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| Issue 10, 2026 |
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Extracts from the Internet | ||
Possible detection of a dark matter particle1 October 2026The nature of dark matter remains one of the main enigmas in cosmology. Among possible candidates are weakly interacting massive particles (wimps) lacking in the Standard Model, but the attempts of their direct detection have not yet given convincing results. A search for wimp scattering by atomic nuclei with a recoil energy of nuclei of 5.4-270 keV took place in the LUX-ZEPLIN experiment carried out in the Sanford Underground Research Complex (USA), whereas it is only the range of ≤ 100 keV that was investigated earlier [1]. The inner chamber of the installation, located at a depth of 1.6 km, contains 7 tons of liquid xenon viewed by photomultipliers. The candidate events are identified by direct scintillation radiation from the point of scattering and by a delayed electroluminescent signal from the emitted electrons. Registered in the data obtained for 220 h was one candidate event with a nucleus recoil energy of 248 ± 23 (stat.) ± 23 (syst.) keV, corresponding to the dark matter particle mass of ≥ 200 GeV. According to the test of all hypotheses, the statistical significance of this result was 2.6 σ and reaches 3.4 σ for one hypothesis (local significance). This potentially interesting event is most likely unrelated to background processes, and the wimp-nucleus interaction is now its only explanation. However, a singular event is insufficient for reliable conclusions, and further research is needed. [1] Akerib D S et al., arXiv:2609.02823 [hep-ex] Quantum phase in a gravitational field1 October 2026Using the equivalence principle, one can show that the wave function of a particle at rest in a gravitational field acquires an additional phase shift compared to the case of a freely falling particle. This phase shift was directly measured for the first time [2] in an experiment conducted at Ben-Gurion University of the Negev (Israel) with the participation of the Nobel laureate R Penrose. The phases of 87Rb atoms, stationary relative to the Earth and captured in a magnetic trap were compared with those of atoms that were thrown upward by a magnetic gradient pulse, were falling freely for some time, and after magnetic deceleration interfered with the immobile atoms. The motion of ultracold atoms was controlled through their transfer to a superposition of spin states that interact differently with the magnetic field. The authors of the experiment propose calling the new interferometer built on this principle “Quantum Galileo interferometer” in honor of G Galileo, who studied the free fall of bodies. The theoretically calculated value of the additional phase shift was confirmed with an accuracy of 2.5 % achieved in the experiment. This result is important for research into the problem of quantum gravity. [2] Dobkowski O et al. Science Advances 12 eaec8045 (2026) The influence of quantum fluctuations in a resonator on superconductivity1 October 2026One of the areas in the research of superconductivity is the study of the effect of zero quantum fluctuations of an electromagnetic field in resonators on the critical temperature Tc of superconducting transition due to changes in the electron-phonon coupling and other effects. H Zhang (the Center for Quantum Technologies, Singapore) and their co-authors discovered an increase in Tc in a layered NbSe2 sample in a resonator and investigated the dependence of the magnitude of the effect on the number of layers [3]. NbSe2 samples were placed in a resonator with a split ring. For a resonance frequency of 0.92 THz, the value of Tc in a two-layer material increases by ≈ 10 %, whereas in an identically prepared ten-layer material the shift is much smaller. The enhancement was observed within a single device, which made it possible to exclude the factor of sample differences. An increase of Tc in a multilayer NbSe2 sample in a cavity was independently discovered in [4], where a theoretical model was also proposed that explained the shift of Tc in the framework of the Ginzburg-Landau theory. According to this model, a superconductor exchanges virtual photons with the resonator, causing a resonant enhancement of superconductivity. [3] Zhang H et al., arXiv:2606.19171 [cond-mat.supr-con] [4] Wang Z et al. Nature 657 912 (2026) Observation of single vortices in a superconducting cavity1 October 2026The existence of quantum vortices in type II superconductors exposed to an external magnetic field was predicted by A A Abrikosov in 1957 within the framework of the Ginzburg-Landau theory [5]. The study of vortices and the search for ways to control their behavior are important for applications in superconducting quantum electronics. In their experiment, K Shulga (University of Tokyo, Japan) and their co-authors demonstrated a new method for recording individual vortices [6]. A flat superconducting resonator was made of niobium film on a silicon substrate. The part of the superconductor entering the cavity had a cone-shaped narrowing through which moving vortices penetrated into the resonator one by one. Each vortex emergence in the resonator was accompanied by a jump of the resonance frequency and quality factor. These changes affected the microwave radiation in the cavity, allowing the detection of individual vortices. Incoming single vortices were also independently recorded by a magnetometer on the basis of a nitrogen vacancy in diamond (NV center). [5] Abrikosov A A UFN 174 1234 (2004) [6] Shulga K et al. Phys. Rev. Lett. 137 116001 (2026) Birefringence in polarized X-ray emission from magnetars1 October 2026Magnetars are a class of isolated neutron stars with magnetic fields of ≈ 1014−1015 Gs. They are considered to be promising objects for investigation of nonlinear effects in quantum electrodynamics. One f these effects is birefringence in vacuum, when the vacuum refractive index for waves with different polarization is different. Birefringence is a direct consequence of quantum vacuum polarization (production of virtual e+e− pairs), but it has not been revealed earlier. The effects of radiation polarization in a magnetized plasma were considered by V L Ginzburg and his co-authors [7, 8], and in the quantum case their theory was developed by Yu N Gnedin and G G Pavlov [9, 10]. Vacuum polarization was expected to affect the propagation of soft X-ray radiation photons in magnetar magnetospheres. On the basis of observations by IXPE, NICER, and Parkes/Murriyang telescopes, R E Stewart (George Washington University, USA) and his co-authors investigated the magnetar 1E 1547.0-5408 with a rotation period of 2.09 and the magnetic field of ≈ 2,2 × 1014 Gs [11]. The magnetic axis of the neutron star almost coincides with the rotation axis, and a terrestrial observer views the object from the side of the pole. Due to these features, 1E 1547.0-5408 is well suited for searching for vacuum birefringence. A strong polarization of X-ray radiation was discovered, reaching 65 ± 8 % at 2 keV and correlating with the magnetic field in direction. These properties are naturally explained in the model with vacuum polarization and birefringence [12]. This was the first direct confirmation of birefringence in a magnetic field. For neutron stars possessing strong magnetic fields, see review [13]. [7] Gershman B N, Ginzburg V L, Denisov N G UFN 61 561 (1957) [8] Ginzburg V L, The propagation of electromagnetic waves in plasmas, Freeman and Co., New York 1970 [9] Gnedin Y N, Pavlov G G, Sov. Phys. JETP 38 903 (1974) [10] Pavlov G G, Gnedin Y N Astrophysics Space Physics Research 3 197 (1984). [11] Stewart R E Nature 656 590 (2026) [12] Markozov I D et al. Mon. Not. R. Astron. Soc. 551 stag1517 (2026) [13] Potekhin A Y Phys. Usp. 57 735 (2014) |
The Extracts from the Internet is a section of Uspekhi Fizicheskih Nauk (Physics Uspekhi) — the monthly rewiew journal of the current state of the most topical problems in physics and in associated fields. The presented News is devoted to the fundamental discoveries of physics and astrophysics. Permanent editor is Yu.N. Eroshenko. It is compiled from a multitude of Internet sources. | |
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