2,529 research outputs found

    Baryonic and mesonic 3-point functions with open spin indices

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    We have implemented a new way of computing three-point correlation functions. It is based on a factorization of the entire correlation function into two parts which are evaluated with open spin- (and to some extent flavor-) indices. This allows us to estimate the two contributions simultaneously for many different initial and final states and momenta, with little computational overhead. We explain this factorization as well as its efficient implementation in a new library which has been written to provide the necessary functionality on modern parallel architectures and on CPUs, including Intel's Xeon Phi series.Comment: 7 pages, 5 figures, Proceedings of Lattice 201

    Leading order mesonic and baryonic SU(3) low energy constants from Nf=3N_f = 3 lattice QCD

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    We determine the leading order mesonic~(B0B_0 and F0F_0) and baryonic~(m0m_0, DD and FF) SU(3) chiral perturbation theory low energy constants from lattice QCD. We employ gauge ensembles with Nf=3N_f=3 (i.e., mu=md=msm_u=m_d=m_s) non-perturbatively improved Wilson fermions at six distinct values of the lattice spacing in the range a≈(0.039−0.098)a\approx (0.039 - 0.098) fm, which constitute a subset of the Coordinated Lattice Simulations (CLS) gauge ensembles. The pseudoscalar meson mass MπM_\pi ranges from around 430430 MeV down to 240240 MeV and the linear spatial lattice extent LL from 6.4 Mπ−16.4\,M_{\pi}^{-1} to 3.3 Mπ−13.3\,M_{\pi}^{-1}, where LMπ≥4 L M_\pi \geq 4 for the majority of the ensembles. This allows us to perform a controlled extrapolation of all the low energy constants to the chiral, infinite volume and continuum limits. We find the SU(3) chiral condensate and F0F_0 to be smaller than their SU(2) counterparts while the Gell-Mann--Oakes--Renner parameters B0≈BB_0\approx B are similar. Regarding baryonic LECs, we obtain F/D=0.612(12)(14)F/D = 0.612^{(14)}_{(12)}.Comment: 17 pages, 12 figures, minor typos corrected, references added, 2 figures update

    Development of a pilot data management infrastructure for biomedical researchers at University of Manchester – approach, findings, challenges and outlook of the MaDAM Project

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    Management and curation of digital data has been becoming ever more important in a higher education and research environment characterised by large and complex data, demand for more interdisciplinary and collaborative work, extended funder requirements and use of e-infrastructures to facilitate new research methods and paradigms. This paper presents the approach, technical infrastructure, findings, challenges and outlook (including future development within the successor project, MiSS) of the ‘MaDAM: Pilot data management infrastructure for biomedical researchers at University of Manchester’ project funded under the infrastructure strand of the JISC Managing Research Data (JISCMRD) programme. MaDAM developed a pilot research data management solution at the University of Manchester based on biomedical researchers’ requirements, which includes technical and governance components with the flexibility to meet future needs across multiple research groups and disciplines

    (In)finite extent of stationary perfect fluids in Newtonian theory

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    For stationary, barotropic fluids in Newtonian gravity we give simple criteria on the equation of state and the "law of motion" which guarantee finite or infinite extent of the fluid region (providing a priori estimates for the corresponding stationary Newton-Euler system). Under more restrictive conditions, we can also exclude the presence of "hollow" configurations. Our main result, which does not assume axial symmetry, uses the virial theorem as the key ingredient and generalises a known result in the static case. In the axially symmetric case stronger results are obtained and examples are discussed.Comment: Corrections according to the version accepted by Ann. Henri Poincar

    Light-cone distribution amplitudes of octet baryons from lattice QCD

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    We present lattice QCD results for the wave function normalization constants and the first moments of the distribution amplitudes for the lowest-lying baryon octet. The analysis is based on a large number of Nf=2+1N_f=2+1 ensembles comprising multiple trajectories in the quark mass plane including physical pion (and kaon) masses, large volumes, and, most importantly, five different lattice spacings down to a=0.039 fma=0.039\,\mathrm{fm}. This allows us to perform a controlled extrapolation to the continuum and infinite volume limits by a simultaneous fit to all available data. We demonstrate that the formerly observed violation of flavor symmetry breaking constraints can, indeed, be attributed to discretization effects that vanish in the continuum limit

    Hyperon couplings from Nf=2+1N_f = 2 + 1 lattice QCD

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    We compute various (generalized) isovector charges of the octet baryons. These include gAg_A, gTg_T and gSg_S as well as the unpolarized, polarized and transversity parton distribution function (PDF) momentum fractions ⟨x⟩u+−d+\langle x\rangle_{u^+-d^+}, ⟨x⟩Δu−−Δd−\langle x\rangle_{\Delta u^--\Delta d^-} and ⟨x⟩δu+−δ+\langle x\rangle_{\delta u^+-\delta ^+}. The simulations are carried out on a subset of the (isospin symmetric) Nf=2+1N_f=2+1 flavour Coordinated Lattice Simulations (CLS) gauge ensembles with lattice spacings ranging from a≈0.086 a\approx 0.086\,fm down to a≈0.050 a\approx 0.050\,fm. First results on the breaking of flavour symmetry and the low energy constants FF and DD are presented. While SU(3) flavour symmetry violations are found to be sizeable for gA=⟨1⟩Δu+−Δd+g_A=\langle 1\rangle_{\Delta u^+-\Delta d^+}, these are quite small for gT=⟨1⟩δu−−δd−g_T=\langle 1\rangle_{\delta u^--\delta d^-} and ⟨x⟩u+−d+\langle x\rangle_{u^+-d^+}.Comment: 7 pages, 5 figures, talk given at Lattice 2019, v2: corrected some typo

    Population, sexual and reproductive health, rights and sustainable development: forging a common agenda.

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    This article suggests that sexual and reproductive health and rights activists seeking to influence the post-2015 international development paradigm must work with sustainable development advocates concerned with a range of issues, including climate change, environmental issues, and food and water security, and that a way of building bridges with these communities is to demonstrate how sexual and reproductive health and rights are relevant for these issues. An understanding of population dynamics, including urbanization and migration, as well as population growth, can help to clarify these links. This article therefore suggests that whether or not sexual and reproductive health and rights activists can overcome resistance to discussing "population", become more knowledgeable about other sustainable development issues, and work with others in those fields to advance the global sustainable development agenda are crucial questions for the coming months. The article also contends that it is possible to care about population dynamics (including ageing and problems faced by countries with a high proportion of young people) and care about human rights at the same time. It expresses concern that, if sexual and reproductive health and rights advocates do not participate in the population dynamics discourse, the field will be left free for those for whom respecting and protecting rights may be less of a priority
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