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Nuclear Theory·nucl-th

Wednesday·April 10, 2019

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 06

    Transverse momentum dependent distributions in and semi-inclusive deep-inelastic scattering using jets

    Daniel Gutierrez-Reyes🇪🇸 · Ignazio Scimemi🇪🇸 · Wouter J. Waalewijn🇳🇱 · Lorenzo Zoppi🇳🇱

    The extraction of transverse momentum dependent distributions (TMDs) in semi-inclusive deep inelastic scattering (SIDIS) is complicated by the presence of both initial- and final-state nonperturbative physics. We recently proposed measuring jets (instead of hadrons) as a solution, showing that for the Winner-Take-All jet axis the same factorization formulae valid for hadrons applied to jets of arbitrary size. This amounts to simply replacing TMD fragmentation functions by our TMD jet functions. In this paper we present the calculation of these jet functions at one loop. We obtain phenomenological results for dijet (Belle II, LEP) and SIDIS (HERA, EIC) with a jet, building on the arTeMiDe code. Surprisingly, we find that the limit of large jet radius describes the full results extremely well, and we extract the two-loop jet function in this limit using Event2, allowing us to achieve NLL accuracy. We demonstrate the perturbative convergence of our predictions and explore the kinematic dependence of the cross section. Finally, we investigate the sensitivity to nonperturbative physics, demonstrating that jets are a promising probe of proton structure.

    ↳ hep-phnucl-thJHEP(2019)·83 citations
  2. 07

    Simulations of the Glasma in 3+1D

    David Müller🇦🇹

    The Glasma is a gluonic state of matter which can be created in collisions of relativistic heavy ions and is a precursor to the quark-gluon plasma. The existence of this state is a prediction of the color glass condensate (CGC) effective theory. In many applications of the CGC framework, the boost invariant approximation is employed. It assumes that the longitudinal extent of the nuclei can be approximated as infinitesimally thin. Consequently, the Glasma produced from such a collision is boost invariant and can be effectively described in 2+1D. Therefore, observables of the boost invariant Glasma are by construction independent of rapidity. The main goal of this thesis is to develop a numerical method for the non-boost-invariant setting where nuclei are assumed to be thin, but of finite longitudinal extent. This is in conflict with a number of simplifications that are used in the boost invariant case. In particular, one has to describe the collisions in 3+1D in the laboratory or center-of-mass frame. The change of frame forces the explicit inclusion of the color charges of nuclei. The new method is tested using an extension of the McLerran-Venugopalan model which includes a parameter for longitudinal thickness. It reproduces the boost invariant setting as a limiting case. Studying the pressure components of the Glasma, one finds the pressure anisotropy remains large. The energy density of the Glasma depends on rapidity due to the explicit breaking of boost invariance. The width of the observed rapidity profiles is controlled by the collision energy and can be shown to roughly agree with experimental data. Finally, a new numerical scheme for real-time lattice gauge theory is developed which provides higher numerical stability than the previous method. This new scheme is shown to be gauge-covariant and conserves the Gauss constraint even for large time steps.

    ↳ hep-phhep-latnucl-th13 citations
  3. 08

    Toward convergence of effective field theory simulations on digital quantum computers

    Omar Shehab🇺🇸 · Kevin A. Landsman🇺🇸 · Yunseong Nam🇺🇸 · Daiwei Zhu🇺🇸 · Norbert M. Linke🇺🇸 · Matthew J. Keesan🇺🇸 · Raphael C. Pooser🇺🇸 · Christopher R. Monroe🇺🇸

    We report results for simulating an effective field theory to compute the binding energy of the deuteron nucleus using a hybrid algorithm on a trapped-ion quantum computer. Two increasingly complex unitary coupled-cluster ansaetze have been used to compute the binding energy to within a few percent for successively more complex Hamiltonians. By increasing the complexity of the Hamiltonian, allowing more terms in the effective field theory expansion and calculating their expectation values, we present a benchmark for quantum computers based on their ability to scalably calculate the effective field theory with increasing accuracy. Our result of MeV may be compared with the exact Deuteron ground-state energy MeV. We also demonstrate an error mitigation technique using Richardson extrapolation on ion traps for the first time. The error mitigation circuit represents a record for deepest quantum circuit on a trapped-ion quantum computer.

    ↳ quant-phcs.ETnucl-thPRA(2019)·46 citations
  4. 09

    Neutron star properties: Constraining the nuclear matter EoS

    Constança Providência

    We examine the influence of the density dependence of the symmetry energy on several properties of neutron stars. In particular, we study the constraints set on the nuclear matter equation of state by the values of the tidal deformability and neutron star radius, using a diverse set of relativistic and non-relativistic mean field models consistent with bulk properties of finite nuclei and the observed lower bound on the maximum mass of neutron star. The tidal deformability and radius show a strong correlation with specific linear combinations of the isoscalar and isovector nuclear matter parameters associated with the EoS. Such correlations suggest that a precise value of the radius or the tidal deformability can put tight bounds on several EoS parameters, in particular, on the slope of the incompressibility and the curvature of the symmetry energy. We show that the density dependence of the symmetry energy has a direct influence on the amount of strangeness inside cold dense matter and, consequently, on the direct Urca process and cooling of neutron stars. We explain the low luminosity of SAX 1808.4-3658 as a result of hyperonic direct Urca processes. Finally, we discuss the strong influence of the density dependence of the symmetry energy on the extension of the crust-core transition region of a magnetized neutron star. The increase of the crust and its of complexity, due to the magnetic field effect, may have a role on the glitch mechanism or on the magnetic field decay.

    ↳ astro-ph.HEnucl-thAIP Conf.Proc.(2019)·4 citations
  5. 10

    Studying newborn neutron stars by the transient emission after stellar collapses and compact binary mergers

    Yun-Wei Yu · Aming Chen · Zi-Gao Dai · Shao-Ze Li · Liang-Duan Liu · Jin-Ping Zhu

    The formation of neutron stars (NSs), both from collapses of massive stars and mergers of compact objects, can be usually indicated by bright transients emitted from explosively-ejected material. In particular, if the newborn NSs can rotate at a millisecond period and have a sufficiently high magnetic field, then the spin-down of the NSs would provide a remarkable amount of energy to the emitting material. As a result, super-luminous supernovae could be produced in the massive stellar collapse cases, while some unusual fast evolving and luminous optical transients could arise from the cases of NS mergers and accretion-induced collapses of white dwarfs. In all cases, if the dipolar magnetic fields of the newborn NSs can be amplified to be as high as G, a relativistic jet could be launched and then a gamma-ray burst can be produced as the jet successfully breaks out from the surrounding nearly-isotropic ejected material.

    ↳ astro-ph.HEnucl-exnucl-thAIP Conf.Proc.(2019)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE