Test of CP invariance in vector-boson fusion production of the Higgs boson using the Optimal Observable method in the ditau decay channel with the ATLAS detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Results for “CP INVARIANCE”
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Baryogenesis in a CP invariant theory
We consider baryogenesis in a model which has a CP invariant Lagrangian, CP invariant initial conditions and does not spontaneously break CP at any of the minima. We utilize the fact that tunneling processes between CP invariant minima can break CP to implement baryogenesis. CP invariance requires the presence of two tunneling processes with opposite CP breaking phases and equal probability of occurring. In order for the entire visible universe to see the same CP violating phase, we consider a model where the field doing the tunneling is the inflaton.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Test of CP invariance in vector-boson fusion production of the Higgs boson in the H -> tau tau channel in proton-proton collisions at root s=13TeV with the ATLAS detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Time reversal and CP invariance in Calabi-Yau compactifications
We revisit the question of time reversal and CP invariance in Calabi-Yau compactifications. We show that time reversal invariance is respected by quantum corrections to the prepotential. In particular, field independent θ angles whose presence is dictated by requiring integrality of relevant monodromy transformations can take precisely the quantized values compatible with time reversal invariance. Furthermore, monodromy symmetry enlarges the region on moduli space on which time reversal is not spontaneously broken. We define the action of the CP transformation for multi-parameter models and argue that on the slice of moduli space where it is defined, CP> is trivially a symmetry of the theory. For supersymmetric vacua that lie in this slice, we derive a condition on the third cohomology of the compactification manifold which determines whether CPpreserving fluxes exist that stabilize the moduli to such points. In the case of one-parameter models, the condition is always satisfied.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Test of CP-invariance of the Higgs boson in vector-boson fusion production and in its decay into four leptons
A search for CP violation in the decay kinematics and vector-boson fusion production of the Higgs boson is performed in the H → ZZ * → 4 ℓ ( ℓ = e, μ ) decay channel. The results are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, corresponding to an integrated luminosity of 139 fb –1 . Matrix element-based optimal observables are used to constrain CP-odd couplings beyond the Standard Model in the framework of Standard Model effective field theory expressed in the Warsaw and Higgs bases. Differential fiducial cross-section measurements of the optimal observables are also performed, and a new fiducial cross-section measurement for vector-boson-fusion production is provided. All measurements are in agreement with the Standard Model prediction of a CP-even Higgs boson.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Test of CP invariance in vector-boson fusion production of the Higgs boson in the H → ττ channel in proton–proton collisions at s=13TeV with the ATLAS detector
Explore the source record for details and available documents.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
The Lightest Neutralino Annihilation in NMSSM with CP Violation
We discuss the violation of CP invariance in the Higgs sector and its impact on the physical characteristics of the neutralino, and its implication in the processes of annihilation. The process of pair annihilation of the lightest neutralinos into two photons for NMSSM in the one-loop approximation considering the violation of CP-invariance in the extended scalar Higgs sector is calculated. The analysis of the obtained results and the comparison are given.
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Collaborative Research: Experimental and Theoretical Study of the Plasma Physics of Antihydrogen Generation and Trapping (Final Technical Report)
The charge-parity-time (CPT) invariance principle and the weak equivalence principle (WEP) undergird our current understanding of Nature. CPT, which is based on only Lorentz invariance, locality, and spin-statistics, is basic to local relativistic quantum field theory (QFT) models of physical laws. Testing established principles like these is a long-standing and honorable tradition in physics. Beginning with Newton’s Laws, many firmly established laws have been superseded, often to the great surprise of contemporaneous physicists. Certainly, CPT rests on firmer grounds than the earlier widely believed, but erroneous principles, of parity (P) and charge-parity (CP) invariance, but this does not necessarily make CPT inviolable. Tests of CPT confront the entire framework of QFT, and are quite distinct from most other “beyond the Standard Model” searches, which look for new physics within the QFT framework. With the failure, so far, to find new physics at the LHC or in dark matter searches, the motivation to test QFT itself is urgent. The revolutionary consequences of CPT and WEP violation would be so great that these principles are under intense scrutiny in many different systems. Here we focus on tests of CPT and WEP that employ antimatter, specifically antihydrogen. Such tests are difficult to realize experimentally, but constitute some of the simplest and most profound matter-antimatter comparisons that can be performed. Antimatter particles have been investigated since the prediction and subsequent discovery of the positron in the 1930s. That early discovery motivated the search for the antiproton, culminating in its creation and detection in Berkeley two decades later. As far as we know today, particles and their antiparticles share identical properties except for the sign of their charge. Antihydrogen is the simplest antimatter system—it is the antiparticle of the simplest atom, hydrogen. Differences between the spectra of the two are forbidden by CPT. The weak equivalence principle (WEP), demands that matter and antimatter accelerate identically in a gravitational field. WEP has never been subjected to a direct, free fall test using antimatter. Because of the weakness of the gravita tional force, direct antimatter WEP tests must employ a neutral particle, of which antihydrogen is the simplest to obtain. There are reasons to suspect that something is amiss with our understanding of antimatter. All generally accepted theories of the Big Bang predict that roughly equal amounts of matter and antimatter should have been created. Instead, very little antimatter has been observed in the Universe. This baryogenesis problem is arguably the most fundamental issue with the theory of the Big Bang. Its resolution may come from the discovery of enhanced CP violation, but could also come from CPT or WEP violation.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
The minimal fermionic model of electroweak baryogenesis
We present the minimal model of electroweak baryogenesis induced by fermions. The model consists of an extension of the Standard Model with one electroweak singlet fermion and one pair of vector like doublet fermions with renormalizable couplings to the Higgs. A strong first order phase transition is radiatively induced by the singlet-doublet fermions, while the origin of the baryon asymmetry is due to asymmetric reflection of the same set of fermions on the expanding electroweak bubble wall. The singlet-doublet fermions are stabilized at the electroweak scale by chiral symmetries and the Higgs potential is stabilized by threshold corrections coming from a multi-TeV ultraviolet completion which does not play any significant role in the phase transition. We work in terms of background symmetry invariants and perform an analytic semiclassical calculation of the baryon asymmetry, showing that the model may effectively generate the observed baryon asymmetry for percent level values of the unique invariant CP violating phase of the singlet-doublet sector. We include a detailed study of electron electric dipole moment and electroweak precision limits, and for one typical benchmark scenario, we also recast existing collider constraints, showing that the model is consistent with all current experimental data. We point out that fermion induced electroweak baryogenesis has irreducible phenomenology at the 13 TeV LHC since the new fermions must be at the electroweak scale, have electroweak quantum numbers and couple strongly to the Higgs. The most promising searches involve topologies with multiple leptons and missing energy in the final state.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
CP symmetry and thermal effects on Dirac bi-spinor spin–parity local correlations
Intrinsic quantum correlations supported by the SU(2)ⓍSU(2) structure of the Dirac equation used to describe particle/antiparticle states, optical ion traps and bilayer graphene are investigated and connected to the description of local properties of Dirac bi-spinors. For quantum states driven by Dirac-like Hamiltonians, quantum entanglement and geometric discord between spin and parity degrees of freedom – sometimes mapped into equivalent low energy internal degrees of freedom – are obtained. Such spin–parity quantum correlations and the corresponding nonlocal intrinsic structures of bi-spinor fermionic states can be classified in order to relate quantum observables to the (non)local behavior of these correlations. It is shown that free particle mixed states do not violate the Clauser–Horne–Shimony–Holt inequality: the correlations in such mixed bi-spinors, although quantum, can be reproduced by a suitable local hidden variable model. Additionally, the effects due to a non-minimal coupling to a homogeneous magnetic field, and to the inclusion of thermal effects are evaluated, and quantum correlations of associated quantum mixtures and of the thermal states are all quantified. The above-mentioned correlation quantifiers are then used to measure the influence of CP transformations on spin–parity quantum correlations, and our results show that quantum entanglement is invariant under CP transformations, although the geometric discord is highly sensitive to the CP symmetry.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Asymmetric dark matter and CP violating scatterings in a UV complete model
We explore possible asymmetric dark matter models using CP violating scatterings to generate an asymmetry. In particular, we introduce a new model, based on DM fields coupling to the SM Higgs and lepton doublets, a neutrino portal, and explore its UV completions. We study the CP violation and asymmetry formation of this model, to demonstrate that it is capable of producing the correct abundance of dark matter and the observed matter-antimatter asymmetry. Crucial to achieving this is the introduction of interactions which violate CP with a T{sup 2} dependence.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Electroweak baryogenesis in the exceptional supersymmetric standard model
We study electroweak baryogenesis in the E{sub 6} inspired exceptional supersymmetric standard model (E{sub 6}SSM). The relaxation coefficients driven by singlinos and the new gaugino as well as the transport equation of the Higgs supermultiplet number density in the E{sub 6}SSM are calculated. Our numerical simulation shows that both CP-violating source terms from singlinos and the new gaugino can solely give rise to a correct baryon asymmetry of the Universe via the electroweak baryogenesis mechanism.
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Baryon mass splittings and strong CP violation in SU(3) chiral perturbation theory
We study SU(3) flavor breaking corrections to the relation between the octet baryon masses and the nucleon-meson CP-violating interactions induced by the QCD theta term. We also work within the framework of SU(3) chiral perturbation theory and work through next-to-next-to-leading order in the SU(3) chiral expansion, which is O(m 2 q ). At lowest order, the CP-odd couplings induced by the QCD θ - term are determined by mass splittings of the baryon octet, the classic result of Crewther et al. We show that for each isospin-invariant CP-violating nucleon-meson interaction there exists one relation which is respected by loop corrections up to the order we work, while other leading-order relations are violated. With these relations we extract a precise value of the pion-nucleon coupling g - 0 by using recent lattice QCD evaluations of the proton-neutron mass splitting. Additionally, we derive semi-precise values for CP-violating coupling constants between heavier mesons and nucleons and discuss their phenomenological impact on electric dipole moments of nucleons and nuclei.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Casimir effect at finite temperature for pure-photon sector of the minimal Standard Model Extension
Dynamics between particles is governed by Lorentz and CPT symmetry. There is a violation of Parity (P) and CP symmetry at low levels. The unified theory, that includes particle physics and quantum gravity, may be expected to be covariant with Lorentz and CPT symmetry. At high enough energies, will the unified theory display violation of any symmetry? The Standard Model Extension (SME), with Lorentz and CPT violating terms, has been suggested to include particle dynamics. The minimal SME in the pure photon sector is considered in order to calculate the Casimir effect at finite temperature.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Neutrino cross-sections: Experiments
Neutrino-nucleus cross-sections are as of today the main source of systematic errors for oscillation experiments together with neutrino flux uncertainties. Despite recent experimental and theoretical developments, future experiments require even higher precisions in their search of CP violation. We will review the experimental status and explore possible future developments required by next generation of experiments.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Future reactor experiments
The non-zero neutrino mixing angle θ{sub 13} has been discovered and precisely measured by the current generation short-baseline reactor neutrino experiments. It opens the gate of measuring the leptonic CP-violating phase and enables the neutrino mass ordering. The JUNO and RENO-50 proposals aim at resolving the neutrino mass ordering using reactors. The experiment design, physics sensitivity, technical challenges as well as the progresses of those two proposed experiments are reviewed in this paper.
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The NOνA experiment, the first 12 months of commissioning, operations and physics data
The NOνA experiment is a long baseline neutrino experiment designed to make precision measurements of the oscillation probabilities for ν{sub µ} → ν{sub e} and ν{sub µ} → ν{sub µ} for both neutrinos and anti-neutrinos. These measurements will provide new information on the neutrino mass hierarchy, improve our knowledge of whether θ{sub 23} is non-maximal and possibility provide information on the CP violating phase δ{sub CP} of the PMNS neutrino mixing matrix. We present the observations of the first neutrino event in the NOνA far and near detectors along with data obtained during the first year of detector commissioning and operations. We use the data to demonstrate the detector’s ability to identify electron and muon neutrino events and to reject cosmic ray induced backgrounds at a level of 4 × 10{sup 7}:1. New estimates for the signal and background sensitivities of the NOνA experiment during the first year of full detector running are presented.
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Neutrinos and flavor symmetries
We discuss the recent progress of flavor models with the non-Abelian discrete symmetry in the lepton sector focusing on the θ{sub 13} and CP violating phase. In both direct approach and indirect approach of the flavor symmetry, the non-vanishing θ{sub 13} is predictable. The flavor symmetry with the generalised CP symmetry can also predicts the CP violating phase. We show the phenomenological analyses of neutrino mixing for the typical flavor models.
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