Carlo Barbieri

Dr Carlo Barbieri

+44 (0)1483 689327
11 BB 03
Please email me to set a meeting.


Research interests

Carlo Barbieri Personal Research Page


Module leader for PHYM038 Non-Linear Physics

Departmental duties

Programme Leader Maths & Physics

University roles and responsibilities

  • Chair of HPC Stakeholders Group

Previous roles

2012 - 2017
Programme Leader Maths & Physics
2013 - 2016
Internatonal exchange coordinator
2016 - 2018
Exam Officer

Courses I teach on


My publications


Sanetullaev A, Tsang MB, Lynch WG, Lee J, Bazin D, Chan KP, Coupland D, Henzl V, Henzlova D, Kilburn M, Rogers AM, Sun ZY, Youngs M, Charity RJ, Sobotka LG, Famiano M, Hudan S, Shapira D, Peters WA, Barbieri C, Hjorth-Jensen M, Horoi M, Otsuka T, Suzuki T, Utsuno Y (2014) Neutron spectroscopic factors of 55Ni hole-states from (p, d) transfer reactions,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 736 pp. 137-141
Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu), one nucleon away from 56Ni, the N = Z = 28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2 hole-state below Fermi energy. © 2014 The Authors.
Barbieri C, Soma V, Cipollone A, Navratil P, Duguet T (2014) Three-Nucleon Forces in Neutron Rich Isotopes,JPS Conference Proceedings, volume 6: Proceedings of the Conference on Advances in Radioactive Isotope Science (ARIS2014) The Physical Society of Japan
Advances in the self-consistent Green's function approach to finite nuclei are discussed, including the implementation of three-nucleon forces and the extension to the Gorkov formalism. We report results on binding energies in the nitrogen and fluorine isotopic chains, as well as first ab-initio calculations for medium-mass open-shell chains ranging from argon to titanium. Results with chiral interactions put in evidence the important role played by 3NF in neutron rich isotopes.
Cipollone A, Barbieri C, Navratil P (2015) Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain,PHYSICAL REVIEW C 92 (1) ARTN 01430 AMER PHYSICAL SOC
Barbieri C (2006) Single particle spectra based on modem effective interactions, PHYSICS LETTERS B 643 (5) pp. 268-272 ELSEVIER SCIENCE BV
Barbieri C, Charity R, Dickhoff W, Sobotka L (2010) Toward a Global Dispersive Optical Model for the Driplines,NUCLEAR PHYSICS A 834 (1-4) pp. 788C-791C Elsevier
A dispersive-optical-model analysis has been performed for both protons and neutrons on 40,42,44,48Ca isotopes. The fitted potentials describe accurately both scattering and bound quantities and extrapolate well to other stable nuclei. Further experimental infor- mation will be gathered to constrain extrapolations toward the driplines.
Reifarthl R, Altstadt S, Goebell K, Heftrich T, Heil M, Koloczek A, Langer C, Plag R, Pohl M, Sonnabend K, Weigand M, Adachi T, Aksouh F, Al-Khalili J, AlGarawi M, AlGhamdi S, Alkhazov G, Alkhomashi N, Alvarez-Pol H, Alvarez-Rodriguez R, Andreev V, Andrei B, Atar L, Aumann T, Adeichikov V, Bacri C, Bagchi S, Barbieri C, Beceiro S, Beck C, Beinrucker C, Belier G, Bemmerer D, Bendel M, Benlliure J, Benzoni G, Berjillos R, Bertini D, Bertulani C, Bishop S, Blasi N, Bloch T, Blumenfeld Y, Bonaccorso A, Boretzky K, Botvina A, Boudard A, Boutachkov P, Boztosun I, Bracco A, Brambilla S, Briz Monago J, Caamano M, Caesar C, Camera F, Casarejos E, Catford W, Cederkall J, Cederwall B, Chartier M, Chatillon A, Cherciu M, Chulkov L, Coleman-Smith P, Cortina-Gil D, Crespi F, Crespo R, Cresswell J, Csatlos M, Dechery F, Davids B, Davinson T, Derya V, Detistov P, Diaz Fernandez P, DiJuliot D, Dmitry S, Dore D, Duenas J, Dupont E, Egelhof P, Egorova I, Elekes Z, Enders J, Endres J, Ershov S, Ershova O, Fernandez-Dominguez B, Fetisov A, Fiori E, Fomichev A, Fonseca M, Fraile L, Freer M, Friese J, Borge MG, Galaviz Redondo D, Gannon S, Garg U, Gasparic I, Gasques L, Gastineau B, Geissel H, Gernhaeuser R, Ghosh T, Gilbert M, Glorius J, Golubev P, Gorshkov A, Gourishett A, Grigorenko L, Gulyas J, Haiduc M, Hammache F, Harakeh M, Hass M, Heine M, Hennig A, Henriques A, Herzberg R, Holl M, Ignatov A, Ignatyuk A, Ilieva S, Ivanov M, Iwasa N, Jakobsson B, Johansson H, Jonson B, Joshi P, Junghans A, Jurado B, Koerner G, Kalantar N, Kanungo R, Kelic-Heil A, Kezzar K, Khan E, Khanzadeev A, Kiselev O, Kogimtzis M, Koerper D, Kraeckmann S, Kroell T, Kruecken R, Krasznahorkay A, Kratz J, Kresan D, Krings T, Krumbholz A, Krupko S, Kulessa R, Kumar S, Kurz N, Kuzmin E, Labiche M, Langanke K, Lazarus I, Le Bleis T, Lederer C, Lemasson A, Lemmon R, Liberati V, Litvinov Y, Loeher B, Lopez Herraiz J, Muenzenberg G, Machado J, Maev E, Mahata K, Mancusi D, Marganiec J, Martinez Perez M, Marusov V, Mengoni D, Million B, Morcelle V, Moreno O, Movsesyan A, Nacher E, Najafi M, Nakamura T, Naqvi F, Nikolski E, Nilsson T, Nociforo C, Nolan P, Novatsky B, Nyman G, Ornelas A, Palit R, Pandit S, Panin V, Paradela C, Parkar V, Paschalis S, Pawlowski P, Perea A, Pereira J, Petrache C, Petri M, Pickstone S, Pietralla N, Pietri S, Pivovarov Y, Potlog P, Prokofiev A, Rastrepina G, Rauscher T, Ribeiro G, Ricciardi M, Richter A, Rigollet C, Riisager K, Rios A, Ritter C, Frutos TR, Rodriguez Vignote J, Roeder M, Romig C, Rossi D, Roussel-Chomaz P, Rout P, Roy S, Soederstroem P, Sarkar MS, Sakuta S, Salsac M, Sampson J, del Rio Saez JS, Sanchez Rosado J, Sanjari S, Sarriguren P, Sauerwein A, Savran D, Scheidenberger C, Scheit H, Schmidt S, Schmitt C, Schnorrenberger L, Schrock P, Schwengner R, Seddon D, Sherrill B, Shrivastava A, Sidorchuk S, Silva J, Simon H, Simpson E, Singh P, Slobodan D, Sohler D, Spieker M, Stach D, Stan E, Stanoiu M, Stepantsov S, Stevenson P, Strieder F, Stuhl L, Suda T, Suemmerer K, Streicher B, Taieb J, Takechi M, Tanihata I, Taylor J, Tengblad O, Ter-Akopian G, Terashima S, Teubig P, Thies R, Thoennessen M, Thomas T, Thornhill J, Thungstrom G, Timar J, Togano Y, Tomohiro U, Tornyi T, Tostevin J, Townsley C, Trautmann W, Trivedi T, Typel S, Uberseder E, Udias J, Uesaka T, Uvarov L, Vajta Z, Velho P, Vikhrov V, Volknandt M, Volkov V, von Neumann-Cose P, von Schmid M, Wagner A, Wamers F, Weick H, Wells D, Westerberg L, Wieland O, Wiescher M, Wimmer C, Wimmer K, Winfield JS, Winkel M, Woods P, Wyss R, Yakorev D, Yavor M, Cardona JZ, Zartova I, Zerguerras T, Zgura I, Zhdanov A, Zhukov M, Zieblinski M, Zilges A, Zuber K (2016) Nuclear astrophysics with radioactive ions at FAIR, Nuclear Physics in Astrophysics VI (NPA6). Journal of Physics: Conference Series 665 (1) IOP Publishing
The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process, ²-decay chains. These nuclei are attributed to the p and rp process.

For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections.

The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.

Barbieri C, Caurier E, Langanke K, Martinez-Pinedo G (2008) Reply to "Comment on 'Pygmy dipole response of proton-rich argon nuclei in random-phase approximation and no-core shell model' ",PHYSICAL REVIEW C 78 (3) ARTN 039802 AMER PHYSICAL SOC
The self-consistent random phase approximation (RPA) based on a correlated realistic nucleon-nucleon interaction is used to evaluate correlation energies in closed-shell nuclei beyond the Hartree-Fock level. The relevance of contributions associated with charge exchange excitations as well as the necessity to correct for the double counting of the second order contribution to the RPA ring summation are emphasized. Once these effects are properly accounted for, the RPA ring summation provides an efficient tool to assess the impact of long-range correlations on binding energies throughout the whole nuclear chart, which is of particular importance when starting from realistic interactions.
Barbieri C, Rohe D, Sick I, Lapikas L (2005) Effect of kinematics on final state interactions in (e, e ' p) reactions, PHYSICS LETTERS B 608 (1-2) pp. 47-52 ELSEVIER SCIENCE BV
Barbieri C, Van Neck D, Degroote M (2012) Accuracy of the Faddeev random phase approximation for light atoms,Physical Review A (Atomic, Molecular and Optical Physics) 85 (1) 012501 American Physical Society
The accuracy of the Faddeev random phase approximation (FRPA) method is tested by evaluating total and ionization energies in the basis-set limit. A set of light atoms up to Ar is considered. Comparisons are made with the results of coupled-cluster singles and doubles (CCSD), with third-order algebraic diagrammatic construction [ADC(3)], and with the experiment. It is seen that even for two-electron systems, He and Be2+, the inclusion of RPA effects leads to satisfactory results, and therefore it does not overcorrelate the ground state. The FRPA becomes progressively better for larger atomic numbers, where it gives H5 mH more correlation energy, and it shifts ionization potentials by 2?10 mH with respect to the similar ADC(3) method. The ionization potentials from FRPA tend to reduce the discrepancies with the experiment.
Barbieri C, Dickhoff WH (2005) Self-consistent Green's function calculations of O-16 at small missing energies, JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS 31 (8) pp. S1301-S1309 IOP PUBLISHING LTD
We review some applications of self-consistent Green's function theory to studies of one- and two-nucleon structure in finite nuclei. Large-scale microscopic calculations that employ realistic nuclear forces are now possible. Effects of long-range correlations are seen to play a dominant role in determining the quenching of absolute spectroscopic factors. They also enhance considerably (e,e'pn) cross sections in superparallel kinematics, in agreement with observations
Barbieri C (2009) Role of Long-Range Correlations in the Quenching of Spectroscopic Factors,PHYSICAL REVIEW LETTERS 103 (20) ARTN 202502 AMER PHYSICAL SOC
Barbieri C, Lapikas L (2004) Effects of rescattering in (e,e ' p) reactions within a semiclassical model,PHYSICAL REVIEW C 70 (5) ARTN 054612 AMERICAN PHYSICAL SOC
Somà V, Duguet T, Barbieri C (2012) Self-consistent Gorkov Green's function calculations of one-nucleon spectral properties,Journal of Physics: Conference Series 337 (1) IOP Publishing
Waldecker SJ, Barbieri C, Dickhoff WH (2011) Microscopic self-energy calculations and dispersive optical-model potentials,PHYSICAL REVIEW C 84 (3) ARTN 034616 AMER PHYSICAL SOC
Barbieri C, Dickhoff WH (2002) Faddeev treatment of long-range correlations and the one-hole spectral function of O-16,PHYSICAL REVIEW C 65 (6) ARTN 064313 AMERICAN PHYSICAL SOC
Barbieri C, Van Neck D (2009) Ab-initio Green's Functions Calculations of Atoms,PERSPECTIVES IN NUCLEAR PHYSICS 1120 pp. 104-108 AMER INST PHYSICS
Avgoulea M, Gangrsky YP, Marinova KP, Zemlyanoi SG, Fritzsche S, Iablonskyi D, Barbieri C, Simpson EC, Stevenson PD, Billowes J, Campbell P, Cheal B, Tordoff B, Bissell ML, Forest DH, Gardner MD, Tungate G, Huikari J, Nieminen A, Penttila H, Aysto J (2011) Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers,JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS 38 (2) ARTN 025104 IOP PUBLISHING LTD
Middleton DG, Annand JRM, Barbieri C, Giusti C, Grabmayr P, Hehl T, MacGregor IJD, Martin I, McGeorge JC, Moschini F, Pacati FD, Schwamb M, Watts D (2010) Knockout of proton-neutron pairs from O-16 with electromagnetic probes, EUROPEAN PHYSICAL JOURNAL A 43 (2) pp. 137-143 SPRINGER
Somà V, Barbieri C, Duguet T (2013) Ab-initio self-consistent Gorkov-Green?s function calculations of semi-magic nuclei II. Numerical implementation at second order with a two-nucleon interaction, Physical Review C: Nuclear Physics 89 024323
The newly developed Gorkov-Green?s function approach represents a promising path to the ab initio description of medium-mass open-shell nuclei. We discuss the implementation of the method at second order with a two-body interaction, with particular attention to the numerical solution of Gorkov?s equation. Different sources of theoretical error and degrees of self-consistency are investi- gated. We show that Krylov projection techniques with a multi-pivot Lanczos algorithm efficiently handle the growth of poles in the one-body Green?s function when Gorkov?s equation is solved self- consistently. The end result is a tractable, accurate and gently scaling ab initio scheme applicable to full isotopic chains in the medium-mass region.
Barbieri C, Jennings BK (2005) Nucleon-nucleus optical potential in the particle-hole approach,PHYSICAL REVIEW C 72 (1) ARTN 014613 AMERICAN PHYSICAL SOC
Somà V, Barbieri Carlo, Cipollone A, Duguet T, Navrátil P (2013) Three-nucleon forces in exotic open-shell isotopes,European Physical Journal: Web of Conferences
Advances in the self-consistent Green's function approach to finite nuclei are discussed, including the implementation of three-nucleon forces and the extension to the Gorkov formalism. We report results on binding energies in the nitrogen and fluorine isotopic chains, as well as spectral functions of 22O. The application to medium-mass open-shell systems is illustrated by separation energy spectra of two argon isotopes, which are compared to one-neutron removal experiments.
Papuga J, Bissell ML, De Rydt M, Garcia Ruiz RF, Heylen H, Neyens G, Rajabali MM, Kreim K, Blaum K, Yordanov DT, Barbieri C, Duguet T, Somà V, Kowalska M, Neugart R, Nörtershäuser W, Sánchez R, Smirnova N (2014) Shell structure of potassium isotopes deduced from their magnetic moments, Physical Review C - Nuclear Physics 90 (3)
Background: Ground-state spins and magnetic moments are sensitive to the nuclear wave function, thus they are powerful probes to study the nuclear structure of isotopes far from stability. Purpose: Extend our knowledge about the evolution of the 1/2+ and 3/2+ states for K isotopes beyond the N=28 shell gap. Method: High-resolution collinear laser spectroscopy on bunched atomic beams. Results: From measured hyperfine structure spectra of K isotopes, nuclear spins, and magnetic moments of the ground states were obtained for isotopes from N=19 up to N=32. In order to draw conclusions about the composition of the wave functions and the occupation of the levels, the experimental data were compared to shell-model calculations using SDPF-NR and SDPF-U effective interactions. In addition, a detailed discussion about the evolution of the gap between proton 1d3/2 and 2s1/2 in the shell model and ab initio framework is also presented. Conclusions: The dominant component of the wave function for the odd-A isotopes up to K45 is a À1d3/2-1 hole. For K47,49, the main component originates from a À2s1/2-1 hole configuration and it inverts back to the À1d3/2-1 in K51. For all even-A isotopes, the dominant configuration arises from a À1d3/2-1 hole coupled to a neutron in the ½1f7/2 or ½2p3/2 orbitals. Only for K48, a significant amount of mixing with À2s1/2-1 - ½(pf) is observed leading to a IÀ=1- ground state. For K50, the ground-state spin-parity is 0- with leading configuration À1d3/2-1 - ½2p3/2-1.
Cipollone A, Barbieri C, Navratil P (2013) Isotopic Chains Around Oxygen from Evolved Chiral Two- and Three-Nucleon Interactions,PHYSICAL REVIEW LETTERS 111 (6) ARTN 062501 AMER PHYSICAL SOC
Barbieri C (2006) Final state interactions in electron scattering at high missing energies and momenta, NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS 159 pp. 174-179 ELSEVIER SCIENCE BV
Barbieri C, Van Neck D, Dickhoff WH (2007) Quasiparticles in neon using the Faddeev random-phase approximation,PHYSICAL REVIEW A 76 (5) ARTN 052503 AMER PHYSICAL SOC
Barbieri C, Jennings BK (2005) Study of the O-16(p,gamma) reaction at astrophysical energies, NUCLEAR PHYSICS A 758 pp. 395C-398C ELSEVIER SCIENCE BV
Middleton DG, Annand JRM, Barbieri C, Barneo P, Blok HP, Boehm R, Distler MO, Friedrich J, Giusti C, Glazier DI, Grabmayr P, Hehl T, Heim J, Hesselink WHA, Jans E, Kohl M, Lapikas L, MacGregor IJD, Martin I, McGeorge JC, Merkel H, Moschini F, Rosner G, Seimetz M, de Vries H, Walcher T, Watts DP, Zihlmann B (2006) First measurements of the O-16(e, e ' pn)N-14 reaction, EUROPEAN PHYSICAL JOURNAL A 29 (3) pp. 261-270 SPRINGER
Soma V, Cipollone A, Barbieri C, Navratil P, Duguet T (2014) Chiral two- and three-nucleon forces along medium-mass isotope chains,PHYSICAL REVIEW C 89 (6) ARTN 061301 AMER PHYSICAL SOC
Barbieri C, Giusti C, Pacati FD, Dickhoff WH (2004) Effects of nuclear correlations on the O-16(e,e ' pN) reactions to discrete final states,PHYSICAL REVIEW C 70 (1) ARTN 014606 AMER PHYSICAL SOC
Dickhoff WH, Barbieri C (2004) Self-consistent Green's function method for nuclei and nuclear matter, PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL. 52, NO 2 52 (2) pp. 377-496 ELSEVIER SCIENCE BV
Lapoux V, Soma V, Barbieri C, Hergert H, Holt JD, Stroberg SR (2016) Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces,PHYSICAL REVIEW LETTERS 117 (5) ARTN 052501 AMER PHYSICAL SOC
Rosenbusch M, Ascher P, Atanasov D, Barbieri C, Beck D, Blaum K, Borgmann C, Breitenfeldt M, Cakirli RB, Cipollone A, George S, Herfurth F, Kowalska M, Kreim S, Lunney D, Manea V, Navrátil P, Neidherr D, Schweikhard L, Somà V, Stanja J, Wienholtz F, Wolf RN, Zuber K (2015) Probing the N=32 Shell Closure below the Magic Proton Number Z=20: Mass Measurements of the Exotic Isotopes ^{52,53}K.,Physical review letters 114 (20)
The recently confirmed neutron-shell closure at N=32 has been investigated for the first time below the magic proton number Z=20 with mass measurements of the exotic isotopes (52,53)K, the latter being the shortest-lived nuclide investigated at the online mass spectrometer ISOLTRAP. The resulting two-neutron separation energies reveal a 3 MeV shell gap at N=32, slightly lower than for 52Ca, highlighting the doubly magic nature of this nuclide. Skyrme-Hartree-Fock-Bogoliubov and ab initio Gorkov-Green function calculations are challenged by the new measurements but reproduce qualitatively the observed shell effect.
Barbieri C, Caurier E, Langanke K, Martinez-Pinedo G (2008) Pygmy dipole response of proton-rich argon nuclei in random-phase approximation and no-core shell model,PHYSICAL REVIEW C 77 (2) ARTN 024304 AMER PHYSICAL SOC
Somà V, Duguet T, Barbieri C (2011) Gorkov self-consistent Green's function calculations of semi-magic nuclei,Journal of Physics: Conference Series 321 (1)
The first nuclear structure application of the newly developed Gorkov self-consistent Green's function method is presented. The approach aims to describe many-nucleon systems from an ab-initio standpoint featuring an explicit treatment of pairing correlations. In the present work calculations of binding energies of calcium isotopes are reported and compared with experimental data and other theoretical references.
Barbieri C (2010) Toward an Ab-initio description of quasiparticle properties, CERN-Proceedings 1 pp. 137-144
Preliminary ab-initio applications of many-body Green's function theory to the ground state of 4He suggest that high accuracy can be achieved in the so-called Faddeev-random-phase-approximation method. We stress the potentialities of this approach for microscopic studies of medium-large nuclei and report applications to 1s0d and 1p0f-shell nuclei. In particular, we discuss the role of long-range correlations on spectroscopic factors and their dependence on asymmetry.
Degroote M, Van Neck D, Barbieri C (2011) Faddeev Random Phase Approximation for molecules, Computer Physics Communications 182 (9) pp. 1995-1998
Al-Khalili J, Barbieri C, Escher J, Jennings BK, Sparenberg JM (2003) Many-body approach to proton emission and the role of spectroscopic factors,PHYSICAL REVIEW C 68 (2) ARTN 024314 AMERICAN PHYSICAL SOC
Barbieri C, Hjorth-Jensen M (2009) Quasiparticle and quasihole states of nuclei around Ni-56,PHYSICAL REVIEW C 79 (6) ARTN 064313 AMER PHYSICAL SOC
Flavigny F, Gillibert A, Nalpas L, Obertelli A, Keeley N, Barbieri C, Beaumel D, Boissinot S, Burgunder G, Cipollone A, Corsi A, Gibelin J, Giron S, Guillot J, Hammache F, Lapoux V, Matta A, Pollacco EC, Raabe R, Rejmund M, De Séreville N, Shrivastava A, Signoracci A, Utsuno Y (2013) Limited asymmetry dependence of correlations from single nucleon transfer,Physical Review Letters 110 (12)
Single nucleon pickup reactions were performed with a 18.1 MeV/nucleon O14 beam on a deuterium target. Within the coupled reaction channel framework, the measured cross sections were compared to theoretical predictions and analyzed using both phenomenological and microscopic overlap functions. The missing strength due to correlations does not show significant dependence on the nucleon separation energy asymmetry over a wide range of 37 MeV, in contrast with nucleon removal data analyzed within the sudden-eikonal formalism. © 2013 American Physical Society.
Barbieri C (2014) Many-body propagator theory with three-body interactions: A path to exotic open shell isotopes,Journal of Physics: Conference Series 529 (1)
Ab-initio predictions of nuclei with masses up to A
Barbieri C, Dickhoff WH (2001) Faddeev description of two-hole-one-particle motion and the single-particle spectral function,PHYSICAL REVIEW C 63 (3) ARTN 034313 AMERICAN PHYSICAL SOC
Barbieri C (2005) Contribution to the wednesday afternoon discussion on spectroscopic factors,Reaction Mechanisms for Rare Isotope Beams 791 pp. 57-60 AMER INST PHYSICS
Somà V, Barbieri C, Duguet T (2013) Ab initio Gorkov-Green's function calculations of open-shell nuclei,Physical Review C - Nuclear Physics 87 (1)
We present results from a new ab initio method that uses the self-consistent Gorkov-Green's function theory to address truly open-shell systems. The formalism has been recently worked out up to second order and is implemented here in nuclei on the basis of realistic nuclear forces. Benchmark calculations indicate that the method is in agreement with other ab initio approaches in doubly closed shell 40Ca and 48Ca. We find good convergence of the results with respect to the basis size in 44Ca and 74Ni and discuss quantities of experimental interest including ground-state energies, pairing gaps, and particle addition and removal spectroscopy. These results demonstrate that the Gorkov method is a valid alternative to multireference approaches for tackling degenerate or near-degenerate quantum systems. In particular, it increases the number of mid-mass nuclei accessible in an ab initio fashion from a few tens to a few hundred. © 2013 American Physical Society.
Middleton DG, Annand JRM, Barbieri C, Barneo P, Bartsch P, Baumann D, Bermuth J, Bosnar D, Blok HP, Boehm R, Ding M, Distler MO, Elsner D, Friedrich J, Giusti C, Glazier DI, Grabmayr P, Groezinger S, Hehl T, Heim J, Hesselink WHA, Jans E, Klein F, Kohl M, Lapikas L, MacGregor IJD, Martin I, McGeorge JC, Merkel H, Merle P, Moschini F, Mueller U, Pospischil T, Rosner G, Schmieden H, Seimetz M, Suele A, de Vries H, Walcher T, Watts DP, Weis M, Zihlmann B (2006) First measurements of the O-16(e, e ' pn)N-14 reaction (vol 29, pg 261, 2006), EUROPEAN PHYSICAL JOURNAL A 30 (2) pp. 469-469 SPRINGER
Somà V, Duguet T, Barbieri C (2011) Ab initio self-consistent Gorkov-Green's function calculations of semimagic nuclei: Formalism at second order with a two-nucleon,Physical Review C (Nuclear Physics) 84 (6) 064317 American Physical Society
An ab initio calculation scheme for finite nuclei based on self-consistent Green's functions in the Gorkov formalism is developed. It aims at describing properties of doubly magic and semimagic nuclei employing state-of-the-art microscopic nuclear interactions and explicitly treating pairing correlations through the breaking of U(1) symmetry associated with particle number conservation. The present paper introduces the formalism necessary to undertake applications at (self-consistent) second order using two-nucleon interactions in a detailed and self-contained fashion. First applications of such a scheme will be reported soon in a forthcoming publication. Future works will extend the present scheme to include three-nucleon interactions and implement more advanced truncation schemes.
Degroote M, Van Neck D, Barbieri C (2011) Faddeev random-phase approximation for molecules,Physical Review A - Atomic, Molecular, and Optical Physics 83 (4) American Physical Society
Carbone A, Cipollone A, Barbieri C, Rios Huguet A, Polls A (2013) Self-consistent Green's functions formalism with three-body interactions,Physical Review C: Nuclear Physics 88 (5) American Physical Society
We extend the self-consistent Green's functions formalism to take into account three-body interactions. We analyze the perturbative expansion in terms of Feynman diagrams and define effective one- and two-body interactions, which allows for a substantial reduction of the number of diagrams. The procedure can be taken as a generalization of the normal ordering of the Hamiltonian to fully correlated density matrices. We give examples up to third order in perturbation theory. To define nonperturbative approximations, we extend the equation of motion method in the presence of three-body interactions. We propose schemes that can provide nonperturbative resummation of three-body interactions. We also discuss two different extensions of the Koltun sum rule to compute the ground state of a many-body system.
Barbieri C, Lapikás L, Rohe D (2005) Two-step rescattering in (e,e'p) reactions,European Physical Journal A 24 (SUPPL.) pp. 85-89 Springer Verlag
This contribution reviews a calculation of two-step rescattering events in (e,e'p) reactions. A semiclassical approach is employed for different kinematics, involving both medium and large missing energies. The effects of nuclear transparency and Pauli blocking are also included. The results are of interest for experiments aimed to study short-range correlations in the spectral distribution and suggest that the effects of rescattering can be strongly reduced in parallel kinematics. The comparison with the experimental data seem to confirm that sensible measurements could be achievable with a careful choice of the kinematics. However, contributions to final state interactions beyond the ones considered here become relevant for heavy nuclei. For transverse kinematics, rescattering induce large shifts of the spectral strength that can lead to a total experimental yield much larger than the direct signal. © Società Italiana di Fisica / Springer-Verlag 2005.
Duguet T, Somà V, Lecluse S, Barbieri C, Navrátil P (2017) Ab initio calculation of the potential bubble nucleus 34Si,Physical Review C: Nuclear Physics 95 034319 American Physical Society
Background: The possibility that an unconventional depletion (referred to as a ?bubble?) occurs in the center of the charge density distribution of certain nuclei due to a purely quantum mechanical effect has attracted theoretical and experimental attention in recent years. Based on a mean-field rationale, a correlation between the occurrence of such a semibubble and an anomalously weak splitting between low angular-momentum spin-orbit partners has been further conjectured. Energy density functional and valence-space shell model calculations have been performed to identify and characterize the best candidates, among which 34 Si appears as a particularly interesting case. While the experimental determination of the charge density distribution of the unstable 34 Si is currently out of reach, ( d , p ) experiments on this nucleus have been performed recently to test the correlation between the presence of a bubble and an anomalously weak 1 / 2 ? ? 3 / 2 ? splitting in the spectrum of 35 Si as compared to 37 S .Purpose: We study the potential bubble structure of 34 Si on the basis of the state-of-the-art ab initio self-consistent Green's function many-body method. Methods: We perform the first ab initio calculations of 34 Si and 36 S . In addition to binding energies, the first observables of interest are the charge density distribution and the charge root-mean-square radius for which experimental data exist in 36 S . The next observable of interest is the low-lying spectroscopy of 35 Si and 37 S obtained from ( d , p ) experiments along with the spectroscopy of 33 Al and 35 P obtained from knock-out experiments. The interpretation in terms of the evolution of the underlying shell structure is also provided. The study is repeated using several chiral effective field theory Hamiltonians as a way to test the robustness of the results with respect to input internucleon interactions. The convergence of the results with respect to the truncation of the many-body expansion, i.e., with respect to the many-body correlations included in the calculation, is studied in detail. We eventually compare our predictions to state-of-the-art multireference energy density functional and shell model calculations. Results: The prediction regarding the (non)existence of the bubble structure in 34 Si varies significantly with the nuclear Hamiltonian used. However, demanding that the experimental charge density distribution and the root-mean-square radius of 36 S be well reproduced, a
Mcilroy Chris, Barbieri Carlo, Inoue T, Doi T, Hatsuda T (2018) Doubly magic nuclei from Lattice QCD forces at MPS = 469 MeV/c
Physical Review C 97 (2) 021303(R) American Physical Society
We perform ab initio self-consistent Green?s function calculations of the closed shell nuclei 4He, 16O and
40Ca, based on two-nucleon potentials derived from Lattice QCD simulations, in the flavor SU(3) limit and at
the pseudo-scalar meson mass of 469 MeV/c
. The nucleon-nucleon interaction is obtained using the HAL QCD
method and its short-distance repulsion is treated by means of ladder resummations outside the model space.
Our results show that this approach diagonalises ultraviolet degrees of freedom correctly. Therefore, ground
state energies can be obtained from infrared extrapolations even for the relatively hard potentials of HAL QCD.
Comparing to previous Brueckner Hartree-Fock calculations, the total binding energies are sensibly improved
by the full account of many-body correlations. The results suggest an interesting possible behaviour in which
nuclei are unbound at very large pion masses and islands of stability appear at first around the traditional doublymagic
numbers when the pion mass is lowered toward its physical value. The calculated one-nucleon spectral
distributions are qualitatively close to those of real nuclei even for the pseudo-scalar meson mass considered
Raimondi Francesco, Barbieri Carlo (2018) Algebraic diagrammatic construction formalism with three-body interactions,Physical Review C 97 (5) 054308 American Physical Society

Self-consistent Green?s function theory has recently been extended to the basic formalism needed
to account for three-body interactions [A. Carbone, A. Cipollone, C. Barbieri, A. Rios, and A. Polls, Phys. Rev.
C 88, 054326 (2013)]. The contribution of three-nucleon forces has then been included in ab initio calculations
on nuclear matter and isotopic chains of finite nuclei.


ractical applications across post Hartree-Fock methods have mostly considered the contribution of
three-nucleon interactions in an effective way, as averaged two-nucleon forces. We derive the working equations
for all possible two- and three-nucleon terms that enter the expansion of the self-energy, including interactionirreducible
(i.e. not averaged) three-nucleon diagrams.


We employ the algebraic diagrammatic construction up to third order as the organization scheme for
generating a non perturbative self-energy, in which ring (particle-hole) and ladder (particle-particle) diagrams are
resummed to all orders.


We derive expressions of the static and dynamic self-energy up to third order, by taking into account
also the set of diagrams required when the skeleton expansion of the single-particle propagator is not assumed. A
hierarchy of importance among different diagrams is revealed, and a particular emphasis is given to a third-order
diagram (see Fig. 2c) which is expected to play a significant role among those featuring an interaction-irreducible
three-nucleon force.


A consistent formalism to resum at infinite order correlations induced by three-nucleon forces in the
self-consistent Green?s function theory is now available, and ready to be implemented in the many-body solvers.
Work is in progress to include the first interaction-irreducible three-nucleon diagram in calculations of closed-shell
medium-mass nuclei.

Leistenschneider E, Reiter M, Ayet San Andrés S, Kootte B, Holt J, Navrátil P, Babcock C, Barbieri Carlo, Barquest B, Bergmann J, Bollig J, Brunner T, Dunling E, Finlay A, Geissel H, Graham L, Greiner F, Hergert H, Hornung C, Jesch C, Klawitter R, Lan Y, Lascar D, Leach K, Lippert W, McKay J, Paul S, Schwenk A, Short D, Simonis J, Somà V, Steinbrügge R, Stroberg S, Thompson R, Wieser M, Will C, Yavor M, Andreoiu C, Dickel T, Dillmann I, Gwinner G, Plaß W, Scheidenberger C, Kwiatkowski A, Dilling J (2018) Dawning of the N=32 Shell Closure Seen through Precision Mass Measurements of Neutron-Rich Titanium Isotopes,Physical Review Letters 120 (6) 062503 American Physical Society
A precision mass investigation of the neutron-rich titanium isotopes
was performed at TRIUMF?s Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the
shell closure, and the overall uncertainties of the
mass values were significantly reduced. Our results conclusively establish the existence of the weak shell effect at
, narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art ab initio shell model calculations which, despite very successfully describing where the
shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements also represent the first scientific results of TITAN using the newly commissioned multiple-reflection time-of-flight mass spectrometer, substantiated by independent measurements from TITAN?s Penning trap mass spectrometer.
Atar L, Paschalis S, Barbieri Carlo, Bertulani C, Díaz Fernández P, Hollington M, Najafi M, Panin V, Alvarez-Pol H, Aumann T, Avdeichikov V, Beceiro-Novo S, Bemmerer D, Benlliure J, Boillos J, Boretzky K, Borge M, Caamaño M, Caesar C, Casarejos E, Catford Wilton, Cederkall J, Chartier M, Chulkov L, Cortina-Gil D, Cravo E, Crespo R, Dillmann I, Elekes Z, Enders J, Ershova O, Estrade A, Farinon F, Fraile L, Freer M, Galaviz Redondo D, Geissel H, Gernhäuser R, Golubev P, Göbel K, Hagdahl J, Heftrich T, Heil M, Heine M, Heinz A, Henriques A, Hufnagel A, Ignatov A, Johansson H, Jonson B, Kahlbow J, Kalantar-Nayestanaki N, Kanungo R, Kelic-Heil A, Knyazev A, Kröll T, Kurz N, Labiche M, Langer C, Le Bleis T, Lemmon R, Lindberg S, Machado J, Marganiec-GaB?zka J, Movsesyan A, Nacher E, Nikolskii E, Nilsson T, Nociforo C, Perea A, Petri M, Pietri S, Plag R, Reifarth R, Ribeiro G, Rigollet C, Rossi D, Röder M, Savran D, Scheit H, Simon H, Sorlin O, Syndikus I, Taylor J, Tengblad O, Thies R, Togano Y, Vandebrouck M, Velho P, Volkov V, Wagner A, Wamers F, Weick H, Wheldon C, Wilson G, Winfield J, Woods P, Yakorev D, Zhukov M, Zilges A, Zuber K (2018) Quasifree ( p , 2p ) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength,Physical Review Letters 120 (5) 052501 American Physical Society
Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic
study of the structure of stable and exotic oxygen isotopes at the R3B=LAND setup with incident beam
energies in the range of 300?450 MeV=u. The oxygen isotopic chain offers a large variation of separation
energies that allows for a quantitative understanding of single-particle strength with changing isospin
asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy onenucleon
removal reactions. Inclusive cross sections for quasifree knockout reactions of the type
AOðp; 2pÞA?1N have been determined and compared to calculations based on the eikonal reaction theory.
The reduction factors for the single-particle strength with respect to the independent-particle model were
obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant
dependence on proton-neutron asymmetry.
Rocco N, Barbieri Carlo (2018) Inclusive electron-nucleus cross section within the self-consistent Green's function approach,Physical Review C 98 025501 American Physical Society
We present results for charge form factors, the point-proton, charge, and single-nucleon momentum distributions of
obtained within the self-consistent Green's function approach. The removal of the center-of-mass contribution for both nuclei has been performed by using a metropolis Monte Carlo algorithm in which the center-of-mass coordinate can be exactly subtracted from the optimal reference state wave function generated during the self-consistent Green's function calculations. The spectral functions of the same two nuclei have been used to compute inclusive electron-nucleus cross sections. The formalism adopted is based on the factorization of the spectral function and the nuclear transition matrix elements. This allows us to provide an accurate description of nuclear dynamics and to account for relativistic effects in the interaction vertex. When final-state interactions for the struck particle are accounted for, we find nice agreement between the data and the theory for the inclusive electron-
cross section. The results lay the foundations for future applications of the self-consistent Green's function method, in both closed and open shell nuclei, to neutrino data analysis.
Rocco Noemi, Barbieri Carlo, Benhar Omar, De Pace Arturo, Lovato Alessandro (2019) Neutrino-nucleus cross section within the extended factorization scheme,Physical Review C 99 (2) 025502 pp. 1-18 American Physical Society
The factorization scheme, based on the impulse approximation and the spectral function formalism, has been recently generalized to allow the description of electromagnetic nuclear interactions driven by two-nucleon currents. We have extended this framework to the case of weakly charged and neutral currents, and carried out calculations of the double-differential neutrino-carbon and neutrino-oxygen cross sections using two different models of the target spectral functions. The results, showing a moderate dependence on the input spectral function, confirm that our approach provides a consistent treatment of all reaction mechanisms contributing to the signals detected by accelerator-based neutrino experiments.
Raimondi Francesco, Barbieri Carlo (2019) Nuclear electromagnetic dipole response with the self-consistent Green's function formalism,Physical Review C 99 (5) 054327 pp. 1-13 American Physical Society

Background: Microscopic calculations of the electromagnetic response of light and medium-mass nuclei are now feasible thanks to the availability of realistic nuclear interactions with accurate saturation and spectroscopic properties, and the development of large-scale computing methods for many-body physics.

Purpose: To compute isovector dipole electromagnetic (E1) response and related quantities, i.e., integrated dipole cross section and polarizability, and compare with data from photoabsorption and Coulomb excitation experiments. To investigate the evolution pattern of the E1 response towards the neutron drip line with calculations of neutron-rich nuclei within a given isotopic chain.

Methods: The single-particle propagator is obtained by solving the Dyson equation, where the self-energy includes correlations nonperturbatively through the algebraic diagrammatic construction (ADC) method. The particle-hole (ph) polarization propagator is treated in the dressed random phase approximation (DRPA), based on an effective correlated propagator that includes some 2p2h effects but keeps the same computation scaling as the standard Hartree-Fock propagator.

Results: The E1 responses for 14,16,22,24O, 36,40,48,52,54,70Ca, and 68Ni have been computed: The presence of a soft dipole mode of excitation for neutron-rich nuclei is found, and there is a fair reproduction of the low-energy part of the experimental excitation spectrum. This is reflected in a good agreement with the empirical dipole polarizability values. The impact of different approximations to the correlated propagator used as input in the E1 response calculation is assessed.

Conclusion: For a realistic interaction that accurately reproduces masses and radii, an effective propagator of the mean-field type computed by the self-consistent Green's function provides a good description of the empirical E1 response, especially in the low-energy part of the excitation spectrum and around the giant dipole resonance. The high-energy part of the spectrum improves and displays an enhancement of the strength when quasiparticle fragmentation is added to the reference propagator. However, this fragmentation (without a proper restoration of dynamical self-consistency) spoils the predictions of the energy centroid of the giant dipole resonance.

This dissertation presents an ab initio investigation of modern nuclear Hamiltonians predicted by chiral effective field theory (ChEFT) and lattice quantum chromodynamics (LQCD), in both infinite and finite matter using self-consistent Green's function (SCGF). The third order algebraic diagrammatic construction [ADC(3)] originally devised for quantum chemistry, was used to approximate the self-energy in both systems. This is the first application of ADC(3) to infinite matter. These calculations implemented both two- and three-nucleon ChEFT interactions to compute the equation of state of pure neutron matter and symmetric nuclear matter, whilst also obtaining the spectral function. The procedure was benchmarked using the NNLOsat interaction against a previous SCGF calculation based on the T-matrix approach. The benchmark showed good convergence with respect to the model space but it yielded an apparent lack in the binding energy of ~30% at the saturation density of symmetric nuclear matter when compared to the SCGF T-matrix results and the available literature. After the benchmark a preliminary investigation in to modern N²{tLO nucleon-nucleon interactions extended to include the N²LO three-nucleon interaction was conducted. These results were reviewed with in the current perceived limitations of the SCGF formalism developed here. In this study, increasing the regulator cut off or the order of the chiral expansion for the nucleon-nucleon interaction decreased the observed binding energy whilst also lowering the saturation density. The calculation of finite nuclei used a potential derived from LQCD by the HAL QCD collaboration at an unphysical pion mass, MPS=469 MeV/c². The short-range repulsion of this interaction requires one to include a resummation of ladder diagrams from the excluded model space. The effectiveness of the ladder resummation from outside the computational model space is considered by the infrared convergence of the total binding energies. The introduction of these missing ladder diagrams leads to a complete diagonalisation of short-range degrees of freedom independently of the choice of model space. The binding energy of Helium-4 was calculated to be -4.80 MeV. The heavier doubly magic nuclei, Oxygen-16 and Calcium-40, had binding energies of -17.9 MeV and -74.4 MeV respectively. This means whilst Calcium-40 is observed to be bound with respect to Alpha break up, Oxygen-16 is expected to be unstable.