bluuebunny/crossref_metadata_2025 huggingface dataset:
Isocyanogen formation in the cold interstellar medium
Authors: Vastel C. , Loison J. C. , Wakelam V. , Lefloch B.
Published: April 2019

Context. Cyanogen (NCCN) is the simplest member of the dicyanopolyynes group, and has been proposed as a major source of the CN radical observed in cometary atmospheres. Although not detected through its rotational spectrum in the cold interstellar medium, this very stable species is supposed to be very abundant.

Aims. The chemistry of cyanogen in the cold interstellar medium can be investigated through its metastable isomer, CNCN (isocyanogen). Its formation may provide a clue on the widely abundant CN radical observed in cometary atmospheres.

Methods. We performed an unbiased spectral survey of the L1544 proto-typical prestellar core, using the IRAM-30 m and have analysed, for this paper, the nitrogen chemistry that leads to the formation of isocyanogen. We report on the first detection of CNCN, NCCNH+, C3N, CH3CN, C2H3CN, and H2CN in L1544. We built a detailed chemical network for NCCN/CNCN/HC2N2+ involving all the nitrogen bearing species detected (CN, HCN, HNC, C3N, CNCN, CH3CN, CH2CN, HCCNC, HC3N, HNC3, H2CN, C2H3CN, HCNH+, HC3NH+) and the upper limits on C4N, C2N. The main cyanogen production pathways considered in the network are the CN + HNC and N + C3N reactions.

Results. The comparison between the observations of the nitrogen bearing species and the predictions from the chemical modelling shows a very good agreement, taking into account the new chemical network. The expected cyanogen abundance is greater than the isocyanogen abundance by a factor of 100. Although cyanogen cannot be detected through its rotational spectrum, the chemical modelling predicts that it should be abundant in the gas phase and hence might be traced through the detection of isocyanogen. It is however expected to have a very low abundance on the grain surfaces compared to HCN.
Obscured AGN at 1.5 <z< 3.0 from the zCOSMOS-deep Survey
Authors: Mignoli M. , Feltre A. , Bongiorno A. , Calura F. , Gilli R. , Vignali C. , Zamorani G. , Lilly S. J. , Le Fèvre O. , Bardelli S. , Bolzonella M. , Bordoloi R. , Le Brun V. , Caputi K. I. , Cimatti A. , Diener C. , Garilli B. , Koekemoer A. M. , Maier C. , Mainieri V. , Peng Y. , Pérez Montero E. , Silverman J. D. , Zucca E.
Published: April 2019

Context. The physics and demographics of high-redshift obscured active galactic nuclei (AGN) is still scarcely investigated. New samples of such objects, selected with different techniques, can provide useful insights into their physical properties.

Aims. With the goal to determine the properties of the gas in the emitting region of type 2 AGN, in particular, the gas metal content, we exploit predictions from photoionization models, including new parameterizations for the distance of gas distribution from the central source and internal microturbulence in the emitting clouds, to interpret rest-frame UV spectral data.

Methods. We selected a sample of 90 obscured (type 2) AGN with 1.45 ≤z≤ 3.05 from the zCOSMOS-deep galaxy sample by 5σdetection of the high-ionization C IVλ1549 narrow emission line. This feature in a galaxy spectrum is often associated with nuclear activity, and the selection effectiveness has also been confirmed by diagnostic diagrams based on utraviolet (UV) emission-line ratios. We applied the same selection technique and collected a sample of 102 unobscured (type 1) AGN. Taking advantage of the large amount of multiband data available in the COSMOS field, we investigated the properties of the C IV-selected type 2 AGN, focusing on their host galaxies, X-ray emission, and UV emission lines. Finally, we investigated the physical properties of the ionized gas in the narrow-line region (NLR) of this type 2 AGN sample by combining the analysis of strong UV emission lines with predictions from photoionization models.

Results. We find that in order to successfully reproduce the relative intensity of UV emission lines of the selected high-ztype 2 AGN, two new ingredients in the photoionization models are fundamental: small inner radii of the NLR (≈90 pc forLAGN = 1045erg s−1), and the internal dissipative microturbulence of the gas-emitting clouds (withvmicr≈ 100 km s−1). With these modified models, we compute the gas-phase metallicity of the NLR, and our measurements indicate a statistically significant evolution of the metal content with redshift. Finally, we do not observe a strong relationship between the NLR gas metallicity and the stellar mass of the host galaxy in our C IV-selected type 2 AGN sample.
Inclination effects on the X-ray emission of Galactic black-hole binaries
Authors: Reig Pablo , Kylafis Nikolaos D.
Published: April 2019

Context. Galactic black-hole X-ray binaries (BHBs) emit a compact, optically thick, mildly relativistic radio jet when they are in hard and hard-intermediate states. In these states, BHBs exhibit a correlation between the time lag of hard with respect to softer photons and the photon index of the power law component that characterizes the X-ray spectral continuum above ∼10 keV. The correlation, however, shows large scatter. In recent years, several works have brought to light the importance of taking into account the inclination of the systems to understand the X-ray and radio phenomenology of BHBs.

Aims. Our objective is to investigate the role that the inclination plays on the correlation between the time lag and photon index.

Methods. We obtained RXTE energy spectra and light curves of a sample of BHBs with different inclination angles. We computed the photon index and the time lag between hard and soft photons and performed a correlation and linear regression analysis of the two variables. We also computed energy spectra and light curves of BHBs using the Monte Carlo technique that reproduces the process of Comptonization in the jet. We account for the inclination effects by recording the photons that escape from the jet at different angles. From the simulated light curves and spectra we obtained model-dependent photon index and time lags, which we compared with those obtained from the real data.

Results. We find that the correlation between the time lag and photon index is tight in low-inclination systems and becomes weaker in high-inclination systems. The amplitude of the lags is also larger at low- and intermediate-inclination angles than at high inclination. We also find that the photon index and time lag, obtained from the simulated spectra and light curves, also follow different relationships for different inclination angle ranges. Our jet model reproduces the observations remarkably well. The same set of models that reproduces the correlation for the low-inclination systems, also accounts for the correlation for intermediate- and high-inclination systems fairly well.

Conclusions. The large dispersion observed in the time lag – photon index correlation in BHBs can naturally be explained as an inclination effect. Comptonization in the jet explains the steeper dependence of the lags on the photon index in low- and intermediate-inclination systems than in high-inclination systems.
Excitation and charge transfer in low-energy hydrogen atom collisions with neutral carbon and nitrogen
Authors: Amarsi A. M. , Barklem P. S.
Published: April 2019

Low-energy inelastic collisions with neutral hydrogen atoms are important processes in stellar atmospheres, and a persistent source of uncertainty in non-LTE modelling of stellar spectra. We have calculated and studied excitation and charge transfer of C I and of N I due to such collisions. We used a previously presented method that is based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions for the adiabatic potential energies, combined with the multichannel Landau-Zener model for the collision dynamics. We find that charge transfer processes typically lead to much larger rate coefficients than excitation processes do, consistent with studies of other atomic species. Two-electron processes were considered and lead to non-zero rate coefficients that can potentially impact statistical equilibrium calculations. However, they were included in the model in an approximate way, via an estimate for the two-electron coupling that was presented earlier in the literature: the validity of these data should be checked in a future work.
Elemental composition in quiescent prominences
Authors: Parenti S. , Del Zanna G. , Vial J.-C.
Published: April 2019

Context. The first ionization potential (FIP) bias is currently used to trace the propagation of solar features ejected by the wind and solar eruptions (coronal mass ejections). The FIP bias also helps us to understand the formation of prominences, as it is a tracer for the solar origin of prominence plasma.

Aims. This work aims to provide elemental composition and FIP bias in quiescent solar prominences. This is key information to link these features to remnants of solar eruptions measured in-situ within the heliosphere and to constrain the coronal or photospheric origin of prominence plasma.

Methods. We used the differential emission measure technique to derive the FIP bias of two prominences. Quiet Sun chromospheric and transition region data were used to test the atomic data and lines formation processes. We used lines from low stage of ionization of Si, S, Fe, C, N, O, Ni, Mg, and Ne, constraining the FIP bias in the range 4.2 ≤ log T ≤ 5.8. We adopted a density-dependent ionization equilibrium.

Results. We showed that the two prominences have photospheric composition. We confirmed a photospheric composition in the quiet Sun. We also identified opacity and/or radiative excitation contributions to the line formation of a few lines regularly observed in prominences.

Conclusions. With our results we thus provide important elements for correctly interpreting the upcoming Solar Orbiter/SPICE spectroscopic data and to constrain prominence formation.
Observational evidence of third dredge-up occurrence in S-type stars with initial masses around 1 M⊙
Authors: Shetye S. , Goriely S. , Siess L. , Van Eck S. , Jorissen A. , Van Winckel H.
Published: April 2019

Context. S stars are late-type giants with spectra showing characteristic molecular bands of ZrO in addition to the TiO bands typical of M stars. Their overabundance pattern shows the signature of s-process nucleosynthesis. Intrinsic, technetium (Tc)-rich S stars are the first objects on the asymptotic giant branch (AGB) to undergo third dredge-up (TDU) events. Exquisite Gaia parallaxes now allow for these stars to be precisely located in the Hertzsprung–Russell (HR) diagram. Here we report on a population of low-mass, Tc-rich S stars previously unaccounted for by stellar evolution models.

Aims. Our aim is to derive parameters for a sample of low-mass, Tc-rich S stars and then, by comparing their location in the HR diagram with stellar evolution tracks, to derive their masses and to compare their measured s-process abundance profiles with recently derived STAREVOL nucleosynthetic predictions for low-mass AGB stars.

Methods. Stellar parameters were obtained using a combination of HERMES high-resolution spectra, accurate Gaia Data Release 2 (Gaia-DR2) parallaxes, stellar-evolution models, and newly designed MARCS model atmospheres for S-type stars.

Results. We report on six Tc-rich S stars lying close to the 1 M⊙ (initial mass) tracks of AGB stars of the corresponding metallicity and above the predicted onset of TDU, as expected. This provides direct evidence for TDUs occurring in AGB stars with initial masses as low as ∼1 M⊙ and at low luminosity, that is, at the start of the thermally pulsing AGB. We present AGB models producing TDU in those stars with [Fe/H] in the range −0.25 to −0.5. There is reasonable agreement between the measured and predicted s-process abundance profiles. For two objects however, CD −29°5912 and BD +34°1698, the predicted C/O ratio and s-process enhancements do not simultaneously match the measured ones.
Photodissociation of CO in the outflow of evolved stars
Authors: Saberi M. , Vlemmings W. H. T. , De Beck E.
Published: April 2019

Context. Ultraviolet (UV) photodissociation of carbon monoxide (CO) controls the abundances and distribution of CO and its photodissociation products. This significantly influences the gas-phase chemistry in the circumstellar material around evolved stars. A better understanding of CO photodissociation in outflows also provides a more precise estimate of mass-loss rates.

Aims. We aim to update the CO photodissociation rate in an expanding spherical envelope assuming that the interstellar radiation field (ISRF) photons penetrate through the envelope. This will allow us to precisely estimate the CO abundance distributions in circumstellar envelope around evolved stars.

Methods. We used the most recent CO spectroscopic data to precisely calculate the depth dependency of the photodissociation rate of each CO dissociating line. We calculated the CO self- and mutual-shielding functions in an expanding envelope. We investigated the dependence of the CO profile on the five fundamental parameters mass-loss rate, the expansion velocity, the CO initial abundance, the CO excitation temperature, and the strength of the ISRF.

Results. Our derived CO envelope size is smaller than the commonly used radius derived by Mamon et al. (1988, ApJ, 328, 797). The difference between results varies from 1 to 39% and depends on the H2 and CO densities of the envelope. We list two fitting parameters for a large grid of models to estimate the CO abundance distribution. We demonstrate that the CO envelope size can differ between outflows with the same effective content of CO, but different CO abundance, mass-loss rate, and the expansion velocity as a consequence of differing amounts of shielding by H2 and CO.

Conclusions. Our study is based on a large grid of models employing an updated treatment of the CO photodissociation, and in it we find that the abundance of CO close to the star and the outflow density both can have a significant effect on the size of the molecular envelope. We also demonstrate that modest variations in the ISRF can cause measurable differences in the envelope extent.
Is there more than meets the eye? Presence and role of sub-micron grains in debris discs
Authors: Thebault P. , Kral Q.
Published: April 2019

Context. The presence of sub-micron grains has been inferred in several debris discs, usually because of a blue colour of the spectrum in scattered light or a pronounced silicate band around 10 μm, even though these particles should be blown out by stellar radiation pressure on very short timescales. So far, no fully satisfying explanation has been found for this apparent paradox.

Aims. We investigate the possibility that the observed abundances of sub-micron grains could be naturally produced in bright debris discs, where the high collisional activity produces them at a rate high enough to partially compensate for their rapid removal. We also investigate to what extent this potential presence of small grains can affect our understanding of some debris disc characteristics.

Methods. We used a numerical collisional code to follow the collisional evolution of a debris disc down to sub-micron grains far below the limiting blow-out size sblow. We considered compact astrosilicates and explored different configurations: A and G stars, cold and warm discs, bright and very bright systems. We then produced synthetic spectra and spectral energy distributions, where we identified and quantified the signature of unbound sub-micron grains.

Results. We find that in bright discs (fractional luminosity ≳10−3) around A stars, the number of sub-micron grains is always high enough to leave detectable signatures in scattered light where the disc colour becomes blue, and also in the mid-IR (10 ≲ λ ≲ 20 μm), where they boost the disc luminosity by at least a factor of 2 and induce a pronounced silicate solid-state band around 10 μm. We also show that with this additional contribution of sub-micron grains, the spectral energy distribution can mimic that of two debris belts separated by a factor of ~2 in radial distance. For G stars, the effect of s ≤ sblow grains remains limited in the spectra although they dominate the geometrical cross section of the system. We also find that for all considered cases, the halo of small (bound and unbound) grains that extends far beyond the main disc contributes to ~50% of the flux up to λ ~ 50 μm wavelengths.
Strong Interactions in the Regge Limit and Infrared Region
Authors: Contreras Carlos , Bartels Jochen , Vacca Gian Paolo
Published: April 2019

In this talk, we encode the perturbative BFKL leading logarithmic resummation, relevant for the Regge limit behavior of QCD scattering amplitudes, in the IR regulated effective action, which satisfies exact functional renormalization group equations. The goal is to use this framework to study, in the high-energy limit and at larger transverse distances the transition to a much simpler effective local Reggeon field theory, whose critical properties were recently investigated in the same framework. We perform a numerical analysis of the spectrum of the BFKL Pomeron by the introduction of a Wilsonian infrared regulator to understand the properties of the leading poles (Pomeron states) contributing to the high-energy scattering
Determination of αs in NNLO QCD using H1 jet cross section measurements
Authors: Chekelian Vladimir
Published: April 2019

Measurements of jet cross sections in neutral current deep-inelastic scattering (NC DIS) using data taken with the H1 detector at HERA are accomplished by the precision measurement of double-diﬀerential inclusive jet, dijet and trijet cross sections at low photon virtualities 5.5 < Q2 < 80 GeV2, and by extending previous inclusive jet measurements in the range 150 < Q2 < 15000 GeV2 to low transverse jet momenta 5 < PT < 7 GeV. The strong coupling constant at the Z-boson mass, αs(mZ), is determined in next-to-next-to-leading order (NNLO) QCD using H1 inclusive jet and dijet cross section measurements. Complementary, αs(mZ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The running of the strong coupling is tested at diﬀerent values of the renormalisation scale and the results are found to be in agreement with the QCD expectations.
Geometrical scaling of prompt photons in heavy ion collisions
Authors: Praszałowicz Michał
Published: April 2019

We discuss geometrical scaling (GS) for the prompt (direct) photons produced in heavy ion collisions. To this end we first introduce the concept of GS and illustrate its emergence on the example of charged particles. Next, we analyse direct photon data from RHIC and from the LHC. We show that thedata supportthehypothesisofGSin termsof participant number relatedto diﬀerent centrality classes. We also study GS at diﬀerent energies, however a more detailed study will be possible only when data for at least three diﬀerent energies from one experiment will be available and also when we use the data obtained from the collisions of large systems (Cu+Cu, Au+Au, Pb+Pb) and small systems (p+p,d+Au,p+Au).
One-loop Feynman integrals with Carlson hypergeometric functions
Authors: Phan Khiem Hong
Published: April 2019

In this paper, we present analytic results for scalar one-loop two-, three-, four-point Feynman integrals with complex internal masses. The calculations are considered in general space-time dimension D for two- and three-point functions and D=4 for four-point functions. The analytic results are expressed in terms of the Carlson hypergeometric functions (ℛ-functions) and valid for both real and complex internal masses.
News on fluctuations and correlations from the NA61/SHINE experiment
Authors: Maćkowiak-Pawłowska Maja
Published: April 2019

In this contribution the latest NA61/SHINE results on fluctuations and correlations from the p+p, Be+Be, and Ar+Sc energy scans will be presented. The NA61 experimental results will be compared with existing NA49 data and with model predictions.
PYTHIA and the preoccupied proton
Authors: Trainor Thomas A.
Published: April 2019

The PYTHIA Monte Carlo (PMC) has been applied broadly to simulations of high-energy p-p and p-
$ \bar p $
collisions. The PMC is based on several assumptions, such as that most hadrons result from jet production (multiple par-ton interactions or MPIs), that p-p centrality is relevant and that color reconnection (CR) strongly influences fragmentation to jets. An alternative description is provided by the two-component (soft + hard) model (TCM) of hadron production. TCM analysis of p-Pb ensemble-mean-pt data reveals centrality trends quite diﬀerent from those estimated via a geometric Glauber model based on the eikonal approximation. Glauber estimates of binary-collision number are three times TCM estimates. Detailed study of p-Pb data conflicts with a basic Glauber assumption – that a projectile proton may interact simultaneously with multiple target nucleons. Instead, in both p-p and p-A collisions, a p-N collision once initiated is exclusive of other possible interactions (during that collision), and within the collision any pair of participant partons may interact –a p-N collision is thus “all or nothing.” In this presentation the PMC is challenged by an assortment of contradictory data, and evidence for p-N exclusivity is reviewed to make a case for the “preoccupied proton” of the title.
Λ(

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$ \bar {\Lambda } $

) polarization in Au+Au collisions at RHIC
Authors: Tu Biao
Published: April 2019

Initial large global angular momentum in non-central relativistic heavy-ion collisions can produce strong vorticity, and through the spin-orbit couping, causes the spin of particles to align with the system’s global angular momentum. We present the azimuthal angle dependent (relative to the first-order plane) global polarization for Λ hyperons in midcentral Au+Au collisions at
$ \sqrt {S_{NN} } $
= 200 GeV. We also present the polarization of Λ hyperons along the beam direction as a function of Λ hyperons’ emission angle relative to the second-order event plane at
$ \sqrt {S_{NN} } $
= 200 GeV. This longitudinal polarization is found to increase in more peripheral collision. The implications of the results are discussed.
Precise determination of αS(
$ m_{Z^0 } $
) from a global fit of energy-energy correlations to NNLO+NNLL predictions
Authors: Kardos A. , Kluth S. , Somogyi G. , Tulipánt Z. , Verbytskyi A.
Published: April 2019

We present a determination of the strong coupling constant αS(

$ m_{Z^0 } $
) using a global fit of theory predictions in next-to-next-next-leading-order (NNLO) combined with resummed predictions at the next-to-next-leading-log level (NNLL) [bibrR11]. The predictions are compared to distributions of energy-energy correlations measured in e+e−annihilation to hadronic final states by experiments at the e+e−colliders LEP, PETRA, TRISTAN and PEP. The predictions are corrected for hadronisation eﬀects using the modern generator programs Sherpa 2.2.4 and Herwig 7.1.1.
Recent results on hard probes with ALICE and STAR
Authors: Mao Yaxian
Published: April 2019

This paper reviews recent experimental results on hard probes in heavy-ion collisions from the ALICE and STAR Collaboration. These studies include various observables characterizing jet properties like nuclear modification factors, recoil jet yields, di-jet and photon-jet energy imbalance, and the observables characterizing jet properties like jet fragmentation function and jet shapes; and measurements of high-pT charged hadrons from jet fragmentation and triggered particle correlations will be highlighted.
Measurement of the γ*γ*→ η' transition form factor and of the e+e−→ π+π−π0π0π0 and π+π−π0π0η cross sections by BABAR
Authors: Gary J. William
Published: April 2019

Two recent studies from the BABAR experiment at SLAC on low-energy hadronic final states in e+e− annihilations are presented. The first study provides the first-ever measurement of the γ*γ*→ η' transition factor, where γ* denotes an oﬀ-shell photon. The second study provides the first-ever measurements of the e+e−→ π+ π−π0π0π0 and π+π−π0π0η cross sections, including studies of the intermediate resonance states and the corresponding J/ψ and ψ(2S) branching fractions.
Harnessing the QCD power spectrum for high energy physics
Authors: Sullivan Zack , Pedersen Keith
Published: April 2019

We introduce a new framework to encode information in the QCD power spectrum on an event-by-event basis from which jets and their substructure can be extracted. Our new “power jets” scheme requires no jet radius parameter, and allows pileup to be extracted in situ. The result is an accurate kinematic reconstruction of underlying hard physics which is robust to extremely high pileup.
Recent results for UPC at the LHC
Authors: Kłusek-Gawenda Mariola
Published: April 2019

Ultraperipheral heavy ion collisions are a source of photons which can collide with each other producing a pair of particles. This work will be focused on analysis of the light-by-light scattering. Here contribution from fermionic boxes, resonance scattering, VDM-Regge model, two-gluon exchange and pionic background will be compared. Each of these processes dominate at diﬀerent ranges of two-photon invariant masses. Our calculated nuclear cross section is in good agreement with recently measured ATLAS and CMS data. Predictions including ALICE and LHCb experimental cuts for the next run at the LHC will be shown.
The elastic differential pp cross-section at 13 TeV: an empirical model analysis
Authors: Grau Agnes , Pacetti Simone , Pancheri Giulia , Srivastava Yogendra N.
Published: April 2019

We discuss the differential elastic pp cross-section data measured at 13 TeV, through the Coulomb Nuclear Interference region until past the dip. We show that data are consistent with the asymptotic predictions from an empirical model and examine the presence of a zero for the real part of the elastic amplitude near the Coulomb region, well before the dip.
Recent Results from the CERN LHC Experiment TOTEM: Implications for Odderon Exchange
Authors: Csörgő T.
Published: April 2019

Recent results are summarized from the TOTEM experiment at CERN LHC, including measurements of the total, elastic and inelastic cross-sections, the nuclear slope parameter B, the diﬀerential cross-section of elastic scattering and the real to imaginary part ration ρ at
$ \sqrt s $
= 2.76 and 13 TeV. The implications of these data for Odderon (odd-gluon colorless) exchange are discussed.
Tensor pomeron, vector odderon and diffractive production of meson and baryon pairs in proton-proton collisions
Authors: Lebiedowicz Piotr , Nachtmann Otto , Szczurek Antoni
Published: April 2019

We review some selected results of the tensor-pomeron and vectorodderon model of soft high-energy proton-proton scattering and central exclusive production of meson and baryon pairs in proton-proton collisions. We discuss the theoretical aspects of this approach and consider the phenomenological implications in a variety of processes at high energies, comparing to existing experimental data. We consider the diﬀractive dipion and dikaon production including the continuum and the dominant scalar and tensor resonance contributions as well as the photoproduction processes. The theoretical results are compared with existing CDF experimental data and predictions for planned or current LHC experiments, ALICE, ATLAS, CMS, LHCb are presented.
Schwarzschild-Tangherlini black holes in five-dimensional massive (bi-)gravity
Authors: Do Tuan Q.
Published: April 2019

We will present main results of our recent investigations on the existence of the Schwarzschild-Tangherlini black holes in a five-dimensional (nonlinear) massive gravity as well as in its dynamical extension, a five-dimensional massive bi-gravity. In particular, we will show how to use the well-known Cayley-Hamilton theorem to construct five-and higher dimensional massive graviton terms. Then, we will present the proof of the existence of the Schwarzschild-Tangherlini black holes in the five-dimensional massive (bi-)gravity.
Possibility for nuclear physics study based on Pelletron accelerator at Hanoi, Vietnam
Authors: Phan Viet Cuong , Le Tuan Anh , Le Xuan Chung , Nguyen Hong Ha , Ho Thi Thao , Pham Duc Khue
Published: April 2019

In this report, overview of the new installed Pelletron 5SDH-2 accelerator at Hanoi University of Science, Vietnam and possibilities for performing astrophysics-related nuclear reactions based on this accelerator will be described. In addition to that, some preliminary simulation results for designing and optimizing the experimental set-up in studying reactions 10B(α, p)13C with projectile energies in the Gamow-window will be shown.
Analysis of the

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$ B_s^0 $

→ µ+µ– decay in the MSSM
Authors: Wu Shuang , Chan Aik Hui , Oh Choo Hiap
Published: April 2019

The first observation of the
$ B_s^0 $
→ µ+µ– decay mode was reported by the CMS and LHCb collaboration. The small branching ratio inherent to this decay mode makes it highly sensitive for probing physics beyond the SM and we analyze this decay in the framework of the Minimal Supersymmetric Standard Model (MSSM). Complete analytical expressions for the decay amplitude at the one-loop order have been obtained with the aid of computational tools such as FeynArts and FeynCalc. The general recipe for utilising these computational tools to aid theoretical calculations in the MSSM is discussed. Working in the phenomenological MSSM with reduced parameter space, a simplification of the complete analytical expression was done to express the
$ B_s^0 $

→ µ+µ– branching ratio as a function of these parameters. Numerical studies of the parametric dependence of
$ B_s^0 $

→ µ+µ– branching ratio in the phenomenological MSSM can be easily performed with the obtained analytical expression.
Constraining Non-linear Dirac Equations with Neutrino Oscillations
Authors: Cheung James Asikin , Ng Wei Khim
Published: April 2019

Considering the phenomenological studies of non-linear quantum models, we use an axiomatic approach to modify the Dirac Lagrangian. We apply constraints such as Hermiticity, locality, universality, etc to obtain various generic modified energy dispersion relations. After-which, we use the parameters from the neutrino oscillations to obtain bounds on these new modified dispersion relations.
A General Free Plane Wave Ansatz to The Classcal SU(2) Yang-Mills Theory: with Application to Gravity
Authors: Li W. , Chan A. H. , Oh C. H.
Published: April 2019

In this project, the free plane wave conditions were imposed on the classical SU(2) gauge field to obtain a new general Ansatz. Although afterwards it was found that this Ansatz is similar to a special case of an existing Ansatz[1], there are important diﬀerences. The idea of this Ansatz was later applied to the other nonlinear interaction of nature, namely gravity. However, this eﬀort encountered some complications, such as the lack of an exact definition or interpretation of energy and momentum of gravitational waves.
Parton Branching Process with Supersymmetric Particles at LHC Energies
Authors: Ang H.W. , Zhang Y.Y. , Chan A.H. , Oh C.H.
Published: April 2019

A 2-step parton branching model is proposed to describe the potential presence of supersymmetric particles in multiplicity distributions. This model gives a reasonable description of the data obtained at 13TeV by the ATLAS Collaboration across the maximum pseudorapidity range of η<= 2.5.
Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials
Authors: Čech Jaroslav , Haušild Petr , Karlík Miroslav , Kadlecová Veronika , Čapek Jiří , Průša Filip , Novák Pavel
Published: April 2019

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.
Contraintes résiduelles et comportement mécanique de revêtements nickel-bore
Authors: Montagne Alex , Vitry Véronique , Bonin Luiza , Mughal Muhammad Zeeshan , Sebastiani Marco , Bemporad Edoardo , Iost Alain , Staia Mariana Henriette
Published: April 2019

Deux revêtements à base nickel obtenus par des bains réducteurs, l’un brut et l’autre ayant subi un traitement thermique sont étudiés. L’essai d’indentation a été mis en œuvre pour caractériser la dureté et le module de Young de ces dépôts. Les résultats montrent une bonne homogénéité des propriétés mécaniques dans l’épaisseur du revêtement, alors que le traitement thermique a eu pour effet d’augmenter sa dureté et son module de façon significative. Les contraintes résiduelles dans les revêtements sont étudiées par la méthode du micro anneau incrémental. Les contraintes calculées sont faibles, dispersées et ne semblent pas dépendre du traitement thermique. En l’absence de contraintes résiduelles avant et après traitement thermique, les variations de propriétés mécaniques ont été attribuées à la modification microstructurale du revêtement et à la précipitation de phases dures.
Influence of piston-bore clearance on second motion characteristics of piston and skirt wear
Authors: Xiaohua Xu
Published: April 2019

The piston dynamic simulation was carried out for the wear of the piston skirt after the test of gasoline engine. In addition, the second motion and wear are studied for the improvement proposal of different cylinder clearances. Results show when the original cylinder clearance is 0.0325–0.0575 mm, the minimum operating clearance of the piston skirt is smaller; it is not good for the formation of lubrication oil film, which causes wear on the thrust side and anti-thrust side of piston skirt. When the cylinder clearance was increased to 0.0400–0.0650 mm, the wear load on the thrust side and anti-thrust side of piston skirt was reduced by 68.3% and 68.1%, respectively, the effect of improved wear is better and the result coincides well with engine test result.
Thermo-mechanical behavior of a granular media in a rotating drum
Authors: Teyar Soumia , Renouf Mathieu , Berthier Yves
Published: April 2019

In the complex granular flow, the shear and flow of particles lead to increase in temperature that can enchain behavioral modifications. However, their thermo-mechanical and electrical behavior is of great interest for applications such as rail transport, grinding, and granular material reproduction systems. To study these behaviors, a numerical experiment is carried out on a rotating drum model. This device makes it possible to generate continuous and controlled free surface flows. Relying on the NSCD approach, the location of the hottest zone and the evolution of the temperature are correlated with the evolution of the velocity field.
Experimental research on cage dynamic characteristics of angular contact ball bearing
Authors: Li Qingqing , Chen Xiaoyang , Zhang Tao , Chen Shijin , Gu Jiaming
Published: April 2019

The dynamic performance and life of the precise bearing, even abnormal operation and early failure are affected directly by the complex and unstable motion of the cage. Based on the cage dynamic performance test device with controllable motion of inner and outer rings, respectively, the dynamic characteristics of the cage were studied under different rotating speeds and loads, while inner ring rotated with outer ring fixed and inner–outer rings rotated reversely. Then the trajectory of the cage mass center was drawn through experimental study. The three-dimensional space motions of cage reveal that, when only inner ring rotates, the trajectories of cage mass center are approximately circular under axial load, and the amplitude of the axial displacement raises with the increase of the rotation speeds. With the increase of radial loads, the cage mass center trajectories are shaking from a circle to a small area on the side of the bearing center. When the inner–outer rings rotate in the opposite direction, the rotation speed of the cage is greatly reduced, and the mass center trajectories of the cage oscillate irregularly on side of the bearing center. As the relative rotation speed of rings increases, the axial displacement fluctuation enlarges. With the increase of the radial loads, the axial fluctuation decreases.
Increase in oil content and changes in quality of macauba mesocarp oil along storage
Authors: Tilahun Wogayehu Worku , Grossi José Antonio Saraiva , Favaro Simone Palma , Sediyama Carlos Sigueyuki , Goulart Samuel De Melo , Pimentel Leonardo Durate , Motoike Sergio Yoshimitsu
Published: April 2019

Macauba is an oleaginous palm species from Latin America. It is a rich source of vegetable oil with diverse benefits. However, there are several gaps in assuring post-harvest oil quality of the mesocarp. Thus, ripe fruits were stored at room temperature for 60 days before oil extraction to evaluate fruit and mesocarp oil quality attributes. Physical (decay incidence, water activity), biochemical (specific activity of lipase), physicochemical (acidity and peroxide indices, molar absorptivity at K232 and K270, oxidative stability, total carotene content and mesocarp colour) analyses were carried out. Results show that nonlinear sigmoid response was obtained for most of the parameters evaluated. Decaying reactions related to microorganism’s growth, free fatty acid release and oxidation took place along storage. However, the overall oil quality was in the acceptable limits up to 20 days of storage. It is much further than palm oil, the main source of oil in the world.
Performance du traitement membranaire (NF et OIBP) : rétention des micropolluants et enjeux énergétiques
Authors: Cotton G. , Feliers C. , Kecili K. , Colon A.-L.
Published: April 2019

Pour s’adapter aux évolutions de la qualité de ses ressources en eau et aux renforcements de la réglementation relative aux eaux destinées à la consommation humaine, le Syndicat des eaux d’Île-de-France (Sedif) s’est engagé dans une réflexion sur l’évolution à long terme des filières de ses usines de production d’eau potable. Les études d’évolutions des usines de potabilisation proposent d’insérer, au sein des filières existantes, une étape de filtration sur membranes d’affinage, à l’horizon 2030. Les procédés membranaires, et plus particulièrement les membranes d’osmose inverse basse pression (OIBP), sont considérés comme un affinage de pointe pour la potabilisation de l’eau de surface, permettant notamment d’appréhender la problématique des micropolluants émergents. Dans ce contexte, il a été choisi de tester des membranes d’OIBP afin de caractériser, d’une part, leurs efficacités en matière de rétention (de micropolluants, de la dureté…) et, d’autre part, leurs performances hydrauliques et énergétiques. Cet article présente les résultats des essais des campagnes de caractérisation des membranes d’OIBP sur un pilote de filtration sur membrane plane installé au centre d’essais de Choisy-le-Roi. Quatorze membranes couvrant l’ensemble du domaine recherché en matière de perméabilité à l’eau et de rétention en sels ont été étudiées. Parmi celles-ci, quelques-unes sont particulièrement adaptées aux besoins du Sedif, car elles présentent un bon compromis entre rétention en micropolluants et consommation énergétique. Les conclusions de ces essais de caractérisation sur coupons ont permis de sélectionner deux modèles de membranes afin de les tester, lors d’une étude actuellement en cours, à l’échelle 4 pouces sur le pilote membranaire trois étages de Choisy-le-Roi. En effet, les résultats obtenus sur ces deux membranes prometteuses doivent être validés à échelle semi-industrielle. Cette étude permet d’aborder également d’autres enjeux relatifs aux membranes d’OIBP tels que le colmatage, la reminéralisation, l’optimisation du fonctionnement à trois étages…
Un procédé de fractionnement innovant au coeur du développement des stations d’épuration durables de demain
Authors: Trouvé E. , Belloir S.
Published: April 2019

Aujourd’hui, la fonction essentielle d’une station d’épuration est de dépolluer les effluents liquides pour limiter les dommages sur les milieux naturels ou pour la santé publique. Cet objectif de conservation ne prend malheureusement pas en compte les pressions sociétales. La croissance démographique, les sociétés de consommation nous ont amenés à une situation où annuellement nous consom mons plus de ressources que la planète peut nous offrir. À l’heure du recyclage et du développement de l’économie circulaire, il semble urgent de faire évoluer la conception et l’exploitation des stations d’épuration (STEP). Ces dernières ne doivent plus jouer le rôle de « déchetterie liquide », mais celui de « récupérateur/producteur de ressources ». Avec son développement, la filière biogaz apparaît comme une évidence. Cependant, malgré ces tendances, la croissance d’unités de biogaz sur STEP est figée. Cela est dû au fait que les procédés classiques d’épuration dégradent le pouvoir méthanogène des effluents et restreignent la valorisation d’autres ressources. Les STEP de demain devront être des bioraffineries à forte valeur ajoutée. Cela conduit à faire évoluer nos procédés : au lieu d’enlever les polluants par étapes successives pour obtenir des effluents « propres », extrayons les ressources les unes après les autres, à commencer par l’eau pour la recycler, de l’énergie ainsi que des matières organiques et minérales. Oublions le traitement et valorisons le tri pour une économie circulaire respectueuse quantitativement et qualitativement de nos ressources naturelles. Des technologies de fractionnement membranaire sont la clé du développement de ces bioraffineries. Un retour d’expérience sur une industrie agroalimentaire est présenté dans cet article. Les résultats de ces essais à grande échelle révèlent le potentiel et l’intérêt du recyclage par fractionnement en comparaison aux procédés conventionnels de traitement. Les nouvelles STEP peuvent ainsi devenir des usines de production d’eau potable, de bioengrais, de biomatériaux… tout en étant productrices d’énergie.
Misplaced Ventricular Lead via an Atrial Septal Defect–Percutaneous Extraction
Authors: Easo Jerry , Book Malte , Hakmi Samer , Weymann Alexander
Published: April 2019

Background Necessity for lead removal in this case was after 12 years due to mitral valve regurgitation caused by retraction of the posterior leaflet by the inadvertently misplaced lead.

Case Description This history describes a 45-year-old woman with history of multiple cardiac operations at young age with an abandoned defibrillator lead via a patent atrial septal defect. Lead extraction was performed with first described use of rotational dilating sheaths to reduce emboli risk, hoping to avoid a fourth surgical procedure with high risk.

Conclusions Percutaneous lead removal using rotational sheaths is possible even for misplaced leads after long-time intervals with acceptable operative risk.
Local optima of the Sherrington-Kirkpatrick Hamiltonian
Authors: Addario-Berry Louigi , Devroye Luc , Lugosi Gábor , Oliveira Roberto I.
Published: April 2019

We study local optima of the Hamiltonian of the Sherrington-Kirkpatrick model. We compute the exponent of the expected number of local optima and determine the “typical” value of the Hamiltonian.
Transformation of the Stäckel matrices preserving superintegrability
Authors: Tsiganov A.V.
Published: April 2019

If we take a superintegrable Stäckel system and make variables “faster” or “slower,” that is, equivalent to a trivial transformation of the Stäckel matrix and potentials, then we obtain an infinite family of superintegrable systems with explicitly defined additional integrals of motion. We present some examples of such transformations associated with angle variables expressed via logarithmic functions.
Ferromagnetism-induced phase separation in a two-dimensional spin fluid
Authors: Casiulis Mathias , Tarzia Marco , Cugliandolo Leticia F. , Dauchot Olivier
Published: April 2019

We study the liquid-gas phase separation observed in a system of repulsive particles dressed with ferromagnetically aligning spins, a so-called “spin fluid.” Microcanonical ensemble numerical simulations of finite-size systems reveal that magnetization sets in and induces a liquid-gas phase separation between a disordered gas and a ferromagnetic dense phase at low enough energies and large enough densities. The dynamics after a quench into the coexistence region show that the order parameter associated with the liquid-vapor phase separation follows an algebraic law with an unusual exponent, as it is forced to synchronize with the growth of the magnetization: this suggests that for finite size systems the magnetization sets in along a Curie line, which is also the gas-side spinodal line, and that the coexistence region ends at a tricritical point. This picture is confirmed at the mean-field level with different approximation schemes, namely, a Bethe lattice resolution and a virial expansion complemented by the introduction of a self-consistent Weiss-like molecular field. However, a detailed finite-size scaling analysis shows that in two dimensions the ferromagnetic phase escapes the Berezinskii-Kosterlitz-Thouless scenario and that the long-range order is not destroyed by the unbinding of topological defects. The Curie line thus becomes a magnetic crossover in the thermodynamic limit. Finally, the effects of the magnetic interaction range and those of the interaction softness are characterized within a mean-field semianalytical low-density approach.
Delay modulation with a glass chopper in pump-probe experiments
Authors: Goharshenasanesfahani S. , Hoveyda F. , Scott-Jones M. , Smadici S.
Published: April 2019

A delay modulator, made of glass plates rotating in a pump beam, is applied to measure time-resolved rates of transient processes in a pump-probe experimental setup. Glass plates modulate both delay and beam power. The contribution from the power modulation is subtracted by using a scaled-down measurement made with metal chopper blades. Delay modulation results obtained with this procedure are consistent with the derivative in delay of the usual power modulation and can show a larger signal to noise ratio.