11.3 Supersymmetry and its predictions
4 min read•august 1, 2024
proposes a new symmetry between particles, doubling the Standard Model's particle count. It aims to solve key issues like the and offers a framework for unifying fundamental forces.
predicts for known particles and introduces the (). This could explain dark matter and help unify forces at high energies, potentially bridging quantum mechanics and gravity.
Supersymmetry: Extending the Standard Model
Theoretical Framework and Implications
Top images from around the web for Theoretical Framework and Implications
particle physics - Supersymmetry and grand unification - Physics Stack Exchange View original
Is this image relevant?
Supersymmetry Archives - Universe Today View original
Is this image relevant?
Supersymmetry - Wikipedia View original
Is this image relevant?
particle physics - Supersymmetry and grand unification - Physics Stack Exchange View original
Is this image relevant?
Supersymmetry Archives - Universe Today View original
Is this image relevant?
1 of 3
Top images from around the web for Theoretical Framework and Implications
particle physics - Supersymmetry and grand unification - Physics Stack Exchange View original
Is this image relevant?
Supersymmetry Archives - Universe Today View original
Is this image relevant?
Supersymmetry - Wikipedia View original
Is this image relevant?
particle physics - Supersymmetry and grand unification - Physics Stack Exchange View original
Is this image relevant?
Supersymmetry Archives - Universe Today View original
Is this image relevant?
1 of 3
- Supersymmetry (SUSY) proposes a symmetry between fermions and bosons predicting each known particle has a supersymmetric partner
- SUSY addresses the hierarchy problem concerning the large difference between the weak force and gravity
- Introduces a new quantum number called distinguishing between Standard Model particles and their supersymmetric partners
- Minimal supersymmetric extension of the Standard Model () doubles the number of particles in the Standard Model
- Provides a framework for unification of fundamental forces at high energies potentially bridging the gap between quantum mechanics and general relativity
- Represents a significant paradigm shift in particle physics offering a more complete description of nature at the most fundamental level
Addressing Standard Model Limitations
- Tackles several limitations of the Standard Model
- Offers potential solutions to theoretical issues (hierarchy problem)
- Expands particle zoo with predicted superpartners
- Introduces new symmetry principles to particle physics
- Provides a framework for incorporating gravity into particle physics through theories
- Suggests mechanisms for resolving by potentially cancelling zero-point energies of bosons and fermions
Bosons vs Fermions in Supersymmetry
Superpartner Pairings
- Every known elementary particle paired with a superpartner differing in spin by 1/2 unit
- Fermions (spin-1/2 particles) paired with bosonic superpartners called
- Bosons (integer spin particles) paired with fermionic superpartners
- Superpartners of Standard Model fermions named by adding prefix "s-" (, )
- Superpartners of bosons named by adding suffix "-ino" (, )
- convert fermions into bosons and vice versa maintaining total number of degrees of freedom in the theory
Theoretical Implications
- Relationship between bosons and fermions in SUSY theories leads to cancellation of quantum corrections to particle masses
- Potentially solves the hierarchy problem through
- In unbroken supersymmetry superpartners would have identical masses to their Standard Model counterparts
- Symmetry must be broken in nature to explain why superpartners have not been observed
- Breaking mechanisms introduce mass differences between particles and their superpartners
- Precise nature of SUSY breaking remains an active area of theoretical research
Supersymmetry Predictions: Superpartners and LSP
Superpartner Predictions
- Predicts existence of complete set of superpartners for all known elementary particles
- Effectively doubles the particle content of the Standard Model
- Predicts Higgs boson mass below about 135 GeV consistent with observed mass of 125 GeV
- Forecasts existence of multiple Higgs bosons two charged Higgs bosons one CP-odd neutral Higgs boson and two CP-even neutral Higgs bosons
- Precise masses and properties of superpartners depend on specific SUSY breaking mechanism
- Various phenomenological models with distinct experimental signatures arise from different breaking scenarios
Lightest Supersymmetric Particle (LSP)
- LSP crucial prediction of many SUSY models often assumed stable due to R-parity conservation
- In many SUSY scenarios LSP predicted to be the
- Neutralino mixture of superpartners of photon Z boson and neutral Higgs bosons
- LSP characteristics depend on specific SUSY model parameters
- Stability of LSP makes it a candidate for dark matter
- Experimental searches for LSP focus on in particle colliders
Supersymmetry Implications: Dark Matter and Force Unification
Dark Matter Connections
- LSP if stable and weakly interacting serves as leading candidate for dark matter
- Potentially explains observed dark matter abundance in the universe
- LSP production in could lead to distinctive missing energy signatures
- Indirect evidence for dark matter might be obtained through these collider observations
- SUSY models provide framework for calculating dark matter relic abundance
- Constraints from dark matter observations help narrow down viable SUSY parameter space
Force Unification and High-Energy Physics
- Naturally provides mechanism for
- Strengths of electromagnetic weak and strong forces converge at high energies in SUSY models
- Unification typically occurs at energy scale of about GeV
- Consistent with constraints from proton decay experiments
- Offers framework for incorporating gravity into particle physics through supergravity theories
- Could lead to bridging quantum mechanics and general relativity
- Absence of observed superpartners at current collider energies necessitates more complex breaking mechanisms or higher mass scales for superpartners
Key Terms to Review (27)
Collider experiments: Collider experiments are high-energy physics experiments where particles are accelerated to nearly the speed of light and collided together, allowing scientists to study fundamental interactions and create conditions similar to those just after the Big Bang. These experiments play a crucial role in exploring the properties of subatomic particles and testing theoretical predictions, such as those related to new physics phenomena like supersymmetry.
Cosmological constant problem: The cosmological constant problem refers to the significant discrepancy between the observed value of the cosmological constant, which contributes to the acceleration of the universe's expansion, and the theoretical predictions made by quantum field theories. This issue highlights the struggle to reconcile how vacuum energy should contribute to the energy density of the universe, with calculations predicting a value that is many orders of magnitude larger than what is observed. This problem leads to deeper questions about the fundamental laws of physics and suggests potential new physics beyond our current understanding.
Dark matter candidates: Dark matter candidates are theoretical particles or entities proposed to make up dark matter, which is an unseen component of the universe that exerts gravitational effects on visible matter. Understanding these candidates is crucial for explaining cosmic phenomena, as they may help bridge gaps in our current knowledge of fundamental physics and particle interactions.
Gauge coupling unification: Gauge coupling unification refers to the idea that the fundamental forces of nature, described by gauge theories, converge at high energy scales into a single interaction. This concept is crucial in theoretical physics, particularly in supersymmetry, as it provides a framework for understanding how different forces might be manifestations of a single underlying force at very high energies.
Gluino: A gluino is a hypothetical supersymmetric partner of the gluon, which is a fundamental particle responsible for the strong force that binds quarks together within protons and neutrons. Gluinos, like all supersymmetric particles, are predicted to have half-integer spin, specifically spin-1/2, making them fermions. They play a critical role in various models of supersymmetry, which aim to explain the imbalance between matter and antimatter and provide solutions to several outstanding problems in particle physics.
Hermann Nicolai: Hermann Nicolai is a theoretical physicist known for his significant contributions to the field of supersymmetry, particularly in the development of models and frameworks that explore the implications of this theory. His work focuses on the connections between supersymmetry and string theory, which aim to unify fundamental forces and particles. Nicolai's research has helped to deepen the understanding of how supersymmetry can provide solutions to some longstanding issues in particle physics, such as the hierarchy problem.
Hierarchy Problem: The hierarchy problem refers to the question of why the weak force is so much stronger than gravity, despite the two forces being unified in the framework of particle physics. This discrepancy suggests that there must be a natural mechanism that stabilizes the mass of the Higgs boson, preventing it from being influenced by quantum corrections that would otherwise make it much heavier. This issue is central to discussions around new physics and has implications for theories such as supersymmetry and other models aiming to explain fundamental forces.
Lightest supersymmetric particle: The lightest supersymmetric particle (LSP) is a hypothetical particle predicted by supersymmetry theories, which proposes a partner particle for every known particle in the Standard Model. The LSP is particularly important because it is expected to be stable, neutral, and the most challenging to detect, potentially serving as a candidate for dark matter. Its properties and interactions have significant implications in particle physics and cosmology.
LSP: LSP stands for Lightest Supersymmetric Particle, which is a key concept in supersymmetry theories in particle physics. The LSP is the lightest of the superpartners of known particles and is often considered a candidate for dark matter due to its stable nature and weak interactions with ordinary matter. Understanding the LSP is crucial as it provides insights into the unification of forces and the search for new physics beyond the Standard Model.
Missing energy signatures: Missing energy signatures refer to the observation of energy and momentum that seems to disappear during high-energy particle collisions, particularly in the context of detecting new particles. This phenomenon often indicates the production of invisible particles, like neutrinos or potential dark matter candidates, which escape detection but conserve overall energy and momentum in the system. These signatures play a crucial role in identifying processes predicted by theories like supersymmetry.
MSSM: The Minimal Supersymmetric Standard Model (MSSM) is an extension of the Standard Model of particle physics that incorporates supersymmetry, proposing a partner particle for every known particle. This model aims to address several limitations of the Standard Model, such as the hierarchy problem and the unification of forces. The MSSM predicts the existence of superpartners, enhances the stability of the Higgs boson mass, and provides potential candidates for dark matter.
Neutralino: A neutralino is a hypothetical elementary particle predicted by supersymmetry, which serves as a potential candidate for dark matter. It is a linear combination of the superpartners of the neutral gauge and Higgs bosons, and its properties are essential in understanding the implications of supersymmetry in particle physics. The existence of neutralinos suggests new physics beyond the Standard Model and impacts our search for solutions to fundamental questions about mass and stability in the universe.
Quantum theory of gravity: Quantum theory of gravity is a theoretical framework that seeks to describe gravity using the principles of quantum mechanics. It aims to unify general relativity, which describes gravity as the curvature of spacetime, with quantum mechanics, which governs the behavior of particles at the smallest scales. This unification is crucial for understanding phenomena in extreme environments, such as black holes and the early universe.
R-parity: R-parity is a symmetry in supersymmetry theories that helps distinguish between particles and their superpartners. It plays a crucial role in defining the conservation laws in particle interactions and dictates the properties of the lightest supersymmetric particle (LSP). R-parity ensures that certain processes are allowed or forbidden, which can lead to significant implications for dark matter candidates and collider physics.
Selectron: A selectron is a hypothetical supersymmetric partner of the electron, predicted by the theory of supersymmetry. In this framework, every fermion, including the electron, has a corresponding bosonic partner, and the selectron represents this concept specifically for electrons. Selectrons are important in understanding the potential for new physics beyond the Standard Model and play a critical role in various supersymmetric models.
Sergio Ferrara: Sergio Ferrara is an Italian theoretical physicist known for his significant contributions to the field of supersymmetry, particularly in the context of string theory and particle physics. His work has helped advance the understanding of the connections between supersymmetry and various models of particle physics, providing insights into the unification of forces and the nature of fundamental particles.
Sfermions: Sfermions are hypothetical particles in supersymmetry that are the superpartners of fermions. Each fermion, which includes particles like quarks and leptons, has a corresponding sfermion, such as squarks and sleptons. These particles help to balance the equations in supersymmetry, providing a more unified understanding of particle interactions and potentially explaining dark matter.
Squark: A squark is a hypothetical particle in supersymmetry, proposed as the superpartner of a quark. In supersymmetric theories, every fermion, like quarks which make up protons and neutrons, has a corresponding boson partner, and squarks play a critical role in the unification of forces and potential solutions to various problems in particle physics.
Supergravity: Supergravity is a theoretical framework that combines the principles of supersymmetry and general relativity, proposing that every fermion has a corresponding bosonic superpartner. This theory aims to unify gravity with the other fundamental forces and suggests that at high energies, spacetime may exhibit additional dimensions and features that could explain phenomena such as dark matter and the early universe.
Superpartner interactions: Superpartner interactions refer to the interactions between particles and their corresponding superpartners in supersymmetry, a theoretical framework that extends the Standard Model of particle physics. In this framework, every known particle has a superpartner with differing spin characteristics, which leads to unique interactions that could provide insights into fundamental forces and matter in the universe. Understanding these interactions is crucial for testing the predictions of supersymmetry, especially in relation to dark matter and unification of forces.
Superpartners: Superpartners are theoretical particles predicted by supersymmetry, a concept in particle physics that proposes a symmetry between fermions and bosons. In this framework, every known particle has a corresponding superpartner with differing spin characteristics; fermions, which have half-integer spins, would have bosonic superpartners with integer spins, and vice versa. This idea is crucial for addressing various issues in particle physics, including unifying forces and explaining dark matter.
Supersymmetry: Supersymmetry is a theoretical framework in particle physics that posits a symmetry between bosons and fermions, suggesting that every known particle has a corresponding 'superpartner' with different spin characteristics. This concept aims to resolve several issues within the Standard Model and to provide a candidate for dark matter, while also offering insights into the fundamental nature of particles and forces.
Supersymmetry breaking: Supersymmetry breaking refers to the phenomenon where supersymmetry, a theoretical symmetry between fermions and bosons, does not manifest at observable energy levels. This breaking is crucial as it explains why superpartners of known particles have not been detected, while also providing solutions to various issues in particle physics, such as the hierarchy problem and the unification of forces.
Supersymmetry transformations: Supersymmetry transformations are mathematical operations that relate bosons (particles that carry forces) and fermions (matter particles) within a theoretical framework aimed at unifying the fundamental forces of nature. These transformations are central to supersymmetry, which posits a symmetry between these two classes of particles, suggesting that every boson has a corresponding fermion partner and vice versa. This concept aims to address several gaps in the Standard Model of particle physics and provides insights into phenomena such as dark matter and unification at high energies.
Susy: SUSY, or Supersymmetry, is a theoretical framework in particle physics that proposes a relationship between two basic classes of particles: bosons and fermions. In this model, each particle has a superpartner with different spin characteristics, which helps solve various issues in the Standard Model, such as the hierarchy problem and dark matter candidates. SUSY offers predictions that could lead to new discoveries at particle colliders.
Unification of forces: The unification of forces is the concept in physics that seeks to explain the fundamental interactions of nature as manifestations of a single force or a set of interrelated forces. This idea suggests that at high energy levels, distinct forces such as electromagnetism, weak nuclear force, and strong nuclear force merge into one unified framework. This concept is critical in understanding the fundamental theories that describe particle interactions and the potential links between them.
Wino: A wino is a type of hypothetical particle predicted by supersymmetry, which is theorized to be the superpartner of the Z boson. These particles are part of a larger framework that seeks to explain the fundamental forces and particles in the universe, proposing a relationship between fermions and bosons. Winos are expected to play a crucial role in unifying interactions at high energy levels and may provide insights into dark matter.