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

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98 views

Why do we need frame-fields to describe fermions in SUGRA?

I'm learning about the frame formalism and read that to couple fermions to gravity you need to go to the frame-formalism. As a motivation to learn more about frame-fields would someone sketch me why ...
3
votes
1answer
86 views

Understanding the $\mu$ problem

I am going through the motivation to introduce singlet extensions of the MSSM (like for instance the NMSSM), and of course such a motivation is naturalness. Here, one argues that the $\mu$ parameter ...
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0answers
51 views

SUSY condition on string theory

In each string theory, there is some condition so called SUSY condition. I want to know susy condition for Type I, Type II, and Heterotic string. Can anyone give some brief explanation about this?...
3
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1answer
322 views

Treating the spinors as Grassmann numbers or as c-number objects

In the literature on supersymmetry, the following spinor summation convention is often used (eg. Wess & Bagger's book Supersymmetry and Supergravity) $$ \psi\chi = \psi^{\alpha}\chi_{\alpha} = -\...
3
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0answers
54 views

Spin of an operator in supersymmetric theories

How exactly is the spin of an operator in the context of a supersymmetric theory defined? For example, in page 25 of [1], $\mathcal{N} = 2$ supersymmetry is defined to have operators $J, G^{+}, G^{-}, ...
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173 views

Killing spinor equation [closed]

The Supersymmetry transformation is: $$\delta \psi_\mu^i=(\partial_\mu +1/4 \gamma^{ab}\omega_{\mu ab})\epsilon^i -1/8\sqrt{2}\kappa \gamma^{ab}F_{ab}\epsilon^{ij} \gamma_\mu \epsilon_j$$ For the ...
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0answers
121 views

Evaluation of the anomalous dimensions of fields in SUSY $SU(5)$

The general formula for the anomalous dimension can be found in Martin΄s review article (hep-ph/9709356), on page 62 relation (6.5.4). In the case of $SU(5)$ and especially in the paper of Kobayashi, ...
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1answer
189 views

Explanation for the minus sign in $\Omega_3$ in the Kappa symmetry of the Green - Schwarz formalism for F1 strings

Just so that there can be more higher - level physics questions here, let me post this question + answer. Also because I'm a bit sad that there are almost no questions on the Green-Schwarz formalism....
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0answers
184 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 ...
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0answers
94 views

Heterotic Supersymmetric derivation of an integrality theorem for differentiable manifolds [closed]

Please consider the following integrality theorem for differentiable manifolds due to K H Mayer: I am trying to prove this theorem using Heterotic Super-symmetric Quantum Mechanics described by a ...
3
votes
1answer
316 views

Susy QM and Atiyah-Singer index theorem

Consider maps $t\mapsto x^i(t)$ from circle to some Riemannian (spin) manifold and lagrangian $$ \mathcal L = \frac12 g_{ij}(x) \partial_t x^i \partial_t x^j + \frac12 g_{ij} \psi^j \left(\delta^i_k \...
3
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1answer
84 views

Dirac operator partial integration

When you have an action with bosonic $X$ and fermionic $\psi$ (Majorana) fields and perform a SUSY transformation $\epsilon$ (the constant, infinitesimal parameter of transformation, a real, ...
5
votes
2answers
172 views

Why doesn't $h\rightarrow \gamma\gamma$ rule out two higgs doublet models?

In two higgs doublet models we introduce a down-type Higgs as well as an up type Higgs and typically (as I understand it) we take the down-type to be the 126 GeV resonance and the up type to be ...
4
votes
3answers
700 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 ...
2
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0answers
39 views

Why do electrons form Cooper pairs below certain temperature? [duplicate]

Just a heads up - please make this answer understandable to around 1st year degree level physics - not PhD research. So I can understand it - thanks. 1) In solid state physics, why is it that below a ...
2
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0answers
79 views

SUSY QM - working out energy spectrum and wavefunctions from a given superpotential

I'm currently self-studying F. Cooper and al.'s Supersymmetry in Quantum Mechanics, and I need help working out a particular case on shape-invariance. From a given superpotential of the form $W(x)=ax^...
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0answers
56 views

Charge Conjugation Operator in Supermultiplet

Consider an $\mathcal{N}=1$ left-handed chiral supermultiplet. The particle content is $$L = (\phi\quad e_L) $$ where $\phi$ is a complex scalar and $e_L$ a left handed Weyl fermion. People usually ...
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0answers
184 views

Mechanism of Supersymmetry Breaking (F-term, D-Term, Mediated)

I will make my question clear. SUSY is broken symmetry because we haven't seen superpartners. As far as I know, there are two mechanism of SUSY breaking, F-term and D-Term. Besides, there are some ...
3
votes
1answer
136 views

The differences of R parity and $U(1)_R$ symmetry

I know that we introduce R-parity to avoid proton decay. But some papers introduce $U(1)_R$ Lepton Number, e.g claudia, thomas. I have questions 1.What is the differences of R parity and $U(1)_R$? ...
1
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0answers
115 views

In SUSY, why do fermions and gauge bosons in the same multiplet both transform in the adjoint representation of the gauge group?

I'm trying to understand a certain point about supersymmetry. We are dealing with a N=1 (i.e, one supersymmetric flavour), massless, four dimensional theory. Then the vector multiplet consists of a ...
3
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0answers
92 views

New Supersymmetry Algebra

We know that SUSY generators commute with translation $$ [P_\mu,Q_\alpha]=0 $$ I have some questions: What is this equation physical meaning? Is it possible to make "SUSY-like" generators that do ...
1
vote
1answer
109 views

Is it possible to make superpartner of Standard Model live in Mirror World?

In the ordinary Supersymmetry (SUSY), the superpartner of SM live in SM world (matter world). Then we introduce mirror world with mirror particle live there. I would like to make a new concept that ...
2
votes
1answer
248 views

Physics in torus, cylinder, Klein bottle and mobius strip

In string theory, or supersymmetric gauge theory, they often calculate the partition function on specific Riemann surfaces, such as torus, cylinder, Klein bottle, Mobius strip. Refer to the ...
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0answers
46 views

About $U(1)_A$ symmetry,

I know a $U(1)_A$ symmetry is related with a global symmetry. (Is it axial or anomaly ) What is A stands for? In the context of supersymmertry, Fundamental and anti-fundamental chiral multiplet has ...
8
votes
2answers
1k views

Does the commutator of anything with itself not vanish?

In a quantum mechanics exam one question was to write the commutator of a couple of operators. Everybody got points taken away since they did not write $[Q_i, Q_i] = 0$ for all the operators $Q_i$ in ...
3
votes
1answer
73 views

The criterion to obtain covariant spinor derivatives in superspace

It can be simply said that covariant derivatives in 4d superspace are given by $\mathcal{D}_\mu $, $\mathcal{D}_{\alpha}$ and $\mathcal{D}_{\dot{\alpha}}$, so that they commute with the ...
2
votes
1answer
485 views

Higgs branch and Coulomb branch

I heard that the distinguish between Higgs branch and Coulomb branch is the limit of some parameters. (If i remember correctly, something like FI parameters. ) Here i want to know what is FI ...
1
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1answer
72 views

What is the difference between $N=(2,2)$ with $N=(2,2)^*$ in 2d?

What is the difference between $N=(2,2)$ with $N=(2,2)^*$ in 2 dimensional theory? In some sense, i heard, they are totally different theory. I heard from breaking of $N=(4,4)$ supersymmetry it ...
3
votes
1answer
126 views

Recommendation of papers, or reading materials on N=2, N=4 supersymmetry

I am familiar with N=1 susy in the context of Wess and Bagger. For further progress, i want to study N=2, N=4 supersymmetry, to study seiberg-like duality. (I am not familiar with the notation $N=(2,...
2
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0answers
63 views

Left (right) invariant vector fields on superspace

I read Freed'd book on "Five lectures on supersymmetry". For any vector space $V$ with metric of signature $(1,n-1)$ he constructs super Lie algebra $$ L=V \oplus S^*, $$ where $S$ is space of ...
4
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0answers
68 views

Highest weight unitary representations of $psl(2|2)$

I'm having some trouble understanding how to extend representation theory from Lie algebras to super Lie algebras, in particular with $psl(2|2)$. Ultimately I'm interested in 2D quantum sigma models ...
2
votes
1answer
62 views

How does the gluino change the strong force?

Given that the gluino is in the same representation of SU(3) that the gluon and so the same kind of interaction vertexes with quarks, I guess that it could have a role in the strong force. But there ...
6
votes
1answer
351 views

Naturalness and experiments

Is there an example where model building that is motivated only by Naturalness, has led to experimentally verified observations? If the question is unclear, or if the reader wants more elaboration, ...
1
vote
1answer
239 views

Does the gravitino contribute to the gravitational interaction?

I have a very basic question with respect to supersymmetry. Actually, I no clear idea at all what the effect of the superpartners (called gauginos??) of the exchange particles of interactions (photons,...
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vote
2answers
126 views

Converting two component product to four component notation

Consider the product of two left Weyl spinors in the notation commonly found in supersymmetry, \begin{equation} \chi ^\alpha\eta_\alpha = \chi ^\alpha \epsilon _{ \alpha \beta } \eta ^\beta \end{...
2
votes
1answer
114 views

Invariant tensors of Symplectic and Exceptional groups.

We know that for special orthogonal groups $SO(N)$ there exists invariant tensors (invariant under the group action). These are $\delta_{ij}$ and the totally anti-symmetric $\epsilon_{m_1,m_2,...m_N}$ ...
0
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1answer
700 views

What is R-symmetry with supersymmetric theory?

What is R-charge and R-symmetry? In usual context, $N=2$ supersymmetry has $U(1)$ R-symmetry. I don't understand what this means. Could you explain to me with more examples? i.e R symmetry with ...
1
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1answer
176 views

What is supersymmetry?

What is supersymmetry? How is it useful in unifying physics? I have heard that supersymmetry states that every fermion is associated with a boson and vice versa. But I don't get hope this can help ...
3
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0answers
137 views

N=4 SYM from Klebanov-Witten field theory

This is with reference to M. J. Strassler's lectures on "The Duality Cascade" pg. 46. I want to see how $\mathcal{N}=4$ SYM emerges when D3 branes, in the KW setup, are placed at smooth point of the ...
3
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0answers
90 views

Cosmological constant (positive, dS) as SUSY/supertring issue

The "almost" de Sitter expansion of current cosmological model implies a puzzle for supersymmetry (SUSY) and also for string theory. A positive value of the cosmological constant implies a non-null ...
21
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1answer
580 views

Vasiliev Higher Spin Theory and Supersymmetry

Recently there is renewed interest in the ideas of Vasiliev, Fradkin and others on generalizing gravity theories on deSitter or Anti-deSitter spaces to include higher spin fields (utilizing known ...
3
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1answer
85 views

How do gauginos and scalars gain masses after gauge-mediated symmetry breaking?

In the minimal-GMSB model, the messenger fields transform under the MSSM gauge group and connect a so-called hidden sector to the visible sector. These meesenger fields (left-handed chiral ...
2
votes
2answers
106 views

Constructing SUSY algebra via index structure

Often in literature the SUSY algebra is simply given, but various books, for example Bailin and Love, goes through the trouble of showing how the SUSY commutation relations are the only possible ones ...
8
votes
2answers
360 views

What is the meaning of negative mass (in a SUSY spectrum)?

I was playing around with SuSpect to generate some SUSY mass spectrums and I'm often encountering situations where I get a negative neutralino mass. What is the physical meaning of this negative ...
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0answers
50 views

Stability of D-Branes and Coupling to Fields

I've been brushing up on my string theory using Becker, Becker, Schwarz (p. 208 in particular). They state that some D-branes can couple to R-R fields from closed string excitations. They then go on ...
4
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2answers
193 views

What can drive the higgs mass in mSUGRA up?

As a test to familiarize myself with the program softsusy, I generated a spectrum for the following (already excluded, but once considered) mSUGRA point: $m_0 = 170\,\mathrm{GeV}$, $m_{1/2} = 190\,\...
3
votes
1answer
632 views

What exactly is a gauge anomaly?

In lots of papers I read about gauge anomalies. For example, avoiding gauge anamolies in the MSSM is the reason for introducing an extra Higgs doublet. Gauge anamolies in the Standard Model are ...
8
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1answer
620 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 ...
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1answer
668 views

What are the limitations of the superspace formalism?

Just from reading this slightly technical introduction to supersymmetry and watching these Lenny Susskind lectures, I thought that the Lagrangian of any "reasonable" supersymmetric theory can always ...
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0answers
103 views

What decides the signs and coefficients of terms in superfield?

I'm working on a problem in 3d field theory and I'm confused about how to write the superfields. Specifically, I'm not sure if the signs and coefficients of terms are purely a matter of convention or ...