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This Letter reports the first measurement of the oscillation amplitude and frequency of reactor antineutrinos at Daya Bay via neutron capture on hydrogen using 1958 days of data. With over 3.6 million signal candidates, an optimized candidate selection, improved treatment of backgrounds and efficiencies, refined energy calibration, and an energy response model for the capture-on-hydrogen sensitive region, the relative $\overline{\nu}_{e}$ rates and energy spectra variation among the near and far detectors gives $\mathrm{sin}^22\theta_{13} = 0.0759_{-0.0049}^{+0.0050}$ and $\Delta m^2_{32} = (2.72^{+0.14}_{-0.15})\times10^{-3}$ eV$^2$ assuming the normal neutrino mass ordering, and $\Delta m^2_{32} = (-2.83^{+0.15}_{-0.14})\times10^{-3}$ eV$^2$ for the inverted neutrino mass ordering. This estimate of $\sin^2 2\theta_{13}$ is consistent with and essentially independent from the one obtained using the capture-on-gadolinium sample at Daya Bay. The combination of these two results yields $\mathrm{sin}^22\theta_{13}= 0.0833\pm0.0022$, which represents an 8% relative improvement in precision regarding the Daya Bay full 3158-day capture-on-gadolinium result.

In the field of rare event physics, it is common to have huge masses of organic liquid scintillator as detection medium. In particular, they are widely used to study neutrino properties or astrophysical neutrinos. Thanks to its safety properties (such as low toxicity and high flash point) and easy scalability, linear alkyl benzene is the most common solvent used to produce liquid scintillators for large mass experiments. The knowledge of the refractive index is a pivotal point to understand the detector response, as this quantity (and its wavelength dependence) affects the Cherenkov radiation and photon propagation in the medium. In this paper, we report the measurement of the refractive index of the JUNO liquid scintillator between 260-1064 nm performed with two different methods (an ellipsometer and a refractometer), with a sub percent level precision. In addition, we used an interferometer to measure the group velocity in the JUNO liquid scintillator and verify the expected value derived from the refractive index measurements., Comment: 6 pages, 9 figures

This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158 days of detector operation, which contains $5.55 \times 10^{6}$ reactor \anue candidates identified as inverse beta-decay interactions followed by neutron-capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties. No significant oscillation due to mixing of a sub-eV sterile neutrino with active neutrinos was found. Exclusion limits are set by both Feldman-Cousins and CLs methods. Light sterile neutrino mixing with $\sin^2 2\theta_{14} \gtrsim 0.01$ can be excluded at 95\% confidence level in the region of $0.01$ eV$^2 \lesssim |\Delta m^{2}_{41}| \lesssim 0.1 $ eV$^2$. This result represents the world-leading constraints in the region of $2 \times 10^{-4}$ eV$^2 \lesssim |\Delta m^{2}_{41}| \lesssim 0.2 $ eV$^2$., Comment: 7 pages, 4 figures, 1 table

Daya Bay presents the first measurement of cosmogenic $^8$He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of $^8$He and its child isotope, $^8$Li. We also measure the production yield of $^9$Li isotopes using well-established methodology. The results, in units of 10$^{-8}\mu^{-1}$g$^{-1}$cm$^{2}$, are 0.307$\pm$0.042, 0.341$\pm$0.040, and 0.546$\pm$0.076 for $^8$He, and 6.73$\pm$0.73, 6.75$\pm$0.70, and 13.74$\pm$0.82 for $^9$Li at average muon energies of 63.9~GeV, 64.7~GeV, and 143.0~GeV, respectively. The measured production rate of $^8$He isotopes is more than an order of magnitude lower than any other measurement of cosmogenic isotope production. It replaces the results of previous attempts to determine the ratio of $^8$He to $^9$Li production that yielded a wide range of limits from 0 to 30\%. The results provide future liquid-scintillator-based experiments with improved ability to predict cosmogenic backgrounds.

The full data set of the Daya Bay reactor neutrino experiment is used to probe the effect of the charged current non-standard interactions (CC-NSI) on neutrino oscillation experiments. Two different approaches are applied and constraints on the corresponding CC-NSI parameters are obtained with the neutrino flux taken from the Huber-Mueller model with a $5\%$ uncertainty. For the quantum mechanics-based approach (QM-NSI), the constraints on the CC-NSI parameters $\epsilon_{e\alpha}$ and $\epsilon_{e\alpha}^{s}$ are extracted with and without the assumption that the effects of the new physics are the same in the production and detection processes, respectively. The approach based on the weak effective field theory (WEFT-NSI) deals with four types of CC-NSI represented by the parameters $[\varepsilon_{X}]_{e\alpha}$. For both approaches, the results for the CC-NSI parameters are shown for cases with various fixed values of the CC-NSI and the Dirac CP-violating phases, and when they are allowed to vary freely. We find that constraints on the QM-NSI parameters $\epsilon_{e\alpha}$ and $\epsilon_{e\alpha}^{s}$ from the Daya Bay experiment alone can reach the order $\mathcal{O}(0.01)$ for the former and $\mathcal{O}(0.1)$ for the latter, while for WEFT-NSI parameters $[\varepsilon_{X}]_{e\alpha}$, we obtain $\mathcal{O}(0.1)$ for both cases., Comment: 25 pages, 16 figures, 6 tables; 36 pages, format changed, references added

Holes in silicon quantum dots are promising for spin qubit applications due to the strong intrinsic spin-orbit coupling. The spin-orbit coupling produces complex hole-spin dynamics, providing opportunities to further optimize spin qubits. Here, we demonstrate a singlet-triplet qubit using hole states in a planar metal-oxide-semiconductor double quantum dot. We observe rapid qubit control with singlet-triplet oscillations up to 400 MHz. The qubit exhibits promising coherence, with a maximum dephasing time of 600 ns, which is enhanced to 1.3 us using refocusing techniques. We investigate the magnetic field anisotropy of the eigenstates, and determine a magnetic field orientation to improve the qubit initialisation fidelity. These results present a step forward for spin qubit technology, by implementing a high quality singlet-triplet hole-spin qubit in planar architecture suitable for scaling up to 2D arrays of coupled qubits.

We present a new determination of the smallest neutrino mixing angle ${\theta}_{13}$ and the mass-squared difference ${\Delta}{\rm m}^{2}_{32}$ using a final sample of $5.55 \times 10^{6}$ inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample was selected from the complete data set obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are ${\rm sin}^{2}2{\theta}_{13} = 0.0851 \pm 0.0024$, ${\Delta}{\rm m}^{2}_{32} = (2.466 \pm 0.060) \times 10^{-3}{\rm eV}^{2}$ for the normal mass ordering or ${\Delta}{\rm m}^{2}_{32} = -(2.571 \pm 0.060) \times 10^{-3} {\rm eV}^{2}$ for the inverted mass ordering., Comment: 7 pages, 3 figures, 1 table, 10 supplementary files

A joint determination of the reactor antineutrino spectra resulting from the fission of $^{235}$U and $^{239}$Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level of consistency of $^{235}$U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant $^{235}$U and $^{239}$Pu isotopes and improves the uncertainty of the $^{235}$U spectral shape to about 3\%. The ${}^{235}$U and $^{239}$Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the $^{235}$U and $^{239}$Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors., Comment: 8 pages, 5 figures, Supplementary Material Included

The one-dimensional Lieb-Liniger Bose gas is a prototypical many-body system featuring universal Tomonaga-Luttinger liquid (TLL) physics and free fermion quantum criticality. We analytically calculate finite temperature local pair correlations for the strong coupling Bose gas at quantum criticality using the polylog function in the framework of the Yang-Yang thermodynamic equations. We show that the local pair correlation has the universal value $g^{(2)}(0)\approx 2 p/(n\varepsilon)$ in the quantum critical regime, the TLL phase and the quasi-classical region, where $p$ is the pressure per unit length rescaled by the interaction energy $\varepsilon=\frac{\hbar^2}{2m} c^2$ with interaction strength $c$ and linear density $n$. This suggests the possibility to test finite temperature local pair correlations for the TLL in the relativistic dispersion regime and to probe quantum criticality with the local correlations beyond the TLL phase. Furthermore, thermodynamic properties at high temperatures are obtained by both high temperature and virial expansion of the Yang-Yang thermodynamic equation., Comment: 8 pages, 6 figures, additional text and references

We present broad band photometry and photometric redshifts for 187611 sources located in ~0.5deg^2 in the Lockman Hole area. The catalog includes 389 X-ray detected sources identified with the very deep XMM-Newton observations available for an area of 0.2 deg^2. The source detection was performed on the Rc, z' and B band images and the available photometry is spanning from the far ultraviolet to the mid infrared, reaching in the best case scenario 21 bands. Astrometry corrections and photometric cross-calibrations over the entire dataset allowed the computation of accurate photometric redshifts. Special treatment is undertaken for the X-ray sources, the majority of which is active galactic nuclei. Comparing the photometric redshifts to the available spectroscopic redshifts we achieve for normal galaxies an accuracy of \sigma_{\Delta z/(1+z)}=0.036, with 12.7% outliers, while for the X-ray detected sources the accuracy is \sigma_{\Delta z/(1+z)}=0.069, with 18.3% outliers, where the outliers are defined as sources with |z_{phot}-z_{spec}|>0.15 (1+z_{spec})}. These results are a significant improvement over the previously available photometric redshifts for normal galaxies in the Lockman Hole, while it is the first time that photometric redshifts are computed and made public for AGN for this field., Comment: 26 pages, 19 figures. Submitted to ApJ. Revised version according to referee comments

The importance of imposing physical boundary conditions on the $T$-matrix to remove the nonperturbative renormalization prescription dependence is stressed and demonstrated in two diagonal channels, $^1P_1$ and $^1D_2$, with the help of Pad\'e expansion., Comment: 4 pages, 2 figures, to appear in Chinese Physics Letters

In this paper a prescription for generating an equilibrium spherical system depicted with cuspy density profiles is extended to a core density profile, the Burkert profile, which is observationally more suitable to dwarfs. By using a time-saving Monte Carlo method instead of N-body simulations, we show that the Burkert halo initialized with the distribution function that depends only on energy is in a practically stable equilibrium. The one generated using the local Maxwellian approximation is unstable, where the flat core density structure tends to steepen. This is fundamentally different from the previous study on a halo with cuspy density profile. The deviation of the unstable "Burkert" from the initial Burkert profile is found to be closely related to taking a Gaussian as the velocity distribution at any given point. The significance of not using the local Maxwellian approximation is further demonstrated by exploring the dynamical evolution of compact super star clusters in the Burkert halo. In particular, the local Maxwellian approximation will result in underestimating the dynamical friction and overestimating sinking time scale. Accordingly, it will lead to lower probability of forming massive bulges and young nuclear star clusters in bulgeless galaxies., Comment: 12 pages, 3 figures, accepted for publication in PASJ

We carried out a Pad\'e approximant analysis on a compact factor of the $T$-matrix for $NN$ scattering to explore the nonperturbative renormalization prescription in a universal manner. The utilities and virtues for this Pad\'e analysis were discussed., Comment: 6 pages, 6 figures, revised version, to appear in Commun. Theor. Phys

The dynamical evolution of super star clusters (SSCs) moving in the background of a dark matter halo has been investigated as a possible event responsible for the formation of bulges in late-type spirals. The underlying physical processes include sinking of SSCs due to the dynamical friction and stripping of SSCs on their way to the center. Our model calculations show that only sinking of circumnuclear SSCs contributes to the formation of galactic bulges at the early stage. Based on the assumption of a universal density profile for the dark matter halo, and an isothermal model for the SSCs, our simulations have yielded bulges that are similar in many aspects to the observational ones. In particular, the derived surface density profiles can be well fitted by anexponential structure with nuclear cusps, which is consistent with HST observations., Comment: 12 pages, 3 figures, accepted for publication in MNRAS Letter

The dynamical evolution of super star clusters (SSCs) moving in the background of dark matter halo has been investigated as a possible event causing the observed correlation between the mass of galactic bulge, $M_{bulge}$, and the mass of its central black hole, $M_{BH}$. The involved physical processes are the sinking of SSCs due to the dynamical friction, and the stripping of SSCs on their way to the center. Model calculations show that only sinking of circumnuclear SSCs contribute to both the growth of the central object and the formation of the galactic bulge at the early stage. On the assumption of a universal density profile for the dark matter halo, and an isothermal model for the SSCs, our simulations have yielded the mass ratio of the central objects to the bulges formed this way to be about a few times $10^{-4}$, less than the observed median value for early type galaxies. It is, however, consistent with the observed mass ratio for disk spirals, implying that the proposed scenario might be a possible event for the formation of bulges and central black holes of late type galaxies and for $M_{BH} - M_{bulge}$ correlation of disk galaxies., Comment: submitted to MNRAS Letter

Our analysis on the two magnitude-limited samples of LINERs suggests a correlation between $L_{\FIR}/L_{\B}$ or f(25\micron)/f(60\micron), and Hubble-type index at $>$99.99% significance level. As $L_{\FIR}/L_{\B}$ and f(25\micron)/f(60\micron) are considered as the indicators of star-formation activity and AGN activity, respectively, our result suggests that LINERs with higher AGN activity may have a lower star-formation contribution. The ones with highest AGN activity and lowest star-formation contributions are ellipticals. All well-studied LINER 1s belong to this group. On the other hand, LINERs with higher star-formation activity present lower AGN contributions. We find all well-studied LINER 2s in this parameter space. Most of LINERs having inner ring structures belong to this group. Statistics with other indicators of star-formation or AGN activity (nulear mass-to-light ratio at H band, and the ratio of X-ray-to-UV power) provide further evidence for such a trend. We have seen that along with the evolution of galaxies from late-type spirals to early-type ones, and up to ellipticals, the intensity of AGN activity increases with decreasing star-formation contributions, The above analyses may suggest a possible connection between the host galaxies and nuclear activities, and it might also indicate a possible evolutionary connection between AGN and starburst in LINERs., Comment: 7 pages, 4 figures. accepted for publication in ApJ Letter

We find that a preliminary classification of LINERs' energetics may be made in terms of the FIR-radio correlation of Wolf-Rayet galaxies. The AGN- or starburst-supported LINERs can be distinguished by their FIR-to-radio ratio, $Q\equiv L(1.4{\rm GHz})/$ $L(60\mu{\rm m})>$ or $<0.01$. It is interesting to note that almost all the LINERs with inner rings might be starburst- supported, indicating reduced AGN activities compared with those of the AGN-supported ones. We also find that a shock-heating phase for the warm dust component might be important for some starbursts at the burst age of $\ge 10^{7}$ yr, with $Q<0.001$., Comment: 9 pages, 4 figures, to be published in Astronomy & Astrophysics

We report our preliminary results on the role of starbursts in LINERs by use of WR galaxies as a tool. The essence of this approach lies in the different FIR-radio relation of WR galaxies from the pure AGN's., Comment: 2 pages including 2 postscript figures, to be published in the Proceedings of the IAU Symposium No. 193: "Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies", held in Puerto Vallarta, Mexico, 3 - 7 November 1998

We present optical spectra for new infrared Seyfert galaxies obtained with the 2.16m telescope at Beijing Astronomical Observatory (BAO). After wavelength and flux calibration, they are classified by the degree of nuclear activity: nine Seyfert 2 and three Seyfert 3 galaxies. In addition, by using the data from de Grijp et al.(1992), we find that (1) there exists a tight correlation between luminosities of far-infrared ($L_{FIR}$) and \Ha ($L_{H\alpha}$) for both Seyfert and HII-like (starburst) galaxies; (2) the median value of \Ha luminosities of Seyfert 1s is one magnitude larger than that of Seyfert 2s and starburst galaxies; (3) the cumulative distributions of FIR luminosities and infrared spectral index $\alpha(100,60)$ for Seyfert 1s and 2s are similar to that of starburst galaxies. We conclude that most of the far-infrared emission from Seyfert 2 galaxies is due to the violent nuclear/circumnuclear starburst, rather than the nonthermal activity in the nucleus, this may also be the case for many Seyfert 1s as well., Comment: 6 pages, incl. 4 PS figures, Latex and l-aa style A&Ap, 1997, 319, 92

In this paper, we report our preliminary results on enhanced star formation activity in Seyfert 2 galaxies. By re-analysing the Tully-Fisher relation for Whittle(1992)'s sample and for a Seyfert 2s' sample selecting from Veron-Cetty & Veron (1996), we find that (1) almost all Seyfert 2 galaxies with circumnuclear star formation have a ratio of far infrared (FIR) to blue luminosities ($L_{FIR}/L_{B}$) to be larger than 1/3; (2) for Seyfert 2 galaxies with $L_{FIR}/L_{B} < 1/3$, the Tully-Fisher relation is similar to that of the normal spiral galaxies; while for those with $\rm L_{FIR}/L_{B} \geq 1/3 $, they are significantly different from the normal ones, which confirms Whittle's suggestion of enhanced star formation activities in the circumnuclear regions of these Seyfert 2 galaxies., Comment: 9 pages, Latex, with two figures, and accepted for publication in ApSS

We report the discovery of two new Wolf-Rayet (WR) galaxies: Mrk~1039, and F08208$+$2816. Two broad WR bumps at 5808\AA~ and 4650\AA~ indicate the presence of WCE and WNL star population in all two sources. We also confirm the presenceof WR features in Mrk~35, previously detected in a different position. The observed equivalent width of the WR bump at 4650\AA~ and the derived number ratios of WR/(WR$+$O) imply that star formation in these sources takes place inshort burst duration. Comparisons with the recent models of WR populations in young starbursts with the observed EW(\HeII)/EW(\CIV)/EW(WRbump) and their relative intensitie provide an indication that the stellar initial mass function in some WR galaxies might not be Salpeter-like. It is interesting to find that the luminous IRAS source, F08208$+$2816, has little dust reddening, probably because of the existence of a powerful superwind. By comparisons with other starbursts observed with the Hopkins Ultraviolet Telescope, F08208$+$2816 as a merging system renders a chance to study the contribution from young starbursts to the UV background radiation in universe., Comment: 22 pages, 6 figures, 4 tables, accepted by The Astrophysical Journal

We have observed an object having strong Balmer absorption lines and blue continuum. The inference about the nuclear stellar population drawn from the line ratios is basically coincident with that drawn from the continuum color, both indicating the dominant fraction of early A type population in the nucleus. This might be expected only if there has been a very massive starburst, burst strength of $>$ 10\% at least., Comment: 4 pages, l-aa.sty, 1 figure available on request at jhh@nju.edu.cn, accepted for publication in A\&A

New test-particle simulations have been performed to study the secular evolution of the gaseous distribution in NGC 4736. We find that the distribution of gas clouds can be understood in the frame of perturbation induced by a nuclear oval potential, in addition to a spiral-like potential. Our experiments show that both inner and outer rings are stable structures located at the inner Lindblad resonance (ILR) and the outer Lindblad resonance(OLR), respectively, in agreement with the observations of NGC 4736. One of our simplified simulations indicates that both nuclear starburst and orbital resonance might be needed for keeping the inner ring stable for a long period. We have introduced a symplectic algorithm in the orbit integration. Its stronger stability allows us to adopt a rather large time step to save computational time. Substitution of a viscous force for cloud-cloud interactions proves adequate in the case of NGC 4736., Comment: 7 pages, l-aa.sty, 6 figures available on request at jhh@nju.edu.cn, Accepted for publication in A\&A

We use the ratio $L_{\rm FIR}/L_{\rm B}$ and the IRAS color index S$_{25}$/S$_{12}$ (both widely used as indices of relative star formation rates in galaxies) to analyse subsets (containing no known AGNs or merging/interacting galaxies) of: (a) the IRAS Bright Galaxy Sample, (b) galaxies from the optically complete RSA sample which have IRAS detections in all four bands, and (c) a volume-limited IR-unselected sample. We confirm that IR-bright barred (SB) galaxies do, on average, have very significantly higher values of the FIR-optical and S$_{25}$/S$_{12}$ ratios (and presumably, higher relative star formation rates, SFR) than that do unbarred ones; the effect is most obvious in the IR colors. We also confirm that these differences are confined to early-type (S0/a - Sbc) spirals and are not evident among late-type systems (Sc - Sdm). {\it Unlike others, we see no enhancement of the SFR in weakly-barred (SAB) galaxies.} We further confirm that the effect of bars on the SFR is associated with the relative IR luminosity and show that it is detectable only in galaxies with $L_{\rm FIR}/L_{\rm B}$ $\proxgreat$ 1/3, suggesting that as soon as they have any effect, bars translate their host galaxies into this relatively IR-luminous group. Conversely, for galaxies with $L_{\rm FIR}/L_{\rm B}$ below$\sim$ 0.1 this luminosity ratio is {\it lower} among barred than unbarred systems, again confirming and quantifying an earlier result. Although there is no simple physical relation between HI content and star formation, a strong correlation of HI content with the presence of bars has been found for early-type spirals with $L_{\rm FIR}/L_{\rm B}$ $\proxgreat$ 1/3. This suggests that the availability of fuel is the factor determining just which galaxies undergo bar-induced starbursts., Comment: 12 pages, l-aa.sty, 1 table and 10 figures available on request at jhh@nju.edu.cn, accepted for publication in A\&A