**3. Conclusions**

We performed a comparative analysis of the experimental and theoretical crosssections for the excitation of molecular hydrogen by electrons. We employed the same set of guiding principles as in our previous analogous study of the electron impact excitation of hydrogen atoms [3]. We found that presumably the most sophisticated calculations by Zammit et al. [9], using the convergen<sup>t</sup> close-coupling method involving 491 states, very significantly underestimate the corresponding experimental cross-sections.

We showed that if in some hydrogen molecules one or both atoms would be the SFHA, then the above very significant discrepancy could be eliminated. We estimated that it would take such unusual hydrogen molecules to be represented in the experimental gas in the share of about 0.26. This is about 40% smaller than the share 0.45 of the SFHA deduced by the corresponding analysis (in paper [3]) of the experiments on the electron impact excitation of hydrogen atoms (rather than hydrogen molecules). It should be emphasized that from a theoretical point of view, the share of the unusual hydrogen molecules in any experimental gas and the share of the unusual hydrogen atoms (SFHA) in any experimental gas should not be expected to coincide. Given the roughness of the above estimates, we can state that the results of the present paper reinforce the main conclusion of paper [3] of the very significant share of the SFHA in the experimental hydrogen gases. Thus, the experiments on the electron impact excitation of hydrogen molecules are the fourth type of the atomic experiments that proved the existence of the SFHA (the three previous types of

atomic experiments proving the existence of the SFHA being listed in the Introduction of the present paper).

The rough estimates provided in the present paper are intended to ge<sup>t</sup> the message across and to motivate further experimental and theoretical works on this subject.

**Funding:** This research received no external funding.

**Data Availability Statement:** All data in included in the paper.

**Acknowledgments:** The author is grateful to Prof. W. Ubachs for advising him to search for indications of the SFHA in experiments on the molecular hydrogen.

**Conflicts of Interest:** The author declares no conflict of interest.

### **Appendix A. On Using the Term "Flavor"**

Both the regular and singular solutions to the Dirac equation outside the proton correspond to the same energy. As this means the additional degeneracy, then according to the fundamental theorem of quantum mechanics, there should be an additional conserved quantity. In other words, the situation is that hydrogen atoms have *two flavors*, differing by the eigenvalue of this additional, new conserved quantity: hydrogen atoms have *flavor symmetry* [16].

It is called so by analogy with quarks that have flavors: for example, there are up and down quarks. For representing this particular flavor symmetry, there was assigned an operator of the additional conserved quantity: the isotopic spin I—the operator having two eigenvalues for its z-projection: Iz = 1/2 assigned to the up quark and Iz = −1/2 assigned to the down quark.
