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Physics High Energy Physics (Experiment)

hep-ex Watch High Energy Physics (Experiment)

Tuesday 8 September

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

Level-Four Modular Symmetry Selected by the Harmonic Pattern of Quark and Lepton Masses

Vernon Barger

The mass ratios of the quarks and charged leptons follow a simple pattern. The logarithmic generation steps come in a two to one ratio, a note to its octave, and the ordering is mirrored between the up-down and down-lepton comparisons. The pattern, read as charge counting on a $Z_N$ clock, is realized at level four and at no level that is not a multiple of four, which motivates modular level four and the finite group $S_4$, with the generations in the triplet at $T$ charges $(3,1,0)$ and the mirror in the sign singlet. The charged-lepton mass ratios lie on a theta-dressed lattice at $0.02\%$, which sets the base $\varepsilon=0.18664$, taken as $14/75$, and the harmonic modulus $\tau=1.0685i$. Five postulates in the weight one-half theta constants, identified on the same data, reproduce the six quark masses from three lepton masses and the electroweak scale. Two more and one empirical relation for $|V_{td}|$ close the CKM matrix, giving $|V_{us}|=\sqrt{m_d/m_s}=0.2255$, $|V_{cb}|=0.04197$, $|V_{ub}|=0.003721$, and $\delta=1.138$ against the measured $1.139\pm0.023$, with no continuous parameter. The unitarity triangle follows, with apex $(0.161,0.348)$ against the measured $(0.161\pm0.010,0.347\pm0.010)$, and $J=3.11\times10^{-5}$ against $(3.09\pm0.07)\times10^{-5}$. The same structure carries the neutrinos. A single theta insertion gives $\sin\theta_{13}=\theta_2(\tau)m_2/m_3$, which holds at $0.7\sigma$ on the 207-day JUNO data, and the harmonic condition completes a normal-ordered spectrum with $m_1=0.25$~meV, $\Sigma m_\nu=0.0589$~eV, a CP-conserving phase $\delta_{CP}=\pi$, and effective Majorana masses quantized at $1.3$ to $3.9$~meV. The ultraviolet completion belongs to the magnetized torus class, with Pati–Salam the natural gauge embedding.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

Bottomonium suppression with a machine-learning-informed Debye mass

Ajaharul Islam, Shibo Chen, Fu-Peng Li et al. (+2 more)

Motivated by recent progress in data-driven approaches, we introduce a machine-learning (ML)-informed Debye mass, extracted from lattice-informed inputs, exclusively in the complex-valued heavy-quark Kent State University (KSU) potential. The resulting complex potential is used to solve the real-time Schrödinger equation within the quantum trajectories (QTraj) framework for the evolution of bottomonium in the quark-gluon plasma. We then compute the nuclear modification factors and double ratios for bottomonium $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ states in Pb-Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV. We compare our ML-induced results with those from the original KSU model and with experimental measurements from ALICE, ATLAS, and CMS collaborations. We find that the machine-learned Debye mass leads to improved agreement with data, particularly for excited states, highlighting the utility of machine learning in modeling in-medium QCD effects.
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All authors Ajaharul Islam, Shibo Chen, Fu-Peng Li, Long-Gang Pang, Guang-You Qin

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

Neutron disappearance and the LZ nuclear recoil event

Mohammad Aghaie and Alessandro Strumia

The LZ experiment reported a nuclear recoil with anomalous energy $E_R=248$ keV, around the typical neutron motion in xenon. This motivates interpreting the event as the disappearance of a bound neutron, either through spontaneous decay or a dark-matter-induced reaction. If the energy released is large, the predicted recoil spectrum is broad around the observed value; only $\sim10\%$ of xenon events avoid extra nuclear activity; the disappearance rate is target-independent and mildly constrained by oxygen experiments. In the special case of near-threshold DM-induced neutron disappearance, it can be open in xenon and closed in oxygen, the quiet fraction rises to $\sim30\%$, the recoil spectrum turns into lines.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

A Vector-Like Lepton Interpretation of the High-Energy Nuclear Recoil Candidate in LUX-ZEPLIN

Fatemeh Elahi and Pedro Schwaller

The LUX-ZEPLIN (LZ) experiment has recently reported a nuclear-recoil candidate at $E_R=248\pm23_{\rm stat}\pm23_{\rm sys}\,{\rm keV}$ in an exposure of $2.84\,{\rm tonne\,yr}$. At this unusually high recoil energy, the spin-independent (SI) xenon response is strongly suppressed, motivating dark matter interactions with a harder recoil spectrum. We show that elastic spin-dependent (SD) scattering through the nonrelativistic operator $\mathcal O_4=\mathbf S_{\rm DM}\cdot\mathbf S_N$ provides a simple realization of such a spectrum. We consider singlet-doublet Majorana dark matter, for which a diagonal $Z$ coupling generates the required SD interaction. The accompanying Higgs-mediated SI interaction would generically produce too many low-energy recoils, but can be suppressed along a Higgs blind spot while retaining a nonzero $Z$ coupling. We find a region of the Higgs blind spot that simultaneously predicts an $\mathcal O(1)$ event rate in the LZ high-recoil window and reproduces the observed thermal relic abundance. The same SD interaction leads to solar capture, allowing this region to be tested independently with solar-neutrino searches. Current IceCube limits already probe part of the LZ-compatible thermal parameter space, while a viable region remains. Additional xenon exposure and improved solar-neutrino searches can therefore provide complementary tests of this interpretation.
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High Energy Physics (Experiment)

A virtual reality extension for the Geant4 toolkit

Benjamin Jobilal, Muhammad Ansar Iqbal and Jay Hauser

Geant4 is a toolkit for simulating particle interactions in matter that is widely used in particle physics, nuclear physics, medical imaging, and astrophysics. At present, Geant4 visualizations are generally viewed on a conventional, two-dimensional computer display. To enhance immersion, we have developed G4VR, a virtual reality (VR) application that extends Geant4 with VR capabilities, providing a more intuitive and comprehensive way to understand these interactions. The user running G4VR in a headset can get detailed information about individual tracks, interactions, and energy depositions by selecting them with the hand controllers. G4VR also allows the user to examine the chronology of interactions, and includes animations of entire events as immersive movies. G4VR includes built-in event displays of several types that allow a first-time user to easily explore its various functionalities. To interface with Geant4, we have developed a new visualization driver called G4XR that allows direct integration with the Geant4 source code. This enables any Geant4 experiment to be loaded and experienced in VR seamlessly.
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High Energy Physics (Experiment)

NOvA Dual-Baseline Search for Active-to-Sterile Neutrino Oscillations using Neutrino- and Antineutrino-Enriched Samples

NOvA Collaboration: S. Abubakar, M. A. Acero, B. Acharya et al. (+184 more)

We report a search for neutrino oscillations to sterile neutrinos in the NOvA detectors under a model with three active and one sterile neutrinos. This search simultaneously fits data in the two NOvA detectors and is the first from NOvA to use both neutrino- and antineutrino-mode beams, with exposures of $26.61\times10^{20}$ and $12.50\times10^{20}$ protons on target, respectively. There is no evidence for sterile neutrinos in the data and we are able to exclude regions of parameter space that were allowed by previous experiments, including most of the allowed region reported by IceCube.
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All authors NOvA Collaboration: S. Abubakar, M. A. Acero, B. Acharya, P. Adamson, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, N. Balashov, P. Baldi, B. A. Bambah, E. F. Bannister, A. Barros, J. Barrow, A. Bat, T. J. C. Bezerra, V. Bhatnagar, B. Bhuyan, J. Bian, A. C. Booth, B. Brahma, C. Bromberg, N. Buchanan, J. Burns, A. Butkevich, T. J. Carroll, E. Catano-Mur, J. P. Cesar, C. Chang, S. Chaudhary, H. Chen, S. Choate, B. C. Choudhary, O. T. K. Chow, A. Christensen, M. F. Cicala, T. E. Coan, T. Contreras, A. Cooleybeck, L. Cremonesi, G. S. Davies, P. F. Derwent, K. Dever, Z. Djurcic, K. Dobbs, D. Duenas Tonguino, E. C. Dukes, A. Dye, R. Ehrlich, E. Ewart, P. Filip, M. J. Frank, H. R. Gallagher, A. Giri, R. A. Gomes, M. C. Goodman, R. Group, A. Gusmao, A. Habig, F. Hakl, J. Hartnell, R. Hatcher, J. M. Hays, M. He, K. Heller, V Hewes, A. Himmel, X. Huang, T. Huynh, A. Ivanova, K. Kaess, G. Kufatty, I. Kakorin, A. Kalitkina, D. M. Kaplan, A. Khanam, B. Kirezli, J. Kleykamp, O. Klimov, L. W. Koerner, L. Kolupaeva, C. D. Kuruppu, V. Kus, T. Lackey, K. Lang, J. Lesmeister, A. Lister, J. A. Lock, W. A. Mann, M. Manrique Plata, A. Marathe, M. Martinez-Casales, V. Matveev, A. Medhi, B. Mehta, M. D. Messier, H. Meyer, T. Miao, R. Mohanta, A. Moren, A. Morozova, L. Mualem, M. Muether, C. Murthy, D. Myers, J. Nachtman, D. Naples, J. K. Nelson, O. Neogi, R. Nichol, E. Niner, G. Nissan, M. Nixon, A. Norman, A. Norrick, A. Olshevskiy, T. Olson, A. Pal, J. Paley, L. Panda, R. B. Patterson, G. Pawloski, R. Petti, R. K. Pradhan, L. R. Prais, S. Puhan, A. Rafique, M. Rajaoalisoa, B. Ramson, B. Rebel, C. Reynolds, P. Roy, D. Sagar, O. Samoylov, M. C. Sanchez, S. Sanchez Falero, P. Shanahan, P. Sharma, A. Sheshukov, S. Shukla, I. Singh, P. Singh, V. Singh, J. Smolik, P. Snopok, N. Solomey, A. Sousa, K. Soustruznik, M. Strait, C. Sullivan, L. Suter, A. Sutton, K. Sutton, S. K. Swain, A. Sztuc, N. Talukdar, P. Tas, T. Thakore, J. Thomas, E. Tiras, Y. Torun, D. Tran, J. Trokan-Tenorio, J. Urheim, B. Utt, P. Vahle, Z. Vallari, K. J. Vockerodt, A. V. Waldron, B. Wang, C. Weber, M. Wetstein, D. Whittington, D. A. Wickremasinghe, J. Wolcott, S. Wu, W. Wu, Y. Xiao, B. Yaeggy, A. Yahaya, A. Yankelevich, K. Yonehara, S. Zadorozhnyy, J. Zalesak, L. Zhao, R. Zwaska

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

Kinematic Control and Dephasing Dynamics of Quantum Resources in $e^{+}e^{-}\to\tau^{+}\tau^{-}$

Elhabib Jaloum, Omar Bachain, Mohamed Amazioug et al. (+1 more)

We characterize several quantum resources carried by the spins of the $\tau^{+}\tau^{-}$ pair produced in $e^{+}e^{-}$ annihilation. At the Belle-II energy, $\sqrt{s}=10.579\,\mathrm{GeV}$, Bell nonlocality, steerability, entanglement of formation, and coherence are governed by the production angle and are largest for transverse emission, $\vartheta=\pi/2$. Their common kinematic origin is exposed by expressing the spin state as a velocity and angle-dependent mixture of a separable contribution and a maximally entangled component. Within the physical production domain, this representation connects the weakly correlated threshold state at $\sqrt{s}=2m_{\tau}$ to the Bell-state limit approached at ultrarelativistic energies. We then propagate the two-spin state through a phenomenological correlated-dephasing channel to determine how environmental memory and inter-channel classical correlations affect the available resources. Memory effects generate collapses and revivals that are absent from the monotonic Markovian evolution. The analysis therefore separates the kinematic mechanism that creates the spin correlations from the noise properties that control their subsequent survival.
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All authors Elhabib Jaloum, Omar Bachain, Mohamed Amazioug, Rachid Ahl Laamara

High Energy Physics (Experiment) · Cross-listed from nucl-ex

News from NA61/SHINE

Antoni Marcinek for the NA61/SHINE Collaboration

NA61/SHINE is a multi-purpose, fixed-target hadron spectrometer at the CERN SPS. Its research program includes studies of strong interactions, as well as reference measurements for neutrino and cosmic-ray physics. A significant advantage of NA61/SHINE over collider experiments is its extended coverage of phase space available for particle production. This contribution summarizes recent selected results from our strong interaction program. These include rapidity spectra of $K^+$ and $\pi^-$ mesons in Xe+La reactions compared to other collision systems, energy dependence of the scaled $\pi^-$ total yield (the `kink` plot) in Xe+La compared to other collision systems and models, $\phi$(1020) rapidity spectra in Ar+Sc collisions compared to models, $\Lambda$ transverse polarization in p+p reactions, energy dependence of intensive quantities of net-electric charge distribution in Ar+Sc collisions compared to p+p results, as well as an update on the evidence of large violation of isospin symmetry in kaon production — the excess of charged over neutral kaons.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

Inclusive electron-nucleus cross section models from domain adaptation

Krzysztof M. Graczyk, Beata E. Kowal, Rwik Dharmapal Banerjee et al. (+3 more)

We apply transfer learning (TL) to construct data-driven models of inclusive electron-nucleus cross sections. Starting from an ensemble of deep neural networks pretrained on \(^{12}\)C data, we fine-tune the models separately for \(^{3}\)He, \(^{6}\)Li, \(^{16}\)O, \(^{27}\)Al, \(^{40}\)Ca, and \(^{56}\)Fe. The resulting models improve for all targets, marginally so for oxygen, where the carbon baseline is already adequate, although their predictive robustness depends on the amount, coverage, and precision of the available target data. We systematically study how model performance depends on the number of fine-tuned layers, on the fraction and selection of the training data, and on the overlap between the source and target kinematic domains. The layer-wise analysis shows that oxygen requires only shallow adaptation, whereas helium, calcium, and iron require substantially deeper fine-tuning. Lithium represents the least robust case because of its limited dataset, while aluminum demonstrates a strong sensitivity to a small subset of highly constraining measurements. For selected kinematic configurations outside the coverage of the carbon training data, the adapted models remain consistent with the measurements within their estimated uncertainties. Finally, we compare the resulting predictions with those of the phenomenological F1F2 model.
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All authors Krzysztof M. Graczyk, Beata E. Kowal, Rwik Dharmapal Banerjee, Jose Luis Bonilla, Hemant Prasad, Jan T. Sobczyk

High Energy Physics (Experiment)

Readout electronics for SUBMET

Claudio Campagnari, Sungwoong Cho, Suyong Choi et al. (+20 more)

A dedicated data acquisition (DAQ) system has been developed for the SUB-Millicharge ExperimenT (SUBMET) at the Japan Proton Accelerator Research Complex (J-PARC), a search for particles carrying a fractional electric charge $Q = \epsilon e$ with $\epsilon$ below $\mathcal{O}(10^{-3})$, hereafter referred to as millicharged particles (mCPs). Because such particles are expected to produce at most a few scintillation photons, the system is optimized for single-photoelectron detection from the photomultiplier tubes (PMTs), combining high-speed waveform digitization with precise timing. To capture eight consecutive proton bunches of the 30 GeV J-PARC beam within a single trigger, the eight channels of the Domino Ring Sampler 4 (DRS4) chip are cascaded in groups of four to form two readout inputs, each sampling 4096 points continuously at 820.5 MHz over an effective time window of 5 us. After calibration, timing differences between channels are within 1 ns on the same DRS4 chip, 2 ns on the same board, and 8 ns across different boards, well within the 30 ns coincidence window of the experiment. The front-end electronics achieve an RMS noise below 0.4 mV. The baseline is deliberately offset upward such that the negative-going pulses span a larger fraction of the digitizer range, improving voltage resolution and dynamic range. A trigger control board aggregates data from multiple readout boards and sustains the data-transfer rate required for beam operation. The measured performance confirms that the DAQ system meets the timing, noise, and throughput requirements of the experiment.
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All authors Claudio Campagnari, Sungwoong Cho, Suyong Choi, Seokju Chung, Matthew Citron, Albert De Roeck, Martin Gastal, Seungkyu Ha, Andy Haas, Christopher Scott Hill, Insung Hwang, Hoyong Jeong, Jaebak Kim, Jeonghwa Kim, Hyunki Moon, Ryan Schmitz, David Stuart, Eunil Won, Jae Hyeok Yoo, Jinseok Yoo, Ayman Youssef, Ahmad Zaraket, Haitham Zaraket

High Energy Physics (Experiment)

Prospects for precision Higgs boson measurements at a 10 TeV muon collider

Paolo Andreetto, Massimo Casarsa, Luca Castelli et al. (+6 more)

A 10 TeV muon collider offers a powerful environment for precision studies of the Higgs sector through its large vector-boson-fusion production rates. This review presents projected sensitivities to single- and double-Higgs production cross sections, the Higgs boson mass, and the trilinear Higgs self-coupling. The projections are obtained from detailed simulations of the MUSIC detector, including machine-induced background, for a baseline configuration of two experiments, each collecting an integrated luminosity of 10 $\mathrm{ab}^{-1}$. The $H\to b\bar{b}$ and $H\to WW^\ast$ production cross sections can be measured with statistical precisions of 0.18% and 0.35%, respectively, while precisions of 2.6%, 4.2%, and 6.9% are expected for $H\to\gamma\gamma$, $H\to ZZ^\ast$, and $H\to\mu^+\mu^-$. Combining the $H\to b\bar{b}$, $H\to\gamma\gamma$, and $H\to\mu^+\mu^-$ channels yields an expected Higgs boson mass precision of about 19 MeV. Double-Higgs production can be measured with statistical precisions of 4.2% in the $HH\to b\bar{b}b\bar{b}$ channel and 14% in the $HH\to b\bar{b}WW^\ast$ channel. Using the $HH\to b\bar{b}b\bar{b}$ channel, the trilinear Higgs self-coupling can be determined with an expected precision of about 5%. These results demonstrate the potential of a high-energy muon collider for precision Higgs physics.
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All authors Paolo Andreetto, Massimo Casarsa, Luca Castelli, Alessio Gianelle, Donatella Lucchesi, Leonardo Palombini, Imran Raghib, Lorenzo Sestini, Davide Zuliani

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

Probing the $B^{0}$ meson in a hot medium with finite baryon chemical potential

A. Türkan, G. Bozk{\i}r and K. Azizi

We perform a quantitative analysis of the $B^{0}$ meson spectroscopic parameters in a hot and dense medium. Within the framework of QCD two-point sum rules, we calculate the mass and decay constant of the $B^{0}$ meson with the help of the perturbative spectral density and nonperturbative contributions up to mass dimension five as functions of temperature $T$ and baryon chemical potential $\mu_B$. For various fixed values of the baryon chemical potential, our numerical results indicate that both the mass and decay constant of the $B^{0}$ meson initially increase with temperature, reach a maximum, and then gradually decrease before eventually vanishing at sufficiently high temperatures. The corresponding vanishing points are found to be in the temperature intervals $(0.182-0.273)~\mathrm{GeV}$ and $(0.118-0.173)~\mathrm{GeV}$, for the mass and decay constant, respectively. Moreover, these temperatures move toward lower values as the baryon chemical potential increases. On the other hand, for various fixed temperatures, both the mass and decay constant exhibit a slight initial increase with increasing baryon chemical potential, followed by a subsequent decrease, eventually vanishing at sufficiently high chemical potentials. The vanishing points for the decay constant is determined to be in baryon chemical potential interval $(0.23-0.83)~\mathrm{GeV}$. For the mass, the decrease at $T=0$ is much weaker than at finite temperatures; excluding this case, the vanishing points for the mass are determined to be in baryon chemical potential interval $(0.38-1.43)~\mathrm{GeV}$ for different fixed temperatures. It is further observed that the baryon chemical potential values corresponding to the vanishing of both the mass and decay constant move to lower values as the temperature increases. In the $T \to 0$ and $\mu_B \to 0$ limit ...
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High Energy Physics (Experiment)

Search for the doubly Cabibbo-suppressed decays $D^0\to K^+\pi^-\eta^\prime$ and $D^+\to K^+\pi^0\eta^\prime$

BESIII Collaboration: M. Ablikim, M. N. Achasov, P. Adlarson et al. (+777 more)

We present the first search for the doubly Cabibbo-suppressed decays $D^0\to K^+\pi^-\eta^\prime$ and $D^+\to K^+\pi^0\eta^\prime$ using an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 20.3 fb$^{-1}$, collected at a center-of-mass energy of 3.773 GeV with the Beijing Spectrometer III (BESIII) detector at the Beijing Electron-Positron Collider II (BEPCII). No significant signals are observed, and the upper limits on their decay branching fractions are set to be $3.0\times 10^{-5}$ and $2.1\times 10^{-5}$ at the 90% confidence level, respectively. By combining these results with the world-average branching fractions of the corresponding Cabibbo-favored decays, upper limits at the 90% confidence level are obtained on the ratios of doubly Cabibbo-suppressed to Cabibbo-favored branching fractions. The limits are determined to be $1.6\times \tan^4\theta_C$ and $3.7\times \tan^4\theta_C$ for $D^0\to K^+\pi^-\eta^\prime$ and $D^+\to K^+\pi^0\eta^\prime$, respectively, where $\theta_C$ denotes the Cabibbo mixing angle.
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All authors BESIII Collaboration: M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, C. S. Akondi, R. Aliberti, A. Amoroso, L. P. An, Q. An, M. S. Anderson, Y. Bai, O. Bakina, H. R. Bao, X. L. Bao, M. Barbagiovanni, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, D. Cabiati, H. Cai, M. H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, X. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, T. T. Chang, G. R. Che, Y. Z. Che, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, J. D. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, W. Chen, X. R. Chen, X. T. Chen, X. Y. Chen, Y. B. Chen, Y. Q. Chen, Z. K. Chen, J. Cheng, L. N. Cheng, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. Cottee-Meldrum, H. L. Dai, J. P. Dai, X. C. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denisenko, M. Destefanis, F. De Mori, E. Di Fiore, X. X. Ding, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, Z. J. Dong, K. B. Du, M. C. Du, S. X. Du, Shaoxu Du, X. L. Du, Y. Q. Du, C. D. Duan, Z. H. Duan, P. Egorov, G. F. Fan, K. X. Fan, Y. H. Fan, Z. F. Fan, J. Fang, Jin Fang, S. S. Fang, W. X. Fang, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, Q. X. Feng, Y. T. Feng, M. Fritsch, C. D. Fu, J. L. Fu, Y. W. Fu, Xu Gao, Y. Gao, Y. N. Gao, Yunong Gao, Z. Gao, S. Garbolino, I. Garzia, L. Ge, L. Q. Ge, P. T. Ge, C. Geng, A. Gilman, K. Goetzen, J. Gollub, J. B. Gong, J. D. Gong, L. Gong, W. X. Gong, W. Gradl, M. Greco, M. D. Gu, M. H. Gu, C. Y. Guan, S. Y. Guan, A. Q. Guo, H. Guo, J. N. Guo, L. B. Guo, M. J. Guo, R. P. Guo, X. Guo, Y. P. Guo, Z. Guo, A. Guskov, J. Gutierrez, J. Y. Han, T. T. Han, X. Han, F. Hanisch, J. Y. Hao, K. D. Hao, X. Q. Hao, F. A. Harris, C. Z. He, K. K. He, K. L. He, F. H. Heinsius, C. H. Heinz, Y. K. Heng, C. Herold, N. D. Hoffman, P. C. Hong, G. Y. Hou, X. T. Hou, Z. L. Hou, H. M. Hu, J. F. Hu, Q. P. Hu, S. L. Hu, T. Hu, Y. Hu, Y. X. Hu, Z. M. Hu, G. S. Huang, L. Q. Huang, P. Huang, X. T. Huang, Y. P. Huang, Y. S. Huang, T. Hussain, N. Hüsken, N. in der Wiesche, Q. Ji, Q. P. Ji, W. Ji, X. B. Ji, X. L. Ji, Y. Y. Ji, L. K. Jia, S. Jia, X. Q. Jia, D. Jiang, H. B. Jiang, S. J. Jiang, X. S. Jiang, Y. Jiang, J. B. Jiao, Z. Jiao, B. W. Jin, L. C. L. Jin, S. Jin, Y. Jin, M. Q. Jing, X. M. Jing, T. Johansson, S. Kabana, X. L. Kang, X. S. Kang, B. C. Ke, A. Khoukaz, O. B. Kolcu, S. H. Kong, B. Kopf, L. Kröger, L. Krümmel, Y. Y. Kuang, M. Kuessner, X. Kui, N. Kumar, A. Kupsc, W. Kühn, L. Y. Lan, Q. Lan, J. Y. Lee, T. T. Lei, M. Lellmann, T. Lenz, C. Li, C. H. Li, C. J. Li, C. K. Li, Cong Li, D. M. Li, F. Li, G. Li, H. B. Li, H. J. Li, H. N. Li, H. P. Li, Hui Li, J. N. Li, J. W. Li, K. Li, K. L. Li, L. J. Li, L. K. Li, Lei Li, M. H. Li, M. R. Li, M. T. Li, P. L. Li, P. R. Li, Q. M. Li, R. Li, S. X. Li, S. Y. Li, Shanshan Li, T. Li, T. Y. Li, W. D. Li, W. G. Li, X. Li, X. H. Li, X. K. Li, X. L. Li, X. Y. Li, X. Z. Li, Y. H. Li, Y. B. Li, Y. C. Li, Y. G. Li, Y. L. Li, Y. P. Li, Yi Li, Z. H. Li, Z. J. Li, Z. L. Li, Z. X. Li, Z. Y. Li, Zaiyi Li, C. Liang, H. Liang, Y. F. Liang, Y. T. Liang, Z. Z. Liang, G. R. Liao, L. B. Liao, M. H. Liao, Y. P. Liao, J. Libby, A. Limphirat, C. X. Lin, D. X. Lin, T. Lin, B. J. Liu, C. Liu, C. X. Liu, F. Liu, F. H. Liu, Feng Liu, G. M. Liu, H. Liu, H. B. Liu, H. M. Liu, Huihui Liu, J. B. Liu, K. Liu, K. Y. Liu, Ke Liu, Kun Liu, L. Liu, L. C. Liu, Lu Liu, M. H. Liu, P. L. Liu, Q. Liu, S. B. Liu, T. Liu, W. T. Liu, X. Liu, X. K. Liu, X. L. Liu, X. P. Liu, X. T. Liu, X. Y. Liu, Y. Liu, Y. B. Liu, Yi Liu, Z. A. Liu, Z. D. Liu, Z. Q. Liu, Z. X. Liu, Z. Y. Liu, X. C. Lou, H. J. Lu, J. G. Lu, X. L. Lu, Y. Lu, Y. H. Lu, Y. P. Lu, C. L. Luo, J. Q. Luo, J. R. Luo, J. S. Luo, M. X. Luo, Q. Q. Luo, T. Luo, X. L. Luo, XiaoRong Lv, Z. Y. Lv, X. R. Lyu, Y. F. Lyu, Y. H. Lyu, C. L. Ma, F. C. Ma, H. L. Ma, Heng Ma, J. L. Ma, L. L. Ma, Q. M. Ma, R. Q. Ma, T. Ma, X. T. Ma, X. Y. Ma, F. E. Maas, M. Maggiora, S. Maity, S. Malde, L. M. Mansur, Y. J. Mao, Z. P. Mao, S. Marcello, A. Marshall, F. M. Melendi, Z. X. Meng, G. Mezzadri, H. Miao, T. J. Min, T. Mineeva, S. W. Ming, R. E. Mitchell, X. H. Mo, A. F. Mohammed, B. Moses, N. Yu. Muchnoi, J. Muskalla, Y. Nefedov, F. Nerling, H. Neuwirth, Z. Ning, S. Nisar, Q. L. Niu, W. D. Niu, Y. Niu, C. Normand, S. L. Olsen, Q. Ouyang, I. V. Ovtin, S. Pacetti, X. Pan, Y. Pan, C. Y. Pang, A. Pathak, Y. P. Pei, Y. Y. Pei, M. Pelizaeus, G. L. Peng, H. P. Peng, X. J. Peng, Y. Y. Peng, K. Peters, K. Petridis, J. L. Ping, R. G. Ping, S. Plura, S. Polikarpov, V. Prasad, L. Pöpping, F. Z. Qi, H. R. Qi, L. Y. Qian, S. Qian, W. B. Qian, C. F. Qiao, J. H. Qiao, J. J. Qin, J. L. Qin, L. Q. Qin, L. Y. Qin, P. B. Qin, X. P. Qin, X. S. Qin, Z. H. Qin, J. F. Qiu, J. Rademacker, K. Ravindran, C. F. Redmer, Y. Ren, A. Rivetti, M. Rolo, G. Rong, S. S. Rong, F. Rosini, Ch. Rosner, M. Q. Ruan, W. R. Ruangyoo, N. Salone, A. Sarantsev, Y. Schelhaas, M. Schernau, K. Schoenning, M. Scodeggio, Jian Shan, W. Shan, X. Y. Shan, Z. J. Shang, J. F. Shangguan, L. G. Shao, M. Shao, C. P. Shen, H. F. Shen, W. H. Shen, X. Y. Shen, B. A. Shi, Ch. Y. Shi, H. Shi, J. L. Shi, J. Y. Shi, S. Shi, X. Shi, X. D. Shi, H. L. Song, J. J. Song, M. H. Song, T. Z. Song, W. M. Song, Y. Song, Y. X. Song, Zirong Song, S. Sosio, S. Spataro, S. Stansilaus, F. Stieler, M. Stolte, J. L. Su, S. S Su, G. B. Sun, G. X. Sun, H. Sun, H. K. Sun, J. F. Sun, K. Sun, L. Sun, R. Sun, S. S. Sun, W. Y. Sun, Y. C. Sun, Y. J. Sun, Y. S. Sun, Y. Z. Sun, Z. Q. Sun, Z. T. Sun, H. Tabaharizato, N. T. Tagsinsit, C. J. Tang, G. Y. Tang, H. Y. Tang, J. Tang, J. J. Tang, L. F. Tang, Y. A. Tang, Z. H. Tang, L. Y. Tao, M. Tat, J. X. Teng, J. Y. Tian, W. H. Tian, Y. Tian, K. Yu. Todyshev, I. Uman, E. van der Smagt, S. W. Wan, X. Wan, B. Wang, B. Q. Wang, Bin Wang, Bo Wang, C. Wang, C. L. Wang, Cong Wang, D. Y. Wang, F. K. Wang, H. J. Wang, H. R. Wang, J. Wang, J. H. Wang, J. J. Wang, J. P. Wang, K. Wang, L. L. Wang, M. Wang, Mi Wang, N. Y. Wang, S. Wang, Shun Wang, W. Wang, W. P. Wang, X. F. Wang, X. L. Wang, X. N. Wang, Xin Wang, Y. Wang, Y.-K. Wang, Y. D. Wang, Y. F. Wang, Y. H. Wang, Y. J. Wang, Y. L. Wang, Yanning Wang, Yaqian Wang, Yi Wang, Yuan Wang, Z. Wang, Z. L. Wang, Z. Q. Wang, Z. Y. Wang, Zhi Wang, D. Wei, D. H. Wei, D. J. Wei, H. R. Wei, F. Weidner, H. R. Wen, S. P. Wen, U. Wiedner, G. Wilkinson, J. F. Wu, L. H. Wu, L. J. Wu, S. G. Wu, S. M. Wu, X. W. Wu, Y. C. Wu, Z. Wu, H. L. Xia, L. Xia, B. H. Xiang, D. Xiao, G. Y. Xiao, H. Xiao, Y. L. Xiao, Z. J. Xiao, C. Xie, K. J. Xie, Y. Xie, Y. Xie, Y. G. Xie, Y. H. Xie, Z. P. Xie, T. Y. Xing, G. F. Xu, H. Y. Xu, Q. J. Xu, Q. N. Xu, X. P. Xu, Y. Xu, Y. C. Xu, Z. S. Xu, F. Yan, J. Z. Yan, L. Yan, W. B. Yan, W. C. Yan, W. H. Yan, X. Q. Yan, Y. Y. Yan, H. J. Yang, H. L. Yang, H. X. Yang, J. H. Yang, L. Y. Yang, N. Yang, R. J. Yang, X. Y. Yang, Y. Yang, Y. G. Yang, Y. H. Yang, Y. Q. Yang, Y. Z. Yang, Z. B. Yang, Z. W. Yang, W. J. Yao, Z. P. Yao, M. Ye, M. H. Ye, M. Y. Ye, Z. J. Ye, H. L. Yi, K. Yi, Junhao Yin, Qiqin Yin, X. Y. Yin, Z. Y. You, B. X. Yu, C. X. Yu, G. Yu, J. S. Yu, L. W. Yu, T. Yu, X. D. Yu, Yongchao Yu, C. Z. Yuan, H. Yuan, J. Yuan, Jie Yuan, L. Yuan, M. K. Yuan, S. H. Yuan, Y. Yuan, Z. Y. Yuan, C. X. Yue, Ying Yue, A. A. Zafar, F. R. Zeng, S. H. Zeng, Xin Zeng, Y. J. Zeng, Yujie Zeng, M. Z. Zhai, Y. C. Zhai, Y. H. Zhan, B. L. Zhang, B. R. Zhang, D. H. Zhang, G. Y. Zhang, Gengyuan Zhang, H. C. Zhang, H. H. Zhang, H. L. Zhang, H. Q. Zhang, H. R. Zhang, H. Y. Zhang, H. Z. Zhang, Han Zhang, J. Zhang, J. J. Zhang, J. L. Zhang, J. Q. Zhang, J. W. Zhang, J. Y. Zhang, J. Z. Zhang, Jianyu Zhang, Jiawen Zhang, Jin Zhang, Jiyuan Zhang, L. M. Zhang, Lei Zhang, N. Zhang, P. Zhang, Q. Y. Zhang, Q. Z. Zhang, R. Y. Zhang, Rui Zhang, S. H. Zhang, S. N. Zhang, Shulei Zhang, W.-C. Zhang, X. M. Zhang, X. Y. Zhang, Y. T. Zhang, Y. H. Zhang, Y. P. Zhang, Y. X. Zhang, Yao Zhang, Yu Zhang, Yu Zhang, Yu Zhang, Z. Zhang, Z. D. Zhang, Z. H. Zhang, Z. R. Zhang, Z. Y. Zhang, Zh. Zh. Zhang, Zhaoke Zhang, Zhilong Zhang, Ziyang Zhang, Ziyu Zhang, P. Zhang, G. Zhao, J.-P. Zhao, J. Y. Zhao, J. Z. Zhao, L. Zhao, Lei Zhao, M. G. Zhao, R. P. Zhao, Y. B. Zhao, Y. L. Zhao, Y. P. Zhao, Y. X. Zhao, Z. G. Zhao, A. Zhemchugov, B. Zheng, B. M. Zheng, J. P. Zheng, W. J. Zheng, W. Q. Zheng, X. R. Zheng, Y. H. Zheng, B. Zhong, C. Zhong, X. Zhong, H. Zhou, J. Q. Zhou, S. Zhou, X. Zhou, X. K. Zhou, X. R. Zhou, X. Y. Zhou, Y. X. Zhou, Y. Z. Zhou, A. N. Zhu, J. Zhu, J. J. Zhu, K. Zhu, K. J. Zhu, K. S. Zhu, Lin Zhu, S. H. Zhu, T. J. Zhu, W. D. Zhu, W. J. Zhu, W. Z. Zhu, Y. C. Zhu, Z. A. Zhu, X. Y. Zhuang, M. Zhuge, J. H. Zou, J. Zu

High Energy Physics (Experiment)

Search for Axion Dark Matter around \texorpdfstring{$15.6\,\mu\text{eV}$}{15.6 microeV} with a Broadly Tunable High-Temperature Superconducting Cavity

Jiwon Lee, Jinsu Kim, Ohjoon Kwon et al. (+9 more)

We report an axion dark matter search in the mass range of $15.30\text{--}15.85\,\mu\text{eV}$ using a broadly tunable high-temperature superconducting (HTS) haloscope. By soldering substrate-stripped rare-earth barium copper oxide (REBCO) films onto a copper shell, we achieved a quality factor 3–4 times higher than in copper cavities across its tuning band in an 8\text{-T} magnetic field. We set robust Frequentist 90%~confidence-level exclusion limits on the axion–photon coupling down to 1.3 times the KSVZ coupling, while a complementary Bayesian analysis achieves KSVZ-level sensitivity.
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All authors Jiwon Lee, Jinsu Kim, Ohjoon Kwon, Saebyeok Ahn, Seonjeong Oh, Sergey Uchaikin, Boris Ivanov, Arjan Ferdinand van Loo, Yasunobu Nakamura, Dojun Youm, SungWoo Youn, HyoungSoon Choi

Monday 7 September

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

Revisiting two-body charmed anti-charmed baryonic $B$ decays

Chun-Khiang Chua

The study of two-body charmed anti-charmed baryonic $\overline B\to {\bf B}_c \overline {\bf B}_c$ decays using the topological amplitude approach is revisited. We include the $b\to u\bar u q$ contributions, in addition to the $b\to c\bar c q$ contributions, to these decays. The topological decomposition of $\overline B\to {\bf B}_c(\bf {\bar 3_f}) \overline {\bf B}_c(\bf { 3_f})$, ${\bf B}_c(\bf 6_f) \overline {\bf B}_c(\bf { 3_f})$, ${\bf B}_c(\bf {\bar 3_f}) \overline {\bf B}_c(\bf {\bar 6_f})$ and ${\bf B}_c(\bf 6_f) \overline {\bf B}_c(\bf {\bar 6_f})$ decay amplitudes are updated accordingly. Although the $b\to u\bar u q$ contributions are Cabibbo-Kobayashi-Maskawa (CKM) suppressed in $\Delta S=-1$ transitions, their effects are significantly amplified in $\Delta S=0$ transitions, as the relative size of the CKM factors in $b\to u\bar u q$ and $b\to c\bar c q$ contributions in $\Delta S=0$ transitions is enlarged by $\lambda^{-2}$, roughly a factor of 20, from the one in $\Delta S=-1$ transitions. Present data in $\overline B\to {\bf B}_c(\bf {\bar 3_f}) \overline {\bf B}_c(\bf { 3_f})$ decay rates allow or even slightly prefer non-negligible $b\to u\bar u q$ contributions. These $b\to u\bar u q$ contributions can allow much larger rates for $B^-\to \Xi_c^0 \bar \Xi_c^{-}$, $\overline B{}_s^0\to \Lambda_c^+ \bar \Xi_c^{-}$ and $\overline B{}^0\to \Xi_c^+ \bar \Xi_c^{-}$ decays than those only have $b\to c\bar c d$ contributions. Several modes containing only $b\to u\bar u q$ contributions in $\overline B\to {\bf B}_c(\bf 6_f) \overline {\bf B}_c(\bf { 3_f})$, ${\bf B}_c(\bf {\bar 3_f}) \overline {\bf B}_c(\bf {\bar 6_f})$ decays are also identified. Measuring these decays will be interesting and useful in clarifying the role of $b\to u\bar u q$ contributions in two-body charmed anti-charmed baryonic $\overline B$ decays.
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High Energy Physics (Experiment)

Solid-state nuclear magnetic resonance search for axion-like dark matter with broadband SQUID magnetometry

Andrew J. Winter, János Ádám, Deniz Aybas et al. (+5 more)

We report the results of an experimental search for ultralight axion-like dark matter in the mass ranges 19.5–20.5 and 21.5–22 neV. The Cosmic Axion Spin Precession Experiment-electric probes the axion-nuclear electric dipole moment coupling. We perform solid-state nuclear magnetic resonance on $^{207}$Pb spin ensembles which reside in a polarized ferroelectric crystal. The background axion-like dark matter field induces an oscillating torque on the $^{207}$Pb spins via the electric dipole moment coupling $g_{d}$. The experiment is calibrated with pulsed magnetic resonance measurements covering two frequency bands (4.6–5.0 and 5.2–5.3 MHz) that correspond to the axion Compton frequencies associated with the identified axion mass ranges. By sweeping the leading magnetic field applied to the sample, we are able to detect the $^{207}$Pb nuclear magnetic resonance in these frequency ranges using a superconducting quantum interference device, inductively coupled to the sample with a broadband circuit. We establish the upper bounds $|g_{d}| < 4\times 10^{-4}$ GeV$^{-2}$ with 95% confidence in these frequency bands. Our results demonstrate the detection and small-tip angle calibration of low-field $^{207}$Pb nuclear magnetic resonance, allowing for sensitivity to axion-like dark matter in the nanoelectron-volt axion mass range.
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All authors Andrew J. Winter, János Ádám, Deniz Aybas, Dmitry Budker, Derek F. Jackson Kimball, Surjeet Rajendran, Arne Wickenbrock, Alexander O. Sushkov

High Energy Physics (Experiment)

Real-time lepton identification at LHCb in Run 3 using Lipschitz neural networks

Adrian Casais Vidal, Kate A. Richardson, Maarten Van Veghel et al. (+3 more)

The LHCb physics program in Run 3 relies critically on the efficient real-time selection of events containing muons and electrons, which are key signatures in a wide range of heavy-flavor and exotic decay processes. The LHCb Run 3 detector now operates with a fully software-based trigger that processes the complete detector readout at the LHC bunch-crossing rate, with the first trigger stage executed on GPUs. In this environment, particle-identification algorithms must achieve high efficiency and background rejection while satisfying stringent constraints on throughput and memory footprint. We present algorithms for muon and electron identification in the LHCb Run 3 GPU trigger based on Lipschitz-constrained neural networks. Separate networks are developed for muons and electrons and are trained using simulated events. Their performance is evaluated relative to the previous baseline algorithms, demonstrating improved discrimination across a wide range of kinematic regions while remaining compatible with the requirements of real-time GPU execution.
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All authors Adrian Casais Vidal, Kate A. Richardson, Maarten Van Veghel, Marco Santimaria, Marianna Fontana, Mike Williams

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

Inelastic Singlet-Doublet Fermion Dark Matter in light of the 248 keV LZ event

Debasish Borah, Sujit Kumar Sahoo, Narendra Sahu et al. (+1 more)

Recently, the LUX-ZEPLIN (LZ) collaboration reported the observation of a single dark matter (DM)-nucleus scattering event at a nuclear recoil energy of $248\pm23_{\rm stat}\pm23_{\rm sys}$ keV, corresponding to an exposure of 2.84 tonne-year. The absence of events at lower nuclear recoil energies in the predicted spectrum is naturally explained if the underlying process is inelastic DM-nucleus scattering. Motivated by this, we investigate the singlet-doublet fermion DM model, in which the DM consists of two pseudo-Dirac states: the Majorana nature of the lighter state forbids tree level $Z$-mediated elastic scattering identically, while the same states enable inelastic DM-nucleus scattering via $Z$ exchange, with any residual elastic scattering proceeding only through a suppressed Higgs-mediated channel. We further extend the model with a $Z_2$-even scalar triplet, which is responsible both for generating the pseudo-Dirac splitting and for realizing Majorana neutrino masses via the Type-II seesaw mechanism.
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All authors Debasish Borah, Sujit Kumar Sahoo, Narendra Sahu, Shashwat Sharma

High Energy Physics (Experiment)

Response of a nitrogen-filled spherical proportional counter to mono-energetic neutrons

T. Avgitas, M. Axiotis, Z. Balmforth et al. (+16 more)

Neutron spectroscopy is an invaluable tool for a wide range of scientific and industrial applications, however, current approaches suffer from limitations that restrict their field of applicability. A safe and inexpensive alternative approach to neutron detection and spectroscopy is the use of a nitrogen-filled spherical proportional counter that exploits the $^{14}\rm{N(n,p)}^{14}\rm{C}$ and $^{14}\rm{N(n},\alpha)^{11}\rm{B}$ reactions. The neutron spectroscopy capabilities of the detector are demonstrated using beams of mono-energetic neutrons. A nitrogen-filled spherical proportional counter, operating at a pressure of $1$ bar, is exposed to neutrons with energies from $0.75$ MeV to $2.75$ MeV at the Tandem accelerator of the National Centre for Scientific Research “Demokritos” in Athens. A linear energy response is observed, within the statistical precision of the measurements.
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All authors T. Avgitas, M. Axiotis, Z. Balmforth, P. Gadow, I. Giomataris, D. Fassouliotis, J. Fock, P. Knights, A. Lagoyannis, I. Manthos, L. Millins, K. Nikolopoulos, I. Oceano, C. Prodromou, L. Schweder, E. Taimpiri, C. Toukmenidis, A. Ziagkova, R. Ward

High Energy Physics (Experiment)

Reducing simulation-related emissions in rare-event searches through optimised event biasing

P. Knights, L. J. Milligan and K. Nikolopoulos

Rare-event search experiments continue to extend their sensitivities to unprecedented levels. This requires increasingly small backgrounds, and shielding schemes that can suppress external backgrounds by several orders of magnitude. Moreover, detailed simulations are required to attain a good understanding of these experimental backgrounds. Studies have suggested, however, that simulations and computing-related tasks contribute approximately 10% to the average particle physicist's carbon footprint. With backgrounds frequently below 0.01 counts per kg of target per keV of energy, simulations require more computing resources; growing a rare-event researcher's computing-related carbon footprint. Event biasing is often applied in shielding simulations as a remedy, yet there is a lack of systematic guidance on how to maximally benefit from them. An optimisation study for the importance-splitting biasing technique is discussed, focused on balancing statistical precision with simulation CPU-time, and how this can benefit the average researcher's carbon footprint.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

LZ nuclear recoil event from inelastic singlet-doublet scalar dark matter

Disha Bandyopadhyay, Debasish Borah and Pankaj Borah

We study the possibility of explaining the recently reported high-energy nuclear recoil event by the LUX-ZEPLIN (LZ) collaboration within the framework of singlet-doublet scalar dark matter (DM). Considering DM to be the CP even mass eigenstate formed out of a scalar doublet and a real scalar singlet, both being odd under an unbroken $Z_2$ symmetry, we find the parameter space of the model consistent with correct relic abundance and direct-detection limits on elastic scattering rates. A large part of the parameter space can also lead to inelastic up-scattering of DM with a rate and recoil energy consistent with the recent LZ event. Depending upon the singlet-doublet mixing, the model allows a much wider range of currently allowed parameter space compared to the pure scalar doublet DM limit, which is disfavored due to non-observations of high-energy neutrinos from solar-captured DM annihilation by the IceCube experiment. Presence of $Z_2$-odd right-handed neutrinos also leads to other interesting phenomenology related to the origin of light neutrino masses and leptogenesis.
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High Energy Physics (Experiment) · Cross-listed from physics.ins-det

Ton-scale Xenon Gas TPC for $0\nu\beta\beta$ Search at Atmospheric Pressure

Y. Mei, K. Mistry and D.R. Nygren

We explore aspects of an unorthodox ton-scale xenon gas time projection chamber detector operated at normal temperature and pressure (NTP), designed for $0\nu\beta\beta$ discovery at $\sim10^{27}$ year sensitivity. At fixed active mass, a greater transparency to $\gamma$-ray backgrounds and better track clarity exists at NTP relative to higher density. Operation at NTP also alleviates difficulties with pressure containment and significantly reduces HV requirements. With metre-scale electron tracks at a few MeV, event topology can be used to efficiently reject the copious $\gamma$-ray backgrounds by factors ranging from 550–1200, largely compensating for the greater surface area of the detector. Event topology is captured from anode plane signals combined with sensing the secondary ion component arriving at the cathode plane. A molecular gas additive limits diffusion of the secondary electron tracks to below a cm and provides stable proportional avalanche gain. An energy resolution $\delta$E/E $\leq$ 1% FWHM seems possible. A 100 kg scale demonstrator for this detector technology could lead directly to a ton-scale search.
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High Energy Physics (Experiment)

GNN-based track reconstruction for MUonE experiment

Damian Mizera, Mateusz Goncerz, Izabela Juszczak et al. (+3 more)

A study of a Graph Neural Network-based model for track reconstruction in the context of MUonE experiment is presented, using simulated data corresponding to the test-run MUonE detector setup. The fully three dimensional model successfully addresses both the reconstruction and particle identification challenges essential for achieving the experiment's primary physics goal. It provides significantly faster pattern recognition than classical reconstruction algorithms, while maintaining comparable efficiency and resolution.
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All authors Damian Mizera, Mateusz Goncerz, Izabela Juszczak, Marcin Kucharczyk, Marcin Wolter, Milosz Zdybal

High Energy Physics (Experiment)

Leakage current evolution in LHCb VELO sensors during Run 1-2 LHC data taking period

M. Pycior, T. Szumlak, A. Oblakowska-Mucha et al. (+33 more)

Silicon detectors operating in the harsh mixed-hadron radiation environment of modern high-energy physics experiments suffer progressive bulk damage, manifesting macroscopically as a steady rise in leakage current.
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All authors M. Pycior, T. Szumlak, A. Oblakowska-Mucha, K. Akiba, W. Barter, S. Borghi, T. Bowcock, E. Buchanan, J. Buytaert, S. de Capua, S. Chen, P. Collins, F. Dettori, L. Eklund, T. Evans, M. Gersabeck, T. Gershon, T. Hadavizadeh, K. Hennessy, W. Hulsbergen, D. Hutchcroft, M. John, P. Kopciewicz, P. Koppenburg, T. Latham, M. Majewski, C. Parkes, A. Poluektov, W. Qian, K. Rinnert, E. Rodrigues, M. Schiller, M. Smith, M. van Beuzekom, J. Velthuis, M. Williams

High Energy Physics (Experiment)

Neutron detector response modeling in NOvA

NOvA Collaboration: S. Abubakar, M. A. Acero, B. Acharya et al. (+193 more)

Neutrons can present a significant challenge for neutrino experiments in which energy reconstruction is critical. With the ability to escape detection completely and with a weak correlation between their kinetic energy and any eventual energy deposition, it is difficult to fully account for neutrons produced in neutrino interactions. This in turn leads to significant model dependence when evaluating neutron-related systematic uncertainties. The NOvA experiment is a long-baseline neutrino oscillation experiment with a high-statistics sample of antineutrino data collected by its near detector. We report an excess relative to data of simulated neutron candidates with low energy depositions when using standard Geant4 physics lists. The simulation excess is traced to an overabundance of secondary photons produced from interactions of neutrons with kinetic energy greater than \SI{20}{\mega\eV}. Improved agreement with data is obtained by applying the data-driven neutron-on-carbon \menate model for neutrons between \SI{20}{\mega\eV} and ${\sim}$\SI{100}{\mega\eV}. With \menate, the residual oversimulation is more uniform across the calorimetric neutron energy spectrum, suggesting possible overproduction of primary neutrons by the GENIE neutrino interaction generator. These results motivate the adoption of \menate-supplemented Geant4 simulation as the nominal simulation in the production of future \nova simulation.
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All authors NOvA Collaboration: S. Abubakar, M. A. Acero, B. Acharya, P. Adamson, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, A. Back, N. Balashov, P. Baldi, B. A. Bambah, E. F. Bannister, A. Barros, J. Barrow, A. Bat, T. J. C. Bezerra, V. Bhatnagar, B. Bhuyan, J. Bian, A. C. Booth, B. Brahma, C. Bromberg, N. Buchanan, J. Burns, A. Butkevich, E. Catano-Mur, J. P. Cesar, C. Chang, S. Chaudhary, H. Chen, S. Choate, B. C. Choudhary, O. T. K. Chow, A. Christensen, M. F. Cicala, T. E. Coan, T. Contreras, A. Cooleybeck, L. Cremonesi, G. S. Davies, P. F. Derwent, K. Dever, Z. Djurcic, K. Dobbs, D. Dueñas Tonguino, E. C. Dukes, A. Dye, R. Ehrlich, E. Ewart, P. Filip, M. J. Frank, H. R. Gallagher, A. Giri, R. A. Gomes, M. C. Goodman, R. Group, A. Gusmão, A. Habig, F. Hakl, J. Hartnell, R. Hatcher, J. M. Hays, M. He, K. Heller, V Hewes, A. Himmel, T. Horoho, X. Huang, T. Huynh, A. Ivanova, K. Kaess, I. Kakorin, A. Kalitkina, D. M. Kaplan, A. Khanam, B. Kirezli, J. Kleykamp, O. Klimov, L. W. Koerner, L. Kolupaeva, G. Kufatty, A. Kumar, C. D. Kuruppu, V. Kus, T. Lackey, K. Lang, A. Lister, J. Liu, J. A. Lock, S. Magill, W. A. Mann, M. T. Manoharan, M. Manrique Plata, A. Marathe, M. L. Marshak, M. Martinez-Casales, V. Matveev, A. Medhi, B. Mehta, M. D. Messier, H. Meyer, T. Miao, S. Mishra, R. Mohanta, A. Moren, A. Morozova, W. Mu, L. Mualem, M. Muether, C. Murthy, D. Myers, J. Nachtman, D. Naples, J. K. Nelson, O. Neogi, R. Nichol, E. Niner, G. Nissan, M. Nixon, A. Norman, A. Norrick, H. Oh, A. Olshevskiy, T. Olson, Y. Onel, A. Pal, J. Paley, L. Panda, R. B. Patterson, G. Pawloski, R. Petti, R. K. Pradhan, L. R. Prais, S. Puhan, M. Rabelhofer, A. Rafique, M. Rajaoalisoa, B. Ramson, B. Rebel, C. Reynolds, P. Roy, D. Sagar, O. Samoylov, M. C. Sanchez, S. Sánchez Falero, P. Shanahan, P. Sharma, A. Sheshukov, S. Shukla, I. Singh, P. Singh, V. Singh, P. Snopok, N. Solomey, A. Sousa, K. Soustruznik, M. Strait, C. Sullivan, L. Suter, A. Sutton, K. Sutton, S. K. Swain, A. Sztuc, N. Talukdar, P. Tas, J. Thomas, E. Tiras, M. Titus, Y. Torun, D. Tran, J. Trokan-Tenorio, J. Urheim, B. Utt, P. Vahle, Z. Vallari, K. J. Vockerodt, A. V. Waldron, M. Wallbank, B. Wang, C. Weber, M. Wetstein, D. Whittington, D. A. Wickremasinghe, J. Wolcott, W. Wu, Y. Xiao, B. Yaeggy, A. Yahaya, A. Yankelevich, K. Yonehara, S. Zadorozhnyy, J. Zalesak, L. Zhao, R. Zwaska

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

Inelastic $B-L$ scalar dark matter and the LUX-ZEPLIN event

Nobuchika Okada and Osamu Seto

We show that our previously proposed inelastic scalar dark matter (DM) model in gauged $U(1)_{B-L}$ symmetry naturally accounts for the $2.6\sigma$ high-energy recoil event recently reported by the LUX-ZEPLIN (LZ) collaboration. To satisfy the thermal relic abundance, TeV-scale scalar DM $S$ with $m_S \simeq m_{Z'}/2$ for resonant annihilation and the gauge coupling constant $g_{B-L} \sim 0.5$ are required, where $m_{Z^\prime}$ is the mass of $U(1)_{B-L}$ gauge boson $Z^{\prime}$. The resulting predicted DM-nucleon inelastic cross section of $\sigma_\mathrm{SI} \sim 10^{-45}$ cm${}^2$ is in excellent agreement with the LZ event. This scenario can be decisively tested for future collider searches for $Z^\prime$ boson resonance.
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High Energy Physics (Experiment) · Cross-listed from hep-ph

High-Energy Nuclear Recoils from Boosted Dark Matter for the LZ 248-keV Event: Beyond the Halo-Dependent High-Velocity Tail

Haider Alhazmi, Doojin Kim, Kyoungchul Kong et al. (+2 more)

The LUX-ZEPLIN (LZ) Collaboration has reported a nuclear-recoil candidate at $E_R=248\pm23_{\rm stat}\pm23_{\rm sys}$ keV, with a maximum local significance of $3.4\sigma$ and a global significance of $2.6\sigma$. A prominent interpretation invokes heavy halo dark matter near an inelastic threshold and therefore depends sensitively on the poorly constrained high-speed tail of the Galactic velocity distribution. In this Letter, we propose a qualitatively different possibility based on light boosted dark matter (BDM), whose incident energy is determined primarily by the dark-sector mass spectrum. We consider multi-component scenarios in which the boosted state scatters elastically or inelastically off xenon nuclei. For elastic scattering, pseudoscalar-mediated momentum dependence suppresses low-energy recoils. Near-threshold endothermic scattering of a nearly monochromatic BDM flux can instead confine the signal between kinematically determined recoil endpoints, suppressing events in both the low- and high-energy sidebands. The upscattered state may furthermore decay invisibly within the dark sector, preserving a single-nuclear-recoil signature without requiring it to be detector-stable. We present representative benchmark spectra and discuss complementary tests using other target nuclei and large-volume liquid-scintillator experiments.
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All authors Haider Alhazmi, Doojin Kim, Kyoungchul Kong, Jong-Chul Park, Seodong Shin

Sunday 6 September

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

Inelastic Self-interacting Dark Matter and LUX-ZEPLIN 248 keV Event in a Dirac Modular Inverse Seesaw

Pritam Das, Biswajit Karmakar, Satyabrata Mahapatra et al. (+1 more)

We propose a novel framework that simultaneously addresses the origin of Dirac neutrino masses and the nature of self-interacting dark matter (SIDM). The model is based on an $A_{4}$ modular symmetry to ensure the Diracness of neutrinos as well as the stability of the DM. The neutrino sector realizes a Dirac Inverse Seesaw mechanism where the smallness of the neutrino mass is governed by the vacuum expectation value (VEV) of a singlet scalar $\phi$. This same scalar couples to a vector-like fermion DM candidate, inducing a tiny Majorana mass splitting that renders the DM pseudo-Dirac and inelastic. Crucially, the scalar also acts as a light mediator for DM self-interactions, potentially solving the small-scale structure problems of Cold DM. In light of the recent 248 keV nuclear-recoil event, LZ230616, observed by LUX-ZEPLIN (LZ) DM direct detection experiment, we demonstrate that our inelastic SIDM parameter space naturally accommodates this signal via endothermic scattering kinematics. Furthermore, the spontaneous breaking of the dark parity required for this inelasticity produces a network of cosmological domain walls. We show that the explicit symmetry breaking needed to safely annihilate these walls generates a stochastic gravitational wave background. The non-holomorphic modular symmetry reduces the free parameters, correlating neutrino observables, addressing DM phenomenology, $\Delta N_{\rm eff}$, and gravitational-wave signatures.
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All authors Pritam Das, Biswajit Karmakar, Satyabrata Mahapatra, Partha Kumar Paul

High Energy Physics (Experiment)

Likelihood-Based Unsupervised Anomaly Detection in CMS Dijet Events

Bhavishya Chebrolu, Hitesh Rasineni and Prajwal Aaryan Immadi

We present an unsupervised search for anomalous dijet events in proton–proton collision data using neural spline flow density estimation. A normalizing flow model is trained on a high-dimensional feature space comprising jet, dijet, and event-level observables to learn the dominant Standard Model background directly from data, without assuming a specific signal hypothesis. Events assigned low likelihood under the learned density are identified as potential anomalous events. Using this approach on a CMS Open Data dijet sample, we investigate extreme events in the tail of the anomaly-score distribution and perform an extensive validation and robustness study. This study includes feature-level statistical comparisons, mass decorrelation tests, permutation-based null tests, and evaluations of training stability. The selected anomalous events exhibit notable departures from the background-only expectation, primarily in jet-substructure observables, while remaining stable under several known sources of bias in unsupervised learning. The identified anomalies are distributed across the kinematic phase space and do not exhibit a narrow structure in the dijet invariant-mass spectrum. Instead, they show correlated deviations across multiple observables, consistent with a multivariate difference in jet substructure and event topology rather than a localized resonance. While no claim of new physics is made, this study demonstrates that neural spline flow-based density estimation can be sensitive to rare, structured deviations in collider data and may provide a model-independent exploratory tool for searches for physics beyond the Standard Model at the LHC.
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High Energy Physics (Experiment) · Cross-listed from nucl-th

Microscopic study of baryon stopping in low-energy heavy-ion collisions within UrQMD model

Sudhir Pandurang Rode

In low-energy heavy-ion collisions, baryon stopping is an important process, in which protons from the initial colliding nuclei are stopped at mid-rapidity region. Quantifying such stopping can reveal information on the properties of the nuclear medium, such as net-baryon density. Though experimental measurement of net-proton rapidity spectra provides constraints, microscopic origin of such protons is not fully accessible. Transport model studies can therefore provide deeper insight into the microscopic origin of protons transported from initial nuclei, complementing experimental measurements. This article presents an investigation of baryon stopping in minimum-bias Au+Au collisions over a wide range of beam energies, $\sqrt{s_{NN}} = 2.4-17.3$ GeV ($E_{\rm lab} = 1.23A-158A$ GeV). Final-state protons are classified based on their origin by analyzing their interaction history in the UrQMD model. A significant fraction of transported protons at mid-rapidity originates from initial neutrons rather than initial protons, referred to as isospin-converted protons, and their contribution as a function of collision energy and centrality is quantified. Anisotropic flow coefficients of different proton categories are estimated and compared with experimental measurements. Furthermore, a comparison between the $\pi^{-}/\pi^{+}$ ratio and isospin conversion rate is performed. The latter is further compared with the $\alpha$ parameters of the Kitazawa-Asakawa formalism, revealing a significant deviation from the chemical equilibrium assumption $\alpha_N = \alpha_\pi$ below $\sqrt{s_{NN}} \lesssim$ 10~GeV. Finally, the saturation of the isospin conversion rate is found to coincide with the onset of nuclear transparency, demonstrating that isospin randomization and baryon stopping are coupled phenomena in hadronic transport across the NICA/FAIR energy range.
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