|
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
Monopoles [was Dark Matter vs Dark Energy]
|
#12
|
|||
|
|||
Monopoles [was Dark Matter vs Dark Energy]
|
#13
|
|||
|
|||
Monopoles [was Dark Matter vs Dark Energy]
[s.a.r. mod. note: followups to s.p.r., please -- mjh]
You are talking about nonsupersymmetric SU(5). When you include supersymmetry, it predicts a much higher proton lifetime. The reason is basically as follows. All particles have a self-energy caused by constantly emitting and reabsorbing virtual particles, which we then explain away using renormalization. The self-energy consists of emitting virtual particles of all the different types of particles in existence. In supersymmetric models, there are twice the number of particles in existence, which means particles are constantly emitting and reabsorbing all the heavy supersymmetric particles, which effects the renormalization. This then changes the renormalization group and equations and the beta equations. This changes the running of the coupling constants, and in fact it causes the coupling constants to converge. In grand unified theory all by itself, the coupling constants almost converge but not quite. In grand unification combined with supersymmetry, they exactly converge. The point where they converge, would be the point at which grand unified theory is broken. The GUT scale would be at about 10^16 GeV, which means the X and Y bosons called leptoquarks would have masses about 10^16 GeV, which is higher than grand unification without supersymmetry. Therefore supersymmetry causes the X and Y bosons to have higher mass. If they have higher mass, they have shorter range, and so it would be rarer that two particles will stray close enough to exchange one. Thereforefore they will lower cross section. Proton decay is caused by the exchange of X and Y bosons. If this happens more rarely, protons will decay more rarely, and the proton lifetime is rarer. Without supersymmetry, the proton has a lifetime of 10^30 years whch has been ruled out by experiment. If you include supersymmetry, the proton has a lifetime of 10^32 years which has not been ruled out, and can never be ruled out because you can't distinguish it from the intrinsic background caused by neutrinos. Now about inflation. If you watch ice freezing on a pond, the entire surface doesn't freeze at once, and the ice doesn't expand from a single point. Different parts of the ice freeze, and then when these different sections meet there is a zig zag boundary between them. In the liquid water, the molecules are unoriented, and when they freeze they become oriented, and in different parts of the pond, they point in different directions. The boundaries between them are called topological defects. The freezing of water breaks the isotropic symmetry of the water molecules. The same thing happens in the early universe. The early universe, such as as at the grand unification breaking scale goes through symmetry breaking. The Higgs field was originally not pointing in any direction, but then when it undergoes symmetry breaking, it ends up pointing in a random direction. In parts of the universe that aren't casually connected, the Higgs field points in different directions. Then as time goes on, they come in contact, and the boundaries between them are topological defects. There are different types of topological defects due to the different types of symmetry breaking and the orientation of the fields, such as monopoles, strings, domain walls, textures, or skyrmions. Grand Unified Theory predicts that magneti monopoles would be created in great profusion. However, we have never detected one. This is called the monopole problem and is one of the three main problems with the traditional Big Bang model, the other two being the flatness problem and horizon problem. All three of these problems can be solved with inflation. Let's say that the universe underwent an enormous expansion at the beginning of its existence. A sphere with a radius of the planck length could expand to several orders of magnitude larger than the current observable universe in just the planck time. Therefore, it would very unlikely that there would be any monopoles within our current observable universe. If you don't like the fact that the Standard Model just links the groups together to form SU(3) x SU(2) x U(1), then go ahead and use SU(5), SO(10), supersymmetric SU(5) or SO(10), SO(32), or E_8 x E_8. Jeffery Winkler http://www.geocities.com/jefferywinkler |
#14
|
|||
|
|||
Monopoles [was Dark Matter vs Dark Energy]
[s.a.r. mod. note: followups to s.p.r., please -- mjh]
You are talking about nonsupersymmetric SU(5). When you include supersymmetry, it predicts a much higher proton lifetime. The reason is basically as follows. All particles have a self-energy caused by constantly emitting and reabsorbing virtual particles, which we then explain away using renormalization. The self-energy consists of emitting virtual particles of all the different types of particles in existence. In supersymmetric models, there are twice the number of particles in existence, which means particles are constantly emitting and reabsorbing all the heavy supersymmetric particles, which effects the renormalization. This then changes the renormalization group and equations and the beta equations. This changes the running of the coupling constants, and in fact it causes the coupling constants to converge. In grand unified theory all by itself, the coupling constants almost converge but not quite. In grand unification combined with supersymmetry, they exactly converge. The point where they converge, would be the point at which grand unified theory is broken. The GUT scale would be at about 10^16 GeV, which means the X and Y bosons called leptoquarks would have masses about 10^16 GeV, which is higher than grand unification without supersymmetry. Therefore supersymmetry causes the X and Y bosons to have higher mass. If they have higher mass, they have shorter range, and so it would be rarer that two particles will stray close enough to exchange one. Thereforefore they will lower cross section. Proton decay is caused by the exchange of X and Y bosons. If this happens more rarely, protons will decay more rarely, and the proton lifetime is rarer. Without supersymmetry, the proton has a lifetime of 10^30 years whch has been ruled out by experiment. If you include supersymmetry, the proton has a lifetime of 10^32 years which has not been ruled out, and can never be ruled out because you can't distinguish it from the intrinsic background caused by neutrinos. Now about inflation. If you watch ice freezing on a pond, the entire surface doesn't freeze at once, and the ice doesn't expand from a single point. Different parts of the ice freeze, and then when these different sections meet there is a zig zag boundary between them. In the liquid water, the molecules are unoriented, and when they freeze they become oriented, and in different parts of the pond, they point in different directions. The boundaries between them are called topological defects. The freezing of water breaks the isotropic symmetry of the water molecules. The same thing happens in the early universe. The early universe, such as as at the grand unification breaking scale goes through symmetry breaking. The Higgs field was originally not pointing in any direction, but then when it undergoes symmetry breaking, it ends up pointing in a random direction. In parts of the universe that aren't casually connected, the Higgs field points in different directions. Then as time goes on, they come in contact, and the boundaries between them are topological defects. There are different types of topological defects due to the different types of symmetry breaking and the orientation of the fields, such as monopoles, strings, domain walls, textures, or skyrmions. Grand Unified Theory predicts that magneti monopoles would be created in great profusion. However, we have never detected one. This is called the monopole problem and is one of the three main problems with the traditional Big Bang model, the other two being the flatness problem and horizon problem. All three of these problems can be solved with inflation. Let's say that the universe underwent an enormous expansion at the beginning of its existence. A sphere with a radius of the planck length could expand to several orders of magnitude larger than the current observable universe in just the planck time. Therefore, it would very unlikely that there would be any monopoles within our current observable universe. If you don't like the fact that the Standard Model just links the groups together to form SU(3) x SU(2) x U(1), then go ahead and use SU(5), SO(10), supersymmetric SU(5) or SO(10), SO(32), or E_8 x E_8. Jeffery Winkler http://www.geocities.com/jefferywinkler |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Has ESA's XMM-Newton cast doubt over dark energy? (Forwarded) | Andrew Yee | Astronomy Misc | 0 | December 12th 03 07:15 PM |
"Dark matter" forms dense clumps in ghost universe (Forwarded) | Andrew Yee | Astronomy Misc | 0 | November 21st 03 04:41 PM |
A Detailed Map of Dark Matter in a Galactic Cluster Reveals How Giant Cosmic Structures Formed | Ron Baalke | Astronomy Misc | 3 | August 5th 03 02:16 PM |
PLANETS ORBIT THE SUN TO CONSERVE TOTAL ENERGY | GRAVITYMECHANIC2 | Astronomy Misc | 0 | July 20th 03 04:59 PM |
Hubble tracks down a galaxy cluster's dark matter (Forwarded) | Andrew Yee | Astronomy Misc | 0 | July 17th 03 01:42 PM |