The structure of the f0(980) scalar boson has been a mystery for decades.
A new study, however, appears to show that it is basically a quark-antiquark meson with a valance strange quark and anti-strange quark. In other words, it is strange quark quarkonia. The new study largely rules out tetraquark, meson molecule, and quark-antiquark-gluon hybrid particle alternatives.
Newtonian mechanics, Newtonian gravity, and Newton's observations about optics went unchallenged and unamended for about 250 years. Scientists and engineers still use them on a daily basis, despite knowing that general relativity, special relativity, and quantum mechanics limit the range of their applicability.
The laws of physics he invented are still taught in high school and freshman college level physics classes. He co-invented calculus, which is still taught in high school and freshman and sophomore level college classes (although the notation of the independent co-inventor of calculus, Leibniz, rather than his own clunky notation, is used today).
Not all parts of Newton's legacy were equally illustrious. He was also a Unitarian theologian and an alchemist, and devoted almost as much time in his life to those ultimately fruitless projects, as he did to science and mathematics. He was also a member of Parliament, ran the Royal Mint for many years, was knighted, and led the Royal Society for twenty-four years. He never married and is not reputed to have had any children.
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a,b, Putative migration routes of BSP inferred using pairwise FST values (a) and after removing the Zambian Lozi population from the analyses (b). Arrow colours correspond to north-western Bantu speakers 2 (NW-BSP 2; brown; one arrow between Cameroon and CAR), west-western Bantu speakers (WW-BSP; green), south-western Bantu speakers (SW-BSP; dark blue) and eastern Bantu speakers (E-BSP; red). c, Spatial visualization of effective migration rates (EEMS software) estimated with the masked Only-BSP dataset. log(m) denotes the effective migration rate on a log10 scale, relative to the overall migration rate across the habitat. Populations are coloured according to each Bantu-speaking linguistic group (brown, green, dark blue and red dots). d, GenGrad analysis using FST as the genetic distance for the admixture-masked BSP dataset. Hexagons of the grid were plotted with a colour scale representing the FST gradient (key).
The expansion of people speaking Bantu languages is the most dramatic demographic event in Late Holocene Africa and fundamentally reshaped the linguistic, cultural and biological landscape of the continent.
With a comprehensive genomic dataset, including newly generated data of modern-day and ancient DNA from previously unsampled regions in Africa, we contribute insights into this expansion that started 6,000–4,000 years ago in western Africa. We genotyped 1,763 participants, including 1,526 Bantu speakers from 147 populations across 14 African countries, and generated whole-genome sequences from 12 Late Iron Age individuals.
We show that genetic diversity amongst Bantu-speaking populations declines with distance from western Africa, with current-day Zambia and the Democratic Republic of Congo as possible crossroads of interaction.
Using spatially explicit methods and correlating genetic, linguistic and geographical data, we provide cross-disciplinary support for a serial-founder migration model. We further show that Bantu speakers received significant gene flow from local groups in regions they expanded into.
Our genetic dataset provides an exhaustive modern-day African comparative dataset for ancient DNA studies and will be important to a wide range of disciplines from science and humanities, as well as to the medical sector studying human genetic variation and health in African and African-descendant populations.
African populations speaking Bantu languages (Bantu-speaking populations (BSP)) constitute about 30% of Africa’s total population, of which about 350 million people across 9 million km2 speak more than 500 Bantu languages. Archaeological, linguistic, historical and anthropological sources attest to the complex history of the expansion of BSP across subequatorial Africa, which fundamentally reshaped the linguistic, cultural and biological landscape of the continent. There is a broad interdisciplinary consensus that the initial spread of Bantu languages was a demic expansion and ancestral BSP migrated first through the Congo rainforest and later to the savannas further east and south. However, debates persist on the pathways and modes of the expansion.Whereas most recent human expansions involved latitudinal movements through regions with similar climatic conditions, the expansion of the BSP is notable for its primarily longitudinal trajectory, traversing regions with highly diverse climates and biomes, including the highlands of Cameroon, central African rainforests, African savannas and arid south-western Africa.
We present the first measurement of the Weyl potential at four redshifts bins using data from the first three years of observations of the Dark Energy Survey (DES). The Weyl potential, which is the sum of the spatial and temporal distortions of the Universe's geometry, provides a direct way of testing the theory of gravity and the validity of the ΛCDM model. We find that the measured Weyl potential is 2.3σ, respectively 3.1σ, below the ΛCDM predictions in the two lowest redshift bins. We show that these low values of the Weyl potential are at the origin of the σ8 tension between Cosmic Microwave Background (CMB) measurements and weak lensing measurements. Interestingly, we find that the tension remains if no information from the CMB is used. DES data on their own prefer a high value of the primordial fluctuations, followed by a slow evolution of the Weyl potential. A remarkable feature of our method is that the measurements of the Weyl potential are model-independent and can therefore be confronted with any theory of gravity, allowing efficient tests of models beyond General Relativity.
The general theory of relativity (GR) has excelled in explaining gravitational phenomena at the scale of the solar system with remarkable precision. However, when extended to the galactic or cosmological scale, it requires dark matter and dark energy to explain observations. In our previous article arXiv:2308.04503, we've formulated a gravity theory based in Mach's principle, known as Machian gravity. We demonstrated that the theory successfully explains galactic velocity profiles without requiring additional dark matter components. In previous studies, for a selected set of galaxy clusters, we also showed its ability to explain the velocity dispersion in the clusters without extra unseen matter components. This paper primarily explores the mass profiles of galaxy clusters. We test the Machian Gravity acceleration law on two distinct sets comprising approximately 150 galaxy clusters sourced from various studies. We fitted the dynamic mass profiles using the Machian gravity model. The outcomes of our study show exceptional agreement between the theory and observational results.
A new study looks at genetics, archeology, and linguistics to explain linguistic diversity in pre-Columbian California.
Before the colonial period, California harboured more language variation than all of Europe, and linguistic and archaeological analyses have led to many hypotheses to explain this diversity.
We report genome-wide data from 79 ancient individuals from California and 40 ancient individuals from Northern Mexico dating to 7,400–200 years before present (BP). Our analyses document long-term genetic continuity between people living on the Northern Channel Islands of California and the adjacent Santa Barbara mainland coast from 7,400 years BP to modern Chumash groups represented by individuals who lived around 200 years BP.
The distinctive genetic lineages that characterize present-day and ancient people from Northwest Mexico increased in frequency in Southern and Central California by 5,200 years BP, providing evidence for northward migrations that are candidates for spreading Uto-Aztecan languages before the dispersal of maize agriculture from Mexico.
Individuals from Baja California share more alleles with the earliest individual from Central California in the dataset than with later individuals from Central California, potentially reflecting an earlier linguistic substrate, whose impact on local ancestry was diluted by later migrations from inland regions.
After 1,600 years BP, ancient individuals from the Channel Islands lived in communities with effective sizes similar to those in pre-agricultural Caribbean and Patagonia, and smaller than those on the California mainland and in sampled regions of Mexico.
The effort to discover a quantum theory of gravity is motivated by the need to reconcile the incompatibility between quantum theory and general relativity.
Here, we present an alternative approach by constructing a consistent theory of classical gravity coupled to quantum field theory. The dynamics is linear in the density matrix, completely positive and trace preserving, and reduces to Einstein's theory of general relativity in the classical limit. Consequently, the dynamics doesn't suffer from the pathologies of the semiclassical theory based on expectation values.
The assumption that general relativity is classical necessarily modifies the dynamical laws of quantum mechanics -- the theory must be fundamentally stochastic in both the metric degrees of freedom and in the quantum matter fields. This allows it to evade several no-go theorems purporting to forbid classical-quantum interactions.
The measurement postulate of quantum mechanics is not needed -- the interaction of the quantum degrees of freedom with classical space-time necessarily causes decoherence in the quantum system.
We first derive the general form of classical-quantum dynamics and consider realisations which have as its limit deterministic classical Hamiltonian evolution. The formalism is then applied to quantum field theory interacting with the classical space-time metric.
One can view the classical-quantum theory as fundamental or as an effective theory useful for computing the back-reaction of quantum fields on geometry. We discuss a number of open questions from the perspective of both viewpoints.
We consider two interacting systems when one is treated classically while the other system remains quantum. Consistent dynamics of this coupling has been shown to exist, and explored in the context of treating space-time classically.
Here, we prove that any such hybrid dynamics necessarily results in decoherence of the quantum system, and a breakdown in predictability in the classical phase space. We further prove that a trade-off between the rate of this decoherence and the degree of diffusion induced in the classical system is a general feature of all classical quantum dynamics; long coherence times require strong diffusion in phase-space relative to the strength of the coupling.
Applying the trade-off relation to gravity, we find a relationship between the strength of gravitationally-induced decoherence versus diffusion of the metric and its conjugate momenta. This provides an experimental signature of theories in which gravity is fundamentally classical.
Bounds on decoherence rates arising from current interferometry experiments, combined with precision measurements of mass, place significant restrictions on theories where Einstein’s classical theory of gravity interacts with quantum matter. We find that part of the parameter space of such theories are already squeezed out, and provide figures of merit which can be used in future mass measurements and interference experiments.
The Kangxi Emperor (r. 1661–1722) holds the record for having the most imperial consorts [in the Qing Dynasty] with 79, while the Guangxu Emperor (r. 1875–1908) holds the record for having the fewest, with one empress and two consorts—a total of just three imperial consorts.
Functionally, this system, somewhat like the Saudi Arabian monarchy's succession system, insured that the hereditary emperorship would not end for lack of an heir. It also provided a pool of potential heirs from which a worthy successor could be chosen, mitigating, although not entirely eliminating, the harm caused by the occasional "mad king".
The Scalar Field Dark Matter model has been known in various ways throughout its history; Fuzzy, BEC, Wave, Ultralight, Axion-like Dark Matter, etc.
All of them consist in proposing that the dark matter of the universe is a spinless field Φ that follows the Klein-Gordon (KG) equation of motion ◻Φ−dV/dΦ=0, for a given scalar field potential V. The difference between different models is sometimes the choice of the scalar field potential V.
In the literature we find that people usually work in the nonrelativistic, weak-field limit of the KG equation where it transforms into the Schrödinger equation and the Einstein equations into the Poisson equation, reducing the KG-Einstein system, to the Schrödinger-Poisson system.
In this paper, we review some of the most interesting achievements of this model from the historical point of view and its comparison with observations, showing that this model could be the last answer to the question about the nature of dark matter in the universe.