String Phenomenology 2025

Session

Parallel Session 3

8 Jul 2025, 13:30

ISEC (Northeastern University)

335. Flavor Symmetries and Winding Modes

Alexander Stewart

08/07/2025, 13:30

Modular flavor symmetries have been proposed as a new way to address the flavor problem. It is known that they can emerge from string compactifications. We discuss this connection in detail, and show how the congruence subgroups of SL(2,Z), which underlie many modular flavor symmetries, emerge from stringy duality symmetries by orbifolding. This requires an analysis of massive states, which...

336. Cosmological trackers from perturbations

Martin Mosny

08/07/2025, 13:48

Compared to standard cosmology, string cosmologies motivate an extended period of kination that can be followed by a cosmological tracker and then an epoch of moduli domination. Conventionally, such trackers occur when there is a scalar field with an exponential potential and an additional fluid whose energy balances the kinetic and potential energy of the scalar field. In this talk we show...

337. F-theory Axiverse

Yunhao Zhu

08/07/2025, 14:06

TBD

338. Axion masses, decay constants, and photon couplings in F-theory ensembles

Sebastian Vander Ploeg Fallon

08/07/2025, 14:24

We compactify F-theory on Weierstrass models over various toric threefold bases, and compute the masses, decay constants, and photon couplings of the associated axions.

339. Unstable Domain Walls and Transitions in the Flux Landscape

Thibaut Coudarchet

08/07/2025, 14:42

Domain walls which arise from the presence of a brane coupled to a modulus field is the setting relevant for studying flux-changing D5/NS5-branes in the type IIB flux Landscape which couple to the volume modulus. In this talk I will revisit known results on the subject and explain that if the modulus is only weakly stabilized, as is the case for scenarios à la KKLT or LVS, no Euclidean...

340. Alignment and Co-Scaling of Electric and Magnetic Towers

Matthew Reece

08/07/2025, 15:30

In regions of the landscape with a tower of light electrically charged particles or branes -- those with charge-to-mass (or tension) ratio parametrically larger than 1 in Planck units -- one also finds a tower of light magnetically charged particles or branes with the same charge-to-mass ratio. We call this phenomenon "electric-magnetic co-scaling." These towers are, furthermore, aligned;...

341. Learning New Constructions of Toric Calabi-Yau Manifolds with Transformers

Jacky Hoi Tung Yip

08/07/2025, 15:48

Fine, regular, and star triangulations (FRSTs) of 4-dimensional reflexive polytopes generate toric varieties, within which Calabi-Yau threefolds can be embedded as hypersurfaces. We use transformers---deep learning models originally developed for language modeling---to generate FRSTs of polytopes of varying sizes. Our method shows promising scalability with polytope size and can be...

342. Cosmic superstrings in large volume compactifications: PTAs, LISA and time-varying tension

Filippo Revello

08/07/2025, 16:06

The Stochastic Gravitational Wave Background (SGWB) from cosmic super- strings offers one of the few known possibilities to test String Theory within current experimental reach. However, in order to be compatible with the existing constraints, the tension of a cosmic superstring network is required to lie several orders of magnitude below the Planck scale. This is naturally realized in string...

343. Astrophysical aspects of string compactifications

Mario Ramos Hamud

08/07/2025, 16:24

A generic aspect of effective field theories coming from string compactifications is the appearance of moduli fields. Among these moduli, the axion and dilaton are present at low energies as (pseudo-)Goldstone bosons from the spontaneous breaking of an exact (or approximate) global symmetry. These moduli have a different microscopic coupling to matter but appear kinetically coupled in such a...

344. A Dynamical Axion Decay Constant with Modulus Kination

Chandrika Chandrashekar

08/07/2025, 16:42

We consider a QCD axion coming from the compactification of extra dimensional gauge fields. In this scenario, the QCD axion is around during inflation and seeds isocurvature. In the standard cosmic picture where reheating immediately follows inflation, CMB isocurvature bounds imply a low inflationary energy scale if the QCD axion were to comprise all of the dark matter. This poses an obstacle,...

365. The Ins and Outs of Casimir energies on Riemann-flat manifolds

Bruno Valeixo Bento

10/07/2025, 13:30

We have used Casimir energies and Riemann-flat manifolds (RFM) to construct an explicit dS5 maximum in M-theory. In this talk I will outline how we did it--in particular, I will present the fully explicit formula we obtain for the Casimir stress-energy in a general RFM, including its higher-dimensional profile; explain how the Casimir energy localizes in particular loci of the RFM, which we...

366. Dark Bubble Cosmology in the 0‘B string

Joaquin Masias

10/07/2025, 13:48

We build a novel realization of dark bubble cosmology in non-supersymmetric string theory. Among the simplest models in ten dimensions, the type 0'B orientifold is the unique option which yields a scale-separated construction. The resulting setting produces a logarithmically varying dynamical dark energy, reflecting its holographic counterpart in terms of running gauge couplings. We analyze in...

367. Experimental particle physics priorities 2025: A String Phenomenology Perspective

Alon Faraggi

10/07/2025, 14:06

With the SNOWMASS 2021 process in the US and the on--going European Strategy Report 2025, the field of elementary particle physics is undergoing detailed community evaluation, and the experimental particle physics program, which requires substantial public investment, is under scrutiny. We offer an assessment of the current experimental particle physics priorities from a string phenomenology...

368. Fuzzy Axions and Associated Relics

Federico Carta

10/07/2025, 14:24

We study fuzzy axion dark matter in type IIB string theory, for axions descending from the Ramond-Ramond four-form in compactifications on orientifolds of Calabi-Yau hypersurfaces. Such models can be tested by cosmological measurements if a significant relic abundance of fuzzy dark matter arises, which we argue is most common in models with small numbers of axions. We construct a topologically...

369. Analysis of inflationary models in higher-dimensional uniform inflation

Takuya Hirose

10/07/2025, 14:42

We consider higher-dimensional uniform inflation, in which the extra dimensions expand at the same rate as three-dimensional non-compact space during inflation. We compute the cosmological perturbation in $D+4$ dimensions and derive the spectral index $n_s$ and the tensor-scalar ratio $r$. We analyze five inflationary models: chaotic inflation, natural inflation, quartic hilltop inflation,...

370. Universality in the String Axiverse

Junyi Cheng

10/07/2025, 15:30

Studies of axion effective theories in the type IIB Calabi-Yau landscape have revealed that hierarchies in geometric volumes drive correlations between axion physics and the number of axions in a given model. We provide evidence that distributions of appropriately normalized divisor volumes in the toric hypersurface Calabi-Yau threefolds are universal across this landscape. Furthermore, we...

371. Intersecting D-branes

Zheng Miao

10/07/2025, 15:48

For decades intersecting D-branes and O-planes have been playing a very important role in string phenomenology in the context of particle physics model building and in the context of flux compactifications. The corresponding supergravity equations are hard to solve so generically solutions only exist in a so-called smeared limit where the delta function sources are replaced by constants. We...

372. Warped G2-throats in IIA and uplift dSillusions

George Tringas

10/07/2025, 16:06

Flux compactifications of IIA supergravity on orientifolded G2-manifolds have been argued to allow for classical 3d Minkowski vacua with moduli and scale-separated 3d AdS vacua with full moduli stabilisation. To further uplift these vacua to meta-stable 3d dS vacua using anti-D2 branes, warped throats are desirable. We study the flux-stabilisation of local “CGLP-type” throats in compact G2...

373. Super-hidden Photons and how to find them in the Landscape

Jonathan Steiner

10/07/2025, 16:24

A generic feature of string theory compactifications are hidden sectors. In particular, in the Type IIB/F-Theory corner of the landscape, a prominent example is an isolated D3-brane hosting a U(1) gauge field that is spatially separated from a locally realized standard model (SM). In this talk, I argue how 'super-hidden' photons living on such branes generically interact with the SM via...

374. Chasing the Standard Model within heterotic line bundle constructions

Luca Armando Nutricati

10/07/2025, 16:42

In this talk, we explore the phenomenological potential of heterotic line bundle models as a promising framework for deriving the Standard Model from string theory. We present a systematic approach to constrain the low-energy effective theories derived from such compactifications using remnants of anomalous U(1) symmetries to retrieve realistic quarks and leptons masses, mixing patterns and...