6,440 research outputs found

    Flavor SU(3) symmetry and QCD factorization in BPPB \to PP and PVPV decays

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    Using flavor SU(3) symmetry, we perform a model-independent analysis of charmless Bˉu,d(Bˉs)PP, PV\bar B_{u,d} (\bar B_s) \to PP, ~PV decays. All the relevant topological diagrams, including the presumably subleading diagrams, such as the QCD- and EW-penguin exchange diagrams and flavor-singlet weak annihilation ones, are introduced. Indeed, the QCD-penguin exchange diagram turns out to be important in understanding the data for penguin-dominated decay modes. In this work we make efforts to bridge the (model-independent but less quantitative) topological diagram or flavor SU(3) approach and the (quantitative but somewhat model-dependent) QCD factorization (QCDF) approach in these decays, by explicitly showing how to translate each flavor SU(3) amplitude into the corresponding terms in the QCDF framework. After estimating each flavor SU(3) amplitude numerically using QCDF, we discuss various physical consequences, including SU(3) breaking effects and some useful SU(3) relations among decay amplitudes of BˉsPV\bar B_s \to PV and BˉdPV\bar B_d \to PV.Comment: 47 pages, 3 figures, 28 table

    New Physics in Bs -> J/psi phi: a General Analysis

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    Recently, the CDF and D0 collaborations measured indirect CP violation in Bs -> J/psi phi and found a hint of a signal. If taken at face value, this can be interpreted as a nonzero phase of Bs-Bsbar mixing (beta_s), in disagreement with the standard model, which predicts that beta_s ~= 0. In this paper, we argue that this analysis may be incomplete. In particular, there can be new physics (NP) in the bbar -> sbar c cbar decay. If so, the value of beta_s is different than for the case in which NP is assumed to be present only in the mixing. We have examined several models of NP and found that, indeed, there can be significant contributions to the decay. These effects are consistent with measurements in B -> J/psi K* and Bd -> J/psi Ks. Due to the NP in the decay, polarization-dependent indirect CP asymmetries and triple-product asymmetries are predicted in Bs -> J/psi phi.Comment: 28 pages, JHEP, no figures. Considerable changes made. Abstract and main text of paper modified to alter presentation. Appendix added. References added. Conclusions unchanged

    Energy- and flux-budget (EFB) turbulence closure model for the stably stratified flows. Part I: Steady-state, homogeneous regimes

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    We propose a new turbulence closure model based on the budget equations for the key second moments: turbulent kinetic and potential energies: TKE and TPE (comprising the turbulent total energy: TTE = TKE + TPE) and vertical turbulent fluxes of momentum and buoyancy (proportional to potential temperature). Besides the concept of TTE, we take into account the non-gradient correction to the traditional buoyancy flux formulation. The proposed model grants the existence of turbulence at any gradient Richardson number, Ri. Instead of its critical value separating - as usually assumed - the turbulent and the laminar regimes, it reveals a transition interval, 0.1< Ri <1, which separates two regimes of essentially different nature but both turbulent: strong turbulence at Ri<<1; and weak turbulence, capable of transporting momentum but much less efficient in transporting heat, at Ri>1. Predictions from this model are consistent with available data from atmospheric and lab experiments, direct numerical simulation (DNS) and large-eddy simulation (LES).Comment: 40 pages, 6 figures, Boundary-layer Meteorology, resubmitted, revised versio

    Hidden local symmetry and color confinement

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    The hidden local symmetry is a successful model to describe the properties of the vector mesons in QCD. We point out that if we identify this hidden gauge theory as the magnetic picture of QCD, a linearized version of the model simultaneously describes color confinement and chiral symmetry breaking. We demonstrate that such a structure can be seen in the Seiberg dual picture of a softly broken supersymmetric QCD. The model possesses exact chiral symmetry and reduces to QCD when mass parameters are taken to be large. Working in the regime of the small mass parameters, we show that there is a vacuum where chiral symmetry is spontaneously broken and simultaneously the magnetic gauge group is Higgsed. If the vacuum we find persists in the limit of large mass parameters, one can identify the rho meson as the massive magnetic gauge boson, that is an essential ingredient for color confinement.Comment: 20 pages, 3 figure

    Effects of intermediate scales on renormalization group running of fermion observables in an SO(10) model

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    In the context of non-supersymmetric SO(10) models, we analyze the renormalization group equations for the fermions (including neutrinos) from the GUT energy scale down to the electroweak energy scale, explicitly taking into account the effects of an intermediate energy scale induced by a Pati--Salam gauge group. To determine the renormalization group running, we use a numerical minimization procedure based on a nested sampling algorithm that randomly generates the values of 19 model parameters at the GUT scale, evolves them, and finally constructs the values of the physical observables and compares them to the existing experimental data at the electroweak scale. We show that the evolved fermion masses and mixings present sizable deviations from the values obtained without including the effects of the intermediate scale.Comment: Comments: 20 pages, 3 figures. Final version published in JHE

    Grp78 promotes the invasion of hepatocellular carcinoma

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    <p>Abstract</p> <p>Background</p> <p>Glucose regulated protein 78 (Grp78) is involved in the invasion and metastasis in many human cancers including gastric cancer, breast cancer, prostate cancer. But the role of Grp78 in the invasion of human hepatocellular carcinoma has not been reported. In this article, we examined if Grp78 was associated with the invasion of hepatocellular carcinoma and explored the possible underlying mechanism.</p> <p>Methods</p> <p>The Grp78 and FAK expression levels in 44 patients with hepatocellular carcinoma were examined using immunohistochemistry. Grp78 overexpressing SMMC7721 cells were established by pcDNA3.1 (+)-Grp78 transfection and screened by G418. Grp78 and FAK levels in Grp78 overexpressing cells were down-regulated by siRNA transfection. The invasion status of tumor cells was evaluated by transwell assay in vitro, and chick embryo metastasis model in vivo. Cell spreading was determined by cell spreading assay, and quantitatively measured by Orisis software HUG. Grp78, pY397 FAK, pY576/577 FAK and FAK levels were detected by western blot. RhoA activity was detected by GST pulldown assay. The distribution of actin cytoskeleton was observed by fluorescent staining.</p> <p>Results</p> <p>Grp78 expression levels in 44 patients with hepatocellular carcinoma were negatively correlated with tumor grading, and positively correlated with portal invasion and intra-hepatic invasion. Overexpression of Grp78 in SMMC7721 cells promoted the invasion of cancer cells in vitro and in vivo, and this increase in tumor cell invasion was blocked by Grp78 siRNA knockdown. Our results also revealed that overexpression of Grp78 in SMMC7721 cells accelerated the process of cell spreading and promoted lamellipodia formation. Further analysis showed that overexpression of Grp78 in SMMC7721 cells increased pY397 and pY576/577 levels of FAK. Grp78 siRNA knockdown decreased FAK activation and activity. Our results also revealed that Grp78 overexpression in SMMC7721 cells decreased RhoA-GTP level, and Grp78 siRNA knockdown rescued RhoA-GTP level in Grp78 overexpressing cells, indicating Grp78 inhibited RhoA activity in hepatocellular carcinoma cells. Furthermore, overexpression of Grp78 in SMMC7721 cells increased phospho-p190RhoGAP level. FAK siRNA knockdown in Grp78 overexpressing cells reversed phospho-p190RhoGAP level. These data suggested that Grp78 inhibited RhoA activity by up-regulated phospho-p190RhoGAP level and Grp78 mediated p190RhoGAP phosphorylation is FAK dependent.</p> <p>Conclusion</p> <p>Grp78 promoted the invasion of hepatocellular carcinoma both in vitro and in vivo. Overexpression of Grp78 in hepatocellular carcinoma cells enhanced the activation and activity of FAK which negatively regulated Rock kinase activity by promoting the phosphorylation of p190RhoGAP.</p

    Socioeconomic status and prostate cancer incidence and mortality rates among the diverse population of California

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    The racial/ethnic disparities in prostate cancer rates are well documented, with the highest incidence and mortality rates observed among African-Americans followed by non-Hispanic Whites, Hispanics, and Asian/Pacific Islanders. Whether socioeconomic status (SES) can account for these differences in risk has been investigated in previous studies, but with conflicting results. Furthermore, previous studies have focused primarily on the differences between African-Americans and non-Hispanic Whites, and little is known for Hispanics and Asian/Pacific Islanders. To further investigate the relationship between SES and prostate cancer among African-Americans, non-Hispanic Whites, Hispanics, and Asian/Pacific Islanders, we conducted a large population-based cross-sectional study of 98,484 incident prostate cancer cases and 8,997 prostate cancer deaths from California. Data were abstracted from the California Cancer Registry, a population-based surveillance, epidemiology, and end results (SEER) registry. Each prostate cancer case and death was assigned a multidimensional neighborhood-SES index using the 2000 US Census data. SES quintile-specific prostate cancer incidence and mortality rates and rate ratios were estimated using SEER*Stat for each race/ethnicity categorized into 10-year age groups. For prostate cancer incidence, we observed higher levels of SES to be significantly associated with increased risk of disease [SES Q1 vs. Q5: relative risk (RR) = 1.28; 95% confidence interval (CI): 1.25–1.30]. Among younger men (45–64 years), African-Americans had the highest incidence rates followed by non-Hispanic Whites, Hispanics, and Asian/Pacific Islanders for all SES levels. Yet, among older men (75–84 years) Hispanics, following African-Americans, displayed the second highest incidence rates of prostate cancer. For prostate cancer deaths, higher levels of SES were associated with lower mortality rates of prostate cancer deaths (SES Q1 vs. Q5: RR = 0.88; 95% CI: 0.92–0.94). African-Americans had a twofold to fivefold increased risk of prostate cancer deaths in comparison to non-Hispanic Whites across all levels of SES. Our findings suggest that SES alone cannot account for the greater burden of prostate cancer among African-American men. In addition, incidence and mortality rates of prostate cancer display different age and racial/ethnic patterns across gradients of SES

    Logarithmic Corrections to Extremal Black Hole Entropy from Quantum Entropy Function

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    We evaluate the one loop determinant of matter multiplet fields of N=4 supergravity in the near horizon geometry of quarter BPS black holes, and use it to calculate logarithmic corrections to the entropy of these black holes using the quantum entropy function formalism. We show that even though individual fields give non-vanishing logarithmic contribution to the entropy, the net contribution from all the fields in the matter multiplet vanishes. Thus logarithmic corrections to the entropy of quarter BPS black holes, if present, must be independent of the number of matter multiplet fields in the theory. This is consistent with the microscopic results. During our analysis we also determine the complete spectrum of small fluctuations of matter multiplet fields in the near horizon geometry.Comment: LaTeX file, 52 pages; v2: minor corrections, references adde
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