Probing unification scenarios with atomic clocks

Pinho

2017

Phys. Rev. D

Astrophysical tests of the stability of fundamental couplings are becoming an increasingly important probe of new physics. Motivated by the recent availability of new and stronger constraints we update previous works testing the consistency of measurements of the fine-structure constant α and the proton-to-electron mass ratio µ = mp/me (mostly obtained in the optical/ultraviolet) with combined measurements of α, µ and the proton gyromagnetic ratio gp (mostly in the radio band). We carry out a global analysis of all available data, including the 293 archival measurements of Webb et al. and 66 more recent dedicated measurements, and constraining both time and spatial variations. While nominally the full datasets show a slight statistical preference for variations of α and µ (at up to two standard deviations), we also find several inconsistencies between different sub-sets, likely due to hidden systematics and implying that these statistical preferences need to be taken with caution. The statistical evidence for a spatial dipole in the values of α is found at the 2.3 sigma level. Forthcoming studies with facilities such as ALMA and ESPRESSO should clarify these issues.

“…Constraints on these parameters have been obtained in previous works [7,8,14], though one finds that current data only constraints a particular combination of R and S .…”

Section: Relating the Variations Of Different Couplingsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stability of fundamental couplings: A global analysis

Pinho

2017

Phys. Rev. D

“…It follows from this that it's highly desirable to identify astrophysical systems where various constants can be simultaneously measured, or systems where a constant can be measured in several independent ways. Systems where combinations of constants can be measured are also interesting, and can provide useful consistency tests [19,20]. Note that while for molecular hydrogen one is indeed measuring µ, for more complex molecules (which may be more sensitive to µ variations than H 2 itself) one is actually measuring a ratio of an effective nucleon mass to the electron mass, and the relative variation of this quantity will only equal that of µ if there are no compositiondependent forces.…”

Section: Fundamental Couplingsmentioning

confidence: 99%

Fundamental cosmology in the E-ELT era: the status and future role of tests of fundamental coupling stability

2014

Gen Relativ Gravit

Self Cite

The observational evidence for the recent acceleration of the universe demonstrates that canonical theories of cosmology and particle physics are incomplete-if not incorrect-and that new physics is out there, waiting to be discovered. The most fundamental task for the next generation of astrophysical facilities is therefore to search for, identify and ultimately characterise this new physics. Here we highlight recent efforts along these lines, mostly focusing on ongoing work by CAUP's Dark Side Team aiming to develop some of the science case and optimise observational strategies for forthcoming facilities. The discussion is centred on tests of the stability of fundamental couplings (since the provide a direct handle on new physics), but synergies with other probes are also briefly considered. The goal is to show how a new generation of precision consistency tests of the standard paradigm will soon become possible.

“…However, current local bounds coming from atomic clock comparison experiments [4], are already about 6 orders of magnitude stronger, and rule out many otherwise viable dynamical dark energy models. A recent combined analysis of all currently available atomic clock measurements [5] led to the following indirect 95% confidence * up080302013@alunos.fc.up.pt † Carlos.Martins@astro.up.pt ‡ mmonteiro@fc.up.pt intervals for present-day (z = 0) drift rateṡ µ µ = (6.8 ± 57.6) × 10 −17 yr −1 (1) g p g p = (−7.2 ± 8.9) × 10 −17 yr −1 ,…”

Section: Introductionmentioning

confidence: 99%

Consistency tests of the stability of fundamental couplings and unification scenarios

Ferreira

Frigola²,

et al. 2014

Phys. Rev. D

We test the consistency of several independent astrophysical measurements of fundamental dimensionless constants. In particular, we compare direct measurements of the fine-structure constant α and the proton-to-electron mass ratio µ = mp/me (mostly in the optical/ultraviolet) with combined measurements of α, µ and the proton gyromagnetic ratio gp (mostly in the radio band). We point out some apparent inconsistencies, which suggest that hidden systematics may be affecting some of the measurements. These findings demonstrate the importance of future more precise measurements with ALMA, ESPRESSO and ELT-HIRES. We also highlight some of the implications of the currently available measurements for fundamental physics, specifically for unification scenarios.