Nuclear Theory·nucl-th

Tuesday·January 1, 2019

14 papers—5 primary·9 cross-listed

01
The puzzle of complete fusion suppression in weakly-bound nuclei: a Trojan Horse effect?
Jin Lei🇺🇸 · Antonio M. Moro🇪🇸
Experimental studies of nuclear collisions involving light weakly-bound nuclei show a systematic suppression of the complete fusion cross section by $\sim$ 30\% with respect to the expectation for tightly bound nuclei, at energies above the Coulomb barrier. Although it is widely accepted that the phenomenon is related to the weak binding of these nuclei, the origin of this suppression is not fully understood. In here, we present a novel approach that provides the complete fusion for weakly bound nuclei and relates its suppression to the competition between the different mechanisms contributing to the reaction cross section. The method is applied to the $^{6, 7}$ Li+ $^{209}$ Bi reactions, where we find that the suppression of complete fusion is mostly caused by the flux associated with non-elastic breakup modes, such as the partial capture of the projectile (incomplete fusion), whereas the elastic breakup mode is found to play a minor role. Finally, we demonstrate that the large $α$ yields observed in these reactions can be naturally explained as a consequence of a {\it Trojan Horse} mechanism.
nucl-thPRL(2019)·55 citations
02
Nuclear effects in the deuteron in the resonance and deep-inelastic scattering region
S.A. Kulagin🇷🇺
We discuss a hybrid model of the proton and neutron inelastic structure functions which incorporates both the partonic and the nucleon resonance structures and applicable in a wide region of the invariant mass $W$ of produced hadronic states. Focusing at the typical kinematics of JLab experiments we compute the deuteron structure functions and demonstrate good performance of the model against data. We perform systematic study of the ratios $F_{2}^{n} / F_{2}^{d}$ and $(F_{2}^{p} + F_{2}^{n}) / F_{2}^{d}$ for both, the deep-inelastic and the resonance, region in the context of recent measurements of BoNuS experiment at Jefferson Lab.
nucl-thPhys.Part.Nucl.(2019)·5 citations
03
Nuclear response in a finite-temperature relativistic framework
Elena Litvinova🇺🇸 · Herlik Wibowo🇺🇸
A thermal extension of the relativistic nuclear field theory is formulated for the nuclear response. The Bethe-Salpeter equation (BSE) with the time-dependent kernel for the particle-hole response is treated within the Matsubara Green's function formalism. We show that, with the help of a temperature-dependent projection operator on the subspace of the imaginary time (time blocking), it is possible to reduce the BSE for the nuclear response function to a single frequency variable equation also at finite temperature. The approach is implemented self-consistently in the framework of quantum hadrodynamics based on the meson-nucleon Lagrangian. The method is applied to the monopole, dipole and quadrupole response of $^{48}$ Ca and to the dipole response of the tin isotopes $^{100, 120, 132}$ Sn, in particular, to a study of the evolution of nuclear collective oscillations with temperature. The article is dedicated to the memory of Pier Francesco Bortignon and devoted to the developments related to his pioneering ideas.
nucl-thnucl-exEPJA(2019)·21 citations
04
A unified quark-nuclear matter equation of state from the cluster virial expansion within the generalized Beth-Uhlenbeck approach
Niels-Uwe Friedrich Bastian🇵🇱 · David Bernhard Blaschke🇵🇱
We consider a cluster expansion for strongly correlated quark matter where the clusters are baryons with spectral properties that are described within the generalized Beth-Uhlenbeck approach by a medium dependent phase shift. We employ a simple ansatz for the phase shift which fulfils the Levinson theorem by describing an on-shell bound state with an effective mass and models the continuum by an anti-bound state located at the mass of the three-quark threshold. The quark and baryon interactions are accounted for by the coupling to scalar and vector meson mean fields modelled by density functionals. At increasing density and temperature, due to the different medium-dependence of quark and baryon masses, the Mott dissociation of baryons occurs and the nuclear cluster contributions to the thermodynamics vanish. It is demonstrated on this simple example that this unified approach to quark-nuclear matter is capable of describing crossover as well as first order phase transition behaviour in the phase diagram with a critical endpoint. Changing the meson mean field, the case of a "crossover all over" in the phase diagram is also obtained.
nucl-thEPJA(2021)·14 citations
05
Hybrid equation of state with pasta phases and third family of compact stars
K. Maslov🇷🇺 · N. Yasutake🇯🇵 · A. Ayriyan🇷🇺 · D. Blaschke🇵🇱 · H. Grigorian🇷🇺 · T. Maruyama🇯🇵 · T. Tatsumi🇯🇵 · D. N. Voskresensky🇷🇺
The effect of pasta phases on the quark-hadron phase transition is investigated for a set of relativistic mean-field equations of state for both hadron and quark matter. The results of the full numerical solution with pasta phases are compared with those of an interpolating construction used in previous works, for which we demonstrate an adequate description of the numerical results. A one-to-one mapping of the free parameter of the construction to the physical surface tension of the quark-hadron interface is obtained for which a fit formula is given. For each pair of quark and hadron matter models the critical value of the surface tension is determined, above which the phase transition becomes close to the Maxwell construction. This result agrees well with earlier theoretical estimates. The study is extended to neutron star matter in beta equilibrium with electrons and muons and is applied to investigate the effect of pasta phases on the structure of hybrid compact stars and the robustness of a possible third family solution.
nucl-thastro-ph.HEhep-phPRC(2019)·78 citations
06
Lattice QCD and nuclear physics for searches of physics beyond the Standard Model
Emanuele Mereghetti🇺🇸
Low-energy tests of fundamental symmetries are extremely sensitive probes of physics beyond the Standard Model, reaching scales that are comparable, if not higher, than directly accessible at the energy frontier. The interpretation of low-energy precision experiments and their connection with models of physics beyond the Standard Model relies on controlling the theoretical uncertainties induced by the nonperturbative nature of QCD at low energy and of the nuclear interactions. In these proceedings, I will discuss how the interplay of Lattice QCD and nuclear Effective Field Theories can lead to improved predictions for low-energy experiments, with controlled uncertainties. I will describe the framework of chiral Effective Field Theory, and then discuss a few examples, including non-standard $β$ decays, neutrinoless double beta decay and searches for electric dipole moments, to highlight the progress achieved in recent years, and the role that Lattice QCD will play in addressing the remaining open problems.
↳ hep-lathep-phnucl-thPoS(2019)·2 citations
07
Magneto-transport in an anomalous fluid with weakly broken symmetries, in weak and strong regime
Navid Abbasi🇮🇷 · Armin Ghazi🇮🇷 · Farid Taghinavaz🇮🇷 · Omid Tavakol🇮🇷
We consider a general system with weakly broken time and translation symmetries. We assume the system also possesses a $U (1)$ symmetry which is not only weakly broken, but is anomalous. We use the second order chiral quasi-hydrodynamics to compute the magneto-conductivities in the system in the presence of a weak magnetic field. Analogous to electrical and thermoelectric conductivities, it turns out that the thermal conductivity is identified with a coefficient which depends on the mixed gauge-gravitational anomaly. By applying our general formulas to a free system of Weyl fermions at low temperature limit $T ≪ μ$ , we find that our system is Onsager reciprocal if the relaxation in all energy, momentum and charge channels occurs at the same rate. In the high temperature limit $T ≫ μ$ , we consider a strongly coupled $S U (N_{c})$ gauge theory with $N_{c} ≫ 1$ in the hydrodynamic limit. Its gravity dual is a magnetized charged brane to which, we apply our formulas and compute the conductivities. On the way, we show that analogous to the weak regime, an energy cut-off emerges to regulate the thermodynamic quantities. From this gravity background we also find the coefficients of chiral magnetic effect in agreement with the well-known result of the Son-Surowka.
↳ hep-thcond-mat.str-elnucl-thJHEP(2019)·12 citations
08
Particle Yields and Ratios within Equilibrium and Non-Equilibrium Statistics
Abdel Nasser Tawfik (Nile U., Cairo & Egyptian Ctr. Theor. Phys., Cairo & WLCAPP, Cairo)🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo & Egyptian Ctr. Theor. Phys., Cairo & WLCAPP, Cairo)🇪🇬
In characterizing the yields and ratios various of well identified particles in the ALICE experiment, we utilize extensive {\it additive} thermal approaches, to which various missing states of the hadron resonances are taken into consideration, as well. Despite some non-equilibrium conditions that are slightly driving this statistical approach away from equilibrium, the approaches are and remain additive and extensive. Besides van der Waals repulsive interactions (assuming that the gas constituents are no longer point-like, i.e. finite-volume corrections taken into consideration), finite pion chemical potentials as well as perturbations to the light and strange quark occupation factors are taken into account. When confronting our calculations to the ALICE measurements, we conclude that the proposed conditions for various aspects deriving the system out of equilibrium notably improve the reproduction of the experimental results, i.e. improving the statistical fits, especially the finite pion chemical potential. This points out to the great role that the non-equilibrium pion production would play, and the contributions that the hadron resonance missing states come up with, even when the principles of statistical extensivity and additivity aren't violated. These results seem to propose revising the conclusions propagated by most of the field, that the produced particles quickly reach a state of local equilibrium leading to a collective expansion often described by fluid dynamics. This situation seems not remaining restrictively valid, at very large collision energies.
↳ hep-phnucl-thEPL(2019)·3 citations
09
Nuclear quantum memory and time sequencing of a single $γ$ photon
Xiwen Zhang🇺🇸 · Wen-Te Liao🇺🇸 · Alexey Kalachev🇷🇺 · Rustem Shakhmuratov🇷🇺 · Marlan Scully🇺🇸 · Olga Kocharovskaya🇺🇸
A $γ$ -ray-nuclear quantum interface is suggested as a new platform for quantum information processing, motivated by remarkable progresses in $γ$ -ray quantum optics. The main advantages of a $γ$ photon over an optical photon lie in its almost perfect detectability and much tighter, potentially sub-angstrom, focusability. Nuclear ensembles hold important advantages over atomic ensembles in a unique combination of high nuclear density in bulk solids with narrow, lifetime-broadening Mössbauer transitions even at room temperature. This may lead to the densest long-lived quantum memories and the smallest size photon processors. Here we propose a technique for $γ$ photon quantum memory through a Doppler frequency comb, produced by a set of resonantly absorbing nuclear targets that move with different velocities. It provides a reliable storage, an on-demand generation, and a time sequencing of a single $γ$ photon. This scheme presents the first $γ$ -photon-nuclear-ensemble interface opening a new direction of research in quantum information science.
↳ quant-phnucl-thPRL(2019)·17 citations
10
Efimov physics beyond three particles
Betzalel Bazak🇮🇱
Efimov physics originally refers to a system of three particles. Here we review recent theoretical progress seeking for manifestations of Efimov physics in systems composed of more than three particles. Clusters of more than three bosons are tied to each Efimov trimer, but no independent Efimov physics exists there beyond three bosons. The case of a few heavy fermions interacting with a lighter atom is also considered, where the mass ratio of the constituent particles plays a significant role. Following Efimov's study of the (2+1) system, the (3+1) system was shown to have its own critical mass ratio to become Efimovian. We show that the (4+1) system becomes Efimovian at a mass ratio which is smaller than its sub-systems thresholds, giving a pure five-body Efimov effect. The (5+1) and (6+1) systems are also discussed, and we show the absence of 6- and 7-body Efimov physics there.
↳ cond-mat.quant-gasnucl-thquant-phSpringer Proc.Phys.(2020)·0 citations
11
Early time dynamics and hard probes in heavy-ion collisions
S. Schlichting🇩🇪
We present an overview of the current state of understanding of the early time dynamics of high-energy heavy-ion collisions, emphasizing recent developments and connections between the physics of the initial state and that of hard probes in heavy-ion collisions. Based on a weak-coupling description, we first establish a microscopic picture of the early time dynamics and equilibration process and subsequently discuss their macroscopic manifestations along with a novel macroscopic description of the pre-equilibrium phase. Some phenomenological consequences concerning the role of the pre-equilibrium phase in large (AA) and small (pp/pA) collision systems are briefly discussed along with open questions and opportunities for future improvements.
↳ hep-phnucl-thPoS(2019)·2 citations
12
Jet fragmentation in a QCD medium: Universal quark/gluon ration and Wave turbulence
Y. Mehtar-Tani🇺🇸 · S. Schlichting🇩🇪
We calculate the evolution of a jet shower due to medium induced splittings in the deep LPM regime. Due to the characteristic energy dependence of the formation time $t_{form} (ω) = ω / q ˉ^$ , the radiative break-up process exhibits turbulent characteristics, allowing for analytic predictions of various inclusive properties of the medium induced cascade in an inertial range of energies $T ≪ ω ≪ E$ , where $E$ is the energy of the jet and $T$ is the temperature of the medium.
↳ hep-phnucl-thPoS(2018)·0 citations
13
Mesonic Condensation in Isospin Matter under Rotation
Hui Zhang🇨🇳 · Defu Hou🇨🇳 · Jinfeng Liao🇺🇸
We investigate the mesonic condensation in isospin matter under rotation. Using the two-flavor NJL effective model under the presence of global rotation, we demonstrate two important effects of the rotation on its phase structure: a rotational suppression of the scalar-channel condensates, in particular the pion condensation region; and a rotational enhancement of the rho condensation region with vector-channel condensate. A new phase diagram for isospin matter under rotation is mapped out on the $ω - μ_{I}$ plane where three distinctive phases, corresponding to $σ$ , $π$ , $ρ$ dominated regions respectively, are separated by a second-order line at low isospin chemical potential and a first-order line at high rotation which are further connected at a tri-critical point.
↳ hep-phnucl-thCPC(2020)·54 citations
14
The path from finite to infinite volume: Hadronic observables from lattice QCD
Zohreh Davoudi🇺🇸
Standard Model determinations of properties of strongly interacting systems of hadrons have become possible with the powerful method of lattice quantum chromodynamics (LQCD), a method with growing applicability and reliability. While growth in computational power and innovations in algorithmic and computational approaches have been essential in advancing the state of the field, conceptual and formal developments have played a crucial role in turning the output of LQCD computations to phenomenologically valuable results. From the invention of finite-volume technology to access physical observables by Martin Lüscher over three decades ago to date, this field has grown in scope and complexity, enabling studies of scattering amplitudes and reaction rates, as well as spectroscopy of excited states of quantum chromodynamics (QCD) and resonances. Further, LQCD studies are augmented with the inclusion of quantum electrodynamics (QED), and subtleties related to the finite volume of systems in presence of QED have been understood and largely controlled. In this talk, I focus on selected developments to give a taste of the status of the field concerning the mapping between the finite and infinite-volume physics and its state-of-the-art applications.
↳ hep-lathep-phnucl-thPoS(2018)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE