Yu. Kulchitsky, N. Rusakovich: JINR, Dubna The state of the proposals for search of the magnetic monopoles on LHC at the ATLAS project Yu. Kurochkin, I. Satsunkevich, Dz. Shoukavy: B.I. Stepanov Institute of Physics, Minsk Yu. Kulchitsky, N. Rusakovich: JINR, Dubna

e g = n ħc/2, n=0,±1,±2,… (P.A.M. Dirac, 1931) Introduction WHY does quantisation of the electric charge exist? In 1931 Dirac showed that the existence of single magnetic monopole with magnetic charge g explained the quantization of electric charge e in terms of the Dirac quantization condition e g = n ħc/2, n=0,±1,±2,… (P.A.M. Dirac, 1931) Besides explaining the quantization of electric charge, the existence of magnetic charges restores the symmetry of the Maxwell’s equations Thus, existence of both electric and magnetic charge in the universe requires charge quantization. Since the quantization of electric charge in nature is well established but still mysterious, the discovery of just a single monopole would provide a much wanted explanation.

Introduction New situation was created in 1974 after work's Polyakov and 'tHooft in which they demonstrated monopole solutions in the SO(3) Georgi-Glashow model. Later it was discovered that any scheme of Grand Unification with an electromagnetic U(1) subgroup embedded into a semi-simple gauge group, which became spontaneously broken by Higgs mechanism, possessed monopole solutions inevitably. The monopoles of the usual Grand Unification have a mass of the order of the unification scale 1017 GeV and therefore cannot be discovered at the current or future accelerators. They could only be produced in the first instants of our Universe and can be searched for in the penetrating cosmic radiation. However, there are models of the Grand Unification where the electroweak symmetry breaking can give rise to monopoles of mass ~ 1 - 15 TeV. It was shown that the unification scale could be significantly lowered through appearance of extra dimensions. Thus, in the some models of the Grand Unification the monopoles of masses which can be produced at LHC energies.

The most recent limits on the monopole mass Tevatron p p – collisions Experiment E-882 (Al) |n|=1, M > 285 GeV (Al) |n|=2, M > 355 GeV (Be) |n|=3, M > 325 GeV (Be) |n|=6, M > 420 GeV LEP 2 e+ e- - collisions HERA e+ p – collisions |n|=1,2,3,6 45 GeV < M < 102 GeV (Al) M > 140 GeV Drell- Yan production CDF Run II M > 360 GeV

Differential cross section The production γγ via virtual monopole loop (I. Ginsburg) Published estimation for monopole mass limit from this mechanism has difficulties with unitarity. Differential cross section Cross section If the cross section were dominated by a single partial wave of angular momentum J, the cross section would be bounded by Unitarity relation Comparing this with the our cross section, we obtain that this cross section violates unitarity relation.

Differential cross section Differential cross section Monopole production By a Dirac monopole we mean a particle without electric charge or hadronic interactions and with magnetic charge g satisfying the Dirac quantization condition. Going from lepton to monopole production we replace e gβ Two photon s=1/2 Drell-Yan Differential cross section Differential cross section When we make duality substitution e gβ the Drell-Yan model satisfy the unitarity relation up to n≈3 Therefore, we need to use n=3 cross section as the unitarity limit for all n>3 As it follows from differential cross section we have all partial waves for two photon production. Thus, we have no any contradiction with unitarity for γγ processes.

Cross section The comparison production cross-section for γγ fusion and Drell-Yan for monopole-antimonopole pair in pp-collisions at √s=14 TeV “On production of magnetic monopoles via photon-photon fusion at high energy pp collisions”, Yu.Kurochkin,I.Satusunkevich,Dz.Soukavy and Yu. Kulchitsky, N. Rusakovich Modern Physics Letters A,vol.21,No.38(2006) So, γ γ production is the leading mechanism for direct monopole searches at LHC

Pythia Modified The coupling constant was redefined in pysgwz.F Pythia was setup to produce heavy muons through the modified Drell-Yan process no initial state shower no final state shower no multiple interactions no hadronization The coupling constant was redefined in pysgwz.F FACZ=4D0*COMFAC*3D0 c DGDG: change coupling constant ALEM = SQRT(1.-4.*PMAS(13,1)*PMAS(13,1)/VINT(44))/2. print*,"ALEM = ",ALEM HP0=ALEM/3D0*SH HP1=ALEM/3D0*XWC*SH DO 100 I=MMINA,MMAXA IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 100 This code was added in Generators/Pythia_i/src/PythiaModified

Beta monopole 1 2 3 Beta Region MM b Energy Loss 1 Very Slow < 10-4 Magnetic Monopoles Searches G.Giacomelli, L.Patrizii, Feb 2003 Region MM b Energy Loss 1 Very Slow < 10-4 Lose energy in elastic collisions with atoms or nuclei 2 Slow 10-4<b<10-2 Ionization or excitation of the atoms 3 Fast >10-2 Ionization: Behaves like a electric charge with e=g b

Comparison Eta and Phi monopoles-muons muons with mass of 500GeV Magnetic monopoles with mass 500 GeV Dz. Shoukavy In. Ph. Minsk, Dubna; D. Goldin, A. Firan, J. Ye, R. Stroynowski: SMU, Dallas

How can we search monopole at LHC? If magnetic monopole produced in ATLAS then monopole would be revealed by its unique characteristic. Transition Radiation The large value of a magnetic charge means that ionization energy losses will be several orders of magnitude greater for monopoles than for electrically charged particle. Trapped magnetic monopoles can be draft by the magnetic field and further registered.

For monopole we make the replacement Transition Radiation As in АTLAS there is a detector of transitive radiation, then we have additional opportunity for monopole search. The energy radiated when a particle with charge ze crosses the boundary between vacuum and a medium plasma frequency ωp is The typical emission angle ~ 1/γ. For a particle with γ=103 the radiated photons are in the soft x-ray range 2 to 20 keV. The number of radiated photons For monopole we make the replacement Thus, for monopole will be some tens times more radiated photons

Energy loss by ionization The energy loss dE/dx due to ionization for an electrically charged particle is given the Bethe-Bloch formula is the mean excitation energy of the scattering material For magnetic monopoles with velocities β≥0.1 just we need make the replacement The energy loss dE/dx due to ionization does not depended on the mass of the incident particle but just its kinematic properties For velocities β<0.01 we need to use the next approximation for all materials

Monte Carlo Simulation-Recent work The behavior of the magnetic monopole inside the Atlas detector will be similar with the one of a massive, neutral particle that interacts with matter via ionization using a modified Bethe-Block formula. The magnetic monopole was implemented in this manner in Geant4 by Mr. Vladimir Ivantchenko and Andrea dell’ Acqua Now there is a work on addition G4 example for a magnetic monopole to current release Athena 14.5.0

Future plans The creation of Monte-Carlo generator for two-photon monopole production The estimation is the detector efficiency and trigger efficiency

Some articles and talks: 1. Yu. Kurochkin, I. Satsunkevich, Dz. Shoukavy and N. Rusakovich, Yu. Kulchitsky. On production of magnetic monopoles via γγ fusion at high energy pp collisions // Mod. Phys. Lett. A, Vol. 21, No. 38 (2006) pp. 2873-2880. 2. Yu.A. Kurochkin, Yu. Kulchitsky, V.V. Makhnatch, N.A. Rusakovich, I.S. Satsunkevich, Dz.V. Shoukavy. Modern status of magnetic monopoles. Methods of Non-Euclidean Geometry in Modern Physics. Proc. of V Intern. Conf. “Bolyai-Gauss-Lobachevsky (BGL-5)” , Minsk 2006, p. 349-358 3. Yu. Kurochkin, I. Satsunkevich, Dz. Shoukavy and N. Rusakovich, Yu. Kulchitsky. Monopoles at ATLAS // Proc. of the International school-seminar “The actual problems of microworld physics” (Gomel, Belarus July 23-August 3, 2007), Dubna, JINR, Russia, 2008, Vol.1, P. 104-111. 4. A. Firan, A. Dell’ Acqua, D. Goldin, V. Ivantchenko, Dz. Shoukavy, R. Stroynowski, J. Ye – Search for magnetic monopoles using ATLAS detector // ATLAS Notes. 5. Yu. Kurochkin, I. Satsunkevich, Dz. Shoukavy and N. Rusakovich, Yu. Kulchitsky. Monopoles in ATLAS. Problems of the Theory and peculiarities of the experimental searchю Proc. of XV Intern. Ann. Seminar NPCS’2008 (Minsk, Sosny, May 2008). 6. Yu. Kurochkin, I. Satsunkevich, Dz. Shoukavy - Modern status of magnetic monopoles and the prospects of their search at LHC. // Proc. of the Natl. Academy of Sciences of Belarus, Ser. Phys.-Math. Sci. - 2008, No.2. - P. 68-72.

Problems Коллобарация Geant (конкретно - Иванченко) создала пример, который позволяет оценивать потери энергии за счет ионизации магнитным монополем при его прохождение в веществе. В области β≥0.1 используется формула Алена (Rev.Mod.Phys 52.(1980), 121), а области β<0.01 приближенная формула, которая не зависит от материала, а только от заряда и скорости магнитного монополя Данный пример был добавлен в geant4.9.0 ref01. С помощью UserPhysicsDefinition.h был сконструирован магнитный монополь, как объект массой 350 ГэВ и магнитным зарядом g=38.5e . До недавнего времени ATHENA использовала geant 4.8.3. Данное обстоятельство не позволяло использовать монопольный скрипт, созданный коллобарацией Geant. Для устранения этой проблемы  Andrea Dell'Acqua создал монопольную библиотеку. Однако пока не удалось добиться приемлемых результатов. А конкретно вызывает сомнеие, как проходила стадия симуляции – слишком быстро, что наводило на мысль что, что-то тут не ладно. В отличие от Д. Шелкового группа из Даласса утверждает, что им удалось добиться того, что Athena версия 12.0.6 работает удовлетворительно с монопольной библиотекой. 3 Декабря вышел релиз Athena 14.5.0 который использует Geant 4.9.1, что как мы надеемся позволить нам оценить потери энергии магнитным монополем при его прохождении детектора ATLAS, без учета ускорения монополя в магнитном поле детектора.