A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of extended objects, such as the 1-dimensional fundamental string. PLEASE DO NOT USE THIS TAG for non-relativistic material strings, such as, e.g., a guitar string.

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75 views

Infinitesimal transformations for a relativistic particle

The action of a free relativistic particles can be given by $$S=\frac{1}{2}\int d\tau \left(e^{-1}(\tau)g_{\mu\nu}(X)X^\mu(\tau)X^\nu(\tau)-e(\tau)m^2\right).$$ If we then make an infinitesimal ...
5
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0answers
45 views

Why does a string connected between a D0-brane and an anti-D0-brane turn into a tachyon upon their annihilation?

Consider a string stretched between a D0-brane and an anti-D0-brane. In this case as the stretching energy is greater than the quantum zero point energy the string will have a positive mass. But, as ...
0
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0answers
15 views

Why does quantum zero point energy contribute negative mass to strings?

A string which doesn't have any kind of vibrations will have mass whose square is negative due to quantum zero point energy. But why does it contribute negative rather than positive mass to strings?
9
votes
1answer
168 views

Quantization of strings, string Fock space and transition to QFT

I am not an expert of string theory and am quite uncertain about the basic ideas of string theory that I am going to ask about. I would appreciate some hints of more experienced physicists. What I am ...
0
votes
1answer
41 views

Poincare Symmetry of Nambu-Goto action

How do I show invariance under the Poincare transformations of the action for a relativistic string, $$S=-\frac{1}{2 \pi \alpha'} \int{\text{d}^2 ...
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vote
2answers
74 views

Road to String Theory [duplicate]

I have a question for our theoretic SuperUsers. How much knowledge and which fields of physics you have to know to start studying string theory? I am now on QFT, after I think I'll start study ...
5
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0answers
56 views

Topology-dependent groud state degeneracy of $B \wedge F + B \wedge B$ and $B \wedge F + B \wedge B \wedge B$

There are some examples of topological BF theory with extra terms allow it still being topological. See this Ref. paper In 4d (3+1D), we have the trace of: $$ \int\frac{k}{2\pi}\text{Tr}[B \wedge F + ...
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0answers
26 views

Non-trivial components of the stress-energy tensor of the bosonic string ghost action

The stress-energy tensor derived from the ghost action of a bosonic string is: $$ T_{\alpha \beta} = \frac{i}{4 \pi} \left ( b_{\alpha \gamma} \nabla_{\beta} c^{\gamma} + b_{\beta \gamma} ...
2
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1answer
37 views

Do all vacua in the string theory landscape have a different cosmological constant?

Or can two vacua with the same energy differ in other ways?
3
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1answer
225 views

Gregory-Laflamme Instability of Black Strings and $p$-Branes

In a paper by Gregory and Laflamme (http://arxiv.org/abs/hep-th/9301052) in 1993, it was demonstrated that black strings and $p$-branes which were solutions to certain low energy string theories were ...
12
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1answer
213 views

Self-dual Maxwell equations, the second homology group, and topological invariants of a four manifold

In Witten's paper Quantum Field Theory and the Jones Polynomial, he mentioned that: Geometers have long known that (via de Rham theory) the self-dual and anti-self-dual Maxwell equations are ...
4
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1answer
92 views

Gravitational Chern-Simons theory for bosons and fermions

Q1: What is the difference of boson and fermions for their Gravitational Chern-Simons theory? I suppose in general if the metric is not flat, we have vierbein ${e_{\hat{b}}}^{\nu}$, with $$ ...
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3answers
115 views

Is Space-Time a special form of energy?

I know space-time can be influenced by matter and energy, so it must be somehow mingled in with the mix of it all, but does space-time have a fundamental particle? Can we make a little bit of ...
5
votes
1answer
63 views

Quantized coefficients of Chern-Simons action and F $\wedge$ F $\wedge \dots$

We know that for U(1) gauge field Chern-Simons action in 2+1 Dim(ension), we have an action $$ S=\alpha \int A \wedge dA $$ with $\alpha=k/(4\pi)$ for a proper level quantization. Here $k$ is the ...
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0answers
42 views

$D$-brane and 5th dimensions

While I was looking up the 5th dimension of the Randall-Sandram model, I have wondered whether Kaluza Klein theory can be applied to the $D$-brane or $p$-brane. Can the $D$-brane and $p$-brane ...
2
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0answers
61 views

Is the cross section of a relativistic water hose or string always a perfect circle?

Given is a very long tube, such as a water hose or a tubular string with finite thickness, that has a constant circular cross section of radius $r$ along the length and that is at rest in an inertial ...
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2answers
187 views

Operator Product Expansion (OPE) in Conformal Field Theory

We denote local operators of a conformal field theory (CFT) as $\mathcal{O}_i$ where $i$ runs over the set of all operators. Formally, the operator product expansion (OPE) is given by, ...
4
votes
1answer
113 views

Which is the role of Algebraic Geometry in String Theory? [closed]

Could someone sketch me what algebraic geometry has to do with string theory? Are there other mathematical disciplines that are interwoven with string theory? I'm aware of a similar question on ...
2
votes
1answer
69 views

Number of zero-modes on the sphere

Is it true that a field of conformal dimension $h$ (integer or half integer) has $1-2h$ zero-modes on the sphere, if $1-2h \geq0$. This seems to be right for different ghost fields : $c$ has ...
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0answers
30 views

Can the length of the closed string larger?

Can the length of the closed strings becomes larger than the plank length ? With that , does the string describe the higgs particles ?
3
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0answers
85 views

String theory and space-time supersymmetry

I actually want to know whether space-time supersymmetry is important for string theory consistency? I see that NS and GS supersymmetric strings have worldsheet supersymmetry, but the first one does ...
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0answers
20 views

Open string amplitude with higher vertices

In Polchinski's String Theory, section 6.2, the tree level amplitude for open strings with higuer vertices are given (6.2.18-20). The amplitude $<\prod_i[e^{ik_i\cdot X(z_i,\bar ...
2
votes
1answer
144 views

Spin connection in higher dimension

I have a problem regarding computation of spin connection in the case where One or more dimension is compactified. For example if we take a $D+1$ dimensional bosonic string action and write the $D+1$ ...
10
votes
2answers
253 views

The difference between The Dilaton and The Radion?

I have read this question on the Dilaton, but I am a little confused with the distinction between the Dilaton and the Radion. I definitely have the feeling that these two scalar fields are different ...
2
votes
0answers
41 views

String Vertex Operators in Light Cone Gauge

I have a basic confusion about how to compute string scattering amplitudes in light cone gauge, using the operator formalism reviewed in GSW. I am familiar with the covariant gauge formalism, where I ...
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0answers
40 views

Is it possible to define a notion of temperature in a microcanonical ensemble?

I am thinking of a mircrocanonical ensemble as a finite system for which the number of particles, volume and the total energy is fixed. Is there a more refined view of this? Can I think of ...
2
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0answers
48 views

Relation between holography and matrix models

Let's consider a 0-dimensional $N \times N$ Hermitean one matrix model. It is defined by a potential V(M). Its partition function is $Z = \int_{H_{N}} dM e^{-\frac{1}{g}V(M)}$ where $H_{N}$ is the ...
0
votes
1answer
34 views

Concerning Electrogravitics in an inertial frame

Listening to Feynman, He pointed out the fact that if a magnet is in an inertial frame with respect to a coil, there can be no electromotive force and hence no electricity produced. It is only when ...
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214 views

p-Adic String Theory and the String-orientation of Topological Modular Forms (tmf)

I am going to ask a question, at the end below, on whether anyone has tried to make more explicit what should be a close relation between p-adic string theory and the refinement of the superstring ...
4
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1answer
94 views

Allowed interactions in bosonic string theory

In a quantum field theory, only a finite set of interactions are allowed, determined by the Lagrangian of the theory which specifies the interaction vertex Feynman rules. In string theory, an ...
0
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2answers
188 views

gravitational waves

Now that scientists found the primordial gravitational waves that formed shortly after the big bang,and we all now that just after the bang the 4 fundamental forces were unified can we consider that ...
7
votes
1answer
75 views

Connection beween infinite gauge symmetries and UV finiteness

In e.g., http://arxiv.org/abs/arXiv:0712.3526 the author claims: Since the massless higher-spin field theories involve infinite-dimensional gauge symmetries, one expects that such theories may be ...
0
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0answers
34 views

Book suggestion for Theoretical Physics with easy maths [duplicate]

I am a Computer Scientist with literature interest in theoretical physics. I have already read books such as A Brief History of Time and Physics of the Impossible, and I am looking for suggestion for ...
6
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0answers
104 views

Which values of the Riemann zeta funtion at negative arguments come up in physics?

For my bachelor's thesis, I am investigating Divergent Series. Apart from the mathematical theory behind them (which I find fascinating), I am also interested in their applications in physics. ...
2
votes
1answer
38 views

How exactly is the Poisson bracket of the modes of a classical string defined?

In the theory of a classical bosonic string, we have expressions like: $$ \{\alpha^\mu_m,\alpha^\nu_n \} = - i m \delta_{m,-n} \eta^{\mu \nu} $$ were $\alpha^\mu_n$ are the Fourier modes of the ...
5
votes
1answer
114 views

Where and how exactly does string theory and Q.E.D. use zeta function regularization?

In the video they mention it being used in many fields of physics inclusing String and QED theory. https://www.youtube.com/watch?v=w-I6XTVZXww But I remember reading somewhere that 1+2+3..=-1/12 is ...
2
votes
1answer
86 views

Where do our 4 macroscopic spacetime dimensions reside in multidimensional models of the universe?

In models such as M-theory with 7 'higher dimensions' plus the 4 macroscopic spacetime dimensions, where do our 4 macroscopic spacetime dimensions reside ordinally? My reason for asking is TV shows ...
2
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0answers
303 views

BICEP2 and string theory

Can anybody elaborate on the implications of the BICEP2 result for string theory? The discussion here What experiment would disprove string theory? suggests that refuting string theory is rather ...
4
votes
1answer
232 views

What does it mean to “wrap” a D-brane around some manifold?

I am getting quite confused with this terminology when I read the papers. Like while constructing the near horizon $AdS_3$ in the $D1-D5$ system one considers $IIB$ on $R^{1,4}\times M^4 \times S^1$ ...
4
votes
1answer
82 views

AdS3 soliton of Witten - for Hawking-Page transition

Are there explicit AdS$_3$ soliton solution? in the sense of Witten's Anti De Sitter Space And Holography and Hawking-page transition paper, by doing a $$\tau_E, y ,r \to y, \tau_E ,r$$ from ...
0
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0answers
63 views

What is the most fundamental peice of matter? What is it that thing which can no more be sub-divided?

I know that there is theory that strings are the most fundamental particles. But if it is a string, then it can be 'cut' into pieces, and if it can be 'cut', then it can be cut at infinitely many ...
3
votes
0answers
47 views

Action for $p-p'$ strings (equation 13.5.21 in Polchinski's textbook)

This action reads $$S=-\frac{1}{4g_{D9}^2}\int d^{10}x F_{MN} F^{MN}-\frac{1}{4g_{D5}^2}\int d^{6}x F'_{MN} F'^{MN}- \int d^6 x \left[ D_{\mu} \chi^{\dagger} D^{\mu} \chi + ...
3
votes
2answers
470 views

Dirac, Weyl and Majorana Spinors

To get to the point - what's the defining differences between them? Alas, my current understanding of a spinor is limited. All I know is that they are used to describe fermions (?), but I'm not sure ...
3
votes
1answer
91 views

Can a D-brane be closed and contractible?

Let's consider for simplicity D-branes in bosonic string theory. I have a very basic question whose answer I couldn't find clearly stated in the few textbooks where I looked for it. Take for ...
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38 views

How to deduce equations 3.6.15 in Polchinski's string theory book? [duplicate]

In polchinski's first course on string, with how to deduce
5
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1answer
223 views

Seiberg-Witten theory and Superconductivity

There seems to have some (deep) relation between Seiberg-Witten theory and superconductivity. e.g. this Witten paper. Q: Could someone introduce the relations between the twos both physically in ...
3
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44 views

entropy relation between ads$_2$ black hole and near extremal ads RN black brane

It seems that the entropy for AdS$_2$ black hole is independent of the temperature $s=s_0$. While for near extremal AdS RN black brane, $s=s_0+ s(T/\mu)$. Should not these two entropies be the same ...
2
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0answers
15 views

Using the boundary states, is there a precise way to write down a planar open string multi-loop amplitude as a closed string tree amplitude?

The only explicit computation I have seen is the planar 1-loop one, but there should be a way to write the multi-loop case in terms of boundary states as well.
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0answers
38 views

Is brane world scenario in contrast with inflation theory? [closed]

Is brane world scenario in contrast in some way with inflation theory ?
3
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1answer
71 views

Question about the vacuum bundle on A- and B-model

Let us consider the topological string A- and B-model (twisted SUSY non-linear sigma model on CY 3-manifold $X$). They are realization of $N=2$ SCFT and there are ground-states vector bundle ...