SUSY SIGNALS AT DESY HERA IN THE NO-SCALE FLIPPED SU(5) SUPERGRAVITY MODEL

Sparticle production and detection at DESY HERA are studied within the recently proposed no-scale flipped SU(5) supergravity model. Among th e various reaction channels that could lead to sparticle production at HERA, only the following are within its limit of sensitivity in this model: e-p --> e(L,R)chi(i)0 + X, v(e)chi1- where chi(i)0 (i= 1,2) are the two lightest neutralinos and chi1- is the lightest chargino. We s tudy the elastic and deep-inelastic contributions to the cross section s using the Weizsacker-Williams approximation. We find that the most p romising supersymmetric production channel is right-handed selectron ( e(R() plus first neutralino (chi1(0)), with one hard electron and miss ing energy signature. The v(e)chi1- channel leads to comparable rates but may also allow jet final states. A right-handedly polarized electr on beam at HERA would shut off the latter channel and allow preferenti ally the former one. With an integrated luminosity of L = 100 pb-1, HE RA may be able to extend the present CERN LEP I lower bounds on m(eR), m(ve), m(chi1)0 by almost-equal-to 15-20 GeV, while L = 1000 pb-1 wou ld make HERA competitive with LEP II. We also show that the Leading Pr oton Spectrometer at HERA is an excellent supersymmetry detector which can provide indirect information about the sparticle masses by measur ing the leading proton longitudinal momentum distribution.