A Direct Search for Magnetic Monopoles at H1 HEP03, Aachen, 17-23/7/03 David Milstead The University of Liverpool

Monopoles in Particle Physics ‘t hooft/Polyakov – Monopole from breaking of simple symmetry group into U(1) SUSY GUTs: GeV Little Higgs: 1-5 TeV ? Electric charge quantisation Dirac - e=nh/g   Gauge group symmetry breaking

First search in ep at =300 GeV Sensitive to 150 GeV mass QED coupling for Dirac Monopole g D  g =g D 2 /4  34  em =1/137 Monopoles at HERA p s Processes predicted but not rate 10 3 greater ionisation energy loss rate than mip m m e e’ gg  em gg

Monopoles of strength > 0.75 g D stopped Bind to Al nucleus dipole moment and only released by melting (Milton et al.) Take 60cm section of 2mm thick H1 beam-pipe around interaction zone. Used : lumi=60pb -1 Cut into 14 strips and pass through superconducting loops and measure current. Monopoles in the H1 beam pipe

Southampton SQUID DC SQUID (2G mod. 581) at Southampton Oceanography Centre, UK. Sample sizes up to 1m long and 5cm radius. Measures changes in magnetic field T.

90g D 10g D 1.2g D Induced current x x position /cm Calibration Signature of monopole is persistent current Use solenoids with varying currents to mimick step solenoidsc loop i B

Signal survival Monopole signal survives after strip traversal strip Solenoid ( = 1 g d ) i

Beam pipe measurements Induced current from strips No candidates found Dirac Monopole Strip number Current

Monopole Acceptance Rising acceptance with high charge and low mass Use  mm (comphep) model

Cross-section upper limits First upper limits in ep collisions

Upper limit for Dirac Monopole Production Different experimental techniques Competitive ep limit

Upper limit for 3g d monopoles Only limits from ep and pp

First search in electron-proton scattering at =300 GeV at the H1 experiment Search for monopoles stopped in the beam pipe. Monopole masses up to 150 GeV and charges 1 < g D < 6 excluded. Magnetic monopoles play fundamental role in modern physics theories. Summary and Outlook s