Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

Abstract

We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively-and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector.

Electromagnetic dipole moment and time reversal invariance violating interactions of high energy short-lived particles in bent and straight crystals

“…As a result, for ϕ xx ≃ 10 18 V cm 2 we have Ω Q ≃ 10 6 s − 1. Hence distance passed by particle in crystal L = 10cm rotation angle is ϑ ≃ 10 −3 rad, that corresponds to experiments for EDM limitations of heavy baryons [1][2][3][4]. Let us note, that in experiments in a straight crystal spin rotation caused by the magnetic moment of Ω ± hyperon is suppressed.…”

“…That is why one should always bear in mind the distinction between beam polarization ξ and spin vector S. Complete description of particle spin motion can be made by the use of spin density matrices equation (in more details see [10,21]). For the case of ultra relativistic baryons with spin S = 1/2 the T-BMT equations supplied with the term, which is responsible for interaction between particle EDM and electric field, can be written as follows (γ ≫ 1, γ is the Lorentz-factor) [1,2,22,23]:…”

Feasibility of τ -lepton electromagnetic dipole moments measurement using bent crystal at the LHC

“…If τ lepton possesses the EDM, the y component of polarisation will also be induced. In the limit γ τ 1, and assuming that EDM effects are small compared to the MDM spin precession, using formulas in [30], the ratio between absolute error on EDM and MDM is…”

“…Nevertheless, the method which uses channeling of short-lived baryons in bent crystals has recently attracted considerable attention [27][28][29][30][31]. In particular, in Ref.…”

“…[32]). The authors of [29,30] studied the application of this method for future measurements of EDM and MDM of the strange, charm and beauty baryons.…”