E. Zavattini

New PVLAS results and limits on magnetically induced optical rotation and ellipticity in vacuum

In 2006 the PVLAS collaboration reported the observation of an optical rotation generated in vacuum by a magnetic field. To further check against possible instrumental artifacts, several upgrades to the PVLAS apparatus have been made during the past year. Two data taking runs, at the wavelength of 1064 nm, have been performed in the new configuration with magnetic field strengths of 2.3 and 5 T. The 2.3 T field value was chosen in order to avoid stray fields. The new observations do not show the presence of a rotation signal down to the levels of

Differential and total cross sections for π− + p → η + n from 718 to 1050 MeV/c

1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\text{ }\text{ }\mathrm{rad}

Experimental method to detect the magnetic birefringence of vacuum

at 5 T and

Frequency locking of a Nd:YAG laser using the laser itself as the optical phase modulator

1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\text{ }\text{ }\mathrm{rad}

Elastic scattering of mesoatoms on hydrogen and on deuterium: Determination of the total spin state of the μp mesoatom

at 2.3 T (at 95% C.L.) with 45 000 passes in the magnetic field zone. In the same conditions no ellipticity signal was detected down to

Observation of muonic X-rays in hydrogen gas

1.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}

Experimental study of the decay modes of the η meson

at 2.3 T (at 95% C.L.), whereas at 5 T a signal is still present. The physical nature of this ellipticity as due to an effect depending on

PVLAS: Vacuum Birefringence And Production And Detection Of Nearly Massless, Weakly Coupled Particles By Optical Techniques

{B}^{2}

Very high Q frequency‐locked Fabry–Perot cavity

can be excluded by the measurement at 2.3 T. These new results completely exclude the previously published magnetically induced vacuum dichroism results, indicating that they were instrumental artifacts. These new results therefore also exclude the particle interpretation of the previous PVLAS results as due to a spin-zero boson. The background ellipticity at 2.3 T can be used to determine a new limit on the total photon-photon scattering cross section of

Measurements of pionic X-rays from hydrogen

{\ensuremath{\sigma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}l4.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}34}\text{ }\text{ }\mathrm{barn}