9310759
Unified Field Theory and Principle of Representation Invariance
The main objectives of this article are to postulate a new principle of representation invariance (PRI), and to refine the unified field model of four interactions, derived using the principle of interaction dynamics (PID). Intuitively, PID takes the variation of the action functional under energy-momentum conservation constraint, and PRI requires that physical laws be independent of representations of the gauge groups. One important outcome of this unified field model is a natural duality between the interacting fields (g,A,Wa,Sk), corresponding to graviton, photon, intermediate vector bosons W± and Z and gluons, and the adjoint bosonic fields $(\varPhi_{\mu}, \phi^{0}, \phi^{a}_{w}, \phi^{k}_{s})$. This duality predicts two Higgs particles of similar mass with one due to weak interaction and the other due to strong interaction. The unified field model can be naturally decoupled to study individual interactions, leading to (1) modified Einstein equations, giving rise to a unified theory for dark matter and dark energy (Ma and Wang in Discrete Contin. Dyn. Syst., Ser A. 34(2):335–366, 2014), (2) three levels of strong interaction potentials for quark, nucleon/hadron, and atom respectively (Ma and Wang in Duality theory of strong interaction, 2012), and (3) two weak interaction potentials (Ma and Wang in Duality theory of weak interaction, 2012). These potential/force formulas offer a clear mechanism for both quark confinement and asymptotic freedom—a longstanding problem in particle physics (Ma and Wang in Duality theory of strong interaction, 2012).
119275511
Gravitational Field Equations and Theory of Dark Matter and Dark Energy
The main objective of this article is to derive new gravitational field equations and to establish a unified theory for dark energy and dark matter. The gravitational field equations with a scalar potential $\varphi$ function are derived using the Einstein-Hilbert functional, and the scalar potential $\varphi$ is a natural outcome of the divergence-free constraint of the variational elements. 
Gravitation is now described by the Riemannian metric 
$g_{\mu\nu}$, the scalar potential $\varphi$ and their interactions, unified by the new field equations. 
From quantum field theoretic point of view, the vector field $\Phi_\mu=D_\mu \varphi$, the gradient of the scalar function $\varphi$, is a spin-1 massless bosonic particle field. The field equations induce a natural duality between the graviton (spin-2 massless bosonic particle) and this spin-1 massless bosonic particle. Both particles can be considered as gravitational force carriers, and as they are massless, the induced forces are long-range forces. The (nonlinear) interaction between these bosonic particle fields leads to a unified theory for dark energy and dark matter. Also, associated with the scalar potential $\varphi$ is the scalar potential energy density $\frac{c^4}{8\pi G} \Phi=\frac{c^4}{8\pi G} g^{\mu\nu}D_\mu D_\nu \varphi$, which represents a new type of energy caused by the non-uniform distribution of matter in the universe. 
The negative part of this potential energy density produces attraction, and the positive part produces repelling force. This potential energy density is conserved with mean zero: $\int_M \Phi dM=0$. 
The sum of this potential energy density 
$\frac{c^4}{8\pi G} \Phi$ and the coupling energy 
 between the energy-momentum tensor $T_{\mu\nu}$ and the scalar potential field $\varphi$ gives rise to a unified theory for dark matter and dark energy: 
The negative part of 
this sum represents the dark matter, which produces attraction, 
and the positive part represents the dark energy, which drives the acceleration of expanding galaxies. 
In addition, the scalar curvature of space-time obeys $R=\frac{8\pi G}{c^4} T + \Phi$. 
Furthermore, the proposed field equations resolve a few difficulties encountered by the classical Einstein field equations.
51818165
Unified field equations coupling four forces and principle of interaction dynamics
The main objective of this article is to postulate a principle of interaction dynamics (PID) and to derive field equations coupling the four fundamental interactions based on first principles. PID is a least action principle subject to div$_A$-free constraints for the variational element with $A$ being gauge potentials. The Lagrangian action is uniquely determined by 1) the principle of general relativity, 2) the $U(1)$, $SU(2)$ and $SU(3)$ gauge invariances, 3) the Lorentz invariance, and 4) the principle of representation invariance (PRI), introduced in [11]. The unified field equations are then derived using PID. The field model spontaneously breaks the gauge symmetries, and gives rise to a new mass generation mechanism. 
The unified field model introduces a natural duality between the mediators and their dual mediators, and can be easily decoupled to study each individual interaction when other interactions are negligible. The unified field model, together with PRI and PID applied to individual interactions, provides clear explanations and solutions to a number of outstanding challenges in physics and cosmology, including e.g. the dark energy and dark matter phenomena, the quark confinement, asymptotic freedom, short-range nature of both strong and weak interactions, decay mechanism of sub-atomic particles, baryon asymmetry, and the solar neutrino problem.
118858199
SIGMOID-TO-FLUX-ROPE TRANSITION LEADING TO A LOOP-LIKE CORONAL MASS EJECTION
Sigmoids are one of the most important precursor structures for solar eruptions. In this Letter, we study a sigmoid eruption on 2010 August 1 with EUV data obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO). In AIA 94 A (Fe XVIII; 6 MK), topological reconfiguration due to tether-cutting reconnection is unambiguously observed for the first time, i.e., two opposite J-shaped loops reconnect to form a continuous S-shaped loop, whose central portion is dipped and aligned along the magnetic polarity inversion line (PIL), and a compact loop crossing the PIL. A causal relationship between photospheric flows and coronal tether-cutting reconnections is evidenced by the detection of persistent converging flows toward the PIL using line-of-sight magnetograms obtained by the Helioseismic and Magnetic Imager on board SDO. The S-shaped loop remains in quasi-equilibrium in the lower corona for about 50 minutes, with the central dipped portion rising slowly at ~10 km s–1. The speed then increases to ~60 km s–1 about 10 minutes prior to the onset of a GOES-class C3.2 flare, as the S-shaped loop speeds up its transformation into an arch-shaped loop, which eventually leads to a loop-like coronal mass ejection. The AIA observations combined with Hα filtergrams as well as hard X-ray imaging and spectroscopy are consistent with most flare loops being formed by reconnection of the stretched legs of less-sheared J-shaped loops that envelopes the rising flux rope, in agreement with the standard tether-cutting scenario.
117498892
First Flare-related Rapid Change of Photospheric Magnetic Field Observed by Solar Dynamics Observatory
Photospheric magnetic field not only plays important roles in building up free energy and triggering solar eruptions, but also has been observed to change rapidly and permanently responding to the coronal magnetic field restructuring due to coronal transients. The Helioseismic and Magnetic Imager instrument (HMI) on board the newly launched Solar Dynamics Observatory (SDO) produces seeing-free full-disk vector magnetograms at consistently high resolution and high cadence, which finally makes possible an unambiguous and comprehensive study of this important back-reaction process. In this study, we present a near disk-center, GOES-class X2.2 flare occurred at NOAA AR 11158 on 2011 February 15 using the magnetic field measurements made by HMI. We obtained the first solid evidence of an enhancement in the transverse magnetic field at the flaring magnetic polarity inversion line (PIL) by a magnitude of 70%. This rapid and irreversible field evolution is unequivocally associated with the flare occurrence, with the enhancement area located in between the two chromospheric flare ribbons. Similar findings have been made for another two major flare events observed by SDO. These results strongly corroborate our previous suggestion that the photospheric magnetic field near the PIL must become more horizontal after eruptions. 
In-depth studies will follow to further link the photospheric magnetic field changes with the dynamics of coronal mass ejections, when full Stokes inversion is carried out to generate accurate magnetic field vectors.
118073401
Observation of $\eta_{c}$ decay into $\Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$ final states
Using a data sample of $2.25\times10^{8}$ $J/\psi$ events collected with the BESIII detector, we present the first observation of the decays of $\eta_{c}$ mesons to $\Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$. The branching fractions are measured to be $(2.11\pm0.28_{\rm stat.}\pm0.18_{\rm syst.}\pm0.50_{\rm PDG})\times10^{-3}$ and $(0.89\pm0.16_{\rm stat.}\pm0.08_{\rm syst.}\pm0.21_{\rm PDG})\times10^{-3}$ for $\eta_{c} \to \Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$, respectively. These branching fractions provide important information on the helicity selection rule in charmonium-decay processes.
92988039
BEPC AND THE FUTURE PROGRAM AT IHEP
Beijing Electron and Positron Collider (BEPC), a 1.55— 2.8GeV accelerator facility serving for both high energy physics experiment and synchrotron radiation application, was constructed in the years from 1984 to 1988. The BEPC has been operating since 1989, in the meantime the BEPC upgrades were conducted and Beijing Tau-Charm Factory, a 1.5—2.5GeV double-ring collider was designed in the period from 1993 to 1996. In this paper, the BEPC and its current status are briefly introduced, the recent progress and the achieved results of the BEPC upgrade project are presented, and the future program of BTCF/BEPC-II is described.
9514883
Measurement of the cross section for prompt isolated diphoton production using the full CDF run II data sample.
This Letter reports a measurement of the cross section for producing pairs of central prompt isolated photons in proton-antiproton collisions at a total energy sqrt[s] = 1.96 TeV using data corresponding to 9.5 fb(-1) integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured differential cross section is compared to three calculations derived from the theory of strong interactions. These include a prediction based on a leading order matrix element calculation merged with a parton shower model, a next-to-leading order calculation, and a next-to-next-to-leading order calculation. The first and last calculations reproduce most aspects of the data, thus showing the importance of higher-order contributions for understanding the theory of strong interaction and improving measurements of the Higgs boson and searches for new phenomena in diphoton final states.