Questions tagged [research-level]

The research-level tag applies to questions that arise in graduate and post-secondary work. These questions often require domain-specific knowledge and could not be answered from a general source or may be beyond the level typically covered by Wikipedia and other popular sources. Research-level questions should not require new or groundbreaking research and results to answer.

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9 views

How (or where) to look up vapor pressure of a material at ultra-high vacuum pressure?

Is there a way to look up the vapor pressure of a given material (usually binary compounds or simply elements) at ultra-high vacuum (usually near $10^{-9}$ Torr). For example, if I want to know the ...
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1answer
46 views

Is there any specific template to write a discovery paper? How to write a paper then? [closed]

I am really an enthusiast of physics! I like to write, read and even live with physics! but the question comes how could I express my researches? I am an amateur physicist but don't really know how to ...
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26 views

BEC Relaxation to Dispersion Minimum

I am reading this paper, which looks at the emergence of a double well dispersion in an optical lattice through shaking as in the figure below. I am curious as to what mechanism results in the atoms ...
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9 views

How to use quartz crystal microbalance (QCM) to determine thin film growth time in molecular beam epitaxy (MBE)?

Let's put the question in the context of growing Bi2Se3 thin film. Say, we would like to grow 20 quintuple layers of Bi2Se3 using MBE. The flux rate of Bi dominates that of Se for the purpose of ...
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Classification of 10-dimensional heterotic string theories

In many textbooks the typical story is told that there are exactly 2 possible heterotic theories in 10 dimensions, the $E8\times E8$ as well as the $SO(32)$ theories. This is of course only true for ...
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2answers
84 views

Can a self-educated physicist publish papers? [closed]

I started self learning mathematics and physics .. but the thing is I can't join a college , but I watch online lectures and read textbooks instead .. I am interested in theoritical physics .. But I ...
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1answer
329 views

Is the recent Nature paper by Minev et al. evidence of new physics?

Ok the title might be slightly clickbaity. A better one might be "Why isn't the recent Nature paper by Minev et al. evidence of new physics?", but I didn't want to make too many assumptions ...
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16 views

How to find length of object in photo, object at an angle

I have a picture of a section of a rectangular prism taken at an angle so that it isn't facing parallel with the camera like below. The end of the prism is cut off by the photo, and I have a scale for ...
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50 views

Regular black hole with an evanescent horizon

I'm reading a great paper named Geodesically Complete Black Holes by R. Carballo, F. Filippo, S. Liberati and M. Visser about regular black holes and I'm trying to understand a particular situation. ...
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72 views

Why is the entry barrier in Physics Research Topics so high? [closed]

Why is the entry barrier in physics research so high?? When I try to read a research paper to see the latest developments in a particular topics I am always held back by my mathematical abilities. And ...
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594 views

Dynamics of a bouncing capsule

I am working on a research project investigating the bounce of a capsule. I have tried to model it using conservation of energy, where we considered torque by normal force and friction during the ...
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54 views

Non-markovian random walk. Elephant random walk

When one does the numerics for the usual random walk, one might use the transition matrix in order to get the probability ar time $t$ of the process. As expected, the asymptotic behavior yields a ...
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Extended Blonder Tinkham Klapwijk in graphene

Background In this paper the author studies the BdG equation for a metal-superconductor-metal system. The left metal is electron doped and is in the region $x<0$, the supercondcutor is in the ...
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1answer
44 views

What's the index (or topological charge) of this vector field image?

I am doing some research in a condensed matter system, and found this Berry curvature / vector field configuration that is unusual. I cannot find another example of something similar, either from ...
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Calculating the Nambu-Gorkov propagator (given its inverse) for quarks

I am working through this paper on the calculation of a Nambu-Gorkov propagator, could someone explain how did we reach the next step right after equation (16)?
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QCD methods - Dirac trace, trace in color space, trace in flavor space

What is meant by the following terms in QCD - Dirac trace, trace in color space, trace in flavor space, etc. Could someone explain with an example (For eg. what's the diffrerence between something ...
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Calculating the quark propagator while dealing with the color, Dirac & flavor matrices all together

$S^+$ is a diagonal matrix in color space, and is given as : $S^+ = S_{rg} ^+ \hat{P_{rg}} + S_b ^+ \hat{P_b}, where, \hat{P_b} = 1_c - \hat{P_{rg}}$ is the projector on blue quarks, $\hat{P_{rg}}$ ...
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1answer
87 views

How to transform a given Lagrangian to a Nambu-Gorkov basis?

With reference to the Nambu (or famously, Nambu-Gorkov) transformation in this paper, could someone explain the reason behind using the 3rd Pauli matrix in the Lagrangian after equation (2.3) (would ...
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Are Chern-Simons theories classified by bordism groups?

For a long time it was thought that anomalies for a group $G$ were classified by $H^n(BG)$, although it is now understood that they are in fact classified by $\Omega^n(BG)$. On the other hand, ...
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14 views

Inferring angle of source?

Given the relative distance of 3 radio antennae, I want to infer an incident angle for some radio source seen by all 3 antennae, which I know to be on the ground. All I know is the relative locations ...
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1answer
44 views

Waves on a topological surface

Are there any formulas for wave motion on a topological surface, like a Mobius strip? If not, is this a valid opportunity for research?
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1answer
84 views

Geometric representations of affine Lie algebras

I have recently been reading literature on geometric constructions of representations of affine Lie algebras by Nakajima and others. In particular, the representations arise as cohomologies of moduli ...
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1answer
47 views

Deriving Drude Theory from Plasma Fluid Equations

Does anyone have experience in looking at Drude theory from the perspective of plasma physics instead of the standard, condensed-matter, "electrons in a metal" sort of thing and can point ...
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1answer
71 views

Definition for long range entanglement (LRE) by generalized local unitary (gLU) and generalized stochastic local (gSL) transformations

I am studying this book: Quantum Information Meets Quantum Matter -- From Quantum Entanglement to Topological Phase in Many-Body Systems (https://arxiv.org/abs/1508.02595). In chapter 7, it introduces ...
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27 views

Photon rate definition in input-output formalism: why such definition commonly used?

I consider a one dimensional waveguide. I study free field propagation on it. I apply periodic boundary condition with periodization length $L$ to describe the physics with Fourier series and not ...
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36 views

What are some good resources to learn accretion processes around black holes?

I am interested in accretion processes around black holes and so I am looking for some comprehensive resources aimed at beginning graduate level. I came across two review papers, Foundations of Black ...
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20 views

How to get algebraic PSG solutions once we got the constraints?

The question is more technical than conceptual. I've been trying to understand the classification of spin liquids as done by Prof.Wen. I have got the constraints on IGG(Invariant gauge group) elements ...
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1answer
103 views

Input-output theory: interpretation of the final expression

I am trying to understand this paper- https://journals.aps.org/pra/abstract/10.1103/PhysRevA.30.1386 I will try to give my understanding of the paper first. We start with the quantum Langevin ...
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1answer
106 views

Metal-insulator transition a quantum phase transition?

One can consider two main types of metal-insulator transitions (MIT), nl. interaction-driven (Mott) or disorder-driven (Anderson-Mott). Recently, I have been reading that these MIT might also have ...
3
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1answer
72 views

Constructing W-algebras

I am following the algorithm in W-algebras with two and three generators, in order to construct consistent (anti-)commutator relations for a particular W-algebra. I am considering $W(2,4,4)$ where ...
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89 views

Origin an realization of 2D magnetic materials

Recently, I encountered 2D magnetic materials. At first, I was a little bit surprised by the fact that one can have a 2D magnetic material because I thought of Mermin-Wagner's theorem, which states ...
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92 views

How many Anyons can be allowed in a state

For fermions, a state allows only one fermion to exist . For bosons, there can be infinite number of bosons in one state . But for anyons, how many can a state allow?How do we come to this conclusion?
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1answer
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What are the efficient ways of reading a physics research paper, understand and come up with new ideas? [closed]

I am planning to do research in theoretical particle physics and phenomenology. But as opposed to reading a textbook, I find that understanding journal papers to complete satisfaction could be quite ...
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0answers
40 views

Bit threads as noisy quantum channels

In literature on the holographic duality, recently a new way of looking at the Ryu-Takayanagi formula has been presented, where the minimal surface area has been replaced by the maximum number of "bit-...
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133 views

Where do theta terms live?

Consider a gauge theory with group $G$. The canonical kinetic term for the gauge field is $F\wedge\star F$ and, depending on the dimensionality of spacetime, there are other allowed terms, such as ...
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79 views

Gauge group R and U(1) and a global symmetry

In the beautiful paper by Harlow et Ooguri, they write in section 2.1 about this action $$ S=-\frac12 \int_M F_a \wedge \star F_b \delta^{ab}\;, $$ with index $a=1,2$. They say that if the gauge ...
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39 views

dS/CFT in a positive curvature universe

Since Maldacena ground breaking theoretical discovery, have there been any succesfull efforts to try to transpose the AdS/CFT duality to our universe (not an AdS)?
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34 views

What is the role of metric transitivity in statistical mechanics?

I was reading a paper of E.T. Jaynes 'Information Theory and Statistical Mechanics'. There he mentions the following principle in the section 'Application to Statistical Mechanics': The link to paper ...
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1answer
216 views

Isn't Big Bang theory a violation of law of conservation of linear momentum?

What Big Bang theory assumed in the formation of universe? Answer:-At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion ...
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45 views

If a particle can exert a force on itself,then can we define a whole lot of newtonian mechanics corresponding to it?

I think that it may be a broad question to be answered but if small amount of discussion is possible then it would be very helpful for all of us. Basically,I asked a question on this website a few ...
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102 views

Calculate the matrix size for ground states BEC using difference with Gross–Pitaevskii equation

The Ground states BEC at $0$ temperature can be described by Gross–Pitaevskii equation as $(-\frac{\hbar^2}{2m}\nabla^2+V(r)+g|\psi|^2)\psi(r)=\mu\psi(r)$ We limit the BEC in 2D where $V(r)=\frac{1}{...
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1answer
186 views

What classifies gaugings?

Gauging a global symmetry $G$ introduces several free parameters to the theory. For example, In $d=4$, gauging a simple and simply-connected Lie group introduces a coupling constant and a theta term, ...
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21 views

Comparision of using two dimensional mode or one dimensional in case of optical data transmission

Many works have been done to increase capacity of optical communication. I saw that some researcher using 1-D mode ,some 2-D to implement their device.The reson of using 1-d/2-d beacuse of their types ...
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1answer
18 views

What is the relationship of optical mode and data?

This question is on the plot of mode division multiplexing system where it is said capacity crunch can be solved using mdm technique. Now, we know single mode fiber can transmit upto 1Tbps. Now if i ...
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2answers
82 views

By how much are various dibaryon states unbound?

It has been known for a long time that the deuteron is stable but the dineutron (nn) and diproton (pp) are not. Many textbooks comment on this, but all the ones I found so far do not give quantitative ...
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2answers
724 views

Lindblad and Input-Output Formalism in Quantum Optics

I'm confused about how to apply the Lindblad formalism and the input-output formalism in practice, and how one goes between the two. Suppose I have a cavity (C) coupled to a reservoir (R), with the ...
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1answer
173 views

How many times do solar protons repeatedly fuse and fission before they form deuteron

In the proton-proton chain reaction in the Sun, the first step is $$p + p \rightarrow \; ^2_2{\rm He} .$$ After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
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1answer
383 views

How does physics research work? [closed]

I am going to try and be as short and as concise as possible. I was thinking these last few days about how we're still trying to discover a unified Theory of Everything. The question is: how is this ...
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0answers
51 views

Vandermonde determinant factor in supersymmetric gauge localisation computation

I am trying to learn supersymmetric localisation computation in which the path integral of a supersymmetric gauge theory (placed on a sphere) can be localised exactly to a BPS configuration ...
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0answers
87 views

How exactly does a spin TQFT depend on the spin structure?

Take a spin Chern-Simons TQFT, such as $U(N)$ or $SO(N)$ with odd level. Such system depends on the spin structure of the underlying manifold. But how exactly does the theory depend on the spin ...

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