Mass Interval Research Articles

Decay X(3872)→π0π+π− and S -wave D0D¯0→π+π− scattering length

The isospin-breaking decay $X(3872)\to(D^*\bar D+ \bar D^*D) \to\pi^0D\bar D\to\pi^0\pi^+\pi^-$ is discussed. In its amplitude there is a triangle logarithmic singularity, due to which the dominant contribution to $BR(X(3872)\to\pi^0\pi^+\pi^-)$ comes from the production of the $\pi^+\pi^-$ system in a narrow interval of the invariant mass $m_{\pi^+\pi^-}$ near the value of $2m_{D^0} \approx 3.73$ GeV. The analysis shows that $BR(X(3872)\to\pi^0 \pi^+\pi^-)$ can be expected at the level of $10^{-3}$--$10^{-4}$. This estimate includes, in particular, the assumption that the $S$-wave inelastic scattering length $|\alpha''_{D^0\bar D^0 \to\pi^+\pi^-}|\approx1/(2m_{D^{*+}})\approx0.25\ \mbox{GeV}^{-1}$.

The lifetime of binary black holes in Sérsic galaxy models

Abstract In the local Universe, black holes of $10^{5-6}\, {\rm M_\odot }$ are hosted in galaxies displaying a variety of stellar profiles and morphologies. These black holes are the anticipated targets of LISA, the Laser Interferometer Space Antenna that will detect the low-frequency gravitational-wave signal emitted by binary black holes in this mass interval. In this paper, we infer upper limits on the lifetime of binary black holes of $10^{5-6}\, {\rm M_\odot }$ and up to $10^8\, {\rm M_\odot }$, forming in galaxy mergers, exploring two underlying stellar density profiles, by Dehnen and by Prugniel & Simien, and by exploiting local scaling relations between the mass of the black holes and several quantities of their hosts. We focus on the phase of the dynamical evolution when the binary is transitioning from the hardening phase ruled by the interaction with single stars to the phase driven by the emission of gravitational waves. We find that different stellar profiles predict very distinct trends with binary mass, with lifetimes ranging between fractions of a Gyr to more than 10 Gyr, and with a spread of about one order of magnitude, given by the uncertainties in the observed correlations, which are larger in the low-mass tail of the observed black hole population.

On the Elevation and Suppression of Star Formation within Galaxies

Abstract To understand star formation in galaxies, we investigate the star formation rate (SFR) surface density ( ) profiles for galaxies, based on a well-defined sample of 976 star-forming MaNGA galaxies. We find that the typical profiles within 1.5 of normal SF galaxies can be well described by an exponential function for different stellar mass intervals, while the sSFR profile shows positive gradients, especially for more massive SF galaxies. This is due to the more pronounced central cores or bulges, rather than the onset of a “quenching” process. While galaxies that lie significantly above (or below) the star formation main sequence show overall an elevation (or suppression) of at all radii, this central elevation (or suppression) is more pronounced in more massive galaxies. The degree of central enhancement and suppression is quite symmetric, suggesting that both the elevation and suppression of star formation are following the same physical processes. Furthermore, we find that the dispersion in within and across the population is found to be tightly correlated with the inferred gas depletion time, whether based on the stellar surface mass density or the orbital dynamical time. This suggests that we are seeing the response of a simple gas-regulator system to variations in the accretion rate. This is explored using a heuristic model that can quantitatively explain the dependence of σ( ) on gas depletion timescale. Variations in accretion rate are progressively more damped out in regions of low star formation efficiency, leading to a reduced amplitude of variations in star formation.

TheKeplerview of magnetic chemically peculiar stars

Context. Magnetic chemically peculiar (mCP) stars exhibit complex atmospheres that allow the investigation of such diverse phenomena as atomic diffusion, magnetic fields, and stellar rotation. The advent of space-based photometry provides the opportunity for the first precise characterizations of the photometric variability properties of these stars, which might advance our understanding of the processes involved and the atmospheric structures of mCP stars.Aims. We carried out a search for new mCP stars in theKeplerfield with the ultimate aim of investigating their photometric variability properties usingKeplerdata. As an aside, we describe criteria for selecting mCP star candidates based on light curve properties, and assess the accuracy of the spectral classifications provided by the MKCLASS code.Methods. As only very few known mCP stars are situated in theKeplerfield, we had to depend largely on alternative (non-spectroscopic) means of identifying suitable candidates that rely mostly on light curve properties; in particular we relied on monoperiodic variability and light curve stability. Newly acquired and archival spectra were used to confirm most of our mCP star candidates. Linear ephemeris parameters and effective amplitudes were derived from detrendedKeplerdata.Results. Our final sample consists of 41 spectroscopically confirmed mCP stars of which 39 are new discoveries, 5 candidate mCP stars, and 7 stars in which no chemical peculiarities could be established. Our targets populate the whole age range from zero-age main sequence to terminal-age main sequence and are distributed in the mass interval from 1.5M⊙to 4M⊙. About 25% of the mCP stars show a hitherto unobserved wealth of detail in their light curves indicative of complex surface structures. We identified light curve stability as a primary criterion for identifying mCP star candidates among early-type stars in large photometric surveys, and prove the reliability of the spectral classifications provided by the MKCLASS code.

Discovery potential of stable and near-threshold doubly heavy tetraquarks at the LHC

We study the LHC discovery potential of the double-bottom tetraquarks bbu¯d¯, bbu¯s¯ and bbd¯s¯, the lightest of which having JP=1+, called T[u¯d¯]{bb}, T[u¯s¯]{bb} and T[d¯s¯]{bb}, are expected to be stable against strong decays. Employing the Monte Carlo generators MadGraph5_aMC@NLO and Pythia6, we simulate the process pp→b¯bb¯b+X and calculate the bb-diquark jet configurations, specified by the invariant mass interval Mbb<MT[q¯q¯′]{bb}+ΔM. Estimates of ΔM from the measured product σ(pp→Bc++X)B(Bc+→J/ψπ+) are presented and used to get the bb-diquark jet cross sections in double-bottom hadrons σ(pp→H{bb}+X), where H{bb} represent tetraquarks and baryons. This is combined with the LHCb data on the fragmentation b→Λb and b→B to obtain σ(pp→T[u¯d¯]{bb}+X)=(2.8−0.7+1.0)nb at s=13 TeV, and about a quarter of this for the T[u¯s¯]{bb} and T[d¯s¯]{bb}, each. We also present estimates of the production cross sections for the mixed bottom-charm tetraquarks, bcu¯d¯, bcu¯s¯ and bcd¯s¯, obtaining σ(pp→T[u¯d¯][bc]+X)=(103−25+39)nb at s=13 TeV, and the related ones having T[u¯s¯][bc] and T[d¯s¯][bc]. They have excellent discovery potential at the LHC, as their branching ratios in various charge combinations of BD(s)(γ) are anticipated to be large.

Isothermal Fragmentation: Is there a low-mass cut-off?

The evolution of self-gravitating clouds of isothermal gas forms the basis of many star formation theories. Therefore it is important to know under what conditions such a cloud will undergo homologous collapse into a single, massive object, or will fragment into a spectrum of smaller ones. And if it fragments, do initial conditions (e.g. Jeans mass, sonic mass) influence the mass function of the fragments, as predicted by many theories of star formation? In this paper we show that the relevant parameter separating homologous collapse from fragmentation is not the Mach number of the initial turbulence (as suspected by many), but the infall Mach number $\mathcal{M}_{\rm infall}\sim\sqrt{G M/(R c_s^2)}$, equivalent to the number of Jeans masses in the initial cloud $N_J$. We also show that fragmenting clouds produce a power-law mass function with slopes close to the expected -2 (i.e. equal mass in all logarithmic mass intervals). However, the low-mass cut-off of this mass function is entirely numerical; the initial properties of the cloud have no effect on it. In other words, if $\mathcal{M}_{\rm infall}\gg 1$, fragmentation proceeds without limit to masses much smaller than the initial Jeans mass.

Outskirts of Galaxy Clusters A1139, A1314, A1656, A2040, A 2052, A2107: Star-Formation Rate

We investigate the variation of the fraction of galaxies with suppressed star formation (MK < −21 . m 5) and early-type galaxies (fracE) of the “red sequence” along the projected radius in six galaxy clusters:Coma (A1656), A1139, and A1314 in the Leo supercluster region (z ≈ 0.037) and A2040, A2052, A2107 in the Hercules supercluster region (z ≈ 0.036). According to SDSS (DR10) data, fracE is the highest in the central regions of galaxy clusters and it is, on the average, equal to 0.62 ± 0.03, whereas in the 2–3R/R200c interval and beyond the Rsp ≈ 0.95 ± 0.04 R200m radius that we inferred from the observed profile fracE is minimal and equal to 0.25 ± 0.02. This value coincides with the estimate fracE = 0.24 ± 0.01 that we inferred for field galaxies located between the Hercules and Leo superclusters at the same redshifts. We show that the fraction of galaxies with suppressed star formation decreases continuously with cluster radius from 0.87 ± 0.02 in central regions down to 0.43 ± 0.03 in the 2–3 R/R200c interval and beyond Rsp, but remains, on the average, higher than 26% than the corresponding fraction for field objects. This decrease is especially conspicuous in the galaxy mass interval log M* [M⊙] = 9.5–10. We found that galaxies with ongoing star formation have average clustercentric distances 1.5–2.5 R/R200c and that their radial-velocity dispersions are higher than those of galaxies with suppressed star formation.

Prospects of discovering stable double-heavy tetraquarks at a Tera-Z factory

Motivated by a number of theoretical considerations, predicting the deeply bound double-heavy tetraquarks T[u¯d¯]{bb}, T[u¯s¯]{bb} and T[d¯s¯]{bb}, we explore the potential of their discovery at Tera-Z factories. Using the process Z→bb¯bb¯, we calculate, employing the Monte Carlo generators MadGraph5_aMC@NLO and Pythia6, the phase space configuration in which the bb pair is likely to fragment as a diquark. In a jet-cone, defined by an invariant mass interval mbb<MT[q¯q¯′]{bb}+ΔM, the sought-after tetraquarks T[q¯q¯′]{bb} as well as the double-bottom baryons, Ξbb0,−, and Ωbb−, can be produced. Using the heavy quark–diquark symmetry, we estimate B(Z→T[u¯d¯]{bb}+b¯b¯)=(1.2−0.3+1.0)×10−6, and about a half of this for the T[u¯s¯]{bb} and T[d¯s¯]{bb}. We also present an estimate of their lifetimes using the heavy quark expansion, yielding τ(T[q¯q¯′]{bb})≃800 fs. Measuring the tetraquark masses would require decays, such as T[u¯d¯]{bb}−→B−D−π+, T[u¯d¯]{bb}−→J/ψK‾0B−, T[u¯d¯]{bb}−→J/ψK−B‾0, T[u¯s¯]{bb}−→Ξbc0Σ−, and T[d¯s¯]{bb}0→Ξbc0Σ¯0, with subsequent decay chains in exclusive non-leptonic final states. We estimate a couple of the decay widths and find that the product branching ratios do not exceed 10−5. Hence, a good fraction of these modes will be required for a discovery of T[q¯q¯′]{bb} at a Tera-Z factory.

Determination of the nuclear level densities and radiative strength function for 43 nuclei in the mass interval 28≤A≤200

The determination of nuclear level densities and radiative strength functions is one of the most important tasks in low-energy nuclear physics. Accurate experimental values of these parameters are critical for the study of the fundamental properties of nuclear structure. The step-like structure in the dependence of the level densities p on the excitation energy of nuclei Eex is observed in the two-step gamma cascade measurements for nuclei in the 28 ≤ A ≤ 200 mass region. This characteristic structure can be explained only if a co-existence of quasi-particles and phonons, as well as their interaction in a nucleus, are taken into account in the process of gamma-decay. Here we present a new improvement to the Dubna practical model for the determination of nuclear level densities and radiative strength functions. The new practical model guarantees a good description of the available intensities of the two step gamma cascades, comparable to the experimental data accuracy.

QCD-based origin of the particle mass discreteness

We consider the accurate relations in the tuning effect in particle masses which consists in integer relations between masses of leptons and hadrons. The role of the QCD based gluon-quark-dressing effect and relations with the constituent quark masses are discussed. In this work, for the first time a check of these relations was performed by the analysis of particle masses from the Particle Data Group Compilation (PDG-2016). In the distribution of all differences between 137 particles known with the accuracy better than 5–8 MeV the grouping effects in difference of masses in the region of the pion mass (142 MeV), the muon mass (107 MeV), the constituent quark mass (445–460 MeV) and bottom quark mass (3960 MeV) were confirmed. The stability of mass intervals in the region of the constituent quark mass and bottom-quark mass is discussed in the connection with masses of fundamental fields.

Annihilation semileptonic decays of B mesons and the model dependence on the choice of the distribution amplitude

The rare semileptonic B-meson decay B → ϕl+l− is considered. The partial decay rate integrated over the 1–8 GeV2 interval of the dilepton invariant mass squared is computed with a 10% systematic uncertainty arising from the model dependence of the distribution amplitude. The purely perturbative contribution to the decay probability amounts to ℬ ∼ 10−12, which suggests that the LHC experiments could observe the B → ϕl+l− decay in a few years of data taking.

Improving the symmetry of asymmetric supercapacitors using battery-type positive electrodes and activated carbon negative electrodes by mass and charge balance

Asymmetric supercapacitors (ASCs) are routinely fabricated using battery-type electrode materials as a positive electrode and electrochemical double layer materials as a negative electrode; the mass-loading in the electrodes is determined by assuming both to be capacitive charge storage materials. This protocol is erroneous as the cyclic voltammograms and galvanostatic charge-discharge curves of the resulting devices showed dissimilarity in the stored charges of the two electrodes and battery-type behaviors, respectively. Herein, we show by employing two choices of battery-type electrodes as positive electrodes and commercial activated carbon as negative electrode in 3M LiOH electrolyte that equal mass loading in both electrodes leads to supercapacitive charge storage. The positive electrode to negative electrode mass ratio is varied from 0.75 to 1.5 in a mass interval of 0.25 which includes a mass ratio of the conventional method. The electrochemical studies of the fabricated ASCs show that the charge storage capabilities depend on the electrode mass. Electrochemical impedance spectroscopy studies show that the equal mass ratio has low series and charge transfer resistances and wider frequency dispersion of capacitance.

PP.19.21] ASSOCIATION BETWEEN QTC AND VASCULAR STIFFNESS

Objective: QTc prolongation is associated with hypertension, insulin resistance, body mass index increase (BMI), left ventricular hypertrophy, female gender, and subclinical artheriosclerosis. Among hypertensives an increased arterial stiffness is considered as a subclinical target organ damage. Our hypothesis was that a direct association between QT interval duration and arterial stiffness could be identified suggesting their interaction towards a higher cardiovascular risk. Aims (a) To evaluate the distribution of corrected QTc duration in hypertensive patients (HP) in comparison with a control group and (b) to determine the association between QTc and vascular stiffness in the general population.Design and method: The study included 53 patients considered as general population, and then classified as hypertensive (n: 30), and normotensive (n:23), age: 55,13 +/− 9,94 years, male: 34, female:19. Arterial pressure, vascular stiffness, index of left ventricular mass (LVMI) and QTc interval were measured. Patients were divided in tertiles according to the QTc duration: T1 QTc 350–400 msec, T2 QTc 400–439 msec and T3 QTc > 440 msec. Results: No major differences was observed between the hypertensive patients group and the control group in terms of age (p 0,0873), gender (p 0,6142), diabetes (p 0,8721), sedentary lifestyle (p 0,0650), and smoking (p 0,9121). Difference was observed in systolic blood pressure (SBP), p 0,00365, diastolic blood pressure (DBP) p 0,001 and QTc (406,10 +/− 29,6 versus 391,76 +/− 21,1 p 0,0345). Table 1 The QTc correlated in univariate form with PWV (p 0,0050) and with SBP (p 0,0328). When making a multivariate analysis the association between PWV and QTc remained unchanged (p 0, 0232). The AUC was 0,686 (p 0.0154), with a 83, 3% sensitivity, 58.54% specificity and a cut point of 402 mseg for QTc as predictor of vascular stiffness increase. Conclusions: The QTc values were more prolonged in hypertensive patients. Furthermore, a direct association between QTc length and arterial stiffness was observed.

Effective and Definite Resonances in the Photoproduction of η′ Mesons on Protons

A qualitative description of the most accurate experimental differential cross sections of the reaction γp→η′p from the CLAS 2009 Collaboration and unprecedentedly accurate total cross sections of this reaction, measured by the A1 Mainz 2015 Collaboration in the isobaric model of photoproduction has been obtained. Masses and widths of four resonances, extracted from such fits, lay claim to a real existence and lie in the usual mass and width intervals of nucleon resonances. But in order for our model not to contradict the results of measurements of the Σ-asymmetry of this reaction made by the GRAAL 2013 Collaboration, the need arose for an additional resonance with mass equal to the threshold of the reaction under discussion, and width Γ = 110 MeV.

Precision measurement and interpretation of inclusive W^+, W^- and Z/gamma ^* production cross sections with the ATLAS detector

High-precision measurements by the ATLAS Collaboration are presented of inclusive W^+ rightarrow ell ^+nu , W^- rightarrow ell ^-bar{nu } and Z/gamma ^* rightarrow ell ell (ell =e,mu ) Drell–Yan production cross sections at the LHC. The data were collected in proton–proton collisions at sqrt{s} = 7,text {TeV} with an integrated luminosity of 4.6,mathrm {fb}^{-1}. Differential W^+ and W^- cross sections are measured in a lepton pseudorapidity range |eta _{ell }|<2.5. Differential Z/gamma ^* cross sections are measured as a function of the absolute dilepton rapidity, for |y_{ell ell }| < 3.6, for three intervals of dilepton mass, m_{ell ell }, extending from 46 to 150,,text {GeV}. The integrated and differential electron- and muon-channel cross sections are combined and compared to theoretical predictions using recent sets of parton distribution functions. The data, together with the final inclusive e^{pm }p scattering cross-section data from H1 and ZEUS, are interpreted in a next-to-next-to-leading-order QCD analysis, and a new set of parton distribution functions, ATLAS-epWZ16, is obtained. The ratio of strange-to-light sea-quark densities in the proton is determined more accurately than in previous determinations based on collider data only, and is established to be close to unity in the sensitivity range of the data. A new measurement of the CKM matrix element vert V_{cs} vert is also provided.

Calculation of the critical overdensity in the spherical-collapse approximation

Critical overdensity $\delta_c$ is a key concept in estimating the number count of halos for different redshift and halo-mass bins, and therefore, it is a powerful tool to compare cosmological models to observations. There are currently two different prescriptions in the literature for its calculation, namely, the differential-radius and the constant-infinity methods. In this work we show that the latter yields precise results {\it only} if we are careful in the definition of the so-called numerical infinities. Although the subtleties we point out are crucial ingredients for an accurate determination of $\delta_c$ both in general relativity and in any other gravity theory, we focus on $f(R)$ modified-gravity models in the metric approach; in particular, we use the so-called large ($F=1/3$) and small-field ($F=0$) limits. For both of them, we calculate the relative errors (between our method and the others) in the critical density $\delta_c$, in the comoving number density of halos per logarithmic mass interval $n_{\ln M}$ and in the number of clusters at a given redshift in a given mass bin $N_{\rm bin}$, as functions of the redshift. We have also derived an analytical expression for the density contrast in the linear regime as a function of the collapse redshift $z_c$ and $\Omega_{m0}$ for any $F$.

The Stellar Initial Mass Function in Early-type Galaxies from Absorption Line Spectroscopy. IV. A Super-Salpeter IMF in the Center of NGC 1407 from Non-parametric Models

It is now well-established that the stellar initial mass function (IMF) can be determined from the absorption line spectra of old stellar systems, and this has been used to measure the IMF and its variation across the early-type galaxy population. Previous work focused on measuring the slope of the IMF over one or more stellar mass intervals, implicitly assuming that this is a good description of the IMF and that the IMF has a universal low-mass cutoff. In this work we consider more flexible IMFs, including two-component power-laws with a variable low-mass cutoff and a general non-parametric model. We demonstrate with mock spectra that the detailed shape of the IMF can be accurately recovered as long as the data quality are high (S/N$\gtrsim300$) and cover a wide wavelength range (0.4um-1.0um). We apply these flexible IMF models to a high S/N spectrum of the center of the massive elliptical galaxy NGC 1407. Fitting the spectrum with non-parametric IMFs, we find that the IMF in the center shows a continuous rise extending toward the hydrogen-burning limit, with a behavior that is well-approximated by a power-law with an index of -2.7. These results provide strong evidence for the existence of extreme (super-Salpeter) IMFs in the cores of massive galaxies.

Characterization of hemicelluloses in process streams in thermomechanical and chemi-thermomechanical pulp mills

Increased interest in hemicelluloses as a renewable source of biopolymers has resulted in an interest in hemicelluloses in process streams in pulp mills. The aim of this study was to compare potential positions for the withdrawal of hemicelluloses from mechanical pulp mills. Samples were withdrawn at a total of fourteen positions from two thermomechanical and two chemi-thermomechanical pulp mills. The molecular mass distributions of hemicelluloses and lignin were determined by size-exclusion chromatography. Hemicelluloses showed peaks in the molecular mass interval of 0.2–2 kDa and 4–60 kDa, whereas lignin showed peaks in the range of 0.5–4 kDa, but no peak in the high-molecular-mass region. Glucomannan accounts for approximately two-thirds of the hemicellulose content of softwood, and mannan and glucan were thus the dominating saccharides in all samples. Mannan was preferentially found in fractions with a molecular mass ranging from 4 to 22 kDa.

Negative Energy Ground States for the L 2-Critical NLSE on Metric Graphs

We investigate the existence of ground states with prescribed mass for the focusing nonlinear Schr\"odinger equation with $L^2$-critical power nonlinearity on noncompact quantum graphs. We prove that, unlike the case of the real line, for certain classes of graphs there exist ground states with negative energy for a whole interval of masses. A key role is played by a thorough analysis of Gagliardo-Nirenberg inequalities and on estimates of the optimal constants. Most of the techniques are new and suited to the investigation of variational problems on metric graphs.

Phase Composition and Microstructure of Ti-Nb Alloy Produced by Selective Laser Melting

The phase composition and microstructure of Ti-Nb alloy produced from composite titanium and niobium powder by selective laser melting (SLM) was studied. Produced monolayered Ti-Nb alloy enhanced the formation of fine-grained and medium-grained zones with homogeneous element composition of 36-38% Nb mass interval. Alloy phase composition responded to β-alloy substrate phase (grain size was 5-7 pm) and non-equilibrium martensite α"- phase (grain size was 0.1-0.7 µm). α"-phase grains were found along β-phase grain boundaries and inside grains, including decreased niobium content. Alloy microhardness varied within 4200-5500 MPa.