Determination of strange sea distributions from νN deep inelastic scattering

We present an analysis of the nucleon strange sea extracted from a global Parton Distribution Function fit including the neutrino and anti-neutrino dimuon data by the CCFR and NuTeV Collaborations, the inclusive charged lepton–nucleon Deep Inelastic Scattering and Drell–Yan data. The (anti-)neutrino induced dimuon analysis is constrained by the semileptonic charmed-hadron branching ratio Bμ=(8.8±0.5)%$B_{\mu }=(8.8\pm 0.5)\mathrm{\%}$, determined from the inclusive charmed hadron measurements performed by the FNAL-E531 and CHORUS neutrino emulsion experiments. Our analysis yields a strange sea suppression factor κ(20 GeV²)=0.62±0.04(exp.)±0.03(QCD)$\kappa (20{\text{GeV}}^2)=0.62\pm 0.04(\text{exp.})\pm 0.03(\text{QCD})$, the most precise value available, an x-distribution of total strange sea that is slightly softer than the non-strange sea, and an asymmetry between strange and anti-strange quark distributions consistent with zero (integrated over x   it is equal to S⁻(20 GeV²)=0.0013±0.0009(exp.)±0.0002(QCD)$S^{-}(20{\text{GeV}}^2)=0.0013\pm 0.0009(\text{exp.})\pm 0.0002(\text{QCD})$).     

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.     

Observation of enhanced orbital electron-capture nuclear decay rate in a compact medium

The eigenstate energies of an atom increase under spatial confinement and this effect should increase the electron density of the orbital electrons at the nucleus thus increasing the decay rate of an electron capturing radioactive nucleus. We have observed that the orbital electron capture rates of ¹⁰⁹In and ¹¹⁰Sn increased by (1.00±0.17)%$(1.00\pm 0.17)\mathrm{\%}$ and (0.48±0.25)%$(0.48\pm 0.25)\mathrm{\%}$ respectively when implanted in the smaller Au lattice compared to implantation in a larger Pb lattice. These observations are interpreted to be a result of the higher compression experienced by the large radioactive atoms in the smaller spatial confinement of the Au lattice.     

Experimental search for neutron–mirror neutron oscillations using storage of ultracold neutrons

The idea of a hidden sector of mirror partners of elementary particles has attracted considerable interest as a possible candidate for dark matter. Recently it was pointed out by Berezhiani and Bento that the present experimental data cannot exclude the possibility of a rapid oscillation of the neutron n to a mirror neutron n′ with oscillation time much smaller than the neutron lifetime. A dedicated search for vacuum transitions n→n^′$\mathrm{n}\to {\mathrm{n}}^{\prime }$ has to be performed at weak magnetic field, where both states are degenerate. We report the result of our experiment, which compares rates of ultracold neutrons after storage at a weak magnetic field well below 20 nT and at a magnetic field strong enough to suppress the seeked transitions. We obtain a new limit for the oscillation time of n–n′ transitions, τosc(90% C.L.)>414 s${\tau }_{\mathrm{osc}}(90\mathrm{\%}\text{C.L.})>414\text{s}$. The corresponding limit for the mixing energy of the normal and mirror neutron states is δm(90% C.L.)<1.5×¹⁰⁻¹⁸ eV$\delta m(90\mathrm{\%}\text{C.L.})<1.5\times {10}^{\mathrm{-18}}\text{eV}$.     

Partially (in)visible Higgs decays at the LHC

Both ATLAS and CMS have reported a discovery of a Standard Model-like Higgs boson H   of mass around 125 GeV. Consistency with the Standard Model implies the non-observation of non-SM-like decay modes of the newly discovered particle. Sensitivity to such decay modes, especially when they involve partially invisible final states is currently beyond scrutiny of the LHC. We systematically study such decay channels in the form of H→AA→jets+missing energy$H\to AA\to \text{jets}+\text{missing energy}$, with A   a light scalar or pseudo-scalar, and analyze to what extent these exotic branching fractions can be constrained by direct measurements at the LHC. While the analysis is challenging, constraints as good as BR?10%$\mathrm{BR}?10\text{\%}$ can be obtained.     

Neutron lifetime measurement with the UCN trap-in-trap MAMBO II

We have measured the free neutron lifetime τn${\tau }_n$ by storage of ultra-cold neutrons (UCN) in a Fomblin coated UCN trap of in situ variable size. The method was initially developed by W. Mampe et al. (1989) [10] with MAMBO I and improved by the addition of a prestorage volume yielding a well defined UCN spectrum for storage in the main trap. By extrapolation to infinite trap size using the time scaling method we obtain for the free neutron lifetime τn=(880.7±1.3±1.2) s${\tau }_n=(880.7\pm 1.3\pm 1.2)\text{s}$. Data from different UCN spectra, trap temperatures and storage times were used for the evaluation. The present result is compared with other experimental neutron lifetime data.     

125 GeV Higgs,type III seesaw and gauge–Higgs unification

Recently, both the ATLAS and CMS experiments have observed an excess of events that could be the first evidence for a 125 GeV Higgs boson. This is a few GeV below the (absolute) vacuum stability bound on the Higgs mass in the Standard Model (SM), assuming a Planck mass ultraviolet (UV) cutoff. In this Letter, we study some implications of a 125 GeV Higgs boson for new physics in terms of the vacuum stability bound. We first consider the seesaw extension of the SM and find that in type III seesaw, the vacuum stability bound on the Higgs mass can be as low as 125 GeV for the seesaw scale around a TeV. Next we discuss some alternative new physics models which provide an effective ultraviolet cutoff lower than the Planck mass. An effective cutoff Λ?10¹¹ GeV$\Lambda ?{10}^{11}\text{GeV}$ leads to a vacuum stability bound on the Higgs mass of 125 GeV. In a gauge–Higgs unification scenario with five-dimensional flat spacetime, the so-called gauge–Higgs condition can yield a Higgs mass of 125 GeV, with the compactification scale of the extra-dimension being identified as the cutoff scale Λ?10¹¹ GeV$\Lambda ?{10}^{11}\text{GeV}$. Identifying the compactification scale with the unification scale of the SM SU(2) gauge coupling and the top quark Yukawa coupling yields a Higgs mass of 121±2 GeV$121\pm 2\text{GeV}$.     

Ocean heat content and Earthʼs radiation imbalance. II. Relation to climate shifts

In an earlier study of ocean heat content (OHC) we showed that Earth?s empirically implied radiation imbalance has undergone abrupt changes. Other studies have identified additional such climate shifts since 1950. The shifts can be correlated with features in recently updated OHC data. The implied radiation imbalance may possibly alternate in sign at dates close to the climate shifts. The most recent shifts occurred during 2001–2002 and 2008–2009. The implied radiation imbalance between these dates, in the direction of ocean heat loss, was −0.03±0.06 W/m²$-0.03\pm 0.06\text{W}/{\text{m}}^2$, with a possible systematic error of [−0.00,+0.09] W/m²$[-0.00,+0.09]\text{W}/{\text{m}}^2$.     

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.     

New Horizons and the onset of the Pioneer anomaly

Analysis of the radio tracking data from the Pioneer 10/11 spacecraft at distances between about 20–70 AU from the Sun has indicated the presence of an unmodeled, small, constant, Doppler blue shift which can be interpreted as a constant acceleration of aP=(8.74±1.33)×¹⁰⁻⁸ cm/s²$a_P=(8.74\pm 1.33)\times {10}^{\mathrm{-8}}\text{ cm}/{\text{s}}^2$ directed approximately towards the Sun. In addition, there is early (roughly modeled) data from as close in as 5 AU which indicates there may have been an onset of the anomaly near Saturn. We observe that the data now arriving from the New Horizons mission to Pluto and the Kuiper Belt could allow a relatively easy, direct experimental test of whether this onset is associated with distance from the Sun (being, for example, an effect of drag on dark matter). We strongly urge that this test be done.     

Security analysis of the “Ping–Pong” quantum communication protocol in the presence of collective-rotation noise

Environmental noise is inevitable in non-isolated systems. It is, therefore, necessary to analyze the security of the “Ping–Pong” protocol in a noisy environment. An excellent model for collective-rotation noise is introduced, and information theoretical methods are applied to analyze the security of this protocol. If noise level ε   is lower than 11%, an eavesdropper can gain some, but not all, information freely without being detected. Otherwise, the protocol becomes insecure. We conclude that the use of ‘Ping–Pong’ protocol as a quantum secure direct communication (QSDC) protocol is quasi-secure, as declared by the original author when ε?11%$\epsilon ?11\text{\%}$.