Nuclear Theory·nucl-th

Tuesday·January 24, 2017

17 papers—10 primary·7 cross-listed

11
Parton energy loss in QCD matter
Konrad Tywoniuk🇨🇭
QCD jets, produced copiously in heavy-ion collisions at LHC and also at RHIC, serve as probes of the dynamics of the quark-gluon plasma (QGP). Jet fragmentation in the medium is interesting in its own right and, in order to extract pertinent information about the QGP, it has to be well understood. We present a brief overview of the physics involved and argue that jet substructure observables provide new opportunities for understanding the nature of the modifications.
↳ hep-phnucl-thNucl.Part.Phys.Proc.(2017)·1 citation
12
Quark matter with strong magnetic field and possibility of the third family of compact stars
Hajime Sotani🇯🇵 · Toshitaka Tatsumi🇯🇵
We consider the possibility for the existence of the third family of compact objects, considering the effect of strong magnetic fields inside the hybrid stars. As a result, we demonstrate such new sequences of stable equilibrium configurations for some hadronic equations of state. Through the analysis of the adiabatic index inside stars, we find the conditions for appearing the third family of compact objects, i.e., for hadronic stars without quarks, that the maximum mass should be small, the central density for the maximum mass should be also small, and the radius for the the maximum mass should be large. Even for soft hadronic equations of state, the two solar-mass stars might survive as the third family of compact objects, once quark matter with strong magnetic field, such as $\sim O (1 0^{19} G)$ , is taken into account. It might give a hint to solve the so-called hyperon puzzle in nuclear physics.
↳ astro-ph.HEhep-phnucl-thMNRAS(2017)·12 citations
13
Temperature oscillations and sound waves in hadronic matter
Grzegorz Wilk🇵🇱 · Zbigniew Wlodarczyk🇵🇱
Recent high energy CERN LHC experiments on transverse momenta distributions of produced particles seem to show the existence of some (small but persistent) log-periodic oscillation in the ratios $R = σ_{d a t a} (p_{T}) / σ_{f i t} (p_{T})$ . We argue that they can provide us with so far unnoticed information on the production process, which can be interpreted as the presence of some kind of sound waves formed during the collision process in the bulk of the produced high density matter.
↳ hep-phcond-mat.stat-mechnucl-thPhysica A(2017)·8 citations
14
Probing the possibility of hotspots on the central neutron star in HESS J1731-347
V.F. Suleimanov · D. Klochkov · J. Poutanen · K. Werner
The X-ray spectra of the neutron stars located in the centers of supernova remnants Cas A and HESS J1731-347 are well fit with carbon atmosphere models. These fits yield plausible neutron star sizes for the known or estimated distances to these supernova remnants. The evidence in favor of the presence of a pure carbon envelope at the neutron star surface is rather indirect and is based on the assumption that the emission is generated uniformly by the entire stellar surface. Although this assumption is supported by the absence of pulsations, the observational upper limit on the pulsed fraction is not very stringent. In an attempt to quantify this evidence, we investigate the possibility that the observed spectrum of the neutron star in HESS J1731-347 is a combination of the spectra produced in a hydrogen atmosphere of the hotspots and of the cooler remaining part of the neutron star surface. The lack of pulsations in this case has to be explained either by a sufficiently small angle between the neutron star spin axis and the line of sight, or by a sufficiently small angular distance between the hotspots and the neutron star rotation poles. As the observed flux from a non-uniformly emitting neutron star depends on the angular distribution of the radiation emerging from the atmosphere, we have computed two new grids of pure carbon and pure hydrogen atmosphere model spectra accounting for Compton scattering. Using new hydrogen models, we have evaluated the probability of a geometry that leads to a pulsed fraction below the observed upper limit to be about 8.2 %. Such a geometry thus seems to be rather improbable but cannot be excluded at this stage.
↳ astro-ph.HEastro-ph.SRnucl-thAstron.Astrophys.(2017)·17 citations
15
Harmonic decomposition of three-particle azimuthal correlations at RHIC
STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · N. N. Ajitanand · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin · E. C. Aschenauer and 336 other authors
We present measurements of three-particle correlations for various harmonics in Au+Au collisions at energies ranging from $s_{NN} = 7.7$ to 200 GeV using the STAR detector. The quantity $⟨ cos (m ϕ_{1} + n ϕ_{2} - (m + n) ϕ_{3})⟩$ is evaluated as a function of $s_{NN}$ , collision centrality, transverse momentum, $p_{T}$ , pseudo-rapidity difference, $Δ η$ , and harmonics ( $m$ and $n$ ). These data provide detailed information on global event properties like the three-dimensional structure of the initial overlap region, the expansion dynamics of the matter produced in the collisions, and the transport properties of the medium. A strong dependence on $Δ η$ is observed for most harmonic combinations consistent with breaking of longitudinal boost invariance. Data reveal changes with energy in the two-particle correlation functions relative to the second-harmonic event-plane and provide ways to constrain models of heavy-ion collisions over a wide range of collision energies.
↳ nucl-exnucl-thPRC(2018)·60 citations
16
Constraining the initial conditions and temperature dependent transport with three-particle correlations in Au+Au collisions
STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · N. N. Ajitanand · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin · E. C. Aschenauer and 336 other authors
We present three-particle mixed-harmonic correlations $\la cos (m ϕ_{a} + n ϕ_{b} - (m + n) ϕ_{c}) \ra$ for harmonics $m, n = 1 - 3$ for charged particles in $s_{N N} =$ 200 GeV Au+Au collisions at RHIC. These measurements provide information on the three-dimensional structure of the initial collision zone and are important for constraining models of a subsequent low-viscosity quark-gluon plasma expansion phase. We investigate correlations between the first, second and third harmonics predicted as a consequence of fluctuations in the initial state. The dependence of the correlations on the pseudorapidity separation between particles show hints of a breaking of longitudinal invariance. We compare our results to a number of state-of-the art hydrodynamic calculations with different initial states and temperature dependent viscosities. These measurements provide important steps towards constraining the temperature dependent transport and the longitudinal structure of the initial state at RHIC.
↳ nucl-exnucl-thPLB(2019)·14 citations
17
Rescattering effects in the hadronic-light-by-light contribution to the anomalous magnetic moment of the muon
Gilberto Colangelo🇨🇭 · Martin Hoferichter🇺🇸 · Massimiliano Procura🇨🇭 · Peter Stoffer🇩🇪
We present a first model-independent calculation of $π π$ intermediate states in the hadronic-light-by-light (HLbL) contribution to the anomalous magnetic moment of the muon $(g - 2)_{μ}$ that goes beyond the scalar QED pion loop. To this end we combine a recently developed dispersive description of the HLbL tensor with a partial-wave expansion and demonstrate that the known scalar-QED result is recovered after partial-wave resummation. Using dispersive fits to high-statistics data for the pion vector form factor, we provide an evaluation of the full pion box, $a_{μ}^{π -box} = - 15.9 (2) \times 1 0^{- 11}$ . We then construct suitable input for the $γ^{*} γ^{*} \to π π$ helicity partial waves based on a pion-pole left-hand cut and show that for the dominant charged-pion contribution this representation is consistent with the two-loop chiral prediction and the COMPASS measurement for the pion polarizability. This allows us to reliably estimate $S$ -wave rescattering effects to the full pion box and leads to our final estimate for the sum of these two contributions: $a_{μ}^{π -box} + a_{μ, J = 0}^{π π, π -pole LHC} = - 24 (1) \times 1 0^{- 11}$ .
↳ hep-phhep-exhep-latnucl-thPRL(2017)·192 citations

Affiliations

first authorsco-authorsvia INSPIRE

Parton energy loss in QCD matter

Quark matter with strong magnetic field and possibility of the third family of compact stars

Temperature oscillations and sound waves in hadronic matter

Probing the possibility of hotspots on the central neutron star in HESS J1731-347

Harmonic decomposition of three-particle azimuthal correlations at RHIC

Constraining the initial conditions and temperature dependent transport with three-particle correlations in Au+Au collisions

Rescattering effects in the hadronic-light-by-light contribution to the anomalous magnetic moment of the muon

Affiliations