Session K10: Test of Physics Laws and Precision Experiments

Gravitational Tests of Lorentz Symmetry with Atom Interferometers

Lorentz-symmetry violation offers a potential probe for new physics at the Planck scale. At currently accessible energies, these violations are described by the Standard-Model Extension (SME). In this talk I will provide an outline of the SME and discuss new sensitivities to Lorentz violation attainable in atom interferometer experiments, arising from gravitational interactions with atoms.   

New Torsion Balance Search for Spin-Spin Forces

We report preliminary results from our new torsion balance search for interactions coupling polarized electron spins. We record the torque on a pendulum containing $10^{23}$ spin-polarized electrons as a function of its angle with respect to large sources of spin-polarized electrons placed outside the torsion balance apparatus. Results can be interpreted as constraints on axion-like pseudoscalar couplings, the exchange of general low-mass bosons constrained only by rotational and translational invariance, and on forces mediated by the Nambu-Goldstone bosons that would arise in the context of spontaneously broken Lorentz symmetry. These Goldstone bosons, often referred to as the ``ghost condensate" because they have a negative kinetic term in the Lagrangian stabilized by higher order terms, are particularly interesting because the energy scale accessible to our experiment is the scale on which they could contribute either to Dark Energy or Dark Matter. We will present the first experimental search for the unique signature of the ghost condensate's interaction with Standard Model fermions.   

Search for very light neutral spin-zero bosons at optical frequencies.

A Hampton-Jefferson Lab-Yale collaboration is working on an experiment (LIPSS) to test one interpretation of the PVLAS experiment. The PVLAS experiment detected a rotation of the plane of polarization of light in a magnetic field in a vacuum. This can be interpreted as due to the production of a very light (meV) neutral boson that couples to two photons. Such a boson would be outside the Standard Model. The LIPSS experiment is looking for the two-step process in which bosons are generated in a magnetic field by a laser beam and then photons are regenerated by the bosons in a second magnetic field. The status of the experiment, being carried out at the Jefferson Lab Free-Electron Laser User Facility, will be reported.   

Electron Electic Dipole Moment Experiment as a Search for TeV Scale Particles

Experimentally observable electric dipole moments (EDMs) are predicted, by nearly all extensions of the Standard Model, to arise from CP-violating couplings to new undiscovered particles in the 0.1 TeV to $>10$ TeV range. EDMs are widely anticipated and not yet observed. Their discovery would motivate a new generation of particle accelerators. Steps towards a new Cs cold-atom fountain EDM experiment to discover or rule out an electron EDM a factor of 100 below the present limit will be described. Included are: glass electric field plates and vacuum chamber to suppress magnetic Johnson noise, electric field quantization to suppress motional magnetic field systematics, and multiple quantum transitions to enhance sensitivity.   

Accelerator Mass Spectrometry Search for Strangelets in Lunar Soil

The theoretical existence of Strange Quark Matter (SQM) with similar amounts of up, down and strange quarks in one single hadronic bag has been postulated for over two decades. A wide range of experimental searches for strangelets (small lumps of SQM with baryon number less than $10^6$) have been conducted. However, none of these experiments, including terrestrial searches, accelerator searches, and the Alpha Magnetic Spectrometer 01 experiment (AMS-01) could give a definite answer to their existence. Our experiment searches for strangelets in lunar soil. Cosmic ray flux deposits strangelets on the Moon with a predicted concentration (one strange oxygen per $10^{16}$ to $10^{17}$ normal oxygen atoms) of $10^5$ times higher than that on Earth. The lunar soil sample is analyzed using accelerator mass spectrometry through the tandem Van-de-Graaff accelerator at Yale University. The accelerator together with our own designed detection system enables us to identify strangelets at a level of less than 1 per $10^{17}$ atoms.   

The Michelson-Morley experiment in an accelerated reference frame

The absence of an observed fringe shift in the Michelson-Morley experiment precludes using the Michelson-Morley interfereometer \textit{in an inertial reference frame} to measure the speed of that frame relative to a preferred absolute reference frame. Interestingly, an analysis of the Michelson-Morley experiment in an accelerated reference frame predicts a fringe shift that to leading order is proportional to the acceleration and to higher order also depends on the translational speed of the experimenter relative to an absolute reference frame. This analysis assumes that the experimental apparatus is subject to relativistic length contraction and reduces to the observed null result when the acceleration is zero. Details of the calculation of the velocity-dependent fringe shift will be presented, and the possibility of using this to measure absolute translational speed will be discussed.   

Constraining possible time variations of the gravitational constant through terrestrial nuclear laboratory data

A possible time variations of the gravitational constant was suggested by Dirac and some modern cosmological models. In contrast with the other fundamental constants, as the precision of measurements increased, the discrepancy among the empirical values of G also increased which led to a rise of the relative uncertainty of the present value for the gravitational constant. As suggested in literature, such hypothetical time variations of G can perturb the equilibrium density of a neutron star causing \textit{gravitochemical heating}. Using available terrestrial laboratory data on isospin diffusion in heavy-ion reactions at intermediate energies, through the gravitochemical heating formalism, we predict the surface temperature of a neutron star. When compared with the surface temperature of the nearest millisecond pulsar, PSR J043-4715, this constraint provides a more restrictive value of time variation of G.   

Fundamental Relationship Between Space, Time, Energy and Mass

A relationship has been postulated that unites energy, mass, space, and time at resonance for the first time. The relationship became apparent after the mystery of the mathematical and physical meaning of the fine structure constant of hydrogen was solved. This constant, which was called the alpha constant by Sommerfeld, and later called the Hand of God mystery by Feynman, was serendipitously solved by postulating that the subatomic structure of electromagnetic energy was quantum in nature and exists in only three dimensions of space with time. The understanding of this concept should serve to unite all the constants of nature and may form the basis of a more unified field theory.   

The Action of Marine Climate on Some Polymers

This article presents some studies referring to the structural changes of some polymers due to the action of marine climate. The marine climate refers to seas, oceans and lands under the action of sea weather. So, the marine climate can be extreme cold, tropical or extreme cold and tropical. In the marine climate, dust, radiation, sand and salt fog have important effects of medium on which the produces are exposed when they are stored, used or transported. The wind increases these effects. However, one of the most important effects, is the effect of humidity. For measurements we have selected those materials which are often aging by climatic factors like humidity, could, warm, dust and sand, radiations. We present the measurements and the results for PN50, PN70, PN80 elastomer rubbers used for gaskets resistant at oil environments. First the structure of the elastomers was analysed (IR measurements) with a spectrometer Equinox-55. Then, the samples were exposed on Agigea Station according to a test program. When we study the intermolecular process, an important role has the double link. The configuration of the double link relating to the position in the main chain in the lateraly groups, influence the oxidative process. Due to the marine climate, appear a lot of changes on the structure of polymers.