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Opening and Welcome Session by Prof. Zbigniew Postawa - Dean of Faculty of Physics, Astronomy and Computer Science Jagiellonian University and Prof. dr hab. Bogdan Fornal - Deputy Director of Niewodniczański Nuclear Physics Institute PAN
Hadronic and radiative decays of light meson decays offer a privileged environment to test QCD and search for physics beyond the Standard Model. A new generation of precision experiments in hadron physics will soon offer new data that will provide sensitive probes to test potential New Physics including searches for dark photons, light scalars and axion-like particles, complementing worldwide efforts to detect new light particles in the MeV-GeV mass range.
In this talk, I will give an update on the theoretical developments and discuss the experimental opportunities in this field, paying particular attention to the sensitivity of the η and η' mesons to dark bosons and ALPs.
TBD
Axions, or axionlike particles (ALPs), can couple to the spin of nucleons and nuclei, either directly through the axion-wind effect, or indirectly, inducing an oscillating electric dipole moment in nucleons in the process. If ALPs are a part of the cold dark matter in our Galaxy, they can be treated as a classical field. A beam of in-plane polarized hadrons circulating in a storage ring can therefore be used as an ALP antenna. At the resonance between the frequency of an ALP field and the spin-precession frequency of the beam, a buildup of the vertical polarization component should appear as a signal of the ALP presence. As the ALP mass and frequency are unknown, the beam momentum, which is directly related to its spin-precession frequency, needs to be ramped in a search for the resonance crossing. The JEDI collaboration conducted a proof-of-principle experiment demonstrating this new method using the polarized deuteron beam of the COSY synchrotron. An ALP mass range of $0.495-0.502\ \mathrm{neV/c}^2$ was scanned. No ALP signal was observed, but a 90% confidence upper limit on the deuteron oscillating electric dipole moment of $6.4\times10^{-23}\ $e$\cdot$cm was obtained. The experimental method was successfully tested through injection into the ring of a fake ALP signal generated using a radio-frequency Wien filter. In my talk, I will discuss the method, necessary preparatory work and developments, the experiment and its subtleties, and the results.
Our present understanding of the properties of Dark Matter (DM), whose existence was confirmed decades ago through its gravitational interactions with ordinary matter, remain limited. A major scientific quest is to uncover its nature, origin, composition, and interactions beyond gravity.
Despite extensive efforts to identify viable Weakly Interacting Massive Particle (WIMP) candidates, no positive results have been achieved so far.
Recently, new hypotheses have emerged about the nature of Dark Matter. For instance, models for light (sub-GeV) DM suggest that its constituents belong to a Hidden Sector, that is uncharged under the Standard Model (SM) forces and interacts with the SM through a new force carrier. Specifically, well-supported theoretical models propose the existence of a new U(1) light gauge boson, known as the heavy (or dark) photon A', which kinetically mixes with the SM photon.
The Heavy Photon Search (HPS) experiment at the Thomas Jefferson National Accelerator Facility (JLAB, USA) was primarily designed to search for heavy photons produced through electron interactions on a thin Tungsten target, that decay into electron-positron pairs.
This presentation will describe the design and performance of the HPS detector and outline the results of the analyses, based both on bump hunt and displaced vertices searches, from the data collected during the 2016 engineering run.
Additionally, the current status of the ongoing analysis of two larger datasets from 2019 and 2021 will be discussed, along with an estimated reach for these new data.
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We present a new lattice QCD calculation of the leading order hadronic vacuum polarization contribution to the muon anomalous magnetic moment $a_\mu$ with a $40\%$ reduction of the uncertainties. The short and intermediate distance window contributions are computed on 28 ensembles with 6 different lattice spacings, while the (small) long distance contributions are obtained using input from experiments in a low-energy regime where they all agree. Combined with other standard model contributions our result leads to a prediction that differs from the measurement of $a_\mu$ by only $0.9$ standard deviations. This provides a remarkable validation of the standard model to $0.37$ppm.
The new JLab Eta Factory (JEF) in Hall D at Jefferson Lab will extend the scientific potential of the GlueX detector beyond its original program to perform precision measurements of various eta(′) decays with emphasis on rare neutral modes. The scientific program spans from precision tests of low-energy QCD to the search for gauge bosons in the mass range below 1 GeV, coupling the SM sector to the dark sector. Photoproduction of energetic eta(′) mesons using a tagged photon beam and detection of recoil protons and multi-photon final states suppresses background and produces a high-statistics data sample of eta mesons. An overview of the JEF project will be presented
We consider the anomalous interactions for mesons with higher spin, the heterochiral nonets with $J^{P C} = 1^{+ -}$ and $2^{- +}$.
Based on the recent results of Ref. Phys.Rev.D 109 (2024) 7, L071502, under the approximation of a dilute gas of instantons the mixing angle between non-strange and strange mesons decreases strongly as $J$ increases, and oscillates in sign. Anomalous interactions also open up new, rare decay channels. For glueballs, anomalous interactions indicate that the $X(2600)$ state is primarily gluonic.
In this study, we present an exclusive analysis of the \textit{pp} $\to$ \textit{ppKK} reaction with data collected by the HADES detector during February 2022. In the course of this analysis, we developed a neural network-based particle identification procedure (PID), which compensates for the differences between simulation and experiment via a domain adversarial technique. We efficiently suppress background by means of kinematic refit with a 4C constraint, corresponding to the conservation of 4-momentum.
We observed clear signals from $\phi(1020) \to KK$ and $\Lambda(1520) \to pK$ with their parameters consistent with PDG data within one standard deviation. However, the formation of $p\phi$ intermediate state doesn't seem to happen. This talk will present the details of our event selection procedures, efficiency corrections and prospects for further understanding of the reaction mechanism