Flechl, Martin
ZEUS
W Production
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W production and the search for events with an isolated high-energy lepton and missing transverse momentum at HERA.

The ZEUS collaboration Breitweg, J. ; Chekanov, S. ; Derrick, M. ; et al.
Phys.Lett.B 471 (2000) 411-428, 2000.
Inspire Record 503787 DOI 10.17182/hepdata.44142

A search for the leptonic decays of W bosons produced in the reaction e^+ p\to e^+ W^\pm X at a centre-of-mass energy of 300 GeV has been performed with the ZEUS detector at HERA using an integrated luminosity of 47.7 pb^-1 . Three events consistent with W\to e\nu decay are found, giving a cross section of 0.9 +1.0 -0.7 \pm 0.2 pb, in good agreement with the Standard Model prediction. The corresponding 95% C.L. upper limit on the cross section is 3.3 pb. A search for the decay W\to \mu\nu has a smaller selection efficiency and yields no candidate events. Limits on the cross section for W production with large hadronic transverse momentum have been obtained. A search for high-transverse-momentum isolated tracks in events with large missing transverse momentum yields results in good agreement with Standard Model expectations, in contrast to a recent report by the H1 collaboration of the observation of an excess of such events.

2 data tables
Table 1

Measured cross section from three events.

Table 2

95 PCT CONFIDENCE UPPER LIMIT TO THE PROCESS.


A Search for excited fermions in electron - proton collisions at HERA

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Z.Phys.C 65 (1995) 627-648, 1995.
Inspire Record 378836 DOI 10.17182/hepdata.45049

A search for excited states of the standard model fermions was performed using the ZEUS detector at the HERA electron-proton collider, operating at a centre of mass energy of 296 GeV. In a sample corresponding to an integrated luminosity of 0.55 pb−1, no evidence was found for any resonant state decaying into final states composed of a fermion and a gauge boson. Limits on the coupling strength times branching ratio of excited fermions are presented for masses between 50 GeV and 250 GeV, extending previous search regions significantly.

1 data table
Table 1

The cross sections times branching ratio.


Search for excited electrons using the ZEUS detector

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 316 (1993) 207-218, 1993.
Inspire Record 355574 DOI 10.17182/hepdata.45106

This paper reports a search for excited electrons at the HERA electron-proton collider. In a sample corresponding to an integrated luminosity of 26 nb − , no evidence was found for any resonant state decaying into e − γ , ν W − or e − Z 0 . Limits on the coupling strength of an excited electron have been determined for masses between 45 and 225 GeV. This study also reports the observation of the wide-angle e γ Compton scattering process.

1 data table
Table 1

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