Search for single top quark production in ep collisions at HERA

被引：49

作者：

Aktas, A

Andreev, V

Anthonis, T

Asmone, A

Babaev, A

Backovic, S

Bähr, J

Baranov, P

Barrelet, E

Bartel, W

Baumgartner, S

Becker, J

Beckingham, M

Behnke, O

Behrendt, O

Belousov, A

Berger, C

Berndt, T

Bizot, JC

Böhme, J

Boenig, MO

Boudry, V

Bracinik, J

Braunschweig, W

Brisson, V

Bröker, HB

Brown, DP

Bruncko, D

Büsser, FW

Bunyatyan, A

Buschhorn, G

Bystritskaya, L

Campbell, AJ

Caron, S

Cassol-Brunner, F

Chekelian, V

Clarke, D

Collard, C

Contreras, JG

Coppens, YR

Coughlan, JA

Cousinou, MC

Cox, BE

Cozzika, G

Cvach, J

Dainton, JB

Dau, WD

Daum, K

Delcourt, B

Delerue, N

机构：

[1] DESY, D-2000 Hamburg, Germany

[2] Rhein Westfal TH Aachen, Inst Phys 1, D-5100 Aachen, Germany

[3] Rhein Westfal TH Aachen, Inst Phys 3, D-5100 Aachen, Germany

[4] Univ Birmingham, Sch Phys & Space Res, Birmingham B15 2TT, W Midlands, England

[5] ULB VUB, Interuniv Inst High Energies, Brussels, Belgium

[6] Univ Antwerp, B-2020 Antwerp, Belgium

[7] Rutherford Appleton Lab, Chilton, Didcot, England

[8] Inst Nucl Phys, Krakow, Poland

[9] Univ Dortmund, Inst Phys, D-4600 Dortmund, Germany

[10] Joint Inst Nucl Res, Dubna, Russia

[11] CEA, DSM, DAPNIA, CE Saclay, Gif Sur Yvette, France

[12] Univ Hamburg, Inst Expt Phys, Hamburg, Germany

[13] Max Planck Inst Kernphys, D-69117 Heidelberg, Germany

[14] Heidelberg Univ, Inst Phys, D-6900 Heidelberg, Germany

[15] Heidelberg Univ, Kirchhoff Inst Phys, Heidelberg, Germany

[16] Univ Kiel, Inst Expt & Angew Phys, Kiel, Germany

[17] Slovak Acad Sci, Inst Expt Phys, Kosice 04353, Slovakia

[18] Univ Lancaster, Sch Phys & Chem, Lancaster, England

[19] Univ Liverpool, Dept Phys, Liverpool L69 3BX, Merseyside, England

[20] Queen Mary Univ London, London E1 4NS, England

[21] Lund Univ, Dept Phys, Lund, Sweden

[22] Univ Manchester, Dept Phys, Manchester M13 9PL, Lancs, England

[23] Univ Mediterranee, CNRS, IN2P3, CPPM, Marseille, France

[24] Inst Theoret & Expt Phys, Moscow 117259, Russia

[25] Max Planck Inst Phys & Astrophys, D-80805 Munich, Germany

[26] Univ Paris 11, CNRS, IN2P3, LAL, Orsay, France

[27] Ecole Polytech, CNRS, IN2P3, LPNHE, F-91128 Palaiseau, France

[28] Univ Paris 06, LPNHE, Paris, France

[29] Univ Paris 07, CNRS, IN2P3, Paris, France

[30] Acad Sci Czech Republ, Inst Phys, Prague, Czech Republic

[31] Charles Univ Prague, Fac Math & Phys, Prague, Czech Republic

[32] Univ Roma Tre, Dipartimento Fis, Rome, Italy

[33] INFN Roma 3, Rome, Italy

[34] Paul Scherrer Inst, Villigen, Switzerland

[35] Berg Univ Wuppertal, Fachbereich Phys, Wuppertal, Germany

[36] Yerevan Phys Inst, Yerevan 375036, Armenia

[37] DESY, Zeuthen, Germany

[38] ETH, Inst Teilchenphys, Zurich, Switzerland

[39] Univ Zurich, Inst Phys, Zurich, Switzerland

[40] Natl Tech Univ Athens, Dept Phys, GR-15773 Athens, Greece

[41] Berg Univ Wuppertal, Inst Expt Kernphys, Wuppertal, Germany

[42] CINVESTAV, Dept Fis Ap, Merida, Yucatan, Mexico

[43] Safarik Univ, Kosice, Slovakia

[44] CERN, Geneva, Switzerland

[45] CINVESTAV, Dept Fis, Mexico City 14000, DF, Mexico

来源：

EUROPEAN PHYSICAL JOURNAL C | 2004年 / 33卷 / 01期

关键词：

D O I：

10.1140/epjc/s2003-01588-2

中图分类号：

O412 [相对论、场论]; O572.2 [粒子物理学];

学科分类号：

摘要：

A search for single top quark production is performed in e(+/-) pcollisions at HERA. The search exploits data corresponding to an integrated luminosity of 118.3 pb(-1). A model for the anomalous production of top quarks in a flavour changing neutral current process involving a tugamma coupling is investigated. Decays of top quarks into a b quark and a W boson are considered in the leptonic and the hadronic decay channels of the W. Both a cut-based analysis and a multivariate likelihood analysis are performed to discriminate anomalous top quark production from Standard Model background processes. In the leptonic channel, 5 events are found while 1.31 +/- 0.22 events are expected from the Standard Model background. In the hadronic channel, no excess above the expectation for Standard Model processes is found. These observations lead to a cross section (ep --> e t X) = 0.29(-0.14)(+0.15) pb at roots = 319 GeV. Alternatively, assuming that the observed events are due to a statistical fluctuation, upper limits of 0.55 pb on the anomalous top production cross section and of 0.27 on the tugamma coupling k(tugamma) are established at the 95% confidence level.

引用

页码：9 / 22

页数：14

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