Search for Light Supersymmetric Baryons

Abstract

We have searched for the production and decay of light supersymmetric baryons produced in 800 GeV͞c proton copper interactions in a charged hyperon beam experiment. We observe no evidence for the decays R 1 ͑uudg͒ ! S 0 ͑udsg͒p 1 and X 2 ͑ssdg͒ ! S 0 ͑udsg͒p 2 in the parent mass and lifetime ranges of 1700 2500 MeV͞c 2 and 50 -500 ps. Production upper limits for R 1 at x F 0.47, P t 1.4 GeV͞c 2 and X 2 at x F 0.48, P t 0.65 GeV͞c 2 of less than 10 23 of all charged secondary particles produced are obtained for all but the highest masses and shortest lifetimes predicted. [S0031-9007(97)03037-8] PACS numbers: 13.85.Rm, 14.80.LyRecent theoretical work [1-3] has proposed a supersymmetric model with a light gluino ͓g͔ in the mass range 100 600 MeV͞c 2 . A direct consequence of this model is the prediction of a set of supersymmetric hadrons in the 1000 3000 MeV͞c 2 mass range. We have searched for two weak decay modes between these hadrons in an attempt to either confirm this hypothesis or close the low mass window for supersymmetry.Among the light hadrons predicted [1-3] are the supersymmetric partners of the proton R 1 ͑uudg͒; J 2 , X 2 ͑ssdg͒; as well as the S 0 ͑udsg͒. Characteristically, the predicted mass and lifetime ranges for those states which have weak decays are 1700 2500 MeV͞c 2 and 50-500 ps. The mass splitting predicted [3] between the R 1 and S 0 is DM RS M R 1 2 M S 0 210 6 20 MeV͞c 2 . The S 0 is less massive than the R 1 in this model [3] due to the very strong attraction of the flavor singlet quarks in the S 0 . In this model this state is the lowest mass superbaryon. Only strangeness changing weak decays are allowed between the lowest mass superbaryons, unless the mass splittings are large enough to allow strong decay by kaon emission. If the mass splittings are similar to the hyperon system, as expected for the R 1 -S 0 system, the lifetimes and decay modes of the superbaryons should mimic the hyperons. Limits on the production rate of R 1 and X 2 as a function of mass and lifetime can be set in charged hyperon beam searches. We report such a search. We have not assumed the predicted mass splitting; we perform the search as a function of this parameter. For DM RS less than M p the R 1 decay is forbidden. For M p , DM XS , M K the X 2 is stable against strong decay via kaon emission and weak decay via pion emission is allowed. We assume the dominant decays are R 1 ! S 0 p 1 and X 2 ! S 0 p 2 analogous to the normal hyperon decays S 1 ! np 1 and J 2 ! L 0 p 2 .Fermilab experiment E761 was a high statistics study of hyperon radiative decays. We reconstructed [4] 48 3 10 6 S 1 ! pp 0 and 38 3 10 3 S 1 ! pg decays from data taken in 1990. Unfortunately, this data set cannot be used for an R 1 search, since the trigger required a photon in the final state. In our observation of the J 2 ! S 2 g decay [5] we took negative beam data in a different configuration of the apparatus. This had good acceptance for low momentum charged secondaries but also required a photon trigger. In order to control the photon ...

Extensive air showers from ultrahigh energy gluinos

“…The profiles shown in the Figure are directly measured in Fly's Eye experiment, and the data are quite different from the graphs displayed here for heavy glueballinos. The second mass window [25][26][27][28][29][30][31][32][33][34][35] GeV can be already reliably excluded on the basis of these measurements, though a detailed analysis is desirable.…”

“…The experiment FNAL-E-0330 by Gustafson et al was designed to search for neutral hadrons with masses > ∼ 2 GeV and lifetimes > ∼ 10 −7 s [37]. In contrast to the recent experiments [25,26,27,28], the Gustafson experiment was sensitive to long-lived or stable hadrons. It set upper limits on the production cross-section of these hadrons in the mass range 2-12 GeV which are given in the second line of Table 5.…”

“…There is some controversy if a light gluino, with a mass of a few GeV, is allowed. As it stands, the Farrar model [20] is in conflict with searches for glueballino decays [25,26,27] as well as for decays of other unstableg-hadrons [28]. However, these searches had been restricted to a narrow band of lifetimes and masses, and their results are not valid in the context of more generic models.…”

Lectures on Astroparticle Physics

“…(78). Since this too seems to be disfavored by accelerator constraints [95] we will here focus on neutrinos.…”

Gaugino mass dependence of electron and neutron electric dipole moments

“…Counterindications to a very light gluino have been published coming from the four-jet angular distributions [17], and from direct searches [18,19]. The four-jet results, which suggest a gluino mass of at least 6.3 GeV, are, however, subject to criticism [20], and it is possible that systematic errors related to monte-carlo dependence might be underestimated.…”