Electroweak Research Articles

Production of massive W±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^{\\pm }$$\\end{document} bosons and fermion–antifermion pairs from vacuum in the de Sitter Universe

In this paper we study the charged electro-weak interactions in the de Sitter geometry. We develop the reduction formalism for the Proca field with the help of the solutions for the interacting fields. Perturbation theory is used for obtaining the definition of the transition amplitudes in the first order. We apply our formalism to the study of spontaneous vacuum emission of fermions, anti-fermions and W±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^{\\pm }$$\\end{document} bosons in the expanding de Sitter universe. Our results are generalizations of the Weinberg–Salam electro-weak theory to curved space-time, in the case of W±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^{\\pm }$$\\end{document} boson interaction with leptons. The probability and transition amplitude are found to be a quantities which depend on the Hubble parameter. Our analytical and graphical results prove that such perturbative processes are possible only for the large expansion conditions of the early Universe. The total probability and rate of transition are obtained for the case of large expansion and we use dimensional regularization for the momenta integrals. In the end we recover the Minkowski limit, where our probabilities vanish, thus confirming the well known fact that spontaneous vacuum emission of W±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^{\\pm }$$\\end{document} bosons and fermions is forbidden in flat space-time due to energy–momentum conservation.

Addressing six standard model problems with Technically Natural Higgs models

We aim to study the potential of the recently proposed model framework, called Technically Natural Higgs (TNH), in addressing six fundamental problems in particle physics and cosmology. These questions encompass the electroweak (EW) naturalness problem, neutrino mass generation, nature of the inflaton, the matter-antimatter asymmetry problem, origin of dark matter (DM) and the strong CP problem. We investigate various solutions within the TNH framework for three inflation scenarios — Higgs, Starobinsky and scale-independent inflation. In the minimal TNH model, the Higgs is a mixture of an elementary and a composite state, with a compositeness scale far exceeding the EW scale. Traditionally, this has required an unnatural small vacuum misalignment, but in the TNH framework a novel mechanism enables a technically natural large compositeness scale, even up to the Planck scale. In this model framework, we demonstrate that a scale-invariant version of the minimal TNH model, featuring a special energy scale of around mathcal{O} (1012) GeV, loop-induced by the inflaton, simultaneously yields a technically natural 125-GeV Higgs boson, scotogenic neutrinos, a scale-invariant inflaton and a QCD axion DM candidate. These components dynamically generate the Planck scale and collectively have the potential to address all six open questions.

The St. Benedict Facility: Probing Fundamental Symmetries through Mixed Mirror β-Decays

Precise measurements of nuclear beta decays provide a unique insight into the Standard Model due to their connection to the electroweak interaction. These decays help constrain the unitarity or non-unitarity of the Cabibbo–Kobayashi–Maskawa (CKM) quark mixing matrix, and can uniquely probe the existence of exotic scalar or tensor currents. Of these decays, superallowed mixed mirror transitions have been the least well-studied, in part due to the absence of data on their Fermi to Gamow-Teller mixing ratios (ρ). At the Nuclear Science Laboratory (NSL) at the University of Notre Dame, the Superallowed Transition Beta-Neutrino Decay Ion Coincidence Trap (St. Benedict) is being constructed to determine the ρ for various mirror decays via a measurement of the beta–neutrino angular correlation parameter (aβν) to a relative precision of 0.5%. In this work, we present an overview of the St. Benedict facility and the impact it will have on various Beyond the Standard Model studies, including an expanded sensitivity study of ρ for various mirror nuclei accessible to the facility. A feasibility evaluation is also presented that indicates the measurement goals for many mirror nuclei, which are currently attainable in a week of radioactive beam delivery at the NSL.

Search for new physics in multijet events with at least one photon and large missing transverse momentum in proton-proton collisions at 13 TeV

A search for new physics in final states consisting of at least one photon, multiple jets, and large missing transverse momentum is presented, using proton-proton collision events at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 137 fb−1, recorded by the CMS experiment at the CERN LHC from 2016 to 2018. The events are divided into mutually exclusive bins characterized by the missing transverse momentum, the number of jets, the number of b-tagged jets, and jets consistent with the presence of hadronically decaying W, Z, or Higgs bosons. The observed data are found to be consistent with the prediction from standard model processes. The results are interpreted in the context of simplified models of pair production of supersymmetric particles via strong and electroweak interactions. Depending on the details of the signal models, gluinos and squarks of masses up to 2.35 and 1.43 TeV, respectively, and electroweakinos of masses up to 1.23 TeV are excluded at 95% confidence level.

Non-thermal Higgs spectrum in reheating epoch: primordial condensate vs. stochastic fluctuation

Since electroweak symmetry is generally broken during inflation, the Standard Model Higgs field can become supermassive even after the end of inflation.In this paper, we study the non-thermal phase space distribution of the Higgs field during reheating, focusing in particular on two different contributions: primordial condensate and stochastic fluctuations.We obtain their analytic formulae, which agree with the previous numerical result.As a possible consequence of the non-thermal Higgs spectrum, we discuss perturbative Higgs decay during reheating for the case it is kinematically allowed.We find that the soft-relativistic and hard spectra are dominant in the decay rate of the stochastic fluctuation and that the primordial condensate and stochastic fluctuations decay almost at the same time.

The Asymptotically Safe Standard Model: From quantum gravity to dynamical chiral symmetry breaking

We present a comprehensive non-perturbative study of the phase structure of the asymptotically safe Standard Model. The physics scales included range from the asymptotically safe trans-Planckian regime in the ultraviolet, the intermediate high-energy regime with electroweak symmetry breaking to strongly correlated QCD in the infrared. All flows are computed with a self-consistent functional renormalisation group approach, using a vertex expansion in the fluctuation fields. In particular, this approach takes care of all physical threshold effects and the respective decoupling of ultraviolet degrees of freedom. Standard Model and gravity couplings and masses are fixed by their experimental low energy values. Importantly, we accommodate for the difference between the top pole mass and its Euclidean analogue. Both, the correct mass determination and the threshold effects have a significant impact on the qualitative properties, and in particular on the stability properties of the specific ultraviolet-infrared trajectory with experimental Standard Model physics in the infrared. We show that in the present rather advanced approximation the matter part of the asymptotically safe Standard Model has the same number of relevant parameters as the Standard Model, and is asymptotically free. This result is based on the novel UV fixed point found in the present work: the fixed point Higgs potential is flat but has two relevant directions. These results and their analysis are accompanied by a thorough discussion of the systematic error of the present truncation, also important for systematic improvements.

Gravitational echoes of lepton number symmetry breaking with light and ultralight Majorons

We formulate a version of the low-scale Majoron model equipped with an inverse seesaw mechanism featuring lepton-number preserving dimension-6 operators in the scalar potential. Contrary to its dimension-4 counterpart, we find that the model can simultaneously provide light and ultralight Majorons, neutrino masses and their mixing, while featuring strong first-order cosmological phase transitions associated to the spontaneous breaking of the lepton number and the electroweak symmetries in the early Universe. We show by a detailed numerical analysis under which circumstances the model can be probed via the primordial gravitational wave spectrum potentially observable at LISA and other planned facilities. We discuss which implications result for collider physics observables, such as scalar trilinear couplings, the scalar mixing angle and the mass of a new CP-even Higgs boson.

Inflation and electroweak symmetry breaking

We present a model of Cosmological Electroweak Symmetry Breaking (CEWSB), where a Higgs-like field and a cosmological background of weak boson gauge fields interact with gravity to realize the epoch of cosmic inflation, which is then followed by a Higgs resonance preheating. As a result, the scale of electroweak symmetry breaking is linked with the end of inflation. The theory is equipped with a shift symmetry that can protect the Higgs mass, and it has close semblance to natural inflation and its variants. As the Higgs field's amplitude decays at the end of inflation, its mass emerges. The model has a built in Higgs self-resonance preheating mechanism which leads to the possible emergence of the cosmic microwave background (CMB) due to resonant Higgs, quark and lepton production after inflation. We provide a pathway to implement a similar mechanism with the realistic Higgs-doublet of the standard electroweak theory and discuss phenomenological considerations.

Time-symmetric quantization of relativistic fields. 2. Electroweak theory. Observable effects of TSQ

In the method of time-symmetric quantization (TSQ) of relativistic systems, based on the Stückelberg-Feynman interpretation, the creation-annihilation operators of quanta of complex fields and massless gauge fields, are automatically normally ordered, and there is no vacuum energy and charge (Z. Zakir 2023, article 1). In this second article the application of TSQ to massive bosonic fields of electroweak theory and the observational consequences of TSQ are considered. It is shown that the vacuum of these fields is free of zero-point energy and zero-point charge, and thus a contribution of these fields to the cosmological constant is absent. A direct observational consequence of TSQ is crossing symmetry in particle physics. The observable effects, which were attributed to the zero-point energy of the vacuum, are actually generated by the fields of real charges, and there is no evidence of the existence of zero-point energy of fundamental fields. This fact contradicts the prediction of the standard formulation of quantum field theory, but indirectly confirms TSQ.

γ-Ray and ultra-high energy neutrino background suppression due to solar radiation

The Sun emits copious amounts of photons and neutrinos in an approximately spatially isotropic distribution. Diffuse γ-rays and ultra-high energy (UHE) neutrinos from extragalactic sources may subsequently interact and annihilate with the emitted solar photons and neutrinos respectively. This will in turn induce an anisotropy in the cosmic ray (CR) background due to attenuation of the γ-ray and UHE neutrino flux by the solar radiation. Measuring this reduction, therefore, presents a simple and powerful astrophysical probe of electroweak interactions. In this letter we compute such anisotropies, which at the Earth (Sun) can be at least ≃5×10−3(1)% and ≃1×10−16(2×10−14)% for TeV scale γ-rays and PeV scale UHE neutrinos respectively. We briefly discuss observational prospects for experiments such as the Fermi Gamma-Ray Space Telescope Large Area Telescope (Fermi LAT), High-Altitude Water Cherenkov (HAWC) detector, The Large High Altitude Air Shower Observatory (LHAASO), Cherenkov Telescope Array (CTA) and IceCube. The potential for measuring γ-ray attenuation at orbital locations of other active satellites such as the Parker Solar Probe and James Webb Space Telescope (JWST) is also explored.

HOW MULTIPLE BRANCHES OF MATHEMATICS UNITE THE MOBIUS STRIP WITH MULTIPLE PHENOMENA IN PHYSICS AND COSMOLOGY

Question – How does the Riemann Hypothesis Support Topological Propulsion and Faster-than-light Travel? Answer – 
 
 a) Using the axiom that there indeed are infinitely many nontrivial zeros on the critical line (calculations have confirmed the hypothesis to be true to over 13 trillion places), the critical line is identified as the y-axis of Wick rotation. This suggests the y-axis is literally infinite and that infinity equals zero. In this case, it is zero distance in time and space. Travelling zero distance is done instantly and is therefore faster-than-light travel. 
 b) Wick rotation is essential to this article’s description of a topological (mathematical) universe and the Riemann hypothesis’ identification with Wick means the hypothesis doesn’t just apply to the distribution of prime numbers but also applies to the fundamental structure of the mathematical universe’s space-time. 
 
 An absolutely essential ingredient of time travel by applied maths is being able to journey into the remote past and future. For this reason, a paragraph about the coexistence of past, present, and future (without such coexistence, time travel could never be a possibility) is included in a section titled “Riemann Hypothesis and Wick Rotation Support Time Travel into the Past and Future”.
 This article provides insights into travelling at significant fractions of – as well as faster than - light, the Higgs boson and field, electroweak interaction, dark matter, dark energy, other dimensions, space-time (eg the expanding-universe question and time travel), quantum mechanics, quantum computers, the Riemann hypothesis, and Unidentified Flying Objects. 
 The article is also a brief summary discussing how the Matrix, the Riemann hypothesis, quaternions, Wick rotation, and imaginary numbers unite topology’s Mobius strip with known and unknown dimensions as well as the Higgs boson, Higgs field, dark matter, dark energy, antigravitons, and the static universe. The article also explains Unidentified Flying Objects as the result of future human technology.

A perturbative production of massive Z bosons and fermion–antifermion pairs from the vacuum in the de Sitter Universe

In this paper we study the problem of neutral electro-weak interactions in a de Sitter geometry. We develop the formalism of reduction for the Proca field with the help of the solutions for the interacting fields and by using perturbative methods we obtain the definition of the transition amplitudes in the first order of perturbation theory. As an application to our formalism we study the generation of massive fermions and Z bosons from vacuum in the expanding de Sitter universe. Our results are the generalization to the curved geometry of the Weinberg–Salam electro-weak theory for the case of Z boson interaction with leptons. The probability is found to be a quantity that depends on the Hubble parameter and we prove that such perturbative processes are possible only for large expansion regime of the early Universe. The total probability and rate of transition are obtained for the case of large expansion and we use the dimensional regularization for extract finite results from the momenta integrals. In the Minkowski limit we obtain that the probability of particle generation from vacuum is vanishing recovering the well known result that forbids particle production in flat space-time due to the momentum-energy conservation.

Physics implication from higher weak isospin decomposition

The SU(3)_Lotimes U(1)_X symmetry actually studied is directly broken to the electroweak symmetry SU(2)_Lotimes U(1)_Y by a Higgs triplet, predicting a relevant new physics at TeV scale. This work argues, by contrast, that the higher weak isospin SU(3)_L might be broken at a high energy scale, much beyond 1 TeV, by a Higgs octet to an intermediate symmetry SU(2)_Lotimes U(1)_{T_8} at TeV, before the latter U(1)_{T_8} recombined with U(1)_X defines (i.e., broken to) U(1)_Y by a Higgs singlet. The new physics coupled to SU(3)_L breaking phase is decoupled, whereas what remains is a novel family-nonuniversal abelian model, U(1)_{T_8}otimes U(1)_X, significantly overhauling the standard model as well as yielding consistent results for neutrino mass, dark matter, W-mass anomaly, and FCNC, differently from the usual 3-3-1 model.

Searches for Higgs boson pair-production in the bbττ channel with the ATLAS detector

Higgs Potential 2022 Proceeding. The Higgs boson (H) was discovered at the Large Hadron Collider (LHC) in 2012, by the ATLAS and CMS collaborations. Many of its properties have been measured. However, the ultimate test of electroweak symmetry breaking, the Higgs boson trilinear self-coupling remains unclear. This coupling is uniquely accessible in the Di-Higgs production. In this talk, the author presents the results of searches for Higgs boson pair production in the bb¯τ+τ− final state at ATLAS. The searches use 139 fb1− of pp collision data with s=13 TeV recorded by the ATLAS experiment at the LHC between 2015 and 2018. The semi-leptonic and fully hadronic di-tau final states are considered. Upper limits are set on the non-resonant di-Higgs production cross-section assuming Standard Model kinematics and on the resonant di-Higgs production cross-section as a function of the resonance mass.

Predictions of the ratio and asymmetry probes of the invisible Z-boson decay

Higher-order predictions through the combined accuracy including next-to-leading order (NLO) electroweak (EW) and next-to-NLO (NNLO) quantum chromodynamics (QCD) corrections in underlying perturbation theories are presented thoroughly for the invisible decay of the Z boson into neutrino pair relative to its decay into charged-lepton pair (leptonic decay). The combined NNLO QCD+NLO EW predictions are achieved based on the fully-differential calculations of cross sections of both the invisible and leptonic processes in proton-proton (pp) collisions at 13 TeV center-of-mass energy. Differential distributions of cross-section ratios of the invisible process to the leptonic process are presented as a function of the transverse momentum of the Z boson . For the first time, the predictions for differential distributions of cross-section asymmetries between the invisible process and the leptonic process are presented in bins of the . The cross-section ratio and asymmetry distributions, which are referred to as the invisible probes, are considered to be important for controlling the invisible process by the leptonic process of the Z boson and probing deviation from the Standard Model (SM) for new-physics searches. The predictions are extensively presented beyond the Z-boson mass resonance region to assess the potential of the invisible ratio and asymmetry probes for new-phenomena searches in high-invariant mass region of the lepton-pair final states. Various tests with threshold requirements of transverse momenta of neutrino pair and leptons are performed to assess the impact on the combined predictions. The invisible ratio and asymmetry probes are proposed to be important probes for indirect searches of new-physics scenarios.

Discriminating between Higgs Production Mechanisms via Jet Charge at the LHC.

Discriminating between Higgs production mechanisms can play a crucial role in determining the couplings of Higgs to gauge bosons, probing the nature of electroweak symmetry breaking. We propose a novel method to distinguish the Higgs production mechanisms at the LHC by utilizing the jet charge asymmetry of the two leading forward jets in Higgs plus two jets production. This novel observable provides a way to disentangle the W fusion from the Z fusion and gluon fusion processes for the first time, due to the electric charge correlation of the two leading jets in the events. We show that the Higgs couplings to gauge bosons can be well constrained, and its conclusion does not depend on the other possible new physics effects which modify the Higgs total or partial width. We also discuss the complementary roles between the proposed jet charge asymmetry measurement and the Higgs signal strength measurements at the high luminosity LHC (HL-LHC) in determining the Higgs couplings.

Multipole expansion for the electron-nucleus scattering at high energies in the unified electroweak theory

The paper presents the multipole expansion for the electron-nucleus scattering cross section at high energies within the framework of the unified electroweak theory. The electroweak currents of the nucleus are expanded into the simple components with definite angular momenta, called the multipole form factors. The multipole expansion of the cross section is a consequence of the above expansion. Besides the familiar electromagnetic form factors, there are also the vector and axial form factors, respectively, related to weak interactions. To determine multipole form factors, general formulas for the calculation of reduced matrix elements are established using the fractional parentage coefficient method and the multiparticle shell model. Calculation of them enables us to obtain more detailed information about the nuclear structure and elucidate the role played by the weak interaction in the high-energy reaction mechanisms.

Muon anomalous magnetic dipole moment in a low scale type I see-saw model

Recent experimental results on muon anomalous magnetic dipole moment have shown a 4.2σ tension with the SM prediction, which has blown a fresh wind into the elementary particle physics community. The problem is believed to be explained only by physics beyond the standard model. Current work considers the anomalous moment in a scenario of models with mirror symmetry and type I see-saw mechanism at low energy scale of electroweak interactions. After a brief introduction to the model, a detailed numerical analysis of muon anomalous phenomenology will be carefully performed. Analysis results show that the model is not successful in explaining the muon moment problem, however the contributions of channels involving neutral Higgs scalars, including both the light and heavy ones, might provide sizable corrections to the discrepancy.

Tensor gauge boson dark matter extension of the electroweak sector

The existence of dark matter is explained by a new, massive, neutral, non-symmetric, rank-2 tensor gauge boson (hbox {Z}_{{upmu upnu }}-boson). The hbox {Z}_{{upmu upnu }}-boson can be predicted by the tensor gauge boson extension of the Electro Weak (EW) theory, proposed by Savvidy (Phys Lett B 625:341, 2005). The non-symmetric rank-2 tensor hbox {Z}_{{upmu upnu }} can be decomposed into a symmetric (hbox {Z}_{{(upmu upnu )}}) and anti-symmetric (hbox {Z}_{{[upmu upnu ]}}) part. Based on the non-Lagrangian formulation for the free sector of the hbox {R}_{textrm{2}}-theory proposed recently by Criado et al. (Phys Rev D 102:125031, arXiv:2010.02224, 2020), our massive anti-symmetric tensor field hbox {Z}_{{[upmu upnu ]}} corresponds to the massive symmetric spinor field hbox {Z}_{{upalpha upbeta upgamma updelta }} in the (2,0) irrep. For the massive hbox {Z}_{{upalpha upbeta upgamma updelta }} with the hbox {Z}_{textrm{2}}-symmetric Higgs portal couplings to a Standard Model (SM) particle, we compute the self-annihilation cross-section of the hbox {Z}_{{upalpha upbeta upgamma updelta }} dark matter and calculate its relic abundance. We also study the SM-SM particle scattering due to the exchange of the massive-hbox {Z}_{{(upmu upnu )}} symmetric field at a high energy scale. This proposition may have far reaching applications in astrophysics and cosmology.

Electroweak input schemes and universal corrections in SMEFT

The choice of an electroweak (EW) input scheme is an important component of perturbative calculations in Standard Model Effective Field Theory (SMEFT). In this paper we perform a systematic study of three different EW input schemes in SMEFT, in particular those using the parameter sets {MW, MZ, GF}, {MW, MZ, α}, or {α, MZ, GF}. We discuss general features and calculate decay rates of Z and W bosons to leptons and Higgs decays to bottom quarks in these three schemes up to next-to-leading order (NLO) in dimension-six SMEFT. We explore the sensitivity to Wilson coefficients and perturbative convergence in the different schemes, and show that while the latter point is more involved than in the Standard Model, the dominant scheme-dependent NLO corrections are universal and can be taken into account by a simple set of substitutions on the leading-order results. Residual NLO corrections are then of similar size between the different input schemes, and performing calculations in multiple schemes can give a useful handle on theory uncertainties in SMEFT predictions and fits to data.