CPA for charge ordering in the extended Hubbard model

We study charge ordering in the extended Hubbard model with both on-site and nearest neighbor Coulomb repulsion (U and V, respectively) within the Coherent potential approximation (CPA). The phase boundary between the homogeneous and charge ordered phase for the square lattice is obtained for different values of U. It is shown that at quarter filling for all values of U the charge ordering exists only if the inter-site Coulomb repulsion V exceeds certain critical value which is of the order of the kinetic energy t. At finite temperature a reentrant transition is found in some region of V.Comment: 5 pages, 4 figure

Implementing invariant mass cuts and finite lifetime effects in top-antitop production at threshold

The effects of the finite top quark width in the top pair production cross section close to the threshold are discussed in this talk. We introduce a $t\bar{t}$ cross section with a cut on the invariant masses of the top and antitop that can be calculated theoretically with effective field theory (EFT) methods. The matching procedure to implement the physical phase-space boundaries in the NRQCD framework (``phase-space matching'') is briefly outlined.Comment: 4 pages, 4 figures. Talk given at the 14th International QCD Conference (Montpellier 7-12th July 2008

Ultrasoft Renormalization in Non-Relativistic QCD

For Non-Relativistic QCD the velocity renormalization group correlates the renormalization scales for ultrasoft, potential and soft degrees of freedom. Here we discuss the renormalization of operators by ultrasoft gluons. We show that renormalization of soft vertices can induce new operators, and also present a procedure for correctly subtracting divergences in mixed potential-ultrasoft graphs. Our results affect the running of the spin-independent potentials in QCD. The change for the NNLL t-tbar cross section near threshold is very small, being at the 1% level and essentially independent of the energy. We also discuss implications for analyzing situations where mv^2 ~ Lambda_QCD.Comment: 31 pages, 11 fig

Transgender at Work: Livelihoods for Transgender People in Vietnam

The laws in the Socialist Republic of Vietnam promote equality for all citizens and refer to ‘persons’ rather than ‘men’ or ‘women’. However, because of traditional gender norms, transgender people in Vietnam are facing severe stigma and discrimination in public, in schools, at home and in the workplace (CCIHP 2011; Hoang 2012; ICS 2015; iSEE 2013). Parents, teachers and policemen are among the most common perpetrators (CCIHP 2011, 2012a, 2012b). Before 1975, homosexuality and transgenderism were considered ‘social diseases’, ‘social evils’, and were targets for elimination in government health and public policies; after 1975, there was a higher emphasis on this as the public saw them as remnants of American neo-colonialism (Blanc 2005). People who were found to practice same-sex sex could be sent to an education centre (Blanc 2005). Transgender people have difficulty accessing services and rights as they cannot change their personal identification (ID) card, which is an obstacle to obtaining social services, housing and work. Gender roles and norms affect the employment practices, options and preferences of transmen and transwomen differently. This study, undertaken by the Center for Creative Initiatives in Health and Population (CCIHP) and Institute of Development Studies (IDS), does not claim to report on behalf of all transgender people in Vietnam, but we hope to gain more insights into both the opportunities and the obstacles that transmen and transwomen face and to understand how they could be supported to increase their livelihood options. First, the research involved a case study on transgender people and livelihood opportunities which sought to answer the following questions: What are the different employment options and preferences for Vietnamese transmen and transwomen? What are the links between stigma, education and employment? Second, it involved testing an integrated application of new quantitative online participatory methodologies on young transmen and transwomen communities, alongside qualitative face-to-face methods to reach elderly transgender people and employers who are not members of online communities. Qualitative interviews also help understand these communities better and provide information that can inform their development.UK Department for International Developmen

1S and MSbar Bottom Quark Masses from Upsilon Sum Rules

The bottom quark 1S mass, $M_b^{1S}$, is determined using sum rules which relate the masses and the electronic decay widths of the $\Upsilon$ mesons to moments of the vacuum polarization function. The 1S mass is defined as half the perturbative mass of a fictitious ${}^3S_1$ bottom-antibottom quark bound state, and is free of the ambiguity of order $\Lambda_{QCD}$ which plagues the pole mass definition. Compared to an earlier analysis by the same author, which had been carried out in the pole mass scheme, the 1S mass scheme leads to a much better behaved perturbative series of the moments, smaller uncertainties in the mass extraction and to a reduced correlation of the mass and the strong coupling. We arrive at $M_b^{1S}=4.71\pm 0.03$ GeV taking $\alpha_s(M_Z)=0.118\pm 0.004$ as an input. From that we determine the $\bar{MS}$ mass as $\bar m_b(\bar m_b) = 4.20 \pm 0.06$ GeV. The error in $\bar m_b(\bar m_b)$ can be reduced if the three-loop corrections to the relation of pole and $\bar{MS}$ mass are known and if the error in the strong coupling is decreased.Comment: 20 pages, latex; numbers in Tabs. 2,3,4 corrected, a reference and a comment on the fitting procedure added, typos in Eqs. 2 and 23 eliminate

Fluid Flows of Mixed Regimes in Porous Media

In porous media, there are three known regimes of fluid flows, namely, pre-Darcy, Darcy and post-Darcy. Because of their different natures, these are usually treated separately in literature. To study complex flows when all three regimes may be present in different portions of a same domain, we use a single equation of motion to unify them. Several scenarios and models are then considered for slightly compressible fluids. A nonlinear parabolic equation for the pressure is derived, which is degenerate when the pressure gradient is either small or large. We estimate the pressure and its gradient for all time in terms of initial and boundary data. We also obtain their particular bounds for large time which depend on the asymptotic behavior of the boundary data but not on the initial one. Moreover, the continuous dependence of the solutions on initial and boundary data, and the structural stability for the equation are established.Comment: 33 page

Determining the CP properties of the Higgs boson

The search and the probe of the fundamental properties of Higgs boson(s) and, in particular, the determination of their charge conjugation and parity (CP) quantum numbers, is one of the main tasks of future high-energy colliders. We demonstrate that the CP properties of a Standard Model-like Higgs particle can be unambiguously assessed by measuring just the total cross section and the top polarization in associated Higgs production with top quark pairs in e+e- collisions.Comment: 4 pages, revtex, uses axodraw (style file included in the submission

Isogeometric analysis for functionally graded microplates based on modified couple stress theory

Analysis of static bending, free vibration and buckling behaviours of functionally graded microplates is investigated in this study. The main idea is to use the isogeometric analysis in associated with novel four-variable refined plate theory and quasi-3D theory. More importantly, the modified couple stress theory with only one material length scale parameter is employed to effectively capture the size-dependent effects within the microplates. Meanwhile, the quasi-3D theory which is constructed from a novel seventh-order shear deformation refined plate theory with four unknowns is able to consider both shear deformations and thickness stretching effect without requiring shear correction factors. The NURBS-based isogeometric analysis is integrated to exactly describe the geometry and approximately calculate the unknown fields with higher-order derivative and continuity requirements. The convergence and verification show the validity and efficiency of this proposed computational approach in comparison with those existing in the literature. It is further applied to study the static bending, free vibration and buckling responses of rectangular and circular functionally graded microplates with various types of boundary conditions. A number of investigations are also conducted to illustrate the effects of the material length scale, material index, and length-to-thickness ratios on the responses of the microplates.Comment: 57 pages, 14 figures, 18 table

Negotiating Public and Legal Spaces: The Emergence of an LGBT Movement in Vietnam

Vietnam’s laws, policies and decrees do not explicitly discriminate against lesbian, gay, bisexual and transgender (LGBT) individuals but their rights are not legally protected and they are socially marginalised. The state promotes a model of a married heterosexual couple with two children in the media and through its public policy campaigns. Families that comply are able to obtain membership of the Communist Party and run for office; women are eligible for micro-credit programmes. Same-sex couples cannot marry and are thus ineligible for the benefits that married couples enjoy. Family laws, with regard to child custody, inheritance and property, do not protect same-sex couples. In order to understand how LGBT civil society organisations can affect legal and social change with regard to the laws that regulate sexual norms and unions, this empirical study explores the following two examples of collective action in Vietnam: 1. The mobilisation strategies of civil society organisations to hold gay pride events. 2. Collective action to legalise same-sex ceremonies and marriages.UK Department for International Developmen