# All Questions

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### Superfields and the Inconsistency of regularization by dimensional reduction

Question: How can you show the inconsistency of regularization by dimensional reduction in the $\mathcal{N}=1$ superfield approach (without reducing to components)? Background and some references: ...
945 views

### What is the upper-limit on intrinsic heating due to dark matter?

Cold dark matter is thought to fill our galactic neighborhood with a density $\rho$ of about 0.3 GeV/cm${}^3$ and with a velocity $v$ of roughly 200 to 300 km/s. (The velocity dispersion is much ...
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### Experimental test of the non-statisticality theorem?

Context: The recent paper The quantum state cannot be interpreted statistically by Pusey, Barrett and Rudolph (now On the reality of the quantum state, Nature Physics 8, 475–478 (2012), ...
804 views

### On the Coulomb branch of N=2 supersymmetric gauge theory

The chiral ring of the Coulomb branch of a 4D $\mathcal N=2$ supersymmetric gauge theory is given by the Casimirs of the vector multiplet scalars, and they don't have non-trivial relations; the ...
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### Linear sigma models and integrable systems

I'm a mathematician who recently became very interested in questions related to mathematical physics but somehow I have already difficulties in penetrating the literature... I'd highly appreciate any ...
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### Orbits of maximally entangled mixed states

It is well known (Please, see for example Geometry of quantum states by Bengtsson and Życzkowski ) that the set of $N-$dimensional density matrices is stratified by the adjoint action of $U(N)$, where ...
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### Systematic approach to deriving equations of collective field theory to any order

The collective field theory (see nLab for a list of main historical references) which came up as a generalization of the Bohm-Pines method in treating plasma oscillations are often used in the study ...
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### Symmetries of the Standard Model: exact, anomalous, spontaneously broken

There are a number of possible symmetries in fundamental physics, such as: Lorentz invariance (or actually, Poincaré invariance, which can itself be broken down into translation invariance and ...
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### What is the status of Witten's and Vafa's argument that the QCD vacuum energy is a minimum for zero $\theta$ angle?

The argument, which I reproduce here from Ramond's Journies BSM', is originally by Witten and Vafa in ($\it{Phys}$. $\it{Rev}$. $\it{Lett}$. 53, 535(1984)). The argument is that for $\theta = 0$ ...
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### A dictionary of string - standard physics correspondences

Motivated by the (for me very useful) remark ''Standard model generations in string theory are the Euler number of the Calabi Yau, and it is actually reasonably doable to get 4,6,8, or 3 ...
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### Mass of empty AdS$_5$

Five dimensional empty AdS$_5$ space has mass $$E = \frac{3 \pi \ell^2}{32 G}.$$ Is the above equation correct? Let's do some dimensional analysis to confirm. In natural units, in 5 dimensions ...
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### Bell polytopes with nontrivial symmetries

Take $N$ parties, each of which receives an input $s_i \in {1, \dots, m_i}$ and produces an output $r_i \in {1, \dots, v_i}$, possibly in a nondeterministic manner. We are interested in joint ...
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### Is there a field equation which can reduce into all three flavors of spin (zero, one, one half)?

Is there a known particle field equation of a similar form $$$$(\Gamma^n \pi_n)^2 \Psi = (mc)^2 \Psi \tag{1}$$$$ such that by reducing the number of degrees of freedom ...
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### Before inflation, what sets the initial value of the inflaton field?

[This is a version of the question that I've revised based on helpful comments from Dan.] I haven't studied inflation at a technical level. My picture of the process is that we have an inflaton field ...
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### Local explanation of the Aharonov-Bohm effect in terms of force fields

Here is an interesting paper for the Physics SE community: On the role of potentials in the Aharonov-Bohm effect. Lev Vaidman. Phys. Rev. A 86 no. 4, 040101 (R) (2012). arXiv:1110.6169 ...
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### How is Matter Modelled in Loop Quantum Gravity?

I have a basic understanding of how gravitational degrees of freedom are modelled in loop quantum gravity, but as far as I know, the main machinery - spin network states and observables, does not ...
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### Is the “Doctor Who” spacetime affected by Hawking's chronology protection mechanism?

Recently, there has been a paper1 (and an accompanying layman-ized white paper2) on "Traversable Achronal Retrograde Domains In Spacetime", TARDIS for short. It proposes a spacetime geometry that ...
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### Is general relativity holonomic?

Is it meaningful to ask whether general relativity is holonomic or nonholonomic, and if so, which is it? If not, then does the question become meaningful if, rather than the full dynamics of the ...
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Ive just read, that for non extremal black holes, there exists a logarithmic (and other) correction(s) to the well known term proportional to the area of the horizon such that $S = \frac{A}{4G} + K ... 0answers 63 views ### Minimal strings and topological strings In http://arxiv.org/abs/hep-th/0206255 Dijkgraaf and Vafa showed that the closed string partition function of the topological B-model on a Calabi-Yau of the form$uv-H(x,y)=0$coincides with the free ... 0answers 523 views ### Could this model have soliton solutions?$\mathcal{L}=i\bar{\Psi}\gamma^\mu\partial_\mu\Psi-m\bar{\Psi}\Psi+\frac{1}{2}g(\bar{\Psi}\Psi)^2$Field equation$(i\gamma^\mu\partial_\mu-m+g\bar{\Psi}\Psi)\Psi=0$Could this model have soliton ... 0answers 111 views ### Super Lie-infinity algebra of closed superstring field theory? Bosonic closed string field theory is famously governed by a Lie n-algebra for$n = \infty$whose$k$-ary bracket is given by the genus-0 (k+1)-point function in the BRST complex of the string. One ... 0answers 363 views ### Hypersingular Boundary Operator in Physics This has been a question I've been asking myself for quite some time now. Is there a physical Interpretation of the Hypersingular Boundary Operator? First, let me give some motivation why I think ... 0answers 212 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 ... 0answers 153 views ### Orbifold CFT of SU(2)/G and SO(3)/G In this paper by Dijkgraaf, Vafa, Verlinde, Verlinde, orbifold CFT is discussed. In that paper, it outlined that orbifold CFT provides a way to generate the new theories from the old known ones. ... 0answers 132 views ### Are quantum decoherence and Everettian approaches to the measurement problem necessarily distinct? As I understand it, there is a large contingent of physicists who believe that the measurement problem is "solved" by decoherence, without, for example, needing to postulate the existence of "many ... 0answers 202 views ### “S-duality” between confinement and the Higgs mechanism? I feel picked by the second to last sentence in this answer to a question about what would happen if EM and QCD were spontaneously broken, which says "In fact, there is a sense in theoretical ... 0answers 254 views ### Derivation of KLT relations The KLT relations (Kawai, Lewellen, Tye) relate a closed string amplitude to a product of open ones. While I get the physics behind this I don't really understand the derivation in the original paper ... 0answers 186 views ### Compactifying on a circle and the exchange of R and NS sectors I've noticed a general phenomenon in compactifying on a circle where if you start with, say, an NS field, then the KK fields with an index along the circle will be in the R sector, and those without ... 0answers 156 views ### Can Lee-Yang zeros theorem account for triple point phase transition? Now the prominent Lee-Yang theorem (or Physical Review 87, 410, 1952) has almost bocome standard ingredient of any comprehensive statistical mechanics textbook. If the volume tends to infinity, ... 0answers 307 views ### Small oscillations of heavy string I'm solving problem in classical field theory and I have some difficulties. I'm trying to study small oscilations of heavy string with fixed points. First of all I wrote down this Lagrangian: ... 0answers 88 views ### Do Franck-Condon oscillations have natural lineshapes? I recently found a paper (for the curious, this one) that talks about observing the motion of a nuclear wavepacket in H2O, as initiated by tunnel ionization. This wavepacket should be thought of as a ... 0answers 208 views ### Nuclear Magnetic Resonance (NMR) Conceptual Questions Let$M$be the magnetic moment of a system. Below are the Bloch equations, including the relaxation terms. $$\frac{\partial M_x}{\partial t}=({\bf M} \times \gamma {\bf H_0})_x-\frac{M_x}{T_2}$$ ... 0answers 149 views ### Is the Hawking radiation of a charged black hole thermal? Suppose you have a Schwarzschild black hole of mass$M$and angular parameter$a = 0$(no rotation). Question: is it possible to throw a charge$Q$at a faster rate than it will be re-radiated? Will ... 0answers 322 views ### Do intergalactic magnetic fields imply an Open Universe? According to a recent paper on the arXiv, they do. How credible is this result? The abstract says: The detection of magnetic fields at high redshifts, and in empty intergalactic space, support ... 0answers 213 views ### gauge invariant but not gauge covariant I'm not sure if someone's already asked this before, but I was wondering, in field theory, when we say that a certain field is gauge invariant but not gauge covariant, what does this mean? In ... 0answers 192 views ### What is Motivic mathematics and how is it used in physics? In a few videos I've seen where he discusses the new approach to calculating the super Yang Mills scattering amplitudes, Nima Arkani-Hamed sometimes alludes to the use of Motivic methods as being ... 0answers 245 views ### Quasi 1D insulators with strong spin-orbital interaction We know that the spin-1 chain realizes the Haldane phase which is an example of symmetry protected topological (SPT) phases (ie short-range entangled phases with symmetry). The Haldane phase is ... 0answers 220 views ### Magnetic monopole and electromagnetic field quantization procedure From the Maxwell's equations point of view, existence of magnetic monopole leads to unsuitability of the introduction of vector potential as$\vec B = \operatorname{rot}\vec A$. As a result, it was ... 0answers 148 views ### Intuitive sketch of the correspondence of a string theory to its limiting quantum field theory I'm looking for an intuitive sketch of how one shows the correspondence of string theory to a certain QFT. My best guess is that one calculates the scattering amplitudes in the string theory as a ... 0answers 514 views ### Gauge redundancies and global symmetries It is often said that local (gauge) transformation is only redundancy of description of spin one massless particles, to make the number degrees of freedom from three to two. It is often said that ... 0answers 73 views ### Quantum statistics of branes Quantum statistics of particles (bosons, fermions, anyons) arises due to the possible topologies of curves in D-dimensional spacetime winding around each other What happens if we replace particles by ... 0answers 89 views ### Mathematical motivation of OPE? In Peskin & Schroeder (and also Cheng which I have skimmed through) they motivate the Operator Product Expansion with a lot of words. Is there any way to motivate it mathematically, e.g. Taylor ... 0answers 163 views ### What's the physical intuition for symplectic structures? I always thought about symplectic forms as elements of areas in little subspaces because of the Darboux theorem, however I cannot get the physical intuition for it and for the hamiltonian vector ... 0answers 163 views ### Hilbert Space of (quantum) Gauge theory Since quantum Gauge theory is a quantum mechanical theory, whether someone could explain how to construct and write down the Hilbert Space of quantum Gauge theory with spin-S. (Are there something ... 0answers 158 views ### How does the Super-Kamiokande experiment falsify SU(5)? In his book "The Trouble With Physics", Lee Smolin writes that he is still stunned by the falsification of the$SU(5)\$ Georgi-Glashow model by the null results of proton decay experiments. I should ...
I am deriving the results of renormalization for nonlinear sigma model using Polyakov approach. I am closely following chapter 2 of Polyakov's book--- Gauge fields and strings''. Action for the ...