Kaon Beam Research Articles

Strangeness plus-one ( S=+1 ) resonance-state P0+* via K+n→K*0p

In our current study, we delve into the peak-like structure observed during the reaction process of K+n→K0p at approximately s≈2.5 GeV. Our focus centers on exploring the potential S=+1 resonance P0+*≡P0* as an excited state within the extended vector-meson and baryon (VB) antidecuplet. To achieve this aim, we employ the effective Lagrangian method in conjunction with the (u,t)-channel Regge approach, operating within the tree-level Born approximation. We thoroughly examine various spin-parity quantum numbers for the resonance, resulting in a compelling description of the data, where MP0*≈2.5 GeV and ΓP0*≈100 MeV. Furthermore, we propose an experimental technique to amplify the signal-to-noise ratio (S/N) for accurately measuring the resonance. Notably, our findings reveal that background interference diminishes significantly within the K* forward-scattering region in the center-of-mass frame when the K* is perpendicularly polarized to the reaction plane. Additionally, we explore the recoil-proton spin asymmetry to definitively determine the spin and parity of the resonance. This study stands to serve as a valuable reference for designing experimental setups aimed at investigating and comprehending exotic phenomena in quantum chromodynamics. Specifically, our insights will inform future J-PARC experiments, particularly those employing higher kaon beam energies. Published by the American Physical Society 2024

Kaon beam simulations employing conventional hadron beam concepts and the RF separation technique at the CERN M2 beamline for the future AMBER experiment

The AMBER-experiment [2, 1], located in the North Experimental Area at CERN, is the successor of the NA58/COMPASS [11] experiment which ran from 2002-2022. AMBER will start its data taking in 2023. The experiment is served by the M2 beamline, employing secondary and tertiary beams produced by 400 GeV c -1 protons from the CERN Super Proton Synchrotron (SPS) impacting the T6 target. For the second phase of their measurements, AMBER will require high-intensity kaon beams [6, 7]. This requirement for high-intensity beams implies a need for accurate particle identification allowing tagging particles of interest that would otherwise be lost for analysis. The beam particle identification is carried out using Cherenkov (CEDAR) detectors [5], whose tagging efficiency depends critically on the beam divergence. In this paper we investigate the beam parameters required, the performance achievable with the current layout of the beamline, as well as possible improvements.

A review of the low-energy K−-nucleus/nuclei interactions with light nuclei AMADEUS investigations

The AMADEUS Collaboration conducts research aimed to experimentally investigate the low-energy K− hadronic interactions with light nuclei like hydrogen, helium, and carbon, in order to provide new constraints to the antikaon-nucleon strong interaction studies in the non-perturbative quantum chromodynamics regime. K− nuclear absorption, both at-rest and in-flight, are explored using the unique low-momentum and monochromatic kaon beam from the DAΦNE collider interacting with the KLOE detector components, a detector characterized by high acceptance and excellent position and momentum resolutions. This paper presents an overview of the AMADEUS results.

Production of dibaryon in kaon induced reactions* *Supported by the National Natural Science Foundation of China (11705056, 12175037, 11947224, 11475192, 11975245, U1832173), the Key Project of Hunan Provincial Education Department (21A0039), the State Scholarship Fund of China Scholarship Council (202006725011), the Sino-German CRC 110 "Symmetries and the Emergence of Structure in QCD" project by NSFC (12070131001), the Key Research Program

In this paper, we propose to investigate the dibaryon production in the process by utilizing a kaon beam with a typical momentum of approximately 10 GeV, which may be available at COMPASS, OKA@U-70, and SPS@CERN. The cross sections for are estimated, and in particular, the magnitude of the cross sections is evaluated to be several hundred nanobarns at GeV. Considering that the dibaryon dominantly decays into and , we also estimate the cross sections for and , where the dibaryon can be observed in the invariant mass distributions of and , respectively.

New methods to achieve meson, muon and gamma light sources through asymmetric electron positron collisions

We propose methods to produce gamma light source, muon and energetic meson beams such as charged and neutral Kaons, which are boosted to be collimated and with relatively long lifetime. The first type of method is based on asymmetric electron positron collisions with a center-of-mass energy of, e.g. 1020[Formula: see text]MeV, and Kaons can be produced at a rate of [Formula: see text]. The electron and positron beams are either asymmetric in energy, e.g. 10[Formula: see text]GeV electron beam with 26[Formula: see text]MeV positron beam, or asymmetric in space, e.g. 10[Formula: see text]GeV electron and positron beams collisions with an angle around 0.05 radius. Such proposals should be able to be achieved with a reasonable budget. The other type of method relies on TeV positron on target experiment, where Kaon beams can be achieved at around [Formula: see text] per bunch crossing. Such Kaon beams are clean with small contamination, and can have great physics potential on, e.g. hyperon searches through Kaon nuclei collision, Kaon rare decay measurement, and Kaon proton or Kaon lepton collisions. The same technique can also be extended to other final states such as pions and tau leptons.

HIKE: High Intensity Kaon Experiments at the CERN SPS

The availability of high intensity kaon beams at the CERN SPS North Area gives rise to unique possibilities for sensitive tests of the Standard Model in the quark flavor sector. Precise measurements of the branching ratios for the flavor-changing neutral current decays can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. Building on the success of the NA62 experiment, plans are taking shape at CERN for a comprehensive program that will include experimental phases to measure the branching ratio for to ∼5% and to to ∼20% precision. These planned experiments would also carry out lepton flavor universality tests, lepton number and flavor conservation tests, and perform other precision measurements in the kaon sector, as well as searches for exotic particles in kaon decays. We overview the physics goals, detector requirements, and project status for the next generation of kaon physics experiments at CERN.

Studies of low-energy K−-nucleus/nuclei interactions with light nuclei by AMADEUS

The AMADEUS Collaboration aims to provide unique experimental constraints to the antikaon-nucleon strong interaction in the regime of nonperturbative QCD. The K− nuclear captures, both at-rest and in-flight, are studied using the monochromatic low-momentum kaon beam (pK ∼ 120 MeV/c) produced at the DAΦNE collider, interacting with the KLOE detector materials. The studies are performed by reconstructing the hyperon-pion and hyperonnucleon final states. In this work a brief description of AMADEUS results for Λπ− and Λp final states is presented.

Design of beam optics for RF-separated kaon and antiproton beams in the M2 beam line of the CERN North Area

The present contribution reviews the principle of RF separation and explains its dependence on different parameters of beam optics and hardware. The first examination of potential showstoppers for the RF-separated beam implementation for Phase-2 of the AMBER experiment in the M2 beam line of the North Area is presented. Different beam optics settings have been examined, providing either focused or parallel beams inside the RF cavities. The separation and transmission capability of the different optics settings for realistic characteristics of RF cavities are discussed and the preliminary results of the potential purity and intensity of the RF-separated beam are presented. These show that a trade-off between the overall beam intensity and the share of the required particle type in the overall beam needs to be established. No showstoppers have been identified for achieving the beam parameters required for AMBER’s kaonic Primakoff reactions, kaon spectroscopy, prompt-photon production and kaon charge-radius programs. However, the high beam intensity requirements of the AMBER Drell–Yan programme cannot be satisfied with an RF-separated beam.

Searching for X_{0}(2900) and X_{1}(2900) through the kaon induced reactions

Within an effective Lagrangian approach, a theoretical study of the K^{+}p rightarrow Sigma _{c}^{++}X_{0}(2900) and K^{+}p rightarrow Sigma _{c}^{++}X_{1}(2900) reactions is carried out to search for the exotic states X_{0}(2900) and X_{1}(2900). The production process is described by the t-channel D^{-} meson exchange. The numerical results show that the total cross sections may reach up to about 0.5 nb and 25 nb for the productions of X_0(2900) and X_1(2900) , respectively. The predicted differential cross sections are sensitive to the scattering angles and have strong forward enhancements. The cross sections for the K^{+}n rightarrow Lambda _{c}^{+}X_{0,1} are also calculated and found to be larger than that in K^{+}p collisions by more than one order of magnitude. The results are helpful to the possible experimental measurements with kaon beam.

Hadron research with AMBER at CERN

The recently approved NA66/AMBER experiment (Apparatus for Meson and Baryon Experimental Research) at the CERN Super Proton Synchrotron pursues a broad research program in quantum chromodynamics. It ranges in its first phase from a precision measurement of the proton radius with a 100 GeV muon beam to investigating the quark-gluon structure of mesons in Drell-Yan processes. In a second phase, radio-frequency separated kaon beams will allow to extend such investigations to the strangeness sector.

News from the light and strange meson sector

Recent high-quality data sets from various experiments grant new insights into the excitation spectrum of light mesons, which are composed of up, down, and strange quarks. In the non-strange light-meson sector, many recent experimental and theory efforts are focused on the search for so-called exotic states, which are states beyond the na¨ıve constituent quark-model. To this end, various potential decay modes of exotic states are studied at experiments such as GlueX or COMPASS. In addition, there is recent progress in the understanding of so-called non-resonant processes, which act as background in searches for light mesons, as well as in the prediction of light mesons from lattice QCD. While the non-strange light-meson spectrum is already mapped out rather well, many predicted strange mesons have not yet been observed experimentally or need further confirmation. Recent high-precision data from experiments such as LHCb and BESIII allow us to study strange mesons in heavy-meson decays. Alternatively, strange mesons are studied in diffractive scattering of high-energy kaon beams. The so far world’s largest data set on the diffractively produced K−π −π + final state was measured by the COMPASS experiment. A recent analysis of this data covers a large variety of strange mesons over a wide mass range in a single, self-consistent analysis

J-PARC Hadron Physics and Future Possibilities on Color Transparency

The Japan Proton Accelerator Research Complex (J-PARC) is a hadron-accelerator facility that aims to provide secondary beams of kaons, pions, neutrinos, muons, and others together with the primary proton beam for investigating a wide range of science projects. High-energy hadron physics can be studied by using high-momentum beams of unseparated hadrons, which are essentially pions, and also primary protons. In this report, possible experiments are explained on color transparency and generalized parton distributions (GPDs). These projects are complementary to lepton-scattering experiments at Jefferson Laboratory (JLab), COMPASS/AMBER, and future electron-ion colliders. Thank to hadron-beam energies up to 30 GeV, J-PARC is a unique facility to investigate the transition region from the hadron degrees of freedom to the quark-gluon degrees of freedom. It is suitable for finding mechanisms of the olor transparency. Such color-transparency studies are also valuable for clarifying the factorization of hadron production processes in extracting the GPDs from actual measurements. These studies will lead to the understanding of basic high-energy hadron interactions in nuclear medium and to clarifications on the origins of hadron spins, masses, and internal pressure mechanisms.

Investigation of the low-energy K− hadronic interactions with light nuclei by AMADEUS

The aim of the AMADEUS collaboration is to provide new experimental constraints to the antikaon-nucleon ([Formula: see text]) strong interaction in the regime of nonperturbative QCD, investigating the low-energy [Formula: see text] hadronic interactions with light nuclei like H, 4He, 9Be and [Formula: see text]C. The unique low-momentum kaon beam produced at the DA[Formula: see text]NE collider is ideal to study [Formula: see text] nuclear captures, both at-rest and in-flight. The large acceptance KLOE detector, used as an active target, allows to achieve excellent position and momentum resolutions. In this work, a brief description of recent AMADEUS results is presented.

Low energy kaon-nuclei interaction studies at DAΦNE

The aim of the AMADEUS experiment is to investigate the lowenergy antikaon interaction with nucleons and nuclei, exploiting the unique lowmomentum beam of kaons produced by the DAΦNE collider at LNF-INFN, to constrain hadronic nuclear physics models in the strangeness -1 sector. As a first step the data collected in 2004/2005 by the KLOE collaboration, consisting in a complex of K−absorptions in H,4He,9Be and12C, was analyzed, leading to the first invariant mass spectroscopic study with very low momentum (about 100 MeV) in-flight K−captures. A dedicated pure Carbon target was also implemented in the central region of the KLOE detector, providing a high statistic reference sample of pure at-rest K−nuclear interaction. The first measurement of the non-resonant transition amplitude $\left| {{T_{{K^ - }n \to \Lambda {\pi ^ - }}}} \right|$ at $\sqrt s = 33$ MeV below the ${\text{\bar KN}}$ threshold is presented, in relation with the Λ(1405) properties studies.

Double exotic state productions in pion and kaon induced reactions

In the present work, we investigate the pion/kaon induced P_c/P_{cs} productions with Z_c state off proton target with an effective Lagrangian approach. Our estimations indicate that the cross sections depend on the model parameters and beam energies, in particular, the cross sections for pi p rightarrow Z_c(3900) P_c(4312) and pi p rightarrow Z_c(3900) P_c(4440) are similar and can reach up to 10 nb, while those for pi p rightarrow Z_c(3900) P_c(4457) can be 30 nb. As for Kp rightarrow Z_{cs}(3985)P_c, the cross sections are about 2.5 times smaller than those for pi p rightarrow Z_c(3900) P_c. The discussed processes in the present work, especially pi p rightarrow Z_c(3900) P_c(4457) process, may be accessible by the high-energy pion and kaon beams in the facilities of J-PARC and COMPASS.

Recent Results and Future Prospects of Kaonic Nuclei at J-PARC

$\bar K$-nuclear bound systems, kaonic nuclei, have been widely discussed as products of the strongly attractive $\bar K N$ interaction in $I = 0$ channels. Recently, we demonstrated that kaonic nuclei can be produced via in-flight $(K^-,N)$ reactions using the low-momentum DC kaon beam at the J-PARC E15 experiment. We observed the simplest kaonic nuclei, $K^-pp$, having a much deeper binding energy than normal nuclei. For further studies, we have proposed a series of experimental programs for the systematic investigation of light kaonic nuclei, from $\bar K N$ ($\Lambda(1405)$) to $\bar K NNNN$. In the new experiment approved as J-PARC E80, we will measure the $\bar K NNN$ ($A=3$) system as a first step toward a comprehensive study.

Studies for the K12 High-Intensity Kaon Beam at CERN

Studies for the K12 High-Intensity Kaon Beam at CERN

Sterile neutrino searches at tagged kaon beams

Tagged kaon beams are attractive neutrino sources, which would provide flavor pure $\nu_e$-beams with exactly measured normalization. We point out that this also leads to an anti-tagged flavor pure $\nu_\mu$-beam, with equally well known normalization. Exposing a 1 kt liquid argon detector at a baseline of 1 km to this combination of unique beams allows to decisively test recent indications by IceCube and Neutrino-4 of sterile neutrino oscillations in the multi-eV range.

KEK and its plans

There are two campuses in KEK, Tsukuba and Tokai. In the Tsukuba campus, the operation of the SuperKEKB accelerator just started with the full Belle II detector from March 2019. SuperKEKB and Belle II had been upgraded from KEKB and Belle, respectively. The luminosity exceeded 1.6× 1034 cm−1s−1 in April 2020 with lower total beam current as compared with KEKB due to smaller vertical focussing length at the interaction point (βy*). It indicates that the upgrade accelerator can provide higher luminosity with higher beam current in the near future after sufficient vacuum scrubbing. The Belle II detector is basically working well. The time-depenednt B0−B̄0 mixing was clearly demonstrated as an example. In the Tokai campus, the high intensity proton accelerator (J-PARC) has been operated for more than 10 years. The facility provides us various particle beams (pion, kaon, neutron, muon and neutrino). Several nuclear experiments have been carried out using pion and kaon beams. The T2K experiment provides some results for the CP-violation in the neutrino sector using neutrino and antineutrino beams. New project, Hyper-Kamiokande (HK) was officially approved in January 2020. The detector and the beam line for the COMET experiment (the search for the charged lepton flavor violation) have been constructed steadly to aim the run start in 2023. The material and other sciences have been performed utilizing neutron and muon beams.

Studies of kaonic atoms at the DAΦNE collider: from SIDDHARTA to SIDDHARTA-2

The DAΦNE electron-positron collider of the Laboratori Nazionali di Frascati of INFN is a worldwide unique low-energy kaon source and for this reason is suitable for low-energy kaon physics like kaonic atoms and kaon-nucleons/nuclei interaction studies. Kaonic atoms are atomic systems where an electron is replaced by a negatively charged kaon, containing the strange quark, which interacts in the lowest orbits with the nucleus also by the strong interaction. As a result, their study offers the unique opportunity to perform experiments equivalent to scattering at vanishing relative energy. This allows to study the strong interaction between the antikaon and the nucleon or the nucleus “at threshold”, without the need of ad hoc extrapolation to zero energy, as in scattering experiments. The most precise kaonic hydrogen measurement to date, together with an exploratory measurement of kaonic deuterium, were carried out by the SIDDHARTA collaboration at the DAΦNE electron-positron collider of LNF-INFN, by combining the excellent quality kaon beam delivered by the collider with new experimental techniques, as fast and precise Silicon-Drift X-ray Detectors. The measurement of kaonic deuterium will be realized in the near future by SIDDHARTA-2, a major upgrade of SIDDHARTA.