Primordial Black Holes from Sound Speed Resonance during Inflation

We report on a novel phenomenon of the resonance effect of primordial density perturbations arisen from a sound speed parameter with an oscillatory behavior, which can generically lead to the formation of primordial black holes in the early Universe. For a general inflaton field, it can seed primordial density fluctuations and their propagation is governed by a parameter of sound speed square. Once if this parameter achieves an oscillatory feature for a while during inflation, a significant non-perturbative resonance effect on the inflaton field fluctuations takes place around a critical length scale, which results in significant peaks in the primordial power spectrum. By virtue of this robust mechanism, primordial black holes with specific mass function can be produced with a sufficient abundance for dark matter in sizable parameter ranges.Comment: 6 pages, 4 figures; v2: figures replotted with corrections, analysis extended, version accepted by Phys.Rev.Let

Hint on new physics from the WW-boson mass excess−-axion-like particle, dark photon or Chameleon dark energy

The $W$-boson mass ($m_{W}=80.4335 \pm 0.0094 \mathrm{GeV}$) measured by the CDF collaboration is in excess of the standard model (SM) prediction at a confidence level of $7\sigma$, which is strongly in favor of the presence of new particles or fields. In the literature, various new particles and/or fields have been introduced to explain the astrophysical and experimental data and their presence in principle may also enhance the $W$-boson mass. Here we examine the models of axion-like particle (ALP), dark photon as well as Chameleon dark energy to see whether one of them can provide a solution of the $W$-boson mass excess. We find that the ALP interpretation is marginally consistent with the astrophysical constraints except for a mass of $\sim 1$ GeV. For the dark photon, the constraint on the $\xi$ parameter has been significantly narrowed down but no other astrophysical bounds are found available to further check this possibility. The possibility of attributing $W-$boson mass anomaly to the Chameleon dark energy has been ruled out by other experiments.Comment: 7 pages, 3 figures, submitte

Sound speed resonance of the stochastic gravitational wave background

We propose a novel mechanism to test time variation of the propagation speed of gravitational waves (GWs) in light of GWs astronomy. As the stochastic GWs experience the whole history of cosmic expansion, they encode potential observational evidence of such variation. We report that, one feature of a varying GWs speed is that the energy spectrum of GWs will present resonantly-enhanced peaks if the GWs speed oscillates in time at high-energy scales. Such oscillatory behaviour arises in a wide class of modified gravity theories. The amplitude of these peaks can be at reach by current and forthcoming GWs instruments, hence making the underlying theories falsifiable. This mechanism reveals that probing the variation of GWs speed can be a promising way to search for new physics beyond general relativity.Comment: 6 pages, 2 figure

(4-Bromo-2-{[2-(morpholin-4-yl)ethyl­imino]­meth­yl}phenolato)dioxido­vanadium(V)

In the title mononuclear dioxidovanadium(V) complex, [V(C13H16BrN2O2)O2], the VV atom is five-coordinated by one phenolate O, one imine N and one morpholine N atom of the Schiff base ligand, and by two oxide O atoms, forming a distorted square-pyramidal geometry. In the crystal, weak C—H⋯O inter­actions and a short Br⋯Br contact [3.4597 (12) Å] are observed

EUCLIA - Exploring the UV/optical continuum lag in active galactic nuclei. I. a model without light echoing

The tight inter-band correlation and the lag-wavelength relation among UV/optical continua of active galactic nuclei have been firmly established. They are usually understood within the widespread reprocessing scenario, however, the implied inter-band lags are generally too small. Furthermore, it is challenged by new evidences, such as the X-ray reprocessing yields too much high frequency UV/optical variations as well as it fails to reproduce the observed timescale-dependent color variations among {\it Swift} lightcurves of NGC 5548. In a different manner, we demonstrate that an upgraded inhomogeneous accretion disk model, whose local {\it independent} temperature fluctuations are subject to a speculated {\it common} large-scale temperature fluctuation, can intrinsically generate the tight inter-band correlation and lag across UV/optical, and be in nice agreement with several observational properties of NGC 5548, including the timescale-dependent color variation. The emergent lag is a result of the {\it differential regression capability} of local temperature fluctuations when responding to the large-scale fluctuation. An average speed of propagations as large as $\gtrsim 15\%$ of the speed of light may be required by this common fluctuation. Several potential physical mechanisms for such propagations are discussed. Our interesting phenomenological scenario may shed new light on comprehending the UV/optical continuum variations of active galactic nuclei.Comment: 18 pages, 8 figures. ApJ accepted. Further comments are very welcome

Prompt Pool based Class-Incremental Continual Learning for Dialog State Tracking

Continual learning is crucial for dialog state tracking (DST) in dialog systems, since requirements from users for new functionalities are often encountered. However, most of existing continual learning methods for DST require task identities during testing, which is a severe limit in real-world applications. In this paper, we aim to address continual learning of DST in the class-incremental scenario (namely the task identity is unknown in testing). Inspired by the recently emerging prompt tuning method that performs well on dialog systems, we propose to use the prompt pool method, where we maintain a pool of key-value paired prompts and select prompts from the pool according to the distance between the dialog history and the prompt keys. The proposed method can automatically identify tasks and select appropriate prompts during testing. We conduct experiments on Schema-Guided Dialog dataset (SGD) and another dataset collected from a real-world dialog application. Experiment results show that the prompt pool method achieves much higher joint goal accuracy than the baseline. After combining with a rehearsal buffer, the model performance can be further improved

An intrinsic link between long-term UV/optical variations and X-ray loudness in quasars

Observations have shown that UV/optical variation amplitude of quasars depend on several physi- cal parameters including luminosity, Eddington ratio, and likely also black hole mass. Identifying new factors which correlate with the variation is essential to probe the underlying physical processes. Combining ~ten years long quasar light curves from SDSS stripe 82 and X-ray data from Stripe 82X, we build a sample of X-ray detected quasars to investigate the relation between UV/optical variation amplitude ($\sigma_{rms}$) and X-ray loudness. We find that quasars with more intense X-ray radiation (com- pared to bolometric luminosity) are more variable in UV/optical. Such correlation remains highly significant after excluding the effect of other parameters including luminosity, black hole mass, Ed- dington ratio, redshift, rest-frame wavelength (i.e., through partial correlation analyses). We further find the intrinsic link between X-ray loudness and UV/optical variation is gradually more prominent on longer timescales (up to 10 years in the observed frame), but tends to disappear at timescales < 100 days. This suggests a slow and long-term underlying physical process. The X-ray reprocessing paradigm, in which UV/optical variation is produced by a variable central X-ray emission illuminating the accretion disk, is thus disfavored. The discovery points to an interesting scheme that both the X-ray corona heating and UV/optical variation is quasars are closely associated with magnetic disc turbulence, and the innermost disc turbulence (where corona heating occurs) correlates with the slow turbulence at larger radii (where UV/optical emission is produced).Comment: 9 pages, 4 figures, 1 table, accepted by Ap

Aqua­[2-(3-carb­oxy-5-carboxyl­atophen­oxy)acetato-κO 1]bis­(1,10-phenanthroline-κ2 N,N′)manganese(II) dihydrate

In the title complex, [Mn(C10H6O7)(C12H8N2)2(H2O)]·2H2O, the MnII atom is coordinated by two O atoms from one 2-(3-carb­oxy-5-carboxyl­atophen­oxy)acetate (HOABDC2−) dianion and one water mol­ecule and by four N atoms from two 1,10-phenanthroline (phen) ligands within a distorted octa­hedral geometry. O—H⋯O hydrogen bonding between –COOH and –COO− groups of adjacent mol­ecules and between carboxyl­ate groups and coordinated and uncoordin­ated water mol­ecules leads to a three-dimensional structure which is further stabilized by weak π–π inter­actions of adjacent phen ligands with centroid–centroid separations of 4.2932 (1) Å