Electroweak Precision Constraints on the Littlest Higgs Model with T Parity

We compute the leading corrections to the properties of W and Z bosons induced at the one-loop level in the SU(5)/SO(5) Littlest Higgs model with T parity, and perform a global fit to precision electroweak data to determine the constraints on the model parameters. We find that a large part of the model parameter space is consistent with data. Values of the symmetry breaking scale as low as 500 GeV are allowed, indicating that no significant fine tuning in the Higgs potential is required. We identify a region within the allowed parameter space in which the lightest T-odd particle, the partner of the hypercharge gauge boson, has the correct relic abundance to play the role of dark matter. In addition, we find that a consistent fit to data can be obtained for large values of the Higgs mass, up to 800 GeV, due to the possibility of a partial cancellation between the contributions to the T parameter from Higgs loops and new physics.Comment: 23 pages, 9 figures. Minor correction

Polarization Transfer in Inelastic Proton Scattering from 12-C and 16-O

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

The Intermediate Higgs

Two paradigms for the origin of electroweak superconductivity are a weakly coupled scalar condensate, and a strongly coupled fermion condensate. The former suffers from a finetuning problem unless there are cancelations to radiative corrections, while the latter presents potential discrepancies with precision electroweak physics. Here we present a framework for electroweak symmetry breaking which interpolates between these two paradigms, and mitigates their faults. As in Little Higgs theories, the Higgs is a pseudo-Nambu Goldstone boson, potentially composite. The cutoff sensitivity of the one loop top quark contribution to the effective potential is canceled by contributions from additional vector-like quarks, and the cutoff can naturally be higher than in the minimal Standard Model. Unlike the Little Higgs models, the cutoff sensitivity from one loop gauge contributions is not canceled. However, such gauge contributions are naturally small as long as the cutoff is below 6 TeV. Precision electroweak corrections are suppressed relative to those of Technicolor or generic Little Higgs theories. In some versions of the intermediate scenario, the Higgs mass is computable in terms of the masses of these additional fermions and the Nambu-Goldstone Boson decay constant. In addition to the Higgs, new scalar and pseudoscalar particles are typically present at the weak scale

A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. I. Theory

We derive an analytical approximation of nonlinear force-free magnetic field solutions (NLFFF) that can efficiently be used for fast forward-fitting to solar magnetic data, constrained either by observed line-of-sight magnetograms and stereoscopically triangulated coronal loops, or by 3D vector-magnetograph data. The derived NLFFF solutions provide the magnetic field components $B_x({\bf x})$, $B_y({\bf x})$, $B_z({\bf x})$, the force-free parameter $\alpha({\bf x})$, the electric current density ${\bf j}({\bf x})$, and are accurate to second-order (of the nonlinear force-free $\alpha$-parameter). The explicit expressions of a force-free field can easily be applied to modeling or forward-fitting of many coronal phenomena.Comment: Solar Physics (in press), 26 pages, 11 figure

Spin structure of the nucleon at low energies

The spin structure of the nucleon is analyzed in the framework of a Lorentz-invariant formulation of baryon chiral perturbation theory. The structure functions of doubly virtual Compton scattering are calculated to one-loop accuracy (fourth order in the chiral expansion). We discuss the generalization of the Gerasimov-Drell-Hearn sum rule, the Burkhardt-Cottingham sum rule and moments of these. We give predictions for the forward and the longitudinal-transverse spin polarizabilities of the proton and the neutron at zero and finite photon virtuality. A detailed comparison to results obtained in heavy baryon chiral perturbation theory is also given.Comment: 29 pp, 14 fig

A Test of the Coplanar and Far-side Features of Intermediate Energy (d,p) Reactions

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

The flavor-changing bottom-strange quark production in the littlest Higgs model with T parity at the ILC

In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the special flavor structures and some new flavor-changing (FC) couplings which could greatly enhance the production rates of the FC processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider (ILC), i.e., $e^+e^-\rightarrow b\bar{s}$ and $\gamma\gamma\rightarrow b\bar{s}$. The results show that the production rates of these processes are sizeable for the favorable values of the parameters. Therefore, it is quite possible to test the LHT model or make some constrains on the relevant parameters of the LHT through the detection of these processes at the ILC.Comment: 12 pages, 8 figure

Two photons into \pi^0\pi^0

We perform a theoretical study based on dispersion relations of the reaction \gamma\gamma\to \pi^0\pi^0 emphasizing the low energy region. We discuss how the f_0(980) signal emerges in \gamma\gamma\to \pi\pi within the dispersive approach and how this fixes to a large extent the phase of the isoscalar S-wave \gamma\gamma\to \pi\pi amplitude above the K\bar{K} threshold. This allows us to make sharper predictions for the cross section at lower energies and our results could then be used to distinguish between different \pi\pi isoscalar S-wave parameterizations with the advent of new precise data on \gamma\gamma\to\pi^0\pi^0. We compare our dispersive approach with an updated calculation employing Unitary Chiral Perturbation Theory (U\chiPT). We also pay special attention to the role played by the \sigma resonance in \gamma\gamma\to\pi\pi and calculate its coupling and width to gamma\gamma, for which we obtain \Gamma(\sigma\to\gamma\gamma)=(1.68\pm 0.15) KeV.Comment: 31 pages, 9 figure

Significant Biochemical, Biophysical and Metabolic Diversity in Circulating Human Cord Blood Reticulocytes

10.1371/journal.pone.0076062PLoS ONE810-POLN

Enhancement of the Near-Side Component in Quasi-Adiabatic Calculations of the 66-Zn(d,p)67-Zn Reaction

This research was sponsored by the National Science Foundation Grant NSF PHY-931478