Search prospects for axionlike particles at rare nuclear isotope accelerator facilities
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
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Light new physics in B → K ( * ) ν ν ¯ ?
The study of the rare decays B → K ( * ) ν ν ¯ offers a window into the dynamics operating at the electroweak scale, allowing studies of the Standard Model and searches for heavy new physics. However, the analysis of these decays is also potentially sensitive to the on shell production of new light bosons X through the process B → K ( * ) X . In particular, Belle II has recently measured B + → K + ν ν ¯ , finding a 2.8 σ excess under the assumption of heavy new physics. Since this excess is rather localized in the kaon energy, a fit that includes the decay mode B + → K + X to the kinematic distributions prefers m X ≈ 2 GeV with branching fraction Br [ B → K X ] = ( 8.8 ± 2.5 ) × 10 − 6 and a significance of ≈ 3.6 σ . However, no excess was found in the measurements of B → K ( * ) ν ν ¯ , and a global analysis of the Belle II and data leads to Br [ B → K X ] = ( 5.1 ± 2.1 ) × 10 − 6 with a reduced significance of ≈ 2.4 σ . We then study various simplified dark-flavored models and present a possible UV completion based on a gauged B 3 − L 3 symmetry, highlighting the discovery potential of dedicated searches for B → K ( * ) X at Belle II. Published by the American Physical Society 2024
Astronomy & Astrophysics↗
Anomalous interactions between mesons with nonzero spin and glueballs
Topologically nontrivial fluctuations control the anomalous interactions for the η and η ′ pseudoscalar mesons. We consider the anomalous interactions for mesons with higher spin, the heterochiral nonets with J P C = 1 + − and 2 − + . Under the approximation of a dilute gas of instantons, the mixing angle between nonstrange and strange mesons decreases strongly as J increases, and oscillates in sign. Anomalous interactions also open up new, rare decay channels. For glueballs, anomalous interactions indicate that the X ( 2600 ) state is primarily gluonic. Published by the American Physical Society 2024
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Data-driven background model for the CUORE experiment
Here, we present the model we developed to reconstruct the CUORE radioactive background based on the analysis of an experimental exposure of 1038.4 kg yr. The data reconstruction relies on a simultaneous Bayesian fit applied to energy spectra over a broad energy range. The high granularity of the CUORE detector, together with the large exposure and extended stable operations, allow for an in-depth exploration of both spatial and time dependence of backgrounds. We achieve high sensitivity to both bulk and surface activities of the materials of the setup, detecting levels as low as 10 nBq kg −1 and 0.1 nBq cm −2 , respectively. We compare the contamination levels we extract from the background model with prior radio-assay data, which informs future background risk mitigation strategies. The results of this background model play a crucial role in constructing the background budget for the CUPID experiment as it will exploit the same CUORE infrastructure.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for B + → K + ν ν ¯ Decays Using an Inclusive Tagging Method at Belle II
Not Available
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Observation of the Singly Cabibbo Suppressed Decay Λ c + → n π +
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First Measurement of the B + → π + π 0 π 0 Branching Fraction and C P Asymmetry
We study B + → π + π 0 π 0 using 711 fb -1 of data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. Here we measure an inclusive branching fraction of (19.0 ±1.5 ±1.4)×10 -6 and an inclusive CP asymmetry of (9.2 ±6.8 ±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B + → ρ(770) + π 0 branching fraction of (11.2 ± 1.1 ± 0.9 $^{+0.8}_{-1.6}$)× 10 -6 , where the third uncertainty is due to possible interference with B + → ρ(1450) + π 0 . We present the first observation of a structure around 1 GeV/c 2 in the π 0 π 0 mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9 ±0.9 ±0.6) × 10 -6 . We also report a measurement of local CP asymmetry in this structure.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for Rare b → d ℓ + ℓ − Transitions at Belle
We present the results of a search for the b → d ℓ + ℓ − flavor-changing neutral-current rare decays B + , 0 → ( η , ω , π + , 0 , ρ + , 0 ) e + e − and B + , 0 → ( η , ω , π 0 , ρ + ) μ + μ − using a 711 fb − 1 data sample that contains 772 × 10 6 B B ¯ events. The data were collected at the ϒ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. We find no evidence for signal and set upper limits on branching fractions at the 90% confidence level in the range ( 3.8 – 47 ) × 10 − 8 depending on the decay channel. The obtained limits are the world’s best results. This is the first search for the channels B + , 0 → ( ω , ρ + , 0 ) e + e − and B + , 0 → ( ω , ρ + ) μ + μ − . Published by the American Physical Society 2024
Physics↗
Search for the 𝐾 𝐿 → 𝜋 0 $𝜈\bar{𝜈}$ Decay at the J-PARC KOTO Experiment
We performed a search for the 𝐾 𝐿 → 𝜋 0 $𝜈\bar{𝜈}$ decay using the data taken in 2021 at the J-PARC KOTO experiment. With newly installed counters and new analysis method, the expected background was suppressed to 0.252 ± 0.055 stat $^{+0.052}_{{−0.067^{syst}}}$. With a single event sensitivity of (9.33 ± 0.06 stat ±0.84 syst ) × 10 −10 , no events were observed in the signal region. An upper limit on the branching fraction for the decay was set to be 2.2 ×10 −9 at the 90% confidence level (C.L.), which improved the previous upper limit from KOTO by a factor of 1.4. With the same data, a search for 𝐾 𝐿 → 𝜋 0 𝑋 0 was also performed, where 𝑋 0 is an invisible boson with a mass ranging from 1 to 260 MeV/𝑐 2 . For 𝑋 0 with a mass of 135 MeV/𝑐 2 , an upper limit on the branching fraction of 𝐾 𝐿 → 𝜋 0 𝑋 0 was set to be 1.6 ×10 −9 at the 90% C.L.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Enhanced sensitivity to trace 238 U impurity of sapphire via coincidence neutron activation analysis
Sapphire has mechanical and electrical properties that are advantageous for the construction of internal components of radiation detectors such as time projection chambers and bolometers. However, it has proved difficult to assess its 232 Th and 238 U content down to the picogram per gram level. Here, this work reports an experimental verification of a computational study that demonstrates 𝛾𝛾 coincidence counting, coupled with neutron activation analysis (NAA), can reach ppt sensitivities. Combining results from 𝛾𝛾 coincidence counting with those of earlier single-𝛾 counting based NAA shows that a sample of Saint Gobain sapphire has 232 Th and 238 U concentrations of <0.26 ppt and <2.3 ppt, respectively; the best constraints on the radiopurity of sapphire.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Charm physics
Abstract We review recent developments in charm physics, focusing on the physics of charmed mesons. We discuss recent progress in charm spectroscopy and the multitude of mesonic and baryonic exotic states containing charm quarks. We review searches for new physics with charmed mesons with rare decays. We also touch upon recent theoretical and experimental progress in searches for CP-violation in charm decays and the status of $$D^0-\overline{D}{}^0$$ D 0 - D ¯ 0 mixing.
Physics↗
JLab eta Factory Experiment in Hall D
The new experiment, JLab Eta Factory (JEF), in the experimental Hall-D at Jefferson Lab will extend the physics potential of the GlueX beyond the main spectroscopy program and study rare decays of eta mesons. Among various physics topics, the experiment will focus on decays of eta mesons to the eta -> pi0 gamma gamma final state. This decay mode provides an important information for higher-order calculations in chiral perturbation theory. The final state is ideal for the search of the leptophobic dark B-boson in the reactions eta -> B gamma, B -> pi0 gamma; and the scaler dark matter mediator S in the channel eta -> pi0 S, S -> gamma gamma. The experiment requires to upgrade the inner part of the forward lead glass calorimeter of the GlueX detector with high-granularity, high-resolution lead tungstate PbWO4 scintillating crystals. The detector will be ready to take data in 2023. I will give an overview of the JEF project.
Somov, Alexander↗
RF Technologies for Future Colliders
Particle colliders remain indispensable scientific instruments to discover and study new elementary particles and fundamental forces of nature. Whether the collider is a factory (used to improve precision of measuring properties of already discovered particles or to enable studies of rare decay channels), an energy frontier machine (aimed at discovering new particles and forces), a heavy ion collider (allowing studies of what the universe looked like in the early moments after its creation), or an electron-hadron collider (where electrons are used for probing heavy ions or protons to study the fundamental force binding all visible matter), the radio frequency technologies play a key role in enabling the machine to reach its goals. This article considers challenges presented to the radio frequency technologies by the next generation of particle colliders and reviews R&D approaches and directions to address these challenges.
43 PARTICLE ACCELERATORS↗
The Future Circular Collider: a Summary for the US 2021 Snowmass Process
In this white paper for the 2021 Snowmass process, we give a description of the proposed Future Circular Collider (FCC) project and its physics program. The paper summarizes and updates the discussion submitted to the European Strategy on Particle Physics. After construction of an approximately 90 km tunnel, an electron-positron collider based on established technologies allows world-record instantaneous luminosities at center-of-mass energies from the Z resonance up to tt thresholds, enabling a rich set of fundamental measurements including Higgs couplings determinations at the sub percent level, precision tests of the weak and strong forces, and searches for new particles, including dark matter, both directly and via virtual corrections or mixing. Among other possibilities, the FCC-ee will be able to (i) indirectly discover new particles coupling to the Higgs and/or electroweak bosons up to scales around 7 and 50 TeV, respectively; (ii) perform competitive SUSY tests at the loop level in regions not accessible at the LHC; (iii) study heavy-flavor and tau physics in ultra-rare decays beyond the LHC reach, and (iv) achieve the best potential in direct collider searches for dark matter, sterile neutrinos, and axion-like particles with masses up to around 90 GeV. The tunnel can then be reused for a proton-proton collider, establishing record center-of-mass collision energy, allowing unprecedented reach for direct searches for new particles up to the around 50 TeV scale, and a diverse program of measurements of the Standard Model and Higgs boson, including a precision measurement of the Higgs self-coupling, and conclusively testing weakly-interacting massive particle scenarios of thermal relic dark matter.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
IRIS-HEP Strategic Plan for the Next Phase of Software Upgrades for HL-LHC Physics
The quest to understand the fundamental building blocks of nature and their interactions is one of the oldest and most ambitious of human scientific endeavors. CERN's Large Hadron Collider (LHC) represents a huge step forward in this quest. The discovery of the Higgs boson, the observation of exceedingly rare decays of $B$ mesons, and stringent constraints on many viable theories of physics beyond the Standard Model (SM) demonstrate the great scientific value of the LHC physics program. The next phase of this global scientific project will be the High-Luminosity LHC (HL-LHC) which will collect data starting circa 2029 and continue through the 2030s. The primary science goal is to search for physics beyond the SM and, should it be discovered, to study its implications. In the HL-LHC era, the ATLAS and CMS experiments will record around 100 times as many collisions as were used to discover the Higgs boson (and at twice the energy). Both NSF and DOE are making large detector upgrade investments so the HL-LHC can operate in this high-rate environment. Similar investment in software R&D for acquiring, managing, processing and analyzing HL-LHC data is critical to maximize the return-on-investment in the upgraded accelerator and detectors. This report presents a strategic plan for a possible second 5-year funded phase (2023 through 2028) for the Institute for Research and Innovation in Software for High Energy Physics (IRIS-HEP) which will close remaining software and computing gaps to deliver HL-LHC science.
43 PARTICLE ACCELERATORS↗
Measurement of the Muon Flux at the Sanford Underground Research Facility with the LUX-ZEPLIN Dark Matter Detector
High-energy cosmic-ray muons reaching deep underground laboratories can cause events in detectors that mimic signals expected from dark matter particles, neutrinos, or rare decays. Knowledge of the muon flux and energy spectrum is important for evaluating the background rate caused by muons and their secondaries. In this paper, we report the measurement of the cosmic-ray muon flux in the Davis Campus of the Sanford Underground Research Facility with the LUX-ZEPLIN detector. Using 366.4~days of exposure, the muon rate through the detector was measured as $10.94\pm0.17_\textrm{stat.}~\textrm{day}^{-1}$ with energy thresholds of 20~MeV in the inner xenon detector and 8 MeV in the outer liquid scintillator detector. This rate corresponds to a muon flux of $(5.09\pm0.08_\textrm{stat.}\pm0.10_\textrm{sys.})\times10^{-9}~\textrm{cm}^{-2}\textrm{s}^{-1}$ in the Davis Cavern.
Akerib, D. S. [SLAC; Stanford U., Phys. Dept.; KIP↗
Search for rare 3-$α$ decays in the region of the Hoyle state of 12 C
We performed a refined analysis of the data collected with the CHIMERA detector with the aim of searching rare 3-$α$ decay modes near the Hoyle state of 12 C. In particular we investigated the direct and sequential decay modes of the Hoyle state including also the recently suggested Efimov state. The comparison of selected events with simulations constrains the precision achievable with measurements in different experimental conditions. We observe good sensitivities to different decay scenarios also in the CHIMERA spherical region notwithstanding its limited angular resolution. Furthermore, the search for the decay of the Efimov state in 12 C was performed by using new selection strategies as suggested by simulations. The obtained results are not conclusive, however, we are able to exclude the presence of a sequential decay of this state, while our data could be compatible with its direct decay.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Two-loop radiative jet function for exclusive B-meson and Higgs decays
The rare radiative B -meson decay \( {B}^{-}\to \gamma {\mathrm{\ell}}^{-}\overline{v} \) and the radiative Higgs-boson decay h → γγ mediated by light-quark loops both receive large logarithmic corrections in QCD, which can be resummed using factorization theorems derived in soft-collinear effective theory. In these factorization theorems the same radiative jet function appears, which is a central object in the study of factorization beyond the leading order in scale ratios. We calculate this function at two-loop order both in momentum space and in a dual space, where its renormalization-group evolution takes on a simpler form. We also derive the two-loop anomalous dimension of the jet function and present the exact solution to its evolution equation at two-loop order. Another important outcome of our analysis is the explicit form of the two-loop anomalous dimension of the B -meson light-cone distribution amplitude in momentum space.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗