Nuclear Theory·nucl-th

Friday·June 29, 2018

7 papers—2 primary·5 cross-listed

03
Joint resummation of two angularities at next-to-next-to-leading logarithmic order
Massimiliano Procura🇨🇭 · Wouter J. Waalewijn🇳🇱 · Lisa Zeune🇳🇱
Multivariate analyses are emerging as important tools to understand properties of hadronic jets which play a key role in the LHC experimental program. We take a first step towards precise and differential theory predictions by calculating the cross section for $e^{+} e^{-} \to$ 2 jets differential in the angularities $e_{α}$ and $e_{β}$ . The logarithms of $e_{α}$ and $e_{β}$ in the cross section are jointly resummed to next-to-next-to-leading logarithmic accuracy, using the SCET+ framework we developed, and are matched to the next-to-leading order cross section. We perform analytic one-loop calculations that serve as input for our numerical analysis, provide controlled theory uncertainties, and compare our results to Pythia. We also obtain predictions for the cross section differential in the ratio $e_{α} / e_{β}$ , which cannot be determined from a fixed-order calculation. The effect of nonperturbative corrections is also investigated. Using Event2, we validate the logarithmic structure of the single angularity cross section predicted by factorization theorems at $O (α_{s}^{2})$ , demonstrating that for specific angularities recoil must be taken into account when using the thrust axis, while it can be ignored if these are measured with respect to the winner-take-all axis.
↳ hep-phnucl-thJHEP(2018)·56 citations
04
The Chiral Magnetic Effect and an experimental bound on the late time magnetic field strength
Berndt Müller🇺🇸 · Andreas Schäfer🇩🇪
We first compare different approaches to estimates of the magnitude of the chiral magnetic effect in relativistic heavy ion collisions and show that their main difference lies in the assumptions on the length of persistence of the magnetic field generated by the colliding nuclei. We then analyze recent measurements of the global polarization of $Λ$ and $Λ ˉ$ hyperons in terms of the bounds they set on the magnitude of the late time magnetic field.
↳ hep-phnucl-thPRD(2018)·56 citations
05
The twist-three distribution $e^{q} (x, k_{⊥})$ in a light-front model
B. Pasquini (1, 2)🇮🇹 · S. Rodini (1, 2) ((1) Pavia U., (2) INFN, Pavia)🇮🇹
We discuss the twist-three, unpolarized, chiral-odd, transverse momentum dependent parton distribution (TMD) $e^{q} (x, k_{⊥})$ within a light-front model. We review a model-independent decomposition of this TMD, which follows from the QCD equations of motion and is given in terms of a leading-twist mass term, a pure interaction-dependent contribution, and singular terms. The leading-twist and pure twist-three terms are represented in terms of overlap of light-front wave functions (LFWFs), taking into account the Fock states with three valence quark ( $3 q$ ) and three-quark plus one gluon ( $3 q + g$ ). The $3 q$ and $3 q + g$ LFWFs with total orbital angular momentum zero are modeled using a parametrization derived from the conformal expansion of the proton distribution amplitudes, with parameters fitted to reproduce available phenomenological information on the unpolarized leading-twist quark and gluon collinear parton distributions. Numerical predictions for both the quark TMD $e^{q} (x, k_{⊥})$ and the collinear parton distribution $e^{q} (x)$ are presented, discussing the role of the quark-gluon correlations in the proton.
↳ hep-phhep-exnucl-exnucl-thPLB(2019)·50 citations
06
Relativistic tidal properties of superfluid neutron stars
Prasanta Char🇮🇳 · Sayak Datta🇮🇳
We investigate the tidal deformability of a superfluid neutron star. We calculate the equilibrium structure in the general relativistic two-fluid formalism with entrainment effect where we take neutron superfluid as one fluid and the other fluid is comprised of protons and electrons, making it a charge neutral fluid. We use a relativistic mean field model for the equation of state of matter where the interaction between baryons is mediated by the exchange $σ$ , $ω$ and $ρ$ mesons. Then, we study the linear, static $l = 2$ perturbation on the star to compute the electric-type Love number following Hinderer's prescription.
↳ gr-qcastro-ph.HEnucl-thPRD(2018)·19 citations
07
Transport peak in thermal spectral function of $N = 4$ supersymmetric Yang-Mills plasma at intermediate coupling
Jorge Casalderrey-Solana🇬🇧 · Sašo Grozdanov🇺🇸 · Andrei O. Starinets🇬🇧
We study the structure of thermal spectral function of the stress-energy tensor in $N = 4$ supersymmetric Yang-Mills theory at intermediate 't Hooft coupling and infinite number of colors. In gauge-string duality, this analysis reduces to the study of classical bulk supergravity with higher-derivative corrections, which correspond to (inverse) coupling corrections on the gauge theory side. We extrapolate the analysis of perturbative leading-order corrections to intermediate coupling by non-perturbatively solving the equations of motion of metric fluctuations dual to the stress-energy tensor at zero spatial momentum. We observe the emergence of a separation of scales in the analytic structure of the thermal correlator associated with two types of characteristic relaxation modes. As a consequence of this separation, the associated spectral function exhibits a narrow structure in the small frequency region which controls the dynamics of transport in the theory and may be described as a transport peak typically found in perturbative, weakly interacting thermal field theories. We compare our results with generic expectations drawn from perturbation theory, where such a structure emerges as a consequence of the existence of quasiparticles.
↳ hep-thhep-lathep-phnucl-thPRL(2018)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE

Joint resummation of two angularities at next-to-next-to-leading logarithmic order

The Chiral Magnetic Effect and an experimental bound on the late time magnetic field strength

The twist-three distribution eq(x,k⊥​) in a light-front model

Relativistic tidal properties of superfluid neutron stars

Transport peak in thermal spectral function of N=4 supersymmetric Yang-Mills plasma at intermediate coupling

Affiliations

The twist-three distribution $e^{q} (x, k_{⊥})$ in a light-front model

Transport peak in thermal spectral function of $N = 4$ supersymmetric Yang-Mills plasma at intermediate coupling