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(30) Production(s) de l'année 2024
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Chromatin structure from high resolution microscopy: scaling laws and microphase separation 
Auteur(s): Remini L., Segers Midas, Palmeri J., Walter J.-C., Parmeggiani A., Carlon Enrico
(Article) Publié:
Physical Review E, vol. 109 p.024408 (2024)
Ref HAL: hal-04177307_v3
DOI: 10.1103/PhysRevE.109.024408
Exporter : BibTex | endNote
Résumé: Recent advances in experimental fluorescence microscopy allow high accuracy determination (resolution of 50nm) of the 3D physical location of multiple (up to ~10^2) tagged regions of the chromosome. We investigate publicly available microscopy data for two loci of the human Chr.21 obtained from multiplexed FISH methods for different cell lines and treatments. Inspired by polymer physics models, our analysis centers around distance distributions between different tags, aiming to unravel the chromatin conformational arrangements. We show that for any specific genomic site, there are (at least) two different conformational arrangements of chromatin, implying coexisting distinct topologies which we refer to as phase "alpha" and phase "beta". These two phases show different scaling behaviors: the former is consistent with a crumpled globule while the latter indicates a confined, but more extended conformation, as a looped domain. The identification of these distinct phases sheds light on the coexistence of multiple chromatin topologies and provides insights into the effects of cellular context and/or treatments on chromatin structure.
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Accidentally light scalars from large representations
Auteur(s): Brümmer Felix, Ferrante Giacomo, Frigerio M., Hambye Thomas
(Article) Publié:
Journal Of High Energy Physics, vol. 24 p.075 (2024)
Texte intégral en Openaccess : 
Ref HAL: hal-04171353_v1
Ref Arxiv: 2307.10092
Ref INSPIRE: 2678514
DOI: 10.1007/JHEP01(2024)075
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: In models with spontaneous symmetry breaking by scalar fields in large group representations, we observe that some of the scalar masses can be loop-suppressed with respect to the naive expectation from symmetry selection rules. We present minimal models -- the $\rm{SU(2)}$ five-plet and $\rm{SU(3)}$ ten-plet -- with such accidentally light scalars, featuring compact tree-level flat directions lifted by radiative corrections. We sketch some potential applications, from stable relics and slow roll in cosmology, to hierarchy and fine-tuning problems in particle physics.
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