1,287 research outputs found

    Model independent analysis of top quark forward-backward asymmetry at the Tevatron up to \mathcal{O}(\as^2/\Lambda^2)

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    We present the complete calculations of the forward-backward asymmetry (AFBA_{\rm FB}) and the total cross section of top quark pair production induced by dimension-six four quark operators at the Tevatron up to \mathcal{O}(\as^2/\Lambda^2). Our results show that next-to-leading order (NLO) QCD corrections can change AFBA_{\rm FB} and the total cross section by about 10%. Moreover, NLO QCD corrections reduce the dependence of AFBA_{\rm FB} and total cross section on the renormalization and factorization scales significantly. We also evaluate the total cross section and the charge asymmetry (ACA_{\rm C}) induced by these operators at the Large Hadron Collider (LHC) up to \mathcal{O}(\as^2/\Lambda^2), for the parameter space allowed by the Tevatron data. We find that the value of ACA_{\rm C} induced by these operators is much larger than SM prediction, and LHC has potential to discover these NP effects when the measurement precision increases.Comment: 25 pages, 10 figures; final version in PR

    (Z)3,4,5,4'-trans-tetramethoxystilbene, a new analogue of resveratrol, inhibits gefitinb-resistant non-small cell lung cancer via selectively elevating intracellular calcium level.

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    Calcium is a second messenger which is required for regulation of many cellular processes. However, excessive elevation or prolonged activation of calcium signaling would lead to cell death. As such, selectively regulating calcium signaling could be an alternative approach for anti-cancer therapy. Recently, we have identified an effective analogue of resveratrol, (Z)3,4,5,4′-trans-tetramethoxystilbene (TMS) which selectively elevated the intracellular calcium level in gefitinib-resistant (G-R) non-small-cell lung cancer (NSCLC) cells. TMS exhibited significant inhibitory effect on G-R NSCLC cells, but not other NSCLC cells and normal lung epithelial cells. The phosphorylation and activation of EGFR were inhibited by TMS in G-R cells. TMS induced caspase-independent apoptosis and autophagy by directly binding to SERCA and causing endoplasmic reticulum (ER) stress and AMPK activation. Proteomics analysis also further confirmed that mTOR pathway, which is the downstream of AMPK, was significantly suppressed by TMS. JNK, the cross-linker of ER stress and mTOR pathway was significantly activated by TMS. In addition, the inhibition of JNK activation can partially block the effect of TMS. Taken together, TMS showed promising anti-cancer activity by mediating calcium signaling pathway and inducing apoptosis as well as autophagy in G-R NSCLC cells, providing strategy in designing multi-targeting drug for treating G-R patients

    Correlations in Two-Dimensional Vortex Liquids

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    We report on a high temperature perturbation expansion study of the superfluid-density spatial correlation function of a Ginzburg-Landau-model superconducting film in a magnetic field. We have derived a closed form which expresses the contribution to the correlation function from each graph of the perturbation theory in terms of the number of Euler paths around appropriate subgraphs. We have enumerated all graphs appearing out to 10-th order in the expansion and have evaluated their contributions to the correlation function. Low temperature correlation functions, obtained using Pad\'{e} approximants, are in good agreement with Monte Carlo simulation results and show that the vortex-liquid becomes strongly correlated at temperatures well above the vortex solidification temperature.Comment: 18 pages (RevTeX 3.0) and 4 figures, available upon request, IUCM93-01

    Aggregation‐induced emission luminogen: A new perspective in the photo‐degradation of organic pollutants

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    Both the variety and uniqueness of organic semiconductors has contributed to the rapid development of environmental engineering applications and renewable fuel production, typified by the photodegradation of organic pollutants or water splitting. This paper presents a rare example of an aggregation‐induced emission luminogen as a highly efficient photocatalyst for pollutant decomposition in an environmentally relevant application. Under irradiation, the tetraphenylethene‐based AIEgen (TPE‐Ca) exhibited high photo‐degradation efficiency of up to 98.7% of Rhodamine B (RhB) in aqueous solution. The possible photocatalytic mechanism was studied by electron paramagnetic resonance and X‐ray photoelectron spectroscopy spectra, electrochemistry, thermal imaging technology, ultra‐performance liquid chromatography and high‐definition mass spectrometry, as well as by density functional theory calculations. Among the many diverse AIEgens, this is the first AIEgen to be developed as a photocatalyst for the degradation of organic pollutants. This research will open up new avenues for AIEgens research, particularly for applications of environmental relevance

    Renormalization Group Running of Lepton Mixing Parameters in See-Saw Models with S4S_4 Flavor Symmetry

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    We study the renormalization group running of the tri-bimaximal mixing predicted by the two typical S4S_4 flavor models at leading order. Although the textures of the mass matrices are completely different, the evolution of neutrino mass and mixing parameters is found to display approximately the same pattern. For both normal hierarchy and inverted hierarchy spectrum, the quantum corrections to both atmospheric and reactor neutrino mixing angles are so small that they can be neglected. The evolution of the solar mixing angle θ12\theta_{12} depends on tanβ\tan\beta and neutrino mass spectrum, the deviation from its tri-bimaximal value could be large. Taking into account the renormalization group running effect, the neutrino spectrum is constrained by experimental data on θ12\theta_{12} in addition to the self-consistency conditions of the models, and the inverted hierarchy spectrum is disfavored for large tanβ\tan\beta. The evolution of light-neutrino masses is approximately described by a common scaling factor.Comment: 23 pages, 6figure

    Probing the isospin dependent mean field and nucleon nucleon cross section in the medium by the nucleon emissions

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    We study the isospin effects of the mean field and two-body collision on the nucleon emissions at the intermediate energy heavy ion collisions by using an isospin dependent transport theory. The calculated results show that the nucleon emission number NnN_{n} depends sensitively the isospin effect of nucleon nucleon cross section and weakly on the isospin dependent mean field for neutron-poor system in higher beam energy region . In particular, the correlation between the medium correction of two-body collision and the momentum dependent interaction enhances the dependence of nucleon emission number NnN_{n} on the isospin effect of nucleon nucleon cross section. On the contrary, the ratio of the neutron proton ratio of the gas phase to the neutron proton ratio of the liquid phase, i.e., the degree of isospin fractionation b/b_{b}/_{b} depends sensitively on the isospin dependent mean field and weakly on the isospin effect of two-body collision for neutron-rich system in the lower beam energy region. In this case, NnN_{n} and b/b_{b}/_{b} are the probes for extracting the information about the isospin dependent nucleon nucleon cross section in the medium and the isospin dependent mean field,respectively.Comment: 4 pages,4 figure

    Lepton flavor violation two-body decays of quarkoniums

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    In this paper we firstly study various model-independent bounds on lepton flavor violation (LFV) in processes of J/ΨJ/\Psi, Ψ\Psi' and Υ\Upsilon two-body decays, then calculate their branch ratios % By using the constraints from other ways, we obtain %the indirect bounds of Br(J/Ψ,Ψ,Υll){\rm Br} (J/\Psi,\Psi',\Upsilon \to ll') in models of the leptoquark, RR violating MSSM and topcolor assisted technicolor(TC2) models.Comment: 14 pages, 4 figures, submitted to PR
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