We present a first-principle computation of the jet quenching parameter, which describes the momentum broadening of a high-energy parton moving through the deconfined state of QCD matter at high ...temperature. Following an idea originally proposed by Caron-Huot, we explain how one can evaluate the soft contribution to the collision kernel characterizing this real-time phenomenon, analyzing certain gauge-invariant operators in a dimensionally reduced effective theory (electrostatic QCD), which can be studied nonperturbatively via simulations on a Euclidean lattice. Our high-precision numerical computations at two different temperatures indicate that soft contributions to the jet quenching parameter are large. After discussing the systematic uncertainties involved, we present a quantitative estimate for the jet quenching parameter in the temperature range accessible at heavy-ion colliders, and compare it to results from phenomenological models as well as to strong-coupling computations based on the holographic correspondence.
Hadrons in lattice QCD are usually created employing smeared interpolators. We introduce a new quark smearing that allows us to maintain small statistical errors and good overlaps of hadronic wave ...functions with the respective ground states, also at high spatial momenta. The method is successfully tested for the pion and the nucleon at a pion mass m sub(pi)approximate295MeV and momenta as high as 2.8 GeV. We compare the results obtained to dispersion relations and suggest further optimizations.
A
bstract
We perform a detailed investigation of multiple hard interactions in hadron-hadron collisions. We discuss the space-time, spin and color structure of multiple interactions, classify ...different contributions according to their power behavior and provide several elements required for establishing all-order factorization. This also allows us to analyze the structure of Sudakov logarithms in double hard scattering. We show how multiparton distributions can be constrained by connecting them with generalized parton distributions and by calculating their behavior at large transverse parton momenta.
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¯ hyperons in terms of the bounds they set on the magnitude of the late-time magnetic field.
Three binary pseudorotaxanes, which are based on two different secondary ammonium/crown ether binding motifs, have been studied by 1H NMR and 1H,1H EXSY NMR experiments with respect to their ...thermodynamic stabilities and their axle exchange kinetics. The stability ranking does not follow the order of axle exchange rates, and the thermodynamically most stable axle−wheel combinations assemble only slowly. On the basis of these binding motifs, a series of self-sorting systems have been studied ranging from simple four-component mixtures through sequence-specific pseudorotaxanes to multiply threaded complexes. Because of the mismatch of kinetic and thermodynamic order, wrongly assembled structures are unavoidable, which require error-correction steps to yield the final thermodynamically controlled self-sorted products. These error-correction steps can easily be monitored by electrospray mass spectrometry, when a mixed-flow microreactor is coupled to the ion source to cover second time scales. Self-assembly intermediates, wrongly assembled structures, and the final thermodynamic products can be simultaneously identified. The determination of preferred assembly pathways as well as the formation of dead-end structures provides a clear picture of a rich kinetic behavior of the self-sorting systems under study.
The COVID-19 pandemic had a dramatic impact on aviation in 2020, and the industry’s future is uncertain. In this paper, we consider scenarios for recovery and ongoing demand, and discuss the ...implications of these scenarios for aviation emissions-related policy, including the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and the EU Emissions Trading Scheme (ETS). Using the Aviation Integrated Model (AIM2015), a global aviation systems model, we project how long-term demand, fleet, and emissions projections might change. Depending on recovery scenario, we project cumulative aviation fuel use to 2050 might be up to 9% below that in scenarios not including the pandemic. The majority of this difference arises from reductions in relative global income levels. Around 40% of modeled scenarios project no offset requirement in either the CORSIA pilot or first phases; however, because of its more stringent emissions baseline (based on reductions from year 2004–2006 CO2, rather than constant year-2019 CO2), the EU ETS is likely to be less affected. However, if no new policies are applied and technology developments follow historical trends, year-2050 global net aviation CO2 is still likely to be well above industry goals, including the goal of carbon-neutral growth from 2019, even when the demand effects of the pandemic are accounted for.
A
bstract
We present lattice results for the non-perturbative Collins-Soper (CS) kernel, which describes the energy-dependence of transverse momentum-dependent parton distributions (TMDs). The CS ...kernel is extracted from the ratios of first Mellin moments of quasi-TMDs evaluated at different nucleon momenta. The analysis is done with dynamical
N
f
= 2 + 1 clover fermions for the CLS ensemble H101 (
a
= 0
.
0854 fm,
m
π
=
m
K
= 422 MeV). The computed CS kernel is in good agreement with experimental extractions and previous lattice studies.
We study the anomalous scale symmetry breaking effects on the proton mass in QCD due to quantum fluctuations at ultraviolet scales. We confirm that a novel contribution naturally arises as a part of ...the proton mass, which we call the quantum anomalous energy (QAE). We discuss the QAE origins in both lattice and dimensional regularizations and demonstrate its role as a scheme-and-scale independent component in the mass decomposition. We further argue that QAE role in the proton mass resembles a dynamical Higgs mechanism, in which the anomalous scale symmetry breaking field generates mass scales through its vacuum condensate, as well as its static and dynamical responses to the valence quarks. We demonstrate some of our points in two simpler but closely related quantum field theories, namely the 1+1 dimensional non-linear sigma model in which QAE is non-perturbative and scheme-independent, and QED where the anomalous energy effect is perturbative calculable.
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