%0 Journal Article %T Search for Higgs boson decays into two new low-mass spin-0 particles in the 4b channel with the ATLAS detector using pp collisions at root s=13 TeV %A ATLAS Collaboration (Aad, G. et al %A Aparisi Pozo, J. A. %A Bailey, A. J. %A Cabrera Urban, S. %A Castillo, F. L. %A Castillo Gimenez, V. %A Cerda Alberich, L. %A Costa, M. J. %A Escobar, C. %A Estrada Pastor, O. %A Ferrer, A. %A Fiorini, L. %A Fullana Torregrosa, E. %A Fuster, J. %A Garcia, C. %A Garcia Navarro, J. E. %A Gonzalez de la Hoz, S. %A Gonzalvo Rodriguez, G. R. %A Guerrero Rojas, J. G. R. %A Higon-Rodriguez, E. %A Lacasta, C. %A Lozano Bahilo, J. J. %A Madaffari, D. %A Mamuzic, J. %A Marti-Garcia, S. %A MiƱano, M. %A Mitsou, V. A. %A Moreno Llacer, M. %A Rodriguez Bosca, S. %A Rodriguez Rodriguez, D. %A Ruiz-Martinez, A. %A Salt, J. %A Santra, A. %A Soldevila, U. %A Sanchez, J. %A Valero, A. %A Valls Ferrer, J. A. %A Vos, M. %J Physical Review D %D 2020 %V 102 %N 11 %I Amer Physical Soc %@ 2470-0010 %G English %F ATLASCollaborationAad_etal2020 %O WOS:000596369400003 %O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4667), last updated on Sat, 16 Jan 2021 21:02:00 +0000 %X This paper describes a search for beyond the Standard Model decays of the Higgs boson into a pair of new spin-0 particles subsequently decaying into b-quark pairs, H -> aa (b (b) over bar)(b (b) over bar), using proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider at center-of-mass energy root s = 13 TeV. This search focuses on the range 15 GeV <= m(a) <= 30 GeV, where the decay products are collimated; it is complementary to a previous search in the same final state targeting the range 20 GeV <= m(a) <= 60 GeV, where the decay products are well separated. A novel strategy for the identification of the a -> b (b) over bar decays is deployed to enhance the efficiency for topologies with small separation angles. The search is performed with 36 fb(-1) of integrated luminosity collected in 2015 and 2016 and sets upper limits on the production cross section of H -> as -> (b (b) over bar)(b (b) over bar), where the Higgs boson is produced in association with a Z boson. %R 10.1103/PhysRevD.102.112006 %U https://arxiv.org/abs/2005.12236 %U https://doi.org/10.1103/PhysRevD.102.112006 %P 112006-28pp