Tuesday, July 10, 2012

Volcano and Aurora

Volcano and Aurora in Iceland
Image Credit & Copyright: Sigurdur H. Stefnisson


Explanation: Sometimes both heaven and Earth erupt. In Iceland in 1991, the volcano Hekla erupted at the same time that auroras were visible overhead. Hekla, one of the most famous volcanoes in the world, has erupted at least 20 times over the past millennium, sometimes causing great destruction. The last eruption occurred only twelve years ago but caused only minor damage. The green auroral band occurred fortuitously about 100 kilometers above the erupting lava. Is Earth the Solar System's only planet with both auroras and volcanos? See: Astronomy Picture of the Day

It is of great consequence that while we understand the sun has it's place in the sky,  do we understand the interactions that are taking place as the Earth radiates as well? If thunderstorms can releases information for us,  then it puts a whole new spin on what is happening within Earth's space.





See:

Also See:

Monday, July 09, 2012

Latest SDO IMage

This image taken by SDO's AIA instrument at 171 Angstrom shows the current conditions of the quiet corona and upper transition region of the Sun.

Active Region 1515 released an M6.9 class flare beginning at 12:23 PM EDT and peaking at 12:32 on July 7, 2012. This region has been the source of much solar activity since July 2.


See: Today's Space Weather

This plot shows 3-days of 5-minute solar x-ray flux values measured on the SWPC primary GOES satellite. One low value may appear prior to eclipse periods. Click on the plot to open an updating secondary window. 6-hour 1-min Solar X-ray Flux plot.

Our Backyard Chickens




As you can see the picture is from 2010 so we have had them for a few years now. We have had chickens in the past, but not in as elaborate set up as we have now.



As you can see it only took a couple of days. Sort of designed it our selves.


This is Buddy our Rooster. Nancy beside him and in the background they are called the Divas as we cannot tell whose who as a account we cannot tell them apart.


So yes after being completed a home.

 This years we let the hen incubate 4 eggs and only two survived.  That's them four weeks old after hatching.

Higgs Search History

Status of Standard Model Higgs Searches in Atlas
See: F. Gianotti, ATLAS talk at Latest update in the searchfor the Higgs boson at CERN, July 4, 2012.


 

 The recent discovery at the LHC by the CMS and ATLAS collaborations of the Higgs boson presents, at long last, direct probes of the mechanism for electroweak symmetry breaking. While it is clear from the observations that the new particle plays some role in this process, it is not yet apparent whether the couplings and widths of the observed particle match those predicted by the Standard Model. In this paper, we perform a global t of the Higgs results from the LHC and Tevatron. While these results could be subject to as-yet-unknown systematics, we nd that the data are signi cantly better t by a Higgs with a suppressed width to gluon-gluon and an enhanced width to, relative to the predictions of the Standard Model. After considering a variety of new physics scenarios which could potenially modify these widths, we nd that the most promising possibility is the addition of a new colored, charged particle, with a large coupling to the Higgs. Of particular interest is a light, and highly mixed, stop, which we show can provide the required alterations to the combination of gg and widths. See Are There Hints of Light Stops in Recent Higgs Search Results?

Majorana Particles in Computation


An artist's conception of the Majorana - a previously elusive subatomic particle whose existence has never been confirmed - until now. Dutch nano-scientists at the technological universities of Delft and Eindhoven, say they have found evidence of the particle. To find it, they devised miniscule circuitry around a microscopic wire in contact with a semiconductor and a superconductor. Lead researcher Leo Kouwenhoven. SOUNDBITE (English), NANOSCIENTIST OF DELFT UNIVERSITY, LEO KOUWENHOVEN, SAYING: "The samples that we use for measuring the Majorana fermions are really very small, you can see the holder of the sample, the sample is actually inside here and if you zoom in, you can actually see little wires and if you zoom in more, you see a very small nano-meter scale sample, where we detected one pair of Majoranas." When a magnetic field was applied along the the 'nanowire', electrons gathered together in synchrony as a Majorana particle. These subatomic particles could be used to encode information, turning them into data to be used inside a tiny, quantum computer. SOUNDBITE (English), NANOSCIENTIST OF DELFT UNIVERSITY, LEO KOUWENHOVEN, SAYING: "The goal is actually to develop those nano-scale devices into little circuits and actually make something like a quantum computer out of it, so they have special properties that could be very useful for computation, a particural kind of computation which we call quantum computation, which would replace actually our current computers by computers that are much more efficient than what we have now." The Majorana fermion's existence was first predicted 75 years ago by Italian Ettore Majorana. Probing the Majorana's particles could allow scientists to understand better the mysterious realm of quantum mechanics. Other groups working in solid state physics are thought to be close to making similar announcements....heralding a new era in super-powerful computer technology. Were he alive today Majorana may well be amazed at the sophisticated computer technology available to ordinary people in every day life. But compared to the revolution his particle may be about to spark, it will seem old fashioned in the not too distant future. Jim Drury, Reuters







Majorana fermion

Composition Elementary
Statistics Fermionic
Status Hypothetical
Antiparticle Itself
Theorised Ettore Majorana, 1937

A Majorana fermion is a fermion that is its own anti-particle. The term is sometimes used in opposition to Dirac fermion, which describes particles that differ from their antiparticles. It is common that bosons (such as the photon) are their own anti-particle. It is also quite common that fermions can be their own anti-particle, such as the fermionic quasiparticles in spin-singlet superconductors (where the quasiparticles/Majorana-fermions carry spin-1/2) and in superconductors with spin-orbital coupling, such as Ir, (where the quasiparticles/Majorana-fermions do not carry well defined spins).

Contents

 

Theory


The concept goes back to Ettore Majorana's 1937 suggestion[1] that neutral spin-1/2 particles can be described by a real wave equation (the Majorana equation), and would therefore be identical to their antiparticle (since the wave function of particle and antiparticle are related by complex conjugation).

The difference between Majorana fermions and Dirac fermions can be expressed mathematically in terms of the creation and annihilation operators of second quantization. The creation operator γj creates a fermion in quantum state j, while the annihilation operator γj annihilates it (or, equivalently, creates the corresponding antiparticle). For a Dirac fermion the operators γj and γj are distinct, while for a Majorana fermion they are identical.

 

Elementary particle


No elementary particle is known to be a Majorana fermion. However, the nature of the neutrino is not yet definitely settled; it might be a Majorana fermion or it might be a Dirac fermion. If it is a Majorana fermion, then neutrinoless double beta decay is possible; experiments are underway to search for this type of decay.
The hypothetical neutralino of supersymmetric models is a Majorana fermion.

 

Quasiparticle


In superconducting materials, Majorana fermions can emerge as (non-fundamental) quasiparticles.[2] (People also name protected zero-energy mode as Majorana fermion. The discussions in the rest of this article are actually about such protected zero-energy mode, which is quite different from the propagating particle introduced by Majorana.) The superconductor imposes electron hole symmetry on the quasiparticle excitations, relating the creation operator γ(E) at energy E to the annihilation operator γ(−E) at energy −E. At the Fermi level E=0, one has γ=γ so the excitation is a Majorana fermion. Since the Fermi level is in the middle of the superconducting gap, these are midgap states. A quantum vortex in certain superconductors or superfluids can trap midgap states, so this is one source of Majorana fermions.[3][4][5] Shockley states at the end points of superconducting wires or line defects are an alternative, purely electrical, source.[6] An altogether different source uses the fractional quantum Hall effect as a substitute for the superconductor.[7]

It was predicted that Majorana fermions in superconductors could be used as a building block for a (non-universal) topological quantum computer, in view of their non-Abelian anyonic statistics.[8]

 

Experiments in superconductivity


In 2008 Fu and Kane provided a groundbreaking development by theoretically predicting that Majorana fermions can appear at the interface between topological insulators and superconductors.[9][10] Many proposals of a similar spirit soon followed. An intense search to provide experimental evidence of Majorana fermions in superconductors[11][12] first produced some positive results in 2012.[13][14] A team from the Kavli Institute of Nanoscience at Delft University of Technology in the Netherlands reported an experiment involving indium antimonide nanowires connected to a circuit with a gold contact at one end and a slice of superconductor at the other. When exposed to a moderately strong magnetic field the apparatus showed a peak electrical conductance at zero voltage that is consistent with the formation of a pair of Majorana quasiparticles, one at either end of the region of the nanowire in contact with the superconductor.[15]

This experiment from Delft marks a possible verification of independent theoretical proposals from two groups[16][17] predicting the solid state manifestation of Majorana fermions in semiconducting wires.

It is important to note that the solid state manifestations of Majorana fermions are emergent low-energy localized modes of the system (quasiparticles) which are not fundamental new elementary particles as originally envisioned by Majorana (or as the neutrino would be if it turns out to be a Majorana fermion), but are effective linear combinations of half-electrons and half-holes which are topological anyonic objects obeying non-Abelian statistics.[8] The terminology "Majorana fermion" is thus not a good nomenclature for these solid state Majorana modes.

 

References

  1. ^ E. Majorana (1937). "Teoria simmetrica dell’elettrone e del positrone" (in Italian). Nuovo Cimento 14: 171. English translation.
  2. ^ F. Wilczek (2009). "Majorana returns". Nature Physics 5 (9): 614. Bibcode 2009NatPh...5..614W. DOI:10.1038/nphys1380.
  3. ^ N.B. Kopnin; Salomaa (1991). "Mutual friction in superfluid 3He: Effects of bound states in the vortex core". Physical Review B 44 (17): 9667. Bibcode 1991PhRvB..44.9667K. DOI:10.1103/PhysRevB.44.9667.
  4. ^ G.E. Volovik (1999). "Fermion zero modes on vortices in chiral superconductors". JETP Letters 70 (9): 609. Bibcode 1999JETPL..70..609V. DOI:10.1134/1.568223.
  5. ^ N. Read; Green (2000). "Paired states of fermions in two dimensions with breaking of parity and time-reversal symmetries and the fractional quantum Hall effect". Physical Review B 61 (15): 10267. Bibcode 2000PhRvB..6110267R. DOI:10.1103/PhysRevB.61.10267.
  6. ^ A. Yu. Kitaev (2001). "Unpaired Majorana fermions in quantum wires". Physics-Uspekhi (supplement) 44 (131): 131. Bibcode 2001PhyU...44..131K. DOI:10.1070/1063-7869/44/10S/S29.
  7. ^ G. Moore; Read (1991). "Nonabelions in the fractional quantum Hall effect". Nuclear Physics B 360 (2–3): 362. Bibcode 1991NuPhB.360..362M. DOI:10.1016/0550-3213(91)90407-O.
  8. ^ a b C. Nayak, S. Simon, A. Stern, M. Freedman, and S. Das Sarma (2008). "Non-Abelian anyons and topological quantum computation". Reviews of Modern Physics 80: 1083.
  9. ^ L. Fu; C. L. Kane (2008). "Superconducting Proximity Effect and Majorana Fermions at the Surface of a Topological Insulator". Physical Review Letters 10 (9): 096407. DOI:10.1103/PhysRevLett.100.096407.
  10. ^ L. Fu; C. L. Kane (2009). "Josephson current and noise at a superconductor/quantum-spin-Hall-insulator/superconductor junction". Physical Review B 79 (16): 161408. DOI:10.1103/PhysRevB.79.161408.
  11. ^ J. Alicea. New directions in the pursuit of Majorana fermions in solid state systems. arXiv:1202.1293.
  12. ^ C. W. J. Beenakker. Search for Majorana fermions in superconductors. arXiv:1112.1950.
  13. ^ E. S. Reich (28 February 2012). "Quest for quirky quantum particles may have struck gold". Nature News. DOI:10.1038/nature.2012.10124.
  14. ^ Jonathan Amos (13 April 2012). "Majorana particle glimpsed in lab". BBC News. Retrieved 15 April 2012.
  15. ^ V. Mourik; K. Zuo; S.M. Frolov; S.R. Plissard; E.P.A.M. Bakkers; L.P. Kouwenhoven (12 April 2012). "Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices". Science. arXiv:1204.2792. DOI:10.1126/science.1222360.
  16. ^ R. Lutchyn; J. Sau; S. Das Sarma (2010). "Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures". Physical Review Letters 105 (7): 077001. Bibcode 2010PhRvL.105g7001L. DOI:10.1103/PhysRevLett.105.077001.
  17. ^ Y. Oreg; G. Refael; F. von Oppen (2010). "Helical Liquids and Majorana Bound States in Quantum Wires". Physical Review Letters 105 (17): 177002. DOI:10.1103/PhysRevLett.105.177002.


The Majorana experiment will search for neutrinoless double-beta decay of 76Ge. The discovery of this process would imply that the neutrino is a Majorana fermion (its own anti-particle) and allow a measurement of the effective Majorana neutrino mass. The first stage of the experiment, the Majorana Demonstrator, will consist of 60kg of germanium crystal detectors in three cryostats. Half of these will be made from natural germanium and half from germanium enriched in 76Ge. The goals of the Demonstrator are to test a claim for measurement of neutrinoless double beta-decay by Klapdor-Kleingrothaus et al. (2006), to demonstrate a low enough background to justify the construction of a larger tonne-scale experiment, and to demonstrate the scalability of the technology to the tonne scale. The experiment will be located at the 4850 ft level of the Sanford Laboratory in Lead, South Dakota. See: The Majorana neutrinoless double beta-decay experiment





See Also: Sounding Off on the Dark Matter Issue

Friday, July 06, 2012

The Bolshoi simulation

A virtual world?

 The more complex the data base the more accurate one's simulation is achieved. The point is though that you have to capture scientific processes through calorimeter examinations just as you do in the LHC.

So these backdrops are processes in identifying particle examinations as they approach earth or are produced on earth. See Fermi and capture of thunder storms and one might of asked how Fermi's picture taking would have looked had they pointed it toward the Fukushima Daiichi nuclear disaster?

So the idea here is how you map particulates as a measure of natural processes? The virtual world lacks the depth of measure with which correlation can exist in the natural world? Why? Because it asks the designers of computation and memory to directly map the results of the experiments. So who designs the experiments to meet the data?

 How did they know the energy range that the Higg's Boson would be detected in?





The Bolshoi simulation is the most accurate cosmological simulation of the evolution of the large-scale structure of the universe yet made ("bolshoi" is the Russian word for "great" or "grand"). The first two of a series of research papers describing Bolshoi and its implications have been accepted for publication in the Astrophysical Journal. The first data release of Bolshoi outputs, including output from Bolshoi and also the BigBolshoi or MultiDark simulation of a volume 64 times bigger than Bolshoi, has just been made publicly available to the world's astronomers and astrophysicists. The starting point for Bolshoi was the best ground- and space-based observations, including NASA's long-running and highly successful WMAP Explorer mission that has been mapping the light of the Big Bang in the entire sky. One of the world's fastest supercomputers then calculated the evolution of a typical region of the universe a billion light years across.

The Bolshoi simulation took 6 million cpu hours to run on the Pleiades supercomputer—recently ranked as seventh fastest of the world's top 500 supercomputers—at NASA Ames Research Center. This visualization of dark matter is 1/1000 of the gigantic Bolshoi cosmological simulation, zooming in on a region centered on the dark matter halo of a very large cluster of galaxies.Chris Henze, NASA Ames Research Center-Introduction: The Bolshoi Simulation



Snapshot from the Bolshoi simulation at a red shift z=0 (meaning at the present time), showing filaments of dark matter along which galaxies are predicted to form.
CREDIT: Anatoly Klypin (New Mexico State University), Joel R. Primack (University of California, Santa Cruz), and Stefan Gottloeber (AIP, Germany).
 THREE “BOLSHOI” SUPERCOMPUTER SIMULATIONS OF THE EVOLUTION OF THE UNIVERSE ANNOUNCED BY AUTHORS FROM UNIVERSITY OF CALIFORNIA, NEW MEXICO STATE UNIVERSITY



Pleiades Supercomputer

 MOFFETT FIELD, Calif. – Scientists have generated the largest and most realistic cosmological simulations of the evolving universe to-date, thanks to NASA’s powerful Pleiades supercomputer. Using the "Bolshoi" simulation code, researchers hope to explain how galaxies and other very large structures in the universe changed since the Big Bang.

To complete the enormous Bolshoi simulation, which traces how largest galaxies and galaxy structures in the universe were formed billions of years ago, astrophysicists at New Mexico State University Las Cruces, New Mexico and the University of California High-Performance Astrocomputing Center (UC-HIPACC), Santa Cruz, Calif. ran their code on Pleiades for 18 days, consumed millions of hours of computer time, and generating enormous amounts of data. Pleiades is the seventh most powerful supercomputer in the world.

“NASA installs systems like Pleiades, that are able to run single jobs that span tens of thousands of processors, to facilitate scientific discovery,” said William Thigpen, systems and engineering branch chief in the NASA Advanced Supercomputing (NAS) Division at NASA's Ames Research Center.
See|:NASA Supercomputer Enables Largest Cosmological Simulations



See Also: Dark matter’s tendrils revealed

Wednesday, July 04, 2012

Darkside

Image credit: Yury Suvorov for the DarkSide collaboration
A leading candidate explanation, motivated by supersymmetry theory, is that dark matter is comprised of as yet undiscovered Weakly Interacting Massive Particles (WIMPs) formed in the early universe and subsequently gravitationally clustered in association with baryonic matter. WIMPs could in principle be detected in terrestrial experiments through their collisions with ordinary nuclei, giving observable low-energy (<100 keV) nuclear recoils. The predicted low collision rates require ultra-low background detectors with large (0.1–10 ton) target masses, located in deep underground sites to eliminate neutron background from cosmic ray muons.The Darkside of Gran Sasso
Also See: Cern Courier: The DarkSide of Gran Sasso

Higg's Boson: Analogies Help


John Ellis,theoretical physicist, answers the question "What is the Higgs boson?" in preparation for the press conference following the seminar on LHC 2012 results on the Higgs boson search, due on July 4 2012 at CERN. For more details: http://cern.ch/press/PressReleases/Releases2012/PR16.12E.html

See Also: What is the Higgs boson? John Ellis, theoretical physicist





webcast of seminar with ATLAS and CMS latest results from ICHEP




You know analogies are important in that they can bring a lay person some clarity in helping to understand what s going on in the world of science. As a blogger I have attach myself to some scientists who have been more then willing to share this aspect of them-self with the world. I do not know of a more honorable thing a scientist can do but by taking this time to help the public.

Tuesday, July 03, 2012

Methods to Discovery Real Science

 I guess in a sense one is looking for the best resource information they can in order to have the right data in front f them when they are trying to understand the science process. So that what this psst is about in looking at methods in order to make such information available.

Most certainly the number of citations any scientific paper written may have.


With all the resources they need in one place, Essential Science Indicators users can determine the influential individuals, institutions, papers, publications, and countries in their field of study — as well as emerging research areas that could impact their work.

This unique and comprehensive compilation of science performance statistics and science trends data is based on journal article publication counts and citation data from Thomson Scientific databases. It is an ideal analytical resource for policymakers, administrators, analysts and information specialists in government agencies, universities, corporations, private laboratories, publishing companies and foundations, as well as members of the scientific press and recruiters. Research Evaluation Tools






John Ellis with Dimitri Nanopoulos (left) and Keith Olive (right).


SW: What first drew your interest to the research area of supersymmetry?
 
I first got interested in the mid-1970s, stimulated by the early papers of Wess, Zumino, and others formulating supersymmetric field theories. But it was rather academic curiosity until various people (Maiani, Witten, etc.) realized around 1980 that supersymmetric particles weighing about a TeV could help stabilize the electroweak mass scale by making quantum corrections naturally small. 

Then in 1984, together with Hagelin, Nanopoulos, Olive, and Srednicki, we realized that the lightest supersymmetric particle would be a very natural candidate for cold dark matter and calculated its density in some detail (this paper now has over 1,000 citations in the SPIRES database; Ellis J, et al., "Supersymmetric relics from the Big Bang," Nuclear Physics B 238[2]: 453-76, 1984). John Ellis on the Symbiosis Between Particle Physics & Astrophysics


10 most recent papers released by the LHC Experiments.

1.
Search for new physics with long-lived particles decaying to photons and missing energy in pp collisions at sqrt(s) = 7 TeV
A search is performed for long-lived neutral particles decaying into a photon and invisible particles. [...]
CERN-PH-EP-2012-164 ; CMS-EXO-11-067-003.
- 2012.
Additional information for the analysis - CMS AuthorList - Fulltext - Full text
2.
Combined search for the Standard Model Higgs boson in pp collisions at $\sqrt{s}$ = 7 TeV with the ATLAS detector
A combined search for the Standard Model Higgs boson with the ATLAS detector at the LHC is presented. [...]
arXiv:1207.0319 ; CERN-PH-EP-2012-167.
- 2012. - 32 p.
Previous draft version - Preprint
3.
Search for the Standard Model Higgs boson produced in association with a vector boson and decaying to a b-quark pair with the ATLAS detector / ATLAS Collaboration
This Letter presents the results of a direct search with the ATLAS detector at the LHC for a Standard Model Higgs boson of mass $110 \le m_H \le 130$ GeV produced in association with a W or Z boson and decaying to $b\bar{b}$. [...]
arXiv:1207.0210 ; CERN-PH-EP-2012-138.
- 2012. - 30 p.
Previous draft version - Preprint
4.
Pion emission from the T2K replica target: method, results and application / Abgrall, N et al.,
The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. [...]
CERN-PH-EP-2012-188.- Geneva : CERN, 2012 - 35. Draft (restricted): PDF; Fulltext: PDF;
5.
New measurement of the charged kaon semileptonic (Ke4) decay Branching Ratio and Hadronic Form Factors / Batley, J R (Cambridge U.)
A sample of more than one million Ke4 decay candidates with less than one percent background contamination has been collected by the NA48/2 experiment at the CERN SPS in 2003-2004, allowing a detailed study of the decay properties. [...]
arXiv:1206.7065 ; CERN-PH-EP-2012-185.
- 2012. - 21 p.
Preprint
6.
Inclusive and differential measurements of the $t\bar{t}$ charge asymmetry in proton-proton collisions at $\sqrt{s}$ = 7 TeV / CMS Collaboration
The t t-bar charge asymmetry is measured in events containing a charged lepton (electron or muon) and at least four jets, one of which is identified as originating from b-quark hadronization. [...]
arXiv:1207.0065 ; CMS-TOP-11-030 ; CERN-PH-EP-2012-175.
- 2012. - 31 p.
Preprint
7.
Search for stopped long-lived particles produced in pp collisions at $\sqrt{s}$ =7 TeV / CMS Collaboration
A search has been performed for long-lived particles that have stopped in the CMS detector, during 7 TeV proton-proton operations of the CERN LHC. [...]
arXiv:1207.0106 ; CMS-EXO-11-020 ; CERN-PH-EP-2012-170.
- 2012. - 31 p.
Preprint
8.
Measurement of the Cross Section for High-p_T Hadron Production in Scattering of 160GeV/c Muons off Nucleons / Adolph, C. ; Alekseev, M.G. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; Alexeev, G.D. ; Amoroso, A. ; Antonov, A.A. ; Austregesilo, A. ; Badellek, B. ; Balestra, F. et al.
The cross section for production of charged hadrons with high transverse momenta in scattering of 160 GeV/c muons off nucleons at low photon virtualities has been measured at the COMPASS experiment at CERN. The results, which cover transverse momenta from 1.1 to 3.6 GeV/c, are compared to a next-to-leading order perturbative Quantum Chromodynamics (NLO pQCD) calculation in order to evaluate the applicability of pQCD to this process in the kinematic domain of the experiment. [...]
CERN-PH-EP-2012-189.- Geneva : CERN, 2012 - 9. Draft (restricted): PDF; Fulltext: PDF;
9.
Search for a light pseudoscalar Higgs boson in the dimuon decay channel in pp collisions at $\sqrt{s}$ = 7 TeV / CMS Collaboration
The dimuon invariant mass spectrum is searched in the range between 5.5 and 14 GeV for a light pseudoscalar Higgs boson "a", predicted in a number of new physics models, including the next-to-minimal supersymmetric standard model. [...]
arXiv:1206.6326 ; CMS-HIG-12-004 ; CERN-PH-EP-2012-176.
- 2012. - 27 p.
Preprint
10.
Search for the Standard Model Higgs boson in the $H \to \tau^+ \tau^-$ decay mode in $\sqrt{s}$ = 7 TeV pp collisions with ATLAS / ATLAS Collaboration
A search for the Standard Model Higgs boson decaying into a pair of tau leptons is reported. [...]
arXiv:1206.5971 ; CERN-PH-EP-2012-140.
- 2012. - 52 p.
Previous draft version - Preprint

Sunday, July 01, 2012

Nima Arkani-Hamed on Maximally Supersymmetric Theories

Could Nature, LHC prefer N=2 supersymmetry?

 SW: Can you explain to us some of the places where supersymmetry shows up in these various theories, and what it does for you when it does show up? 
 
Let me back up for one second here: Supersymmetry is an extension of the symmetries of space-time, and it has this really interesting character. On the one hand, supersymmetric theories are examples of ordinary quantum field theories. They’re not radically outside the framework of the rubric handed down to us by our ancestors by the 1930s. But on the other hand, while being ordinary quantum field theories, they have extraordinary properties; they extend the symmetries of space-time. And so they fit at a nexus between two worlds. Considering this deep, central idea, it’s not surprising that it’s going to show up in a host of places.
One of the places it shows up is in attempts to extend, very pragmatically, the standard model of particle physics and to solve a variety of its problems. So there are these famous fine-tuning problems and other difficulties we have, which can be summarized as attempts to understand the following major puzzle: Because of quantum fluctuations—violent vacuum fluctuations that get more and more violent as you go to shorter and shorter distances—it seems to be impossible to have any macroscopic order in the universe at all. The universe is big, gravity is weak; there is a very big macroscopic universe, but that seems almost impossible given that there are these gigantic quantum fluctuations.

Supersymmetry is one attempt to solve these problems by coming up with an explanation for why the quantum fluctuations disappear at short distances. This isn’t a small problem, a details thing. If you’re going to fix it, it’s going to need a big fix. The way supersymmetry does it is by extending the idea of space-time, and it does it in a way that you can’t fluctuate at all in these quantum dimensions. There’s a perfect symmetry between the quantum dimensions and the ordinary dimensions, and so the gigantic quantum fluctuations have to cancel out. That’s why it showed up and people care about it a lot in particle physics and in finding extensions of the standard model. 

It also shows up all over the place in string theory, because if you’re going to have a quantum mechanical theory of gravity, which is what string theory is about, one of the first things it should do is give you a nice big macroscopic universe to play with—even a toy universe. Any other attempt to talk about quantum gravity just fails at this starting point, because of exactly the same violent quantum fluctuation problem. So supersymmetry shows up because it allows us to get going and even talk about it. It also shows up for other reasons.

It turns out that just the structure of quantum field theories—how to calculate with them, and see what the consequences are—is very rich, very complicated, and difficult to calculate with. When the couplings between quarks and gluons get strong, it’s impossible to calculate anything analytically, and for a long time people had no idea how to make progress. Supersymmetric theories have so many theoretical properties that you can really make wonderfully significant progress studying the dynamics of quantum field theories. And you do it by studying them in their most supersymmetric aspect first.
See:Nima Arkani-Hamed on Maximally Supersymmetric Theories- ScienceWatch.com correspondent Gary Taubes.


See Also: