Questions tagged [bosons]
Bosons are integer-spin particles that obey Bose-Einstein statistics. Two bosons can occupy the same quantum state.
291
questions
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votes
1answer
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Can multiple electron pairs be present in a single orbital?
An electron pair as a composite system acts as a boson. So why can’t three/four electron “pairs” be present in a single 1 s Hydrogen atomic orbital?
7
votes
1answer
129 views
Why can't a gas of photons reach a Bose-Einstein condensate?
I have read in many places that as the gas of photons has a chemical potential $\mu=0$ it can't reach a Bose-Einstein condensate (BEC), but I don't understand why.
I am reading Greiner's "...
3
votes
0answers
31 views
Can one combine Jordan-Wigner Transformation and Schwinger-Boson Representation?
Is it technically possible to map a fermionic problem with $M$ Orbitals to a bosonic problem with $2M$ orbitals by combining the Jordan-Wigner transformation with the Schwinger-Boson representation? ...
0
votes
1answer
33 views
Resourcs on learning about 2-body resources
As a part of my Particle Physics Course, I will need to give a talk on 2-body resonances - What are they? Some examples like 𝐽(Ψ), Z boson and significance of those discoveries. I am looking for ...
6
votes
2answers
139 views
Why are particles either bosons or fermions in spatial dimensions $d>2$ (in Wigner classification)
This questions might have been asked several times, but I haven't seen a mathematical point of view, so here it is.
Based on Wigner classfication: A particle is a representation, because any theory ...
2
votes
0answers
43 views
Dirac matrix algebra from bosonic creation/anihilation operators?
Using some generic fermionic creation/anihilation operators $a_i$ and $a_i^{\dagger}$ ($i, j = 1, 2, 3, \dots, N$) such that
\begin{align}
\{ a_i, \, a_j^{\dagger} \} &= \delta_{ij}, \tag{1} \\[...
3
votes
0answers
64 views
What is the intuitive physical difference between fermions and hard-core bosons?
(This is a soft question.)
If we work on a discrete lattice for simplicity, then ordinary bosons are characterized by creation and annihilation operators that satisfy the canonical commutation ...
4
votes
3answers
148 views
Is a pseudo-Goldstone boson always a pseudoscalar particle?
There are several examples of pseudo-Goldstone bosons which are CP-odd particles, such as the pion, as well as many axion-inspired models.
If we invert the logic,
Are all pseudo-Goldstone boson of ...
0
votes
1answer
41 views
A system of two identical non-interacting bosons, one in a stationary state with pos. parity, the other in a state with neg. parity
In a system of two identical non-interacting spinless bosons, one particle is in a stationary state $\psi_{1}(\textbf{r})$ with positive parity and another is in stationary state $\psi_{2}(\textbf{r})$...
1
vote
0answers
41 views
Symmetry of bosonic propagators and vertices under the exchange of indices
Quoting P. Cvitanovic's lecture notes on field theory:
Assumption of additivity of probability amplitudes then implies that the bosonic propagators and vertices must be symmetric under the ...
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vote
0answers
33 views
Why does probing Higgs self coupling provides information on *dynamics* of Electroweak Symmetry Breaking?
Why does probing Higgs self coupling provides information on dynamics of Electroweak Symmetry Breaking ?
Also, Why does probing Higgs self coupling provides information whether Higgs boson is ...
5
votes
1answer
393 views
Why is the normal argument for fermions/bosons wrong?
If we have a state $\psi(x_1,x_2)$ of two identical particles and an exchange operator $O$ which swaps the particles. Obviously the physics must be the same and hence $O$ can only introduce an ...
1
vote
0answers
16 views
Some questions about Dirac's sea? [closed]
Did Paul Dirac develop some way to include bosons in his formulation of the sea of particles?
I have read that both electrons and anti-electrons would follow the same Dirac equation. But could there ...
0
votes
0answers
34 views
Spin dependence of particle decay
I was wondering
How does the spin of a decaying particle influence the kinematics of the decay?
For example: I know that for a spin-0 particle decay such as
$$ \pi^0 \rightarrow \gamma\gamma $$
...
1
vote
1answer
73 views
Commutation of bosonic operators on finite Hilbert space
I'm checking this article of R. Somma
https://arxiv.org/abs/quant-ph/0512209
I understand the common commutation relations for creationd and annihilation operators, given by:
$$[b_i, b_j^\dagger]|...
0
votes
1answer
40 views
Importance of position of Bosonic and Fermionic operators in quantum mechanics
In quantum mechanics if (Fermionic or Bosonic) operators do not commute with each other, one cannot swap position of two operators easily. For example, let $(c^\dagger, c)$ are Fermionic operators, ...
0
votes
0answers
44 views
Does permutation symmetry follow the Wigner's theorem?
The permutation symmetry for boson/ferminon is
$$
P_{12} | 12 \rangle = \pm |21\rangle
$$
I may think it as a linear unitary transformation, since
$$
P_{12}^{\dagger} P_{12} =P_{12} P_{12} =1
$$
...
2
votes
2answers
85 views
What do we mean by charge in physics?
I am drawing the comparison between electrical charge and colour charge, in electric charges they communicate with (virtual) photon and photon itself is a boson carrying no charge. How about colour ...
0
votes
1answer
91 views
What are all the possible direct interactions between bosons in Standard Model?
For the bosons $g$, $\gamma$, $Z$, $W$, $H$ in the standard model, what are all of the possible direct interactions between them?
Some of the interactions I can think of are $H \rightarrow ZZ$, $HH \...
2
votes
1answer
55 views
Vertex algebra confusion
In Blumenhagen's book on CFT, the authors have defined $\bar{v}(\bar{z})$ to be the antiholomorphic part of the vertex operator for a free bosonic CFT, $V(z,\bar{z})=:\exp{(\alpha X(z,\bar{z})}):$ ...
2
votes
0answers
51 views
Why do forces have to be mediated by bosons? (Or do they?) [duplicate]
In another question, I was asking about the interaction between photons and electrons. It was suggested that in compton scattering there is no particle to "mediate" the force. The tree-level diagrams ...
2
votes
1answer
59 views
Usage of the word “gauge” in these contexts
This is probably a trivial question to someone with more knowledge than myself. I have met the word "gauge" now in the context of the gauge transformations that change the scalar and vector potentials ...
0
votes
0answers
38 views
How to calculate thermal corrected masses of Higgs and Gauge bosons?
How are the self energies of scalars and gauge bosons at finite temperature calculated in the process of determining the 1-loop resummation of Debye masses? I have seen some papers where the explicit ...
0
votes
1answer
22 views
Why do d-type bosons in the interacting boson model have angular momentum $J=2$?
I'm reading about the interacting boson model in both Wong's Introductory Nuclear Physics (1999) and Casten's Nuclear structure from a simple perspective (1990). In both books the IBM-1 model is ...
0
votes
1answer
50 views
Two-level system + bosonic field: an arbitrary choice of operators ordering leads to two different results
I encountered a situation where two seemingly equivalent choices of the ordering of operators lead, after some calculation, to two non-equivalent operator orderings.
Consider the interaction between ...
0
votes
0answers
101 views
Are results of “quantum eraser experiment” same both for particles moving at the speed of light and slower ones?
Recently I've encountered a video about the quantum eraser experiment. I was curious, if results of this experiment are the same for entangled particles moving with the speed of light and slower ones?
0
votes
0answers
29 views
Phase Fluctuations in a BKT transition
The 1D Bose-Hubbard model exhibits a BKT-type quantum phase transition along trajectories of constant density in the $\mu$ vs. $t$ phase diagram (where $\mu$ is the chemical potential and $t$ is the ...
0
votes
0answers
25 views
Converting a Fermion to a Boson by attaching proper flux
In this article the author says that a Fermion can be formally converted to a Boson if
the path of the Fermion encloses a single flux quantum $\phi_0 = \frac{h}{e}$. As the phase cancels
any ...
37
votes
1answer
5k views
Was X17 predicted before it was observed?
Articles, with very little detail, have made their rounds about an X17 boson (16.7 MeV) being observed in tests of decaying beryllium-8 and perhaps once in a test with helium.
Most of the ...
2
votes
1answer
38 views
Green function for bosons in ground state
I have to obtain a one-particle Green function for phonons at $T=0$ $$D^{0}(\mathbf{x},t)=\frac{1}{iV}\sum_{\mathbf{k}}\frac{\omega_\mathbf{k}}{2}\big(\theta(t)e^{i(\mathbf{kx}-\omega_{\mathbf{k}} t)}+...
0
votes
1answer
38 views
Why are the weak force bosons not massless
I thought all bosons were theorized to be massless. The w+and-and z bosons of the weak force are said to carry mass. Dont bosons such as the photon just pass through each other? Is that not a property ...
0
votes
1answer
21 views
Thermal harmonic oscillator as bose factor
Let us consider a harmonic oscillator $V=\frac{1}{2}m\omega x^2$ in contact with a heat reservoir. Take the partition function
$$Z=\sum e^{-\beta \hbar \omega (n+1/2)}=e^{-\beta \hbar \omega /2} \sum ...
0
votes
0answers
44 views
Why is the W boson (and none other elementary boson) the only with EM charge?
I have read this question:
Working out the charge of a W Boson
The role of W bosons in the weak nuclear force and beta decay
The W, Z, together with the photon comprise the four gauge bosons of the ...
2
votes
2answers
83 views
How to understand effective interaction in non-interacting quantum gas models (Fermi-Dirac, Bose-Einstein statistics)?
It's known that Fermi-Dirac and Bose-Einstein statistics describe non-interacting indistinguishable particles at thermodynamic equilibrium. However, if we solve some problems wtih using such ...
3
votes
1answer
48 views
Generalized commutator/anticommutator via phase factor
We know that the commutator between two operators $A$ and $B$ reads $[A,B]_{-}=AB - BA$, while the anticommutator reads $[A,B]_+=AB + BA$.
I am wondering if someone has ever used a generalized ...
1
vote
1answer
49 views
Alpha decay and Fermi-Dirac vs Bose-Einstein statistics
This article on wikipedia on alpha decay states:
One curiosity is why alpha particles, helium nuclei, should be preferentially emitted as opposed to other particles like a single proton or neutron ...
2
votes
1answer
95 views
How can multiple fermions combine to form a boson? [duplicate]
I understand that composite particles with integer spin form a boson. For example a helium nucleus is a boson because it has 2 protons and 2 neutrons.
If all of the components on their own are ...
1
vote
0answers
24 views
Swap fermion with boson?
I wonder what actions/factors/terms show up when you swap a fermion and boson that are tensored together in second quantisation. It would suffice for me if someone could give me the name of such an ...
1
vote
0answers
38 views
Strange material, Bydrogen
Let's take a hypothetical scenario in which you manage to make a meta material in which the bulk of the mass is made of by a central negative nucleus and that has a single spin 1 boson whizzing around ...
0
votes
0answers
30 views
Formation of fields with momentum operator
Ok. Weinberg says that in their QFT book Vol 1 on pages 238 and 239 that we can construct any bosonic (A,A) field from scalar ((0,0)) field if we form operator of 2A partial derivatives (momentum ...
0
votes
0answers
61 views
zero spin particles' spin states
We know that the full wave function of spin particles have two parts. One is the spin part and another is the spatial part.
Let's assume I have given a wave function which is the spatial part:
$$\...
0
votes
1answer
71 views
When a Z boson decays into a particle/antiparticle pair, do those particles instantly annihilate each other?
If you look at a Feynman diagram of neutrino-electron scattering, there is the mediation of force by means of a virtual Z boson, and the product of this interaction is just the neutrino and electron ...
1
vote
1answer
94 views
Where does the extra mass of a $W$ boson come from in particle decay?
I’ve seen everywhere explaining that it can exist because of time/energy uncertainty. I get this. I understand that’s WHY it exists but I’ve still never gotten WHERE the extra mass comes from. Is the ...
1
vote
1answer
68 views
Creation operator on coherent state and issue with commutation relations
If our bosonic annihilation and creation operators are $[a,a^\dagger] = 1$, then for any complex number $\varphi$ we can define the (unnormalized) coherent state
$$ | \varphi \rangle \equiv e^{\varphi ...
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votes
1answer
56 views
Inverse covariance matrix for a Gaussian state
I was reading an article about Gaussian Boson Sampling (https://arxiv.org/pdf/1801.07488.pdf) and following some calculation appear an inverse covariance matrix when he defines the following matrix A.
...
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0answers
18 views
Bosonic Vacuum State under Unitary Transformation
I consider a set of independent harmonic oscillators in mass- and frequency weighted coordinates and second quantization representation. The corresponding Hamiltonian reads
$
\hat{H}
=
\displaystyle\...
4
votes
1answer
91 views
Transformation of the derivative of the scalar field in Ramond's book about QFT
In the book by Pierre Ramond about quantum field theory, he explores in chapter 1.4 (p.13) the behavior of fields under Poincaré transformations. He starts by explaining that infinitesimal ...
0
votes
2answers
167 views
Why has the free boson a charge $c=1$ in 2D CFT?
In the free scalar field theory in 2D conformal field theory, we consider the correlation functions of the derivatives of the fields, i.e.
$$\langle \partial \phi(z) \partial \phi(w) \rangle, \tag{1}$...
0
votes
0answers
16 views
How to construct general multiparticle states that respect fermionic or bosonic symmetry?
Background: The arena is fixed particle number nonrelativistic quantum mechanics. The state space is $$ \mathbf{H}(1)=\mathcal H\otimes\mathcal S, $$ where $\mathcal H$ is an "orbital" state space ($L^...
0
votes
0answers
97 views
Grand Canonical derivation of Bose-Einstein and Maxwell-Boltzmann statistics
So, our professor introduced the Bose-Einstein statistics by deriving the Grand Canonical Partition function of a boson system associated to a single energy state $\epsilon_r$. So the formula is: $$\...
