⚛️ high-energy theory

Holograms and Standard Models

The paper argues that the current paradigm of Wilsonian quantum field theory is inadequate for resolving long-standing mysteries in particle physics and proposes replacing it with a holographic framework based on de Sitter holography, which naturally yields a rich standard model in the flat-space limit and eliminates the problem of huge quantum corrections to the cosmological constant.

Original authors: Shoichiro Miyashita, Yasuhiro Sekino, Leonard Susskind

Published 2026-07-08

📖 5 min read🧠 Deep dive

CC BY 4.0

Original authors: Shoichiro Miyashita, Yasuhiro Sekino, Leonard Susskind

Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

The Big Problem: The Universe is "Fine-Tuned"

Imagine you are trying to bake a cake (the universe) that is perfectly flat and stable. In the current way physicists think about the world (called "Standard Quantum Field Theory"), the recipe requires you to mix ingredients with such extreme precision that it feels impossible.

If you add just a tiny pinch of sugar (representing quantum energy corrections) to the batter, the cake explodes or collapses. To keep the cake flat, you have to subtract that pinch of sugar with a precision of one part in a trillion trillion. Physicists call this the "Fine-Tuning Problem." It's like balancing a pencil on its tip; it's theoretically possible, but it feels incredibly unnatural that the universe would just happen to be balanced that way.

For 50 years, scientists have tried to fix this by inventing new ingredients (like Supersymmetry), but none have worked.

The New Idea: The Hologram

The authors propose a radical new way to look at the universe. They suggest we stop thinking of the universe as a 3D cake and start thinking of it as a hologram.

Think of a credit card hologram. It looks like a 3D image, but it's actually just a flat, 2D sticker with a pattern on it. The 3D world we see is "projected" from that 2D surface.

The Paper's Claim: The entire universe, including all particles, forces, and the "Standard Model" of physics, is actually a projection from a lower-dimensional boundary (a hologram).
The Twist: Usually, holograms are used to explain gravity. This paper argues that the hologram also explains particle physics (electrons, quarks, light) and solves the fine-tuning problem without needing any new "magic" ingredients.

The "Toy" Universe: DSSYK

To prove this works, the authors built a "toy" universe. It's not our real universe, but it's complex enough to act like one.

The Ingredients: They used a mathematical model called DSSYK (a collection of many interacting particles, like a very busy party of fermions).
The Setup: Imagine this party is happening on the edge of a room (the hologram). The rules of the party are random, but when you look at the "shadow" they cast into the room (the bulk), something amazing happens.

The Magic Trick: How the Toy Solves the Problem

In the old way of thinking (Quantum Field Theory), you have to manually adjust the "knobs" (constants) of the universe to stop the vacuum energy from blowing up.

In this new holographic view, the authors show that you don't need to adjust the knobs. Here is the analogy:

Imagine you have a giant library (the hologram) with $N$ books.

The Old View: You try to calculate the total weight of the library by weighing every single page. If you miss a page or weigh it wrong, the total weight is wrong. You have to fine-tune your scale to get the right answer.
The New View: The authors say, "Wait, the total weight of the library isn't about the pages; it's about the number of books."
- If you fix the number of books ( $N$ ) to be a huge number, the "weight" (vacuum energy) automatically becomes tiny and stable.
- You don't need to tweak the pages. You just set the number of books, and the physics takes care of the rest.

The paper calls this "Set it and Forget it."

In the holographic model, the "knob" is the number of particles ( $N$ ).
Once you set $N$ to be very large, the vacuum energy naturally becomes zero (or very close to it).
There are no quantum corrections to mess it up because the "entropy" (the amount of information) is fixed by the number of books, not by the messy details of the pages.

What Emerges from the Toy?

When the authors let their "toy" hologram project into a flat space (simulating our universe), a standard model of physics pops out naturally:

Gauge Forces: It creates forces like electricity and the strong nuclear force (QCD).
Particles: It creates quarks, mesons, and even things that look like photons (light) and gravitons (gravity), though in this specific 2D toy model, they act a bit differently than in our 3D world.
No Supersymmetry Needed: The most exciting part is that they solved the fine-tuning problem without using Supersymmetry (a popular but unproven theory). The hologram does the job on its own.

The Conclusion

The paper argues that the "Standard Model" of particle physics isn't a fundamental set of rules we have to guess. Instead, it is a shadow cast by a deeper, holographic reality.

The Old Paradigm: We are trying to build a house by balancing bricks on top of each other, and we have to be incredibly precise to keep it from falling.
The New Paradigm: The house is actually a projection from a blueprint. If the blueprint (the hologram) is set up correctly, the house builds itself perfectly, and the "fine-tuning" we worried about was just an illusion caused by looking at the bricks instead of the blueprint.

In short: The universe doesn't need to be fine-tuned because the "input" isn't the messy details of particles, but the simple, fixed number of degrees of freedom in a holographic system. Once you fix that number, the rest of physics falls into place naturally.

Technical Summary: Holograms and Standard Models

Problem Statement
The authors argue that the current paradigm of particle physics, Wilsonian Quantum Field Theory (QFT), is inadequate for resolving fundamental puzzles that have persisted for over 50 years, specifically the "fine-tuning" problem regarding the vacuum energy (cosmological constant). In standard QFT, the vacuum energy receives huge quantum corrections dependent on physics up to the Planck scale, requiring extreme fine-tuning of parameters to match the observed small value. The paper posits that this paradigm should be replaced by one based on the Holographic Principle, specifically applied to de Sitter (dS) space rather than the more common Anti-de Sitter (AdS) space. The central question is whether a "Standard Model" (SM) of particle physics can emerge from a holographic theory in the flat-space limit ( $G \to 0$ ) without requiring such fine-tuning.

Methodology
The paper employs a "toy" model approach, constructing a simplified but non-trivial correspondence between a holographic boundary theory and a bulk particle physics theory.

Static Patch Holography: The authors utilize the static patch of Jackiw-Teitelboim (JT) de Sitter gravity. They analyze the system in the limit of high Boltzmann temperature ( $T_B \to \infty$ ), where the "sliver" of the static patch expands to fill the bulk, effectively eliminating the original bulk geometry and leaving a holographic description on the stretched horizon.
DSSYK $_\infty$ Model: The boundary theory is identified as the Double-Scaled Sachdev-Ye-Kitaev (DSSYK) model with $N$ fermions in the limit $N \to \infty$ . The model involves random couplings $J_{i_1 \dots i_p}$ drawn from a Gaussian ensemble.
Flat-Space Limit (FSL): The authors define the FSL by taking $N \to \infty$ (implying $G \to 0$ ) while keeping energies fixed and the double-scaling parameter $\lambda = p^2/N$ fixed. In this limit, the static patch geometry becomes flat Rindler space.
Ensemble Averaging vs. Unaveraged Theory: The authors distinguish between the Ensemble Averaged (EA) theory (where couplings are integrated out) and the Unaveraged (UA) theory (fixed couplings). They demonstrate "perfect self-averaging" in the FSL, where symmetry violations in the UA theory vanish faster than any exponential in $N^{1/2}$ , allowing the assumption of exact $O(N)$ or $U(N)$ symmetry.
Duality Mapping: The authors map the parameters of the DSSYK $_\infty$ model to the 't Hooft model (1+1 dimensional QCD with $N$ colors and one flavor). They establish a correspondence where the $O(N)$ or $U(N)$ global symmetry of the hologram becomes the gauge symmetry of the bulk.

Key Contributions and Results

Emergence of a Gauge Theory: The paper demonstrates that the bulk physics emerging from the DSSYK $_\infty$ hologram in the flat-space limit is a gauge theory, specifically the 't Hooft model ( $QCD_2 \times U(1)$ ). The global symmetries of the boundary fermions map to the gauge symmetries of the bulk.
Particle Spectrum: The spectrum of the emergent theory includes:
- Regge Trajectories: Dynamically propagating mesons corresponding to $n \ge 2$ singlet operators.
- Non-Propagating Gauge Fields: The $n=0$ and $n=1$ states correspond to a photon and a graviton, respectively. In 1+1 dimensions, these do not propagate as dynamical particles but mediate long-range Coulomb and gravitational forces.
- Confinement: The theory exhibits quark confinement via a linear potential, analogous to the open string tension in the 't Hooft model.
Resolution of Fine-Tuning: The paper provides a mechanism to resolve the cosmological constant problem without supersymmetry.
- In the holographic framework, the vacuum energy density is inversely proportional to the de Sitter entropy ( $S$ ).
- In the limit $T_B \to \infty$ , the entropy is determined solely by the dimension of the Hilbert space ( $S = N \log 2$ for Dirac fermions) and is independent of the Hamiltonian or interaction details.
- Consequently, there are no quantum corrections to the entropy, and thus no quantum corrections to the vacuum energy. The "fine-tuning" is replaced by the selection of a large $N$ (the "input" parameter), which naturally yields a small vacuum energy.
Holographic Tuning vs. QFT Tuning: The authors show that what appears as fine-tuning in Wilsonian QFT (adjusting coupling constants $g$ to cancel large corrections) is a misinterpretation of the holographic setup. In the holographic theory, $N$ and $\lambda$ are the fundamental inputs fixed at $T_B = \infty$ . The gauge coupling $g$ is a derived quantity ( $g^2 = \lambda$ ) that is fixed by the choice of $N$ . A small shift in the derived $g$ in QFT corresponds to a massive shift in the input $N$ , which is not a fine-tuning problem in the holographic context but a "set it and forget it" mechanism.

Significance and Claims
The authors claim that this work offers a "new paradigm" for particle physics based on the Holographic Principle.

Paradigm Shift: They argue that the Standard Model should be viewed as the flat-space limit of a holographic theory, where the input parameters are holographic (e.g., $N$ , $\lambda$ , $T_B$ ) rather than field-theoretic UV parameters.
Fine-Tuning: The paper claims to resolve the hierarchy and cosmological constant problems by showing that in a holographic theory at infinite temperature, the vacuum energy is protected from quantum corrections by the exactness of the entropy formula. This occurs without the need for supersymmetry.
Scope: The authors explicitly state that their results are derived from a "toy" model (1+1 dimensions, DSSYK $_\infty$ ). They do not claim to have derived the full 4D Standard Model but argue that the mechanism for evading fine-tuning and the emergence of gauge symmetry from holographic symmetries are general principles that should apply to more realistic higher-dimensional de Sitter holographic theories.
Modesty: The paper acknowledges that the duality between DSSYK $_\infty$ and JT-de Sitter is unproven and that the derivation of the full Standard Model from a hologram remains a largely unachieved ambition. However, they assert that the toy model successfully demonstrates how a rich particle physics structure and the resolution of fine-tuning can emerge from holographic principles.