Search

The determination of the β intensity probability between the ground states of parent and daughter nuclei has traditionally been a difficult task with standard γ -spectroscopy approaches due to the lack of the associated γ emission. In the last years, the total absorption γ -ray spectroscopy technique has successfully proven its ability to deal with this problem by means of different procedures. This article discusses the potential of these methods, and a new approach for segmented total-absorption γ -ray spectrometers is also introduced. An overview of applications is presented based on past, present, and future β -decay experiments. [ABSTRACT FROM AUTHOR]

In this paper, we study spin effects in the neutrino gravitational scattering by a supermassive black hole with a magnetized accretion disk having a finite thickness. We exactly describe the propagation of ultrarelativistic neutrinos on null geodesics and solve the spin precession equation along each neutrino trajectory. The interaction of neutrinos with the magnetic field is due to the nonzero diagonal magnetic moment. Additionally, neutrinos interact with plasma of the accretion disk electroweakly within the Fermi approximation. These interactions are obtained to change the polarization of incoming neutrinos, which are left particles. The fluxes of scattered neutrinos, proportional to the survival probability of spin oscillations, are derived for various parameters of the system. In particular, we are focused on the matter influence on the outgoing neutrinos flux. The possibility to observe the predicted effects for astrophysical neutrinos is briefly discussed. [ABSTRACT FROM AUTHOR]

In the boundless landscape of scientific exploration, there exists a hidden, yet easily accessible, dimension that has often not only intrigued and puzzled researchers but also provided the key. This dimension is chirality, the property that describes the handedness of objects. The influence of chirality extends across diverse fields of study from the parity violation in electroweak interactions to the extremely large macroscopic systems such as galaxies. In this opinion piece, we will delve into the power of chirality in scientific exploration by examining some examples that, at different scales, demonstrate its role as a key to a better understanding of our world. Our goal is to incite researchers from all fields to seek, implement and utilize chirality in their research. Going this extra mile might be more rewarding than it seems at first glance, in particular with regard to the increasing demand for new functional materials in response to the contemporary scientific and technological challenges we are facing. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'. [ABSTRACT FROM AUTHOR]

Results for the full electroweak two-loop contributions of O N c 2 , where N c is the colour factor, to the Higgs-boson masses in the MSSM are obtained using a Feynman-diagrammatic approach including the full dependence on the external momentum. These corrections are expected to constitute the dominant part of the two-loop corrections that were still missing up to now. As a consequence of working at O N c 2 , the relevant two-loop self-energies decompose into products of one-loop integrals, giving rise to a transparent analytical structure of the self-energies. We compare different renormalisation schemes for tan (β) , the ratio of the vacuum expectation values of the two Higgs doublets, and demonstrate under which conditions different renormalisation schemes can be related to each other via a simple reparametrisation. We explicitly show that this is in general not possible for mixed renormalisation schemes due to the presence of evanescent terms. In our numerical analysis, the new corrections are compared with already known two-loop contributions and the experimental uncertainty of the mass of the observed Higgs boson. While smaller than the already known two-loop corrections, the new terms are typically larger in size than the experimental uncertainty. This underlines the relevance of the so-far unknown electroweak two-loop contributions. [ABSTRACT FROM AUTHOR]

The observation of the electroweak production of a W boson and a photon in association with two jets, using pp collision data at the Large Hadron Collider at a centre of mass energy of s = 13 TeV, is reported. The data were recorded by the ATLAS experiment from 2015 to 2018 and correspond to an integrated luminosity of 140 fb - 1 . This process is sensitive to the quartic gauge boson couplings via the vector boson scattering mechanism and provides a stringent test of the electroweak sector of the Standard Model. Events are selected if they contain one electron or muon, missing transverse momentum, at least one photon, and two jets. Multivariate techniques are used to distinguish the electroweak W γ j j process from irreducible background processes. The observed significance of the electroweak W γ j j process is well above six standard deviations, compared to an expected significance of 6.3 standard deviations. Fiducial and differential cross sections are measured in a fiducial phase space close to the detector acceptance, which are in reasonable agreement with leading order Standard Model predictions from MadGraph5+Pythia8 and Sherpa. The results are used to constrain new physics effects in the context of an effective field theory. [ABSTRACT FROM AUTHOR]

Perturbative calculations predict that the effective potential of the Standard Model should have a new minimum, well beyond the Planck scale, which is much deeper than the electroweak vacuum. So far, most authors have accepted the metastability scenario in a cosmological perspective which is needed to explain why the theory remains trapped in our electroweak vacuum but requires to control the properties of matter in the extreme conditions of the early universe. As an alternative, one can consider the completely different idea of a non-perturbative effective potential that, as at the beginning of the Standard Model, is restricted to the pure Φ 4 sector but is consistent with the indications of the now existing analytical and numerical studies, namely "triviality" and a description of SSB as weak first-order phase transition. In this approach, the electroweak vacuum is now the lowest energy state because, besides the state with mass m h = 125 GeV, defined by the quadratic shape of the potential at its minimum, there is a second much larger mass scale (M H) Theor ∼ 690 (30) GeV associated with the zero-point energy determining the potential depth. Despite its large mass, the heavier state would couple to longitudinal Ws with the same typical strength as the low-mass state at 125 GeV and thus represent a relatively narrow resonance mainly produced at LHC by gluon-gluon fusion. Therefore, it is interesting that, in the LHC data, one can find combined indications of a new resonance of mass (M H) comb ∼ 685 (10) GeV, with a statistical significance which is far from negligible. Since this non-negligible evidence could become an important new discovery with forthcoming data, we outline further refinements of the theoretical predictions, that could be obtained by implementing unitarity constraints, in the presence of fermion and gauge fields, with the type of coupled-channel calculations nowadays used in meson spectroscopy. [ABSTRACT FROM AUTHOR]

We consider all magnetic monopoles that could have settled in the Standard Model after descending from a generic microscopic theory. These monopoles have Standard Model quantum numbers, are stable, and we also require that their magnetic fluxes are consistent with the electroweak symmetry breaking. Scattering processes involving quarks, leptons and protons on these monopoles are studied using partial waves decomposition. These processes in the lowest partial wave are known to be unsuppressed by the monopole mass and are relevant for monopole catalysis of proton decay. We provide estimates for scattering cross-sections and investigate and confirm the applicability of the twisted sector approach to scattering processes on these Standard Model monopoles. We find that the SM monopole catalysis processes are universal and model-independent. [ABSTRACT FROM AUTHOR]

The electroweak (EW) phase transition in the early Universe might be supercooled due to the presence of the classical scale invariance involving Beyond the Standard Model (BSM) sectors and the supercooling could persist down till a later epoch around which the QCD chiral phase transition is supposed to take place. Since this supercooling period keeps masslessness for all the six SM quarks, it has simply been argued that the QCD phase transition is the first order, and so is the EW one. However, not only the QCD coupling but also the top Yukawa and the Higgs quartic couplings get strong at around the QCD scale due to the renormalization group running, hence this scenario is potentially subject to a rigorous nonperturbative analysis. In this work, we employ the ladder Schwinger-Dyson (LSD) analysis based on the Cornwall-Jackiw-Tomboulis formalism at the two-loop level in such a gauge-Higgs-Yukawa system. We show that the chiral broken QCD vacuum emerges with the nonperturbative top condensate and the lightness of all six quarks is guaranteed due to the accidental U(1) axial symmetry presented in the top-Higgs sector. We employ a quark-meson model-like description in the mean field approximation to address the impact on the EW phase transition arising due to the top quark condensation at the QCD phase transition epoch. In the model, the LSD results are encoded to constrain the model parameter space. We then observe the cosmological phase transition of the first-order type and discuss the induced gravitational wave (GW) productions. We find that in addition to the conventional GW signals sourced from an expected BSM at around or over the TeV scale, the dynamical topponium-Higgs system can yield another power spectrum sensitive to the BBO, LISA, and DECIGO, etc. [ABSTRACT FROM AUTHOR]

The lack of positive evidence for Weakly Interacting Massive Particles (WIMPs) as well as the lack of discovery of supersymmetric (SUSY) particles at the LHC may appeal to a non-supersymmetric solution for the Standard Model problem of the Higgs boson mass divergence, the origin of the electroweak energy scale and the physical nature of the cosmological dark matter in the approach of composite Higgs boson. If the Higgs boson consists of charged constituents, their binding can lead to stable particles with electroweak charges. Such particles can take part in sphaleron transitions in the early Universe, which balance their excess with baryon asymmetry. Constraints on exotic charged species leave only stable particles with charge − 2 n possible, which can bind with n nuclei of primordial helium in neutral dark atoms. The predicted ratio of densities of dark atoms and baryonic matter determines the condition for dark atoms to dominate in the cosmological dark matter. To satisfy this condition of the dark-atom nature of the observed dark matter, the mass of new stable − 2 n charged particles should be within reach of the LHC for their searches. We discuss the possibilities of dark-atom binding in multi-atom systems and present state-of-the-art quantum mechanical descriptions of dark-atom interactions with nuclei. Annual modulations in such interactions with nuclei of underground detectors can explain the positive results of DAMA/NaI and DAMA/LIBRA experiments and the negative results of the underground WIMP searches. [ABSTRACT FROM AUTHOR]

In this paper, we present the current situation of the determinations of the first-row CKM components and show the Cabibbo angle anomaly corresponding to a deficit in the first-row CKM unitarity condition at the 3σ level. In this contribution, we show two new physics interpretations: heavy vector-like quark models and a MeV scale sterile neutrino scenario. The super tau-charm facility will directly probe the other CKM unitarity conditions related to Vcd. [ABSTRACT FROM AUTHOR]

Weakly nonlocal (WNL) Quantum Field Theories (QFTs) may define a new class of UV-completions in particle physics and gravity, without introducing any new elementary particle. One problematic issue is how to realize spontaneous symmetry breaking without introducing an infinite tower of ghosts in the perturbative spectrum. In this article, a WNL extension of the Standard Model (SM) is proposed: the Fuzzy Standard Model (FSM). It is a smooth deformation of the SM based on covariant star-products of fields. This new formalism realizes electroweak symmetry breaking without ghosts at tree-level. We give evidence that the FSM exhibits Vainshtein screening, aka classicalization, in the deep-UV. This could solve the electroweak hierarchy problem if it occurs at the TeV-scale. [ABSTRACT FROM AUTHOR]

The concept of symmetry under various transformations of quantities describing basic natural phenomena is one of the fundamental principles in the mathematical formulation of physical laws. Starting with Noether's theorems, we highlight some well–known examples of global symmetries and symmetry breaking on the particle level, such as the separation of strong and electroweak interactions and the Higgs mechanism, which gives mass to leptons and quarks. The relation between symmetry energy and charge symmetry breaking at both the nuclear level (under the interchange of protons and neutrons) and the particle level (under the interchange of u and d quarks) forms the main subject of this work. We trace the concept of symmetry energy from its introduction in the simple semi-empirical mass formula and liquid drop models to the most sophisticated non-relativistic, relativistic, and ab initio models. Methods used to extract symmetry energy attributes, utilizing the most significant combined terrestrial and astrophysical data and theoretical predictions, are reviewed. This includes properties of finite nuclei, heavy-ion collisions, neutron stars, gravitational waves, and parity–violating electron scattering experiments such as CREX and PREX, for which selected examples are provided. Finally, future approaches to investigation of the symmetry energy and its properties are discussed. [ABSTRACT FROM AUTHOR]

The decays of the B meson into vector mesons, observed during the LHCb experiment, provide an ideal laboratory to investigate particle physics phenomena with quantum information theory methods. In this article, we focus on the decays yielding a pair of ϕ mesons to investigate the presence of entanglement in the spin correlations of the system and quantify the amount of Bell inequality violation it entails. Our results show that the present LHCb data allow access to entanglement and to the Bell inequality violation with a significance exceeding the 5 σ threshold in both the cases. This demonstrates that the strong and electroweak interactions responsible for the B meson decay act as a source of entanglement and the quantum mechanics nature of high-energy phenomena. Particular attention is paid to the assessment of loopholes: deficiencies in the experimental setup which could invalidate the results of the Bell test. [ABSTRACT FROM AUTHOR]

We develop the asymptotic analysis as ε→0 for the natural gradient flow of the self-dual U(1)-Higgs energies on Hermitian line bundles over closed manifolds (Mn,g) of dimension n≥3, showing that solutions converge in a measure-theoretic sense to codimension-two mean curvature flows—i.e., integral (n−2)-Brakke flows—generalizing results of (Pigati and Stern in Invent. Math. 223:1027–1095, 2021) from the stationary case. Given any integral (n−2)-cycle Γ0 in M, these results can be used together with the convergence theory developed in (Parise et al. in Convergence of the self-dual U(1)-Yang–Mills–Higgs energies to the (n−2)-area functional, 2021, arXiv:2103.14615) to produce nontrivial integral Brakke flows starting at Γ0 with additional structure, similar to those produced via Ilmanen's elliptic regularization. [ABSTRACT FROM AUTHOR]

The super tau-charm facility will provide excellent conditions to perform a high-precision investigation of the tau-lepton properties: very high statistics, controllable systematics and low backgrounds. An overview of the broad physics program that could be addressed at this facility is presented. [ABSTRACT FROM AUTHOR]

In this paper, the analytical solutions of the complex coupled Higgs field equation, which explains a system of conserved scalar nucleons that interact with neutral scalar mesons in particle physics, are extracted. The enhanced modified extended tanh expansion method (eMETEM) is successfully employed to solve the considered equation. Besides, the effect of problem parameters on a real scalar meson field and a complex scalar nucleon field is investigated, plotted and interpreted. Some effective results are obtained in the examination and are presented for the first time in this study. The obtained results can be applied to a wide range of nonlinear equations including ocean and shallow-water waves. 3D, 2D and contour graphical representations of the attained solutions are given using appropriate parameters. The method is efficient for gathering analytical solutions for various kinds of phenomena modeling by classical, fractional, or stochastic partial differential equations. [ABSTRACT FROM AUTHOR]

Let |$C$| be a smooth projective curve over |${{\mathbb{C}}}$|⁠. We link the periodicity of Hitchin's uniformizing Higgs bundle of |$C$| with the underlying arithmetic geometry of the curve. Some new relations are discovered. We also speculate on the whole class of periodic Higgs bundles. [ABSTRACT FROM AUTHOR]

We prove that a blowing-up formula for the intersection cohomology of the moduli space of rank 2 Higgs bundles over a curve with trivial determinant holds. As an application, we derive the Poincaré polynomial of the intersection cohomology of the moduli space under a technical assumption. [ABSTRACT FROM AUTHOR]

Measurement of electroweak production of single heavy vector bosons in -collisions at the LHC is an important test for new physics. The most interesting case is the so-called vector boson fusion process which involves trilinear gauge coupling constant. This paper summarizes experimental results on electroweak production cross sections of events with leptonic decays of - and -bosons plus two hadron jets. They are based on datasets accumulated by the ATLAS and CMS detectors at , and TeV during Run1 and Run2 of the LHC. [ABSTRACT FROM AUTHOR]

We find an explicit solution formula of the time dependent self-dual equations of Chern—Simons—Higgs model. The solution is expressed completely in terms of initial data. [ABSTRACT FROM AUTHOR]

This study introduces the generalized Khater Method (gKM) as a tool for investigating the existence and dynamics of soliton solutions within the realm of the Fractional Coupled Higgs System (FCHS) with conformable fractional derivatives. The methodology involves obtaining Nonlinear Ordinary Differential Equations (NODEs) from FCHS via a fractional complex transformation. The reduced NODEs are further used to uncover various families of soliton solutions, elucidating their intricate interrelationships and dynamics. Using some 3D graphics, we visually depict the behavior of some soliton solutions, including shock, lump-type shock, periodic, multiple periodic, rogue, and kink solitons. These findings contribute to a better understanding of the dynamics inherent in the FCHS and have potential applications in domains dealing with nonlinear fractional partial differential equations. Arguably, the study also highlights the importance of incorporating the conformable fractional derivative into the FCHS to provide it with more degrees of freedom, which allows for a deeper exploration of its behaviors and could have significant implications for particle physics, particularly for phenomena such as mass origin and electroweak violation of symmetry. [ABSTRACT FROM AUTHOR]

In this article, the Bernoulli sub-ODE and generalized Kudryashov methods have been successfully used to look for travelling wave solutions for the coupled non-linear evolution equations including the coupled Higgs equation and the Maccari system. The aforementioned approaches provide more new broad solutions than the previous ones now in use and are straightforward to apply. In both techniques, a travelling wave transformation is employed to convert non-linear partial differential equations into an ordinary differential equation. The solitary wave solutions are also generated from the travelling wave solutions when the parameters are considered as unique values. Several soliton solutions are generated for various parameter combinations. Numerous innovative solutions have been created by using Bernoulli sub-ODE and generalized Kudryashov approaches, including the periodic wave, kink wave, bell shape, anti-bell shape, M-shape, V-shape, W-shape, Z-shape, bright, dark and singular soliton solutions. To demonstrate how the Bernoulli sub-ODE and generalized Kudryashov approaches can be used to uncover the analytical solutions of the coupled Higgs equation and the Maccari system, replicate many figures in computer software Mathematica 13.2 along with several 3D, 2D, and contour plots. The similarities, contrasts, advantages and disadvantages of the two analytical techniques are examined. It has been demonstrated that the travelling wave solutions generated by these two analytical techniques, each using a different basis equation, have unique characteristics. The outcomes show that the methods used may reliably identify wide-spectral stable travelling wave solutions to non-linear evolution equations that appear in a variety of scientific, technical, and engineering disciplines. [ABSTRACT FROM AUTHOR]

In this study, we aim to see how much the actual measurement of the Z+photon and di-photon signal strength, μ γ γ and μ γ Z , could influence the allowed parameter space of the Inert Doublet Model (IDM), and to what extent such measurement can be aligned with the latest bound from XenonNT experiment on the spin-independent dark-matter-nucleon scattering cross-section. Also, by considering the new embedded scalars in the IDM (i.e., S, A and H ± ), a wide investigation of the one-loop radiative corrections to the trilinear Higgs coupling hhh has been made in the light of the previous measurements. [ABSTRACT FROM AUTHOR]

We consider computations of Wilson loop expectations to leading order at large β in the case where a non-abelian finite gauge field interacts with a Higgs boson. By identifying the main order contributions from minimal vortices, we can express the Wilson loop expectations via an explicit Poisson random variable. This paper treats multiple cases of interests, including the Higgs boson at low and high disorder, and finds efficient polymer expansion like computations for each of these regimes. [ABSTRACT FROM AUTHOR]

The theory of heavy ion double charge exchange (DCE) reactions proceeding by effective rank-2 isotensor interactions is presented. Virtual pion–nucleon charge exchange interactions are investigated as the source for induced isotensor interactions, giving rise to the Majorana DCE (MDCE) reaction mechanism. MDCE is of a generic character, proceeding through pairs of complementary ( π ± , π ∓ ) reactions in the projectile and target nucleus. The dynamics of the elementary processes is discussed, where the excitation of pion–nucleon resonances are of central importance. Investigations of initial and final state ion–ion interactions show that these effects are acting as vertex renormalizations. In closure approximation, well justified by the finite pion mass, the second-order transition matrix elements reduce to pion potentials and effective two-body isotensor DCE interactions, giving rise also to two-body correlations in either of the participating nuclei. Connections to neutrinoless Majorana double beta decay (MDBD) are elucidated at various levels of the dynamics, from the underlying fundamental electro-weak and QCD scales to the physical scales of nuclear MDBD and MDCE physics. It is pointed out that heavy ion MDCE reactions may also proceed by competing electro-weak charge exchange processes, leading to lepton MDCE by electrons, positrons, and neutrinos. [ABSTRACT FROM AUTHOR]

Previously, a class of regular and asymptotically flat gravitating scalar solitons (scalarons) has been constructed in the Einstein–Klein–Gordon (EKG) theory by adopting a phantom field with Higgs-like potential where the kinetic term has the wrong sign and the scalaron possesses the negative Arnowitt–Deser–Misner (ADM) mass as a consequence. In this paper, we demonstrate that the use of the phantom field can be avoided by inverting the Higgs-like potential in the EKG system when the kinetic term has a proper sign, such that the corresponding gravitating scalaron can possess the positive ADM mass. We systematically study the basic properties of the gravitating scalaron, such as the ADM mass, the energy conditions, the geodesics of test particles, etc. Moreover, we find that it can be smoothly connected to the counterpart hairy black hole solutions from our recent work in the small horizon limit. [ABSTRACT FROM AUTHOR]

In the Standard Model, ad hoc hypotheses assume the existence of three generations of point-like leptons and quarks, which possess a point-like structure and follow the Dirac equation involving four anti-commutative matrices. In this work, we consider the sedenion hypercomplex algebra as an extension of the Standard Model and show its close link to SU(5), which is the underlying symmetry group for the grand unification theory (GUT). We first consider the direct-product quaternion model and the eight-element octonion algebra model. We show that neither the associative quaternion model nor the non-associative octonion model could generate three fermion generations. Instead, we show that the sedenion model, which contains three octonion sub-algebras, leads naturally to precisely three fermion generations. Moreover, we demonstrate the use of basis sedenion operators to construct twenty-four 5 × 5 generalized lambda matrices representing SU(5) generators, in analogy to the use of octonion basis operators to generate Gell-Mann's eight 3 × 3 lambda-matrix generators for SU(3). Thus, we provide a link between the sedenion algebra and Georgi and Glashow's SU(5) GUT model that unifies the electroweak and strong interactions for the Standard Model's elementary particles, which obey SU(3) ⊗ SU(2) ⊗ U(1) symmetry. [ABSTRACT FROM AUTHOR]

Recently, formalism has been derived for studying electroweak transition amplitudes for three-body systems both in infinite and finite volumes. The formalism provides exact relations that the infinite-volume amplitudes must satisfy, as well as a relationship between physical amplitudes and finite-volume matrix elements, which can be constrained from lattice QCD calculations. This formalism poses additional challenges when compared with the analogous well-studied two-body equivalent one, including the necessary step of solving integral equations of singular functions. In this work, we provide some non-trivial analytical and numerical tests on the aforementioned formalism. In particular, we consider a case where the three-particle system can have three-body bound states as well as bound states in the two-body subsystem. For kinematics below the three-body threshold, we demonstrate that the scattering amplitudes satisfy unitarity. We also check that for these kinematics the finite-volume matrix elements are accurately described by the formalism for two-body systems up to exponentially suppressed corrections. Finally, we verify that in the case of the three-body bound state, the finite-volume matrix element is equal to the infinite-volume coupling of the bound state, up to exponentially suppressed errors. [ABSTRACT FROM AUTHOR]

We study the self-gravitating Higgs field of a scalar charge. We show that in the zeroth and first approximation in the smallness of the scalar charge, the gravitational field of the scalar charge is described by the Schwarzschild–de Sitter metric with a cosmological constant determined by the vacuum potential of the Higgs field. An equation for the perturbation of the vacuum potential is obtained and studied. Particular exact solutions of the field equation are given. It is shown that in the case of a naked singularity, solutions of the field equation have the character of microscopic oscillations with a Compton wavelength. Asymptotic limit cases of the behavior of solutions are studied and their comparative analysis is carried out in relation to the Fisher solution. The averaging of microscopic oscillations of the scalar field is carried out and it it shown that at they make a negative contribution to the macroscopic energy of the scalar field, reducing the observed value of the black hole mass. A computer simulation of a scalar field demonstrates various types of the behavior of solutions. [ABSTRACT FROM AUTHOR]

The International Linear Collider (ILC) will allow the precise study of e - e + → q q ¯ interactions at different center-of-mass energies from the Z -pole to 1 TeV. In this paper, we discuss the experimental prospects for measuring differential observables in e - e + → b b ¯ and e - e + → c c ¯ at the ILC baseline energies, 250 and 500 GeV. The study is based on full simulation and reconstruction of the International Large Detector (ILD) concept. Two gauge-Higgs unification models predicting new high-mass resonances beyond the Standard Model are discussed. These models predict sizable deviations of the forward–backward observables at the ILC running above the Z mass and with longitudinally polarized electron and positron beams. The ability of the ILC to probe these models via high-precision measurements of the forward–backward asymmetry is discussed. Alternative scenarios at other energies and beam polarization schemes are also discussed, extrapolating the estimated uncertainties from the two baseline scenarios. [ABSTRACT FROM AUTHOR]

We study washout processes in post-sphaleron baryogenesis, a mechanism where the matter–antimatter asymmetry is generated in the decay of exotic particles after the electroweak phase transition. In particular we focus, in a quite model independent way, on those scattering processes that have an amplitude proportional to the CP asymmetry. We find that when the scatterings involve only massless particles, the washouts are very severe for light decaying particles (with masses below a few hundred of GeV) and successful baryogenesis is only possible in a small portion of parameter space. Instead, if even a very light particle participates in these processes, the allowed region of parameter space opens considerably, although the final amount of baryon asymmetry may differ significantly from the expression which is typically used and neglects washouts. Furthermore, we analyze washouts from the non-thermal spectrum of energetic particles produced in cascade decays and indicate in which models they can be relevant. [ABSTRACT FROM AUTHOR]

The Moller experiment and the P2 experiment aim at measuring the weak mixing angle at low scales. The Moller experiment uses e - e - → e - e - -scattering, the P2 experiment uses e - N → e - N -scattering. In both cases, two-loop electroweak corrections have to be taken into account, and here in particular diagrams which give rise to large logarithms. In this paper we compute a set of two-loop electroweak Feynman integrals for point-like particles, which are obtained from a box integral by the insertion of a light fermion loop. By rationalising all occurring square roots we show that these Feynman integrals can be expressed in terms of multiple polylogarithms. We present the results in a form, which makes the large logarithms manifest. We provide highly efficient numerical evaluation routines for these integrals. [ABSTRACT FROM AUTHOR]

We construct a set of parton distribution functions (PDFs), based on the recent NNPDF4.0 PDF set, that also include a photon PDF. The photon PDF is constructed using the LuxQED formalism, while QED evolution accounting for O α , O α α s , and O α 2 corrections is implemented and benchmarked by means of the EKO code. We investigate the impact of QED effects on NNPDF4.0, and compare our results both to our previous NNPDF3.1QED PDF set and to other recent PDF sets that include the photon. We assess the impact of photon-initiated processes and electroweak corrections on a variety of representative LHC processes, and find that they can reach the 5% level in vector boson pair production at large invariant mass. [ABSTRACT FROM AUTHOR]

We investigate self-conjugate Dark Matter (DM) particles that primarily interact with Standard Model (SM) electroweak gauge bosons within an effective field theoretical framework. Our analysis focuses on effective contact interactions, invariant under the SM gauge group, between Majorana fermions, and real scalar DM, with SM neutral electroweak gauge bosons. We calculate the Wilson coefficients for interaction terms up to dimension-8 and establish constraints on the theory's parameters. These constraints are derived from the observed relic density, and indirect detection observations. We discuss the potential for DM–nucleon scattering in direct detection experiments. Additionally, we utilize low-energy Large Electron–Positron (LEP) data to assess sensitivity to the pair production of low-mass (≤ 8 0 GeV) DM particles. Furthermore, we highlight the potential of the proposed International Linear Collider (ILC) in probing effective operators through the pair production of DM particles with masses ≥ 5 0 GeV in association with mono-photons. [ABSTRACT FROM AUTHOR]

Despite the discovery of the Higgs boson, the Higgs sector of the standard model is still not fully established. In particular, the self-couplings of the Higgs boson, and its couplings with gauge bosons, are still to be fully determined. We consider electroweak corrections to the process H → ν e ν ̄ e ν μ ν ̄ μ . The corrections depend on the H H H and Z Z H H couplings. We investigate this dependence in κ -framework. We find that the width depends on H H H coupling significantly. The dependence on Z Z H H coupling is only marginal. We also discuss the dependence on Z Z W W coupling. [ABSTRACT FROM AUTHOR]

Is there more to Dirac's gamma matrices than meets the eye? It turns out that gamma zero can be factorized into a product of three operators. This revelation facilitates the expansion of Dirac's space-time algebra to Clifford algebra Cl (0 , 6). The resultant rich geometric structure can be leveraged to establish a combined framework of the standard model and gravity, wherein a gravi-weak interaction between the vierbein field and the extended weak gauge field is allowed. Inspired by the composite Higgs model, we examine the vierbein field as an effective description of the fermion–antifermion condensation. The compositeness of space-time manifests itself at an energy scale which is different from the Planck scale. We propose that all the regular classical Lagrangian terms are of quantum condensation origin, thus possibly addressing the cosmological constant problem provided that we exercise extreme caution in the renormalization procedure that entails multiplications of divergent integrals. The Clifford algebra approach also permits a weaker form of charge conjugation without particle–antiparticle interchange, which leads to a Majorana-type mass that conserves lepton number. Additionally, in the context of spontaneous breaking of two global U (1) symmetries, we explore a three-Higgs-doublet model which could explain the fermion mass hierarchies. [ABSTRACT FROM AUTHOR]

Axion-like particles (ALPs) can be naturally lighter than the electroweak scale. We consider an ALP that couples to the Standard Model Higgs to achieve the strong first-order electroweak phase transition. We discuss the two-field dynamics of the phase transition and the associated computation in detail and identify the viable parameter space. The ALP mass can be from the MeV to GeV scale. Baryon asymmetry can be explained by local baryogenesis without violating the current electron and atom electric dipole moment bound in most of the viable parameter space. The viable parameter space can be probed through Higgs exotic decay, rare kaon decay, the electron and atomic electric dipole moment, and the effective number of neutrinos in the cosmic microwave background in the future. The gravitational-wave signal is too weak to be detected. [ABSTRACT FROM AUTHOR]

Discrete symmetries play an important role in several extensions of the Standard Model (SM) of particle physics. For instance, in order to avoid flavor changing neutral currents, a discrete Z2 symmetry is imposed on the Two-Higgs-Doublet Model (2HDM). This can lead to the formation of domain walls (DW) as the Z2 symmetry gets spontaneously broken during electroweak symmetry breaking in the early universe and domain walls form between regions whose vacua are related by the discrete symmetry. Due to this simultaneous spontaneous breaking of both the discrete symmetry and the electroweak symmetry, the vacuum manifold consists of two disconnected 3-spheres. Such a non-trivial disconnected vacuum manifold leads to several choices for the vacua at two adjacent regions, in contrast to models where only the discrete symmetry gets spontaneously broken and the vacuum manifold consists of several disconnected points. Due to this, we end up with several classes of DW solutions having different properties localized inside the wall, such as electric charge and/or CP violating vacua. We discuss the properties of these different classes of DW solutions as well as the interaction of SM fermions with such topological defects leading to different exotic phenomena such as, for example, the top quark being transmitted or reflected off the wall as a bottom quark. [ABSTRACT FROM AUTHOR]

Future colliders aim to provide highly precise experimental measurements of the properties of the Higgs boson. In order to benefit from these precision machines, theoretical errors in the Higgs sector observables have to match at least the experimental uncertainties. The theoretical uncertainties in the Higgs sector observables can be reduced by including missing higher-order terms in their perturbative calculations. In this direction, we compute the mixed QCD-electroweak corrections at to the Higgs decay into four charged leptons by considering the golden decay channel, H → e+e−μ+μ−. Due to color conservation, these corrections receive contributions only from the two-loop virtual diagrams. In the complex mass scheme, we find that the mixed QCD-electroweak corrections to the partial decay width, relative to the leading order predictions, are positive and about 0.27% for αs(MZ). Relative to the next-to-leading order electroweak corrections, the mixed QCD-electroweak corrections are found to be approximately 18% for αs(MZ). With respect to the leading order, we observe a flat effect of the mixed QCD-electroweak corrections on the invariant mass distribution of the lepton pairs with fixed QCD coupling. The ϕ distribution, due to the mixed QCD-electroweak corrections, follows a (1 − cos ϕ) dependence. [ABSTRACT FROM AUTHOR]

This paper presents the measurement of fiducial and differential cross sections for both the inclusive and electroweak production of a same-sign W-boson pair in association with two jets (W±W±jj) using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of s = 13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed by selecting two same-charge leptons, electron or muon, and at least two jets with large invariant mass and a large rapidity difference. The measured fiducial cross sections for electroweak and inclusive W±W±jj production are 2.92 ± 0.22 (stat.) ± 0.19 (syst.) fb and 3.38 ± 0.22 (stat.) ± 0.19 (syst.) fb, respectively, in agreement with Standard Model predictions. The measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confidence level intervals on dimension-8 operators. A search for doubly charged Higgs bosons H±± that are produced in vector-boson fusion processes and decay into a same-sign W boson pair is performed. The largest deviation from the Standard Model occurs for an H±± mass near 450 GeV, with a global significance of 2.5 standard deviations. [ABSTRACT FROM AUTHOR]

The Higgs boson pair production at the LHC provides a probe to the Higgs boson self-coupling. The higher-order QCD corrections in this process are sizable and must be taken into account in comparison with data. Due to the small cross section, it is necessary to consider at least one of the Higgs bosons decaying to bottom quarks. The QCD corrections to the decay processes would also be important in such cases. We present a full calculation of the total and differential cross sections for the b b ¯ γγ final state with next-to-leading order (NLO) QCD corrections. After applying typical kinematic cuts in the final state, we find that QCD NLO corrections in the decay decrease the LO result by 19% and reduce the scale uncertainties by a factor of two. The QCD corrections to the invariant mass mjjγγ distribution, the transverse momentum spectra of the leading bottom quark jet and photon are significant and can not be approximated by a constant factor. [ABSTRACT FROM AUTHOR]

Measurements of vector boson polarisation in vector boson production processes offer a powerful probe of the electroweak symmetry breaking mechanism, scrutinising the Standard Model and new physics scenarios alike. Since massive vector bosons can only be observed as intermediate particles, polarised cross section templates from simulation are necessary to extract their polarisation from measurable unpolarised distributions. In this work we present an extension of the Sherpa Monte-Carlo event generator allowing the simulation of polarised cross sections for vector boson production processes. Based on the narrow-width approximation, polarised cross sections of all possible polarisation combinations for an arbitrary number of intermediate vector bosons can be simulated in a single simulation run. In addition, it is possible to directly predict the interference between different intermediate polarisation states, and various differing polarisation definitions can be studied simultaneously. Besides the simulation of polarised cross sections at fixed LO and LO+PS accuracy as well as in multijet-merged calculations, we also present parton-shower-matched polarised cross sections with approximate NLO QCD corrections in the vector boson production processes. We demonstrate that the differences of this approximation to full NLO QCD predictions are small and it thus opens up the possibility for fully-simulated calculations at the hadron level including polarisation information and higher-order QCD effects for the first time. [ABSTRACT FROM AUTHOR]

We demonstrate the construction of Poisson structures via Lie algebroids on moduli spaces of twisted stable Higgs bundles over stacky curves. The construction provides new examples of Poisson structures on such moduli spaces. Special attention is paid to moduli spaces of parabolic Higgs bundles over a root stack. [ABSTRACT FROM AUTHOR]

Experimental information on the trilinear Higgs boson self-coupling κ 3 and the quartic self-coupling κ 4 will be crucial for gaining insight into the shape of the Higgs potential and the nature of the electroweak phase transition. While Higgs pair production processes provide access to κ 3 , triple Higgs production processes, despite their small cross sections, will provide valuable complementary information on κ 3 and first experimental constraints on κ 4 . We investigate triple Higgs boson production at the HL-LHC, employing efficient Graph Neural Network methodologies to maximise the statistical yield. We show that it will be possible to establish bounds on the variation of both couplings from the HL-LHC analyses that significantly go beyond the constraints from perturbative unitarity. We also discuss the prospects for the analysis of triple Higgs production at future high-energy lepton colliders operating at the TeV scale. [ABSTRACT FROM AUTHOR]

The production of a W-boson with a charm quark jet provides a highly sensitive probe of the strange quark distribution in the proton. Employing a novel flavour dressing procedure to define charm quark jets, we compute W+charm-jet production up to next-to-next-to-leading order (NNLO) in QCD. We study the perturbative stability of production cross sections with same-sign and opposite-sign charge combinations for the W boson and the charm jet. A detailed breakdown according to different partonic initial states allows us to identify particularly suitable observables for the study of the quark parton distributions of different flavours. [ABSTRACT FROM AUTHOR]

We review the theory and phenomenology of isosinglet vector-like quarks (VLQs). In recent years, interest in VLQs has been increasing, due to their contributions to new physics effects that can be tested in experiments at LHC and High-Luminosity LHC. The similarities of models with isosinglet VLQs and the seesaw framework in the leptonic sector are pointed out. The existence of VLQs leads to flavour-changing neutral currents at tree level and deviations from unitarity of the CKM matrix, introducing rich phenomenological implications. These new effects are naturally suppressed by the masses of the new quarks, that are constrained to be above the electroweak scale. In addition, striking new effects can be achieved with the inclusion of an extra complex scalar singlet. Such a minimal extension of the SM can give rise to new sources of CP violation with profound theoretical implications, allowing for a solution to the strong CP problem and a possible explanation for the baryon asymmetry of the Universe. We list and explain strong motivations to consider this class of models. We also briefly review how models with VLQs can be matched to the SM effective field theory (SMEFT). A detailed analysis of flavour observables that can be affected by the presence of VLQs is presented. Current bounds from collider searches of VLQs are summarized. We point out that the discovery of VLQs can be within the reach of present or future colliders being planned. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue of the journal "Universe" focused on top quark physics. The editors chose to emphasize recent results from the Large Hadron Collider (LHC) and discuss future prospects in the field, including the relation to cosmology. The top quark is an elementary particle with a high mass and unique properties. It is predominantly produced through QCD interactions at hadron colliders, but can also be produced through electroweak interactions. The study of the top quark allows for tests of quantum theory at high energy scales. The special issue covers various topics related to top quark physics, including tests of charge-parity symmetry, lepton-flavor conservation, and Lorentz-invariance violation. The analysis of data from the LHC has not yet provided any indication of new particles or interactions. The focus has shifted to quantifying the effects of hypothetical particles using the effective field theory approach. The issue also discusses the prospects for top quark measurements and new physics searches at future colliders. The editors emphasize the need for precision measurements and open discussion in the field. [Extracted from the article]

The Standard Model of electroweak interactions is based on the fundamental SU(2)weak × U(1)elect representation. It assumes massless neutrinos and purely left-handed massive W ± and Z0 bosons to which one should add the massless photon. The existence, verified experimentally, of neutrino oscillations poses a challenge to this scheme, since the oscillations take place between at least three massive neutrinos belonging to a mass hierarchy still to be determined. One should also take into account the possible existence of sterile neutrino species. In a somehow different context, the fundamental nature of the strong interaction component of the forces in nature is described by the, until now, extremely successful representation based on the SU(3)strong group which, together with the confining rule, give a description of massive hadrons in terms of quarks and gluons. To this is added the minimal U(1) Higgs group to give mass to the otherwise massless generators. This representation may also be challenged by the existence of both dark matter and dark energy, of still unknown composition. In this note, we shall discuss a possible connection between these questions, namely the need to extend the SU(3)strong × SU(2)weak × U(1)elect to account for massive neutrinos and dark matter. The main point of it is related to the role of axions, as postulated by Roberto Peccei and Helen Quinn. The existence of neutral pseudo-scalar bosons, that is, the axions, has been proposed long ago by Peccei and Quinn to explain the suppression of the electric dipole moment of the neutron. The associated U(1)PQ symmetry breaks at very high energy, and it guarantees that the interaction of other particles with axions is very weak. We shall review the axion properties in connection with the apparently different contexts of neutrino and dark matter physics. [ABSTRACT FROM AUTHOR]

SMEFT Wilson coefficients are subject to various positivity bounds in order to be consistent with the fundamental principles of S-matrix. Previous bounds on dimension-8 SMEFT operators have been obtained using the positivity part of UV partial wave unitarity and form a (projective) convex cone. We derive a set of linear UV unitarity conditions that go beyond positivity and are easy to implement in an optimization scheme with dispersion relations in a multi-field EFT. Using Higgs scattering as an example, we demonstrate how to obtain closed bounds in the space of the three relevant dimension-8 coefficients, making use of the UV unitarity conditions as well as so-called null constraints that arise from full crossing symmetry. Specifically, we show that they are bounded by inequalities schematically going like C < O ((4π)2). We compare the newly obtained upper bounds with the traditional perturbative unitarity bounds from within the EFT, and discuss some phenomenological implications of the two-sided positivity bounds in the context of experimental probes of Vector Boson Scattering. [ABSTRACT FROM AUTHOR]