Search for heavy neutrinos with the T2K near detector ND280

Physical Review D American Physical Society 100:5 (2019) 052006

Authors:

K Abe, R Akutsu, A Ali, C Andreopoulos, L Anthony, M Antonova, S Aoki, A Ariga, Y Ashida, Y Awataguchi, Y Azuma, S Ban, M Barbi, GJ Barker, Giles Barr, C Barry, M Batkiewicz-Kwasniak, F Bench, V Berardi, S Berkman, RM Berner, L Berns, S Bhadra, S Bienstock, A Blondel, S Bolognesi, B Bourguille, SB Boyd, D Brailsford, A Bravar, C Bronner, MB Avanzini, J Calcutt, T Campbell, S Cao, SL Cartwright, Catanesi, A Cervera, A Chappell, C Checchia, D Cherdack, N Chikuma, G Christodoulou, J Coleman, G Collazuol, D Coplowe, A Cudd, A Dabrowska, GD Rosa, T Dealtry

Abstract:

This paper reports on the search for heavy neutrinos with masses in the range $140 < M_N < 493$ MeV/c$^2$ using the off-axis near detector ND280 of the T2K experiment. These particles can be produced from kaon decays in the standard neutrino beam and then subsequently decay in ND280. The decay modes under consideration are $N \to \ell^{\pm}_{\alpha} \pi^{\mp}$ and $N \to \ell^+_{\alpha} \ell^-_{\beta} \nu (\bar\nu)$ ($\alpha,\beta=e,\mu$). A search for such events has been made using the Time Projection Chambers of ND280, where the background has been reduced to less than two events in the current dataset in all channels. No excess has been observed in the signal region. A combined Bayesian statistical approach has been applied to extract upper limits on the mixing elements of heavy neutrinos to electron-, muon- and tau- flavoured currents ($U_e^2$, $U_{\mu}^2$, $U_{\tau}^2$) as a function of the heavy neutrino mass, e.g. $U_e^2 < 10^{-9}$ at $90\%$ C.L. for a mass of $390$ MeV/c$^2$. These constraints are competitive with previous experiments.

Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb(-1) of root s = 13 TeV pp collision data with the ATLAS detector (vol 09, 084, 2017)

JOURNAL OF HIGH ENERGY PHYSICS 2019:8 (2019) ARTN 121

Authors:

M Aaboud, G Aad, B Abbott, Dc Abbott, O Abdinov, B Abeloos, Dk Abhayasinghe, Sh Abidi, Os AbouZeid, Nl Abraham, H Abramowicz, H Abreu, Y Abulaiti, Bs Acharya, S Adachi, L Adam, L Adamczyk, L Adamek, J Adelman, M Adersberger, A Adiguzel, T Adye, Aa Affolder, Y Afik, C Agheorghiesei, Ja Aguilar-Saavedra, F Ahmadov, G Aielli, S Akatsuka, Tpa Akesson, E Akilli, Av Akimov, Gl Alberghi, J Albert, P Albicocco, Mj Alconada Verzini, S Alderweireldt, M Aleksa, In Aleksandrov, C Alexa, D Alexandre, T Alexopoulos, M Alhroob, B Ali, G Alimonti, J Alison, Sp Alkire, C Allaire, Bmm Allbrooke, Bw Allen

Abstract:

© 2019, The Author(s). One correction is made to the figure 4e of the paper.

Search for chargino and neutralino production in final states with a Higgs boson and missing transverse momentum at s√=13 TeV with the ATLAS detector

Physical Review D American Physical Society 100:1 (2019) 012006

Authors:

M Aaboud, G Aad, B Abbott, Luca Ambroz, Giacomo Artoni, Moritz Backes, Alan Barr, Lydia Beresford, Daniela Bortoletto, JTP Burr, Amanda Cooper-Sarkar, James Frost, Gabriel E Gallardo, Elizabeth Gallas, F Giuli, Claire Gwenlan, CP Hays, Todd Huffman, Cigdem Issever, JKK Liu, Luigi Marchese, Koichi Nagai, Michael Nelson, Richard Nickerson, Nurfikri Norjoharuddeen

Abstract:

A search is conducted for the electroweak pair production of a chargino and a neutralino pp → χ˜ 1 χ˜ 0 2, where the chargino decays into the lightest neutralino and a W boson, χ˜ 1 → χ˜ 0 1W, while the neutralino decays into the lightest neutralino and a Standard Model-like 125 GeV Higgs boson, χ˜ 0 2 → χ˜ 0 1h. Fully hadronic, semileptonic, diphoton, and multilepton (electrons, muons) final states with missing transverse momentum are considered in this search. Higgs bosons in the final state are identified by either two jets originating from bottom quarks (h → bb¯), two photons (h → γγ), or leptons from the decay modes h → WW, h → ZZ or h → ττ. The analysis is based on 36.1 fb−1 of ffiffi s p ¼ 13 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider. Observations are consistent with the Standard Model expectations, and 95% confidence-level limits of up to 680 GeV in χ˜ 1 =χ˜ 0 2 mass are set in the context of a simplified supersymmetric model.

Search for dark matter with a 231-day exposure of liquid argon using DEAP-3600 at SNOLAB

Physical Review D American Physical Society (APS) 100:2 (2019) 022004

Authors:

R Ajaj, P-A Amaudruz, GR Araujo, M Baldwin, M Batygov, B Beltran, CE Bina, J Bonatt, MG Boulay, B Broerman, JF Bueno, PM Burghardt, A Butcher, B Cai, S Cavuoti, M Chen, Y Chen, BT Cleveland, D Cranshaw, K Dering, J DiGioseffo, L Doria, FA Duncan, M Dunford, A Erlandson, N Fatemighomi, G Fiorillo, S Florian, A Flower, RJ Ford, R Gagnon, D Gallacher, EA Garcés, S Garg, P Giampa, D Goeldi, VV Golovko, P Gorel, K Graham, DR Grant, AL Hallin, M Hamstra, PJ Harvey, C Hearns, A Joy, CJ Jillings, O Kamaev, G Kaur, A Kemp, I Kochanek, M Kuźniak, S Langrock, F La Zia, B Lehnert, X Li, J Lidgard, T Lindner, O Litvinov, J Lock, G Longo, P Majewski, AB McDonald, T McElroy, T McGinn, JB McLaughlin, R Mehdiyev, C Mielnichuk, J Monroe, P Nadeau, C Nantais, C Ng, AJ Noble, E O’Dwyer, C Ouellet, P Pasuthip, SJM Peeters, M-C Piro, TR Pollmann, ET Rand, C Rethmeier, F Retière, N Seeburn, K Singhrao, P Skensved, B Smith, NJT Smith, T Sonley, J Soukup, R Stainforth, C Stone, V Strickland, B Sur, J Tang, E Vázquez-Jáuregui, L Veloce, S Viel, J Walding, M Waqar, M Ward, S Westerdale, J Willis, A Zuñiga-Reyes

Search for neutral-current induced single photon production at the ND280 near detector in T2K

Journal of Physics G: Nuclear and Particle Physics IOP Publishing 46:8 (2019) 08LT01

Authors:

K Abe, R Akutsu, A Ali, C Andreopoulos, L Anthony, M Antonova, S Aoki, A Ariga, Y Ashida, Y Awataguchi, Y Azuma, S Ban, M Barbi, GJ Barker, Giles Barr, C Barry, M Batkiewicz-Kwasniak, F Bench, V Berardi, S Berkman, RM Berner, L Berns, S Bhadra, S Bienstock, A Blondel

Abstract:

All rights reserved. Neutrino neutral-current (NC) induced single photon production is a subleading order process for accelerator-based neutrino beam experiments including T2K. It is, however, an important process to understand because it is a background for electron (anti)neutrino appearance oscillation experiments. Here, we performed the first search of this process below 1 GeV using the finegrained detector at the T2K ND280 off-axis near detector. By reconstructing single photon kinematics from electron positron pairs, we achieved 95% pure gamma ray sample from 5.738 1020 protons-on-targets neutrino mode data. We do not find positive evidence of NC induced single photon production in this sample. We set the model-dependent upper limit on the cross-section for this process, at 0.114 10-38 cm2 (90% C.L.) per nucleon, using the J-PARC off-axis neutrino beam with an average energy of .En. ~ 0.6 GeV. This is the first limit on this process below 1.GeV which is important for current and future oscillation experiments looking for electron neutrino appearance oscillation signals.