343 research outputs found
Final State Interactions and CP Violation in
Using chiral perturbation theory we calculate the imaginary parts of the form factors that arise from and
rescattering. We discuss their influence on CP violating variables in .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 and
. The correct hierarchies are reproduced only when
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 meV, and mixing of the order of 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 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 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, . 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 . 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
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