Search for fractional charge and heavy stable particles at PETRA

A search has been made for new particles with chargeQ=2/3, 1, 4/3, 5/3 produced ine⁺e⁻-reactions at PETRA. The energy range wasE_cm=27–35 GeV. No such particles were found. Upper limits for the cross-section depending on the assumed mass and production spectrum are given. ForQ=2/3 quarks with mass less than 12 GeV/c², upper limits <img src="/fulltext-image.asp?format=htmlnonpaginated&src=J8321157740H5106_html\10052_2005_Article_BF01474803_TeX2GIFIE1.gif" border="0" alt=" $${{\sigma \left( {q\bar q} \right)} \mathord{\left/ {\vphantom {{\sigma \left( {q\bar q} \right)} {\sigma \left( {\mu \mu } \right)}}} \right. \kern-\nulldelimiterspace} {\sigma \left( {\mu \mu } \right)}} \leqq 10^{ - 2} $$ " /> (90% C.L.) are obtained both for inclusive and exclusive production. For the lifetime of theB-meson (m_B=5GeV/c²) an upper limit τ≦2×10⁻⁹s is obtained.