Subject: title and abstract of Apr 16 RPM
Date: Tue, 24 Mar 1998 12:43:25 -0800
From: LUK@csa6.lbl.gov
Reply-To: K_Luk@lbl.gov
To: MKIHANYA@lbl.gov
CC: MOROI@OBLEIX.lbl.gov

Hello Mary,
        The following is the title and abstract of the Apr 16 RPM. Greg
Landsberg would like to have a room reserved for him. Would you please
help him with that? Since he is going to rent a car, he will need gate-pass
and reserved parking. You may need direction from you as well.
        Thanks,
                        Kam-Biu

============================================================================
          "SEARCH FOR LEPTOQUARKS AND DIRAC MONOPOLES AT D-ZERO"
                            Greg Landsberg
                              (Fermilab)

The D-Zero experiment  at the Fermilab Tevatron  has performed a variety of
searches for the new physics, such as SUSY and exotic particles. Two recent
searches  for  the  exotic  elementary   particles:  leptoquarks  and heavy
magnetic  monopoles will be  discussed. In both cases  they resulted in the
most restrictive limits on the existence of these objects to date.

Leptoquarks are elementary objects  that can decay into quarks and leptons.
Following some weak  evidence for the production  of such particles in high
energy colisions of  electrons with protons at  HERA, we performed a search
for first-generation leptoquarks.  Such leptoquarks can be pair-produced in
antiproton-proton     interactions, and  would  appear as  events  with two
electrons, or two  (electron) neutrinos, or one  electron and one neutrino,
all with two  accompanying quark jets. In all  three channels, there was no
excess observed beyond the expected  background, The absence of interesting
candidate  events  was used  to set  limits  on the  possible  mass of such
leptoquarks. Limits on  second and  third-generation leptoquarks (involving
muonic and tau-lepton decays) will also be discussed.

Magnetic monopoles were predicted by  Dirac to symmetrize Maxwell equations
and  explain a   mysterious   quantization of the   electric  charge. Being
strongly coupled to photons, heavy pointlike monopoles are expected to give
rise to hard photon pair production  in high energy  collisions. Search for
such  events  with  the  D-Zero  detector,  first  of this  kind  at hadron
colliders, resulted in strong limits on the existence of these particles.