arXiv subjects

Igor P. Ivanov

Publications and source records attributed to Igor P. Ivanov.

At least 19 recordsLinked to original sources

arXiv2026

Lepton flavor violating signals driven by CP symmetry of order 4

CP4 3HDM is a curious version of the three-Higgs-doublet model built upon a CP symmetry of order 4 (dubbed CP4). When extended to fermions, CP4 leads to unusually tight correlations between the scalar and Yukawa sectors and induces tree-level flavor changing neutral couplings. Still, viable scenarios exist, in which quark flavor changing signals remain within experimental limits. In this work, we extend CP4 to the lepton sector and investigate whether the lepton-Higgs couplings and lepton flavor violating (LFV) signals can also be kept under control. We consider two classes of LFV processes: tree-level leptonic decays of the 125 GeV Higgs boson and the muon decays $μ\to eγ$ and $μ\to 3e$. For each CP4-invariant lepton Yukawa scenario, we perform a focused Yukawa sector scan that uses physical lepton properties as input and suppresses LFV effects. We identify a promising CP4 3HDM scenario compatible with the present-day experimental constraints, show that it can accommodate the recent CMS hint of a 146 GeV scalar decaying to $eμ$, and argue that this interpretation can be tested at future colliders through the search of comparably strong $ee$ and $μμ$ signals.

hep-ph↗

arXiv2026

Universal features of high-energy scattering of Laguerre-Gaussian states

Vortex states of photons, electrons, and other particles are wave packets that carry intrinsic orbital angular momentum (OAM) and exhibit other features unavailable for plane waves. Collisions of high-energy vortex states can become a promising tool for nuclear and particle physics, once experimental challenges are overcome. An extensive literature exists on scattering processes involving vortex states; however, most works rely on assumptions that will be challenging to achieve in experiment. In this work, we initiate a systematic re-analysis of vortex-state scattering processes using paraxial Laguerre-Gaussian (LG) wave packets colliding at a non-zero impact parameter $b$. Since the total final transverse momentum $P_\perp$ is no longer fixed, we focus on how the differential cross section depends on $P_\perp$. We emphasize that non-trivial $P_\perp$-dependent features can originate either from the shape of the LG wave packets or from the dynamics of the scattering process under interest. Here, we focus on the former source and explore in detail these universal kinematic features, while the study of process-specific modifications, along with the novel insights they may bring, is delegated to a future work. Interestingly, the non-zero impact parameter $b$ plays a key role in many $P_\perp$-dependent effects, making it a useful probe of vortex states, not a nuisance factor as often assumed.

hep-ph↗

arXiv2025

Constraining the CP4-invariant three-Higgs-doublet model via top quark decays

CP4 3HDM is a peculiar three-Higgs-doublet model in which a single symmetry leads to tight constraints on the scalar and Yukawa sectors. In this models, tree-level flavor-changing neutral couplings are unavoidable; however, as previously shown, their contributions to neutral meson oscillations can be suppressed. Here, we explore the remaining quark flavor violating effects, which give rise to the top quark decays to light scalars, including the 125 GeV Higgs boson $h_{SM}$, as well as the magnitude of the $h_{SM} t\bar t$ coupling. Utilizing the recently developed scanning procedure, in which observables are used as input, we narrow down the viable options to a unique CP4-invariant Yukawa sector capable of satisfying all meson oscillation and top quark constraints. We present benchmark models that feature neutral or charged Higgs bosons lighter than the top quark, and we look forward to testing them further at the LHC and through flavor physics observables.

hep-ph↗

arXiv2025

Super light-by-light scattering in vacuum induced by intense vortex lasers

Collision of ultra-intense optical laser and X-ray free electron laser (XFEL) pulses is a promising approach to detecting nonlinear vacuum polarization (VP), a long-standing prediction of quantum electrodynamics remaining to be tested. Identifying the signals induced by polarized vacuum relies on purifying the X-ray polarization and poses significant challenges due to strongly reduced signal and low signal-to-noise ratio (SNR). Here we propose an approach that allows one to directly detect VP signals without the need for an X-ray polarizer. We identify a new VP effect in collision of an X-ray probe with an intense laser in a vortex mode, which we call the super light-by-light scattering (super-LBL), through which signal photons are kicked out of the X-ray background with large tangential momentum. Super-LBL originates from the gradient force of the vortical vacuum current in azimuthal direction and induces momentum exchange beyond the transverse momentum of laser-photon. This effect efficiently sets the scattered signal photons apart from the X-ray background, producing observable signals with both the strength and SNR more than two orders of magnitude higher than those from the known VP effects. This finding paves the way for single-shot detection of nonlinear VP phenomena with current ultra-intense laser and XFEL technologies.

physics.optics↗

arXiv2025

Superkick Effect in Vortex Particle Scattering

Vortex states of photons or electrons are a novel and promising experimental tool across atomic, nuclear, and particle physics. Various experimental schemes to generate high-energy vortex particles have been proposed. However, diagnosing the characteristics of vortex states at high energies remains a significant challenge, as traditional low-energy detection schemes become impractical for high-energy vortex particles due to their extremely short de Broglie wavelength. We recently proposed a novel experimental detection scheme based on a mechanism called "superkick" that is free from many drawbacks of the traditional methods and can reveal the vortex phase characteristics. In this paper, we present a complete theoretical framework for calculating the superkick effect in elastic electron scattering and systematically investigate the impact of various factors on its visibility. In particular, we argue that the vortex phase can be identified either by detecting the two scattered electrons in coincidence or by analyzing the characteristic azimuthal asymmetry in individual final particles.

hep-ph↗

arXiv2025

Tridiagonal scalar mass matrix in the CP4 3HDM and its implications

When parametrizing multi-Higgs potentials, it is desirable to express its coefficients via observables. This is routinely done for the 2HDM, but this approach often fails in more elaborate models. Here, we show that the scalar sector of the CP4 3HDM, an intriguing model based on an order-4 $CP$ symmetry, can also be parametrized in an observable-driven manner. The key feature that makes it work is the very special tridiagonal form of the $5\times 5$ neutral Higgs mass matrix. We propose a set of input observables and present an algorithm to reconstruct the coefficients of the potential through linear relations. Equipped with this procedure, we explore the scalar sector of the CP4 3HDM beyond the limitations of previous studies. In particular, we identify a viable and testable regime in which all additional Higgses lie in the 300-600 GeV range. This work offers a key ingredient for a future full phenomenological scan of this model.

hep-ph↗

arXiv2025

Dark matter stabilized by a non-abelian group: lessons from the $Σ(36)$ 3HDM

When building dark matter (DM) models, one often imposes conserved discrete symmetries to stabilize DM candidates. The simplest choice is ${\mathbb Z}_2$ but models with larger stabilizing groups have also been explored. Can a conserved non-abelian group lead to a viable DM model? Here, we address this question within the three-Higgs-doublet model based on the group $Σ(36)$, in which DM stabilization by a non-abelian group is not only possible but inevitable. We show that the tight connections between the Higgs, fermion, and DM sectors repeatedly drive the model into conflict with the LHC results and DM observations, with the most recent LZ results playing a decisive role. We believe that the lessons learned from this study help chart the limits of what can be achieved within multi-Higgs-doublet DM models with large symmetry groups.

hep-ph↗

arXiv2024

Unambiguous detection of high energy vortex states via the superkick effect

Vortex states of photons, electrons, and other particles are freely propagating wave packets with helicoidal wave fronts winding around the axis of a phase vortex. A particle prepared in a vortex state carries a non-zero orbital angular momentum projection on the propagation direction, a quantum number that has never been exploited in experimental particle and nuclear physics. Low-energy vortex photons, electrons, neutrons, and helium atoms have been demonstrated in experiment and found numerous applications, and there exist proposals of boosting them to higher energies. However, verification that a high energy particle is indeed in a vortex state will be a major challenge, since the low energy techniques become impractical at higher energies. Here, we propose a new diagnostic method based of the so-called superkick effect, which can unambiguously detect the presence of a phase vortex. A proof-of-principle experiment with vortex electrons can be done with existing technology, and its realization will also constitute the first observation of the superkick effect.

hep-ph↗

arXiv2024

Decay of the vortex muon

Muon decay is self-analyzing: the spectral-angular distribution of the emitted electron reveals the spin orientation of the polarized muon. Here, we show that the same feature applies to muons in non-plane-wave states and helps reveal the rich polarization opportunities available. We focus on the so-called vortex states, in which the muon carries a non-zero orbital angular momentum with respect to the average propagation direction and exhibits a cone structure in the momentum distribution. We compute the spectrum and the angular distribution of the electrons emitted in decays of vortex muons and show that the most revealing observable is not the angular distribution but the fixed-angle electron spectra. Even for very small cone opening angles of the vortex muons, it will be easy to observe significant modifications of the electron spectra which would allow one to distinguish vortex muons from approximately plane wave muons, as well as to differentiate among various polarization states. These features will be the key to tracking the evolution of vortex muons in external magnetic fields.

hep-ph↗

arXiv2024

Symmetries for the 4HDM. II. Extensions by rephasing groups

We continue classification of finite groups which can be used as symmetry group of the scalar sector of the four-Higgs-doublet model (4HDM). Our objective is to systematically construct non-abelian groups via the group extension procedure, starting from the abelian groups $A$ and their automorphism groups $\mathrm{Aut}(A)$. Previously, we considered all cyclic groups $A$ available for the 4HDM scalar sector. Here, we further develop the method and apply it to extensions by the remaining rephasing groups $A$, namely $A = \mathbb{Z_2}\times\mathbb{Z_2}$, $\mathbb{Z_4}\times \mathbb{Z_2}$, and $\mathbb{Z_2}\times \mathbb{Z_2}\times \mathbb{Z_2}$. As $\mathrm{Aut}(A)$ grows, the procedure becomes more laborious, but we prove an isomorphism theorem which helps classify all the options. We also comment on what remains to be done to complete the classification of all finite non-abelian groups realizable in the 4HDM scalar sector without accidental continuous symmetries.

hep-ph↗

arXiv2024

Splitting the second: Designing a physics course with an emphasis on timescales of ultrafast phenomena

Timescales spanning 24 orders of magnitude smaller than one second can be studied experimentally, and each range is packed with different physical phenomena. This rich range of timescales offers a great context for an innovative undergraduate physics course which introduces modern physics and technology from an unconventional perspective. Based on the author's experience in lecturing on these topics to different audiences, this paper proposes a syllabus of a semester-long timescale-based undergraduate physics course.

physics.ed-ph↗

arXiv2024

Charge-breaking domain walls separating neutral vacua in multi-Higgs models

The scalar potential of a multi-Higgs model can possess a rich structure of minima and saddle points, which evolves in an intricate way as the parameters change. In the hot early Universe, it could trigger multi-step phase transitions, with exotic intermediate phases and peculiar domain wall configurations. Here, we provide a glimpse into this richness with the example of the three-Higgs-doublet model with the symmetry group $Σ(36)$, either exact or softly broken. We present its phase diagram tracking not only the global minimum but all of its extrema. In particular, we reveal parameter space regions in which the deepest saddle point is charge breaking. This naturally leads to phase transitions between neutral vacua which involve expanding and colliding charge-breaking bubble walls. We also comment on opportunities of multi-step phase transitions, on charge-breaking intermediate phases, and on phase transitions between different charge-breaking vacua. We illustrate the general discussion with two benchmark models, one of which possesses competing saddle points and allows for emergence of bubbles of the same true vacuum but with bubble walls of different nature. The intriguing cosmological implications of all these possibilities deserve dedicated study.

hep-ph↗

arXiv2024

Confronting CP symmetry of order 4 with experimental data

CP4 3HDM is a three-Higgs-doublet model based on a $CP$ symmetry of order 4 (CP4). It is the minimal model incorporating CP4 without leading to accidental symmetries or running into immediate conflict with experiment. Imposing CP4 on the lagrangian induces remarkably tight connections between the scalar and Yukawa sectors, including the unavoidable tree-level flavor-changing neutral couplings (FCNC). Here, we explore whether it is at all possible in the CP4 3HDM to suppressed FCNC to a level compatible with the neutral meson oscillation constraints. We express the FCNC matrices in terms of physical quark observables and quark rotation parameters, and scan the Yukawa parameter space using the quark masses and mixing parameters as input. With this procedure, we find that only two out of the eight possible CP4 Yukawa sectors are compatible with the $K$, $B$, $B_s$ and, in particular, $D$-meson oscillation constraints. The results clearly indicate a way how to construct phenomenologically viable benchmark CP4 3HDMs.

hep-ph↗

arXiv2024

Intermediate Charge-Breaking Phases and Symmetry Non-Restoration in the 2-Higgs-Doublet Model

The Higgs potentials of extended Higgs sectors exhibit a complex and interesting vacuum structure. When travelling back in time, i.e. going to higher temperatures, the structure may change and exhibit interesting phase patterns and sequences of phases related to the respective minima of the potential. The investigation of the vacuum structure can give us indirect insights in beyond-Standard-Model physics and the evolution of the Universe. In this paper, we investigate the possibility of an intermediate charge-breaking (CB) phase in the 2-Higgs-Doublet Model (2HDM) type I. The existence has been reported previously by using a simple potential setup. We here confirm that the intermediate CB phase can still exist when using the one-loop corrected effective potential including thermal masses. We discuss its features and the relation with SU(2) symmetry (non-)restoration as well as its consistency with the current experimental data. Lastly, we show for some selected benchmark points the rich and interesting phase patterns and sequences that the 2HDM can undergo during its evolution from the early Universe to today's electroweak vacuum.

hep-ph↗

arXiv2023

Symmetries for the 4HDM: extensions of cyclic groups

Multi-Higgs models equipped with global symmetry groups, either exact or softly broken, offer a rich framework for constructions beyond the Standard Model and lead to remarkable phenomenological consequences. Knowing all the symmetry options within each class of models can guide its phenomenological exploration, as confirmed by the vast literature on the two- and three-Higgs-doublet models. Here, we begin a systematic study of finite non-abelian symmetry groups which can be imposed on the scalar sector of the four-Higgs-doublet model (4HDM) without leading to accidental symmetries. In this work, we derive the full list of such non-abelian groups available in the 4HDM that can be constructed as extensions of cyclic groups by their automorphism groups. This list is remarkably restricted but it contains cases which have not been previously studied. Since the methods we develop may prove useful for other classes of models, we present them in a pedagogical manner.

hep-ph↗

arXiv2023

Threshold effects in high-energy vortex state collisions

Collisions of particles prepared in non--plane-wave states with a non-trivial phase structure, such as vortex states carrying an adjustable orbital angular momentum (OAM), open novel opportunities in atomic, nuclear, and high-energy physics unavailable for traditional scattering experiments. Recently, it was argued that photoinduced processes such as $γd \to pn$ and $γp \to Δ^+$ initiated by a high-energy vortex photon should display a remarkable threshold shift and a sizable cross section enhancement as the impact parameter $b$ of the target hadron with respect to the vortex photon axis goes to zero. In this work, we theoretically explore whether this effect exists within the quantum-field-theoretic treatment of the scattering process. We do not rely on the semiclassical assumption of pointlike, non-spreading target particle and, instead, consider the toy process of heavy particle pair production in collision of two light particles prepared as a Laguerre-Gaussian and a compact Gaussian wave packets, paying special attention to the threshold behavior of the cross section. We do observe threshold smearing due to non-monochromaticity of the wave packets, but we do not confirm the near-threshold enhancement. Instead we find an OAM-related dip at $b\to 0$ as compared with the two Gaussian wave packet collision.

hep-ph↗

arXiv2023

Limiting FCNC induced by a CP symmetry of order 4

CP4 3HDM is a three-Higgs-doublet model based on the $CP$ symmetry of order 4 (CP4). Imposing CP4 leads to remarkable connections between the scalar and Yukawa sectors and unavoidably generates tree-level flavor-changing neutral couplings (FCNC). It remains unclear whether FCNC can be sufficiently suppressed in the CP4 3HDM. In this paper, we systematically explore this issue. We first develop an efficient scanning procedure which takes the quark masses and mixing as input and expresses the FCNC matrices in terms of physical quark observables and quark rotation parameters. This procedure allows us to explore the FCNC effects for all the Yukawa sectors possible within the CP4 3HDM. We find that, out of the eight possible CP4 Yukawa sectors, only two scenarios are compatible with the $K$, $B$, $B_s$ and, in particular, $D$-meson oscillation constraints. The results of this work serve as clear guidelines for future phenomenological scans of the model.

hep-ph↗

arXiv2022

Promises and challenges of high-energy vortex states collisions

Vortex states of photons, electrons, and other particles are non--plane-wave solutions of the corresponding wave equation with helicoidal wave fronts. These states possess an intrinsic orbital angular momentum with respect to the average propagation direction, which represents a new degree of freedom, previously unexplored in particle or nuclear collisions. Vortex states of photons, electrons, neutrons, and neutral atoms have been experimentally produced, albeit at low energies, and are being intensively explored. Anticipating future experimental progress, one can ask what additional insights on nuclei and particles one can gain once collisions of high-energy vortex states become possible. This review describes the present-day landscape of physics opportunities, experimental progress and suggestions relevant to vortex states in high energy collisions. The aim is to familiarize the community with this emergent cross-disciplinary topic and to provide a sufficiently complete literature coverage, highlighting some results and calculational techniques.

hep-ph↗