Open Access

Antoni Aduszkiewicz, Evgeny V. Andronov, Tome Antičić, Vadim A. Babkin, Mateusz Baszczyk, S. Bhosale, A. Blondel, M. Bogomilov, Andrei V. Brandin, Alessandro Bravar, Wojciech Bryliński, Janusz Brzychczyk, M. Buryakov, O. Busygina, A. Bzdak, H. Cherif, M. Ćirković, Máté Csanád, J. Cybowska, T. Czopowicz, A. Damyanova, N. Davis, M. Deliyergiyev, Michael Deveaux, A. Dmitriev, W. Dominik, Piotr Dorosz, J. Dumarchez, Ralph Engel, G. A. Feofilov, L. Fields, Zoltán Fodor, A. Garibov, Marek Gaździcki, O. Golosov, V. Golovatyuk, Marina Golubeva, Katarzyna Grebieszkow, Fedor Guber, A. Haesler, Sergey N. Igolkin, Stoyanka Ilieva, Ivashkin Ivashkin, S. R. Johnson, Krešo Kadija, N. Kargin, E. Kashirin, Mirosław Kiełbowicz, Viktar A. Kireyeu, V. Klochkov, Vadim I. Kolesnikov, D. Kolev, A. Korzenev, V. N. Kovalenko, S. Kowalski, M. Koziel, A. Krasnoperov, W. Kucewicz, M. Kuich, Alexander Kurepin, D. Larsen, A. László, Tatiana V. Lazareva, M. Lewicki, K. Łojek, V. V. Lyubushkin, Maja Maćkowiak-Pawłowska, Zbigniew Majka, Bartosz Maksiak, Aleksandr I. Malakhov, A. Marcinek, A. D. Marino, K. Marton, H.-J. Mathes, T. Matulewicz, V. Matveev, Georgy L. Melkumov, A. O. Merzlaya, B. Messerly, Ł. Mik, S. Morozov, Stanislaw Mrówczyński, Y. Nagai, M. Naskręt, Vitalii Ozvenchuk, V. Paolone, Oleg Petukhov, R. Płaneta, P. Podlaski, B. A. Popov, B. Porfy, M. Posiadała-Zezula, D. S. Prokhorova, Damian Pszczel, Szymon Puławski, Jovan Puzović, M. Ravonel, Rainer Arno Ernst Renfordt, Dieter Röhrich, E. Rondio, M. Roth, Brant T. Rumberger, M. Rumyantsev, Anar Rustamov, Maciej Rybczyński, Andrzej Rybicki, A. Sadovsky, K. Schmidt, Ilya Selyuzhenkov, A. Yu. Seryakov, Peter Seyboth, M. Słodkowski, P. Staszel, Grzegorz Stefanek, J. Stepaniak, Michail Nikolaevič Strichanov, Herbert Ströbele, Tatjana Šuša, Arkadiy Taranenko, A. Tefelska, D. Tefelski, V. Tereshchenko, Alberica Toia, R. Tsenov, L. Turko, R. Ulrich, M. Unger, Denis Uzhva, F. F. Valiev, Darko Veberič, V. V. Vechernin, A. Wickremasinghe, Zbigniew Włodarczyk, K. Wojcik, Oskar Wyszyński, E. D. Zimmerman, Robert Zwaska

• A measurement of charged hadron pair correlations in two-dimensional ηφ space is presented. The analysis is based on total 30 million central Be + Be collisions observed in the NA61/SHINE detector at the CERN SPS for incident beam momenta of 19A, 30A, 40A, 75A, and 150A GeV/c. Measurements were carried out for unlike-sign and like-sign charge hadron pairs independently. The C(η, φ) correlation functions were compared with results from a similar analysis on p + p interactions at similar beam momenta per nucleon. General trends of the backto-back correlations are similar in central Be + Be collisions and p + p interactions, but are suppressed in magnitude due to the increased combinatorial background. Predictions from the Epos and UrQMD models are compared to the measurements. Evolution of an enhancement around (η, φ) = (0, 0) with incident energy is observed in central Be + Be collisions. It is not predicted by both models and almost non-existing in proton–proton collisions at the same momentum per nucleon.