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Physics High Energy Physics (Phenomenology)

hep-ph Watch High Energy Physics (Phenomenology)

Monday 31 August

High Energy Physics (Phenomenology)

Exclusive Leptonium Electroproduction

Hao-ye Deng, Qi-Ming Feng, Qi-Wei Hu et al. (+8 more)

Purely leptonic bound states provide precision probes of QED. Positronium $(e^+e^-)$ and muonium $(\mu^+e^-)$ have long been observed, whereas dimuonium $(\mu^+\mu^-)$ and tauonium $(\tau^+\tau^-)$ remain undiscovered. We study exclusive vector-leptonium electroproduction in $ep$ collisions within nonrelativistic QED. We include the Bethe–Heitler and double deeply virtual Compton scattering contributions and their interference, and calculate the NLO QCD hard-scattering kernels entering the dominant Compton form factor $\Hcal$ within collinear GPD factorization. The NLO QCD correction to the DDVCS contribution changes from a strong suppression at low photon virtuality to a sizable enhancement as the lower virtuality cut is raised, with the gluon channel providing the dominant contribution. Bethe–Heitler production dominates the exclusive rate, supporting dedicated dimuonium searches at the EIC and JLab, with larger samples expected at higher-energy electron–proton colliders. The much larger positronium samples provide a high-statistics environment for precision QED studies, whereas tauonium production remains strongly suppressed.
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All authors Hao-ye Deng, Qi-Ming Feng, Qi-Wei Hu, Si-Qin Huang, Cong-Feng Qiao, Jia-Xuan Shen, Ting-Ting Wang, Shun-Yan Yu, Hao Zhang, Xuan-Heng Zhang, Yi-Nan Zhao

High Energy Physics (Phenomenology) · Cross-listed from hep-lat

$D \to (K \pi)_{\mathbf{27}}$ at the SU(3)-flavour-symmetric point I: Methodology and strong phase determination

Matthew Black, Felix Erben, Maxwell T. Hansen et al. (+5 more)

We present part one of an SU(3)-flavour-symmetric lattice QCD calculation of the amplitude for a $D$-meson decaying to a $K\pi$ final state in the 27-dimensional irreducible representation of the flavour symmetry group, denoted $(K\pi)_{\mathbf{27}}$. The Wilson–clover gauge ensembles used in this work, generated by the OpenLat collaboration, are tuned such that $M_\pi = M_K \approx 410\,\mathrm{MeV}$. Using the distillation framework, we construct a matrix of Euclidean correlation functions from pairs of single-hadron operators projected to definite spatial momentum. Solving a generalised eigenvalue problem yields the finite-volume energy spectrum that is used to determine the scattering phase shift from threshold up to $4 M_\pi \approx 1640 \,\mathrm{MeV}$, which sits below but plausibly within reach of $M_D^{\rm SU(3)} \simeq 1900\,\mathrm{MeV}$. The calculation is performed across three lattice spacings, and we apply two strategies in which the continuum limit is taken at different stages of the computation: (i) on the extracted scattering parameters and (ii) on the finite-volume energies at fixed physical volume before extracting the scattering parameters. We find consistent results across these methods for the scattering phase shift as a function of the centre-of-mass energy, $\delta_{\mathbf{27}}(E_{\sf cm})$. Taking a scattering-length-only parametrisation, we infer a value for the strong phase of the weak decay, $\delta_{\mathbf{27}}(M_D^{\rm SU(3)})=-38.4(2.4)^\circ$. We further describe the methodology for using the same operator basis to compute three-point correlation functions to extract $\langle (K\pi)_{\mathbf{27}}| H_W| D\rangle$, for the tree-level effective weak Hamiltonian $H_W$, and for relating such finite-volume matrix elements to the full decay amplitude. The complete analysis leading to the latter will be presented in a forthcoming manuscript.
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All authors Matthew Black, Felix Erben, Maxwell T. Hansen, Fabian Joswig, Nelson Pitanga Lachini, Rajnandini Mukherjee, Srijit Paul, Antonin Portelli

High Energy Physics (Phenomenology)

Small-x TMD distributions: JIMWLK evolution and the Gaussian truncation

Florian Cougoulic and Piotr Korcyl

We extend the systematic study of small-$x$ Transverse Momentum Dependent (TMD) distributions, initiated in [Cougoulic:2026drr], by including the energy evolution. We use the JIMWLK evolution equation to study the energy dependence of three distributions in the quark-gluon sector, $\mathcal{F}_{qg}$, and seven distributions in the gluon-gluon sector, $\mathcal{F}_{gg}$. The initial conditions are provided by the McLerran-Venugopalan model. We study these TMD distributions in position space and with $N_c = 3$ fixed. We then compare these results to the Gaussian truncation of the Balitsky hierarchy. Although the Gaussian truncation worked very well for the TMD distributions at the initial condition, now we identify some cases where the Gaussian truncation provides a reasonably good description, but in the majority of cases it fails to fully reproduce numerical data. Using the fixed representation building blocks, $\Omega_{ag}^\omega$, we are able to partially explain the outcomes. This work constitutes the next step with the goal of understanding the interplays between the large-$N_c$ limit and Gaussian truncation as well as the BK/JIMWLK evolution equations for phenomenologically relevant observables.
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High Energy Physics (Phenomenology)

Hadron interactions in the U-70 energy range: results and problems

V. A. Petrov and N. P. Tkachenko

From late 1967 until the early 1970s, the Soviet proton synchrotron (better known as the Serpukhov accelerator or U-70), with a nominal laboratory energy of up to 76 GeV, was the world leader. During these few years, several results of fundamental significance were obtained (partially in collaboration with physicists from CERN, France, and other countries). Let us briefly outline the main provisions of the paradigm that reigned at that time in the field of strong interaction theory.
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High Energy Physics (Phenomenology) · Cross-listed from nucl-th

NS-UNO: Neutron Star EoS Inference from an Unconstrained Number of Observations

Valéria Carvalho, Márcio Ferreira, Michał Bejger et al. (+1 more)

Future multimessenger observations of neutron stars (NS) are expected to substantially increase both the number and precision of astrophysical constraints on the equation of state (EoS) of dense matter. This motivates inference frameworks capable of accommodating a variable, non fixed number of observations while preserving the posterior information associated with each measurement. In this work, we introduce NS-UNO, a Neural Posterior Estimation framework for NS EoS inference designed to accommodate an Unconstrained Number of Observations (UNO). NS-UNO combines a hierarchical DeepSets model with a conditional normalising flow, enabling a single trained model to perform inference from mass-radius observation sets of varying size, with each observation represented by a set of posterior samples. We demonstrate accurate and well calibrated posterior reconstructions using a model trained jointly on piecewise polytropic and non-parametric Gaussian process EoS ensembles. The reconstruction improves as observations probe a broader range of NS masses, while remaining robust to variations in the number and precision of the observations. The model also generalises to EoSs outside the families used during training. Finally, we qualitatively demonstrate the framework on current multimessenger constraints from NICER and GW170817. NS-UNO provides a flexible and scalable approach to NS EoS inference, naturally suited to the increasingly diverse observational datasets expected from next generation multimessenger astronomy.
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All authors Valéria Carvalho, Márcio Ferreira, Michał Bejger, Constança Providência

High Energy Physics (Phenomenology) · Cross-listed from astro-ph.HE

Cascades from ultra-high-energy neutrinos

Gaetano Di Marco, Rhorry Gauld, Rafael Alves Batista et al. (+2 more)

Neutrinos produced at the highest energies can interact with cosmic neutrino and radiation backgrounds during their propagation to Earth. The many available $\nu\nu$, $\nu\bar{\nu}$, and $\nu\gamma$ channels can lead to their absorption or energy redistribution, whilst the leptonic and hadronic final states may feed secondary fluxes of neutrinos, protons, and electromagnetic particles through the decay or hadronisation of the heavy leptons, bosons, and quarks produced. We present a framework to characterise these propagation effects in detail, \texttt{$\nu$propa}, an extension of the CRPropa Monte Carlo code that interfaces with event generators and to dedicated computations of the relevant cross sections. It also treats flavour oscillations in vacuum. Using this code, we investigate sources at high redshifts ($z = 10$), and find a strong absorption of the prompt flux beyond~$\sim 10^{21} \; \text{eV}$, although the copious secondary neutrinos partially compensate this depletion, also contributing to the spectrum at lower energies. The framework is designed to study scenarios of cosmological neutrino production beyond~EeV energies such as superheavy dark matter, cosmic strings, and primordial black holes, and to yield reliable predictions for the forthcoming neutrino observatories.
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All authors Gaetano Di Marco, Rhorry Gauld, Rafael Alves Batista, Alfonso García-Soto, Miguel Á. Sánchez-Conde

High Energy Physics (Phenomenology)

Charmonium production in p+A collisions at SPS and FAIR energies

Taesoo Song, Jiaxing Zhao, Joerg Aichelin et al. (+1 more)

We employ the Parton-Hadron-String Dynamics (PHSD) transport approach to investigate the influence of baryon-rich matter on charmonium production and dissociation. The Remler formalism is implemented to dynamically model charmonium formation from charm-anticharm pairs. As a validation step, the formalism is first benchmarked against experimental data from elementary pp collisions and then extended to pA systems to extract the effective nuclear absorption cross section of charmonium. This extracted cross section can subsequently be applied in heavy-ion collisions to quantify medium-induced effects. Our results demonstrate that the Remler formalism provides a quantitatively consistent description of charmonium production in pp and pA collisions at SPS energies. The approach is then extrapolated to GSI/FAIR energies, where predictions for charmonium yields and survival probabilities are presented. These findings highlight the relevance of the Remler formalism as a dynamical framework for studying heavy-quark bound-state formation in baryon-rich matter and offer theoretical guidance for future experimental programs at SPS, FAIR and NICA aimed at mapping the QCD phase structure.
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All authors Taesoo Song, Jiaxing Zhao, Joerg Aichelin, Elena Bratkovskaya

High Energy Physics (Phenomenology)

Exploring possible $^3_{\Lambda_c}\text{H}$ bound states through $p\Lambda_c$ femtoscopic correlations

Ye Yan, Qi Huang, Qian Wu et al. (+2 more)

The femtoscopic correlation technique in relativistic heavy-ion collisions provides a unique opportunity to investigate hadron-hadron interactions and possible exotic states. In this work, we study the $p\Lambda_c$ correlation function and its sensitivity to the low-energy $N\Lambda_c$ interaction related to possible $^3_{\Lambda_c}\mathrm{H}$ bound states. Based on the quark delocalization color screening model, three interaction scenarios with different strengths are constructed, and the corresponding spin-averaged $p\Lambda_c$ correlation functions are calculated within the Koonin–Pratt formalism. The results demonstrate that the correlation function is sensitive to the $p\Lambda_c$ interaction strength, with coupled-channel effects and $S$-$D$ wave mixing producing additional enhancements in the correlation signal. These findings suggest that future $p\Lambda_c$ femtoscopic measurements at relativistic heavy-ion collision experiments can provide valuable constraints on the interaction between charmed baryons and nucleons and offer guidance for exploring possible heavy-flavor hypernuclei.
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All authors Ye Yan, Qi Huang, Qian Wu, Hongxia Huang, Jialun Ping

High Energy Physics (Phenomenology)

Polarized jet anisotropy at the Electron-Ion Collider

Zhong-Bo Kang, Hongxi Xing, Fanyi Zhao et al. (+1 more)

Jets provide a powerful probe of the three-dimensional spin structure of the nucleon, a central goal of the Electron-Ion Collider. Yet the observed jet defines an axis that breaks the azimuthal isotropy of soft-gluon radiation, thereby reshaping the very asymmetries used to extract that structure. Using transverse-momentum-dependent (TMD) QCD factorization, we show for the first time that this jet-induced anisotropy imposes a parity selection rule on polarized asymmetries. Expanding the transversely polarized structure functions in harmonics $\cos(n\phi_{qJ})$, where $\phi_{qJ}$ is the angle between the jet and the lepton-jet momentum imbalance, makes this rule explicit: the symmetry of each harmonic is fixed by the parity of $n$, independently of the magnitudes of the harmonic coefficients. For the Sivers function, the canonical left-right asymmetry about the proton spin survives for even $n$ but is replaced by a counterintuitive left-right symmetry for odd $n$. The worm-gear function retains its up-down asymmetry at every harmonic while being left-right symmetric for even $n$ and asymmetric for odd $n$. At EIC kinematics, the higher harmonics studied here are predicted to be individually measurable, providing new observables for the azimuthal dynamics of soft radiation and an essential ingredient in precision extractions of nucleon structure.
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All authors Zhong-Bo Kang, Hongxi Xing, Fanyi Zhao, Yiyu Zhou

High Energy Physics (Phenomenology) · Cross-listed from hep-th

Examples of Gribov copies in the presence of planar boundaries, and an emergent boundary gauge invariance in Yang-Mills theory

David Dudal, Luigi Rosa and Sebbe Stouten

First, we explicitly construct zero-modes of the Yang-Mills Faddeev-Popov operator in the presence of two parallel plates, with either perfect electric (PEC) or perfect magnetic (PMC) boundary conditions imposed. This establishes the existence of Gribov copies with finite action, and even finite L_2-norm, in Yang-Mills theory with non-trivial interfaces. We adapt Henyey's construction, although the boundary configuration imposes extra restrictions on the ansatz for the gauge field. Second, we discuss the phenomenon of an emergent boundary gauge invariance for PEC and PMC plates in Yang-Mills theory. This shall be important when applying the Gribov-Zwanziger procedure to parallel plate setups, of relevance for non-perturbatively studying the non-Abelian Casimir effect in the future.
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High Energy Physics (Phenomenology)

Two-loop QCD corrections to $CP$-even Higgs boson decays into $V\gamma$ in the Type-I Two-Higgs-Doublet Model

Lin-Qiao Qu, Zhong-Yuan Liu, Peng-Fei Duan et al. (+2 more)

We investigate the QCD corrections to the loop-induced decays of the heavy $CP$-even Higgs boson, $H \to V\gamma$ ($V = Z, \gamma$), within the framework of the Type-I Two-Higgs-Doublet Model (THDM). Owing to the similarity of the underlying loop topologies, the two decay channels exhibit closely correlated behaviour. After imposing relevant phenomenological constraints, we evaluate the decay widths for 5000 viable parameter points at next-to-leading order (NLO) in QCD under the alignment limit. The $H\to\gamma\gamma$ width exceeds that of $H\to Z\gamma$ by roughly a factor of four. Both are dominated by the top-quark loop: the $W$ contribution vanishes in the alignment limit, and the charged-Higgs loop is suppressed throughout most of the viable parameter region. The corrections exhibit a pronounced dependence on the heavy Higgs boson mass $m_H$, attaining a maximum in the vicinity of the $t\bar{t}$ production threshold. To elucidate the individual parameter dependences, dedicated benchmark scenarios are analysed, revealing that the decay widths diminish monotonically with increasing $\tan\beta$ while growing with $m_H$. The QCD corrections for both decay modes typically span approximately $-20\%$ to $+20\%$, with larger corrections in the non-alignment scenario: in the $H\to\gamma\gamma$ channel they reach up to $+38\%$ at large $\tan\beta$, and in the $H\to Z\gamma$ channel they cross zero to become positive. The $CP$ selection rule forces the $t\bar{t}$ pair into a $P$-wave configuration at threshold, which strongly suppresses the Coulomb corrections and secures the perturbative stability of the fixed-order prediction. A comparison with ATLAS limits shows that current data do not yet constrain the parameter space, whereas the $\mathcal{O}(15\%)$ NLO corrections may become relevant for interpreting exclusion bounds at the HL-LHC.
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All authors Lin-Qiao Qu, Zhong-Yuan Liu, Peng-Fei Duan, Yu Zhang, Wei-Long Duan

High Energy Physics (Phenomenology)

Meson gravitational D-form factors and symmetry breaking in low-energy QCD

Mamiya Kawaguchi, Kazuhiro Tanaka and Mitsuru Tanaka

We investigate meson gravitational D-form factors in the three-flavor linear sigma model and their connection to symmetry breaking in low-energy QCD. Within the scalar meson dominance picture, we examine the scalar meson exchange contributions and their relation to meson masses through scalar-meson couplings. In the three-flavor symmetric limit, we first derive analytical expressions for the D-form factors of pseudoscalar and scalar mesons. In the chiral limit, the forward-limit value of the octet pseudoscalar D-form factor is fixed to $-1$, whereas the $U(1)_A$ anomaly generates additional contributions to the singlet pseudoscalar and scalar-meson D-form factors. For realistic flavor breaking, the interaction introduced to reproduce the scalar-meson mass hierarchy below $1$ GeV significantly affects the scalar-meson D-form factors. We further compare the linear sigma model results with those obtained from a chiral perturbation theory Lagrangian including a dilatonic scalar field and show that their differences are governed by the canonical mass dimensions of the interaction terms contributing to meson mass generation. These results indicate that meson D-form factors provide sensitive probes of symmetry-breaking structures in low-energy hadron physics.
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High Energy Physics (Phenomenology)

First-principle predictions of fragmentation functions via quantum computing

Juan J. Gálvez-Viruet, Felipe J. Llanes-Estrada, Nicolas M. Arenaza et al. (+2 more)

We report on an algorithm to compute fragmentation functions from the first principles Quantum Chromodynamics (QCD) Hamiltonian quantized in Light-Front Gauge, opening a path for digital quantum computers to calculate these longitudinal jet-structure observables. Simulating the behaviour of such computers on a classical cluster (which is memory-limited to about 30 qubits, given the expansive Hilbert spaces of actual quantum computers), we run a demonstration of a heavy-quark leading parton fragmenting into quarkonium, which we benchmark against NRQCD computations. Future quantum computers, perhaps concurrently running with HL-LHC, would have ample opportunity to extract arbitrary parton-hadron combinations.
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All authors Juan J. Gálvez-Viruet, Felipe J. Llanes-Estrada, Nicolas M. Arenaza, María Gómez-Rocha, T. J. Hobbs

High Energy Physics (Phenomenology)

High energy thermal photons from chirally imbalanced QGP

Sourav Duari, Nilanjan Chaudhuri, Pradip Roy et al. (+1 more)

We compute the thermal photon production rate from a chirally asymmetric quark gluon plasma. We estimate the hard part from scattering of chiral quarks and demonstrate the cut-off independence of the total thermal photon emission rate. This is achieved by combining the hard with the soft contribution evaluated in our previous work using the Braaten-Pisarski method of hard thermal loop perturbation theory. It is observed that the presence of chiral imbalance leads to an overall enhancement in the emission rate of thermal photons.
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All authors Sourav Duari, Nilanjan Chaudhuri, Pradip Roy, Sourav Sarkar

High Energy Physics (Phenomenology)

Spin-dependent fermion potentials from mixed tensor couplings of massive spin-1 and spin-2 bosons

D. Khadka and V.V. Flambaum

Searches for weak spin-dependent forces are commonly interpreted in terms of a basis of sixteen rotationally invariant two-fermion potentials, including potentials which violate parity (P) and time-reversal (T) invariance. We derive finite-range coordinate-space potentials generated by a massive spin-1 boson with vector, axial-vector, tensor, and pseudotensor couplings to Dirac fermions. In addition to the familiar vector–vector, vector–axial-vector, and axial-vector–axial-vector interactions, we obtain the mixed vector–tensor, vector–pseudotensor, axial-vector–tensor, and axial-vector–pseudotensor potentials, together with tensor–tensor, tensor–pseudotensor, and pseudotensor–pseudotensor terms. We retain the contact terms needed in atomic-scale applications and give compact expressions that include both orderings of inequivalent fermion vertices. We then extend the analysis to a massive spin-2 mediator described by a symmetric Fierz–Pauli field. Besides the conventional coupling to the conserved fermion energy–momentum tensor, we consider a symmetric axial-tensor current. Its nonconservation for massive fermions makes the longitudinal spin-2 helicities contribute to axial-tensor–axial-tensor exchange. The leading minimal spin-2 interactions are either P,T even or P odd and T even; in particular, they do not generate a T-odd potential. We map the resulting interactions onto the sixteen-potential Dobrescu–Mocioiu basis and use this mapping to translate existing experimental constraints into numerical limits on spin-1 and spin-2 coupling products in the small- and large-mediator-mass regimes, together with representative limits at finite mediator masses. The derived relations between the boson-exchange coupling constants and the coefficients of the basis potentials also allow published exclusion curves to be rescaled to arbitrary mediator masses.
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High Energy Physics (Phenomenology)

Building a Better Beta: Nucleation and Timescales in Cosmological Phase Transitions

William Searle and Csaba Balázs

First-order phase transitions in the early universe can generate a stochastic background of gravitational waves, offering a unique probe of high-energy physics. In this work, we investigate aspects of bubble nucleation and transition timescales, which play a central role in shaping the resulting gravitational wave spectrum. Many common approaches characterise the transition rate via a Taylor expansion of the false vacuum decay rate. We argue that a more fundamental description is instead given by the distribution of bubble lifetimes, and define a new timescale, $\beta_\nu$, as the first moment of this distribution. We show that $\beta_\nu$ reproduces the behaviour of previous timescale definitions in the appropriate limits, while avoiding their pathologies, and offers a more natural description of the ensemble of nucleated bubbles. We then quantify the impact of this improved timescale on the predicted gravitational wave spectrum, finding that it shifts the peak amplitude by up to an order of magnitude relative to previous definitions. As next-generation gravitational wave detectors come online, robust theoretical predictions will be essential; we hope this work represents a step in that direction.
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Sunday 30 August

High Energy Physics (Phenomenology)

Quantum Steering Geometry at High Energy Particle Colliders

Juan J. Mejia Alvarez, Andrew J. Wildridge, Angelo Arisi et al. (+5 more)

We formulate collider observables based on quantum steering ellipsoids (QSEs) for reconstructed bipartite systems of spin-$1/2$ particles. A collider spin density matrix defines a two-qubit state, while its QSE gives the geometry of conditional states accessible through local measurements. This makes the ellipsoid a direct probe of the quantum properties of fundamental particles, encoding polarization, spin correlation anisotropy, accessible-state volume, and the orientation of the dominant correlation axes. Using top-quark pair production as a benchmark process, we show how QSE observables organize the Standard Model spin state, probe entanglement, steerability, and Bell-nonlocality criteria, and use an expected precision metric to assess sensitivity to non-local correlations in the boosted central region. We show that different dimension-six operators generate distinctive QSE deformations, and provide a geometric interpretation of quantum information observables in high-energy particle physics. Quantum steering geometry therefore provides a unified framework for particle collider tomography, quantum information diagnostics, and precision searches for physics beyond the Standard Model with applications spanning the HL–LHC and future lepton, muon, flavor, and electron-ion collider programs.
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All authors Juan J. Mejia Alvarez, Andrew J. Wildridge, Angelo Arisi, Juan M. Duarte-Quiros, Santosh Bhandari, Jingyan Li, Giulia Negro, Andreas W. Jung

High Energy Physics (Phenomenology)

Quantum-statistical effects of bosonic warm dark matter in microscopic interacting dark sectors

Zhijian Zhang

We investigate the impact of the quantum statistical properties of bosonic warm dark matter (BWDM) on a microscopic interacting dark-sector model mediated by a Yukawa coupling. We consider a BWDM scenario containing a Bose–Einstein condensed (BEC) component. By separating the BWDM phase-space distribution into thermal and condensate components, we derive the thermally averaged annihilation cross sections for the thermal–thermal, thermal–condensate, and condensate–condensate channels. The long-range scalar interaction and its Sommerfeld enhancement are included in the annihilation processes. We find that the condensate fraction provides an additional quantum-statistical degree of freedom controlling the microscopic dark-sector energy transfer. In particular, the transition between the thermal–thermal dominated regime and the condensate–condensate dominated regime is characterized by a critical condensate fraction r_c, which is mainly determined by the BWDM mass and the dark energy scalar field mass. For condensate fractions above this critical value, the condensate–condensate channel dominates the present-day interaction rate. By imposing the condition that the present-day interaction rate does not exceed the Hubble expansion rate, we determine the corresponding region of the dark-sector parameter space satisfying this condition.
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High Energy Physics (Phenomenology)

NNLO QCD corrections to the weak radiative $B$-meson decay with exact dependence on $m_c$

M. Czaja, M. Czakon, T. Huber et al. (+5 more)

The inclusive weak radiative $B$-meson decay provides important constraints on many popular extensions of the Standard Model. Some of the numerically relevant Next-to-Next-to-Leading-Order QCD corrections to its branching ratio have so far been evaluated using an interpolation in the charm quark mass between the $m_c=0$ and $m_c \gg m_b$ limits. In the current paper, we present their determination for the physical value of $m_c$, which required calculating hundreds of four-loop propagator diagrams with unitarity cuts and two mass scales. Our final result for the CP- and isospin-averaged branching ratio reads ${\mathcal B}_{s \gamma}^{\rm SM} = (3.54 \pm 0.14)\times 10^{-4}$ for $E_\gamma > 1.6\,{\rm GeV}$ in the decaying meson rest frame. It is in good agreement with the current Particle Data Group average ${\mathcal B}_{s \gamma}^{\rm exp} = (3.49 \pm 0.19)\times 10^{-4}$.
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All authors M. Czaja, M. Czakon, T. Huber, M. Misiak, M. Niggetiedt, A. Rehman, K. Schönwald, M. Steinhauser

High Energy Physics (Phenomenology)

The inclusive $\bar B \to X_s \gamma$ decay rate with higher precision

M. Misiak, H. M. Asatrian, K. Brune et al. (+11 more)

We present a new and upgraded analysis of the inclusive weak radiative decay of the $B$ meson in the standard model and beyond. The ${\mathcal O}(\alpha_s)$ perturbative corrections are included in a formally complete manner. At the order $\alpha_s^2$, exact dependence on the charm quark mass is calculated for the dominant corrections, which removes a sizeable uncertainty that was present in all the previous analyses. The global normalization factor and many of the non-perturbative contributions are expressed in terms of the kinetic-scheme mass of the $b$-quark and the heavy-quark-expansion matrix elements. These parameters are adopted from the most recent semileptonic fits that include ${\mathcal O}(\alpha_s^3)$ corrections and up-to-date experimental results. We find ${\mathcal B}_{s\gamma}^{\rm SM} = (3.54 \pm 0.14)\times 10^{-4}$ for the CP- and isospin-averaged branching ratio of the considered decay in the standard model, with a lower cut on the photon energy $E_\gamma > 1.6\,{\rm GeV}$. It agrees with the current experimental average ${\mathcal B}_{s\gamma}^{\rm exp} = (3.49 \pm 0.19)\times 10^{-4}$, which provides constraints on beyond standard model physics. In particular, we find $M_{H^\pm} > 670\,{\rm GeV}$ at $95\%\,{\rm C.L.}$ for the charged Higgs boson mass in the two-Higgs-doublet model~II.
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All authors M. Misiak, H. M. Asatrian, K. Brune, M. Czaja, M. Czakon, M. Fael, C. Greub, T. Huber, F. Lange, L. T. Moos, M. Niggetiedt, A. Rehman, K. Schönwald, M. Steinhauser

High Energy Physics (Phenomenology)

In-Medium Modification of $\phi$ Meson Mass over Temperature and Momentum

Hidefumi Matsuda, Philipp Gubler and Koichi Hattori

We analyze the in-medium modification of the $\phi$ meson mass below the pseudo-critical temperature $T_\text{c}$ at vanishing baryon chemical potential using QCD sum rules. The sum rules are applied separately to the transverse and longitudinal polarization modes of the $\phi$ meson defined relative to the spatial momentum in the medium rest frame. We map out the temperature and momentum dependence of the mass in each mode and quantify the resulting transverse–longitudinal mass splitting. The splitting develops with increasing temperature and momentum.
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High Energy Physics (Phenomenology)

Kaon gravitational form factors and mechanical structure in a three-flavor NJL model

Zhibo Liu and Hiroaki Abuki

We investigate the gravitational form factors (GFFs) of the kaon in a proper-time-regularized three-flavor Nambu–Jona-Lasinio model. We treat the kaon as a light–strange pseudoscalar bound state and evaluate its energy–momentum-tensor matrix element using a dressed quark–graviton vertex. By retaining the interaction-induced contact contribution alongside the quark triangle diagrams, we preserve the gravitational Ward–Takahashi identity and ensure the conservation of the total energy–momentum tensor. We determine the light- and strange-quark contributions to the kaon GFFs, contrast them with the corresponding pion results, and extract the associated pressure and shear-force distributions, together with the Breit-frame and transverse light-front mass radii. Explicit flavor-symmetry breaking dictates that the strange sector carries a larger share of the kaon momentum and mechanical response. Consequently, compared to the pion, the kaon exhibits a less negative $D$-term and more compact mechanical distributions, featuring enhanced central pressure and shear. We further show that a Ward–Takahashi-identity-preserving reduction of the $C$-term projection is essential for maintaining the pion low-energy theorem in proper-time regularization.
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High Energy Physics (Phenomenology)

Debye screening mass in hot QCD at three loops: Canonical form of the integrand

York Schröder and Miguel Váez

The Debye screening mass is a fundamental parameter characterizing the screening of chromo-electric fields in a hot quark-gluon plasma. It plays an important role in thermal field theory, entering the description of screening lengths, transport phenomena, heavy-particle interactions in the early Universe, and the dimensional reduction program that connects thermal QCD to effective three-dimensional theories. In this contribution, we revisit the reduction strategy that serves to organize the large number of terms that contribute to the screening mass at the three-loop level, applying recent advances based on canonical forms of thermal (sum-) integrands. We emphasize the role of integration variable shifts, and discuss how canonical representations of thermal integrands may simplify future high-order calculations in hot QCD.
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High Energy Physics (Phenomenology)

Seesaw and Axion in No-Scale Gravity

Anamaria Hell, Lincoln da S. Pereira and Tsutomu T. Yanagida

The No-Scale gravity is a compelling framework to describe particle physics, gravity and cosmology, in which all mass scales are an illusion given by the value of a scalar field $\phi$. This theory, however, falls under the umbrella of more general scalar-tensor theories, which propagate different modes depending on the scalar field, and faces the extensive debate regarding the equivalence between its Jordan and Einstein frame descriptions. In this work we advocate that by excluding the singular point in the transformation between the two frames (e.g., $\phi=0$) we can have the classical equivalence between them. To show the merit of removing this singular point, we argue the Jordan frame makes the symmetries of the model manifest, which creates a suitable playground for the particle-physics model building which we illustrate by showing the emergence of discrete symmetries which leads to a high-quality axion and also naturally incorporate the seesaw mechanism.
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High Energy Physics (Phenomenology)

X(2370) as the pseudoscalar glueball: Another clue from a constituent approach

F. Buisseret

The pseudoscalar state X(2370) is the clearest glueball candidate experimentally identified so far. From a phenomenological point of view, constituent approaches, in which the lightest glueballs are modelled as bound states of two transverse constituent gluons linked by an adjoint flux tube, reach a good agreement with quenched lattice QCD pure gauge spectrum. Based on the assumption that the total decay width of glueballs or light unflavoured mesons is proportional to the energy stored in the flux tube, a model is developed that linearly correlates the hadron decay width to its mass. The model is first fitted on light unflavoured mesons and then extended to glueballs. Both the mass and decay width of the X(2370) are compatible with the results of the constituent approach. Other experimental glueball candidates in the scalar and tensor channels are also reviewed to show the ability of the developed approach to identify glueballs: The f$_2$(2150) and f$_2$(2300) states appear as promising tensor glueball candidates.
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High Energy Physics (Phenomenology) · Cross-listed from hep-ex

Searching for Extra Dimensions and Copies of the Standard Model with IceCube

R. Abbasi, M. Ackermann, J. Adams et al. (+418 more)

The hierarchy problem remains an open question in particle physics. A number of theories that address this problem lower the fundamental scale of gravity, resulting in observable consequences in the neutrino sector. In this work, we place constraints on low-scale gravity scenarios using high-energy neutrinos observed with the IceCube Neutrino Observatory. The analysis is based on 10.7 years of upward-going muon neutrino data in the energy range from 0.5 to 100 TeV. In this energy range, the theories predict characteristic spectral distortions arising from matter effects when neutrinos propagate through Earth. In the context of large extra dimension models, we constrain the compactification radius of the largest extra dimension to $R \lesssim 0.17\,\mu\mathrm{m}$ at $90\%$ confidence level for both normal and inverted neutrino mass ordering. For scenarios with multiple Standard Model copies, we obtain lower limits of up to $N \gtrsim \mathcal{O}(400)$, depending on the value of the lightest neutrino mass. In parts of the parameter space, these results constitute the strongest constraints in the literature to our knowledge, while in other regions they probe previously unexplored parameter space.
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All authors R. Abbasi, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, J.M. Alameddine, S. Ali, N. M. Amin, K. Andeen, C. Argüelles, S. Athanasiadou, S. N. Axani, R. Babu, X. Bai, A. Balagopal V., S. W. Barwick, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, P. Behrens, J. Beise, C. Bellenghi, S. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, B. Brinson, Z. Brisson-Tsavoussis, L. Brusa, R. T. Burley, D. Butterfield, K. Carloni, J. Carpio, N. Chau, Y. C. Chen, Z. Chen, D. Chirkin, S. Choi, A. Chubarov, B. A. Clark, D. A. Coloma Borja, A. Connolly, J. M. Conrad, D. F. Cowen, C. De Clercq, J. J. DeLaunay, D. Delgado, T. Delmeulle, S. Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. Díaz-Vélez, S. DiKerby, T. Ding, M. Dittmer, A. Domi, L. Draper, L. Dueser, D. Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, C. Eldridge, P. Eller, E. Ellinger, D. Elsässer, R. Engel, H. Erpenbeck, W. Esmail, S. Eulig, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. Fattorini, A. R. Fazely, A. Fedynitch, N. Feigl, C. Finley, D. Fox, A. Franckowiak, S. Fukami, P. Fürst, J. Gallagher, E. Ganster, A. Garcia, M. Garcia, E. Genton, L. Gerhardt, A. Ghadimi, C. Glaser, T. Glüsenkamp, J. G. Gonzalez, S. Goswami, A. Granados, D. Grant, S. J. Gray, S. Griffin, S. Griswold, K. M. Groth, D. Guevel, C. Günther, P. Gutjahr, C. Ha, A. Hallgren, L. Halve, F. Halzen, L. Hamacher, M. Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, J. Häußler, K. Helbing, J. Hellrung, B. Henke, L. Hennig, F. Henningsen, L. Heuermann, R. Hewett, N. Heyer, S. Hickford, A. Hidvegi, C. Hill, G. C. Hill, R. Hmaid, K. D. Hoffman, A. Hollnagel, D. Hooper, S. Hori, K. Hoshina, M. Hostert, W. Hou, M. Hrywniak, T. Huber, K. Hultqvist, K. Hymon, A. Ishihara, W. Iwakiri, M. Jacquart, S. Jain, O. Janik, M. Jansson, M. Jin, N. Kamp, D. Kang, W. Kang, A. Kappes, L. Kardum, T. Karg, A. Karle, A. Katil, M. Kauer, J. L. Kelley, M. Khanal, A. Khatee Zathul, A. Kheirandish, T. Kim, H. Kimku, F. Kirchner, J. Kiryluk, C. Klein, S. R. Klein, Y. Kobayashi, S. Koch, A. Kochocki, R. Koirala, H. Kolanoski, T. Kontrimas, L. Köpke, C. Kopper, D. J. Koskinen, P. Koundal, M. Kowalski, T. Kozynets, A. Kravka, N. Krieger, T. Krishnan, K. Kruiswijk, E. Krupczak, E. Kun, N. Kurahashi, C. Lagunas Gualda, L. Lallement Arnaud, M. J. Larson, F. Lauber, J. P. Lazar, K. Leonard DeHolton, A. Leszczyńska, C. Li, J. Liao, C. Lin, Q. R. Liu, Y. T. Liu, M. Liubarska, C. Love, L. Lu, F. Lucarelli, W. Luszczak, Y. Lyu, M. Macdonald, E. Magnus, Y. Makino, E. Manao, S. Mancina, A. Mand, I. C. Mariş, S. Marka, Z. Marka, L. Marten, I. Martinez-Soler, R. Maruyama, J. Mauro, F. Mayhew, F. McNally, K. Meagher, A. Medina, M. Meier, Y. Merckx, L. Merten, J. Mitchell, L. Molchany, S. Mondal, T. Montaruli, R. W. Moore, Y. Morii, A. Mosbrugger, D. Mousadi, E. Moyaux, T. Mukherjee, M. Nakos, U. Naumann, R. Neshat, L. Neste, M. Neumann, M. U. Nisa, K. Noda, A. Noell, A. Novikov, A. Obertacke, V. O'Dell, A. Olivas, R. Orsoe, J. Osborn, E. O'Sullivan, B. Owens, V. Palusova, H. Pandya, A. Parenti, C. Parisel, N. Park, V. Parrish, E. N. Paudel, L. Paul, C. Pérez de los Heros, T. Pernice, T. C. Petersen, J. Peterson, S. Pick, M. Plum, A. Pontén, V. Poojyam, B. Pries, R. Procter-Murphy, G. T. Przybylski, L. Pyras, C. Raab, J. Rack-Helleis, N. Rad, M. Ravn, K. Rawlins, Z. Rechav, A. Rehman, I. Reistroffer, E. Resconi, C. D. Rho, W. Rhode, L. Ricca, B. Riedel, A. Rifaie, E. J. Roberts, S. Rodan, M. Rongen, A. Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, J. Saffer, D. Salazar-Gallegos, P. Sampathkumar, A. Sandrock, G. Sanger-Johnson, M. Santander, S. Sarkar, M. Scarnera, M. Schaufel, H. Schieler, S. Schindler, L. Schlickmann, B. Schlüter, F. Schlüter, N. Schmeisser, T. Schmidt, F. Schmitt, A. Scholz, F. G. Schröder, S. Schwirn, S. Sclafani, D. Seckel, L. Seen, M. Seikh, S. Seunarine, P. A. Sevle Myhr, R. Shah, S. Shah, A. Sharma, S. Shefali, N. Shimizu, M. Shin, B. Skrzypek, R. Snihur, J. Soedingrekso, D. Soldin, P. Soldin, G. Sommani, D. Song, C. Spannfellner, G. M. Spiczak, C. Spiering, J. Stachurska, M. Stamatikos, T. Stanev, T. Stezelberger, T. Stürwald, T. Stuttard, G. W. Sullivan, I. Taboada, S. Ter-Antonyan, A. Terliuk, A. Thakuri, M. Thiesmeyer, W. G. Thompson, J. Thwaites, W. Tian, S. Tilav, K. Tollefson, J. A. Torres, S. Toscano, D. Tosi, K. Upshaw, J. A. Urruty, A. Vaidyanathan, N. Valtonen-Mattila, J. Valverde, J. Vandenbroucke, T. Van Eeden, N. van Eijndhoven, L. Van Rootselaar, J. van Santen, J. Vara, F. Varsi, M. Velazquez, M. Venugopal, M. Vereecken, S. Vergara Carrasco, S. Verpoest, A. Vijai, J. Villarreal, C. Walck, A. Wang, E. H. S. Warrick, C. Weaver, P. Weigel, A. Weindl, J. Weldert, A. Y. Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, L. Witthaus, J. Woodward, G. Wrede, X. W. Xu, J. P. Yanez, Y. Yao, E. Yildizci, S. Yoshida, F. Yu, S. Yu, T. Yuan, S. Yun-Cárcamo, A. Zander Jurowitzki, A. Zegarelli, S. Zhang, Z. Zhang, P. Zhelnin, P. Zilberman, C. Zilleruelo Cañas

High Energy Physics (Phenomenology)

$(g-2)_{\ell}$ and LFV decays in a $U(1)_{L_{\mu} -L_{\tau}}$ left-right model with inverse seesaw neutrinos

L. T. Hue, Vo Quoc Phong, T.D. Tham et al. (+1 more)

In the framework of a $U(1)_{L_{\mu} -L_{\tau}}$ left-right model with inverse seesaw neutrinos recently proposed, we show that one-loop contributions from heavy singly charged Higgs bosons to the anomalous magnetic moments of charged leptons $(g-2)_{e,\mu}$ can accommodate the observed discrepancies, of $10^{-9}$ and $\mathcal{O}(10^{-13})$ for the muon and electron, respectively. Meanwhile, all lepton-flavor violating decay rates for $h\to e_b^\pm e_a^\mp $, $Z\to e_b^\pm e_a^\mp$, and $e_b\to e_a \gamma$ are found to be highly suppressed as a consequence of the gauged $U(1)_{L_{\mu}-L_\tau}$ symmetry.
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All authors L. T. Hue, Vo Quoc Phong, T.D. Tham, N.H.T. Nha

High Energy Physics (Phenomenology) · Cross-listed from hep-th

Latent Geometry and the Emergence of Lorentzian Time in Matrix Quantum Mechanics

Badis Ydri

We introduce latent geometry in BFSS/BMN models. Before an emergent geometry evaporates at the geometric transition, large-$d$ Gaussianization encodes its information in the exceptional $N=2$ sector selected by the baby fuzzy sphere, a single active spin-$1/2$ Pauli block. Dimensional reduction, finite-$N$ Gaussianization and exact Molien–Weyl projection transport this encoding to mass-deformed BFSS$_2$. At $N=2$, the same stable BFSS$_2$ oscillator admits inequivalent unitary $\mathbf{H}^2_\theta=\mathbf{EAdS}^2_\theta$ and $\mathbf{dS}^2_\theta$ decodings, realizing spacetime transmutation and the emergence of Lorentzian time.
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High Energy Physics (Phenomenology)

On-shell renormalization in NREFT: a simplified description of resonances, bound states, and coupled channel effects

Guo-Ying Chen

We discuss several issues regarding the modern generalization of Weinberg's compositeness criterion. In particular, we demonstrate that the on-shell renormalization in NREFT reproduces Weinberg's result and provides a simple description of resonances, bound states, and coupled channel effects. Additionally, we present the complete propagator, including the charged channel for the near-threshold p-wave states.
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High Energy Physics (Phenomenology)

Probability-based Estimates of the Uncalculated N$^5$LO QCD Contribution to the Hadronic $W$-Boson Decay Width

Shu-Heng Yang, Jiang Yan, Xing-Gang Wu et al. (+1 more)

The perturbative QCD corrections to the hadronic decay width of the $W$ boson are currently known up to next-to-next-to-next-to-next-to-leading order ($\mathrm{N^4LO}$), whereas the exact $\mathrm{N^5LO}$ correction remains unavailable owing to its formidable computational complexity. In this work, we estimate the $\mathrm{N^5LO}$ contributions by adopting Bayesian analysis (BA). Before performing the estimation, the Principle of Maximum Conformality (PMC) is employed to improve the precision of the initial scale-dependent perturbative series. Through recursive application of the renormalization group equation, non-conformal terms are absorbed into the strong running coupling, yielding a scheme-independent, scale-invariant perturbative series with improved convergence. The PMC procedure determines an effective coupling $\alpha_s(Q_*)$, with the PMC scale fixed as $Q_* = 100.102~\mathrm{GeV}$ at next-to-next-to-leading logarithmic accuracy. Based on the improved and more precise series, the $95.5\%$ BA credible interval yields an uncertainty of $\Delta\delta_\mathrm{QCD}|_{\mathrm{PMC, BA}}^{\mathrm{N^5LO}} = \pm 1.0\times 10^{-5}$. The resulting hadronic branching ratio is $\mathcal{B}(W\to \text{hadrons})|_\mathrm{PMC} = (65.84\pm 1.54)\%$, which is consistent with experimental data within reasonable errors.
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All authors Shu-Heng Yang, Jiang Yan, Xing-Gang Wu, Zhi-Fei Wu