The Two Higgs Doublet Model (2HDM) stands as a promising framework for exploring physics beyond the Standard Model (SM). Within this context, we explore the possibility that the two Higgs doublets may serve as a window into CP-violating dark sectors, neutral under the SM gauge groups. Specifically, our focus is on investigating the electric dipole moment (EDM) of the electron, generated solely by CP violation in the dark sector. We present a general formula for the electron EDM, without specifying the structure of the dark sectors, and discuss the current constraints on various dark sector models. It is noteworthy that even in the case of a CP-conserving 2HDM, the resulting electron EDM is capable of reaching the current experimental limit, with CP violation arising exclusively from the dark sectors. Furthermore, we introduce a heavy dark sector (HDS) approximation for the analytic calculation of the EDM, assuming that the dark sector particles are much heavier than the physical states in the 2HDM. This approximation yields simplified analytic results that are consistent with the full numerical calculations.
We perform realistic simulations of the current and future long baseline experiments such as T2K, NO$ν$A, DUNE and T2HK in order to determine their ultimate potential in probing neutrino oscillation parameters. We quantify the potential of these experiments to underpin the octant of the atmospheric angle $θ_{23}$ as well as the value and sign of the CP phase $δ_{CP}$.
We discuss how a possible violation of the combined symmetry CPT in the B meson system can be investigated at the LHC. We show how a tagged and an untagged analysis of the decay modes of both B(d) and B(s) mesons can lead not only to a possible detection of a CPT-violating new physics but also to an understanding of its precise nature. The implication of CPT violation to a large mixing phase in the B(s) system is also discussed.
We revisit the topic of triple-product asymmetries which probe CP violation through differential distributions. We construct distributions with well-defined discrete symmetry properties and characterize the asymmetries formed upon them. It is stressed that the simplest asymmetries may not be optimal. We explore systematic generalizations having limited reliance on the process dynamics and phase-space parametrization. They exploit larger fractions of the information contained in differential distributions and may lead to increased sensitivities to CP violation. Our detailed treatment of the cas…
We consider the time-dependent analysis of rare $B_d$ and $B_s$ decays mediated by $b\to s ν\bar ν$ transitions. The inclusion of time evolution allows us to construct novel observables with specific sensitivity to CP-odd phases in these processes. The sensitivity to CP violation of corresponding time-integrated measurements in presence of flavor-tagging is also explored. We provide precise predictions for these observables in the SM and explore their sensitivity to new CP-violating NP contributions at present and planned future $B$-physics experiments. As such, these observables provide uniqu…
We have studied $CPT$ violation in neutrino oscillation considering three flavor framework with matter effect. We have constructed a new way to find the oscillation probability incorporating $CPT$ violating terms without any approximation. Then $CPT$ violation with atmospheric neutrinos for a magnetized iron calorimeter detector considering the muons (directly measurable with high resolution) of the charge current events has been studied for zero and nonzero $θ_{13}$ values. It is found that a potential bound of $δb_{32} \lapp 6\times 10^{-24}$ GeV at 99% CL can be obtained with 1 Mton.year ex…
Electric dipole moments from flavoured CP violation in SUSY
所谓的超对称味和CP问题与味的起源有很深的关系，因此也与SM汤川耦合本身的起源有很深的关系。我们表明，现实的SU（3）味对称性与自发CP破坏正确再现SM汤川矩阵可以同时解决这两个问题，而无需特别修改的超对称模型。我们分析了这些模型中的轻子电偶极矩和轻子味破坏过程。我们表明，电子EDM和衰变μ-> e γ自然是在拟议的实验范围内，如果sfermion质量是可测量的大型强子对撞机。
Observation of lepton number ($L$) violation by two units at colliders would provide evidence for the Majorana nature of neutrinos. We study signals of $L$-violation in the context of two popular models of neutrino masses, the type-II seesaw model and the Zee model, wherein small neutrino masses arise at the tree-level and one-loop level, respectively. We focus on $L$-violation signals at the LHC arising through the process $pp \to \ell^{\pm}\ell^{\prime \pm}$ + jets within these frameworks. We obtain sensitivity to $L$-violation in the type-II seesaw model for triplet scalar masses up to 700 …
This work mainly introduces the recent experimental process on probing the effect of Lorentz violation (LV) at d = 6, which is a specially striped-type structure experiment to increase the signal of LV. Besides, we also proposed a new experimental design using the striped geometry with triplex modulation to independently constrain the 14 LV coefficients with a higher sensitivity.
The three-body charmless hadronic decay $B^0_s \rightarrow K^{0}_{\rm S} π^{+}π^{-}$ provides a number of novel possibilities to search for CP violation effects and test the Standard Model of particle physics. These include fits to the Dalitz-plot distributions of the decay-time-integrated final state, decay-time-dependent (but without initial state flavour tagging) fits to the Dalitz-plot distribution, as well as full decay-time-dependent and flavour tagged fits. The relative sensitivities of these different approaches are investigated.
Probing $τ$ lepton dipole moments at future Lepton Colliders
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa（意大利国家核物理研究所比萨分部）；Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern（伯尔尼大学理论物理研究所爱因斯坦基础物理中心）；Centre for Cosmology, Particle Physics and Phenomenology (CP3), UCLouvain（UCLouvain宇宙学、粒子物理与现象学中心（CP3））；Dipartimento di Fisica e Astronomia, Università di Bologna and INFN, Sezione di Bologna（博洛尼亚大学物理与天文系及INFN博洛尼亚分部）；CERN, Theoretical Physics Department（欧洲核子研究中心理论物理部）；Dipartimento di Fisica e Astronomia ‘G. Galilei’, Università di Padova（帕多瓦大学‘伽利略’物理与天文系）；Istituto Nazionale Fisica Nucleare, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）
If neutrinos get mass via the seesaw mechanism the mixing matrix describing neutrino oscillations can be effectively non-unitary. We show that in this case the neutrino appearance probabilities involve a new CP phase, phi, associated to non-unitarity. This leads to an ambiguity in extracting the "standard" three--neutrino phase delta_CP, which can survive even after neutrino and antineutrino channels are combined. Its existence should be taken into account in the planning of any oscillation experiment aiming at a robust measurement of delta_CP.
We study the sensitivity of the Iron Calorimeter (ICAL) at the India-Based Neutrino Observatory (INO) to Lorentz and CPT violation in the neutrino sector. Its ability to identify the charge of muons in addition to their direction and energy makes ICAL a useful tool in putting constraints on these fundamental symmetries. Using resolution, efficiencies, errors and uncertainties obtained from ICAL detector simulations, we determine sensitivities to $δ{b}_{31}$, which parametizes the violations in the muon neutrino sector. We carry out calculations for three generic cases representing mixing in th…
Electric dipole moments (EDMs) of elementary particles are powerful probes of new physics with flavor-diagonal CP violation. The reported discrepancy in the muon anomalous magnetic moment motivates us to explore to what extent new physics with flavor-diagonal CP violation to address the discrepancy is probed by searches for the muon EDM. As a benchmark, we focus on a CP-violating two-Higgs-doublet model to explain the muon $g-2$ anomaly where the muon exclusively couples to one Higgs doublet. Since contributions to flavor violating processes as well as the electron EDM are suppressed, the muon…
The SM predicts zero value for {\bf CP} \& {\bf T} violation in the decays of $τ$ leptons -- except $τ^- \to νK_S [π^-/π^-π^0 ...]$. Our community could establish impact of New Dynamics (ND) in a {\bf CP} asymmetry in a semi-hadronic $τ$ transition and later in a second one. To be `practical', I suggest to our experimental colleagues to probe $τ^- \to ν\bar K^0 [π^-/π^-π^0/π^-η]$and $τ^- \to νK^-[π^0/π^+π^-/η]$. While I had mostly given comments about {\bf CP} violation in $τ$ transitions, some theorists have shown how ND models could produce {\bf CP} asymmetries; I will discuss these ones, al…
The production of a single top quark in association with an isolated photon probes the electromagnetic coupling structure of the top quark. We investigate the sensitivity of kinematical distributions at the LHC in single-top-plus-photon production in view of a detection of anomalous electric and magnetic dipole moments of the top quark.
CP violation (CPV) in the baryon sectors has not yet been established experimentally. In this work, we propose to search for the hyperon CPV through the Cabibbo-favored charm-baryon decaying processes involving a hyperon in the final states, such as $Λ_c^+\to Λ^0π^+, Λ^0\to pπ^-$. The CPV of the hyperon decays are purely revealed in these chain processes, since the CPV in the Cabibbo-favored charm decays are vanishing in the Standard Model (SM). The hyperons are polarized in the weak charm decays, so that we can measure the Lee-Yang asymmetric parameter $α$ by the angular distributions, and th…
Recent results from the LHC's first run have revealed intriguing departures from lepton flavour universality in the semi-leptonic decays of $B$-mesons. We discuss the complementary role that rare kaon decays can provide in testing new physics explanations of these flavour anomalies. In the framework of minimal flavour violation, we relate the chiral low-energy constants involved in $K\toπ\ell\ell'$ and $K\to\ell\ell'$ ($\ell = μ\mbox{ or } e$) with the new physics Wilson coefficients of the $b\to s$ effective Hamiltonian. We comment on the determination of these low-energy constants at NA62 an…
Motivated by the first observation of coherent-elastic neutrino-nucleus scattering at the COHERENT experiment, we confront the neutrino dipole portal giving rise to the transition of the standard model neutrinos to sterile neutrinos with the recently released CENNS 10 data from the liquid argon as well as the CsI data of the COHERENT experiment. Performing statistical analysis of those data, we show how the transition magnetic moment can be constrained for the range of the sterile neutrino mass between 10 keV and 40 MeV.
The latest data from the ACME Collaboration have put a stringent constraint on the electric dipole moment d_e of the electron. Nevertheless, the standard model (SM) prediction for d_e is many orders of magnitude below the new result, making this observable a powerful probe for physics beyond the SM. We carry out a model-independent study of d_e in the SM with right handed neutrinos and its extension with the neutrino seesaw mechanism under the framework of minimal flavor violation. We find that d_e crucially depends on whether neutrinos are Dirac or Majorana particles. In the Majorana case, d_…
We investigate the bounds on tau-mu lepton flavor violation (LFV). Our main focus is on the collider constrains on tau-mu LFV. We use the Type-III Two-Higgs-Doublet-Model (2HDM) as a set up for our study. While the LFV branching fraction of the 125 GeV is well constrained by current LHC searches, the heavier neutral states could have a large branching fraction to tau and muon. We estimate the LHC reach for the 13 TeV center of mass energy with 300 $\text{fb}^{-1}$ luminosity for a neutral boson decaying into a tau and a muon. We identify parts of the LFV parameter space where the searches for …
We study the effects of chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) on the production cross section of single top $tW$-channel at the LHC based on the effective Lagrangian approach. We show that the impact of CEDM and CMDM could be large. Using the experimental measurement of the $tW$-channel cross section, constraints on CEDM and CMDM are extracted. These constraints are comparable with the ones obtained from the top pair analysis.
The presence of non-unitary neutrino mixing can affect the measurement of the three-neutrino leptonic Dirac CP phase and hamper efforts to probe CP violation due to degeneracies of the extra non-unitary CP phase with the standard CP phase. We study the effect of including non-unitarity on probing CP violation with the long-baseline experiments NO$ν$A, T2K and DUNE. We analyze the effect of non-unitary mixing at the level of oscillation probabilities associated with the relevant baselines, and present the CP violation sensitivity for the individual experiments and their combination. Our results…
We present predictions at NLO accuracy in QCD for top-quark pair production induced by an anomalous chromomagnetic dipole moment of the top quark. Our results are obtained for total as well as fully differential cross sections, including matching to parton shower simulations. This process is expected to provide the most stringent direct limits on top-quark chromomagnetic dipole moment. We find that NLO corrections increase the contribution from the dipole moment by about 50\% at the LHC, and significantly reduce the renormalization and factorization scale dependence. Using the NLO prediction, …
When neutrino masses arise from the exchange of neutral heavy leptons, as in most seesaw schemes, the effective lepton mixing matrix $N$ describing neutrino propagation is non-unitary, hence neutrinos are not exactly orthonormal. New CP violation phases appear in $N$ that could be confused with the standard phase $δ_{\text{CP}}$ characterizing the three neutrino paradigm. We study the potential of the long-baseline neutrino experiment DUNE in probing CP violation induced by the standard CP phase in the presence of non-unitarity. In order to accomplish this we develop our previous formalism, so…
In this paper we study CP violation in photon self-interactions at low energy. These interactions, mediated by the effective operator $FFF\tilde{F}$, where ($\tilde F$) $F$ is the (dual) electromagnetic field strength, have yet to be directly probed experimentally. Possible sources for such interactions are weakly coupled light scalars with both scalar and pseudoscalar couplings to photons (for instance, complex Higgs-portal scalars or the relaxion), or new light fermions coupled to photons via dipole operators. We propose a method to isolate the CP-violating contribution to the photon self-in…
Probing unitarity violation of lepton flavor mixing matrix with reactor antineutrinos at JUNO and TAO
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）
We examine relation between neutrino oscillation parameters and prediction of lepton flavor violation, in light of deviations from tri-bimaximal mixing. Our study shows that upcoming experimental searches for lepton flavor violation process can provide useful implications for neutrino mass spectrum and mixing angles. With simple structure of heavy right-handed neutrino and supersymmetry breaking sectors, the discovery of tau \to mu gamma decay determines neutrino mass hierarchy if large (order 0.1) reactor angle is established.
The possible existence of light and heavy sterile neutrinos may give rise to direct and indirect unitarity violation of the $3\times3$ lepton mixing matrix respectively. In the current work we study the potential of future accelerator neutrino facilities in probing the unitarity violation effects. Taking DUNE, T2HK and a low-energy Neutrino Factory (LENF) as working examples of future accelerator neutrino facilities, we study the distinct effects of direct and indirect unitarity violation on the discovery reach of the leptonic CP violation and precision measurements of $θ_{23}$ in the three ne…
We discuss the formulation of the general two-Higgs doublet model type III, which incorporates flavor changing neutral scalar interactions (FCNSI) and CP violation from several sources. CP violation can arise either from Yukawa terms or from the Higgs potential, and it can explicit or spontaneous. We discuss the case that includes CP violation with Yukawa textures to control FCNSI and evaluate the CP asymmetry for the decay h-> c-b+ W-, which may allow to test the patterns of FCNSI and CP violation, that arises in these models.
In this work we study the anomalous top quark-gluon couplings Chromoelectric Dipole Moment (CEDM) and Chromomagnetic Dipole Moment (CMDM) in a general THDM with CP violation. We find that this model provides an important contribution from the $Y_{tt}$ Yukawa coupling that needs to be taken into account. The CMDM and CEDM obtained are $-0.03<Δ\tilde{k} < 0.005}$ and $|Δ\tilde{d}| < 0.005$, respectively.
The electric dipole moment (EDM) is an excellent probe of new physics beyond the standard model of particle physics. The EDM of light nuclei is particularly interesting due to the high sensitivity to the hadron level CP violation. In this proceedings contribution, we investigate the mechanism of the generation of the EDM for several light nuclei and the prospect for the discovery of new physics.
We investigate the weak electric and magnetic dipole moments of top quark-Z boson interactions at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). Their vanishingly small magnitude in the Standard Model makes these couplings ideal for probing New Physics interactions and for exploring the role of top quarks in electroweak symmetry breaking. In our analysis, we consider the production of two top quarks in association with a Z boson at the LHC, and top quark pairs mediated by neutral gauge bosons at the ILC. These processes yield direct sensitivity to top quark-Z boso…
We demonstrate that hard dijet production via coherent inelastic diffraction is a promising channel for probing gluon saturation at the Electron-Ion Collider. By $inelastic$ diffraction we mean a process in which the two hard jets - a quark-antiquark pair generated by the decay of the virtual photon - are accompanied by a softer gluon jet, emitted by the quark or the antiquark. This process can be described as the elastic scattering of an effective gluon-gluon dipole. The cross section takes a factorised form, between a hard factor and a unintegrated ("Pomeron") gluon distribution describing t…
We discuss the potential of observing effects of CP-violation phases in squark decay chains at the LHC. As the CP-odd observable, we use the asymmetry composed by triple products of final state momenta. There are good prospects of observing these effects using the method of kinematic reconstruction for the final and intermediate state particles. We also discuss the main experimental factors and the expected sensitivity.
We establish model independent bounds on the anomalous magnetic and electric dipole moments of the tau-lepton using the two-photon processes $γγ\to τ^+τ^-$ and $γγ\to τ^+τ^-γ$. We use ${\cal L}=10, 50, 100, 300, 500, 1000, 1500, 2000, 3000 \hspace{0.8mm}fb^{-1}$ of data collected with the future $e^+e^-$ linear collider such as the CLIC at $\sqrt{s}=380, 1500, 3000 \hspace{0.8mm}GeV$ and we consider systematic uncertainties of $δ_{sys}=0, 3, 5\hspace{1mm}\%$. Precise bounds at $95\%$ C. L. on the anomalous dipole moments to the tau-lepton $-0.00015\leq \tilde{a}_τ\leq 0.00017$ and $|\tilde{d}_…
In radiative $β$ decay, $T$ violation can be studied through a spin-independent $T$-odd correlation. We consider contributions to this correlation by beyond the standard model (BSM) sources of $T$-violation, arising above the electroweak scale. At the same time such sources, parametrized by dimension-6 operators, can induce electric dipole moments (EDMs). As a consequence, the manifestations of the $T$-odd BSM physics in radiative $β$ decay and EDMs are not independent. Here we exploit this connection to show that current EDM bounds already strongly constrain the spin-independent $T$-odd corre…
