Surgical Therapy for a Solitary Form of Hepatic Epithelioid Hemangioendothelioma: A Long-Term Survival Case

Hepatic epithelioid hemangioendothelioma (HEHE) is a rare neoplasm of vascular origin. The clinical presentation of HEHE is variable, and the therapeutic criteria are still unclear since its natural history is unpredictable. A 53-year-old woman was admitted to our hospital because she had a 2.5-cm diameter nodule in the segment V of the liver. She had undergone segmental hepatectomy for solitary HEHE in segment VII 10 years before. There had been no recurrence for the 10 years after the first operation. The tumor was diagnosed as a new lesion of HEHE by percutaneous needle liver biopsy, and thereafter repeated hepatectomy was performed. HEHE seems to be resistant to chemotherapy and radiotherapy. Either surgical resection or orthotopic liver transplantation is generally recommended as a curative treatment for this disease. However, HEHE tends to be detected in multiple lesions, and localized disease is rare. Therefore, the chance of resection is very low. Some reports do not recommend local resection because of early aggressive tumor spread even after curative resection. We herein demonstrate a rare case of HEHE in a patient who underwent repeated hepatectomy for a solitary lesion and who survived for 17 years. It is concluded that surgical resection is one of the most effective treatments for a solitary form of HEHE

Dirichlet Higgs as radion stabilizer in warped compactification

We study implications of generalized non-zero Dirichlet boundary condition along with the ordinary Neumann one on a bulk scalar in the Randall-Sundrum warped compactification. First we show profiles of vacuum expectation value of the scalar under the general boundary conditions. We also investigate Goldberger-Wise mechanism in several setups with the general boundary conditions of the bulk scalar field and find that the mechanism can work under non-zero Dirichlet boundary conditions with appropriate vacuum expectation values. Especially, we show that $SU(2)_R$ triplet Higgs in the bulk left-right symmetric model with custodial symmetry can be identified with the Goldberger-Wise scalar.Comment: 35 pages, 25 figures, published versio

Top Yukawa Deviation in Extra Dimension

We suggest a simple one-Higgs-doublet model living in the bulk of five-dimensional spacetime compactified on $S^1/Z_2$, in which the top Yukawa coupling can be smaller than the naive standard-model expectation, i.e. the top quark mass divided by the Higgs vacuum expectation value. If we find only single Higgs particle at the LHC and also observe the top Yukawa deviation, our scenario becomes a realistic candidate beyond the standard model. The Yukawa deviation comes from the fact that the wave function profile of the free physical Higgs field can become different from that of the vacuum expectation value, due to the presence of the brane-localized Higgs potentials. In the Brane-Localized Fermion scenario, we find sizable top Yukawa deviation, which could be checked at the LHC experiment, with a dominant Higgs production channel being the $WW$ fusion. We also study the Bulk Fermion scenario with brane-localized Higgs potential, which resembles the Universal Extra Dimension model with a stable dark matter candidate. We show that both scenarios are consistent with the current electroweak precision measurements.Comment: 61 pages, 19 figures, typos corrected, comments added, published versio

A4 Flavor Models in Split Seesaw Mechanism

A seesaw mechanism in an extra-dimension, known as the split seesaw mechanism, provides a natural way to realize a splitting mass spectrum of right-handed neutrinos. It leads to one keV sterile neutrino as a dark matter candidate and two heavy right-handed neutrinos being responsible for leptogenesis to explain the observed baryon asymmetry of the Universe. We study models based on $A_4$ flavor symmetry in the context of the split seesaw mechanism. It is pointed out that most of known $A_4$ flavor models with three right-handed neutrinos being $A_4$ triplet suffer from a degeneracy problem for the bulk mass terms, which disturbs the split mechanism for right-handed neutrino mass spectrum. Then we construct a new $A_4$ flavor model to work in the split seesaw mechanism. In the model, the experimentally observed neutrino masses and mixing angles can be realized from both type I+II seesaw contributions. The model predicts the $\mu-\tau$ symmetry in the neutrino mass matrix at the leading order, resulting in the vanishing $\theta_{13}$ and maximal $\theta_{23}$. The flavor symmetry $A_4$ is broken via the flavon vacuum alignment which can be obtained from the orbifold compactification. The model can be consistent with all data of neutrino oscillation experiments, cosmological discussions of dark matter abundance, leptogenesis, and recent astrophysical data.Comment: 21 pages, 1 figure, version to appear in JHE