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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: 1015 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 gD
g=gD2/434
em=1/137
Monopoles at HERA
p
s
Processes predicted but not rate
103 greater ionisation energy loss rate than mip
m
m
e e’
g
em
g
Monopoles of strength > 0.75 gD stoppedBind 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 1994-1997 : 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 10-12 T.
90gD
10gD
1.2gD
Ind
uce
d c
urr
en
t
x 10
-1x
10-2
position /cm
CalibrationSignature 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 gd)i
Beam pipe measurements Induced current from strips
No candidates found
Dirac Monopole
Strip number
Cur
rent
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 techniquesCompetitive ep limit
Upper limit for 3gd 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 < gD < 6 excluded.
Magnetic monopoles play fundamental role in modern physics theories.
Summary and Outlook
s
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