Search

This study is aimed to set severe constraints on a whole class of non-commutative space-times scenarios as a class of universality for several quantum gravity models. To this end, slight violations of the Pauli exclusion principle—predicted by these models—are investigated by searching for Pauli forbidden Kα and Kβ transitions in lead. The selection of a high atomic number target material allows to test the energy scale of the space-time non-commutativity emergence at high atomic transition energies. As a consequence, the measurement is very sensitive to high orders in the power series expansion of the Pauli violation probability, which allows to set the first constraint to the “triply special relativity” model proposed by Kowalski-Glikman and Smolin. The characteristic energy scale of the model is bound to Λ>5.6·10−9 Planck scales.

Pauli Exclusion Principle (PEP) violations induced by space-time non-commutativity, a class of universality for several models of Quantum Gravity, are investigated by the VIP-2 Lead experiment at the Gran Sasso underground National Laboratory of INFN. The VIP-2 Lead experimental bound on the non-commutative space-time scale $\Lambda$ excludes $\theta$-Poincar\'e far above the Planck scale for non vanishing ``electric-like" components of $\theta_{\mu \nu}$, and up to $6.9 \cdot 10^{-2}$ Planck scales if they are null. Therefore, this new bound represents the tightest one so far provided by atomic transitions tests. This result strongly motivates high sensitivity underground X-ray measurements as critical tests of Quantum Gravity and of the very microscopic space-time structure., Comment: 13 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:2209.00074

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.

The kaonic deuterium 2p→1s transition X-ray measurement, a fundamental information needed for a deeper understanding of the Quantum ChromoDynamics (QCD) in the strangeness sector, is still missing. The SIDDHARTA-2 collaboration is now ready to achieve this unprecedented result thanks to the dedicated experimental apparatus that will allow to obtain the values of the kaonic deuterium K-transitions with a precision comparable to the most precise kaonic hydrogen measurement to-date performed by SIDDHARTA in 2009. Both the kaonic hydrogen and kaonic deuterium X-ray spectroscopy measurements of the de-excitation towards the fundamental level are a direct probe on KN interaction at threshold, as opposed to the scattering experiments which need an extrapolation to zero energy. Combining these results through the Deser-Truemann like formula, the isospin-dependent kaon-nucleon scattering lengths can be obtained in a model-independent way. The SIDDHARTA-2 setup is presently installed at the DAΦNE (Double Annular Φ Factory for Nice Experiments) collider of Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali di Frascati and it is ready to perform the challening kaonic deuterium measurement. Thispaper provides an overview on the SIDDHARTA-2 experimental apparatus and a preliminary result of the kaonic helium run, preparatory for the SIDDHARTA-2 data taking campaign, is also presented.

Based on an integrated luminosity of 1.61 fb$^{-1}$ $e^+e^-$ collision data collected with the KLOE detector at DA$\Phi$NE, the Frascati $\phi$-factory, a search for the $P$- and $CP$-violating decay $\eta\to\pi^{+}\pi^{-}$ has been performed. Radiative $\phi\to\eta\gamma$ decay is exploited to access the $\eta$ mesons. No signal is observed in the $\pi^{+}\pi^{-}$ invariant mass spectrum, and the upper limit on the branching fraction at 90\% confidence level is determined to be ${\mathcal B}(\eta\to\pi^{+}\pi^{-}), Comment: 11 pages, 3 figures

Investigations of possible violations of the Pauli Exclusion Principle represent critical tests of the microscopic space-time structure and properties. Space-time non-commutativity provides a class of universality for several Quantum Gravity models. In this context the VIP-2 Lead experiment sets the strongest bounds, searching for Pauli Exclusion Principle violating atomic-transitions in lead, excluding the $\theta$-Poincar\'e Non Commutative Quantum Gravity models far above the Planck scale for non-vanishing $\theta_{\mu \nu}$ ``electric-like'' components, and up to $6.9 \cdot 10^{-2}$ Planck scales if $\theta_{0i} = 0$., Comment: 7 pages, 2 figures

The possible existence of deeply-bound $\bar K$-nuclear bound states, kaonic nuclei, has been widely discussed as products of the strongly attractive $\bar K$Ninteraction in I = 0 channels. Investigations of those exotic states will provide us unique information of the $\bar K$Ninteraction below the threshold, which is still not fully understood so far. Recently, we observed the simplest kaonic nuclei, $\bar K$NN, having a much deeper binding energy than normal nuclei via inflight (K−,N) reactions at the J-PARC E15 experiment. For further studies, we have proposed a series of experimental programs for the systematic investigation of light kaonic nuclei, from $\bar K$N(Λ(1405)) to $\bar K$NNNN. We will measure the $\bar K$NNN(A= 3) system at the new experiment approved as J-PARC E80, as a first step toward a comprehensive study.

VIP-2 (VIolation of Pauli exclusion principle - 2) is an underground experiment sited in the underground “Laboratori Nazionali del Gran Sasso.” It aims to investigate possible violations of the Pauli Exclusion Principle (PEP) and, in this context, Quantum Gravity models implying violations of PEP. While an upper limit of PEP violation probability is recently published, the data requires further developments of accurate analysis techniques and methods. In this contribution, we present an overview of the methodologies proposed for current and planned analysis.

The X-ray spectroscopy measurements of light kaonic atoms’ deexcitation towards the fundamental level provide unique information on the low-energy Quantum ChromoDynamics (QCD) in the strangeness sector, being a direct probe of the kaon/nucleon interaction at threshold, unobtainable through the scattering experiments. In this framework, the SIDDHARTA-2 collaboration is going to perform the first kaonic deuterium 2p → 1s transition measurement at the DAΦNE collider of Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali di Frascati. Combining this measurement with the kaonic hydrogen one performed by SIDDHARTA in 2009 it will be possible to obtain, in a model-independent way, the isospin-dependent antikaon-nucleon scattering lengths. The paper introduces the SIDDHARTA-2 setup, an upgraded version with respect to the one used for the kaonic hydrogen measurement, dedicated to the ambitious kaonic deuterium measurement, together with the preliminary results obtained during the kaonic helium run, preparatory for the SIDDHARTA-2 data taking campaign.

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.

We observed a distinct peak in the Λp invariant mass spectrum of He 3 ( K − , Λ p ) n , well below m K + 2 m p , i.e., the mass threshold of the K − to be bound to two protons. By selecting a relatively large momentum-transfer region q = 350 ∼ 650 MeV/c, one can kinematically separate the peak from the quasi-free process, K ‾ N → K ‾ N followed by the non-resonant absorption by the two spectator-nucleons K ‾ N N → Λ N . We found that the simplest fit to the observed peak gives us a Breit–Wigner pole position at B Kpp = 47 ± 3 ( s t a t . ) − 6 + 3 ( s y s . ) MeV having a width Γ Kpp = 115 ± 7 ( s t a t . ) − 20 + 10 ( s y s . ) MeV, and the S-wave Gaussian reaction form-factor parameter Q Kpp = 381 ± 14 ( s t a t . ) − 0 + 57 ( s y s . ) MeV/c, as a new form of the nuclear bound system with strangeness – “ K − p p ”.

$\bar K$-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., Comment: 10 pages, 5 figures, proceedings of the 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020), accepted for publication in Fwe-Body Systems

High precision light kaonic atoms X-ray spectroscopy is a unique tool for performing experiments equivalent to scattering at vanishing relative energies, to determine the antikaon–nucleus interaction at threshold without the need of extrapolation to zero energy. The SIDDHARTA-2 collaboration is going to perform the first measurement of kaonic deuterium transitions to the fundamental level, which is mandatory to extract the isospin dependent antikaon–nucleon scattering lengths. The SIDDHARTA-2 experiment is presently installed on the DA $$\Phi $$ NE collider of INFN-LNF. The preliminary results obtained during the machine commissioning phase in preparation for the kaonic deuterium data taking campaign, together with future perspectives for extreme precision kaonic atoms studies at DA $$\Phi $$ NE are presented.

The SIDDHARTA-2 collaboration developed an innovative large area Silicon Drift Detectors technology to perform high precision spectroscopy for the investigation of the K¯ N strong interaction in the low-energy regime, in the strangeness sector. The SIDDHARTA-2 devices take advantage of special geometry to maximize the experimental geometrical acceptance together with a dedicated Front End electronics able to provide energy resolution of 163 1 eV at 170 K for the Fe Kα line and a linear response better than 10-3, both preserved along the whole DAQ analog-digital chain in a colliding beams challenging environment. In this work the SIDDHARTA-2 Silicon Drift Detectors spectroscopic characterization and the preliminary results obtained at the DAΦNE collider of Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Frascati are presented.

The article reviews our recent experimental results on the Continuous Spontaneous Localization (CSL) model and on the gravity related collapse model developed by Diósi and Penrose (DP). These models of dynamical reduction of the wave function consist in non-linear and stochastic modifications of the Schröedinger equation, which lead to a progressive breakdown of the superposition principle, as the size of the system increases. We performed a high sensitivity survey of the spontaneous radiation phenomenon, predicted by the collapse models, at the Gran Sasso underground National Laboratory of INFN in Italy. Our studies set the strongest bounds on the CSL parameters, in a broad region of the parameters space, and rule out the DP in its present formulation.

In this paper we report on the results of two analyses of the data taken with a dedicated VIP-Lead experiment at the Gran Sasso National Laboratory of the INFN. We use measurements taken in an environment that is especially well screened from cosmic rays, with a metal target made of “Roman lead” which is characterised by a low level of intrinsic radioactivity. The analyses lead to an improvement, on the upper bounds of the Pauli Exclusion Principle violation for electrons, which is more than one (four) orders of magnitude, when the electron-atom interactions are described in terms of scatterings (or close encounters) respectively.

The standard scheme of several tests of the Pauli Exclusion Principle in bulk matter — both in the experiment and in the subsequent data analysis — has long been based on the seminal paper by E. Ramberg, G.A. Snow [Phys. Lett. B 238, 438 (1990)]. The ideas exposed in that paper are so simple and immediate that they have long gone unchallenged. However, while some of the underlying approximations are still valid, other parts of the article must be reconsidered. Here, we discuss some new concepts thatare related to the motion of the electrons in the test metal (the “target” of the experiment) and which have been recently studied in the framework of the VIP-2 Collaboration.

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.

The AMADEUS collaboration aims to provide new experimental constraints to the \(K^{-}\)N strong interaction in the regime of non-perturbative QCD, exploiting low-energy \(K^{-}\) hadronic interactions with light nuclei (e.g. H, \({}^{4}\)He, \({}^{9}\)Be and \({}^{12}\)C). The low-momentum kaons (\(p_{K}\) \(\sim \) 127 MeV/c) produced at the DA\(\Phi \)NE collider are ideal to explore both stopped and in-flight \(K^{-}\) nuclear captures. The KLOE detector is used as an active target, allowing to achieve excellent acceptance and resolutions for the data. In this work the results obtained from the study of \(\varLambda \pi ^{-}\) and \(\varLambda p\) correlated production in the final state are presented.

The VIP experiment performed an accurate investigation of the Pauli Exclusion Principle for electrons. The apparatus was installed in the Gran Sasso Laboratories of the National Institute of Nuclear Physic in Italy, an underground environment with an extremely low cosmic background. The aim of the experiment was to test the Pauli Exclusion Principle for electrons in a copper target circulated by a Direct Current (DC) current, searching for X-rays emission due to an atomic transition forbidden by Pauli exclusion principle, from the L shell to the K shell of copper when the K shell is already occupied by two electrons. VIP set an upper limit on the Pauli exclusion principle violation probability 1/2β 2 –29. The goal of the upgraded VIP-2 experiment, presently in data taking at Gran Sasso Laboratories, is to improve this limit by two orders of magnitude. The VIP-2 experimental apparatus, in which the Silicon Drift Detectors have the key role of X-ray detectors, and preliminary results are presented.

X-ray spectroscopy of kaonic atoms provides a versatile tool to study the strong interaction at low energies via a direct observation of its influence on the ground state of kaonic hydrogen atoms. The SIDDHARTA experiment provided precise results on the energy shift and width of the kaonic hydrogen 1s state induced by the strong interaction. To enable the extraction of the antikaon-nucleon scattering lengths a0 and a1, SIDDHARTA-2 aims to determine the energy shift and width in kaonic deuterium with precisions of 30 eV and 75 eV, respectively. This measurement is aggravated by the low kaonic deuterium X-ray yield and a high background environment and will only be possible by implementing a severe upgrade on the SIDDHARTA apparatus.

The K¯NN bound system, symbolically denoted as “K−pp”, is the simplest K¯-nuclear bound system which has been widely discussed as a consequence of the strongly attractive K¯N interaction in I = 0 channels. Many theoretical works have pointed out the existence of the “K−pp” bound system, but the calculated properties such as the binding energy and the width spread out due to the uncertainty of the K¯N interaction below the K¯+N mass threshold. Experimentally, there are several reports on observation of a “K−pp” candidate with the binding energy of around 100 MeV, however, no definitive evidence was available so far. At J-PARC, we conducted a experimental search for the “K−pp” bound system using K− + 3He reaction at 1.0 GeV/c where the “K−pp” is expected to be directly produced via the (K−, n) reaction. We finally observed a bound state below the K− +p+p mass threshold in the Λpn final state, which can be interpreted as the “K− pp” bound state. The possible existence of the “K− pp” state is discussed from both aspects of production and decay.

Based on a sample of 300 million KS mesons produced in ϕ→KLKS decays recorded by the KLOE experiment at the DAΦNE e+e− collider we have measured the branching fraction for the decay KS→πμν. The KS mesons are identified by the interaction of KL mesons in the detector. The KS→πμν decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of KL→πμν decays. A fit to the reconstructed muon mass distribution finds 7223±180 signal events. Normalising to the KS→π+π− decay events the result for the branching fraction is B(KS→πμν)=(4.56±0.11stat±0.17syst)×10−4. It is the first measurement of this decay mode and the result allows an independent determination of |Vus| and a test of the lepton-flavour universality.

The VIP Collaboration is performing high precision tests of the Pauli Exclusion Principle for electrons in the extremely low cosmic background environment of the Underground Gran Sasso Laboratories of INFN (Italy). The experimental technique consists in introducing a DC current in a copper conductor, searching for Kα PEP-forbidden atomic transitions when the K shell is already occupied by two electrons. VIP set an upper limit on the PEP-violation probability (½) x β^2 < 4.7 × 10^−29. The aim of the upgraded VIP-2 experiment is to improve this result at least by two orders of magnitude. The improved experimental setup and the results of a preliminary data analysis, corresponding to the the first run of the VIP-2 data taking (2016–2017), will be presented.

The AMADEUS collaboration is providing unique experimental information on the low-energy strong interaction between K− and nucleons exploiting the low momentum K− (pK ∼ 127 MeV/c) produced at the DAΦNE collider and using the KLOE detector as active target. The absorption of the K− in light nuclei (H, 4He, 9Be and 12C) are investigated and hyperon-pion/hyperon-nucleons, emitted in the final state, are reconstructed. In the present work the results obtained from the study of Λπ−, Ap and At correlated production will be presented.

We briefly report the recent results obtained by the AMADEUS collaboration on experimental studies of the K\(^-\) low-energy interactions with light nuclei and outline the future perspectives.

Light kaonic atoms spectroscopy offers the unique opportunity to perform experiments equivalent to scattering at vanishing relative energies. This allows the determination of the antikaon-nucleus interaction at threshold, without the need of extrapolation to zero energy, as in the case of scattering experiments. In this framework, the SIDDHARTA-2 collaboration aims to perform the first measurement of kaonic deuterium transition to the fundamental level, which is mandatory to extract the isospin dependent antikaon—nucleon scattering lengths. The experiment will be carried out at the DA(formula presented)NE collider of LNF-INFN in 2019–2020.

The excellent quality kaon beam provided by the DA\PhiΦNE collider of LNF-INFN (Italy) together with SIDDHARTA/SIDDHARTA-2 new experimental techniques, as very precise and fast-response X-ray detectors, allow to perform unprecedented measurements on light kaonic atoms crucial for a deeper understanding of the low-energy quantum chromodynamics (QCD) in the strangeness sector. In this paper an overview of the main results obtained by the SIDDHARTA collaboration, as well as the future plans related to the SIDDHARTA-2 experiment, are discussed.

The VIP-2 (VIolation of the Pauli Exclusion Principle) experiment conducted at the Gran Sasso underground laboratory (LNGS) of INFN is searching for possible tiny violations of standard quantum mechanics in copper atoms with extremely high sensitivity. We investigate atomic transitions with precision X-ray spectroscopy in order to test the Pauli Exclusion Principle (PEP) and therefore the spin-statistics theorem. We present the experimental method for the search for "anomalous" (i.e. Pauli-forbidden) X-ray transitions in copper atoms, produced by "new" electrons, which could have a tiny probability to undergo a Pauli-forbidden transition to the 1s ground state already occupied by two electrons. We describe the VIP-2 experimental setup and its recent optimisations. Presently VIP-2 is taking data at LNGS. The goal of VIP-2 is to test PEP for electrons with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10-31 (and using a more elaborate analysis even 10-40). We present current experimental results.