2021/01/26 by Svjetlana Fajfer, A. Novosel, Anja Novosel
Physics and Astronomy · #B meson #Charm (quantum number) #Colored #Dark Matter and Cosmic Phenomena #Fermion #Meson #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-ph
paper · pdf · doi:10.1103/physrevd.104.015014
published as Phys. Rev. D 104, 015014 (2021) · 8 pages, 4 figures
arxiv created 2021/01/26 · openalex created_date 2021/02/01 · openalex publication_date 2021/07/08 · arxiv updated 2021/07/14 · openalex updated_date 2026/08/05
We consider the effects of colored scalar mediators in decays c\ensuremath→u invisibles. In particular, in these processes, as invisibles, we consider right-handed fermions. The colored scalar S1\ensuremath≡(3,1,\ensuremath-2/3), due to its coupling to weak up-quark singlets and invisible right-handed fermions (\ensuremathχ), is very appealing. Then, we consider \stackrel\texttildelowR2\ensuremath≡(3,2,1/6), which as a weak doublet can couple to both up- and down-quarks and invisible fermions. We determine branching ratios for D\ensuremath→\ensuremathχ\ensuremathχ, D\ensuremath→\ensuremathχ\ensuremathχ\ensuremathγ and D\ensuremath→\ensuremathπ\ensuremathχ\ensuremathχ for several \ensuremathχ masses, using most constraining bounds.The D0\ensuremath-D0 mixing gives the most robust constraint for S1 and \stackrel\texttildelowR2 when only one down-like quark couples to invisible fermion. When \stackrel\texttildelowR2 with two nonzero Yukawa couplings is analysed, we find that the bound on B\ensuremath→K)E is very constraining. We calculate for decays mediated by S1 that branching ratios can be B(D\ensuremath→\ensuremathχ\ensuremathχ)<10^\ensuremath-8 for m_\ensuremathχ=0.8 GeV, B(D\ensuremath→\ensuremathχ\ensuremathχ\ensuremathγ)\ensuremath∼10^\ensuremath-12 for massless \ensuremathχ, while B(D+\ensuremath→\ensuremathπ+\ensuremathχ\ensuremathχ) can reach \ensuremath∼10^\ensuremath-8 for the low mass of \ensuremathχ. In the second scenario with \stackrel\texttildelowR2, we obtain high suppression of these decay rates. We find that future tau-charm factories and Belle II experiments offer good opportunities to search for such processes. Both S1 and \stackrel\texttildelowR2 might have masses within LHC reach.