The KOTO experiment aims to observe the CP-violating rare decay, $K_{L}\rightarrow\pi^{0}\nu\bar{\nu}$, at J-PARC.
We will present the new analysis result of $K_{L}\rightarrow\pi^{0}\nu\bar{\nu}$ search in the KOTO experiment.
In this analysis we used the data set collected in 2016, 2017 and 2018.
The data was taken with a new trigger system and a new barrel photon veto detector which had...
The decay K+→π+vv ̅, with a very precisely predicted branching ratio of less than 10-10, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+→π+vv ̅ with a decay-in-flight technique. NA62 took data so far in 2016-2018. Statistics collected in 2016 allowed NA62...
Ks->mumu is a FCNC-type decay that is very suppressed in the SM and whose properties make it very sensitive to BSM physics, independently from other similar decays, such as Kl->mumu. In this talk we will present the latest search for this channel at LHCb, which provides the world-best sensitivity and improves very significantly previous results.
The most precise measurement of the charged kaon semi-leptonic form factors obtained by NA48/2 with 4.4 million Ke3 and 2.3 million Kmu3 events collected in 2004 will be presented.
The NA48/2 experiment at CERN reports the first observation of the K± → π±π0e e− decay from an exposure of 1.7×1011 charged kaon decays recorded in 2003−2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region. The study of the kinematic space shows evidence for a structure dependent contribution in...
Precision measurements of CP violating observables in the decays of b and c hadrons are powerful probes to search for physics beyond the Standard Model. The most recent results on CP violation in the decay, mixing and interference of both b and c hadrons obtained by the LHCb Collaboration with Run I and years 2015-2016 of Run II are presented, including the first observation of CP violation in...
The KLOE-2 experiment finished data taking in March 2018 at the upgraded e+e- DAΦNE collider of the INFN Laboratori Nazionali di Frascati, collecting more than 5 fb$^{-1}$ at the center of mass energy of the ϕ meson. Together with the data sample collected by its predecessor KLOE, the total of almost 8 $^{-1}$ integrated luminosity represents the largest existing data sample in the world...
The KLOE-2 experiment at the upgraded e+e- DAPHNE collider of the INFN Laboratori Nazionali di Frascati completed its data taking campaign at the end of Mach 2018, collecting more than 5 fb$^{-1}$ at the center of mass energy of the phi-meson. Together with the data set of its predecessor KLOE, the acquired data sample of 8 fb$^{-1}$ corresponds to 2.4$\times$10$^{10}$ $\phi$-meson produced:...
The phenomenological structure of inclusive cross-sections of the production of two neutral $K$ mesons in hadron--hadron, hadron--nucleus and nucleus--nucleus collisions is theoretically studied taking into account the strangeness conservation in strong and electromagnetic interactions. Relations for the dependence of correlations of two short-lived and two long-lived neutral kaons
$K^0_S...
The J-PARC KOTO experiment aims to search the rare kaon decay $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$, which breaks CP in the FCNC process. It is sensitive to the new physics beyond the Standard Model because of the small theoretical uncertainty. The signature of $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$ is two photon clusters on the CsI calorimeter from the pion without any hit in other...
The KOTO experiment at the J-PARC research facility in Tokai, Japan aims to observe and measure the rare decay of the neutral kaon, $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$. This decay has a Standard Model (SM) predicted branching ratio (BR) of $(3.00 \pm 0.30) \times 10^{-11}$ [1]. While this decay is extremely rare, it is one of the best decays in the quark sector to probe for new physics...
The KOTO experiment was designed to observe and study the K$_{L}\rightarrow \pi^0 \nu \bar\nu$ decay at J-PARC. The Standard Model (SM) prediction for the process is (3.0$\pm$0.3) x 10$^{-11}$ with small uncertainties. This unique golden decay is an ideal candidate to probe for new physics and can place strict constraints on beyond the standard model (BSM) theories. The previous experimental...
The KOTO experiment at J-PARC is searching for the $ K_{L} \rightarrow \pi^0 \nu \bar{\nu} \ $ decay, which is one of the most sensitive probes to new physics beyond the Standard Model. Its signature is a pair of photons from a $\pi^0 \ $ decay without any additional activity in a hermetic detector system surrounding the decay region. In order to detect this highly suppressed decay, expected...
We are searching for the $K_L\to\pi^0\nu \bar{\nu}$ decay at the J-PARC KOTO experiment. This decay mode is highly suppressed in the Standard Model and its branching ratio is predicted to be $(3.0\pm0.3)\times10^{-11}$ with small theoretical uncertainties. This decay mode is thus sensitive to new physics beyond the Standard Model.
The signature of the signal events is two photons from a...
We are searching for the decay $K_L\to \pi^0\nu\bar{\nu}$ at the KOTO experiment in J-PARC. The standard model prediction for the branching ratio (BR) is $(3.0\pm0.3)\times10^{-11}$. In 2018 KOTO achieved the best upper limit to date of BR$ < 3.0\times10^{-9} (90\%\,\mbox{C.L.})$, improving by an oder of magnitude the previous limit by KEK E391a. The experimental signature is two photons from...
The recent measurements of the $\tau^-\ to K^-K_S \nu_\tau$ decay spectral function carried out with BABAR detector is described. Combining the results on $K^-K_$ mass spectrum and measurements of $e^+e^-\to K_SK_L$ and $e^+e^-\to K^+K^-$ cross sections, the isoscalar and isovector electromagnetic kaon form factors and their relative phase are derived in a model independent way. The...
Spin correlations for the $\Lambda \Lambda$ and $\Lambda \bar{\Lambda}$ pairs, produced in relativistic heavy-ion collisions, and related angular correlations at the joint registration of space-parity nonconserving hadronic decays
of two hyperons are theoretically analyzed. These correlations give important information about the character and mechanism of multiple processes, and the advantage...
The theoretical study of spin structure for the processes of lepton pair
production by pairs of $\gamma$ quanta, which may be emitted in various relativistic hadronic reactions and decays (in particular -- in the rare two-photon decays of the neutral kaons $K^0_S$ and $K^0_L$ ), is performed. For the two-photon process $\gamma \gamma \rightarrow e^+ e^-$, it is shown
that in the case of...
The theoretical study of correlations of the linear and circular polarizations in the system of two $\gamma$ quanta emitted in hadronic decays ( in particular -- in the rare two-photon decays of the neutral kaons $K_S^0$ and $K_L^0$) has been performed. The polarization of a two-photon state is described by the one-photon Stokes parameters and by the components of the correlation "tensor" in...
The features of the NA62 experiment at the CERN SPS - high-intensity setup, trigger-system flexibility, high-frequency tracking of the beam particles, redundant particle identification, and high-efficiency photon vetoes - make NA62 particulary suitable to search for long-lived, weakly-coupled
particles within Beyond the Standard Model physics, using kaon and pion decays as well as operating...
NA62 is the last generation kaon experiment at the CERN SPS aiming to study the ultra-rare $K^+ \rightarrow \pi^+ \nu \overline{\nu}$ decay.
The challenging aspect of NA62 is the suppression of background decay channels with BR up to 10 orders of magnitude higher than the signal and with similar experimental signature, such as $K^+ \rightarrow \mu^+ \nu$. To this purpose, the NA62...
In the Standard Model, fermion masses are generated by Yukawa couplings between the Higgs boson and the fermions. These couplings can be determined from measurements of Higgs boson production and decays. For example, Higgs boson production via gluon fusion and in association with a ttbar pair are sensitive to the top Yukawa coupling, and Higgs boson decays to fermions are sensitive to the...
The main goal of experiments with CMD-3 is the measurement of the cross-sections and dynamics of the exclusive
modes of e+e-->hadrons reactions. In particular, these results provide important input for the hadronic vacuum polarization function
P(q^2), which plays a central role in various issues of QCD and Standard Model, such as hadronic tensor, running electromagnetic coupling and the...
An overview of the kaon physics program of the RBC and UKQCD collaborations will be presented with a focus on the lattice calculation of K->pi-pi decay and the direct CP violation parameter epsilon'. We will describe substantial improvements to our earlier 2015 K->pi-pi calculation, including the use of three independent pi-pi interpolating operators and the results we obtain for I=0 pi-pi...
We present an updated analysis of isospin-violating contributions to eps'/eps in the framework of chiral perturbation theory, taking advantage of the different improvements in the determination of quark masses and nonperturbative parameters. The role of the different pieces entering into the analysis is carefully assessed.
We review the current status of epsilon'/epsilon within the Standard Model, discussing in detail the different ingredients that enter into the calculation of this observable. Both short-distance and long-distance contributions need to be taken into account, within a properly-defined theoretical framework. An update of the Standard Model prediction is presented and the prospects for future...
Spin correlations for the $\Lambda \Lambda$ and $\Lambda \bar{\Lambda}$ pairs, produced in relativistic heavy-ion collisions, and related angular correlations at the joint registration of space-parity nonconserving hadronic decays
of two hyperons are theoretically analyzed. These correlations give important information about the character and mechanism of multiple processes, and the advantage...
The theoretical study of correlations of the linear and circular polarizations in the system of two $\gamma$ quanta emitted in hadronic decays ( in particular -- in the rare two-photon decays of the neutral kaons $K_S^0$ and $K_L^0$) has been performed. The polarization of a two-photon state is described by the one-photon Stokes parameters and by the components of the correlation "tensor" in...
The theoretical study of spin structure for the processes of lepton pair
production by pairs of $\gamma$ quanta, which may be emitted in various relativistic hadronic reactions and decays (in particular -- in the rare two-photon decays of the neutral kaons $K^0_S$ and $K^0_L$ ), is performed. For the two-photon process $\gamma \gamma \rightarrow e^+ e^-$, it is shown
that in the case of...
The recent measurements of the $\tau^-\ to K^-K_S \nu_\tau$ decay spectral function carried out with BABAR detector is described. Combining the results on $K^-K_$ mass spectrum and measurements of $e^+e^-\to K_SK_L$ and $e^+e^-\to K^+K^-$ cross sections, the isoscalar and isovector electromagnetic kaon form factors and their relative phase are derived in a model independent way. The...
We are searching for the decay $K_L\to \pi^0\nu\bar{\nu}$ at the KOTO experiment in J-PARC. The standard model prediction for the branching ratio (BR) is $(3.0\pm0.3)\times10^{-11}$. In 2018 KOTO achieved the best upper limit to date of BR$ < 3.0\times10^{-9} (90\%\,\mbox{C.L.})$, improving by an oder of magnitude the previous limit by KEK E391a. The experimental signature is two photons from...
We are searching for the $K_L\to\pi^0\nu \bar{\nu}$ decay at the J-PARC KOTO experiment. This decay mode is highly suppressed in the Standard Model and its branching ratio is predicted to be $(3.0\pm0.3)\times10^{-11}$ with small theoretical uncertainties. This decay mode is thus sensitive to new physics beyond the Standard Model.
The signature of the signal events is two photons from a...
The KOTO experiment at J-PARC is searching for the $ K_{L} \rightarrow \pi^0 \nu \bar{\nu} \ $ decay, which is one of the most sensitive probes to new physics beyond the Standard Model. Its signature is a pair of photons from a $\pi^0 \ $ decay without any additional activity in a hermetic detector system surrounding the decay region. In order to detect this highly suppressed decay, expected...
The KOTO experiment at the J-PARC research facility in Tokai, Japan aims to observe and measure the rare decay of the neutral kaon, $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$. This decay has a Standard Model (SM) predicted branching ratio (BR) of $(3.00 \pm 0.30) \times 10^{-11}$ [1]. While this decay is extremely rare, it is one of the best decays in the quark sector to probe for new physics...
The KOTO experiment was designed to observe and study the K$_{L}\rightarrow \pi^0 \nu \bar\nu$ decay at J-PARC. The Standard Model (SM) prediction for the process is (3.0$\pm$0.3) x 10$^{-11}$ with small uncertainties. This unique golden decay is an ideal candidate to probe for new physics and can place strict constraints on beyond the standard model (BSM) theories. The previous experimental...
The J-PARC KOTO experiment aims to search the rare kaon decay $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$, which breaks CP in the FCNC process. It is sensitive to the new physics beyond the Standard Model because of the small theoretical uncertainty. The signature of $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$ is two photon clusters on the CsI calorimeter from the pion without any hit in other...
The features of the NA62 experiment at the CERN SPS - high-intensity setup, trigger-system flexibility, high-frequency tracking of the beam particles, redundant particle identification, and high-efficiency photon vetoes - make NA62 particulary suitable to search for long-lived, weakly-coupled
particles within Beyond the Standard Model physics, using kaon and pion decays as well as operating...
NA62 is the last generation kaon experiment at the CERN SPS aiming to study the ultra-rare $K^+ \rightarrow \pi^+ \nu \overline{\nu}$ decay.
The challenging aspect of NA62 is the suppression of background decay channels with BR up to 10 orders of magnitude higher than the signal and with similar experimental signature, such as $K^+ \rightarrow \mu^+ \nu$. To this purpose, the NA62...
After a brief review of some theoretical aspects and difficulties related to the calculation of rare kaon decays in the SM, I describe recent work done in the particular case of the K→ pill decay
The NA62 experiment at CERN collected a large sample of charged kaon decays into final states with multiple charged particles in 2016-2018. The sensitivity to a range of lepton flavour and lepton number violating kaon decays provided by this data set improves over the previously reported measurements. Results from the searches for these processes with a partial NA62 data sample are presented.
Rare decays are fundamental probes for physics beyond the Standard Model, and the expanding LHCb programme on strange physics provides unique and complementary information with respect to the beauty and charm sectors. Recent results of rare kaon decays at LHCb will be presented as well as prospects for strange physics with the LHCb Upgrade.
During last years quite significant statistics of kaon decays has been accumulated by “OKA” setup which is working in the 20 GeV/c RF-separated secondary $K^+$ beam of the U-70 synchrotron. About 7 billions of kaon decays have been detected. Results on several radiative decays have been obtained.
On the selected ~100K of $K_{\mu2\gamma}$ decays with $25<...
$K_L\rightarrow \pi^0 \gamma $ is forbidden by the standard model
because this decay mode threatens the Lorentz invariance and gauge principle.
There have been various experimental tests of the Lorentz invariance
using optical cavities, however, experimental tests in the high energy
regime are also useful probes of New Physics.
In spite of its interesting opportunity,
neither...
I discuss generic effects of new physics on the rare decay modes KL → π0νν̄ and K+ → π+νν̄ from the point of view of the neutrino sector. I consider left-handed neutrino couplings; right handed neutrino couplings; neutrino lepton flavour violating (LFV) interactions; and ∆I = 3/2 interactions. The first of these cases has been studied before as it covers many new physics extensions of the...
Rare decays are very sensitive probes for phenomena beyond the Standard Model, complementary to direct searches. In the Standard Model, rare decays are loop suppressed and may receive significant contributions from new particles, if these exist. Particularly interesting are b->sll transitions, which allow tests of lepton universality to be performed. Very rare decays such as B(s)->ll are...
Charged Lepton flavour violation (LVF) is a striking signature of potential beyond the Standard Model physics. Searches for LFV with the ATLAS detector are reported in channels focusing on the decay of the Higgs boson, the Z boson and of a heavy neutral gauge boson, Z', using
pp collisions data with a center of mass energy of 13 TeV
Lepton flavour violation effects are predicted in several extensions of the Standard Model (SM), including supersymmetric versions of Grand Unification Theories, at a measurable level. Since the SM background, even including neutrino oscillations and mixing, is completely negligible the observation of such effects would be a strong evidence for New Physics beyond the SM, while a non...
The PIENU experiment at TRIUMF aims to measure the branching ratio, Re/μ = Γ(π+ → e+ν(γ))/Γ(π+ → μ+ν(γ)), with 0.1% of the precision; providing the most precise test of the lepton universarity. The collaboration collected physics data during 2009--2012, and the result of...
A search for the very rare $\Sigma^+ \to p \mu^+ \mu^-$ performed within the LHCb experiment is presented. An evidence for this decay was seen by the HyperCP collaboration, with the invariant mass of the dimuon pairs surprisingly found peaking at 214 MeV/c2, leading to the hypothesis of an intermediate (unknown) particle mediating this decay (known as HyperCP anomaly).
Thanks to the copious...
Semileptonic Hyperon Decays (SHD) are interesting decays that allow to test LFV with operators not accesible to kaon decays. In this talk we will discuss the prospects of LHCb to improve the existing measurement of muonic SHD's
The interaction of antikaons with nucleons and nuclei in the low-energy regime represents an active research field in hadron physics and offers a unique tool to understand the low energy kaon-nucleus interaction at threshold. The lightest atomic systems, namely the kaonic hydrogen and the kaonic deuterium, provide the isospin dependent kaon-nucleon scattering lengths by measuring the X-rays...
The AMADEUS collaboration aims to study the K$^-$ hadronic interaction with light nuclei in the low-energy regime with high precision. The main goal is to provide information on the KbarN interaction in nuclear medium, fundamental for the understanding of the non-perturbative QCD in the strangeness sector, with implications going from nuclear physics to astrophysics. Hyperon-nucleon/nuclei...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure...
KOTO (step-I) is the first experiment with the designed sensitivity of $O(10^{-11})$ to probe for new physics through the rare $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$ decay. In 2018-2019, there were critical changes in the detector and the data acquisition system that further improved the research potential of KOTO. One of the significant changes in the detector was the dual-sided readout...
We are searching for the decay $K_L\rightarrow \pi^0\nu\overline{\nu}$ in the KOTO experiment at J-PARC. The signal is identified by detecting two photons from the $\pi^0$ decay with a calorimeter composed of undoped CsI crystals. The main background “hadron cluster background” comes from neutrons generating two clusters in the calorimeter: a neutron in the beam halo hits the calorimeter to...
Precise measurements of the branching ratios (BRs) for the flavor-changing neutral current decays $K\to\pi\nu\bar{\nu}$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both decay modes, $K^+\to\pi^+\nu\bar{\nu}$ and $K_L\to\pi^0\nu\bar{\nu}$, since different new physics models affect the rates for each channel differently....
Heavy neutral leptons (HNLs) with masses below the electroweak scale offer a testable explanation for observed masses and mixings of active neutrinos. Moreover, at the same time, they could be responsible for the generation of the baryon asymmetry of the Universe.
We describe production and decay channels of such HNLs. We demonstrate that some additional information (Dirac vs Majorana...
The high-intensity setup, trigger system flexibility, and detector performance – high-frequency tracking of beam particles, redundant PID, ultra-high-efficiency photon vetoes – make NA62 particularly suitable for searching for new-physics effects from different scenarios. We report the results of a search for π0 decays to one photon and an invisible massive dark photon. From a total of about...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has...
The features of the NA62 experiment at the CERN SPS - high-intensity setup, trigger-system flexibility, high-frequency tracking of beam particles, redundant particle identification, and
ultra-high-efficiency photon vetoes - make NA62 particularly suitable to search for long-lived, weakly-coupled particles within Beyond the Standard Model (BSM) physics.
Searches for Heavy Neutral Lepton (HNL)...
Light feebly interacting particles (axions/ALPs, HNLs, Dark Photons, Dark Scalars) represent an alternative paradigm to the current lore of strongly coupled New Physics at the TeV scale and are getting an increasing attention within the accelerator-based communities.
I will review the experimental prospects for their searches at beam dump, fixed-target, and collider-based experiments.
KAON 2019 experimental summary
