Accelerator Neutrinos

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The HARP detector at the CERN PS

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 571:3 (2007) 527-561

Authors:

MG Catanesi, MT Muciaccia, E Radicioni, S Simone, R Edgecock, M Ellis, S Robbins, FJP Soler, C Gößling, M Mass, S Bunyatov, A Chukanov, O Klimov, I Krasin, A Krasnoperov, D Kustov, B Popov, V Serdiouk, V Tereshchenko, V Carassiti, E Di Capua, F Evangelisti, G Vidal-Sitjes, A Artamonov, P Arce, R Brocard, G Decreuse, B Friend, S Giani, S Gilardoni, P Gorbunov, A Grant, A Grossheim, P Gruber, V Ivanchenko, JC Legrand, A Kayis-Topaksu, J Panman, I Papadopoulos, J Pasternak, E Tcherniaev, I Tsukerman, R van der Vlugt, R Veenhof, C Wiebusch, P Zucchelli, A Blondel, S Borghi, M Campanelli, A Cervera-Villanueva, MC Morone, G Prior, R Schroeter, I Kato, U Gastaldi, GB Mills, JS Graulich, G Grégoire, M Bonesini, F Chignoli, F Ferri, F Paleari, M Kirsanov, V Postoev, A Bagulya, V Grichine, N Polukhina, V Palladino, L Coney, D Schmitz, G Barr, A De Santo, C Pattison, K Zuber, G Barichello, F Bobisut, D Gibin, A Guglielmi, M Laveder, A Menegolli, M Mezzetto, A Pepato, J Dumarchez, S Troquereau, F Vannucci, U Dore, A Iaciofano, M Lobello, F Marinilli, D Orestano, D Panayotov, M Pasquali, F Pastore, A Tonazzo, L Tortora, C Booth, C Buttar, P Hodgson, L Howlett, R Nicholson

Abstract:

HARP is a high-statistics, large solid angle experiment to measure hadron production using proton and pion beams with momenta between 1.5 and 15 GeV/c impinging on many different solid and liquid targets from low to high Z. The experiment, located in the T9 beam of the CERN PS, took data in 2001 and 2002. For the measurement of momenta of produced particles and for the identification of particle types, the experiment includes a large-angle spectrometer, based on a Time Projection Chamber and a system of Resistive Plate Chambers, and a forward spectrometer equipped with a set of large drift chambers, a threshold Cherenkov detector, a time-of-flight wall and an electromagnetic calorimeter. The large angle system uses a solenoidal magnet, while the forward spectrometer is based on a dipole magnet. Redundancy in particle identification has been sought, to enable the cross-calibration of efficiencies and to obtain a few percent overall accuracy in the cross-section measurements. Detector construction, operation and initial physics performances are reported. In addition, the full chain for data recording and analysis, from trigger to the software framework, is described. © 2006 Elsevier B.V. All rights reserved.
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Search for exotic S=-2 baryons in pp̄ collisions at s=1.96TeV

Physical Review D - Particles, Fields, Gravitation and Cosmology 75:3 (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:

A search for a manifestly exotic S=-2 baryon state decaying to Ξ-π-, and its neutral partner decaying to Ξ-π+, has been performed using 220pb-1 of pp̄ collisions at s=1.96TeV collected by the Collider Detector at Fermilab. The Ξ- trajectories were measured in a silicon tracker before their decay, resulting in a sample with low background and excellent position resolution. No evidence was found for S=-2 pentaquark candidates in the invariant mass range of 1600-2100MeV/c2. Upper limits on the product of pentaquark production cross section times its branching fraction to Ξ-π+,-, relative to the cross section of the well-established Ξ(1530) resonance, are presented for neutral and doubly negative candidates with pT>2GeV/c and |y|<1 as a function of pentaquark mass. At 1862MeV/c2, these upper limits for neutral and doubly negative final states were found to be 3.2% and 1.7% at the 90% confidence level, respectively. © 2007 The American Physical Society.
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Search for the pair production of scalar top quarks in the acoplanar charm jet final state in p over(p, ̄) collisions at sqrt(s) = 1.96  TeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 645:2-3 (2007) 119-127

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, P Bargassa, P Baringer, C Barnes, 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, I Blackler, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, U Blumenschein, A Boehnlein, 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

Abstract:

A search for the pair production of scalar top quarks, over(t, ̃), has been performed in 360 pb-1 of data from p over(p, ̄) collisions at a center-of-mass energy of 1.96 TeV, collected by the DØ detector at the Fermilab Tevatron collider. The over(t, ̃) decay mode considered is over(t, ̃) → c over(χ, ̃)10, where over(χ, ̃)10 is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data and standard model expectation are in agreement, and a 95% C.L. exclusion domain in the (mover(t, ̃), mover(χ, ̃)10) plane has been determined, extending the domain excluded by previous experiments. © 2006 Elsevier B.V. All rights reserved.
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Measurement of the ratios of branching fractions B(Bs0→Ds- π+π+π-)/B(B0→D-π+π+π-) and B(Bs0→Ds-π+)/ B(B0→D-π+)

Physical Review Letters 98:6 (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, 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, A Clark

Abstract:

Using 355pb-1 of data collected by the CDF II detector in pp̄ collisions at s=1.96TeV at the Fermilab Tevatron, we study the fully reconstructed hadronic decays B(s)0→D(s)-π+ and B(s)0→D(s)- π+π+π-. We present the first measurement of the ratio of branching fractions B(Bs0→Ds-π+π+π-)/B(B0→D-π+π+π-)=1. 05±0.10(stat)±0.22(syst). We also update our measurement of B(Bs0→Ds-π+)/B(B0→D-π+) to 1.13±0.08(stat)±0. 23(syst), improving the statistical uncertainty by more than a factor of 2. We find B(Bs0→Ds-π+)=[3.8±0.3(stat)±1.3(syst)]×10-3 and B(Bs0→Ds-π+π+π-)=[8.4±0.8(stat)±3.2(syst)] ×10-3. © 2007 The American Physical Society.
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Measurement of the W boson helicity in top quark decays at D0

Physical Review D - Particles, Fields, Gravitation and Cosmology 75:3 (2007)

Authors:

VM Abazov, B Abbott, M Abolins, BS Acharya, M Adams, T Adams, M Agelou, E Aguilo, 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, 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, KM Black, I Blackler, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, U Blumenschein, A Boehnlein, O Boeriu, 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

Abstract:

We present a measurement of the fraction f+ of right-handed W bosons produced in top quark decays, based on a candidate sample of tt̄ events in the +jets and dilepton decay channels corresponding to an integrated luminosity of 370pb-1 collected by the D0 detector at the Fermilab Tevatron pp̄ Collider at s=1.96TeV. We reconstruct the decay angle θ* for each lepton. By comparing the cos θ* distribution from the data with that for the expected background and signal for various values of f+ (where we assume that the fraction of longitudinally-polarized W bosons has the standard model value of 0.70), we find f+=0.056±0.080(stat)±0.057(syst) (f+<0.23 at 95% C.L.), consistent with the standard model prediction of f+=3.6×10-4. © 2007 The American Physical Society.
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