https://doi.org/10.1140/epjc/s2005-02399-1
Experimental Physics
Search for lepton-flavor violation at HERA
A search for lepton-flavor-violating interactions 
and 
has been performed with the ZEUS detector using the entire HERA I data sample, corresponding to an integrated luminosity of 
. The data were taken at center-of-mass energies, 
, of 300 and 
. No evidence of lepton-flavor violation was found, and constraints were derived on leptoquarks (LQs) that could mediate such interactions. For LQ masses below , limits were set on 
, where 
is the coupling of the LQ to an electron and a first-generation quark q
1, and 
is the branching ratio of the LQ to the final-state lepton 
(μ or 
) and a quark q. For LQ masses much larger than , limits were set on the four-fermion interaction term 
for LQs that couple to an electron and a quark 
and to a lepton and a quark 
, where 
and 
are quark generation indices. Some of the limits are also applicable to lepton-flavor-violating processes mediated by squarks in R-Parity-violating supersymmetric models. In some cases, especially when a higher-generation quark is involved and for the process , the ZEUS limits are the most stringent to date.
© Springer-Verlag, 2005
