The European Physical Journal C最新文献

Space-borne gravitational wave detectors like TianQin might encounter data gaps due to factors like micro-meteoroid collisions or hardware failures. Such events will cause discontinuity in the data, presenting challenges to the data analysis for TianQin, especially for massive black hole binary mergers. Since the signal-to-noise ratio (SNR) accumulates in a non-linear way, a gap near the merger could lead to a significant loss of SNR. It could introduce bias in the estimate of noise properties, and the results of the parameter estimation. In this work, using simulated TianQin data with injected a massive black hole binary merger, we study the window function method, and for the first time, the inpainting method to cope with the data gap, and an iterative estimate scheme is designed to properly estimate the noise spectrum. We find that both methods can properly estimate noise and signal parameters. The easy-to-implement window function method can already perform well, except that it will sacrifice some SNR due to the adoption of the window. The inpainting method is slower, but it can minimize the impact of the data gap.

Cryogenic calorimetric experiments to search for neutrinoless double-beta decay ((0nu beta beta )) are highly competitive, scalable and versatile in isotope. The largest planned detector array, CUPID, is comprised of about 1500 individual Li(_{2}) (^{100})MoO(_4) detector modules with a further scale up envisioned for a follow up experiment (CUPID-1T). In this article, we present a novel detector concept targeting this second stage with a low impedance TES based readout for the Li(_2)MoO(_4) absorber that is easily mass-produced and lends itself to a multiplexed readout. We present the detector design and results from a first prototype detector operated at the NEXUS shallow underground facility at Fermilab. The detector is a 2-cm-side cube with 21 g mass that is strongly thermally coupled to its readout chip to allow rise-times of (sim )0.5 ms. This design is more than one order of magnitude faster than present NTD based detectors and is hence expected to effectively mitigate backgrounds generated through the pile-up of two independent two neutrino decay events coinciding close in time. Together with a baseline resolution of 1.95 keV (FWHM) these performance parameters extrapolate to a background index from pile-up as low as (5cdot 10^{-6}) counts/keV/kg/yr in CUPID size crystals. The detector was calibrated up to the MeV region showing sufficient dynamic range for (0nu beta beta ) searches. In combination with a SuperCDMS HVeV detector this setup also allowed us to perform a precision measurement of the scintillation time constants of Li(_2)MoO(_4), which showed a primary component with a fast O(20 (upmu )s) time scale.

We investigate the thermodynamics of a Schwarzschild black hole, surrounded by the quintessence energy-matter in the linear and quadratic generalized uncertainty principle framework. Considering the variance in the position to be of the order of the event horizon radius and equating the variance in the momentum to the Hawking temperature of the black hole, we substitute these variances in the deformed algebra. From there we obtained the generalized uncertainty principle-modified black hole temperature and eventually the specific heat of the black hole. Then we calculate the critical as well as the remnant mass and obtain the entropy relation. We observe that the entropy relation includes the usual leading order “area divided by four” term, sub-leading logarithmic term, and higher order inverse of the area corrections. Finally, calculating the energy output as a function of time, we obtain the evaporation time of the black hole. The results show the dependence of the quintessence parameter on the thermodynamic quantities in the framework of linear and quadratic generalized uncertainty principle.

Double beta plus decay is a rare nuclear disintegration process. Difficulties in its measurement arise from suppressed decay probabilities, experimentally challenging decay signatures and low natural abundances of suitable candidate nuclei. In this article, we propose a new detector concept to overcome these challenges. It is based on the first-time combination of hybrid and opaque scintillation detector technology paired with novel light read-out techniques. This approach is particularly suitable for detecting positrons (beta plus) signatures. We expect to discover two-neutrino double beta plus decay modes within 1 tonne-week exposure and are able to probe neutrinoless double beta plus decays at several orders of magnitude improved significance compared to current experimental limits.

We present evidence for new phases of the Standard Model Higgs potential. We study the Standard Model physical trajectory accounting for the Higgs curvature mass with the mass-dependent functional renormalisation group. New unstable and non-trivially stable phases are found at energies above the Planck scale and below the Abelian Landau pole. While the first aggravates the well-known metastable phase and threatens the viability of the Standard Model extrapolated to arbitrary scales, the latter can provide a well-defined ultraviolet completion. We investigate the phase diagram as a function of the top quark pole mass and study the effect of new physics through a scalar singlet portal coupling. The new non-trivial phase appears below the Planck scale in extensions of the Standard Model seeking stable trajectories. These findings have a significant impact on existing model building.

We continue the study of dipole cosmology framework put forward in Krishnan et al. (JCAP 07:020, 2023), a beyond FLRW setting that has a preferred direction in the metric which may be associated with a cosmological tilt, a cosmic dipole. In this setup the shear and the tilt can be positive or negative given the dipole direction. We thoroughly analyze evolution of the universe in this setting, particularly focusing on the behaviour near the Big Bang (BB). We first analyze a single fluid model with a generic constant equation of state w. While details of the behavior near the BB depends on w and the other initial conditions, we find that when the shear is negative we have a shear dominated BB singularity, whereas for a positive shear we have a much milder singularity, the whimper singularity (Ellis and King in Commun Math Phys 38:119–156, 1974), at which the tilt blows up while curvature invariants remain finite. We then consider dipole (Lambda )CDM model which besides the shear has two tilt parameters, one for radiation and one for the pressureless matter. For positive (negative) shear we again find whimper (curvature) singularity near the BB. Moreover, when the tilt parameters have opposite signs, the shear can change sign from negative to positive in the course of evolution of the Universe. We show that the relative tilt of the radiation and the matter generically remains sizable at late times.

We extend the construction of Alcubierre–Natário class of warp drives to an infinite class of spacetimes with similar properties. This is achieved by utilising the Martel–Poisson charts which closely resembles the Weak Painlevé–Gullstrand form for various background metrics (Mink, AdS, dS). The highlight of this construction is the non-flat intrinsic metric which in three dimensional spacetimes introduce conical singularities at the origin and in higher dimensions generates non-zero Ricci scalar for the spatial hypersurfaces away from the origin. We analyse the expansion/contraction of space and the (NEC) violations associated with these warp drives and find interesting scalings due to the global imprints of the conical defects. Other properties like tilting of light cones, event horizons and several generalisations are also discussed.

We study the time dependence of the generalized complexity of Lovelock black holes using the “complexity = anything” conjecture, which expands upon the notion of “complexity = volume” and generates a large class of observables. By applying a specific condition, a more limited class can be chosen, whose time growth is equivalent to a conserved momentum. Specifically, we investigate the numerical full time behavior of complexity time rate, focusing on the second and third orders of Lovelock theory coupled with Maxwell term, incorporating an additional term – the square of the Weyl tensor of the background spacetime – into the generalization function. Furthermore, we repeat the analysis for case with three additional scalar terms: the square of Riemann and Ricci tensors, and the Ricci scalar for second-order gravity (Gauss–Bonnet) showing how these terms can affect to multiple asymptotic behavior of time. We study how the phase transition of generalized complexity and its time evolution occur at turning point ((tau _{turning})) where the maximal generalized volume supersedes another branch. Additionally, we discuss the late time behavior, focusing on proportionality of the complexity time rate to the difference of temperature times entropy at the two horizons ((TS(r_+)-TS(r_-))) for charged black holes, which can be corrected by generalization function of each radius in generalized case. In this limit, we also explore near singularity structure by approximating spacetime to Kasner metrics and finding possible values of complexity growth rate with different choices of the generalization function.

In this paper, we study four-body systems and consider them as diquark–antidiquark. We use the Bethe–Salpeter equation (Schrödinger equation with relativistic kinematics) to calculate the binding energies and the mass of heavy tetraquarks with hidden charm and bottom structures. To solve the Bethe–Salpeter equation, we use the Hellmann potential and the Ansatz method and calculate the mass of tetraquarks X(3.872),  Y(3.940),  (Z_{cs}(3.985),) X(4.140),  (Z_{b}(10.610),) and (Z_{b}(10.650).) Our results are in good agreement with theoretical and experimental data.

Integrating out supersymmetric M2 branes wrapped on two-cycles in Calabi–Yau manifolds is an important calculation: it allows the determination of, and in some ways defines, the free energy of topological strings. In these notes, based on a short course aimed at graduate students, we go through various aspects of this calculation in detail. The end result is a recently proposed new formula for the topological string free energy.