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Physics High Energy Physics (Experiment)

hep-ex Watch High Energy Physics (Experiment)

Friday 21 August

High Energy Physics (Experiment) · Cross-listed from hep-ph

The excited baryon spectrum from a unified quark model

Yan-Ke Chen, Liang-Zhen Wen, Wei-Lin Wu et al. (+2 more)

A common approach to studying the multiquark states is to solve the few-body Schrödinger equation within a quark potential model. The multiquark states may contain quarks with several different flavors and have richer color structures than ordinary hadrons. The reliability of such an investigation requires that the underlying quark potential model can simultaneously describe the meson and baryon spectra across all flavor sectors, including orbital and radial excitations, with a single parameter set. At present, no quark potential model fully satisfies this requirement. We construct a simple nonrelativistic constituent quark potential model that includes spin–orbit and tensor interactions. We refit the model parameters to the latest experimental data. The excited light hadrons and several exotic hadron candidates are excluded from the fit. The resulting parameter set reproduces the spectra across all fitted sectors. The vast majority of deviations are below 20 MeV, while the largest deviations remain of the order of several tens of MeV, which is the typical accuracy of nonrelativistic quark potential models. Using the same parameters, we predict the spectra and internal structures of the orbitally and radially excited heavy baryons, which await further experimental determination. The excited light baryons are calculated with the same parameters. The calculated excited light baryon spectra deviate substantially from experimental values. Our refitted model does not resolve these longstanding discrepancies. The results delimit the range of validity of the nonrelativistic constituent quark potential model. By treating mesons and baryons across all flavor sectors, including both orbital and radial excitations within a unified framework, the model provides a controlled starting point for few-body calculations of multiquark states. We also urge experimental searches for the predicted states.
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All authors Yan-Ke Chen, Liang-Zhen Wen, Wei-Lin Wu, Lu Meng, Shi-Lin Zhu

High Energy Physics (Experiment) · Cross-listed from hep-ph

Qubits for Dark Matter Hunting

Takeo Moroi

An introductory review is provided for those who are interested in exploring applications of qubits and other quantum excitations to the detection of dark matter (and any other physics beyond the Standard Model). Topics covered include the fundamental properties of qubits, the excitation mechanism of qubits due to the electric field induced by dark matter (with attention to the effects of the coherence of dark matter), the dynamics of coupled qubit-cavity systems modeled by the Jaynes-Cummings framework, and the influence of noise and decoherence (especially Markovian noise described by the Lindblad equation). In addition, the article introduces essential concepts in quantum sensing, including the operator-sum representation and positive operator-valued measures, the Cramér-Rao bound, the standard quantum limit and the Heisenberg limit, and the potential enhancement of sensitivity to dark matter achievable with entangled states. Throughout, these topics are discussed with particular emphasis on their application to the detection of wave-like dark matter.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

A window for the mixed same-sign signature in the type-II seesaw models

Cheng-Wei Chiang

The mass splitting between the doubly and singly charged members of the Higgs triplet of the type-II seesaw model is usually treated as a free parameter in the collider literature. Electroweak loops fix it to $767$ to $841$~MeV over the mass range considered here once the quartic coupling $\lambda_4$ is set to zero at the renormalization scale $\overline\mu = M_{H^{\pm\pm}}$. Moving that scale by a factor of two in either direction moves the loop value by $208$~MeV at $200$~GeV, falling to $42$~MeV at $1$~TeV. At the reference splitting of $852$~MeV, the transition $H^{\pm\pm} \to H^\pm W^{\pm(*)}$ takes $40\%$ ($7\%$) of the total width at the crossover triplet vacuum expectation value for a doubly charged Higgs mass of $200$~GeV ($500$~GeV). That splitting is also where the partonic counting of that rate fails. Evaluated from hadronic data, the counting overestimates the rate by a factor $1.46 \pm 0.05$ at a splitting of $852$~MeV and underestimates it by a factor $4.87 \pm 0.09$ at $200$~MeV. Whether the mixed same-sign topology survives is then a condition on $\lambda_4$. The same channel moves the two published exclusion boundaries in opposite directions, by $-1.4\%$ and $+24.5\%$, at the level of branching ratios and at fixed experimental acceptance.
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Thursday 20 August

High Energy Physics (Experiment)

Measurement of the muon flux at SNOLAB using the DEAP-3600 experiment

DEAP Collaboration: P. Adhikari, M. Alpízar-Venegas, P.-A. Amaudruz et al. (+115 more)

A direct measurement of the muon flux at SNOLAB is performed using the DEAP-3600 experiment, located 2 km underground at SNOLAB near Sudbury, Canada. Primarily designed for the direct detection of weakly interacting massive particles (WIMPs), a dark matter candidate, DEAP-3600 consists of an inner spherical acrylic vessel containing a liquid argon target; this vessel is enclosed within a steel shell which is submerged in an instrumented water tank, serving as a muon veto for the dark matter search. The muon flux measurement is performed using a cut-and-count analysis of events observed in the muon veto detector and of events which are coincident between the muon veto and the liquid argon target. The requirement that muons traverse both the water and liquid argon minimizes instrumental backgrounds and systematic uncertainties. Using data collected from November 2016 to March 2020, the muon flux is measured by this coincidence analysis to be $(3.71 \pm 0.25_{\textrm{stat}} \pm 0.09_{\textrm{sys}}) \times 10^{-10}\, \mu/$cm$^2$/s. The standalone measurement using muon veto data only is compatible within uncertainties. Both measurements agree with the previous result by the SNO experiment and with simulations carried out using the MUTE software. These results provide an important benchmark for future rare-event searches at the SNOLAB facility.
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All authors DEAP Collaboration: P. Adhikari, M. Alpízar-Venegas, P.-A. Amaudruz, D. J. Auty, M. Batygov, B. Beltran, M. A. Bigentini, C. E. Bina, W. Bonivento, M. G. Boulay, J. F. Bueno, M. Cadeddu, B. Cai, M. Cárdenas-Montes, N. Cargioli, S. Cavuoti, S. Choudhary, B. T. Cleveland, R. Crampton, E. Darling, S. Daugherty, P. Di Stefano, G. Dolganov, L. Doria, F. A. Duncan, M. Dunford, E. Ellingwood, A. Erlandson, S. S. Farahani, N. Fatemighomi, L. Ferro, G. Fiorillo, R. J. Ford, A. Garai, P. García Abia, S. Garg, P. Giampa, A. Giménez-Alcázar, D. Goeldi, P. Gorel, K. Graham, A. L. Hallin, M. Hamstra, S. Haskins, J. Hu, J. Hucker, D. Huff, T. Hugues, A. Ilyasov, B. Jigmeddorj, C. J. Jillings, G. Kaur, A. Kemp, M. Khoshraftar Yazdi, G. Killaire, M. Kuźniak, F. La Zia, M. Lai, S. Langrock, B. Lehnert, M. Lissia, L. Luzzi, I. Machulin, S. MacKenzie, A. Maru, J. Mason, A. B. McDonald, T. McElroy, J. B. McLaughlin, C. Mielnichuk, L. Mirasola, S. Mohanty, A. Moharana, J. Monroe, A. Murray, M. Needs, C. Ng, G. Nieradka, G. Oliviéro, M. Olszewski, S. Pal, D. Papi, B. Park, R. Pavarani, M. Perry, V. Pesudo, T. R. Pollmann, F. Rad, C. Rethmeier, F. Retière, L. Roszkowski, R. Santorelli, F. G. Schuckman II, M. Sestu, S. Seth, V. Shalamova, P. Skensved, T. Smirnova, K. Sobotkiewich, T. Sonley, J. Sosiak, J. Soukup, R. Stainforth, M. Stringer, J. Tang, P. Taylor, C. Tierney, P. Tokareva, S. Tullio, R. Turcotte-Tardif, E. Vázquez-Jáuregui, G. Vera Díaz, S. Viel, B. Vyas, J. Walding, M. Ward, S. Westerdale, R. Wormington

High Energy Physics (Experiment) · Cross-listed from hep-ph

First Search for Ultraheavy Dark Matter Using a Magnetically Levitated Particle

Dennis G. Uitenbroek, Dorian W. P. Amaral, Juehang Qin et al. (+4 more)

We present the first search for ultraheavy dark matter using a magnetically levitated particle. The POLONAISE experiment uses a milligram-scale ferromagnet levitated in a superconducting trap, admitting a force sensitivity of $0.07\,\mathrm{fN\,Hz^{-1/2}}$ and resolving impulses as small as $1\,\mathrm{TeV}/c$. Treating every candidate impulse as a possible dark matter event, we set optimum-interval upper limits on the neutron coupling $\alpha_n$ for dark matter interacting through a new light mediator. For dark matter masses $10^6\,\mathrm{GeV}/c^2\text{-}10^{15}\,\mathrm{GeV}/c^2$ and mediators lighter than $30\,\mathrm{meV}/c^2$, we exclude couplings as low as $\alpha_n = 3.2\times 10^{-9}$ at $95\%$ confidence level and set leading constraints on the dark matter-neutron cross section for composite dark matter. Our results extend levitated sensing beyond the mass reach of optical levitation by seven orders of magnitude into the ultraheavy dark matter frontier.
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All authors Dennis G. Uitenbroek, Dorian W. P. Amaral, Juehang Qin, Jurriaan Langendorff, Andrew Gingerich, Tjerk H. Oosterkamp, Christopher D. Tunnell

High Energy Physics (Experiment) · Cross-listed from hep-ph

Poles in $\pi N$ scattering from forward dispersion relations and revised total cross-section data

José Ramón Peláez, Pablo Rabán and Jacobo Ruiz de Elvira

We present a model-independent calculation of $\pi N$ forward dispersion relations and their analytic continuation to the complex plane, using a revised set of $\pi^\pm p$ total cross-section data up to 3 GeV, and Regge asymptotics above. Up to that energy, we find four stable poles for each isospin combination. The lightest pole in the $I=3/2$ channel corresponds to the $\Delta(1232)$ resonance, while the lightest in the $I=1/2$ channel corresponds to the Roper resonance, even though the latter is imperceptible in the data. We extract their pole parameters and the parameter difference between the $\Delta^0$ and $\Delta^{++}$, without relying on a partial-wave analysis. The remaining poles cannot be identified with a single resonance each. They are not artifacts but the combined effect of multiple resonances unresolved by total cross-section data alone. Finally, we write sum rules relating the residues of these constituent resonances to the residues of the poles extracted from the dispersive representation.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

QED radiative effects in semi-inclusive deep-inelastic scattering: traditional and factorized approaches

Igor Akushevich, Haiyan Gao, Alexander Ilyichev et al. (+5 more)

Semi-inclusive deep-inelastic scattering (SIDIS) of leptons is a vital tool for probing the three-dimensional momentum space partonic structure of the nucleon. Reliable extraction of the intrinsic collinear or transverse momentum dependent parton distributions from SIDIS data requires careful treatment of QED radiative effects beyond the Born level. In this work we perform a detailed comparative analysis of QED effects in SIDIS using the traditional Bardin-Shumeiko approach, augmented by the electron structure function method, and a more recent factorized approach that treats QED and QCD radiation on equal footing. We compare analytical and numerical results of these approaches for the unpolarized $\pi^+$ electroproduction cross sections off the proton and the Collins and Sivers transverse single-spin asymmetries, and identify the sources of discrepancies between the calculations, which for the cross sections can reach up to $\approx 2\%$, $\approx 7\%$, and $\approx 5\%$ at Jefferson Lab, HERMES, and EIC kinematics, respectively. To provide a unified approach for reliably extracting partonic information from future SIDIS measurements, we propose a hybrid framework that employs the salient features of both frameworks in their respective regions of applicability.
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All authors Igor Akushevich, Haiyan Gao, Alexander Ilyichev, Shuo Jia, Vladimir Khachatryan, Youjie Lin, Tianbo Liu, W. Melnitchouk

High Energy Physics (Experiment) · Cross-listed from cs.LG

Green BOA: Determining the environmental break-even point for ML-based data compression

Caterina Doglioni, Thomas Elliott, Akshat Gupta et al. (+3 more)

We summarise the outcome of two summer internship projects based at the University of Manchester, focused on the break-even point in terms of environmental sustainability for ML-based data compression algorithms. Using the example of a ML-based lossless compression algorithm, we compare estimates for the carbon-equivalent of the infrastructure needed for ML training and inference with the carbon-equivalent savings from reduced disk storage requirements, and discuss their break-even point.
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All authors Caterina Doglioni, Thomas Elliott, Akshat Gupta, Hanzila Hussain, Sanjiban Sengupta, Zhengkai Sun

High Energy Physics (Experiment)

Distilling Normalizing Flows for Real-Time Anomaly Detection at the LHC

Tara P. A. Tahseen, Noah Clarke Hall, Nikolaos Konstantinidis et al. (+1 more)

Normalizing flows are principled anomaly detectors, selecting anomalies using a probabilistic per-event likelihood. Extreme latency and resource constraints have prevented the deployment of flow likelihoods within the hardware triggers at the Large Hadron Collider. We bypass these limitations by distilling the likelihood from a large normalizing flow into lightweight student estimators suitable for deployment on a field-programmable gate array. Our use of a conditional normalizing flow enables precise likelihood estimation in the presence of missing input features. Both decision tree and neural network students are considered, the latter optimized under advanced quantization techniques. By simultaneously improving likelihood quality and lowering inference cost, we demonstrate both state-of-the-art physics performance and latency compared with existing flow-based approaches.
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All authors Tara P. A. Tahseen, Noah Clarke Hall, Nikolaos Konstantinidis, Paula Martínez Suárez

High Energy Physics (Experiment)

The Search Budget of the BSM Resonance Program

Theresa Reisch and Tobias Golling

Data-directed scans, anomaly searches and general searches probe many mass spectra at once, and for them the look-elsewhere effect sets the discovery bar. We count the trials factor of the ATLAS BSM resonance program in effective independent resolution elements, from public inputs alone, and then work out what a fully combinatorial scan would cost in the same units. The published record, summed over the 104 spectra it scans, amounts to $N_{\mathrm{trials}} = 7.9 \times 10^{3}$ looks, so a $5\sigma$ global discovery today costs a local $Z_{\mathrm{local}} = 6.55$. Scanning instead every mass built from up to four reconstructed objects, one event-level selection at a time and priced on Run 2 and Run 3 together, amounts to $3.6 \times 10^{5}$ looks and $Z_{\mathrm{local}} = 7.11$. A factor 46 more looks therefore costs $0.56\sigma$. If the trials factor cannot be enumerated because the estimator is itself imperfect, as in machine-learning searches, two-stage unblinding is a safeguard against its spurious signals: at the defect rate measured for a published bump-hunting network it is the more sensitive procedure.
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High Energy Physics (Experiment)

Heavy-flavour production and correlations in pp collisions: precision tests of pQCD and hadronisation with ALICE

Deependra Sharma and for the ALICE Collaboration

Heavy quarks (charm and beauty) are predominantly produced in hard partonic scatterings, making their cross sections in proton–proton (pp) collisions calculable in perturbative quantum chromodynamics (pQCD) and thus providing stringent tests of pQCD. Furthermore, the associated production of two charm hadrons in a single collision offers a sensitive probe of multiparton interaction dynamics, distinguishing between single parton scattering (SPS) and double parton scattering (DPS) processes. In this contribution, preliminary measurements of prompt D-meson production are reported, together with the final results of the $\rm B^{0}$-meson production cross section down to $p_{\rm T}$ = 1 GeV/$c$ at midrapidity. The rapidity dependence of B-meson production is investigated by computing the ratio with respect to LHCb measurements at forward rapidity. The associated production of $\rm D^{0}$–$\mathrm{J}/\psi$ pairs in pp collisions at $\sqrt{s} = 13.6$ TeV is presented as well, where $\rm D^{0}$ mesons are reconstructed at midrapidity, while $\mathrm{J}/\psi$ candidates are measured at forward rapidity. These measurements are compared with pQCD calculations and phenomenological models, providing crucial constraints on heavy-quark production, hadronisation, and multiparton interaction dynamics.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

Tracing Vacuum Hadronization with Conserved Currents

Weiyao Ke, Hai Tao Li, Wanchen Li et al. (+2 more)

We show that color triality constrains the nonperturbative states that screen a Wilson-line endpoint, allowing the joint flows of net electric charge, baryon number, and strangeness to probe QCD vacuum hadronization. Whether evaluated from resolved hadrons in a jet initiated by a quark of flavor $f$ or from the corresponding charge correlators, these flows satisfy the Gell-Mann–Nishijima relation $\langle Q_{\rm flow}\rangle_f \simeq I_{3,f} +\frac{1}{2}\left( \langle S_{\rm flow}\rangle_f +\langle B_{\rm flow}\rangle_f \right)$, where $I_{3,f}$ is the third component of the initiating-quark isospin. The net jet baryon number, $\langle B_{\rm flow}\rangle_f\simeq \frac{r_{qq}}{1+r_{qq}}$, directly probes the relative probability of a diquark–antidiquark vacuum excitation, with $r_{qq}$ the diquark-to-quark production ratio. Thus, for $r_{qq}\ll1$, the baryon number carried by the jet is substantially suppressed relative to the initiating-quark value $B_f=1/3$. Likewise, the strange-to-light pair-production ratio, defined by $u\bar u:d\bar d:s\bar s=1:1:r_s$, is encoded in the measured jet strangeness $\langle S_{\rm flow}\rangle_f \simeq S_f+\frac{3r_s}{2+r_s} \left(\frac{1}{3}- \langle B_{\rm flow}\rangle_f\right)$, predicting a nonzero mean net strangeness even in $u$- and $d$-initiated jets. The conserved-current moments appearing in these relations are independent of the renormalization scale. Their simultaneous measurement therefore provides a direct, flavor-resolved probe of vacuum pair production and quantum-number transport during hadronization.
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All authors Weiyao Ke, Hai Tao Li, Wanchen Li, Xiaohui Liu, Ding Yu Shao

High Energy Physics (Experiment) · Cross-listed from hep-ph

Electroweak Baryogenesis in Top-Philic Type-III Two-Higgs-Doublet Model motivated by the $t\bar{t}$ Excess at the LHC

Yoshiki Matsuoka

The CMS and ATLAS Collaborations have reported a $t\bar{t}$ threshold enhancement possibly involving a pseudoscalar toponium quasi-bound state and an elementary pseudoscalar. Identifying the elementary pseudoscalar with the CP-odd Higgs boson, we investigate electroweak baryogenesis in the top-philic Type-III two-Higgs-doublet model (2HDM), whose scalar sector may support a strong first-order electroweak phase transition. We compare two scenarios: explicit CP violation and transitional CP violation (TCPV). In the first, a complex additional top-quark Yukawa coupling induces a spatially varying phase of the top-quark mass across the bubble wall. This generates a chiral asymmetry that electroweak sphalerons convert into baryon asymmetry. In TCPV, CP symmetry would be broken inside the bubble wall but preserved in the vacuum in the absence of explicit CP violation. A small explicit CP-violating bias would favor one of the otherwise CP-conjugate wall configurations, avoiding exact cancellation of the generated baryon asymmetry. This could allow baryogenesis without large explicit CP violation, potentially alleviating electric dipole moment constraints. Combining a one-loop finite-temperature analysis of bubble nucleation with transport calculations, we find that electroweak baryogenesis with explicit CP violation remains possible, although this conclusion depends on the thermal-resummation schemes. No viable TCPV solution is found in the parameter regions explored.
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High Energy Physics (Experiment)

Search for top quark flavor-changing neutral currents in multilepton final states using an effective field theory approach in proton–proton collisions at $\sqrt{s}$ = 13 TeV

CMS Collaboration

We present a search for flavor-changing neutral current (FCNC) interactions involving the top quark in production and decay. This analysis establishes the first global search in the top quark FCNC sector within the standard model effective field theory where all relevant operators are constrained simultaneously in a single fit to data, providing a framework for future measurements and combinations at the LHC. The analysis uses proton$-$proton collision data collected at $\sqrt{s}$ = 13 TeV by the CMS detector, corresponding to an integrated luminosity of 138 fb$^{-1}$. Signal contributions are probed in final states with two same-sign charged leptons or three leptons. Multivariate discriminants are used to separate signal from background, and their distributions enter a likelihood fit to determine 95% confidence intervals for 24 Wilson coefficients. No evidence for FCNC interactions is observed. These results provide the first simultaneous constraints on the complete operator set and place the most stringent limits to date on FCNC top quark decay branching fractions via two-quark$-$two-lepton interactions.
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High Energy Physics (Experiment)

Observation of an excess at the top quark pair production threshold in the single-lepton channel

CMS Collaboration

A search is presented for top quark-antiquark ($\mathrm{t\bar{t}}$) quasi-bound “toponium” states, near the kinematic $\mathrm{t\bar{t}}$ production threshold in final states with a single electron or muon and jets. The study uses proton-proton collision data at $\sqrt{s}$ = 13 TeV, collected by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis examines the relative velocity between the top quark and antiquark, along with two angular observables sensitive to the parity and spin of the $\mathrm{t\bar{t}}$ system. A significant excess of events is observed relative to the standard model prediction for $\mathrm{t\bar{t}}$ production calculated at next-to-next-to-leading order in perturbative quantum chromodynamics (QCD). The excess corresponds to an observed total cross section of 5.1$\pm$0.9 pb and is consistent with a simplified model of a color singlet pseudoscalar toponium motivated by nonrelativistic QCD, with a resulting observed significance of 6.1 standard deviations. The result provides an independent confirmation of the excess reported in the dilepton channel.
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Wednesday 19 August

High Energy Physics (Experiment) · Cross-listed from physics.ins-det

PSEC6: an 8-Channel 40 GSa/s Waveform Sampling ASIC in TSMC 65nm with 10.24 GHz PLL

Ahan Datta, Andrew Arzac, Davide Braga et al. (+14 more)

Picosecond level timing resolution is a prerequisite capability for improved coincidence matching, time-of-flight measurements, and secondary vertex reconstruction. Here, we present the specification, design, and simulation results for a new Application Specific Integrated Circuit (ASIC), called PSEC6, in the TSMC 65nm process. It features 8 channels, a maximum sampling rate of 40 GSa/s, a buffer length of 204.8 nanoseconds, and a 10.24 GHz Phase Locked Loop (PLL), which is the first of its kind in the 65nm CMOS process. The event readout rate is 32 kHz, with the digitization done by an off-chip Analog-to-Digital Converter (ADC). Simulations predict a 4.0 GHz analog input bandwidth and 20 mW per channel during sampling; the 10.24 GHz PLL has a predicted jitter of 550 fs RMS at 15.7 mW. The paper describes the sampling architecture, chip signal paths, PLL design, and presents simulation results.
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All authors Ahan Datta, Andrew Arzac, Davide Braga, Gordon Chen, Troy England, Farah Fahim, Henry J. Frisch, Nathan Gehl, Mary Heintz, Sumin Kim, Ava Lalich, Jinseo Park, Nathaniel J. Pastika, Hector D. Rico-Aniles, Paul M. Rubinov, Xiaoran Wang, Y.M. Richmond Yeung

High Energy Physics (Experiment)

Exploring the limits of high-energy proton-pion separation in granular calorimeters

Andrea De Vita, Abhishek, Tommaso Dorigo et al. (+1 more)

Highly granular calorimeters provide detailed information about hadronic-shower development that may enable particle identification beyond their conventional role in energy measurement. We investigate how well this information can distinguish protons from positively charged pions and how the achievable discrimination depends on detector segmentation and particle energy. The study uses Geant4 simulations of isolated particles with energies from 10 to 100 GeV in a homogeneous lead-tungstate calorimeter. A Deep Sets model operating directly on cell positions and detected energy and time outperforms a boosted decision tree based on reconstructed shower observables. With cells measuring $3 \times 3 \times 6$ mm$^3$, Deep Sets achieves an accuracy of 93.8% at 10 GeV, decreasing to 67.2% at 100 GeV. Shower topology is independently informative, deposited energy provides the largest additional contribution, and timing supplies complementary information. Coarser segmentation reduces discrimination, with performance more sensitive to longitudinal than transverse granularity. These results provide an encouraging benchmark for calorimeter-based hadron identification and motivate its inclusion among the optimization targets for future highly granular calorimeters.
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All authors Andrea De Vita, Abhishek, Tommaso Dorigo, Pietro Vischia

High Energy Physics (Experiment) · Cross-listed from physics.ins-det

The Radioactive Background of the JUNO Calibration System

Rui Li, Youhui Yun, Zhangming Chen et al. (+13 more)

The Jiangmen Underground Neutrino Observatory (JUNO) experiment is a reactor antineutrino detector employing 20 kton of ultra-pure liquid scintillator to determine the neutrino mass ordering and to precisely measure oscillation parameters. The total singles background rate from radioactivity is required to be below 10 Hz in the energy range of 0.7-12 MeV within the fiducial volume for reactor neutrino analysis. The calibration system is designed to characterize the detector energy and position responses, while several of its components are located close to the target and may contribute to the background budget. Therefore, extensive material screening and selection are required to construct a low-background calibration system and to ensure that its contribution remains within the design requirements. In this work, a comprehensive study of the radioactive background induced by the calibration system is presented, including material radioactivity measurements using high-purity germanium detectors and neutron activation analysis techniques, detailed Monte Carlo simulations to evaluate the background, and comparisons with in-situ detector data to validate the predictions. In this data analysis, dedicated spatial selection methods are developed to isolate calibration-related contributions and to suppress the liquid scintillator background. The total radioactivity contribution from the calibration system is estimated to be less than 76 mHz, which satisfies the requirement of 200 mHz (2% of the total background budget). The results from in-situ data are found to be consistent with the expectations based on material assay and simulation within uncertainties. These results demonstrate that the calibration-induced background is well understood, in agreement between data and simulation, and negligible for reactor antineutrino measurements in JUNO.
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All authors Rui Li, Youhui Yun, Zhangming Chen, Junting Huang, Jiaqi Hui, Haojing Lai, Jianglai Liu, Yankai Liu, Yue Meng, Akira Takenaka, Ziqian Xiang, Feiyang Zhang, Ping Zhang, Qingmin Zhang, Tao Zhang, Yuanyuan Zhang

High Energy Physics (Experiment) · Cross-listed from hep-ph

$\Upsilon(nS)$ Production within Jets at the LHC

Taewook Ha, Hee Sok Chung, Daekyoung Kang et al. (+2 more)

Heavy quarkonium production inside jets offers a sensitive probe of QCD dynamics and bound-state formation mechanisms. While recent studies demonstrate that charmonium-in-jet observables effectively discriminate among competing nonrelativistic QCD (NRQCD) long-distance matrix element (LDME) sets, whether this discriminating power persists in the bottomonium sector remains an open question. Here, we present the first phenomenological study of $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ production inside jets using the fragmenting jet function (FJF) framework at next-to-leading order (NLO), incorporating DGLAP evolution, threshold resummation, and feeddown contributions from higher bottomonium states. In sharp contrast to charmonium, we find that bottomonium-in-jet momentum-fraction ($z_H$) distributions exhibit a universal shape that is remarkably insensitive to the choice of LDME sets. We show that this universality stems from the strong dominance of the S-wave spin-triplet color-octet ($^3S_1^{[8]}$) production mechanism reinforced by $\chi_b$ feeddown transitions. Our predictions capture both the characteristic large-$z_H$ peak and the spectral broadening with increasing jet transverse momentum observed in recent CMS measurements. These results establish a clear physical distinction between charmonium and bottomonium fragmentation inside jets, providing a theoretical benchmark for future high-precision measurements at the LHC.
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All authors Taewook Ha, Hee Sok Chung, Daekyoung Kang, Yunlu Wang, Haixiang Zhu

High Energy Physics (Experiment) · Cross-listed from hep-ph

Unified spectroscopy of $P$-wave flavor-sextet heavy baryons from QCD sum rules

Shu-Wei Zhang, Xuan Luo, Hua-Xing Chen et al. (+1 more)

We investigate the $P$-wave flavor-sextet charmed and bottom baryons within heavy quark effective theory. A key motivation is provided by the recent evidence for the $\Xi_c(2882)^0$, which completes a sequence of four narrow $\Xi_c$ structures together with the $\Xi_c(2923)^0$, $\Xi_c(2939)^0$, and $\Xi_c(2965)^0$. Their characteristic mass-splitting pattern closely parallels that of the $\Omega_c(3000)^0$, $\Omega_c(3050)^0$, $\Omega_c(3066)^0$, and $\Omega_c(3090)^0$ states, providing strong constraints on their spectroscopic assignments. We classify the seven $P$-wave states in each of the $\Sigma_Q$, $\Xi_Q^\prime$, and $\Omega_Q$ sectors ($Q=c,b$), calculate their masses and intra-doublet mass splittings using QCD sum rules, and study their strong decays using light-cone sum rules. Configuration mixing between states with the same quantum numbers is also investigated. The combined analysis favors a common interpretation of the four narrow $\Xi_c$ and the four lowest narrow $\Omega_c$ structures in terms of the corresponding $\lambda$-mode excitations. Extending the same framework to the bottom sector, we obtain a coherent picture of the observed $\Sigma_b$, $\Xi_b$, and $\Omega_b$ structures. In particular, the $\Sigma_b(6097)$, $\Xi_b(6227)$, and $\Omega_b(6350)$ structures may each contain an unresolved pair of nearby $P$-wave states. We also predict two additional $\Sigma_b$ states, two additional $\Xi_b^\prime$ states, and one additional $\Omega_b$ state, all of which are expected to be relatively narrow and remain to be identified experimentally.
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All authors Shu-Wei Zhang, Xuan Luo, Hua-Xing Chen, Hui-Min Yang

High Energy Physics (Experiment) · Cross-listed from hep-ph

Modelling electroweak interactions at lepton colliders - from the Z pole to the highest energies

Krzysztof Mękała

Despite the Standard Model's ability to describe collider data from all experiments conducted around the world, several questions about the history of the Universe, including the hierarchy problem, the baryon asymmetry, and the dark matter density, remain open. To address these unresolved issues, the particle physics community agrees on the need to construct a next-generation collider that could probe the Standard Model with higher accuracy and potentially reveal deviations from the predictions of this fundamental theory. Future lepton colliders, operating at energies from the Z pole up to the multi-TeV scale, could probe the electroweak sector in various ways. In this thesis, the influence of radiative corrections on the modelling of electroweak processes is investigated.
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High Energy Physics (Experiment)

FAST-HEP: Compiling Declarative Analysis Workflows for High-Energy Physics and Beyond

Luke Kreczko

High-energy physics analyses increasingly rely on complex software workflows whose scientific lifetime often exceeds that of the underlying software ecosystem. Maintaining reproducibility while accommodating evolving analysis software, data formats, and execution environments therefore remains a significant challenge. These challenges are not unique to high-energy physics and are shared by many data-intensive scientific analyses. We present FAST-HEP and its workflow engine, Flow, which combines a declarative workflow language, compiler, and runtime. Flow separates the scientific description of a workflow from its implementation and execution, and compiles workflows into backend-independent execution plans through normalization, graph construction, dependency analysis, and execution planning. A common runtime then orchestrates the resulting plan using replaceable capabilities. This architecture enables static validation and modular replacement of analysis operations, execution backends, and storage technologies, while recording provenance throughout compilation and execution. Although developed for the requirements of high-energy physics analysis, Flow's workflow model and orchestration layer are domain-independent. By applying compiler techniques to scientific analysis workflows, FAST-HEP provides a foundation for workflows that are transparent, extensible, portable, and reproducible, allowing scientific analyses and their supporting software ecosystems to evolve independently.
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High Energy Physics (Experiment)

Technical Proposal for the Atom Interferometer CERN Experiment (AICE) Facility

Gianluigi Arduini, Nadja Augst, Mark G. Bason et al. (+79 more)

We present the technical proposal for the Atom Interferometer CERN Experiment (AICE), a $\mathcal{O}(100)$ m vertical atom interferometer to be installed against the wall of the PX46 access shaft to the LHC. AICE is conceived as a versatile and flexible long-baseline atom-interferometry facility whose primary scientific goal is probing for bosonic ultralight dark matter (ULDM) in a mass range inaccessible to other experiments, with a secondary goal of pioneering the exploration of gravitational waves (GWs) with frequencies in the range ${\sim}$0.03-3 Hz as a pathfinder for future longer-baseline detectors. The initial configuration employs ultracold $^{87}$Sr atoms in a single-photon 698-nm interferometer with three shaft-based atom sources in a multi-source gradiometer geometry, supported by one surface reference source for laser stabilisation and diagnostics, to target scalar ULDM. Operation with $^{88}$Sr will give sensitivity to axion-like particles (ALPs), vector ULDM with $B-L$ couplings and violation of the principle of equivalence, while a $^{171}$Yb upgrade will improve the sensitivity to $B-L$ couplings and equivalence violations. Probing the Einstein equivalence principle (EP) and measuring $\alpha$ will proceed in parallel with the ULDM searches. A conceptual feasibility study and a detailed technical implementation study have established that PX46 is a uniquely mature and implementation-ready site, with no technical showstoppers. Completing site preparation works during LS3 would enable the subsequent installation and operation of AICE without impacting HL-LHC operations. The detector design builds on the VLBAI and MAGIS experiments and the AION-10 Technical Design Report, scaling the strontium gradiometer architecture to the $\sim$100 m baseline. AICE is endorsed by the TVLBAI Proto-Collaboration, comprising 57 institutions in 22 countries.
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All authors Gianluigi Arduini, Nadja Augst, Mark G. Bason, Charles Baynham, Andrea Bertoldi, Gianfranco Bertone, Diego Blas, Daniela Bortoletto, Sougato Bose, Roberto Ales Bozzi, Oliver Buchmueller, Tamara Alice Bud, Clare Burrage, Sergio Calatroni, John Carlton, Vassilis Charmandaris, Maria Luisa Chiofalo, Pierre Cladé, Jonathon Coleman, Fabio Corsanego, Albert De Roeck, Arnaud Devienne, Fabio Di Pumpo, John Ellis, Pierre Fayet, Chris Foot, Elina Fuchs, Naceur Gaaloul, Susan Gardner, Enno Giese, Eduardo Granados, Saïda Guellati-Khelifa, Michael Guinchard, Timo Hakulinen, Tiffany Harte, Richard Hobson, Michael Holynski, Angelo Infantino, Alex Kehagias, Eva Kilian-Rademacher, Wolfgang Korsch, Damien Lafarge, Samuel Lellouch, Lucas Lombriser, Elias Lopez Asamar, J. Luis Lopez-Gonzalez, Michele Maggiore, Charline Marcel, Anna Marchant, Christopher McCabe, Gaetano Mileti, Peter Millington, Jeremiah Mitchell, Noam Mouelle, Angel Navascues Cornago, François Pillon, Rosa Poggiani, Johann Rafelski, Ernst M. Rasel, Maike Reckermann, Albert Roura, Rui Samoes, Federico Sanchez Nieto, Jack Sander, Carlo Scarcia, Jesse Schelfhout, Wolfgang Schleich, Dennis Schlippert, Ulrich Schneider, Steven Schramm, Florian Schreck, Olga Sergijenko, Marcelle Soares-Santos, Guglielmo M. Tino, Jonathan N. Tinsley, Tristan Valenzuela, Daniel Valuch, Maurits van der Grinten, Klaasjan van Druten, Ville Vaskonen, Wolf von Klitzing, Michael Werner

High Energy Physics (Experiment)

Exact time-correlated coincidence modeling with reset boundaries

Jinjing Li

Delayed-coincidence searches identify a rare prompt-delayed signal, but their accidental background is not a simple product of marginal rates: muon vetoes, event dead time, and delayed events created before the current window condition which event sequences can be recorded. We derive exact ordered coincidence rates, within a stated stochastic model, for a recorded stream of uncorrelated prompt-like singles and correlated prompt-delayed sources subject to Poisson reset boundaries and event dead time. The calculation separates two tasks: a Markov history chain carries the delayed events still pending at reset boundaries across windows, and a current-window propagator evaluates the ordered within-window integrals in closed form with block-matrix exponentials, the matrix-analytic toolkit of applied probability. The construction extends to any prescribed finite multiplicity by increasing the block-chain depth. Here we report every ordered one-, two-, and three-fold rate formed from uncorrelated singles, correlated prompts, and recorded delayed events, together with the genuine/accidental split of prompt-delayed pairs, multiplicity efficiencies, and the aggregate rate for multiplicity four or more. For the default window-close convention, we derive a three-term a posteriori error bound for the finite pending-population truncation. An independent streaming toy Monte Carlo validates the ordered rates, two-fold time densities, matched dead-time conventions, and aggregate high multiplicity. Within the stated assumptions, the construction is exact on the retained finite state spaces and provides explicit, computable truncation-error bounds.
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High Energy Physics (Experiment) · Cross-listed from physics.ins-det

Study of the intrinsic resolution of LaBr3(Ce,Sr) and NaI(Tl) crystals

Peiyi Feng, Xilei Sun, Zhenghua An et al. (+4 more)

The Gravitational wave burst high-energy Elec?tromagnetic Counterpart All-sky Monitor (GECAM) utilizes a large number of LaBr3 and NaI(Tl) crystals as sensitive materials for its gamma-ray detectors. To address the fitting issues of the energy resolution curves in the ground calibration of the GECAM detectors, this work conducts a comprehensive testing and comparative study of the energy resolution of 1-inch LaBr3(Ce,Sr) and NaI(Tl) crystals produced from the same batch. We employed a Hard X-ray Calibration Facility (HXCF), a PMT single-photoelectron calibration system, and Geant4 Monte Carlo simulation tools to quantify seven factors influencing energy resolution. The results indicate that the contributions of various components to energy resolution differ, with pho?toelectron statistical fluctuations and intrinsic resolution being predominant. For 100 keV X-rays, the total energy resolution of the LaBr3(Ce,Sr) crystal is 3.71% \pm 0.03% (expressed as 1-{\sigma}), with a contribution from photoelectron statistical fluctuations of 2.69% \pm 0.00% and an intrinsic resolution of 2.45% \pm 0.05%. For 100 keV X-rays, the total energy resolution of the NaI(Tl) crystal is 4.41% \pm 0.14% (expressed as 1-{\sigma}), with a contribution from photoelectron statistical fluctuations of 3.20% \pm 0.00% and an intrinsic resolution of 2.90% \pm 0.21%. We discussed the sources of intrinsic resolution, and the results indicate that the intrinsic resolution of the LaBr3(Ce,Sr) crystal primarily arises from luminescence non-proportionality, while that of the NaI(Tl) crystal mainly stems from fluctuations during energy transfer. This study emphasizes precise and specific experimental measurements and comparative research, demonstrating that both factors are important contributors to intrinsic resolution.
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All authors Peiyi Feng, Xilei Sun, Zhenghua An, Dali Zhang, Xinqiao Li, Shaolin Xiong, Hong Lu

High Energy Physics (Experiment) · Cross-listed from hep-ph

Axion-like particle at the 10 GeV scale: Higgs decays to wide jets and photons

Bogdan A. Dobrescu and Subhojit Roy

If axion-like particles (ALPs) exist, they may have renormalizable couplings only to the Higgs boson ($h^0$) or to fields beyond the Standard Model. An ALP $A_h$ lighter than about 60 GeV would allow the $h^0 \to A_h A_h$ decay, with a branching fraction determined by the explicit global symmetry breaking responsible for the main contributions to the $A_h$ mass ($M_A$). New heavy fields that carry color and electric charge, such as squarks, can mediate $A_h$ decays at one loop mostly into gluons, but also into photons. Exploring LHC sensitivity to $A_h$, we show that the $h^0 \to A_h A_h \to (gg)(\gamma\gamma)$ channel leads to a diphoton resonance at $M_A$ whose production rate is consistent with a $3.5\sigma$ excess reported by a CMS search at $M_A \approx 13.6$ GeV. For $M_A$ of order 10 GeV, the $h^0 \to A_h A_h \to 4g$ cascade decay leads to two wide jets (each with 2-prong substructure) that form a resonance at 125 GeV.
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Tuesday 18 August

High Energy Physics (Experiment) · Cross-listed from physics.chem-ph

Polyaniline as a conductive polymer and its role in improving the efficiency and conductivity of perovskite solar cells

Mehran Hosseinzadeh Dizaj

This article investigates the role of polyaniline as a conductive polymer in the active layer of perovskite solar cells. Samples were created by incorporating polyaniline into the transport layers to assess its impact on enhancing efficiency and conductivity. The application of this polymer across various layers of the cell structure led to improved stability and performance. Given its high doping capability, polyaniline was examined in detail, particularly focusing on two types of oxidation doping and its integration into the hole transport layer. Graphene oxide and reduced graphene oxide were chosen as comparative models, and their performance was evaluated against the standard polyaniline configuration. Laboratory results revealed that power conversion efficiency increased by 17.5% with graphene oxide and by 36.8% with reduced graphene oxide. Furthermore, short-circuit current density improved by 9.8% and 23.1%, respectively. These findings are consistent with existing studies in the field and support the validity of the approach.
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High Energy Physics (Experiment) · Cross-listed from physics.data-an

Multivariate amplitude analysis of the cascade particle decays based on the Nearest Neighbors fitting

I. V. Yeletskikh and A. O. Vasyukov

The Nearest Neighbors estimation of likelihood is implemented for the multivariate amplitude analysis of the cascades of particle decays. In this approach Monte Carlo simulated events that are used to describe data are assigned weights dependent on the parameters of the theoretical fitting model. Each of such weighted events is considered as contributing to N-dimensional probability density function in it's neighborhood in the parameter space. No analytic p.d.f. or cpu-intensive re-generation of N-dimensional p.d.f. at each fit step are required. The method allows accurate accounting for reconstruction effects, demands modest cpu resources and can be effectively multi-threaded. General setup of the fit as well as toy example of the amplitude analysis of B-meson decays are demonstrated.
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High Energy Physics (Experiment)

Performance of heavy-flavour jet identification in the CMS high-level trigger in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV

CMS Collaboration

The CMS trigger system plays a crucial role during data taking, reducing the large collision rate delivered by the LHC to a few kHz for data storage and subsequent offline analysis. The system aims to maintain a high selection efficiency for a wide range of processes, including those involving jets originating from heavy-flavour quarks (b and c), which provide a distinctive signature in many physics analyses. To achieve this while maintaining a sustainable trigger output rate, dedicated jet flavour identification methods are developed and optimized for use in the high-level trigger (HLT). This paper presents the design, commissioning, and performance of deep-learning-based jet identification algorithms deployed in the HLT during 2022$-$2024, for proton-proton collisions at $\sqrt{s}$ = 13.6 TeV. The new algorithms enabled significant improvements in signal efficiency for a variety of key physics processes, including the non-resonant production of Higgs boson pairs decaying to four b quarks, as well as Higgs boson production via both vector boson fusion and in association with a $\mathrm{t\bar{t}}$ pair, in the H $\to$ $\mathrm{b\bar{b}}$ and H $\to$ $\mathrm{c\bar{c}}$ decay channels.
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High Energy Physics (Experiment) · Cross-listed from nucl-ex

Observation of enhanced baryon production using strange hadrons in oxygen-oxygen collisions

CMS Collaboration

A hot deconfined medium known as the quark-gluon plasma (QGP) is created in collisions of ultrarelativistic heavy nuclei. In these systems, hadron production is strongly modified relative to proton-proton (pp) interactions. In the hadron transverse momentum region 2 $\lt$ $p_\mathrm{T}$ $\lt$ 5 GeV, collective radial flow and quark coalescence are important mechanisms that can produce such modifications. While these effects are well-established for collisions of large ions, such as lead, it is unknown if they are present in systems produced using smaller ions. To address this question, the $p_\mathrm{T}$ spectra of two strange hadrons, K$^0_\mathrm{S}$ and $\Lambda$, are measured in oxygen-oxygen (OO) and pp collisions at a center-of-mass energy per nucleon pair of 5.36 TeV. The measurements are performed using the CMS detector at the LHC, and the OO and pp datasets correspond to integrated luminosities of 6.8 nb$^{-1}$ and 1.1 pb$^{-1}$, respectively. The spectral modification of K$^0_\mathrm{S}$ mesons in OO collisions relative to pp collisions is found to be similar to that of inclusive charged hadrons. Conversely, the $\Lambda$-to-K$^0_\mathrm{S}$ cross section ratio exhibits a pronounced enhancement in OO collisions when compared to pp collisions. The results provide the first observation of a baryon-to-meson enhancement in OO collisions and suggest the formation of a deconfined medium, offering insight into the roles of strangeness, radial flow, and quark coalescence in QGP.
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