Chiral Lagrangians at finite density

The effective SU(2) chiral Lagrangian with external sources is given in the presence of non-vanishing nucleon densities by calculating the in-medium contributions of the chiral pion-nucleon Lagrangian. As a by product, a relativistic quantum field theory for Fermi many-particle systems at zero temperature is directly derived from relativistic quantum field theory with functional methods.Comment: 6 Pages, 3 figures, REVTeX. Extended version. Explicit Feynman rules are give

Limitations of the heavy-baryon expansion as revealed by a pion-mass dispersion relation

The chiral expansion of nucleon properties such as mass, magnetic moment, and magnetic polarizability are investigated in the framework of chiral perturbation theory, with and without the heavy-baryon expansion. The analysis makes use of a pion-mass dispersion relation, which is shown to hold in both frameworks. The dispersion relation allows an ultraviolet cutoff to be implemented without compromising the symmetries. After renormalization, the leading-order heavy-baryon loops demonstrate a stronger dependence on the cutoff scale, which results in weakened convergence of the expansion. This conclusion is tested against the recent results of lattice quantum chromodynamics simulations for nucleon mass and isovector magnetic moment. In the case of the polarizability, the situation is even more dramatic as the heavy-baryon expansion is unable to reproduce large soft contributions to this quantity. Clearly, the heavy-baryon expansion is not suitable for every quantity.Comment: Accepted for publication in EPJ C. Made changes based on referee comments: clarifying sentences to conclusion 1. of Section IV, beginning of Section V, and new footnote in Section VI, page 8. Added more detailed explanation in paragraph 4 of Section III. Added citations of Phys.Rev. D60, 034014, and Phys.Lett. B716, 33

Convergence of chiral effective field theory

We formulate the expansion for the mass of the nucleon as a function of pion mass within chiral perturbation theory using a number of different ultra-violet regularisation schemes; including dimensional regularisation and various finite-ranged regulators. Leading and next-to-leading order non-analytic contributions are included through the standard one-loop Feynman graphs. In addition to the physical nucleon mass, the expansion is constrained by recent, extremely accurate, lattice QCD data obtained with two flavors of dynamical quarks. The extent to which different regulators can describe the chiral expansion is examined, while varying the range of quark mass over which the expansions are matched. Renormalised chiral expansion parameters are recovered from each regularisation prescription and compared. We find that the finite-range regulators produce consistent, model-independent results over a wide range of quark mass sufficient to solve the chiral extrapolation problem in lattice QCD.Comment: 13 pages, 13 figures; To appear in Progress in Particle and Nuclear Physics; presented at Erice School on Quarks in Hadrons and Nuclei, September 200

Nucleon mass, sigma term and lattice QCD

We investigate the quark mass dependence of the nucleon mass M_N. An interpolation of this observable, between a selected set of fully dynamical two-flavor lattice QCD data and its physical value, is studied using relativistic baryon chiral perturbation theory up to order p^4. In order to minimize uncertainties due to lattice discretization and finite volume effects our numerical analysis takes into account only simulations performed with lattice spacings a5. We have also restricted ourselves to data with m_pi<600 MeV and m_sea=m_val. A good interpolation function is found already at one-loop level and chiral order p^3. We show that the next-to-leading one-loop corrections are small. From the p^4 numerical analysis we deduce the nucleon mass in the chiral limit, M_0 approx 0.88 GeV, and the pion-nucleon sigma term sigma_N= (49 +/- 3) MeV at the physical value of the pion mass.Comment: 12 pages, 4 figures, revised journal versio

Advanced Hydrogen Transport Membranes for Vision 21 Fossil Fuel Plants

Seeks to economically eliminate the environmental concerns associated with the use of fossil fuels

Genetic insights into biological mechanisms governing human ovarian ageing

Reproductive longevity is essential for fertility and influences healthy ageing in women, but insights into its underlying biological mechanisms and treatments to preserve it are limited. Here we identify 290 genetic determinants of ovarian ageing, assessed using normal variation in age at natural menopause in approximately 200,000 women of European ancestry. These common alleles were associated with clinical extremes of age at natural menopause; women in the top 1% of genetic susceptibility have an equivalent risk of premature ovarian insufficiency to those carrying monogenic FMR1 premutations. The identified loci implicate a broad range of DNA damage response (DDR) processes and include loss-of-function variants in key DDR-associated genes. Integration with experimental models demonstrates that these DDR processes act across the lifecourse to shape the ovarian reserve and its rate of depletion. Furthermore, we demonstrate that experimental manipulation of DDR pathways highlighted by human genetics increases fertility and extends reproductive life in mice. Causal inference analyses using the identified genetic variants indicate that extending reproductive life in women improves bone health and reduces risk of type 2 diabetes, but increases the risk of hormone-sensitive cancers. These findings provide insight into the mechanisms that govern ovarian ageing, when they act, and how they might be targeted by therapeutic approaches to extend fertility and prevent disease

Search for gravitational-wave transients associated with magnetar bursts in advanced LIGO and advanced Virgo data from the third observing run

Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant f lares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and longduration (∼100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA’s third observation run. These 13 bursts come from two magnetars, SGR1935 +2154 and SwiftJ1818.0−1607. We also include three other electromagnetic burst events detected by FermiGBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant flares were detected during the analysis period. We find no evidence of gravitational waves associated with any of these 16 bursts. We place upper limits on the rms of the integrated incident gravitational-wave strain that reach 3.6 × 10−²³ Hz at 100 Hz for the short-duration search and 1.1 ×10−²² Hz at 450 Hz for the long-duration search. For a ringdown signal at 1590 Hz targeted by the short-duration search the limit is set to 2.3 × 10−²² Hz. Using the estimated distance to each magnetar, we derive upper limits upper limits on the emitted gravitational-wave energy of 1.5 × 1044 erg (1.0 × 1044 erg) for SGR 1935+2154 and 9.4 × 10^43 erg (1.3 × 1044 erg) for Swift J1818.0−1607, for the short-duration (long-duration) search. Assuming isotropic emission of electromagnetic radiation of the burst fluences, we constrain the ratio of gravitational-wave energy to electromagnetic energy for bursts from SGR 1935+2154 with the available fluence information. The lowest of these ratios is 4.5 × 103

A joint Fermi-GBM and Swift-BAT analysis of gravitational-wave candidates from the third gravitational-wave observing run

We present Fermi Gamma-ray Burst Monitor (Fermi-GBM) and Swift Burst Alert Telescope (Swift-BAT) searches for gamma-ray/X-ray counterparts to gravitational-wave (GW) candidate events identified during the third observing run of the Advanced LIGO and Advanced Virgo detectors. Using Fermi-GBM onboard triggers and subthreshold gamma-ray burst (GRB) candidates found in the Fermi-GBM ground analyses, the Targeted Search and the Untargeted Search, we investigate whether there are any coincident GRBs associated with the GWs. We also search the Swift-BAT rate data around the GW times to determine whether a GRB counterpart is present. No counterparts are found. Using both the Fermi-GBM Targeted Search and the Swift-BAT search, we calculate flux upper limits and present joint upper limits on the gamma-ray luminosity of each GW. Given these limits, we constrain theoretical models for the emission of gamma rays from binary black hole mergers

Constraints on the cosmic expansion history from GWTC–3

We use 47 gravitational wave sources from the Third LIGO–Virgo–Kamioka Gravitational Wave Detector Gravitational Wave Transient Catalog (GWTC–3) to estimate the Hubble parameter H(z), including its current value, the Hubble constant H0. Each gravitational wave (GW) signal provides the luminosity distance to the source, and we estimate the corresponding redshift using two methods: the redshifted masses and a galaxy catalog. Using the binary black hole (BBH) redshifted masses, we simultaneously infer the source mass distribution and H(z). The source mass distribution displays a peak around 34 M⊙, followed by a drop-off. Assuming this mass scale does not evolve with the redshift results in a H(z) measurement, yielding ${H}_{0}={68}_{-8}^{+12}\,\mathrm{km}\ \,\ {{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ (68% credible interval) when combined with the H0 measurement from GW170817 and its electromagnetic counterpart. This represents an improvement of 17% with respect to the H0 estimate from GWTC–1. The second method associates each GW event with its probable host galaxy in the catalog GLADE+, statistically marginalizing over the redshifts of each event's potential hosts. Assuming a fixed BBH population, we estimate a value of ${H}_{0}={68}_{-6}^{+8}\,\mathrm{km}\ \,\ {{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ with the galaxy catalog method, an improvement of 42% with respect to our GWTC–1 result and 20% with respect to recent H0 studies using GWTC–2 events. However, we show that this result is strongly impacted by assumptions about the BBH source mass distribution; the only event which is not strongly impacted by such assumptions (and is thus informative about H0) is the well-localized event GW190814

Measurement of the Z boson differential cross section in transverse momentum and rapidity in proton-proton collisions at 8 TeV

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