Questions tagged [bosons]

Bosons are integer-spin particles that obey Bose-Einstein statistics. Two bosons can occupy the same quantum state.

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Elementary Particle of Magnetic Field

If gravity - a field force - has an elementary particle, the graviton, why don't other field forces like magnetic fields have their elementary particles? I mean, why isn't there a magneton? Or, what ...
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commutation relations for many-body permanents

I'm interested in understanding the many-body generalization of the canonical commutation relations. I.e. commutators of the form $$ [a^\dagger_I, a_J] $$ where $I,J$ are multi-indices with the ...
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Why bosons have integer spin and fermions have half-integer ones?

Due the fact that the fermions are the "block particles" and the bosons are the "carriers" I just came out with the question that, why the "block particle" have half-integer spin and the "carriers" ...
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Qubits from fermions?

I'm confused about qubits and fermions/bosons. I would like to look at a specific example: Take an electron (which is a fermion) with its spins as a qubit system. A spin up state is the $\lvert 0 \...
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Is bosonic state space a proper subspace of the original Hilbert space on which we have an N-particle free Hamiltonian?

This question may be pretty naive. But I wanted to confirm it anyway. Also if people can tell me more about this fact, I will be grateful. I am looking at a simple problem of n-particle free ...
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The ratio between $m_W$ and decay distance of hadrons resulting from pp collision

A pp collision results in: $pp\rightarrow t\overline{t}\\ t \rightarrow bW^{+}\\ \overline{t} \rightarrow \overline{b}W^{-}\\ W^{+}\rightarrow u\overline{d}\\ W^{-}\rightarrow\overline{u}d$ From b ...
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217 views

Calculating the probability to find two bosons at the same place

I want to calculate the probability to find two bosons at the same place. Let the bosonic wave function be $$\Psi_B(x_1,x_2)=\frac{1}{\sqrt{2}}\left(\Psi_1(x_1)\Psi_2(x_2)+\Psi_2(x_1)\Psi_1(x_2)\...
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Identical particles seem to reduce probability

$\newcommand{\ket}[1]{| #1\rangle}$This question basically has two very related parts. This came up in the context of trying to verify something my professor said a while ago: that if the wave ...
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What is the wavefunction of a Bose-Einstein condensate made of composite particles?

The textbook answer is that a problem involving bosons is described by a wavefunction $\Psi(R_1,...,R_n)$ which is completely symmetric, and if non-interacting particles Bose condense, the ...
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Why are composite fermions either bosons or fermions but not neither?

The question is getting at something subtle and not necessarily obvious to me. It is often claimed that an atom being composed purely of fermions is either a boson or a fermion itself. I interpret ...
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752 views

How to obtain the Bose-Einstein distribution from the canonical ensemble?

In the wikipedia page https://en.wikipedia.org/wiki/Fermi%E2%80%93Dirac_statistics#Canonical_ensemble the Fermi-Dirac distribution is obtained from the canonical ensemble in the following manner: ...
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Are fermions and bosons fundamentally different?

Looking at various particles regarding being fermions or bosons, it seems to me that fermions are something fundamentally different from bosons. What I mean by "fundamentally different" is "as ...
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What does the symmetrization postulate mean for the decomposition of the $N$ particle Hilbert space $\mathcal{H}^N$?

Suppose you have $N$ particles, each of which can occupy any of $s$ states. In general, you can write the $N$ particle Hilbert space $\mathcal{H}^N$ as a product of $1$ particle Hilbert spaces $\...
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1answer
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What's the form of total wavefunction of Carbon-12: symmetric or asymmetric?

Considering the two electrons in 2p, is the total wave function of C-12 (anti)symmetric under particle exchanging in it's ground state? What about other states?
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Bosonization and Commutation Relation

I'm playing a bit with bosonization $ψ→:e^{-φ}:$ and $ψ^*→:e^{φ}:$ in the sense that $$ \Bigg\langle 0_\mathrm{F} \Bigg|∏_{i=1}^nψ(z_i)ψ^*(w_i)\Bigg|0_\mathrm{F}\Bigg\rangle = \Bigg\langle 0_\mathrm{...
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Is it possible to compute the kubo conductivity of bosons in disorder via mean-field theory?

The kubo conductivity is computed essentially from the current-current correlation function. This works fine when there is no or a periodic potential, as there are a number of ways that can be found ...
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1answer
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Are there bound elementary bosons

I know that a pion can take place of an electron in an atom, but pion is not an elementary boson, but a particle made of constituents. However, my question regards elementary particles. Are there ...
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1answer
890 views

Where this polarization vector is coming from?

When dealing with vector fields in his QFT book, Schwartz writes the classical field in terms of a basis which I don't know how he is getting. He first introduces the Proca Lagrangian $$\mathcal{L}=-...
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Why zero chemical potential does not allow the Bose-Einstein Condensation of Phonons?

Here I report the reasoning from which my question comes. According to: O.V. Misochko, Muneaki Hase, K. Ishioka, and M. Kitajima. Transient bose–einstein condensation of phonons. Physics Letters A, ...
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1answer
475 views

Finding states of a system of 2 identical bosons (including spin)

I'm trying to find the ground state and first excited state for 2 identical bosons in an infinite square well. I know that both states are degenerate and the spatial and spin parts of the wave ...
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794 views

Meson wave function

I have a basic question about pseudoscalar mesons wavefunction. As I understand it, mesons are bosons so they have a total symmetric wavefunction under exchange of particles. For pseudoscalar mesons,...
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1answer
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What do $SU(N)$ Dynkin labels say about a multi-component bosonic wavefunction?

Suppose you have a system of A bosons of $N$ different types, each of which can be in different angular momentum orbitals. We define the creation operator of a boson of type $a$ with angular momentum $...
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Bose occupation factor

I am a novice to Bose-Einstein statistics. What is the Bose occupation factor? I understand the terms of statistical mechanics as I am familiar with the Maxwell-Boltzmann statistics.
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1answer
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Understanding concepts of $N$ identical particles

I'm uncomfortable with the concepts of $N$ number of identical fermions and identical bosons and their degeneracies and energies. For example, lets say we a have a 3-dimensional isotropic harmonic ...
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Fields: Bosons vs Fermions

Reading Student Friendly Quantum Field Theory by Robert Klauber and he made me realize I've taken as fact for some time that bosons are the "force carriers" in QFT, without really understanding fully ...
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92 views

Extracting the probabilities of single-particle energy measurements from a multi-particle configuration state

I need help understanding how to do a quantum particle-statistics problem, based on the Example 5.4.1 in Griffiths' Introduction to quantum mechanics. Let's say that I have 3 identical particles in a ...
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1answer
344 views

Is a Gravastar more dense than a Neutron Star?

Given: A Neutron star is the collapsed core of a larger star; Models for Neutron stars suggest they are composed almost entirely of neutrons; And if: Bose-Einstein condensates are extremely dense ...
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1answer
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Integral spin and half integral spin

I am reading a book (Laudau and Lifshitz, Vol. 4, page 94) and it derived why spin-0 should obey Bose quantization and spin-1/2 should obey Fermi Quantization. Then it says, all integral spin ...
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I'm confused. Is electromagnetism a matter field or a force field… or both? [closed]

The question is based on this video. It says that photons (which are matter based) are formed by exciting the electromagnetic field. Then it says that bosons are based on force fields, which are the ...
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Canonical quantization of bosons

During my studies on QFT a fundamental question occurred concerning the canonical quantization. In our course, we mentioned that: "The canonical quantization of a field with values in the complex ...
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945 views

Why are He-4 nuclei considered bosons, and He-3 nuclei considered fermions?

Why are helium-4 nuclei considered bosons, while helium-3 nuclei are considered fermions? From the Wikipedia page on Identical Particles: Examples of bosons are photons, gluons, phonons, helium-4 ...
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Can quarks of different generations enter a $Z$ boson vertex?

Reading through my particle physics book (Thomson's "Modern Particle Physics"), it appears that when calculating the possible decays of the $Z$ boson, we do not consider decays such as $Z\rightarrow u ...
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1answer
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How to evaluate this weird delta-function like sum

In the process of computing the two-point function for a free boson system, I have been led to the following sum that I'm not sure how to evaluate: $$\sum_{\vec{k}}e^{i(\vec{k}\cdot\vec{x}-\frac{\vec{...
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$N$ copies of 1D bosonic harmonic oscillator partition function

I am trying to understand the partition function of $N$ copies of 1D bosonic harmonic oscillator. $$ Z_N{}^B = q^{\frac{N}{2}} \prod_{n=1}^N \frac{1}{1-q^n}\quad\text{ with }\quad q=e^{-\beta \hbar w}....
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2answers
941 views

Partition function for classical indistinguishable particles and Bose particles

We have two particles that can be in either level $E_0 = 0$ or in level $E_1$. If we treat them as Bose particles, then the partition function will be: $$ Z = 1 + e^{-\beta E_1} + e^{-2\beta E_1}, $$ ...
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Can all types of particle be created in quantum fluctuation?

In quantum / vacuum fluctuation, a pair of virtual particles is formed. But can all different types of particles be created, both virtual fermions and virtual bosons? For example electrons, quarks, ...
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1answer
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Time of flight images of Bose-Hubbard model

on the website of Immanuel Bloch, you can find time of flight images of bosonic particles inside an optical lattice for different values of the depth of the lattice. (http://www.quantum.physik.uni-...
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Does the top quark decay into an on-shell W boson?

Considering that the top/truth quark is the only quark with higher mass than the massive bosons, is the W boson in its decay different than the off-shell bosons that mediate the weak decay of other ...
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Finding the state and wave-function for two identical spin-1 bosons trapped in one-dimensional harmonic oscillator

My question concerns the validity of my approach to a problem and wether the answer is correct. I am tasked with writing the state vector(s) and wave-function(s) for when two identical spin-1 bosons ...
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2answers
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Could new massive bosons (“Massive Photons”) explain the dark matter mystery?

I saw a news from an official MIT website about a hypothesis proposed by MIT scientists which "massive photons" could be the sources of dark matter. They've also proposed an experiment for proving ...
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Is dark energy made by bosons? [closed]

Theoretically speaking, would dark energy be made by bosons or similar particles or by a completely new type of particles?
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Can we regard a spin-1 particle as combination of two spin-1/2 particles?

As we know, the square of time-reverse operator is -1 acting on fermion and +1 on boson. I can prove it by regarding the time-reverse operator as 2π rotation around $y$-axis multiply the complex ...
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Why does the weak interaction not conserve the flavour quantum number? [duplicate]

The weak interaction, in contrast to the strong and electromagnetic, is the mediator of the decay of the strange quark, purely because the weak interaction is 'allowed' to break conservation of ...
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Product of expectation values for multimode operators

If $A_{n}, B_{n'}, C^{\dagger}_{n''}, D^{\dagger}_{n'''}$ are multimode field operators that obey the bosonic commutation relations, under which circumstances the product of expectation values $\...
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How to relate the number of bosons (fermions) with the number of vertices and external (internal) bosons (fermion) lines?

I am following the QCD book: "QCD: Renormalisation for the Practitioner" by P. Pascual, R. Tarrach. In chapter 3, page 64, equation III.13 they relate the following quantities: Let us consider a ...
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1answer
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Showing phase change for fermions

When discussing identical particles books often use that the states are eigenstates of the permutation operator: $P_{ij}|\psi\rangle = \lambda |\psi\rangle$ for bosons this is easy to see if I use ...
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Capturing superfluid condensation with exact diagonalization

Doing exact diagonalization on bosonic systems is tricky, because the possibility of multiple occupancy means that even the single-site Hilbert space is infinite-dimensional. It's my understanding ...
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Can fermions composing a boson ignore Pauli's principle?

After a discussion with a fellow student, we came above this problem asked as question in the title. A similar question was answered here. But it doesn't answer the question for us. In a BEC, many, ...
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Clarification of the concept of Boson Mediator and 'Mediation' in Physics? [closed]

I would like to have a clear concept of Higgs 'mediator' and that 'mediation' speak in physics, what you 'swap' a particle with ...
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1answer
695 views

What does it mean that a Cooper pair behaves as a boson but respects the obligations of fermions?

I refer to the fact that it has integer spin, but antisymmetric wavefunction. How is this possible?