What is Susy: Definition and 115 Discussions

Last year I was studying supersymmetry and since them I'm regularly thinking to one question for which I don't have answer: when one looks at the susy algebra with N generators, one sees that there is a U(N) R-symmetry. But for N=4, the group is in fact SU(4). To explain this, one generally...

I've been studying, just for pleasure, but studying in the end, a lot about QFT and its prerrequisites reaching some not so bad understanding of the Standard Model. I know that I still have to fill a lot of gaps, but nevertheless, I am looking for some new topic to start reading (while I fill...

Is SUSY theory "necessary" at this point? I have a question: http://www.scientificamerican.com/article.cfm?id=beautiful-theory-collides Based on the presumed energy state of the newly found Higgs Boson, is SUSY theory even necessary or beneficial in terms of explaining particle physics...

When building the massless supermultiplets in N=1 supersymmetry one needs to add the CPT conjugate states to render the theory CPT invariant. My question is, what do they mean by "CPT-conjugate"? Is it just the state with opposite helicity? Is it the state with opposite C, P and T? Or is it...

Hi, I have a question about non-relativistic SUSY, see e.g. "non-relativistic SUSY" by Clark and Love. The supersymmetric Galilei algebra with central extension M can easily be obtained from the N=1 Super Poincaré algebra by an Inonu-Wigner contraction. In this proces, SUSY and spacetime...

Hi, I was going through the concept of R parity in SUSY. In the case of SUSY we do not have Baryon and Lepton number conservation instead we have R parity conservation defined by, R-parity= (-1)^2s+3B+L which is required for the proton to be stable. But it has been found that...

Hello, How could SUSY provides a candidate to dark matter since it would only appear only above the TeV scale? The galaxies' environments is at such energies? Thanks

Point is, Huerta and Baez, building upon the shoulders of M-theoretists, show us that susy is more relevant that just a trick to move the dimension of string theory. And Bott periodicity in Connes models did the same hint. Still, it seems that besides sugra, no model of space time has been able...

Well, all of this is theoretical, but I asked myself this because I never heard about antimatter in a SUSY particle context.

Hi guys, I'm under the impression that nowadays everything going on in hep-th is N=4 Susy stuff and that it has 20384093 awesome properties. Are there lecture notes where I can learn about all of that? I mean I know buzzwords but I don't see the whole picture. So, as I've said, are there...

Hi, Could you pls advise me any textbooks or papers where I can find pedagogical introduction to N=2 Supersymmetry & familiarize myself... Thank you very much Best Regards

I'm a little confused about the relaionship between susy transformations involving Q generators & gso projection in superstring theory. If gso projection is used in RNS sectors, does that only eliminate certain states, such as tachyon, then susy must still be applied? Or does gso projection...

This may seem like a naive question to some people. I had always heard that Lqg can easily incorporate supersymmetry---that if there were any evidence of it, putting it into the theory would be straightforward. This goes way back, to papers I read in 2003-2005. Not sure exactly which, but it...

I am recently reading the articles "Search for squarks and gluinos using final states with jets and missing transverse momentum with the ATLAS detector in sqrt s=7 TeV proton-proton collisions". However, as my limited knowledge, many technical terms that I am understanding as a result I am now...

Im having a little bit of trouble with SuperSymmerty. I understand all the basics with the sparticles and gauginos being -1/2 less and how their properties change to boson-like and fermion-like respectively. What i don't understand is how do the interact exactly. i know none have been found in...

In post #549 here I answered: And then I was surprised by the comment of Tom, asking how the pairing was done. Well, I thought that I had discussed it in some thread in BSM, but after looking at it, it seems that I did only a few sparse remarks here and there. On other hand, people was not...

For example, the right-handed sneutrino. It can decay into both (s)leptons and anti-(s)leptons, so it is also the anti-particle of itself. I wonder how it looks like mathematically. If it is the same as normal scalar field, we can still distinguish its anti-particle (the complex conjugate)...

Hi, I have a conceptual problem in understanding the SUSY (N=1) massless supermultiplet. Using appropriately normalized creation and annihilation operators Q, Q+ (only one component survives in this representation) we have for the quark state: Q+|p,-1/2>=0 (quark) where the 1/2 labels the...

Hi, accounting for the new LHC results, e.g. Search for squarks and gluinos ... Search for supersymmetry... Search for Supersymmetry in pp Collisions... it seems that SUSY is becoming problems. I guess that there are reasons why the masses of the supersymmetric particles cannot be...

I followed a book on SUSY where the SUSY Casimir operator, modified from the Pauli-Lubanski vector, is stated and then proven to commute with all SUSY generators. However, I'm wondering whether there's a systematic approach of deriving the Casimir operator, other than trial-and-error? Is there a...

Supposed we are given a set of SUSY transformation law, the way to get the BPS equation is by requiring that \delta \psi = 0 where \psi is a fermion field. Could somebody explain why this is the BPS equation? Thanks!

reading the light-heart book of Aitchison, "an informal intro...", we see that the problem with mass terms in the electroweak bosons is not that they spoil gauge invariance, but that they spoil gauge invariance in a way that it is not recovered when their mass goes to zero. After one has been...

Hi N=1 supersymmetric gauge theories usually have moduli spaces of vacua that are parametrized by vacuum expectation values of the scalar components of chiral superfieds. Often these are lifted quantum mechanically due to non-perturbative effects. For example in the lectures hep-th/9509066...

In this paper*, Brian Greene just asserts that: "In order to contribute nine to the central charge, the dimension of M must be six, and to ensure the additional condition of N = 2 supersymmetry, M must be a complex Kahler manifold." Is there some paper that discusses the relationship...

Hello all. Again, thank you for the help so far. Forgive the lack of tex in this post, it somehow was creating errors no matter what I tried. My question this time involves understanding the F and D terms in SUSY theories. From what I understood, they were introduced as auxiliary fields (EOM...

So, I've been tasked to learn SUSY in a small time span (few weeks) and I've made some progress but I'm a little stumped on how deeply I should go into things while still making reasonable progress (get to phenomenology, etc). First of all, most primers seem to gloss over the algebra or go...

Last week I was watching events at the LHC at this screen: http://lhc.web.cern.ch/lhc/ when something happened and there was a shutdown. In the “Comments” section at lower screen right, someone had entered “UFINO?” as a possible explanation for the shutdown. Is this shorthand for unidentified...

Hi, I'm currently reading "Supersymmetry demystifed" by Patrick Labelle, chapter 10, about SUSY non-Abelian gauge theories. We have a Lagrangian with SU(N)-gauge fields, and gaugino's. What puzzles me are the following claims of Labelle about the representations. In the...

LHC thus far has ruled out some of the SUSY parameter space over and above Tev, esp gluinos above a certain mass. So LHC has offered some useful research into SUSY. Were SUSY gluinos detected it would be a huge boost to strings/Supergravity Beyond the Standard Model...

The neutralino is the lightest supersymmetric stable particle, and is a good dark matter candidate. Some theories like MSSM predicts the LHC has enough energy to produce neutralinos, which can be indirectly detected by missing energy in collisions. Neutralinos are predicted to be abundant and...

One argument in favor of SUSY is that without SUSY, the running gauge coupling unification do not meet for the three forces, but with SUSY they meet around 10^15 GEV. This implies that gauge coupling most meet for GUT to be viable. So without SUSY, the running gauge couplings do not meet. If...

I am sorry if the question is naive. In N=1 SUSY, for every boson we have a fermionic partner (and an auxilliary field) and vice-versa. When N>1 how many superpartners do we have given a boson (or a fermion)? Is it N?

When N=1, is the superspace formulation of 10D SYM the same as the 4D SYM, except the differences of the coefficient and gamma matrices? For the extended SUSY in 10D, are the superspace formulation available for N=2, 4? How about N=8, 16, and 32? Thanks for any tips you may tell me.

Thus far Tevatron has not detected any multiple higgs bosons or any SUSY particles. If SUSY is the correct explanation for Higgs stabilization, given both the amount of data and energies reached, does this present a problem (i.e makes more unlikely) SUSY as an explanation for Higgs...

I'm currently doing a third year project (undergraduate) on supersymmetry, and am slightly confused as to just how the Higgs naturalness problem is solved through adding superparticles to the standard model. I've been advised to include discussion of radiative corrections, which, at most, all i...

I am not talking about superstrings, but the idea of supersymmetry itself. Let me say what annoys me. I will put aside the advantages of it satisfying Coleman-Mandula theorem or solving the instabilities of the Higgs field, lorentz invariance or any other consistency that it satisfies in...

If SUSY is a candidate theory of nature, it must not allow for Flavor changing neutral current in disagreement with observation. Is there a viable mechanism in low-energy EW-stabilizing broken SUSY that prohibits Flavor changing neutral current?

SUSY, (SUSY-MSSM, SUSY-GR, M-theory) doubles the number of particles in the SM, but what about SUSY partners for mesons like pions?

Hi, I'm reading Bilal's notes on SUSY, hep-th/0101055v1, and have some computational questions. So I understand that spinors can be seen as objects carrying the basis rep. of SL(2,C), and how SO(3,1) is locally isomorphic to SU(2)XSU(2), giving basically two "sectors". With dots and bars we...

If you have doublet Q=(u,d) , and want to give the u-quark mass, you have to connect it to the Higgs VEV H=(\nu,0) doublet through the adjoint opertion: H^{\dagger i}Q_i Connecting H and Q through the Levi-Civita symbol e_{ij} : e^{ji} H_{ i}Q_j results in d-quark mass, not u-quark...

Homework Statement I am giving a short talk on supersymmetry for my intro to high energy class, but I do not have the time to read an entire book on the subject. Most resources I have found go into much more depth than I need, but these seem to be the only resources. Can anyone help me with...

How to solve the Free Parameter Problem in SUSY ?? In Standard Model, we have 19 free parameters: me Electron mass 511 keV mμ Muon mass 106 MeV mτ Tauon mass 1.78 GeV mu Up quark mass () 1.9 MeV md Down quark mass () 4.4 MeV ms Strange quark mass () 87 MeV mc Charm quark mass...

Hello I need a lot of exercises and problems on SUSY (supersymmetry). Do you know any good (and complete!) website where to find them? My teacher in the phD only gives us theory. Thanks!

This is surely a stupid question but here it goes... An auxiliary field is needed in the Wess-Zumino Lagrangian in order to have the algebra close off-shell. I have a couple of questions about this but let me ask the first one only for now. Why is this required? The variation of the...

Hello once again. I'm trying to understand the relation between the superspace representation of the SUSY generators Q_\alpha,\overline Q_{\dot\beta} and the covariant derivatives on superspaces D_\alpha, \overline D_{\dot\beta}: Q_\alpha = \frac{\partial}{\partial\theta^\alpha} -...

N=1 susy with massive supermultiplets; therefore we have two pairs of raising/lowering operators. Define a1 dagger as raising j3 by half and a2 dagger as lowering j3 by half. Take vacuum state with j, j3 where j3 has 2J+1 possible values. If we act with just a1 dagger we get superposition of...

Hi guys, I am doing a dissertation on one of these topics and wondered if anyone knows of some good books that may be good to start out from. Especially if the books focus on the particle physics aspects of these topics. So any books for CP violation and the imbalance of antimatter to...

Hi: I've heard that Susy is a central prediction of string theory, is that true?, and if that is true, does that mean that if susy isn't found, then string theory will be wrong? Thanks

N=1 SUSY (massless) multiplets contain two particles with helicities differering by half a unit . So one possible multiplet contains j=-1/2 and j=0. That corresponds to a left-handed spinor and a complex scalar so that's the chiral multiplet. Another possibility is j=-1 and j=-1/2...

I am struggleing in an identity, i.e. \nabla_m R_{ikjl}(\overline{\epsilon}\psi^m)(\overline{\psi^i}\psi^j)(\overline{\psi^k}\psi^l)=0 , where i,j,k,l,m are dummy indices, \nabla_m is covariant derivative, R_{ikjl} is Riemann-Christoffel curvature tensor, and it is known that, for any two...