PhD Student · Senior Researcher

Roy Betser

I am a researcher working at the intersection of machine learning theory, representation learning, and trustworthy AI. I received my BSc. and MSc. from the ECE faculty at the Technion, where I continue my PhD studies. As a PhD candidate in the Technion, under the supervision of Prof. Guy Gilboa, I study the geometric and probabilistic structure of learned representations. My work spans theory, conceptual frameworks, and practical methods, aiming to uncover underlying structure in foundation vision representations and leverage it for a range of applications. In parallel, as a Senior Researcher at Fujitsu Research of Europe, I work on AI security, safety, and trust. This work focuses on detection and evaluation methods to ensure safety, reliability, and control in the rapidly evolving landscape of LLM-based agentic systems.

Roy Betser

Selected Publications

For a full list, see scholar profile (link above).

The Universal Normal Embedding

Chen Tasker*, Roy Betser*, Eyal Gofer*, Meir Yossef Levi, Guy Gilboa · CVPR 2026

A conceptual framework proposing a shared Gaussian latent space underlying both vision encoders and generative models.

Training-free Detection of Generated Videos via Spatial-Temporal Likelihoods

Omer Ben Hayun, Roy Betser, Meir Yossef Levi, Levi Kassel, Guy Gilboa · CVPR 2026

Detecting generated videos via combined spatial and temporal likelihood estimation in pretrained vision representations.

InfoNCE Induces Gaussian Distribution

Roy Betser*, Eyal Gofer*, Meir Yossef Levi, Guy Gilboa · ICLR 2026 (oral, top 1.18%)

A theoretical analysis showing how Gaussian structure emerges in learned representations under contrastive objectives.

Training-Free Policy Violation Detection via Activation-Space Whitening in LLMs

Oren Rachmil, Roy Betser, Itay Gershon, Omer Hofman, Nitay Yakoby, Yuval Meron, Idan Yankelev, Asaf Shabtai, Yuval Elovici, Roman Vainshtein · DAI, AAAI workshop 2026

LLM policy violation detection through activation-space whitening of hidden representations.

General and Domain-Specific Zero-shot Detection of Generated Images via Conditional Likelihood

Roy Betser, Omer Hofman, Roman Vainshtein, Guy Gilboa · WACV 2026

A domain-adaptive approach for detecting generated images via conditional likelihood estimation in CLIP embedding space.

CAIR : Counterfactual-based Agent Influence Ranker for Agentic AI Workflows

Amit Giloni, Chiara Picardi, Roy Betser, Shamik Bose, Aishvariya Priya Rathina Sabapathy, Roman Vainshtein · EMNLP 2025

LLM policy violation detection through activation-space whitening of hidden representations.

Whitened CLIP as a Likelihood Surrogate of Images and Captions

Roy Betser, Meir Yossef Levi, Guy Gilboa · ICML 2025

A whitening-based Gaussian modeling of CLIP embeddings that yields a closed-form likelihood surrogate for images and captions.