arXiv subjects

I. Alikhanov

Publications and source records attributed to I. Alikhanov.

At least 19 recordsLinked to original sources

arXiv2026

Another relation among the neutrino mass-squared differences?

Determining the absolute neutrino mass scale remains a compelling challenge in particle physics. Establishing precise mathematical connections among the neutrino masses could significantly facilitate this task and shed additional light on the underlying mass-generation mechanism. We highlight the possible existence of a simple algebraic relation between the mass-squared differences, $(\sqrt{Δm^2_{31}}+\sqrt{Δm^2_{21}})/(\sqrt{Δm^2_{31}}-\sqrt{Δm^2_{21}})=\sqrt{2}$, which exhibits excellent agreement with the central values of recent global fits of neutrino oscillation data. We investigate the implications of adopting this ansatz and how it reduces the number of independent parameters in the neutrino sector. Notably, for a vanishing $ν_1$ mass, this expression directly simplifies to the elegant Fritzsch relation: $\sqrt{m_2/m_3}=\tan{(π/8)}$.

hep-ph↗

arXiv2026

Integral representation of the neutrino mass-squared differences

Determining the absolute neutrino mass scale remains one of the most compelling challenges in particle physics. To constrain theoretical models, establishing precise relations among neutrino masses is essential. We propose a simple integral representation of the neutrino mass-squared differences $Δm_{ij}^2$ that provides a complementary perspective on these oscillation parameters. We then demonstrate its utility through several examples. Specifically, assuming stringent cosmological bounds that confine the sum of neutrino masses near the normal ordering floor, we derive an analytical condition for the lightest neutrino mass, $m_1 < \sqrt{61Δm^2_{21}}/30$. Using recent data from the JUNO experiment, this yields a competitive upper limit of $m_1<0.0023$ eV (95\% C.L.). We also formulate practical analytical bounds for $m_{2}$ and $m_{3}$ adaptable to future data, and translate the results into allowed ranges for the effective electron and Majorana neutrino masses $m_{ν_e}$ and $m_{ββ}$. Finally, we show that neutrino mass relations of the Gatto-Sartori-Tonin type emerge directly from the proposed integral representation.

hep-ph↗

arXiv2026

Excitation of the Glashow resonance without neutrino beams

The $s$-channel process $\barν_ee^-\rightarrow W^-$ (on-shell) is now referred to as the Glashow resonance and being searched for at kilometer-scale neutrino ice/water detectors like IceCube, Baikal-GVD or KM3NeT. After over a decade of observations, IceCube has recorded only a few neutrino events with energies of interest such that an independent confirmation of the existence of this resonant interaction would be of great importance for testing the Standard Model. One might therefore ask: are there reactions with the Glashow resonance that would not necessitate having initial (anti)neutrino beams? This article suggests a surprisingly affirmative answer to the question $-$ namely, that the process may proceed in electron-positron collisions at accelerator energies, occurring as $e^+e^-\rightarrow W^-ρ(770)^+$. Although the resonance appears somewhat disguised, the underlying physics is transparent, quite resembling the well known radiative return: emission of $ρ^+$ from the initial state converts the incident $e^+$ into $\barν_e$. Likewise, the CP conjugate channel, $ν_e e^+\rightarrow W^+$, takes the form $e^+e^-\rightarrow W^+ρ(770)^-$. Similar reactions with muons and other hadrons are also possible. From this viewpoint, future high-luminosity lepton colliders seem to be promising for excitation of the Glashow resonance in laboratory conditions.

hep-ph↗

arXiv2021

A Light Mediator Relating Neutrino Reactions

The extension of the standard model with a multiplicative $U(1)_R$ factor is consistent with a light vector boson. In its simplest realization, only right-handed particles carry charges of the new group. In this model, there is a residual $τ_{3R}$ symmetry and one new coupling constant which correlates neutrino interactions. We compute new contributions to antineutrino$-$electron scattering and coherent scattering on nuclei, and compare them with the XENON1T result.

hep-ph↗

arXiv2021

Impact of nuclear gluon distributions on neutrino-induced leptoquark production

We analyze neutrino-induced leptoquark production on atomic nuclei. A leptoquark term in the Lagrangian admits the possibility that neutrinos interact with gluons. The current lower limits on the leptoquark masses are of the order of 1 TeV depending on the leptoquark quantum numbers and couplings. Such heavy states can be produced in ultra-high energy cosmic neutrino scattering processes. The four-momentum transfer squared and the Bjorken variable simultaneously probed in these processes may reach values kinematically inaccessible at present collider experiments. We study the impact of the gluon density in a nucleus on the cross section for the leptoquark production. We show that taking into account the nuclear parton distributions shifts the production threshold to significantly lower neutrino energies. As a particular case we consider the interaction with oxygen, which is abundant in water/ice neutrino telescopes.

hep-ph↗

arXiv2020

A chiral gauge-invariant model for Majorana neutrinos

The article investigates the possibility that right-handed neutrinos are Majorana particles embedded in an abelian multiplicative $U(1)_R$ factor, with the Lagrangian in the new factor being invariant under chiral gauge transformations. Majorana neutrinos couple to charged and neutral currents, producing new signatures to (anti)neutrino-electron elastic scattering and an additional term to coherent scattering of neutrinos on atomic nuclei. The model is ultraviolet complete and depends on one extra hypercharge correlating the reactions and providing upper bounds for the new coupling constant.

hep-ph↗

arXiv2020

Probing the Glashow resonance at electron-positron colliders

The Glashow resonance is a rapid enhancement of the cross section for scattering of electron antineutrinos on electrons at the $W^-$ boson production threshold due to the $s$-channel contribution. This resonance is being searched for at large volume neutrino detectors in which the reaction $\barν_ee^-\rightarrow W^-$ to be initiated by cosmic ray antineutrinos of energies about 6.3 PeV. The relatively small neutrino flux reaching the Earth together with the necessity of analyzing ultra-high-energy final states make such searches challenging. We argue here that the Glashow resonance may contribute to the process $e^+e^-\rightarrow~W^+W^-$. By extending the method of the effective (equivalent) particles to the neutral leptons, we relate the distribution of the effective neutrinos in the electron to the total cross section for $e^+e^-\rightarrow~W^+W^-$. Our approach gives a good fit to existing experimental data measured at the collider LEP at CERN and allows one to interpret these measurements as an observation of the Glashow resonance. We also discuss an advantage of future electron-positron colliders for probing the resonance.

hep-ph↗

arXiv2020

Charged lepton beams as a source of effective neutrinos

Neutrinos are likely the most poorly understood basic constituents of the Standard Model. In order to investigate precisely their interactions one should be able to create high intensity and well-collimated neutrino beams with known flavor compositions. This is a challenging problem for neutrino experiments. We propose a method of studying neutrino interactions based on the fact that a charged lepton is able to manifest itself effectively, with a certain probability, as a neutrino. The effective neutrino method may provide an additional tool for probing neutrino-induced reactions at $e^+e^-$ and $ep$ colliders as well as at other facilities that use charged lepton beams. We derive the distributions of the effective neutrinos in the charged leptons and give examples of application of the method to electron-positron collisions.

hep-ph↗

arXiv2018

The equivalent vector boson approximation at threshold energies

A simple derivation of the distributions of the equivalent electroweak vector bosons in leptons and quarks is presented. The applicability of the equivalent vector boson approximation at relatively low energies close to the $W$ and $Z$ boson thresholds is demonstrated. It is shown that the threshold correction to the distribution functions emerges naturally in the theory. Implications of the results for processes with the emission of the gauge bosons are discussed.

hep-ph↗

arXiv2018

Searching for new light gauge bosons at $e^+e^-$ colliders

Neutral gauge bosons beyond the Standard Model are becoming interesting as possible mediators to explain several experimental anomalies. They have small masses, below one GeV, and are referred to as dark photons, $U$, $A'$ or $Z'$ bosons. Electron--positron collision experiments at the B-factories provide the most straightforward way to probe bosons of this kind. In the present article we study production of the bosons at $e^+e^-$ colliders operating at GeV center-of-mass energies. We have studied two channels: $e^+e^-\rightarrow γZ'$ and $e^+e^-\rightarrow e^+e^-Z'$. Analytic expressions for the cross sections and various observables such as the energy spectra of the produced bosons and the final electrons from the $Z'$ decays are derived. We have also studied the transverse momentum distribution of the bosons and the spatial distribution of the $Z'\rightarrow e^+e^-$ decay vertices. It is shown that these distributions provide distinct signatures of the bosons in $e^+e^-\rightarrowγZ'$. The reaction $e^+e^-\rightarrow e^+e^-Z'$ becomes important at small $Z'$ scattering angles where its contribution to the overall yield may be larger by orders of magnitude compared to $e^+e^-\rightarrowγZ'$. The standard processes $e^+e^-\rightarrowγγ$ and $e^+e^-\rightarrow e^+e^-γ$ that lead to the same signal are considered. We include numerical predictions for the production rates at the energy $\sqrt{s}=10.5$ GeV. The case with a light scalar boson is also discussed. The calculations are performed in detail and can be useful for additional studies.

hep-ph↗

arXiv2016

Distributions for tau neutrino interactions observed through the decay $τ\rightarrow μν_τ\barν_μ$

We investigate the problem of identifying $ν_τ$-induced reactions in large neutrino telescopes. We concentrate on events with tracks and showers where the respective energies $E_μ$ and $E_X$ are measured separately. Then we compute analytically and numerically event distributions in two variables $r_l = E_X/E_l$ and $y'=E_{\text{X}}/(E_μ+E_{X})$. We find that the $y'$-distribution is especially useful because in the $ν_τ$-induced reactions the distribution has a minimum at $y'=0.75$ and then increases as $y'\rightarrow1$. This is different in $ν_μ$-induced reactions where the $y'$-distribution decreases monotonically. The results are demonstrated with figures where one can estimate the required sensitivity of the experiments. Another attractive property is that in several ratios the neutrino flux factorizes and drops out. We hope the results of this article will be useful for searches of tau (anti)neutrinos of energies above 100 GeV to several TeV in the present and planned large volume neutrino telescopes.

hep-ph↗

arXiv2016

Hidden Glashow resonance in neutrino-nucleus collisions

Today it is widely believed that $s$-channel excitation of an on-shell~$W$ boson, commonly known as the Glashow resonance, can be initiated in matter only by the electron antineutrino in the process $\barν_ee^-\rightarrow W^-$ at the laboratory energy around~6.3~PeV. In this paper we argue that the Glashow resonance within the Standard Model also occurs in neutrino--nucleus collisions. The main conclusions are as follows. 1)~The Glashow resonance can be excited by both~neutrinos and~antineutrinos of all the three flavors scattering in the Coulomb field of a nucleus. 2)~The Glashow resonance in a neutrino--nucleus reaction does not manifest itself as a Breit--Wigner-like peak in the cross section but the latter exhibits instead a slow logarithmic-law growth with the neutrino energy. The resonance turns thus out to be hidden. 3)~More than~$98\%$ of~$W$ bosons produced in the sub-PeV region in neutrino-initiated reactions in water/ice will be from the Glashow resonance. 4)~The vast majority of the Glashow resonance events in a neutrino detector is expected at energies from a few TeV to a few tens of TeV, being mostly initiated by the conventional atmospheric neutrinos dominant in this energy range. Calculations of the cross sections for Glashow resonance excitation on the oxygen nucleus as well as on the proton are carried out in detail. The results of this paper can be useful for studies of neutrino interactions at large volume water/ice neutrino detectors. For example, in the IceCube detector one can expect~0.3 Glashow resonance events with shower-like topologies and the deposited energies above~$300~\text{TeV}$ per year. It is therefore likely already to have at least one Glashow resonance event in the IceCube data set.

hep-ph↗

arXiv2014

The Glashow resonance in neutrino-photon scattering

Reactions ${ν_l}γ\rightarrow W^+l^-\,(l=e,μ,τ)$ near the threshold $\sqrt{s}=m_W+m_l$ are analyzed. Two independent calculations of the corresponding cross sections (straightforward calculations using the Standard Electroweak Lagrangian and calculations in the framework of the parton model) are compared. It is shown that the Standard Electroweak Theory strongly suggests that these reactions proceed via the Glashow resonances. Accordingly, a hypothesis that the on-shell $W$ bosons in the reactions ${ν_l}γ\rightarrow$$W^+l^-$ are the Glashow resonances is put forward. A role of these reactions for testing T symmetry at the IceCube Neutrino Observatory is discussed. A model with T-violating Glashow resonances for description of the distribution of the TeV-PeV neutrino events recently observed by the IceCube Collaboration is presented.

hep-ph↗

arXiv2014

Particle decays in the presence of a neutrino background

Several non-threshold reactions which may be used to detect the cosmic neutrino background are presented. The corresponding cross sections are calculated analytically within the Standard Model. These reactions are sensitive not only to the electron neutrinos but also to the muon and tau neutrinos. Some possibilities of experimental observation of the neutrino background are indicated.

astro-ph.CO↗

arXiv2013

CP violation in neutrino-photon scattering

It is shown that effects of CP violation arise in neutrino-photon scattering. Several CP-violating $νγ$ reactions are considered within the Standard Model and predictions for some observables are made. It is emphasized that neutrino-photon scattering may provide an experimental tool for testing the scale dependence of CP violation.

hep-ph↗

arXiv2013

Neutrino photoproduction on pseudo Nambu-Goldstone bosons

Production of single neutrinos as well as neutrino-antineutrino pairs by photons interacting with pseudo Nambu-Goldstone bosons is studied within the Standard Model. The corresponding cross sections are found analytically. The energy loss due to neutrino emission in a thermal plasma of photons and pions is calculated. It is shown that the obtained neutrino emissivity may be significantly enhanced in hot and dense matter due to in-medium modification of the pion decay constant. Phenomenological consequences for ultrarelativistic heavy-ion collisions and astrophysics are discussed.

hep-ph↗

arXiv2013

Do leptoquarks manifest themselves in ultra-high energy neutrino interactions?

It is assumed that neutrino-nucleon scattering at ultra-high energies effectively proceeds through excitations of leptoquarks in neutrino-quark subprocesses. This approach reproduces the behavior of the energy dependence of the ultra-high energy neutrino-nucleon scattering cross sections and allows to estimate masses as well as the decay widths of the involved leptoquarks. For instance, this leads to the leptoquark mass $1353\pm230$ GeV in a way independent on the leptoquark quantum numbers. The discovery potential of the LHC for the leptoquarks is evaluated.

hep-ph↗

arXiv2012

Single vector leptoquark production at hadron colliders due to direct lepton-gluon interaction

The cross section of single vector leptoquark production in direct lepton-gluon interaction is calculated. In a model independent analysis an effective Lagrangian describing the most general $C$ and $P$ conserving coupling of the leptoquarks to gluons is considered. An analytical expression is derived for the cross section in the case of anomalous vector leptoquark couplings to the gluon field. The cross sections of inclusive production of ($eq$)-, ($μq$)- and ($τq$)-type vector leptoquarks in $ep$ and $pp$ collisions due to direct lepton-gluon interaction are evaluated for $q=u, b, t$. Dependences of the cross sections on the anomalous couplings are investigated. The obtained results can be useful for studies at $ep$ colliders and the LHC.

hep-ph↗