scholarly journals The Fragmented Glueball: A Personal View

2022 ◽  
Vol 258 ◽  
pp. 08005
Author(s):  
Eberhard Klempt
Keyword(s):  
Mass Range ◽  
Personal View ◽  
Scalar Mesons ◽  
Clear Peak ◽  
Low Mass ◽  
Singlet Component ◽  
Limited Mass ◽  
Channel Analysis ◽  
Coupled Channel ◽  
Scalar Resonances

A coupled-channel analysis has been performed to identify the spectrum of scalar mesons. The data include BESIII data on radiative J/ψ decays into π0π0, KS KS, ηη, and ωϕ, 15 Dalitz plots from ¯N annihilation at rest at LEAR, the CERN-Munich multipoles for ππ elastic scattering, the S-wave from BNL data on ππ scattering into KS KS, from GAMS data on ππ π0π0; ηη, and ηη', and NA48/2 data on low-mass ππ interactions from K± → ππe±v decays. The analysis reveals the existence of ten scalar isoscalar resonances. The resonances can be grouped into two classes: resonances with a large SU(3) singlet component and those with a large octet component. The production of isoscalar resonances with a large octet component should be suppressed in radiative J/ψ decays. However, in a limited mass range centered at 1900MeV, these mesons are produced abundantly. Mainly-singlet scalar resonances are produced over the full mass range but with larger intensity at 1900MeV. The total scalar isoscalar yield in radiative decays into scalar mesons shows a clear peak which is interpreted as the scalar glueball of lowest mass.

scholarly journals X(6200) as a compact tetraquark in the QCD string model

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
A. V. Nefediev
Keyword(s):  
String Model ◽  
Mass Range ◽  
Bound State ◽  
Lhcb Collaboration ◽  
Plausible Assumption ◽  
Compact Component ◽  
Molecular Interpretation ◽  
Channel Analysis ◽  
Coupled Channel ◽  
Qcd String

AbstractRecently the LHCb Collaboration announced the first observation of nontrivial structures in the double-$$J/\psi $$ J / ψ mass spectrum in the mass range 6.2–7.2 GeV, and a theoretical coupled-channel analysis of these data performed in Dong et al. (Phys Rev Lett 126:132001, 2021) evidenced the existence of a new state X(6200) close to the double-$$J/\psi $$ J / ψ threshold. Although its molecular interpretation seems the most plausible assumption, the present data do not exclude an admixture of a compact component in its wave function, for which a fully-charmed compact tetraquark is the most natural candidate. It is argued in this work that the QCD string model is compatible with the existence of a compact $$cc{\bar{c}}{\bar{c}}$$ c c c ¯ c ¯ state bound by QCD forces just below the double-$$J/\psi $$ J / ψ threshold. A nontrivial interplay of the quark dynamics associated with this compact state and the molecular dynamics provided by soft gluon exchanges between $$J/\psi $$ J / ψ mesons is discussed and the physical X(6200) is argued to be a shallow bound state, in agreement with the results of the aforementioned coupled-channel analysis of the LHCb data.

scholarly journals The emergence of the galactic stellar mass function from a non-universal IMF in clusters

2018 ◽  
Vol 614 ◽  
pp. A43 ◽  
Author(s):  
Sami Dib ◽  
Shantanu Basu
Keyword(s):  
Mass Range ◽  
Mass Function ◽  
Stellar Mass ◽  
Stellar Clusters ◽  
Galactic Clusters ◽  
Power Law Function ◽  
Low Mass ◽  
Mass Functions ◽  
Characteristic Mass ◽  
The Imf

We investigate the dependence of a single-generation galactic mass function (SGMF) on variations in the initial stellar mass functions (IMF) of stellar clusters. We show that cluster-to-cluster variations of the IMF lead to a multi-component SGMF where each component in a given mass range can be described by a distinct power-law function. We also show that a dispersion of ≈0.3 M⊙ in the characteristic mass of the IMF, as observed for young Galactic clusters, leads to a low-mass slope of the SGMF that matches the observed Galactic stellar mass function even when the IMFs in the low-mass end of individual clusters are much steeper.

scholarly journals Stellar models and isochrones from low-mass to massive stars including pre-main sequence phase with accretion

2019 ◽  
Vol 624 ◽  
pp. A137 ◽  
Author(s):  
L. Haemmerlé ◽  
P. Eggenberger ◽  
S. Ekström ◽  
C. Georgy ◽  
G. Meynet ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Evolution ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Range ◽  
Stellar Clusters ◽  
Solar Metallicity ◽  
Low Mass ◽  
Stellar Models ◽  
Young Clusters

Grids of stellar models are useful tools to derive the properties of stellar clusters, in particular young clusters hosting massive stars, and to provide information on the star formation process in various mass ranges. Because of their short evolutionary timescale, massive stars end their life while their low-mass siblings are still on the pre-main sequence (pre-MS) phase. Thus the study of young clusters requires consistent consideration of all the phases of stellar evolution. But despite the large number of grids that are available in the literature, a grid accounting for the evolution from the pre-MS accretion phase to the post-MS phase in the whole stellar mass range is still lacking. We build a grid of stellar models at solar metallicity with masses from 0.8 M⊙ to 120 M⊙, including pre-MS phase with accretion. We use the GENEC code to run stellar models on this mass range. The accretion law is chosen to match the observations of pre-MS objects on the Hertzsprung-Russell diagram. We describe the evolutionary tracks and isochrones of our models. The grid is connected to previous MS and post-MS grids computed with the same numerical method and physical assumptions, which provides the widest grid in mass and age to date.

The demographics of central massive black holes in low-mass early-type galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 286-288
Author(s):  
Dieu D. Nguyen
Keyword(s):  
Black Holes ◽  
Adaptive Optics ◽  
Mass Range ◽  
Early Type ◽  
Host Galaxies ◽  
Seed Formation ◽  
Unique Constraint ◽  
Low Mass ◽  
Important Extension ◽  
Stellar Masses

AbstractThe existence intermediate mass black holes (IMBH, MBH ≲ 106M⊙) at the centers low-mass galaxies with stellar masses between (1–10)×10M⊙ are key to constraining the origin of black hole (BH) seeds and understanding the physics deriving the co-evolution of central BHs and their host galaxies. However, finding and weighing IMBH is challenging. Here, we present the first observational evidence for such IMBHs at the centers of the five nearest early-type galaxies (D < 3.5 Mpc, ETGs) revealed by adaptive optics kinematics from Gemini and VLT and high-resolution HST spectroscopy. We find that all five galaxies appear to host IMBHs with four of the five having masses below 1 million M⊙ and the lowest mass BH being only ∼7,000 M⊙. This work provides a first glimpse of the demographics of IMBHs in this galaxy mass range and at velocity dispersions < 70 km/s, and thus provides an important extension to the bulge mass and galaxy dispersion scaling relations. The ubiquity of central BHs in these galaxies provides a unique constraint on BH seed formation scenarios, favoring a formation mechanism that produces an abundance of low-mass seed BHs.

scholarly journals The Λ(1405) with one pole

2020 ◽  
Vol 241 ◽  
pp. 03002
Author(s):  
Eberhard Klempt
Keyword(s):  
Partial Wave ◽  
Good Description ◽  
Mass Range ◽  
Partial Wave Analysis ◽  
Wave Analysis ◽  
Channel System ◽  
Analysis Group ◽  
Coupled Channel

The Λ(1405)1/2- resonance is discussed and a fit of the Bonn-Gatchina (BnGa) partial-wave- analysis group is presented to data relevant for this resonance. In the Σπ - NK coupled channel system, no Σ pole and only one Λ pole in the mass range from the Σπ threshold to 1500 MeV is required to get a good description of the data.

scholarly journals Positive parity scalar mesons in the 1–2 GeV mass range

2007 ◽  
Vol 50 (3) ◽  
pp. 609-616 ◽  
Author(s):  
L. Maiani ◽  
F. Piccinini ◽  
A.D. Polosa ◽  
V. Riquer
Keyword(s):  
Mass Range ◽  
Positive Parity ◽  
Scalar Mesons
Sign in / Sign up

Export Citation Format

Share Document