Search for electric dipole moments of light ions in storage rings

The Standard Model (SM) of Particle Physics is not capable to account for the apparent matterantimatter asymmetry of our Universe. Physics beyond the SM is required and is searched for by (i) employing highest energies (e.g., at LHC), and (ii) striving for ultimate precision and sensitivity (e.g., in the search for electric dipole moments (EDMs)). Permanent EDMs of particles violate both time reversal (T) and parity (P) invariance, and are via the CPT-theorem also CP-violating. Finding an EDM would be a strong indication for physics beyond the SM, and pushing upper limits further provides crucial tests for any corresponding theoretical model, e.g., SUSY. Direct searches of proton and deuteron EDMs bear the potential to reach sensitivities beyond 10^?29 e cm. For an all-electric proton storage ring, this goal is pursued by the US-based srEDM collaboration [2], while the newly found Julich-based JEDI collaboration [1] is pursuing an approach using a combined electric-magnetic lattice which shall provide access to the EDMs of protons, deuterons, and ³He ions in the same machine. In addition, JEDI has recently proposed to perform a direct measurement of the proton and/or deuteron EDM at COSY using resonant techniques involving Wien filters.     

Phase transitions in RbCaF3. II: Neutron scattering

The 196 K phase transition of RbCaF₃ has been identified as a phonon condensation at the R point (cubic [111] zone boundary). Above the transition temperature, a ridge of scattering extending from the [110] zone boundary (M point) to the R point was observed, corresponding to a line of soft phonons from M₃ to R₂₅. Below the transition the scattering at M decreases rapidly with temperature, indicating a lattice stabilization which causes the ridge of scattering to disappear.     

Can extra dimensions accessible to the SM explain the recent measurement of anomalous magnetic moment of the muon?

We investigate whether models with flat extra dimensions in which SM fields propagate can give a significant contribution to the anomalous magnetic moment of the muon (MMM). In models with only SM gauge and Higgs fields in the bulk, the contribution to the MMM from Kaluza–Klein (KK) excitations of gauge bosons is very small. This is due to the constraint on the size of the extra dimensions from tree-level effects of KK excitations of gauge bosons on precision electroweak observables such as Fermi constant. If the quarks and leptons are also allowed to propagate in the (same) bulk (“universal” extra dimensions), then there are no contributions to precision electroweak observables at tree-level. However, in this case, the constraint from one-loop contribution of KK excitations of (mainly) the top quark to T parameter again implies that the contribution to the MMM is small. We show that in models with leptons, electroweak gauge and Higgs fields propagating in the (same) bulk, but with quarks and gluon propagating in a sub-space of this bulk, both the above constraints can be relaxed. However, with only one Higgs doublet, the constraint from the process b→sγ requires the contribution to the MMM to be smaller than the SM electroweak correction. This constraint can be relaxed in models with more than one Higgs doublet.     

Probing new physics from top quark FCNC processes at linear colliders: a mini review

We briefly review the studies on the top quark FCNC processes at a next-generation linear collider. Such processes, including various FCNC top quark rare decays and top-charm associated productions, are extremely suppressed in the standard model (SM) but could be significantly enhanced in some extensions. We compared the predictions from different typical new physics models: the SM, the minimal supersymmetric model (MSSM), the general two-higgs-doublet model (2HDM), and the topcolor-assisted technicolor (TC2) model. Our conclusion is: (1) While all the new physics models can enhance the rates by several orders relative to the SM predictions, the TC2 model predicts much larger rates than other models; (2) The optimal channel for probing the top quark FCNC is the top-charm associated production in γγ collision, which occurs at a much higher rate than e⁺e⁻ or e⁻γ collision and can reach the detectable level for a large part of the parameter space.     

Analysis of the Λb → Λ?+?? transition in the SM4 using form factors from full QCD

Using the responsible form factors calculated via full QCD, we analyze the ?? _b ?? ???⁺?^? transition in the standard model containing fourth-generation quarks (SM4). We discuss the effects of the presence of the t?? fourth-family quark on related observables like branching ratio, forward-backward asymmetry, baryon polarization as well as double-lepton polarization asymmetries. We also compare our results with those obtained in the SM as well as with predictions of the SM4 but using form factors calculated within heavy-quark effective theory. The obtained results on the branching ratio indicate that the ? transition is more probable in full QCD comparing to the heavy-quark effective theory. It is also shown that the results on all considered observables in the SM4 deviate considerably from the SM predictions when m _t?? ?? 400 GeV.     

Employing Higgs boson production at photon colliders to discriminate between the two Higgs doublet model and the standard model in the process <Emphasis Type="Italic">eγ</Emphasis> → <Emphasis Type="Italic">eh</Emphasis>

The possibility of employing experiments at photon colliders to discriminate between various models of electroweak-symmetry breaking is discussed for the case where experiments at LHC and at future linear electron-positron colliders reveal no disagreement with the predictions of the Standard Model (SM)—that is, the case of an SM-like scenario. The two Higgs boson doublet model (2HDM) is considered as an alternative to the SM. A comparison of the cross sections obtained for the process eγ → eh within the SM and the natural 2HDM shows that investigation of this cross section would make it possible to discriminate between these models of electroweak-symmetry breaking reliably and to confirm or disprove the results obtained by studying the reaction γγ → h.     

Pseudoscalar Higgs bosons at the LHC: production and decays into electroweak gauge bosons revisited

We analyse and compute, within a number of standard model (SM) extensions, the cross sections σ _A→VV′ for the production of a heavy neutral pseudoscalar Higgs-boson/spin-zero resonance at the LHC and its subsequent decays into electroweak gauge bosons. For comparison we calculate also the corresponding cross sections for a heavy scalar. The SM extensions we consider include a type-II two-Higgs doublet model (2HDM), a 2HDM with four chiral fermion generations, the minimal supersymmetric extension of the SM (MSSM), and top-colour assisted technicolour models. Presently available phenomenological constraints on the parameters of these models are taken into account. We find that, with the exception of the MSSM, these models permit the LHC cross sections σ _A→VV′ to be of observable size. That is, a pseudoscalar resonance may be observable, if it exists, at the LHC in its decays into electroweak gauge bosons, in particular in WW and γ γ final states.     

An unusualM1 electromagnetic transition connecting octupole and quadrupole vibrations in179Hf

A detailed level scheme for¹⁷⁹Hf has been constructed on the basis of extensive (n, γ), (d, p) and (d, t) data. The low lying levels are grouped into 15 rotational bands of which 14 are classified by Nilsson quantum numbers or vibrational configurations. One of the most interesting results concerns a dominant transition matrix element which connects an octupole vibration built on the 1/2[510] Nilsson orbit with a quadrupole vibration built on the 9/2⁺ [624] Nilsson ground state. A simple interpretation of this unusual decay mode is offered in terms of microscopic wave functions for the vibrational states. This interpretation leads to reasonable estimates forE1 hindrance factors from the octupole vibration to lower lying quasi-particle levels.     

On the geometry and homology of certain simple stratified varieties

We study certain mild degenerations of algebraic varieties which appear in the analysis of a large class of supersymmetric theories, including superstring theory. We analyze Witten’s σ-model [Nucl. Phys. B 403 (1993) 159] and find that the non-transversality of the superpotential induces additional singularities and a stratification of the ground state variety. This stratified variety admits certain homology groups such that ⊕_qH^2q satisfies the “Kähler package” of requirements [Ann. Math. Studies 102 (1982) 303]. Also, this ⊕_qH^2q extends the “flopped” pair of small resolutions [Nucl. Phys. B 416 (1994) 414; Nucl. Phys. B 330 (1990) 49; Commun. Math. Phys. 119 (1988) 431] to an “(exo)flopped” triple, and is compatible with both mirror symmetry [S.-T. Yau (Ed.), Mirror Manifolds, International Press, Hong Kong, 1990; B. Greene, S.-T. Yau (Eds.), Mirror Manifolds II, International Press, Hong Kong, 1996] and string theory [Mod. Phys. Lett. A 12 (1997) 521; Nucl. Phys. B 451 (1995) 96] results. Finally, we revisit the conifold transition [Nucl. Phys. B 330 (1990) 49] as it applies in our formalism.     

Piezospectroscopic investigation of the nature of the subsidiary valence band extrema in TiO2

In order to assess the localization in k-space of the secondary valence band extrema, we have measured the stress dependence of the indirect transition of TiO₂, at 1.6 K, for static uniaxial compression along the [100] and [110] directions. From the stress-induced splittings we localize the secondary valence-band extrema in [100] direction (Δ direction) and associate the indirect gap of TiO₂ with a Δ_4v → Γ_1c phonon-assisted transition. The shear deformation potential of the Δ_4v valence band has been determined from the stress-induced splitting of the TA phonon-assited transition. We find |C_Δ4v| = 0.75 eV.     

The four quasi-particle 178Hf isomeric state,its excitation energy and multipolarities of deexciting transitions

The decay properties of the 31 y ¹⁷⁸Hf isomeric state have been investigated by means of a Ge(Li)-NaI(Tl) Compton suppression device and a Si(Li) detector, as well as with Ge(Li) and Ge(Li), intrinsic Ge and Si(Li) coincidence arrangements. From the E3 character of the unobserved isomeric transition (11.7 ≦ E_IT ≦ 16.7 keV), deduced from L-subshell and M/L ratios, I^π, K of the isomeric level was determined as 16⁺, 16. The {p[404] ↓ + p1514] ↑ + n[514] ↓ + n[624]↑}_16⁺ + four quasi-particle configuration was assigned to this level at 2447.5 ± 2.5 keV. As proposed earlier the isomeric E3 transition decays to the 13^? level of the band built upon the I^π = 8^? isomer. The |g_K?g_R| values derived from $\text{E}\text{2}\text{M}\text{1}$ ratios of interband transitions show that the 8^? isomer contains about 36 % of the p[404] ↓ + p[514] ↑ configuration and about 64 % of the n[624] ↑ + n[514] ↓ configuration.     

Near-infrared LIF spectroscopy of HfF

The molecular ion HfF⁺ is the chosen species for a JILA experiment to measure the electron electric dipole moment (eEDM). Detailed knowledge of the spectrum of HfF is crucial to prepare HfF⁺ in a state suitable for performing an eEDM measurement [1]. We investigated the near-infrared electronic spectrum of HfF using laser-induced fluorescence (LIF) of a supersonic molecular beam. We discovered eight unreported bands, and assign each of them unambiguously, four to vibrational bands belonging to the transition [13.8]0.5 ← X1.5, and four to vibrational bands belonging to the transition [14.2]1.5 ← X1.5. Additionally, we report an improved measurement of vibrational spacing of the ground state, as well as anharmonicity ω_ex_e.     

23Na NMR study of the local order in the Na1/2Bi1/2TiO3 structure in a weak magnetic field

The orientation dependences of the second-order quadrupole shifts of the central component in the ²³Na NMR spectrum were studied in the temperature range 293–760 K. The profile of the spectral distribution is calculated using various models of the Na_1/2Bi_1/2TiO₃ structure. The calculations agree with the experimental data for the monoclinic structure of a polar cluster with two Na displacement components: a displacement along the [111] _p direction and a small displacement statistically or dynamically disordered over six equally probable [100] _p -type directions. Tetragonal-phase nuclei and monoclinic clusters with a very small displacement component along the [111] _p direction are found to coexist and have close energies over the temperature range 580–610 K. The results obtained provide new information concerning the character of the diffuse phase transition at 610 K.     

Low-wavenumber turbulent boundary layer wall-pressure measurements from vibration data on a cylinder in pipe flow

The response of a structure to turbulent boundary layer (TBL) excitation has been an area of research for roughly 50 years, although uncertainties persist surrounding the low-wavenumber levels of the TBL surface pressure spectrum. In this experimental investigation, a cylindrical shell with a smooth internal surface is subjected to TBL excitation from water in fully developed pipe flow. The cylinder's vibration response to this excitation is used to determine low-wavenumber TBL surface pressure levels at lower streamwise wavenumbers than previously reported (k₁/k_c<0.01). An experimental modal analysis is also conducted on the water-filled cylindrical shell to determine structural parameters which are used to extract TBL pressures. The measured low-wavenumber pressure data falls midway between TBL models by Smol’yakov [Acoustical Physics 52(3) (2006) 331-337] and Chase [Journal of Sound and Vibration 112(1) (1987) 125-147] and is roughly 23 dB lower than an early TBL model by Corcos [Journal of the Acoustical Society of America 35(2) (1963) 192-198]. The current data is a few decibels below the lower bound of related measurements in air by Farabee and Geib [ICIASF ‘75 Record, 1975, pp. 311-319] and Martin and Leehey [Journal of Sound and Vibration 52(1) (1977) 95-120]. A simple wavenumber white form for the TBL surface pressure spectrum at low-wavenumber is suggested.     

Isomeric state at 945.3 keV in237Np

A new isomeric state in²³⁷Np has been discovered at an excitation energy of (945.3±0.2) keV withT _1/2 =(711±40) ns. Six gamma-ray lines have been measured depopulating the isomeric state to known levels in²³⁷Np. The comparison of the measured absolute gamma-ray transition probabilities with empirical values yields as most probable spinI andK assignmentI=K=13/2 for this isomeric state. It is most likely a 1-proton-2-neutron quasiparticle state 13/2^?π5/2⁺ [642] +ν7/2^? [743] + ν 1/2⁺ [631]. However, a one-quasiparticle 11/2^? [505] configuration for the isomer cannot be excluded.     

The supersymmetric Standard Models with decaying and stable dark matters

We propose two supersymmetric Standard Models (SMs) with decaying and stable dark matter (DM) particles. To explain the SM fermion masses and mixings and have a heavy decay DM particle S, we consider the Froggatt–Nielsen mechanism by introducing an anomalous U(1) _X gauge symmetry. Around the string scale, the U(1) _X gauge symmetry is broken down to a Z ₂ symmetry under which S is odd while all the SM particles are even. S obtains a vacuum expectation value around the TeV scale, and then it can three-body decay dominantly to the second/third family of the SM leptons in Model I and to the first family of the SM leptons in Model II. Choosing a benchmark point in the constrained minimal supersymmetric SM with exact R parity, we show that the lightest neutralino DM is consistent with the CDMS II experiment. Considering S three-body decay and choosing suitable parameters, we show that the PAMELA and Fermi-LAT experiments and the PAMELA and ATIC experiments can be explained in Model I and Model II, respectively.     

Isotope shifts in Sm II and changes in mean-square nuclear charge radii of the stable even Sm isotopes

Isotope shifts have been measured in Sm II from which the shifts between pure configurations 4f ⁶ s and 4f ⁶5d can be determined. The specific mass shift for such a “transition” was estimated to be (?1±2)mK for a change of two neutrons. The values derived for the change in the nuclear charge distribution,δ〈r ²〉, are in good agreement with the results obtained from isotope shift measurements in Sm I (H. Brand et al.: J. Phys. B11, L99, 1978). The weighted mean values representing the best information onδ〈r ²〉 presently available are in fm²: [144, 148] 0.488(23); [148, 150] 0.285(14); [150, 152] 0.400(19); [152, 154] 0.217(11).     

Synthesis, X-ray structure, EPR and optical properties of a ferrocene substituted polychlorotriphenylmethyl radical

The optical, magnetic and electrochemical properties of the octamethylferrocene aldehyde substituted polychlorotriphenylmethyl radical 1 are reported. Radical 1 is prepared in a three step synthetic route starting with a Wittig-Horner reaction to yield (E)-1-formyl-1′-{2-{4-[bis(2,3,4,5,6-pentachlorophenyl)methyl]-2,3,5,6-tetrachloro phenyl}ethen-1-yl}-2,2′,3,3′,4,4′,5,5′-octamethyl ferrocene (6), which is subsequently deprotonated to yield the corresponding anion 7 and finally oxidized to (E)-4-[2-(1′-formyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocen)ethen-1-yl]-2,3,5,6-tetrachlorophenyl-bis(2,3,4,5,6-pentachlorophenyl)methyl radical (1). Radical 1 exhibits a charge-transfer band transition in the near infrared region which is associated with an intramolecular electron transfer from the ferrocene unit (donor) to the radical unit (acceptor) of this dyad molecule. The X-ray crystal structure of [K⁺(18-crown-6)] (E)-[4-[2-(1′-formyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocen)ethen-1-yl]-2,3,5,6-tetrachlorophenyl-bis(2,3,4,5,6-pentachlorophenyl) methide] (7) has been determined. This organic salt shows an interesting one-dimensional polymeric structure formed by the coordination of the K⁺ cation with several atoms of the organic carbanion.     

Characterization of the photolyase-like iron sulfur protein PhrB from Agrobacterium tumefaciens by Mössbauer spectroscopy

High field Mössbauer spectroscopy has been used to characterize the [4Fe-4S] ^{2 +}cluster of the protein PhrB from Agrobacterium tumefaciens which belongs to the cryptochrome/photolyase family (CPF) and which biological function has previously been shown to be DNA repair. Mössbauer spectra taken of the as prepared protein reveal δ = 0. 42 mms ^{? 1}, and Δ E _Q = 1. 26 mms ^{? 1}as well as an asymmetry parameter of η = 0. 8. These parameters are characteristic for a ferredoxin-type [4Fe-4S] ^{2 +}cluster. In order to investigate whether this cluster is involved in DNA-repair the protein has also been studied in its photoactivated state during DNA binding. The so obtained data sets exhibit essentially the same Mössbauer parameters as those of the non-activated PhrB. This indicates that during DNA repair the [4Fe-4S] ^{2 +}cluster of PhrB has no significant amounts of transition states which have conformational changes compared to the resting state of the protein and which have life times of several seconds or longer.     

Large spontaneous Hall angle in [Co,CoFe/Pt] multilayer

We have quantitatively investigated the Hall effect in [Co, CoFe/Pt] multilayer films. The [Co, CoFe/Pt] multilayers exhibit large spontaneous Hall resistivity (ρ_H) and Hall angle (ρ_H/ρ). Even though the Hall resistivity in [Co, CoFe/Pt] multilayer films (2.7–4 × 10⁻⁷ Ω cm) is smaller than that of amorphous RE–TM alloy films which show large spontaneous Hall resistivity (<2 × 10⁻⁶ Ω cm), the Hall angle of multilayer (6–8%) is almost twice than that in amorphous rare earth–transition metal alloy films (∼3%). The Hall angle provides evidence of the effects of the exchange interaction of the Hall scattering. The exchange is between conduction electron spins and the localized spins of the transition metal. The large Hall angle of [Co, CoFe/Pt] multilayer can be considered due to the high spin polarization and high Curie temperature of Co and CoFe transition metal layers. Even though the role of interfaces and surfaces in the magnetic properties of multilayer films may dominate that of the bulk, the Hall effects in [Co, CoFe/Pt] multilayer may be mainly dominated by the bulk effect.