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

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368 views

Supersymmetric Noether theorem and supercurrents — invariance requirements

Consider $\mathcal{N}=1,d=4$ SUSY with $n$ chiral superfields $\Phi^i,$ Kaehler potential $K,$ superpotential $W$ and action ($\overline{\Phi}_i$ is complex conjugate of $\Phi^i$) $$ S= \int d^4x \...
4
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1answer
215 views

Why does in string theory the amount of supersymmetry have to be $\cal{N} \leq 2 $?

Why is this, that in string theory the maximum amount of supersymmetry is $\cal{N} = 2$, whereas in supergravity one can have up to $\cal{N} = 8$ ?
8
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3answers
979 views

What is kappa symmetry?

On page 180 David McMohan explains that to obtain a (spacetime) supersymmetric action for a GS superstring one has to add to the bosonic part $$ S_B = -\frac{1}{2\pi}\int d^2 \sigma \sqrt{h}h^{\alpha\...
8
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1answer
595 views

Supersymmetry calculations using computer algebra

Already the early papers on supergravity were written using computer algebra software to do some calculations. What modern packages do people normally use for doing such calculations? Of course ...
5
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0answers
182 views

What is the fundamental difference between ghost and auxiliary fields?

I am somehow confused by the notion of auxiliary fields, such as for example the fields $F$ and $D$ which appear in supersymmetry, and the notion of ghost fields which appear for example in the BRST ...
6
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1answer
185 views

Strange Grassmann double integration

I can unterstand why because the integration over Grassman variables has to be translational invariant too, one has $$ \int d\theta = 0 $$ and $$ \int d\theta \theta = 1 $$ but I dont see where ...
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139 views

References for Understanding Minahan's N=4 SCFT review

This is about the same paper as this thread: Some questions about chapter I.1 (by Minahan) of the "Review of AdS/CFT Integrability" but it was never answered. I have some different ...
4
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1answer
316 views

How to determine R charge?

Ref. 1, page 15, equation (23) defines the $U(1)_V$ and $U(1)_A$ actions as $$e^{i\alpha F_V}: \Phi(x,\theta^{\pm},\bar{\theta}^{\pm}) \rightarrow e^{i\alpha q_V}: \Phi(x,e^{-i\alpha }\theta^{\pm},e^{...
3
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1answer
132 views

How to determine predicted CP violation for a given SUSY point?

I'm currently studying at the spectra of some supersymmetric models, and would like to know whether the parameter points I'm looking at are ruled out due to excessive CP violation. I am using SPheno, ...
0
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1answer
153 views

Is there a relation between supersymmetry and entropy?

Considering that entropy denotes the level of order/disorder in a system, would it be possible for entropy and supersymmetry to exist at the same time? Or, are they entirely unrelated?
4
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1answer
189 views

Soft Mass and Physical Mass in Softly-broken SUSY

In softly broken SUSY, the bare mass parameters may be specified at e.g. the GUT scale, and then we can run these down to another scale using RGEs, similar in form to the RGEs for gauge couplings, ...
5
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1answer
175 views

Geometric interpretation of hidden SUSY

Hidden supersymmetry, which is the classical(non-super) symmetry in the form of susy, acting on a non-Grassmann space (e.g., Grassmann space is $(t,x,\theta,\bar{\theta})$, corresponding non-...
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192 views

Does anybody know of any good sources that explain (generically) how we form Lagrangians/Actions/Superpotentials for different field content?

I regularly find that I'll understand where the field content in a particular physics paper comes from, but then a Lagrangian or action or superpotential is stated and I don't know how it's derived. ...
6
votes
1answer
143 views

WIMPs and Gravitinos

I was just wandering if a gravitino could be in the WIMP class, because they are both massive (admittedly WIMP's more so) and are both weakly interacting and predicted by R-parity. i.e Gravitinos are ...
2
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0answers
96 views

What are the implications if Supersting theory is discredited? [duplicate]

Please forgive my ignorance, I am not a student of physics in any capacity, therefor my understanding of string theory is extremely limited to say the least. Based on the recent lack of evidence in ...
4
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1answer
332 views

Tangent bundles and $\mathbb{C}P^n$ and $\mathbb{C}^n$

As discussed here the complex projective space $\mathbb{C}P^n$ is the set of all lines on $\mathbb{C}^n$ passing through the origin. It would seem natural to assume that any $\mathbb{C}P^n$ can be ...
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0answers
104 views

A puzzle from 'The origin of the hidden supersymmetry'

In the paper arXiv:1004.5489 The origin of the hidden supersymmetry, the author use {Qa,Qa}={Qb,Qb}=2H, {Qa,Qb}=0 for N=2 hidden SUSY, which is different from what I was taught: {Qa,Qa}={Qb,Qb}=0, {Qa,...
2
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1answer
123 views

Hamiltonian in SUSY (SUSY algebra)

I was reading the book Supersymmetry, Theory, Experiment and Cosmology by P. Binétruy, and on page 25 the author goes from $$ 1)[Q_r,Q_t]_+ \gamma^{0}_{ts}=2\gamma^{\mu}_{rs}P_{\mu} $$ $$ 2)\mbox{...
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1answer
252 views

Differences between Goldstone bosons and fermions

I have been looking into basic SUSY and SUGRA theory and have a question relating to Goldstinos (particles giving gravitinos mass). Simply are these analogous to Goldstone bosons produced in the ...
6
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0answers
110 views

sigma model on $S^1 \times S^3$

In arXiv:1207.3497 - 4D partition function on $S^1 \times S^3$ and 2D Yang-Mills with nonzero area, Yuji Tachikawa explains the partition function for an 4d $\mathcal{N}=2$ sigma model on $S^3 \times ...
29
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3answers
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What is the current status of string theory (2013)?

I've seen a bunch of articles talking about how new findings from the LHC seem to disprove (super)string theory and/or supersymmetry, or at least force physicists to reformulate them and change ...
2
votes
1answer
113 views

Induce a Fayet-Iliopoulos term

In a supersymmetric U(1) gauge theory, if I leave off the Fayet-Iliopoulos term $\kappa [V]_D$, what keeps it from being induced in loop corrections?
5
votes
1answer
128 views

CP-violation in SUSY QED?

I have just gone through the exercise of constructing the supersymmetrized QED action. In the end, I get a reasonable action which matches literature. But after a little analysis, I find that the ...
7
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0answers
153 views

How to perform contour integral in Nekrasov's formula

My question is technical. It is about instanton counting calculation (see this paper). The partition function of SU(N) gauge theory with $N_f$ fundamental multiplets in k instanton background is ...
4
votes
3answers
689 views

Mathematically: What is SUSY?

Wikipedia says: In particle physics, supersymmetry (often abbreviated SUSY) is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and ...
3
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1answer
225 views

Supersymmetric Sigma Model

I was working through the Mirror Symmetry book by Clay Math Institute. It deals with supersymmetric sigma model in 10.4 section. It doesn't derive how the action is invariant under the variation. I am ...
10
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1answer
496 views

About defining “baryons” and “mesons”

I want to understand the proof of the claims (of the construction as well as of its uniqueness) of gauge singlet states given around equation 2.13 (page 10) of this paper. Also does the listing of ...
7
votes
1answer
397 views

Canonical quantization in supersymmetric quantum mechanics

Suppose you have a theory of maps $\phi: {\cal T} \to M$ with $M$ some Riemannian manifold, Lagrangian $$L~=~ \frac12 g_{ij}\dot\phi^i\dot\phi^j + \frac{i}{2}g_{ij}(\overline{\psi}^i D_t\psi^j-D_t\...
1
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1answer
192 views

Divergence in Supergravity

I'm not familiar with supergravity so here's my question: I've heard in talks that if one finds divergence for five-loop 4-graviton scattering amplitudes in five dimensions this translates to a ...
3
votes
0answers
179 views

Can mass dimension of a field be viewed as another 'quantum number'?

While studying SUSY in 4D, I noticed the dynamical chiral superfield has dimension [GeV], whereas the dynamical vector superfield (for gauge theories) is unitless. Because I was introduced to the ...
5
votes
0answers
121 views

Are irrelevant terms in the Kahler potential always irrelevant, even at strong coupling?

I've been reading about the duality cascade in Strassler's TASI '03 lectures (hep-th/0505153). He reminds us of the non-renormalization theorem theorem for the superpotential so that the beta ...
5
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1answer
210 views

Why does unbroken supersymmetry imply the absence of tachyons?

Just a quick question, same as in the title. I'm trying to understand stable D-branes.
2
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1answer
203 views

Construction of the supersymmetric Faraday tensor

When I first learned gauge theories in my introductory quantum field theory course, I was taught that the Faraday (field-strength) tensor can be constructed by computing the commutator of the gauge-...
4
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1answer
175 views

$U(1)$ beta function of low energy effective Seiberg-Witten theory

My question is about figure3 (page 8) of this paper hep-th/9705131. Start from Seiberg-Witten theory, integrate out the charged high energy modes down to Higgs scale and we get a $U(1)$ gauge theory ...
11
votes
1answer
566 views

Auxiliary fields in supersymmetry

I know that auxiliary fields can be used to close the supersymmetry algebra in case the bosonic and fermionic on-shell degrees of freedom do not match. Could somebody please elaborate on this concept ...
4
votes
2answers
174 views

What constitutes a 'reliable' instanton calculation?

In Modern Supersymmetry, John Terning, on pgs 151, and 153 performs a so called 'reliable' instanton calculation when dealing with the ADS superpotential 'since the gauge group is completely broken'. ...
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2answers
747 views

How exactly do superstrings reduce the number of dimensions in bosonic string theory from 26 to 10 and remove the tachyons?

In bosonic string theory, to obtain the photon as the first excited state, the ground state must have a negative mass (tachyon). By applying $1 + 2 + 3 + \cdots = -1/12$, it can be shown (in a ...
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1answer
593 views

What are “hidden valley sectors”?

In this end of the year article, Prof. Strassler mentioned that hidden valley sectors could lead to some still open loopholes concerning the experimental discovery of supersymmetry and other BSM ...
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0answers
52 views

Linear combination of anomalous dimensions in effective potential on pseudomoduli space

In the paper of Intriligator, Seiberg, and Shih from 2007, they give an expression for the effective potential on the pseudo-moduli space $X$, estimated at large $X$ (equation 1.3). In this equation, ...
4
votes
1answer
189 views

How to handle Yukawa contractions in calculating SUSY beta functions?

I'm reading Chapter 6 of Martin's introduction to SUSY http://arxiv.org/abs/hepph/9709356, which is about RGEs in the MSSM. I tried to convince myself of some of the calculations, and I was ...
3
votes
1answer
391 views

What is non-Abelian about non-Abelian Chern-Simons' theory?

One is aware that in the axial gauge (say the light-cone gauge $A_{-}=0$) non-supersymmetric Chern-Simons' theory is a quadratic theory. Hence in this gauge there are no gauge-gauge interactions. Then ...
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52 views

Conservation laws in mSUGRA model

Can somebody list all the quantum numbers (beside R-parity) that are conserved in vertex for SUSY particles in mSUGRA model?
11
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1answer
391 views

Witten's constrained S-matrix and Coleman-Mandula Theorem

I remember reading somewhere that Witten argued that if the Poincaré symmetry of spacetime were nontrivially combined with internal symmetries, then the S-matrix would be so constrained that the ...
3
votes
0answers
68 views

Can the mass of a SUSY particle depend on the process it participates in?

I believe that mass is property of every particle,as well as spin etc.Now I'm interested in SUSY particles in cMSSM model.Can it be,that mass of a SUSY particle (at one point in five parameter space) ...
5
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1answer
202 views

Mass of a superstring between two branes?

A open bosonic string between two parallel branes seems to obey formulae such as $M^2 = \big((n + {\theta_i - \theta_j \over 2 \pi}) {R' \over \alpha'}\big)^2 + {N-1 \over \alpha'} $ So that the ...
5
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1answer
102 views

Low-scale supersymmetry

One of the major reasons SUSY was adopted in particle physics is to Naturally have a Higgs boson (a fundamental scalar) at the weak scale. If we abandon this argument, what other motivation for low-...
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1answer
704 views

why are two higgs doublets required in SUSY?

I can't really understand why two higgs doublets are required in SUSY. From the literature, I have found opaque explanations that say something along the lines of: the superpotential W must be a ...
3
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1answer
323 views

It seems to me that superpotentials can be defined in a theory with or without supersymmetry. Is this true?

I recently read "An Introduction to Supersymmetry in Quantum Mechanical Systems" by T. Wellman (amongst other sources) in an effort to find out what a superpotential actually is and how it relates to ...
2
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1answer
202 views

Other Gross-Neveu like theories?

By "Gross-Neveu like" I mean non-supersymmetric QFTs whose partition function/beta-function (or any n-point function) is somehow exactly solvable in the large $N_c$ or $N_f$ or 't Hooft limit. (.....
6
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1answer
298 views

SUSY, ways to boost Chargino/Neutralino production?

Does anybody know a good reference that works out the equations for the Chargino/Neutralino production cross section in SUSY? I'm trying to understand if there are any tricks for boosting the ...