Related papers: Eta Decay and Muonic Puzzles
The mass and decay width of the $\phi$ meson in cold nuclear matter are computed in an effective Lagrangian approach, with the medium dependence of these properties obtained by evaluating kaon-antikaon loop contributions to the $\phi$…
We present evidence for the existence of a light scalar particle that most probably couples exclusively to gluons and quarks. Theoretical and phenomenological arguments are presented to support the existence of a light scalar boson for…
A search is presented for a new scalar resonance, X, decaying to a standard model Higgs boson and another new scalar particle, Y, in the final state where the Higgs boson decays to a $\mathrm{b\bar{b}}$ pair, while the Y particle decays to…
Flavor-specific scalar bosons exist in various Standard Model extensions and couple to a single generation of fermions via a global flavor symmetry breaking mechanism. Given this strategy, we propose a MeV flavor-specific scalar model in…
We investigate the pp --> pp eta and pn --> pn eta reactions within an effective Lagrangian model for laboratory kinetic energies ranging from very close to eta meson production threshold to about 10 GeV. Production amplitudes include…
Since its discovery in the 1930s, the muon has played an important role in our quest to understand the sub-atomic theory of matter. The muon was the first second-generation standard-model particle to be discovered, and its decay has…
An inclusive search for long-lived exotic particles decaying to a pair of muons is presented. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV in 2016 and 2018 and…
Muon colliders offer special opportunities to discover and study new physics. With the high intensity source of muons at the front end, orders of magnitude improvements would be realized in searches for rare muon processes, in deep…
We present a model explaining both the 4.2 $\sigma$ muon $g-2$ anomaly and the relic density of dark matter (DM) in which DM interacts with the Standard Model (SM) via a scalar portal boson $\varphi$ carrying both dark and SM leptonic…
A model-independent search for low-mass resonances decaying into pairs of oppositely charged muons is presented. The analysis uses proton-proton collision data corresponding to an integrated luminosity of 140 fb$^{-1}$, recorded by the…
The anomalous results of recent measurements on various $b\to s\mu^+\mu^-$ processes could be initial evidence of physics beyond the standard model (SM). Assuming this to be the case, we entertain the possibility that the underlying new…
We calculate new constraints on extra neutrino interactions via light Abelian vector bosons, where the boson mass arises from Stuckelberg mechanism. We use the requirement that $Z$, $W$, and kaon decays, as well as electron-neutrino…
Experimental searches for fifth forces coupled to muons are fundamentally limited by the scarcity of muons in ordinary matter, whereas neutron stars contain abundant muon populations. We show that these compact objects therefore provide…
We obtain mass limits on the extra neutral gauge boson which is predicted in a model with hidden gauge symmetry and dynamical breaking of the electroweak symmetry by a top quark condensate. For typical model assumptions, present LEP data…
One of the objectives of the vast physics programme of the recently comissioned WASA-at-COSY facility is the study of fundamental symmetries via the measurements of the eta and eta-prime mesons decays. Especially interesting are isospin…
Rare decays of light mesons may be a discovery window for a new weakly coupled forces hidden at low energy QCD scale. BES-III Collaboration reported the observation of the rare decay $\eta'\rightarrow\pi^0\gamma\gamma$. The observed decay…
The isoscalar $\eta$ and $\eta'$ mesons are special in QCD, being linked both to chiral symmetry and to non-perturbative glue associated with the axial anomaly. The properties of these mesons in medium are sensitive to how these dynamics…
A first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model $\tau$ lepton. The pseudoscalar boson is assumed to have a mass below the $\tau^+\tau^-$ threshold, so that…
We point out that heavy new physics contributions in leptonic dipole moments and high-energy cross-sections of lepton pairs into Higgs bosons and photons are connected model-independently. In particular, we demonstrate that a muon collider,…
We study the \egg, \egm and \epg decays using an extended three-flavor Nambu-Jona-Lasinio model that includes the 't~Hooft instanton induced interaction. We find that the $\eta$-meson mass, the \egg, \egm and \epg decay widths are in good…