a0(980) physics in semileptonic D0

Abstract

The decays D 0 → dūe þ ν → a − 0 ð980Þe þ ν → π − ηe þ ν and D þ → dde þ ν → a 0 0 ð980Þe þ ν → π 0 ηe þ ν (and the charge conjugated ones) are the direct probe of the constituent two-quark components in the a AE 0 ð980Þ and a 0 0 ð980Þ wave functions. The recent BESIII experiment is the first step in the experimental study of these decays. We suggest adequate formulas for the data analysis and present a variant of ηπ invariant mass distribution when a 0 ð980Þ has no constituent two-quark component at all.

Semileptonic decays of charmed mesons to light scalar mesons

“…There are different ways in which these scalar mesons are studied globally, viz. conventional quark-antiquark states [25][26][27] and compact multiquark states including diquarkdiantiquark [28], meson-meson composite molecule [29][30][31][32][33][34][35][36][37], as well as compact structure of tetra quarks [38][39][40][41][42][43][44][45][46]. In this mass range, one can also consider the possibility of scalar glueball bound state [47,48].…”

Semileptonic D0 and D+ decays as a probe of the a0(980) nature

“…The results are shown in table 1 and figures 2, 3, 4, and 5. The data is described well, the a 0 (980) coupling constants agree with the four-quark model scenario, see [5]. In [10,11] the program of studying light scalars in semileptonic D and B decays was suggested.…”

Recent results from SND detector at VEPP-2000 collider

“…The e + e − → π + π − 4π 0 preliminary cross section measured by SND in the energy range below 2 GeV. 7 × 10 −7 90% CL was set [25]. It is three times better then the previous limit 2.3 × 10 −6 [26], but still much higher then unitary limit prediction: Br(η → e + e − ) = 1.78 × 10 −9 [27].…”