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Questions tagged [bosons]

Bosons are integer-spin particles that obey Bose-Einstein statistics.

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Can we consider oscillation of air column in the wind instruments as phonons subject to Bose- Einstein statistics ?

A flute is a wind instrument, which could be modelled as a resonance cylinder open at both ends. Any cylinder resonates at multiple frequencies. A skilful player produces a standing wave in the flute ...
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What is the super-bunching effects of composite boson?

What is the super-bunching effects of composite boson ?
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Can we ever “measure” a quantum field at a given point?

In quantum field theory, all particles are "excitations" of their corresponding fields. Is it possible to somehow "measure" the "value" of such quantum fields at any point in the space (like what is ...
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Is possible to replace the photon as a force carrier of electromagnetic force with a sfermion-fermion relation pair model?

force carriers or messenger particles or intermediate particles are particles that give rise to forces between other particles. I read that A field’s spin is determined by how it transform if you ...
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Relation between entanglement and average number of modes that are taken by constituent particles of coboson

Let we have composite boson made of pair of fermions, and fermions are entangled with each other. The state of composite boson can be written as $ \sum_m \sqrt{\lambda_m} a^{\dagger}_m b^{\dagger}_m |...
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Indistinguishable particles and symmetrization of wavefunction

For 2 indistinguishable particles, we take the wave function to be $$\psi\pm (r_1,r_2) = A[\psi_a (r1)\psi_b (r2) \pm \psi_b (r1)\psi_a (r2) ]$$ where fermions get a - sign and bosons get a + But, if ...
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Bose condensate in 4d

Could a boson gas condensate in a hypervolume $V$ in 4D? How can I find its critical temperature and the heat capacity? In the books it just said volume $V$, it does not specify the dimension. My ...
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Can we say that bosons attract each other?

We know that bosons donot follow Pauli exclusion principle, thus they can occupy the same state. But is it equivalent to say that bosons attract each other?
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Quantum statistics from the (anti)commutation relations of the operators?

From a QFT point of view, the difference between bosons and fermions is that their creation/annihilation operators ($a^{\dagger}$, $a$ and $c^{\dagger}$, $c^{\dagger}$ respectively) obey the following ...
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What happens if we consider at the level of calculation-definition (not physically) the photon have charge $\pm$ $1$ and the electron charge = $0$? [closed]

Warning: physically you do not have to change anything, photon still remain 'photon' and electron still remain 'electron'. I'm interested configuring an behavior in particle function exchange, not ...
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119 views

Is there such a thing as an anti-boson?

Can there be an anti-boson that when interacting with normal bosons, creates matter, like when anti-matter creates energy when interacting with matter? I know that anti-particles can be considered ...
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How to calculate the spin of an atom [duplicate]

If given an atom say ${^{108}_{47}Ag}$, what is the systematic way to determine its spin so that one knows whether it is a boson or a fermion?
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What are Cooper pairs in superconductivity? [duplicate]

At low temperature how does electron become Cooper pair and why can they pass through a superconductor without resistance? Please give quantum mechanical explaination.
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Why is boson spin number related to attraction and repulsion?

The accepted answer to this question says Since the electroweak interaction is mediated by spin 1 bosons, it is the case that "like (charge) repels like and opposites attract". Another answer ...
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Chemical potential in Bose-Einstein condensation

For a Bose gas, we know that when temperature goes to zero, chemical potential also reach to zero. At $T=0$ all bosons fall into ground state and thus chemical potential is also zero at $T=0$. Also ...
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Bose gas Hamiltonian in second quantization with indefinite parity potential

In the book Bose-Einstein Condensation by Pitaevski, Lev; Petrovitch, and Sandro Stringari (Oxford University Press), the Hamiltonian for weakly interacting Bose gas reads as, $$H=\sum\dfrac{p^2}{2m}\...
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What happens during a weak interaction?

For e.g. during $\beta^-$ decay a $W^- $ boson is emitted changing an up quark to a down quark. This seems very weird to me as it looks like that up quark is not interacting with some other particle ...
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66 views

How do I know that gauge fields are bosons?

QED and the Dirac equation have field operators $\psi$ interact with a gauge field $A^{\mu}$. We identify $\psi$ as a fermionic field and $A^{\mu}$ as a gauge boson - the photon. Do we or can we ...
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Suppressed emission of composite particles

If a composite (pseudo)Goldstone boson $\phi$ emerges in a spontaneous symmetry breaking (similar to the mesons of QCD), is the emission of the $\phi$ particle suppressed in high-energy processes, i.e....
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Physics of a Second quantized Hamiltonian?

It is frequently seen that the (Bosonic) Hamiltonian $H=e a^{\dagger}a+f( a^{\dagger}a^{\dagger}+a a)$ is discussed and diagonalized using Bogoliubov transformation. My question is that what is ...
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1answer
70 views

Simulating the evolution of many-boson states

My task is to simulate the scheme presented in this paper: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.77.062316. In this question: Creating an operator for a polarizing beam splitter, I ...
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Integrals involving Bose-functions (Computational)

In short, I'm looking for some advice/literature how to deal numerically with Bose function. My physical problem is to calculate a coupled set of Self-energies, thermal loop integrals, self ...
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Definition of Ohmic bath and damping force

I have read the Wikipedia article on quantum dissipation where it is talking about the bath spectral function. The bath spectral function provides a constraint in the choice of the coefficients $...
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How are computed Branching decay modes (for Higgs boson and from a general point of view)

I would like to know how are computed the branching decay diagram, like for example with Higgs boson represented below (source): It seems there are 5 ways of decays for Higgs boson. I suppose there ...
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Two bosons having the same state — how do you know there are two?

So, suppose that photons have the same quantum state. How do we know that there are 'two' photons having the same state, rather than just one? Is there a technical way to guarantee that there are ...
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Diagonalization of Quadratic Fermionic/Bosonic Hamiltonians

I'm currently reading Quantum Theory of Finite Systems by Blaziot and Ripka, and I have a question regarding the first few pages of chapter 3. In particular, the chapter takes on the task of ...
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Frequencies associated with boson/fermion operators

For a Hamiltonian like, $$\hat{H}=\sum_{k}\hbar\omega_{k}b_{k}^{\dagger}b_{k}$$ What does it mean to say that the frequencies $\omega_{k}$ must be positive if $b_{k}$, $b_{k}^{\dagger}$ are boson ...
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Fermionic and Bosonic physical Hilbert spaces - are they actually Hilbert spaces?

Consider two identical particles $A$ and $B$. The combined Hilbert space $\mathcal{H}_A\otimes \mathcal{H}_B \newcommand{\ket}[1]{\left|#1\right>} \newcommand{\bra}[1]{\left<#1\right|} $ is a ...
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Can we have Bose condensation for bosons satisfying a dispersion relation $E=Cp^s$ $\forall$ s?

Suppose a dispersion relation $E=Cp^s$ where $C$ is a constant is known for a collection of massive non-interacting bosons. What is the way to find out whether there will be Bose-Einstein condensation ...
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Bose - Einstein Correlation

I want to study about Bose-Einstein correlations and I have been searching online for many days without any luck. Can any of you suggest me some online materials about this topic? I don't have any ...
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1answer
52 views

Hard-core bosons and fermions - spinless?

The introduction to this paper about bosonic atoms expanding in an optical lattice says the following: Are hard-core bosons mapped to spinless fermions? Because this link shows the mapping ...
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1answer
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What experiments can measure the eigenvalues of the particle exchange operator

In a system with two indistinguishable particles, the eigenvalue to the particle exchange operator $\hat{P_{ij}}$ is $+1$ if the two particles are exchange symmetric, ie. bosons, and $-1$ if they are ...
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Bogoliubov approximation, coherent states and particle number conservation

I am slightly confused about an aspect of the Bogoloibov approximation for BEC. In it we take: $$a^\dagger (\vec 0)\approx \sqrt{N_0}$$ $$a(\vec 0)\approx \sqrt{N_0}$$ and find our Hamiltonian in ...
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Why is a collection of non-interacting bosons pathological?

In this lecture titled "Disorder and Interactions: From Spin Chains to Cold Atoms" the speaker Thierry Giamarchi claims that a collection of non-interacting bosons is totally pathological. His argues ...
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Can matter/antimatter “annihilation” produce “dark matter”?

I was thinking about the following reasoning: If a matter and antimatter reaction produces energy, this energy would have particles itself. I found out (reading...) that one (the main?) product are ...
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System of $N$ bosons

What precaution needs to be observed in writing down an expression for the total number of bosons $N$ valid at low temperatures?
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Boson or Fermion

How do you deduce that an atom is a fermion or a boson? Do you determine it from the number of neutrons because "electrons and protons cancel out each other in a neutral atom"? What does this have to ...
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How do you know $W$ and $Z$ bosons are really bosons and not fermions?

It has been always said that $W$ an $Z$ bosons are bosons and not fermions but is there any experimental trial that prove that? Has anyone put two of them in the same quantum state or studies have ...
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Goldstone modes $\hat a^\dagger(k) \left|0\right>$ for small $k$ or $\hat a^\dagger(0) \left|0\right>$

Consider the Hamiltonian: $$H=\sum_{\vec k} \varepsilon (\vec k)a_{\vec k}^\dagger a_{\vec k}$$ with $\varepsilon(\vec k) \rightarrow 0$ as $|\vec k|\rightarrow 0$. I know that this has gapless ...
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Which $W$ boson is involved in electron capture?

I am learning about Electron Capture. $$p+e\to n+\nu_e$$ My question is whether the $W^+$ boson or the $W^-$ boson is involved in this transfer. I can consider this two ways: 1) Since the electron ...
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1answer
264 views

Imaginary Frequency in Bosonic Hamiltonian

I'm doing some calculations for my Thesis involving a Bosonic Hamiltonian of the form: \begin{equation} H=\sum_{\vec{k}}\alpha\ a^{+}_{\vec{k}}a^{+}_{-\vec{k}} + \beta\ a^{+}_{\vec{k}}a^{-}_{\vec{k}}...
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Does the field (force-carrying) of a gluon or boson have a magnetic-like shape? Not spherical

The challenge of force-carrying boson is that many experiments generate results that are not consistent. Hence, quantum statistics. It is established that things like 'strong nuclear interaction/...
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Two particles in a harmonical potential (indistinguishable particles)

In statistical mechanics, we are going to find the difference between the canonical partition function for distinguishable particles and indistinguishable particles. For understanding this prinicple,...
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1answer
350 views

Spin of a neutral pion

I was going through the book High Energy Physics by DH Perkins. In the decay $\pi^{0}\rightarrow 2\gamma \ (photon)$, the possible spin components of the system of photons $S_z$ can be $0$ or $2$. A ...
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1answer
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Why the $\beta^-$ decay releases $e^-+\nu_e$ and not $\tau$ or $\mu$ generations?

The $\beta^-$ decay is \begin{equation} n \rightarrow p + e^- + \bar\nu_e \tag{1} \end{equation} It can be broken down into \begin{align} d \rightarrow & \ u + W^- \tag{2}\\ W^- \rightarrow &...
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Exercise on bosonic vacuum

Consider bosonic canonical transformation, generated by operator $S = e^{\lambda (a^{\dagger})^2}$. Show, that \begin{equation} b \equiv SaS^{-1} = a - 2\lambda a^{\dagger}. \end{equation} ...
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What Makes a $W$-Boson a Gauge Boson?

I understand that in beta decay, a quark changes its flavor and emits a $W$-Boson, and this $W$ (is the W Boson virtual, by the way?) quickly decays into an electron and an electron antineutrino or ...
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47 views

Trace with Boson operators

I want to compute the following trace $$ \operatorname{tr}(\exp(-\sum_k\varepsilon_k a_k^\dagger a_k)a_i a_j) $$ with bosonic operators $a_i,a_j$. I think the result will be proportional to $\delta_{i,...
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1answer
60 views

Fock space-Weyl Algebra

I am new to quantum physics, help me out please on this question. I am confuse about how to compute the norm of the states describe below: Given the operators $a_m, a_m^{\dagger}, m=1,2,\dots, M$, ...
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What makes common matter what it is compared to, for example, Electromagnetic Fields?

Last week, I discussed with some friends (we are all Physics Students) what are the differences between photons and electrons that account for the differences between light and matter. One team argued ...