Nuclear Theory·nucl-th

Thursday·February 27, 2020

7 papers—2 primary·5 cross-listed

03
Quantum Algorithms for Simulating the Lattice Schwinger Model
Alexander F. Shaw🇺🇸 · Pavel Lougovski🇺🇸 · Jesse R. Stryker🇺🇸 · Nathan Wiebe🇺🇸
The Schwinger model (quantum electrodynamics in 1+1 dimensions) is a testbed for the study of quantum gauge field theories. We give scalable, explicit digital quantum algorithms to simulate the lattice Schwinger model in both NISQ and fault-tolerant settings. In particular, we perform a tight analysis of low-order Trotter formula simulations of the Schwinger model, using recently derived commutator bounds, and give upper bounds on the resources needed for simulations in both scenarios. In lattice units, we find a Schwinger model on $N /2$ physical sites with coupling constant $x^{- 1/2}$ and electric field cutoff $x^{- 1/2} Λ$ can be simulated on a quantum computer for time $2 x T$ using a number of $T$ -gates or CNOTs in $O (N^{3/2} T^{3/2} x Λ)$ for fixed operator error. This scaling with the truncation $Λ$ is better than that expected from algorithms such as qubitization or QDRIFT. Furthermore, we give scalable measurement schemes and algorithms to estimate observables which we cost in both the NISQ and fault-tolerant settings by assuming a simple target observable---the mean pair density. Finally, we bound the root-mean-square error in estimating this observable via simulation as a function of the diamond distance between the ideal and actual CNOT channels. This work provides a rigorous analysis of simulating the Schwinger model, while also providing benchmarks against which subsequent simulation algorithms can be tested.
↳ quant-phhep-latnucl-thQuantum(2020)·206 citations
04
Heavy Quark Energy Loss in the Quark-Gluon Plasma in the Moller theory
B. Blok (Technion)🇮🇱
We study the energy loss of a heavy quark propagating in the Quark-Gluon Plasma (QGP) in the framework of the Moller theory, including possible large Coulomb logarithms as a perturbation to BDMPSZ bremsstrahlung, described in the Harmonic Oscillator (HO) approximation. We derive the analytical expression that describes the energy loss in the entire emitted gluon frequency region. In the small frequencies region, for angles larger than the dead cone angle, the energy loss is controlled by the BDMPSZ mechanism, while for larger frequencies it is described by N=1 term in the GLV opacity expansion. We estimate corresponding quenching rates for different values of the heavy quark path and different $m / E$ ratios.
↳ hep-phhep-exnucl-exnucl-thEPJC(2020)·5 citations
05
Chiral Radiation Transport Theory of Neutrinos
Naoki Yamamoto🇯🇵 · Di-Lun Yang🇯🇵
We construct the chiral radiation transport equation for left-handed neutrinos in the context of radiation hydrodynamics for core-collapse supernovae. Based on the chiral kinetic theory incorporating quantum corrections due to the chirality of fermions, we derive a general relativistic form of the chiral transfer equation with collisions. We show that such quantum corrections explicitly break the spherical symmetry and axisymmetry of the system. In the inertial frame, in particular, we find that the so-called side jump leads to quantum corrections in the collisions between neutrinos and matter. We also derive analytic forms of such corrections in the emission and absorption rates for the neutrino absorption process. These corrections result in the generation of kinetic helicity and cross helicity of matter, which should then modify the subsequent evolution of matter. This theoretical framework can be applied to investigate the impacts of the chirality of neutrinos on the evolution of core-collapse supernovae.
↳ astro-ph.HEhep-phnucl-thApJ(2020)·36 citations
06
Multi-messenger constraints on the neutron-star equation of state and the Hubble constant
Tim Dietrich🇩🇪 · Michael W. Coughlin🇺🇸 · Peter T. H. Pang🇳🇱 · Mattia Bulla🇸🇪 · Jack Heinzel🇺🇸 · Lina Issa🇸🇪 · Ingo Tews🇺🇸 · Sarah Antier🇫🇷
Observations of neutron-star mergers based on distinct messengers, including gravitational waves and electromagnetic signals, can be used to study the behavior of matter denser than an atomic nucleus, and to measure the expansion rate of the Universe described by the Hubble constant. We perform a joint analysis of the gravitational-wave signal GW170817 with its electromagnetic counterparts AT2017gfo and GRB170817A, and the gravitational-wave signal GW190425, both originating from neutron-star mergers. We combine these with previous measurements of pulsars using X-ray and radio observations, and nuclear-theory computations using chiral effective field theory to constrain the neutron-star equation of state. We find that the radius of a $1.4$ solar mass neutron star is $11.7 5_{- 0.81}^{+ 0.86} km$ at $90%$ confidence and the Hubble constant is $66. 2_{- 4.2}^{+ 4.4} km Mp c^{- 1} s^{- 1}$ at $1 σ$ uncertainty.
↳ astro-ph.HEastro-ph.COgr-qcnucl-thScience(2020)·512 citations
07
Measurement of the charge separation along the magnetic field with Signed Balance Function in 200 GeV Au + Au collisions at STAR
Yufu Lin (for the STAR Collaboration)🇨🇳
Experimental searches for Chiral Magnetic Effect (CME) in heavy-ion collisions have been going on for a decade, and so far there is no conclusive evidence for its existence. Recently, the Signed Balance Function (SBF), based on the idea of examining the momentum ordering of charged pairs along the in- and out-of-plane directions, has been proposed as a probe of CME. In this approach, a pair of observables is invoked: one is $r_{rest}$ , the out-of-plane to in-plane ratio of $Δ B$ measured in pair's rest frame, where $Δ B$ is the difference between signed balance functions; The other is a double ratio, $R_{B} = r_{rest} / r_{lab}$ , where $r_{lab}$ is a measurement similar to $r_{rest}$ but measured in the laboratory frame. These two observables give opposite responses to the CME-driven charge separation compared to the background correlations arising from resonance flow and global spin alignment. Both $r_{rest}$ and $R_{B}$ being larger than unity can be regarded as a case in favor of the existence of CME. It is found experimentally that $r_{rest}$ , $r_{lab}$ and $R_{B}$ are larger than unity in Au+Au collisions at 200 GeV, and larger than realistic model calculations with no CME implemented. These findings are difficult to be explained by a background-only scenario.
↳ nucl-exhep-exhep-phnucl-thNPA(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantum Algorithms for Simulating the Lattice Schwinger Model

Heavy Quark Energy Loss in the Quark-Gluon Plasma in the Moller theory

Chiral Radiation Transport Theory of Neutrinos

Multi-messenger constraints on the neutron-star equation of state and the Hubble constant

Measurement of the charge separation along the magnetic field with Signed Balance Function in 200 GeV Au + Au collisions at STAR

Affiliations