Electromagnetic superconductivity of vacuum induced by strong magnetic field: Numerical evidence in lattice gauge theory

Using numerical simulations of quenched SU(2)$\mathit{SU}(2)$ gauge theory we demonstrate that an external magnetic field leads to spontaneous generation of quark condensates with quantum numbers of electrically charged ρ   mesons if the strength of the magnetic field exceeds the critical value e_Bc=0.927(77) GeV²$e{B}_c=0.927(77){\text{GeV}}^2$ or _Bc=(1.56±0.13)⋅10¹⁶ Tesla$B_c=(1.56\pm 0.13)\cdot {10}^{16}\text{Tesla}$. The condensation of the charged ρ mesons in strong magnetic field is a key feature of the magnetic-field-induced electromagnetic superconductivity of the vacuum.     

Top quark spin correlations at the Tevatron and the LHC

Spin correlations of top quarks produced in hadron collisions have not been observed experimentally with large significance. In this Letter, we propose a new variable that may enable demonstration of the existence of spin correlations with 3–4 σ$3\text{–}4\sigma$ significance using just a few hundred dilepton events both at the Tevatron and the LHC. Such number of dilepton events has been observed at the Tevatron. At the LHC, it will become available once integrated luminosity of a few hundred inverse picobarns is collected.     

Strange stars properties calculated in the framework of the Field Correlator Method

We calculate the strange star properties in the framework of the Field Correlator Method. We find that for gluon condensate values G₂$G_2$ in the range 0.006–0.007 GeV⁴$0.006\text{–}0.007{\text{GeV}}^4$, which give a critical temperature Tc∼170 MeV$T_c\sim 170\text{MeV}$ at μc=0${\mu }_c=0$, the sequences of strange stars are compatible with some of the semi-empirical mass–radius relations and data obtained from astrophysical observations.     

Anomalous Higgs couplings at the LHeC

The discovery of Higgs boson plays a crucial role in understanding the electroweak symmetry breaking sector. From now on, solving the dynamics of this sector needs precision measurements of the couplings of the Higgs boson to the Standard Model particles. In this work, we investigate the constrains on the anomalous HWW   and HWWγ$HWW\gamma$ couplings, described by the dimension-six operators in the effective Lagrangian, in a high energy envisaged ep collider which is called Large Hadron electron Collider (LHeC). We obtained the 95% confidence level limits on the couplings of anomalous HWW   and HWWγ$HWW\gamma$ vertex, with the design luminosity of 10 fb⁻¹$10{\text{fb}}^{-1}$ and electron beam energy of 140 GeV, through ep→νH+X$ep\to \nu H+X$, γp→WH+X$\gamma p\to WH+X$ and eγ→WHν$e\gamma \to WH\nu$ processes by considering the new physics energy scale to be Λ=1 TeV$\Lambda =1\text{TeV}$. The sensitivity of the LHeC to the new physics scale is also briefly discussed.     

Probing a possible vacuum refractive index with γ-ray telescopes

We have used a stringy model of quantum space–time foam to suggest that the vacuum may exhibit a non-trivial refractive index depending linearly on γ  -ray energy: η−1∼Eγ/M_QG1$\eta -1\sim E_{\gamma }/M_{\mathrm{QG}1}$, where MQG$M_{\mathrm{QG}}$ is some mass scale typical of quantum gravity that may be ∼¹⁰¹⁸ GeV$\sim {10}^{18}\text{GeV}$: see [J. Ellis, N.E. Mavromatos, D.V. Nanopoulos, Phys. Lett. B 665 (2008) 412] and references therein. The MAGIC, HESS and Fermi γ-ray telescopes have recently probed the possible existence of such an energy-dependent vacuum refractive index. All find indications of time-lags for higher-energy photons, but cannot exclude the possibility that they are due to intrinsic delays at the sources. However, the MAGIC and HESS observations of time-lags in emissions from AGNs Mkn 501 and PKS 2155-304 are compatible with each other and a refractive index depending linearly on the γ  -ray energy, with M_QG1∼¹⁰¹⁸ GeV$M_{\mathrm{QG}1}\sim {10}^{18}\text{GeV}$. We combine their results to estimate the time-lag Δt   to be expected for the highest-energy photon from GRB 080916c measured by the Fermi telescope, which has an energy ∼13.2 GeV$\sim 13.2\text{GeV}$, assuming the redshift z=4.35±0.15$z=4.35\pm 0.15$ measured by GROND. In the case of a refractive index depending linearly on the γ  -ray energy we predict Δt=26±11 s$\mathrm{\Delta }t=26\pm 11\text{s}$. This is compatible with the time-lag Δt?16.5 s$\mathrm{\Delta }t?16.5\text{s}$ reported by the Fermi Collaboration, whereas the time-lag would be negligible in the case of a refractive index depending quadratically on the γ-ray energy. We suggest a strategy for future observations that could distinguish between a quantum-gravitational effect and other interpretations of the time-lags observed by the MAGIC, HESS and Fermi γ-ray telescopes.