Production Amplitudes Research Articles

White-crowned sparrow males show immediate flexibility in song amplitude but not in song minimum frequency in response to changes in noise levels in the field.

The soundscape acts as a selective agent on organisms that use acoustic signals to communicate. A number of studies document variation in structure, amplitude, or timing of signal production in correspondence with environmental noise levels thus supporting the hypothesis that organisms are changing their signaling behaviors to avoid masking. The time scale at which organisms respond is of particular interest. Signal structure may evolve across generations through processes such as cultural or genetic transmission. Individuals may also change their behavior during development (ontogenetic change) or in real time (i.e., immediate flexibility). These are not mutually exclusive mechanisms, and all must be investigated to understand how organisms respond to selection pressures from the soundscape. Previous work on white‐crowned sparrows (Zonotrichia leucophrys) found that males holding territories in louder areas tend to sing higher frequency songs and that both noise levels and song frequency have increased over time (30 years) in urban areas. These previous findings suggest that songs are changing across generations; however, it is not known if this species also exhibits immediate flexibility. Here, we conducted an exploratory, observational study to ask whether males change the minimum frequency of their song in response to immediate changes in noise levels. We also ask whether males sing louder, as increased minimum frequency may be physiologically linked to producing sound at higher amplitudes, in response to immediate changes in environmental noise. We found that territorial males adjust song amplitude but not minimum frequency in response to changes in environmental noise levels. Our results suggest that males do not show immediate flexibility in song minimum frequency, although experimental manipulations are needed to test this hypothesis further. Our work highlights the need to investigate multiple mechanisms of adaptive response to soundscapes.

Possible small- x effects in the Kaluza-Klein graviton and radion production at high energies

We study the single graviton production at the CERN LHC using the ${k}_{T}$-factorization approach of QCD. We consider the Arkani-Hamed-Dimopoulos-Dvali scenario and Randall-Sundrum model with one warped extra dimension and derive the production amplitudes for spin-2 (Kaluza-Klein excitation of the graviton) and spin-0 (radion) states, including subsequent graviton decay into the dilepton or diphoton pairs. We use the transverse momentum dependent (unintegrated) parton densities in a proton obtained from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation, which resums the leading logarithmic small-$x$ corrections to the production cross sections, and estimate the uncertainties of our predictions. We demonstrate that the small-$x$ effects can manifest themselves in the different angular distributions of graviton decay products and give some examples of what these distributions can look like at the LHC energies.

Climate controls over the net carbon uptake period and amplitude of net ecosystem production in temperate and boreal ecosystems

The seasonal and interannual variability of the terrestrial carbon cycle is regulated by the interactions of climate and ecosystem function. However, the key factors and processes determining the interannual variability of net ecosystem productivity (NEP) in different biomes are far from clear. Here, we quantified yearly anomalies of seasonal and annual NEP, net carbon uptake period (CUP), and the maximum daily NEP (NEPmax) in response to climatic variables in 24 deciduous broadleaf forest (DBF), evergreen forest (EF), and grassland (GRA) ecosystems that include at least eight years of eddy covariance observations. Over the 228 site-years studied, interannual variations in NEP were mostly explained by anomalies of CUP and NEPmax. CUP was determined by spring and autumn net carbon uptake phenology, which were sensitive to annual meteorological variability. Warmer spring temperatures led to an earlier start of net carbon uptake activity and higher spring and annual NEP values in DBF and EF, while warmer autumn temperatures in DBF, higher autumn radiation in EF, and more summer and autumn precipitation in GRA resulted in a later ending date of net carbon uptake and associated higher autumn and annual NEP. Anomalies in NEPmax s were determined by summer precipitation in DBF and GRA, and explained more than 50% of variation in summer NEP anomalies for all the three biomes. Results demonstrate the role of meteorological variability in controlling CUP and NEPmax, which in turn help describe the seasonal and interannual variability of NEP.

Exclusive neutrino production of a charmed meson

We calculate the leading order in $\alpha_s$ QCD amplitude for exclusive neutrino and antineutrino production of a $D$ pseudoscalar charmed meson on an unpolarized nucleon. We work in the framework of the collinear QCD approach where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We include both $O(m_c)$ terms in the coefficient functions and $O(M_D)$ mass term contributions in the heavy meson distribution amplitudes. We emphasize the sensitivity of specific observables on the transversity quark GPDs.

Partial waves in Bs*B¯s* production in e+e− annihilation near threshold

The production of the vector meson pairs $B_s^* \bar B_s^*$ in the $e^+e^-$ annihilation is generally contributed by two $P$ wave amplitudes with different total spin $S$ of the mesons, $S=0$ and $S=2$, and also by an $F$ wave amplitude. Belle has recently reported a study of the available data at the energy of the $\Upsilon(5S)$ peak in terms of the two $P$ wave contributions only. It is argued here that although at this energy the $F$ wave should be quite suppressed, especially for the strange-bottom vector mesons, the particular studied angular distribution is very sensitive to a presence of even small $F$ wave amplitude due to a significant interference with the dominant $S=2$ $P$ wave. Thus the available data are not conclusive with regards to the partial wave structure of the production amplitude. Additional angular correlations are discussed that can be measured for a full amplitude analysis of the production process.

Clearer visibility of the Hong-Ou-Mandel effect with a correlation function based on rates rather than intensities

We test ideas put forward e.g in arXiv:1508.02368, which suggest that using rates in quantum optics can lead to better indicators of non-classicality for states of quantum optical fields with undefined photon numbers. By rate we mean the ratio of registered photons in a given detector to the total number of detected photons in all detectors in the experiment. For the Hong-Ou-Mandel effect for parametric down conversion fields, we show that by using two detector correlation functions which are defined in terms of averages of products of measured rates, rather than usual intensities, one can observe non -- classical visibilities beyond $1/2$ for significantly higher pump rates. At such rates we already have a partially stimulated emission which leads to significant amplitudes for multiple pairs production, still the new approach allows to clearly see the non-classical dip.

General Unquenching Properties of Two-meson Scattering and Production Amplitudes

General Unquenching Properties of Two-meson Scattering and Production Amplitudes

Effective field theory for long-range properties of bottomonium

In this communication we present selected results from a recent study [N. Brambilla, G. Krein, J. Tarrus Castella and A. Vairo, Phys. Rev. D 93 , 054002 (2016)] of long-range properties of bottomonium. An analytical expression for the chromopolarizability of 1S bottomonium states is derived within the framework of potential nonrelativistic QCD (pNRQCD). Next, after integrating out the ultrasoft scale associated with the binding energy of bottomonium, the QCD trace anomaly is used to obtain the two-pion production amplitude for the chromopolarizability operator and the result is matched to a chiral effective field theory having bottomonium states and pions as degrees of freedom. We present results for the leading chiral logarithm correction to the mass of the 1S bottomonium and the van der Waals potential between two bottomonium states.

Occlusion effect on compensatory formant production and voice amplitude in response to real-time perturbation.

The importance of auditory feedback for controlling speech articulation has been substantiated by the use of the real-time auditory perturbation paradigm. With this paradigm, speakers receive their own manipulated voice signal in real-time while they produce a simple speech segment. In response, they spontaneously compensate for the manipulation. In the case of vowel formant control, various studies have reported behavioral and neural mechanisms of how auditory feedback is processed for compensatory behavior. However, due to technical limitations such as avoiding an electromagnetic artifact or metal transducers near a scanner, some studies require foam tip insert earphones. These earphones occlude the ear canal, and may cause more energy of the unmanipulated first formant to reach the cochlea through bone conduction and thus confound the effect of formant manipulation. Moreover, amplification of lower frequencies due to occluded ear canals may influence speakers' voice amplitude. The current study examined whether using circumaural headphones and insert earphones would elicit different compensatory speech production when speakers' first formant was manipulated in real-time. The results of the current study showed that different headphones did not elicit different compensatory formant production. Voice amplitude results were varied across different vowels examined; however, voice amplitude tended to decrease with the introduction of F1 perturbation.

Hadron diffractive production at ultrahigh energies and shadow effects

Shadow effects at collisions of hadrons with light nuclei at high energies were subject of scientific interest of V.N. Gribov, first, we mean his study of the hadron-deuteron scattering, see Sov. Phys. JETP 29, 483 (1969) [Zh. Eksp. Teor. Fiz. 56, 892 (1969)] and discovery of the reinforcement of shadowing due to inelastic diffractive rescatterings. It turns out that the similar effect exists on hadron level though at ultrahigh energies. Diffractive production is considered in the ultrahigh energy region where pomeron exchange amplitudes are transformed into black disk ones due to rescattering corrections. The corresponding corrections in hadron reactions [Formula: see text] with small momenta transferred ([Formula: see text], [Formula: see text]) are calculated in terms of the [Formula: see text]-matrix technique modified for ultrahigh energies. Small values of the momenta transferred are crucial for introducing equations for amplitudes. The three-body equation for hadron diffractive production reaction [Formula: see text] is written and solved precisely in the eikonal approach. In the black disk regime final state scattering processes do not change the shapes of amplitudes principally but dump amplitudes by a factor [Formula: see text]; initial state rescatterings result in additional factor [Formula: see text]. In the resonant disk regime initial and final state scatterings damp strongly the production amplitude that corresponds to [Formula: see text] at [Formula: see text] in this mode.

Reconsideration of the inclusive prompt photon production at the LHC withkT-factorization

We reconsider the inclusive production of isolated prompt photons in $pp$ collisions at the LHC energies in the framework of $k_T$-factorization approach. Our analysis is based on the ${\cal O}(\alpha \alpha_s)$ off-shell (depending on the transverse momenta of initial quarks and gluons) production amplitudes of $q^* g^* \to \gamma q$ and $q^* \bar q^* \to \gamma g$ partonic subprocesses and transverse momentum dependent (or unintegrated) quark and gluon densities in a proton, which are chosen in accordance with the Kimber-Martin-Ryskin prescription. We show that the sub-leading high-order ${\cal O}(\alpha \alpha_s^2)$ contributions, not covered by the non-collinear evolution of parton densities, are important to describe latest LHC data.

Relativistic corrections to the pair Bc-meson production in e+e− annihilation

Relativistic corrections to the pair Bc-meson production in e+e−-annihilation are calculated. We investigate a production of pair pseudoscalar, vector and pseudoscalar+vector Bc-mesons in the leading order perturbative quantum chromodynamics and relativistic quark model. Relativistic expressions of the pair production cross sections are obtained. Their numerical evaluation shows that relativistic effects in the production amplitudes and bound state wave functions three times reduce nonrelativistic results at the center-of-mass energy s=22 GeV.

Bcdiquark pair production in high energy proton-proton collisions

The cross section of pair double heavy diquark production process $pp\to(bc)+(\bar b \bar c)+X$ is calculated in the leading order of gluonic fusion channel with all four possible color and spin combinations $[^1S_0]_{\bar3}$, $[^1S_0]_{6}$, $[^3S_1]_{\bar3}$, and $[^3S_1]_{6}$ for each of the two final diquarks taken into account. Several sources of relativistic corrections to the cross section are handled in the framework of relativistic quark model. Perturbative $\mathcal O(v^2)$ corrections originating from the production amplitude expansions in heavy quark relative velocity~$v$ depend on the color and spin states of the final particles, but can be generally considered as unimportant ones giving maximally 12\% improvement in numerically significant cases. Modifications of the quark--quark and antiquark--antiquark bound state wave functions caused by the appropriate generalization of the Breit interaction potential have rather severe impact on the cross section suppressing it almost three times. Under assumption of antitriplets and sextuplets' nonperturbative parameters having the same order of magnitude, it is shown that the color-sextet mechanism strongly dominates pair diquark production in both nonrelativistic and relativistic approximations.

Investigating the preservation of orbital forcing in peritidal carbonates

AbstractMetre‐scale cycles in ancient peritidal carbonate facies have long been thought to represent the product of shallow water carbonate accumulation under orbitally controlled sea‐level oscillations. The theory remains somewhat controversial, however, and a contrasting view is that these cycles are the product of intrinsic, and perhaps random, processes. Owing to this debate, it is important to understand the conditions that do, or do not, favour the preservation of orbital forcing, and the precise stratigraphic expression of that forcing. In this work, a one‐dimensional forward model of carbonate accumulation is used to test the ability of orbitally paced sea‐level changes to reconstruct cyclicities and cycle stacking patterns observed in greenhouse peritidal carbonate successions. Importantly, the modelling specifically tests insolation‐based sea‐level curves that probably best reflect the pattern and amplitude of sea‐level change in the absence of large‐scale glacioeustasy. This study found that such sea‐level histories can generate precession and eccentricity water depth/facies cycles in models, as well as eccentricity‐modulated cycles in precession cycle thicknesses (bundles). Nevertheless, preservation of orbital forcing is highly sensitive to carbonate production rates and amplitudes of sea‐level change, and the conditions best suited to preserving orbital cycles in facies/water depth are different to those best suited to preserving eccentricity‐scale bundling. In addition, it can be demonstrated that the preservation of orbital forcing is commonly associated with both stratigraphic incompleteness (missing cycles) and complex cycle thickness distributions (for example, exponential), with corresponding implications for the use of peritidal carbonate successions to build accurate astronomical timescales.

Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold

The $\phi$-$\Lambda(1520)$ interference effect in the $\gamma p\to K^+K^-p$ reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between $\phi$ and $\Lambda(1520)$ production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when $K^+K^-$ pairs are observed at forward angles, but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the $\sqrt{s}=2.1$ GeV bump structure in forward differential cross sections for $\phi$ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange and rescattering processes via other hyperon states.

Long-range properties of1Sbottomonium states

In the framework of weakly-coupled pNRQCD, we derive, first, an analytical expression for the chromo-polarizability of $1S$-bottomonium states in agreement with previous determinations. Then we use the QCD trace anomaly to obtain the two-pion production amplitude for the chromo-polarizability operator and match the result to a chiral effective field theory with $1S$-bottomonium states and pions as degrees-of-freedom. In this chiral effective field theory we compute some long-range properties of the $1S$ bottomonium generated by the pion coupling such as the leading chiral logarithm to the $1S$-bottomonium mass and the van der Waals potential between two $1S$-bottomonium states. Both results improve on previously known expressions.

Fermion production in a magnetic field in a de Sitter universe

The process of fermion production in the field of a magnetic dipole on a de Sitter expanding universe is analyzed. The amplitude and probability for production of massive fermions are obtained using the exact solution of the Dirac equation written in the momentum-helicity basis. We found that the most probable transitions are those that generate the fermion pair perpendicular to the direction of the magnetic field. The behavior of the probability is graphically studied for large/small values of the expansion factor, and a detailed analysis of the probability in terms of the angle between the momenta vectors of the particle and antiparticle is performed. The phenomenon of fermion production is significant only at large expansion which corresponds to the conditions from the early Universe. When the expansion factor vanishes we recover the Minkowski limit where this process is forbidden by the simultaneous energy-momentum conservation.

Pion-induced production of theZc(3900)off a nuclear target

We investigate the possibility to study the charmoniumlike state ${Z}_{c}(3900)$ through the pion-induced production off a nuclear target. By using a high-energy pion beam, the ${Z}_{c}(3900)$ can be produced off a proton or nucleus though the Primakoff effect. The production amplitude is calculated in an effective Lagrangian approach combined with the vector dominance model. The total cross sections of the $p({\ensuremath{\pi}}^{\ensuremath{-}},{Z}_{c}^{\ensuremath{-}}(3900))$ and $p({\ensuremath{\pi}}^{\ensuremath{-}},{Z}_{c}^{\ensuremath{-}}(3900)\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{\ensuremath{-}})$ reactions are calculated, and their order of magnitude is about 0.1 and 0.01 nb, respectively, with an assumption of branch ratio 10% for the ${Z}_{c}(3900)$ decay in $J/\ensuremath{\psi}\ensuremath{\pi}$ channel. If the proton target is replaced by a nuclear target, the production of the ${Z}_{c}(3900)$ enhances obviously. The predicted total cross sections for the $A({\ensuremath{\pi}}^{\ensuremath{-}},{Z}_{c}^{\ensuremath{-}}(3900))$ and $A({\ensuremath{\pi}}^{\ensuremath{-}},{Z}_{c}^{\ensuremath{-}}(3900)\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{\ensuremath{-}})$ reactions with $A=^{12}\mathrm{C}$ or $^{208}\mathrm{Pb}$ are on the order of magnitude of 100 and 10 nb, respectively, which is about one thousand times larger than the cross sections off a proton target. Based on these results, we suggest the experimental study of the ${Z}_{c}(3900)$ by using high-energy pion beams with a nuclear target at facilities such as COMPASS and J-PARC.

Resonance matrix elements on the lattice

The notion of resonance matrix elements is discussed. The analogue of the Lellouch-Luscher formula for the pion photo(electro)production amplitude in the Δ(1232) resonance region is given. A prescription for the pole extraction of the ΔNγ * transition form factors is provided. Theoretical prospects on the lattice calculation of B → K *(892)l + l − form factors are briefly summarized.

Classical gluon production amplitude in heavy-ion collisions

The initial condition for the formation of the Quark-Gluon Plasma, the distribution of quarks and gluons produced in the initial stages of nuclear collisions, is the fundamental building block of heavy-ion theory. In the framework of saturation physics and Wilson lines formalism we calculate the scattering amplitude, beyond the leading order, of the classical gluon produced in heavy-ion collisions.known as the initial condition of the Quark-Gluon Plasma formation, is the fundamental building block of heavy-ion theory.