2,190 research outputs found

    First phylogenetic analyses of galaxy evolution

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    The Hubble tuning fork diagram, based on morphology, has always been the preferred scheme for classification of galaxies and is still the only one originally built from historical/evolutionary relationships. At the opposite, biologists have long taken into account the parenthood links of living entities for classification purposes. Assuming branching evolution of galaxies as a "descent with modification", we show that the concepts and tools of phylogenetic systematics widely used in biology can be heuristically transposed to the case of galaxies. This approach that we call "astrocladistics" has been first applied to Dwarf Galaxies of the Local Group and provides the first evolutionary galaxy tree. The cladogram is sufficiently solid to support the existence of a hierarchical organization in the diversity of galaxies, making it possible to track ancestral types of galaxies. We also find that morphology is a summary of more fundamental properties. Astrocladistics applied to cosmology simulated galaxies can, unsurprisingly, reconstruct the correct "genealogy". It reveals evolutionary lineages, divergences from common ancestors, character evolution behaviours and shows how mergers organize galaxy diversity. Application to real normal galaxies is in progress. Astrocladistics opens a new way to analyse galaxy evolution and a path towards a new systematics of galaxies

    Charmonium properties from lattice QCD + QED: hyperfine splitting, J/ψJ/\psi leptonic width, charm quark mass and aμca_{\mu}^c

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    We have performed the first nf=2+1+1n_f = 2+1+1 lattice QCD computations of the properties (masses and decay constants) of ground-state charmonium mesons. Our calculation uses the HISQ action to generate quark-line connected two-point correlation functions on MILC gluon field configurations that include u/du/d quark masses going down to the physical point, tuning the cc quark mass from MJ/ψM_{J/\psi} and including the effect of the cc quark's electric charge through quenched QED. We obtain MJ/ψMηcM_{J/\psi}-M_{\eta_c} (connected) = 120.3(1.1) MeV and interpret the difference with experiment as the impact on MηcM_{\eta_c} of its decay to gluons, missing from the lattice calculation. This allows us to determine ΔMηcannihiln\Delta M_{\eta_c}^{\mathrm{annihiln}} =+7.3(1.2) MeV, giving its value for the first time. Our result of fJ/ψ=f_{J/\psi}= 0.4104(17) GeV, gives Γ(J/ψe+e)\Gamma(J/\psi \rightarrow e^+e^-)=5.637(49) keV, in agreement with, but now more accurate than experiment. At the same time we have improved the determination of the cc quark mass, including the impact of quenched QED to give mc(3GeV)\overline{m}_c(3\,\mathrm{GeV}) = 0.9841(51) GeV. We have also used the time-moments of the vector charmonium current-current correlators to improve the lattice QCD result for the cc quark HVP contribution to the anomalous magnetic moment of the muon. We obtain aμc=14.638(47)×1010a_{\mu}^c = 14.638(47) \times 10^{-10}, which is 2.5σ\sigma higher than the value derived using moments extracted from some sets of experimental data on R(e+ehadrons)R(e^+e^- \rightarrow \mathrm{hadrons}). This value for aμca_{\mu}^c includes our determination of the effect of QED on this quantity, δaμc=0.0313(28)×1010\delta a_{\mu}^c = 0.0313(28) \times 10^{-10}.Comment: Added extra discussion on QED setup, some new results to study the effects of strong isospin breaking in the sea (including new Fig. 1) and a fit stability plot for the hyperfine splitting (new Fig. 7). Version accepted for publication in PR

    QED interaction effects on heavy meson masses from lattice QCD+QED

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    Hadron masses are subject to few MeV corrections arising from QED interactions, almost entirely arising from the electric charge of the valence quarks. The QED effects include both self-energy contributions and interactions between the valence quarks/anti-quarks. By combining results from different signs of the valence quark electric charge we are able to isolate the interaction term which is dominated by the Coulomb piece, αQEDeq1eq2/r\langle \alpha_{\mathrm{QED}}e_{q_1}e_{\overline{q}_2}/r \rangle, in the nonrelativistic limit. We study this for DsD_s, ηc\eta_c and J/ψJ/\psi mesons, working in lattice QCD plus quenched QED. We use gluon field configurations that include up, down, strange and charm quarks in the sea at multiple values of the lattice spacing. Our results, including also values for mesons with quarks heavier than charm, can be used to improve phenomenological models for the QED contributions. The QED interaction term carries information about meson structure; we derive effective sizes 1/reff1\langle 1/r_{\mathrm{eff}} \rangle^{-1} for ηc\eta_c, J/ψJ/\psi and DsD_s of 0.206(8) fm, 0.321(14) fm and 0.307(31) fm respectively.Comment: 8 pages, 3 figure

    Renormalisation of the tensor current in lattice QCD and the J/ψJ/\psi tensor decay constant

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    Lattice QCD calculations of form factors for rare Standard Model processes such as BK+B \to K \ell^+ \ell^- use tensor currents that require renormalisation. These renormalisation factors, ZTZ_T, have typically been calculated within perturbation theory and the estimated uncertainties from missing higher order terms are significant. Here we study tensor current renormalisation using lattice implementations of momentum-subtraction schemes. Such schemes are potentially more accurate but have systematic errors from nonperturbative artefacts. To determine and remove these condensate contributions we calculate the ground-state charmonium tensor decay constant, fJ/ψTf_{J/\psi}^T, which is also of interest in beyond the Standard Model studies. We obtain fJ/ψT(MSˉ,2 GeV)=0.3927(27)f_{J/\psi}^T(\bar{\text{MS}}, 2\ \mathrm{GeV})=0.3927(27) GeV, with ratio to the vector decay constant of 0.9569(52), significantly below 1. We also give ZTZ_T factors, converted to the MSˉ\bar{\mathrm{MS}} scheme, corrected for condensate contamination. This contamination reaches 1.5\% at a renormalisation scale of 2 GeV (in the preferred RI-SMOM scheme) and so must be removed for accurate results.Comment: 12 pages, version accepted for publication in PR

    Improving Access to Psychological Therapies (IAPT) services outcomes for people with learning disabilities: National data 2012-2013 to 2019-2020

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    Primary care interventions for people with common mental health problems in England are primarily delivered through Improving Access to Psychological Therapies (IAPT) services. One of the priorities for IAPT services is to reduce inequalities in access and outcomes for potentially disadvantaged populations. This paper uses national data from the years 2012-2013 to 2019-2020 to present a comparison of service process and therapy outcomes for people with learning disabilities. Annual data for people with learning disabilities, people with other recorded disabilities and people with no recorded disabilities were extracted from a publicly available, national data source. Data are presented graphically with relative risk calculated for each variable and year, and show a broadly similar pattern of waiting time access for people with learning disabilities and people with no disabilities, and a broadly similar proportion of people with learning disabilities and people with no disabilities who finish treatment. However, people with learning disabilities have poorer clinical outcomes than people with no disabilities. We discuss adaptations to IAPT processes and therapy provision that may further support people with learning disabilities' access to IAPT services. Key learning aims (1) To describe how IAPT services record disabilities, and in particular record whether a person identifies themselves as having a learning disability.1 (2) To explore the differences in processes and therapy outcomes for people with learning disabilities compared with people with no disabilities and people with other disabilities. (3) To understand adaptations to IAPT processes and therapies that may make IAPT services more accessible to people with learning disabilities
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