Narrow States Research Articles

Redox activity of surface oxygen anions in oxygen-deficient perovskite oxides during electrochemical reactions

Surface redox-active centres in transition-metal oxides play a key role in determining the efficacy of electrocatalysts. The extreme sensitivity of surface redox states to temperatures, to gas pressures and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Here we report the direct observation of surface redox processes by surface-sensitive, operando X-ray absorption spectroscopy using thin-film iron and cobalt perovskite oxides as model electrodes for elevated-temperature oxygen incorporation and evolution reactions. In contrast to the conventional view that the transition metal cations are the dominant redox-active centres, we find that the oxygen anions near the surface are a significant redox partner to molecular oxygen due to the strong hybridization between oxygen 2p and transition metal 3d electronic states. We propose that a narrow electronic state of significant oxygen 2p character near the Fermi level exchanges electrons with the oxygen adsorbates. This result highlights the importance of surface anion-redox chemistry in oxygen-deficient transition-metal oxides.

Observation of new states of the 7He isotope

The formation of the 7He heavy isotope has been studied in the 11B(π−, pt)7He, 11B(π−, dd)7He, and 10B(π−, pd)7He reactions of absorption of stopped π− mesons. No indications of the existence of a low-lying level with Ex ∼ 1 MeV have been obtained in any of the three reactions. The existence of three narrow states with excitation energies Ex = 3.1(1), 4.90(15), and 6.65(15) MeV has been proven. Highly excited states with Ex = 16.9(5) MeV, Γ = 1.0(3) MeV, Ex = 19.8(3) MeV, Γ = 1.5(3) MeV, and Ex = 24.8(4) MeV, Γ = 4.6(7) MeV have been identified.

Prediction of a missing higher charmonium around 4.26 GeV in $$J/\psi $$ J / ψ family

Inspired by the similarity of mass gaps of $J/\psi$ and $\Upsilon$ families, the prediction of missing higher charmonium with mass $4263$ MeV and very narrow width is made. In addition, the properties of two charmonium-like states, $X(3940)$ and $X(4160)$, and charmonium $\psi(4415)$ are discussed. Here, $X(3940)$ as $\eta_c(3S)$ is established while the explanation of $X(4160)$ to be $\eta_c(4S)$ is fully excluded and $\eta_c(4S)$ is typically a very narrow state. These predictions can be accessible at BESIII, Belle and BelleII in near future.

Search for the [formula omitted] and other hidden-beauty states in the [formula omitted] channel at ATLAS

This Letter presents a search for a hidden-beauty counterpart of the X(3872) in the mass ranges of 10.05–10.31 GeV and 10.40–11.00 GeV, in the channel Xb→π+π−ϒ(1S)(→μ+μ−), using 16.2 fb−1 of s=8 TeVpp collision data collected by the ATLAS detector at the LHC. No evidence for new narrow states is found, and upper limits are set on the product of the Xb cross section and branching fraction, relative to those of the ϒ(2S), at the 95% confidence level using the CLS approach. These limits range from 0.8% to 4.0%, depending on mass. For masses above 10.1 GeV, the expected upper limits from this analysis are the most restrictive to date. Searches for production of the ϒ(13DJ), ϒ(10860), and ϒ(11020) states also reveal no significant signals.

Spectroscopy of the heavy helium isotope 7He

Three narrow (Γ ≤ 0.5 MeV) low-lying states of 7He with excitation energies of 3.2(1) MeV, 4.9(2) MeV and 6.65(15) MeV are observed simultaneously for the first time in reactions of the absorption of stopped π−-mesons 11B(π−,pt)7He and 11B(π−,dd)7He. No indications of the existence of a level in the area of Ex ∼ 1 MeV are found. Highly excited 7He states with parameters Ex = 19.6(3) MeV, Γ = 1.7(4) MeV and Ex = 25.2(6) MeV, Γ= 4.8(9) MeV are observed.

EPECUR setup for the search for narrow baryon resonances in pion-proton scattering

EPECUR experimental setup is aimed at the search of narrow resonant states by precision measurement of differential and total reaction cross sections of pion-nucleon interaction with 1 MeV pion energy steps. In five years passed from the idea of the experiment till the start of the data taking in April of 2009, a new apparatus was build from scratch at the universal beam line 322 of ITEP proton synchrotron U-10. The setup is essentially a non-magnetic spectrometer with a liquid hydrogen target based on the large aperture drift chambers with hexagonal structure. The unique properties of the beam line allow individual pion momentum measurement with the accuracy better than 0.1%. The momentum tagging is done with 1 mm pitch proportional chambers located in the first focus of the beam line. The design of numerous subsystems of the setup is based on modern electronic components including microprocessors and FPGA. All the subsystems are tuned and tested both individually and as parts of the whole working setup. The distributed data acquisition system uses widely spread USB and Ethernet protocols, which allows to achieve high performance and take full advantage of the industrial solutions.

Interactions between barrier islands and backbarrier marshes affect island system response to sea level rise: Insights from a coupled model

AbstractInteractions between backbarrier marshes and barrier islands will likely play an important role in determining how low‐lying coastal systems respond to sea level rise and changes in storminess in the future. To assess the role of couplings between marshes and barrier islands under changing conditions, we develop and apply a coupled barrier island‐marsh model (GEOMBEST+) to assess the impact of overwash deposition on backbarrier marsh morphology and of marsh morphology on rates of island migration. Our model results suggest that backbarrier marsh width is in a constant state of change until either the backbarrier basin becomes completely filled or backbarrier marsh deposits have completely eroded away. Results also suggest that overwash deposition is an important source of sediment, which allows existing narrow marshes to be maintained in a long‐lasting alternate state (~500 m wide in the Virginia Barrier Islands) within a range of conditions under which they would otherwise disappear. The existence of a narrow marsh state is supported by observations of backbarrier marshes along the eastern shore of Virginia. Additional results suggest that marshes reduce accommodation in the backbarrier bay, which, in turn, decreases island migration rate. As climate change results in sea level rise, and the increased potential for intense hurricanes resulting in overwash, it is likely that these couplings will become increasingly important in determining future system behavior.

Spin wave localization in one-dimensional magnonic microcavity comprising yttrium iron garnet

We demonstrate the localization of magnetostatic surface waves, i.e., spin waves, in a one-dimensional magnonic microcavity substantialized with periodical conductivity modulation. The narrow localized state is observed inside band gaps and is responsible for a sharp transmission peak. The experimental results strongly agree with the theoretical prediction made with the shape magnetic anisotropy of the propagating medium composed of yttrium iron garnet taken into account.

Pion-assisted charmed dibaryon candidate

The ${\mathrm{\ensuremath{\Lambda}}}_{c}(2286)N$ system is studied in a chiral constituent quark model, and the resulting $s$-wave interaction is used in separable form within three-body models of the $\ensuremath{\pi}{\mathrm{\ensuremath{\Lambda}}}_{c}N$ system with quantum numbers $(C,I,{J}^{P})=(+1,\frac{3}{2},{2}^{+})$. Separable interactions are also used for the dominant $p$-wave pion-baryon channels dominated by the $\mathrm{\ensuremath{\Delta}}(1232)$ and ${\mathrm{\ensuremath{\Sigma}}}_{c}(2520)$ resonances. Faddeev equations with relativistic kinematics are solved on the real axis to search for bound states and in the complex plane to search for three-body resonances. Some of the models considered generate a very narrow bound state, requiring isospin violation for its strong decay. Other models lead to a narrow resonance ($\mathrm{\ensuremath{\Gamma}}\ensuremath{\lesssim}0.4\text{ }\text{ }\mathrm{MeV}$) for a resonance mass below the ${\mathrm{\ensuremath{\Sigma}}}_{c}(2455)N$ threshold. This would be the lowest-lying $C=+1$ dibaryon, with mass estimated as $\ensuremath{\approx}3370\ifmmode\pm\else\textpm\fi{}15\text{ }\text{ }\mathrm{MeV}$.

Are there tetraquarks at largeNcin QCD(F)?

Weinberg recently pointed out a flaw in the standard argument that large $N_c$ QCD with color-fundamental quarks [QCD(F)] cannot yield narrow tetraquark states. In particular, he observed that the argument does not rule out narrow tetraquarks associated with the leading-order connected diagrams; such tetraquarks would have a width scaling as $N_c^{-1}$. It is shown here, however, that while the standard analysis of tetraquarks does not rule them out, a more thorough analysis rules out quantum-number exotic tetraquarks associated with the leading-order connected diagrams. This analysis is based entirely on conventional assumptions used in large $N_c$ physics applied to the analytic properties of meson-meson scattering. Our result implies that one of three possibilities must be true: i) quantum-number exotic tetraquarks do not exist at large $N_c$; ii) quantum-number exotic tetraquarks exist, but are associated with subleading connected diagrams and have anomalously small widths that scale as $N_c^{-2}$ or smaller; or iii) the conventional assumptions used in large $N_c$ analysis are inadequate.

Open bottom states and theB¯-meson propagation in hadronic matter

The interaction and propagation of anti-B mesons with light mesons, N and Delta baryons is studied within a unitarized approach based on effective models that are compatible with chiral and heavy-quark symmetries. We find several heavy-quark spin doublets in the open-bottom sectors, where anti-B and anti-B* mesons are present. In the meson sector we find several resonant states, among them, a B0 and a B1 with masses 5530 MeV and 5579 MeV as well as Bs0* and Bs1* narrow states at 5748 MeV and 5799 MeV, respectively. They form two doublets with no experimental identification yet, the first one being the bottom counterpart of the D0(2400) and D1(2430) states, and the second bottom doublet associated to the ubiquitous Ds0* (2317) and the Ds1 (2460). In the baryon sector, several Lambda_b and Sigma_b doublets are identified, among them the one given by the experimental Lambda_b(5910) and Lambda*_b(5921). Moreover, one of our states, the Sigma_b*(5904), turns out to be the bottom counterpart of the Sigma*(1670) and Sigma_c*(2549), which is a case for discovery. We finally analyze different transport coefficients for the anti-B meson in hot matter, such as formed in heavy-ion collisions at RHIC and LHC. For RHIC/LHC energies, the main contribution to the coefficients comes from the interaction of anti-B mesons with pions. However, we also include the effects of baryonic density which might be sizable at temperatures T < 100 MeV, as the chemical potential is expected to increase in the last stages of the expansion. We conclude that although the relaxation time decreases with larger baryonic densities, the anti-B meson does not thermalize at RHIC/LHC energies, representing an ideal probe for the initial bottom distribution.

Rising Powers, Rising Networks: Brazilian Actors in Private Governance

This article analyses Brazilian involvement in private labour and environmental governance. It does so by mapping the local actors participating in three recent international initiatives—the UN Global Compact, the Global Reporting Initiative, and the ISO 26000 Working Group—and exploring the activities of a central group around the Ethos Institute for Business and Social Responsibility. The article argues that the privileged position of this group of actors is supported by the lasting association between a sector of Brazilian business and influential political players, in particular the ruling Workers' Party. On this basis, the article discusses the model of institutional complementarity, suggesting that both the local network and the global initiatives benefited from the narrow state–society relations pervading Brazilian politics. The article contests the claim that emerging economies are necessarily disadvantaged newcomers to private governance, and calls for greater attention to the interface between international initiatives and local political institutions.

The anti-individualist revolution in the philosophy of language

The canonical arguments against the description theory of names are usually taken to have established that the reference of a name as used on a given occasion is not semantically determined by the qualitative descriptions that the speaker may have in mind. The deepest moral of these arguments, on the received view, would be that the speaker’s narrow mental states play no semantic role in fixing reference. My central aim in this paper is to challenge this common understanding by highlighting that the same argumentative schemas can be adapted to undermine a related non-description theory, according to which the reference of a name as used on a given occasion would semantically depend on broad mental states of the speaker. Once this is realised, it becomes evident that the falsity of the description theory is not the deepest lesson of the canonical arguments, but only a consequence of the deepest lesson. The most fundamental moral is that the speaker’s mental states, whether narrow or broad, do not always determine linguistic reference.

Tetraquarks with exotic flavor quantum numbers at largeNcin QCD(AS)

It is shown that the large $N_c$ limit of QCD with quarks in the two-index antisymmetric color representation [QCD(AS)] has narrow tetraquark states with exotic flavor quantum numbers. They decay into mesons with a width that is parametrically $O(1/N_c^2)$. Tetraquarks with non-exotic quantum numbers mix at leading order with mesons of the same overall quantum numbers. QCD(AS) at $N_c=3$ corresponds to ordinary QCD; its large $N_c$ limit represents an alternative starting point for a $1/N_c$ expansion to the standard one with quarks in the fundamental color representation.

Calculation of the Mass of X(3872) by the Mandelstam Generalization of the Gell—Mann—Low Method

On the basis of assuming that the narrow state X(3872) is a molecule state consisting of D0 and D̄*0, we apply the Mandelstam generalization of the Gell—Mann—Low method to calculate the matrix element of quark current between the heavy meson states described by Bether—Salpeter wave function. In calculation of the matrix element of quark current the operator product expansion is used in order to include the nonperturbative contribution of the vacuum condensates. In this scheme we calculate the mass of X(3872). We believe that this scheme is closer to QCD than the previous work.

In-medium ηN interactions and η nuclear bound states

The in-medium Eta-N interaction near and below threshold is constructed from a free-space chirally-inspired meson-baryon coupled-channel model that captures the physics of the N(1535) baryon resonance. Nucleon Pauli blocking and hadron self-energies are accounted for. The resulting energy dependent in-medium interaction is used in self-consistent dynamical calculations of Eta nuclear bound states. Narrow states of width about or less than 2 MeV are found across the periodic table, beginning with A=10, for this in-medium coupled-channel interaction model. The binding energy of the 1s-Eta state increases with A, reaching a value of B(1s-Eta) about 15 MeV. The implications of our self-consistency procedure are discussed with respect to procedures used in other works.

Search for Signatures of New Heavy Top Quark of the Fourth Generation at the Hadron Colliders

The Fourth Generation and Vector Like Quark (VLQ) models are extensions of the Standard Model of particles physics. These models predict the existence of new heavy quarks like heavy top quark t' with electric charge 2/3 and heavy bottom quark b' with electric charge -1/3. The t' and b' will act the fourth generation quarks. In current work we present a search for a pair production of a fourth generation quark, t' quark and its antiparticle, followed by their decays to Z, W bosons followed by decays to trilepton plus jets and missing transverse energy in the final state according to the process . We use Monte Carlo simulation techniques Pythia8, MadGraph5 and CalcHEP to simulate this process at both the Large Hadron Collider at CERN (proton-proton collisions) and the Fermilab Tevatron Collider (proton-antiproton collisions). We assume that the t' quark is a narrow state that always decay to a W and Z bosons plus jets. We select 2 electrons + jets+ missing energy final states with one isolated with high transverse momentum. The three charged leptons plus missing energy in the final state offer the best discovery potential at the hadron colliders for new heavy top quark mass of 500 GeV. We study the possible signals at both the LHC and the Tevatron of new quarks t' coupled to the third generation quarks in the context of fourth generation and vector like quark models under the assumption of a branching ratios and . Heavy quark pair production gives interesting signals in final states with three charged leptons plus missing energy. Finally, from our analysis the new heavy fourth generation quark t' can be discovered at both the Tevatron and the LHC with mass 500 GeV.

Mobilizing Labor &amp; Engineering Development: The Politics of Expanding Welfare Coverage in the Postwar Period

Expanding population coverage is an inherently political process that has often been overlooked in the study of welfare state development. This paper examines the politics of expanding welfare coverage, focusing on developing countries in the postwar period. Through comparative case studies of welfare reform in Brazil, China, and India, two political variables are identified as important: economic development strategies and the mobilization of labor. Labor often plays a contradictory role in welfare reform, supporting the adoption of new programs, but opposing the expansion of coverage. Orthodox macroeconomic policies and the preferential incorporation of labor both contribute to the development of narrow welfare states with limited population coverage.

Search for baryonium and the physics at FAIR

The existence of nucleon-antinucleon quasi-bound state is indicated in two decay modes of the J/psi meson studied by BES. We discuss an explanation in a fairly traditional Paris-potential model of the nucleon-antinucleon interactions. A broad, S-wave and a narrow P-wave quasi-bound states are predicted by this model. Some existing experimental evidence and possible verifications in the future are indicated.

5D perspective on Higgs production at the boundary of a warped extra dimension

A comprehensive, five-dimensional calculation of Higgs-boson production in gluon fusion is performed for both the minimal and the custodially protected Randall-Sundrum (RS) model, with Standard Model fields propagating in the bulk and the scalar sector confined on or near the IR brane. For the first time, an exact expression for the gg->h amplitude in terms of the five-dimensional fermion propagator is derived, which includes the full dependence on the Higgs-boson mass. Various results in the literature are reconciled and shown to correspond to different incarnations of the RS model, in which the Higgs field is either localized on the IR brane or is described in terms of a narrow bulk state. The results in the two scenarios differ in a qualitative way: the gg->h amplitude is suppressed in models where the scalar sector is localized on the IR brane, while it tends to be enhanced in bulk Higgs models. In both cases, effects of higher-dimensional operators contributing to the gg->h amplitude at tree level are shown to be numerically suppressed under reasonable assumptions. There is no smooth cross-over between the two scenarios, since the effective field-theory description breaks down in the transition region. A detailed phenomenological analysis of Higgs production in various RS scenarios is presented, and for each scenario the regions of parameter space already excluded by LHC data are derived.