Patterns of Spontaneous Chiral Symmetry Breaking in Vectorlike Gauge Theories

It has been conjectured that spontaneous chiral symmetry breaking in strongly coupled vectorlike gauge theories falls into only three different classes, depending on the gauge group and the representations carried by the fermions. We test this proposal by studying SU(2), SU(3) and SU(4) lattice gauge theories with staggered fermions in different irreducible representations. Staggered fermions away from the continuum limit should, for all complex representations, still belong to the continuum class of spontaneous symmetry breaking. But for all real and pseudo-real representations we show that staggered fermions should belong to incorrect symmetry breaking classes away from the continuum, thus generalizing previous results. As an unambiguous signal for whether chiral symmetry breaks, and which breaking pattern it follows, we look at the smallest Dirac eigenvalue distributions. We find that the patterns of symmetry breaking are precisely those conjectured.Comment: LaTeX, 17 pages. Typos in eq (17) correcte

Improved KL->pi e nu Form Factor and Phase Space Integral with Reduced Model Uncertainty

Using the published KTeV sample of 2 million KL-> pi e nu decays and a new form factor expansion with a rigorous bound on higher order terms, we present a new determination of the KL->pi e nu form factor and phase space integral. Compared to the previous KTeV result, the uncertainty in the new form factor expansion is negligible and results in an overall uncertainty in the phase space integral (IKe) that is a factor of two smaller: IKe = 0.15392 +- 0.00048 \.Comment: 3 pages, 2 figures, submitted to PRD Rapid Communicatio

Proximity to Sports Facilities and Sports Participation for Adolescents in Germany

Objectives - To assess the relationship between proximity to specific sports facilities and participation in the corresponding sports activities for adolescents in Germany. Methods - A sample of 1,768 adolescents aged 11–17 years old and living in 161 German communities was examined. Distances to the nearest sports facilities were calculated as an indicator of proximity to sports facilities using Geographic Information Systems (GIS). Participation in specific leisure-time sports activities in sports clubs was assessed using a self-report questionnaire and individual-level socio-demographic variables were derived from a parent questionnaire. Community-level socio-demographics as covariates were selected from the INKAR database, in particular from indicators and maps on land development. Logistic regression analyses were conducted to examine associations between proximity to the nearest sports facilities and participation in the corresponding sports activities. Results - The logisitic regression analyses showed that girls residing longer distances from the nearest gym were less likely to engage in indoor sports activities; a significant interaction between distances to gyms and level of urbanization was identified. Decomposition of the interaction term showed that for adolescent girls living in rural areas participation in indoor sports activities was positively associated with gym proximity. Proximity to tennis courts and indoor pools was not associated with participation in tennis or water sports, respectively. Conclusions - Improved proximity to gyms is likely to be more important for female adolescents living in rural areas

Determination of the Parity of the Neutral Pion via the Four-Electron Decay

We present a new determination of the parity of the neutral pion via the double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511 candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi^0 parity, and place a limit on scalar contributions to the pi^0 -> e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The pi^0 gamma* gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi^0 -> e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).Comment: 5 pages, 4 figures. Typographical error in radiative branching ratio (Eq. 6) correcte

Measurements of the Decay KL→e+e−γK_L \to e^+e^-\gamma

The E799-II (KTeV) experiment at Fermilab has collected 83262 $K_L \to e^+e^-\gamma$ events above a background of 79 events. We measure a decay width, normalized to the $K_L \to \pi^0\pi^0\pi^0_D$ (\pi^0 \to \gamma\gamma, \pi^0 to \gamma\gamma, \pi^0_D \to e^+e^-\gamma) decay width, of $\Gamma($K_L \to e^+e^-\gamma$)/\Gamma(K_L \to \pi^0\pi^0\pi^0_D) = (1.3302 \pm 0.0046_{stat} \pm 0.0102_{syst}) \times 10^{-3}$. We also measure parameters of two $K_L \gamma^{\ast}\gamma$ form factor models. In the Bergstrom, Masso, and Singer (BMS) parametrization, we find \caks = -0.517 \pm 0.030_{stat} \pm 0.022_{syst}. We separately fit for the first parameter of the D'Ambrosio, Isidori, and Portoles (DIP) model and find \adip = -1.729 \pm 0.043_{stat} \pm 0.028_{syst}.Comment: 5 pages, 3 figures, submitted to PR

Detailed Study of the KL -> 3pi0 Dalitz Plot

Using a sample of 68 million KL -> 3pi0 decays collected in 1996-1999 by the KTeV (E832) experiment at Fermilab, we present a detailed study of the KL -> 3pi0 Dalitz plot density. We report the first observation of interference from KL->pi+pi-pi0 decays in which pi+pi- rescatters to 2pi0 in a final-state interaction. This rescattering effect is described by the Cabibbo-Isidori model, and it depends on the difference in pion scattering lengths between the isospin I=0 and I=2 states, a0-a2. Using the Cabibbo-Isidori model, we present the first measurement of the KL-> 3pi0 quadratic slope parameter that accounts for the rescattering effect.Comment: accepted by Phys. Rev

A Measurement of the K0 Charge Radius and a CP Violating Asymmetry Together with a Search for CP Violating E1 Direct Photon Emission in the Rare Decay KL->pi+pi-e+e-

Using the complete KTeV data set of 5241 candidate KL->pi+pi-e+e- decays (including an estimated background of 204+-14 events), we have measured the coupling gCR=0.163+- 0.014(stat)+-0.023(syst) of the CP conserving charge radius process and from it determined a K0 charge radius of (K0)=(-0.077+-0.007(stat)+-0.011(syst)) fm**2. We have also determined a first experimental upper limit of 0.04 (90% CL) for the ratio |g_{E1}|/|g_{M1}| of the coupling for the E1 direct photon emission process relative to the coupling for M1 direct photon emission process. We also report the measurement of its associated vector form factor |gM1`|(1+ (a_1/a_2)/(M(rho)**2-M(K)**2)+2M(K)E(gamma*)) where |gM1`|=(1.11+- 0.12(stat)+-0.08(syst) and a_1/a_2 = (-0.744+-0.027(stat)0.032(syst)) GeV**2/c**2. In addition, a measurement of the manifestly CP violating asymmetry of magnitude (13.6+- 1.4+-(stat)+-1.5(syst))% in the CP and T odd angle phi between the decay planes of the e+e- and pi+pi- pairs in the KL center of mass system is reported

Search for the Rare Decay K_{L}\to\pi^{0}\pi^{0}\gamma

The KTeV E799 experiment has conducted a search for the rare decay $K_{L}\to\pi^{0}\pi^{0}\gamma$ via the topology $K_{L}\to\pi^{0}\pi^{0}_D\gamma$ (where $\pi^0_D\to\gamma e^+e^-$). Due to Bose statistics of the $\pi^0$ pair and the real nature of the photon, the $K_{L}\to\pi^{0}\pi^{0}\gamma$ decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level $O(p^4)$. Therefore, this mode probes chiral perturbation theory at $O(p^6)$. In this paper we report a determination of an upper limit of $2.43\times 10^{-7}$ (90% CL) for $K_{L}\to\pi^{0}\pi^{0}\gamma$. This is approximately a factor of 20 lower than previous results.Comment: six pages and six figures in the submission. Reformatted for Physics Review

Search for the Rare Decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-

The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \bar{d}sX0 coupling is completely real