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1
LEDDIG, TORSTEN. "INVESTIGATION OF B-MESON DECAYS INTO BARYONS WITH THE BABAR DETECTOR". International Journal of Modern Physics A 26, n. 03n04 (10 febbraio 2011): 545–48. http://dx.doi.org/10.1142/s0217751x11051986.
Testo completoAbstract (sommario):
We report on investigations of B-meson decays into baryons with the BABAR detector. The comparison of different decay channels reveals that higher multiplicities are preferred for these decays. Furthermore, an enhancement in the invariant baryon-antibaryon mass distribution can be observed in several baryonic decay modes. In addition, the study of baryon resonances seen in baryonic B-meson decays is presented.
2
Pardo Calderón, Leandro Manuel. "Baryon Acoustic Oscillations. Equation and physical interpretation". Scientia et Technica 23, n. 2 (30 giugno 2018): 263–68. http://dx.doi.org/10.22517/23447214.17251.
Testo completoAbstract (sommario):
Baryon Acoustic Oscillations are a phenomenon occurred before matter-radiation decoupling, characterized because the baryonic matter perturbation presents oscillations, as the name suggests. These perturbations propagate like a pressure wave on the photon-baryon fluid produced by gravitational potentials, which join the baryonic matter, and collisions of baryons and photons, which scatter it. This paper shows the Baryon Acoustic Oscillations equation and it provides its physical meaning. Besides, it presents software CAMB as a tool to find BAO equation solutions and support for its physical description.
3
GARCIA-RECIO, C., L. L. SALCEDO, D. GAMERMANN, J. NIEVES, O. ROMANETS e L. TOLOS. "CHARMING BARYONS". International Journal of Modern Physics: Conference Series 26 (gennaio 2014): 1460124. http://dx.doi.org/10.1142/s2010194514601240.
Testo completoAbstract (sommario):
We study odd-parity baryonic resonances with one heavy and three light flavors, dynamically generated by meson-baryon interactions. Special attention is paid to Heavy Quark Spin Symmetry (HQSS), hence pseudoscalar and vector mesons and baryons with Jπ = 1/2+ and 3/2+ are considered as constituent hadrons. For the hidden-charm sector ([Formula: see text]), the meson-baryon Lagrangian with Heavy Flavor Symmetry is constructed by a minimal extension of the SU(3) Weinberg-Tomozawa (WT) Lagrangian to fulfill HQSS, such that not new parameters are needed. This interaction can be presented in different formal ways: as a Field Lagrangian, as Hadron creation-annihilation operators, as SU(6)×HQSS group projectors and as multichannel matrices. The multichannel Bethe-Salpeter equation is solved for odd-parity light baryons, hidden-charm N and Δ and Beauty Baryons (Λb). Results of calculations with this model are shown in comparison with other models and experimental values for baryonic resonances.
4
Khan, Mehbub, Yun Hao e Jong-Ping Hsu. "Baryonic Force for Accelerated Cosmic Expansion and Generalized U1b Gauge Symmetry in Particle-Cosmology". EPJ Web of Conferences 168 (2018): 04004. http://dx.doi.org/10.1051/epjconf/201816804004.
Testo completoAbstract (sommario):
Based on baryon charge conservation and a generalized Yang-Mills symmetry for Abelian (and non-Abelian) groups, we discuss a new baryonic gauge field and its linear potential for two point-like baryon charges. The force between two point-like baryons is repulsive, extremely weak and independent of distance. However, for two extended baryonic systems, we have a dominant linear force α r. Thus, only in the later stage of the cosmic evolution, when two baryonic galaxies are separated by an extremely large distance, the new repulsive baryonic force can overcome the gravitational attractive force. Such a model provides a gauge-field-theoretic understanding of the late-time accelerated cosmic expansion. The baryonic force can be tested by measuring the accelerated Wu-Doppler frequency shifts of supernovae at different distances.
5
HOSAKA, A., H. TOKI e M. TAKAYAMA. "BARYON SPECTRA IN DEFORMED OSCILLATOR QUARK MODEL". Modern Physics Letters A 13, n. 21 (10 luglio 1998): 1699–707. http://dx.doi.org/10.1142/s0217732398001777.
Testo completoAbstract (sommario):
We study theoretically the baryon spectra in terms of a deformed oscillator quark (DOQ) model. This model is motivated by confinement of quarks and chiral symmetry breaking, which are the most important nonperturbative phenomena of QCD. The minimization of the DOQ Hamiltonian with respect to the deformation for each principal quantum number results in deformations for the intrinsic states of excited baryonic states. We find that the resulting baryon spectra agree very well with the existing experimental data including SU(3) baryons. The spatial deformation of the baryonic excited states carry useful information on the quark confinement and provide a clue to understand the confining mechanism.
6
Dominguez-Tenreiro, Rosa, e Gustavo Yepes. "On the Possibility of a Higher Baryonic Contribution to Dark Matter". Symposium - International Astronomical Union 130 (1988): 592. http://dx.doi.org/10.1017/s0074180900137180.
Testo completoAbstract (sommario):
The most stringent constraint against baryonic dark matter is provided by primordial nucleosynthesis. Agreement between theory and observations is reachedonly for a limited range of the baryon-to-photon ratio ‘LR, namely , which implies that, in standard cosmological frameworks, the universe cannot be closed by baryons.
7
Kostyuk, Ivan, Robert Lilow e Matthias Bartelmann. "Baryon-photon interactions in Resummed Kinetic Field Theory". Journal of Cosmology and Astroparticle Physics 2023, n. 09 (1 settembre 2023): 032. http://dx.doi.org/10.1088/1475-7516/2023/09/032.
Testo completoAbstract (sommario):
Abstract We explore how interactions between baryons and photons can be incorporated into Kinetic Field Theory (KFT), a description of cosmic structure formation based on classical Hamiltonian particle dynamics. In KFT, baryons are described as effective mesoscopic particles which represent fluid elements governed by the hydrodynamic equations. In this paper, we modify the mesoscopic particle model to include pressure effects exerted on baryonic matter through interactions with photons. As a proof of concept, we use this extended mesoscopic model to describe the tightly coupled baryon-photon fluid between matter-radiation equality and recombination. We show that this model can qualitatively reproduce the formation of baryon-acoustic oscillations in the cosmological power spectrum.
8
Martinsson, Thomas, Marc Verheijen, Matthew Bershady, Kyle Westfall, David Andersen e Rob Swaters. "Mass distributions in disk galaxies". Proceedings of the International Astronomical Union 11, S321 (marzo 2016): 283. http://dx.doi.org/10.1017/s1743921316011169.
Testo completoAbstract (sommario):
AbstractWe present results on luminous and dark matter mass distributions in disk galaxies from the DiskMass Survey. As expected for normal disk galaxies, stars dominate the baryonic mass budget in the inner region of the disk; however, at about four optical scale lengths (hR) the atomic gas starts to become the dominant contributor. Unexpectedly, we find the total baryon to dark-matter fraction within a galaxy stays nearly constant with radius from 1hR out to at least 6hR, with a baryon fraction of 15–50% among galaxies. On average, only one third of the mass within 2.2hR in a disk galaxy is baryonic and these baryons appear to have had only a minor effect on the distribution of the dark matter.
9
Ghalenovi, Zahra. "Study of Heavy Strange Baryons in a Hypercentral Quark Model". International Journal of Modern Physics: Conference Series 46 (gennaio 2018): 1860037. http://dx.doi.org/10.1142/s2010194518600376.
Testo completoAbstract (sommario):
In this work, we study the properties of the heavy baryons with strangeness employing a constituent quark model in the hypercentral approach. The potential model considers the interactions arising the one-gluon exchange, Goldstone boson exchange and confinement, aspects of underlying theory, quantum chromodynamics (QCD). By solving three-body Schrodinger equation of baryonic system, we obtain the ground as well as the corresponding energy eigenvalues of the system. Using the obtained energies, we calculate the baryon spectrum. We extend our scheme to predict the radiative decay width of the charm baryons. A comparison of our results with those of other works and experimental data is also presented.
10
Huang, Hung-Jin, Tim Eifler, Rachel Mandelbaum, Gary M. Bernstein, Anqi Chen, Ami Choi, Juan García-Bellido et al. "Dark energy survey year 1 results: Constraining baryonic physics in the Universe". Monthly Notices of the Royal Astronomical Society 502, n. 4 (15 febbraio 2021): 6010–31. http://dx.doi.org/10.1093/mnras/stab357.
Testo completoAbstract (sommario):
ABSTRACT Measurements of large-scale structure are interpreted using theoretical predictions for the matter distribution, including potential impacts of baryonic physics. We constrain the feedback strength of baryons jointly with cosmology using weak lensing and galaxy clustering observables (3 × 2pt) of Dark Energy Survey (DES) Year 1 data in combination with external information from baryon acoustic oscillations (BAO) and Planck cosmic microwave background polarization. Our baryon modelling is informed by a set of hydrodynamical simulations that span a variety of baryon scenarios; we span this space via a Principal Component (PC) analysis of the summary statistics extracted from these simulations. We show that at the level of DES Y1 constraining power, one PC is sufficient to describe the variation of baryonic effects in the observables, and the first PC amplitude (Q1) generally reflects the strength of baryon feedback. With the upper limit of Q1 prior being bound by the Illustris feedback scenarios, we reach $\sim 20{{\ \rm per\ cent}}$ improvement in the constraint of $S_8=\sigma _8(\Omega _{\rm m}/0.3)^{0.5}=0.788^{+0.018}_{-0.021}$ compared to the original DES 3 × 2pt analysis. This gain is driven by the inclusion of small-scale cosmic shear information down to 2.5 arcmin, which was excluded in previous DES analyses that did not model baryonic physics. We obtain $S_8=0.781^{+0.014}_{-0.015}$ for the combined DES Y1+Planck EE+BAO analysis with a non-informative Q1 prior. In terms of the baryon constraints, we measure $Q_1=1.14^{+2.20}_{-2.80}$ for DES Y1 only and $Q_1=1.42^{+1.63}_{-1.48}$ for DESY1+Planck EE+BAO, allowing us to exclude one of the most extreme AGN feedback hydrodynamical scenario at more than 2σ.
11
Bertschinger, Edmund. "Galaxy Formation in a Universe Dominated by Cold Dark Matter". Symposium - International Astronomical Union 117 (1987): 360. http://dx.doi.org/10.1017/s0074180900150478.
Testo completoAbstract (sommario):
ABSTRACT The mass spectrum of bound baryonic systems (galaxies and globular clusters) is computed as a function of redshift in an Einstein-de Sitter (Ω=1) universe dominated by weakly interacting, cold dark matter. Baryons are assumed to fall into primordial density peaks in the cold particle distribution when the mass in the peaks exceeds the baryon Jeans mass. The distribution of peaks is computed using Gaussian statistics. As the universe expands the baryonic mass attached to a given peak increases because of infall (treated in a spherical approximation), and new peaks of lower amplitude become nonlinear. Globular clusters form first (by z∼40 if the galaxies represent a biased mass distribution). The remaining gas may be reheated to ∼10000 K if a few percent of globular cluster (or Pop. III) stars are very massive. Reheating increases the baryon Jeans mass and delays galaxy formation until z≲10. The present method reproduces the shape (but not the amplitude) of the Schechter galaxy mass function when merging of substructure is included in an approximate fashion.
12
Wright, Ruby J., Claudia del P. Lagos, Chris Power e Peter D. Mitchell. "The impact of stellar and AGN feedback on halo-scale baryonic and dark matter accretion in the eagle simulations". Monthly Notices of the Royal Astronomical Society 498, n. 2 (14 agosto 2020): 1668–92. http://dx.doi.org/10.1093/mnras/staa2359.
Testo completoAbstract (sommario):
ABSTRACT We use the eagle suite of hydrodynamical simulations to analyse accretion rates (and the breakdown of their constituent channels) on to haloes over cosmic time, comparing the behaviour of baryons and dark matter (DM). We also investigate the influence of sub-grid baryon physics on halo-scale inflow, specifically the consequences of modelling radiative cooling, as well as feedback from stars and active galactic nuclei (AGNs). We find that variations in halo baryon fractions at fixed mass (particularly their circumgalactic medium gas content) are very well correlated with variations in the baryon fraction of accreting matter, which we show to be heavily suppressed by stellar feedback in low-mass haloes, Mhalo ≲ 1011.5 M⊙. Breaking down accretion rates into first infall, recycled, transfer, and merger components, we show that baryons are much more likely to be smoothly accreted than to have originated from mergers when compared to DM, finding (averaged across halo mass) a merger contribution of $\approx 6{{\ \rm per\ cent}}$ for baryons, and $\approx 15{{\ \rm per\ cent}}$ for DM at z ≈ 0. We also show that the breakdown of inflow into different channels is strongly dependent on sub-grid physics, particularly the contribution of recycled accretion (accreting matter that has been previously ejected from progenitor haloes). Our findings highlight the dual role that baryonic feedback plays in regulating the evolution of galaxies and haloes: by (i) directly removing gas from haloes, and (ii) suppressing gas inflow to haloes.
13
Ciepał, Izabela. "Studies of Time-like Electromagnetic Structure of Baryons with HADES". EPJ Web of Conferences 291 (2024): 01011. http://dx.doi.org/10.1051/epjconf/202429101011.
Testo completoAbstract (sommario):
We present results of studies of Dalitz decays of baryon resonances (R→Ne+e−) in proton-proton (pp) and pion-proton (πp) collisions performed by the HADES collaboration. They provided the first measurement of electromag netic transition form factors of baryons in the time-like region and contribute to the understanding of the photon-baryon coupling and the role of Vector Dom inance Model in a baryonic sector. We discuss also implications of the results to the understanding of the emissivity of dense and hot QCD matter created in heavy-ion collisions and the role played by the in-medium modification of the ρ meson. Further prospects for future studies with pion beams at GSI with HADES are given in the outlook.
14
Khan, Shahid, Viktor Klochkov, Olha Lavoryk, Oleksii Lubynets, Ali Imdad Khan, Andrea Dubla e Ilya Selyuzhenkov. "Machine Learning Application for Λ Hyperon Reconstruction in CBM at FAIR". EPJ Web of Conferences 259 (2022): 13008. http://dx.doi.org/10.1051/epjconf/202225913008.
Testo completoAbstract (sommario):
The Compressed Baryonic Matter experiment at FAIR will investigate the QCD phase diagram in the region of high net-baryon densities. Enhanced production of strange baryons, such as the most abundantly produced Λ hyperons, can signal transition to a new phase of the QCD matter. In this work, the CBM performance for reconstruction of the Λ hyperon via its decay to proton and π− is presented. Decay topology reconstruction is implemented in the Particle-Finder Simple (PFSimple) package with Machine Learning algorithms providing effcient selection of the decays and high signal to background ratio.
15
Castro, T., S. Borgani, M. Costanzi, J. Dakin, K. Dolag, A. Fumagalli, A. Ragagnin et al. "Euclid preparation". Astronomy & Astrophysics 685 (maggio 2024): A109. http://dx.doi.org/10.1051/0004-6361/202348388.
Testo completoAbstract (sommario):
The Euclid photometric survey of galaxy clusters stands as a powerful cosmological tool, with the capacity to significantly propel our understanding of the Universe. Despite being subdominant to dark matter and dark energy, the baryonic component of our Universe holds substantial influence over the structure and mass of galaxy clusters. This paper presents a novel model that can be used to precisely quantify the impact of baryons on the virial halo masses of galaxy clusters using the baryon fraction within a cluster as a proxy for their effect. Constructed on the premise of quasi-adiabaticity, the model includes two parameters, which are calibrated using non-radiative cosmological hydrodynamical simulations, and a single large-scale simulation from the Magneticum set, which includes the physical processes driving galaxy formation. As a main result of our analysis, we demonstrate that this model delivers a remarkable 1% relative accuracy in determining the virial dark matter-only equivalent mass of galaxy clusters starting from the corresponding total cluster mass and baryon fraction measured in hydrodynamical simulations. Furthermore, we demonstrate that this result is robust against changes in cosmological parameters and against variation of the numerical implementation of the subresolution physical processes included in the simulations. Our work substantiates previous claims regarding the impact of baryons on cluster cosmology studies. In particular, we show how neglecting these effects would lead to biased cosmological constraints for a Euclid-like cluster abundance analysis. Importantly, we demonstrate that uncertainties associated with our model arising from baryonic corrections to cluster masses are subdominant when compared to the precision with which mass–observable (i.e. richness) relations will be calibrated using Euclid and to our current understanding of the baryon fraction within galaxy clusters.
16
Schramm, D. N. "Cosmological Dark Matter". International Journal of Modern Physics D 06, n. 04 (agosto 1997): 393–407. http://dx.doi.org/10.1142/s0218271897000236.
Testo completoAbstract (sommario):
The basic arguments for cosmological dark matter are reviewed. It is shown that the Big Bange Nucleosynthesis constraints on the cosmological baryon density, when compared with dynamical arguments, demonstrate that the bulk of the baryons are dark and also that the bulk of the matter in the universe is nonbaryonic. The recent extragalactic deuterium observations as well as the other light element abundances were examined in detail as is the argument on the number of neutrino flavors. Arguments from recent MACHO/EROS observations of halo dark matter seem to imply that at least some of the dark baryons are in the halos of galaxies. Comparison of baryonic density arguments with recent x-ray cluster data is also made. Discussion of the interface of density and age arguments is also presented.
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Schramm, D. N. "Big Bang Nucleosynthesis". Symposium - International Astronomical Union 187 (2002): 1–15. http://dx.doi.org/10.1017/s0074180900113695.
Testo completoAbstract (sommario):
Big Bang Nucleosynthesis (BBN) is on the verge of undergoing a transformation now that extragalactic deuterium is being measured. Previously, the emphasis was on demonstrating the concordance of the Big Bang Nucleosynthesis model with the abundances of the light isotopes extrapolated back to their primordial values using stellar and Galactic evolution theories. Once the primordial deuterium abundance is converged upon, the nature of the field will shift to using the much more precise primordial D/H to constrain the more flexible stellar and Galactic evolution models (although the question of potential systematic error in 4He abundance determinations remains open). The remarkable success of the theory to date in establishing the concordance has led to the very robust conclusion of BBN regarding the baryon density. The BBN constraints on the cosmological baryon density are reviewed and demonstrate that the bulk of the baryons are dark and also that the bulk of the matter in the universe is non-baryonic. Comparison of baryonic density arguments from Lyman-α clouds, x-ray gas in clusters, the Sunyaev-Zeldovich effect, and the microwave anisotropy are made and shown to be consistent with the BBN value.
18
Karthein, Jamie M., Volker Koch, Claudia Ratti e Volodymyr Vovchenko. "Constraints on hadron resonance gas interactions via first-principles Lattice QCD susceptibilities". EPJ Web of Conferences 276 (2023): 03014. http://dx.doi.org/10.1051/epjconf/202327603014.
Testo completoAbstract (sommario):
We investigate extensions of the Hadron Resonance Gas (HRG) Model beyond the ideal case by incorporating both attractive and repulsive interactions into the model. When considering additional states exceeding those measured with high confidence by the Particle Data Group, attractive corrections to the overall pressure in the HRG model are imposed. On the other hand, we also apply excluded-volume corrections, which ensure there is no overlap of baryons by turning on repulsive (anti)baryon-(anti)baryon interactions. We emphasize the complementary nature of these two extensions and identify combinations of conserved charge susceptibilities that allow us to constrain them separately. In particular, we find interesting ratios of susceptibilities that are sensitive to one correction and not the other. This allows us to constrain the excluded volume and particle spectrum effects separately. Analysis of the available lattice results suggests the presence of both the extra states in the baryonstrangeness sector and the repulsive baryonic interaction, with indications that hyperons have a smaller repulsive core than non-strange baryons. We note that these results are interesting for heavy-ion-collision systems at both the LHC and RHIC.
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Du, Lipei, Chun Shen, Sangyong Jeon e Charles Gale. "Constraints on initial baryon stopping and equation of state from directed flow". EPJ Web of Conferences 296 (2024): 05011. http://dx.doi.org/10.1051/epjconf/202429605011.
Testo completoAbstract (sommario):
Our investigation focuses on the rapidity-dependent directed flow, v1(y), of identified hadrons in Au+Au collisions across a broad range of √SNN from 7.7 to 200 GeV. Employing a (3+1)-dimensional hybrid framework, our study successfully reproduces the characteristic features of the measured v1(y) for both mesons and baryons across the considered beam energies. Notably, our analysis reveals the constraining power of baryonic v1(y) on the initial baryon stopping mechanism. Together with mesonic v1(y), the directed flow serves as a crucial tool for probing the equation of state governing dense nuclear matter at finite chemical potentials.
20
Rauner, Max. "Bits statt Baryonen: In der IT-Branche sind Physikerinnen und Physiker gern gesehen - wer mehr als Programmieren will, muss teamfähig sein." Physik Journal 57, n. 5 (maggio 2001): 33–37. http://dx.doi.org/10.1002/phbl.20010570512.
Testo completo
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Lu, Tianhuan, e Zoltán Haiman. "The impact of baryons on cosmological inference from weak lensing statistics". Monthly Notices of the Royal Astronomical Society 506, n. 3 (10 luglio 2021): 3406–17. http://dx.doi.org/10.1093/mnras/stab1978.
Testo completoAbstract (sommario):
ABSTRACT As weak lensing surveys are becoming deeper and cover larger areas, information will be available on small angular scales down to the arcmin level. To extract this extra information, accurate modelling of baryonic effects is necessary. In this work, we adopt a baryonic correction model, which includes gas both bound inside and ejected from dark matter (DM) haloes, a central galaxy, and changes in the DM profile induced by baryons. We use this model to incorporate baryons into a large suite of DM-only N-body simulations, covering a grid of 75 cosmologies in the Ωm–σ8 parameter space. We investigate how baryons affect Gaussian and non-Gaussian weak lensing statistics and the cosmological parameter inferences from these statistics. Our results show that marginalizing over baryonic parameters degrades the constraints in Ωm–σ8 space by a factor of 2–5 compared to those with baryonic parameters fixed. We also find that combining the lensing power spectrum and peak counts can break the degeneracy between cosmological and baryonic parameters and mitigate the impact of the uncertainty in baryonic physics.
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CIARCELLUTI, PAOLO. "COSMOLOGY WITH MIRROR DARK MATTER I: LINEAR EVOLUTION OF PERTURBATIONS". International Journal of Modern Physics D 14, n. 02 (febbraio 2005): 187–221. http://dx.doi.org/10.1142/s0218271805006213.
Testo completoAbstract (sommario):
This is the first paper of a series devoted to the study of the cosmological implications of the parallel mirror world with the same microphysics as the ordinary one, but having smaller temperature, with a limit set by the BBN constraints. The difference in temperature of the ordinary and mirror sectors generates shifts in the key epochs for structure formation, which proceeds in the mirror sector under different conditions. We consider adiabatic scalar primordial perturbations as an input and analyze the trends of all the relevant scales for structure formation (Jeans length and mass, Silk scale, horizon scale) for both ordinary and mirror sectors, comparing them with the CDM case. These scales are functions of the fundamental parameters of the theory (the temperature of the mirror plasma and the amount of mirror baryonic matter), and in particular they are influenced by the difference between the cosmological key epochs in the two sectors. Then we use a numerical code to compute the evolution in linear regime of density perturbations for all the components of a Mirror Universe: ordinary baryons and photons, mirror baryons and photons, and possibly cold dark matter. We analyze the evolution of the perturbations for different values of mirror temperature and baryonic density, and obtain that for x=T′/T less than a typical value x eq , for which the mirror baryon–photon decoupling happens before the matter–radiation equality, mirror baryons are equivalent to the CDM for the linear structure formation process. Indeed, the smaller the value of x, the closer mirror dark matter resembles standard cold dark matter during the linear regime.
23
Voit, G. Mark, Benjamin D. Oppenheimer, Eric F. Bell, Bryan Terrazas e Megan Donahue. "Black Hole Growth, Baryon Lifting, Star Formation, and IllustrisTNG". Astrophysical Journal 960, n. 1 (19 dicembre 2023): 28. http://dx.doi.org/10.3847/1538-4357/ad0039.
Testo completoAbstract (sommario):
Abstract Quenching of star formation in the central galaxies of cosmological halos is thought to result from energy released as gas accretes onto a supermassive black hole. The same energy source also appears to lower the central density and raise the cooling time of baryonic atmospheres in massive halos, thereby limiting both star formation and black hole growth, by lifting the baryons in those halos to greater altitudes. One predicted signature of that feedback mechanism is a nearly linear relationship between the central black hole’s mass (M BH) and the original binding energy of the halo’s baryons. We present the increasingly strong observational evidence supporting a such a relationship, showing that it extends up to halos of mass M halo ∼ 1014 M ⊙. We then compare current observational constraints on the M BH–M halo relation with numerical simulations, finding that black hole masses in IllustrisTNG appear to exceed those constraints at M halo < 1013 M ⊙ and that black hole masses in EAGLE fall short of observations at M halo ∼ 1014 M ⊙. A closer look at IllustrisTNG shows that quenching of star formation and suppression of black hole growth do indeed coincide with black hole energy input that lifts the halo’s baryons. However, IllustrisTNG does not reproduce the observed M BH–M halo relation because its black holes gain mass primarily through accretion that does not contribute to baryon lifting. We suggest adjustments to some of the parameters in the IllustrisTNG feedback algorithm that may allow the resulting black hole masses to reflect the inherent links between black hole growth, baryon lifting, and star formation among the massive galaxies in those simulations.
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Hofmeister, Anne M., Robert E. Criss e Hugh Chou. "Baryonic Mass Inventory for Galaxies and Rarefied Media from Theory and Observations of Rotation and Luminosity". Galaxies 11, n. 5 (20 settembre 2023): 100. http://dx.doi.org/10.3390/galaxies11050100.
Testo completoAbstract (sommario):
Available inventories of baryonic mass in the universe are based largely on galactic data and empirical calculations made >20 years ago. Values falling below cosmological estimates underlie proposals that certain rarified gassy regions could have extremely high T, which motivated absorption measurements and hydrodynamic models. Yet, the shortfall remains. We inventory the total baryonic mass, focusing on gravitational interactions and updated measurements. A recent analytical inverse method for analyzing galactic rotation curves quantified how baryon mass and associated volumetric density (ρ) depend on distance (r) from galactic centers. The model is based on the dynamical consequences of the observed oblate shape of galaxies and the Virial Theorem. The parameter-free solution provides ρ(r) ∝ 1/r2 which describes star-rich galactic interiors, gas-rich outer discoids, circumgalactic media, and gradation into intergalactic media. Independent observational determinations of baryonic ρ validate that our 1/r2 result describes baryons alone. This solution shows that total baryonic mass associated with any galaxy is 2.4 to 40 times detectable luminosity, depending on galaxy size and spacing. Luminosity data within 50 Mpc show that Andromeda equivalents separated by ~1 Mpc represent the local universe. Combining the above yields (6 ± 2) × 10−25 kg m−3 for the present-day universe. Three other approaches support this high density: (1) evaluating trends and luminosity data near 1000 Mpc; (2) using a recent estimate for the number of galaxies in the universe; (3) calculating an energy balance. We discuss uncertainties in the critical density. Implications of large baryonic ρ are briefly discussed.
25
Courteau, Stéphane. "The Distribution of Mass in (Disk) Galaxies: Maximal or Not?" Proceedings of the International Astronomical Union 10, S309 (luglio 2014): 364–70. http://dx.doi.org/10.1017/s1743921314010540.
Testo completoAbstract (sommario):
AbstractThe relative distribution of matter in galaxies ought to be one of the most definitive predictions of galaxy formation models yet its validation is challenged by numerous observational, theoretical, and operational challenges. All galaxies are believed to be dominated by an invisible matter component in their outskirts. A debate has however been blazing for the last two decades regarding the relative fraction of baryons and dark matter in the inner parts of galaxies: whether galaxies are centrally dominated by baryons (“maximal disk”) is of issue. Some of those debates have been misconstrued on account of operational confusion, such as dark matter fractions being measured and compared at different radii. All galaxies are typically baryon-dominated (maximal) at the center and dark-matter dominated (sub-maximal) in their outskirts; for low-mass galaxies (Vtot ≲ 200 km s− 1), the mass of the dark halo equals the stellar mass at least within 2 disk scale lengths, the transition occurs at larger effective radii for more massive galaxies. An ultimate goal for galaxy structure studies is to achieve accurate data-model comparisons for the relative fractions of baryonic to total matter at any radius.
26
Wicker, Raphaël, Marian Douspis, Laura Salvati e Nabila Aghanim. "Constraining hydrostatic mass bias and cosmological parameters with the gas mass fraction in galaxy clusters". EPJ Web of Conferences 257 (2022): 00046. http://dx.doi.org/10.1051/epjconf/202225700046.
Testo completoAbstract (sommario):
The gas mass fraction in galaxy clusters is a convenient tool to use in the context of cosmological studies. Indeed this quantity allows to constrain the universal baryon fraction Ωb/Ωm, as well as other parameters like the matter density Ωm, the Hubble parameter h or the Equation of State of Dark Energy w. This gas mass fraction is also sensitive to baryonic effects that need to be taken into account, and that translate into nuisance parameters. Two of them are the depletion factor ϒ, and the hydrostatic mass bias B = (1 - b). The first one describes how baryons are depleted in clusters with respect to the universal baryon fraction, while the other encodes the bias coming from the fact that the mass is deduced from X-ray observations under the hypothesis of hydrostatic equilibrium. We will show preliminary results, obtained using the Planck-ESZ clusters observed by XMM-Newton, on both cosmological and cluster parameters. We will notably discuss the investigation on a possible redshift dependence of the mass bias, which is considered to be non-existent in hydrodynamic simulations based on Λ-CDM, and compare our results with other studies.
27
McGaugh, Stacy S. "The Halo by Halo Missing Baryon Problem". Proceedings of the International Astronomical Union 3, S244 (giugno 2007): 136–45. http://dx.doi.org/10.1017/s1743921307013920.
Testo completoAbstract (sommario):
AbstractThe global missing baryon problem – that the sum of observed baryons falls short of the number expected form BBN – is well known. In addition to this, there is also a local missing baryon problem that applies to individual dark matter halos. This halo by halo missing baryon problem is such that the observed mass fraction of baryons in individual galaxies falls short of the cosmic baryon fraction. This deficit is a strong function of circular velocity. I give an empirical estimate of this function, and note the presence of a critical scale of ~ 900 km s−1 therein. I also briefly review Ωb from BBN, highlighting the persistent tension between lithium and the CMB, and discuss some pros and cons of individual galaxies and clusters of galaxies as potential reservoirs of dark baryons.
28
PAGE, PHILIP R. "HYBRID AND CONVENTIONAL BARYONS IN THE FLUX-TUBE AND QUARK MODELS". International Journal of Modern Physics A 20, n. 08n09 (10 aprile 2005): 1791–96. http://dx.doi.org/10.1142/s0217751x05023347.
Testo completoAbstract (sommario):
The status of conventional baryon flux-tubes and hybrid baryons is reviewed. Recent surprises are that a model prediction indicates that hybrid baryons are very weakly produced in glue-rich Ψ decays, and an analysis of electro-production data concludes that the Roper resonance is not a hybrid baryon. The baryon decay flux-tube overlap has been calculated in the flux-tube model, and is discussed here. The behavior of the overlap follows naïve expectations.
29
Hofmeister, Anne M. "Thermodynamic Constraints on the Non-Baryonic Dark Matter Gas Composing Galactic Halos". Galaxies 8, n. 4 (8 novembre 2020): 77. http://dx.doi.org/10.3390/galaxies8040077.
Testo completoAbstract (sommario):
To explain rotation curves of spiral galaxies through Newtonian orbital models, massive halos of non-baryonic dark matter (NBDM) are commonly invoked. The postulated properties are that NBDM interacts gravitationally with baryonic matter, yet negligibly interacts with photons. Since halos are large, low-density gaseous bodies, their postulated attributes can be tested against classical thermodynamics and the kinetic theory of gas. Macroscopic models are appropriate because these make few assumptions. NBDM–NBDM collisions must be elastic to avoid the generation of light, but this does not permit halo gas temperature to evolve. If no such collisions exist, then the impossible limit of absolute zero would be attainable since the other available energy source, radiation, does not provide energy to NBDM. The alternative possibility, an undefined temperature, is also inconsistent with basic thermodynamic principles. However, a definable temperature could be attained via collisions with baryons in the intergalactic medium since these deliver kinetic energy to NBDM. In this case, light would be produced since some proportion of baryon collisions are inelastic, thereby rendering the halo detectable. Collisions with baryons are unavoidable, even if NBDM particles are essentially point masses. Note that <0.0001 × the size of a proton is needed to avoid scattering with γ-rays, the shortest wavelength used to study halos. If only elastic collisions exist, NBDM gas would collapse to a tiny, dense volume (zero volume for point masses) during a disturbance—e.g., cosmic rays. NBDM gas should occupy central galactic regions, not halos, since self-gravitating objects are density stratified. In summary, properties of NBDM halos as postulated would result in violations of thermodynamic laws and in a universe unlike that observed.
30
Bian, Jian-Ming, Vladimir Bytev, Ying Chen, Hong-Ying Jin, Shan Jin, Hu Qin, Xiao-Yan Shen et al. "Chapter 10 Baryon Spectrum". International Journal of Modern Physics A 24, supp01 (maggio 2009): 233–50. http://dx.doi.org/10.1142/s0217751x09046527.
Testo completo
31
Ma, Yong-Liang, e Mannque Rho. "Dichotomy of Baryons as Quantum Hall Droplets and Skyrmions: Topological Structure of Dense Matter". Symmetry 13, n. 10 (7 ottobre 2021): 1888. http://dx.doi.org/10.3390/sym13101888.
Testo completoAbstract (sommario):
We review a new development on the possible direct connection between the topological structure of the Nf=1 baryon as a FQH droplet and that of the Nf≥2 baryons (such as nucleons and hyperons) as skyrmions. This development suggests a possible “domain-wall (DW)” structure of compressed baryonic matter at high density expected to be found in the core of massive compact stars. Our theoretical framework is anchored on an effective nuclear effective field theory that incorporates two symmetries either hidden in the vacuum in QCD or emergent from strong nuclear correlations. It presents a basically different, hitherto undiscovered structure of nuclear matter at low as well as high densities. Hidden “genuine dilaton (GD)” symmetry and hidden local symmetry (HLS) gauge-equivalent at low density to nonlinear sigma model capturing chiral symmetry, put together in nuclear effective field theory, are seen to play an increasingly important role in providing hadron–quark duality in baryonic matter. It is argued that the FQH droplets could actually figure essentially in the properties of the vector mesons endowed with HLS near chiral restoration. This strongly motivates incorporating both symmetries in formulating “first-principles” approaches to nuclear dynamics encompassing from the nuclear matter density to the highest density stable in the Universe.
32
Robertson, Andrew, David Harvey, Richard Massey, Vincent Eke, Ian G. McCarthy, Mathilde Jauzac, Baojiu Li e Joop Schaye. "Observable tests of self-interacting dark matter in galaxy clusters: cosmological simulations with SIDM and baryons". Monthly Notices of the Royal Astronomical Society 488, n. 3 (10 luglio 2019): 3646–62. http://dx.doi.org/10.1093/mnras/stz1815.
Testo completoAbstract (sommario):
ABSTRACT We present bahamas-SIDM, the first large-volume, $(400 \, h^{-1} \mathrm{\, Mpc})^{3}$, cosmological simulations including both self-interacting dark matter (SIDM) and baryonic physics. These simulations are important for two primary reasons: (1) they include the effects of baryons on the dark matter distribution and (2) the baryon particles can be used to make mock observables that can be compared directly with observations. As is well known, SIDM haloes are systematically less dense in their centres, and rounder, than CDM haloes. Here, we find that that these changes are not reflected in the distribution of gas or stars within galaxy clusters, or in their X-ray luminosities. However, gravitational lensing observables can discriminate between DM models, and we present a menu of tests that future surveys could use to measure the SIDM interaction strength. We ray-trace our simulated galaxy clusters to produce strong lensing maps. Including baryons boosts the lensing strength of clusters that produce no critical curves in SIDM-only simulations. Comparing the Einstein radii of our simulated clusters with those observed in the CLASH survey, we find that at velocities around $1000 \mathrm{\, km \, s^{-1}}$ an SIDM cross-section of $\sigma /m \gtrsim 1 \, \mathrm{cm^2 \, g^{-1}}$ is likely incompatible with observed cluster lensing.
33
Borrow, Josh, Daniel Anglés-Alcázar e Romeel Davé. "Cosmological baryon transfer in the simba simulations". Monthly Notices of the Royal Astronomical Society 491, n. 4 (9 dicembre 2019): 6102–19. http://dx.doi.org/10.1093/mnras/stz3428.
Testo completoAbstract (sommario):
ABSTRACT We present a framework for characterizing the large-scale movement of baryons relative to dark matter in cosmological simulations, requiring only the initial conditions and final state of the simulation. This is performed using the spread metric that quantifies the distance in the final conditions between initially neighbouring particles, and by analysing the baryonic content of final haloes relative to that of the initial Lagrangian regions (LRs) defined by their dark matter component. Applying this framework to the simba cosmological simulations, we show that 40 per cent (10 per cent) of cosmological baryons have moved $\gt 1\, h^{-1}\, {\rm Mpc}{}$ ($3\, h^{-1}\, {\rm Mpc}{}$) by z = 0, primarily due to entrainment of gas by jets powered by an active galactic nucleus, with baryons moving up to $12\, h^{-1}\, {\rm Mpc}{}$ away in extreme cases. Baryons decouple from the dynamics of the dark matter component due to hydrodynamic forces, radiative cooling, and feedback processes. As a result, only 60 per cent of the gas content in a given halo at z = 0 originates from its LR, roughly independent of halo mass. A typical halo in the mass range Mvir = 1012–1013 M⊙ only retains 20 per cent of the gas originally contained in its LR. We show that up to 20 per cent of the gas content in a typical Milky Way-mass halo may originate in the region defined by the dark matter of another halo. This inter-Lagrangian baryon transfer may have important implications for the origin of gas and metals in the circumgalactic medium of galaxies, as well as for semi-analytic models of galaxy formation and ‘zoom-in’ simulations.
34
Thakre, Mangleshwar. "Distribution of Baryonic and Dark Matter in Spiral Galaxies". International Journal for Research in Applied Science and Engineering Technology 9, n. VI (30 giugno 2021): 4131–35. http://dx.doi.org/10.22214/ijraset.2021.35925.
Testo completoAbstract (sommario):
In the present paper, the distributions of baryonic and dark matter are derived for 24 northern sky spiral galaxies. The baryonic mass surface density profile is derived, and the component of the galaxies' observed rotation due to the baryons (stars and gas) is computed. Thus, the baryonic rotation curve of each sampled galaxy is separated from the observed rotation curve given in data base (Stapehane Courteau).
35
Bernardini, M., R. Feldmann, D. Anglés-Alcázar, M. Boylan-Kolchin, J. Bullock, L. Mayer e J. Stadel. "From EMBER to FIRE: predicting high resolution baryon fields from dark matter simulations with deep learning". Monthly Notices of the Royal Astronomical Society 509, n. 1 (25 ottobre 2021): 1323–41. http://dx.doi.org/10.1093/mnras/stab3088.
Testo completoAbstract (sommario):
ABSTRACT Hydrodynamic simulations provide a powerful, but computationally expensive, approach to study the interplay of dark matter and baryons in cosmological structure formation. Here, we introduce the EMulating Baryonic EnRichment (EMBER) Deep Learning framework to predict baryon fields based on dark matter-only simulations thereby reducing computational cost. EMBER comprises two network architectures, U-Net and Wasserstein Generative Adversarial Networks (WGANs), to predict 2D gas and H i densities from dark matter fields. We design the conditional WGANs as stochastic emulators, such that multiple target fields can be sampled from the same dark matter input. For training we combine cosmological volume and zoom-in hydrodynamical simulations from the Feedback in Realistic Environments (FIRE) project to represent a large range of scales. Our fiducial WGAN model reproduces the gas and H i power spectra within 10 per cent accuracy down to ∼10 kpc scales. Furthermore, we investigate the capability of EMBER to predict high resolution baryon fields from low resolution dark matter inputs through upsampling techniques. As a practical application, we use this methodology to emulate high-resolution H i maps for a dark matter simulation of a $L=100\, \text{Mpc}\, h^{ -1}$ comoving cosmological box. The gas content of dark matter haloes and the H i column density distributions predicted by EMBER agree well with results of large volume cosmological simulations and abundance matching models. Our method provides a computationally efficient, stochastic emulator for augmenting dark matter only simulations with physically consistent maps of baryon fields.
36
Debackere, Stijn N. B., Joop Schaye e Henk Hoekstra. "How baryons can significantly bias cluster count cosmology". Monthly Notices of the Royal Astronomical Society 505, n. 1 (10 maggio 2021): 593–609. http://dx.doi.org/10.1093/mnras/stab1326.
Testo completoAbstract (sommario):
ABSTRACT We quantify two main pathways through which baryonic physics biases cluster count cosmology. We create mock cluster samples that reproduce the baryon content inferred from X-ray observations. We link clusters to their counterparts in a dark matter-only universe, whose abundances can be predicted robustly, by assuming the dark matter density profile is not significantly affected by baryons. We derive weak lensing halo masses and infer the best-fitting cosmological parameters Ωm, S8 = σ8(Ωm/0.3)0.2, and w0 from the mock cluster sample. We find that because of the need to accommodate the change in the density profile due to the ejection of baryons, weak lensing mass calibrations are only unbiased if the concentration is left free when fitting the reduced shear with NFW profiles. However, even unbiased total mass estimates give rise to biased cosmological parameters if the measured mass functions are compared with predictions from dark matter-only simulations. This bias dominates for haloes with $m_\mathrm{500c} \lt 10^{14.5} \, \rm h^{-1} \, \mathrm{M_\odot }$. For a stage IV-like cluster survey without mass estimation uncertainties, an area $\approx 15\,000 \, \mathrm{deg^2}$ and a constant mass cut of $m_\mathrm{200m,min} = 10^{14} \,\rm h^{-1} \, \mathrm{M_\odot }$, the biases are $-11 \pm 1 \, \mathrm{per\, cent}$ in Ωm, $-3.29 \pm 0.04 \, \mathrm{per\, cent}$ in S8, and $9 \pm 1.5 \, \mathrm{per\, cent}$ in w0. The statistical significance of the baryonic bias depends on how accurately the actual uncertainty on individual cluster mass estimates is known. We suggest that rather than the total halo mass, the (re-scaled) dark matter mass inferred from the combination of weak lensing and observations of the hot gas, should be used for cluster count cosmology.
37
DMITRAŠINOVIĆ, V., KEITARO NAGATA e ATSUSHI HOSAKA. "CHIRAL PROPERTIES OF BARYON INTERPOLATING FIELDS". Modern Physics Letters A 23, n. 27n30 (30 settembre 2008): 2381–84. http://dx.doi.org/10.1142/s0217732308029423.
Testo completoAbstract (sommario):
We study the chiral transformation properties of all possible local (non-derivative) interpolating field operators for baryons consisting of three quarks with two flavors, assuming good isospin symmetry. We derive and use the relations/identities among the baryon operators with identical quantum numbers that follow from the combined color, Dirac and isospin Fierz transformations. These relations reduce the number of independent baryon operators with any given spin and isospin. The Fierz identities also effectively restrict allowed baryon chiral multiplets. It turns out that the chiral multiplets of the baryons are equivalent to their Lorentz representation.
38
Kiren, O. V., Arun Kenath e Chandra Sivaram. "Primordial Planets with an Admixture of Dark Matter Particles and Baryonic Matter". Universe 9, n. 9 (31 agosto 2023): 401. http://dx.doi.org/10.3390/universe9090401.
Testo completoAbstract (sommario):
It has been suggested that primordial planets could have formed in the early universe and the missing baryons in the universe could be explained by primordial free-floating planets of solid hydrogen. Many such planets were recently discovered around the old and metal-poor stars, and such planets could have formed in early epochs. Another possibility for missing baryons in the universe could be that these baryons are admixed with DM particles inside the primordial planets. Here, we discuss the possibility of the admixture of baryons in the DM primordial planets discussed earlier. We consider gravitationally bound DM objects with the DM particles constituting them varying in mass from 20 to100 GeV. Different fractions of DM particles mixed with baryonic matter in forming the primordial planets are discussed. For the different mass range of DM particles forming DM planets, we have estimated the radius and density of these planets with different fractions of DM and baryonic particles. It is found that for heavier-mass DM particles with the admixture of certain fractions of baryonic particles, the mass of the planet increases and can reach or even substantially exceed Jupiter mass. The energy released during the process of merger of such primordial planets is discussed. The energy required for the tidal breakup of such an object in the vicinity of a black hole is also discussed.
39
ISHII, TAKAAKI. "LONG-DISTANCE PROPERTIES OF BARYONS IN THE SAKAI-SUGIMOTO MODEL". International Journal of Modern Physics: Conference Series 21 (gennaio 2013): 187–88. http://dx.doi.org/10.1142/s2010194513009732.
Testo completoAbstract (sommario):
We reconsider the realization of baryons in the Sakai-Sugimoto model. It has previously been shown that, at least with the standard approach to calculations of baryon properties in the theory, one does not reproduce some model-independent predictions for the behavior of baryon electromagnetic form factors connected with long-range pion physics. It is suspected that the pion contributions has been dropped because of the linearization approximations. We study the long-range properties of baryons without relying on the approximations. The baryon solution we obtain gives the correct result for the model-independent ratio of the form factors.
40
LAPORTA, VINCENZO. "FINAL STARE INTERACTION ENHANCEMENT EFFECT ON THE NEAR THRESHOLD $p\bar p$ SYSTEM IN $B^\pm\to p\bar p \pi^\pm$ DECAY". International Journal of Modern Physics A 22, n. 29 (20 novembre 2007): 5401–11. http://dx.doi.org/10.1142/s0217751x07037949.
Testo completoAbstract (sommario):
We discuss the low-mass enhancement effect in the baryon–antibaryon invariant mass in three-body baryonic B decays using final state interactions in the framework of Regge theory. We show that the rescattering between baryonic pair can reproduce the observed mass spectrum.
41
Matskevich, Elena. "Bottom (70,1-) baryon multiplet". E3S Web of Conferences 164 (2020): 01008. http://dx.doi.org/10.1051/e3sconf/202016401008.
Testo completoAbstract (sommario):
The aim of this paper is to derive systems of equations for the amplitudes for the case of negative parity (70,1-) bottom nonstrange baryons and to calculate the masses of these particles. In order to calculate masses of (70,1-) bottom baryons we use the relativistic quark model. The relativistic three-quark equations of the (70,1-) bottom baryon multiplet are derived in the framework of the dispersion relation technique. The relativistic three-quark equations of the (70,1-) bottom baryon multiplet are derived. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitude are obtained. The masses of 21 baryons are predicted.
42
Santos-Santos, Isabel M. E., Julio F. Navarro, Andrew Robertson, Alejandro Benítez-Llambay, Kyle A. Oman, Mark R. Lovell, Carlos S. Frenk, Aaron D. Ludlow, Azadeh Fattahi e Adam Ritz. "Baryonic clues to the puzzling diversity of dwarf galaxy rotation curves". Monthly Notices of the Royal Astronomical Society 495, n. 1 (24 aprile 2020): 58–77. http://dx.doi.org/10.1093/mnras/staa1072.
Testo completoAbstract (sommario):
ABSTRACT We use a compilation of disc galaxy rotation curves to assess the role of the luminous component (‘baryons’) in the rotation curve diversity problem. As in earlier work, we find that rotation curve shape correlates with baryonic surface density: high surface density galaxies have rapidly rising rotation curves consistent with cuspy cold dark matter haloes; slowly rising rotation curves (characteristic of galaxies with inner mass deficits or ‘cores’) occur only in low surface density galaxies. The correlation, however, seems too weak to be the main driver of the diversity. In addition, dwarf galaxies exhibit a clear trend, from ‘cuspy’ systems where baryons are unimportant in the inner mass budget to ‘cored’ galaxies where baryons actually dominate. This trend constrains the various scenarios proposed to explain the diversity, such as (i) baryonic inflows and outflows during galaxy formation; (ii) dark matter self-interactions; (iii) variations in the baryonic mass structure coupled to rotation velocities through the ‘mass discrepancy–acceleration relation’ (MDAR); or (iv) non-circular motions in gaseous discs. Together with analytical modelling and cosmological hydrodynamical simulations, our analysis shows that each of these scenarios has promising features, but none seems to fully account for the observed diversity. The MDAR, in particular, is inconsistent with the observed trend between rotation curve shape and baryonic importance; either the trend is caused by systematic errors in the data or the MDAR does not apply. The origin of the dwarf galaxy rotation curve diversity and its relation to the structure of cold dark matter haloes remains an open issue.
43
Buchmann, Alfons J. "Ernest Henley and the shape of baryons". International Journal of Modern Physics E 27, n. 12 (dicembre 2018): 1840009. http://dx.doi.org/10.1142/s0218301318400098.
Testo completoAbstract (sommario):
Calculations of pion–baryon couplings, baryon quadrupole and octupole moments, baryon spin and orbital angular momentum done in collaboration with Ernest Henley are reviewed. A common theme of this work is the shape of baryons. Also, a personal account of my work with Ernest Henley during the period 1999–2013 is given.
44
PAULINI, MANFRED. "PROPERTIES OF HEAVY B HADRONS". International Journal of Modern Physics A 24, n. 24 (30 settembre 2009): 4413–35. http://dx.doi.org/10.1142/s0217751x09046114.
Testo completoAbstract (sommario):
We review recent measurements of heavy B hadron states including masses and lifetimes of the [Formula: see text] meson as well as excited B states [Formula: see text]. We discuss properties of the [Formula: see text] meson such as lifetime, lifetime difference ΔΓs/Γs and CP violation in [Formula: see text] decays. We also summarize new measurements of the masses and lifetimes of bottom baryons including the [Formula: see text] baryon, the Σb baryon states as well as the [Formula: see text] and [Formula: see text] baryons.
45
Ryden, Barbara S., e James E. Gunn. "The Formation of Galactic Halos in Universes Dominated by Cold Dark Matter". Symposium - International Astronomical Union 117 (1987): 364. http://dx.doi.org/10.1017/s007418090015051x.
Testo completoAbstract (sommario):
If the universe is dominated by cold dark matter (CDM), had an inflationary phase, and has Ω = 1, then the spectrum of primordial density perturbations can be calculated. Using the spectrum calculated by J. Bardeen, we have found the structure of halos which form around peaks in the density. If the initial density is given by , where ) is a Gaussian process, then the mean run of density around a peak is proportional to the correlation function of . If the mass about a peak comes to equilibrium in near-circular orbits, the exact equilibrium configuration can be calculated. The resulting rotation curve for a 1.5σ perturbation is shown as the curve HB in the figure below. As the baryon mass cools and condenses, it drags the CDM in with it, conserving the adiabatic invariants. Putting a 5×1010 M⊙ exponential disk and a 2×1010 M⊙ bulge at the center of the system, the rotation curve of the resulting compressed dark halo is given by the curve HA. D and B show the disk and bulge contributions, and T gives the net velocity. There are many arguments for wanting large galaxies to form from perturbations rarer than 1.5σ. Our spectrum was normalized by assuming that mass clusters as galaxies do on large scales; if Ω = 1, however, galaxies cannot trace the mass and the amplitude must decrease. The flatness of the rotation curve from the baryon-dominated to the CDM-dominated region comes about, in this case, from the imposition of the phenomenological baryon distribution, but the following argument indicates that the result is general. The ratio of baryonic to dark matter is ∼1/15; the rotation parameter Λ, the ratio of rotation velocity to halo dispersion, is also ∼1/15. When baryons fall though the CDM to the point at which they are rotationally supported, their density increases by (15)3. The CDM density increases by (15)2. Hence, baryon and CDM densities are comparable at the mean baryon radius.
46
Meadows, Brian T. "Charm Decays at B Factories". International Journal of Modern Physics A 21, n. 27 (30 ottobre 2006): 5436–44. http://dx.doi.org/10.1142/s0217751x06034574.
Testo completoAbstract (sommario):
Recent results relating to charm baryon and meson decays from the Belle and BABAR experiments are presented. In addition to recent observations for charm hyperons, evidence for a new charm baryon state, the Λc(2940), observed in its decay to D0p is also reported. No evidence for doubly charmed baryons is seen in e+e- interactions. A measurement of the spin of the Ω- hyperon is made using decays of the [Formula: see text] and [Formula: see text] baryons. On the assumption that the spin of the parent baryons are J = 1/2, the assignment J = 3/2 is confirmed and both J = 1/2 and also higher spins are excluded. New results on rare, Cabibbo-suppressed decays of charm mesons are also presented.
47
Russ, James S. "New Results on Heavy Flavor Baryons". International Journal of Modern Physics A 21, n. 27 (30 ottobre 2006): 5482–87. http://dx.doi.org/10.1142/s0217751x06034641.
Testo completoAbstract (sommario):
Heavy flavor baryons are attractive systems for testing effective theories for weak lifetime and decay systematics. Recently, new experimental results have mitigated one historic problem in the weak lifetime systematics and continued another. The charm baryon system continues to show new high mass, narrow states well isolated from one another. The spectroscopy of these states will challenge new advances in lattice gauge theoretic calculations of baryon structure. Double charm baryons still are seen only by SELEX, which showed a new [Formula: see text] candidate. High-sensitivity searches by BELLE and BaBar show only featureless background.
48
RICHARD, JEAN-MARC. "BARYON SPECTROSCOPY AND HEAVY QUARKS". International Journal of Modern Physics: Conference Series 02 (gennaio 2011): 168–72. http://dx.doi.org/10.1142/s2010194511000754.
Testo completoAbstract (sommario):
Two topics are briefly reviewed in this talk: the decay of flavored hadrons or quarkonium states involving a baryon–antibaryon pair, and the spectroscopy of heavy baryons containing one, two or three heavy quarks. Some prospects for exotic heavy baryons are also discussed.
49
Paranjape, Aseem, e Ravi K. Sheth. "The radial acceleration relation in a ΛCDM universe". Monthly Notices of the Royal Astronomical Society 507, n. 1 (24 luglio 2021): 632–50. http://dx.doi.org/10.1093/mnras/stab2141.
Testo completoAbstract (sommario):
ABSTRACT We study the radial acceleration relation (RAR) between the total (atot) and baryonic (abary) centripetal acceleration profiles of central galaxies in the cold dark matter (CDM) paradigm. We analytically show that the RAR is intimately connected with the physics of the quasi-adiabatic relaxation of dark matter in the presence of baryons in deep potential wells. This cleanly demonstrates how the mean RAR and its scatter emerge in the low-acceleration regime ($10^{-12}{\rm \, m\, s}^{-2}\lesssim a_{\rm bary}\lesssim 10^{-10}{\rm \, m\, s}^{-2}$) from an interplay between baryonic feedback processes and the distribution of CDM in dark haloes. Our framework allows us to go further and study both higher and lower accelerations in detail, using analytical approximations and a realistic mock catalogue of ${\sim}342\, 000$ low-redshift central galaxies with Mr ≤ −19. We show that, while the RAR in the baryon-dominated high-acceleration regime ($a_{\rm bary}\gtrsim 10^{-10}{\rm \, m\, s}^{-2}$) is very sensitive to details of the relaxation physics, a simple ‘baryonification’ prescription matching the relaxation results of hydrodynamical CDM simulations is remarkably successful in reproducing the observed RAR without any tuning. And in the (currently unobserved) ultra-low-acceleration regime ($a_{\rm bary}\lesssim 10^{-12}{\rm \, m\, s}^{-2}$), the RAR is sensitive to the abundance of diffuse gas in the halo outskirts, with our default model predicting a distinctive break from a simple power-law-like relation for H i-deficient, diffuse gas-rich centrals. Our mocks also show that the RAR provides more robust, testable predictions of the ΛCDM paradigm at galactic scales, with implications for alternative gravity theories than the baryonic Tully–Fisher relation.
50
Castro, Tiago, Stefano Borgani, Klaus Dolag, Valerio Marra, Miguel Quartin, Alexandro Saro e Emiliano Sefusatti. "On the impact of baryons on the halo mass function, bias, and cluster cosmology". Monthly Notices of the Royal Astronomical Society 500, n. 2 (10 novembre 2020): 2316–35. http://dx.doi.org/10.1093/mnras/staa3473.
Testo completoAbstract (sommario):
ABSTRACT Luminous matter produces very energetic events, such as active galactic nuclei and supernova explosions, that significantly affect the internal regions of galaxy clusters. Although the current uncertainty in the effect of baryonic physics on cluster statistics is subdominant as compared to other systematics, the picture is likely to change soon as the amount of high-quality data is growing fast, urging the community to keep theoretical systematic uncertainties below the ever-growing statistical precision. In this paper, we study the effect of baryons on galaxy clusters, and their impact on the cosmological applications of clusters, using the magneticum suite of cosmological hydrodynamical simulations. We show that the impact of baryons on the halo mass function can be recast in terms on a variation of the mass of the haloes simulated with pure N-body, when baryonic effects are included. The halo mass function and halo bias are only indirectly affected. Finally, we demonstrate that neglecting baryonic effects on haloes mass function and bias would significantly alter the inference of cosmological parameters from high-sensitivity next-generations surveys of galaxy clusters.