Search for exotic decays of the Higgs boson into long-lived particles in $pp$ collisions at $ \sqrt{s} $ = 13 TeV using displaced vertices in the ATLAS inner detector

• Published in: The journal of high energy physics 2021-07, Vol.11
• Main Authors: Aad, Georges, Abbott, Braden Keim, Abbott, Dale, Abed Abud, Adam, Abeling, Kira, Abhayasinghe, Deshan Kavishka, Abidi, Haider, Abramowicz, Halina, Abreu, Henso, Abulaiti, Yiming, Abusleme Hoffman, A.C., Acharya, Bobby Samir, Achkar, Baida, Adam, Lennart, Adam Bourdarios, Claire, Adamczyk, Leszek, Adamek, Lukas, Adelman, Jahred, Adiguzel, Aytul, Adorni Braccesi Chiassi, Sofia, Adye, Tim, Affolder, A.A., Affolder, Tony, Afik, Yoav, Agapopoulou, Christina, Agaras, Merve Nazlim, Agarwala, Jinky, Aggarwal, Anamika, Agheorghiesei, Catalin, Aguilar Saavedra, Juan Antonio, Ahmad, Ammara, Ahmadov, Faig, Ahmed, Waleed Syed, Ai, Xiaocong, Aielli, Giulio, Akatsuka, Shunichi, Akbiyik, Melike, Akesson, Torsten, Akimov, Andrei, Al Khoury, Konie, Alberghi, Gian Luigi, Albert, Justin, Alconada Verzini, M.J., Alderweireldt, Sara, Aleksa, Martin, Aleksandrov, I.N., Alexa, Calin, Alexopoulos, Theodoros, Alfonsi, Alice, Alfonsi, Fabrizio, Alhroob, Muhammad, Ali, Babar, Ali, Shahzad, Aliev, Malik, Alimonti, Gianluca, Allaire, Corentin, Allbrooke, Benedict, Allport, Philip Patrick, Aloisio, Alberto, Alonso, Francisco, Alpigiani, Cristiano, Alunno Camelia, Elio, Alvarez Estevez, Manuel, Alviggi, Mariagrazia, Do Amaral Coutinho, Yara, Ambler, Alessandro, Ambroz, Luca, Amelung, Christoph, Amidei, Dante, Amor dos Santos, Susana Patricia, Amoroso, Simone, Amrouche, Cherifa Sabrina, Anastopoulos, Christos, Andari, Nansi, Andeen, Timothy Robert, Anders, John Kenneth, Andrean, Stefio Yosse, Andreazza, Attilio, Andrei, Victor, Angelidakis, Stylianos, Angerami, Aaron, Anisenkov, Alexey, Annovi, Alberto, Antel, Claire, Anthony, Matthew Thomas, Antipov, Egor, Antonelli, Mario, Antrim, Daniel Joseph, Anulli, Fabio, Aoki, Masato, Aparisi Pozo, Javier Alberto, Aparo, Marco, Aperio Bella, Ludovica, Aranzabal Barrio, Nordin, Araujo Ferraz, Victor, Arcangeletti, Chiara, Arce, Ayana Tamu, Arena, Eloisa, Arguin, Jean-Francois, Argyropoulos, Spyros
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 1126-6708; 1029-8479
• DOI: 10.1007/JHEP11(2021)229

A novel search for exotic decays of the Higgs boson into pairs of long-lived neutral particles, each decaying into a bottom quark pair, is performed using 139 fb$^{−1}$ of $ \sqrt{s} $ = 13 TeV proton-proton collision data collected with the ATLAS detector at the LHC. Events consistent with the production of a Higgs boson in association with a leptonically decaying Z boson are analysed. Long-lived particle (LLP) decays are reconstructed from inner-detector tracks as displaced vertices with high mass and track multiplicity relative to Standard Model processes. The analysis selection requires the presence of at least two displaced vertices, effectively suppressing Standard Model backgrounds. The residual background contribution is estimated using a data-driven technique. No excess over Standard Model predictions is observed, and upper limits are set on the branching ratio of the Higgs boson to LLPs. Branching ratios above 10% are excluded at 95% confidence level for LLP mean proper lifetimes cτ as small as 4 mm and as large as 100 mm. For LLP masses below 40 GeV, these results represent the most stringent constraint in this lifetime regime.[graphic not available: see fulltext]