Nuclear Theory·nucl-th

Tuesday·July 30, 2019

17 papers—9 primary·8 cross-listed

01
$^{15}$ C: from Halo-EFT structure to the study of transfer, breakup and radiative-capture reactions
Laura Moschini · Jiecheng Yang · Pierre Capel
Aside from being a one-neutron halo nucleus, $^{15}$ C is interesting because it is involved in reactions of relevance for several nucleosynthesis scenarios. The aim of this work is to analyze various reactions involving $^{15}$ C, using a single structure model based on Halo EFT. To develop a Halo-EFT model of $^{15}$ C at NLO, we first extract the ANC of its ground state by analyzing $^{14}$ C(d,p) $^{15}$ C transfer data at low energy. Using this Halo-EFT description, we study the $^{15}$ C Coulomb breakup at high (605AMeV) and intermediate (68AMeV) energies using eikonal models with a consistent treatment of nuclear and Coulomb interactions at all orders, and proper relativistic corrections. Finally, we study the $^{14}$ C(n, $γ$ ) $^{15}$ C radiative capture. Our theoretical cross sections are in good agreement with experimental data for all reactions, thereby assessing the robustness of the $^{15}$ C Halo-EFT model. Since a simple NLO description is enough to reproduce all data, the only nuclear-structure observables that matter are the binding energy and its ANC, showing that all the reactions considered are purely peripheral. In particular, it confirms the ANC value obtained for the $^{15}$ C ground state: 1.59 $\pm$ 0.06fm $^{- 1}$ . Our model provides also a new estimate of the radiative-capture cross section at astrophysical energy (23.3keV): 4.66 $\pm$ 0.14 $μ$ b. Including a Halo-EFT description of $^{15}$ C within precise models of reactions is confirmed to be an excellent way to relate the nucleus reaction cross sections and structure. Its systematic expansion enables us to deduce which nuclear-structure observables are actually probed in the collision. From this, we can infer valuable information on both the structure of $^{15}$ C and its synthesis through the $^{14}$ C(n, $γ$ ) $^{15}$ C radiative capture at astrophysical energies.
nucl-thPRC(2019)·30 citations
02
Coherent-Nuclear Pion Photoproduction and Neutron Radii
Gerald A. Miller🇺🇸
{ {\bf Background:} Knowing the difference between the neutron and proton densities of nuclei is a significant topic because of its importance for understanding neutron star structures and cooling mechanisms. The coherent-nuclear photoproduction of pions, $(\g, π^{0})$ , combined with elastic electron scattering, has been suggested to be a very accurate probe of density differences. {\bf Purpose:} Study the $(\g, π^{0})$ reaction mechanism so as to better access the uncertainties involved in extracting the neutron density. {\bf Methods:} Include the effects of final-state pion-nucleus charge-exchange reactions on the cross section and study the influence of the non-zero spatial extent of the proton. {\bf Results:} The effects of final-state charge-exchange increase the cross section between 6\% and 5\%, generally decreasing as the momentum transfer increases. This leads to an increase of the extracted neutron skin distance by about 50\%. The validity of the previous treatments of the proton size is confirmed. {\bf Conclusion:} The model dependence of the theoretically computed cross section increases the total systematic uncertainty (experiment plus theory) in extracting the neutron skin from the $(\g, π^{0})$ cross section by at least a factor of three. }
nucl-thhep-phnucl-exPRC(2019)·11 citations
03
Removing the Wigner bound in non-perturbative effective field theory
Saar Beck🇮🇱 · Betzalel Bazak🇮🇱 · Nir Barnea🇮🇱
The Wigner bound, setting an upper limit on the scattering effective range, is examined at different orders of contact effective field theory. Using cutoff regulator we show that the bound loosens when higher orders of the theory are considered. For a sharp and a Gaussian regulators, we conjecture an analytic formula for the dependence of the Wigner bound on the theory's order. It follows that the bound vanishes in the limit of infinite order. Using a concrete numerical example we demonstrate that the above surmise still holds after renormalization at finite cutoff. Studying the 3-body system with this example, we have found that limiting the permissible range of cutoffs by the Wigner bound, we avoid the Thomas collapse, and don't need to promote the 3-body force to leading order.
nucl-thPLB(2020)·9 citations
04
The effect of single-particle space-momentum angle distribution on two-pion HBT correlation in high-energy heavy-ion collisions
Hang Yang🇨🇳 · Qichun Feng · Yanyu Ren · Jingbo Zhang🇨🇳 · Lei Huo
Using several source models, we analyze the transverse momentum dependence of HBT radii in the relativistic heavy-ion collisions. The results indicate that the single-particle space-momentum angle distribution plays an important role in the transverse momentum dependence of HBT radii. In a cylinder source, we use several formulas to describe the transverse momentum dependence of HBT radii and the single-particle space-momentum angle distribution. We also make a numerical connection between them in the transverse plane.
nucl-thCPC(2020)·3 citations
05
Hybrid star within the framework of a lowest-order constraint variational method
S. Khanmohamadi🇮🇷 · H.R. Moshfegh🇮🇷 · S.Atashbar Tehrani🇮🇷
The hadron-quark phase transition in the core of heavy neutron star (NS) has been studied. For the hadronic sector, we have used the lowest-order constraint variational method by employing $A V_{18}$ , $A V_{14}$ , $U V_{14}$ , and Reid $68$ two-body nucleon-nucleon forces supplemented by the phenomenological Urbana-type three-body force. We have adopted the MIT bag model as well as three-flavor version of the Nambu- Jona-Lasinio (NJL) model to describe the quark phase. The equation of state (EOS) of a hybrid star (HS) is presented by combining two EOS of the hadronic sector and quark sector of a star, which are derived from independent models or theories. The hadron-quark transition is constructed by considering a sharp phase transition, i.e., Maxwell construction. The structure of the HS is calculated and reported by solving Tolman-Oppenheimer-Volkoff equations. Finally the radii and tidal deformability of purely NS and HS for the mass of $1.4 M_{⊙}$ is computed and new constraints on these quantities are checked. The maximum mass of HS is found more than $2 M_{⊙}$ for both the NJL and MIT bag models. However, the maximum mass of $1.796 M_{⊙}$ ( $1.896 M_{⊙}$ ) was the best result that would be calculated for a stable HS with the pure quark core within the MIT (NJL) model. All the hybrid EOS fulfill the constraints on radii and tidal deformability extracted from the binary GW170817 for HSs. A comprehensive analysis on the structure of purely NS and HS and also compactness, tidal Love number, and tidal deformability for the star with the mass of 1.4 $M_{⊙}$ has been conducted for various EOS of the hadron sector and several parameter sets of the quark EOS. The results achieved in this study are in good concurrence with the other calculations reported on this subject.
nucl-thastro-ph.HEhep-phPRD(2020)·12 citations
06
Energy loss of heavy quarks in the isotropic collisional hot QCD medium
Mohammad Yousuf Jamal🇮🇳 · Vinod Chandra🇮🇳
Collisional energy loss of heavy partons (charm and bottom quarks) has been determined within the framework of semi-classical transport theory implying Bhatnagar-Gross-Krook (BGK) collisional kernel. Hot QCD medium effects have been incorporated while employing a quasi-particle description of the medium in terms of effective gluons, quarks and antiquarks with respective temperature dependent effective fugacities. The momentum dependence of the energy loss for charm and bottom quark has been investigated. It is observed that with the increase in momentum of the heavy quarks, the loss increases sharply for the smaller values and reaches a saturation later. Further, as compared to the charm quark, bottom quark losses less energy at a particular momentum and collisional frequency. The energy loss is seen to increase with increasing collisional frequency. We also provide a comparative study of the results obtained using BGK-kernel than those using relaxation time approximation (RTA)-kernel and found them consistent with each other. The medium effects in all the situations are seen to play quite significant role.
nucl-thhep-phEPJC(2019)·21 citations
07
Smallest QCD Droplet and Multiparticle Correlations in pp Collisions
Seyed Farid Taghavi🇩🇪
The collective evolution of produced matter in heavy-ion collisions is effectively described by hydrodynamics from time scales greater than the inverse of the temperature, $τ ≳ 1/ T$ . In the context of the Gubser solution, I show that the hydrodynamization condition $τ T ≳ 1$ is translated into an allowed domain in the spatial system size and the final multiplicity for hydrodynamics applicability. It turns out that the flow measurements in pp collisions are inside the domain of validity. I predict that by approaching the boundaries of the allowed domain the hydrodynamic response to the initial ellipticity changes its sign. I follow a rather model-independent approach for the initial state where, instead of modeling the initial energy density of individual events, the initial system size and ellipticity event-by-event fluctuation are modeled. The model, initial state fluctuation+Gubser solution+Cooper-Frye freeze-out, describes the multiplicity and transverse momentum dependence of two-point and four-point correlation functions ( $c_{2} {2}$ and $c_{2} {4}$ ) in an accurate agreement with pp collision experimental measurements. In particular, the sign of the four-point correlation function is the same as the observation, which failed to be described correctly in previous studies. I also predict a signal for the sign change in the hydrodynamic response that can be inspected in future experimental measurements of two-point and four-point correlation functions at lower multiplicities.
nucl-thhep-phnucl-exPRC(2021)·11 citations
08
Structure of 16C from analyses of proton scattering data and the B(E2) problem
S. Karataglidis🇿🇦 · K. Murulane🇿🇦
The B(E2) value for the decay of the 2+_1 state in 16C to ground has been the subject of much discussion. Analyses assuming a simple model of two neutrons coupled to a 14C core of the available data, which extend over an order of magnitude,gives reasonable agreement but with an inclusion of a large effective charge for the neutrons. To assess this situation, a large scale (2+4)hw shell model calculation of 16C has been made from which the wave functions have been used to obtain the B(E2) value. As a check, comparison is made with available data on the spectrum of 16C and intermediate-energy elastic proton scattering.
nucl-thPRC(2020)·3 citations
09
Ruling out the supersoft high-density symmetry energy from the discovery of PSR J0740+6620 with mass $2.1 4_{- 0.09}^{+ 0.10} M_{⊙}$
Ying Zhou🇨🇳 · Lie-Wen Chen🇨🇳
Using the very recently reported mass $2.1 4_{- 0.09}^{+ 0.10} M_{⊙}$ of PSR J0740+6620 together with the data of finite nuclei and the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy-ion collisions, we show that the symmetry energy $E_{sym} (n)$ cannot be supersoft so that it becomes negative at suprasaturation densities in neutron stars (NSs) and thus may make the NS have a pure neutron matter core. This is in contrast to the fact that using the mass $2.01 \pm 0.04 M_{⊙}$ of PSR J0348+0432 as the NS maximum mass cannot rule out the supersoft high-density $E_{sym} (n)$ . Furthermore, we find the stiffer high-density $E_{sym} (n)$ based on the existence of $2.14 M_{⊙}$ NSs leads to a strong constraint of $Λ_{1.4} \geq 34 8_{- 51}^{+ 88}$ for the dimensionless tidal deformability of the canonical $1.4 M_{⊙}$ NS.
nucl-thastro-ph.HEastro-ph.SRhep-ph+1ApJ(2019)·33 citations
10
Thermodynamic Geometry of the Quark-Meson Model
Bonan Zhang🇨🇳 · Shen-Song Wan🇨🇳 · Marco Ruggieri🇨🇳
We study the thermodynamic geometry of the Quark-Meson model, focusing on the curvature, $R$ , around the chiral crossover at finite temperature and baryon chemical potential. We find a peculiar behavior of $R$ in the crossover region, in which the sign changes and a local maximum develops; in particular, the height of the peak of $R$ in the crossover region becomes large in proximity of the critical endpoint and diverges at the critical endpoint. The appearance of a pronounced peak of $R$ close to the critical endpoint supports the idea that $R$ grows with the correlation volume around the phase transition. We also analyze the mixed fluctuations of energy and baryon number, $⟨ Δ U Δ N ⟩$ , which grow up substantially in proximity of the critical endpoint: in the language of thermodynamic geometry these fluctuations are responsible for the vanishing of the determinant of the metric, which results in thermodynamic instability and are thus related to the appearance of the second order phase transition at the critical endpoint.
↳ hep-phhep-latnucl-thPRD(2020)·12 citations
11
A global extraction of the jet transport coefficient in cold nuclear matter
Peng Ru🇨🇳 · Zhong-Bo Kang🇺🇸 · Enke Wang🇨🇳 · Hongxi Xing🇨🇳 · Ben-Wei Zhang🇨🇳
Within the framework of the generalized QCD factorization formalism, we perform the first global analysis of the jet transport coefficient ( $q^$ ) for cold nuclear matter. The analysis takes into account the world data on transverse momentum broadening in semi-inclusive electron-nucleus deep inelastic scattering, Drell-Yan dilepton and heavy quarkonium production in proton-nucleus collisions, as well as the nuclear modification of the structure functions in deep inelastic scattering, comprising a total of 215 data points from 8 data sets. For the first time, we clarify quantitatively the universality and probing scale dependence of the nuclear medium property as encoded in $q^$ . We expect that the determined parametrization of $q^$ in cold nuclear matter will have significant impact on precise identification of the transport property of hot dense medium created in heavy ion collisions.
↳ hep-phhep-exnucl-exnucl-thPRD(2021)·46 citations
12
Level scheme of $^{153}$ Sm obtained from $^{152}$ Sm( $n_{t h}$ , $γ$ ) reaction using $γ - γ$ coincidence spectrometer
Nguyen Ngoc Anh · Nguyen Quang Hung · Nguyen Xuan Hai · Pham Dinh Khang · A. M. Sukhovoj · L. V. Mitsyna · Ho Huu Thang · Le Hong Khiem
The level scheme of the compound $^{153}$ Sm nucleus formed via the $^{152}$ Sm( $n_{t h}$ , $γ$ ) reaction is studied by using the $γ - γ$ coincidence spectrometer at Dalat Nuclear Research Institute, Vietnam. All the gamma cascades, which correspond to the decays from the compound state to 12 final levels of 0 ( $\frac{3}{2}^{+}$ ), 7.535 ( $\frac{5}{2}^{+}$ ), 35.844 ( $\frac{3}{2}^{-}$ ), 90.875 ( $\frac{5}{2}^{-}$ ), 126.412 ( $\frac{1}{2}^{-}$ ), 127.298 ( $\frac{3}{2}^{-}$ ), 182.902 ( $\frac{5}{2}^{-}$ ), 321.113 ( $\frac{3}{2}^{+}$ ), 404.129 ( $\frac{1}{2}^{-}$ ), 405.470 ( $\frac{3}{2}^{-}$ ), 414.924 ( $\frac{1}{2}^{+}$ ), and 481.088 ( $\frac{3}{2}^{+}$ ) keV, have been measured. A total number of 386 cascades corresponding to 576 gamma transitions has been detected. Among these cascades, 103 primary gamma transitions together with their corresponding intermediate levels and 299 secondary transitions have been determined. In addition, 29 primary gamma transitions, 42 intermediate levels, and 8 secondary transitions have been found to be the same as those extracted from the ENSDF data. The remain 74 primary gamma transitions, 61 intermediate levels, and 291 secondary transitions are therefore considered as the new data. In particular, based on an assumption that most of the transitions are dipole, we have tentatively assigned the unique spin value of $\frac{3}{2} ℏ$ for 53 observed intermediate levels corresponding to the cascades from the compound state to the final ones of 7.535 ( $\frac{5}{2}^{+}$ ), 90.875 ( $\frac{5}{2}^{-}$ ), and 182.902 ( $\frac{5}{2}^{-}$ ) keV, whereas the remain levels are assigned with the spin values in the range of $[\frac{1}{2}, \frac{3}{2}] ℏ$ ...
↳ nucl-exnucl-th0 citations
13
Jet suppression from small to intermediate to large radius
Daniel Pablos🇳🇴
We present predictions for jet suppression from small to intermediate to very large radius, for low and very high energy jets created in heavy ion collisions at the LHC. We use the hybrid strong/weak coupling model for jet quenching that combines perturbative shower evolution with an effective strongly coupled description of the energy and momentum transfer from the jet into the hydrodynamic quark-gluon plasma. Because of momentum conservation, the wake created by the jet enhances or depletes the amount of particles generated at the freeze-out hypersurface depending on their orientation with respect to the jet. Within such framework we find that jet suppression is surprisingly independent of the anti- $k_{T}$ radius $R$ , first slightly increasing as one increases $R$ , then at larger values of $R$ very slowly decreasing. This nearly independence of jet suppression with increasing values of $R$ arises from two competing effects, namely the larger energy loss of the hard jet components, which tends to increase suppression, versus the partial recovery of the lost energy due to medium response, reducing suppression. We also find that the boosted medium from the recoiling jet reduces the amount of plasma in the direction opposite to it in the transverse plane, increasing the amount of jet suppression due to an over-subtraction effect. We show that this characteristic signature of the hydrodynamization of part of the jet energy can be quantified by selecting samples of dijet configurations with different relative pseudorapidities between the leading and the subleading jet.
↳ hep-phnucl-thPRL(2020)·67 citations
14
Chiral susceptibility in Nambu Jona Lasinio model: a Wigner function approach
Arpan Das🇮🇳 · Deepak Kumar🇮🇳 · Hiranmaya Mishra🇮🇳
We estimate here chiral susceptibility at finite temperature within the framework of the Nambu-Jona-Lasinio model (NJL) using the Wigner function approach. We also estimate it in the presence of chiral chemical potential ( $μ_{5}$ ) as well as a non vanishing magnetic field ( $B$ ). We use medium separation regularization scheme (MSS) to calculate the chiral condensate and corresponding susceptibility. It is observed that for a fixed value of chiral chemical potential ( $μ_{5}$ ), transition temperature increases with the magnetic field. While for the fixed value of the magnetic field, transition temperature decreases with chiral chemical potential. For a strong magnetic field, we observe non degeneracy in susceptibility for up and down type quarks.
↳ hep-phnucl-thPRD(2019)·19 citations
15
New physics from COHERENT data with improved Quenching Factor
Amir N. Khan🇩🇪 · Werner Rodejohann🇩🇪
A recent new measurement and re-analysis of past measurements suggested an improved quenching factor value and uncertainty for CsI[Na]. This implies a measurement of the COHERENT experiment of coherent elastic neutrino-nucleus scattering that is closer to the Standard Model prediction and has less uncertainty. We illustrate the impact of this improvement by revisiting fits to the Weinberg angle, neutrino magnetic moments, neutron rms and neutrino charge radii, neutrino non-standard interactions (in particular those relevant for LMA-Dark) and new scalar as well as vector bosons. Significant improvement is observed, particularly for those scenarios coherently affecting the electroweak SM process.
↳ hep-phastro-ph.HEhep-exnucl-thPRD(2019)·75 citations
16
Theory of strongly paired fermions with arbitrary short-range interactions
Jianshen Hu · Fan Wu · Lianyi He · Xia-Ji Liu · Hui Hu
We develop an effective field theory to describe the superfluid pairing in strongly interacting fermions with arbitrary short-range attractions, by extending Kaplan's idea of coupling fermions to a fictitious boson state in Nucl. Phys. B \textbf{494}, 471 (1997). This boson field is assigned with unconventional kinetic term to recover the exact scattering phase shift obtained either from scattering data or model calculations. The theory works even if the explicit form of the interaction potential has not been constructed from scattering data. The contact boson-fermion coupling allows us to go beyond mean-field to include Gaussian pair fluctuations, yielding reliable predictions on equations of state. As an application, we use our theory to address the non-univerisal ground-state energy of strongly paired fermions, due to the non-trivial momentum dependence of the phase shift characterized, for example, by effective range. We find a good agreement between our predictions and recent quantum Monte Carlo simulations on the effective-range dependence in both three and two spatial dimensions. We propose that in cold-atom experiments, the non-universal dependence in thermodynamics can be probed using dark-state optical control of Feshbach resonances.
↳ cond-mat.quant-gascond-mat.supr-connucl-thPRA(2020)·8 citations
17
Can We Observe Jet $P_{T}$ -broadening in Heavy-Ion Collisions at the LHC?
Felix Ringer🇺🇸 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸
We investigate the effect of PT-broadening on jet substructure observables in heavy-ion collisions at the LHC. As an example, we focus on the opening angle of the two branches that satisfy the soft drop grooming condition in a highly energetic jet. The medium modification of the angular distribution can provide important information on the jet transport properties of hot QCD matter. In addition, we take into account a change of the overall fraction of quark and gluon jets in heavy-ion collisions. We comment on the comparison to a recent measurement from the ALICE Collaboration.
↳ hep-phnucl-exnucl-thPLB(2020)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE