Lightest U-parity particle (LUP) dark matter

We suggest a U(1)^′$U{(1)}^{\prime }$ gauge symmetry as an alternative to the usual R  -parity of supersymmetric standard models, showing that it can also work as a common source of stabilities of proton and dark matter in addition to other attractive features. The residual discrete symmetries of a single U(1)^′$U{(1)}^{\prime }$ can provide stabilities to both the MSSM sector (proton) and the hidden sector (new dark matter candidate, LUP). The LUP can expand the viability of many models such as R-parity violating models and gauge mediation models regarding dark matter issue.     

A complete calculation for direct detection of Wino dark matter

In the anomaly-mediated supersymmetry (SUSY) breaking scenario, neutral gaugino of SUL₍₂₎$\mathit{SU}{(2)}_L$ multiplet, Wino, can be the lightest SUSY particle and become a candidate for dark matter. We calculated scattering cross section of Wino dark matter with nucleon, which is responsible for direct detection of the dark matter, on the assumption that the SUSY particles and the heavier Higgs bosons have masses of the order of the gravitino mass in the SUSY standard model. In such a case, the Wino–nucleon coupling is generated by loop processes. We have included two-loop contribution to Wino–gluon interaction in the calculation, since it is one of the leading contributions to the Wino–nucleon coupling. It was found that the spin-independent scattering cross section with proton is ^{10−(46–48)} cm²${10}^{-(46\text{–}48)}{\text{cm}}^2$. While it is almost independent of the Wino mass, the result is quite sensitive to the Higgs boson mass due to the accidental cancellation.     

Heavy neutral gauge bosons at the LHC in an extended MSSM

Searching for heavy neutral gauge bosons Z^′$Z^{\prime }$, predicted in extensions of the Standard Model based on a U(1)^′$\mathrm{U}{(1)}^{\prime }$ gauge symmetry, is one of the challenging objectives of the experiments carried out at the Large Hadron Collider. In this paper, we study Z^′$Z^{\prime }$ phenomenology at hadron colliders according to several U(1)^′$\mathrm{U}{(1)}^{\prime }$-based models and in the Sequential Standard Model. In particular, possible Z^′$Z^{\prime }$ decays into supersymmetric particles are included, in addition to the Standard Model modes so far investigated. We point out the impact of the U(1)^′$\mathrm{U}{(1)}^{\prime }$ group on the MSSM spectrum and, for a better understanding, we consider a few benchmarks points in the parameter space. We account for the D-term contribution, due to the breaking of U(1)^′$\mathrm{U}{(1)}^{\prime }$, to slepton and squark masses and investigate its effect on Z^′$Z^{\prime }$ decays into sfermions. Results on branching ratios and cross sections are presented, as a function of the MSSM and U(1)^′$\mathrm{U}{(1)}^{\prime }$ parameters, which are varied within suitable ranges. We pay special attention to final states with leptons and missing energy and make predictions on the number of events with sparticle production in Z^′$Z^{\prime }$ decays, for a few values of integrated luminosity and centre-of-mass energy of the LHC.     

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)$S^{-}(20{\text{GeV}}^2)=0.0013\pm 0.0009(\text{exp.})\pm 0.0002(\text{QCD})$).     

Dark matter annihilation in the Galactic Center as seen by the Fermi Gamma Ray Space Telescope

We analyze the first two years of data from the Fermi Gamma Ray Space Telescope from the direction of the inner 10° around the Galactic Center with the intention of constraining, or finding evidence of, annihilating dark matter. We find that the morphology and spectrum of the emission between 1.25° and 10° from the Galactic Center is well described by the processes of decaying pions produced in cosmic ray collisions with gas, and the inverse Compton scattering of cosmic ray electrons in both the disk and bulge of the Inner Galaxy, along with gamma rays from known points sources in the region. The observed spectrum and morphology of the emission within approximately 1.25° (∼175 parsecs) of the Galactic Center, in contrast, departs from the expectations for by these processes. Instead, we find an additional component of gamma ray emission that is highly concentrated around the Galactic Center. The observed morphology of this component is consistent with that predicted from annihilating dark matter with a cusped (and possibly adiabatically contracted) halo distribution (ρ∝r−γ$\rho \propto r^{-\gamma }$, with γ=1.18$\gamma =1.18$ to 1.33). The observed spectrum of this component, which peaks at energies between 1–4 GeV (in E²$E^2$ units), can be well fit by a 7–10 GeV dark matter particle annihilating primarily to tau leptons with a cross section in the range of 〈σv〉=4.6×¹⁰⁻²⁷$〈\sigma v〉=4.6\times {10}^{-27}$ to 5.3×¹⁰⁻²⁶ cm³/s$5.3\times {10}^{-26}{\text{cm}}^3/\text{s}$, depending on how the dark matter distribution is normalized. We also discuss other sources for this emission, including the possibility that much of it originates from the Milky Way?s supermassive black hole.     

Isomer-tagged differential-plunger measurements in proton-unbound Ho

The lifetime of an excited state above a weakly populated isomer in the proton-unbound odd–odd nucleus ¹⁴⁴Ho has been measured using the recoil distance Doppler shift method. This measurement represents the first differential-plunger lifetime measurement to utilize recoil-isomer tagging. The first excited Iπ=(¹⁰⁺)$I^{\pi }=({10}^{+})$ state above the two-quasiparticle πh_11/2⊗νh_11/2(⁸⁺)$\pi h_{11/2}\otimes \nu h_{11/2}(8^{+})$ isomer was determined to have a lifetime of τ=6(1) ps$\tau =6(1)\text{ps}$. Potential energy surface calculations, based on the configuration-constrained blocking method, predict the isomeric state to have γ  -soft triaxial-nuclear shape with |γ|≈24°$|\gamma |\approx 24\text{°}$. The lifetime of the (¹⁰⁺)$({10}^{+})$ state can be understood from these calculations if there is a degree of rotational alignment in this band, with the K value being lower than the bandhead spin. However, the validity of the K quantum number with large predicted triaxiality and gamma softness requires further theoretical study.     

Higgs-boson couplings beyond the Standard Model

The implications for Higgs decays of potential new physics beyond the Standard Model (BSM) are considered in the context of effective field theory, assuming perturbative decoupling. Using existing data to restrict which dimension-six operators can arise, it is shown that, given the existing experimental constraints, only a small number of operators can affect the decays of the Higgs: those that may be potentially-tree-generated (PTG) and modify the Higgs–fermion couplings, or those that may be loop-generated (LG) that modify the Higgs couplings to γγ, Zγ and GG  . Implications for specific branching ratios are given in terms of the coefficients of various dimension-six operators. In such a scenario, the ratios Γ(H→WW^?)/Γ(H→ZZ^?)$\Gamma (H\to W{W}^{?})/\Gamma (H\to Z{Z}^{?})$ and Γ(H→W?ν)/Γ(H→Z??)$\Gamma (H\to W?\nu )/\Gamma (H\to Z??)$ equal to their Standard Model values to an accuracy of O(1%)$O(1\text{\%})$ or less.     

Enhanced x-ray emissions from low-density high-Z mixture plasmas generated with intense nanosecond laser

Enhancement of x-ray emissions from laser-produced plasmas is imperative for various applications. Low-density Au–Gd mixture was proposed to enhance the x-ray emissions. X-ray emissions were simulated for the laser-irradiated gold and Au–Gd mixtures with different initial densities. It was shown that 1.34 times conversion efficiency has been achieved for the 0.05 g/cm³$0.05\text{g}/{\text{cm}}^3$ Au–Gd (6/4)$(6/4)$ mixture comparing with the 10 g/cm³$10\text{g}/{\text{cm}}^3$ gold. The enhancement is attributed to higher Rosseland mean opacities of the mixture and reduction of the ion kinetic energy caused by the lower initial density.     

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$\delta m(90\mathrm{\%}\text{C.L.})<1.5\times {10}^{\mathrm{-18}}\text{eV}$.     

Spontaneous Lorentz violation: Non-Abelian gauge fields as pseudo-Goldstone vector bosons

We argue that non-Abelian gauge fields can be treated as the pseudo-Goldstone vector bosons caused by spontaneous Lorentz invariance violation (SLIV). To this end, the SLIV which evolves in a general Yang–Mills type theory with the nonlinear vector field constraint Tr(AμAμ)=±M²$\mathrm{Tr}({\mathit{A}}_{\mu }{\mathit{A}}^{\mu })=\pm M^2$ (M is a proposed SLIV scale) imposed is considered in detail. Specifically, we show that in a theory with an internal symmetry group G having D   generators not only the pure Lorentz symmetry SO(1,3)$\mathit{SO}(1,3)$, but the larger accidental symmetry SO(D,3D)$\mathit{SO}(D,3D)$ of the SLIV constraint in itself appears to be spontaneously broken as well. As a result, although the pure Lorentz violation on its own still generates only one genuine Goldstone vector boson, the accompanying pseudo-Goldstone vector bosons related to the SO(D,3D)$\mathit{SO}(D,3D)$ breaking also come into play properly completing the whole gauge multiplet of the internal symmetry group G taken. Remarkably, they appear to be strictly massless as well, being protected by the starting non-Abelian gauge invariance of the Yang–Mills theory involved. When expressed in terms of the pure Goldstone vector modes, this theory look essentially nonlinear and contains a plethora of Lorentz and CPT violating couplings. However, they do not lead to physical SLIV effects which turn out to be strictly cancelled in all the lowest order processes considered.     

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$[-0.00,+0.09]\text{W}/{\text{m}}^2$.     

High-K multi-quasiparticle states in No

We report results from an experiment on the decay of the high-K isomers in ²⁵⁴No. We have been able to establish the decay from the known high-lying four-quasiparticle isomer, which we assign as a Kπ=¹⁶⁺${\mathrm{K}}^{\pi }={16}^{+}$ state at an excitation energy of Ex=2.928(3) MeV${\mathrm{E}}_x=2.928(3)\text{MeV}$. The decay of this state passes through a rotational band based on a previously unobserved state at Ex=2.012(2) MeV${\mathrm{E}}_x=2.012(2)\text{MeV}$, which we suggest is based on a two-quasineutron configuration with Kπ=¹⁰⁺${\mathrm{K}}^{\pi }={10}^{+}$. This state in turn decays to a rotational band based on the known Kπ=⁸⁻${\mathrm{K}}^{\pi }=8^{-}$ isomer, which we infer must also have a two quasineutron configuration. We are able to assign many new gamma-rays associated with the decay of the Kπ=⁸⁻${\mathrm{K}}^{\pi }=8^{-}$ isomer, including the identification of a highly K-forbidden ΔK=8$\mathrm{\Delta }\mathrm{K}=8$ E1 transition to the ground-state band. These results provide valuable new information on the orbitals close to the Fermi surface, pairing correlations, deformation and rotational response, and K-conservation in nuclei of the deformed trans-fermium region.     

Constraints on sub-GeV hidden sector gauge bosons from a search for heavy neutrino decays

Several models of dark matter motivate the concept of hidden sectors consisting of SU_(3)C×SU_(2)L×U_(1)Y$\mathit{SU}{(3)}_C\times \mathit{SU}{(2)}_L\times U{(1)}_Y$ singlet fields. The interaction between our and hidden matter could be transmitted by new abelian U^′(1)$U^{\prime }(1)$ gauge bosons A^′$A^{\prime }$ mixing with ordinary photons. If such A^′$A^{\prime }$?s with the mass in the sub-GeV range exist, they would be produced through mixing with photons emitted in decays of η   and η^′${\eta }^{\prime }$ neutral mesons generated by the high energy proton beam in a neutrino target. The A^′$A^{\prime }$?s would then penetrate the downstream shielding and be observed in a neutrino detector via their A^′→e⁺e⁻$A^{\prime }\to e^{+}{e}^{-}$ decays. Using bounds from the CHARM neutrino experiment at CERN that searched for an excess of e⁺e⁻$e^{+}{e}^{-}$ pairs from heavy neutrino decays, the area excluding the γ−A^′$\gamma -A^{\prime }$ mixing range 10⁻⁷???10⁻⁴${10}^{-7}???{10}^{-4}$ for the A^′$A^{\prime }$ mass region 1?_MA′?500 MeV$1?M_{A^{\prime }}?500\text{MeV}$ is derived. The obtained results are also used to constrain models, where a new gauge boson X   interacts with quarks and leptons. New upper limits on the branching ratio as small as Br(η→γX)?10⁻¹⁴$\mathrm{Br}(\eta \to \gamma X)?{10}^{-14}$ and Br(η^′→γX)?10⁻¹²$\mathrm{Br}({\eta }^{\prime }\to \gamma X)?{10}^{-12}$ are obtained, which are several orders of magnitude more restrictive than the previous bounds from the Crystal Barrel experiment.     

Decaying hidden gaugino as a source of PAMELA/ATIC anomalies

We study a scenario that a U(1)$\mathrm{U}(1)$ hidden gaugino constitutes the dark matter in the Universe and decays into a lepton and slepton pair through a mixing with a U_(1)B–_L$\mathrm{U}{(1)}_{\mathrm{B}\text{–}\mathrm{L}}$ gaugino. We find that the dark-matter decay can account for the recent PAMELA and ATIC anomalies in the cosmic-ray positrons and electrons without an overproduction of antiprotons.