Accelerator Neutrinos

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Measurements of atmospheric neutrinos and antineutrinos in the MINOS far detector

Physical Review D - Particles, Fields, Gravitation and Cosmology 86:5 (2012)

Authors:

P Adamson, C Backhouse, G Barr, M Bishai, AST Blake, GJ Bock, DJ Boehnlein, D Bogert, SV Cao, JD Chapman, S Childress, JAB Coelho, L Corwin, D Cronin-Hennessy, IZ Danko, JK De Jong, NE Devenish, MV Diwan, CO Escobar, JJ Evans, E Falk, GJ Feldman, MV Frohne, HR Gallagher, RA Gomes, MC Goodman, P Gouffon, N Graf, R Gran, K Grzelak, A Habig, J Hartnell, R Hatcher, A Himmel, A Holin, J Hylen, GM Irwin, Z Isvan, DE Jaffe, C James, D Jensen, T Kafka, SMS Kasahara, G Koizumi, S Kopp, M Kordosky, A Kreymer, K Lang, J Ling, PJ Litchfield, L Loiacono, P Lucas, WA Mann, ML Marshak, M Mathis, N Mayer, MM Medeiros, R Mehdiyev, JR Meier, MD Messier, WH Miller, SR Mishra, J Mitchell, CD Moore, L Mualem, S Mufson, J Musser, D Naples, JK Nelson, HB Newman, RJ Nichol, JA Nowak, WP Oliver, M Orchanian, RB Pahlka, J Paley, RB Patterson, G Pawloski, S Phan-Budd, RK Plunkett, X Qiu, A Radovic, J Ratchford, B Rebel, C Rosenfeld, HA Rubin, MC Sanchez, J Schneps, A Schreckenberger, P Schreiner, R Sharma, A Sousa, B Speakman, M Strait, N Tagg, RL Talaga, J Thomas, MA Thomson, R Toner, D Torretta

Abstract:

This paper reports measurements of atmospheric neutrino and antineutrino interactions in the MINOS Far Detector, based on 2553 live-days (37.9kton-years) of data. A total of 2072 candidate events are observed. These are separated into 905 contained-vertex muons and 466 neutrino-induced rock-muons, both produced by charged-current ν μ and ν ̄μ interactions, and 701 contained-vertex showers, composed mainly of charged-current ν e and ν ̄e interactions and neutral-current interactions. The curvature of muon tracks in the magnetic field of the MINOS Far Detector is used to select separate samples of ν μ and ν ̄μ events. The observed ratio of ν ̄μ to ν μ events is compared with the MonteCarlo (MC) simulation, giving a double ratio of Rν̄/νdata/ Rν̄/νMC=1.03±0.08(stat)±0.08(syst). The ν μ and ν ̄μ data are separated into bins of L/E resolution, based on the reconstructed energy and direction of each event, and a maximum likelihood fit to the observed L/E distributions is used to determine the atmospheric neutrino oscillation parameters. This fit returns 90% confidence limits of |Δm2|=(1.9±0.4)×10 -3eV2 and sin22θ>0.86. The fit is extended to incorporate separate ν μ and ν ̄μ oscillation parameters, returning 90% confidence limits of |Δm2|-|Δm ̄2|=0.6- 0.8+2.4×10 -3eV2 on the difference between the squared-mass splittings for neutrinos and antineutrinos. © 2012 American Physical Society.
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Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 716:1 (2012) 1-29

Authors:

G Aad, T Abajyan, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, O Abdinov, R Aben, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Agustoni, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, T Akdogan, TPA Åkesson, G Akimoto, AV Akimov, MS Alam, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Aliev, G Alimonti, J Alison, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, F Alonso, A Altheimer, B Alvarez Gonzalez, MG Alviggi, K Amako, C Amelung, VV Ammosov, SP Amor Dos Santos, A Amorim, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, ML Andrieux, XS Anduaga, S Angelidakis, P Anger, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, M Aoki, S Aoun, L Aperio Bella

Abstract:

© 2012 CERN. Published by Elsevier B.V. A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb -1 collected at √s = 7 TeV in 2011 and 5.8 fb -1 at √s = 8 TeV in 2012. Individual searches in the channels H → ZZ(*) → 4l, H → γγ and H → WW(*) eνμν in the 8 TeV data are combined with previously published results of searches for H → ZZ (*) , WW (*) , bb and τ + τ - in the 7 TeV data and results from improved analyses of the H → ZZ(*) →4l and H → γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0±0.4 (stat)±0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10 -9 , is compatible with the production and decay of the Standard Model Higgs boson.
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Search for the Standard Model Higgs boson in the H→WW({star operator})→ℓνℓν decay mode with 4.7 fb-1 of ATLAS data at √s=7 TeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 716:1 (2012) 62-81

Authors:

G Aad, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, O Abdinov, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, E Acerbi, E Acerbi, BS Acharya, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Agustoni, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, G Aielli, T Akdogan, TPA Åkesson, G Akimoto, AV Akimov, MS Alam, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Alhroob, M Aliev, G Alimonti, J Alison, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, A Aloisio, R Alon, A Alonso, B Alvarez Gonzalez, MG Alviggi, MG Alviggi, K Amako, C Amelung, VV Ammosov, A Amorim, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, A Andreazza, V Andrei, XS Anduaga, P Anger, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, S Aoun, L Aperio Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce, S Arfaoui, JF Arguin, E Arik

Abstract:

A search for the Standard Model Higgs boson in the H→WW({star operator})→ℓνℓν (ℓ=e, μ) decay mode is presented. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb-1 at a centre-of-mass energy of 7 TeV collected during 2011 with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed. An upper bound is placed on the Higgs boson production cross section as a function of its mass. A Standard Model Higgs boson with mass in the range between 133 GeV and 261 GeV is excluded at 95% confidence level, while the expected exclusion range is from 127 GeV to 233 GeV. © 2012 CERN.
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Search for the Standard Model Higgs boson in the H→WW(⋆)→ℓνℓν decay mode with 4.7 fb-1of ATLAS data at √s=7 TeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 716:1 (2012) 62-81

Authors:

G Aad, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, O Abdinov, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, E Acerbi, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Agustoni, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, T Akdogan, TPA A kesson, G Akimoto, AV Akimov, MS Alam, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Aliev, G Alimonti, J Alison, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, B Alvarez Gonzalez, MG Alviggi, K Amako, C Amelung, VV Ammosov, A Amorim, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, XS Anduaga, P Anger, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, S Aoun, L Aperio Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce

Abstract:

A search for the Standard Model Higgs boson in the H→WW (⋆) →ℓνℓν (ℓ=e, μ) decay mode is presented. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb -1 at a centre-of-mass energy of 7 TeV collected during 2011 with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed. An upper bound is placed on the Higgs boson production cross section as a function of its mass. A Standard Model Higgs boson with mass in the range between 133 GeV and 261 GeV is excluded at 95% confidence level, while the expected exclusion range is from 127 GeV to 233 GeV. © 2012 CERN.
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Search for second generation scalar leptoquarks in pp collisions at √s = 7 TeV with the ATLAS detector

European Physical Journal C 72:9 (2012)

Authors:

G Aad, B Abbott, J Abdallah, SA Khalek, AA Abdelalim, A Abdesselam, O Abdinov, B Abi, M Abolins, OSA Zeid, H Abramowicz, H Abreu, E Acerbi, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, M Aderholz, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, T Akdogan, TPA Åkesson, G Akimoto, AV Akimov, A Akiyama, MS Alam, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Aliev, G Alimonti, J Alison, M Aliyev, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, BA Gonzalez, MG Alviggi, K Amako, P Amaral, C Amelung, VV Ammosov, A Amorim, G Amorós, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, ML Andrieux, XS Anduaga, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, S Aoun, LA Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce, S Arfaoui, JF Arguin, E Arik, M Arik, AJ Armbruster

Abstract:

The results of a search for the production of second generation scalar leptoquarks are presented for final states consisting of either two muons and at least two jets or a muon plus missing transverse momentum and at least two jets. A total of 1.03 fb−1 integrated luminosity of protonproton collision data produced by the Large Hadron Collider at √s = 7 TeV and recorded by the ATLAS detector is used for the search. The event yields in the signal regions are found to be consistent with the Standard Model background expectations. The production of second generation leptoquarks is excluded for a leptoquark mass mLQ < 594 (685) GeV at 95 % confidence level, for a branching ratio of 0.5 (1.0) for leptoquark decay to a muon and a quark.
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