Tue·May 20, 2025Tuesday·May 20, 2025

1. 01*

   Singlet-doublet dark matter revisited

   Prudhvi N. Bhattiprolu🇺🇸 · Evan Petrosky🇺🇸 · Aaron Pierce🇺🇸

   The singlet-doublet model is an economical model of weakly interacting dark matter. We revisit it in light of improved dark matter direct detection limits. We characterize the now well-defined regions of remaining parameter space with suppressed direct detection cross sections and discuss features of the spectrum accessible at the Large Hadron Collider. We discuss when and how parameters in these special regions might be realized as the result of renormalization group evolution when starting with generic ultraviolet initial conditions.

   hep-phPRD(2025)·7 citations
2. 02*

   Probing Lepton Flavor Violation at Linear Electron-Positron Colliders

   Wolfgang Altmannshofer🇺🇸 · Pankaj Munbodh🇺🇸

   The production of $\tau \mu$ pairs in electron-positron collisions offers a powerful probe of lepton flavor violation. In this work, we calculate the $e^{+}{e}^{-}\to \tau \mu$ cross section within the framework of the Standard Model Effective Field Theory, allowing for arbitrary $e^{+}{e}^{-}$ beam polarizations. We then estimate the sensitivities of proposed future linear colliders, ILC and CLIC, to effective lepton flavor-violating interactions. The high center-of-mass energies achievable at these machines provide particularly strong sensitivity to four-fermion operators. Furthermore, the polarization of the $e^{+}{e}^{-}$ beams enables novel tests of the chirality structure of these interactions. We find that our projected sensitivities not only complement but in certain scenarios surpass those achievable with low-energy tau decay measurements at Belle~II.

   hep-phJHEP(2025)·7 citations
3. 03*

   Bayesian Optimization of Pythia8 Tunes

   Ali Al Kadhim🇺🇸 · Harrison B Prosper🇺🇸 · Stephen Mrenna🇺🇸

   A new tune (set of model parameters) is found for the six most important parameters of the Pythia8 final state parton shower and hadronization model using Bayesian optimization. The tune fits the LEPI data from ALEPH better than the default tune in Pythia8. To the best of our knowledge, we present the most comprehensive application of Bayesian optimization to the tuning of a parton shower and hadronization model using the LEPI data.

   hep-phhep-exstat.APPRD(2025)·2 citations
4. 04*

   Quantum tomography beyond the leading order

   J. A. Aguilar-Saavedra🇪🇸

   Quantum tomography, as a tool to probe foundational aspects of quantum mechanics, relies on extracting spin information from angular distributions. This is inherently a leading-order technique, ill-defined when higher-order corrections are significant. For those cases, we propose to treat higher-order corrections as a background, to be modeled and subtracted from data in the same way as other backgrounds are. We illustrate this procedure for Higgs decays $H\to ZZ\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$, which is of high interest for upcoming qutrit entanglement tests at the Large Hadron Collider.

   hep-phhep-exEPJC(2025)·18 citations
5. 05*

   Universal properties of elastic pp cross section from the ISR to the LHC

   Michał Praszałowicz🇵🇱

   We explore the phenomenology of the property that the ratio of bump to dip {\em positions} of the elastic differential $pp$ cross section is constant over the energy range from the ISR to the LHC. We review the old idea of geometric scaling at the ISR and argue that it also holds at the LHC. We discuss its consequences for the $\rho$ parameter and for the ratio of bump to dip cross section {\em values}.

   hep-ph2 citations
6. 06*

   Nonlocal Advantage of Quantum Coherence in Top Quarks

   Saurabh Rai🇮🇳 · Jitendra Kumar🇮🇳

   There is a growing interest in investigating top-quark systems using tools from quantum information theory. A key peculiarity of the top quark is that it decays before hadronization or spin decorrelation occurs, thereby preserving its spin information. This unique property enables direct access to spin correlations, making the top quark an ideal candidate for probing fundamental quantum correlations in high-energy physics processes. A wide range of concepts from quantum information theory, such as entanglement, Bell nonlocality, quantum steering, quantum discord, and fidelity, have been investigated in this context. Several of these measures have been employed as diagnostic tools to test the Standard Model and to search for possible signatures of physics beyond. However, the \textit{nonlocal advantage of quantum coherence} (NAQC) has remained largely unexplored in this context. In this work, we present a detailed investigation of the NAQC in top quark pair production. We employ two complementary NAQC measures based on the $l_1$-norm and the relative entropy of coherence. We also study the effect of angular averaging on these measures and assess the sensitivity of current LHC spin-correlation measurements to NAQC. Our findings reveal rich coherence structures and highlight NAQC as potentially a novel and complementary quantum signature in high-energy physics systems.

   hep-phPRD(2025)·6 citations
7. 07*

   Quantum Entanglement is Quantum: ZZ Production at the LHC

   Dorival Gonçalves🇺🇸 · Ajay Kaladharan🇺🇸 · Frank Krauss🇬🇧 · Alberto Navarro🇺🇸

   Polarization and spin correlations in diboson systems serve as powerful tools for precision tests and searches for new physics. Recently, interpreting these observables through the lens of quantum information, for instance by examining whether the diboson systems exhibit entanglement, has introduced a compelling new dimension to these studies. We analyze the angular coefficients in the processes $pp\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$ and $h\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$, incorporating higher-order QCD and electroweak corrections. Guided by the fundamental properties of the spin density matrix, we assess the stability of the two-qutrit interpretation under radiative effects. For the $pp\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$ process, NLO QCD corrections preserve the two-qutrit structure but weaken entanglement indicators, an effect that can be partially mitigated by jet binning. In contrast, electroweak corrections introduce non-factorizable contributions that modify the quantum properties of the system. While these effects can be largely depleted by selecting events with a double-resonant $ZZ$ structure, such a kinematic handle is not available for Higgs decays. In the $h\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$ channel, singly-resonant NLO electroweak corrections substantially distort the angular coefficients, challenging the description of these events as a two-qutrit system.

   hep-phhep-exquant-phJHEP(2025)·39 citations
8. 08*

   Improved Bounds and Global Fit of Flavor-Violating Charged Lepton Yukawa Couplings post LHC

   Fayez Abu-Ajamieh🇮🇳 · Suman Kumbhakar🇮🇳 · Ratan Sarkar🇮🇳 · Sudhir Vempati🇮🇳

   Higgs couplings to charged leptons form an important measurement to understand not only the Standard Model (SM), but also physics Beyond Standard Models (BSM). In this work, we update the bounds on the Flavor-Violating (FV) Higgs couplings to charged leptons. We find that the bounds on the size of the couplings could range between $\sim \mathcal{O}(10^{-3})-\mathcal{O}(10^{-6})$. In fact, the direct constraints from LHC are much stronger than those inferred indirectly from rare decays in the $\tau$-$\mu$ and $\tau$-$e$ sector. We also match these bounds to the SM Effective Field Theory (SMEFT) and find lower limits on the scale of New Physics (NP). We find that the scale of NP ranges between $\sim \mathcal{O}(10)-\mathcal{O}(100)$ TeV. We also present future projections for some upcoming experiments. We find that the current bounds on the couplings to $\mu$-$e$ are stronger than all future projections.

   hep-phhep-exEPJC(2025)·7 citations
9. 09*

   Comprehensive Constraints on ALP Couplings from future $e^{+}{e}^{-}$ Colliders, Muon $g-2$, Thermal Dark Matter and Higgs Measurements

   Pramod Sharma🇮🇳 · Soham Singh🇿🇦 · Mukesh Kumar🇿🇦 · Ashok Goyal🇮🇳

   In this article, we present projected 95\% C.L. limits on Axion-Like Particle (ALP) couplings from ALP production at a future $e^{+}{e}^{-}$ collider operating at $\sqrt{s}=250\text{GeV}$ with integrated luminosity $L=0.5{\text{ab}}^{-1}$. We constrain the effective couplings $g_{\gamma \gamma }$, $g_{Z\gamma }$, $g_{ZZ}$, and $g_{WW}$ over the ALP mass range $20\text{GeV}\le m_a\le 100\text{GeV}$, finding projected bounds at the level of $\mathcal{O}(10^{-1}){\text{TeV}}^{-1}$ for $g_{\gamma \gamma }/f_a$. Given that the latest muon anomalous magnetic moment measurement ($\Delta a_{\mu }$) shows no statistically significant deviation from the Standard Model prediction, we reinterpret the ALP contributions to $\Delta a_{\mu }$ as a stringent consistency requirement. We then derive the corresponding allowed regions for $g_{\gamma \gamma }$ and the ALP--muon coupling $C_{\mu \mu }$, and apply them to a fermionic dark matter scenario in which the relic density depends on both the dark matter mass $m_{\chi }$ and $m_a$. The same parameter space is further constrained by Higgs signal strength measurements through $h\to \gamma \gamma$ and $h\to Z\gamma$. A comparative analysis with existing experimental and theoretical bounds highlights the complementarity of $\Delta a_{\mu }$, dark matter, and Higgs observables in restricting ALP couplings, demonstrating that even in the absence of a $\Delta a_{\mu }$ anomaly, these constraints provide essential guidance for viable ALP parameter space.

   hep-phEPJC(2026)·3 citations
10. 10*

    Probing new physics in the top sector using quantum information

    Rafael Aoude🇬🇧 · Hannah Banks🇬🇧 · Chris D. White🇬🇧 · Martin J. White🇦🇺

    Recent studies have shown that quantitative concepts from quantum information theory can play a role in analysing collider physics, including elucidating new physics. In this paper, we study various QI measures including magic, trace distance and fidelity distance, in generic new physics scenarios modelled by the Standard Model Effective Field Theory. We argue that such measures can indeed show up differences with respect to the pure Standard Model, and we compare our results with similar findings for the concurrence discussed previously in the literature. We examine the relative sensitivity of different measures to new physics in two-dimensional bins of the top pair invariant mass and scattering angle, finding that the concurrence, magic and trace distance each emerge as the best measure in at least some regions of the phase space. This highlights the importance of exploring multiple quantum information measures in the hunt for beyond the Standard Model physics.

    hep-phhep-exhep-thquant-phPRD(2026)·36 citations
11. 11*

    The Two-Higgs Doublet Model beyond tree-level: A gauge-invariant formalism

    T. Guerandel🇫🇷 · M. Maniatis🇨🇱 · L. Sartore🇫🇷 · I. Schienbein🇫🇷

    Employing the gauge-invariant formalism in the two-Higgs-doublet model (THDM) offers profound insights into the model's fundamental structure. A specific set of gauge-invariant bilinear combinations, constructed from the Higgs doublets, establishes a one-to-one correspondence between the components of the doublet fields and real-valued bilinears. This formalism provides a compact and consistent framework to study various aspects of the THDM, including stability, electroweak symmetry breaking, basis transformations, and general symmetries of the Higgs potential. Recently, the bilinear formalism has been extended beyond the Higgs potential to encompass the full THDM, including the gauge and Yukawa sectors, all in gauge-invariant terms. In this work, we advance the formalism further by incorporating quantum corrections. Specifically, we show how bilinears, combined with the $\hslash$-expansion, can be used to compute one-loop corrections. We provide concise, gauge-invariant expressions for these corrections, which are directly applicable to the THDM.

    hep-phJHEP(2025)·2 citations
12. 12*

    Probing the 3+1 neutrino model in the SHiP experiment

    Ki-Young Choi🇰🇷 · Yu Seon Jeong🇰🇷 · Sung Hyun Kim🇰🇷 · Yeong Gyun Kim🇰🇷 · Kang Young Lee🇰🇷 · Kyong Sei Lee🇰🇷 · Byung Do Park🇰🇷 · Jong Yoon Sohn🇰🇷 · Seong Moon Yoo🇰🇷 · Chun Sil Yoon🇰🇷

    In this study, as an extension of our previous work, we estimate the sensitivity of the Search for Hidden Particles (SHiP) experiment to the 3+1 model using the charged-current deep inelastic scattering event spectrum. We employ the Feldman-Cousins method with a parametric bootstrap to account for nuisance parameters and systematic uncertainties. In the previous study, we proposed a dual baseline approach by suggesting Far SND (FSND) at 120 m with Near SND (NSND) at 27 m. We employ the same approach in this study. The NSND-only configuration can probe mixing parameters of $|U_{\alpha 4}{|}^2\gtrsim 0.1$ near $\Delta m_{41}^2\sim 10^3{\mathrm{eV}}^2$, with a reduction of normalized systematic uncertainties from 20\% to 10\% improving sensitivity by roughly a factor of two. Moreover, the inclusion of FSND significantly enhances the sensitivity by a factor of 2 to 10 depending on the flavor and the systematic uncertainty. In two-flavor mixing scenarios, a cancellation between neutrino appearance and disappearance generates kinks in the sensitivity curves, that are vanished in the dual-baseline approach.

    hep-phhep-exPRD(2025)·1 citation
13. 13*

    Exploring the spectroscopic features of double-strangeness tetraquark states

    Xuejie Liu🇨🇳 · Haoming Zheng🇨🇳 · Dianyong Chen🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

    Since the discovery of the $T_{cc}$ double-charm tetaquark by the LHCb collaboration, the field of the theoretical research on heavy quarks has advanced rapidly, with increasing interest in exploring the light quark sector. In this study, the quark model is employed to systematically analyze the double-strange tetraquark system. Both the meson-meson configuration and diquark-antidiquark configuration are considered. The interactions between hadron pairs under various quantum numbers, as well as the possibilities of bound states and resonances, are evaluated. The results indicate the presence of two bound states, ${\bar{K}}^{\ast }\bar{K}$ and ${\bar{K}}^{\ast }{\bar{K}}^{\ast }$, with quantum number $I(J^P)=0(1^{+})$ in single-channel estimations. Additionally, by considering the channel coupling between the two configurations, a bound state with quantum numbers $I(J^P)=0(1^{+})$ and a mass of approximately $1310$ MeV is obtained. Moreover, through the application of Resonance Ground Method, a resonance state is identified in the $I(J^P)=0(1^{+})$ $\text{ssqq}$ system, with an estimated mass of around 1783 MeV and a decay width of approximately 17 MeV.

    hep-phnucl-thPRD(2026)·1 citation
14. 14*

    Basis light-front quantization approach to deuteron

    Chandan Mondal🇨🇳 · Satvir Kaur🇨🇳 · Jiatong Wu🇨🇳 · Siqi Xu🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

    We obtain the deuteron's wave functions as eigenstates of the light-front quantum chromodynamics (QCD) Hamiltonian using a fully relativistic and nonperturbative approach based on light-front quantization, without an explicit confining potential. These eigenstates include six-quark and six-quark--one-gluon components. The deuteron wave function consists of both a singlet-singlet color state and additional hidden color states arising from non-trivial color rearrangements. Our results reveal that while the singlet-singlet state is present, the hidden color states collectively dominate, contributing a larger probability to the deuteron wave function. This highlights the significant role of hidden color components in the QCD description of nuclear structure. Using these wave functions, we investigate the deuteron's electromagnetic properties.

    hep-phhep-thnucl-thJ.Subatomic Part.Cosmol.(2025)·6 citations
15. 15*

    Modular Symmetry with Weighton

    Gui-Jun Ding🇨🇳 · Stephen F. King🇬🇧 · Jun-Nan Lu🇨🇳 · Ming-Hua Weng🇨🇳

    We systematically develop the weighton mechanism for natural quark and charged lepton mass hierarchies in the framework of modular symmetry with a single modulus field $\tau$. The weighton $\varphi$ is defined as a complete singlet with unit modular weight, leading to fermion mass suppression by powers of $\tilde{\varphi }$, which is the vacuum expectation value of the field scaled by a flavour cut-off. Further mass and mixing angle suppression comes from powers of the small parameter, $q\equiv e^{i2\pi \tau }$. Assuming some fields transform as triplets under the finite modular symmetry, with general assignments for the other fields, we perform a complete analysis for the levels $N=3,4,5$, expressing fermion masses and mixings in terms of powers of the small parameters $\tilde{\varphi }$ and $q$. We present two examples in detail, based on the modular group $T^{\prime }$, close to the CP boundary of $\tau$, which can address both fermion mass and mixing hierarchies using a weighton field.

    hep-phJHEP(2025)·3 citations
16. 16*

    Experimental Particle Physics Priorities 2025: A String Phenomenology Perspective

    Jonathan DeMont🇺🇸 · Alon E. Faraggi🇬🇧 · Mark Goodsell🇫🇷 · Marco Guzzi🇺🇸

    With the SNOWMASS 2021 process in the US and the on--going European Strategy Report 2025, the field of elementary particle physics is undergoing detailed community evaluation, and the experimental particle physics program, which requires substantial public investment, is under scrutiny. We offer an assessment of the current experimental particle physics priorities from a string phenomenology point of view. String theory provides a perturbatively consistent framework for quantum gravity. String phenomenology aims to connect between string theory and observational data. String theory is a consistent theory of quantum gravity that contains the other fundamental constituents of matter and interactions. As all forms of energy couple to gravity, string theory provides a framework that reproduces the structures of the Standard Model of particle physics and gives rise to detailed physics scenarios beyond the Standard Model, {\it e.g.} dark matter candidates, axions, additional gauge symmetries, etc. Given this breadth, we propose that from a string phenomenology perspective, the experimental particle physics priority is the nature of the Higgs boson and the electroweak symmetry breaking mechanism. An ideal facility in the near future to study this sector is a hadron collider at 50--60 TeV that utilises contemporary magnet technology and can be built in 10--15 years from decision.

    hep-phhep-exhep-thPoS(2025)·2 citations
17. 17*

    RGE effects on new physics searches via gravitational waves

    Katsuya Hashino🇯🇵 · Daiki Ueda🇮🇱

    Gravitational wave (GW) observations offer a promising probe of new physics associated with a first-order electroweak phase transition. Precision studies of the Higgs potential, including Fisher matrix analyses, have been extensively conducted in this context. However, significant theoretical uncertainties in the GW spectrum, particularly those due to renormalization scale dependence in the conventional daisy-resummed approach, have cast doubt on the reliability of such precision measurements. These uncertainties have been highlighted using the Standard Model Effective Field Theory (SMEFT) as a benchmark. To address these issues, we revisit Fisher matrix analyses based on the daisy-resummed approach, explicitly incorporating renormalization scale uncertainties. We then reassess the prospects for precise new physics measurements using GW observations. Adopting the SMEFT as a benchmark, we study the effects of one-loop RGE running of dimension-six operators on the Higgs effective potential via the Higgs self-couplings, top Yukawa coupling, and gauge couplings, in addition to the SMEFT tree-level effects. We find that future GW observations can remain sensitive to various dimension-six SMEFT effects, even in the presence of renormalization scale uncertainties, provided that the SMEFT $(H^{†}H{)}^3$ operator is precisely measured, e.g., by future collider experiments.

    hep-phastro-ph.HEhep-exhep-thJHEP(2025)·3 citations
18. 18*

    Fermionic sub-GeV Dark Matter from evaporating Primordial Black Holes at DarkSide-50

    The DarkSide-50 Collaboration: P. Agnes · I. F. Albuquerque · T. Alexander · A. K. Alton · M. Ave · H. O. Back · G. Batignani · K. Biery · V. Bocci · W. M. Bonivento · B. Bottino · S. Bussino and 115 other authors

    We present a search for boosted dark matter from Primordial Black Holes (PBH) evaporation using the DarkSide-50 ionization-signal-only dataset corresponding to the experiment's ($12202\pm 180$) $\mathrm{kg}\mathrm{d}$ exposure. We focus on evaporation of PBHs with masses in the range [$10^{14},10^{16}$] g producing Dirac fermionic dark matter particles with sub-GeV kinetic energy. These relativistic particles, with energies up to hundreds of MeV, can generate detectable signals for masses below $\mathcal{O}(100)$ MeV. The absence of a signal enables setting complementary limits to those derived from cosmological observations and direct detection searches for cosmic ray-boosted dark matter.

    hep-phhep-exhep-thPRD(2025)·4 citations
19. 19*

    Fully Differential Soft Gluon Evolution at the Amplitude Level

    Jeffrey R. Forshaw🇬🇧 · Simon Plätzer🇦🇹 · Fernando Torre González🇬🇧

    We study differential intra-jet radiation patterns in jet production at full colour. We present a systematic study of several QCD $2\to 2$ processes and also multi-jet production from a colourless initial state. We examine how subleading colour corrections are distributed differentially in phase space and find that mere normalization effects due to subleading colour can be due to subtle cancellations across phase space. In general, we find that subleading colour does affect the shapes of distributions.

    hep-phJHEP(2025)·11 citations
20. 20*

    Sensitivity to New Physics Phenomena in Anomaly Detection: A Study of Untunable Hyperparameters

    Fernando Abreu de Souza🇵🇹 · Maura Barros🇵🇹 · Nuno Filipe Castro🇵🇹 · Miguel Crispim Romão🇬🇧 · Céu Neiva🇵🇹 · Rute Pedro🇵🇹

    The search for physics beyond the Standard Model (BSM) at collider experiments requires model-independent strategies to avoid missing possible discoveries of unexpected signals. Anomaly detection (AD) techniques offer a promising approach by identifying deviations from the Standard Model (SM) and have been extensively studied. The sensitivity of these methods to untunable hyperparameters has not been systematically compared, however. This study addresses it by investigating four semi-supervised AD methods -- Auto-Encoders, Deep Support Vector Data Description, Histogram-based Outlier Score, and Isolation Forest -- trained on simulated SM background events. In this paper, we study the sensitivity of these methods to BSM benchmark signals as a function of these untunable hyperparameters. Such a study is complemented by a proposal of a non-parametric permutation test using signal-agnostic statistics, which can provide a robust statistical assessment.

    hep-phhep-exphysics.data-anPRD(2026)·2 citations
21. 21*

    Probing the ${\Lambda }_b\to {\Lambda }_c^{\ast }\tau {\bar{\nu }}_{\tau }$ decays with leptoquarks

    C P Haritha🇮🇳 · Karthik Jain🇮🇳 · Barilang Mawlong🇮🇳

    The extension of the standard model to include a single scalar or vector leptoquark has been shown to account for the observed deviations in the lepton flavor universality ratios in the $b\to c\ell {\nu }_{\ell }$ and $b\to s\ell \ell$ transitions. Exploring new physics in the $b\to c\tau {\nu }_{\tau }$ decays, in this work we analyze the baryonic decay channels ${\Lambda }_b\to {\Lambda }_c^{\ast }(2595,2625){\tau }^{-}{\bar{\nu }}_{\tau }$ beyond the standard model. Specifically, we investigate the role of leptoquarks in these decays, focusing on the $U_1$ vector leptoquark and the $S_1$ scalar leptoquark. Employing recent lattice QCD results for the ${\Lambda }_b\to {\Lambda }_c^{\ast }$ form factors, the helicity amplitudes for all possible four-fermion interactions are worked out explicitly and presented here. Utilizing the current $b\to c\ell {\nu }_{\ell }$ experimental data, we impose constraints on the leptoquark couplings and test new physics sensitivity of various observables for the decay processes under consideration. Our analysis demonstrates the significance of testing the lepton flavor universality ratio $R_{{\Lambda }_c^{\ast }}$ as it is observed to be particularly sensitive to these leptoquarks.

    hep-ph0 citations
22. 22*

    Scaling laws for softened hadron production at LHC energies

    D. Rosales Herrera🇲🇽 · J. R. Alvarado García🇲🇽 · A. Fernández Téllez🇲🇽 · E. Cuautle🇲🇽 · J. E. Ramírez🇲🇽

    In this paper, we conduct a data-driven study of the production of softened hadrons and their contribution to the transverse momentum spectrum. To this end, we assume that the production of charged particles at soft and hard scales fundamentally results from the fragmentation of color strings. We analyze the $p_{\text{T}}$-spectrum data from pp to AA collisions at LHC energies reported by the ALICE Collaboration, finding that, in all cases, the data can be collapsed into a $p_{\text{T}}$-exponential trend in the range 1 GeV$<p_{\text{T}}<$6 GeV. With this insight, the description of the $p_{\text{T}}$-spectrum should contain information on the charged particle production coming from two different sources: fragmentation of color strings and collective phenomena that redistribute the transverse momentum and enhance the production of particles at intermediate $p_{\text{T}}$. We also found different relations between the effective temperature, multiplicity, and average $p_{\text{T}}$ for pp and AA collisions, indicating inherent dissimilarities between small and large colliding systems. In contrast, the contribution of the softened hadrons to the $p_{\text{T}}$-spectrum and average $p_{\text{T}}$ collapse onto scaling laws. Our results show that the physical mechanisms producing softened hadrons have similar origins for all colliding systems, revealing a stronger dependence on freeze-out parameters rather than the system size.

    hep-phEPJC(2025)·4 citations
23. 23*

    Constraining Reheating Temperature, Inflaton-SM Coupling and Dark Matter Mass in Light of ACT DR6 Observations

    Rajesh Mondal🇮🇳 · Sourav Mondal🇮🇳 · Ayan Chakraborty🇮🇳

    We explore the phenomenological implications of the latest Atacama Cosmology Telescope (ACT) DR6 observations, in combination with Planck 2018, BICEP/Keck 2018, and DESI, on the physics of inflation and post-inflationary reheating. We focus on the $\alpha$-attractor class of inflationary models (both E- and T-models) and consider two reheating scenarios: perturbative inflaton ($\varphi$) decay ($\varphi \to bb$) and inflaton annihilation ($\varphi \varphi \to bb$) into Standard Model (SM) bosonic particles ($b$). By solving the Boltzmann equations, we derive bounds on key reheating parameters, including the reheating temperature, the inflaton equation of state (EoS), and the inflaton-SM coupling, in light of ACT data. To accurately constrain the coupling, we incorporate the Bose enhancement effect in the decay width. To ensure the validity of our perturbative approach, we also identify the regime where nonperturbative effects, such as parametric resonance, become significant. Additionally, we include indirect constraints from primordial gravitational waves (PGWs), which can impact the effective number of relativistic species, $\Delta N_{\mathrm{eff}}$. These constraints further bound the reheating temperature, particularly in scenarios with a stiff EoS. Finally, we analyze dark matter (DM) production through purely gravitational interactions during reheating and determine the allowed mass ranges consistent with the constrained reheating parameter space and recent ACT data.

    hep-phastro-ph.COhep-thJCAP(2026)·37 citations
24. 24*

    Building Next-to-Next Leading Logarithmic parton showers: the PanScales recipe

    Silvia Ferrario Ravasio🇨🇭

    Parton showers lie at the core of Shower Monte Carlo event generators, the default theoretical tools used to interpret collider data. In these proceedings, we summarise the strategy of the PanScales collaboration that led to the attainment of the first demonstrably next-to-next-to-leading-logarithmic accurate parton showers.

    hep-ph4 citations
25. 25*

    An Improvement of AmpRed: Analytic Continuation of Complex Integrals

    Wen Chen🇨🇳

    The AmpRed package has been updated with an improved method for analytic continuation of complex integrals. Compared to the previous version, the new implementation significantly enhances computational efficiency for evaluating complex integrals.

    hep-phhep-thnucl-th6 citations
26. 26*

    Single arm interferometry to probe the scalar field dark matter

    Antonio Capolupo🇮🇹 · Gabriele Pisacane🇮🇹 · Aniello Quaranta🇮🇹 · Raoul Serao🇮🇹

    We analyse the interaction of photons with a scalar dark matter field \phi and we propose to use a single arm interferometer to reveal this interaction and constrain the parameters of the scalar dark matter model. By considering a beam of coherent light and two spatially separated squeezing operations, we show that the interaction of photons with scalar dark matter leads to an observable deviation in the outgoing light state, with respect to free evolution. Therefore the single arm interferometer may yield a novel revelation method for scalar dark matter.

    hep-phPRD(2026)·5 citations
27. 27*

    Fantômas: epistemic and nuclear uncertainties for the parton distributions of the pion

    Lucas Kotz🇺🇸 · Aurore Courtoy🇲🇽 · Pavel Nadolsky🇺🇸 · Maximiliano Ponce-Chavez🇺🇸

    We present Fanto10, a new ensemble of NLO error parton distribution functions (PDFs) in a charged pion that provides the most detailed estimate of uncertainties from experimental, theoretical, and methodological sources in order to enable faithful comparisons against upcoming precision experiments and ab initio QCD predictions. For the first time, the Fanto10 PDFs quantify two important types of uncertainties, arising from in-depth exploration of feasible functional forms of pion PDFs and from the nuclear PDFs describing the internal composition of the tungsten target in the key E615 data set for pion-nuclear Drell-Yan process. Accounting for these uncertainties modifies physics conclusions of more restrictive analyses about the pion's gluon and quark sea composition. These advancements are made by employing the recently developed C++ framework Fantômas for systematic exploration of epistemic sources of PDF uncertainties, such as those arising from the choice of the PDF functional forms and sampling over methodological choices and third-party inputs, e.g., the nuclear PDF uncertainty in the presented case. The framework employs polynomial universal approximators (Bézier curves) to parametrize diverse PDF functional forms and reduce biases associated with the PDF parametrization choice. Its other component combines PDF ensembles from multiple preliminary fits into a single published ensemble of Hessian error PDFs. We review key steps of the Fantômas methodology, properties of Fanto10 PDFs, and implications for future studies.

    hep-phPRD(2025)·18 citations
28. 28*

    Dark Matter in an Evanescent Three-Brane Randall-Sundrum Scenario

    Andrea Donini🇪🇸 · Miguel G. Folgado🇪🇸 · Juan Herrero-García🇪🇸 · Giacomo Landini🇪🇸 · Alejandro Muñoz-Ovalle🇪🇸 · Nuria Rius🇪🇸

    Apart from its gravitational interactions, dark matter (DM) has remained so far elusive in laboratory searches. One possible explanation is that the relevant interactions to explain its relic abundance are mainly gravitational. In this work we consider an extradimensional Randall-Sundrum scenario with a TeV-PeV IR brane, where the Standard Model is located, and a GeV-TeV deep IR (DIR) one, where the DM lies. When the curvatures of the bulk to the left and right of the IR brane are very similar, the tension of the IR brane is significantly smaller than that of the other two branes, and therefore we term it \evanescent". In this setup, the relic abundance of DM arises from the freezeout mechanism, thanks to DM annihilations into radions and gravitons. Focusing on a scalar singlet DM candidate, we compute and apply current and future constraints from direct, indirect and collider-based searches. Our findings demonstrate the viability of this scenario and highlight its potential testability in upcoming experiments. We also discuss the possibility of inferring the number of branes if the radion and several Kaluza-Klein graviton resonances are detected at a future collider.

    hep-phJHEP(2025)·7 citations
29. 29*

    Sampling NNLO QCD phase space with normalizing flows

    Timo Janßen🇩🇪 · Rene Poncelet🇵🇱 · Steffen Schumann🇩🇪

    We showcase the application of neural importance sampling for the evaluation of NNLO QCD scattering cross sections. We consider Normalizing Flows in the form of discrete Coupling Layers and time continuous flows for the integration of the various cross-section contributions when using the sector-improved residue subtraction scheme. We thereby consider the stratification of the integrands into their positive and negative contributions, and separately optimize the phase-space sampler. We exemplify the novel methods for the case of gluonic top-quark pair production at the LHC at NNLO QCD accuracy. We find significant gains with respect to the current default methods used in STRIPPER in terms of reduced cross-section variances and increased unweighting efficiencies. In turn, the computational costs for evaluations of the integrand needed to achieve a certain statistical uncertainty for the cross section can be reduced by a factor 8.

    hep-phJHEP(2025)·24 citations
30. 30*

    Quintessence Dark Energy from non-perturbative Higgs-Yang-Mills mass gap

    Marco Frasca🇮🇹 · Anish Ghoshal🇵🇱 · Massimiliano Rinaldi🇮🇹

    We discuss the equations that arise from a Higgs--Yang-Mills dark sector coupled to gravity on a flat Friedmann-Lemaitre-Robinson-Walker metric. We choose the simplest $SU(2)$ representation, which we show to be compatible with the Cosmological Principle. We devise a multiple time scale approach to solve the equations of motion through a hierarchy of the couplings, utilizing exact solutions in terms of Jacobi elliptic functions. This novel method implements the dynamical system approach used in the literature and can shed new light on the possibility that this model can describe dark energy.

    ↳ astro-ph.COgr-qchep-phhep-thEur.Phys.J.Plus(2026)·3 citations
31. 31*

    Probing Nuclear Geometry through Multi-Particle Azimuthal Correlations and Rapidity-Even Dipolar Flow in ${}^{16}$O+${}^{16}$O Collisions

    Kaiser Shafi🇮🇳 · Sandeep Chatterjee🇮🇳

    We study symmetric and asymmetric cumulants as well as rapidity-even dipolar flow in ${}^{16}$O+${}^{16}$O collisions at $\sqrt{s_{NN}}=200$~GeV to explore $\alpha$-clustering phenomena in light nuclei within the viscous relativistic hydrodynamics framework. Signatures of $\alpha$-clustering manifest in the anisotropic flow coefficients and their correlations -- particularly in observables involving elliptic-triangular flow correlations. We show that final-state symmetric and asymmetric cumulants -- especially $\mathrm{NSC}(2,3)$ and ${\mathrm{NAC}}_{2,1}(2,3)$ -- are sensitive to the initial nuclear geometry. Additionally, we observe a significant difference in rapidity-even dipolar flow, $v_1^{\text{even}}$, between $\alpha$-clustered and Woods--Saxon configurations in high-multiplicity events. These findings underscore the pivotal role of nuclear structure in heavy-ion collision dynamics and provide observables for distinguishing nuclear geometries, particularly in ultra-central collisions.

    ↳ nucl-thhep-phEPJC(2026)·6 citations
32. 32*

    Efficient lattice QCD computation of radiative-leptonic-decay form factors at multiple positive and negative photon virtualities

    Davide Giusti🇩🇪 · Christopher F. Kane🇺🇸 · Christoph Lehner🇩🇪 · Stefan Meinel🇺🇸 · Amarjit Soni🇺🇸

    In previous work Phys. Rev. D 107, 074507 (2023), we showed that form factors for radiative leptonic decays of pseudoscalar mesons can be determined efficiently and with high precision from lattice QCD using the ``3d method,'' in which three-point functions are computed for all values of the current-insertion time and the time integral is performed at the data-analysis stage. Here, we demonstrate another benefit of the 3d method: the form factors can be extracted for any number of nonzero photon virtualites from the same three-point functions at no extra cost. We present results for the $D_s\to \ell \nu {\gamma }^{\ast }$ vector form factor as a function of photon energy and photon virtuality, for both positive and negative virtuality. In our analysis, we separately consider the two different time orderings and the different quark flavors in the electromagnetic current. We discuss in detail the behavior of the unwanted exponentials contributing to the three-point functions, as well as the choice of fit models and fit ranges used to remove them for various values of the virtuality. While positive photon virtuality is relevant for decays to multiple charged leptons, negative photon virtuality suppresses soft contributions and is of interest in QCD-factorization studies of the form factors.

    ↳ hep-lathep-phPRD(2025)·7 citations
33. 33*

    Effective interaction of Chern-Simons boson with fermions

    Ivan Hrynchak🇺🇦 · Oleksandr Khasai🇺🇦 · Yuliia Borysenkova🇪🇸 · Mariia Tsarenkova🇺🇦 · Volodymyr Gorkavenko🇺🇦

    We consider a vector extension of the Standard Model (SM) with a Chern-Simons-type interaction. This extension introduces a new massive vector boson (the Chern-Simons (CS) boson) that does not couple directly to SM fermions at tree level. We analyze the effective loop-induced interaction of this new vector boson with SM fermions and study its renormalizability in the $R_{\xi }$ gauge. We find that, in the effective interaction between the CS boson and same-flavor fermions, the divergent contributions from individual loop diagrams do not cancel when all relevant diagrams are taken into account. In contrast, for interactions involving fermions of different flavors, the corresponding loop-induced contributions are finite and well-defined. This indicates that, in the low-energy limit, the theory exhibits nonrenormalizable behavior in the sector describing the loop-induced interaction of the CS boson with same-flavor fermions. The interaction terms between the CS boson and same-flavor fermions, characterized by divergent coefficients, are identified and must be treated within the framework of effective field theory. Finally, we derive the leading-order effective Lagrangian describing the interaction of a GeV-scale CS boson with SM fermions and discuss the number of independent parameters entering this Lagrangian. The leading-order interaction we obtained turns out to be similar to the interaction of a $Z^{\prime }$ boson with SM fermions.

    ↳ hep-thhep-phNPB(2026)·0 citations
34. 34*

    Holographic composite Higgs model and gravitational waves produced during first order phase transition

    Andrey A. Shavrin🇷🇺

    The soft-wall holographic composite Higgs model assumes first-order phase transition from the dynamical inner symmetry breaking. This research focuses on the implications of the semi-analytical perturbative solution of the dual 5-dimensional theory as an effective description of the strongly coupled composite Higgs sector. We clarify the thermodynamical description and gravitational waves spectrum produced during the phase transition, which were previously numerically estimated. Besides, we investigate the limits of the applicability of our solution within the thin-wall approximation and quasiclassical approach in terms of the dual theory, that correspond to the strongly coupled regime of composite Higgs model. Our semi-analytic framework provides description of the strong first-order phase transition within the runaway scenario.

    ↳ hep-thgr-qchep-phJCAP(2026)·0 citations
35. 35*

    Lecture Notes: WISPs in gamma-ray astrophysics

    Francesca Calore🇫🇷 · Christopher Eckner🇸🇮

    These lecture notes provide an overview of high-energy astrophysical processes involving axions, axion-like particles (ALPs), and other weakly interacting slim particles (WISPs) focusing on their potential observational signatures in astrophysical environments. After introducing key concepts in high-energy astrophysics, we present the fundamental properties of WISPs, emphasizing their phenomenological implications. Particular attention is given to ALP-photon conversion in strong magnetic fields and the possible decay signatures of ALPs in sources such as active galactic nuclei, galaxy clusters, and cosmic-ray accelerators. These effects can lead to distinctive modifications in astrophysical spectra, spatial distributions, and polarization patterns, providing unique probes of physics beyond the Standard Model. We discuss their role in dark matter scenarios and their potential impact on high-energy observations. The lecture series is supplemented by hands-on tutorials, including exercises on axion electrodynamics and an analysis of gamma-ray data from NGC 1275 to search for ALP-photon conversion signatures.

    ↳ astro-ph.HEhep-phPoS(2025)·2 citations
36. 36*

    Study of the hottest droplet of fluid through correlations and fluctuations of collective variables

    Rupam Samanta🇵🇱

    In this thesis, we focus on the fluctuations and correlations of the collective observables such as the mean transverse momentum per particle ($[p_T]$) and harmonic flow coefficients ($v_n$) of particles produced in the ultrarelativistic heavy-ion collisions at RHIC and the LHC. Specifically, we show that the fluctuations of harmonic flow can be probed by the factorization-breaking coefficients between flow vectors in different $p_T$-bins. Experimental difficulty can be reduced by taking one of the flow vectors momentum averaged. Fluctuations cause a decorrelation between the flow vectors, which can be attributed to equal contributions from the flow magnitude and flow angle decorrelation. We study fluctuations of mean transverse momentum per particle ($[p_T]$) in ultra-central collisions and show that our model can explain the steep fall of its variance observed by the ATLAS collaboration. We also present robust predictions for the skewness and kurtosis, and highlight the role of impact parameter fluctuations in ultracentral collisions. We study the Pearson correlation coefficients between $[p_T]$ and $v_n^2$, which can map the initial state correlations between the shape and size of the fireball. We show that higher order normalized and symmetric cumulants between these observables can be constructed, which put useful additional constraints on the initial state properties. Furthermore, we study the momentum dependent Pearson correlation between $[p_T]$ and the transverse momentum dependent flow. It shows sensitivity to the Gaussian width of the nucleon at the initial state. Finally, we show that such correlations and fluctuations of collective observables can be used to study nuclear deformation and put robust constraints on their deformation parameters through high energy nuclear collisions.

    ↳ nucl-thhep-ph1 citation
37. 37*

    Conditions for Quantum Violation of Macrorealism in Large-spin Limit

    Qi-Hong Cai · Xue-Hao Yu · Ma-Cheng Yang · Ao-Xiang Liu🇨🇳 · Cong-Feng Qiao🇨🇳

    This study investigates the emergence of macroscopic classical behavior from quantum foundations via the entropic Leggett--Garg inequality. We introduce a geometric framework for deriving entropic Leggett--Garg inequalities with higher-order temporal correlations and demonstrate their advantages over conventional formulations. Numerical analyses show that entropic Leggett--Garg inequalities offer a robust and complementary criterion to standard approaches, providing a transparent information theoretic interpretation that facilitates the characterization of coherent quantum processes. By applying the WKB approximation, we prove that violations for maximally mixed states remain bounded by a constant in the macroscopic limit, indicating that macrorealism dominates in generic parameter regimes. We further explain previously reported maximal violations at specific parameter regimes as a consequence of the breakdown of the WKB approximation. Our findings indicate that quantum and classical descriptions remain macroscopically incompatible, while violations persist only in fine-tuned regimes, clarifying the conditions for detecting macroscopic quantum phenomena.

    ↳ quant-phhep-ph0 citations
38. 38*

    Topology and the Infrared Structure of Quantum Electrodynamics

    J. Gamboa🇨🇱

    We study infrared divergences in quantum electrodynamics using geometric phases and the adiabatic approximation in quantum field theory. In this framework, the asymptotic \textit{in} and \textit{out} states are modified by Berry phases, $e^{i\Delta {\alpha }_{\text{in}}}$ and $e^{i\Delta {\alpha }_{\text{out}}}$, which encode the infrared structure non-perturbatively and regulate soft-photon divergences. Unlike the Faddeev--Kulish formalism, which employs perturbative dressing with coherent states, our approach reformulates the effective action in terms of Berry connections in field space. This yields finite, gauge-invariant scattering amplitudes without requiring a sum over soft-photon emissions. We show that infrared divergences cancel to all orders in the bremsstrahlung vertex function ${\Gamma }^{\mu }(p_1,p_2)$, due to destructive interference among inequivalent Berry phases. As an application, we study the formation of positronium in the infrared regime and argue that the dressed \(S\)-matrix exhibits a functional singularity at $s=4m_e^2$, corresponding to a physical pole generated by topological flux.

    ↳ hep-thhep-phJHEP(2025)·12 citations
39. 39*

    First Nucleon Gluon PDF from Large Momentum Effective Theory

    William Good🇺🇸 · Fei Yao🇺🇸 · Huey-Wen Lin🇺🇸

    We report the first nucleon gluon parton distribution function (PDF) using Large-Momentum Effective Theory (LaMET). We focus on the gluon operator which was demonstrated to have the best signal-to-noise in the previous attempt [1] in computing gluon PDFs using LaMET. We compute the corresponding Wilson coefficients needed for the hybrid-renormalized matrix elements and the matching kernel to convert the quasi-PDF to the lightcone one at the one-loop level. We demonstrate that with the proper Wilson coefficients in place, the counterterms for the renormalization are independent of the hadron and mass within statistical error. Using the resulting renormalization, we then compute the nucleon PDF using a HISQ ensemble generated by the MILC collaboration with $N_f=2+1+1$, $a\approx 0.12$ fm, with valence pion masses of 310 and 690 MeV and two gauge link smearing techniques. Despite the physics effects of the heavier than physical pion masses and gauge link smearing, this calculation provides excellent proof of principle and compares reasonably with selected global fit results.

    ↳ hep-lathep-phPLB(2026)·14 citations
40. 40*

    Scalar-Induced Gravitational Waves in Palatini $f(R)$ Gravity

    Samuel Sánchez López🇮🇳 · José Jaime Terente Díaz🇵🇹

    Primordial scalar perturbations that reenter the horizon after inflation may induce a second-order Gravitational Wave spectrum with information about the primordial Universe on scales inaccessible to Cosmic Microwave Background experiments. In this work, we develop a general framework for the study of Scalar-Induced Gravitational Waves in Palatini $f(R)$ gravity, a theory that was proven to successfully realise inflation and quintessence, and consider the case of the Starobinsky-like model as an example. A regime of radiation domination with a subdominant matter component is assumed, allowing for a well-motivated perturbative approach to the gravity modifications. We calculate the kernel function and the density spectrum numerically and find accurate analytical expressions. The spectral density, which may be tested across a wide range of frequencies by upcoming Gravitational Wave experiments, is shown to differ from the General Relativity and metric $f(R)$ gravity predictions under certain conditions. We comment on previous results in the literature regarding the metric formulation and make special emphasis on the potential of these distinctive features of the spectrum to probe the two formalisms of gravity.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·16 citations
41. 41*

    Wonderings on Wiggly Bispectra: Non-linear Evolution and Reconstruction of Oscillations in the Squeezed Bispectrum

    Samuel Goldstein🇺🇸 · Oliver H. E. Philcox🇺🇸 · Emanuele Fondi🇪🇸 · William R. Coulton🇬🇧

    Oscillations in the primordial bispectrum are sourced by a range of inflationary phenomena, including features in the inflaton potential and interactions with massive fields through the Cosmological Collider scenario. These signatures offer a powerful window into early-universe physics. In this work, we study how oscillations of the form ${\lim }_{q\ll k}B(q,k)\propto \cos (\mu \ln (q/k))$ impact the non-linear squeezed matter bispectrum. Using a suite of $N$-body simulations with non-Gaussian initial conditions, we show that non-linear evolution significantly damps these oscillations, effectively erasing the signal on scales $k\gtrsim 0.3h/\mathrm{Mpc}$ at redshift $z=0$. This damping is well-described by the Zel'dovich approximation and can be modeled deep into the non-linear regime using non-perturbative separate universe simulations. Promisingly, we show that reconstruction techniques developed for baryon acoustic oscillation (BAO) analyses can largely undo this damping, improving constraints on the amplitude (phase) of oscillations in the primordial squeezed bispectrum by up to a factor of five (four) at $z=0$. We also discuss several challenges with modeling the non-linear evolution of the squeezed bispectrum in the Cosmological Collider scenario, where the bispectrum is suppressed by a factor of $(q/k{)}^{3/2}$ relative to the template studied here. Our findings pave the way for future searches for oscillatory bispectra using large-scale structure data.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·14 citations
42. 42*

    Modeling Galaxy Surveys with Hybrid SBI

    Gemma Zhang · Chirag Modi🇺🇸 · Oliver H. E. Philcox🇺🇸

    Simulation-based inference (SBI) has emerged as a powerful tool for extracting cosmological information from galaxy surveys deep into the non-linear regime. Despite its great promise, its application is limited by the computational cost of running simulations that can describe the increasingly-large cosmological datasets. Recent work proposed a hybrid SBI framework (HySBI), which combines SBI on small-scales with perturbation theory (PT) on large-scales, allowing information to be extracted from high-resolution observations without large-volume simulations. In this work, we lay out the HySBI framework for galaxy clustering, a key step towards its application to next-generation datasets. We study the choice of priors on the parameters for modeling galaxies in PT analysis and in simulation-based analyses, as well as investigate their cosmology dependence. By jointly modeling large- and small-scale statistics and their associated nuisance parameters, we show that HySBI can obtain 20\% and 60\% tighter constraints on ${\Omega }_m$ and ${\sigma }_8$, respectively, compared to traditional PT analyses, thus demonstrating the efficacy of this approach to maximally extract information from upcoming spectroscopic datasets.

    ↳ astro-ph.COastro-ph.GAastro-ph.IMgr-qc+1PRD(2026)·4 citations

* 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.