High Energy Physics - Experiment
See recent articles · View on arXiv
Showing new listings for Friday, 11 September 2026
New submissions (showing 4 entries)
- [1] arXiv:2609.10804 [pdf, other]
- Title: The NOvA Test Beam ExperimentSubjects: High Energy Physics - Experiment (hep-ex)
NOvA is a long-baseline neutrino oscillation experiment designed to study the neutrino mixing parameters, mass ordering, and CP violation in the lepton sector. A key component of the success of the experiment is a robust understanding of the systematic uncertainties associated with detector response and calibration. To address this, NOvA deployed a Test Beam experiment at the Fermilab Test Beam Facility, which collected data from April 2019 through July 2022. The NOvA Test Beam experiment used a 30-ton segmented liquid scintillator detector functionally identical to the NOvA Near and Far Detectors to analyze tagged particles produced from p-Cu collisions, with instrumentation capable of selecting and identifying electrons, muons, pions, kaons, and protons with momentum ranging from 0.4-1.5GeV/c. Analysis of the collected data provides a better understanding of the largest systematic uncertainties impacting NOvA's analyses, which include the detector response, energy calibration, and hadronic and electromagnetic energy resolutions.
- [2] arXiv:2609.10963 [pdf, other]
- Title: Production of Light Nuclei and Hypernuclei in Heavy-Ion CollisionsComments: SQM2026 proceedingsSubjects: High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
We review recent STAR and ALICE measurements of light-nucleus and hypernucleus yields, femtoscopic correlations, and collective flow presented at SQM 2026. Statistical-hadronization calculations provide a useful baseline for integrated yields but do not simultaneously describe all measured light-nucleus ratios across collision energies and system sizes. For bound states with mass number , current coalescence calculations provide a broadly consistent description of yields, femtoscopic correlations, and collective flow, although the quantitative hypertriton comparison depends on the assumed few-body wave function. The suppressed production of resonant Li relative to compact He indicates an effect of nuclear structure and late-stage dynamics. However, the quantitative model comparison also depends on the treatment of feed-down from unstable states. In high-multiplicity + collisions, pion-deuteron femtoscopy further indicates that most observed (anti)deuterons are formed through nucleon fusion after strong decays of short-lived resonances. Taken together, these measurements show that production chronology and internal nuclear structure leave measurable imprints on the physics observables.
- [3] arXiv:2609.11057 [pdf, other]
- Title: Search for the process at the SND detectorComments: 15 pages, 5 figuresSubjects: High Energy Physics - Experiment (hep-ex)
In the experiment with the SND detector at the VEPP-2000 collider, a search is performed for the direct production of the -even resonance in collisions. The analysis is based on data with an integrated luminosity of about 200 pb, accumulated in the center-of-mass energy range of 1.14--1.46 GeV, of which about 72 pb were recorded near the maximum of the resonance. The production cross section at the resonance maximum pb and the branching fraction have been measured. The significance of the observation of the process is . Since the significance is low, we also present the upper limits at the 90% confidence level: and .
- [4] arXiv:2609.11617 [pdf, other]
- Title: Projected Sensitivity to Slow Muonphilic Dark Matter with Accelerator Muon BeamsComments: 6 pages, 6 figuresSubjects: High Energy Physics - Experiment (hep-ex)
The nature of dark matter (DM) remains one of the most enduring open questions in modern physics, and muonphilic DM has emerged as a promising scenario that complements traditional DM candidates. Following the recently established cosmic-ray muon scattering approach, we investigate the sensitivity for probing slow muonphilic DM with accelerator muon beams. A Geant4-based simulation framework is developed, incorporating the detector geometry from the PKMu muon tomography system and a dedicated elastic -DM scattering process. The projected sensitivity is found to be largely insensitive to both the beam energy and the transverse beam size when the beam is fully contained within the detector acceptance. For a benchmark beam intensity of , the simulated pure-muon beam surpasses the existing cosmic-ray limit of cm at GeV within approximately 11 seconds. A realistic muon beam phase-space distribution based on simulations for the High Intensity heavy-ion Accelerator Facility (HIAF) is also implemented, yielding projected limits that improve upon the cosmic-ray results by nearly two orders of magnitude in a one-day exposure. These results demonstrate that a beam-muon scattering experiment offers a robust and promising route toward significantly improved sensitivity to slow muonphilic DM.
Cross submissions (showing 13 entries)
- [5] arXiv:2609.10491 [pdf, other]
- Title: Inelastic Dark Matter and High-Energy Recoil Signatures in LZSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
We study the inelastic dark matter (iDM) that consists of two-component dark matter particles and serves as a minimal extension beyond the commonly used one-component DM models. A distinctive feature of such iDM scattering with the target nuclei is to favorably produce signals at high nuclear recoil (NR) energy region in both exothermic and endothermic processes. In particular, for the exothermic dark matter scenario, the signal does not rely on the tail of the Boltzmann velocity distribution. As a result, the required DM-nucleus scattering cross section is significantly reduced, which in turn helps to substantially relax the stringent constraints imposed by IceCube neutrino searches. Using the inelastic DM-nucleus scattering, we naturally explain the newly reported event excess at high recoil energy with the LUX-ZEPLIN (LZ) experiment.
- [6] arXiv:2609.10668 [pdf, other]
- Title: The Dark Dimension and Majorana NeutrinosComments: 11+9 pages, 7 Figures, 1 TableSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Theory (hep-th)
Recent developments in the Swampland program motivate the existence of a mesoscopic Dark Dimension of size m with bulk Majorana fermions in the keV range. Motivated by this, we derive terrestrial constraints on Majorana bulk neutrinos as a function of the compactification radius. After determining the mass spectrum and mixing structure, we confront the model with Daya Bay neutrino-oscillation data, the KATRIN beta-decay bound, and the KamLAND-Zen neutrinoless double beta decay limit. For the latter, we obtain a closed-form expression for the effective Majorana mass and show that the Kaluza-Klein tower efficiently screens neutrinoless double beta decay when the nuclear momentum exceeds the compactification and Majorana scales. In the Dark-Dimension window, beta decay provides the strongest constraint, pushing the allowed Yukawa couplings down to . Oscillation and neutrinoless double beta decay searches remain complementary, probing smaller and larger Majorana masses, respectively. For completeness, outside the Dark-Dimension assumptions, we investigate how hierarchical Majorana masses can weaken the constraints.
- [7] arXiv:2609.10784 [pdf, other]
- Title: Low-Mass Magnetic Monopoles in the Galaxy: Simulations and Comparison with Ultra-High-Energy Cosmic-Ray DataComments: 32 pages, 19 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
Origin and composition of ultra-high energy cosmic rays are still uncertain, particularly the rare events exceeding the Greisen-Zatsepin-Kuzmin cutoff and whose apparent arrival directions point to the Local Void. This work is an in-depth investigation of the possibility that such cosmic rays contain low-mass magnetic monopoles predicted in several recent theoretical models. Using a custom extension to CRPropa, a state-of-the-art code for modeling cosmic ray propagation, monopoles are tracked in the galactic environment under realistic assumptions on mass, magnetic charge, and initial phase-space distributions. Our simulations demonstrate that relic MMs follow filamentary ``Galactic magnetic funnels'', producing anisotropic arrival directions at Earth. The expected arrival directions are concentrated in a small region of the sky, which has significant implications for the design and interpretation of future searches. A comparison of the simulated arrival directions with the Pierre Auger Observatory dataset shows that the null hypothesis - no monopole contribution - is statistically preferred for the majority of cases. Using a profile-likelihood analysis that incorporates both directional and energy information, we set 90% C.L. upper limits on the integral MM flux of .
- [8] arXiv:2609.10827 [pdf, other]
- Title: Generalized Chiral with Inelastic Scalar Dark Matter for the LZ 248 keV EventComments: 11 pages, 1 figure, 1 table. Comments are welcome!Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
The high-energy nuclear recoil event with keV recently reported by the LZ collaboration, with a background-only significance of , offers an intriguing window into dark matter scattering beyond the conventional elastic picture. We study an inelastic scalar dark matter scenario within a generalized chiral framework. After symmetry breaking, the dark sector scalar gives rise to two nearly degenerate states with a small mass splitting. The lighter state serves as the dark matter candidate and couples off-diagonally to the boson, leading to endothermic inelastic scattering. The resulting kinematics suppress the contribution from low-velocity dark matter while making the high-velocity tail increasingly relevant for nuclear recoils at higher energies. We identify the parameter space consistent with the observed relic abundance and current experimental constraints, and discuss the inelastic scattering kinematics relevant to the recent LZ observation, together with the complementary collider prospects for the associated boson.
- [9] arXiv:2609.10891 [pdf, other]
- Title: Mitigating Sensor Cracking using the Interposer Strategy in the ATLAS ITk Strip DetectorComments: 39 pages in total, author list starting page 35, 24 figures, 2 tablesSubjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)
This paper introduces the strategy of using an interposing layer to mitigate thermal-stress-induced fracturing of silicon sensors in ATLAS ITk Strip modules. This strategy involves a change in the module design in which layers of soft adhesive and a kapton separator, known as an interposer, are added to the module stack-up to decouple thermal stresses. This paper discusses the interposer design and its implementation in the ATLAS ITk Strip barrel, including material tests to validate the additional components, the development of new processes to integrate the new layers into the module assembly workflow, results from design validation and quality control testing of prototype interposed modules, and studies indicating that the new design significantly reduces the thermal stress experienced by the sensor. Tests of prototype support structures loaded with interposed modules have shown no sensor fractures in the relevant temperature range for operation in ATLAS, resulting in the adoption of the interposer strategy as the primary sensor cracking mitigation in the ATLAS ITk Strip barrel.
- [10] arXiv:2609.10903 [pdf, other]
- Title: Unitarity dressing of the dynamical gluon mass scaleComments: 8 pages, 4 figures, 2 tablesSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat); High Energy Physics - Theory (hep-th)
We study the effect of -channel unitarity on the dynamical gluon mass scale, , extracted from high-energy elastic scattering. The elementary input is a Reggeized Landshoff--Nachtmann two-gluon exchange, in which the soft Pomeron is represented by a color-singlet pair of dynamically massive gluons. At Born level, the logarithmic and power-law mass solutions give --, in the usual phenomenological range. When the same input is embedded in the eikonal and -matrix schemes, the preferred values move to --. The enhancement, by a factor close to , is stable against the ATLAS--TOTEM data choice, the running of the gluon mass, and the unitarization prescription. We trace this shift to the nonlinear mapping between the elementary two-gluon kernel and the physical impact-parameter profile. The scale inferred from elastic scattering is therefore a unitarity-dressed infrared scale, fixed jointly by the nonperturbative gluon propagator and by multiple-exchange dynamics.
- [11] arXiv:2609.11026 [pdf, other]
- Title: Properties of the positive and negative parity charm-strange and bottom-strange mesons , , , , , , , from lattice QCD: masses, decay constants, and compositenessComments: 72 pages, 53 figuresSubjects: High Energy Physics - Lattice (hep-lat); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)
We present a lattice-QCD determination of properties of the lightest scalar, pseudoscalar, vector, and axial-vector heavy-strange mesons. This includes the decay constants of all mesons, and the binding energies and Weinberg compositeness parameters of the positive-parity states. The calculations are performed with domain-wall fermions for the light and strange quarks and anisotropic clover actions for the charm and bottom quarks. We use seven ensembles generated by RBC/UKQCD with pion masses ranging from 431 MeV to 139 MeV and lattice spacings ranging from 0.114 fm to 0.073 fm, which allows us to perform combined chiral and continuum extrapolations. For the negative-parity mesons, we obtain , , , , , and . In the positive-parity sector, the finite-volume energies and decay constants are extracted using the GEVP from correlation matrices with three different types of hadron interpolating operators, including operators with covariant derivatives and meson-meson-scattering operators at both source and sink. After extrapolation to the physical point, we obtain MeV, MeV, MeV, and MeV. Our results for and are the first from lattice QCD. Lüscher's method is used to find the infinite-volume bound-state masses. At the physical point, we obtain MeV, MeV, MeV, and MeV. Our analysis shows consistency with the positive-parity states being predominantly molecular.
- [12] arXiv:2609.11151 [pdf, other]
- Title: Qubit-Qutrit Quantum Tomography of hadronic and systemsComments: A short letter with 4 pages, two figures, one table, and an AppendixSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
Quantum-information observables have emerged in recent years as new tools in nuclear and particle physics, from entanglement in top-quark pairs to spin correlations in production. Extending these studies to unequal-spin hadronic final states poses a fundamental challenge: the density matrix of a qubit-qutrit system contains 35 independent spin parameters, but the decays of pairs, with or , provide access to only 23 due to the hidden vector polarization from the strong decay. In this Letter, we formulate a qubit-qutrit quantum tomography (QQQT) technique for these spin- systems and establish exact criteria for entanglement certification from the \textit{incomplete} density matrix. Compared with the system, QQQT of and provides a new probe of nonperturbative QCD hadronization, enabling a direct comparison of the spin evolution of entangled quark pairs produced from the vacuum as they hadronize into a baryon or a vector meson.
- [13] arXiv:2609.11196 [pdf, other]
- Title: Doubling down on proton structure: what double parton scattering can and cannot tell us about partonic separationSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
Double parton scattering provides a unique probe of proton structure and is commonly characterized by the effective cross section . We examine, under the factorized ansatz for the double-parton-scattering cross section and without assuming any specific parametric form for the transverse profile, what the effective cross section can reveal about the transverse separation, , between partons in the proton. We derive a sharp lower bound on the transverse partonic separation, , and demonstrate through explicit counterexamples that previously posited upper bounds do not hold. Our results establish, within the effective-cross-section parametrization of double parton scattering framework, that can provide a sharp lower bound on partonic separation but cannot provide a general upper bound.
- [14] arXiv:2609.11461 [pdf, other]
- Title: Combinations of measurements that are simultaneous fits of parameters of interest and systematic uncertainties using the BLUE methodComments: 13 pages, 5 figures, 4 tables, submitted to EPJCSubjects: Data Analysis, Statistics and Probability (physics.data-an); High Energy Physics - Experiment (hep-ex)
Combining estimates of the same physics parameter obtained from different measurements improves the precision and robustness of the parameter determination. Modern particle physics measurements are often performed using likelihood fits that include the physics parameter(s) of interest together with nuisance parameters representing systematic uncertainties. In high-statistics analyses, typical of many analyses at the Large Hadron Collider, these nuisance parameters can be constrained in the likelihood fits. We describe how the Best Linear Unbiased Estimator method for combinations can be applied to both the estimates of the parameters of interest and the estimates of the nuisance parameters. We show with concrete example combinations that including the nuisance parameters can improve the precision on the parameters of interest. We show with pseudo-experiments that the uncertainty reported by the combination is reliable and that the approximate likelihood combination proposed in a previous publication and implemented in the Convino software reports an underestimated uncertainty. The method is implemented in an open-source software tool, Combiner.
- [15] arXiv:2609.11604 [pdf, other]
- Title: Collinear fragmentation of pseudoscalar quarkonia from NLO NRQCDComments: 7 pages, 2 figures. Proceedings of the 33rd International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2026), 4-8 May 2026, Bologna, ItalySubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
We discuss a new family of publicly available collinear fragmentation functions (FFs) for pseudoscalar quarkonia, the NRFF1.0 set. It builds upon the Heavy-Flavor Non-Relativistic evolution (HF-NRevo) scheme, designed to describe heavy-hadron formation through leading-power fragmentation at moderate and large transverse momentum. Heavy-quarkonium production naturally involves both perturbative and non-perturbative QCD dynamics, from the production of the heavy pair to its formation into a physical bound state. Within NRFF1.0, Non-Relativistic Quantum Chromodynamics (NRQCD) provides the theoretical framework for calculating the FF inputs at the initial scale, which are subsequently evolved through the HF-NRevo scheme. This setup provides a precision baseline for investigating the underlying partonic hierarchy and jet structure across the moderate- to high-transverse-momentum regime. The explicit treatment of partonic channels and heavy-flavor thresholds makes this framework particularly suitable for exploring quarkonium-in-jet fragmentation, jet-quenching sensitivity, energy-loss mechanisms, and the emergence of medium-modified fragmentation patterns in the quark-gluon plasma.
- [16] arXiv:2609.11683 [pdf, other]
- Title: Bayesian Superiority in On/Off analysisComments: 6 pages, 3 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)
We present a detailed comparison of Bayesian criteria with three non-informative priors - flat, Jeffreys, and scale-invariant - for testing a signal against an unknown background and compare them with the classical frequentist Li-Ma approach in the On/Off problem. We perform Monte Carlo simulations for various background levels and evaluate the Li-Ma and Bayesian criteria by their Type I error rates. We then simulate a nonzero signal and compare the criteria in terms of Type II error rates. We find that the Bayesian criterion with the Jeffreys prior yields lower Type I and Type II error rates than the Li-Ma criterion. In addition, we show that the Bayesian criteria are more robust than the Li-Ma criterion when the background distribution is overdispersed relative to the Poisson distribution.
- [17] arXiv:2609.11840 [pdf, other]
- Title: Signatures of Invisible Fermions in DecaysComments: 19 pages, 3 figures, and 2 tablesSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
We investigate the effects of a massive invisible fermion in decays using a model-independent weak effective theory. Through a comprehensive angular analysis, we show that a nonzero invisible-particle mass leaves characteristic imprints on angular observables that can distinguish massless and massive invisible states. We further demonstrate that these observables provide strong discrimination among vector/axial-vector, scalar/pseudoscalar, and tensor interactions, as well as between left- and right-handed quark and lepton current operators.
Replacement submissions (showing 7 entries)
- [18] arXiv:2608.09462 [pdf, other]
- Title: A Reusable Four-Port S-Parameter to Link-Level Signal-Integrity Analysis Framework for High-Speed Detector InterconnectsSubjects: High Energy Physics - Experiment (hep-ex); Systems and Control (eess.SY)
A reusable MATLAB signal-integrity (SI) framework is presented that converts compatible four-port S-parameter data, measured by VNA or obtained from electromagnetic simulation, into traceable link-level evidence rather than a single loss metric. Its contribution is the checked, traceable automation of established SI operations while keeping source data, model assumptions, analytical projections, and finite-record observations distinct. The framework is demonstrated on the four 1.25 Gbps differential routes (DP1-DP4) of the PPCB-1347-MuPix11 probe card using PTSL CST Microwave 3D-Solver-derived four-port S-parameters and a virtual time-domain solver. The automated pipeline preflights file structures, performs a power-normalized mixed-mode transformation, applies route-length-aware loss decomposition, constructs a causally loaded channel model, and propagates full PRBS-31 sequences into eye-diagram, conditional-BER, and 8b10b-coded-link analyses. At the 1.25 Gbps data rate (Nyquist 0.625 GHz), DP1-DP4 exhibit differential insertion loss (SDD21) from -0.350 to -0.300 dB, differential-to-common conversion from -31.038 to -28.236 dBc, and modeled FEB-input eye openings from 0.586 to 0.588 V. The comparison shows that path length alone is not an adequate SI ranking variable: DP3 has the lowest Nyquist insertion loss, DP1 the strongest differential-to-common isolation, and DP4 the largest modeled eye. All analytical BER values remain below the reporting floor and therefore do not support a BER ranking. By preserving the distinction between route-dependent waveform behavior, model projections, and finite-record observations, the framework provides an extensible basis for comparative high-speed-interconnect SI analysis from design review through calibrated VNA measurement interpretation.
- [19] arXiv:2609.05900 [pdf, other]
- Title: Prospective study of light dark matter search in positron beam mode with DarkSHINE experiment initiativeSubjects: High Energy Physics - Experiment (hep-ex)
We perform the prospective study on searching for invisibly decayed dark photons () in positron-on-fixed-target (POT) scheme with the DarkSHINE experiment simulation setup. In the positron-on-fixed-target scheme, two additional production channels of dark photons via annihilation with extranuclear electrons are present: non-resonant t-channel () and resonant s-channel (), alongside bremsstrahlung emission similar to electron-on-fixed-target scheme. Based on a Geant4 full detector simulation of an 8 GeV positron beam with POT events, we developed an analysis strategy using missing energy and momentum signatures across three orthogonal signal regions optimized for these channels. Our results indicate that the additional annihilation channels of dark photon production improve the dark photon invisible decay search sensitivity, improving the exclusion limits by approximately two orders of magnitude compared to existing constraints in the electron-on-fixed target (EOT) scheme, particularly near the center-of-mass energy threshold.
- [20] arXiv:2602.21181 [pdf, other]
- Title: CP Violation in Decays: A Comparative Analysis of Triplet and Sextet DiquarksComments: 19 pages, 2 figuresJournal-ref: Phys. Rev. D 114,035037 (2026)Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
Recent measurements of the CP asymmetry in the decay by the CMS collaboration, , and by LHCb, , suggest possible deviations from Standard Model (SM) expectations, which predict asymmetries below the percent level. This singly Cabibbo-suppressed decay is particularly sensitive to new physics, as the leading amplitudes vanish in the exact U-spin symmetry limit and the process is dominated by W-exchange topologies. We investigate scalar diquark contributions to this decay, comparing color-sextet and color-triplet representations. We find that the color-sextet diquark, characterized by a symmetric color structure , avoids color suppression and can generate CP asymmetries in the range -- for a diquark mass of order 1~TeV. In contrast, the color-triplet contribution is strongly suppressed due to destructive interference from its antisymmetric color structure. We further show that a flavor hierarchy in the sextet couplings, with , can simultaneously account for the observed deviation from the U-spin sum rule in and and the measured CP asymmetry in . These results identify color-sextet scalar diquarks as viable candidates for explaining enhanced CP violation in charm decays.
- [21] arXiv:2604.02825 [pdf, other]
- Title: Measure charge transport in high-energy nuclear collisions with an energy scan of isobaric collisionsComments: 8 pages, 7 figuresSubjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)
We present a method to measure electric-charge transport in high-energy nuclear collisions using a beam-energy scan of isobaric systems. Comparing collisions of nuclei with identical mass number but different atomic number allows the charge difference () to be extracted with a double-ratio technique that suppresses most experimental systematic uncertainties. By varying the beam energy, the rapidity gap () over which electric charge is transported can be systematically scanned. Simulations of Ru+Ru and Zr+Zr collisions at =19.6-200GeV with UrQMD and PYTHIA Angantyr show that midrapidity decreases exponentially with increasing , with the slope parameter exhibiting strong model dependence. Comparisons with the baryon number transport reveal distinct patterns. In both UrQMD and PYTHIA Angantyr (with and without final-state baryon junctions), where baryon number is carried solely by valence quarks, the rapidity slope for baryon transport is larger than that for electric-charge transport. In contrast, scenarios that include baryon junctions in the initial state are expected to produce the opposite trend. This demonstrates that an isobar beam-energy scan provides a sensitive probe of electric-charge transport and offers new constraints on the microscopic mechanisms governing conserved-charge redistribution in QCD matter.
- [22] arXiv:2604.11847 [pdf, other]
- Title: Causal-Horizon Effects on Quarkonium Fragmentation in JetsComments: Substantially revised. Corrects the CMS bottomonium interpretation and the distinction between spin dephasing, relaxation, and momentum migration. Adds explicit J/psi and Upsilon fragmentation tests and baseline limitations; the earlier claim of resolving inclusive polarization is superseded. Title changed to reflect the fragmentation focusSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
We reassess a horizon-inspired description of quarkonium formation in jets, distinguishing momentum redistribution from loss of spin alignment. A normalized energy-sharing prescription, with benchmark inputs for the QCD string tension and quarkonium radii, softens specified and fragmentation baselines without fitting their measured distributions. For the LO implementation displayed by LHCb, the mean momentum fraction changes from 0.629 to 0.476, compared with 0.452 in the prompt data. Applied to CMS-displayed PYTHIA bottomonium spectra, the same prescription produces shifts of the observed order, but neither comparison establishes agreement with the complete shape. An independent NLO bottomonium baseline already overestimates the low-fraction region, and an approximate acceptance-ordered application increases that excess. These results constrain the interpretation of an additional universal softening contribution. Momentum redistribution that preserves each event's spin matrix cannot change the fully integrated polarization. A separate formation-reweighting benchmark changes the polar anisotropy from 0.420 to 0.389; a larger reduction requires an additional spin-relaxation assumption. The earlier claim that the measured bottomonium fragmentation distribution establishes a resolution of the inclusive polarization puzzle is superseded. The remaining hypothesis is tested primarily through fragmentation in separately specified experimental phase spaces, with polarization as a conditional consequence.
- [23] arXiv:2606.06180 [pdf, other]
- Title: Vector charmonium(-like) states in the energy range of 4.1-4.6 GeVComments: 62 pages, 14 figures and 9 tables. JHEP versionJournal-ref: JHEP09(2026)125Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat)
The spectrum of vector charmonium(-like) states in the 4.1\dash4.6~GeV energy region exhibits a long-standing tension between inclusive and exclusive measurements. While the inclusive -value indicates only conventional vector charmonia such as and , exclusive cross sections reveal additional structures whose parameters strongly depend on the observed final states when fitted with Breit--Wigner functions. This puzzling pattern suggests that coupled-channel and threshold effects play an essential role. In this work, we develop a unified coupled-channel framework for the resonances in this energy region. The framework incorporates the -wave open-charm channels , , and constrained by heavy-quark spin symmetry, optional bare poles associated with and , and final-state interactions in the channels. We perform simultaneous fits to the BESIII cross sections for , , , , , and , together with invariant-mass distributions exhibiting the and structures. The benchmark models differ in the number of bare seed states and the fitting strategy. We show that even the purely dynamical scheme without bare charmonia captures the gross features of the analyzed distributions. The inclusion of bare compact states improves the fit quality but does not change the conclusion that the measured line shapes can be understood in terms of strong coupled-channel effects with dynamically generated poles. We also discuss possible heavy-quark spin partners of the exotic states.
- [24] arXiv:2607.26112 [pdf, other]
- Title: SET-ANUBIS: a modular pipeline for ANUBIS long-lived particle sensitivity studiesComments: 22 pages, v1.0.0 of SET-ANUBIS. Corrected minus sign in the W-HNL LagrangianSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
The proposed ANUBIS detector has been designed to search for Long-Lived Particle (LLP) signatures, which have become a focus for a variety of experiments within recent years. Due to the variety of possible LLP models and the need for directly comparable sensitivity results highlighting the potential coverage of ANUBIS, the SET-ANUBIS (Simulation, accEptance and sensiTivity studies framework for ANUBIS) framework has been developed. SET-ANUBIS is a flexible open-source Python framework that can perform full sensitivity studies of LLP signatures for the ANUBIS detector, allowing others to directly produce ANUBIS-like limits or even implement other geometries and detectors. It starts from a Universal FeynRules Output model or user-supplied rates; it exposes model parameters and particle content for user modification, and evaluates decay widths, branching ratios and lifetimes. MARTY can also be used to compute matrix elements, decay widths, branching ratios, and cross-sections. Then the framework prepares or runs event generation through Pythia8 or MadGraph, ingests HepMC event records, models the geometry of the ATLAS cavern and ANUBIS tracking stations, and applies a configurable sequence of geometric, kinematic and isolation requirements to select a set of surviving LLP candidates for evaluation. The implementation follows a ports-and-adapters architecture so that the core logic remains separate from external generators, persistent storage and visualisation. A scan-aware SQLite catalogue and content-addressed store preserve cards, metadata and compact selection-ready event bundles while avoiding duplicate artifacts. A pre-release version of the SET-ANUBIS framework has already been used to successfully derive the sensitivity of ANUBIS to three LLP benchmark models involving a Higgs portal and a Heavy Neutral Lepton model.