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D-branes in Standard Model building, Gravity and Cosmology

Elias Kiritsis

TL;DR

This review surveys how D-branes provide a unified framework to realize the Standard Model, four-dimensional gravity, and cosmology. It covers heterotic, Type I, and Type II compactifications, orientifolds, and intersecting brane constructions that yield chiral spectra and anomaly-canceled U(1)s, with attention to low string scales and phenomenological constraints. It then discusses novel gravity realizations, including Randall–Sundrum localization, brane-induced gravity, and their cosmological implications via brane-bulk energy exchange and mirage cosmology, as well as inflationary scenarios with brane/antibrane dynamics and massive gravity. The article emphasizes the interplay between open-string (brane) dynamics and closed-string (bulk) gravity, offering mechanisms to address hierarchy, dark energy, and early-universe inflation within a string- and brane-based picture, while highlighting theoretical and phenomenological challenges and opportunities.

Abstract

D-branes are by now an integral part of our toolbox towards understanding nature. In this review we will describe recent progress in their use to realize fundamental interactions. The realization of the Standard Model and relevant physics and problems will be detailed. New ideas on realizing 4-dimensional gravity use the brane idea in an important way. Such approaches will be reviewed and compared to the standard paradigm of compactification. Branes can play a pivotal role both in early- and late-universe cosmology mainly via the brane-universe paradigm. Brane realizations of various cosmological ideas (early inflation, sources for dark matter and dark energy, massive gravity etc) will be also reviewed.

D-branes in Standard Model building, Gravity and Cosmology

TL;DR

This review surveys how D-branes provide a unified framework to realize the Standard Model, four-dimensional gravity, and cosmology. It covers heterotic, Type I, and Type II compactifications, orientifolds, and intersecting brane constructions that yield chiral spectra and anomaly-canceled U(1)s, with attention to low string scales and phenomenological constraints. It then discusses novel gravity realizations, including Randall–Sundrum localization, brane-induced gravity, and their cosmological implications via brane-bulk energy exchange and mirage cosmology, as well as inflationary scenarios with brane/antibrane dynamics and massive gravity. The article emphasizes the interplay between open-string (brane) dynamics and closed-string (bulk) gravity, offering mechanisms to address hierarchy, dark energy, and early-universe inflation within a string- and brane-based picture, while highlighting theoretical and phenomenological challenges and opportunities.

Abstract

D-branes are by now an integral part of our toolbox towards understanding nature. In this review we will describe recent progress in their use to realize fundamental interactions. The realization of the Standard Model and relevant physics and problems will be detailed. New ideas on realizing 4-dimensional gravity use the brane idea in an important way. Such approaches will be reviewed and compared to the standard paradigm of compactification. Branes can play a pivotal role both in early- and late-universe cosmology mainly via the brane-universe paradigm. Brane realizations of various cosmological ideas (early inflation, sources for dark matter and dark energy, massive gravity etc) will be also reviewed.

Paper Structure

This paper contains 52 sections, 378 equations, 6 figures, 6 tables.

Table of Contents

  1. Introduction and perspective
  2. A survey of various string theory compactifications
  3. The heterotic string
  4. The type-I string
  5. Type II string theory
  6. Orientifold vacua, chirality and supersymmetry
  7. D-brane mechanics
  8. D-branes at orbifold singularities
  9. Internal magnetic fields and branes intersecting at angles
  10. Intersecting $D_6$-branes
  11. Supersymmetry breaking
  12. Supersymmetry breaking in low-string scale orientifolds
  13. Anomalies and symmetries in four dimensions
  14. Anomalies in six dimensions
  15. String calculation of anomalous U(1) masses
  16. ...and 37 more sections

Figures (6)

  • Figure 1: Pictorial representation of models$A, A'$.
  • Figure 2: Pictorial representation of models $B$ and $B'$.
  • Figure 3: Evolution of the ratio $m_b/m_\tau$ as a function of the energy $\mu$ for $\tan \beta=2$ and $\tan \beta=80$. We have used as low energy parameters $m_b=4$GeV, $m_{top}=174$GeV$a_3(M_z)=0.12$, $\sin^2\theta_W=0.23113$.
  • Figure 4: Different regions in density, during the evolution of the universe for $Kr_c<<1$.
  • Figure 5: Outflow, $k=0$, $w=0$, $\nu=1$. The arrows show the direction of increasing scale factor
  • ...and 1 more figures