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DOE OSTI2012

The NOvA Experiment

The NOνA experiment aims to study the mixing behavior of neutrinos and will attempt to resolve the neutrino mass hierarchy. The experiment will rely on data collected at two detectors, one near Fermilab\'s NuMI (Neutrinos at the Main Injector) target and one 810 km north at Ash River, MN. The detectors are 14 mrad off the beam axis, which results in an almost monoenergetic beam of 2 GeV neutrinos. The construction of the far detector started early this year, the instrumentation will commence this fall, and we hope to take our first data in the beginning of next year. In this talk I will focus on the exciting possibilities of our detector in light of recent neutrino results and will discuss our plans to measure the neutrino mixing angle θ13 as well as to attempt to resolve the neutrino mass hierarchy and to understand the effects of the CP violating phase angle δ. I will also survey the rich physics program provided by our 14 kT fully active far detector, such as searches for magnetic monopoles and detection of supernovaneutrinos.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2013

Neutrinos: Theory and Phenomenology

The theory and phenomenology of neutrinos will be addressed, especially that relating to the observation of neutrino flavor transformations. The current status and implications for future experiments will be discussed with special emphasis on the experiments that will determine the neutrino mass ordering, the dominant flavor content of the neutrino mass eigenstate with the smallest electron neutrino content and the size of CP violation in the neutrino sector. Beyond the neutrino Standard Model, the evidence for and a possible definitive experiment to confirm or refute the existence of light sterile neutrinos will be briefly discussed.

HEP↗

DOE OSTI2017

Hot leptogenesis from thermal Dark Matter

In this work, we investigate a scenario in which heavy Majorana Right-Handed Neutrinos (RHNs) are in thermal equilibrium with a dark sector with temperature higher than the Standard Model (SM) thermal bath. Specifically, we consider the scenario in which thermal Dark Matter (DM) abundance is fixed from the freeze-out of DM annihilations into RHNs. Due to the inert nature of the RHNs, we show that it is possible for the two sectors to remain thermally decoupled by having more than two generations of the RHNs. The hotter temperature implies higher abundances of DM and RHNs with the following consequences. For leptogenesis, an enhancement in efficiency up to a factor of 51.6 can be obtained, though a resonant enhancement of CP violation is still required due to an upper mass bound of about 4 TeV for the RHNs. For the DM, an enhanced annihilation cross section up to a factor of 51.6 is required to obtain the correct DM abundance. This scenario can be probed via indirect detection of DM annihilating into RHNs, which then decay into hν, Zν and W ± ℓ ∓ with an enhanced annihilation cross section above the typical thermal value.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Baryogenesis, primordial black holes and MHz–GHz gravitational waves

Gravitational waves (GWs) in the MHz–GHz frequency range are motivated by a host of early Universe phenomena such as oscillons, preheating, and cosmic strings. We point out that baryogenesis too serves as a motivation to probe GWs in this frequency range. The connection is through primordial black holes (PBHs): on the one hand, PBHs induce baryogenesis by Hawking evaporating into a species that has baryon number and CP violating decays; on the other, PBHs induce GWs through second order effects when the scalar fluctuations responsible for their formation re-enter the horizon. We describe the interplay of the parameters responsible for successful baryogenesis on the plane of the strain and frequency of the induced GWs, being careful to delineate regimes where PBH domination or washout effects occur. We provide semi-analytic scalings of the GW strain with the baryon number to entropy ratio and other parameters important for baryogenesis. Along the way, we sketch a solution to the dark matter-baryogenesis coincidence problem with two populations of PBHs, which leads to a double-peaked GW signal. Our results underscore the importance of probing the ultra high frequency GW frontier.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Recent three-flavor neutrino oscillation results from the NOvA experiment

NOvA is a long-baseline experiment studying primarily neutrino oscillations in the NuMI beam from Fermi National Laboratory (FNAL), USA. It consists of two functionally identical, finely granulated detectors which are separated by 810 km and situated 14.6 mrad off the NuMI beam axis from FNAL. By measuring the transition probabilities P(vμ → ve) and P(vμ → vμ), NOvA is able to probe the following parameters: , the mixing angle θ23, the CP violating phase δCP and the neutrino mass hierarchy. This document is devoted to the latest NOvA measurements of the neutrino oscillation parameters using neutrino and antineutrino disappearance and appearance obtained in 2020.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2012

The NOvA Data Acquisition System

The NOvA experiment is a long baseline neutrino experiment designed to make key measures to determine the neutrino mass hierarchy, neutrino mixing and CP violation in the neutrino sector. In order to make these measurements the NOvA collaboration has designed a highly distributed, synchronized, continuous digitization and readout system that is able to acquire and correlate data from the Fermilab accelerator complex, the NOvA near detector at Fermilab and the NOvA far detector which is located 810 km away at Ash River, MN. This system has unique properties that let it fully exploit the physics capabilities of the NOvA detector. This paper discusses the design of the NOvA DAQ system and its capabilities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2014

Synchronization of the 14 kTon NO$\nu$A neutrino detector with the Fermilab NuMI beam

The NOνA experiment is a neutrino oscillation experiment designed to measure parameters related to the neutrino mixing matrix, mass hierarchy and CP violation. The experiment measures neutrino and anti-neutrino interactions from the NuMI beam line at Fermilab in a Near Detector and a Far Detector located 810 kilometers away. Making these measurements requires precise synchronization of 344,064 channels in the Far Detector to an absolute wall time with a channel to channel variation of less then 10 ns. The experiment must correlate the presence of the relatively narrow neutrino beam in the detector with data readout. This paper will discuss the performance of the NOνA timing system during the first few months of operation at the Far Detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2014

The NO$\nu$A Far Detector Data Acquisition System

The NOνA experiment is a long-baseline neutrino experiment designed to make measurements to determine the neutrino mass hierarchy, neutrino mixing parameters and CP violation in the neutrino sector. In order to make these measurements the NOνA collaboration has designed a highly distributed, synchronized, continuous digitization and readout system that is able to acquire and correlate data from the Fermilab accelerator complex (NuMI), the NOνA near detector at the Fermilab site and the NOνA far detector which is located 810 km away at Ash River, MN. This system has unique properties that let it fully exploit the physics capabilities of the NOνA detector. The design of the NOνA DAQ system and its capabilities are discussed in this paper.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2025

DUNE Photon Detection System

The Deep Underground Neutrino Experiment (DUNE) aims to provide a broad physics program primarily addressed to probing CP violation in the neutrino sector and identifying the neutrino mass hierarchy. The search for proton decay, the observation of supernova neutrino bursts, and the investigation of solar neutrinos represent other additional goals of DUNE experiment, which can be enhanced by the use and the high performances of the Photon Detection System (PDS). Using the technology based on liquid argon Time Projection Chamber (LArTPC), the experiment plans to observe neutrino interactions inside detectors located 1300 km away from the Long Baseline Neutrino Facility (LBNF) at Fermi National Accelerator Laboratory (FNAL), where the neutrinos are produced. The experiment consists of two main parts, respectively the far and near detectors. The far site will comprise four detector modules. The first module is constituted by a vertical drift single-phase LArTPC, while the second module provides a horizontal drift single-phase LArTPC. The configurations of the other modules are still under definition. Neutrino detection in LArTPCs is achieved by identifying the charge and light generated from its interactions with liquid argon. The wire planes of the instrumented anode and the PDS detect these signals, respectively. The PDS in the first two modules, detailed in the present document, uses a modified version of the so-called ARAPUCA technology, named X-ARAPUCA. This system consisting of a highly reflecting box with an entrance window made by dichroic filters and wavelength shifters, creates a trap to detect the VUV (128 nm) scintillation photons. The X-ARAPUCA of the first module is called Supercell, and it has dimensions of 488×100 mm 2 , while Megacell is the second module version, with an active area of 60×60 cm 2 . This latter configuration also represents a significant technological advancement. Since half of the modules are placed on the cathode at high voltage, they are powered and read out using innovative power-over-fiber (PoF) and signal-over-fiber (SoF) technologies. Meanwhile, the other half are installed in a membrane behind the field cage, with a total transparency of around 70%.

Neutrino detectors↗

DOE OSTI2013

High-statistics study of $K^0_S$ pair production in two-photon collisions

We report a high-statistics measurement of the differential cross section of the process $γγ → K^0_S K^0_S$ in the range 1.05 GeV $≤ W ≤$ 4.00 GeV, where $W$ is the center-of-mass energy of the colliding photons, using 972 fb -1 of data collected with the Belle detector at the $KEKB$ asymmetric-energy $e^+ e^-$ collider operated at and near the $Υ$-resonance region. The differential cross section is fitted by parameterized S-, D 0 - , D 2 - , G 0 - and G 2 -wave amplitudes. In the D 2 wave, the $f_2$(1270), $a_2$(1320) and $f^\prime_2$(1525) are dominant and a resonance, the $f_2$(2200), is also present. The $f_0$(1710) and possibly the $f_0$(2500) are seen in the $S$ wave. The mass, total width and product of the two-photon partial decay width and decay branching fraction to the $K\overline{K}$ state $Γ_{γγ}(ΒK\overline{K})$ are extracted for the $f^\prime_2$(1525), $f_0$(1710), $f_2$(2200) and $f_0$(2500). The destructive interference between the $f_2$(1270) and $a_2$(1320) is confirmed by measuring their relative phase. The parameters of the charmonium states $Χ_{c0}$ and $Χ_{c2}$ are updated. Possible contributions from the $Χ_{c0}(2P)$ and $Χ_{c2}(2P)$ states are discussed. A new upper limit for the branching fraction of the $P-$ and $CP-$violating decay channel $η_c → K^0_S K^0_S$ is reported. The detailed behavior of the cross section is updated and compared with $QCD$-based calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2015

Physics potential of a long-baseline neutrino oscillation experiment using a J-PARC neutrino beam and Hyper-Kamiokande

Hyper-Kamiokande will be a next generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande. One of the main goals of Hyper-Kamiokande is the study of CP asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams. In this paper, the physics potential of a long baseline neutrino experiment using the Hyper-Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented. The analysis uses the framework and systematic uncertainties derived from the ongoing T2K experiment. With a total exposure of 7.5 MW × 107 sec integrated proton beam power (corresponding to 1.56×1022 protons on target with a 30 GeV proton beam) to a 2.5-degree off-axis neutrino beam, it is expected that the leptonic CP phase δCP can be determined to better than 19 degrees for all possible values of δCP, and CP violation can be established with a statistical significance of more than 3σ (5σ) for 76% (58%) of the δCP parameter space. Using both νe appearance and νμ disappearance data, the expected 1σ uncertainty of sin2θ23 is 0.015(0.006) for sin2θ23=0.5(0.45).

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

Long-lived neutral-kaon flux measurement for the KOTO experiment

The KOTO(K 0 at Tokai) experiment aims to observe the CP-violating rare decay K L → π 0 νν¯ over bar by using a long-lived neutral-kaon beam produced by the 30 GeV proton beam at the Japan Proton Accelerator Research Complex. The K L flux is an essential parameter for the measurement of the branching fraction. Three K L neutral decay modes, K L → 3 π 0 , K L → 2 π 0 , and K L → 2γ, were used to measure the K L flux in the beam line in the 2013 KOTO engineering run. A Monte Carlo simulation was used to estimate the detector acceptance for these decays. Agreement was found between the simulation model and the experimental data, and the remaining systematic uncertainty was estimated at the 1.4% level. Here, the K L flux was measured as (4.183 ± 0.017 stat. ± 0.059 sys. ) x 10 7 K L per 2 x 10 14 protons on a 66-mm-long Au target.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2026

Mesogenesis through the ephemeral dark decay of Beauty

Mesogenesis provides a path for generating the baryon asymmetry of the Universe, using only the CP violation furnished by the Standard Model in the decay of B mesons. While this is an intriguing possibility, it is largely constrained by the data on B meson branching fractions into baryons and missing energy carried into the dark sector. We point out that it is possible to make this branching fraction dominant only in the early Universe, through an ultralight scalar coupled to the dark sector and the Standard Model leptons. A scenario is examined where the thermal density of muons in the early Universe temporarily lowers the mass of a dark fermion, allowing for efficient B meson decays. This `dark’ decay channel is shut off later when the muon number density falls, making the scenario compatible with flavor data. Our model can be consistent with the LHC constraints on color-charged heavy bosons required to implement Mesogenesis; such states may be discovered in the future runs as their masses cannot be far above the current bounds. We also outline other possible signals, which can arise in future displaced vertex searches, long range force searches, and observations of neutron star binary mergers.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

First measurement of the Ti ( e , e ' ) X cross section at Jefferson Lab

To probe CP violation in the leptonic sector using GeV energy neutrino beams in current and future experiments using argon detectors, precise models of the complex underlying neutrino and antineutrino interactions are needed. The E12-14-012 experiment at Jefferson Lab Hall A was designed to perform a combined analysis of inclusive and exclusive electron scatterings on both argon (N = 22) and titanium (Z = 22) nuclei using GeV-energy electron beams. The measurement on titanium nucleus provides essential information to understand the neutrino scattering on argon, large contribution to which comes from scattering off neutrons. Here we report the first experimental study of electron-titanium scattering as double-differential cross section at beam energy E = 2.222 GeV and electron-scattering angle θ = 15.541°, measured over a broad range of energy transfer, spanning the kinematical regions in which quasielastic scattering and delta production are the dominant reaction mechanisms. In conclusion, the data provide valuable new information needed to develop accurate theoretical models of the electromagnetic and weak cross sections of these complex nuclei in the kinematic regime of interest to neutrino experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2020

Higgs troika for baryon asymmetry

To explain the baryon asymmetry of the Universe, we extend the Standard Model (SM) with two additional Higgs doublets with small vacuum expectation values. The additional Higgs fields interact with SM fermions through complex Yukawa couplings, leading to new sources of $CP$ violation. We propose a simple flavor model with $\mathcal{O}$(1) or less Yukawa couplings for quarks and charged leptons, consistent with current flavor constraints. To generate neutrino masses and the baryon asymmetry, right-handed neutrinos in the ~ 0.1 - 10 TeV range couple to the "Higgs Troika." The new Higgs doublet masses are at or above the TeV scale, allowing for asymmetric decays into SM lepton doublets and right-handed neutrinos. The asymmetry in lepton doublets is then processed into a baryon asymmetry, similar to leptogenesis. Since the masses of the new fields could be near the TeV scale, there is potentially a rich high energy collider phenomenology, including observable deviations in the 125 GeV Higgs decay into muons and taus, as well as detectable low energy signals such as the electron EDM or $µ → eγ$. Hence, this is in principle a testable model for generation of baryon asymmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Leptonic unitarity triangles

We present a comprehensive analysis of leptonic unitarity triangles, using both current neutrino oscillation data and projections of next-generation oscillation measurements. Future experiments, sensitive to the degree of CP violation in the lepton sector, will enable the construction of precise triangles. We show how unitarity violation could manifest in the triangles and discuss how they serve as unitarity tests. We also propose the use of Jarlskog factors as a complementary means of probing unitarity. This analysis highlights the importance of testing the unitarity of the leptonic mixing matrix, an understanding of which is crucial for deciphering the nature of the neutrino sector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2021

Interplay between the factorization of the Jarlskog invariant and location of the solar and atmospheric resonances for neutrino oscillations in matter

The Jarlskog invariant which controls the size of intrinsic CP violation in neutrino oscillation appearance experiments is modified by Wolfenstein matter effects for neutrinos propagating in matter. In this paper we give the exact factorization of the Jarlskog invariant in matter into the vacuum Jarlskog invariant times two, two-flavor matter resonance factors that control the matter effects for the solar and atmospheric resonances independently. We compare the location of the minima of the factorizing resonance factors with the location of the solar and atmospheric resonances, precisely defined. They are not identical but the fractional differences are both found to be less than 0.1%. In addition, we explain why symmetry polynomials of the square of the mass of the neutrino eigenvalues in matter, such as inverse of the square of the Jarlskog invariant in matter, can be given as polynomials in the matter potential.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Novel method for the identification of the production flavor of neutral charmed mesons

We propose a new algorithm for the identification of the production flavor of neutral D mesons in the Belle II experiment. The algorithm exploits the correlation between the flavor of a reconstructed neutral D meson (signal D meson) and the electric charges of particles reconstructed in the rest of the e + e – →$c\bar{c}$ event. These include those originating from the decay of the other charm hadron produced in the event, as well as those possibly produced in association with the signal D meson. We develop the algorithm using simulation and calibrate it in data using decay modes that identify the flavor of the decaying neutral D meson. We use a data sample of e + e – collisions, corresponding to 362 fb –1 of integrated luminosity, collected by Belle II at center-of-mass energies near the Υ(4S) mass. The effective tagging efficiency in data is (47.91±0.07 (stat) ±0.51 (syst)) %, independent of the neutral-D-meson decay mode. This charm flavor tagger will approximately double the effective sample size of many CP-violation and charm-mixing measurements that so far have exclusively relied on neutral D mesons originating from D* ± decays. While developed for Belle II, the basic principles underlying the charm flavor tagger can be used in other experiments, including those at hadron colliders.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗