HEP Phenomenology·hep-ph
48 papers—28 primary·20 cross-listed·reconstructed*
Jeppe R. Andersen🇬🇧 · Andreas Maier🇪🇸 · Malina Rosca🇬🇧 · Giacomo Ruisi🇩🇪
We present the first calculation of the high-energy corrections to the process of isolated photon production in association with two jets. These corrections both stabilise the perturbative behaviour in and lead to a significantly improved description of data from a recent ATLAS measurement.
F. Arleo🇫🇷 · P. Caucal🇫🇷 · A. Deshpande🇺🇸 · J. M. Durham🇺🇸 · G. M. Innocenti🇺🇸 · J. Jalilian-Marian🇺🇸 · A. Kusina🇵🇱 · M. X. Liu🇺🇸 · Y. Mehtar-Tani🇺🇸 · C.-J. Naïm🇺🇸 · H. Paukkunen🇫🇮 · S. Platchkov🇫🇷 and 3 other authors
This review examines data from hadron-nucleus collisions, primarily focusing on hard processes like Drell-Yan, heavy flavor and quarkonium production. It highlights observed modifications of particle yields as functions of momentum and rapidity, aiming to clarify the underlying QCD effects in cold nuclear matter (CNM). The paper outlines strategies for future experiments, including the Electron-Ion Collider (EIC), to distinguish between these effects. Key questions address the universality of suppression mechanisms and the role of non-perturbative physics, providing a road map for upcoming nuclear data.
Cheng-Wei Chiang🇹🇼 · Kazuki Enomoto🇹🇼 · Min-Yuan Liao🇹🇼
We investigate the search for doubly charged Higgs bosons in the Georgi-Machacek (GM) model at same-sign lepton colliders. The dominant production mode is vector boson fusion, through which the particle is singly produced and decays into a pair of same-sign bosons if the triplet vacuum expectation value is sufficiently large, as allowed in the GM model. Considering the leptonic decays of the bosons, we discuss the discovery reach of the signal and a method to extract the mass of the doubly charged Higgs boson. It is impossible to construct the transverse mass of the decay product to obtain the mass because of the neutrinos radiated from the initial-state leptons. Alternatively, we propose to make use of the invariant mass of the same-sign leptons. We perform fitting using the analytical formula for the invariant mass distribution and demonstrate that this approach is effective in extracting the information on the mass. We also compare the process with pair production processes at the opposite-sign lepton colliders.
Anish Ghoshal🇵🇱 · Debarun Paul🇮🇳 · Supratik Pal🇮🇳
We propose a novel cosmological probe of dark matter (DM) through inflationary primordial gravitational wave (GW) measurements highlighting its complementarity with traditional indirect detection. In scenarios like early matter domination (EMD), the thermal DM relic is diluted and then replenished via non-thermal production, leaving characteristic imprints on the primordial GW spectrum, inducing frequency-dependent suppressions in the GW amplitudes. By analysing signal-to-noise ratio (SNR) and employing Fisher forecast, we show that upcoming GW experiments have good potential to probe the DM parameter space involving its mass and annihilation cross-section. We show, for instance, LISA will be sensitive to DM mass range GeV. Furthermore, we identify a significant overlap of the GW missions' sensitivity reaches with the projected reach of future indirect searches like CTA with gamma rays, ANTARES, KM3NeT with neutrinos. In those overlapping regions of interests, we forecast on the GW experiments to estimate the precision of measurements. We show, for instance, that DM mass of GeV with an annihilation cross-section of , and a mass of GeV with an annihilation cross-section of , lie within the projections of CTA. We find that whilst the former can be probed by ET with uncertainties, the latter can be probed by -ARES with uncertainties. Similarly, DM mass of GeV, with cross-section lies within the projection of ANTARES and KM3NeT, which can be probed by ET with uncertainties.
Aleksandr Pustyntsev🇩🇪 · Marc Vanderhaeghen🇩🇪
Recent theoretical and experimental studies of the muon magnetic moment indicate the absence of the previously reported discrepancy, providing a vital opportunity to constrain potential BSM physics. In this work, we explore the MeV-GeV mass range, where existing exclusion limits remain relatively loose. We analyze both scalar and pseudoscalar as well as vector and axial vector mediators. We demonstrate that the new bounds are not only comparable to - but in several cases, significantly more stringent than - the constraints obtained from previous collider experiments, even when near-future projections are considered.
Kishora Nayak🇮🇳 · Vipul Bairathi🇨🇱
The directed flow () of charged hadrons () in symmetric collision systems (O+O, Cu+Cu, Zr+Zr, Ru+Ru, Au+Au, and U+U) at 200 GeV using string-melting version of A Multiphase Transport (AMPT-SM) model is reported. The as a function of pseudo-rapidity () is obtained for transverse momentum () ranges of 0.2-2.0 GeV/ and 2.0-5.0 GeV/. The dependence of -slope () at mid-rapidity on range, collision centrality, and system size are discussed particularly in the context of the hard-soft asymmetry in the flow profiles of produced particles. In the AMPT-SM model, a system size independence of the magnitude of between Cu+Cu and Au+Au collisions at low- is observed, and this finding is similar to the observation from the STAR experiment at 200 GeV. In contrast, a strong centrality and system size dependence, with the opposite sign of , is found for the high- charged hadrons. The AMPT-SM model demonstrates a clear violation of the expected scaling of charged hadrons across different colliding systems.
Yin-Zhen Xu🇪🇸 · Adnan Bashir🇲🇽 · Khépani Raya🇪🇸 · José Rodríguez-Quintero🇪🇸 · Jorge Segovia🇪🇸
We investigate the internal structure of a comprehensive set of pseudoscalar and vector mesons, including both flavor-symmetric and flavor-asymmetric systems, by reconstructing their charge distributions from electromagnetic form factors. To achieve this, we employ a Maximum Entropy Method optimized for charge distributions, utilizing previously published form factor data obtained within the Dyson-Schwingers and Bethe-Salpeter equations framework. Furthermore, we calculate the average distance between the valence quark and antiquark that constitute the meson, interpreting it as an estimate for both the meson's spatial size and the typical range of quark motion. Our results reveal that this distance for the lightest quarkonia is approximately five times larger than that for the heaviest. Moreover, due to spin effects, vector mesons exhibit sizes that are 5-15\% larger than their pseudoscalar counterparts.
We investigate charged lepton flavor violating top quark flavor-changing neutral current interactions at the proposed asymmetric muon-electron collision stage of the TRISTAN collider, operating at a center-of-mass energy of 346 GeV. Specifically, we study the process () with , within the framework of three classes of four-fermion contact interactions: scalar, vector, and tensor operators. A cut-based analysis is performed using boost-invariant kinematic observables, followed by a likelihood-based statistical treatment to derive projected sensitivities for each operator. For an integrated luminosity of , the projected constraints improve upon current LHC bounds on the corresponding effective couplings by approximately an order of magnitude. Projections for indicate even stronger sensitivity, indicating improved reach at higher luminosity. Additionally, we explore the impact of initial-state beam polarization on these projections, showing how it can further enhance sensitivity to specific operator structures.
Wang Li🇨🇳 · Xing-Gang Wu🇨🇳 · Hua Zhou🇨🇳 · Xu-Chang Zheng🇨🇳
The Cabibbo-Kobayashi-Maskawa matrix element is an important Standard Model parameter, whose value can be determined by using the semi-leptonic decay . The perturbative QCD (pQCD) corrections to the transform form factor has been known up to the NLO level, whose magnitude remains sensitive to the choice of renormalization scale . To improve the precision of and hence , we first apply the single-scale approach of Principle of Maximum Conformality (PMC) to eliminate the conventional (Conv.) renormalization scale dependence of the short-distance parameter and then predict the contribution of its unknown NLO term via Bayesian analysis. In this paper, we adopt two probabilistic models for Bayesian analysis: the Cacciari-Houdeau model (CH model) and the geometric behavior model (GB model). It is shown that by using the PMC series in combination with Bayesian analysis, one can achieve high degree of reliability in estimating unknown higher-order terms. A more convergent behavior is achieved by applying the PMC, confirmed by the predicted NLO contributions: for the CH model, and ; for the GB model, and . Comparing with the latest experimental measurements, we obtain , which is consistent for both CH and GB models and in good agreement with the PDG world average, within errors.
Abdelrahman AbuSiam (University of Sharjah)🇦🇪 · Amine Ahriche (University of Sharjah)🇦🇪
In this work, we study a scotogenic extension of the Standard Model featuring two inert scalar doublets and three singlet Majorana fermions, where neutrino masses are generated radiatively at one loop. The lightest among the Majorana fermions and neutral scalars can serve as dark matter candidates. We explore the parameter space, considering theoretical constraints (perturbativity, unitarity, vacuum stability) and experimental limits (lepton flavor violation, Higgs measurements, electroweak precision observables). Our analysis identifies regions where sizable Yukawa couplings naturally arise due to constructive interference in the scalar sector. Additionally, we estimate the oblique parameters, finding that only is sensitive to charged mass splittings, while and remain small across the viable parameter space. However, 60\% of the viable parameter space is excluded by the recent CMS measurement of the boson mass, since the shift depends on the oblique parameters, particularly that is sensitive to scalar mass splittings.
Shi-Dong Liu🇨🇳 · Qi Wu🇨🇳 · Gang Li🇨🇳
Recently, the new structure observed by the BESIII Collaboration in the was identified to be the -wave vector molecular resonance using a unified meson exchange model. Apart from the vector -wave state, a possible pseudoscalar -wave molecular state of the [called for short] was also predicted, which is likely to be observed in future experiments. Within the molecular framework, we calculated the partial decay widths for a series of hadronic decays of the , including , , , and . Under present model parameters, the hidden-charm decay modes are dominated by the and , and the partial widths can reach 1 MeV and 0.1 MeV, respectively. The open-charm channel exhibits a rather small decay rate (). In terms of our present predictions, we suggest BESIII and Belle II to search for the pseudoscalar -wave molecular state with in the hidden-charm processes or .
It has been assumed that nuclear modification does not exist in the longitudinal-transverse structure-function ratio in lepton deep inelastic scattering. This assumption is widely used in obtaining structure functions of the "nucleon" from nuclear data such as the deuteron ones. However, nuclear modifications do exist theoretically at least in medium- and large- regions because nucleons in a nucleus move in any direction, which is not necessarily the longitudinal direction of the virtual-photon or weak-boson momentum in lepton scattering. Because of this transverse motion, the nucleon's transverse and longitudinal structure functions should mix with each other in nuclei with the mixture probability proportional to the nucleon's transverse momentum squared . In this work, numerical results are explicitly shown regarding such nuclear modifications in the deuteron. These nuclear modifications are important for determining precise structure functions of the nucleon. Furthermore, modifications of should be investigated also at small by the future electron-ion collider to find interesting gluon dynamics in nuclei. Hopefully, this nuclear effect of could be found by future experimental measurements at lepton accelerator facilities.
K. A. Bronnikov🇷🇺 · V. D. Ivashchuk🇷🇺 · V. V. Khruschov🇷🇺
A brief description of the main methods for determining the fine structure constant is given. It is shown that the exact value of the fine structure constant is important for the new International System of Units (SI) and for fundamental metrology. Recent measurement results and theoretical calculations of the fine structure constant, as well as its possible space-time variations, are presented. The results of laboratory experiments on the search for long-term variations of the fine structure constant are described. The astrophysical and cosmological observational data on possible variability of the fine structure constant are displayed. The possibility of slightly lower values of the fine structure constant in the remote past as compared to its modern value, as well as the existence of unresolved problems related to possible space-time variations of the fine structure constant and the spread of the results of its precise laboratory measurements, are mentioned. Despite the absence of experimentally confirmed long-term variations of the fine structure constant at a high level of accuracy, possible practical applications of the results are noted, namely, the construction of an optical frequency standard with high stability and frequency reproduction accuracy based on the ytterbium-171 ion and a laser frequency synthesizer which may replace the caesium frequency standard.
Jinmian Li🇨🇳 · Peng Li🇨🇳 · Bingwei Long🇨🇳 · Rao Zhang🇨🇳
We introduce a novel end-to-end framework for jet reconstruction in high-energy collider events, leveraging the efficiency and long-range modeling capabilities of the Mamba architecture. Our model unifies instance segmentation, classification, and kinematic regression into a single multi-task learning system, enabling a sophisticated multi-level reconstruction that simultaneously identifies primary heavy jets (, , ) and their constituent sub-jets. To facilitate supervised learning for this complex task, we develop a novel method for assigning final-state hadrons to their ancestor colored partons using a Mixed-Integer Linear Programming solver, which generates high-fidelity ground-truth labels. The model achieves high classification accuracy, with an Average Precision score of 0.569 for -jets and 0.568 for -jets, and shows exceptional precision in kinematic reconstruction. Furthermore, we show that the model not only maintains stable performance in high-pileup environments but also successfully reconstructs the mass peaks of beyond the standard model particles. This work presents a powerful and versatile new tool for comprehensive event reconstruction at the LHC.
Christian Bierlich🇸🇪 · Peter Christiansen🇸🇪
Recent measurements of event-by-event fluctuations of multistrange baryons and kaons in proton-proton collisions by ALICE have been proposed as sensitive probes to distinguish between thermal and string-based hadronization mechanisms. We demonstrate that two key observables -- the normalized net- second-order cumulant and the net---net- Pearson correlation coefficient -- can be re-expressed in terms of balance function integrals, thereby revealing their underlying microscopic content, and relating them to balance functions previously measured by ALICE. This allows us to show that both observables probe the same physics and primarily measure the impact of strangeness conservation on hadronization. We compare both sets of ALICE data with two contrasting models, PYTHIA and Thermal-FIST. Importantly, while Thermal-FIST can reproduce the magnitude of fluctuation observables, it fails to describe the shape of the measured balance functions. Our findings highlight the importance of balance functions as precision tools for testing hadronization models in small collision systems and propose a robust baseline for future studies exploring hadronization dynamics in QCD matter.
Imtiaz Khan🇨🇳 · Ali Muhammad🇨🇳 · Tianjun Li🇨🇳 · Shabbar Raza🇵🇰
We explore the Electroweak Supersymmetry (EWSUSY) scenario within the Minimal Supersymmetric Standard Model (MSSM) under the Generalized Minimal Supergravity (GmSUGRA) framework, given that the anomalous magnetic moment of the muon may now be consistent with the Standard Model (SM) prediction, we consider both signs of the Higgsino mass parameter, and . A comprehensive scan of the parameter space is performed, subject to the experimental constraints from the LHC SUSY searches, Planck 2018 relic density, and LUX-ZEPLIN (LZ) direct detection limits. We identify the viable regions featuring neutralino dark matter production via coannihilation with stau, chargino, stop, sbottom, and gluino, as well as through -funnel, Higgs-resonance, and -resonance mechanisms. Notably, the scenario yields a broader allowed parameter space, including for the first time sbottom-neutralino coannihilation solutions in GmSUGRA, which are absent for . While the Higgs-pole and -pole regions for are largely excluded by the current LZ bounds, substantial viable regions remain for . Gluino coannihilation scenarios are strongly constrained by the current LHC data. The characteristic mass ranges of interest include sbottoms (0.7-1.3~TeV), stops (up to 1.0~TeV for and 1.3~TeV for ), staus and charginos (up to 1.5~TeV), and pseudoscalar Higgs bosons in the -funnel (0.4-1.4~TeV). Moreover, the supersymmetric contributions to the muon anomalous magnetic moment remain within a deviation from the SM prediction. And our findings suggest that significant portions of the parameter space can be probed at the future LHC SUSY searches and upcoming dark matter direct detection experiments.
Anisha🇩🇪 · Francisco Arco🇩🇪 · Stefano Di Noi🇩🇪 · Christoph Englert🇬🇧 · Margarete Mühlleitner🇩🇪
We investigate the potential of future electron-positron colliders, such as FCC-ee and CEPC, to probe 2-Higgs-doublet models (2HDMs) that facilitate a strong first-order electroweak phase transition (SFOEWPT), a necessary condition for electroweak baryogenesis. Focusing on a 2HDM in the CP-conserving limit, we identify parameter regions consistent with an SFOEWPT and evaluate their compatibility with projected precision electroweak and Higgs measurements, as well as searches for exotic Higgs bosons. We show that radiative corrections to production introduce deviations in the cross section that are resolvable with the anticipated sub-percent precision at lepton colliders even when experimental outcomes of the LHC and pole measurements are in agreement with the SM. This underscores the opportunities of a precision lepton collider to explore BSM quantum corrections to the Higgs sector more broadly.
Andrey L. Pankratov🇷🇺 · Pavel A. Belov🇷🇺 · Eduard E. Boos🇷🇺 · Alexander S. Chepurnov🇷🇺 · Alexander V. Chiginev🇷🇺 · Alexander V. Derbin🇷🇺 · Ilia S. Drachnev🇷🇺 · Lev V. Dudko🇷🇺 · Dmitry S. Gorbunov🇷🇺 · Maxim A. Gorlach🇷🇺 · Vadim V. Ivanov🇷🇺 · Leonid V. Kravchuk🇷🇺 and 15 other authors
Firmly established in astrophysical observations, dark matter evades direct detection in experiments. Axions and axion-like particles are among the leading dark-matter candidates, and numerous attempts to detect them in laboratories have been performed. Here, we propose to advance these efforts substantially, extending the sensitivity for dark-matter axions in the mass range eV down to the axion-photon couplings GeV, motivated by generic models of Quantum Chromodynamics axion. Single-photon detectors operating at ultra-low temperatures are key elements of the experiment. The projected sensitivity will be reached in one year of data taking with magnetic field of T, making Cosmological Axion Sarov Haloscope (CASH) the most sensitive haloscope in this mass range.
Niu Su🇨🇳 · Er-Liang Cui🇨🇳 · Yi-Wei Jiang🇨🇳 · Hua-Xing Chen🇨🇳
Confirming the existence of hybrid states remains challenging due to their experimental indistinguishability from tightly bound tetraquarks and loosely bound molecules. To address this issue, we employ QCD sum rules to systematically investigate the and as candidate tetraquark states with exotic quantum numbers . Within the hybrid framework, an flavor nonet is expected, featuring two isoscalar configurations, and , where . In contrast, the tetraquark scenario predicts an flavor 81-plet comprising three isoscalar states: , , and . Our analysis yields a mass of GeV for the tetraquark state, which is expected to decay predominantly into the and final states. Therefore, experimental scrutiny of their invariant mass spectra is pivotal for distinguishing between hybrid and tetraquark interpretations.
We present the complete one-loop corrected Higgs mass within the Standard Model. It is crucial to identify the observable mass as the renormalized one that depends on the external momentum. The correction is finite and dominated by the loops involving the W bosons and the top quark. These contributions exhibit a power-law running with momentum, which may be verifiable at the Large Hadron Collider.
Ugo Giuseppe Aglietti🇮🇹 · Giancarlo Ferrera🇮🇹 · Wan-Li Ju🇨🇦
We consider the form factor appearing in QCD resummation formalism for event shape distributions in the two-jet (or Sudakov) region. We present an analytic formula for the inverse transform of the form factor, namely from the conjugate moment space to the (physical) momentum space, based on the saddle-point method. The saddle-point itself is determined by means of an analytic recursion method as well as by standard numerical methods. The results we have found are in very good agreement with the exact (numerical) evaluation of the inverse transform, while they significantly differ from classical analytical formulations of resummation in momentum space. The latter are based on a Taylor expansion of the form factor around the free-theory saddle point.
Liang-Zhen Wen🇨🇳 · Yan-Ke Chen🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳
We employ Heavy Baryon Chiral Perturbation Theory (HBPT), a non-relativistic effective field theory that treats baryons as heavy static sources, to calculate the electromagnetic polarizabilities of spin-3/2 baryons in two sectors: the light-flavor decuplet baryons and singly heavy sextet baryons. We derive the analytical expressions up to . Our results indicate that the long-range chiral corrections provide substantial contributions to the polarizabilities. In addition, magnetic dipole (M1) transitions of the baryons can significantly affect the magnetic polarizabilities and may even reverse their signs. For the decuplet baryons, the and exhibit the largest electric polarizabilities. Their values, and , significantly exceed those typically observed for nucleons. Meanwhile, the electric polarizabilities of spin-3/2 singly heavy baryons are comparable to those of their spin-1/2 partners.
Sarah K. Blask🇺🇸 · Sean Fleming🇺🇸 · Thomas Mehen🇺🇸 · Jyotirmoy Roy🇺🇸 · Iain W. Stewart🇺🇸 · Fanyi Zhao🇺🇸
Non-relativistic QCD (NRQCD) is used to calculate the relativistic correction to the amplitude for exclusive photoproduction of vector Quarkonia in the near-threshold region within the generalized parton distribution (GPD) framework. The relativistic corrections are found to be large for , and lead to a breakdown of the GPD moment expansion near threshold. Cross-sections for both and are calculated with the former being compared to the data. We also demonstrate the presence of endpoint divergences for the relativistic correction away from the near-threshold regime.
Clara Murgui🇨🇭 · Samuel Patrone🇺🇸
In this study, we numerically show that automatic Nelson-Barr models with new chiral fermions can simultaneously solve the strong CP problem and generate the observed baryon asymmetry via high-scale leptogenesis. In these models, all CP violation arises from a single spontaneous symmetry-breaking scale, linking the origin of quark and lepton CP phases. Using conservative assumptions and minimal dynamics, we identify a viable parameter window where successful leptogenesis occurs without spoiling the quality of the strong CP solution. Models with vector-like fermions face tension within this leptogenesis scenario. A key prediction is a correlation between the baryon asymmetry and the induced QCD vacuum angle shift. Remarkably, we find that the majority of the available parameter space is within reach of current and future nucleon EDM experiments.
Yang Bai🇺🇸 · Carlos Henrique de Lima🇨🇦 · Daniel Stolarski🇨🇦
We investigate the phases of a strongly coupled QCD-like theory at finite baryon chemical potential using s-confining supersymmetric QCD deformed by anomaly-mediated supersymmetry breaking. Focusing on the case of three colors and four flavors, we identify novel phases including spontaneous breaking of baryon number and/or parity. Both first-order and second-order phase transitions are observed as the baryon chemical potential is varied. These findings may offer insights into possible phases of real QCD at intermediate baryon densities.
Disha Bandyopadhyay🇮🇳 · Debasish Borah🇮🇳 · Arnab Dasgupta🇺🇸
We propose a novel cogenesis scenario by utilising the two-body decay of heavy right-handed neutrino (RHN) via an effective operator involving an axion-like particle (ALP) dark matter (DM) and a light chiral fermion . This allows the two-body decay of heavy RHN into and ALP thereby generating a lepton asymmetry in which later gets transferred to left-handed leptons via sizeable Yukawa coupling with a neutrinophilic Higgs doublet. The asymmetry in left-handed leptons is then converted into baryon asymmetry via electroweak sphalerons. The lepton number violation by heavy RHN also induces a one-loop Majorana mass of rendering the light neutrinos to be Majorana fermions. Successful leptogenesis constrain the parameter space in terms of RHN mass and axion decay constant. This has interesting consequences for both ALP and QCD axion DM parameter space within reach of several ongoing and near future experiments. We also propose a Dirac version of this scenario without any total lepton number violation. This leads to a long-lived asymmetric Dirac fermion contributing partially to DM thereby opening up more parameter space for ALP. In addition to axion search experiments, the proposed scenarios can have observable signatures at cosmic microwave background (CMB), DM search as well as terrestrial particle physics experiments.
Markus Frank🇨🇭 · Sven Heinemeyer🇪🇸 · Margarete Mühlleitner🇩🇪 · Kateryna Radchenko🇩🇪
The shape of the Higgs potential is modified by the presence of additional scalar fields, as predicted in many Beyond-Standard-Model (BSM) scenarios. In such cases, deviations in the Higgs self-interactions, in particular the trilinear Higgs couplings, could serve to disentangle the physics beyond the Standard Model (SM). While the SM predicts only one trilinear Higgs coupling, extended scalar sectors allow for additional self-interactions that can manifest themselves in Higgs pair production, via the -channel contribution of a heavy -even scalar . We present the first sensitivity study to such a BSM trilinear scalar coupling using machine learning. Specifically, we train a neural network on the invariant mass distributions of Higgs pair production at the HL-LHC to extract , i.e. the product of the resonant top-Yukawa coupling and the trilinear coupling of to the two SM-like Higgses in the final state, . Assuming a hypothetical mass of 450 GeV, we show that, depending on future experimental efficiencies and uncertainties, a determination of at the 10-20% level may be achievable by the end of the HL-LHC. We present a simple and more efficient alternative to classical statistical methods, proving the efficiency of neural networks for both hypothesis testing and parameter estimation, which outperforms conventional maximum likelihood methods in this context.
Enrico Bothmann🇩🇪 · Timo Janßen🇩🇪 · Max Knobbe🇺🇸 · Bernhard Schmitzer🇩🇪 · Fabian Sinz🇩🇪
We apply for the first time the Flow Matching method to the problem of phase-space sampling for event generation in high-energy collider physics. By training the model to remap the random numbers used to generate the momenta and helicities of the scattering matrix elements as implemented in the portable partonic event generator Pepper, we find substantial efficiency improvements in the studied processes. We focus our study on the highest final-state multiplicities in Drell--Yan and top--antitop pair production used in simulated samples for the Large Hadron Collider, which computationally are the most relevant ones. We find that the unweighting efficiencies improve by factors of 150 and 17, respectively, when compared to the standard approach of using a Vegas-based optimisation. We also compare Continuous Normalizing Flows trained with Flow Matching against the previously studied Normalizing Flows based on Coupling Layers and find that the former leads to better results, faster training and a better scaling behaviour across the studied multiplicity range.
Shulei Cao🇺🇸 · Amit Kumar Mandal🇵🇱 · Michal Zajaček🇨🇿 · Bharat Ratra🇺🇸
We present a high-quality, homogeneous sample of 157 H reverberation-mapped active galactic nuclei (RM AGNs) spanning redshifts , which is approximately 3.8 times larger than the previously available high-quality homogeneous sample. Using the broad-line region radiusluminosity relation (), which involves the broad H line time delay and the monochromatic luminosity at 5100\,Å\,, we show that the sample is standardizable by using six spatially flat and nonflat cosmological models. The inferred cosmological model parameters are consistent within 2 uncertainties with those from better established baryon acoustic oscillation and Hubble parameter measurements, with the exception of two nonflat models that are ruled out by other data. The relation slope is found to be flatter ( in the flat CDM model) than the slope expected from a simple photoionization model as well as the slope found previously for the smaller homogeneous sample. In addition, we find a mild dependence of H relation parameters as well as its intrinsic scatter on the Eddington ratio by comparing the relations for low- and high-accreting equal-sized subsamples. A future analysis of a larger homogeneous sample containing a broader range of luminosities and Eddington ratios is necessary to confirm the standardizability of H AGNs.
Wei-Xiang Feng🇨🇳 · Hai-Bo Yu🇺🇸 · Yi-Ming Zhong🇨🇳
The gravothermal core collapse of self-interacting dark matter halos provides a mechanism for seeding supermassive black holes in the early Universe. We show that the collapse of a small fraction of the halo mass can trigger general-relativistic instability and produce black hole seeds in halos with masses at high redshift. We investigate whether this process can account for the origin of JWST little red dots at , which host black holes with masses . We find that such masses can be reached within through rapid core collapse followed by efficient accretion, even for initial seed masses of . This scenario allows a substantial fraction of the black hole mass to originate from dark matter accretion, potentially offering a viable pathway to forming massive black holes at high redshift.
M. Maroudas🇩🇪 · A. Argiriou🇬🇷 · G. Cantatore🇮🇹 · E. Georgiopoulou🇬🇷 · M. Karuza🇭🇷 · A. Kryemadhi🇺🇸 · I. Lazanu🇷🇴 · A. Mastronikolis🇬🇧 · M. Parvu🇷🇴 · Y. K. Semertzidis🇰🇷 · I. Tsagris🇬🇷 · M. Tsagri🇬🇷 · G. Tsiledakis🇫🇷 · K. Zioutas🇬🇷
This study analyzes an 11-year cosmic ray dataset of positrons and antiprotons for planetary dependencies related to gravitationally focused dark matter streams. By projecting event timestamps onto planetary heliocentric longitudes, structured flux modulations are found. The results resemble previously reported planetary relationships in solar and terrestrial observables. This supports the possibility that streaming dark matter particles are focused toward Earth by solar system bodies, including the Moon. The findings suggest further searches using other cosmic ray channels, including existing very high-energy gamma-ray data.
STAR Collaboration
Most atomic nuclei exhibit ellipsoidal shapes characterized by quadrupole deformation and triaxiality , and sometimes even a pear-like octupole deformation . The STAR experiment introduced a new "imaging-by-smashing" technique [arXiv:2401.06625, arXiv:2501.16071] to image the nuclear global shape by colliding nuclei at ultra-relativistic speeds and analyzing outgoing debris. Features of nuclear shape manifest in collective observables like anisotropic flow and radial flow via mean transverse momentum . We present new measurements of the variances of (, 3, and 4) and , and the covariance of with , in collisions of highly deformed U and nearly spherical Au. Ratios of these observables between the two systems effectively suppress common final-state effects, isolating the strong impact of uranium's deformation. By comparing results with state-of-the-art hydrodynamic model calculations, we extract and values consistent with those deduced from low-energy nuclear structure measurements. Measurements of and its correlation with also provide the first experimental suggestion of a possible octupole deformation for U. These findings provide significant support for using high-energy collisions to explore nuclear shapes on femtosecond timescales, with implications for both nuclear structure and quark-gluon plasma studies.
Kourosh Nozari🇮🇷 · Sara Saghafi🇮🇷 · Fatemeh Aliyan🇮🇷
The Einstein Euler Heisenberg (EEH) black hole model represents an extension of classical black hole solutions in general relativity by incorporating quantum electrodynamic (QED) corrections. These corrections are introduced through the inclusion of the Euler-Heisenberg Lagrangian, which accounts for the nonlinear effects of QED in the presence of strong electromagnetic fields. This study investigates the observational properties of a thin accretion disk surrounding the electrically charged rotating EEH black hole. By exploring the influence of the spin parameter and charge on key dynamical quantities such as the energy, angular momentum, angular velocity, and the innermost stable circular orbit (ISCO) of a test particle it becomes possible to analyze the radiative flux, temperature distribution, and differential luminosity of the thin accretion disk in the spacetime of the charged rotating EEH black hole. The results are compared to those of Kerr and Kerr Newman black holes in General relativity, revealing that QED corrections are found to increase the ISCO radius. Specifically, for a fixed electric charge, an increasing spin parameter leads to a larger ISCO radius compared to the standard Kerr black holes as a result of additional electromagnetic corrections introduced by the Euler Heisenberg theory. Conversely, when the spin parameter is held constant, an increase in the electric charge reduces the ISCO radius. Additionally, thin accretion disks around charged EEH rotating black holes exhibit higher temperatures and greater efficiency when the spin parameter is fixed and the electric charge is increased.
Dhritimalya Roy🇮🇳 · Somnath Nag🇮🇳
Quantum variational algorithms (QVAs) are increasingly potent tools for simulating quantum many-body systems on noisy intermediate-scale quantum (NISQ) devices. This work examines the application of the Variational Quantum Eigensolver (VQE) to four progressively complex models based on the cranked Nilsson-Strutinsky (CNS) framework. By incorporating single-particle spacings, pairing correlations, and rotational cranking terms, we evaluate VQE performance against exact diagonalization (ED) benchmarks. We provide a systematic benchmarking of VQE across a hierarchy of CNS-inspired Hamiltonians, explicitly identifying where hardware-efficient ansatz succeed and fail, and introducing quantum information diagnostics, the entanglement spectrum and Quantum Fisher Information, as novel probes of the pairing-rotation. Our results demonstrate that with a properly optimised multi-restart warm-starting strategy, VQE achieves near-machine-precision convergence () across the full cranking frequency range and we confirm that the same strategy reproduces an established He shell-model pairing benchmark, demonstrating that the RealAmplitudes ansatz is expressively sufficient for this problem class. The entanglement spectrum confirms the product-state character of the exact ground state throughout the pairing-rotation transition, while the Quantum Fisher Information identifies a finite-size precursor to the critical pair-breaking frequency. These results establish a systematic methodological baseline and provide a reproducible framework for the nuclear physics community.
Waqas Ahmed🇨🇳 · Mansoor Ur Rehman🇸🇦
Nonminimal coupling between the inflaton and the Ricci scalar plays a crucial role in shaping the predictions of single-field inflationary models. While a quartic potential with such coupling represents one of the simplest realizations compatible with cosmological observations, it generically receives important radiative corrections when the inflaton interacts with other fields, particularly those involved in the reheating process. In this work, we focus on radiative corrections arising from bosonic scalar couplings and study their impact on inflationary dynamics within the nonminimally coupled quartic potential framework. We demonstrate that bosonic corrections, unlike fermionic ones, yield predictions more compatible with the latest constraints from the Atacama Cosmology Telescope (ACT) Data Release 6, especially when combined with Planck and BICEP/Keck data. We begin with a general model involving a gauge-singlet real scalar inflaton coupled to a complex scalar field, which could be the Standard Model Higgs or a GUT Higgs. As a concrete realization, we also investigate the case where the inflaton serves as a dark matter candidate through a Higgs portal interaction while highlighting its potential to generate observable levels of primordial gravitational waves. Notably, the nonminimally coupled inflation model studied here is field-theoretically equivalent to the Starobinsky model, and the inclusion of quantum corrections from scalar fields leads to characteristic imprints in the plane, allowing for refined constraints on scalar couplings from current and future observations.
Sermet Çağan🇹🇷 · Omer Guleryuz🇹🇷 · Cemal Berfu Senisik🇹🇷
What if supersymmetry is not something to be hidden, but something to be reached? We introduce the Supersymmetric Horizon Stabilization (SHS): a conceptually unified and analytically controlled framework for embedding metastable de Sitter vacua and trans-Planckian inflation within effective supergravity. Built from a logarithmic Kähler potential modified by nilpotent constraints, SHS yields a framework that connects the early universe's inflationary phase, intermediate metastable acceleration, and a final supersymmetric fixed point. We classify viable models by enforcing four essential criteria: absence of ghosts, de Sitter metastability, smooth Minkowski transitions, and asymptotic supersymmetry. The resulting scalar dynamics exhibit exponential field-space profiles, , allowing trans-Planckian excursions with bounded moduli. This structure leads to finite geodesic distance and a stabilized gravitino mass, conditionally avoiding towers of light states and remaining consistent with the Gravitino and Swampland Distance Conjectures. At the same time, the divergent Euclidean cost of reaching the supersymmetric endpoint realizes the AdS and Generalized Swampland Distance Conjectures, situating the infrared boundary at infinite dynamical distance. From this behavior emerges the Supersymmetric Horizon Conjecture: that consistent gravitational EFTs may begin and end with supersymmetry -- both at the origin and the asymptotic edge of cosmic evolution -- not as a fine-tuned remnant, but as a geometric boundary condition. SHS also supports localized features that transiently enhance scalar fluctuations, enabling efficient production of primordial black holes with masses far exceeding those in conventional inflationary scenarios.
Shreyas Tiruvaskar🇳🇿 · Chris Gordon🇳🇿
A self-interacting dark-matter (SIDM) density spike around merging supermassive black holes (SMBHs) may be able to supply the dynamical friction needed to shrink binaries from to , thereby resolving the long-standing "final-parsec problem". Embedding the binary-halo system in a cosmological population model, we evolve the inspiral under the combined influence of gravitational-wave (GW) emission and SIDM drag, compute the resulting nanohertz GW background, and confront it with the NANOGrav 15-year pulsar-timing data. A six-parameter Bayesian analysis, performed with a Gaussian-process-accelerated Markov chain Monte Carlo, yields posterior constraints on the cross-section per unit mass and maximum circular velocity values that were consistent with independent galaxy-rotation and cluster-lensing limits. Within this parameter space, the SIDM spike remains intact, supplies sufficient friction to overcome the stellar depletion barrier, and produces a characteristic-strain spectrum that matches the NANOGrav signal as well as phenomenological astrophysical models.
Haiyang Wang🇨🇳 · Renhui Qin🇨🇳 · Ligong Bian🇨🇳
We develop a real-time Wigner-functional lattice framework with positive Hartree-Gaussian initial sampling and introduce a connected-cluster survival criterion for extracting false-vacuum decay rates across the crossover from quantum fluctuations to thermal nucleation. At high temperatures, the connected-cluster rate agrees well with the Hartree-resummed thermal nucleation benchmark, while the commonly used global-survival criterion can give substantially smaller rates because of multi-seed dynamics and global averaging. At low temperatures, the connected-cluster and global-survival rates approach each other in the dilute-event regime, whereas the false-vacuum fraction observable can be contaminated by transient spatial conversion and kink-antikink reflection. Our results clarify how different real-time observables encode distinct aspects of metastable decay.
Roman N. Lee🇷🇺 · Andrei A. Pomeransky🇷🇺
We consider the monodromy group of the differential systems for multiloop integrals. We describe a simple heuristic method to obtain the monodromy matrices as functions of space-time dimension . We observe that in a special basis the elements of these matrices are Laurent polynomials in with integer coefficients, i.e., the monodromy group is a subgroup of . We derive bilinear relations for monodromies in and dimensions which follow from the twisted Riemann bilinear relations and check that the found monodromy matrices satisfy them.
A direct interaction between dark energy and dark matter provides a natural and important extension to the standard CDM cosmology. We perform a non-parametric reconstruction of the vacuum energy () interacting with cold dark matter using the cosmological data from DESI DR2, Planck CMB, and three SNIa samples (PP, DESY5, and Union3). By discretizing the coupling function into 20 redshift bins and assuming a Gaussian smoothness prior, we reconstruct without assuming any specific parameterization. The mean reconstructed changes sign during cosmic evolution, indicating an energy transfer from cold dark matter to dark energy at early times and a reverse flow at late times. At high redshifts, shows a deviation from CDM. At low redshifts, the results depend on the SNIa sample: CMB+DESI and CMB+DESI+PP yield consistent with zero within , while CMB+DESI+DESY5 and CMB+DESI+Union3 prefer negative at . Both tests and Bayesian analyses favor the model, with CMB+DESI DR2+DESY5 showing the most significant support through the largest improvement in goodness of fit () and strongest Bayesian evidence (). Principal component analysis reveals that the data effectively constrain three additional degrees of freedom in the model, accounting for most of the improvement in goodness of fit. Our results demonstrate that the dynamical dark energy preference in current data can be equally well explained by such a sign-reversal interacting dark energy, highlighting the need for future observations to break this degeneracy.
Wei-Jiang Zou🇨🇳 · Yi-Long Yang🇨🇳 · Jun-Xu Lu🇨🇳 · Peng-Wei Zhao🇨🇳 · Li-Sheng Geng🇨🇳 · Jie Meng🇨🇳
The symmetric nuclear matter and pure neutron matter are investigated by the relativistic Brueckner-Hartree-Fock (RBHF) theory with the covariant chiral nuclear forces up to the next-to-leading order~(NLO). A fitting scheme to ensure the naturalness of the low-energy constants is proposed, which plays a crucial role in the proper description of nuclear matter. With a momentum cutoff MeV, the empirical saturation energy and density, as well as the incompressibility coefficient at the saturation density are reproduced well. The EoSs show less dependence on the momentum cutoff and become softer at densities above saturation density, in comparison with the previous leading order results. Given the good description for the saturation properties of nuclear matter, the present work encourages future studies of the finite nuclei in the framework of the RBHF theory with the NLO covariant chiral nuclear forces.
Matteo Bacci · Claudio Bonati🇮🇹
We numerically investigate the stability of universal properties at continuous phase transitions against perturbations of the Markov Chain Monte Carlo algorithm used to simulate the system. We consider the three dimensional XY model as test bed, and both local (single site Metropolis) and global (single cluster) updates, introducing deterministic truncation-like perturbations and stochastic perturbations in the acceptance probabilities. In (almost) all the cases we find a remarkable stability of the universal properties, even against large perturbations of the Markov Chain Monte Carlo algorithm, with critical exponents and scaling curves consistent with those of the standard XY model within statistical uncertainties. Only for the single cluster update with very large truncation error does something different happen, but large scaling corrections prevent us from precisely assessing the critical properties of the transition, and, in particular, to understand whether the critical behavior observed corresponds to a known universality class.
Tribhuban Parida🇮🇳 · Rupam Samanta🇵🇱 · Jean-Yves Ollitrault🇫🇷
We introduce a new observable to probe the collective nature of the radial expansion of the quark-gluon plasma. This observable, dubbed , represents the correlation of the spectrum with elliptic flow, in the same way as the recently measured represents the correlation of the spectrum with the transverse momentum per particle. The advantage of over is that it is measured using a three-particle cumulant, as opposed to a pair correlation, which significantly reduces the sensitivity to nonflow effects. We predict non-trivial differences between and in semi-central Pb+Pb collisions at the Large Hadron Collider (LHC) on the basis of hydrodynamic simulations. A hint of these differences can be seen in the modification of spectra observed by ALICE in event-shape-engineered events.
Xin Zhang🇨🇳 · Yu Zhang🇨🇳 · Xiaofeng Luo🇨🇳 · Nu Xu🇨🇳
High moments of conserved quantities such as net-baryon, net-electric charge, and net-strangeness in heavy-ion collisions are sensitive to fluctuations caused by the QCD critical point (CP). The event-by-event analysis of high moments of the conserved charges has been widely used in experiments to search for the CP, especially in the RHIC-STAR experiment. In order to establish a {\it dynamical non-critical base line}, especially at the high baryon density region, we have performed a systematic analysis of the proton multiplicity distributions from Au+Au collisions at 3 9.2 GeV collisions. The results on beam energy, centrality and rapidity width dependence of proton (factorial) cumulants, up to the order, are extracted from the calculations of the hadronic transport model UrQMD. In addition, the effects of initial volume fluctuation is also discussed. These results will be important when we do physics analysis the RHIC beam energy scan (BES) data, especially for the fixed-target data and experimental data from future CBM experiment at FAIR.
Ruican Ma🇬🇧 · Chris Done · Aya Kubota
We present a comprehensive spectral and timing analysis of the newly discovered black hole transient Swift J1727.81613, based on broadband (2150 keV) observations from -HXMT during its 2023 outburst. We use the flexible, energy-conserving SSsed model to model both the outer disc and inner, complex Comptonisation, using the expected disc emissivity to constrain the corona radius, . This decreases from 45 to 9 during the transition from the hard to hard intermediate and then soft intermediate state. We plot versus the centroid frequency of the strong quasi-periodic oscillations (QPOs; ) seen in these data to test the inner hot flow Lense-Thirring (LT) precession model. The overall slope of the observed trend is in strong agreement with the predictions of LT precession, despite the complexities of accretion behavior, though there is an offset in absolute value which may indicate that the system parameters are still not well determined. The inner radius of the hot flow is consistent with a constant value throughout most of the outburst, indicating that changes in the jet (e.g. the discrete ejections) do not strongly affect the radiated power. Either the jet kinetic power is not a large fraction of the accretion power or the jet is instead mostly powered by the spin energy of the black hole.
Jad C. Halimeh🇩🇪 · Masanori Hanada🇬🇧 · Shunji Matsuura🇯🇵
We present a quantum simulation framework universally applicable to a wide class of quantum systems, including quantum field theories such as quantum chromodynamics (QCD). Specifically, we generalize an efficient quantum simulation protocol developed for bosonic theories in [Halimeh et al., arXiv:2411.13161] which, when applied to Yang-Mills theory, demonstrated an exponential resource advantage with respect to the truncation level of the bosonic modes, to systems with both bosons and fermions using the Jordan-Wigner transform and also the Verstraete-Cirac transform. We apply this framework to QCD using the orbifold lattice formulation and achieve an exponential speedup compared to previous proposals. As a by-product, exponential speedup is achieved in the quantum simulation of the Kogut-Susskind Hamiltonian, the latter being a special limit of the orbifold lattice Hamiltonian. In the case of Hamiltonian time evolution of a theory on an spatial lattice via Trotterization, one Trotter step can be realized using numbers of CNOT gates, Hadamard gates, phase gates, and one-qubit rotations. We show this analytically for any matter content and gauge group with any . Even when we use the Jordan-Wigner transform, we can utilize the cancellation of quantum gates to significantly simplify the quantum circuit. We also discuss a block encoding of the Hamiltonian as a linear combination of unitaries using the Verstraete-Cirac transform. Our protocols do not assume oracles, but rather present explicit constructions with rigorous resource estimations without a hidden cost, and are thus readily implementable on a quantum computer.
Christina Schwemmbauer🇩🇪 · Guy Daniel Hadas🇮🇱 · Yonit Hochberg🇮🇱 · Katharina-Sophie Isleif🇩🇪 · Friederike Januschek🇩🇪 · Benjamin V. Lehmann🇺🇸 · Axel Lindner🇩🇪 · Adriana E. Lita🇺🇸 · Manuel Meyer🇩🇰 · Gulden Othman🇩🇪 · Elmeri Rivasto🇩🇰 · José Alejandro Rubiera Gimeno🇩🇪
We propose the use of transition-edge sensor (TES) single-photon detectors as a simultaneous target and sensor for direct dark matter searches, and report results from the first search of this kind. We perform a 489 h science run with a TES device optimized for the detection of 1064 nm photons, with a mass of ~0.2 ng and an energy threshold of ~0.3 eV, and set new limits on dark matter interactions with both electrons and nucleons for dark matter with mass below the MeV scale. With their excellent energy resolution, TESs enable search strategies that are complementary to recent results from superconducting nanowire single-photon detectors and kinetic inductance detectors. We show that next-generation TES arrays hold promise to probe new regions of light dark matter parameter space.
Mariam Bouhmadi-López🇪🇸 · Beñat Ibarra-Uriondo🇪🇸
In this work, we carry out a comprehensive perturbative analysis of four cosmological models featuring a sign-switching cosmological constant. Among these, we include the well-known CDM model, characterised by an abrupt transition from a negative to a positive cosmological constant. We also consider the LCDM model, which exhibits a generalised ladder-step evolution, as well as the SSCDM and ECDM models, both of which undergo a smooth sign change at comparable redshifts. We solve the linear cosmological perturbation equations from the radiation-dominated era, imposing initial adiabatic conditions for matter and radiation, for modes well outside the Hubble radius in the early Universe. We analyse the behaviour of the matter density contrast, the gravitational potential, the linear growth rate, the matter power spectrum, and the evolution . These results are contrasted with predictions from the standard CDM model and are confronted with observational data.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.