Résumé:

: String theory predicts that generating functions of rank 0 Donaldson-Thomas invariants, realized physically as D4-D2-D0 BPS indices in type IIA string theory on a CalabiYau threefold, are (higher depth) mock moduar forms with a specific modular completion. I'll show how the modular anomaly equations can be solved to get the generating functions up to modular ambiguities. The solution is found in terms of indefinite theta series.

Résumé:

I'll explain the modular properties of the generating functions of rank 0 Donaldson-Thomas invariants, equal to D4-D2-D0 BPS indices in Calabi-Yau compactifications of string theory, and their physical origin. These properties can be used to find generating functions up to a finite number of coefficients, the so-called polar terms, which in turn can be fixed using wall-crossing. I'll show how this program is realized for compact one-parameter Calabi-Yau threefolds and 2 units of D4-brane charge, leading to explicit mock modular forms encoding BPS indices. For higher charges, the polar terms remain so far inaccessibble, but I'll present a general solution of modular anomaly equations in terms of indefinite theta series.

Ref HAL: hal-04623148_v1
Ref Arxiv: 2310.16935
DOI: 10.1103/PhysRevLett.132.258201
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We propose a computational strategy to quantify the temperature evolution of the timescales and length scales over which dynamic facilitation affects the relaxation dynamics of glass-forming liquids at low temperatures, which requires no assumption about the nature of the dynamics. In two glass models, we find that dynamic facilitation depends strongly on temperature, leading to a subdiffusive spreading of relaxation events which we characterize using a temperature-dependent dynamic exponent. We also establish that this temperature evolution represents a major contribution to the increase of the structural relaxation time.

Ref HAL: hal-04615103_v1
Ref Arxiv: 2402.10856
DOI: 10.1103/PhysRevE.109.064133
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We explore the dynamics of a simple liquid whose particles, in addition to standard potential-based interactions, are also subjected to transverse forces preserving the Boltzmann distribution. We derive the effective dynamics of one and two tracer particles in the infinite-dimensional limit. We determine the amount of acceleration of the dynamics caused by the transverse forces, in particular in the vicinity of the glass transition. We analyze the emergence and evolution of odd transport phenomena induced by the transverse forces.

Ref HAL: hal-04609830_v1
Ref Arxiv: 2406.02531
Ref INSPIRE: 2794447
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We construct a hybrid-inflation model where the inflaton potential is generated radiatively, as gauge symmetries guarantee it to be accidentally flat at tree level. The model can be regarded as a small-field version of Natural Inflation, with inflation ending when the mass of a second scalar, the waterfall field, turns tachyonic. This provides a minimal, robust realisation of hybrid inflation, which predicts specific correlations among CMB observables. Tachyonic preheating leads to the production of gravitational waves which, for a low inflationary scale, might be detected by upcoming experiments. Simple variations of the model can give rise to topological defects, such as unstable domain walls. Their dynamics produces a stochastic gravitational-wave background, which can be compatible with the recent detection by pulsar timing arrays.

Ref HAL: hal-04604013_v1
Exporter : BibTex | endNote
Résumé:

Recent advancements in experimental fluorescence microscopy have revolutionized our ability to accurately determine the three-dimensional physical location of multiple chromosomal regions with a resolution down to 50 nm. In this study, we leverage publicly available microscopy data focusing on loci from human Chr21 obtained through multiplexed fluorescence in situ hybridization (mFISH) techniques across various cell lines and treatments. Inspired by models from polymer physics, our analysis delves into the distance distributions between different tagged regions, aiming to elucidate the chromatin's conformational arrangements. Our findings reveal the presence of at least two distinct conformational arrangements, which we term phase α and phase β, coexisting at any given genomic site. These phases exhibit contrasting scaling behaviors: phase α aligns with a crumpled globule model, while phase β suggests a confined yet more extended conformation resembling a looped domain. The identification of these distinct phases not only sheds light on the multifaceted nature of chromatin topology but also offers insights into the impact of cellular context and/or treatments on chromatin structure.

DOI: 10.1038/s41467-024-48176-6