Nuclear Theory·nucl-th

Thursday·July 6, 2023

12 papers—5 primary·7 cross-listed

01
How to extract the electromagnetic response of $^{6}$ He in relativistic collisions
C.A. Bertulani
I investigate the difficulties in obtaining the electromagnetic response of light, halo-like, nuclei using reactions at radioactive beam facilities. A relativistic coupled-channels theory for the calculation of dissociation cross sections of halo nuclei is compared to first-order perturbation theory. A comparison with semiclassical models frequently used in experimental analysis is also performed. It is shown that the effects of relativity and of the nuclear interaction lead to sizable effects in the extraction of the electromagnetic response of 6He projectiles.
nucl-thnucl-exPRC(2023)·4 citations
02
Cluster decay dynamics of Actinides yielding non-Pb-daughter
Joshua T. Majekodunmi · M. Bhuyan · Raj Kumar
The cluster dynamics of radioactive nuclei decaying to neighbouring daughter nuclei of the double magic $^{132}$ Sn and $^{208}$ Pb is investigated using the relativistic mean-field (RMF) approach with NL3 $^{*}$ parameter set within the preformed cluster-decay model (PCM). The novel feature of the present study is the application of the newly derived preformation formula, laying the groundwork for accessing the break-up of the Q-value: preformation energy, cluster emission energy and the recoil energy of the daughters formed. The energy associated with cluster preformation is theoretically quantified for the first time. This treatment underscores the shell effect, pairing correlation as well as the blocking of particular orbitals by unpaired nucleons. To ascertain the applicability of the new formula, the PCM based calculations are carried out with nuclear potential obtained using the phenomenological M3Y and microscopic RMF-based R3Y nucleon-nucleon (NN) potentials along with corresponding densities. We found a marginal variation that can be attributed to the difference in their barrier properties, however, the predictions for the case of both M3Y and R3Y potentials are found to agree well with the experimental half-lives. Although none of the considered reaction systems yields a double magic daughter nucleus, we found that the kinematics of their cluster emissions is governed by their proximity to the shell closure. The deduced systematic of the recoil energy in cluster decays can provide valuable insight for the synthesis of elements in superheavy mass region in the future.
nucl-thEPJA(2024)·3 citations
03
Reaction dynamics in clustered nuclear systems
Salvatore Simone Perrotta
This work is concerned with the theoretical study of nuclear reactions between light charged ions at incident energies around and below the reactants Coulomb barrier, with a focus on the energy range of astrophysical interest for Big Bang and quiescent stellar processes. The main goal of the analysis is to investigate the sensitivity of nuclear reaction dynamics, and more specifically the cross-section predictions, to the description of the structure of each reactant, and in particular to clustering phenomena. The case of the $^{6}$ Li + p $\to$ $^{3}$ He + $^{4}$ He reaction was investigated explicitly, treating the process as a direct deuteron transfer in first- or second-order distorted-wave Born approximation and through a coupled-reaction-channels approach. The penetrability of the Coulomb barrier in the initial state was also analysed phenomenologically from available experimental data, and studied theoretically taking into account the $^{6}$ Li ground-state deformation.
nucl-th3 citations
04
Laser-assisted deformed $α$ decay of the ground state even-even nuclei
Jun-Hao Cheng · Wen-Yu Zhang · Qiong Xiao · Jun-Gang Deng · Tong-Pu Yu
In the present work, the influence of ultra-intense laser fields on the $α$ decay half-life of the deformed ground state even-even nucleus with the mass number $52 \leq Z \leq 118$ is systematically studied. The calculations show that the laser field changes the $α$ decay half-life by varying the $α$ decay penetration probability in a small range. Moreover, the analytical formulas for the rate of change of the $α$ decay penetration probability in the ultra-intense laser fields have been derived by the spherical approximation, which agrees well with the numerical solutions for nuclei with more significant proton numbers. This provides a fast way to estimate the rate of change of the $α$ decay penetration probability for superheavy nuclei. Furthermore, the relationship between laser properties and the average rate of change of the $α$ decay penetration probability is investigated. The calculations indicate that the shorter the wavelength of the laser pulse is, the larger the average rate of change of the penetration probability.
nucl-thNucl.Sci.Tech.(2025)·8 citations
05
Collision integral with momentum-dependent potentials and its impact on pion production in heavy-ion collisions
Natsumi Ikeno🇯🇵 · Akira Ono🇯🇵
The momentum dependence of the nucleon mean-field potential in a wide momentum range can be an important factor to determine the $Δ$ resonance and pion production in intermediate-energy heavy-ion collisions. In particular, in neutron-rich systems such as $^{132} Sn +^{124} Sn$ collisions, we need to carefully treat the momentum dependence because the neutron and proton potentials can have different momentum dependence, as characterized at low momenta by effective masses. In the present work, we rigorously calculate the collision terms of $N N \leftrightarrow N Δ$ and $Δ \leftrightarrow N π$ processes with the precise conservation of energy and momentum under the presence of momentum-dependent potentials for the initial and final particles of the process. The potentials affect not only the threshold condition for the process but also the cross section in general as a function of the momenta of the initial particles, which is treated in a natural way in the present work. Calculations are performed by combining the nucleon dynamics obtained by the antisymmetrized molecular dynamics (AMD) model with a newly developed transport code which we call sJAM. The calculated results for central $^{132} Sn +^{124} Sn$ collisions at 270 MeV/nucleon clearly show that the momentum dependence of the neutron and proton potentials has a significant impact on the $N N \to N Δ$ process, and this information is strongly reflected in the charged pion ratio ( $π^{-} / π^{+}$ ). We also investigate the effects of the high-density symmetry energy and the isovector part of the potential of $Δ$ resonances on pion production, which we find are relatively small compared to the effect of the momentum dependence of the neutron and proton potentials.
nucl-thnucl-exPRC(2023)·13 citations
06
Collider constraints on massive gravitons coupling to photons
David d'Enterria (CERN)🇨🇭 · Malak Ait Tamlihat (Mohammed V University in Rabat)🇲🇦 · Laurent Schoeffel (CEA)🇫🇷 · Hua-Sheng Shao (LPTHE)🇫🇷 · Yahya Tayalati (Mohammed V University in Rabat)🇲🇦
We study the discovery potential of massive graviton-like spin-2 particles coupled to standard model fields, produced in photon-photon collisions at the Large Hadron Collider (LHC) as well as in electron-positron ( $e^{+} e^{-}$ ) collisions, within an effective theory with and without universal couplings. Our focus is on a massive graviton G coupled to the electromagnetic field, which decays via $G \to γ γ$ and leads to a resonant excess of diphotons over the light-by-light scattering continuum at the LHC, and of triphoton final states at $e^{+} e^{-}$ colliders. Based on similar searches performed for pseudoscalar axion-like particles (ALPs), and taking into account the different cross sections, $γ γ$ partial widths, and decay kinematics of the pseudoscalar and tensor particles, we reinterpret existing experimental bounds on the ALP- $γ$ coupling into G- $γ$ ones. Using the available data, exclusion limits on the graviton-photon coupling are set down to $g_{G γ γ} \approx 1$ --0.05~TeV $^{- 1}$ for masses $m_{G} \approx 100$ ~MeV--2~TeV. Such bounds can be improved by factors of 100 at Belle~II in the low-mass region, and of 4 at the HL-LHC at high masses, with their expected full integrated luminosities.
↳ hep-phhep-exnucl-exnucl-thPLB(2023)·24 citations
07
Collider physics with no PDFs
Tuomas Lappi🇫🇮 · Heikki Mäntysaari🇫🇮 · Hannu Paukkunen🇫🇮 · Mirja Tevio🇫🇮
Measurements of Deep Inelastic Scattering (DIS) provide a powerful tool to probe the fundamental structure of protons and other nuclei. The DIS cross sections can be expressed in terms of structure functions which are conventionally expressed in terms of parton distribution functions (PDFs) that obey the DGLAP evolution equations. However, it is also possible to formulate the DGLAP evolution directly in terms of measurable DIS structure functions entirely sidestepping the need for introducing PDFs. We call this as the physical-basis approach. In a global analysis one would thereby directly parametrize the (observable) structure functions -- not the (unobservable) PDFs. Ideally, with data constraints at fixed $Q^{2}$ , the initial condition for the evolution would be the same at each perturbative order (unlike for PDFs) and the approach thus provides a more clean test of the QCD dynamics. We first study a physical basis consisting of the structure functions $F_{2}$ and $F_{L}$ in the fixed-flavour number scheme to the leading non-zero order in $α_{s}$ . We show how to express the quark singlet and gluon PDFs in terms of $F_{2}$ and $F_{L}$ directly in momentum space which then leads to the DGLAP evolution of the structure functions $F_{2}$ and $F_{L}$ . In the second step we expand the physical basis to include six independent structure functions, which allows for a consistent global analysis. The steps towards NLO accuracy and the variable-flavour-number scheme are outlined. At NLO accuracy (when the scheme dependence of PDFs starts to play a part), we can take advatage of the physical basis and express e.g. the Drell-Yan cross sections at the LHC directly in terms of measurable DIS structure functions and thus without the scheme dependence.
↳ hep-phnucl-th1 citation
08
Holographic baryons, dense matter and neutron star mergers
Matti Jarvinen🇰🇷
The gauge/gravity duality, combined with information from lattice QCD, nuclear theory, and perturbative QCD, can be used to constrain the equation of state of hot and dense QCD. I discuss an approach based on the holographic V-QCD model. I start by reviewing the results from the construction of the V-QCD baryon as a soliton of the gauge fields in the model. Then I discuss implementing nuclear matter in the model by using a homogeneous approach. The model predicts a strongly first order phase transition from nuclear to quark matter with a critical endpoint. By using the model in state-of-the-art simulations of neutron star binaries with parameters consistent with GW170817, I study the formation of quark matter during the merger process.
↳ hep-phnucl-thJHAP(2023)·4 citations
09
Quantum simulation of in-medium QCD jets: momentum broadening, gluon production, and entropy growth
João Barata🇺🇸 · Xiaojian Du🇪🇸 · Meijian Li🇪🇸 · Wenyang Qian🇪🇸 · Carlos A. Salgado🇪🇸
Jets provide one of the primary probes of the quark-gluon plasma produced in ultrarelativistic heavy ion collisions and the cold nuclear matter explored in deep inelastic scattering experiments. However, despite important developments in the last years, a description of the real-time evolution of QCD jets inside a medium is still far from being complete. In our previous work, we have explored quantum technologies as a promising alternative theoretical laboratory to simulate jet evolution in QCD matter, to overcome inherent technical difficulties in present calculations. Here, we extend our previous investigation from the single particle $∣ q ⟩$ to the $∣ q ⟩ + ∣ q g ⟩$ Fock space, taking into account gluon production. Based on the light-front Hamiltonian formalism, we construct a digital quantum circuit that tracks the evolution of a multi-particle jet probe in the presence of a medium described as a stochastic color field. Studying the momentum broadening of the jet state, we observe sizable sub-eikonal effects by comparing to eikonal estimates. We also study the medium-induced modifications to the gluon emission probability, which exhibit small corrections compared to the vacuum splitting function. In addition, we study the time evolution of the von-Neumann entropy associated with the quark component; we find that the exponential of the entropy grows linearly in time for the bare quark but super-linearly when taking into account gluon emission.
↳ hep-phnucl-thquant-phPRD(2023)·53 citations
10
Long-Lived Particles and the Quiet Sun
R. Andrew Gustafson🇺🇸 · Ryan Plestid🇺🇸 · Ian M. Shoemaker🇺🇸 · Albert Zhou🇩🇪
The nuclear reaction network within the interior of the Sun is an efficient MeV physics factory, and can produce long-lived particles generic to dark sector models. In this work we consider the sensitivity of satellite instruments, primarily the RHESSI Spectrometer, that observe the Quiet Sun in the MeV regime where backgrounds are low. We find that Quiet Sun observations offer a powerful and complementary probe in regions of parameter space where the long-lived particle decay length is longer than the radius of the Sun, and shorter than the distance between the Sun and Earth. We comment on connections to recent model-building work on heavy neutral leptons coupled to neutrinos and high-quality axions from mirror symmetries.
↳ hep-phastro-ph.HEastro-ph.SRnucl-thPRD(2024)·5 citations
11
Femtoscopy of $D$ mesons and light mesons upon unitarized effective field theories
Juan M. Torres-Rincon🇪🇸 · Àngels Ramos🇪🇸 · Laura Tolos🇪🇸
Hadron femtoscopy has turned into a powerful tool for accessing space-time information of heavy-ion collisions as well as for studying final-state interactions of hadrons. Recently, heavy-flavor femtoscopy has become feasible using the ALICE detector at the LHC. We compute the correlation function of $D$ mesons and light mesons using an off-shell $T$ -matrix approach to access the two-meson wave function, and predict the correlation functions involving charged $D^{+}, D^{*+}, D_{s}^{+}$ and $D_{s}^{*+}$ with $π^{\pm}$ and $K^{\pm}$ . From the obtained results -- all of them accessible in $p + p$ collision experiments -- we point up the case of $D^{+} π^{-}$ , which is sensitive to the lower state of the two-pole $D_{0}^{*} (2300)$ system. The presence of such poles imprints a depletion on the correlation function, which could potentially be detected in experiments. While preliminary ALICE data do not show evidence of this effect, we suggest to look into the $D_{s}^{+} K^{-}$ system to explore the higher pole of the $D_{0}^{*} (2300)$ , as the depletion in the correlation function is more pronounced. Using heavy-quark spin symmetry we also propose exploring the effect of the two poles of the $D_{1} (2430)$ and predict similar structures in the correlation functions of the $D^{*+} π^{-}$ and $D_{s}^{*+} K^{-}$ pairs.
↳ hep-phnucl-thPRD(2023)·50 citations
12
X17 discovery potential from $γ D \to e^{+} e^{-} p n$ with neutron tagging
Cornelis J.G. Mommers🇩🇪 · Marc Vanderhaeghen🇩🇪
We propose a novel direct search experiment for X17 using the reaction $γ D \to e^{+} e^{-} p n$ . X17 is a hypothetical particle conjectured by the ATOMKI collaboration to explain anomalous signals around 17 MeV in excited $^{8}$ Be, $^{4}$ He and $^{12}$ C nuclear decays via internal pair creation. It has been subject to a global experimental and theoretical research program. The proposed direct search in $γ D \to e^{+} e^{-} p n$ can verify the existence of X17 through the production on a quasi-free neutron, and determine its quantum numbers separate from ongoing and planned nuclear-decay experiments. This is especially timely in view of the theoretical tension between results from the $^{12}$ C and $^{8}$ Be measurements. Using the plane-wave impulse approximation, we quantify the expected signal and background for pseudoscalar, vector and axial-vector X17 scenarios. We optimize the kinematics for the quasi-free neutron region with the upcoming MAGIX experiment at MESA in mind and show that for all three scenarios the X17 signal is clearly visible above the QED background.
↳ hep-phnucl-exnucl-th2 citations

Affiliations

first authorsco-authorsvia INSPIRE