75 research outputs found
Measurement of Linear Stark Interference in 199Hg
We present measurements of Stark interference in the 6
6 transition in Hg, a process whereby a static electric field
mixes magnetic dipole and electric quadrupole couplings into an electric
dipole transition, leading to -linear energy shifts similar to those
produced by a permanent atomic electric dipole moment (EDM). The measured
interference amplitude, = = (5.8 1.5) (kV/cm), agrees with relativistic, many-body predictions and
confirms that earlier central-field estimates are a factor of 10 too large.
More importantly, this study validates the capability of the Hg EDM
search apparatus to resolve non-trivial, controlled, and sub-nHz Larmor
frequency shifts with EDM-like characteristics.Comment: 4 pages, 4 figures, 1 table; revised in response to reviewer comment
Improved limit on the permanent electric dipole moment of 199Hg
We report the results of a new experimental search for a permanent electric
dipole moment of 199Hg utilizing a stack of four vapor cells. We find d(199Hg)
= (0.49 \pm 1.29_stat \pm 0.76_syst) x 10^{-29} e cm, and interpret this as a
new upper bound, |d(199Hg)| < 3.1 x 10^{-29} e cm (95% C.L.). This result
improves our previous 199Hg limit by a factor of 7, and can be used to set new
constraints on CP violation in physics beyond the standard model.Comment: 4 pages, 4 figures. additional reference, minor edits in response to
reviewer comment
A new limit on the permanent electric dipole moment of ^{199}Hg
We present the first results of a new search for a permanent electric dipole
moment of the ^{199}Hg atom using a UV laser. Our measurements give d(Hg)= -
(1.06 +/- 0.49 +/- 0.40) 10^{-28} e cm. We interpret the result as an upper
limit |d(Hg)| < 2.1 10^{-28} e cm (95% C.L.), which sets new constraints on
theta_{QCD}, chromo-EDMs of the quarks, and CP violation in Supersymmetric
models.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Gravitational Couplings of Intrinsic Spin
The gravitational couplings of intrinsic spin are briefly reviewed. A
consequence of the Dirac equation in the exterior gravitational field of a
rotating mass is considered in detail, namely, the difference in the energy of
a spin-1/2 particle polarized vertically up and down near the surface of a
rotating body is . Here is the latitude and
, where and are, respectively, the angular
momentum and radius of the body. It seems that this relativistic quantum
gravitational effect could be measurable in the foreseeable future.Comment: LaTeX file, no figures, 16 page
Quantum Theory in Accelerated Frames of Reference
The observational basis of quantum theory in accelerated systems is studied.
The extension of Lorentz invariance to accelerated systems via the hypothesis
of locality is discussed and the limitations of this hypothesis are pointed
out. The nonlocal theory of accelerated observers is briefly described.
Moreover, the main observational aspects of Dirac's equation in noninertial
frames of reference are presented. The Galilean invariance of nonrelativistic
quantum mechanics and the mass superselection rule are examined in the light of
the invariance of physical laws under inhomogeneous Lorentz transformations.Comment: 25 pages, no figures, contribution to Springer Lecture Notes in
Physics (Proc. SR 2005, Potsdam, Germany, February 13 - 18, 2005
Axions In String Theory
In the context of string theory, axions appear to provide the most plausible
solution of the strong CP problem. However, as has been known for a long time,
in many string-based models, the axion coupling parameter F_a is several orders
of magnitude higher than the standard cosmological bounds. We re-examine this
problem in a variety of models, showing that F_a is close to the GUT scale or
above in many models that have GUT-like phenomenology, as well as some that do
not. On the other hand, in some models with Standard Model gauge fields
supported on vanishing cycles, it is possible for F_a to be well below the GUT
scale.Comment: 62 pages, v2; references, acknowledgements and minor corrections
adde
Techniques used to search for a permanent electric dipole moment of the 199 Hg atom and the implications for CP violation
No description supplie
Strong-weak CP hierarchy from non-renormalization theorems
We point out that the hierarchy between the measured values of the CKM phase
and the strong CP phase has a natural origin in supersymmetry with spontaneous
CP violation and low energy supersymmetry breaking. The underlying reason is
simple and elegant: in supersymmetry the strong CP phase is protected by an
exact non-renormalization theorem while the CKM phase is not. We present
explicit examples of models which exploit this fact and discuss corrections to
the non-renormalization theorem in the presence of supersymmetry breaking. This
framework for solving the strong CP problem has generic predictions for the
superpartner spectrum, for CP and flavor violation, and predicts a preferred
range of values for electric dipole moments.Comment: 36 pages, 3 figure
Sub-millimeter Tests of the Gravitational Inverse-square Law
Motivated by a variety of theories that predict new effects, we tested the
gravitational 1/r^2 law at separations between 10.77 mm and 137 microns using
two different 10-fold azimuthally symmetric torsion pendulums and rotating
10-fold symmetric attractors. Our work improves upon other experiments by up to
a factor of about 100. We found no deviation from Newtonian physics at the 95%
confidence level and interpret these results as constraints on extensions of
the Standard Model that predict Yukawa or power-law forces. We set a constraint
on the largest single extra dimension (assuming toroidal compactification and
that one extra dimension is significantly larger than all the others) of R <=
160 microns, and on two equal-sized large extra dimensions of R <= 130 microns.
Yukawa interactions with |alpha| >= 1 are ruled out at 95% confidence for
lambda >= 197 microns. Extra-dimensions scenarios stabilized by radions are
restricted to unification masses M >= 3.0 TeV/c^2, regardless of the number of
large extra dimensions. We also provide new constraints on power-law potentials
V(r)\propto r^{-k} with k between 2 and 5 and on the gamma_5 couplings of
pseudoscalars with m <= 10 meV/c^2.Comment: 34 pages, 38 figure
Muon Physics: A Pillar of the Standard Model
Since its discovery in the 1930s, the muon has played an important role in
our quest to understand the sub-atomic theory of matter. The muon was the first
second-generation standard-model particle to be discovered, and its decay has
provided information on the (Vector -Axial Vector) structure of the weak
interaction, the strength of the weak interaction, G_F, and the conservation of
lepton number (flavor) in muon decay. The muon's anomalous magnetic moment has
played an important role in restricting theories of physics beyond the standard
standard model, where at present there is a 3.4 standard-deviation difference
between the experiment and standard-model theory. Its capture on the atomic
nucleus has provided valuable information on the modification of the weak
current by the strong interaction which is complementary to that obtained from
nuclear beta decay.Comment: 8 pages, 9 figures. Invited paper for the Journal of Physical Society
in Japan (JPSJ), Special Topics Issue "Frontiers of Elementary Particle
Physics, The Standard Model and beyond
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