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.

learn more… | top users | synonyms (7)

1
vote
0answers
34 views

Why are WZW models interesting?

I realise this is a very broad question, but when I was studying for my thesis I randomly came across WZW models for a few times and I never quit understood them. So I understand that these models ...
2
votes
0answers
63 views
+100

Can pure-bosonic string theories exist in curved spacetime?

Question: Can there be a consistent non-supersymmetric pure-bosonic string theory in some curved spacetimes? Reason: Since fields with certain amount of negative mass can exist in curved spacetime ...
4
votes
1answer
475 views

Does string theory pose a photon mass problem?

A few weeks ago, I started reading books on string theory. One thing that really seemed confusing or contradictory was that string theory explains that the energy of a superstring gives mass to the ...
1
vote
0answers
17 views

Hypermultiplet as BPS particles

In the third paragraph of page 7 of the paper arxiv:1112.3984 it mentions that we form a basis out of hypermultiplets on the charge lattice $\Gamma$. My questions are: In what sense do we form such ...
4
votes
0answers
36 views

Concerning topology of BPS states of the M5-brane

My question is about the M5-brane in M-theory. I would like to know whether the BPS states of the M5-brane worldvolume theory (especially the 1/2 BPS and 1/4 BPS ones) are independent of the topology ...
0
votes
0answers
22 views

Is there a constant decay of particles that maintains the value of the Quantum Vacuum? [on hold]

By my question I am attempting to understand how the Vacuum of space remains at a constant value, (GR the universe on the large scale matches the “critical” energy density of about 8.5×10-10 J/m3) ...
1
vote
1answer
38 views

How does the holographic principle apply to the $n$ dimensional space of String Theory?

The holographic principle is a property of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a ...
0
votes
1answer
78 views

M-theory and Mathematics [on hold]

If the framework of M-theory is the right path for a unification of gravity with quantum mechanics, is it obligatory to believe that, at a certain level, reality is not just easily describable by ...
-3
votes
1answer
91 views

Can someone explain about M-theory? [closed]

Can someone explain about M-theory? I am very new to M-theory and string theory. I am very through with classical physics and little bits of quantum mechanics. Will you be able to explain why ...
0
votes
0answers
63 views

A few questions about gravity [on hold]

Please don't count this as a duplicate, I have searched so many similar questions and have not found the answer. Also, don't count this as too broad because I can't find the answers anywhere else so ...
1
vote
0answers
12 views

Toroidal compactification and number of susy

In case of Tordial compactification, reference states page 13, A.Font et al, Introduction to string compactification, it does not reduce the number of real supercharges. I wonder why this happens. ...
1
vote
0answers
48 views

Fayet-Iliopolous Parameters from Separation of NS5-branes in $(x_{7}, x_{8}, x_{9})$: An ambiguity as to which gauge group the FI parameter belongs

hep-th/9611230v3, page 12 explains how, for a configuration of D3s along $(x_{1}, x_{2}, x_{6})$, and NS5's along $(x_{1}, x_{2}, x_{3}, x_{4}, x_{5})$, the Fayet-Iliopolous D-term coefficient $\zeta$ ...
0
votes
0answers
30 views

How M theory or String theory explains fundamental forces and Quantum mechanical phenomena? [closed]

How M theory explains fundamental forces gravity,strong,weak and electromagnetic? And how does M theory explains phenomena of light like reflection,refraction,diffraction,interference etc?
0
votes
0answers
39 views

Role of special unitary groups in string theory [closed]

I have chosen string theory as an elective subject for my masters.Today, I attended my very first lecture on string theory. My professor mentioned special unitary groups $SU(2)$ and $SU(3)$ many ...
4
votes
0answers
124 views

Has Sen quantized superstring fields?

Today I saw a paper by Ashoke Sen titled "BV Master Action for Heterotic and Type II String Field Theories". Is it really the "quantization" of superstring fields for the first time? What can be its ...
-4
votes
2answers
67 views

Quantum computers for string theory? [closed]

I read something about that locating our space in the multitude of multidimensional spaces of M-theory (and so identifying particular particles which we can measure with particular strings) is a too ...
1
vote
0answers
41 views

How can the stress tensor components of a worldsheet CFT in general background be (anti)-holomorphic?

In all textbooks/lecture notes on string theory (e.g. Polchinski, page 43 at the bottom) it is proven that, as the stress tensor is traceless and conserved, $T^a_a=\partial^a T_{ab}=0$, we have ...
6
votes
3answers
283 views

Problems book recommendation on supersymmetry, supergravity and superstring theory

I'm learning supersymmetry, supergravity and superstring. I want some problems books to have some idea in this area. Is there this kind of books? Or are there some papers that have many solved model?
2
votes
1answer
137 views

What causes gravity in M-Theory?

New and updated, because people were misunderstanding what I meant! General relativity describes gravity as the result of....(very roughly) spacetime curvature Newtonian gravity describes gravity as ...
9
votes
1answer
648 views

String theory from a mathematical point of view

I have a great interest in the area of string theory, but since I am more focused on mathematics, I was wondering if there is any book out there that covers mathematical aspects of string theory. I ...
1
vote
1answer
61 views

Global symmetries in type IIB string theory vs type IIB supergravity

In the AdS/CFT correspondence I know that the mapping of global symmetries involves also the S duality that in the field theory side is $SL(2,Z)$. In Type IIB supegravity this duality is $SL(2,R)$. I ...
0
votes
0answers
15 views

constructing string path integral through Markov chain procedure

We all know the textbook way of constructing the path integral for a point particle. It goes approximately like this (if relativistic). Say we want the propagator $\Delta(x_\text{in},x_\text{out}) = ...
2
votes
0answers
45 views

QFT background needed for AdS/CFT integrability [closed]

Apologies if this type of question isn't permitted. I'm very interested in integrability in the context of AdS/CFT. I'm starting my Masters soon in a very GATIS-involved institute and would like to ...
1
vote
0answers
23 views

Holography with wave functionals rather than partition functions

Roughly speaking Gubser-Klebanov-Polyakov Witten's (GKPW) prescription in the context of holography tells us partition function of CFT is "equal" to that of the gravity theory in one higher dimension ...
2
votes
1answer
132 views

Proper way to quantize the string in the light-cone gauge

In many books like Polchinski and Green-Schwarz-Witten the light cone quantization is carried out in a fast way. They just use the virasoro constraint in the light-cone gauge to get the ligh-cone ...
1
vote
0answers
46 views

Effect of orbifolding on form ields

A paper by Lalak et al, entitled "Soliton Solutions of M-theory on an orbifold", considers the brane solutions of 11 dimensional supergravity on a space of the form $R^{10} \times S^1/\mathbb{Z}_2$. ...
4
votes
2answers
225 views

Why does the non-linearity of the string action prohibit stretching due to strong excitations?

From 't Hooft's String Theory lecture notes on page 8 (paraphrased): To understand hadronic particles as excited states of strings, we have to study the dynamical properties of these strings, and ...
1
vote
0answers
48 views

Gravity dual of N free scalars in 2D

I have a very basic (and might be very naive) question. What should be the dual gravity description of $N$ (with $N>>1$) free scalars in two dimensions? I was wondering whether it would be ...
0
votes
0answers
51 views

Has string theory predicted any experimently verified results? [duplicate]

I'm just getting into string theory and I'm wondering if it has made any unique predictions that have been verified by experiment?
3
votes
1answer
115 views

Estimating volume of moduli space of genus-g Riemann surface with n marked points

I wanted to know how can I estimate the volume of the moduli space of a Riemann surface of genus $g$ and having $n$ marked points. I am reading some old string theory papers which discuss divergences ...
1
vote
1answer
61 views

Calabi Yau Motivation

I have just begin to study Calabi Yau compactification. Looking in many book I found that, if we start with a critical superstring theory in $D=10$, we are in search of a compact $D=6$ Calabi Yau ...
6
votes
2answers
287 views

Is there some no-go theorem for $D=9$ Kaluza Klein QCD+EM?

While QCD is a typical product of AdS/CFT and some other research trends in extra dimensions, I have never found in the literature an example producing the non-chiral part of the standard model, ...
10
votes
2answers
7k views

Fundamental equation(s) of string theory?

I often hear about string theory and its complicated mathematical structure as a physical theory, but I can't say that I've ever actually seen any of the related math. In general, I'm curious as to ...
0
votes
0answers
48 views

Can string theory and the Penrose interpretation coexist?

Is it possible for string theory to coexist with the Penrose interpretation of quantum mechanics? Does string theory require the many worlds interpretation?
1
vote
1answer
125 views

What is a ghost number?

I am currently studying CFT chapter of Becker,Becker,Schwarz and am trying to understand what the ghost number is in BRST Quantization. From what I gather BRST Quantization is used to add an extra ...
1
vote
1answer
85 views

Generalized spin connection and dreibein in higher spin gravity

I am studying 3D higher spin gravity and I would like to know the mathematical and physical meaning of generalized spin connection and generalized dreibein that appear in this theory. It is well known ...
0
votes
0answers
36 views

How much do we know about Quantum Gravity at energies larger than Planck energy?

What kind of predictions do current approaches to quantum gravity (superstrings/M-theory, loop quantum gravity,...) make at energies LARGER than Planck scale? Or is that a meaningless question? Does ...
0
votes
0answers
19 views

Are $T^2/Z_2$ orbifolds just ironed spheres? [migrated]

The only $Z_2$ symmetries I can think of the torus are reflection on plane, whose quotient should form an open cylinder, and rotation by 180 degrees, which becomes the "branched covering" of the ...
12
votes
2answers
780 views

Why can the Euler beta function be interpreted as a scattering amplitude?

The Wikipedia article on the Veneziano Amplitude claims that the Euler beta function can be interpretted as a scattering amplitude. Why is this? In another word, when the Euler beta function is ...
5
votes
1answer
113 views

Where do $X_0^{-d}$ and $G'_r$ come from in Polchinski Eq. (6.2.13)?

I have a question about deriving Eq. (6.2.13) in Polchinski's string theory book volume I. It is claimed that Now consider the path integral with a product of tachyon vertex operators, ...
2
votes
0answers
56 views

Problem with OPE (from Polchinski) [closed]

I was reading Polchinski, Vol. 2 pag 12, while I found (10.3.12a): $$ e^{iH(z)}e^{-iH(z)}=\frac{1}{2z} + i\partial H(0) + 2zT^H_B(0) + O(z^2).\tag{10.3.12a} $$ Now I tried to do the OPE, what I ...
2
votes
0answers
28 views

Superstring NS tachyon vertex operator

After reading some confusing chapter of various string theory book I'm trying to construct the Tachyon vertex operator for superstring theory. I know that this is removed after GSO projection, but for ...
1
vote
0answers
22 views

Correlator $bc$ system [closed]

I have da doubt with bc system. Polchinski says (2.5.10) $$ b(z)b(0)~=~O(z). \tag{2.5.10} $$ I tried to compute the correlation function With eom, using eq (2.5.6b) by Polchinki, removing the ...
1
vote
1answer
76 views

Polchinski Equation (10.4.7) [closed]

I'm having a problem to interpret eq. (10.4.7) in Polchinski: $$ \gamma(z)\delta(\gamma(0)) = O(z), \qquad \beta(z)\delta(\gamma(0)) = O(z^{-1}). $$ What does he mean by $\delta$? He tries to ...
3
votes
0answers
44 views

Connection between the M5 brane and (2, 0) superconformal field theory

I have read that the worldvolume theory of the M5 brane is a $(2, 0)$ superconformal field theory (SCFT). But I have also learnt from talks that the $(2, 0)$ theory lacks a Lagrangian description. ...
5
votes
3answers
925 views

Does string theory and preons exclude each other?

Does string theory contradict the theory of preons, especially the Harari-Shupe one?
2
votes
1answer
103 views

How is a string in string theory different from a harmonic oscillator or a point?

I am reading String Theory and M-Theory: A Modern Introduction by Becker, Becker and Schwartz. I've tried to read this book before but not succeeded because I didn't know enough math or physics. This ...
1
vote
0answers
29 views

Quantum corrections to holographic entanglement entropy

I was looking at this paper by Faulkner-Lewkowycz-Maldacena. They give a very interesting proposal of calculating one loop (i.e, 1/N) correction to EE from computing the EE between the bulk regions. ...
3
votes
0answers
32 views

Type I string theory on $K3 \times \mathbb T^2/\mathbb Z_2$ and the K3 orbifold limit

Consider Type IIB string theory with 4 O7-planes and 32 D7-branes on $K3 \times \mathbb T^2/\mathbb Z_2$. The K3 induces D3-charge on their world-volumes which can be cancelled by the introduction of ...
1
vote
0answers
24 views

D-brane tension of type I D9-branes after T-duality

Type I contains branes with a brane tension which is $\frac{1}{\sqrt 2}$ times that of type II branes. The reason is that, e.g., in the computation of the D9-D9 amplitude the open string is ...