The $$Z_c(3900)$$ Z c ( 3900 ) peak does not come from the “triangle singularity”

Abstract

We compare contributions from the triangle diagram and the DD * bubble chain with the processes of e + e − → J/ψπ + π − and e + e − → (DD * ) ∓ π ± . By fitting the J/ψπ maximum spectrum and the DD * spectrum, we find that the triangle diagram cannot explain the new experimental results from BESIII Collaboration at center of mass at 4.23 and 4.26 GeV, simultaneously. On the contrary, the molecular assignment of Z c (3900) gives a much better description.

Can Horndeski theory be recast using teleparallel gravity?

“…After the recent discovery of gravitational waves and specifically after the electromagnetic counterpart of GW170817, most of Horndeski's terms are severely constrained by the tensor mode propagation speed [40,41]. That is the reason why we wanted to study the Horndeski analog in the teleparallel framework, in order to see if the constrained terms in the curvature case could survive in this setting.…”

Zc(4430) and ZcNakamura1, Tsushima2 2019Phys. Rev. D

“…This is so far the most successful TS-based interpretation of charged quarkoniumlike states; Z c ð3900Þ as a TS has been disfavored in Ref. [33]. 3 First, we show that the triangle diagrams in Fig.…”

“…Meanwhile, triangle singularities (TSs) [24][25][26][27][28] have been considered to interpret several resonance(like) states such as a hidden charm pentaquark P c ð4450Þ þ [29][30][31] and a charged charmoniumlike state Z c ð3900Þ [32,33]. The TS is a kinematical effect that arises in a triangle diagram like Fig.…”

Selected topics in scalar–tensor theories and beyond

“…In this regard we recommend the book 41 -chapter 3 -that contains a compact and complete introduction to this particular issue (see also Refs. [42][43][44][45][46][47][48][49][50][51]. Another subject that is not covered in the present review is the discussion on exact cosmological solutions that is covered in detail in the book 41 as well.…”