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2019-02-28 | TRIUMF ab initio workshop | 1
Continuum extension of the NCSM: HORSE and ACCC
Stefan Alexa, Thomas Hüther, Robert Roth
TRIUMF Workshop 2019
2019-02-28 | TRIUMF ab initio workshop | 2
Describe possible resonance of the four neutron system from ab initio bound state calculations
Use existing Jacobi-NCSM framework with favourable model space scaling behaviour
Single state HORSE calculations of 4n with large model spaces and different chiral interactions
Combine Jacobi-NCSM with analyticcontinuation in the coupling constant
Motivation
Kukulin et al. Theory of Resonances, Springer (1989)
Kisamori et al. PRL 116, 052501 (2016)
Shirokov et al. PRL 117, 182502 (2016)
2019-02-28 | TRIUMF ab initio workshop | 3
HORSE
Harmonic Oscillator Representation of Scattering Equation
Single-state version
Large model spaces
Interactions consistent
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● N3LOEM bare
■ JISP16
◆ DAEJEON16
▲ Various chiral 2N and
2N+3N interactions
0 5 10 15
10
30
50
70
90
110
Energy [MeV]
δN
,l[d
eg]
Nmax =26
2019-02-28 | TRIUMF ab initio workshop | 4
ACCC – Introduction
Obtain resonance from unbound system by artificially binding system, e.g.
Generate set of binding energies
Padé fit of wavenumber for analytic continuation
Resonance energy and width
2019-02-28 | TRIUMF ab initio workshop | 5
ACCC – 4n
Modification:
Di-neutron not accounted for
Padé extrapolation unstable
Effect of modification?
2019-02-28 | TRIUMF ab initio workshop | 6
ACCC – 4n
Modification:
Di-neutron unbound
Padé orders “better behaved”
Far extrapolation due to large λ0
Modification too strong?
2019-02-28 | TRIUMF ab initio workshop | 7
ACCC – 4n – Statistical ACCC
Modification:
Statistical approach
Papp et al. Chem.Phys 418 (2013)
Number of data points impact fit
Modification generates unphysical state?
External potential necessary?
2019-02-28 | TRIUMF ab initio workshop | 8
See you at the poster
2019-02-28 | TRIUMF ab initio workshop | 9
Thank you for your attention!
Thanks to my group and collaboratorsM. Deuker, T. Hüther, P. Käse, M. Knöll, L. Mertes, T. Mongelli, J. Müller, R. Roth, K. Vobig, C. Walde, T. Wolfgruber
Institut für Kernphysik, TU Darmstadt
Special thanks
R. Wirth
Michigan State University
