Nuclear Theory·nucl-th

Wednesday·December 19, 2018

12 papers—4 primary·8 cross-listed

05
[Submitted on 18 Dec 2018] (cross-list from hep-ph)
Unravelling High-Energy Hadron Structures with Lattice QCD
Yong Zhao🇺🇸
Parton distribution functions are key quantities for us to understand the hadronic structures in high-energy scattering, but they are difficult to calculate from lattice QCD. Recent years have seen fast development of the large-momentum effective theory which allows extraction of the $x$ -dependence of parton distribution functions from a quasi-parton distribution function that can be directly calculated on lattice. The extraction is based on a factorization formula for the quasi-parton distribution function that has been derived rigorously in perturbation theory. A systematic procedure that includes renormalization, perturbative matching, and power corrections has been established to calculate parton distribution functions. Latest progress from lattice QCD has shown promising signs that it will become an effective tool for calculating parton physics.
Comments:
28 pages, 5 figures. Corrected minor mistakes in Eqs.(27-28, 31-33, 35-36)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1812.07192 [pdf]
Int.J.Mod.Phys.A(2019)·33 citations
06
[Submitted on 18 Dec 2018] (cross-list from hep-ph)
Jet quenching parameter in an expanding QCD plasma
Edmond Iancu🇫🇷 · Pieter Taels🇫🇷 · Bin Wu🇨🇭
We present a new definition of the jet quenching parameter $q^$ in a weakly-coupled quark-gluon plasma undergoing boost-invariant longitudinal expansion. We propose a boost-invariant definition of $q^$ , which is proportional to the broadening of the angular variables $η$ (the pseudo-rapidity) and $ϕ$ (the azimuthal angle). We furthermore consider radiative corrections to $q^$ and find potentially large corrections enhanced by a double logarithm like the case of a static medium. But unlike for the static medium, these corrections are now local in (proper) time.
Comments:
5 pages, 1 figure, Proceedings of Hard Probes 2018
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.07382 [pdf]
PoS(2018)·0 citations
07
[Submitted on 18 Dec 2018] (cross-list from hep-lat)
Hyperons in thermal QCD: A lattice view
Gert Aarts🇬🇧 · Chris Allton🇬🇧 · Davide De Boni🇬🇧 · Benjamin Jäger🇩🇰
The hadron resonance gas (HRG) is a widely used description of matter under extreme conditions, e.g. in the context of heavy-ion phenomenology. Commonly used implementations of the HRG employ vacuum hadron masses throughout the hadronic phase and hence do not include possible in-medium effects. Here we investigate this issue, using nonperturbative lattice simulations employing the FASTSUM anisotropic Nf=2+1 ensembles. We study the fate of octet and decuplet baryons as the temperature increases, focussing in particular on the positive- and negative-parity groundstates. While the positive-parity groundstate masses are indeed seen to be temperature independent, within the error, a strong temperature dependence is observed in the negative-parity channels. We give a simple parametrisation of this and formulate an in-medium HRG, which is particularly effective for hyperons. Parity doubling is seen to emerge in the deconfined phase at the level of correlators, with a noticeable effect of the heavier s quark. Channel dependence of this transition is analysed.
Comments:
9 pages, 6 eps figures, minor changes, to appear in PRD
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.07393 [pdf]
PRD(2019)·84 citations
08
[Submitted on 18 Dec 2018] (cross-list from hep-ph)
The Angular Power Spectrum of Heavy Ion Collisions
Meera Machado🇩🇰 · Poul Henrik Damgaard🇩🇰 · Jens Jørgen Gaardhøje🇩🇰 · Christian Bourjau🇩🇰
Particles produced in heavy ion collisions carry information about anisotropies present already in the early state of the system and play a crucial role in understanding the Quark Gluon Plasma and its evolution. We explore the angular power spectrum of particle multiplicities in such heavy ion collisions to extract fluctuations in particle multiplicities on the surface a sphere. Results are presented for Pb-Pb data at $s_{N N} = 2.76 TeV$ , extracted from the ALICE open data portal. We find that odd modes of the power spectrum display a power-law behavior with corresponding index $β$ , which is found to be close to unity. We also demonstrate that the angular power spectrum allows us to extract accurately the flow coefficients of non-central collisions.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.07449 [pdf]
PRC(2019)·5 citations
09
[Submitted on 18 Dec 2018] (cross-list from cond-mat.quant-gas)
Anyon optics with time-of-flight two-particle interference of double-well-trapped interacting ultracold atoms
Constantine Yannouleas · Uzi Landman
The subject of bianyon interference with ultracold atoms is introduced through theoretical investigations pertaining to the second-order momentum correlation maps of two anyons (built upon spinless and spin-1/2 bosonic, as well as spin-1/2 fermionic ultracold atoms) trapped in a double-well optical trap. The two-particle system is modeled according to the recently proposed protocols for emulating an anyonic Hubbard Hamiltonian in ultracold-atom one-dimensional lattices. Because the second-order momentum correlations are mirrored in the time-of-flight second-order interference patterns in space, our findings provide impetus for time-of-flight experimental protocols for detecting anyonic statistics via interferometry measurements of massive particles that broaden the scope of the biphoton interferometry of quantum optics.
Comments:
Published version. Typos corrected. 10 pages with 3 color figures. For related papers, see http://www.prism.gatech.edu/~ph274cy/
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1812.07475 [pdf]
PRA(2019)·7 citations
10
[Submitted on 18 Dec 2018] (cross-list from nucl-ex)
$β^{-}$ decay study of the $^{66}$ Mn - $^{66}$ Fe - $^{66}$ Co - $^{66}$ Ni chain
M. Stryjczyk🇧🇪 · Y. Tsunoda🇯🇵 · I. G. Darby🇧🇪 · H. De Witte🇧🇪 · J. Diriken🇧🇪 · D. V. Fedorov🇷🇺 · V. N. Fedosseev🇨🇭 · L. M. Fraile🇪🇸 · M. Huyse🇧🇪 · U. Köster🇫🇷 · B. A. Marsh🇨🇭 · T. Otsuka🇯🇵 and 10 other authors
Background: Shell evolution can impact the structure of the nuclei and lead to effects such as shape coexistence. The nuclei around $^{68}$ Ni represent an excellent study case, however, spectroscopic information of the neutron-rich, $Z < 28$ nuclei is limited. Purpose: The goal is to measure $γ$ -ray transitions in $^{66}$ Fe, $^{66}$ Co and $^{66}$ Ni populated in the $β^{-}$ decay of $^{66}$ Mn, to determine absolute $β$ -feedings and relative $γ$ -decay probabilities and to compare the results with Monte Carlo Shell Model calculations in order to study the influence of the relevant single neutron and proton orbitals occupancies around $Z = 28$ and $N = 40$ . Method: The low-energy structures of $^{65, 66}$ Fe, $^{66}$ Co and $^{66}$ Ni were studied in the $β^{-}$ decay of $^{66}$ Mn produced at ISOLDE, CERN. The beam was purified by means of laser resonance ionization and mass separation. The $β$ and $γ$ events detected by three plastic scintillators and two MiniBall cluster germanium detectors, respectively, were correlated in time to build the low-energy excitation schemes and to determine the $β$ -decay half-lives of the nuclei. Results: The relative small $β$ -decay ground state feeding of $^{66}$ Fe obtained in this work is at variant to the earlier studies. Spin and parity $1^{+}$ was assigned to the $^{66}$ Co ground state based on the strong ground state feeding in the decay of $^{66}$ Fe as well as in the decay of $^{66}$ Co. Experimental log(ft) values, $γ$ -ray deexcitation patterns and energies of excited states were compared to Monte Carlo Shell Model calculations. Based on this comparison, spin and parity assignments for the selected number of low-lying states in the $^{66}$ Mn to $^{66}$ Ni chain were proposed. Conclusions: The $β$ -decay chain starting $^{66}$ Mn towards $^{66}$ Ni, crossing $N = 40$ , evolves from deformed nuclei to sphericity...
Comments:
accepted for publication in PRC
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.07510 [pdf]
PRC(2018)·19 citations
11
[Submitted on 18 Dec 2018] (cross-list from hep-ph)
Jet substructure in high-energy hadron collisions
Felix Ringer🇺🇸
In the past years significant progress has been made toward achieving a quantitative understanding of jets and their substructure in high-energy proton-proton collisions from first principles in QCD. Precise measurements have become available from the experimental collaborations at the LHC and RHIC allowing a direct comparison of theoretical calculations and data. These developments make it possible to use jet substructure observables as precision probes in heavy-ion collisions. The radiation pattern inside jets contains valuable information about the hot and dense QCD medium which can be investigated using jet substructure techniques. By studying the soft sensitivity of the different observables it is possible to obtain important insights into the interaction of hard probes with the quark gluon plasma.
Comments:
8 pages, 1 figure, for the International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, 30 September - 5 October 2018 in Aix-Les-Bains, Savoie, France
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.07547 [pdf]
PoS(2018)·0 citations
12
[Submitted on 18 Dec 2018] (cross-list from hep-ph)
A transverse momentum dependent framework for back-to-back photon+jet production
Maarten G.A. Buffing🇺🇸 · Zhong-Bo Kang🇺🇸 · Kyle Lee🇺🇸 · Xiaohui Liu🇨🇳
We propose the $pp \to jet + γ$ as a new process for studying the Transverse Momentum Dependent Parton Distribution Functions (TMDs). To do so, we developed a novel framework for the jet- $γ$ imbalance in $pp \to jet + γ$ using Soft Collinear Effective Theory. The new framework opens up many new insights to the TMDs which the current TMD studies confined to the Drell-Yan and semi-inclusive deep inelastic scattering processes cannot achieve. The established formalism provides, for the first time, a first principle prediction of the jet- $γ$ imbalance in $pp$ collisions and therefore a first direct probe of the factorization breaking effects when compared with the future experimental data. If the factorization breaking effects are found small, the process will offer the unique sensitivities to both the polarized and un-polarized quark/gluon TMDs. We demonstrate the predictive power of the framework by calculating each component in the formalism to the next-to-leading order accuracy and by realizing the next-to-leading-logarithmic evolution. We provide the first numerical estimates for this process, for both the unpolarized cross section and the Sivers asymmetry.
Comments:
5 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.07549 [pdf]
52 citations

Affiliations

first authorsco-authorsvia INSPIRE