A Weak-Isospin-Based Resolution of Particle-Antiparticle and Baryon Asymmetry Problems

One of the important unresolved problems in modern particle physics and cosmology is the particle–antiparticle asymmetry problem and the baryon asymmetry problem.

Mainstream research has devoted substantial effort to finding baryogenesis or leptogenesis mechanisms that can explain how the net baryon asymmetry observed in the present Universe was generated in the early Universe.

Here, we approach the problem from a different perspective. Before searching for mechanisms that generate the asymmetry, the field should first have asked a more fundamental question:

Is there a physical criterion that determines the particle–antiparticle orientation consistently across different particle species?
And is it correct to place the proton, neutron, and electron in the same particle sector?

The proton–antiproton, neutron–antineutron, and electron–positron pairs are all well-defined charge-conjugate pairs. However, the conventional particle–antiparticle classification does not provide a universal physical principle that determines which orientation across different species should be assigned to the common “particle side.”

We therefore look for a species-level physical criterion that determines the particle–antiparticle orientation in the structure of the weak interaction, and examine whether this criterion can provide a new way to address the particle–antiparticle and baryon asymmetry problems.


1. A New Classification Based on Weak Isospin

In the Standard Model, left-handed fermions form weak-isospin doublets:

We therefore define a new classification quantum number N by

N_f = 2T_3L(f_L)

and classify states according to

N>0: particle, N<0: antiparticle, N=0: N-neutral state.

Here, N is a species-level quantum number defined by the weak-isospin orientation of the left-handed component.
Thus, the electron is assigned

N(e)=−1,

including its right-handed component as part of the same physical species.

This does not mean that T_3L(e_R)=−1/2. In the Standard Model, e_R is an SU(2)_L singlet.

If N is extended to an exact additive charge acting directly on both chiralities, a possible left–right symmetric completion is

N=2(T_3L + T_3R)

For composite nucleons, the constituent N values give

N(p) = u + u + d = (+1)+(+1)+(−1) = +1,

and

N(n) = u + d +d = (+1)+(−1)+(−1) = −1.

Thus, in the weak-isospin classification, the proton and neutrino are particles, whereas the electron and neutron are antiparticles.

2. N Is Conserved in Physical Processes

Consider neutron beta decay,

n → p + e− + ν̅ₑ.

The initial state has

N(n)=−1

while the final state has

N(p) + N(e−) + N(ν̅ₑ) = (+1) + (−1) + (−1) = −1.

Therefore,

ΔN=0.

The same conservation appears in the stellar proton–proton chain,

p + p → d + e+ + ν_e.

Since

N(d) = N(p) + N(n) = 0,

we have

N_initial=+2, N_final=0 + 1 + 1 = +2.

Thus, N conservation appears in weak processes and stellar fusion: ΔN=0.

3.The Particle-Antiparticle Asymmetry Problem

Let us define the abundance differences of the principal species as

The positive proton, neutron, and electron abundance differences correspond to the observed matter composition of the Universe.

A positive neutrino–antineutrino asymmetry has not yet been directly observed. However, global N-symmetry gives

δν=δn,

and the same relation follows in an electrically neutral Universe under the conventional cosmological condition

B−L=0.

Since δn is positive,

δν>0

is a theoretically derived and observationally testable relation.

4.In the Conventional Standard Model Classification, This Appears as a Particle–Antiparticle Asymmetry

In the conventional Standard Model classification, the proton, neutron, and electron are all placed on the matter or particle side.

Therefore, a present state with

δp > 0, δn > 0, δe > 0

appears to be a Universe in which particles overwhelmingly dominate over antiparticles.

In particular, the proton and neutron both carry conventional baryon number

B=+1,

so the nucleon sector has a net baryon excess,

δB ∼ δp + δn > 0.

This is the baryon asymmetry problem of the Standard Model.

5.The Situation Changes in the Weak-Isospin Classification

In the new classification,

N(p)=+1, N(ν)=+1,

while

N(n)=−1, N(e−)=−1.

Thus, the principal particles abundant in the present Universe do not all belong to the same sector.

The total N can be written as

N_tot = δp − δn − δe + δν,

or equivalently,

N_tot = (δp − δe) + (δν − δn).

Electric neutrality gives

δp = δe,

while global N-symmetry gives

δν = δn.

Therefore,

N_tot = 0.

Hence, the present Universe may satisfy

δp>0, δn>0, δe>0, δν>0,

while simultaneously satisfying

N_tot = 0.

Thus, a Universe that appears overwhelmingly particle-dominated in the conventional Standard Model classification corresponds, in the weak-isospin classification, to a global particle–antiparticle symmetric state in which the positive-N and negative-N sectors cancel each other.

*Starting from the initial symmetric state,

δp = δn = δe = δν = 0 ,

how can we generate the asymmetric state of the present Universe,

δp > 0, δn > 0, δe > 0, δν > 0 ?

In the following post, I will explain a mechanism that can generate this asymmetry.


#paper
A Weak-Isospin-Based Resolution of Particle-Antiparticle and Baryon Asymmetry Problems

Edited 15 hours ago15 hr by icarus2

It's not clear to me that you have truly resolved the matter-antimatter asymmetry. You may have shown a cosmological balance with regards to isospin, but it is not clear that this is the same as a matter-antimatter balance. For example, there is still a cosmological imbalance between protons and antiprotons. You can't get around this imbalance by claiming a balance between protons and electrons because there are still antiprotons and positrons to consider. There appears to me to be a disregard of the fact that each type of particle has its own particular antiparticle, and that the balance between matter and antimatter is not simply a matter grouping particles into matter and antimatter categories.

I've often seen it said that the asymmetric decay of neutral kaons and neutral antikaons might resolve the matter-antimatter asymmetry. But this doesn't seem possible to me because neutral kaons and neutral antikaons are both mesons that consist of a quark and an antiquark, and therefore are neither matter nor antimatter. This means that neither the neutral kaons nor the neutral antikaons are going to decay into an imbalance of matter or antimatter, even if the decay of neutral kaons and neutral antikaons is not symmetric.

6.One Possible Mechanism for Generating the Species-Level Asymmetries

The remaining question is how an initial state with

δp = δn = δe = δν = 0

could evolve into the positive abundance orientations observed today.

δp > 0, δn > 0, δe > 0, δν > 0.


A representative candidate transition is

n̄ → p + e− + ν_e.

This process satisfies

N(n̄)=+1

and

N(p)+N(e−)+N(ν_e)=(+1)+(−1)+(+1)=+1

so that

ΔN=0.

A single transition removes one antineutron and produces one proton, one electron, and one neutrino. Therefore,

(δp, δn, δe, δν) = (+1,+1,+1,+1).

Thus, a single transition changes all four abundance differences in the direction required for the present Universe.

The process changes the conventional baryon and lepton numbers according to

ΔB=ΔL=+2,

while

Δ(B−L)=0, ΔN=0.

The |ΔB|=2 decay channel considered here does not exist in the renormalizable Standard Model. However, it can arise in models beyond the Standard Model.

**********
The important point is that this process preserves ΔN=0, and is therefore allowed within the weak-isospin N framework.
**********

7.A Decay-Rate Asymmetry Can Select the Abundance Orientation
The CP-conjugate process that produces the opposite species-level orientation is

n → p̄ + e+ + ν̄ₑ.

Let the two partial decay rates be

Γ_+ = Γ(n̄ → p + e- + ν_e),

and

Γ_− = Γ(n → p̄ + e+ + ν̄ₑ).

For a symmetric initial neutron–antineutron population, if Γ_+ = Γ_−, the two effects cancel.

However, if Γ_+>Γ_−, the net effect selects

δp>0, δn>0, δe>0, δν>0.

Thus, a single CP-asymmetric particle-conversion mechanism can generate the proton, neutron, electron, and neutrino asymmetries simultaneously in the same direction.

Since the process also gives ΔB=+2, an accumulated partial-rate asymmetry in the early Universe could generate the conventional baryon asymmetry of the Standard Model.


8. 2→2 Scattering Processes May Be More Important in the Early Universe

The same transition structure also permits related 2 → 2 scattering processes, such as

n̄ + e+ → p + ν_e

and

n̄ + ν̄ₑ → p + e-.

Both processes generate the same species-level abundance orientation,

(δp, δn, δe, δν)=(+1,+1,+1,+1).

In the early Universe, such 2→2 scattering processes may have played a more important role than the corresponding 1→3 spontaneous decay.


9.How the Asymmetry Problem Changes in This Framework

In the weak-isospin-based N classification, the early Universe can begin with

N_{tot}^{initial}=0, δp = δn = δe = δν = 0

and undergo N-conserving particle conversion that produces

δp>0, δn>0, δe>0, δν>0

while still maintaining N_tot=0.

Thus, the species-level abundance asymmetry and the conventional baryon asymmetry of the Standard Model can be generated through particle conversion without creating or destroying N.

In particular, this transition family satisfies

ΔN=0, Δ(B−L)=0, ΔB=ΔL≠0.

The central idea of this framework is therefore that global N-symmetry can be preserved while conversions among different particle species generate the observed proton, neutron, electron, and neutrino abundance orientations together with the conventional baryon asymmetry of the Standard Model.

The proposed mechanism can be tested directly through searches for N-conserving 1 → 3 decay and 2 → 2 scattering channels and their CP-conjugate rate asymmetries, while cosmic neutrino asymmetry and B−L violation provide additional tests of the broader framework.

#paper
A Weak-Isospin-Based Resolution of Particle-Antiparticle and Baryon Asymmetry Problems

Edited 13 hours ago13 hr by icarus2

Strikes me as looking for any difference between particle types, and working backwards to make that difference account for matter/anti-matter inbalance.
A good 'first step'; I would prefer the reasoning to work forward, establishing a causal relation.