Flat Higgs Potential from Planck Scale Supersymmetry Breaking

The observed Higgs boson mass poses a new puzzle in addition to the longstanding problem of the origin of the electroweak scale; the shallowness of the Higgs potential. The Higgs quartic coupling even seems to vanish at around the Planck scale within the uncertainties of the top quark mass and the strong gauge coupling. We show that the shallowness of the Higgs potential might be an outcome of supersymmetry breaking at around the Planck scale. There, the electroweak fine-tuning in the Higgs quadratic terms leads to an almost vanishing quartic coupling at around the Planck scale.Comment: 4 pages, 2 figure

Wino Dark Matter in light of the AMS-02 2015 Data

The AMS-02 collaboration has recently reported the antiproton to proton ratio with improved accuracy. In view of uncertainties of the production and the propagation of the cosmic rays, the observed ratio is still consistent with the secondary astrophysical antiproton to proton ratio. However, it is nonetheless enticing to examine whether the observed spectrum can be explained by a strongly motivated dark matter, the wino dark matter. As we will show, we find that the antiproton flux from the wino annihilation can explain the observed spectrum well for its mass range 2.5-3 TeV. The fit to data becomes particularly well compared to the case without the annihilation for the thermal wino dark matter case with a mass about 3 TeV. The ratio is predicted to be quickly decreased at the energy several hundreds of GeV, if this possibility is true, and it will be confirmed or ruled out in near future when the AMS-02 experiment accumulates enough data at this higher energy region.Comment: 6 pages, 2 figures, version accepted for publication in PRD (Rapid Communication

Mass of Decaying Wino from AMS-02 2014

We revisit the decaying wino dark matter scenario in the light of the updated positron fraction, electron and positron fluxes in cosmic ray recently reported by the AMS-02 collaboration. We show the AMS-02 results favor the mass of the wino dark matter at around a few TeV, which is consistent with the prediction on the wino mass in the pure gravity mediation model.Comment: 10 pages, 1 figur

A scenario of heavy but visible baryonic dark matter

We consider a model in which dark matter is a composite baryon of a dark sector governed by $SU(3)$ gauge theory, with vector-like quarks also charged under $U(1)_Y$. The model provides simple answer to the dark matter stability problem: it is a result of the accidental dark baryon number conservation. And with an analogy to QCD, all physical quantities of the dark matter can be calculated by rescaling the QCD experimental results. According to the thermal freeze-out mechanism the mass of the dark matter is predicted to be $\mathcal{O}(100)$~TeV in order to achieve a correct relic abundance. Such heavy dark matter is in general hard for detection due to small dark matter number density in the universe. However, dark baryon number in our model is not necessarily strictly preserved thanks to operators suppressed by the Planck scale, and such decay operator results in a decay lifetime marginal to the current detection bound. We show our model with $\mathcal{O}(10^{27})~s$ dark matter decay life time can explain the AMS-02 anti-proton data, if it is experimentally interpreted as an access, although some theoretical uncertainty may weaken its significance. We also investigate other phenomena of this model such as the extragalactic gamma ray and neutrino signatures.Comment: 14 pages, 43 figures, published in JHE

Sortase A-assisted metabolic enzyme ligation in Escherichia coli

We demonstrated the metabolic enzyme ligation by sortase A-mediated ligation (sortagging) for the redirection of metabolic flux thorough metabolic channeling. Staphylococcal sortase A (SrtA) is utilized for the ligation of metabolic enzymes. SrtA is transpeptidase, which recognizes Leu-Pro-Xaa-Thr-Gly sequences (LP tag) and cleaves between Thr and Gly, and subsequently links amino group of oligoglycine (G tag) thorough a native peptide bond. Sortagging enables to conjugate protein with other molecules in a site-specific manner. Minimal modifications of protein with short peptide tags; LP tag and G tag are only required for site-specific ligation. Hence, sortagging has been utilized for preparing a variety of bioconjugation not only in vitro but also in vivo.1 In current study, we hypothesize that SrtA-mediated metabolic enzyme ligation in cytoplasm of Escherichia coli facilitates processing metabolic intermediate, and redirects metabolic fluxes to desired pathway. As proof of concept, we constructed acetate producing E. coli with engineered endogenous metabolic pathway, which redirect central metabolic fluxes to acetate producing flux by the induction of chemical additives (Figure 1). The expression of SrtA was controlled by Lac operating promoter, metabolic channeling was videlicet occurred by the addition of IPTG. Acetyl-CoA was chosen as the intermediate model because acetyl-CoA is one of the most important central metabolic intermediates, which is converted to alcohols, fatty acids, and mevalonate derivatives. In this study, we tested covalent linking of pyruvate-formate lyase and phosphate acetyltransferase by sortase A-mediated ligation and evaluated the production of acetate. The time point of addition of IPTG was not critical for facilitating metabolic enzyme ligation, and acetate production increased upon expression of sortase A. These results show that sortase A-mediated enzyme ligation enhances an acetate-producing flux in E. coli. We have validated that sortase A-mediated enzyme ligation offers a metabolic channeling approach to redirect a central flux to a desired flux.2 Please click Additional Files below to see the full abstract