Baryonic Mass Research Articles

Velocity relationships of isolated galaxy pairs in support of MOND-type theories

ABSTRACT The MOND-type theories of AQUADratic Lagrangian (AQUAL) and GRavitational Anti-Screening (GRAS) are applied to isolated galaxy pairs. Theoretical relationships between their intervelocities, line-of-sight velocities, and their baryonic masses will be derived. These relationships will be compared with observations taken of a set of 3970 highly isolated pairs. The theoretical velocity relationships and distributions provided by AQUAL and GRAS are found to be in very good agreement with these observations. This agreement indirectly implies that there is no fall-off in the rotational curves of galaxies, which remain flat out to large distances.

Baryon and meson masses in the Nambu–Jona-Lasinio model: A Bayesian approach

We investigate the capabilities of the Nambu--Jona-Lasinio model to describe and reproduce fundamental vacuum properties of Quantum Chromodynamics, notably the hadronic spectrum. Mesons are described as quark-antiquark bound states at the level of the random phase approximation of the Bethe-Salpeter equation, while baryons are characterized as quark-diquark bound states within the static approximation of the Faddeev equation. Within a Bayesian framework, we constrain the model by phenomenologically known quantities and study the implications on its parameters and predictions in vacuum, as well as the correlations between the two. We find that within our framework, the vacuum masses of mesons and baryons can be reasonably well reproduced. Scalar diquarks need to be significantly bound in order to correctly reproduce the masses of the baryon octet, therefore enforcing values of the scalar diquark coupling larger than what is suggested by the canonical Fierz values. These findings could have important implications on the phenomenology of strongly-interacting matter at high temperature and density as well as of compact star physics.

Mass spectra of singly, doubly, triply light-strange baryons in light of 𝒪(1m2) relativistic correction

The hypercentral Constituent Quark Model (hCQM) has been employed to obtain the resonance masses of hadrons ranging from light, strange to heavy sector. This work is dedicated towards incorporating the higher order correction in the mass so as to improve the spin-order hierarchy. The potential is Coulomb-like part and linear term as confinement part along with the spin–spin interaction terms. In this paper, the light, strange baryon masses have been revisited with correction term with [Formula: see text] and [Formula: see text] and compared with earlier results as well as various other approaches. The slope and intercepts have been recalculated for obtained masses which are expected to aid in experimental findings. The recent results are found to be in good accordance with the experimental range as well as theoretical models.

Systematic analysis of single heavy baryons ΛQ, ΣQ and ΩQ

Motivated by great progresses in experiments in searching for the heavy baryons, we systematically analyze the mass spectra and root mean square radius of single heavy baryons ΛQ, ΣQ and ΩQ. The calculations of the mass spectra are carried out in the frame work of relativized quark model, where the baryon is regarded as a three-body system of quarks. Our results show that the mass of single heavy baryon with λ-mode is lower than those of the ρ-mode and λ-ρ mixing mode, which indicates that the lowest state is dominated by the λ-mode. Basing on this research, we systematically calculate the mass spectra and the root mean square radius of the baryons with λ excited mode. With these predicated mass spectra, the Regge trajectories in the (J, M2) plane are constructed, and the slopes, intercepts of the Regge trajectories are obtained by linear fitting. It is found that all available experimental data are well reproduced by model predictions and fit nicely to the constructed Regge trajectories.

Global Dynamic Scaling Relations of H i-rich Ultra-diffuse Galaxies

The baryonic Tully–Fisher relation (BTFR), which connects the baryonic mass of galaxies with their circular velocities, has been validated across a wide range of galaxies, from dwarf galaxies to massive galaxies. Recent studies have found that several ultra-diffuse galaxies (UDGs) deviate significantly from the BTFR, indicating a galaxy population with abnormal dynamical properties. However, such studies were still confined within a small sample size. In this study, we used the 100% complete Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) to investigate the BTFR of 88 H i-rich UDGs (HUDGs), which is the largest UDG sample with dynamical information. We found that the HUDGs form a continuous distribution in the BTFR diagram, with high-velocity galaxies consistent with normal dwarf galaxies at a 1σ level, and low-velocity galaxies deviating from the BTFR, in line with that reported in the literature. We point out that the observed deviation may be subject to various selection effects or systemic biases. Nevertheless, we found that the significance of the deviation of HUDGs from the BTFR and TFR are different, i.e., they either deviate from the BTFR or from the TFR. Our result indicates that a high gas fraction may play an important role in explaining the deviation of HUDGs from BTFR.

A Suggested Alternative to Dark Matter in Galaxies: I. Theoretical Considerations

Abstract: We have resorted to a modified form of Modified Newtonian Dynamics (MOND) to account for galactic rotation curves, as a possible alternative to the dark-matter paradigm, by assuming that either (i) the gravitational constant is a function of distance scale, or, (ii) the gravitational-to-inertial mass ratio is a function of distance scale. We have used a linear approximation of each function, from which two new parameters appeared that have to be determined: G1, the first-order coefficient of gravitational coupling and C1, the first-order coefficient of gravitational-to-inertial mass ratio. We have generated simplified theoretical rotation curves for some hypothetical spherical galaxies by varying our model’s parameters. We have concluded that our model gives a qualitatively and quantitatively acceptable behavior of the galactic-rotation curves for some values of those parameters: G1 between around 10-31 and 10-30 m2 s-2 kg-1; or, C1 between 10-21 and 10-20 m-1. Our model also may imply the existence of a critical distance at which the MOND effects become significant rather than a critical acceleration. Furthermore, assuming that the critical centripetal acceleration in our model is equivalent to that in Milgrom’s MOND (a_0), we found that a_0 is not a constant, but a linear function of the galactic baryonic mass (a_0≈〖G_1〗^2 M_b/G_0). We were able to re-derive Milgrom’s version of MOND (〖a_c〗^2/a_0=G_0 M_b/r^2). Keywords: Dark matter, Modified theories of gravity, MOND. PACS Nos.: 95.35.+d; 04.50.Kd.

Stellar cluster formation in a Milky Way-sized galaxy at z > 4 – I. The proto-globular cluster population and the imposter amongst us

ABSTRACT The formation history of globular clusters (GCs) at redshift z > 4 remains an unsolved problem. In this work, we use the cosmological, N-body hydrodynamical ‘zoom-in’ simulation GigaEris to study the properties and formation environment of proto-GC candidates in the region surrounding the progenitor of a Milky Way-sized galaxy. The simulation employs a modern implementation of smoothed-particle hydrodynamics, including metal-line cooling and metal and thermal diffusion. We define proto-GC candidate systems as gravitationally bound stellar systems with baryonic mass fraction Fb ≥ 0.75 and stellar velocity dispersion σ⋆ < 20 km s−1. At z = 4.4, we identify nine systems that satisfy our criteria, all of which form between 10 and 30 kpc from the centre of the main host. Their baryonic masses are in the range 105–107 M⊙. By the end of the simulation, they still have a relatively low stellar mass (M⋆ ∼ 104–105 M⊙) and a metallicity (−1.8 ≲ [Fe/H] ≲ −0.8) similar to the blue Galactic GCs. All of the identified systems except one appear to be associated with gas filaments accreting onto the main galaxy in the circum-galactic region and formed at z = 5–4. The exception is the oldest object, which appears to be a stripped compact dwarf galaxy that has interacted with the main halo between z = 5.8 and z = 5.2 and has lost its entire dark matter content due to tidal mass loss.

Summing up the Feynman diagrams: Toward quantum gluonodynamics

Summing up all Feynman diagrams describing an elementary particle can provide a measure of the energy and, with it, the mass of that particle. Moreover, a single mass quantum can be used to convert the Feynman sum into the particle mass. In the following, a mass formula for the calculation of the baryon and meson masses is introduced and explained. This formula involves calculating the number of possible Feynman diagrams and multiplying it by an elementary mass quantum. The mass formula results from a generalization of the connection between the electromagnetic coupling constant alpha (Sommerfelds constant) and the Rydberg constant. This mass formula adds an energy parametrization to the standard model, an important component that has been missing to date. Afterward, this mass formula is interpreted, leading to an interpretation of the elementary particles that is similar to the way in which molecules are interpreted. In this interpretation, gluons take the place of electrons in the case of elementary particles.

First results on QCD+QED with C* boundary conditions

Accounting for isospin-breaking corrections is critical for achieving subpercent precision in lattice computations of hadronic observables. A way to include QED and strong-isospin-breaking corrections in lattice QCD calculations is to impose C⋆ boundary conditions in space. Here, we demonstrate the computation of a selection of meson and baryon masses on two QCD and five QCD+QED gauge ensembles in this setup, which preserves locality, gauge and translational invariance all through the calculation. The generation of the gauge ensembles is performed for two volumes, and three different values of the renormalized fine-structure constant at the U-symmetric point, corresponding to the SU(3)-symmetric QCD in the two ensembles where the electromagnetic coupling is turned off. We also present our tuning strategy and, to the extent possible, a cost analysis of the simulations with C⋆ boundary conditions.

Reconstructing the extended structure of multiple sources strongly lensed by the ultra-massive elliptical galaxy SDSS J0100+1818

We study the total and baryonic mass distributions of the deflector SDSS J0100+1818 through a full strong lensing analysis. The system is composed of an ultra-massive early-type galaxy at z = 0.581, with a total stellar mass of (1.5 ± 0.3)×1012 M⊙ and a stellar velocity dispersion of (450 ± 40) km s−1, surrounded by ten multiple images of three background sources, two of which are spectroscopically confirmed at z = 1.880. We took advantage of high-resolution HST photometry and VLT/X-shooter spectroscopy to measure the positions of the multiple images and performed a strong lensing study with the software GLEE. We tested different total mass profiles for the lens and modeled the background sources first as point-like and then as extended objects. We successfully predict the positions of the observed multiple images and reconstruct over approximately 7200 HST pixels the complex surface brightness distributions of the sources. We measured the cumulative total mass profile of the lens and find a total mass value of (9.1 ± 0.1)×1012 M⊙, within the Einstein radius of approximately 42 kpc, and stellar-over-total mass fractions ranging from (49 ± 12)%, at the half-light radius (Re = 9.3 kpc) of the lens galaxy, to (10 ± 2)%, in the outer regions (R = 70 kpc). These results suggest that the baryonic mass component of SDSS J0100+1818 is very concentrated in its core and that the lens early-type galaxy (or group) is immersed in a massive dark matter halo, which allows it to act as a powerful gravitational lens, creating multiple images with exceptional angular separations. This is consistent with what has been found in other ultra-high-mass candidates at intermediate redshift. We also measured the physical sizes of the distant sources, resolving them down to a few hundred parsecs. Finally, we quantify and discuss a relevant source of systematic uncertainties on the reconstructed sizes of background galaxies, associated with the adopted lens total mass model.

Strong decay widths and mass spectra of charmed baryons

The total decay widths of the charmed baryons are calculated by means of the $^{3}{P}_{0}$ model. Our calculations consider in the final states: the charmed baryon-(vector/pseudoscalar) meson pairs and the (octet/decuplet) baryon-(pseudoscalar/vector) charmed meson pairs, within a constituent quark model. Furthermore, we calculate the masses of the charmed baryon ground states and their excitations up to the $D$-wave in a constituent quark model both in the three-quark and in the quark-diquark schemes, utilizing a Hamiltonian model based on a harmonic oscillator potential plus a mass splitting term that encodes the spin, spin-orbit, isospin, and flavor interactions. The parameters of the Hamiltonian model are fitted to the experimental data of the charmed baryon masses and decay widths. As the experimental uncertainties of the data affect the fitted model parameters, we have thoroughly propagated these uncertainties into our predicted charmed baryon masses and decay widths via a Monte Carlo bootstrap approach, which is often absent in other theoretical studies on this subject. Our quantum number assignments and predictions of the masses and strong partial decay widths are in reasonable agreement with the available data. Thus, our results show the ability to guide future measurements in LHCb, Belle and Belle II experiments. Finally, the appendices provide some details of our calculations, in which we include the flavor coupling coefficients, which are useful for further theoretical investigations.

Inverse mass ordering of light scalar mesons in the Nambu–Jona-Lasinio model

AbstractThe masses of the low-lying scalar mesons are investigated in the three-flavor Nambu–Jona-Lasinio (NJL) model by treating the scalar mesons as composite objects of a quark and an antiquark. It is known that a simple $\bar{q}q$ picture fails to reproduce the so-called inverse mass ordering for the scalar mesons. Recently a new mechanism to reproduce the observed mass spectrum of the scalar mesons was proposed in a linear sigma model by introducing flavor symmetry breaking induced by the U(1) axial anomaly. Motivated by this proposal, we examine whether this new mechanism also works in the NJL model. By calculating the scalar meson masses, we find that the NJL model reproduces the observed mass ordering with sufficient strength of the new term. With this mechanism, it turns out that the constituent strange quark mass becomes degenerate to that of the up and down quarks if the inverse mass ordering is reproduced. We also discuss the scalar diquark masses to check the consistency of the degeneracy of the constituent quark masses with the light baryon masses.

Probing the baryon mass fraction in IGM and its redshift evolution with fast radio bursts using Bayesian inference method

ABSTRACT We investigate the fraction of baryon mass in intergalactic medium (fIGM), using 18 well-localized fast radio bursts (FRBs) in the redshift range z ∈ (0.0039, 0.66). We construct a five-parameter Bayesian inference model, with the probability distributions of dispersion measures (DMs) of IGM and host galaxy properly taken into account. To check the possible redshift evolution, we parametrize fIGM as a mildly evolving function of redshift, fIGM = fIGM,0[1 + αz/(1 + z)]. By simultaneously constraining five parameters, we get $f_\mathrm{IGM,0} = 0.92^{+0.06}_{-0.12}$ and $\alpha = 0.49^{+0.59}_{-0.47}$, and the median value of DM of host galaxy is $\exp (\mu)=72.49^{+33.31}_{-25.62}~{\rm pc ~ cm ^ {-3}}$. By fixing two parameters that can be constrained independently with other observations, we obtain $\alpha =0.11^{+0.24}_{-0.27}$ in the three-parameter fit, which is consistent with zero within 1σ uncertainty. Monte Carlo simulations show that even 300 FRBs are not enough to tightly constrain five parameters simultaneously. This is mainly caused by the correlation between parameters. Only if two parameters are fixed, 100 FRBs are necessary to achieve unbiased constraints on the remaining parameters.

Cosmological model-independent constraints on the baryon fraction in the IGM from fast radio bursts and supernovae data

Fast Radio Bursts (FRBs) are millisecond-duration radio transients with an observed dispersion measure (DM) greater than the expected Milky Way contribution, which suggests that such events are of extragalactic origin. Although some models have been proposed to explain the physics of the pulse, the mechanism behind the FRBs emission is still unknown. From FRBs data with known host galaxies, the redshift is directly measured and can be combined with estimates of the DM to constrain the cosmological parameters, such as the baryon number density and the Hubble constant. However, the poor knowledge of the fraction of baryonic mass in the intergalactic medium (f_{IGM}) and its degeneracy with the cosmological parameters impose limits on the cosmological application of FRBs. In this work we present a cosmological model-independent method to determine the evolution of f_{IGM} combining the latest FRBs observations with localized host galaxy and current supernovae data. We consider constant and time-dependent f_{IGM} parameterizations and show, through a Bayesian model selection analysis, that a conclusive answer about the time-evolution of f_{IGM} depend strongly on the DM fluctuations due to the spatial variation in cosmic electron density (delta ). In particular, our analysis show that the evidence varies from strong (in favor of a growing evolution of f_{IGM} with redshift) to inconclusive, as larger values of delta are considered.

Discovery of an Isolated Dark Dwarf Galaxy in the Nearby Universe

Based on a new H i survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with the Pan-STARRS1 images, we identified an isolated H i cloud without any optical counterpart, named FAST J0139+4328. The newly discovered H i cloud appears to be a typical disk galaxy since it has a double-peak shape in the global H i profile and an S-like rotation structure in the velocity-position diagram. Moreover, this disk galaxy has an extremely low absolute magnitude (M B > −10.0 mag) and stellar mass (<6.9 ×105 M ⊙). Furthermore, we obtained that the H i mass of this galaxy is (8.3 ± 1.7) ×107 M ⊙, and the dynamical mass to total baryonic mass ratio is 47 ± 27, implying that dark matter dominates over baryons in FAST J0139+4328. These findings provide observational evidence that FAST J0139+4328 is an isolated dark dwarf galaxy with a redshift of z = 0.0083. This is the first time that an isolated dark galaxy has been detected in the nearby universe.

GalCEM. I. An Open-source Detailed Isotopic Chemical Evolution Code

This is the first of a series of papers that will introduce a user-friendly, detailed, and modular Galactic Chemical Evolution Model, GalCEM, that tracks isotope masses as a function of time in a given galaxy. The list of tracked isotopes automatically adapts to the complete set provided by the input yields. The present iteration of GalCEM tracks 86 elements broken down into 451 isotopes. The prescription includes massive stars, low-to-intermediate-mass stars, and Type Ia supernovae as enrichment channels. We have developed a preprocessing tool that extracts multidimensional interpolation curves from the input yield tables. These interpolation curves improve the computation speeds of the full convolution integrals, which are computed for each isotope and for each enrichment channel. We map the integrand quantities onto consistent array grids in order to perform the numerical integration at each time step. The differential equation is solved with a fourth-order Runge–Kutta method. We constrain our analysis to the evolution of all light and intermediate elements from carbon to zinc, and lithium. Our results are consistent up to the extremely metal-poor regime with Galactic abundances. We provide tools to track the mass rate change of individual isotopes on a typical spiral galaxy with a final baryonic mass of 5 × 1010 M ⊙. Future iterations of the work will extend to the full periodic table by including the enrichment from neutron-capture channels as well as spatially dependent treatments of galaxy properties. GalCEM is publicly available at https://github.com/egjergo/GalCEM.

Exploring the cosmological dark matter coincidence using infrared fixed points

The asymmetric dark matter (ADM) paradigm is motivated by the apparent coincidence between the cosmological mass densities of visible and dark matter, $\Omega_\mathrm{DM} \simeq 5\Omega_\mathrm{VM}$. However, most ADM models only relate the number densities of visible and dark matter, and do not motivate the similarity in their particle masses. One exception is a framework introduced by Bai and Schwaller, where the dark matter is a confined state of a dark QCD-like gauge group, and the confinement scales of visible and dark QCD are related by a dynamical mechanism utilising infrared fixed points of the two gauge couplings. We build upon this framework by properly implementing the dependence of the results on the initial conditions for the gauge couplings in the UV. We then reassess the ability of this framework to naturally explain the cosmological mass density coincidence, and find a reduced number of viable models. We identify features of the viable models that allow them to naturally relate the masses of the dark baryon and the proton while also avoiding collider constraints on the new particle content introduced.

Concepts and Results of a Practical Model of Quantum Cosmology

We have proposed new concepts and results pertaining to a very simple and practical model of quantum cosmology based on light speed expanding black hole universe having no dark matter and no dark energy. Big bang concept can be replaced with Plank scale. Cosmic temperature and expansion rate can be related with scaled Hawking’s Black hole temperature formula. Starting from cosmic center to cosmic boundary, a decreasing trend of galactic acceleration can be understood with continuous light speed expansion at cosmic boundary. Issue of ‘causal disconnection of galaxies at large scale distances’ can be eliminated by cosmic black hole physical concepts. Dark matter concept can be eliminated with ‘super gravity of galactic baryonic mass caused by weak interaction’. Cosmic inflation and dark energy concepts can be eliminated with ‘light speed expansion’. To fit the estimated light travel distances and to eliminate the dark energy, cosmic red shift can be redefined

Predicting the masses of exotic hadrons with data augmentation using multilayer perceptron

Recently, there have been significant developments in neural networks, which led to the frequent use of neural networks in the physics literature. This work focuses on predicting the masses of exotic hadrons, doubly charmed and bottomed baryons using neural networks trained on meson and baryon masses that are determined by experiments. The original dataset has been extended using the recently proposed artificial data augmentation methods. We have observed that the neural network’s predictive ability will increase with the use of augmented data. The results indicated that data augmentation techniques play an essential role in improving neural network predictions; moreover, neural networks can make reasonable predictions for exotic hadrons, doubly charmed, and doubly bottomed baryons. The results are also comparable to Gaussian Process and Constituent Quark Model.

Capture of Dark Matter Particles by a Galaxy in the Case of a Bimodal Distribution of Their Velocities

We have analyzed the rate of capture of dark matter (DM) particles by the galaxy in the case of the existence of two different types of DM or a bimodal velocity distribution function for DM. It is shown that, in addition to the scenario considered in our previous work which is based on the assumption of an unimodal distribution, more complex scenarios are possible in which the transition to the state of intense capture and/or exit from it can occur in two stages. A detailed description is given of the change in the curve describing the rate of capture of dark matter particles as a function of the rate of increase in the baryon mass of the galaxy for various values of the rate of decrease of the DM density.