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