Abstract
We report on analysis of observations of the bright transient X-ray pulsar Swift J0243.6+6124 obtained during its 2017-2018 giant outburst with Insight-HXMT, NuSTAR, and Swift observatories. ...We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disk to a radiation pressure dominated (RPD) state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to super-critical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars (ULPs), which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields.
A search for a time-varying ν¯e signal was performed with 621 days of data acquired by the Daya Bay Reactor Neutrino Experiment over 704 calendar days. The time spectrum of the measured ν¯e flux ...normalized to its prediction was analyzed with a Lomb-Scargle periodogram, which yielded no significant signal for periods ranging from 2 hours to nearly 2 years. The normalized time spectrum was also fit for a sidereal modulation under the Standard Model Extension (SME) framework to search for Lorentz and CPT violation (LV-CPTV). Limits were obtained for all six flavor pairs e¯μ¯,e¯τ¯, μ¯τ¯, e¯e¯,μ¯μ¯ and τ¯τ¯ by fitting them one at a time, constituting the first experimental constraints on the latter three. Daya Bay’s high statistics and unique layout of multiple directions from three pairs of reactors to three experimental halls allowed the simultaneous constraint of individual SME LV-CPTV coefficients without assuming others contribute negligibly, a first for a neutrino experiment.
Using a total of 9.0 fb−1 of e+e− collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes e+e−→γX(3872) with X(3872)→π0χcJ ...for J=0, 1, 2. We report the first observation of X(3872)→π0χc1, a new decay mode of the X(3872), with a statistical significance of more than 5σ for all systematic fit variations. Normalizing to the previously established process e+e−→γX(3872) with X(3872)→π+π−J/ψ, we find B(X(3872)→π0χc1)/B(X(3872)→π+π−J/ψ)=0.88−0.27+0.33±0.10, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to π0χc0 and π0χc2 of 19 and 1.1, respectively.
Using 6.32 fb–1 of electron-positron collision data recorded by the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we present the first search for the decay $D^{+}_{s}$ → ...a0(980)0e+νe, a0(980)0 → π0η, which could proceed via a0(980) – f0(980) mixing. No significant signal is observed. An upper limit of 1.2 × 10–4 at the 90% confidence level is set on the product of the branching fractions of $D^{+}_{s}$ → a0(980)0e+νe and a0(980)0 → π0η decays.
By analyzing a data sample corresponding to an integrated luminosity of 2.93 fb−1 collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure for the first time the ...absolute branching fraction of the D+ → ημ+νμ decay to be BD+→ημ+νμ = ( 10.4 ± 1.0stat ± 0.5syst) × 10−4. Using the world averaged value of BD+ → ηe+νe, the ratio of the two branching fractions is determined to be BD+ → ημ+νμ/BD+ → ηe+νe = 0.91 ± 0.13(stat+syst), which agrees with the theoretical expectation of lepton flavor universality within uncertainty. By studying the differential decay rates in five four-momentum transfer intervals, we obtain the product of the hadronic form factor f+η(0) and the c → d Cabibbo-Kobayashi-Maskawa matrix element |Vcd| to be fη+(0) |Vcd| = 0.087 ± 0.008stat ± 0.002syst. Taking the input of |Vcd| from the global fit in the standard model, we determine fη+(0) = 0.39 ± 0.04stat ± 0.01syst. On the other hand, using the value of fη+(0) calculated in theory, we find |Vcd| = 0.242 ± 0.022stat ± 0.00 6 syst ± 0.033theory.
Using a data set of 2.93 fb taken at a center-of-mass energy root s = 3.773 GeV with the BESIII detector at the BEPCII collider, we perform a search for an extra U(1) gauge boson, also denoted as a ...dark photon. We examine the initial state radiation reactions e(+)e(-) -> e(+)e(-) gamma(ISR) and e(+)e(-) -> mu(+)mu(-) gamma(ISR) for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. We observe no obvious enhancement in the mass range between 1.5 and 3.4 GeV/c(2) and set a 90% confidence level upper limit on the mixing strength of the dark photon and the Standard Model photon. We obtain a competitive limit in the tested mass range.
We report new measurements of the branching fraction B (Ds+ → ℓ+ν), where ℓ+ is either μ+ or τ+ ( → π+ ντ), based on 6.32 fb−1 of electron-positron annihilation data collected by the BESIII ...experiment at six center-of-mass energy points between 4.178 and 4.226 GeV. Simultaneously floating the Ds+ → μ+ νμ and Ds+ → τ+ ντ components yields B (Ds+ → τ+ ντ) = ( 5.21 ± 0.25 ± 0.17 ) × 10−2, B (Ds+ → μ+ νμ) = ( 5.35 ± 0.13 ± 0.16 ) × 10−3, and the ratio of decay widths ..., where the first uncertainties are statistical and the second systematic. No evidence of CP asymmetry is observed in the decay rates Ds± → μ± νμ and Ds± → τ± ντ : ACP (μ± ν) = (− 1.2 ± 2.5 ± 1.0) % and ACP (τ± ν) = ( + 2.9 ± 4.8 ± 1.0)%. Constraining our measurement to the Standard Model expectation of lepton universality (R = 9.75), we find the more precise results B (Ds+ → τ+ ντ) = ( 5.22 ± 0.10 ± 0.14 ) × 10−2 and ACP ( τ± ντ) = ( − 0.1 ± 1.9 ± 1.0 )%. Combining our results with inputs external to our analysis, we determine the c →s quark mixing matrix element, Ds+ decay constant, and ratio of the decay constants to be | Vcs | = 0.973 ± 0.009 ± 0.014 , fD+s = 249.9 ± 2.4 ± 3.5 MeV , and fD+s / fD+ = 1.232 ± 0.035, respectively.
This prospective, randomized, phase III trial shows that prophylactic cranial irradiation prolongs disease-free survival, decreases the rate of cerebral metastases and does not affect quality-of-life ...for patients with fully resected postoperative pathologically confirmed stage IIIA-N2 non-small-cell lung cancer and high risk of cerebral metastases after adjuvant chemotherapy.
This study compared prophylactic cranial irradiation (PCI) with observation in patients with resected stage IIIA–N2 non-small-cell lung cancer (NSCLC) and high risk of cerebral metastases after adjuvant chemotherapy.
In this open-label, randomized, phase III trial, patients with fully resected postoperative pathologically confirmed stage IIIA–N2 NSCLC and high cerebral metastases risk without recurrence after postoperative adjuvant chemotherapy were randomly assigned to receive PCI (30 Gy in 10 fractions) or observation. The primary end point was disease-free survival (DFS). The secondary end points included the incidence of brain metastases, overall survival (OS), toxicity and quality of life.
This trial was terminated early after the random assignment of 156 patients (81 to PCI group and 75 to control group). The PCI group had significantly lengthened DFS compared with the control group, with a median DFS of 28.5 months versus 21.2 months hazard ratio (HR), 0.67; 95% confidence interval (CI) 0.46–0.98;P = 0.037. PCI was associated with a decrease in risk of brain metastases (the actuarial 5-year brain metastases rate, 20.3% versus 49.9%; HR, 0.28; 95% CI 0.14–0.57;P < 0.001). The median OS was 31.2 months in the PCI group and 27.4 months in the control group (HR, 0.81; 95% CI 0.56–1.16;P = 0.310). While main toxicities were headache, nausea/vomiting and fatigue in the PCI group, they were generally mild.
In patients with fully resected postoperative pathologically confirmed stage IIIA–N2 NSCLC and high risk of cerebral metastases after adjuvant chemotherapy, PCI prolongs DFS and decreases the incidence of brain metastases.
We report on the analysis of the 10-1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October to 2010 February. ...In this analysis, we improve the energy estimate and extend the decl. range down to −30°. We find that the anisotropy maps above 100 TeV are distinct from that at a multi-TeV band. The so-called tail-in and loss-cone features identified at low energies get less significant, and a new component appears at ∼100 TeV. The spatial distribution of the GCR intensity with an excess (7.2 pre-trial, 5.2 post-trial) and a deficit (−5.8 pre-trial) are observed in the 300 TeV anisotropy map, in close agreement with IceCube's results at 400 TeV. Combining the Tibet results in the northern sky with IceCube's results in the southern sky, we establish a full-sky picture of the anisotropy in hundreds of TeV band. We further find that the amplitude of the first order anisotropy increases sharply above ∼100 TeV, indicating a new component of the anisotropy. All these results may shed new light on understanding the origin and propagation of GCRs.
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