Neutrino-nucleon Cross Section Research Articles

A ν window onto leptoquarks?

Upcoming neutrino telescopes promise a new window onto the interactions of neutrinos with matter at ultrahigh energies (Eν = 107–1010 GeV), and the possibility to detect deviations from the Standard Model predictions. In this paper, we update previous predictions for the enhancement of the neutrino-nucleon cross-section for motivated leptoquark models and show the latest neutrino physics bound, as well as analyse the latest LHC pair production and Drell-Yan data, and flavour constraints (some of which were previously missed). We find that, despite the next generation of neutrino experiments probing the highest energies, they will not be enough to be competitive with collider searches.

Geant4model for neutrino nucleon/nucleus integral cross sections

The Geant4model for neutrino nucleon/nucleus integral cross sections, based on selection of the existing physical models, is discussed. The comparison of the model predictions with experimental data for quasi-elastic, inelastic and total neutrino nucleon cross sections is presented.

Single-pion production in electron-proton interactions

This paper presents an extension of the MK single-pion production model [Kabirnezhad, Phys. Rev. D 97, 013002 (2018); Phys. Rev. D 102, 053009 (2020)] to high hadron invariant mass ($W$) and high momentum transfer (${Q}^{2}$) to conform to the predictions of perturbative QCD due to the quark-hadron duality evidence. New form factors for several resonances and nonresonant background in the electron-nucleon cross sections are determined taking into account the experimental data and improved evaluation techniques. Fits to electron-proton scattering data are used to constrain free parameters and to assign the related uncertainties of the model. The results from this work can be used to determine the vector current in the corresponding neutrino-nucleon cross sections, which is an important input for event generators in long-baseline neutrino-oscillation measurements.

Detector requirements for model-independent measurements of ultrahigh energy neutrino cross sections

The ultrahigh energy range of neutrino physics (above $\ensuremath{\sim}{10}^{7}\text{ }\text{ }\mathrm{GeV}$), as yet devoid of detections, is an open landscape with challenges to be met and discoveries to be made. Neutrino-nucleon cross sections in that range---with center-of-momentum energies $\sqrt{s}\ensuremath{\gtrsim}4\text{ }\text{ }\mathrm{TeV}$---are powerful probes of unexplored phenomena. We present a simple and accurate model-independent framework to evaluate how well these cross sections can be measured for an unknown flux and generic detectors. We also demonstrate how to characterize and compare detector sensitivity. We show that cross sections can be measured to ${\ensuremath{\simeq}}_{\ensuremath{-}30}^{+65}%$ precision over $\sqrt{s}\ensuremath{\simeq}4--140\text{ }\text{ }\mathrm{TeV}$ (${E}_{\ensuremath{\nu}}={10}^{7}\ensuremath{-}{10}^{10}\text{ }\text{ }\mathrm{GeV}$) with modest energy and angular resolution and $\ensuremath{\simeq}10$ events per energy decade. Many allowed novel-physics models (extra dimensions, leptoquarks, etc.) produce much larger effects. In the distant future, with $\ensuremath{\simeq}100$ events at the highest energies, the precision would be $\ensuremath{\simeq}15%$, probing even QCD saturation effects.

Implications of the neutrino-nucleon cross-section dynamics on the description of ultrahigh-energy neutrino data

Implications of the neutrino-nucleon cross-section dynamics on the description of ultrahigh-energy neutrino data

The ultra-high-energy neutrino-nucleon cross section: measurement forecasts for an era of cosmic EeV-neutrino discovery

Neutrino interactions with protons and neutrons probe their deep structure and may reveal new physics. The higher the neutrino energy, the sharper the probe. So far, the neutrino-nucleon (νN) cross section is known across neutrino energies from a few hundred MeV to a few PeV. Soon, ultra-high-energy (UHE) cosmic neutrinos, with energies above 100 PeV, could take us farther. So far, they have evaded discovery, but upcoming UHE neutrino telescopes endeavor to find them. We present the first detailed measurement forecasts of the UHE νN cross section, geared to IceCube-Gen2, one of the leading detectors under planning. We use state-of-the-art ingredients in every stage of our forecasts: in the UHE neutrino flux predictions, the neutrino propagation inside Earth, the emission of neutrino-induced radio signals in the detector, their propagation and detection, and the treatment of backgrounds. After 10 years, if at least a few tens of UHE neutrino-induced events are detected, IceCube-Gen2 could measure the νN cross section at center-of-mass energies of sqrt{s} ≈ 10–100 TeV for the first time, with a precision comparable to that of its theory prediction.

NNNPDF3.0: evidence for a modified partonic structure in heavy nuclei

We present an updated determination of nuclear parton distributions (nPDFs) from a global NLO QCD analysis of hard processes in fixed-target lepton-nucleus and proton-nucleus together with collider proton-nucleus experiments. In addition to neutral- and charged-current deep-inelastic and Drell–Yan measurements on nuclear targets, we consider the information provided by the production of electroweak gauge bosons, isolated photons, jet pairs, and charmed mesons in proton-lead collisions at the LHC across centre-of-mass energies of 5.02 TeV (Run I) and 8.16 TeV (Run II). For the first time in a global nPDF analysis, the constraints from these various processes are accounted for both in the nuclear PDFs and in the free-proton PDF baseline. The extensive dataset underlying the nNNPDF3.0 determination, combined with its model-independent parametrisation, reveals strong evidence for nuclear-induced modifications of the partonic structure of heavy nuclei, specifically for the small-x shadowing of gluons and sea quarks, as well as the large-x anti-shadowing of gluons. As a representative phenomenological application, we provide predictions for ultra-high-energy neutrino-nucleon cross-sections, relevant for data interpretation at neutrino observatories. Our results provide key input for ongoing and future experimental programs, from that of heavy-ion collisions in controlled collider environments to the study of high-energy astrophysical processes.

Neutrino-nucleon cross-section model tuning in GENIE v3

We summarise the results of a study performed within the GENIE global analysis framework, revisiting the GENIE bare-nucleon cross-section tuning and, in particular, the tuning of a) the inclusive cross-section, b) the cross-section of low-multiplicity inelastic channels (single-pion and double-pion production), and c) the relative contributions of resonance and non-resonance processes to these final states. The same analysis was performed with several different comprehensive cross-section model sets available in GENIE Generator v3. In this work we performed a careful investigation of the observed tensions between exclusive and inclusive data, and installed analysis improvements to handle systematics in historic data. All tuned model configurations discussed in this paper are available through public releases of the GENIE Generator. With this paper we aim to support the consumers of these physics tunes by providing comprehensive summaries of our alternate model constructions, of the relevant datasets and their systematics, and of our tuning procedure and results.

Measurement of the high-energy all-flavor neutrino-nucleon cross section with IceCube

The flux of high-energy neutrinos passing through the Earth is attenuated due to their interactions with matter. The interaction rate is modulated by the neutrino interaction cross section and affects the flux arriving at the IceCube Neutrino Observatory, a cubic-kilometer neutrino detector embedded in the Antarctic ice sheet. We present a measurement of the neutrino cross section between 60 TeV and 10 PeV using the high-energy starting events (HESE) sample from IceCube with 7.5 years of data. The result is binned in neutrino energy and obtained using both Bayesian and frequentist statistics. We find it compatible with predictions from the Standard Model. Flavor information is explicitly included through updated morphology classifiers, proxies for the the three neutrino flavors. This is the first such measurement to use the three morphologies as observables and the first to account for neutrinos from tau decay.

Cross sections of ultrahigh-energy neutrinos: Comparison with ICE-CUBE data

Ultrahigh energetic neutrino events have been recorded by ICE-CUBE. The detection of these events indicates the extragalactic origin of the neutrinos. In order to characterized the elementary mechanisms responsible for the emission of these neutrinos it is necessary to determine their energy distributions and flavor compositions. In this work we are presenting the results of neutrino-nucleon cross section for the interaction with nucleons of a detector. The elementary diagrams for the neutrino-proton (or neutron) interactions have been calculated at the quark level adding the corresponding form factors for quarks in nucleons, as well as nuclear parton distribution functions. The leptonic sector of the current-current interactions have been calculated including neutrino oscillations and the mixing with a sterile neutrino.

Precise predictions for multi-TeV and PeV energy neutrino scattering rates

The scattering rate of multi-${\rm TeV}$ and ${\rm PeV}$ energy neutrinos is fast becoming an interesting topic in (astro)particle-physics. This is due to experimental progress at Neutrino Telescopes such as IceCube which have begun to gain sensitivity to the flux of neutrinos in this energy range. In view of this, a precise calculation of the scattering rate of neutrinos upon atoms is presented. The two main components of the calculation are the differential cross-section predictions for neutrino scattering upon an atomic nucleus (such as that which make up water), as well as upon atomic electrons. In the first case, the predictions for neutrino-nucleon cross-sections in charged- and neutral-current scattering are refined by including resonant contributions generated within the photon field of the nucleus, which alter the considered distributions by up to $\approx 4\%$. In the latter case, radiative corrections are provided for all $2\to2$ scattering processes of the form $\bar{\nu}_e e^-\to f\bar{f}^{\prime}$. For antineutrino energies of $E_{\bar{\nu}_e}\approx6{\rm~PeV}$, where these processes become resonantly enhanced (the Glashow resonance) and dominate the total cross-section, these corrections amount to $\approx-10\%$.

Probing strong dynamics with cosmic neutrinos

IceCube has observed 80 astrophysical neutrino candidates in the energy range 0.02 < E_\nu/PeV < 2. Deep inelastic scattering of these neutrinos with nucleons on Antarctic ice sheet probe center-of-mass energies $\sqrt{s} \sim$ 1 TeV. By comparing the rates for two classes of observable events, any departure from the benchmark (perturbative QCD) neutrino-nucleon cross section can be constrained. Using the projected sensitivity of South Pole next generation neutrino telescope we show that this facility will provide a unique probe of strong interaction dynamics. In particular, we demonstrate that the high-energy high-statistics data sample to be recorded by IceCube-Gen2 in the very near future will deliver a direct measurement of the neutrino-nucleon cross section at $\sqrt{s} \sim 1$ TeV, with a precision comparable to perturbative QCD informed by HERA data. We also use IceCube data to extract the neutrino-nucleon cross section at $\sqrt{s} \sim 1$ TeV through a likelihood analysis, considering (for the first time) both the charged-current and neutral-current contributions as free parameters of the likelihood function.

Strong constraints on non-standard neutrino interactions: LHC vs. IceCube

We find the constraints on various non-standard interactions (NSI) of neutrinos from monojet+T searches at the Large Hadron Collider (LHC). Also, we show that the measurement of neutrino-nucleon cross-section from the observation of high energy astrophysical neutrino events at IceCube facilitates strong constraints on NSI as well. To this end, we pursue a comparative study of the prospects of LHC and IceCube in detecting NSI, also mentioning the role of low-energy experiments. We discuss the case of NSI with a new vector boson Z′ and it is found that for some range of mz′ LHC puts more stringent bound, whereas IceCube supersedes elsewhere. We also pay special attention to the case of Z′ of mass of a few GeVs, pointing out that the IceCube constraints can surpass those from LHC and low-energy experiments. Although, for contact-type effective interactions with two neutrinos and two partons, constraints from LHC are superior.

Studying low−x structure function models with astrophysical tau neutrinos

Despite not have been yet identified by the IceCube detector, events generated from $\nu_{\tau}$ deep inelastic neutrino scattering in ice with varied topologies, such as double cascades (often called \textit{double bangs}), \textit{lollipops} and \textit{sugardaddies}, constitute a potential laboratory for low-x parton studies. Here we investigate these events, analyzing the effect of next-to-next-to-leading order (NNLO) Parton Distribution Function (PDFs) in the total neutrino--nucleon cross section, as compared with the color dipole formalism, where saturation effects play a major role. Energy deposit profiles in the `bangs' are also analysed in terms of virtual $W$-boson and tauon energy distributions and are found to be crucial in establishing a clear signal for gluon distribution determination at very small $x$. By taking the average (all flavor) neutrino flux ($\Phi_{\nu}\sim E_{\nu}^{-2.3}$) into differential cross sections as a function of $\tau$ and $W$ energies, we find significant deviations from pure DGLAP parton interactions for neutrino energies already at a few PeV. With these findings one aims at providing not only possible observables to be measured in large volume neutrino detectors in the near future, but also theoretical ways of unraveling QCD dynamics using unintegrated neutrino-nucleon cross sections in the ultrahigh-energy frontier.

Prime–index parametrization for total neutrino-nucleon cross sections and pp cross sections

A prime number based parametrization for total neutrino-nucleon cross section is presented. The method employs the relation between prime numbers and their indices to reproduce neutrino cross sections for neutrino energies from the MeV to the PeV regions where experimental data are available. This prime–index relation provides estimates of the neutrino-nucleon cross sections valid across many decades of neutrino energy scales. The PeV data are from the recently published astrophysical rates in the IceCube detector as well as neutrino-nucleon cross section measurements. A similar method has been employed for high energy pp cross sections which explains the parametrization first proposed by Heisenberg.

Extracting the Energy-Dependent Neutrino-Nucleon Cross Section above 10TeV Using IceCube Showers.

Neutrinos are key to probing the deep structure of matter and the high-energy Universe. Yet, until recently, their interactions had only been measured at laboratory energies up to about 350GeV. An opportunity to measure their interactions at higher energies opened up with the detection of high-energy neutrinos in IceCube, partially of astrophysical origin. Scattering off matter inside Earth affects the distribution of their arrival directions-from this, we extract the neutrino-nucleon cross section at energies from 18TeV to 2PeV, in four energy bins, in spite of uncertainties in the neutrino flux. Using six years of public IceCube High-Energy Starting Events, we explicitly show for the first time that the energy dependence of the cross section above 18TeV agrees with the predicted softer-than-linear dependence, and reaffirm the absence of new physics that would make the cross section rise sharply, up to a center-of-mass energy sqrt[s]≈1 TeV.

High-energy neutrino interaction physics with IceCube

Although they are best known for studying astrophysical neutrinos, neutrino telescopes like IceCube can study neutrino interactions, at energies far above those that are accessible at accelerators. In this writeup, I present two IceCube analyses of neutrino interactions at energies far above 1 TeV. The first measures neutrino absorption in the Earth, and, from that determines the neutrino-nucleon cross-section at energies between 6.3 and 980 TeV. We find that the cross-sections are 1.30 +0.21 -0.19 (stat.) +0.39 -0.43 (syst.) times the Standard Model crosssection. We also present a measurement of neutrino inelasticity, using νμ charged-current interactions that occur within IceCube. We have measured the average inelasticity at energies from 1 TeV to above 100 TeV, and found that it is in agreement with the Standard Model expectations. We have also performed a series of fits to this track sample and a matching cascade sample, to probe aspects of the astrophysical neutrino flux, particularly the flavor ratio.

Neutrino tomography of Earth

Cosmic-ray interactions with the atmosphere produce a flux of neutrinos in all directions with energies extending above the TeV scale1. The Earth is not a fully transparent medium for neutrinos with energies above a few TeV, as the neutrino–nucleon cross-section is large enough to make the absorption probability non-negligible2. Since absorption depends on energy and distance travelled, studying the distribution of the TeV atmospheric neutrinos passing through the Earth offers an opportunity to infer its density profile3–7. This has never been done, however, due to the lack of relevant data. Here we perform a neutrino-based tomography of the Earth using actual data—one-year of through-going muon atmospheric neutrino data collected by the IceCube telescope8. Using only weak interactions, in a way that is completely independent of gravitational measurements, we are able to determine the mass of the Earth and its core, its moment of inertia, and to establish that the core is denser than the mantle. Our results demonstrate the feasibility of this approach to study the Earth’s internal structure, which is complementary to traditional geophysics methods. Neutrino tomography could become more competitive as soon as more statistics is available, provided that the sources of systematic uncertainties are fully under control. Geophysical properties of the Earth’s interior have been inferred by looking at the absorption of neutrinos as they pass through our planet.

Freeze-in production of sterile neutrino dark matter in U(1)B−L model

With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1)B−L model. The U(1)B−L model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W± decay can also be a dominant production mode of the sterile neutrino DM . To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1)B−L model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.

Highlights from T2K

T2K is a long-baseline neutrino experiment designed to measure neutrino oscillations parameters. A high-intensity beam of muon neutrinos produced at the J-PARC accelerator complex is sent towards the near detector facility (the ND280 and INGRID detectors, located 280 m away from the neutrino source) and the far detector, Super-Kamiokande (295 km away). The change in the measured intensity and the composition of the neutrino beam between the near and far detectors are used to provide information on the oscillation parameters. T2K has delivered the world’s best measurement of the θ23 angle by observing muon neutrino disappearance. It was also the first experiment to observe electron neutrino appearance (2013) with a significance of 7.3 σ, to measure the associated θ13 mixing angle, and to provide the first hint of a non-zero δCP phase. The first running of anti-neutrinos in the T2K experiment shows a clear dip below 1 GeV, as expected for an oscillation signal. The T2K experiment is also capable of providing information on neutrino-nucleon cross sections at energies around 1 GeV, thanks to a large amount of target material present in the near detector facility.