Problems with Strange Hadrons
1. The Binding Energy of Strange Quarks
The following table shows energy properties of the lightest positively charged mesons and baryons that contain zero or one strange quark [1]. According to the energy conservation law, if the binding energy of a composite particle increases, then its mass decreases by the same amount. This law applies to the data described in the following table.
Table 1: Quark Dependence of Hardonic Mass
In the second row an s quark replaces the d quark of the first row. The change in the mass is described as follows:
Where 
denotes the binding energy. An analogous expression holds true for the third and the fourth rows. The difference between the pairs of rows is that the first and the second pair contain antiquarks, whereas in the third and the fourth rows, quarks replace the antiquarks of the upper pair.
The last column of table 1 shows how the mass of the particle increases as one d quark is replaced by an 
quark. The data of the first row and of the third row pertains to quarks of the 
flavor. These data show that for these quarks the 
binding energy of mesons is greater than the 
binding energy of baryons. On the other hand, the data of the last column shows that in baryons the strange quark binding energy is greater than the corresponding value in mesons.
Research topic #1: Why the relative strength of strange quark interaction behaves differently in baryons and mesons?
2. The Proton’s Antiquark population
Recent CERN experiments [2, 3] show that the proton’s anti-strange 
population is greater than the 
population by a factor of about 1.2, implying that the proton contains more 
pairs than 
pairs. The data of table 1 indicates that the quark is significantly more massive than the 
quark. A general rule of physics says, that the probability of finding lighter states is larger than that of finding heavier states.
Research topic #2: Explain why the population of the protons quark is larger than that of its quark, although the mass of the quark is larger than that of the quark.
References
[1] http://pdg.lbl.gov/2018/listings/contents_listings.html
[2] https://home.cern/news/news/experiments/how-strange-proton
[3] M. Aaboud et al., Eur. Phys. J. C, 77, 367 (2017).