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Nuclear Theory·nucl-th

Tuesday·February 3, 2015

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    [Submitted on 31 Jan 2015]

    Tunneling of atoms, nuclei and molecules

    C.A. Bertulani

    This is a brief review of few relevant topics on tunneling of composite particles and how the coupling to intrinsic and external degrees of freedom affects tunneling probabilities. I discuss the phenomena of resonant tunneling, different barriers seen by subsystems, damping of resonant tunneling by level bunching and continuum effects due to particle dissociation.

    Comments:
    8 pages, 8 figures, Contribution to the Proceedings of the International Workshop on Critical Stability, Santos, SP, Brazil, October 12-17, 2014. Ed. by Tobias Frederico
    Subjects:
    Nuclear Theory (nucl-th); Superconductivity (cond-mat.supr-con); Nuclear Experiment (nucl-ex); Quantum Physics (quant-ph)
    arXiv:
    1502.00074 [pdf]
    Few Body Syst.(2015)·6 citations
  2. 02

    [Submitted on 1 Feb 2015]

    Low-energy proton capture reactions in the mass region 55-60

    Saumi Dutta🇮🇳 · Dipti Chakraborty🇮🇳 · G. Gangopadhyay🇮🇳 · Abhijit Bhattacharyya🇮🇳

    Low energy proton capture reactions in the mass 55-60 region are studied in a microscopic optical model. Nuclear density profile is calculated using the relativistic mean field theory. The DDM3Y interaction is folded with the theoretical density to obtain the proton-nucleus optical potential. A definite set of normalization parameters has been obtained for the concerned mass region by comparing with all available experimental data in this mass region. These parameters have been used to obtain proton capture rates for astrophysically important reactions in this mass region.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.00222 [pdf]
    PRC(2015)·11 citations
  3. 03

    [Submitted on 2 Feb 2015]

    Quantifying properties of hot and dense QCD matter through systematic model-to-data comparison

    Jonah E. Bernhard🇺🇸 · Peter W. Marcy🇺🇸 · Christopher E. Coleman-Smith🇺🇸 · Snehalata Huzurbazar🇺🇸 · Robert L. Wolpert🇺🇸 · Steffen A. Bass🇺🇸

    We systematically compare an event-by-event heavy-ion collision model to data from the Large Hadron Collider. Using a general Bayesian method, we probe multiple model parameters including fundamental quark-gluon plasma properties such as the specific shear viscosity , calibrate the model to optimally reproduce experimental data, and extract quantitative constraints for all parameters simultaneously. The method is universal and easily extensible to other data and collision models.

    Comments:
    15 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.00339 [pdf]
    PRC(2015)·112 citations
  4. 04

    [Submitted on 2 Feb 2015]

    Toward Universality in Similarity Renormalization Group Evolved Few-body Potential Matrix Elements

    Brian Dainton🇺🇸

    We first examine how T-matrix equivalence drives the flow of similarity renormalization group (SRG) evolved potential matrix elements to a universal form, with the ultimate goal of gaining insight into universality for three-nucleon forces. In agreement with observations made previously for Lee-Suzuki transformations, regions of universal potential matrix elements are restricted to where half-on-shell T-matrix equivalence holds, but the potentials must also reproduce binding energies. We find universality in local energy regions, reflecting a local decoupling by the SRG. To continue the study in the 3-body sector, we create a simple 1-D spinless boson "theoretical laboratory" for a dramatic improvement in computational efficiency. We introduce a basis-transformation, harmonic oscillator (HO) basis, which is used for current many-body calculations and discuss the imposed truncations. When SRG evolving in a HO-basis, we show that the evolved matrix elements, once transformed back into momentum-representation, differ from those when evolving with momentum representation. This is because the generator in each basis is not exactly the same due to the truncation, which creates evolution artifacts in the 3-body potential matrix elements. In the 2- body sector, this can be avoided by increasing the basis size, but it remains unclear whether this is possible in the 3-body sector, as truncation errors in the 3-body sector are more difficult to avoid, and the computational power required is greatly increased for three-body evolution.

    Comments:
    PhD thesis, Ohio State, 2015
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.00578 [pdf]
    0 citations
  5. 05

    [Submitted on 2 Feb 2015]

    Collision Geometry and Flow in Uranium+Uranium Collisions

    Andy Goldschmidt🇺🇸 · Zhi Qiu🇺🇸 · Chun Shen🇺🇸 · Ulrich Heinz🇺🇸

    Using event-by-event viscous fluid dynamics to evolve fluctuating initial density profiles from the Monte-Carlo Glauber model for U+U collisions, we report a "knee"-like structure in the elliptic flow as a function of collision centrality, located near 0.5% centrality as measured by the final charged multiplicity. This knee is due to the preferential selection of tip-on-tip collision geometries by a high-multiplicity trigger. Such a knee structure is not seen in the STAR data. This rules out the two-component MC-Glauber model for initial energy and entropy production. An enrichment of tip-tip configurations by triggering solely on high-multiplicity in the U+U collisions thus does not work. On the other hand, using the Zero Degree Calorimeters (ZDCs) coupled with event-shape engineering, we identify the selection purity of body-body and tip-tip events in the full-overlap U+U collisions. With additional constraints on the asymmetry of the ZDC signals one can further increases the probability of selecting tip-tip events in U+U collisions.

    Comments:
    9 pages, 4 figures, Proceedings of WPCF 2014 in Gyöngyös, Hungary, Aug.25-29, 2014
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.00603 [pdf]
    13 citations

Affiliations

first authorsco-authorsvia INSPIRE