The Search for Variations of Fundamental Couplings and Mass Scales

Conference Date: 
Monday, July 14, 2008 (All day) to Friday, July 18, 2008 (All day)

 

The last decade has seen a dramatic improvement in the quality of tests of variations of fundamental couplings and mass scales in space and time. Currently, a large number of the astrophysical, cosmological, space-based and laboratory-based tests are being conducted. Should any of such tests give a non-zero result, they would also suggest a dynamical nature for the dark energy in the Universe, which makes them highly relevant for the on-going effort in cosmology to measure the dynamical properties of dark energy. The workshop aims to bring together atomic and nuclear physics experimentalists and theorists working on the implementation of such tests, and theoretical particle physicists and cosmologists working on creating consistent models that can account for changing couplings.

 

Julian Berengut, University of New South Wales 
James Bergquist, NIST
Dmitry Budker, University of California, Berkeley
Thomas Dent, University of Heidelberg
John F.Donoghue, University of Massachusetts
Victor Flambaum, University of New South Wales 
Joe Henson, Perimeter Institute 
Eric Hudson, Yale University
A.V. Ivanchik, Ioffe Institute 
Savely Karshenboim, Max-Planck-Institute 
Hidetoshi Katori, University of Tokyo 
Rishi Khatri, University of Illinois, Urbana-Champaign
Julian King, University of New South Wales 
Mikhail Kozlov, University of Turku
Michael Murphy, Swinburne University 
Ekkehard Peik, PTB
Federico Piazza, Perimeter Institute
Maxim Pospelov, University of Victoria &Perimeter Institute
Lee Smolin, Perimeter Institute 
Raghunathan, Srianand IUCAA
Jan Thomsen, Niels Bohr Institute 
Michael Tobar, University of Western Australia 
Justin Torgerson, Los Alamos National Laboratory
Wim Ubach, University of Amsterdam

 

Julian Berengut, University of New South Wales 
Hadronic Mass Variation in Big Bang Nucleosynthesis

I will present a brief introduction to Big Bang Nucleosynthesis theory and observation. I will then discuss BBN as a probe of hadronic mass variation in the very early universe, including comparison with the observed Li7 discrepancy. Finally I want to explore the possibility of overproducing Li6 by three orders of magnitude in order to match reported observations.


James Bergquist, NIST


Dmitry Budker, University of California, Berkeley
Search for temporal variation of \alpha in radio-frequency transitions of atomic dysprosium.


Thomas Dent, University of Heidelberg
Recent and Local Variations and Unified Models

Precision tests of Local Position Invariance (LPI) involve many different methods in atomic, nuclear and gravitational physics, astrophysics and cosmology, and many different epochs and environments. We present some methods for comparing or combining different methods, either in a model-independent way or within simple scalar field models of variation. We focus on which methods are most sensitive to cosmologically recent time variation, and also on tests of spatial variation within the Solar System.


John F.Donoghue, University of Massachusetts
Nuclear binding and the light quark masses – Dynamics and constraints

I will describe a method of understanding how the nuclear binding energies depend on the masses of the light quarks. This is useful in applications ranging from anthropic constraints to equivalence principle tests and bounds on the time variation on the quark masses.

 


Eric Hudson, Yale University
Enhanced Sensitivity to Variation of me/mp in Molecular Spectra 
 

 

We propose new experiments with high sensitivity to a possible variation of the electron-to-proton mass ratio µ me/mp. We consider a nearly degenerate pair of molecular vibrational levels, each associated with a different electronic potential. With respect to a change in µ, the change in the splitting between such levels can be large both on an absolute scale and relative to the splitting. We demonstrate the existence of such pairs of states in Cs2, where the narrow spectral lines achievable with ultracold molecules make the system promising for future searches for small variations in µ.


A.V. Ivanchik, Ioffe Institute 
Testing the m_p/m_e cosmological variation from H_2 lines in High-Redshift QSO spectra

 


Savely Karshenboim, Max-Planck-Institute
Conceptual problems in phenomenological interpretation in searches for variation of constants and violation of various invariances

 

At present a number of current or proposed experiments are directed towards a search for a `new physics' by detecting variations of fundamental physical constants or violations of certain basic symmetries. Various problems related to the phenomenology of such experiments will be considered.


Hidetoshi Katori, University of Tokyo
Optical lattice clocks with bosonic/fermionic Sr and with the other atomic elements

 


Rishi Khatri, University of Illinois, Urbana-Champaign
21 cm radiation: A new probe of fundamental physics

 

New low frequency radio telescopes currently being built open up the possibility of observing the 21 cm radiation before the Epoch of Reionization in the future, in particular at redshifts 200 ≥ z ≥ 30, also known as the dark ages. At these high redshifts, Cosmic Microwave Back-ground (CMB) radiation is absorbed by neutral hydrogen at its 21 cm hyperfine transition. This redshifted 21 cm signal thus carries information about the state of the early Universe and can be used to test fundamental physics. We study the constraints these observations can put on the variation of fundamental constants and on fundamental mass scales. We show that the 21 cm radiation is very sensitive to the variations in the fine structure constant and can in principle place constraints comparable to or better than the other astrophysical experiments. Cosmic strings, if they exist, contribute to the anisotropies in the primordial gas leaving an imprint on the 21 cm radiation. They can tell us about the fundamental mass scales involved in the theories beyond the standard model. We show that the 21 cm radiation can potentially probe cosmic strings of tension ~10−12 asumming intercommutation probability of 1. Making such observations will require radio telescopes of collecting area 10 − 106 km2 compared to ~ 1 km2 of current telescopes.


Julian King, University of New South Wales 

 

Stringent constraint on variation in mu from three quasar spectra

 

We have used molecular hydrogen transitions in high quality spectra of quasars Q0403-443, Q0347-383 and Q0528-250, to search for a change in the proton-to-electron mass ratio, mu. Our improvement on previous works is twofold. Firstly, we use an improved technique to calibrate the wavelength scale of the VLT/UVES data, which reduces systematics. Secondly, we model all the hydrogen Lyman alpha transitions in the vicinity of each molecular hydrogen transition. The motivation for doing so is to reduce systematic effects associated with the use of low order polynomial continuum approximations near the molecular hydrogen transitions. We find a fractional change, delta(mu)/mu of (+2.6 ± 3.0) x 10^(-6). Our measurement error is a factor of two improvement over Reinhold et al [PRL 96, 151101
(2006)] who find a 4-sigma detection of (+24 +/- 6) x 10^(-6). The new result we present in this paper, coupled with the previous results on
varying alpha, appear inconsistent with generic predictions from Grand Unified Theories, suggesting either the latter are invalid, or the
varying alpha results wrong.


Mikhail Kozlov, University of Turku
Limits on variation of fundamental constants from microwave and infrared transitions in atoms and molecules


Michael Murphy, Swinburne University
Quasar absorption line constraints on variable fundamental constants

I will review the published quasar absorption line constraints on variations in the fine-structure constant, alpha, focusing on the apparent disagreement between those derived from Keck/HIRES and VLT/UVES spectra which have provided evidence for and against alpha variation, respectively. I demonstrate simple yet fundamental flaws in the UVES constraints which preclude reliable comparison with those from HIRES. I will outline our program to obtain a definitive UVES measurement. I will also present several new absorption line constraints on variations in the proton-to-electron mass ratio, mu. For the two molecular hydrogen absorbers from which previous authors found tentative evidence for mu-variation, we find robustly null results. A further two molecular hydrogen absorbers, including an entirely new system, also yield tight, null constraints. Finally, I present new, detailed comparison of a radio absorption system containing ammonia inversion and molecular rotational transitions which yields the strongest current astrophysical constraint on mu-variation, dmu/mu=[mu(z)-mu(lab)]/mu(lab)=[+0.74+/-0.47(stat)+/-0.76(sys)]x10^-6, at redshift z=0.685.


Nelson Nunes, Cambridge University 
Reconstructing the evolution of dark energy with the variaton of fundamental parameters


Federico Piazza, Perimeter Institute 
Coupling variations and equivalence principle violations in string inspired scenarios

I will describe how and why coupling variations and violations of the equivalence principle are generally expected in string theory and focus on two main scenarios/realizations: the Damour-Polyakov and the runaway dilaton.


Ekkehard Peik, PTB
Laboratory search for temporal variations of fundamental constants with optical clocks


Maxim Pospelov, University of Victoria & Perimeter Institute
Review of Models


Lee Smolin, Perimeter Institute 
How to test mutiverse theories


Raghunathan Srianand, IUCAA
Probing the variation of fundamental constants using QSO absorption lines


Jan Thomsen, Niels Bohr Institute 
High accuracy 87Sr atomic lattice clock for laboratory measurements of alpha variation

High precision measurements in atomic and molecular systems have reached unprecedented accuracy owing to the state-of-the-art quantum control of both light and matter. We have recently completed an evaluation of the uncertainty of our 87Sr optical lattice clock at the 1x10e-16 fractional level, surpassing the best current evaluations of Cs primary standards. By analyzing worldwide measurements of the absolute frequency of the clock transitions in Sr, we constrain temporal variations of fundamental physical constants as well as their possible couplings to the gravitational potential.  We will report the latest results on our 87Sr optical atomic clock, as well as the use of the Sr system to constrain variations of the fine-structure constant.


Michael Tobar, University of Western Australia 
Precision microwave oscillators and interferometers to test Lorentz Invariance and Local Position Invariance

 

We present recent and ongoing work that uses precision frequency generation and phase measurement to test the constancy of the speed of light Local Position Invariance (LPI) and the Lorentz Invariance (LI) of the photon with respect to the Standard Model of Particle Physics under the frame work of the Standard Model Extension (SME). The first experiment consists of a pair of orthogonally orientated single crystal sapphire resonators cooled to cryogenic temperatures and configured as stable oscillators operating in Whispering Gallery Mode (Cryogenic Sapphire Oscillator). The experiment is continuously rotated at a period of about 20 seconds, and modulations are searched for with respect to an absolute frame of reference. Our experiment has confirmed Lorentz Invariance at sensitivity better than one order of magnitude than previous tests. The experiment is now being upgraded and has the potential to improve this result by further one and a half orders of magnitude. 

The second experiment consists of a Mach-Zender Interferometer with a magnetic material in one arm. This experiment allows us to measure odd parity and scalar Lorentz violating parameters predicted in the SME, in which the cavity experiment either exhibit suppressed or no sensitivity to. The experiment has been in continuous operation since September 2007 and has put a limit of order 10^-7 on the scalar Lorentz violating parameter, we show that an upgraded experiment can improve this result by a few more orders of magnitude.

The final experiment measures over seven years the frequency comparison of a Cryogenic Sapphire Oscillator and a Hydrogen maser at the Paris Observatory. Amongst the data we search for signals correlated with the changing gravitational potential (test of LPI) and reference frame velocity (test of LI), with first results to be presented.


Justin Torgerson, Los Alamos National Laboratory


Wim Ubach, University of Amsterdam
In search for mu-variation: laboratory spectroscopy and astronomical observations of molecular hydrogen