Tree Level Research Articles

A complete set of 4-point amplitudes in the constructive Standard Model

We present a complete set of 4-point amplitudes in the constructive Standard Model at tree level. Any 4-point amplitude can be obtained from the results presented here by a suitable choice of masses, a permutation of the particles (by crossing symmetry), and a reversal of the momenta of the outgoing particles. We have validated all of these amplitudes by comparing with Feynman diagrams for a variety of masses, scattering energy and angles, and helicities of the photons and gluons, when they are in the initial states. The standard constructive techniques work for these amplitudes without the need for any contact terms and indeed, contact terms are not allowed. Only three 4-point vertices are used (allowed), involving the Higgs boson and the W and Z bosons. When external photons or gluons are present, the amplitude simplifies to a single spinor-product structure, present in the numerator. In a few cases, however, the propagator structure is more complex, with different terms depending on the charge or color structure. In the case of internal photons or gluons, we find that the massless limit of a massive photon or gluon diagram gives the correct result in all cases. We have additionally found that using the x factor directly gives the correct result in all cases and agrees with the massless limit calculation.

One-loop elastic amplitudes from tree-level elasticity in 2d

In this paper we extend the study initiated in [1] to the computation of one-loop elastic amplitudes. We consider 1+1 dimensional massive bosonic Lagrangians with polynomial-like potentials and absence of inelastic processes at the tree level; starting from these assumptions we show how to write sums of one-loop diagrams as products and integrals of tree-level amplitudes. We derive in this way a universal formula for the one-loop two-to-two S-matrices in terms of tree S-matrices. We test our results on different integrable theories, such as sinh-Gordon, Bullough-Dodd and the full class of simply-laced affine Toda theories, finding perfect agreement with the bootstrapped S-matrices known in the literature. We show how Landau singularities in amplitudes are naturally captured by our universal formula while they are lost in results based on unitarity-cut methods implemented in the past [2, 3].

New Intrinsic Ecological Mechanisms of Leaf Nutrient Resorption in Temperate Deciduous Trees.

Leaf nutrient resorption is a critical process in plant nutrient conservation during leaf senescence. However, the ecological mechanisms underlying the large variability in nitrogen (NRE) and phosphorous (PRE) resorption efficiencies among trees remain poorly understood. We conducted a comprehensive study on NRE and PRE variability using 61 tree individuals of 10 temperate broad-leaved tree species. Three potentially interrelated intrinsic ecological mechanisms (i.e., leaf senescence phenology, leaf pigments, and energy residual) were verified. We found that a delayed leaf senescence date, increased degradation of chlorophylls and carotenoids, biosynthesis of anthocyanins, and reduced nonstructural carbohydrates were all positively correlated with NRE and PRE at the individual tree level. The intrinsic factors affecting resorption efficiency were ranked in decreasing order of importance: leaf pigments > energy residual > senescence phenology. These factors explained more variability in NRE than in PRE. Our findings highlight the significance of these three ecological mechanisms in leaf nutrient resorption and have important implications for understanding how nutrient resorption responds to climate change.

Top-philic ALP phenomenology at the LHC: the elusive mass-window

We study the LHC phenomenology of an Axion Like Particle (ALP) that couples only derivatively with the top quark at tree level. We inspect the radiatively induced couplings with the SM fermions and (gauge) bosons and the associated production and decay mechanisms of the ALP. We focus on the most challenging mass window that remains open for a top-philic ALP, i.e., the range between tens and hundreds of GeV. Not only ALP production processes but also virtual ALP contributions to final states with top quarks are considered in detail. We show how searches through resonant production, such as ALP production in association with a tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} $$\\end{document} pair, are complementary to precision measurements of tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} $$\\end{document} and tt¯tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}t\\overline{t} $$\\end{document} final states, the latter being competitive or even more powerful for a top-philic ALP in this mass window. Finally, we explore the scenario where the top-philic ALP acts as a mediator to a dark-matter sector, resulting in missing energy signatures at the LHC. We find that the LHC constraints from tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} $$\\end{document}, tt¯tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}t\\overline{t} $$\\end{document} and ALP + jet production, together with those from tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} $$\\end{document} + ALP production, can already exclude a large fraction of the parameter space leading to the correct relic abundance.

STRUKTUR DAN KOMPOSISI HUTAN MANGROVE DI NEGERI HATUSUA KECAMATAN KAIRATU KABUPATEN SERAM BAGIAN BARAT

The aim of this research is to determine the structure and composition of mangrove forests in Hatusua State, Kairatu District, West Seram Regency. And vegetation analysis was carried out by collecting data on the type, number, diameter and height of trees. In this research, the path method was used by carrying out a 100% inventory. The measuring plot area for the vegetation growth level of Seedlings, Saplings and Trees is 20 m x 20 m, a total of 46 plots for a total area of ​​1.84 ha. The research results show that the mangrove forests in Hatusua State can be divided into two from inundation, namely the middle zone and the distal zone, where in this mangrove forest there is no proximal zone because there are no mangroves that face the sea. The stratification of Hatusua State's mangrove forests is simpler than that of mainland natural forests. Mangrove trees in Hatusua Country can reach a tree height of 15 – 25 meters, which are dominated by Rhizophora apiculata, Heritiera littoralis, Parmentiera cereifera, and Intsia bijuga. The Hatusua State mangrove forest diversity index value of 1.37 seedlings, 2.30 saplings and 1.36 trees is categorized as medium because the value 1 <H' < 3.

Short Communication: Estimation of aboveground biomass and carbon sequestration in KGPAA Mangkunagoro I Grand Forest Park, Central Java, Indonesia

Abstract. Indriyani S, Sari SP, Negari SIT, Prambudi SA, Nur AAI, Kusumaningrum L, Indrawan M, Sunarto, Sugiyarto, Budiharta S, Setyawan AD. 2024. Short Communication: Estimation of aboveground biomass and carbon sequestration in KGPAA Mangkunagoro I Grand Forest Park, Central Java, Indonesia. Biodiversitas 25: 2257-2263. Forests play an important role in climate change mitigation by absorbing carbon dioxide in the atmosphere and store it in the form of biomass. Valuation of carbon storage potential of a forest will provide insight on the importance of preserving it. This study aims to assess plant diversity and estimate aboveground biomass, carbon stocks, carbon dioxide sequestration potential, and the economic value of ecosystem services from carbon sequestration in KGPAA Mangkunagoro I Grand Forest Park, Central Java, Indonesia. We used a non-destructive method (i.e. allometric equation) in estimating aboveground biomass and carbon stock. We established 50 sampling plots to identify and measure trees (DBH >20 cm) and poles (10<DBH<20 cm). The results showed that there were 30 species from 20 families found in the observation plots. The potential aboveground biomass at the tree and pole level was 297.92 tons/ha and 57.22 tons/ha, respectively, while the total carbon stock for tree and pole was 140.02 tons/ha and 26.89 tons/ha, respectively. This was equivalent to carbon dioxide sequestration of 513.88 tons/ha and 98.70 tons/ha for trees and poles. The economic value of environmental services from carbon stock in the whole area of KGPAA Mangkunagoro I Grand Forest Park was estimated at IDR 21,289,040,253. The results of this research show that apart from playing a role in mitigating climate change by absorbing carbon, KGPAA Mangkunagoro I Grand Forest Park also has valuable economic value.

Interpreting the W-mass and muon (gμ − 2) anomalies within a 2-Higgs doublet model

In this study, we investigate the anomalous magnetic moment of the muon (gμ−2) as reported by Fermilab (FNAL), along with the recent measurement of the W-boson mass by the CDF-II collaboration. Both findings show significant deviations from the predictions of the Standard Model (SM), hinting at the possibility of new physics. Our focus is on the Type III two-Higgs-doublet model (2HDM), wherein both Higgs doublets couple with all fermions, leading to the induction of flavour-changing neutral currents (FCNCs) at the tree level. Within this framework, we investigate a lepton-flavour-violating (LFV) scenario, aiming to explain both observed anomalies, while satisfying the up-to-date theoretical and experimental constraints.

Is ward-level calculation of urban green space availability important?—A case study on Vellore city, India, using the histogram-based spectral discrimination approach

How much green space is available for individuals is a major question that city planners are generally interested in, and the present study aimed to address this issue in the context of Vellore, India, through two approaches, namely, the per capita and the geographical area approach. In existing studies, urban green space (UGS) was only calculated at the macro level, i.e., for the city as a whole. Micro-or ward-level analysis was not attempted before, and the present study carried out the same to get a clear picture of the amount of greenery available in each ward of a city. For this purpose, a two-step approach was proposed where the histograms of Google Earth (GE) images were analyzed first to check whether the green cover types such as trees, shrubs/grassland, and cropland were spectrally different. Then, classification techniques such as ISODATA, maximum likelihood, support vector machine (SVM), and object-based methods were applied to the GE images. It was found that SVM performed well in extracting different green cover types with the highest overall accuracy of 93% and Kappa coefficient of 0.881. It was found that when considering the city as a whole, the amount of UGS available is 42% of the total area, which is more than the recommended range of 20–40%. Similarly, the available UGS per person is 97.84 m2, which is far above the recommended 12 m2/person. However, the micro-level analysis revealed that some of the wards have not satisfied the criteria of per capita and percentage area, though the city as a whole has satisfied both the criteria. Thus, the results indicate the importance of calculating the urban green space availability at the ward level rather than the city level as the former gives a closer look at the surplus and deficit areas. The results of terrestrial LiDAR survey at individual tree level revealed that if trees are located adjacent to buildings or roads, it results in fewer heat islands compared to the case where there are no trees.

Strongly-ordered infrared counterterms from factorisation

In the context of infrared subtraction algorithms beyond next-to-leading order, it becomes necessary to consider multiple infrared limits of scattering amplitudes, in which several particles become soft or collinear in a strongly-ordered sequence. We study these limits from the point of view of infrared factorisation, and we provide general definitions of strongly-ordered soft and collinear kernels in terms of gauge-invariant operator matrix elements. With these definitions in hand, it is possible to construct local subtraction counterterms for strongly-ordered configurations. Because of their factorised structure, these counterterms cancel infrared poles of real-virtual contributions by construction. We test these ideas at tree level for multiple emissions, and at one loop for single and double emissions, contributing to NNLO and N3LO distributions, respectively.

Integration of field measurements with unmanned aerial vehicle to predict forest inventory metrics at tree and stand scales in natural pure Crimean pine forests

ABSTRACT Inventorying forest ecosystems is an essential part of forest management planning. However, it is quite costly and time-consuming, particularly for larger areas. Recently, significant developments have been made in unmanned aerial vehicle (UAV) technology to improve the cost and time efficiency in forest inventory. Therefore, UAV images have become one of the inventory tools that produces data with high spatial resolution in determining forest resources. This study aims to investigate the contribution of UAV data to forest inventory in a case study area with a total of 30 sample plots located in pure and natural Crimean pine (Pinus nigra J.F. Arnold ssp. pallasiana (Lamb.) Holmboe) stands in the Black Sea backward region of Türkiye. Total tree height (h) and stem volume (v) were recorded at individual tree level (n = 367), and the number of trees (N), mean height (hmean), top height (htop), stand basal area (BA) and stand volume (V) were calculated at sample plot level (n = 30) from both the field and UAV-based data. Pearson’s correlation coefficients (r) for h and v were 0.96 and 0.72, respectively, the highest correlation at the sample plot level was observed for the hmean - htop (r = 0.96), while the lowest correlation was found for BA (r = 0.54). The suitability of the observation and prediction values was assessed using a t-test at both individual tree and sample plot levels. According to the t-test results, the observation and prediction values for h, v, hmean, htop, BA and V metrics were found to be compatible (p > 0.05), but not for N (p < 0.05). Overall results indicated that UAV technology has a potential to be used in forest inventory and can contribute to the determination of individual tree and stand metrics. Thereby, it saves cost and time in forest inventory studies and helps monitoring the dynamic structure of the forest ecosystem with an effective approach in forest inventory.

A new framework for higher loop Witten diagrams

The differential representation is a novel formalism for studying boundary correlators in (d + 1)-dimensional anti-de Sitter space. In this letter, we generalize the differential representation beyond tree level using the notion of operator-valued integrals. We use the differential representation to compute three-point bubble and triangle Witten diagrams with external states of conformal dimension ∆ = d. We compare the former to a position space computation.

KERAPATAN DAN KELAS KEHADIRAN JENIS EHA (CASTANOPSIS BURUANA MIQ) DI BLOK LINDUNG TAHURA NIPA-NIPA KELURAHAN PUNGGALOBA KENDARI

The Tahura Nipa-Nipa nature conservation area located in the city of Kendari has a type of Eha that is susceptible to disturbance. The research aimed to determine the density level of the Eha (Castanopsis buruana Miq) species at tree, pole, sapling and seedling level growth; knowing the presence class in the community (presence) and knowing the distribution pattern. The observation sample used the plotted path method with a sampling intensity of 1% and an entire sample area of 0.96 ha. The sample consisted of 3 transects each containing 8 plots (0.04 ha per plot), so the total sample was 24 plots. Transects were placed systematically, the distance between transects was 100 m, and the distance between plots within transects was 20 m. The results showed that the Eha tree density level was 107.29 trees/ha, the pole level was 200 trees/ha, the sapling level was 233.33 trees/ha, and the seedling level was 13229.166 trees/ha. The presence of Eha in the community at the tree, pole and seedling level is in the "Always Present" class (81%-100%). Meanwhile, the stake level and presence in the community is in the "Sometimes There" class (21%-40%). The distribution pattern of Eha at the tree level is clustered, while at the pole, sapling and seedling levels it is a regular pattern.

Complete tree-level dictionary between simplified BSM models and SMEFT d≤7 operators

Finding all possible UV resonances of effective operators is an important task in the bottom-up approach of effective field theory. We present all the tree-level UV resonances for the dimension-5, -6, and -7 operators in the Standard Model effective field theory (SMEFT) and then obtain the correspondence between the UV resonances and the effective operators from the relations among their Wilson coefficients, through the functional matching and operator reduction procedure. This provides a cross-dimension UV/IR dictionary for the SMEFT at tree level, and the methods used here, especially the on shell construction of general UV Lagrangian and the systematic reduction of operators, are extendable for UV resonances of d≥8 operators in SMEFT and other effective field theories. Published by the American Physical Society 2024

Assisted baryon number violation in 4k+2 dimensions

Proton decay in six-dimensions orbifolded on square T2/Z2 is highly suppressed at tree level. This is because baryon number violating (BNV) operators containing only the zero mode of bulk fermions must satisfy the selection rule 32ΔB±12ΔL=0 mod 4. In this article, we show that the above relation does not prohibit mass dimension-six BNV operators containing Kaluza-Klein partners of the bulk fermions. Together with a “spinless” adjoint scalar partner of hypercharge gauge boson (the dark matter candidate), these novel operators generate dark matter assisted proton decay at mass dimension eight. Here, with explicit examples of scalar and vector baryon number violating interactions, we discuss the importance of such ΔB=1=ΔL and ΔB=2=ΔL operators and derive the limit on new physics. Published by the American Physical Society 2024

Freeze-in production of sterile neutrino dark matter in a gauged U(1)′ model with inverse seesaw

We consider a general, anomaly free U(1)′ extension of the Standard Model (SM) where the neutrino mass is generated at the tree level via the inverse seesaw mechanism. The model contains three right handed neutrinos, three additional singlet fermions, one extra complex scalar and a neutral gauge boson (Z′). Instead of resorting to a specific U(1) extension, we consider a class of models by taking the U(1)′ charges of the scalars to be free parameters. Here, we assign one pair of the pseudo-Dirac degenerate sterile neutrinos as Dark Matter (DM) candidates which are produced by the freeze-in mechanism. Considering different mass regimes of the DM, Z′ and reheating temperature, we obtain constraints on the U(1)′ charges giving the correct relic abundance. We have also obtained constraints on Z′ mass and coupling from consideration of relic density as well as high energy collider experiments like ATLAS in case of heavy Z′ or in intensity and lifetime frontier experiments like DUNE, FASERs, and ILC beam dump which are looking for light Z′. Additionally, in this model, the decay of pseudo-Dirac DM into active neutrinos can explain the 511 keV line observed by the INTEGRAL satellite.

The gustatory stalk of the Remo flounder exemplifies how complex evolutionary novelties may arise

The appearance of evolutionary novelties is a central issue in biology. Since Darwin’s theory, difficulties in explaining how novel intricate body parts arose have often been used by creationists and other deniers to challenge evolution. Here, we describe the gustatory stalk of the Remo flounder (Oncopterus darwinii), an anatomically and functionally complex organ presumably used as a chemoreceptor probe to detect prey buried in the substrate. We demonstrate that the gustatory stalk is derived from the first dorsal-fin ray, which acquired remarkable modifications in its external morphology, integument, skeleton, muscles, and nerves. Such structural innovations are echoed in both functional and ecological specializations. We reveal that the gustatory stalk arose through the gradual accumulation of changes that evolved at different levels of the phylogenetic tree of ray-finned fishes. At least five preconditions arose in nodes preceding Oncopterus darwinii. This finding constitutes an interesting example of how evolution can deeply remodel body parts to perform entirely new functions. In this case, a trivial support structure primitively used for swimming became a sophisticated sensory tool to uncover hidden prey.

Maximising CP Violation in naturally aligned Two-Higgs Doublet Models

The Two-Higgs Doublet Model (2HDM) is a well-motivated theoretical framework that provides additional sources of CP Violation (CPV) beyond the Standard Model (SM). After studying the vacuum topology of a general (convex) 2HDM potential, we unambiguously identify three origins of CPV: (i) Spontaneous CPV (SCPV), where the vacuum manifold has at least two degenerate CPV minima disconnected by domain walls, (ii) Explicit CPV (ECPV) with one single CPV ground state, and (iii) Mixed Spontaneous and Explicit CPV (MCPV), where the theory possesses more than one non-degenerate CPV local minimum. Most importantly, we define a novel complex parameter rCP whose norm and phase control the three different realisations of CPV, at least at the tree level. In all these scenarios, only two CPV phases can be made independent, as any third CPV parameter will always be constrained via the CP-odd tadpole condition. Since ECPV vanishes in 2HDMs where SM Higgs alignment is achieved naturally through accidental continuous symmetries, we analyse the possibility of maximising CPV through soft and explicit breaking of these symmetries. We derive upper limits on key CPV parameters that quantify the degree of SM misalignment from constraints due to the non-observation of an electron Electric Dipole Moment (EDM). Finally, we delineate the CP-violating parameter space of the so-constrained naturally aligned 2HDMs that can further be probed at the CERN Large Hadron Collider (LHC).

A Fast Time Synchronization Method for Large Scale LEO Satellite Networks Based on A Bionic Algorithm

A fast time synchronization method for large-scale LEO satellite networks based on a bionic algorithm is proposed. Because the inter-satellite links are continuously established and interrupted due to the relative motion of the satellites, the topology of the LEO satellite networks is time varying. Firstly, according to the ephemeris information in navigation messages, a connection table which records the connections between satellites is generated. Then, based on the connection table, the current satellite network topology is calculated and generated. Furthermore, a bionic algorithm is used to select some satellites as time source nodes and calculate the hierarchy of the clock transmission tree. By taking the minimum level of the time transmission tree as the optimization objective, the time source nodes and the clock stratums of the whole satellite networks are obtained. Finally, the onboard computational center broadcasts the time layer table to all the satellites in the LEO satellite networks and the time synchronization links can be established or recovered fast.

A citizen science method to monitor a polyphagous shot hole borer infestation in Johannesburg's urban forest

Citizen science has become a powerful tool for gathering data, and the validity of these data should be tested. The accuracy of a citizen science database used to monitor the polyphagous shothole borer (PSHB) (Euwallacea fornicatus) (Coleoptera: Curculionidae: Scolytinae) infestation in a suburb of the city of Johannesburg was assessed. Out of 785 trees surveyed by the citizen scientists, 157 trees (20%) were selected as a validation data set to confirm the tree identity, tree health status and level of PSHB infestation. A chi-square (χ2) test was performed to examine whether there was a significant agreement between the citizen scientists’ and researcher’s data used for the classification of the tree infestation, tree health status and PSHB infestation holes. A Cohen’s kappa coefficient was calculated to determine the level of agreement between the two different sources of data, for the infested parts (trunk, main branches, and canopy branches) of the trees surveyed and PSHB infestation signs. The two surveys showed no significance difference for classifying tree health status and PSHB infestation holes. There was a high level of agreement between citizen scientists and the researcher ratings for measures of PSHB infestation (kappa values ranging between 0.71 and 0.89) and the level of agreement was significant. In conclusion, citizen science allowed us to obtain a large quantity of data at a low cost that correlated with the researchers’ validation dataset. Citizen science is a useful method for monitoring PSHB in a diverse urban forest in trees that show obvious signs of infestation.

Cosmological constraints from the EFT power spectrum and tree-level bispectrum of 21 cm intensity maps

We explore the information content of 21 cm intensity maps in redshift space using the 1-loop Effective Field Theory power spectrum model and the bispectrum at tree level. The 21 cm signal contains signatures of dark matter, dark energy and the growth of large-scale structure in the Universe. These signatures are typically analysed via the 2-point correlation function or power spectrum. However, adding the information from the 3-point correlation function or bispectrum will be crucial to exploiting next-generation intensity mapping experiments. The bispectrum could offer a unique opportunity to break key parameter degeneracies that hinder the measurement of cosmological parameters and improve on the precision. We use a Fisher forecast analysis to estimate the constraining power of the HIRAX survey on cosmological parameters, dark energy and modified gravity.