A data sample corresponding to 1.23 million hadronic Z decays collected by the ALEPH detector at LEP has been searched for signals of the production of a non-minimal CP-even Higgs boson h in the reaction e+e- --> hZ*. The h decay modes considered were: those of the minimal standard model Higgs boson, with modified branching ratios; decays into a pair of CP-odd Higgs bosons A; and decays into invisible final states. Only one event was found, a very acoplanar e+e- pair which could originate from the standard model background process e+e- --> e+e- nu (nu) over bar. Upper limits for the cross-section of the reaction e+e- --> hZ* have been derived as a function of m(h), the mass of the Higgs boson h. In the case of invisible decays, the 95% CL lower limit on m(h) is 65 GeV/c(2) for a production cross-section equal to that of a minimal standard model Higgs boson. When combined with previous ALEPH results on the reaction e+e- --> hA, these cross-section upper limits exclude a domain in the (m(h), M(A)) plane of the MSSM such that, if invisible h and A decays can be neglected, 95% CL lower limits of 44 and 21 GeV/c(2) result for m(h) and m(A), respectively, independent of the other parameters of the model.

Search For A Non-minimal Higgs boson Produced In the Reaction e+e- -> hZ*

G. BATIGNANI;CIOCCI, MARIA AGNESE;FERRANTE, ISIDORO;FIDECARO, FRANCESCO;F. FORTI;MESSINEO, ALBERTO MARIA;G. RIZZO;TONELLI, GUIDO EMILIO;G. TRIGGIANI;
1993-01-01

Abstract

A data sample corresponding to 1.23 million hadronic Z decays collected by the ALEPH detector at LEP has been searched for signals of the production of a non-minimal CP-even Higgs boson h in the reaction e+e- --> hZ*. The h decay modes considered were: those of the minimal standard model Higgs boson, with modified branching ratios; decays into a pair of CP-odd Higgs bosons A; and decays into invisible final states. Only one event was found, a very acoplanar e+e- pair which could originate from the standard model background process e+e- --> e+e- nu (nu) over bar. Upper limits for the cross-section of the reaction e+e- --> hZ* have been derived as a function of m(h), the mass of the Higgs boson h. In the case of invisible decays, the 95% CL lower limit on m(h) is 65 GeV/c(2) for a production cross-section equal to that of a minimal standard model Higgs boson. When combined with previous ALEPH results on the reaction e+e- --> hA, these cross-section upper limits exclude a domain in the (m(h), M(A)) plane of the MSSM such that, if invisible h and A decays can be neglected, 95% CL lower limits of 44 and 21 GeV/c(2) result for m(h) and m(A), respectively, independent of the other parameters of the model.
1993
Buskulic, D.; Debonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J. P.; Minard, M. N.; Pietrzyk, B.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/828815
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