Nuclear Theory·nucl-th

Wednesday·April 19, 2017

15 papers—9 primary·6 cross-listed

10
[Submitted on 18 Apr 2017] (cross-list from hep-lat)
High statistics study of in-medium S- and P-wave quarkonium states in lattice Non-relativistic QCD
Seyong Kim🇰🇷 · Peter Petreczky🇺🇸 · Alexander Rothkopf🇩🇪
Many measurements of quarkonium suppression at the LHC, e.g. the nuclear modification factor $R_{AA}$ of $J /Ψ$ , are well described by a multitude of different models. Thus pinpointing the underlying physics aspects is difficult and guidance based on first principles is needed. Here we present the current status of our ongoing high precision study of in-medium spectral properties of both bottomonium and charmonium based on NRQCD on the lattice. This effective field theory allows us to capture the physics of quarkonium without modeling assumptions in a thermal QCD medium. In our study a first principles and realistic description of the QCD medium is provided by state-of-the-art lattices of the HotQCD collaboration at almost physical pion mass. Our updated results corroborate a picture of sequential modification of states with respect to their vacuum binding energy. Using a novel low-gain variant of the Bayesian BR method for reconstructing spectral functions we find that remnant features of the Upsilon may survive up to $T \sim 400$ MeV, while the $χ_{b}$ signal disappears around $T \sim 270$ MeV. The $c c ˉ$ analysis hints at melting of $χ_{c}$ below $T \sim 190$ MeV while some $J /Ψ$ remnant feature might survive up to $T \sim 245$ MeV. An improved understanding of the numerical artifacts in the Bayesian approach and the availability of increased statistics have made possible a first quantitative study of the in-medium ground state masses, which tend to lower values as $T$ increases, consistent with lattice potential based studies.
Comments:
4 pages, 3 figures, oral contribution to the XXVI International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017), Chicago, USA, February 6-11, 2017
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05221 [pdf]
NPA(2017)·2 citations
11
[Submitted on 18 Apr 2017] (cross-list from hep-ph)
Thermal effects on $ρ$ meson properties in an external magnetic field
Snigdha Ghosh🇮🇳 · Arghya Mukherjee🇮🇳 · Mahatsab Mandal🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳
A detailed study of the analytic structure of 1-loop self energy graphs for neutral and charged $ρ$ mesons is presented at finite temperature and arbitrary magnetic field using the real time formalism of thermal field theory. The imaginary part of the self energy is obtained from the discontinuities of these graphs across the Unitary and Landau cuts, which is seen to be different for $ρ^{0}$ and $ρ^{\pm}$ . The magnetic field dependent vacuum contribution to the real part of the self energy, which is usually ignored, is found to be appreciable. A significant effect of temperature and magnetic field is seen in the self energy, spectral function, effective mass and dispersion relation of $ρ^{0}$ as well as of $ρ^{\pm}$ relative to its trivial Landau shift. However, for charged $ρ$ mesons, on account of the dominance of the Landau term, the effective mass appears to be independent of temperature. The trivial coupling of magnetic moment of $ρ^{\pm}$ with external magnetic field, when incorporated in the calculation, makes the $ρ^{\pm}$ to condense at high magnetic field.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05319 [pdf]
PRD(2017)·40 citations
12
[Submitted on 18 Apr 2017] (cross-list from hep-th)
Real-Time dynamics and phase separation in a holographic first order phase transition
Romuald A. Janik🇵🇱 · Jakub Jankowski🇵🇱 · Hesam Soltanpanahi🇮🇷
We study the fully nonlinear time evolution of a holographic system possessing a first order phase transition. The initial state is chosen in the spinodal region of the phase diagram, and includes an inhomogeneous perturbation in one of the field theory directions. The final state of the time evolution shows a clear phase separation in the form of domain formation. The results indicate the existence of a very rich class of inhomogeneous black hole solutions.
Comments:
4 pages,4 figures, one reference added
Subjects:
High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05387 [pdf]
PRL(2017)·60 citations
13
[Submitted on 18 Apr 2017] (cross-list from hep-ph)
Universality regained: Kibble-Zurek dynamics, off-equilibrium scaling and the search for the QCD critical point
Swagato Mukherjee🇺🇸 · Raju Venugopalan🇺🇸 · Yi Yin🇺🇸
We generalize and apply the key elements of the Kibble-Zurek framework of nonequilibrium phase transitions to study the non-equilibrium critical cumulants near the QCD critical point. We demonstrate the off-equilibrium critical cumulants are expressible as universal scaling functions. We discuss how to use off-equilibrium scaling to provide powerful model-independent guidance in searches for the QCD critical point.
Comments:
4 pages, 6 figures, contribution to the proceedings of Quark Matter - XXVI international conference on ultrarelativistic heavy-ion collisions (Chicago, USA, February 5 to February 11, 2017), a minor typo corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05427 [pdf]
NPA(2017)·7 citations
14
[Submitted on 18 Apr 2017] (cross-list from astro-ph.HE)
Cosmic rays, anti-helium, and an old navy spotlight
Kfir Blum🇮🇱 · Kenny Chun Yu Ng🇮🇱 · Ryosuke Sato🇮🇱 · Masahiro Takimoto🇯🇵
Cosmic-ray anti-deuterium and anti-helium have long been suggested as probes of dark matter, as their secondary astrophysical production was thought extremely scarce. But how does one actually predict the secondary flux? Anti-nuclei are dominantly produced in pp collisions, where laboratory cross section data is lacking. We make a new attempt at tackling this problem by appealing to a scaling law of nuclear coalescence with the physical volume of the hadronic emission region. The same volume is probed by Hanbury Brown-Twiss (HBT) two-particle correlations. We demonstrate the consistency of the scaling law with systems ranging from central and off-axis AA collisions to pA collisions, spanning 3 orders of magnitude in coalescence yield. Extending the volume scaling to the pp system, HBT data allows us to make a new estimate of coalescence, that we test against preliminary ALICE pp data. For anti-helium the resulting cross section is 1-2 orders of magnitude higher than earlier estimates. The astrophysical secondary flux of anti-helium could be within reach of a five-year exposure of AMS02.
Comments:
16 pages, 15 figures. v2: match journal version
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05431 [pdf]
PRD(2017)·116 citations
15
[Submitted on 18 Apr 2017] (cross-list from hep-lat)
$P$ -wave $π π$ scattering and the $ρ$ resonance from lattice QCD
Constantia Alexandrou🇨🇾 · Luka Leskovec🇺🇸 · Stefan Meinel🇺🇸 · John Negele🇺🇸 · Srijit Paul🇨🇾 · Marcus Petschlies🇩🇪 · Andrew Pochinsky🇺🇸 · Gumaro Rendon🇺🇸 · Sergey Syritsyn🇺🇸
We calculate the parameters describing elastic $I = 1$ , $P$ -wave $π π$ scattering using lattice QCD with $2 + 1$ flavors of clover fermions. Our calculation is performed with a pion mass of $m_{π} \approx 320 MeV$ and a lattice size of $L \approx 3.6$ fm. We construct the two-point correlation matrices with both quark-antiquark and two-hadron interpolating fields using a combination of smeared forward, sequential and stochastic propagators. The spectra in all relevant irreducible representations for total momenta $∣ P ∣ \leq 3 \frac{2 π}{L}$ are extracted with two alternative methods: a variational analysis as well as multi-exponential matrix fits. We perform an analysis using Lüscher's formalism for the energies below the inelastic thresholds, and investigate several phase shift models, including possible nonresonant contributions. We find that our data are well described by the minimal Breit-Wigner form, with no statistically significant nonresonant component. In determining the $ρ$ resonance mass and coupling we compare two different approaches: fitting the individually extracted phase shifts versus fitting the $t$ -matrix model directly to the energy spectrum. We find that both methods give consistent results, and at a pion mass of $a m_{π} = 0.18295 (36)_{s t a t}$ obtain $g_{ρ π π} = 5.69 (13)_{s t a t} (16)_{sy s}$ , $a m_{ρ} = 0.4609 (16)_{s t a t} (14)_{sy s}$ , and $a m_{ρ} / a m_{N} = 0.7476 (38)_{s t a t} (23)_{sy s}$ , where the first uncertainty is statistical and the second is the systematic uncertainty due to the choice of fit ranges.
Comments:
20 pages, 12 figures, published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05439 [pdf]
PRD(2017)·133 citations

Affiliations

first authorsco-authorsvia INSPIRE

High statistics study of in-medium S- and P-wave quarkonium states in lattice Non-relativistic QCD

Thermal effects on ρ meson properties in an external magnetic field

Real-Time dynamics and phase separation in a holographic first order phase transition

Universality regained: Kibble-Zurek dynamics, off-equilibrium scaling and the search for the QCD critical point

Cosmic rays, anti-helium, and an old navy spotlight

P-wave ππ scattering and the ρ resonance from lattice QCD

Affiliations

Thermal effects on $ρ$ meson properties in an external magnetic field

$P$ -wave $π π$ scattering and the $ρ$ resonance from lattice QCD