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  1. Probing light quark Yukawa couplings through angularity distributions in Higgs boson decay

    Yan, Bin ; Lee, Christopher - Journal of High Energy Physics (Online)
    We propose to utilize angularity distributions in Higgs boson decay to probe light quark Yukawa couplings at e+e- colliders. Angularities $$τ$$a are a class of 2-jet event shapes with variable and tunable sensitivity to the distribution of radiation in hadronic jets in the final state. Using soft-collinear effective theory (SCET), we present a prediction of angularity distributions from Higgs decaying to quark and gluon states at e+e- colliders to NNLL + $$\mathcal{O}$$(αs) accuracy. Due to the different color structures in quark and gluon jets, the angularity distributions from H → $$q\overline{q}$$ and H → gg show different behaviors and canmore » be used to constrain the light quark Yukawa couplings. We show that the upper limit of light quark Yukawa couplings could be probed to the level of ~ 15% of the bottom quark Yukawa coupling in the Standard Model in a conservative analysis window far away from nonperturbative effects and other uncertainties; the limit can be pushed to ≲ 7 – 9% with better control of the nonperturbative effects especially on gluon angularity distributions and/or with multiple angularities.« less

  2. Enhanced Production of Λ b 0 Baryons in High-Multiplicity p p Collisions at s = 13     TeV

    Aaij, R. ; Abdelmotteleb, A. S. W. ; Abellan Beteta, C. ; ... - Physical Review Letters
    The production rate of Λ b 0 baryons relative to B 0 mesons in p p collisions at a center-of-mass energy s = 13     TeV is measured by the LHCb experiment. The ratio of Λ b 0 to B 0 production cross sections shows a significant dependence on both the transverse momentum and the measured charged-particle multiplicity. At low multiplicity, the ratio measured at LHCb is consistent with the valuemore » measured in e + e − collisions, and increases by a factor of ∼ 2 with increasing multiplicity. At relatively low transverse momentum, the ratio of Λ b 0 to B 0 cross sections is higher than what is measured in e + e − collisions, but converges with the e + e − ratio as the momentum increases. These results imply that the evolution of heavy b quarks into final-state hadrons is influenced by the density of the hadronic environment produced in the collision. Comparisons with several models and implications for the mechanisms enforcing quark confinement are discussed. © 2024 CERN, for the LHCb Collaboration 2024 CERN« less

  3. Adiabatic and post-adiabatic hyperspherical treatment of the huge ungerade proton-hydrogen scattering length

    Singh, Shayamal ; Greene, Chris H. - Canadian Journal of Physics
    While the hydrogen molecular ion is the simplest molecule in nature and very well studied in all of its properties, it remains an interesting system to use for explorations of fundamental questions. One such question treated in this study relates to finding an optimal adiabatic representation of the physics, i.e., the best adiabatic description that minimizes the role of nonadiabatic effects. As a test case explored here in detail, we consider the ungerade symmetry of $$H$$$^{+}_{2}$$, which is known to have a huge scattering length of order 750 Bohr radii, and an incredibly weakly bound excited state. We show thatmore » a hyperspherical adiabatic description does an excellent job of capturing the main physics. Furthermore, our calculation yields a competitive scattering length and shows that nonadiabatic corrections are small and can even be adequately captured using the post-adiabatic theory of Klar and Fano.« less

  4. Centrality-dependent modification of hadron and jet production in electron-nucleus collisions

    Li, Hai Tao ; Liu, Ze Long ; Vitev, Ivan - Physics Letters. B

  5. SPLENDAQ: A Detector-Agnostic Data Acquisition System for Small-Scale Physics Experiments

    Watkins, Samuel Linton - Journal of Low Temperature Physics
    Many scientific applications from rare-event searches to condensed matter system characterization to high-rate nuclear experiments require time-domain triggering on a raw stream of data, where the triggering is generally threshold-based or randomly acquired. When carrying out detector R &D, there is a need for a general data acquisition (DAQ) system to quickly and efficiently process such data. In the SPLENDOR collaboration, we are developing the Python-based SPLENDAQ package for this exact purpose—it offers two main features for offline analysis of continuous data: a threshold triggering algorithm based on the time-domain optimal filter formalism and an algorithm for randomly choosing nonoverlappingmore » segments for noise measurements. Further, combined with the commercially available Moku platform, developed by Liquid Instruments, we have a full pipeline of event building off raw data with minimal setup. Here, we review the underlying principles of this detector-agnostic DAQ package and give concrete examples of its utility in various applications.« less

  6. Deep underground measurement of B 11 ( α , n ) N 14

    Borgwardt, Tyler C. ; deBoer, Richard James ; Boeltzig, Axel ; ... - Physical Review. C
    The primordial elemental abundance composition of the first stars leads to questions about their modes of energy production and nucleosynthesis. The formation of 12C has been thought to occur primarily through the 3α process, however, alternative reaction chains may contribute significantly, such as 7Li (α, γ)11B (α,n)14N. This reaction sequence cannot only bypass the mass A = 8 stability gap, but could also be a source of neutrons in the first star environment. However, the efficiency of this reaction chain depends on the possible enhancement of its low energy cross section by α-cluster resonances near the reaction threshold. A newmore » study of the reaction 11B(α,n) 14N has been undertaken at the CASPAR underground facility at beam energies from 300–700 keV. A 4π neutron detector in combination with pulse shape discrimination at low background conditions resulted in the ability to probe energies lower than previously measured. Further, resonance strengths were determined for both the resonance at a laboratory energy of 411 keV, which was measured for the second time, and for a new resonance at 337 keV that has been measured for the first time. This resonance, found to be significantly weaker than previous estimates, dominates the reaction rate at lower temperatures (T < 0.2 KG) and reduces the reaction rate in first star environments.« less

  7. Sensitivity of the η ( ′ ) → π 0 γ γ and η ′ → η γ γ decays to a sub-GeV leptophobic U ( 1 ) B boson

    Escribano, Rafel ; Gonzàlez-Solís, Sergi ; Royo, Emilio - Physical Review D

  8. Searching for a fifth force with atomic and nuclear clocks

    Brzeminski, Dawid ; Chacko, Zackaria ; Dev, Abhish ; ... - Physical Review D

  9. Comprehensive Analysis of the Neutrino Process in Core-collapsing Supernovae

    Ko, Heamin ; Jang, Dukjae ; Cheoun, Myung-Ki ; ... - The Astrophysical Journal
    We investigate the neutrino flavor change effects due to neutrino self-interaction and shock wave propagation, as well as the matter effects on the neutrino process in core-collapsing supernovae (CCSNe). For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamics model for SN1987A. For the presupernova model, we take an updated model, adjusted to explain SN1987A, which employs recent developments in the (n, γ) reaction rates for nuclei near the stability line (A ~ 100). As for the neutrino luminosity, we adopt two different models: equivalent neutrino luminosity and nonequivalent luminosity models. The latter ismore » taken from a synthetic analysis of CCSN simulation data, which quantitatively presented the results obtained by various neutrino transport models. Relevant neutrino-induced reaction rates are calculated using a shell model for light nuclei and a quasiparticle random phase approximation model for heavy nuclei. For each model, we present abundances of the light nuclei (7Li, 7Be, 11B, and 11C) and the heavy nuclei (92Nb, 98Tc, 138La, and 180Ta) produced by the neutrino process. The light nuclei abundances turn out to be sensitive to the Mikheyev–Smirnov–Wolfenstein (MSW) region around O-Ne-Mg layer while the heavy nuclei are mainly produced prior to the MSW region. Through detailed analyses, we find that neutrino self-interaction becomes a key ingredient, in addition to the MSW effect, for understanding the neutrino process and the relevant nuclear abundances. The normal mass hierarchy is shown to be more compatible with the meteorite data. The main nuclear reactions for each nucleus are also investigated in detail.« less

  10. $$$$\alpha $$$$-event characterization and rejection in point-contact HPGe detectors

    Arnquist, I. J. ; Avignone, III, F. T. ; Barabash, A. S. ; ... - European Physical Journal. C, Particles and Fields
    Abstract P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We have characterized a PPC detector’s response to $$$$\alpha $$$$ α particles incident on the sensitive passivated and p $$^+$$ + surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the Majorana Demonstrator experiment, a search for neutrinoless double-beta decay ( $$$$0\nu \beta \beta $$$$ 0 ν β β ) in $$$$^{76}$$$$ more » 76 Ge. $$$$\alpha $$$$ α decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of $$$$\alpha $$$$ α identification, reliably identifying $$$$\alpha $$$$ α background events on the passivated surface of the detector. We demonstrate effective rejection of all surface $$$$\alpha $$$$ α events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the $$$$0\nu \beta \beta $$$$ 0 ν β β region of interest window by an order of magnitude in the Majorana Demonstrator   and will be used in the upcoming LEGEND-200 experiment.« less
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