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  1. 𝜌-meson nucleon scattering length from CLAS threshold photoproduction measurements

    Strakovsky, Igor I. ; Isupov, Evgeny L. ; Mokeev, Victor ; ... - Physical Review. D.
    Here, extending our study of the vector meson-nucleon scattering lengths, we are focusing on the 𝜌-meson case using recent CLAS threshold data for the reaction 𝛾⁒𝑝 β†’πœŒβ’π‘ within the meson–baryon reaction model. The total πœŽπ‘‘β‘(𝛾⁒𝑝 β†’πœŒβ’π‘) and πœŽπ‘‘β‘(𝛾⁒𝑝 β†’πœ”β’π‘) cross sections are close to the momentum of the vector meson in CM π‘ž =0.2 GeV/c. Then the πœŒβ’π‘ photoproduction cross section grows rapidly. Our result for πœŒβ’π‘ scattering length is a factor of 4 smaller than the size of the hadron and the phenomenological determination of the πœ” nucleon scattering length using threshold photoproduction cross sections. The observed difference betweenmore » πœŒβ’π‘ and πœ”β’π‘ scattering lengths is of interest for further understanding within hadron structure theory.« less

  2. Model-agnostic likelihood for the reinterpretation of the 𝐡+β†’ 𝐾+⁒$$𝑣\bar{𝑣}$$ measurement at Belle II

    Abumusabh, M. ; Adachi, I. ; Aggarwal, L. ; ... - Physical Review. D.
    We recently measured the branching fraction of the 𝐡+β†’ 𝐾+⁒$$𝑣\bar{𝑣}$$ decay using 362 fbβˆ’1 of on-resonance 𝑒+β’π‘’βˆ’ collision data under the assumption of Standard Model kinematics, providing the first evidence for this decay. To facilitate future reinterpretations and maximize the scientific impact of this measurement, we publicly release the full analysis likelihood along with all necessary material required for reinterpretation under arbitrary theoretical models sensitive to this measurement. In this work, we demonstrate how the measurement can be reinterpreted within the framework of the weak effective theory. Using a kinematic reweighting technique in combination with the published likelihood, we derivemore » marginal posterior distributions for the Wilson coefficients, construct credible intervals, and assess the goodness of fit to the Belle II data. For the weak effective theory Wilson coefficients, the posterior mode of the magnitudes |𝐢VL+𝐢VR|, |𝐢SL +𝐢SR|, and |𝐢TL| corresponds to the point (11.3, 0.0, 8.2). The respective 95% credible intervals are [1.9, 16.2], [0.0, 15.4], and [0.0, 11.2].« less

  3. Hitting the Thermal Target for Leptophilic Dark Matter at Future Lepton Colliders

    Cesarotti, Cari ; Krnjaic, Gordan - Physical Review Letters
    We study future lepton collider prospects for testing predictive models of leptophilic dark matter (DM) candidates with a thermal origin. We calculate experimental milestones for testing the parameter space compatible with freeze-out and the associated collider signals at past, present, and future facilities. This analysis places new limits on such models by leveraging the utility of lepton colliders. At 𝑒+β’π‘’βˆ’ machines, we make projections using precision 𝑍 -pole observables from 𝑒+β’π‘’βˆ’β†’β„“+β’β„“βˆ’+𝐸 signatures at large electron-positron collider and future projections for future circular collider (ee) in these channels. Additionally, a muon collider could also probe new thermal relic parameter space inmore » this scenario via πœ‡+β’πœ‡βˆ’β†’π‘‹+𝐸 , where 𝑋 is any easily identifiable standard model object. Collectively, these processes can probe much of the parameter space for which DM direct annihilation to β„“+β’β„“βˆ’ yields the observed relic density in Higgs-like models with mass-proportional couplings to charged leptons.« less

  4. Exploring quantum statistics for massive Dirac and Majorana neutrinos using spinor-helicity techniques

    Bigaran, Innes ; Parke, Stephen J. ; Pasquini, Pedro - Physical Review. D.
    Recently, there has been interest in the applicability of quantum statistics to distinguish Dirac from Majorana neutrinos in multineutrino final states. In particular, debate has arisen over the validity of the Dirac-Majorana confusion theorem in these processes, i.e., that any distinction between the Dirac and Majorana processes goes to zero as the neutrino mass goes to zero. Here we approach this problem equipped with spinor-helicity methods generalized for massive Dirac and Majorana fermions. We explicitly calculate all helicity amplitudes, and their squares, for the decay of a light scalar particle to two neutrinos and two oppositely charged leptons. This allowsmore » us to pinpoint the crucial steps which could lead to claims of a violation of the confusion theorem. We show that, if the correct antisymmetrization of Dirac to Majorana amplitudes is used, identification of which is clear in this framework, and all relevant contributions are appropriately summed, a scalar decay into two charged leptons and two neutrinos satisfies the Dirac-Majorana confusion theorem.« less

  5. Piezoelectric bulk acoustic resonators for dark photon detection

    Trickle, Tanner - Physical Review D
    The kinetically mixed dark photon is a simple, testable dark matter candidate with strong theoretical motivation. Detecting the feeble electric field dark photon dark matter produces requires extremely sensitive detectors. Bulk acoustic resonators (BARs), with their exceptionally high-quality phonon modes, are highly sensitive detectors, and have previously leveraged this sensitivity to search for gravitational waves in the MHz to GHz frequency range. The BAR phonons are typically read out by detecting the electric field generated by the BAR materials’ piezoelectricity. Here we show that this piezoelectricity also rewards such detectors sensitivity to dark photon dark matter, as the dark electricmore » field can resonantly excite BAR phonons. A single 10 g piezoelectric BAR in a large, cold, environment can be orders of magnitude more sensitive to the kinetic mixing parameter than any current experiment, with only a month-long exposure and thermally limited backgrounds.« less

  6. Lepton flavor violation by three units

    Heeck, Julian ; Sokhashvili, Mikheil ; Thapa, Anil - Physical Review. D.
    The conservation of lepton flavor is a prediction of the Standard Model and is still an excellent approximate symmetry despite our observation of neutrino oscillations. Lepton flavor violation by one or two units has been discussed for decades, with several dedicated experiments exploring the vast model landscape but no discoveries so far. Here, we explore operators and processes that violate at least one lepton flavor by three units and identify testable signatures. In the Standard Model effective field theory, such operators already arise at mass dimension 7 and can be tested through their contributions to Michel parameters in leptonic decays.more » True neutrinoless charged-lepton flavor violation arises at mass dimension 10 and can realistically only be seen in the tau decay channels 𝜏 β†’ $$𝑒⁒𝑒⁒𝑒⁒\bar{πœ‡}⁒\bar{πœ‡}$$ or 𝜏 β†’ $$πœ‡β’πœ‡β’πœ‡\bar{𝑒}\bar{𝑒}$$, for example in Belle II. Testable rates for these tau decays require light new particles and subsequently predict an avalanche of remarkably clean but so-far unconstrained collider signatures.« less

  7. New physics particles mixing with mesons: Production in the fragmentation chain

    Kyselov, Yehor ; Mrenna, Stephen ; Ovchynnikov, Maksym - Physical Review D
    A class of extensions to the Standard Model adds hypothetical long-lived particles (LLPs) that have mass- or kinetic-mixing with neutral mesons, such as pions or rho mesons. The mixing can contribute significantly to the production of LLPs at proton accelerator experiments, and no consistent description of these production modes exists in the literature. In this paper, we develop a framework for studying different LLPsβ€”dark photons, vector mediators coupled to the baryon current, and axionlike particles with different coupling patterns. In particular, we implement the production mechanisms in PYTHIA8, study how the overall flux and kinematic distributions depend on the LLP’smore » mass, and compare various subprocesses where the mixing contributesβ€”proton bremsstrahlung, meson decay, and production in the fragmentation chain. We find that our new description of LLP production predicts an integrated flux that differs from current approaches by one to two orders of magnitude, and highlight the unavoidable theoretical uncertainties coming from poor knowledge of the properties of heavy mesons.« less

  8. Bayesian optimization of PYTHIA8 tunes

    Al Kadhim, Ali ; Prosper, Harrison B. ; Mrenna, Stephen - Physical Review D
    A new tune (set of model parameters) is found for the six most important parameters of the PYTHIA8 final state parton shower and hadronization model using Bayesian optimization. The tune fits the Large Electron-Positron collider (LEPI) data from ALEPH better than the default tune in PYTHIA8. To the best of our knowledge, we present the most comprehensive application of Bayesian optimization to the tuning of a parton shower and hadronization model using the LEPI data.

  9. Gravitational wave detection with plasma haloscopes

    Capdevilla, Rodolfo ; Gelmini, Graciela B. ; Hyman, Jonah ; ... - Physical Review. D.
    Searches for high frequency gravitational waves using cavities based on the Gertsenshtein effect were recently proposed, building off existing axion dark matter experiments. In particular, the sensitivity of axion dark matter experiments using metamaterial plasmas (tunable plasma haloscopes) to gravitational waves has not been explored in detail. Here we perform a full analysis of gravitational wave detection in plasma haloscopes, showing that the baseline design of experiments such as ALPHA is several orders of magnitude less sensitive than previously thought. We show how simple changes to the experiment can recover that sensitivity and lead to a powerful gravitational wave detectormore » in the π’ͺ⁑(10–50) GHz frequency range.« less

  10. Extending the dark matter reach of water Cherenkov detectors using Jupiter

    Robles, Sandra ; Meighen-Berger, Stephan A. - Physical Review. D.
    We propose the first method for water Cherenkov detectors to constrain GeV-scale dark matter (DM) below the solar evaporation mass. While previous efforts have highlighted the Sun and Earth as DM capture targets, we demonstrate that Jupiter is a viable target. Jupiter’s unique characteristics, such as its lower core temperature and significant gravitational potential, allow it to capture and retain light DM more effectively than the Sun, particularly in the mass range below 4 GeV where direct detection sensitivity diminishes. Our calculations provide the first sensitivity estimates to GeV-scale annihilating DM within Jupiter, predicting Hyper-K can reach spin dependent crossmore » sections as low as $$𝜎^{SD}_{π‘β’πœ’}$$ = 2Γ—10βˆ’35 cm2 for DM masses below 2 GeV. This surpasses current solar limits and direct detection results. We additionally provide estimates for Super-K ORCA, and the IceCube-Upgrade, showing that these experiments could provide complimentary bounds to direct detection experiments.« less
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