Binding energies of light, A≤6, ΛΛ hypernuclei are calculated using the stochastic variational method in a pionless effective field theory (π̸EFT) approach at leading order with the purpose of ...assessing critically the onset of binding in the strangeness S=−2 hadronic sector. The π̸EFT input in this sector consists of (i) a ΛΛ contact term constrained by the ΛΛ scattering length aΛΛ, using a range of values compatible with ΛΛ correlations observed in relativistic heavy ion collisions, and (ii) a ΛΛN contact term constrained by the only available A≤6 ΛΛ hypernucler binding energy datum of ΛΛ6He. The recently debated neutral three-body and four-body systems ΛΛ3n and ΛΛ4n are found unbound by a wide margin. A relatively large value of |aΛΛ|≳1.5 fm is needed to bind ΛΛ4H, thereby questioning its particle stability. In contrast, the particle stability of the A=5 ΛΛ hypernuclear isodoublet ΛΛ5H–ΛΛ5He is robust, with Λ separation energy of order 1 MeV.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Abstract
We analyze constraints from perturbative unitarity and crossing on the leading contributions of higher-dimension operators to the four-graviton amplitude in four spacetime dimensions, ...including constraints that follow from distinct helicity configurations. We focus on the leading-order effect due to exchange by massive degrees of freedom which makes the amplitudes of interest infrared finite. In particular, we place a bound on the coefficient of the
R
3
operator that corrects the graviton three-point amplitude in terms of the
R
4
coefficient. To test the constraints we obtain nontrivial effective field-theory data by computing and taking the large-mass expansion of the one-loop minimally-coupled four-graviton amplitude with massive particles up to spin 2 circulating in the loop. Remarkably, we observe that the leading EFT coefficients obtained from both string and one-loop field-theory amplitudes lie in small islands. The shape and location of the islands can be derived from the dispersive representation for the Wilson coefficients using crossing and assuming that the lowest-spin spectral densities are the largest. Our analysis suggests that the Wilson coefficients of weakly-coupled gravitational physical theories are much more constrained than indicated by bounds arising from dispersive considerations of 2 → 2 scattering. The one-loop four-graviton amplitudes used to obtain the EFT data are computed using modern amplitude methods, including generalized unitarity, supersymmetric decompositions and the double copy.
We published a meta-analysis of studies that examined the various components of an evidence-based therapy called emotional freedom techniques (EFTs). EFT uses elements of conventional therapies such ...as exposure and cognitive processing but includes the unique ingredient of acupoint stimulation using fingertip tapping. Six studies were identified, and three of these met the quality control criteria of the American Psychological Association's Division 12 Task Force for Empirically Validated Therapies. Meta-analysis found that the acupoint component of EFT was not an inert ingredient or inactive placebo but made an active contribution to the therapeutic effects noted in a research literature that now numbers over 100 clinical trials of EFT. Subsequent to publication, errors in the original analysis were identified, primarily incorrect standard deviations. A new analysis was performed by an independent statistician and found slightly greater effects than the original investigation. The results were published as a corrigendum, which was subsequently challenged by Spielmans. Here we examine the critiques of the corrigendum and original article. We find that although they may be of academic interest, they are irrelevant to the central research question of whether the acupoint component of EFT is inert or active. We reaffirm that the evidence clearly validates the contribution made by acupoint tapping to EFT's observed clinical effects.
Higgs boson production in association with a photon (H+ ) offers a promising channel to test the Higgs boson to photon coupling at various energy scales. Its potential sensitivity to anomalous ...couplings of the Higgs boson has not been explored with the proton-proton collision data. In this paper, we reinterpret the latest ATLAS H+ resonance search results within the Standard Model effective field theory (EFT) framework, using 36.1 fb−1 of proton-proton collision data recorded with the ATLAS detector at TeV. Constraints on the Wilson coefficients of dimension-six EFT operators related to the Higgs boson to photon coupling are provided for the first time in the H+ final state at the LHC.
The microstructure of the polymer PBDTTT‐EFT and blends with the fullerene derivative PC71BM that achieve solar conversion efficiencies of over 9% is comprehensively investigated. A combination of ...synchrotron techniques are employed including surface‐sensitive near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy and bulk‐sensitive grazing‐incidence wide angle X‐ray scattering (GIWAXS). A preferential “face‐on” orientation of PBDTTT‐EFT is observed in the bulk of both pristine and blend thin films, with π–π stacking largely normal to the substrate, which is thought to be beneficial for charge transport. At the surface of the blend, a slight “edge‐on” structure of the polymer is observed with side‐chains aligned normal to the substrate. The effect of the solvent additive 1,8‐diiodooctane (DIO) on solar cell efficiency and film microstructure is also investigated, where the addition of 3 vol% DIO results in an efficiency increase from ≈6.4% to ≈9.5%. GIWAXS studies indicate that the addition of DIO improves the crystallization of the polymer. Furthermore, atomic force microscopy and transmission electron microscopy are employed to image surface and bulk morphology revealing that DIO suppresses the formation of large PC71BM aggregates.
The morphology of a novel and highly efficient polymer solar cell is comprehensively investigated using surface sensitive near‐edge X‐ray absorption fine structure spectroscopy and bulk‐sensitive grazing incidence wide angle X‐ray scattering. The solvent additive 1,8‐diiodooctane in particular is shown to be effective at controlling fullerene aggregation and enhancing polymer ordering, facilitating efficiencies of over 9%.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We review the current state of knowledge of the nucleon polarizabilities and of their role in nucleon Compton scattering and in hydrogen spectrum. We discuss the basic concepts, the recent lattice ...QCD calculations and advances in chiral effective-field theory. On the experimental side, we review the ongoing programs aimed to measure the nucleon (scalar and spin) polarizabilities via the Compton scattering processes, with real and virtual photons. A great part of the review is devoted to the general constraints based on unitarity, causality, discrete and continuous symmetries, which result in model-independent relations involving nucleon polarizabilities. We (re-)derive a variety of such relations and discuss their empirical value. The proton polarizability effects are presently the major sources of uncertainty in the assessment of the muonic hydrogen Lamb shift and hyperfine structure. Recent calculations of these effects are reviewed here in the context of the “proton-radius puzzle”. We conclude with summary plots of the recent results and prospects for the near-future work.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Heavy vectorlike quarks (VLQs) appear in many models of beyond the Standard Model physics. Direct experimental searches require these new quarks to be heavy, ≳800–1000 GeV. We perform a global fit ...of the parameters of simple VLQ models in minimal representations of SU(2)L to precision data and Higgs rates. An interesting connection between anomalous Zbb¯ interactions and Higgs physics in VLQ models is discussed. Finally, we present our analysis in an effective field theory (EFT) framework and show that the parameters of VLQ models are already highly constrained. Exact and approximate analytical formulas for the S and T parameters in the VLQ models we consider are available in the Supplemental Material as Mathematica files.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The program AutoEFT is described. It allows one to generate Effective Field Theories (EFTs) from a given set of fields and symmetries. Allowed fields include scalars, spinors, gauge bosons, and ...gravitons. The symmetries can be local or global Lie groups based on U(1) and SU(N). The mass dimension of the EFT is limited only by the available computing resources. The operators are stored in a compact, human and machine-readable format. Aside from the program itself, we provide input files for EFTs based on the Standard Model and a number of its extensions. These include additional particles and symmetries, EFTs with minimal flavor violation, and gravitons.
Program title:AutoEFT
CPC Library link to program files:https://doi.org/10.17632/z8xm2hpbsp.1
Developer's repository link:https://gitlab.com/auto_eft/autoeft
Licensing provisions: MIT license
Programming language:Python
Nature of problem: The bottom-up construction of an Effective Field Theory (EFT) which describes physics below a certain energy scale Λ requires obtaining a set of operators, composed of fields with mass m≪Λ, that are invariant under certain symmetries. One is primarily interested in complete sets of independent operators, called operator bases. Their construction for a given mass dimension of the operators is nontrivial due to algebraic and kinematic relations that may render different operators redundant. Except for the lowest mass dimensions, the number of operators is so large that the task of constructing an explicit EFT operator basis requires a high degree of automation on a computer. In addition, an automated approach will allow one to immediately take into account newly postulated or discovered light particles beyond the Standard Model.
Solution method: Based on the group theoretical techniques and concepts established in Refs. 1–9 and in particular Refs. 10,11, we developed the program AutoEFT, capable of constructing a non-redundant on-shell operator basis for general EFTs and arbitrary mass dimension. Provided a suitable model file, the respective operator basis is generated explicitly, including contractions of the symmetry group indices, in a fully automated fashion. Due to the generality of the algorithm, it can be applied to a variety of low-energy scenarios. The underlying low-energy theory is encoded in a model file which defines the symmetries and the field content. The fairly simple format enables the user to compose their own model files and to construct the respective operator basis with minimal effort.
Additional comments including restrictions and unusual features: In its current form, AutoEFT is restricted to theories including particles with spin 0, 1/2, 1, and 2, where the latter two are considered massless. In addition, AutoEFT only constructs operators that mediate proper interactions, meaning that any operator must be composed of at least three fields. The internal symmetries must be given as factors of U(1) and SU(N) groups. In principle, operator bases can be generated for any mass dimension, which is, however, limited by the available computing resources.
1Y. Shadmi, Y. Weiss, Effective field theory amplitudes the on-shell way: scalar and vector couplings to gluons, J. High Energy Phys. 02 (2019) 165, arXiv:1809.09644 hep-ph.2B. Henning, T. Melia, Conformal-helicity duality & the Hilbert space of free CFTs, arXiv:1902.06747 hep-th.3T. Ma, J. Shu, M.-L. Xiao, Standard model effective field theory from on-shell amplitudes, Chin. Phys. C 47 (2023) 023105, arXiv:1902.06752 hep-ph.4B. Henning, T. Melia, Constructing effective field theories via their harmonics, Phys. Rev. D 100 (2019) 016015, arXiv:1902.06754hep-ph.5R. Aoude, C.S. Machado, The Rise of SMEFT on-shell amplitudes, J. High Energy Phys. 12 (2019) 058, arXiv:1905.11433 hep-ph.6R.M. Fonseca, Enumerating the operators of an effective field theory, Phys. Rev. D 101 (2020) 035040, arXiv:1907.12584 hep-ph.7G. Durieux, T. Kitahara, Y. Shadmi, Y. Weiss, The electroweak effective field theory from on-shell amplitudes, J. High Energy Phys. 01 (2020) 119, arXiv:1909.10551 hep-ph.8A. Falkowski, Bases of massless EFTs via momentum twistors, arXiv:1912.07865hep-ph.9G. Durieux, C.S. Machado, Enumerating higher-dimensional operators with on-shell amplitudes, Phys. Rev. D 101 (2020) 095021, arXiv:1912.08827 hep-ph.10H.-L. Li, Z. Ren, J. Shu, M.-L. Xiao, J.-H. Yu, Y.-H. Zheng, Complete set of dimension-eight operators in the standard model effective field theory, Phys. Rev. D 104 (2021) 015026, arXiv:2005.00008hep-ph.11H.-L. Li, Z. Ren, M.-L. Xiao, J.-H. Yu, Y.-H. Zheng, Complete set of dimension-nine operators in the standard model effective field theory, Phys. Rev. D 104 (2021) 015025, arXiv:2007.07899 hep-ph.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The discovery of the Higgs boson with its mass around 125 GeV by the ATLAS and CMS Collaborations marked the beginning of a new era in high energy physics. The Higgs boson will be the subject of ...extensive studies of the ongoing LHC program. At the same time, lepton collider based Higgs factories have been proposed as a possible next step beyond the LHC, with its main goal to precisely measure the properties of the Higgs boson and probe potential new physics associated with the Higgs boson. The Circular Electron Positron Collider~(CEPC) is one of such proposed Higgs factories. The CEPC is an $e^+e^-$ circular collider proposed by and to be hosted in China. Located in a tunnel of approximately 100~km in circumference, it will operate at a center-of-mass energy of 240~GeV as the Higgs factory. In this paper, we present the first estimates on the precision of the Higgs boson property measurements achievable at the CEPC and discuss implications of these measurements.
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