Lepton flavor violation in lopsided models and a neutrino mass model

A widely adopted theoretical scheme to account for the neutrino oscillation phenomena is the see-saw mechanism together with the ``lopsided'' mass matrices, which is generally realized in the framework of supersymmetric grand unification. We will show that this scheme leads to large lepton flavor violation at low energy if supersymmetry is broken at the GUT or Plank scale. Especially, the branching ratio of $\mu\to e\gamma$ already exceeds the present experimental limit. We then propose a phenomenological model, which can account for the LMA solution to the solar neutrino problem and at the same time predict branching ratio of $\mu\to e\gamma$ below the present limit.Comment: 15 pages, 4 figure

Cosmic e^\pm, \bar p, \gamma and neutrino rays in leptocentric dark matter models

Dark matter annihilation is one of the leading explanations for the recently observed $e^\pm$ excesses in cosmic rays by PAMELA, ATIC, FERMI-LAT and HESS. Any dark matter annihilation model proposed to explain these data must also explain the fact that PAMELA data show excesses only in $e^\pm$ spectrum but not in anti-proton. It is interesting to ask whether the annihilation mode into anti-proton is completely disallowed or only suppressed at low energies. Most models proposed have negligible anti-protons in all energy ranges. We show that the leptocentric $U(1)_{B-3L_i}$ dark matter model can explain the $e^\pm$ excesses with suppressed anti-proton mode at low energies, but at higher energies there are sizable anti-proton excesses. Near future data from PAMELA and AMS can provide crucial test for this type of models. Cosmic $\gamma$ ray data can further rule out some of the models. We also show that this model has interesting cosmic neutrino signatures.Comment: Latex 20 pages and five figures. References adde

Perspective of Galactic dark matter subhalo detection on Fermi from the EGRET observation

The perspective of the detectability of Galactic dark matter subhaloes on the Fermi satellite is investigated in this work. Under the assumptions that dark matter annihilation accounts for the "GeV excess" of the Galactic diffuse $\gamma$-rays discovered by EGRET and the $\gamma$-ray flux is dominated by the contribution from subhaloes of dark matter, we calculate the expected number of dark matter subhaloes that Fermi may detect. We show that Fermi may detect a few tens to several hundred subhaloes in 1-year all sky survey. Since EGRET observation is taken as a normalization, this prediction is independent of the particle physics property of dark matter. The uncertainties of the prediction are discussed in detail. We find that the major uncertainty comes from the mass function of subhaloes, i.e., whether the subhaloes are "point like" (high-mass rich) or "diffuse like" (low-mass rich). Other uncertainties like the background estimation and the observational errors will contribute a factor of $2\sim 3$.Comment: 16 pages, 4 figures and 1 table, accepted for publication in Chinese Physics

Diffuse γ\gamma-rays and pˉ\bar{p} flux from dark matter annihilation -- a model for consistent results with EGRET and cosmic ray data

In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\gamma$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $\gamma$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuation for the proton energy loss is negligible. The dark matter annihilation signals are `boosted' after taking the contribution from subhalos into account. Another interesting feature of the model is that it gives better description of the diffuse $\gamma$ rays when taking the source distribution compatible with supernova remnants data, which is different from previous studies.Comment: 29 pages, 13 figures; the published versio

Genomic Characterization Of Sarcomatoid Transformation In Clear Cell Renal Cell Carcinoma

The presence of sarcomatoid features in renal cell carcinoma (ccRCC) confers a poor prognosis. The mechanisms that account for these sarcomatoid features are unknown. We performed whole exome sequencing of matched normal-carcinomatous-sarcomatoid specimens from 21 subjects. Two tumors had hypermutation and a mutational signature consistent with mismatch repair deficiency. In the remaining 19 tumors, sarcomatoid and carcinomatous elements shared a mean of 45/108 (41.7%) somatic single nucleotide variants (SSNVs). Sarcomatoid elements had a higher overall SSNV burden (mean 90 vs 63 SSNVs, p=4.0x10-4), increased frequency of non-synonymous SSNVs in Pan-Cancer genes (mean 1.4 vs 0.26, p=0.002), and increased frequency of loss of heterozygosity across the genome (median 913 vs 460 Mb in LOH, p \u3c 0.05), with significant recurrent segments of LOH on chromosomes 1p, 9, 10, 14, 17p, 18, and 22. The most frequent somatic mutations shared by carcinomatous and sarcomatoid elements were in known ccRCC genes (VHL, PBRM1, SETD2, PTEN). Most interestingly, sarcomatoid elements acquired new bi-allelic TP53 mutations in 32% of tumors (p=5.47x10-17); TP53 mutations were absent in carcinomatous elements in non-hypermutated tumors and rare in previously studied ccRCCs. Mutations in known cancer drivers ARID1A and BAP1 were significantly mutated in sarcomatoid elements, and were mutually exclusive with TP53 and each other. Additionally, LOH on chromosome 9 was found in all TP53-mutant tumors. These findings demonstrate that sarcomatoid elements arise from dedifferentiation of carcinomatous ccRCCs and implicate specific genes in this process. These findings have implications for the treatment of patients with these poor-prognosis cancers