Follow-up of multi-messenger alerts with the KM3NeT ARCA and ORCA detectors

The strength of multi-messenger astronomy comes from its capability to increase the significance of a detection through the combined observation of events coincident in space and time. This is particularly valuable for transient events, since the use of a narrow time window can allow a reduction of background of the search. In KM3NeT, we are actively monitoring and analysing a variety of external triggers in real-time, including alerts like IceCube neutrinos, HAWC gamma-ray transients, LIGO-Virgo- KAGRA gravitational waves, SNEWS neutrino alerts, and others. In this contribution, we present the follow-up of various external alerts using the comple- mentary capabilities of the two KM3NeT detectors, ORCA (covering the few GeV to few TeV energy range) and ARCA (ranging from sub-TeV energies up to tens of PeV). Both detectors were collecting high-quality data with partial configurations during the period of the studied alerts, which goes from December 2021 until June 2023

KM3NeT real-time analysis framework

KM3NeT is a deep-sea neutrino observatory under construction at two sites in the Mediterranean Sea. The ARCA telescope (Italy), aims at identifying and studying TeV-PeV astrophysical neutrino sources, while the ORCA telescope (France), aims at studying the intrinsic properties of neutrinos in the few-GeV range. Since they are optimised in complementary energy ranges, both telescopes can be used to do neutrino astronomy from a few MeV to a few PeV, despite of their different primary goals. The KM3NeT observatory takes active part to the real-time multi-messenger searches, which allow to study transient phenomena by combining information from the simultaneous observation of complementary cosmic messengers with different observatories. In this respect, a key component is the real-time distribution of alerts when potentially interesting detections occur, in order to increase the discovery potential of transient sources and refine the localization of poorly localized triggers, such as gravitational waves. The KM3NeT real-time analysis framework is currently reconstructing all ARCA and ORCA events, searching for spatial and temporal coincidences with alerts received from other operating multi-messenger instruments and performing core-collapse supernova analyses. The selection of a sample of interesting events to send alerts to the external multi-messenger community is presently under definition. This contribution deals with the status of the KM3NeT real-time analysis framework and its first results. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).The authors acknowledge the financial support of the funding agencies: SC gratefully acknowledges the support from Università La Sapienza di Roma through the grant ID RM1221816813FFA3; Agence Nationale de la Recherche (contract ANR-15-CE31-0020), Centre National de la Recherche Scientifique (CNRS), Commission Européenne (FEDER fund and Marie Curie Program), LabEx UnivEarthS (ANR-10-LABX-0023 and ANR-18-IDEX-0001), Paris Île-de-France Region, France; Shota Rustaveli National Science Foundation of Georgia (SRNSFG, FR-22-13708), Georgia; The General Secretariat of Research and Innovation (GSRI), Greece Istituto Nazionale di Fisica Nucleare (INFN), Ministero dell’Università e della Ricerca (MIUR), PRIN 2017 program (Grant NAT-NET 2017W4HA7S) Italy; Ministry of Higher Education, Scientific Research and Innovation, Morocco, and the Arab Fund for Economic and Social Development, Kuwait; Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; The National Science Centre, Poland (2021/41/N/ST2/01177); The grant “AstroCeNT: Particle Astrophysics Science and Technology Centre”, carried out within the International Research Agendas programme of the Foundation for Polish Science financed by the European Union under the European Regional Development Fund; National Authority for Scientific Research (ANCS), Romania; GrantsPID2021-124591NB-C41,-C42,-C43fundedbyMCIN/AEI/10.13039/501100011033and,asappropriate, by“ERDF A way of making Europe”, by the “European Union” or by the “European Union NextGenerationEU/PRTR”, Programa de Planes Complementarios I+D+I (refs. ASFAE/2022/023, ASFAE/2022/014), Programa Prometeo (PROMETEO/2020/019) and GenT (refs. CIDEGENT/2018/034, /2019/043, /2020/049. /2021/23) of the Generalitat Valenciana, Junta de Andalucía (ref. SOMM17/6104/UGR, P18-FR-5057), EU: MSC program (ref. 101025085), Programa María Zambrano (Spanish Ministry of Universities, funded by the European Union, NextGenerationEU), Spain; The European Union’s Horizon 2020 Research and Innovation Programme (ChETEC-INFRA- Project no. 101008324)Peer ReviewedMembres del K3MNet: M. Mastrodicasa*, S. Aiello, A. Albert, M. Alshamsi, S. Alves Garre, Z. Aly, A. Ambrosone, F. Ameli, M. André, E. Androutsou, M. Anguita, L. Aphecetche, M. Ardid, S. Ardid, H. Atmani, J. Aublin, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, S. Basegmez du Pree, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, D.M. Benoit, E. Berbee, V. Bertin, S. Biagi, M. Boettcher, D. Bonanno, J. Boumaaza, M. Bouta, M. Bouwhuis, C. Bozza, R.M. Bozza, F. Bretaudeau, R. Bruijn, J. Brunner, R. Bruno, E. Buis, R. Buompane, J. Busto, B. Caiffi, D. Calvo, S. Campion, A. Capone, F. Carenini, V. Carretero, T. Cartraud, P. Castaldi, V. Cecchini, S. Celli, L. Cerisy, M. Chabab, M. Chadolias, A. Chen, S. Cherubini, T. Chiarusi, M. Circella, R. Cocimano, J.A.B. Coelho, A. Coleiro, R. Coniglione, P. Coyle, A. Creusot, G. Cuttone, R. Dallier, Y. Darras, A. De Benedittis, B. De Martino, V. Decoene, R. Del Burgo, I. Del Rosso, U.M. Di Cerbo, L.S. Di Mauro, I. Di Palma, A.F. Díaz, C. Díaz, D. Diego-Tortosa, C. Distefano, A. Domi, C. Donzaud, D. Dornic, M. Dörr, E. Drakopoulou, D. Drouhin, R. Dvornický, T. Eberl, E. Eckerová, A. Eddymaoui, T. van Eeden, M. Eff, D. van Eijk, I. El Bojaddaini, S. El Hedri, A. Enzenhöfer, G. Ferrara, M.D. Filipović, F. Filippini, D. Franciotti, L.A. Fusco, J. Gabriel, S. Gagliardini, T. Gal, J. García M{é}ndez, A. Garcia Soto, C. Gatius Oliver, N. Geißelbrecht, H. Ghaddari, L. Gialanella, B.K. Gibson, E. Giorgio, I. Goos, D. Goupilliere, S.R. Gozzini, R. Gracia, K. Graf, C. Guidi, B. Guillon, M. Gutiérrez, H. van Haren, A. Heijboer, A. Hekalo, L. Hennig, J.J. Hernandez Rey, W. Idrissi Ibnsalih, G. Illuminati, M. de Jong, P. de Jong, B.J. Jung, P. Kalaczyński, O. Kalekin, U.F. Katz, N.R. Khan Chowdhury, A. Khatun, G. Kistauri, C. Kopper, A. Kouchner, V. Kueviakoe, V. Kulikovskiy, R. Kvatadze, M. Labalme, R. Lahmann, G. Larosa, C. Lastoria, A. Lazo, S. Le Stum, G. Lehaut, E. Leonora, N. Lessing, G. Levi, M. Lindsey Clark, F. Longhitano, J. Majumdar, L. Malerba, F. Mamedov, J. Manczak, A. Manfreda, M. Marconi, A. Margiotta, A. Marinelli, C. Markou, L. Martin, J.A. Martínez-Mora, F. Marzaioli, M. Mastrodicasa, S. Mastroianni, S. Miccichè, G. Miele, P. Migliozzi, E. Migneco, M.L. Mitsou, C.M. Mollo, L. Morales-Gallegos, M. Morga, A. Moussa, I. Mozun Mateo, R. Muller, M.R. Musone, M. Musumeci, S. Navas, A. Nayerhoda, C.A. Nicolau, B. Nkosi, B. Ó Fearraigh, V. Oliviero, A. Orlando, E. Oukacha, D. Paesani, J. Palacios González, G. Papalashvili, V. Parisi, E.J. Pastor Gomez, A.M. Păun, G.E. Păvălaš, S. Peña Martínez, M. Perrin-Terrin, J. Perronnel, V. Pestel, R. Pestes, P. Piattelli, C. Poirè, V. Popa, T. Pradier, S. Pulvirenti, G. Quéméner, C.A. Quiroz-Rangel, U. Rahaman, N. Randazzo, R. Randriatoamanana, S. Razzaque, I.C. Rea, D. Real, G. Riccobene, J. Robinson, A. Romanov, A. Saina, F. Salesa Greus, D.F.E. Samtleben, A. Sánchez Losa, S. Sanfilippo, M. Sanguineti, C. Santonastaso, D. Santonocito, P. Sapienza, J. Schnabel, J. Schumann, H.M. Schutte, J. Seneca, N. Sennan, B. Setter, I. Sgura, R. Shanidze, A. Sharma, Y. Shitov, F. Šimkovic, A. Simonelli, A. Sinopoulou, M.V. Smirnov, B. Spisso, M. Spurio, D. Stavropoulos, I. Štekl, M. Taiuti, Y. Tayalati, H. Tedjditi, H. Thiersen, I. Tosta e Melo, B. Trocm{é}, V. Tsourapis, E. Tzamariudaki, A. Vacheret, V. Valsecchi, V. Van Elewyck, G. Vannoye, G. Vasileiadis, F. Vazquez de Sola, C. Verilhac, A. Veutro, S. Viola, D. Vivolo, J. Wilms, E. de Wolf, H. Yepes-Ramirez, G. Zarpapis, S. Zavatarelli, A. Zegarelli, D. Zito, J.D. Zornoza, J. Zúñiga, N. ZywuckaPostprint (published version

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions

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Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson