Final State Interactions and CP Violation in KL→π+π−e+e−K_L \to \pi^+ \pi^- e^+ e^-

Using chiral perturbation theory we calculate the imaginary parts of the $K_L \rightarrow \pi^+ \pi^- e^+ e^-$ form factors that arise from $\pi \pi \rightarrow \pi^+ \pi^-$ and $\pi \pi \rightarrow \pi^+ \pi^- \gamma^*$ rescattering. We discuss their influence on CP violating variables in $K_L \rightarrow \pi^+ \pi^- e^+ e^-$.Comment: ; 12 pages, 2 figures, TeX format; uses epsf.tex, tables.tex, and phyzzx.te

Stage at diagnosis and cancer survival for Indigenous Australians in the Northern Territory

Objective: To investigate whether Indigenous Australians with cancer have more advanced disease at diagnosis than other Australians, and whether late diagnosis explains lower Indigenous cancer survival rates. Design: Retrospective cohort study. Setting and participants: Indigenous and non-Indigenous people diagnosed with cancers of the colon and rectum, lung, breast or cervix and non-Hodgkin lymphoma in the Northern Territory of Australia in 1991–2000. Main outcome measures: SEER summary stage of cancer at diagnosis (local, regional or distant spread), cause-specific cancer survival rates and relative risk of cancer death. Results: Diagnosis with advanced disease (regional or distant spread) was more common for Indigenous people (70%; 95% CI, 62%–78%) than for non-Indigenous people (51%; 95% CI, 53%–59%) with cancers of the colon and rectum, breast, cervix and non-Hodgkin lymphoma, but for lung cancer the opposite was found (Indigenous, 56% [95% CI, 46%–65%] v non-Indigenous, 69% [95% CI, 64%–75%]). Stage-adjusted survival rates were lower for Indigenous people for each cancer site. With few exceptions, the relative risk of cancer death was higher for Indigenous people for each category of stage at diagnosis for each cancer site. Conclusions: Health services apparently could, and should, be performing better for Indigenous people with cancer in the Northern Territory, and probably elsewhere in Australia. This study has demonstrated that data from cancer registers, enhanced with data on stage at diagnosis, can be used to monitor health service performance for Indigenous Australians in the Northern Territory; similar data is available in other States, and could be used to monitor health service performance for Indigenous people throughout Australia

A Model of Yukawa Hierarchies

We present a model for the observed hierarchies among the Yukawa couplings of the standard model in the context of an effective low energy theory with an anomalous U(1) symmetry. This symmetry, a generic feature of superstring compactification, is a remnant of the Green-Schwarz anomaly cancellation mechanism. The gauge group is that of the standard model, augmented by X, the anomalous U(1), and two family-dependent phase symmetries $Y^{(1)}$ and $Y^{(2)}$. The correct hierarchies are reproduced only when $sin^2\theta_w=3/8$ at the cut-off. To cancel anomalies, right-handed neutrinos and other standard model singlets must be introduced. Independently of the charges of the right-handed neutrinos, this model produces the same neutrino mixing matrix and an inverted hierarchy of neutrino masses. The heaviest is the electron neutrino with a mass $\sim 1$ meV, and mixing of the order of $\lambda_c^3$ with each of the other two neutrinos.Comment: 15 pages, no figures, LaTex. Revised version, containing minor typographical corrections, as well as a substantial revision of the final three paragraphs of the text. Submitted to Physics Letters

Final-state interactions and CP violation in KL→π+π- e+e-

Using chiral perturbation theory we calculate the imaginary parts of the KL→π+π-e+e- form factors that arise from ππ→π+π- and ππ→π+π-γ* rescattering. We discuss their influence on CP-violating variables in KL→π+π-e+e-

Excited Charmed Baryon Decays and Their Implications for Fragmentation Parameters

The production of the excited charmed baryon doublet $\Lambda_c^*$ via fragmentation is studied. An analysis of the subsequent hadronic decays of the doublet within the framework of heavy hadron chiral perturbation theory produces expressions for both the angular distribution of the decay products and the polarization of the final state heavy baryon in terms of various nonperturbative fragmentation parameters. Future experimental investigation of this system will determine these parameters. In addition, recent experimental results are shown to fix one of the parameters in the heavy hadron chiral Lagrangian.Comment: 23 Pages, including 6 figs., in TeX; uses harvmac.tex, epsf.tex, and tables.te

Exotic leptoquarks from superstring derived models

The H1 and ZEUS collaborations have recently reported a significant excess of events at high $Q^2$ in positron-proton collisions. While there exists insufficient data to conclusively determine the origin of this excess, one possibility is that it is due to a new leptoquark at mass scale around 200 GeV. We examine the type of leptoquark states that exist in superstring derived standard-like models, and show that, while these models may contain the standard leptoquark states which exist in Grand Unified Theories, they also generically contain new and exotic leptoquark states with fractional lepton number, $\pm1/2$. In contrast to the traditional GUT-type leptoquark states, the couplings of the exotic leptoquarks to the Standard Model states are generated after the breaking of $U(1)_{B-L}$. This important feature of the exotic leptoquark states may result in local discrete symmetries which forbid some of the undesired leptoquark couplings. We examine these couplings in several models and study the phenomenological implications. The flavor symmetries of the superstring models are found to naturally suppress leptoquark flavor changing processes.Comment: 28 pages. Standard Latex. Final version to appear in Nuclear Physics B. Minor changes. References adde

Dynamical supersymmetry breaking in a superstring inspired model

We present a dilaton dominated scenario for supersymmetry breaking in a recently constructed realistic superstring inspired model with an anomalous U(1) symmetry. Supersymmetry is broken via gaugino condensation due to a confining SU(Nc) gauge group in the hidden sector. In particular, we find that by imposing on the model the phenomenological constraint of the absence of observed flavor changing neutral currents, there is a range of parameters related to the hidden sector and the Kahler potential for which we obtain a low energy spectrum consistent with present experimental bounds. As an illustrative example, we derive the low energy spectrum of a specific model. We find that the LSP is the lightest neutralino with a mass of 53 GeV and the lightest Higgs has a mass of 104 GeV.Comment: 13 page