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Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization

More, Sushant N
http://orcid.org/0000-0002-3746-2431
http://rave.ohiolink.edu/etdc/view?acc_num=osu1468246999

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Physics.
New insights into the inter-nucleon interactions, developments in many-body technology, and the surge in computational capabilities has led to phenomenal progress in low-energy nuclear physics in the past few years. Nonetheless, many calculations still lack a robust uncertainty quantification which is essential for making reliable predictions. In this work we investigate two distinct sources of uncertainty and develop ways to account for them. Harmonic oscillator basis expansions are widely used in ab-initio nuclear structure calculations. Finite computational resources usually require that the basis be truncated before observables are fully converged, necessitating reliable extrapolation schemes. It has been demonstrated recently that errors introduced from basis truncation can be taken into account by focusing on the infrared and ultraviolet cutoffs induced by a truncated basis. We show that a finite oscillator basis effectively imposes a hard-wall boundary condition in coordinate space. We accurately determine the position of the hard-wall as a function of oscillator space parameters, derive infrared extrapolation formulas for the energy and other observables, and discuss the extension of this approach to higher angular momentum and to other localized bases. We exploit the duality of the harmonic oscillator to account for the errors introduced by a finite ultraviolet cutoff. Nucleon knockout reactions have been widely used to study and understand nuclear properties. Such an analysis implicitly assumes that the effects of the probe can be separated from the physics of the target nucleus. This factorization between nuclear structure and reaction components depends on the renormalization scale and scheme, and has not been well understood. But it is potentially critical for interpreting experiments and for extracting process-independent nuclear properties. We use a class of unitary transformations called the similarity renormalization group (SRG) transformations to systematically study the scale dependence of factorization for the simplest knockout process of deuteron electrodisintegration. We find that the extent of scale dependence depends strongly on kinematics, but in a systematic way. We find a relatively weak scale dependence at the quasi-free kinematics that gets progressively stronger as one moves away from the quasi-free region. Based on examination of the relevant overlap matrix elements, we are able to qualitatively explain and even predict the nature of scale dependence based on the kinematics under consideration.
Richard Furnstahl (Advisor)
Robert Perry (Committee Member)
Michael Lisa (Committee Member)
John Beacom (Committee Member)
225 p.
Physics
low-energy nuclear theory, extrapolation schemes, factorization

Recommended Citations

Citations

  • More, S. N. (2016). Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468246999

    APA Style (7th edition)

  • More, Sushant. Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1468246999.

    MLA Style (8th edition)

  • More, Sushant. "Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468246999

    Chicago Manual of Style (17th edition)

osu1468246999
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This open access ETD is published by The Ohio State University and OhioLINK.