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Nuclear Theory·nucl-th

Wednesday·May 17, 2023

15 papers—10 primary·5 cross-listed

All15Primary10Cross-lists5
  1. 11

    Is infrared-collinear safe information all you need for jet classification?

    Dimitrios Athanasakos🇺🇸 · Andrew J. Larkoski🇺🇸 · James Mulligan🇺🇸 · Mateusz Ploskon🇺🇸 · Felix Ringer🇺🇸

    Machine learning-based jet classifiers are able to achieve impressive tagging performance in a variety of applications in high-energy and nuclear physics. However, it remains unclear in many cases which aspects of jets give rise to this discriminating power, and whether jet observables that are tractable in perturbative QCD such as those obeying infrared-collinear (IRC) safety serve as sufficient inputs. In this article, we introduce a new classifier, Jet Flow Networks (JFNs), in an effort to address the question of whether IRC unsafe information provides additional discriminating power in jet classification. JFNs are permutation-invariant neural networks (deep sets) that take as input the kinematic information of reconstructed subjets. The subjet radius and a cut on the subjet's transverse momenta serve as tunable hyperparameters enabling a controllable sensitivity to soft emissions and nonperturbative effects. We demonstrate the performance of JFNs for quark vs. gluon and Z vs. QCD jet tagging. For small subjet radii and transverse momentum cuts, the performance of JFNs is equivalent to the IRC-unsafe Particle Flow Networks (PFNs), demonstrating that infrared-collinear unsafe information is not necessary to achieve strong discrimination for both cases. As the subjet radius is increased, the performance of the JFNs remains essentially unchanged until physical thresholds that we identify are crossed. For relatively large subjet radii, we show that the JFNs may offer an increased model independence with a modest tradeoff in performance compared to classifiers that use the full particle information of the jet. These results shed new light on how machines learn patterns in high-energy physics data

    ↳ hep-phhep-exnucl-thJHEP(2024)·22 citations
  2. 12

    Uncertainties on the EFT coupling limits for direct dark matter detection experiments stemming from uncertainties of target properties

    Daniel J. Heimsoth🇺🇸 · Brandon Lem🇺🇸 · Anna M. Suliga🇺🇸 · Calvin W. Johnson🇺🇸 · A. Baha Balantekin🇺🇸 · Susan N. Coppersmith🇺🇸

    Direct detection experiments are still one of the most promising ways to unravel the nature of dark matter. To fully understand how well these experiments constrain the dark matter interactions with the Standard Model particles, all the uncertainties affecting the calculations must be known. It is especially critical now because direct detection experiments recently moved from placing limits only on the two elementary spin independent and spin dependent operators to the complete set of possible operators coupling dark matter and nuclei in nonrelativistic theory. In our work, we estimate the effect of nuclear configuration-interaction uncertainties on the exclusion bounds for one of the existing xenon-based experiments for all fifteen operators. We find that for operator number 13 the uncertainty on the coupling between the dark matter and nucleon can reach more than 50% for dark matter masses between 10 and 1000 GeV. In addition, we discuss how quantum computers can help to reduce this uncertainty and how the uncertainties are affected for couplings obtained for the nonrelativistic reductions of the relativistic interactions.

    ↳ hep-phastro-ph.COhep-exnucl-thPRD(2023)·6 citations
  3. 13

    Chiral and trace anomalies in Deeply Virtual Compton Scattering II: QCD factorization and beyond

    Shohini Bhattacharya🇺🇸 · Yoshitaka Hatta🇺🇸 · Werner Vogelsang🇩🇪

    We extend the discussion of the recently discovered 'anomaly poles' in QCD Compton scattering. We perform the complete one-loop calculation of the Compton amplitude using momentum transfer as the regulator of collinear divergences. In the gluon channel, we confirm the presence of poles in both the real and imaginary parts of the amplitude. In the quark channel, we find unexpected infrared single and double poles. We then perform the one-loop calculation of the leading-twist quark generalized parton distributions (GPDs) for quark and gluon external states with the same regulators and find that all these singular terms can be systematically absorbed into the GPDs, showing that QCD factorization is restored to this order. Having established this, we discuss the fate of the poles. We argue that they become the nonperturbative building blocks of GPDs that encode the chiral and trace anomalies of QCD, in a way consistent with the known constraints these anomalies impose on the nucleon axial and gravitational form factors. The scope of research on GPDs can therefore be expanded to address the manifestation and implications of quantum anomalies in high-energy exclusive processes.

    ↳ hep-phhep-thnucl-thPRD(2023)·33 citations
  4. 14

    Absence of inhomogeneous chiral phases in 2+1-dimensional four-fermion and Yukawa models

    Laurin Pannullo🇩🇪 · Marc Winstel🇩🇪

    We show the absence of an instability of homogeneous (chiral) condensates against spatially inhomogeneous perturbations for various 2+1-dimensional four-fermion and Yukawa models. All models are studied at non-zero baryon chemical potential, while some of them are also subjected to chiral and isospin chemical potential. The considered theories contain up to 16 Lorentz-(pseudo)scalar fermionic interaction channels. We prove the stability of homogeneous condensates by analyzing the bosonic two-point function, which can be expressed in a purely analytical form at zero temperature. Our analysis is presented in a general manner for all of the different discussed models. We argue that the absence of an inhomogeneous chiral phase (where the chiral condensate is spatially non-uniform) follows from this lack of instability. Furthermore, the existence of a moat regime, where the bosonic wave function renormalization is negative, in these models is ruled out.

    ↳ hep-phcond-mat.str-elnucl-thPRD(2023)·24 citations
  5. 15

    Ultrastable optical, XUV and soft-x-ray clock transitions in open-shell highly charged ions

    Chunhai Lyu · Christoph H. Keitel · Zoltán Harman

    Highly charged ions (HCIs) are insensitive to external perturbations and are attractive for the development of ultrastable clocks. However, only a few HCI candidates are known to provide optical clock transitions. In this Letter, we show that, as a result of strong relativistic effects, there are more than 100 suitable optical HCI clock candidates in more than 70 elements. Their transitions are embedded in the fine-structure splitting of the , and ground-state configurations with being the principal quantum numbers. The corresponding high multipolarity transitions in these ions have lifetimes and quality factors many orders of magnitude longer and larger, respectively, than those in state-of-the-art clocks. Their polarizabilities are also orders of magnitude smaller, rendering them more stable against external electromagnetic fields. Furthermore, within the same electronic configurations, the clock transitions in heavy ions scale up to the XUV and soft-x-ray region, thus enable the development of clocks based on shorter wavelengths. The existence of multiple clock transitions in different charge states of a single element, as well as in a whole isoelectronic sequence, would significantly enrich the detection of fine-structure constant variations, the search for new physics and the test of nuclear theories via high-precision spectroscopy.

    ↳ physics.atom-phnucl-exnucl-thphysics.opticsCommun.Phys.(2025)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE