15 research outputs found
A Geometry of the Generations
We propose a geometric theory of flavor based on the discrete group
, in the context of the minimal supersymmetric standard model. The
group treats three objects symmetrically, while making fundamental distinctions
between the generations. The top quark is the only heavy quark in the symmetry
limit, and the first and second generation squarks are degenerate. The
hierarchical nature of Yukawa matrices is a consequence of a sequential
breaking of .Comment: 10 pages, 1 EPS figure as uuencoded tar-compressed file, uses
psfig.st
Proton Decay in Minimal Supersymmetric SU(5)
We systematically study proton decay in the minimal supersymmetric SU(5)
grand unified theory. We find that although the available parameter space of
soft masses and mixings is quite constrained, the theory is still in accord
with experiment.Comment: 12 pages, uses axodraw.sty, few more comments, one new referenc
Supersymmetric origin of a low CP asymmetry
We show that general Minimal Supersymmetric extensions of the Standard Model
(MSSM) allow for a CP asymmetry in B --> J/psi K(S) well bellow the SM
expectations with dominant Supersymmetric contributions to epsilon_K and
epsilon'/epsilon. Indeed, we provide an explicit example of an MSSM with
non-universal soft breaking terms fully consistent with the low results of this
asymmetry recently announced by Babar and Belle collaborations.Comment: 6 pages, no figures. Reference added, typos correcte
Maximal Neutrino Mixing from a Minimal Flavor Symmetry
We study a number of models, based on a non-Abelian discrete group, that
successfully reproduce the simple and predictive Yukawa textures usually
associated with U(2) theories of flavor. These models allow for solutions to
the solar and atmospheric neutrino problems that do not require altering
successful predictions for the charged fermions or introducing sterile
neutrinos. Although Yukawa matrices are hierarchical in the models we consider,
the mixing between second- and third-generation neutrinos is naturally large.
We first present a quantitative analysis of a minimal model proposed in earlier
work, consisting of a global fit to fermion masses and mixing angles, including
the most important renormalization group effects. We then propose two new
variant models: The first reproduces all important features of the SU(5)xU(2)
unified theory with neither SU(5) nor U(2). The second demonstrates that
discrete subgroups of SU(2) can be used in constructing viable supersymmetric
theories of flavor without scalar universality even though SU(2) by itself
cannot.Comment: 34 pages LaTeX, 1 eps figure, minor revisions and references adde
Baryogenesis in Models with a Low Quantum Gravity Scale
We make generic remarks about baryogenesis in models where the scale of
quantum gravity is much below the Planck scale. These correspond to M-theory
vacua with a large volume for the internal space. Baryogenesis is a challenge,
particularly for M_s \lappeq 10^5 GeV, because there is an upper bound on the
reheat temperature of the Universe, and because certain baryon number violating
operators must be suppressed. We discuss these constraints for different values
of , and illustrate with a toy model the possibility of using horizontal
family symmetries to circumvent them.Comment: 15 pages, latex, one figure. References adde
Lepton Flavour Violating Leptonic/Semileptonic Decays of Charged Leptons in the Minimal Supersymmetric Standard Model
We consider the leptonic and semileptonic (SL) lepton flavour violating (LFV)
decays of the charged leptons in the minimal supersymmetric standard model
(MSSM). The formalism for evaluation of branching fractions for the SL LFV
charged-lepton decays with one or two pseudoscalar mesons, or one vector meson
in the final state, is given. Previous amplitudes for the SL LFV charged-lepton
decays in MSSM are improved, for instance the -penguin amplitude is
corrected to assure the gauge invariance. The decays are studied not only in
the model-independent formulation of the theory in the frame of MSSM, but also
within the frame of the minimal supersymmetric SO(10) model within which the
parameters of the MSSM are determined. The latter model gives predictions for
the neutrino-Dirac Yukawa coupling matrix, once free parameters in the model
are appropriately fixed to accommodate the recent neutrino oscillation data.
Using this unambiguous neutrino-Dirac Yukawa couplings, we calculate the LFV
leptonic and SL decay processes assuming the minimal supergravity scenario. A
very detailed numerical analysis is done to constrain the MSSM parameters.
Numerical results for SL LFV processes are given, for instance for tau -> e
(mu) pi0, tau -> e (mu) eta, tau -> e (mu) eta', tau -> e (mu) rho0, tau -> e
(mu) phi, tau -> e (mu) omega, etc.Comment: 36 pages, 3 tables, 5 .eps figure
Amplification of hypercharge electromagnetic fields by a cosmological pseudoscalar
If, in addition to the standard model fields, a new pseudoscalar field exists
and couples to hypercharge topological number density, it can exponentially
amplify hyperelectric and hypermagnetic fields in the symmetric phase of the
electroweak plasma, while coherently rolling or oscillating. We present the
equations describing the coupled system of a pseudoscalar field and hypercharge
electromagnetic fields in the electroweak plasma at temperatures above the
electroweak phase transition, discuss approximations to the equations, and
their validity. We then solve the approximate equations using assorted
analytical and numerical methods, and determine the parameters for which
hypercharge electromagnetic fields can be exponentially amplified.Comment: 14 pages, 6 figure
Global surveillance of cancer survival 1995-2009: analysis of individual data for 25,676,887 patients from 279 population-based registries in 67 countries (CONCORD-2)
BACKGROUND:
Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control.
METHODS:
Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights.
FINDINGS:
5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease.
INTERPRETATION:
International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems
Phenomenology of a new minimal supersymmetric extension of the standard model
We study the phenomenology of a new minimally extended supersymmetric standard model (nMSSM) where a gauge singlet superfield is added to the MSSM spectrum. The superpotential of this model contains no dimensionful parameters, thus solving the ? problem of the MSSM. A global discrete R symmetry, forbidding the cubic singlet self-interaction, imposed on the complete theory, guarantees its stability with respect to generated higher-order tadpoles of the singlet and solves both the domain wall and Peccei-Quinn axion problems. We give the free parameters of the model and display some general constraints on them. Particular attention is devoted to the neutralino sector where a (quasipure) singlino appears to be always the LSP of the model, leading to additional cascades, involving the NLSP ? LSP transition, compared with the MSSM. We then present the upper bounds on the masses of the lightest and next-to-lightest—when the lightest is an invisible singlet—CP-even Higgs bosons, including the full one-loop and dominant two-loop corrections. These bounds are found to be much higher than the equivalent ones in the MSSM. Finally, we discuss some phenomenological implications for the Higgs sector of the nMSSM in Higgs boson production at future hadron colliders