Related papers: Kaon decays shedding light on massless dark photon…
Kaon excitations (kaonic modes) are investigated in hyperonic matter, where hyperons ($\Lambda$, $\Sigma^-$, $\Xi^-$) are mixed in the ground state of neutron-star matter. $P$-wave kaon-baryon interactions as well as the s-wave interactions…
Kaon physics provides a unique opportunity to identify new flavour and CP violating interactions beyond the Standard Model (SM). In the SM, implied by the hierarchical structure of the CKM matrix and the GIM mechanism, flavour changing…
New results from the NA48 experiment on kaon and hyperon decays relevant to |V_us| are reported here. For charged kaons we present measurements of BR(K+- -> pi0 e+- nu) and BR(K+- -> pi0 mu+- nu). On neutral kaon decays we report the…
We entertain the possibility that scalar leptoquarks (LQs) generate consequential effects on the strangeness-changing decays of hyperons and kaons involving missing energy carried away by a pair of invisible fermions. Although such…
The KOTO experiment is a particle physics experiment located in J-PARC, Japan, aiming to explore physics beyond the Standard Model by measuring the branching ratio of the $K_L\rightarrow\pi^{0}\nu\bar{\nu}$ decay. This decay has not yet…
Recent results from the NA48/1 and NA48/2 experiments at the CERN SPS are presented. NA48/2 carried out data taking in 2003 and 2004 collecting charged kaon decays: branching ratios and form factors have been measured for the rare K+- to…
We consider decays of $B$ and $K$ mesons into a pseudo-scalar or vector meson plus missing energy. Within the SM, these modes originate from flavor changing neutral current (FCNC) processes with two neutrinos in the final state. In this…
We report measurements of B meson decays to two kaons using 250/fb of data collected with the Belle detector at the KEKB asymmetric energy e+ e- collider. We find evidence of signals in B+ -> K0(bar) K+ and B0 -> K0 K0(bar) with…
The new experimental data of kaon photoproduction on the nucleon, gamma p -> K+ Lambda, have been analyzed by means of a multipoles model. Different from the previous models, in this analysis the resonance decay widths are constrained to…
The rare decays $\mathrm{K}^+\to \pi^+ \nu \bar{\nu}$ and $\mathrm{K_L}\to \pi^0 \nu \bar{\nu}$ are extremely attractive processes to study flavor physics because they are both exceptionally clean from a theoretical point of view. These…
The availability of high-intensity kaon beams at the J-PARC Hadron Experimental Facility and the CERN SPS North Area, together with the abundant forward production of kaons at the LHC, gives rise to unique possibilities for sensitive tests…
We point out kaon decays to multiple charged leptons as a novel probe of light dark particles $X$. Previously neglected channels, such as $K^+\to \pi^+ \left(XX \to 2(e^+e^-)\right)$, $K_L\to \pi^0 \left( XX \to 2(e^+e^-)\right)$, and…
In this paper, radiative decays $\rho^0 \to \pi^+\pi^-\gamma, \pi^0\pi^0\gamma$ ,$\phi \to K^+K^-\gamma, K^0 \bar{K^0}\gamma$ are studied systematically in the U(3)$_L\timesU(3)_R$ chiral theory of mesons. The theoretical differential…
We report a search for an invisible particle $X$ in the decay $K^0_L\rightarrow \gamma X$ ($X \to \text{invisible}$), where $X$ can be interpreted as a massless or massive dark photon. No evidence for $X$ was found, based on 13 candidate…
The Fermilab HyperCP collaboration is making precision studies of charged hyperon and kaon decays, as well as searches for rare and forbidden hyperon and kaon decays. We report here on measurements of the branching ratios of the…
Rare kaon decays via Flavor Changing Neutral Currents are discussed in the context of the CKM unitarity triangle with a particular interest in the rare kaon decays K^+ --> pi^+ nu nubar and K^0_L --> pi^0 nu nubar. New results and the…
Searches for lepton flavour violation and lepton number violation in kaon decays by the NA62 and NA48/2 experiments at CERN are presented. A new measurement of the ratio of charged kaon leptonic decay rates…
We summarize the results of two recent searches for flavor-changing neutral current, lepton-flavor violating, and lepton-number violating decays of D+, Ds, and D0 mesons (and their antiparticles) into modes containing muons and electrons.…
Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other…
We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to \pi^0 \nu \overline{\nu}$, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while…