Electromagnetic dipole moments and time reversal violating interactions for high energy charged baryons in bent crystals at LHC

V G Baryshevsky

doi:10.1140/epjc/s10052-019-6857-6

V G Baryshevsky

Open Access

https://doi.org/10.1140/epjc/s10052-019-6857-6

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Abstract

Spin precession of channelled particles in bent crystals at the LHC gives unique possibility for measurements of constants determining T-odd, P-odd (CP) violating interactions and P-odd, T-even interactions of charm, beauty and strange charged baryons with electrons and nucleus (nucleons), similarly to the possibility of measuring their electric and magnetic moments. For a particle moving in a bent crystal new effects caused by non-elastic processes arise. In addition to the spin rotation around the effective magnetic field {varvec{B}} direction (the bending axis direction), due to electromagnetic interactions and leading to changes in spin direction in the plane orthogonal to {varvec{B}} , the spin acquires projection along the {varvec{B}} direction. Moreover, when spin rotates around the direction of the electric field {varvec{E}} or the particle momentum {varvec{k}}, a spin component along {varvec{E}} or {varvec{k}}, respectively, is induced.

Highlights

Besides electromagnetic interaction a channelled particle moving in a crystal, experiences weak interaction with electrons and nuclei, as well as strong interaction with nuclei
When analyzing particle’s spin rotation, which is caused by electric dipole moment interaction with electric field, one should consider both P-odd, T-even and P-odd, T-odd noninvariant spin rotations, resulting from weak interaction with electrons and nuclei [12,13]
This paper demonstrates that spin precession of channelled particles in bent crystals at the LHC gives unique possibility to measure constants determining T-odd, P-odd (CP) violating interactions and P-odd, T-even interactions of charm,beauty and strange baryons, to possibility of measuring their electric and magnetic moments considered in [5,6,7,8,9,10,11]

Summary

Introduction

Besides electromagnetic interaction a channelled particle moving in a crystal, experiences weak interaction with electrons and nuclei, as well as strong interaction with nuclei. When analyzing particle’s spin rotation, which is caused by electric dipole moment interaction with electric field, one should consider both P-odd, T-even and P-odd, T-odd noninvariant spin rotations, resulting from weak interaction with electrons and nuclei [12,13]. This paper demonstrates that spin precession of channelled particles in bent crystals at the LHC gives unique possibility to measure constants determining T-odd, P-odd (CP) violating interactions and P-odd, T-even interactions of charm,beauty and strange baryons, to possibility of measuring their electric and magnetic moments considered in [5,6,7,8,9,10,11]. When spin rotates around the direction of electric field E or the particle momentum k, a spin component parallel to E or k, respectively, appears. The unit vectors along directions of B, E and k will be hereinafter denoted as Nm, NT and n respectively

Spin rotation and particles scattering in a crystal

P and CP violating spin rotation in bent crystals

Conclusion

Scattering amplitude

Effective potential energy U determined by spin-orbit interaction

Effective potential energy U determined by P-odd and T-even interactions