skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


This content will become publicly available on September 1, 2026

Title: Search for axionlike dark matter using liquid-state nuclear magnetic resonance
We search for dark matter in the form of axionlike particles (ALPs) in the mass range 5.576741 neV / c 2 5.577733 neV / 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 ap 3 × 10 2 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 peV / c 2 to 17    neV / c 2 with hyperpolarized samples to boost the sensitivity beyond the astronomical limits.  more » « less
Award ID(s):
2110388
PAR ID:
10652417
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
American Physical Society
Date Published:
Journal Name:
Physical Review D
Volume:
112
Issue:
5
ISSN:
2470-0010
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. We present results of a search for spin-independent dark matter-nucleus interactions in a 1 cm 2 by 1 mm thick (0.233 g) high-resolution silicon athermal phonon detector operated above ground. For interactions in the substrate, this detector achieves an rms baseline energy resolution of 361.5 ( 4 ) m eV (statistical error), the best for any athermal phonon detector to date. With an exposure of 0.233 g × 12 hours, we place the most stringent constraints on dark matter masses between 44 and 87 M eV / c 2 , with the lowest unexplored cross section of 4 × 10 32 c m 2 at 87 M eV / c 2 . We employ a conservative salting technique to reach the lowest dark matter mass ever probed via direct detection experiment. This constraint is enabled by two-channel rejection of low energy backgrounds that are coupled to individual sensors. 
    more » « less
  2. DMRadio- m 3 is an experimental search for dark matter axions. It uses a solenoidal dc magnetic field to convert an axion dark-matter signal to an ac electromagnetic response in a coaxial copper pickup. The current induced by this axion signal is measured by dc SQUIDs. DMRadio- m 3 is designed to be sensitive to Kim-Shifman-Vainshtein-Zakharov (KSVZ) and Dine-Fischler-Srednicki-Zhitnisky (DFSZ) QCD axion models in the 10–200 MHz ( 41 neV / c 2 0.83 μ eV / c 2 ) range, and to axions with g a γ γ = g a γ γ , DFSZ ( 30 MHz ) = 1.87 × 10 17 GeV 1 over 5–30 MHz as an extended goal. In this work, we present the electromagnetic modeling of the response of the experiment to an axion signal over the full frequency range of DMRadio- m 3 , which extends from the low-frequency, lumped-element limit to a regime where the axion Compton wavelength is only a factor of 2 larger than the detector size. With these results, we determine the live time and sensitivity of the experiment. The primary science goal of sensitivity to DFSZ axions across 30–200 MHz can be achieved with a 3 σ live scan time of 2.9 years. 
    more » « less
  3. The Ξ b 0 ( ) Ξ c ( 3055 ) + ( 0 ) ( D + ( 0 ) Λ ) π decay chains are observed, and the spin-parity of Ξ c ( 3055 ) + ( 0 ) baryons is determined for the first time. The measurement is performed using proton-proton collision data at a center-of-mass energy of s = 13 TeV , corresponding to an integrated luminosity of 5.4 fb 1 , recorded by the LHCb experiment between 2016 and 2018. The spin-parity of the Ξ c ( 3055 ) + ( 0 ) baryons is determined to be 3 / 2 + with a significance of more than 6.5 σ ( 3.5 σ ) compared to all other tested hypotheses. The up-down asymmetries of the Ξ b 0 ( ) Ξ c ( 3055 ) + ( 0 ) π transitions are measured to be 0.92 ± 0.10 ± 0.05 ( 0.92 ± 0.16 ± 0.22 ), consistent with maximal parity violation, where the first uncertainty is statistical and the second is systematic. These results support the hypothesis that the Ξ c ( 3055 ) + ( 0 ) baryons correspond to the first D -wave λ -mode excitation of the Ξ c flavor triplet. © 2025 CERN, for the LHCb Collaboration2025CERN 
    more » « less
  4. The production yields of the orbitally excited charm-strange mesons D s 1 ( 1 + ) ( 2536 ) + and D s 2 * ( 2 + ) ( 2573 ) + were measured for the first time in proton-proton (pp) collisions at a center-of-mass energy of s = 13 TeV with the ALICE experiment at the LHC. The D s 1 + and D s 2 * + mesons were measured at midrapidity ( | y | < 0.5 ) in minimum-bias and high-multiplicity pp collisions in the transverse-momentum interval 2 < p T < 24 GeV / c . Their production yields relative to the D s + ground-state yield were found to be compatible between minimum-bias and high-multiplicity collisions, as well as with previous measurements in e ± p and e + e collisions. The measured D s 1 + / D s + and D s 2 * + / D s + yield ratios are described by statistical hadronization models and can be used to tune the parameters governing the production of excited charm-strange hadrons in Monte Carlo generators, such as 8. 
    more » « less
  5. The polarization of the Λ and Λ ¯ hyperons along the beam direction has been measured in proton-lead ( p -Pb ) collisions at a center-of-mass energy per nucleon pair of 8.16 TeV. The data were obtained with the CMS detector at the LHC and correspond to an integrated luminosity of 186.0 ± 6.5 nb 1 . A significant azimuthal dependence of the hyperon polarization, characterized by the second-order Fourier sine coefficient P z , s 2 , is observed. The P z , s 2 values decrease as a function of charged particle multiplicity, but increase with transverse momentum. A hydrodynamic model that describes the observed P z , s 2 values in nucleus-nucleus collisions by introducing vorticity effects does not reproduce either the sign or the magnitude of the p -Pb results. These observations pose a challenge to the current theoretical implementation of spin polarization in heavy ion collisions and offer new insights into the origin of spin polarization in hadronic collisions at LHC energies. 
    more » « less