8,311 research outputs found
Low Energy Precision Test of Supersymmetry
Supersymmetry (SUSY) remains one of the leading candidates for physics beyond
the Standard Model, and the search for SUSY will be a central focus of future
collider experiments. Complementary information on the viability and character
of SUSY can be obtained via the analysis of precision electroweak measurements.
In this review, we discuss the prospective implications for SUSY of present and
future precision studies at low energy.Comment: 118 pages, review pape
Supersymmetric contributions to weak decay correlation coefficients
We study supersymmetric contributions to correlation coefficients that characterize the spectral shape and angular distribution for polarized µ- and beta-decays. In the minimal supersymmetric standard model (MSSM), one-loop box graphs containing superpartners can give rise to non-(V-A)[direct-product](V-A) four-fermion operators in the presence of left-right or flavor mixing between sfermions. We analyze the present phenomenological constraints on such mixing and determine the range of allowed contributions to the weak decay correlation coefficients. We discuss the prospective implications for future µ- and beta-decay experiments, and argue that they may provide unique probes of left-right mixing in the first generation scalar fermion sector
Parity-Violating Electron Scattering as a Probe of Supersymmetry
We compute the one-loop supersymmetric (SUSY) contributions to the weak
charges of the electron () and proton () using the Minimal
Supersymmetric Standard Model (MSSM). These vector couplings of the
-boson to fermions will be determined in two fixed-target,
parity-violating electron scattering experiments. The SUSY loop contributions
to and can be substantial, leading to several percent
corrections to the Standard Model values for these quantities. We show that the
relative signs of the SUSY loop effects on and are correlated
and positive over nearly all of the MSSM parameter space, whereas inclusion of
R-parity nonconserving interactions can lead to opposite sign relative shifts
in the weak charges. Thus, a comparison of and measurements
could help distinguish between different SUSY scenarios.Comment: 4 pages, 2 figure
Probing Supersymmetry with Neutral Current Scattering Experiments
We compute the supersymmetric contributions to the weak charges of the
electron and proton in the framework of Minimal Supersymmetric Standard Model.
We also consider the ratio of neutral current to charged current cross
sections, R_nu and R_nubar at nu (nubar)-nucleus deep inelastic scattering, and
compare the supersymmetric corrections with the deviations of these quantities
from the Standard Model predictions implied by the recent NuTeV measurement.Comment: 4 pages, contribution to the proceedings of CIPANP 2003 (May, 2003),
New York Cit
High-Precision Optical Measurement of the 2S Hyperfine Interval in Atomic Hydrogen
We have applied an optical method to the measurement of the 2S hyperfine
interval in atomic hydrogen. The interval has been measured by means of
two-photon spectroscopy of the 1S-2S transition on a hydrogen atomic beam
shielded from external magnetic fields. The measured value of the 2S hyperfine
interval is equal to 177 556 860(15) Hz and represents the most precise
measurement of this interval to date. The theoretical evaluation of the
specific combination of 1S and 2S hyperfine intervals D_21 is in moderately
good agreement with the value for D_21 deduced from our measurement
Octet Baryon Charge Radii, Chiral Symmetry and Decuplet Intermediate States
We compute the octet baryon charge radii to O(1/Heavy^3) in heavy baryon
chiral perturbation theory. We examine the effect of including the decuplet of
spin-3/2 baryons explicitly. We find that it does no t improve the level of
agreement between the HBchiPT and experimental values for the Sigma^- charge
radius.Comment: 9 pages, 2 figures. Uses axodraw.sty, include
Supersymmetric Contributions to Weak Decay Correlation Coefficients
We study supersymmetric contributions to correlation coefficients that
characterize the spectral shape and angular distribution for polarized muon-
and beta-decays. In the minimal supersymmetric Standard Model (MSSM), one-loop
box graphs containing superpartners can give rise to non-(V-A)x(V-A) four
fermion operators in the presence of left-right or flavor mixing between
sfermions. We analyze the present phenomenological constraints on such mixing
and determine the range of allowed contributions to the weak decay correlation
coefficients. We discuss the prospective implications for future muon- and
beta-decay experiments, and argue that they may provide unique probes of
left-right mixing in the first generation scalar fermion sector.Comment: Revised version - to appear in Phys.Rev.
Subleading corrections to parity-violating pion photoproduction
We compute the photon asymmetry Bγ for near threshold parity-violating (PV) pion photoproduction through subleading order. We show that subleading contributions involve a new combination of PV couplings not included in previous analyses of hadronic PV. We argue that existing constraints on the leading order contribution to Bγ—obtained from the PV γ-decay of 18F—suggest that the impact of the subleading contributions may be more significant than expected from naturalness arguments
Chiral Symmetry and the Parity-Violating Yukawa Coupling
We construct the complete SU(2) parity-violating (PV)
interaction Lagrangian with one derivative, and calculate the chiral
corrections to the PV Yukawa coupling constant through in the leading order of heavy baryon expansion. We
discuss the relationship between the renormalized \hpi, the measured value of
\hpi, and the corresponding quantity calculated microscopically from the
Standard Model four-quark PV interaction.Comment: RevTex, 26 pages + 5 PS figure
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