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1. Leptogenesis during an era of early SU(2) confinement

   https://doi.org/10.1103/nmpt-fwz6  

   Bhalla-Ladd, India; Ginnett, Izzy; Tait, Tim_M P (October 2025, Physical Review D)

   We explore leptogenesis during a cosmological epoch during which the electroweak $\mathrm{SU}(2{)}_L$force is confined. During weak confinement, there is only one conserved nonanomalous global charge, $r$, which is a linear combination of lepton-number, baryon-number, and hypercharge. The inclusion of heavy Majorana neutrinos leads to an $r$-charge and $CP$-violating interaction with a composite scalar, $\mathrm{\Phi }$, and composite fermions, $\mathrm{\Psi }$, allowing for the generation of an $r$-charge asymmetry, which translates into a baryon asymmetry post $\mathrm{SU}(2{)}_L$deconfinement. Determining the resulting baryon asymmetry as a function of the model parameters, we find that the predicted baryon-asymmetry can match observations for a wide swath of parameter space: a weak confinement scale ${\mathrm{\Lambda }}_W\sim {10}^{11}–{10}^{14}\mathrm{GeV}$, the sum of the Standard Model Yukawa couplings $\sum Y_{i\alpha }{Y}_{i\alpha }^{*}\sim {10}^{-2}-{10}^0$, $m_{\mathrm{\Phi }}/m_{\mathrm{\Psi }}\sim 0-0.5$, and a $\mathrm{\Phi }-\mathrm{\Psi }-\mathrm{\Psi }$coupling $\left|g\right|\sim 1$with complex phase ${\theta }_g\sim \pi /4$. While leptogenesis under the assumption of a standard cosmology relies on the complex phase of the neutrino Yukawa couplings, the asymmetry generated in this novel background cosmology primarily depends on a strong phase from $\mathrm{SU}(2{)}_L$confinement, ${\theta }_g$, and favors negligible $CP$-violation in the right-handed neutrino decays. 

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2. Resonant conversion of axion dark radiation into terahertz electromagnetic radiation in a neutron star magnetosphere

   https://doi.org/10.1103/PhysRevD.110.103020  

   Long, Andrew J; Schiappacasse, Enrico D (November 2024, Physical Review D)

   In the strong magnetic field of a neutron star’s magnetosphere, axions coupled to electromagnetism develop a nonzero probability to convert into photons. Past studies have revealed that the axion-photon conversion can be resonantly enhanced. We recognize that the axion-photon resonance admits two parametrically distinct resonant solutions, which we call the mass-matched resonance and the Euler-Heisenberg assisted resonance. The mass-matched resonance occurs at a point in the magnetosphere where the radially-varying plasma frequency crosses the axion mass ${\omega }_{\mathrm{pl}}\approx m_a$. The Euler-Heisenberg assisted resonance occurs where the axion energy satisfies $\omega \approx (2{\omega }_{\mathrm{pl}}^2/7g_{\gamma \gamma \gamma \gamma }{\overline{B}}^2{)}^{1/2}$. This second resonance is made possible though the strong background magnetic field $\overline{B}$, as well as the nonzero Euler-Heisenberg four-photon self-interaction, which has the coupling $g_{\gamma \gamma \gamma \gamma }=8{\alpha }^2/45m_e^4$. We study the resonant conversion of relativistic axion dark radiation into photons via the Euler-Heisenberg assisted resonance, and we calculate the expected electromagnetic radiation assuming different values for the axion-photon coupling $g_{a\gamma \gamma }$and different amplitudes for the axion flux onto the neutron star ${\mathrm{\Phi }}_a$. We briefly discuss several possible sources of axion dark radiation. Achieving a sufficiently strong axion flux to induce a detectable electromagnetic signal seems unlikely. Published by the American Physical Society2024 

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3. Bayesian Search of Massive Scalar Fields from LIGO-Virgo-KAGRA Binaries

   https://doi.org/10.1103/PhysRevLett.134.191402  

   Xie, Yiqi; Chung, Adrian Ka-Wai; Sotiriou, Thomas P; Yunes, Nicolás (May 2025, Physical Review Letters)

   Massive scalar fields are promising candidates for addressing many unresolved problems in fundamental physics. We report the first model-agnostic Bayesian search of massive scalar fields that are nonminimally coupled to gravity in LIGO/Virgo/KAGRA gravitational-wave data. We find no evidence for such fields and place the most stringent upper limits on their coupling for scalar masses $\lesssim 2\times {10}^{-12}\mathrm{eV}$. We exemplify the strength of these bounds by applying them to massive scalar-Gauss-Bonnet gravity, finding the tightest constraints on the coupling constant to date, $\sqrt{{\alpha }_{\mathrm{GB}}}\lesssim 1\mathrm{km}$for scalar masses $\lesssim {10}^{-13}\mathrm{eV}$to 90% credible level. Published by the American Physical Society2025 

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4. Search for axionlike dark matter using liquid-state nuclear magnetic resonance

   https://doi.org/10.1103/39nc-vr9m  

   Walter, Julian; Maliaka, Olympia; Zhang, Yuzhe; Blanchard, John W; Centers, Gary; Dogan, Arian; Engler, Martin; Figueroa, Nataniel L; Kim, Younggeun; Kimball, Derek_F Jackson; et al (September 2025, Physical Review D)

   We search for dark matter in the form of axionlike particles (ALPs) in the mass range $5.576741\mathrm{neV}/{\mathrm{c}}^2-5.577733\mathrm{neV}/{\mathrm{c}}^2$by probing their possible coupling to fermion spins through the ALP field gradient. This is achieved by performing proton nuclear magnetic resonance spectroscopy on a sample of methanol as a technical demonstration of the Cosmic Axion Spin Precession Experiment Gradient (CASPEr-Gradient) Low-Field apparatus. Searching for spin-coupled ALP dark matter in this mass range with associated Compton frequencies in a 240 Hz window centered at 1.348570 MHZ resulted in a sensitivity to the ALP-proton coupling constant of $g_{\mathrm{ap}}\approx 3\times {10}^{-2}{\mathrm{GeV}}^{-1}$. This narrow-bandwidth search serves as a proof-of-principle and a commissioning measurement, validating our methodology and demonstrating the experiment’s capabilities. CASPEr-Gradient Low-Field will probe the mass range from $4.1\mathrm{peV}/{\mathrm{c}}^2$to $17\mathrm{neV}/{\mathrm{c}}^2$with hyperpolarized samples to boost the sensitivity beyond the astronomical limits. 

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5. Search for high-mass exclusive diphoton production with tagged protons in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevD.110.012010  

   Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Escalante_Del_Valle, A; Hussain, P S; Jeitler, M; et al (July 2024, Physical Review D)

   A search is presented for high-mass exclusive diphoton production via photon-photon fusion in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$in events where both protons survive the interaction. The analysis utilizes data corresponding to an integrated luminosity of $103{\mathrm{fb}}^{-1}$collected in 2016–2018 with the central CMS detector and the CMS and TOTEM precision proton spectrometer (PPS). Events that have two photons with high transverse momenta ( $p_{\mathrm{T}}^{\gamma }>100\mathrm{GeV}$), back-to-back in azimuth, and with a large diphoton invariant mass ( $m_{\gamma \gamma }>350\mathrm{GeV}$) are selected. To remove the dominant inclusive diphoton backgrounds, the kinematic properties of the protons detected in PPS are required to match those of the central diphoton system. Only events having opposite-side forward protons detected with a fractional momentum loss between 0.035 and 0.15 (0.18) for the detectors on the negative (positive) side of CMS are considered. One exclusive diphoton candidate is observed for an expected background of 1.1 events. Limits at 95% confidence level are derived for the four-photon anomalous coupling parameters $\left|{\zeta }_1\right|<0.073{\mathrm{TeV}}^{-4}$and $\left|{\zeta }_2\right|<0.15{\mathrm{TeV}}^{-4}$, using an effective field theory. Additionally, upper limits are placed on the production of axionlike particles with coupling strength to photons $f^{-1}$that varies from $0.03{\mathrm{TeV}}^{-1}$to $1{\mathrm{TeV}}^{-1}$over the mass range from 500 to 2000 GeV. © 2024 CERN, for the CMS and TOTEMs Collaboration2024CERN 

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