We formulate a renormalizable pionless effective field theory (Pionless EFT) with a non-perturbative treatment of the Coulomb interaction up to next-to-leading order (NLO) for few-nucleon systems. We extract scattering observables for charged clusters by employing two-, three-, and four-body contact interactions and using the stochastic variational method with a Coulomb-corrected harmonic oscillator trap. Our NLO results yield a $pd$ spin-quartet scattering length and effective range of $a_{pd}^{3/2} = 12.76(29)\,\mathrm{fm}$ and $r_{pd}^{3/2} = 1.17(7)\,\mathrm{fm}$; for $dd$ scattering in the spin-quintet channel, we find $a_{dd}^{2} = 6.26(3)\,\mathrm{fm}$ and $r_{dd}^{2} = 1.41(7)\,\mathrm{fm}$; and for $p^3\mathrm{He}$ scattering, the spin-singlet and spin-triplet channels are characterized by $a_{p^3\mathrm{He}}^0 = 11.26(4)\,\mathrm{fm}$, $r_{p^3\mathrm{He}}^0 = 1.65(26)\,\mathrm{fm}$ and $a_{p^3\mathrm{He}}^1 = 9.06(4)\,\mathrm{fm}$, $r_{p^3\mathrm{He}}^1 = 1.36(25)\,\mathrm{fm}$, respectively. Our predictions exhibit mild cutoff dependence and agree well with existing experimental phase shift analyses and potential model calculations. This demonstrates the predictive power of (Pionless EFT) for charged few-nucleon systems.

Considering the elastic scattering of two charged particles, we present two methods for numerically solving the generalized Coulomb-corrected BERW formula with high accuracy across the entire energy spectrum. We illustrate these methods using p-alpha scattering, employing a phenomenological p-alpha short-range interaction. Our results reproduce the phase shifts computed with the Numerov method for all l=0 and l=1 channels. We also provide full access to the Python script used to obtain these results, which can be readily applied to a wide range of core-fragment scattering problems in nuclear and atomic physics.

We address the question of minimal requirements for the existence of quantum bound states. In particular, we demonstrate that a few-body system with zero-range momentum-independent two-body interactions is unstable against decay into clusters, if mixed-symmetry of its wave function is enforced. We claim that any theory in which the two-body scattering length is much larger than any other scale involved exhibits such instability. We exemplify this with the inability of the leading-order pionless effective field theory to describe stable states of $A>4$ nuclei. A finite interaction range is identified as a sufficient condition for a bound mixed-symmetry system. The minimal value of this range depends on the proximity of a system to unitarity, on the number of constituents, and on the particular realization of discrete scale invariance of the three-body spectrum.

I investigate whether it is possible to generate bound-states from resonances or virtual states through first-order perturbation theory. Using contact-type potentials as those appeared in pionless effective field theory, I show that it is possible to obtain negative-energy states by sandwiching a next-to-leading order (NLO) interaction with the leading-order (LO) wavefunctions, under the presence of LO resonances or virtual states. However, at least under the framework of time-independent Schr\"odinger equation and Hermitian Hamiltonian, there is an inability to create bound-states with structure similar to those formed by the non-perturbative treatments.

We formulate two methods to facilitate the calculation of perturbative corrections to quantum few-body observables. Both techniques are designed for a numerical realization in combination with any tool that obtains either the entire spectrum or solely the eigenvalues of an operator corresponding to the observable of interest. We exemplify these methods in the context of the nuclear contact theory without pions (Pionless EFT) and benchmark them in the deuteron channel with available analytical, field-theoretical calculations, as well as in the triton and 3-helium channels through earlier extractions within the dibaryon formalism, where in all three systems the point-proton root-mean-square charge radius (rms) was the perturbed observable of choice. Beyond these $A\leq3$ consistency and accuracy checks, we employ the numerical methods to predict the rms of the 4-helium nuclear ground state to assess three different ways of integrating the Coulomb interaction into Pionless EFT. By comparing the respective results at leading and next-to-leading order for 3- and 4-helium, we find that the uncertainty due to the strong, short-range interaction is significantly larger compared with that due to the long-range Coulomb interaction for both bound states with their different binding momenta. Thereby, we provide strong support for simplifying extractions of bound-state observables by shutting off any Coulomb interaction if the strong part of the potential is considered only up to first order in the effective range expansion.

The structure of the unbound $^{15}$F nucleus is investigated using the inverse kinematics resonant scattering of a radioactive $^{14}$O beam impinging on a CH$_2$ target. The analysis of $^{1}$H($^{14}$O,p)$^{14}$O and $^{1}$H($^{14}$O,2p)$^{13}$N reactions allowed the confirmation of the previously observed narrow $1/2^{-}$ resonance, near the two-proton decay threshold, and the identification of two new narrow 5/2$^{-}$ and 3/2$^{-}$ resonances. The newly observed levels decay by 1p emission to the ground of $^{14}$O, and by sequential 2p emission to the ground state (g.s.) of $^{13}$N via the $1^-$ resonance of $^{14}$O. Gamow shell model (GSM) analysis of the experimental data suggests that the wave functions of the 5/2$^{-}$ and 3/2$^{-}$ resonances may be collectivized by the continuum coupling to nearby 2p- and 1p- decay channels. The observed excitation function $^{1}$H($^{14}$O,p)$^{14}$O and resonance spectrum in $^{15}$F are well reproduced in the unified framework of the GSM.

Partons traversing the strongly interacting medium produced in heavy-ion collisions are expected to lose energy depending on their color charge and mass. We measure the nuclear modification factors for charm- and bottom-decay electrons, defined as the ratio of yields, scaled by the number of binary nucleon-nucleon collisions, in $\sqrt{s_{\rm NN}}$ = 200 GeV Au+Au collisions to $p$+$p$ collisions ($R_{\rm AA}$), or in central to peripheral Au+Au collisions ($R_{\rm CP}$). We find the bottom-decay electron $R_{\rm AA}$ and $R_{\rm CP}$ to be significantly higher than that of charm-decay electrons. Model calculations including mass-dependent parton energy loss in a strongly coupled medium are consistent with the measured data. These observations provide clear evidence of mass ordering of charm and bottom quark energy loss when traversing through the strongly coupled medium created in heavy-ion collisions.

The unit vectors transformation between the Cartesian and the novel Similar Oblate Spheroidal coordinates, and vice versa, is derived. It can help to transform vector fields between these two types of orthogonal coordinates which can advantageously simplify solutions of problems exhibiting oblate spheroidal geometry. Several examples demonstrate the use of the derived relations. Generalized sine and cosine applicable in Similar Oblate Spheroidal coordinate system are introduced.

The energy levels of light hypernuclei are experimentally accessible observables that contain valuable information about the interaction between hyperons and nucleons. In this work we study strangeness $S = -1$ systems $^{3,4}_\Lambda$H and $^{4,5}_\Lambda$He using the ab initio no-core shell model (NCSM) with realistic interactions obtained from chiral effective field theory ($\chi$EFT). In particular, we quantify the finite precision of theoretical predictions that can be attributed to nuclear physics uncertainties. We study both the convergence of the solution of the many-body problem (method uncertainty) and the regulator- and calibration data-dependence of the nuclear $\chi$EFT Hamiltonian (model uncertainty). For the former, we implement infrared correction formulas and extrapolate finite-space NCSM results to infinite model space. We then use Bayesian parameter estimation to quantify the resulting method uncertainties. For the latter, we employ a family of 42 realistic Hamiltonians and measure the standard deviation of predictions while keeping the leading-order hyperon-nucleon interaction fixed. Following this procedure we find that model uncertainties of ground-state $\Lambda$ separation energies amount to $\sim 20(100)$ keV in $^3_\Lambda$H($^4_\Lambda$H,He) and $\sim 400$ keV in $^5_\Lambda$He. Method uncertainties are comparable in magnitude for the $^4_\Lambda$H,He $1^+$ excited states and $^5_\Lambda$He, which are computed in limited model spaces, but otherwise much smaller. This knowledge of expected theoretical precision is crucial for the use of binding energies of light hypernuclei to infer the elusive hyperon-nucleon interaction.

The ab initio symmetry-adapted no-core shell model naturally describes nuclear deformation and collectivity, and is therefore well-suited to studying the dynamics and coexistence of shapes in atomic nuclei. For the first time, we analyze how these features in low-lying states of 6Li and 12C are impacted by the underlying realistic nucleon-nucleon interaction. We find that the interaction parametrization has a notable but limited effect on collective shapes in the lowest 6Li and 12C states, while collective structures in the excited 2+ state of 12C are significantly more sensitive to the interaction parameters and exhibits emergent shape coexistence.

We present a coupled channels separable potential approach to $\eta N$ and $\eta'N$ interactions using a chiral-symmetric interaction kernel. The s-wave $\pi N$ amplitudes and $\pi^{-}p$ induced total cross sections are reproduced satisfactorily in a broad interval of energies despite limiting the channel space to two-body interactions of pseudoscalar mesons with the baryon ground-state octet. It is demonstrated that an explicit inclusion of the $\eta_0$ meson singlet field leads to a more attractive $\eta N$ interaction, with the real part of the scattering length exceeding 1 fm. The $\eta'N$ diagonal coupling appears sufficient to generate an $\eta'N$ bound state but the inter-channel dynamics moves the respective pole far from physical region making the $\eta'N$ interaction repulsive at energies around the channel threshold. The $N^{*}(1535)$ and $N^{*}(1650)$ resonances are generated dynamically and the origin and properties of the $S$-matrix poles assigned to them are studied in detail. We also hint at a chance that the $N^{*}(1895)$ state might also be formed provided a suitably varied model setting is found.

Based on the Watson expansion of the multiple scattering series, we employ a nonlocal translationally invariant nuclear density derived within the symmetry-adapted no-core shell model (SA-NCSM) framework from a chiral next-to-next-to-leading order (NNLO) nucleon-nucleon interaction and the very same interaction for a consistent full-folding calculation of the effective (optical) potential for nucleon-nucleus scattering for medium-heavy nuclei. The leading order effective (optical) folding potential is computed by integrating over a translationally invariant SA-NCSM one-body scalar density, spin-projected momentum distribution, and the Wolfenstein amplitudes $A$, $C$, and $M$. The resulting nonlocal potentials serve as input for a momentum space Lippmann-Schwinger equation, whose solutions are summed up to obtain nucleon-nucleus scattering observables. In the SA-NCSM, the model space is systematically up-selected using $\SpR{3}$ symmetry considerations. For the light nucleus of $^6$He, we establish a systematic selection scheme in the SA-NCSM for scattering observables. Then, we apply this scheme to calculations of scattering observables, such as differential cross sections, analyzing powers, and spin rotation functions for elastic proton scattering from $^{20}$Ne and $^{40}$Ca in the energy regime between 65 and 200 MeV, and compare to available data. Our calculations show that the leading order effective nucleon-nucleus potential in the Watson expansion of multiple scattering theory obtained from an up-selected SA-NCSM model space describes $^{40}$Ca elastic scattering observables reasonably well to about 60 degrees in the center-of-mass frame, which coincides roughly with the validity of the NNLO chiral interaction used to calculate both the nucleon-nucleon amplitudes and the one-body scalar and spin nuclear densities.

We report on the first \textit{ab initio} informed $\alpha$ knock-out reaction in the intermediate-mass region, with the aim to probe the underlying chiral potential and its impact on the emergence of alpha clustering in this mass region. The theoretical predictions of the $\alpha+^{16}$O clustering in the $^{20}$Ne ground state, based on the \textit{ab initio} symmetry-adapted no-core shell model, yield a triple differential cross section for $^{20}$Ne(p, p$\alpha$)$^{16}$O that is in a remarkable agreement with the data. This allows us to examine predictions of surface and in-medium $\alpha$-cluster features from a chiral potential and to compare these to the successful antisymmetrized molecular dynamics approach.

We discover a surprising relation between the collective motion of nucleons within atomic nuclei, traditionally understood to be driven by long-range correlations, and short-range nucleon-nucleon interactions. Specifically, we find that quadrupole collectivity in low-lying states of $^6$Li and $^{12}$C, calculated with state-of-the-art ab initio techniques, is significantly influenced by two opposing $S$-wave contact couplings that subtly alter the surface oscillations of one largely deformed nuclear shape, without changing that shape's overall contribution within the nucleus. The results offer new insights into the nature of emergent nuclear collectivity and its link to the underlying nucleon-nucleon interaction at short distances.

Bent monolithic active pixel sensors are the basis for the planned fully cylindrical ultra low material budget tracking detector ITS3 of the ALICE experiment. This paper presents results from testbeam campaigns using high-energy particles to verify the performance of 50 um thick bent ALPIDE chips in terms of efficiency and spatial resolution. The sensors were bent to radii of 18, 24 and 30 mm, slightly smaller than the foreseen bending radii of the future ALICE ITS3 layers. An efficiency larger than $99.9\%$ and a spatial resolution of approximately 5 um, in line with the nominal operation of flat ALPIDE sensors, is obtained at nominal operating conditions. These values are found to be independent of the bending radius and thus constitute an additional milestone in the demonstration of the feasibility of the planned ITS3 detector. In addition, a special geometry in which the beam particles graze the chip and traverse it laterally over distances of up to 3 mm is investigated.

We present an improved action for Pionless Effective Field Theory (EFT). Previous formulations of renormalizable nuclear EFTs have encountered instabilities in systems with more than four nucleons. We resolve this issue by introducing a finite interaction range at leading order, which is compensated for in perturbation theory at next-to-leading order. Calculated ground-state energies of $^4$He, $^6$Li, $^{12}$C, and $^{16}$O converge and agree with experiment within theoretical uncertainties. This first successful implementation of systematic renormalizability beyond the lightest nuclei enables not only applications to larger nuclei but also extensions to other EFTs in the strong-coupling regime.

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) is a heavy-ion experiment designed to study nuclear matter at the highest baryonic density. For high-statistics measurements of rare probes, event rates of up to 10 MHz are targeted. The experiment, therefore, requires fast and radiation-hard detectors, self-triggered detector front-ends, free-streaming readout architecture, and online event reconstruction. The Silicon Tracking System (STS) is the main tracking detector of CBM, designed to reconstruct the trajectories of charged particles with efficiency larger than 95%, a momentum resolution better than 2% for particle momenta larger than 1 GeV/c inside a 1 Tm magnetic field, and to identify complex decay topologies. It comprises 876 double-sided silicon strip modules arranged in 8 tracking stations. A prototype of this detector, consisting of 12 modules arranged in three tracking stations, is installed in the mini-CBM demonstrator. This experimental setup is a small-scale precursor to the full CBM detector, composed of sub-units of all major CBM systems installed on the SIS18 beamline. In various beam campaigns taken between 2021 and 2024, heavy ion collisions at 1-2 AGeV with an average collision rate of 500 kHz have been measured. This allows for the evaluation of the operational performance of the STS detector, including time and position resolution, hit reconstruction efficiency, charge distribution, signal-to-noise ratio, and its potential for track and vertex reconstruction.

We report on the measurements of directed flow $v_1$ and elliptic flow $v_2$ for hadrons ($\pi^{\pm}$, $K^{\pm}$, $K_{S}^0$, $p$, $\phi$, $\Lambda$ and $\Xi^{-}$) from Au+Au collisions at $\sqrt{s_{NN}}$ = 3\,GeV and $v_{2}$ for ($\pi^{\pm}$, $K^{\pm}$, $p$ and $\overline{p}$) at 27 and 54.4\,GeV with the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3\,GeV the $v_{2}$ at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the $v_1$ slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative $v_2$ and positive $v_1$ slope at 3\,GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.

A systematic study of all relevant in-medium effects on the total $K^-$-nuclear potential is presented in this work. The $K^-N$ scattering amplitudes, including Pauli blocking effects and hadron self-energies (hyperons, nucleons, pions and kaons), are derived within a next-to-leading order chiral meson-baryon coupled-channel interaction model. These amplitudes are employed in a microscopic model of the $K^-$-nuclear potential in symmetric nuclear matter that includes one-, two- and, when the kaons and pions are dressed, also multi-nucleon absorption processes. The potential is then applied in calculations of the strong energy shifts and widths of 64 measured kaonic atom levels. The comparison of the results of the full model that includes Pauli correlations and hadron self-energies with data provides $\chi^2 /d.p=1.5$, the lowest value obtained by a theoretical model to date and comparable with that of the best fitted phenomenological potentials. Furthermore, the calculated branching ratios for mesonic and non-mesonic absorption channels in kaonic carbon and kaonic neon are in good agreement with available data.

Quark interactions with topological gluon configurations can induce local chirality imbalance and parity violation in quantum chromodynamics, which can lead to the chiral magnetic effect (CME) -- an electric charge separation along the strong magnetic field in relativistic heavy-ion collisions. The CME-sensitive azimuthal correlator observable ($\Delta\gamma$) is contaminated by background arising, in part, from resonance decays coupled with elliptic anisotropy ($v_{2}$). We report here differential measurements of the correlator as a function of the pair invariant mass ($m_{\rm inv}$) in 20-50\% centrality Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$= 200 GeV by the STAR experiment at RHIC. Strong resonance background contributions to $\Delta\gamma$ are observed. At large $m_{\rm inv}$ where this background is significantly reduced, the $\Delta\gamma$ value is found to be significantly smaller. An event-shape-engineering technique is deployed to determine the $v_{2}$ background shape as a function of $m_{\rm inv}$. We extract a $v_2$-independent and $m_{\rm inv}$-averaged signal $\Delta\gamma_{\rm sig}$ = (0.03 $\pm$ 0.06 $\pm$ 0.08) $\times10^{-4}$, or $(2\pm4\pm5)\%$ of the inclusive \Delta\gamma(m_{\rm inv}>0.4 GeV/$c^2$)$ =(1.58 \pm 0.02 \pm 0.02) \times10^{-4}$, within pion$p_{T}$ = 0.2 - 0.8~\gevc and averaged over pseudorapidity ranges of -1 < \eta < -0.05 and 0.05 < \eta < 1. This represents an upper limit of $0.23\times10^{-4}$, or $15\%$ of the inclusive result, at $95\%$ confidence level for the $m_{\rm inv}$-integrated CME contribution.