119247311
CHIRAL SYMMETRY BREAKING AND STABILITY OF THE MAGNETIZED VACUUM
The recent claim [arXiv:hep-th/0603070, arXiv:hep-th/0605020] that there exists in QED a maximum magnetic field of 10^{42} G, above which the magnetized vacuum becomes unstable with respect to the so-called "positronium collapse" is critically examined and unequivocally refuted.
5549498
PROGRESS ON CHIRAL SYMMETRY BREAKING IN A STRONG MAGNETIC FIELD
The problem of chiral symmetry breaking in QED in a strong magnetic field is briefly reviewed. Recent progress on issues regarding the gauge fixing independence of the dynamically generated fermion mass is discussed.
17740001
Nonequilibrium relaxation of Bose-Einstein condensates: Real-time equations of motion and Ward identities
Abstract We present a field-theoretical method to obtain consistently the equations of motion for small amplitude condensate perturbations in a homogeneous Bose-condensed gas directly in real time. It is based on a linear response and combines the Schwinger–Keldysh formulation of nonequilibrium quantum field theory with the Nambu–Gor'kov formalism of quasiparticle excitations in the condensed phase and the tadpole method in quantum field theory. This method leads to causal equations of motion that allow us to study the nonequilibrium evolution as an initial value problem. It also allows us to extract directly the Ward identities, which are a consequence of the underlying gauge symmetry and which in equilibrium lead to the Hugenholtz–Pines theorem. An explicit one-loop calculation of the equations of motion beyond the Hartree–Fock–Bogoliubov approximation reveals that the nonlocal, absorptive contributions to the self-energies corresponding to the Beliaev and Landau damping processes are necessary to fulfill the Ward identities in or out of equilibrium. It is argued that a consistent implementation at low temperatures must be based on the loop expansion, which is shown to fulfill the Ward identities order by order in perturbation theory.
35173511
Real time nonequilibrium dynamics in hot QED plasmas: Dynamical renormalization group approach
We study the real-time nonequilibrium dynamics in hot QED plasmas implementing a dynamical renormalization group and using the hard thermal loop (HTL) approximation. The focus is on the study of the relaxation of gauge and fermionic mean fields and on the quantum kinetics of the photon and fermion distribution functions. For semihard photons of momentum eT q \gamma and \bar{q} -> \bar{q}\gamma) at O(\alpha) grows logarithmically in time and is comparable to that produced from on-shell Compton scattering and pair annihilation at O(\alpha \alpha_s). Fermion mean fields relax as e^{-\alpha T t ln(\omega_P t)} with \omega_P=eT/3 the plasma frequency, as a consequence of the emission and absorption of soft magnetic photons. A quantum kinetic equation for hard fermions is obtained directly in real time from a field theoretical approach improved by the dynamical renormalization group. The collision kernel is time-dependent and infrared finite.
28322811
Dynamical electron mass in a strong magnetic field
Motivated by recent interest in understanding properties of strongly magnetized matter, we study the dynamical electron mass generated through approximate chiral symmetry breaking in QED in a strong magnetic field. We reliably calculate the dynamical electron mass by numerically solving the nonperturbative Schwinger-Dyson equations in a consistent truncation within the lowest Landau level approximation. It is shown that the generation of dynamical electron mass in a strong magnetic field is significantly enhanced by the perturbative electron mass that explicitly breaks chiral symmetry in the absence of a magnetic field.
119494487
REAL-TIME NONEQUILIBRIUM DYNAMICS IN HOT QED PLASMAS
The quantum kinetics of photons in hot QED plasmas is studied directly in real time by implementing the dynamical renormalization group. In contrast to conventional approach, the dynamical renormalization group method consistently includes off-shell (energy non-conserving) effects and accounts for time-dependent collisional kernel. To lowest order we find that in the relaxation time approximation the semihard photon distribution function relaxes with a power law.
118143387
Chern Simons Theory and the volume of 3-manifolds
We give some applications of the Chern Simons gauge theory to the study of the set ${\rm vol}(N,G)$ of volumes of all representations $\rho\co\pi_1N\to G$, where $N$ is a closed oriented three-manifold and $G$ is either ${\rm Iso}_e\t{\rm SL_2(\R)}$, the isometry group of the Seifert geometry, or ${\rm Iso}_+{\Hi}^3$, the orientation preserving isometry group of the hyperbolic 3-space. We focus on three natural questions: 
(1) How to find non-zero values in ${\rm vol}(N, G)$? or weakly how to find non-zero elements in ${\rm vol}(\t N, G)$ for some finite cover $\t N$ of $N$? 
(2) Do these volumes satisfy the covering property in the sense of Thurston? 
(3) What kind of topological information is enclosed in the elements of ${\rm vol}(N, G)$? 
We determine ${\rm vol}(N, G)$ when $N$ supports the Seifert geometry, and we find some non-zero values in ${\rm vol}(N,G)$ for certain 3-manifolds with non-trivial geometric decomposition for either $G={\rm Iso}_+{\Hi}^3$ or ${\rm Iso}_e\t{\rm SL_2(\R)}$. Moreover we will show that unlike the Gromov simplicial volume, these non-zero elements carry the gluing information between the geometric pieces of $N$. 
For a large class 3-manifolds $N$, including all rational homology 3-spheres, we prove that $N$ has a positive Gromov simplicial volume iff it admits a finite covering $\t N$ with ${\rm vol}(\t N,{\rm Iso}_+{\Hi}^3)\ne \{0\}$. On the other hand, among such class, there are some $N$ with positive simplicial volume but ${\rm vol}(N,{\rm Iso}_+{\Hi}^3)=\{0\}$, yielding a negative answer to question (2) for hyperbolic volume.
118441515
Dark energy: A brief review
The problem of dark energy is briefly reviewed in both theoretical and observational aspects. In the theoretical aspect, dark energy scenarios are classified into symmetry, anthropic principle, tuning mechanism, modified gravity, quantum cosmology, holographic principle, back-reaction and phenomenological types. In the observational aspect, we introduce cosmic probes, dark energy related projects, observational constraints on theoretical models and model independent reconstructions.
14093861
Is the Schwarzschild black hole really stable
The stability of the Schwarzschild black hole is studied. Regge and Wheeler treated the problem first at 1957 and obtained the dynamical equations for the small perturbation. There are two kinds of perturbations: odd one and even one. Using the Painlev\'{e} coordinate, we reconsider the odd perturbation and find that: the white-hole-connected universe(r>2m, see text) is unstable. Because the odd perturbation may be regarded as the angular perturbation, therefore, the physical mean to it may be that the white-hole-connected universe is unstable with respect to the rotating perturbation.
122825097
CHIRAL SYMMETRY IN ATOMIC NUCLEI
The significant progresses of the chirality in atomic nuclei are briefly reviewed for both experimental and theoretical sides. Chiral doublet bands beyond one-particle and one-hole coupled with a triaxial rotor as well as the possibilities of new phenomenon MχD are discussed.
6081960
Search for the standard model Higgs boson decaying to a bb pair in events with two oppositely charged leptons using the full CDF data set.
We present a search for the standard model Higgs boson produced in association with a Z boson in data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45  fb(-1). In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electron or muon pairs, we set 95% credibility level upper limits on the ZH production cross section times the H→bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125  GeV/c(2), we observe (expect) a limit of 7.1 (3.9) times the standard model value.