Another interesting gravitational explanation of dark matter and dark energy phenomena.
We argue that the effect of cold dark matter in the cosmological setup can be explained by the coupling between the baryonic matter particles in terms of the long-range force having a graviton mass mg via the Yukawa gravitational potential. Such a quantum-corrected Yukawa-like gravitational potential is characterized by the coupling parameter α, the wavelength parameter λ, which is related to the graviton mass via m(g)=ℏ/(λc), that determines the range of the force and, finally, a Planck length quantity l(0) that makes the potential regular at the centre. The corrected Friedmann equations are obtained using Verlinde's entropic force interpretation of gravity based on the holographic scenario and the equipartition law of energy. The parameter α modifies Newton's constant as G(eff)→G(1+α). We argue that dark matter is an apparent effect as no dark matter particle exists in this picture. Furthermore, the dark energy is also related to graviton mass and α; in particular, we point out that the cosmological constant can be viewed as a self-interaction effect between gravitons. We further show that there exists a precise correspondence with Verlinde's emergent gravity theory, and due to the long-range force, the theory can be viewed as a non-local gravity theory. To this end, we performed the phase space analyses and estimated λ≃103[Mpc] and α∈(0.0385,0.0450), respectively. Finally, from these values, for the graviton mass, we get mg≃10^−68 kg, and cosmological constant Λ≃10^−52m^−2. Further, we argue how this theory reproduces the MOND phenomenology on galactic scales via the acceleration of Milgrom a(0)≃10^−10m/s^2.
Kimet Jusufi, Genly Leon, Alfredo D. Millano, "Dark Universe Phenomenology from Yukawa Potential?" arXiv:2304.11492 (May 14, 2024) (Phys. Dark Univ. 42 (2023), 101318).
very slow progress
ReplyDeletearXiv:2405.07203 (hep-ex)
[Submitted on 12 May 2024]
Characterization of the PADME positron beam for the X17 measurement
S. Bertelli, F. Bossi, B. Buonomo, R. De Sangro, C. Di Giulio, E. Di Meco, K. Dimitrova, D. Domenici, F. Ferrarotto, G. Finocchiaro, L.G. Foggetta, A. Frankenthal, M. Garattini, G. Georgiev, P. Gianotti, S. Ivanov, Sv. Ivanov, V. Kozhuharov, E. Leonardi, E. Long, M. Mancini, G.C. Organtini, M. Raggi, I. Sarra, R. Simeonov, T. Spadaro, E. Spiriti, P. Valente, A. Variola, E. Vilucchi
This paper presents a detailed characterization of the positron beam delivered by the Beam Test Facility at Laboratori Nazionali of Frascati to the PADME experiment during Run III, which took place from October to December 2022. It showcases the methodology used to measure the main beam parameters such as the position in space, the absolute momentum scale, the beam energy spread, and its intensity through a combination of data analysis and Monte Carlo simulations. The results achieved include an absolute precision in the momentum of the beam to within ∼ 1-2 MeV/c, a relative beam energy spread below 0.25\%, and an absolute precision in the intensity of the beam at the level of 2\% percent.
Subjects: High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)
Cite as: arXiv:2405.07203 [hep-ex]
In search of new particles with PADME
PADME
Collaboration
•
Radoslav Simeonov(
Sofia U. (main)
)
for the collaboration.
Mar 26, 2024
6 pages
Published in:
PoS COSMICWISPers (2024) 043
Contribution to:
COSMICWISPers
, 043
Published: Mar 26, 2024
DOI:
10.22323/1.454.0043
Experiments:
Abstract: (SISSA)
Several contemporary particle physics experiments at accelerators aim to contribute in the quest todescribe the properties of the Dark matter by looking for new particles. One of them is the PositronAnnihilation into Dark Matter Experiment (PADME), at the Laboratori Nazionali di Frascati ofINFN. Its main goal is to search for a Dark Photon (A’) by studying the annihilation of beampositrons on a fixed target. Since 2018, two data taking periods were completed successfully,collecting O(10131013) positrons on target. In 2022 the detector setup was then modified to explore theexistence of the so-called "X17" particle, postulated to explain an anomalous effect observed bythe ATOMKI collaboration. In this paper the PADME experiment is presented, the main resultsand the possible future prospects are discussed.
PADME
arXiv:2405.10019 (astro-ph)
ReplyDelete[Submitted on 16 May 2024]
Anomalous radial acceleration of galaxies and clusters supports hyperconical modified gravity
Robert Monjo, Indranil Banik
General relativity (GR) is the most successful theory of gravity, with great observational support at local scales. However, to keep GR valid at over cosmic scales, some phenomena (such as the flat galaxy rotation curves and the cosmic acceleration) require the assumption of exotic dark matter. The radial acceleration relation (RAR) indicates a tight correlation between dynamical mass and baryonic mass in galaxies and galaxy clusters. This suggests that the observations could be better explained by modified gravity theories without exotic matter. Modified Newtonian Dynamics (MOND) is an alternative theory for explaining some cases of flat galaxy rotation curves by using a new fundamental constant acceleration a0, the so-called Milgromian parameter. However, this non-relativistic model is too rigid (with insufficient parameters) to fit the large diversity of observational phenomena. In contrast, a relativistic MOND-like gravity naturally emerges from the hyperconical model, which derives a fictitious acceleration compatible with observations. This study analyses the compatibility of the hyperconical model with respect to RAR observations of 10 galaxy clusters obtained from HIFLUGCS and 60 high-quality SPARC galaxy rotation curves. The results show that a general relation can be fitted to most cases with only one or two parameters, with an acceptable chi-square and p-value. These findings suggest a possible way to complete the proposed modification of GR on a cosmic scale.
Comments: 18 pages, 5 figures, 1 table. Submitted to ApJL in this form
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2405.10019 [astro-ph.CO]
arXiv:2405.08557 (astro-ph)
ReplyDelete[Submitted on 14 May 2024 (v1), last revised 15 May 2024 (this version, v2)]
Galaxy clusters in Milgromian dynamics: Missing matter, hydrostatic bias, and the external field effect
Ruth Kelleher, Federico Lelli
We study the mass distribution of galaxy clusters in Milgromian dynamics, or modified Newtonian dynamics (MOND). We focus on five galaxy clusters from the X-COP sample, for which high-quality data are available on both the baryonic mass distribution (gas and stars) and internal dynamics (from the hydrostatic equilibrium of hot gas and the Sunyaev-Zeldovich effect). We confirm that galaxy clusters require additional `missing matter' in MOND, although the required amount is drastically reduced with respect to the non-baryonic dark matter in the context of Newtonian dynamics. We studied the spatial distribution of the missing matter by fitting the acceleration profiles of the clusters with a Bayesian method, finding that a physical density profile with an inner core and an outer r−4 decline (giving a finite total mass) provide good fits within ∼1 Mpc. At larger radii, the fit results are less satisfactory but the combination of the MOND external field effect and hydrostatic bias (quantified as 10%-40%) can play a key role. The missing mass must be more centrally concentrated than the intracluster medium (ICM). For relaxed clusters (A1795, A2029, A2142), the ratio of missing-to-visible mass is around 1−5 at R≃200−300 kpc and decreases to 0.4−1.1 at R≃2−3 Mpc, showing that the total amount of missing mass is smaller than or comparable to the ICM mass. For clusters with known merger signatures (A644 and A2319), this global ratio increases up to ∼5 but may indicate out-of-equilibrium dynamics rather than actual missing mass. We discuss various possibilities regarding the nature of the extra mass, in particular `missing baryons' in the form of pressure-confined cold gas clouds with masses of <105 M⊙ and sizes of <50 pc.
Comments: Accepted for publication in A&A
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cite as: arXiv:2405.08557 [astro-ph.CO]
2 things
We confirm that galaxy clusters require additional `missing matter' in MOND, although the required amount is drastically reduced with respect to the non-baryonic dark matter in the context of Newtonian dynamics.
the missing mass must be more centrally concentrated than the intracluster medium (ICM).
so MOND + DM, with DM centrally concentrated than the intracluster medium
DM could be PBH centrally concentrated than the intracluster medium
@neo
ReplyDeleteI've seen all three papers. Your characterization of the PADME paper is apt.
Monjo and Banik is intriguing and probably deserves a closer look.
The Kelleher and Lelli paper, is suggestive of the possibility that the missing matter could be baryonic.
PADME is taking a very long time with X17 as the data was done in 2022
ReplyDeletethere's also
The X17 search with the MEG-II apparatus at PSI
Search for the X17 particle with the MEG-II apparatus
data was also taken in 2022
Kelleher and Lelli paper, also implies that bounds on dark matter + Newton gravity would not apply in MOND, since much less mass is needed, enough to escape those bounds, including PBH
the bullet cluster issue is that strong gravitational lensing seems to imply there is invisible mass causing the lensing