arXiv subjects

Michaël Sarrazin

Publications and source records attributed to Michaël Sarrazin.

5 recordsLinked to original sources

arXiv2026

Matter Swapping between Two Branes: A Local Type IIB D3-D7-D3 Realization of Charged-Fermion Mixing via E3 Instantons

Effective infrared two-sheeted descriptions of fermion mixing between braneworlds have emerged in several distinct realizations and lead to testable matter-swapping effects, motivating low-energy searches and cosmological applications. The recurrence of the same low-energy fermion operator motivates asking whether this structure can also arise from a D-brane mechanism. We construct a local Type IIB D3$_+$-D7-D3$_-$/E3 realization in which direct interbrane mixing is perturbatively forbidden but generated non-perturbatively by a suitable E3 instanton sector. The resulting low-energy interaction reproduces the characteristic pseudoscalar structure of the two-sheeted fermion operator, together with its scalar companion, while D7 Wilson transport provides the required gauge-invariant relative connection. The construction therefore provides a local string realization of the same operator structure, subject to the stated instanton and zero-mode conditions. The analysis further provides a concrete model-building roadmap toward a compact phenomenological realization: the compactification must achieve electromagnetic sequestering of the two fermion sectors and support a sufficiently light non-uniform D7 gauge mode capable of mediating a long-range relative interaction. In such a complete compactification, the mixing parameter $g$ would in principle become computable from microscopic string data and directly testable against low-energy constraints.

hep-th↗

arXiv2026

Braneworld Baryogenesis and QCD-Era Magnetogenesis: A Predictive Link

We demonstrate that primordial magnetic fields (PMF) play a decisive role in the braneworld baryogenesis scenario of [Phys. Rev. D $\textbf{110}$, 023520 (2024)], where C/CP violation arises from the coupling of visible and hidden matter-antimatter sectors through a pseudo-scalar field. Although this mechanism generates baryon number efficiently only after the quark-hadron transition, by incorporating a realistic stochastic PMF within a semi-analytical framework, we find that matching the observed baryon-antibaryon asymmetry robustly requires PMF strengths of order $10^{10}$ T right after the transition, in agreement with causal QCD-era magnetogenesis. We further reveal that magnetic fluctuations drive the baryon-density spectrum to white noise on large scales, yielding an isocurvature component compatible with Cosmic Microwave Background (CMB) bounds. This establishes a predictive link between the braneworld baryogenesis model and realistic early-Universe magnetic fields.

hep-ph↗

arXiv2025

Stellar Light Scattering as a Probe for a Braneworld-Induced Baryogenesis Scenario

A recent baryogenesis scenario [Phys. Rev. D 110, 023520 (2024)], rooted in a two-brane Universe model, proposed a solution to the matter-antimatter asymmetry through the dynamics of a new pseudo-scalar field. In the present paper, one investigates the phenomenological consequences of this proposal. One shows that the associated boson could persist as a relic from the early Universe, forming a subdominant component of dark matter. While its overall cosmological density is small ($\approx 0.2\%$), one demonstrates that a one-loop process facilitates an ultra-weak coupling to photons, leading to a distinctive scattering signature. One argues that this effect could produce a faint, glowing halo around massive, hot stars, characterized by a unique spectral decay. Detecting or constraining this elusive light with current and future instruments like the JWST would provide a powerful and direct observational test of the underlying braneworld dynamics and its connection to baryogenesis.

hep-ph↗

arXiv2025

Exciton Binding Energies in 2D Materials: Insights from Braneworld Physics

In the present work, we introduce a new interpretation of exciton binding energies in two-dimensional (2D) materials using concepts from brane physics. We adapt the Dvali-Gabadadze-Porrati-Shifman mechanism to a (2+1)-dimensional brane in a (3+1)-D spacetime, deriving an effective electromagnetic potential on the brane. Using this potential, we develop a hydrogenic model for exciton binding energies in 2D materials, applying it to s-type excitons and comparing theoretical predictions with experimental results on WS$_{2}$ monolayers. This interdisciplinary approach bridges high-energy and condensed matter physics, offering a new didactic representation of excitons in low-dimensional systems.

cond-mat.mes-hall↗

arXiv2019

Search for neutron-hidden neutron interbrane transitions with MURMUR, a low-noise neutron passing-through-walls experiment

Multi-braneworld universe is at the heart of many scenarios of physics beyond the Standard Model and the cosmological model $ΛCDM$. It is thus an important concern to constrain these scenarios which also allow for experiments below the GeV scale. MURMUR is a new neutron-passing-through-walls experiment designed to constrain neutron-hidden neutron transitions in the context of braneworlds scenarios. As our visible universe could be a 3-brane embedded in a multidimensional bulk, adjacent hidden 3-branes are often expected. Their existence can be constrained as matter exchange between braneworlds must occur with a swapping probability $p$. A neutron $n$ can convert into a hidden neutron $n'$ when scattered by a nucleus with cross section $σ(n \to n')$ $\propto$ $σ_E (n \to n)\ p$, where $σ_E$ is the usual elastic cross-section. Hidden neutrons could therefore be generated in the moderator medium of a nuclear reactor, where high-flux neutrons undergo many elastic collisions. All the theoretical and technological keys of this experiment soon to be installed at the nuclear research reactor BR2 (SCK.CEN, Mol, Belgium) are introduced.

nucl-ex↗