Essential Question: Why is finding supersymmetric particles and important task for physicists to undertake?
Answer: The lightest supersymmetric particle (LSP,) if stable, is a very good candidate for Weakly Interacting Massive Particles (WIMPs) or dark matter.
1. Supersymmetric neutralinos (gravitinos, axinos, singlinos, higgsinos, binos, winos, photinos, etc.) can be thermally produced in the early universe and leave exactly the right relic density to constitute the Cold Dark Matter of the universe.
2. Detecting supersymmetric dark matter may be the best way to find SUSY particles. SUSY particles are expected to be extremely heavy (reaching into the multi-TeV range) and thus are likely out of reach of collider physics. However, dark matter detection experiments (such as Ice Cube in Antarctica) can be specifically calibrated to find neutralinos.
3. There can be multiple possible models of SUSY dark matter, as different SUSY models yield different LSPs. For example, the Next-to-Minimal Supersymmetric Standard Model yields an LSP called the singlino, which is a good candidate for dark matter should the Minimal Supersymmetric Standard Model become too constrained. In addition, it is possible for neutralino dark matter to be non thermally produced, as well as in a "mixed" state such as with axions.
I plan on taking my science project on neutralino dark matter to the science fair. I am interested in hearing feedback on it as well as what others think the most likely neutralino dark matter model is.
Jedamzik, Karsten and Maxim Pospelov. "Big Bang Nucleosynthesis and Particle Dark Matter." Cornell University Library, 11 Jun. 2009. Web. 21 Feb. 2013.
Wednesday, February 27, 2013
Wednesday, February 20, 2013
Blog 17: Fourth Interview Questions
1. Why is finding supersymmetric particles an important task for physicists to undertake?
2. What do you believe is the most accurate model of supersymmetry proposed today?
3. What are the implications for the Cold Dark Matter search if supersymmetry is found not to exist?
4. How might scientists go about disproving supersymmetry if there is no empirical evidence found?
5. How might scientists go about narrowing down proposed supersymmetric models?
6. How might scientists go about narrowing down supersymmetric dark matter models?
7. What do you believe is the next step we must take in our efforts to locate supersymmetric particles?
8. If a spontaneously broken supersymmetry does not solve the problem of the vacuum energy all the way, what are the implications?
9. In what way, if any, can the problem of the vacuum energy be resolved without supersymmetry?
10. If supersymmetry is discovered, what are the implications for string theory?
11. Is it necessary for us to narrow down the number of superstring theories? If so, how can we do it?
12. How can theoretical physicists avoid being "not even wrong" about supersymmetry?
13. If supersymmetric particles are self interacting, how will this change our search for them as dark matter?
14. How to you believe an experiment solely dedicated to looking for supersymmetric particles would be received by scientists and donors?
15. If another, lighter Higgs Boson is found, what are the implications for supersymmetry?
16. What theories, if any, do you believe can explain the Hierarchy Problem in place of supersymmetry?
17. Can string theory be complete without supersymmetry? Why or why not?
18. Do you believe superstring theory is the "best" theory of quantum gravity? Why? If not, what other theories do you believe are better?
19. What, if anything, does the quantum vacuum say about dark energy?
20. What is wrong with very heavy sparticles?
No need to worry about the end of the universe, for those who saw the article. Supersymmetry will save us! Maybe...
2. What do you believe is the most accurate model of supersymmetry proposed today?
3. What are the implications for the Cold Dark Matter search if supersymmetry is found not to exist?
4. How might scientists go about disproving supersymmetry if there is no empirical evidence found?
5. How might scientists go about narrowing down proposed supersymmetric models?
6. How might scientists go about narrowing down supersymmetric dark matter models?
7. What do you believe is the next step we must take in our efforts to locate supersymmetric particles?
8. If a spontaneously broken supersymmetry does not solve the problem of the vacuum energy all the way, what are the implications?
9. In what way, if any, can the problem of the vacuum energy be resolved without supersymmetry?
10. If supersymmetry is discovered, what are the implications for string theory?
11. Is it necessary for us to narrow down the number of superstring theories? If so, how can we do it?
12. How can theoretical physicists avoid being "not even wrong" about supersymmetry?
13. If supersymmetric particles are self interacting, how will this change our search for them as dark matter?
14. How to you believe an experiment solely dedicated to looking for supersymmetric particles would be received by scientists and donors?
15. If another, lighter Higgs Boson is found, what are the implications for supersymmetry?
16. What theories, if any, do you believe can explain the Hierarchy Problem in place of supersymmetry?
17. Can string theory be complete without supersymmetry? Why or why not?
18. Do you believe superstring theory is the "best" theory of quantum gravity? Why? If not, what other theories do you believe are better?
19. What, if anything, does the quantum vacuum say about dark energy?
20. What is wrong with very heavy sparticles?
No need to worry about the end of the universe, for those who saw the article. Supersymmetry will save us! Maybe...
Wednesday, February 6, 2013
Blog 16: 2-Hour Meeting Answer #2
Essential Question: Why is finding supersymmetric particles an important task for physicists to undertake?
Answer 2: Supersymmetry is the one of the only theories that can completely solve the hierarchy problem of the Standard Model.
1. The hierarchy problem is one of the biggest inconsistencies of the Standard Model. We have observed the mass of the Higgs Boson to be ~125 GeV. The trouble is that the mass should be much greater than that due to a phenomenon called "quantum corrections." Without some very tight fine-tuning between the quantum corrections and the regular mass, this seems impossible. However, physicists don't like unexplained fine-tunings.
2. The Higgs Boson will couple to the most massive particles in the Standard Model, thus most of the quantum corrections to its mass will come from those particles, such as the top quark, which is the heaviest Standard Model particle. Supersymmetry predicts the existence of a stop squark partner for the top quark. As it turns out, the corrections from the stop squark should cancel with those from the top quark, leaving just enough left over to give us the Higgs mass we see in nature.
![\Delta m_{H}^{2} = 2* \frac{\lambda_{S}}{16\pi^2} [\Lambda_{UV}^2+ ...].](http://upload.wikimedia.org/math/0/a/2/0a2ccd5c4998ac5ee33bb920fd4fc0fe.png)
(Contributions from both-assume one negative and one positive contribution, where UV is the Planck scale.)
3. There isn't a theory that explains the hierarchy problem so cleanly and accurately. If supersymmetry doesn't exist, it is important that physicists begin work on another theory so we do not have any unexplained fine-tunings. Therefore it is important that we continue the search for supersymmetric particles, just in case we have to start work on another theory.
Source: Warped Passages by Lisa Randall. I could never really wrap my head around the hierarchy problem but she made it very clear and understandable, and she explains why supersymmetry is such a good solution for it.
I plan to bulk up on my knowledge of Quantum Field Theory, and on Richard Feynman's work. I never cared for Feynman as a person, but as Einstein would say, "There is no emotion in science!*" I want to be able to create my own Feynman diagrams so I can better understand them.
*Einstein didn't really say this.
Answer 2: Supersymmetry is the one of the only theories that can completely solve the hierarchy problem of the Standard Model.
1. The hierarchy problem is one of the biggest inconsistencies of the Standard Model. We have observed the mass of the Higgs Boson to be ~125 GeV. The trouble is that the mass should be much greater than that due to a phenomenon called "quantum corrections." Without some very tight fine-tuning between the quantum corrections and the regular mass, this seems impossible. However, physicists don't like unexplained fine-tunings.
2. The Higgs Boson will couple to the most massive particles in the Standard Model, thus most of the quantum corrections to its mass will come from those particles, such as the top quark, which is the heaviest Standard Model particle. Supersymmetry predicts the existence of a stop squark partner for the top quark. As it turns out, the corrections from the stop squark should cancel with those from the top quark, leaving just enough left over to give us the Higgs mass we see in nature.
(Contributions from both-assume one negative and one positive contribution, where UV is the Planck scale.)3. There isn't a theory that explains the hierarchy problem so cleanly and accurately. If supersymmetry doesn't exist, it is important that physicists begin work on another theory so we do not have any unexplained fine-tunings. Therefore it is important that we continue the search for supersymmetric particles, just in case we have to start work on another theory.
Source: Warped Passages by Lisa Randall. I could never really wrap my head around the hierarchy problem but she made it very clear and understandable, and she explains why supersymmetry is such a good solution for it.
I plan to bulk up on my knowledge of Quantum Field Theory, and on Richard Feynman's work. I never cared for Feynman as a person, but as Einstein would say, "There is no emotion in science!*" I want to be able to create my own Feynman diagrams so I can better understand them.
*Einstein didn't really say this.
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