F.Martins Tostes, D.Massafferri, A.Matev, R.Mathad, A.Mathe, Z.Matteuzzi, C.Mauri, A.Maurin, B.Mazurov, A.Mccann, M.Mccarthy, J.Mcnab, A.Mcnulty, R.Meadows, B.Meier, F.Meissner, M.Merk, M.Milanes, D. A.Minard, M. -N.Mitzel, D. S.Rodriguez, J. MolinaMonteil, S.Morandin, M.Morawski, P.Morda, A.Morello, M. J.Moron, J.Morris, A. -B.Mountain, R.Muheim, F.Mueller, K.Mussini, M.Muster, B.Naik, P.Nakada, T.Nandakumar, R.Nasteva, I.Needham, M.Neri, N.Neubert, S.Neufeld, N.Neuner, M.Nguyen, A. D.Nguyen, T. D.Nguyen-Mau, C.Niess, V.Niet, R.Nikitin, N.Nikodem, T.Novoselov, A.O'Hanlon, D. P.Oblakowska-Mucha, A.Obraztsov, V.Ogilvy, S.Okhrimenko, O.Oldeman, R.Onderwater, C. J. G.Osorio Rodrigues, B.Otalora Goicochea, J. M.Otto, A.Owen, P.Oyanguren, A.Palano, A.Palombo, F.Palutan, M.Panman, J.Papanestis, A.Pappagallo, M.Pappalardo, L. L.Parkes, C.Passaleva, G.Patel, G. 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P.Soomro, F.Souza, D.Souza De Paula, B.Spaan, B.Spradlin, P.Sridharan, S.Stagni, F.Stahl, M.Stahl, S.Steinkamp, O.Stenyakin, O.Sterpka, F.Stevenson, S.Stoica, S.Stone, S.Storaci, B.Stracka, S.Straticiuc, M.Straumann, U.Stroili, R.Sun, L.Sutcliffe, W.Swientek, K.Swientek, S.Syropoulos, V.Szczekowski, M.Szczypka, R.Szumlak, T.T'Jampens, S.Teklishyn, M.Tellarini, G.Teubert, R.Thomas, C.Thomas, E.Van Tilburg, J.Tisserand, V.Tobin, M.Todd, J.Tolk, S.Tomassetti, L.Tonelli, D.Topp-Joergensen, S.Torr, N.Tournefier, E.Tourneur, S.Trabelsi, K.Tran, M. T.Tresch, M.Trisovic, A.Tsaregorodtsev, A.Tsopelas, P.Tuning, N.Ukleja, A.Ustyuzhanin, A.Uwer, U.Vacca, C.Vagnoni, V.Valenti, G.Vallier, A.Gomez, R. VazquezVazquez Regueiro, P.Vazquez Sierra, C.Vecchi, S.Velthuis, J. J.Veltri, M.Veneziano, G.Vesterinen, M.Viana Barbosa, J. V.Viaud, B.Vieira, D.Vieites Diaz, M.Vilasis-Cardona, X.Vollhardt, A.Volyanskyy, D.Voong, D.Vorobyev, A.Vorobyev, V.Voss, C.De Vries, J. A.Waldi, R.Wallace, C.Wallace, R.Walsh, J.Wandernoth, S.Wang, J.Ward, D. R.Watson, N. K.Websdale, D.Weiden, A.Whitehead, M.Wiedner, D.Wilkinson, G.Wilkinson, M.Williams, M.Williams, M. P.Williams, M.Wilson, F. F.Wimberley, J.Wishahi, J.Wislicki, W.Witek, M.Wormser, G.Wotton, S. A.Wright, S.Wyllie, K.Xie, Y.Xu, Z.Yang, Z.Yuan, X.Yushchenko, O.Zangoli, M.Zavertyaev, M.Zhang, L.Zhang, Y.Zhelezov, A.Zhokhov, A.Zhong, L.2015-09-282015-09-282015-09-28201510.1016/j.physletb.2015.06.027https://infoscience.epfl.ch/handle/20.500.14299/118899WOS:000358624800076Proton-proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb(-1), are analysed to search for the charmless B-0 -> rho(0)rho(0) decay. More than 600 B-0 -> (pi(+)pi(-))(pi(+)pi(-)) signal decays are selected and used to perform an amplitude, analysis, under the assumption of no CP violation in the decay, from which the B-0 -> rho(0)rho(0) decay is observed for the first time with 7.1 standard deviations significance. The fraction of B-0 -> rho(0)rho(0) decays yielding a longitudinally polarised final state is measured to be f(L) = 0.745(-0.058)(+0.048)(stat) +/- 0.034(syst). The B-0 -> rho(0)rho(0) branching fraction, using the B-0 -> phi K*(892)(0) decay as reference, is also reported as B(B-0 -> rho(0)rho(0)) = (0.94 +/- 0.17(stat) +/- 0.09(syst) +/- 0.06(BF)) x 10(-6). (C) 2015 CERN for the benefit of the LHCb Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY licensetext::journal::journal article::research article