scholarly journals An effective field theory approach for electroweak interactions in the high energy limit

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Melina Gómez Bock ◽  
Martin Hentschinski ◽  
Agustín Sabio Vera
Keyword(s):  
Degrees Of Freedom ◽  
High Energy ◽  
Effective Field ◽  
Theory Approach ◽  
Energy Limit ◽  
The Standard Model ◽  
Electroweak Sector ◽  
Electroweak Boson ◽  
Regge Limit ◽  
Logarithmic Accuracy

AbstractWe present an effective action for the electroweak sector of the standard model valid for the calculation of scattering amplitudes in the high energy (Regge) limit. Gauge invariant Wilson lines are introduced to describe reggeized degrees of freedom whose interactions are generated by effective emission vertices. From this approach previous results at leading logarithmic accuracy for electroweak boson Regge trajectories are reproduced together with the corresponding interaction kernels. The proposed framework lays the path for calculations at higher orders in perturbation theory.

scholarly journals Unitarity violation and the geometry of Higgs EFTs

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Timothy Cohen ◽  
Nathaniel Craig ◽  
Xiaochuan Lu ◽  
Dave Sutherland
Keyword(s):  
Standard Model ◽  
Higgs Field ◽  
Higgs Sector ◽  
High Energy ◽  
Effective Field ◽  
Energy Limit ◽  
Geometric Invariants ◽  
Energy Behavior ◽  
The Standard Model ◽  
Derivatives Of

Abstract We derive the scale of unitarity violation from the geometry of Effective Field Theory (EFT) extensions of the Standard Model Higgs sector. The high-energy behavior of amplitudes with more than four scalar legs depends on derivatives of geometric invariants with respect to the physical Higgs field h, such that higher-point amplitudes begin to reconstruct the scalar manifold away from our vacuum. In theories whose low-energy limit can be described by the Higgs EFT (HEFT) but not the Standard Model EFT (SMEFT), non-analyticities in the vicinity of our vacuum limit the radius of convergence of geometric invariants, leading to unitarity violation at energies below 4πv. Our results unify approaches to the HEFT/SMEFT dichotomy based on unitarity, analyticity, and geometry, and more broadly illustrate the sense in which observables probe the geometry of an EFT. Along the way, we provide novel basis-independent results for Goldstone/Higgs boson scattering amplitudes expressed in terms of geometric covariant quantities.

scholarly journals Searching for elusive dark sectors with terrestrial and celestial observations

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Roberto Contino ◽  
Kevin Max ◽  
Rashmish K. Mishra
Keyword(s):  
Field Theory ◽  
Broad Class ◽  
High Energy ◽  
Effective Field ◽  
Dark Sector ◽  
Minimum Requirement ◽  
Conformal Field ◽  
Starting Point ◽  
The Standard Model ◽  
Visible Sector

Abstract We consider the possible existence of a SM-neutral and light dark sector coupled to the visible sector through irrelevant portal interactions. Scenarios of this kind are motivated by dark matter and arise in various extensions of the Standard Model. We characterize the dark dynamics in terms of one ultraviolet scale Λuv, at which the exchange of heavy mediator fields generates the portal operators, and by one infrared scale ΛIR, setting the mass gap. At energies ΛIR « E « Λuv the dark sector behaves like a conformal field theory and its phenomenology can be studied model independently. We derive the constraints set on this scenario by high- and low-energy laboratory experiments and by astrophysical observations. Our results are conservative and serve as a minimum requirement that must be fulfilled by the broad class of models satisfying our assumptions, of which we give several examples. The experimental constraints are derived in a manner consistent with the validity of the effective field theory used to define the portal interactions. We find that high-energy colliders give the strongest bounds and exclude UV scales up to a few TeV, but only in specific ranges of the IR scale. The picture emerging from current searches can be taken as a starting point to design a future experimental strategy with broader sensitivity.

scholarly journals PROBING HIGH ENERGY PROPERTY OF STRING SCATTERING BY EFFECTIVE FIELD THEORY

2013 ◽  
Vol 21 ◽  
pp. 153-154
Author(s):  
CHUAN-TSUNG CHAN ◽  
SHOICH KAWAMOTO ◽  
DAN TOMINO
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Open String ◽  
High Energy ◽  
Effective Field ◽  
Energy Limit ◽  
High Energy Limit ◽  
Linear Relations ◽  
Massive Spin ◽  
Symmetry Structure

It is known that infinitely many linear relations among string scattering amplitudes appear in high energy limit. These linear relations would imply a symmetry structure that is not manifest before taking the high energy limit. Motivated by this observation, we study an effective field theory of massive spin-2 and spin-1 particles, and try to understand what kind of structure reproduces the linear relations among the amplitudes of bosonic open string.

scholarly journals Effective Theory Approach to Direct Detection of Dark Matter

2020 ◽  
pp. 650-688
Author(s):  
Junji Hisano
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Particle Physics ◽  
Direct Detection ◽  
Effective Field ◽  
Weakly Interacting Massive Particles ◽  
Effective Theory ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
The Standard Model

It is now certain that dark matter exists in the Universe. However, we do not know its nature, nor are there dark matter candidates in the standard model of particle physics or astronomy However, weakly interacting massive particles (WIMPs) in models beyond the standard model are one of the leading candidates available to provide explanation. The dark matter direct detection experiments, in which the nuclei recoiled by WIMPs are sought, are one of the methods to elucidate the nature of dark matter. This chapter introduces an effective field theory (EFT) approach in order to evaluate the nucleon–WIMP elastic scattering cross section.

scholarly journals Exclusion Limits on a Scalar Decaying to Photons and Distinguishing Its Production Mechanisms

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Tanumoy Mandal
Keyword(s):  
Cross Sections ◽  
Effective Field Theory ◽  
Gluon Fusion ◽  
Effective Field ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
The Standard Model ◽  
Resonance Search ◽  
Model Independent ◽  
Production Mechanisms

LHC run-II has a great potential to search for new resonances in the diphoton channel. Latest 13 TeV data already put stringent limits on the cross sections in the diphoton channel assuming the resonance is produced through the gluon-gluon fusion. Many beyond the Standard Model (SM) theories predict TeV-scale scalars, which copiously decay to diphotons. Apart from the gluon-gluon fusion production, these scalars can also be dominantly produced in other ways too at the LHC, namely, through the quark-quark fusion or the gauge boson fusions like the photon-photon, photon-Z, WW, or ZZ fusions. In this paper we use an effective field theory approach where a heavy scalar can be produced in various ways and recast the latest ATLAS diphoton resonance search to put model-independent limits on its mass and effective couplings to the SM particles. If a new scalar is discovered at the LHC, it would be very important to identify its production mechanism in order to probe the nature of the underlying theory. We show that combining various kinematic variables in a multivariate analysis can be very powerful to distinguish different production mechanisms from one another.

scholarly journals Precision SMEFT bounds from the VBF Higgs at high transverse momentum

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Jack Y. Araz ◽  
Shankha Banerjee ◽  
Rick S. Gupta ◽  
Michael Spannowsky
Keyword(s):  
Standard Model ◽  
Vector Boson ◽  
High Energy ◽  
Effective Field ◽  
Higgs Bosons ◽  
Quadratic Growth ◽  
Final States ◽  
High Transverse Momentum ◽  
The Standard Model ◽  
Independent Operator

Abstract We study the production of Higgs bosons at high transverse momenta via vector-boson fusion (VBF) in the Standard Model Effective Field Theory (SMEFT). We find that contributions from four independent operator combinations dominate in this limit. These are the same ‘high energy primaries’ that control high energy diboson processes, including Higgs-strahlung. We perform detailed collider simulations for the diphoton decay mode of the Higgs boson as well as the three final states arising from the ditau channel. Using the quadratic growth of the SMEFT contributions relative to the Standard Model (SM) contribution, we project very stringent bounds on these operators that far surpass the corresponding bounds from the LEP experiment.

scholarly journals On the τ flavor of the cosmic neutrino flux

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Yasaman Farzan
Keyword(s):  
Dark Matter ◽  
Degrees Of Freedom ◽  
Neutrino Flux ◽  
High Energy ◽  
New Physics ◽  
Beyond The Standard Model ◽  
New Era ◽  
The Standard Model ◽  
Cosmic Neutrino ◽  
Standard Picture

Abstract Observation of high energy cosmic neutrinos by ICECUBE has ushered in a new era in exploring both cosmos and new physics beyond the Standard Model (SM). In the standard picture, although mostly νμ and νe are produced in the source, oscillation will produce ντen route. Certain beyond SM scenarios, like interaction with ultralight DM can alter this picture. Thus, the flavor composition of the cosmic neutrino flux can open up the possibility of exploring certain beyond the SM scenarios that are inaccessible otherwise. We show that the τ flavor holds a special place among the neutrino flavors in elucidating new physics. Interpreting the two anomalous events observed by ANITA as ντ events makes the tau flavor even more intriguing. We study how the detection of the two tau events by ICECUBE constrains the interaction of the neutrinos with ultralight dark matter and discuss the implications of this interaction for even higher energy cosmic neutrinos detectable by future radio telescopes such as ARA, ARIANNA and GRAND. We also revisit the 3 + 1 neutrino scheme as a solution to the two anomalous ANITA events and clarify a misconception that exists in the literature about the evolution of high energy neutrinos in matter within the 3 + 1 scheme with a possibility of scattering off nuclei. We show that the existing bounds on the flux of ντ with energy of EeV rules out this solution for the ANITA events. We show that the 3 + 1 solution can be saved from both this bound and from the bound on the extra relativistic degrees of freedom in the early universe by turning on the interaction of neutrinos with ultralight dark matter.

scholarly journals The emergence of electroweak Skyrmions through Higgs bosons

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Juan Carlos Criado ◽  
Valentin V. Khoze ◽  
Michael Spannowsky
Keyword(s):  
Production Cross ◽  
Finite Size ◽  
Higgs Field ◽  
Finite Energy ◽  
High Energy ◽  
Field Configuration ◽  
Effective Field ◽  
Dark Matter Candidate ◽  
Topological Solitons ◽  
Electroweak Sector

Abstract Skyrmions are extended field configurations, initially proposed to describe baryons as topological solitons in an effective field theory of mesons. We investigate and confirm the existence of skyrmions within the electroweak sector of the Standard Model and study their properties. We find that the interplay of the electroweak sector with a dynamical Higgs field and the Skyrme term leads to a non-trivial vacuum structure with the skyrmion and perturbative vacuum sectors separated by a finite energy barrier. We identify dimension-8 operators that stabilise the electroweak skyrmion as a spatially localised soliton field configuration with finite size. Such operators are induced generically by a wide class of UV models. To calculate the skyrmion energy and radius we use a neural network method. Electroweak skyrmions are non-topological solitons but are exponentially long lived, and we find that the electroweak skyrmion is a viable dark matter candidate. While the skyrmion production cross section at collider experiments is suppressed, measuring the size of the Skyrme term in multi-Higgs-production processes at high-energy colliders is a promising avenue to probe the existence of electroweak skyrmions.

scholarly journals Loops and trees in generic EFTs

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Nathaniel Craig ◽  
Minyuan Jiang ◽  
Ying-Ying Li ◽  
Dave Sutherland
Keyword(s):  
Standard Model ◽  
High Energy ◽  
Tree Level ◽  
Energy Limit ◽  
High Energy Limit ◽  
Functional Methods ◽  
Weakly Coupled ◽  
The Standard Model ◽  
Helicity Amplitudes ◽  
The Impact

Abstract We consider aspects of tree and one-loop behavior in a generic 4d EFT of massless scalars, fermions, and vectors, with a particular eye to the high-energy limit of the Standard Model EFT at operator dimensions 6 and 8. First, we classify the possible Lorentz structures of operators and the subset of these that can arise at tree-level in a weakly coupled UV completion, extending the tree/loop classification through dimension 8 using functional methods. Second, we investigate how operators contribute to tree and one-loop helicity amplitudes, exploring the impact of non-renormalization theorems through dimension 8. We further observe that many dimension 6 contributions to helicity amplitudes, including rational parts, vanish exactly at one-loop level. This suggests the impact of helicity selection rules extends beyond one loop in non-supersymmetric EFTs.

scholarly journals General non-leptonic ∆F = 1 WET at the NLO in QCD

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Jason Aebischer ◽  
Christoph Bobeth ◽  
Andrzej J. Buras ◽  
Jacky Kumar ◽  
Mikołaj Misiak
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
High Energy ◽  
Effective Field ◽  
Effective Theory ◽  
Leading Order ◽  
The Standard Model ◽  
Complete Set ◽  
The One

Abstract We reconsider the complete set of four-quark operators in the Weak Effective Theory (WET) for non-leptonic ∆F = 1 decays that govern s → d and b → d, s transitions in the Standard Model (SM) and beyond, at the Next-to-Leading Order (NLO) in QCD. We discuss cases with different numbers Nf of active flavours, intermediate threshold corrections, as well as the issue of transformations between operator bases beyond leading order to facilitate the matching to high-energy completions or the Standard Model Effective Field Theory (SMEFT) at the electroweak scale. As a first step towards a SMEFT NLO analysis of K → ππ and non-leptonic B-meson decays, we calculate the relevant WET Wilson coefficients including two-loop contributions to their renormalization group running, and express them in terms of the Wilson coefficients in a particular operator basis for which the one-loop matching to SMEFT is already known.

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