Related Experiment Video
Updated: May 3, 2026
07:46
Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
8.2K
Anomaly nucleation constrains SU(2) gauge theories
1Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030, USA.
Physical Review Letters
|February 4, 2014
Summary
New constraints on SU(2) gauge theories are proposed, crucial for avoiding anomalies in string theory compactifications. Most standard model realizations are inconsistent without additional fermions.
Area of Science:
- High Energy Physics
- String Theory
- Quantum Field Theory
Background:
- SU(2) gauge theories are fundamental in particle physics.
- String theory compactifications provide ultraviolet completions for quantum field theories.
- Anomalies can render quantum field theories inconsistent.
Purpose of the Study:
- To investigate additional constraints on SU(2) gauge theories in four dimensions.
- To explore the role of D-brane nucleation analogs in these constraints.
- To determine the implications for anomalies and particle physics models.
Main Methods:
- Analysis of SU(2) gauge theories within ultraviolet completions.
- Examination of type II string compactifications with D-brane nucleation analogs.
- Investigation of cubic non-Abelian anomalies in nucleated SU(N>2) theories.
Main Results:
- Existence of additional constraints on SU(2) gauge theories is argued.
- These constraints are necessary and sufficient for anomaly absence in specific SU(N>2) theories.
- Such constraints appear broadly in the string landscape.
Conclusions:
- Most standard model realizations in this context are inconsistent.
- Inconsistency can be resolved by introducing extra electroweak fermions.
- The findings have significant implications for particle physics model building.
Related Concept Videos
01:16Second Uniqueness Theorem
1.4K
Consider a region consisting of several individual conductors with a definite charge density in the region between these conductors. The second uniqueness theorem states that if the total charge on each conductor and the charge density in the in-between region are known, then the electric field can be uniquely determined.
In contrast, consider that the electric field is non-unique and apply Gauss's law in divergence form in the region between the conductors and the integral form to the surface...
In contrast, consider that the electric field is non-unique and apply Gauss's law in divergence form in the region between the conductors and the integral form to the surface...
1.4K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.5K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
1.5K
03:18Nuclear Stability
20.5K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively...
To hold positively...
20.5K
01:21Nondisjunction
4.5K
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers. Nondisjunction is common during anaphase I or anaphase II of meiosis. Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold...
4.5K
01:29Nondisjunction
68.0K
During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.
68.0K
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
143
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
143