The unique mouse pollination in an orchid species

The Chinese orchid, _Cymbidium serratum_, is pollinated by the wild mountain mouse _Rattus fulvescens_. The flowers use both odor and colour as attractants, and provide labellum as food reward for the pollinators. The mice pollinate the flowers during their endeavour to eat the labellums

Interpretation of 750 GeV Diphoton Excess at LHC in Singlet Extension of Color-octet Neutrino Mass Model

We propose that the possible 750 GeV diphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet $\Phi$. The model generally contains $N_s$ species of color-octet, electroweak doublet scalars $S$ and $N_f$ species of color-octet, electroweak triplet $\chi$ or singlet $\rho$ fermions. While both scalars and fermions contribute to the production of $\Phi$ through gluon fusion, only the charged members induce the diphoton decay of $\Phi$. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops. We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits.Comment: 12 pages, 4 figures; v2: 13 pages, 4 figures, version to appear in EPJC, clarified a few things, updated numerical analysis using the most recent bound on color-octet fermions but without changing conclusions, corrected a mistake when quoting the branching ratio to Z gamma, added some references missed in v

Renormalization Group Evolution of Dimension-seven Operators in Standard Model Effective Field Theory and Relevant Phenomenology

We showed in a previous publication that there are six independent dimension-seven operators violating both lepton and baryon numbers ($L=-B=1$) and twelve ones violating lepton but preserving baryon number ($L=2,~B=0$) in standard model effective field theory, and we calculated one-loop renormalization for the former six operators. In this work we continue our efforts on renormalization of the operators. It turns out this could become subtle because the operators are connected by nontrivial relations when fermion flavors are counted. This kind of relations does not appear in lower dimensional operators. We show how we can extract anomalous dimension matrix for a flavor-specified basis of operators from counterterms computed for the above flavor-blind operators without introducing singular inverse Yukawa coupling matrices. As a phenomenological application, we investigate renormalization group effects on nuclear neutrinoless double $\beta$ decay. We also discuss very briefly its analog in the meson sector, $K^\pm\to\pi^\mp\mu^\pm\mu^\pm$, and indicate potential difficulties to compute its decay width.Comment: v1: 18 pages, 2 figures, 5 tables. v2: 21 pages, 3 figures, 5 tables, to appear in jhep; minor revisions made without changing results: (1) corrected typos; (2) added clarifying statements and three refs; (3) Appendix expanded by an explicit example of calculation; (4) corrected an error in eq. (13), thanks to the referee; (5) replaced fig. 2 due to a numerical proble