| |
Ramirez Alfaro, J., Moreno Llacer, M., & Vos, M. (2026). The bottom quark mass at high scale. Eur. Phys. J. Plus, 141(8), 969–5pp.
Abstract: A measurement of the MS & strns; bottom quark mass at the renormalization scale of the Higgs boson mass can be extracted from measurements of Higgs boson decay rates at the LHC. Using the latest ATLAS results, we extract mb(mH)=2.38-0.21+0.24GeV , reaching a precision of 9.5%. This measurement could be further improved at the HL-LHC and future colliders, with potential to become the most precise measurement of mb at any scale. Together with measurements at other energy scales and the predicted mb scale evolution from QCD, mb(mH) demonstrates the “running” of the bottom quark mass.
|
|
Sesana, A., & Figueroa, D. G. (2026). Nanohertz Gravitational Waves. Annu. Rev. Astron. Astrophys., 64(1), 537–586.
Abstract: Evidence of a gravitational wave (GW) signal has emerged in pulsar timing array (PTA) data, opening a new window into the nanohertz GW Universe. We explore the physics of GW signals that may explain the data, with a focus on GW backgrounds (GWBs) considering both astrophysical and cosmological origins. We describe how: An astrophysical nanohertz GWB emerges as the superposition of individual signals from inspiraling massive black hole binaries. Environment coupling, eccentricity, and sparse sampling cause great uncertainty in the theoretical prediction of the supermassive black hole signal but also offer a way to determine the origin of the signal. PTA data offer unprecedented opportunities to constrain high-energy physics beyond the Standard Model by probing early Universe GWBs that originated during or after inflation. Different early Universe GWBs, typically created by nonlinear and out-of-equilibrium dynamics, can explain the PTA data (e.g., those from inflation scenarios, first-order phase transitions, or topological defects). The PTA detection of GWs opens a new window to explore the Universe, with profound implications for astrophysics and particle physics (probing, e.g., the equation of state of the early Universe, the origin of cosmological perturbations, the nature of dark matter, or whether exotic objects like primordial black holes or cosmic strings exist).
|
|
Alkofer, R., Ferreira, M. N., Miramontes, A. S., Morgado, J. M., & Papavassiliou, J. (2026). Real poles with opposite-sign residues in the non-perturbative quark propagator. Phys. Lett. B, 880, 140856–10pp.
Abstract: We investigate the analytic structure of the quark propagator in the Landau gauge by dynamically coupling the standard gap equation to the non-perturbative quark-gluon vertex. Employing the full vertex basis, we demonstrate that for sub-GeV time-like momenta, the proper inclusion of the underlying dynamics leads to a pair of real poles with opposite-sign residues. In particular, in stark contradistinction to the results obtained in widely used approximations, we see no sign of complex conjugate poles. This distinctive analytic structure evades conceptual shortcomings frequently associated with complex conjugate poles while remaining fully compatible with the aspects of color confinement related to positivity violation. Crucially, this novel behavior is governed by a dominant triplet of vertex form factors: the tree-level component, the anomalous chromomagnetic moment, and a component we label as “spin-momentum curvature”. By gradually tuning the individual strengths of these components, we demonstrate that while they contribute in distinct ways to the quark propagator, their joint action is vital for stabilizing the system. Together, they place the low-lying poles onto the real axis while producing a robust constituent quark mass of 350 MeV.
|
|
Torres-Sanchez, P., Babiano-Suarez, V., Correa, J. B., Gameiro, B., Lerendegui-Marco, J., Ladarescu, I., et al. (2026). First experimental demonstration of Compton imaging of 10B at clinical concentrations for real-time dosimetry in BNCT. Phys. Med. Biol., 71(16), 165030–17pp.
Abstract: Objective. Boron neutron capture therapy (BNCT) requires accurate knowledge of the boron distribution during treatment to enable reliable dosimetry and treatment verification. Compton imaging of the 478 keV prompt gamma rays emitted following neutron capture by 10B has been proposed as a promising technique for real-time boron monitoring. This work aims to experimentally evaluate the feasibility of Compton imaging under clinically relevant boron concentrations and realistic neutron-induced background conditions. Approach. A dedicated experimental campaign was performed at the Institut Laue-Langevin (ILL, Grenoble, France) using the i-TED Compton camera array. Three experimental configurations with progressively increasing neutron-induced background were investigated, including a water phantom containing 65 ppm 10B, representative of typical tumor concentrations during BNCT. Experimental measurements were complemented by detailed Geant4 Monte Carlo simulations to interpret detector performance, identify current limitations, and assess potential detector improvements. Main results. The experiments demonstrate, for the first time, Compton imaging of 10B at a clinically relevant concentration of 65 ppm under neutron irradiation. The reconstructed 478 keV gamma-ray emission was correctly localized with a spatial resolution of 22 mm (FWHM) and a signal-to-background ratio of 6.4. The study also identifies the principal limitations affecting detector performance, namely high count-rate effects and contamination from back-scattered Compton events. Dedicated analyses and simulations show that optimized event filtering substantially mitigates image degradation, while future detector developments based on pixelated scintillator arrays and improved timing capabilities are expected to significantly enhance performance under BNCT operating conditions. Significance. These results constitute the first experimental validation of Compton imaging for boron monitoring at clinically relevant concentrations and demonstrate the potential of the technique for real-time BNCT dosimetry. The identified detector improvements provide a technically grounded pathway towards clinical implementation of gamma-ray imaging-based dose monitoring in BNCT.
|
|
Barenboim, G., Ireland, A., & Stebbins, A. (2026). Constraints on Large-Scale White Noise in the Cosmic Density Field. Phys. Rev. Lett., 137(8), 081003–6pp.
Abstract: We present observational constraints on large-scale white noise (LSWN) in the cosmic density field, a phenomenon predicted to arise from nonlinear mode coupling during cosmological evolution. Building on the theoretical framework of our companion paper, where we demonstrated that nonlinearities inevitably redistribute power from small to large scales through mode mixing, we confront these predictions with current cosmological data. We modify the CLASS Boltzmann code to incorporate a white noise component kBH/k in the primordial power spectrum and perform parameter estimation using current cosmological data. The nondetection of excess power on the largest observable scales places stringent upper bounds: kBH <= 1.80 & times; 10-13 Mpc-1 at 99% confidence. These constraints imply the primordial power spectrum must deviate from a power law on small scales, perhaps with a sharp cutoff at kcut 0.03 pc-1 or through running of the spectral index with alpha s-0.019. Our results demonstrate that LSWN provides a powerful probe of the primordial spectrum at scales orders of magnitude smaller than those directly observable, offering unique constraints on early-universe physics.
|
|
|
