Accelerator Neutrinos

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Multivariate searches for single top quark production with the D0 detector

Physical Review D - Particles, Fields, Gravitation and Cosmology 75:9 (2007)

Authors:

VM Abazov, B Abbott, M Abolins, BS Acharya, M Adams, T Adams, M Agelou, JL Agram, SH Ahn, M Ahsan, GD Alexeev, G Alkhazov, A Alton, G Alverson, GA Alves, M Anastasoaie, T Andeen, S Anderson, B Andrieu, MS Anzelc, Y Arnoud, M Arov, A Askew, B Åsman, ACS Assis Jesus, O Atramentov, C Autermann, C Avila, C Ay, F Badaud, A Baden, L Bagby, B Baldin, DV Bandurin, P Banerjee, S Banerjee, E Barberis, P Bargassa, P Baringer, C Barnes, J Barreto, JF Bartlett, U Bassler, D Bauer, A Bean, M Begalli, M Begel, C Belanger-Champagne, A Bellavance, JA Benitez, SB Beri, G Bernardi, R Bernhard, L Berntzon, I Bertram, M Besançon, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, M Binder, C Biscarat, KM Black, I Blackler, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, U Blumenschein, A Boehnlein, O Boeriu, TA Bolton, E Boos, F Borcherding, G Borissov, K Bos, T Bose, A Brandt, R Brock, G Brooijmans, A Bross, D Brown, NJ Buchanan, D Buchholz, M Buehler, V Buescher, V Bunichev, S Burdin, S Burke, TH Burnett, E Busato, CP Buszello, JM Butler, S Calvet, J Cammin, S Caron, W Carvalho, BCK Casey, NM Cason

Abstract:

We present a search for electroweak production of single top quarks in the s-channel (pp̄→tb̄+X) and t-channel (pp̄→tqb̄+X) modes. We have analyzed 230pb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy of s=1.96TeV. No evidence for a single top quark signal is found. We set 95% confidence level upper limits on the production cross sections, based on binned likelihoods formed from a neural network output. The observed (expected) limits are 6.4 pb (4.5 pb) in the s-channel and 5.0 pb (5.8 pb) in the t-channel. © 2007 The American Physical Society.
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Measurement of the Atmospheric Muon Charge Ratio at TeV Energies with MINOS

ArXiv 0705.3815 (2007)
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Measurement of σ(pp̄→Z)•B(Z→ττ) in pp̄ collisions at s=1.96TeV

Physical Review D - Particles, Fields, Gravitation and Cosmology 75:9 (2007)

Authors:

A Abulencia, J Adelman, T Affolder, T Akimoto, MG Albrow, D Ambrose, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, JF Arguin, T Arisawa, A Artikov, W Ashmanskas, A Attal, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, F Bedeschi, S Behari, S Belforte, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, S Budroni, K Burkett, G Busetto, P Bussey, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, S Carillo, D Carlsmith, R Carosi, S Carron, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, I Cho, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, M Ciljak, CI Ciobanu, MA Ciocci

Abstract:

We present a measurement of the inclusive production cross section for Z bosons decaying to tau leptons in pp̄ collisions at s=1.96TeV. We use a channel with one hadronically-decaying and one electronically-decaying tau. This measurement is based on 350pb-1 of CDF Run II data. Using a sample of 504 opposite sign eτ events with a total expected background of 190 events, we obtain σ(pp̄→4Z)•B(Z→ττ)=264±23(stat) ±14(syst)±15(lumi)pb, in agreement with the next-to-next-to- leading order QCD prediction. This is the first CDF cross section measurement using hadronically-decaying taus in Run II. © 2007 The American Physical Society.
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Charge-separated atmospheric neutrino-induced muons in the MINOS far detector

Physical Review D - Particles, Fields, Gravitation and Cosmology 75:9 (2007)

Authors:

P Adamson, C Andreopoulos, KE Arms, R Armstrong, DJ Auty, S Avvakumov, DS Ayres, B Baller, B Barish, PD Barnes, G Barr, WL Barrett, E Beall, BR Becker, A Belias, T Bergfeld, RH Bernstein, D Bhattacharya, M Bishai, A Blake, B Bock, GJ Bock, J Boehm, DJ Boehnlein, D Bogert, PM Border, C Bower, E Buckley-Geer, A Cabrera, JD Chapman, D Cherdack, S Childress, BC Choudhary, JH Cobb, AJ Culling, JK De Jong, A De Santo, M Dierckxsens, MV Diwan, M Dorman, D Drakoulakos, T Durkin, AR Erwin, CO Escobar, JJ Evans, EF Harris, GJ Feldman, TH Fields, R Ford, MV Frohne, HR Gallagher, GA Giurgiu, A Godley, J Gogos, MC Goodman, P Gouffon, R Gran, EW Grashorn, N Grossman, K Grzelak, A Habig, D Harris, PG Harris, J Hartnell, EP Hartouni, R Hatcher, K Heller, A Holin, C Howcroft, J Hylen, D Indurthy, GM Irwin, M Ishitsuka, DE Jaffe, C James, L Jenner, D Jensen, T Joffe-Minor, T Kafka, HJ Kang, SMS Kasahara, MS Kim, G Koizumi, S Kopp, M Kordosky, DJ Koskinen, SK Kotelnikov, A Kreymer, S Kumaratunga, K Lang, A Lebedev, R Lee, J Ling, J Liu, PJ Litchfield, RP Litchfield, P Lucas, WA Mann, A Marchionni, AD Marino

Abstract:

We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector, which has an acceptance for neutrino-induced muons of 6.91×106cm2sr. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios, R, is R=0.65-0.12+0.15(stat)±0.09(syst), a result that is consistent with an oscillation signal. A fit to the data for the oscillation parameters sin 22θ23 and Δm232 excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons into μ- and μ+ in both the data and Monte Carlo events and found the ratio of the total number of μ- to μ+ in both samples. The ratio of those ratios, R^CPT, is a test of CPT conservation. The result R^CPT=0.72-0.18+0.24(stat)-0. 04+0.08(syst) is consistent with CPT conservation. © 2007 The American Physical Society.
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Measurement of the top quark mass in the lepton+jets channel using the ideogram method

Physical Review D - Particles, Fields, Gravitation and Cosmology 75:9 (2007)

Authors:

VM Abazov, B Abbott, M Abolins, BS Acharya, M Adams, T Adams, E Aguilo, SH Ahn, M Ahsan, GD Alexeev, G Alkhazov, A Alton, G Alverson, GA Alves, M Anastasoaie, LS Ancu, T Andeen, S Anderson, B Andrieu, MS Anzelc, Y Arnoud, M Arov, A Askew, B Åsman, ACS Assis Jesus, O Atramentov, C Autermann, C Avila, C Ay, F Badaud, A Baden, L Bagby, B Baldin, DV Bandurin, P Banerjee, S Banerjee, E Barberis, AF Barfuss, P Bargassa, P Baringer, J Barreto, JF Bartlett, U Bassler, D Bauer, S Beale, A Bean, M Begalli, M Begel, C Belanger-Champagne, L Bellantoni, A Bellavance, JA Benitez, SB Beri, G Bernardi, R Bernhard, L Berntzon, I Bertram, M Besançon, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, M Binder, C Biscarat, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, A Boehnlein, D Boline, TA Bolton, G Borissov, K Bos, T Bose, A Brandt, R Brock, G Brooijmans, A Bross, D Brown, NJ Buchanan, D Buchholz, M Buehler, V Buescher, S Burdin, S Burke, TH Burnett, E Busato, CP Buszello, JM Butler, P Calfayan, S Calvet, J Cammin, S Caron, W Carvalho, BCK Casey, NM Cason, H Castilla-Valdez, S Chakrabarti, D Chakraborty

Abstract:

A measurement of the top quark mass using events with one charged lepton, missing transverse energy, and jets in the final state, collected by the D0 detector from pp̄ collisions at s=1.96TeV at the Fermilab Tevatron collider, is presented. A constrained fit is used to fully reconstruct the kinematics of the events. For every event a top quark mass likelihood is calculated taking into account all possible jet assignments and the probability that an event is signal or background. Lifetime-based identification of b jets is employed to enhance the separation between tt̄ signal and background from other physics processes and to improve the assignment of the observed jets to the quarks in the tt̄ hypothesis. We extract a multiplicative jet energy scale (JES) factor in situ, greatly reducing the systematic effect related to the jet energy measurement. In a data sample with an integrated luminosity of 425pb-1, we observe 230 candidate events, with an estimated background of 123 events, and measure mt=173.7±4.4(stat+JES)-2.0+2.1(syst)GeV. This result represents the first application of the ideogram technique to the measurement of the top quark mass in lepton+jets events. © 2007 The American Physical Society.
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