High Mass Limit Research Articles

On global behavior of classical effective field theories

In this paper, we continue the rigorous study of classical effective field theories (EFTs) that was recently initiated in the work of Reall and Warnick. We study a system with one light and one heavy field with cubic coupling and prove global existence [of the ultraviolet (UV) solution] under an effective norm in the high mass limit. Furthermore, we prove that the global solution linearly scatters (in Lax–Philips sense) and that this final state has an expansion in inverse powers of the mass, and can be recovered from the EFT equation alone.

How the mass of a scalar field influences resonance Casimir-Polder interaction in Schwarzschild spacetime

Resonance Casimir-Polder interaction (RCPI) occurs in nature when two or more atoms are in their excited states and the exchange of a real photon occurs between them due to vacuum fluctuations of the quantum fields. In recent times, many attempts have been made to show that some curved spacetimes can be differentiated from a thermal Minkowski spacetime by using the RCPI. Motivated by these ideas, here we study the RCPI between two atoms that interact with a massive scalar field in Schwarzschild spacetime provided the atoms are placed in the near-horizon region. In this context we use the tool of the open quantum system and calculate the Lamb shift of the atomic energy level of the entangled states. We show that the behavior of RCPI changes depending on the mass of the scalar field. In the high mass limit, the interaction becomes short-ranged and eventually disappears beyond a characteristic length scale of , where m is the mass of the scalar field.

The VIMOS Public Extragalactic Redshift Survey (VIPERS)

We use the full VIPERS redshift survey in combination with SDSS-DR7 to explore the relationships between star-formation history (using d4000), stellar mass and galaxy structure, and how these relationships have evolved since z~1. We trace the extents and evolutions of both the blue cloud and red sequence, by fitting double Gaussians to the d4000 distribution of galaxies in narrow stellar mass bins, for four redshift intervals over 0<z<1. This reveals downsizing in star formation, as the high-mass limit of the blue cloud retreats steadily with time from M*~10^11.2 M_sun at z~0.9 to M*~10^10.7 M_sun by the present day. The number density of massive blue-cloud galaxies (M*>10^11 M_sun, d4000<1.55) drops sharply by a factor five between z~0.8 and z~0.5. These galaxies are becoming quiescent at a rate that largely matches the increase in the numbers of massive passive galaxies seen over this period. We examine the size-mass relation of blue cloud galaxies, finding that its high-mass boundary runs along lines of constant M*/r_e or equivalently inferred velocity dispersion. Larger galaxies can continue to form stars to higher stellar masses than smaller galaxies. As blue cloud galaxies approach this high-mass limit, they start to be quenched, their d4000 values increasing to push them towards the green valley. In parallel, their structures change, showing higher Sersic indices and central stellar mass densities. For these galaxies, bulge growth is necessary for them to reach the high-mass limit of the blue cloud and be quenched by internal mechanisms. The blue cloud galaxies that are being quenched at z~0.8 lie along the same size-mass relation as present day quiescent galaxies, and seem the likely progenitors of today's S0s.

Indirect detection constraints on s- and t-channel simplified models of dark matter

Recent Fermi-LAT observations of dwarf spheroidal galaxies in the Milky Way have placed strong limits on the gamma-ray flux from dark matter annihilation. In order to produce the strongest limit on the dark matter annihilation cross-section, the observations of each dwarf galaxy have typically been "stacked" in a joint-likelihood analysis, utilizing optical observations to constrain the dark matter density profile in each dwarf. These limits have typically been computed only for singular annihilation final states, such as $b\bar{b}$ or $\tau^+\tau^-$. In this paper, we generalize this approach by producing an independent joint-likelihood analysis to set constraints on models where the dark matter particle annihilates to multiple final state fermions. We interpret these results in the context of the most popular simplified models, including those with s- and t-channel dark matter annihilation through scalar and vector mediators. We present our results as constraints on the minimum dark matter mass and the mediator sector parameters. Additionally, we compare our simplified model results to those of Effective Field Theory contact interactions in the high-mass limit.

Transition paths are hot

Transition paths in a one-dimensional double-well potential are studied by Brownian dynamics simulations. For large mass and high barrier the velocity distribution of transition paths deviates significantly from the equilibrium Maxwell distribution and their effective temperature at the initial position in the potential well reaches many times the ambient temperature. The effective transition path temperature at the barrier top is only slightly increased and turns out to be maximal at intermediate values of the mass. An analytic expression for the temperature evolution along a transition path in the high-mass limit is derived.

The impact of galaxy formation on the total mass, mass profile and abundance of haloes

We use cosmological hydrodynamical simulations to investigate how the inclusion of physical processes relevant to galaxy formation (star formation, metal-line cooling, stellar winds, supernovae and feedback from Active Galactic Nuclei, AGN) change the properties of haloes, over four orders of magnitude in mass. We find that gas expulsion and the associated dark matter (DM) expansion induced by supernova-driven winds are important for haloes with masses M200 < 10^13 Msun, lowering their masses by up to 20% relative to a DM-only model. AGN feedback, which is required to prevent overcooling, has a significant impact on halo masses all the way up to cluster scales (M200 ~ 10^15 Msun). Baryonic physics changes the total mass profiles of haloes out to several times the virial radius, a modification that cannot be captured by a change in the halo concentration. The decrease in the total halo mass causes a decrease in the halo mass function of about 20%. This effect can have important consequences for abundance matching technique as well as for most semi-analytic models of galaxy formation. We provide analytic fitting formulae, derived from simulations that reproduce the observed baryon fractions, to correct halo masses and mass functions from DM-only simulations. The effect of baryonic physics (AGN feedback in particular) on cluster number counts is about as large as changing the cosmology from WMAP7 to Planck, even when a moderately high mass limit of M500 ~ 10^14 Msun is adopted. Thus, for precision cosmology the effects of baryons must be accounted for.

Understanding the Cosmic Mass Function High-Mass Behavior

We claim that the discrepancy found between theoretical predictions for the cosmic mass function and those found in numerical simulations is due to the fact that in deriving the former all mass elements are assumed to be at the center of the object they belong to (the all-mass-at-center problem). By an appropriate treatment of this problem, using the spherical collapse model (which is not a bad approximation in the high mass limit), we obtain both the high mass behaviour found in simulations and the true assymptotic behaviour of the mass function (for arbitrarily high masses). Therefore, we conclude that by combining ellipsoidal dynamics with a suitable treatment of the all-mass-at-center problem (that we will show in a follow up work) a theoretical prediction for the cosmic mass function in full agreement with simulations may be obtained.

A Black Hole in the Galactic Center Complex IRS 13E?

The IRS 13E complex is an unusual concentration of massive, early-type stars at a projected distance of ~0.13 pc from the Milky Way's central supermassive black hole Sagittarius A* (Sgr A*). Because of their similar proper motion and their common nature as massive, young stars, it has recently been suggested that IRS 13E may be the remnant of a massive stellar cluster containing an intermediate-mass black hole (IMBH) that binds its members gravitationally in the tidal field of Sgr A*. Here, we present an analysis of the proper motions in the IRS 13E environment that combines the currently best available data with a time line of 10 years. We find that an IMBH in IRS 13E must have a minimum mass of ~104 M☉ in order to bind the source complex gravitationally. This high-mass limit in combination with the absence so far of compelling evidence for a nonthermal radio and X-ray source in IRS 13E make it appear unlikely that an IMBH exists in IRS 13E that is sufficiently massive to bind the system gravitationally.

Optical Spectroscopy of Metal‐rich HiiRegions and Circumnuclear Hot Spots in M83 and NGC 3351

We present optical spectroscopy of a sample of metal-rich extragalactic HII regions in the spiral galaxies M83, NGC 3351 and NGC 6384, including a number of circumnuclear HII regions (hot spots). Different age estimators (equivalent width of the Hbeta emission line W(Hb), Balmer line absorption profiles, UV spectra) provide consistently young ages (4-6 Myr) for the hot spots. We have detected the W-R bump feature at 4650 A in five of the objects, and in fewer cases possibly the WC features at 5696 A and 5808 A. Six additional objects showing W-R features are drawn from our previous work on extragalactic HII regions. From the measured luminosity of the W-R blue bump we estimate a small number of WN stars (from 1-2 to about 30). By assuming instantaneous bursts of star formation the ages derived from W(Hb) (3-6 Myr) and the strength of the W-R bump are in agreement with the predictions of evolutionary stellar population models, provided we account for stochastic effects on the IMF. From a comparison with published photoionization models based on synthetic cluster spectral energy distributions we find some evidence for an overestimation of the number of He ionizing photons in the model fluxes. In general, however, the massive star diagnostics are in agreement with the predictions of recent evolutionary models calculated with a Salpeter IMF and a high mass limit. We find no compelling evidence for a depletion of massive stars (M > 40-50 solar masses) in the IMF of metal-rich clusters, contrary to our previous conclusions based on older evolutionary models.

How Many Galaxies Fit in a Halo? Constraints on Galaxy Formation Efficiency from Spatial Clustering

We study galaxy clustering using halo models, where gravitational clustering is described in terms of dark matter halos. At small scales, clustering statistics are dominated by halo density profiles, whereas at large scales, correlations are the result of combining non-linear perturbation theory with halo biasing. Galaxies are assumed to follow the dark matter profiles, and galaxy formation efficiency is given by the number of galaxies as a function of halo mass. This approach leads to generic predictions: the galaxy power spectrum shows a power-law behavior even though the dark matter does not, and the galaxy higher-order correlations show smaller amplitudes at small scales than their dark matter counterparts, as observed in galaxy catalogs. We find that requiring to fit both the second and third order moments of the APM galaxies provides a strong constraint on galaxy formation models. The data at large scales require that galaxy formation be relatively efficient at small masses, m =10^10 Msun/h, whereas data at smaller scales require that the number of galaxies in a halo scale as the mass to the 0.8th power in the high-mass limit. These constraints are independent of those derived from the luminosity function or Tully-Fisher relation. We also predict the power spectrum, bispectrum, and higher-order moments of the mass density field. Although halo models agree well with measurements of the mass power spectrum and the higher order Sp parameters in N-body simulations, the model assumption that halos are spherical leads to disagreement in the configuration dependence of the bispectrum at small scales. We stress the importance of finite volume effects in higher-order statistics and show how they can be estimated in this approach.

New finite-lattice study of the massive Schwinger model

A new finite lattice calculation of the low lying bound state energies in the massive Schwinger model is presented, using a Hamiltonian lattice formulation. The results are compared with recent analytic series calculations in the low mass limit, and with a new higher order non-relativistic series which we calculate for the high mass limit. The results are generally in good agreement with these series predictions, and also with recent calculations by light cone and related techniques.

Constraints on the mass and abundance of black holes in the Galactic halo: the high-mass limit

We establish constraints on the mass and abundance of black holes in the Galactic halo by determining their impact on globular clusters, which are conventionally considered to be little evolved. Using detailed Monte Carlo simulations and simple evolutionary models, we argue that black holes with masses Mbh≳(1–3)×106 M⊙ can comprise no more than a fraction fbh≈0.17 of the total halo density at Galactocentric radius R≈8 kpc. This bound arises from requiring stability of the cluster mass function. A more restrictive bound may be derived if we demand that the probability of destruction of any given, low-mass Mc≈(2.5–7.5)×104 M⊙] globular cluster not exceed 50 per cent; this bound is fbh≲0.025–0.05 at R≈8 kpc. This constraint improves those based on disc heating and dynamical friction arguments as well as current lensing results. At smaller radius the constraint on fbh strengthens, while at larger radius an increased fraction of black holes is allowed.

Determining a 'safe' high-mass limit in matrix-assisted laser desorption/ionisation time-of-flight mass spectra of coal derived materials with reference to instrument noise

Three methods for determining a 'safe' estimate for high-mass limits of MALDI spectra of coal derived liquids were explored, using a sample of coal-tar pitch and its pyridine-insoluble fraction. Co-addition of increasing numbers of single-shot spectra (10, 30, 50 and 100 pulses) showed visually observable reductions in noise levels, consistent with robust and statistically meaningful signals. Three separate types of post-acquisition calculation were used to identify high-mass limits of the spectra. (i) A literature method indicated high-mass limits similar to those observed visually-as a shift from baseline at the highest masses, nearly 350 000 u for the coal tar pitch and about 390 000 u for its pyridine insoluble fraction. (ii) Comparing instrument signal with pre-selected multiples of the standard deviation, upper mass estimates of between 40-60 000 u for the coal-tar pitch and about 95 000 u for its pyridine-insoluble fraction were found. (iii) Calculation of the slope was used to identify 'lift-off' of the spectrum from baseline. The angle between the smoothed spectrum and the baseline was matched to a pre-selected value (e.g. 0.5 degrees and 1 degrees ). However, the arbitrary specification of the key parameter did not establish this last method on a firm basis. The choice of a criterion for estimating high-mass limits of MALDI spectra remains a semi-quantitative procedure; a reasonably conservative high-mass limit may be estimated by comparison of signal with five times the standard deviation. However, evaluation of size exclusion chromatograms of the present samples using polystyrene standards suggests that molecular mass distributions of pitch samples arrived at by MALDI mass spectrometry are, at least partly, determined by the limitations of available instruments. Copyright 1999 John Wiley & Sons, Ltd.

Bethe-Salpeter equation: 3D reductions, heavy mass limits and abnormal solutions

We show that the 3D reductions of the Bethe-Salpeter equation have the same bound state spectrum as the original equation, with the possible exception of solutions for which the 3D reduction vanishes identically. The abnormal solutions of the Bethe-Salpeter equation (corresponding to excitations in the relative time-energy degree of freedom), when they exist, are recovered in the 3D reductions via a complicated dependence of the final potential on the total energy. We know however that the one-body (or one high mass) limit of some 3D reductions of the exact Bethe-Salpeter equation leads to a compact 3D equation (by a mutual cancellation of the ladder and crossed graph contributions), which does not exhibit this kind of dependence on the total energy anymore, and admits thus no abnormal solution. This is in contrast with the results of the ladder approximation, where no such cancellation occurs. We draw the same conclusions for the static model, which we obtain by letting the mass of the lighter particle go also to infinity. These results enforce Wick's conjecture that the abnormal solutions are a spurious consequence of the ladder approximation.

Performance of Infrared Matrix-assisted Laser Desorption/Ionization Mass Spectrometry with Lasers Emitting in the 3 μm Wavelength Range

The performance characteristics of two lasers emitting in the mid infrared, an Er-YAG (2.94 μm wavelength, 80–90 ns pulse width), and an Er-YSGG infrared laser (2.79 μm wavelength, 80 ns pulse width), in matrix-assisted laser desorption/ionization mass spectrometry (IR-MALDI-MS) of biological macromolecules, is reported. Glycerol and succinic acid were used as matrices. In IR-MALDI sample consumption per laser shot typically exceeds that of UV-MALDI by about two orders of magnitude. Using glycerol as matrix, the reproducibility of the ion signals from shot to shot is comparable to the best values achieved in UV-MALDI. The same holds true for the precision and accuracy of the mass determination. For succinic acid all these values are significantly worse, due to the strong sample heterogeneity as typically found in dried droplet preparations. Metastable fragmentation is comparable for UV- and IR-MALDI in the low mass range, but is significantly less for the IR in the mass range above ca. 20 kDa, leading to an improved mass resolution and an extended high mass limit for IR-MALDI. © 1997 John Wiley & Sons, Ltd.

Prediction of a Space Charge Induced Upper Molecular Mass Limit Towards Achieving Unit Mass Resolution in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Cyclotron phase locking arises when two ion clouds have similar mass-to-charge ratios and a sufficiently large ion population such that the relative cyclotron dynamics are dominated by the mutual Coulomb E x B drift dynamics. Once two or more ion clouds are phase locked, a Fourier transform ion cyclotron resonance mass spectrometer cannot distinguish them by image current detection since the ion clouds have identical detected cyclotron frequencies. A simple analytical model, based on the assumption of rigid ion clouds, predicts that the maximum number of ions having equal charge states and closely spaced masses, which can be contained in two clouds before phase locking occurs, is proportional to their mass difference and to the square of the magnetic field strength divided by the molecular mass, Δm(B/M) 2 , and is independent of the charge state. This molecular mass dependence establishes an upper molecular mass limit for resolving closely spaced peaks due to cyclotron phase locking. The rigid ion cloud model, supported by numerical simulations, demonstrates that phase locking causes the 1 Da spacing of the isotopic envelope for large molecules to be unresolvable past a high molecular mass limit (M max ). M max is directly proportional to B and independent of the charge state for adjacent ion clouds with equal charge state. An order of magnitude estimate predicts that M max 1x10 4 (in units of Da and Tesla), independent of charge state for peaks having a 1 Da spacing. This estimate concurs with present instrumental capabilities. Full three-dimensional numerical stimulations on realistic ion clouds, which include the combined effects of internal and external ion cloud dynamics, Z-oscillation, linear dipolar excitation and trap potential anharmonicity, demonstrate the qualitative validity of the assumptions inherent in the rigid ion cloud model predictions.

Theory of trapped ion motion in the non-quadrupolar electrostatic potential of a cubic ion cyclotron resonance cell

Perturbation theory is employed to analytically investigate the dynamics of a single ion trapped in a cubic ion cyclotron resonance cell. The trapping potential is expanded in a Taylor series with terms which are quadratic, powers of four and powers of six in coordinates treated as zero-, first-, and second-order perturbations, respectively. Frequencies are calculated to second order while the mode amplitudes and coordinates are solved to first order. The frequency shifts derived by this method agree very well with numerically evaluated frequency shifts obtained using the exact cubic cell trapping potential. For low m/z, the cyclotron frequency shift is shown to be due to just the cylindrically symmetric part of the cubic cell potential. An internal resonance involving energy exchange between the mode amplitudes is predicted to occur for an ion in a cubic cell when m ≈ m c/3, where m c is the high mass limit.

Consequences of a possible gamma gamma resonance at KEK TRISTAN.

If high mass $\ensuremath{\gamma}\ensuremath{\gamma}$ events observed at CERN LEP are due to the production of a $\ensuremath{\gamma}\ensuremath{\gamma}$ resonance via its leptonic coupling, its consequences can be observed at KEK TRISTAN. We find that a predicted $Z$ decay branching rate is too small to account for the observed events if the resonance spin is zero, due to a strong cancellation in the decay amplitudes. Such a cancellation is absent if the resonance has a spin two. We study the consequences of a tensor production in the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}, {\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}, \mathrm{and} \ensuremath{\gamma}\ensuremath{\gamma}$ at energies reached at TRISTAN. Complete helicity amplitudes with tensor boson exchange contributions are given, and the signal can clearly be identified from various distributions. TRISTAN experiments are also sensitive to the virtual tensor boson exchange effects, which reduce to the contact interaction terms in the high mass limit.

Mass-to-charge ratio upper limits for matrix-assisted laser desorption Fourier transform ion cyclotron resonance mass spectrometry

One of the well-known analytical uses of Fourier transform ion cyclotron resonance mass spectrometry (FT/ICR/MS) ise its high theoretical upper mass limit. FT/ICR/MS upper mass limits with respect to radial or axial loss of trapped lone have previously been derived and computed for lone which are in thermal equilibrium with their surroundings (i.e., follow Boltzmann preexcitation ion initial velocity distributions). However, recent results by Beavis and Chalt show that lone formed by the matrix-assisted laser desorption (MALD) ionization technique are clearly not in thermal equilibrium with their surroundings

Fourier transform mass spectrometry.

Fourier transform mass spectrometry will play an important role in the future because of its unique combination of high mass resolution, high upper mass limit, and multichannel advantage. These features have already found application in gas chromatography-mass spectrometry, multiphoton ionization, laser desorption, and secondary ion mass spectrometry. However, its most notable feature is the ability to store ions. This characteristic, when combined with the others, will allow expeditious study of the interaction of gas-phase ions with both photons (photodissociation) and neutral molecules, and the convenient application of this fundamental information for chemical analysis.