Accidental Goldstone Bosons

We study vacuum alignment in theories in which the chiral symmetry of a set of massless fermions is both spontaneously and explicitly broken. We find that transitions occur between different phases of the fermions' CP symmetry as parameters in their symmetry breaking Hamiltonian are varied. We identify a new phase that we call pseudoCP-conserving. We observe first and second-order transitions between the various phases. At a second-order (and possibly first-order) transition a pseudoGoldstone boson becomes massless as a consequence of a spontaneous change in the discrete, but not the continuous, symmetry of the ground state. We relate the masslessness of these ``accidental Goldstone bosons'' (AGBs) bosons to singularities of the order parameter for the phase transition. The relative frequency of CP-phase transitions makes it commonplace for the AGBs to be light, much lighter than their underlying strong interaction scale. We investigate the AGBs' potential for serving as light composite Higgs bosons by studying their vacuum expectation values, finding promising results: AGB vevs are also often much less than their strong scale.Comment: 27 pages, latex, with 12 postscript figure

An Effective Lagrangian for Low-Scale Technicolor

We present an effective Lagrangian for low-scale technicolor. It describes the interactions at energies near the mass of the lowest-lying bound states of the lightest technifermion doublet -- the spin-one $\rho_T,\omega_T, a_T, f_T$ and the corresponding technipions $\pi_T$. This Lagrangian is intended to put on firmer ground the technicolor straw-man phenomenology used for collider searches of low-scale technicolor. The technivectors are described using the hidden local symmetry (HLS) formalism of Bando et al. The Lagrangian is based on $SU(2)\otimes U(1)\otimes U(2)_L \otimes U(2)_R$, where $SU(2)\otimes U(1)$ is the electroweak gauge group and $U(2)_L \otimes U(2)_R$ is the HLS gauge group. Special attention is paid to the higher-derivative standard HLS and Wess-Zumino-Witten interactions needed to describe radiative and other decays of the $a_T$ and $\rho_T/\omega_T$, respectively.Comment: Updated introduction, to appear in Phys. Rev.

CP violation and mixing in technicolor models

Vacuum alignment in technicolor models provides an attractive origin for the quarks' CP violation and, possibly, a natural solution for the strong-CP problem of QCD. We discuss these topics in this paper. Then we apply them to determine plausible mixing matrices for left and right-handed quarks. These matrices determine the Cabibbo-Kobayashi-Maskawa matrix as well as new mixing angles and phases that are observable in extended technicolor (ETC) and topcolor (TC2) interactions. We determine the contributions of these new interactions to CP-violating and mixing observables in the K0, Bd and Bs systems. Consistency with mixing and CP violation in the K0 system requires assuming that ETC interactions are electroweak generation-conserving even if technicolor has a walking gauge coupling. Large ETC gauge boson masses and small intergenerational mixing then result in negligibly small ETC contributions to B-meson mixing and CP violation and to Re(ϵ′/ϵ). We confirm our earlier strong lower bounds on TC2 gauge boson masses from Bd–¯¯¯Bd mixing. We then pay special attention to the possibility that current experiments indicate a deviation from standard model expectations of the values of sin2β measured in Bd→J/ψKS, ϕKS, η′KS, and πKS, studying the ability of TC2 to account for these. We also determine the TC2 contribution to ΔMBs and to Re(ϵ′/ϵ), and find them to be appreciable.First author draf

Space Station Freedom solar array panels plasma interaction test facility

The Space Station Freedom Power System will make extensive use of photovoltaic (PV) power generation. The phase 1 power system consists of two PV power modules each capable of delivering 37.5 KW of conditioned power to the user. Each PV module consists of two solar arrays. Each solar array is made up of two solar blankets. Each solar blanket contains 82 PV panels. The PV power modules provide a 160 V nominal operating voltage. Previous research has shown that there are electrical interactions between a plasma environment and a photovoltaic power source. The interactions take two forms: parasitic current loss (occurs when the currect produced by the PV panel leaves at a high potential point and travels through the plasma to a lower potential point, effectively shorting that portion of the PV panel); and arcing (occurs when the PV panel electrically discharges into the plasma). The PV solar array panel plasma interaction test was conceived to evaluate the effects of these interactions on the Space Station Freedom type PV panels as well as to conduct further research. The test article consists of two active solar array panels in series. Each panel consists of two hundred 8 cm x 8 cm silicon solar cells. The test requirements dictated specifications in the following areas: plasma environment/plasma sheath; outgassing; thermal requirements; solar simulation; and data collection requirements

Technicolor at the Tevatron

We propose that the 3.2 sigma excess at ~150 GeV in the dijet mass spectrum of W + jets reported by CDF is the technipion $\pi_T$ of low-scale technicolor. Its relatively large cross section is due to production of a narrow $Wjj$ resonance, the technirho, which decays to W + $\pi_T$. We discuss ways to enhance and strengthen the technicolor hypothesis and suggest companion searches at the Tevatron and LHC.Comment: 5 pages, 6 figures. Note added regarding Z(l+l-)+jj signals at the Tevatron and LH

Testing the Technicolor Interpretation of CDF's Dijet Excess at the LHC

Under the assumption that the dijet excess seen by the CDF Collaboration near 150 Gev in Wjj production is due to the lightest technipion of the low-scale technicolor process $\rho_T \rightarrow W \pi_T$, we study its observability in LHC detectors with 1--20 inverse femtobarns of data. We describe interesting new kinematic tests that can provide independent confirmation of this LSTC hypothesis. We find that cuts similar to those employed by CDF, and recently by ATLAS, cannot confirm the dijet signal. We propose cuts tailored to the LSTC hypothesis and its backgrounds at the LHC that may reveal $\rho_T \rightarrow \ell\nu jj$. Observation of the isospin-related channel $\rho^{pm}_T \rightarrow Z \pi^{pm}_T \rightarrow \ell^+ \ell^- jj$ and of $\rho^{pm}_T \rightarrow WZ$ in the three lepton plus neutrino and dilepton plus dijet modes will be important confirmations of the LSTC interpretation of the CDF signal. The $Z\pi_T$ channel is experimentally cleaner than $W\pi_T$ and its rate is known from $W\pi_T$ by phase space. It can be discovered or excluded with the collider data expected in 2012. The $WZ \rightarrow 3\ell\nu$ channel is cleanest of all and its rate is determined from $W\pi_T$ and the LSTC parameter $\sin\chi$. This channel and $WZ \rightarrow \ell^+\ell^- jj$ are discussed as a function of $\sin\chi$.Comment: 24 pages, 24 figure