A New Limit on the Light Speed Isotropy From the Graal Experiment at Esrf

Abstract

When the electrons stored in the ring of the European Synchrotron Radiation Facility (ESRF, Grenoble) scatter on a laser beam (Compton scattering in flight) the lower energy of the scattered electron spectra, the Compton Edge (CE), is given by the two body photon-electron relativistic kinematics and depends on the velocity of light. A precision measurement of the position of this CE as a function of the daily variations of the direction of the electron beam in an absolute reference frame provides a oneway test of Relativistic Kinematics and the isotropy of the velocity of light. The results of GRAAL-ESRF measurements improve the previously existing one-way limits, thus showing the efficiency of this method and the interest of further studies in this direction.

Triangular Ring Resonator: Direct Measurement of the Parity-Odd Parameters of the Photon Sector of Sme

“…The local constraints can be provided by accelerators. For example not having observed the Compton-edge photons at the ESRF's GRAAL facility [24,25] leads to the bound of 10 −13 on the mSME coefficients. There exist proposals to measure the parity-odd LIV terms at the level of 10 −16 by the electrostatics or magnetostatics systems [4][5][6].…”

“…[87] for the purpose of this section. In the sense that (16), (17) and (18) have been implemented in (25) and (26). We notice that (25) and (26) lead to expressing the parity odd coefficients in the material in term of the parity coefficients in the vacuum.…”

“…This model adds all the perturbative parameters breaking the Lorentz symmetry to the Lagrangian of the standard model before asking how much which experiment or observation constrains them. This model has stemmed recent research aimed to detect or study the Lorentz Invariance Violation (LIV) terms for electromagnetic (photon sector of the SME) in various fields, including the classical solutions of SME electrodynamics [4][5][6][7], cosmological birefringence constraints [8][9][10], radiation spectrum of the electromagnetic waves and CMB data [11][12][13][14][15][16][17], black body radiation in finite temperature [18][19][20][21], LIV terms in higher dimensional scenarios [22,23], synchrotron radiation [24,25], Cherenkov radiation [26][27][28][29] and modern cavity resonators or interferometry experiments [30][31][32][33][34][35]. Studies have been conducted to search for the LIV terms in the neutrino sector [36][37][38][39][40][41][42], meson sector [43][44][45][46]…”