A Seventh Quark?

I don't think this conjecture is correct, but it is an interesting idea. 

The existence of a fourth flavor of down-type quark with a mass of approximately 1.6 GeV is hypothesized. The right-handed component of this quark is assumed to decay to a right-handed charm quark and a virtual W boson. Many of the recently discovered exotic charged charmonium-like resonances are re-interpreted as mesons involving the new quark.

Scott Chapman, "Charmonium tetraquarks or a new light quark?" arXiv:2204.00913 (April 2, 2022). This paper is a sequel to a March 2022 preprint by the same author.  He also submitted an unrelated preprint in December of 2021.

He is affiliated with the Institute for Quantum Studies, Chapman University, Orange, CA 92866, which is a legitimate decent sized U.S. News and World Report ranked university in Orange County, California. 

It isn't clear if this Scott Chapman is related to the individual after whom the university is named, or if that is just a coincidence. There is a Scott Chapman who is the son of Trustee C. Stanley Chapman and great-grandson of university namesake C.C. Chapman, but it seems that this professor is probably not the same person, because as of 2019, the great-grandson of C.C. Chapman ran an IT consulting business. But on the other hand, the physics professor did join the Chapman University faculty in 2019.

It also appears that the Dr. Scott Chapman who taught astrophysics at the University of Victoria and the University of Cambridge, who now teaches at Dalhousie University, and moonlights at Eureka Scientific, Inc. is a different Scott Chapman than the high energy physics physicist the Chapman University who is the author of these papers.

It also isn't entirely clear to me if the Scott Chapman who worked at the ALPHA experiment at CERN and published mostly in the areas of QCD and supersymmetry starting from 1994 is actually the same person as the author of the current paper, as the name is a common enough one. The QCD physicist Scott Chapman does not appear to be the Scott Chapman at Dalhousie University.