arXiv subjects

Omer Guleryuz

Publications and source records attributed to Omer Guleryuz.

10 recordsLinked to original sources

arXiv2026

Quantum Selection of Classical Histories

Can a finite quantum episode populate a classical future that the same prepared state never reaches deterministically? We show that it can, using inflation as a cosmological laboratory. In our supergravity realization, two classical continuations already exist, but the prepared state reaches only one without noise. A stable entropy direction temporarily becomes light without a tachyonic instability, allowing mode-derived phase-space fluctuations to access the competing continuation. Finite-horizon first passage assigns it a $0.33$--$0.40$ conditional weight across three nearby CMB-normalized realizations, while suppressing the stochastic source restores its exact deterministic zero. The entropy sector then becomes heavy again, and the selected histories continue classically. A finite quantum episode can thus leave a lasting redistribution among classical futures.

hep-th↗

arXiv2026

Stochastic Survival near Swampland Boundaries

Swampland and compactification data tell us where a chosen EFT description can lose parametric control; stochastic cosmology asks which histories survive near that edge. We turn this question into a survival problem for fluctuating moduli over cosmological time scales. Given a valid stochastic generator, hard loss surfaces, soft degradation profiles, and finite horizons define a survival probability, whose logarithm is the survival action. The Doob transform then converts this logarithmic survival cost into the drift of the ensemble conditioned to remain on the controlled side. Near a regular hard boundary with nonzero normal diffusion, the inward normal component of the conditioned response is universal: it is fixed at leading order by the proper distance to the wall and the normal diffusion coefficient. The same finite-horizon construction also determines loss probabilities, first-exit statistics, survival hazards, and the control margin required to retain a prescribed fraction of histories. In this way, tower/species cutoffs, weak-coupling limits, string and Kaluza-Klein thresholds, and carefully qualified potential-based diagnostics acquire stochastic boundary layers without becoming microscopic forces. The inverse map tests when a conditioned drift is compatible with a scalar operational loss surface and reconstructs its boundary-normal Doob class. The construction therefore gives a stochastic survival interface between quantum-gravity control data and the cosmological histories that remain inside the prescribed EFT domain.

hep-th↗

arXiv2026

Universal Nonminimal Coupling-to-Starobinsky Matching and a Single-Field Attractor

We establish an off-shell commutativity theorem in 4D parity-even quadratic gravity that the Hubbard-Stratonovich/Legendre lifts, algebraic elimination of auxiliaries, including the torsionless Palatini connection, and Jordan-Einstein Weyl rescalings commute at the action level up to boundary terms. This yields a frame-independent characterization of the propagating degrees of freedom and isolates a universal scalaron EFT in the metric branch, while clarifying the algebraic nature of the Palatini $f(R)$ scalar. We obtain, as a result, a frame-universal matching from the generic nonminimal couplings to a positive $R^2$ sector and a quantitative single-field attractor bound, enhanced by a $1/ΔN$ selection term, providing sharp and falsifiable CMB targets.

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arXiv2026

String Thresholds, Dynamical Gauss--Bonnet Couplings, and Starobinsky Attractors

We develop a string-motivated dynamical Gauss--Bonnet completion of Starobinsky inflation. Since a constant Gauss--Bonnet term is topological in four dimensions, observable effects must arise from a modulus, dilaton, or compactification threshold whose value changes during inflation. We formulate the system as a scalar--Gauss--Bonnet effective theory, derive an invariant matching between the threshold-corrected plateau and the leading CMB observables $n_s$, $r$, and the running $α_s \equiv \mathrm d n_s / \mathrm d \ln k$, and impose explicit string and Kaluza--Klein cutoff bounds. Calabi--Yau topology and string threshold amplitudes are used only as microscopic priors for the threshold function; the observable deformation is fixed only after stabilization, trajectory selection, and single-clock matching. In the controlled heavy-modulus regime, a positive matched deformation raises the scalar tilt, lowers the tensor signal, and makes the running mildly less negative. A representative $X_{24}(1,1,2,8,12)$ example illustrates how topological data and an effective threshold response define a quantitative compactification target for the range $κ_G \simeq 7 \text{--} 17$, while emphasizing that this is not a direct prediction from a fully stabilized compactification.

gr-qc↗

arXiv2025

Supersymmetric Horizons at the Edge of Effective Field Theory

What if supersymmetry is not something to be hidden, but something to be reached? We introduce the Supersymmetric Horizon Stabilization (SHS): a conceptually unified and analytically controlled framework for embedding metastable de Sitter vacua and trans-Planckian inflation within effective $\mathcal{N}=1$ supergravity. Built from a logarithmic Kähler potential modified by nilpotent constraints, SHS yields a framework that connects the early universe's inflationary phase, intermediate metastable acceleration, and a final supersymmetric fixed point. We classify viable models by enforcing four essential criteria: absence of ghosts, de Sitter metastability, smooth Minkowski transitions, and asymptotic supersymmetry. The resulting scalar dynamics exhibit exponential field-space profiles, $τ(φ) \sim e^{-Δφ}$, allowing trans-Planckian excursions with bounded moduli. This structure leads to finite geodesic distance and a stabilized gravitino mass, conditionally avoiding towers of light states and remaining consistent with the Gravitino and Swampland Distance Conjectures. At the same time, the divergent Euclidean cost of reaching the supersymmetric endpoint realizes the AdS and Generalized Swampland Distance Conjectures, situating the infrared boundary at infinite dynamical distance. From this behavior emerges the Supersymmetric Horizon Conjecture: that consistent gravitational EFTs may begin and end with supersymmetry -- both at the origin and the asymptotic edge of cosmic evolution -- not as a fine-tuned remnant, but as a geometric boundary condition. SHS also supports localized features that transiently enhance scalar fluctuations, enabling efficient production of primordial black holes with masses far exceeding those in conventional inflationary scenarios.

hep-th↗

arXiv2024

Non-perpetual Eternal Inflation and the Emergent de Sitter Swampland Conjecture

We introduce a novel correlation, $n_s$ - $ΔN$, connecting CMB parameters to the required total e-folds for eternal inflation. This correlation provides a robust tool for evaluating eternal (string) inflation models using CMB data and explores the impact of quantum fluctuations on non-attractor phases. By generalizing eternal inflation criteria, our parameterization simplifies rigorous testing of predictions and reveals a link between refined de Sitter conjecture parameters and the eternal nature of the cosmic landscape. This points to a general tendency towards eternal behavior in low-energy effective field theories within the landscape, opening the possibility for our cosmic stage to potentially embrace a 'multiverse' scenario.

hep-th↗

arXiv2023

(Super)Universal Attractors and the de Sitter Vacua in String Landscape

In this work, we present an effective field theory for string inflation with spontaneously broken supersymmetry without generating any supersymmetric anti-de Sitter vacua. In that regard, we analyze the nilpotent superfields that effectively capture the physics of anti-D3 branes, and obtain the underlying pattern of universal attractors with a single parameter. Accordingly, we reveal a novel uplifting method by adding the same parameter as a complex contribution parallel to the decomposition of a superfield. Following that, we obtain an almost vanishing cosmological constant in a region where the inflationary attractors unify. Finally, we show that the introduction of nilpotent superfields drastically extends the string landscape for the de Sitter (swampland) conjecture, and the (super)universal attractors are in the string landscape in that respect.

hep-th↗

arXiv2021

On the Trans-Planckian Censorship Conjecture and the Generalized Non-Minimal Coupling

We investigate the Trans-Planckian Censorship Conjecture (TCC) and the arising bounds on the inflationary cosmology caused by that conjecture. In that investigation, we analyze TCC bounds for both Jordan and Einstein frames in the presence of a generic non-minimal coupling (to gravity) term. That term allows us to use the functional freedom it brings to the inflationary Lagrangian as an effective Planck mass. In this sense, we argue one should consider the initial field value of the effective Planck mass for the TCC. We show that as a result, one can remove the TCC upper bounds without the need to produce a new process or go beyond the standard inflation mechanism, with the generalized non-minimal coupling, and for Higgs-like symmetry-breaking potentials.

hep-th↗

arXiv2021

A Solution to the de Sitter Swampland Conjecture versus Inflation Tension via Supergravity

The methods of supergravity allow us to derive a multi-field F-term potential. Using this, we denote a generic and non-positive single-field F-term potential. We insert our theory into the scalar-gravity part of the $SU(2,1|1)$ invariant superconformal action. That action leads us to a de Sitter solution at the inflationary trajectory. One can denote stabilization of fields in terms of the Kähler kinetic terms and single-field slow-roll inflation parameters. We combine these with the de Sitter swampland conjecture to generate a bounded conjecture. This approach allowed us to show that the single field slow-roll inflation works in harmony with bounded de Sitter conjecture for any concave inflation potential.

hep-th↗

arXiv2020

Off-Shell ${\mathcal N}=(1,0)$ Linear Multiplets in Six Dimensions

We provide a tensor calculus for $n$-number of ${\mathcal N}=(1,0)$ linear multiplets in six dimensions. The coupling of linear multiplets is encoded in a function ${\mathcal F}_{IJ}$ that is subject to certain constraints. We provide various rigid and local supersymmetric models depending on the choice of the function ${\mathcal F}_{IJ}$ and provide an interesting off-diagonal superinvariant, which leads to an $R^2$ supergravity upon elimination of auxiliary fields.

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