2,190 research outputs found
First phylogenetic analyses of galaxy evolution
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, leptonic width, charm quark mass and
We have performed the first 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
quark masses going down to the physical point, tuning the quark mass from
and including the effect of the quark's electric charge
through quenched QED. We obtain (connected) =
120.3(1.1) MeV and interpret the difference with experiment as the impact on
of its decay to gluons, missing from the lattice calculation. This
allows us to determine =+7.3(1.2) MeV,
giving its value for the first time. Our result of 0.4104(17)
GeV, gives =5.637(49) keV, in agreement
with, but now more accurate than experiment. At the same time we have improved
the determination of the quark mass, including the impact of quenched QED
to give = 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 quark HVP contribution to the
anomalous magnetic moment of the muon. We obtain , which is 2.5 higher than the value derived using moments
extracted from some sets of experimental data on . This value for includes our determination of
the effect of QED on this quantity, .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
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, , in the
nonrelativistic limit. We study this for , and 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
for , and 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 tensor decay constant
Lattice QCD calculations of form factors for rare Standard Model processes
such as use tensor currents that require
renormalisation. These renormalisation factors, , 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,
, which is also of interest in beyond the Standard Model studies.
We obtain GeV, with
ratio to the vector decay constant of 0.9569(52), significantly below 1. We
also give factors, converted to the 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
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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