Volume 254, number 3,4 PHYSICS LETTERS B 24 January 1991 Production of W R and W I bosons from superstring-inspired E 6 models at hadron colliders Fabrizio Aversa, Stefano Bellucci, Mario Greco 1NFN-Laboratori Nazionali di FrascatL P.O. Box 13, 1-00044 Frascati, Italy and Pierre Chiappetta Centre de Physique Th~orique, Luminy, F-13288 MarseiUe, France Received 2 November 1990 We study the production cross sections at future hadron colliders for W R and W I gauge bosons associated with two low-energy groups arising from the breaking of the E6 superstring. Discovery limits are given at LHC and SSC using estimated machine luminosities. Our results are compared with previous studies. I. Introduction and conclusions The possibility of observing new neutral gauge bosons has been recently considered with renewed interest in the perspective of the future hadron colliders LHC and SSC. The phenomenological implications of various classes of models that provide interesting scenarios of new physics beyond the standard SU (3) × SU (2) × U ( 1 ) have been examined in detail, particularly in the framework of superunified gauge theories. The aim of the present paper is to study the production at LHC and SSC energies of the gauge bosons associ- ated to two classes of superstring-inspired E 6 models, and compare the corresponding discovery limits at the expected machine luminosities. The first model is the so-called alternative left-right model (ALRM), where the normal bounds on the WR mass do not apply, as in the standard SU (2) r × SU (2)R × U ( 1 ) e- R model, because of the absence of mixing with the usual WL. This model takes advantage of the ambiguity existing in the assign- ment of fermions in the 27 representation of E 6 and leads to interesting phenomenological consequences at the future multi-TeV colliders, particularly if the exotic matter sector is not very heavy. In the second model the additional SU (2)i subgroup of E 6 which is obtained at relatively low energy has generators that commute with the electric charge [ 1 ]. The corresponding flavour-changing nonhermitian gauge bosons Wb W~ couple the conventional fermions to their exotic partners of the 27 representation of E 6. For both models we only focus on the flavour changing bosons WR and Wi production and our results show the similarity of the expected effects from the two classes of models, with discovery limits up to masses of 1.2- 2.5 TeV, for both hadron colliders. We also compare with previous studies of the production cross sections at SSC and LHC, and in particular we get larger results than those obtained in ref. [ 2 ]. 47 8 0370-2693/91/$ 03.50 © 1991 - Elsevier Science Publishers B.V. ( North-Holland )