A postulated symmetry between bosonic and fermionic fields in quantum field theories and string theories.

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Sterile Neutrinos as Dark Matter

There has been recent activity by astrophysicists to determine whether a fourth flavor of neutrino, a sterile neutrino, exists. It would likely be more massive than electron, muon or tau neutrinos. ...
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1answer
389 views

Seiberg Witten theory

I'm currently reading the Seiberg-Witten paper on $N=2$ supersymmetric Yang Mills pure gauge theory (i.e. no hypermultiplets). I have the following question: How does one understand that the metric ...
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1answer
185 views

Why are the third generation superpartners lighter than the other sfermions in MSUGRA

In the MSUGRA breaking scenario, the stop particle typically appears at energies reachable at the LHC. Other sfermions, notably the partners of up, down, strange and charm are assumed to be degenerate ...
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1answer
730 views

Definition and difference between the R-symmetry and the $U(1)_R$ internal symmetry

For a general ${\cal N}$ the R-symmetry group is $U({\cal N})$ but for the ${\cal N}=2$ case why is it $SU(2)$ ? I guess it is again different for ${\cal N}=4$. How does one understand this? One ...
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2answers
472 views

Neutralino Dark Matter Detection

Assuming supersymmetry exists and a neutralino is stable, it's often seen as a leading dark matter candidate. What would be expected from the interaction of a neutralino and its anti-particle? Has ...
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1answer
432 views

BPS sectors in $\cal{N}=4$ SYM

I am familiar with the idea of a BPS bound as in a lower limit on the mass of supermultiplets given by a certain function of the central charge and when I think of $\cal{N}=4$ SYM I see a complicated ...
7
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1answer
229 views

Are non-supersymmetric GUTs ruled out due to lack of precise gauge coupling unification?

Does there exist any good proposal on how the gauge coupling unification can be fixed in non-supersymmetric GUTs? If not, can we assert that non-supersymmetric GUTs have been experimentally ruled out? ...
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1answer
376 views

The superconformal algebra

How does one derive the superconformal algebra? Especialy how to argue the existence of the operator $S$ which doesn't exist either in either the supersymmetric algebra or the conformal algebra? ...
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3answers
557 views

Is there a maximum number of types of elementary particles?

Doing a Google search i found a paper called The maximum number of elementary particles in a super symmetric extension of the standard model. It claims in the abstract that the upper bound is 84 (i ...
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1answer
130 views

Why is there more analysis of short multiplets compared to long multiplets?

In theories with extended supersymmetry, both short and long multiplets exist. For some reason or other, short multiplets are studied more often. Why? What's wrong with long multiplets?
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1answer
444 views

An unfamiliar way of writing supersymmetry transformations

This question is in relation to this recent paper. I would like to know how the so called supersymmetry transformations at the start of page 27 or at the end of page35 (equation 8.4) or at the end ...
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2answers
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What does “soft” in “soft symmetry breaking” mean?

For example it is stated that if supersymmetry breaking is soft then stability of gauge hierarchy can be still maintained.
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416 views

Decay of SUSY particles

In discussion of LHC searches for SUSY particles, physicists seem to assume they will decay quickly to the lightest SUSY particle which then remains stable (at least within the time it takes to leave ...
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1answer
443 views

Katz and Vafa's work on F-theory

I would like to know about the larger picture, current state and future prospects of the sequence of papers that were written by Sheldon Katz and Cumrun Vafa on F-theory. (Freddy Cachazo was also a ...
6
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2answers
413 views

Classifying all possible BPS configurations in string theory

Is there a classification of all possible BPS configurations in string theory? It has to include Calabi-Yau orbifolds, intersecting D-branes, coincident D-branes, etc. . To simplify matters, take the ...
2
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1answer
281 views

A particular notation about fermions

I am not sure that this notation is specific to supersymmetry theories but I ran into this while studying that. I see people talking of component fields of a chiral superfield as $\phi$ and ...
4
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2answers
222 views

Constructing the $\cal{N}=2$ supersymmetric non-Abelian Chern-Simon's theory

This is related to this earlier question I had asked. I am using the so called ``Majorana" representation of gamma matrices in $2+1$ dimensions in which everything is real. After doing the ...
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2answers
830 views

What if LHC finds SUSY?

Here and on many other forums and blogs people ask the question "What if LHC does not find SUSY?". I would like to ask the opposite. What if it finds it? What would the implications be? Is it going to ...
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1answer
324 views

Construction of the $\cal{N}=3$ supersymmetric Yang-Mills Chern-Simons theory in $2+1$ dimensions

I am stuck with understanding the following construction. I am breaking it up into segments which I think can be separately answered. This is related to an earlier question of mine. Note that this ...
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4answers
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What if the LHC doesn't see SUSY?

A question in four parts. What are the main problems which supersymmetry purports to solve? What would constitute lack of evidence for SUSY at the proposed LHC energy scales (e.g. certain predicted ...
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1answer
291 views

$B\mu$ from $\tan\beta$ and $\mu$

I'm using the SOFTSUSY package to generate the sparticle spectrum at the EW scale. One of the input parameters is the ratio of the up and down-type Higgs vevs commonly known as $\tan\beta$. The $\mu$ ...
4
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1answer
709 views

Dimensional reduction from $3+1$ to $2+1$ for $\cal{N}=2$ vector superfield

Let the supersymmetry transformations for the chiral multiplet $(z_k,\psi_{kL},f_k)$ be, $\delta z_k = 2i \bar{\alpha} \psi_{kL}$ $\delta \psi_{kL} = D_\mu z_k \gamma ^\mu \alpha_R + f_k \alpha_L$ ...
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1answer
326 views

How do ideas of leading singularities and Grassmanian help in curing infrared divergences when calculating N=4 scattering amplitudes?

Broadly speaking how do ideas of leading singularities and Grassmanian help in curing infrared divergences when calculating N=4 scattering amplitudes? My understanding is that one gets infra red ...
6
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3answers
472 views

Is holomorphy the real reason for nonrenormalization in supersymmetry?

Seiberg traced the nonrenormalization of supersymmetric theories to holomorphy of the superpotential in chiral superspace. However, this overlooks the fact that with a different number of ...
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0answers
174 views

A particular supersymmetry transformation

While reading a paper I ran into this particular way of writing a $\cal{N}=3$ fields (in a theory with $N_f$ hypermultiplets) that I couldn't relate to anything I had seen before in the text-books ...
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2answers
225 views

How do you derive Noether's theorem when the action combines chiral, antichiral, and full superspace?

How do you derive Noether's theorem when the action combines chiral, antichiral, and full superspace?
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2answers
557 views

Supersymmetry algebra

Let the $i=x,y,z$ components of the angular momentum have the commutation relations with the supersymmetry generators (also called supercharges?) $Q_a$ ($a = \pm \frac{1}{2}$) as, $[J_i , Q_a] = ...
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1answer
171 views

Would it be worthwhile to work out a manifestly supersymmetric superspace formalism for 16 and 32 real SUSY generators?

For 4 real SUSY generators, the superspace formalism has been worked out a long time ago. For 8 real SUSY generators, some brilliant theoreticians have worked out the details of harmonic superspace. ...
4
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1answer
518 views

Supersymmetry breaking and Goldstino

I would be glad if someone can explain to me the argument as to why supersymmetry breaking is necessarily accompanied by appearance of a massless fermion, namely the goldstino. (and also why this is a ...
12
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0answers
227 views

Is there any way to distinguish experimentally gauge mediation from gravity mediation in an unambiguous way?

There are lots of models of gravity mediated SUSY breaking with various spectra as well as various general gauge mediation models. Are there any "smoking gun" experimental singnatures that could ...
2
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1answer
188 views

Vanishing of field strength in gauged WZW model

Consider gWZW action $S_{gWZW}(g,A)=S_{WZW}(g)+S_{gauge}(g,A)$, where $S_{WZW}$ is usual WZW action being sum of sigma model and WZ terms for field $g$ taking values in group $G$ and $S_{gauge}=\int ...
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2answers
575 views

Superconformal algebra

I had earlier also asked a question about super conformal theories and I am continuing with that, now with more specific examples. I am quite puzzled with it given that I see no book explaining even ...
8
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1answer
1k views

$N=4$ supersymmetric yang-mills theory and S-duality

[Question suggested by @Lawrence B. Crowell's answer to the question on T-duality] There are three parts to my question: A. What is the action for $N=4$ SUSY Yang-Mills and what is the physics of ...
7
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2answers
1k views

Can someone give a simple expose on Coleman Mandula theorem and what Mandelstam variables are?

Can someone give a simple expose on Coleman Mandula theorem and what Mandelstam variables are? Coleman-Mandula is often cited as being the key theorem that leads us to consider Supersymmetry for ...