Nuclear Theory·nucl-th

Wednesday·November 29, 2017

17 papers—11 primary·6 cross-listed

12
[Submitted on 27 Nov 2017] (cross-list from hep-ph)
Vector boson tagged jets and jet substructure
Ivan Vitev🇺🇸
In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. $Z^{0}$ -tagging and $γ$ -tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at $s_{N N} = 5.02$ TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.
Comments:
Proceedings of the XLVII International Symposium on Multiparticle Dynamics; 9 pages, 9 eps figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1711.09905 [pdf]
EPJ Web Conf.(2018)·1 citation
13
[Submitted on 27 Nov 2017] (cross-list from hep-ph)
Comment on `Nucleon Structure Functions from Operator Product Expansion on the Lattice'
Keh-Fei Liu🇺🇸
It is suggested in the paper by A.J. Chambers {\it et al.} (Phys. Rev. Lett. 118, 242001 (2017), arXiv:1703.01153) that the time-ordered current-curent correlator in the nucleon calculated on the lattice is to be identified as the forward Compton amplitude so that it is related to the sum of the even moments of the structure function as in the Minkowski space in the continuum. We point out two problems with this identification. First of all, the current-current correlator defined in the Euclidean space is not analytic everywhere on the rest of the complex $ν$ or $ω$ plane, besides the cuts on the real axis. As such, there is no dispersion relation to relate it to its imaginary part and hence the moments of the structure function. On the lattice, there is an additional difficulty in that the higher dimensional local operators from the operator production expansion (OPE) of the current-current product can mix with lower dimensional higher-twist operators which leads to divergences in the powers of inverse lattice spacing. This mixing needs to be removed before their matrix elements can be identified as the moments of the structure function.
Comments:
This article has been withdrawn by the author. The comment on the analyticity of the Euclidean current-current correlator is not relevant and actually validates the approach of the cited work in the stated kinematic region
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1711.09956 [pdf]
0 citations
14
[Submitted on 28 Nov 2017] (cross-list from hep-ph)
3D structure of hadrons by generalized distribution amplitudes and gravitational form factors
S. Kumano🇯🇵 · Qin-Tao Song🇯🇵 · O. V. Teryaev🇷🇺
Generalized distribution amplitudes (GDAs) are one type of three-dimensional structure functions, and they are related to the generalized distribution functions (GPDs) by the $s$ - $t$ crossing of the Mandelstam variables. The GDA studies provide information on three-dimensional tomography of hadrons. The GDAs can be investigated by the two-photon process $γ^{*} γ \to h h ˉ$ , and the GPDs are studied by the deeply virtual Compton scattering $γ^{*} h \to γ h$ . The GDA studies had been pure theoretical topics, although the GPDs have been experimentally investigated, because there was no available experimental measurement. Recently, the Belle collaboration reported their measurements on the $γ^{*} γ \to π^{0} π^{0}$ differential cross section, so that it became possible to find the GDAs from their measurements. Here, we report our analysis of the Belle data for determining the pion GDAs. From the GDAs, the timelike gravitational form factors $Θ_{1} (s)$ and $Θ_{2} (s)$ can be calculated, which are mechanical (pressure, shear force) and mass (energy) form factors, respectively. They are converted to the spacelike form factors by using the dispersion relation, and then gravitational radii are evaluated for the pion. The mass and mechanical radii are obtained from $Θ_{2}$ and $Θ_{1}$ as $⟨ r^{2} ⟩_{mass} = 0.56 \sim 0.69$ fm and $⟨ r^{2} ⟩_{mech} = 1.45 \sim 1.56$ fm, whereas the experimental charge radius is $⟨ r^{2} ⟩_{charge} = 0.672 \pm 0.008$ fm for the charged pion. Future developments are expected in this new field to explore gravitational physics in the quark and gluon level.
Comments:
6 pages, LaTeX, 1 style file, 8 figure files, Proceedings of the XXV International Workshop on Deep-Inelastic Scattering and Related Subjects, April 3-7, 2017, University of Birmingham, UK
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1711.10086 [pdf]
PoS(2018)·0 citations
15
[Submitted on 2 Nov 2017] (cross-list from physics.atom-ph)
$Ab initio$ calculation of the calorimetric electron capture spectrum of $^{163}$ Holmium: Intra-atomic decay into bound-states
M. Braß · C. Enss · L. Gastaldo · M.W. Haverkort
The determination of the electron neutrino mass by electron capture in $^{163}$ Ho relies on a precise understanding of the deexcitation of a core hole after an electron capture event. We here present an \textit{ab intio} calculation of the electron capture spectrum in $^{163}$ Ho, including all intra-atomic decay channels into bound-states. We use theoretical methods developed for the calculation of core level spectroscopy on correlated electron compounds. Our comparison critically tests the reality of these theories. We find that relativistic interactions beyond the Dirac equation, i.e. quantum-electro dynamics, only lead to minor shifts of the spectral peaks. The electronic relaxation after an electron capture event due to the changed nuclear potential leads to a mixing of different edges, but due to conservation of angular momentum of each scattered electron, no additional structures emerge. Many-body Coulomb interactions lead to the formation of multiplets and to additional peaks with multiple core-holes due to Auger decay. Multiplets crucially change the appearance of the resonances on a Rydberg energy scale. The additional structures due to Auger decay are, although clearly visible, relatively weak compared to the one core hole states and accidentally far away from the end-point region of the spectrum. As the end-point of the spectrum is effected most by the neutrino mass these additional states do not influence the statistics for determining the neutrino mass directly. The multiplet broadening and Auger shake-up of the main core-level edges do change the apparent line-width and accompanying lifetime of these edges, thereby invalidating experimentally obtained lifetimes at the resonance for regions far away from the resonance.
Subjects:
Atomic Physics (physics.atom-ph); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
1711.10309 [pdf]
PRC(2018)·29 citations
16
[Submitted on 28 Nov 2017] (cross-list from hep-ph)
Hyperasymptotics and quark-hadron duality violations in QCD
Diogo Boito🇧🇷 · Irinel Caprini🇷🇴 · Maarten Golterman🇪🇸 · Kim Maltman🇦🇺 · Santiago Peris🇪🇸
We investigate the origin of the quark-hadron duality-violating terms in the expansion of the QCD two-point vector correlation function at large energies in the complex $q^{2}$ plane. Starting from the dispersive representation for the associated polarization, the analytic continuation of the operator product expansion from the Euclidean to the Minkowski region is performed by means of a generalized Borel-Laplace transform, borrowing techniques from hyperasymptotics. We establish a connection between singularities in the Borel plane and quark-hadron duality violating contributions. Starting with the assumption that for QCD at $N_{c} = \infty$ the spectrum approaches a Regge trajectory at large energy, we obtain an expression for quark-hadron duality violations at large, but finite $N_{c}$ .
Comments:
38 pages, 19 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1711.10316 [pdf]
PRD(2018)·57 citations
17
[Submitted on 28 Nov 2017] (cross-list from gr-qc)
Canonical transformation path to gauge theories of gravity II --- Spacetime coupling of spin-0 and spin-1 particle fields
J. Struckmeier🇩🇪 · J. Muench🇩🇪 · P. Liebrich🇩🇪 · M. Hanauske🇩🇪 · J. Kirsch🇩🇪 · D. Vasak🇩🇪 · L. Satarov🇩🇪 · H. Stoecker🇩🇪
The generic form of spacetime dynamics as a classical gauge field theory has recently been derived, based on only the action principle and on the Principle of General Relativity. It was thus shown that Einstein's General Relativity is the special case where (i) the Hilbert Lagrangian (essentially the Ricci scalar) is supposed to describe the dynamics of the "free" (uncoupled) gravitational field, and (ii) the energy-momentum tensor is that of scalar fields representing real or complex structureless (spin- $0$ ) particles. It followed that all other source fields---such as vector fields representing massive and non-massive spin- $1$ particles---need careful scrutiny of the appropriate source tensor. This is the subject of our actual paper: we discuss in detail the coupling of the gravitational field with (i) a massive complex scalar field, (ii) a massive real vector field, and (iii) a massless vector field. We show that different couplings emerge for massive and non-massive vector fields. The \emph{massive} vector field has the \emph{canonical} energy-momentum tensor as the appropriate source term---which embraces also the energy density furnished by the internal spin. In this case, the vector fields are shown to generate a torsion of spacetime. In contrast, the system of a \emph{massless} and charged vector field is associated with the \emph{metric} (Hilbert) energy-momentum tensor due to its additional $U (1)$ symmetry. Moreover, such vector fields do not generate a torsion of spacetime. The respective sources of gravitation apply for all models of the dynamics of the `free' (uncoupled) gravitational field---which do not follow from the gauge formalism but must be specified based on separate physical reasoning.
Comments:
26 pages
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1711.10333 [pdf]
IJMPE(2019)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

Vector boson tagged jets and jet substructure

Comment on `Nucleon Structure Functions from Operator Product Expansion on the Lattice'

3D structure of hadrons by generalized distribution amplitudes and gravitational form factors

Ab initio calculation of the calorimetric electron capture spectrum of 163Holmium: Intra-atomic decay into bound-states

Hyperasymptotics and quark-hadron duality violations in QCD

Canonical transformation path to gauge theories of gravity II --- Spacetime coupling of spin-0 and spin-1 particle fields

Affiliations

$Ab initio$ calculation of the calorimetric electron capture spectrum of $^{163}$ Holmium: Intra-atomic decay into bound-states