High Energy Physics (Phenomenology) · Cross-listed from hep-th
Calculating Axion-Matter Couplings in String Theory
Joshua N. Benabou, Naomi Gendler, Thomas R. Harvey et al. (+1 more)
In this work we calculate, for the first time, the dominant perturbative contributions to
axion–matter couplings explicitly in string theory. Concretely, we compute these couplings in Calabi–Yau compactifications of heterotic string theory where the vector bundle is a sum of line bundles. They are expressed as overlap integrals requiring the Ricci-flat metric, the Hermitian Yang-Mills bundle metric, and the matter field harmonic forms. We compute these by solving the corresponding coupled differential equations with neural networks. Our results establish a characteristic hierarchy of four-dimensional couplings:
axions couple to
fermions as $\mathcal{L} \supset c_\psi\,\frac{\partial_\mu a}{f_a}\, \psi^\dagger \bar{\sigma}^\mu \psi$ with $c_\psi$ an $\mathcal{O}(1)$ function of Kähler moduli for the model-dependent
axions, while the corresponding coupling for the model-independent
axion is suppressed by $\alpha_{\rm YM}$ at the ultraviolet matching scale. The model-dependent
axions thus couple to
fermions similarly as DFSZ-like four-dimensional
axions, whereas the model-independent
axion's couplings are loop-suppressed as in KSVZ-like constructions. The methods developed here apply directly to the large class of heterotic line bundle models with realistic spectra, and can be adapted to type II constructions.
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All authors Joshua N. Benabou, Naomi Gendler, Thomas R. Harvey, Jakob Moritz
High Energy Physics (Phenomenology)
The axion mass in the post-inflationary scenario in a minimal scaling model
José Correia, Mark Hindmarsh, Joanes Lizarraga et al. (+3 more)
We calculate the dark matter
axion mass in the post-inflationary scenario in a minimal model with a set of classical field theory simulations on $12\,288^3$ grids. In the model, the Peccei-Quinn U(1)
symmetry is broken by a complex scalar field at a temperature $f_{\rm a} \sim 10^{11}$ GeV, creating a string network. The strings become the boundaries of domain walls at the QCD transition, which draw the strings together and annihilate them. The decay of the strings and domain walls leaves behind
axion radiation, with a comoving number density estimated to be $9.48(23)f_{\rm a}^2 H_*$, normalised to unit scale factor when the
axion mass is equal to the Hubble rate $H_*$. Using the most commonly quoted
lattice results for the topological susceptibility, the dark matter
axion mass in this minimal model is $17.46(84)\,\mu\text{eV}$. This corresponds to a
symmetry-breaking scale of $3.27(15) \times 10^{11}\, \text{GeV}$, and a haloscope resonant frequency of $4.22(20)\,\text{GHz}$. We argue that field theory simulations of non-minimal models where the strings have a
Higgs condensate or gauge flux, and are annihilated by domain walls, will give
axion mass predictions below about $40\,\mu\text{eV}$.
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All authors José Correia, Mark Hindmarsh, Joanes Lizarraga, Asier Lopez-Eiguren, Kari Rummukainen, Jon Urrestilla
High Energy Physics (Phenomenology) · Cross-listed from hep-th
Environmental Effects in Post-Minkowskian Dynamics: Effective Field Theory, Feynman Rules, and Ward Identities for Compact Objects in Relativistic Fluids
Zvi Bern, Samuel Degen, Enrico Herrmann et al. (+2 more)
We develop a hydrodynamic effective field theory for the gravitational dynamics of compact objects moving through an inviscid fluid environment. The fluid is described by the effective theory of perfect fluids, whose Goldstone
phonons are kept as explicit fields coupled to
gravity. We establish a consistent power counting for the resulting Feynman rules and derive the propagators and interaction vertices through four points in $D$ dimensions, together with the generalized on-shell Ward identities they obey. These identities relate amplitudes with an external graviton to those with the graviton replaced by a
phonon, and thus provide nontrivial checks on higher-order calculations. As an application, we recover the leading-order relativistic dynamical-friction force from the tree-level amplitude for single-
phonon emission. This work is a first step towards a toolkit for incorporating environmental effects into the scattering-amplitude pipeline used in post-Minkowskian calculations.
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All authors Zvi Bern, Samuel Degen, Enrico Herrmann, Mikhail P. Solon, Anna M. Wolz
High Energy Physics (Phenomenology)
Electromagnetic form factors of vector mesons in Einstein-dilaton holographic QCD
Alfonso Ballon-Bayona, Tobias Frederico, Luis A. H. Mamani et al. (+2 more)
We investigate the electromagnetic form factors of the $\rho$
meson family within a holographic QCD framework based on Einstein-dilaton
gravity with confining backgrounds. We obtain the elastic and transition form factors using a spectral decomposition of the three-point isospin current correlator and an independent approach based on the Kaluza-Klein expansion. Furthermore, we establish a holographic dictionary of the current
matrix element. The elastic form factors are in agreement with available
lattice QCD results, whereas the transition form factors, not yet determined within
lattice QCD, are predictions of the model. For the elastic case, the electric form factor for the $\rho$
meson family exhibits a zero at $q^{2} = 6\, m_{\rho^{n}}^{2}$ and in particular for the ground state $q^{2} = 3.61\,\text{GeV}^{2}$, consistent with light-front and Dyson-Schwinger calculations. We also compute strong couplings between vector
meson states and find some approximate selection rules. In the elastic case and low-$q^{2}$ regime, we calculate dimensionless electric radius,
magnetic and quadrupole moments and compare with other approaches. In the high-$q^{2}$ regime, the form factors follow the expected scaling behavior, and the model predicts their asymptotic normalization. The results in the high-$q^{2}$ regime lead to superconvergence relations and establish a new sum rule involving masses, decay constants and couplings.
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All authors Alfonso Ballon-Bayona, Tobias Frederico, Luis A. H. Mamani, Adão S. da Silva Junior, Wayne de Paula
High Energy Physics (Phenomenology)
An invertible map between 3D Breit-frame mechanical distributions and 2D infinite-momentum-frame mechanical densities in spin-1 hadrons
Kemal Tezgin
We construct an invertible map between the complete set of 3D Breit-frame pressure and shear force distributions and the constrained space of 2D infinite-momentum-frame pressure and shear force densities in coordinate space for
spin-1
hadrons. The correspondence between the two sets of distributions in different frames is established by combining the
geometric forward and inverse Abel transformations with recoil operators after separating the Wigner rotation induced mixing effects on the infinite-momentum-frame side. Unlike in the
spin-1/2 case, these mixings complicate the coordinate space relations for
spin-1
hadrons by introducing additional multipole structures, but the constraints among the form factors propagate into constraints on mechanical densities, so that these additional multipoles do not introduce new mechanical information.
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High Energy Physics (Phenomenology)
Adiabatic hydrodynamization with transverse spatial gradients in boost-invariant plasmas
Uri Sharell, Jasmine Brewer and Weiyao Ke
The quantitative success of relativistic viscous hydrodynamics in describing the short-lived
quark–gluon
plasma raises a fundamental question: how does far-from-
equilibrium QCD matter approach hydrodynamic behavior so rapidly? Microscopic kinetic-theory studies have related this onset to attractor dynamics, but typically assume transverse homogeneity. We relax this assumption by introducing gradient modes with finite transverse wave number $k$, extending the analysis of arXiv:2212.00820. These couple different spherical harmonics of the momentum distribution, and the resulting dynamics is controlled by the competition among the expansion rate $1/\tau$, the collision rate $1/\tau_R$, and the gradient scale $k$. At early times, longitudinal expansion suppresses this coupling, and different spherical harmonic sectors follow their homogeneous attractors. We find that, at later times and sufficiently small $k$, this gradient coupling drives the system toward a global attractor
manifold spanned by hydrodynamic sound and shear modes, on a timescale $\tau_D$ that depends on both the azimuthal harmonic $m$ and $k\tau_R$. For sufficiently large $k\tau_R$, the spectral gap closes: perturbations retain finite damping rates and therefore equilibrate, but no longer follow an isolated hydrodynamic attractor or admit a reduced description involving only a few hydrodynamic modes.
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High Energy Physics (Phenomenology)
Line shapes of $\Omega(2012)$ production in the $\Xi \bar K $ and $\Xi \pi \bar K$ decay channels
Natsumi Ikeno and Eulogio Oset
We theoretically study the line shape of the experiment for $\Omega(2012)$ production in the $\Xi^- \pi^+ K^-$ and $\Xi^0 K^-$ decay modes, reflecting the $\Xi^* \bar K$ and $\Xi \bar K$ decay modes, from the perspective that the $\Omega(2012)$ is a molecular state dynamically generated from the interaction of the $\Xi^* \bar K $ and $\Omega \eta$, coupled channels with $\Xi \bar K$ as a decay channel. We show the consistency of the picture with the experimental mass distributions, giving support to the molecular picture for the $\Omega(2012)$ state. We also call the
attention to the sensitivity of the results to the cut imposed on the $\pi \Xi$ invariant mass, and suggest a different method to obtain the ratio $R^{\Xi \pi \bar K}_{\Xi \bar K}$ of the three-body to two-body decay widths used so far as a test of the molecular picture. We stress that the direct comparison with the experimental mass distributions done here is a more stringent test of the molecular nature of the $\Omega(2012)$ state than the comparison of the ratio $R^{\Xi \pi \bar K}_{\Xi \bar K}$ which has been so far obtained using different criteria.
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High Energy Physics (Phenomenology) · Cross-listed from gr-qc
Palatini inflationary (non-)attractors: Universal mapping of observables
Christian Dioguardi, Francesco Gianesello and Antonio Racioppi
We study single-field slow-roll inflation in the context of Palatini
gravity for the class of non-minimally coupled $\xi$-attractors, i.e.,\ models where the same function $f(\phi)$ fixes both the non-minimal coupling, $1+\xi f(\phi)$, and the inflationary potential, $V(\phi) = M^4 f(\phi)^2$. For an arbitrary $f(\phi)$, the number of $e$-folds is, at leading order, independent of $\xi$. Thanks to this, we provide an immediate mapping between the observables of the non-minimally coupled setup and those of the minimally coupled one. In the strong coupling limit, the tensor-to-scalar ratio is, as usual, suppressed, while the scalar spectral index is shifted towards larger values, with the magnitude of the shift depending only on the tensor-to-scalar ratio associated with the original potential $V(\phi)$.
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High Energy Physics (Phenomenology)
A quantum representation of $\pi$ fragmentation functions through variational quantum circuits
David F. Rentería-Estrada, Roger J. Hernández-Pinto, Germán Rodrigo et al. (+2 more)
We present a variational
quantum-
circuit model for fragmentation functions (FFs). Isospin and charge-conjugation
symmetries are imposed to construct an independent six-flavor basis describing charged and neutral pion production, while physics-inspired Ansätze, including logarithmic feature maps and mass thresholds, encode the relevant kinematics. This
quantum architecture substantially reduces the
quantum circuit redundancies and improve optimization convergence. Using the DSS14 pion FF set as a
benchmark, we first develop a one-dimensional variational representation (FF-VQR) in the momentum fraction at fixed energy scale, and show how
entanglement between
quark and gluon FFs yields a significant improvement, with accurate results already obtained using just two variational layers. A spectral analysis further demonstrates that the
quantum model achieves high expressivity with a limited number of
Fourier modes, supporting its use as a compact non-perturbative parametrization suitable for DGLAP
evolution. We then extend the FF-VQR to two dimensions by incorporating the energy-scale dependence. By encoding all flavor channels within a single entangled
quantum circuit, the
quantum model provides a unified representation with higher accuracy than an independent encoding for each partonic species.
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All authors David F. Rentería-Estrada, Roger J. Hernández-Pinto, Germán Rodrigo, Rodolfo Sassot, German F. R. Sborlini
High Energy Physics (Phenomenology) · Cross-listed from physics.ins-det
Mineral Detection of Neutrinos and Dark Matter 2026 Proceedings
Alexey Elykov, Patrick Stengel, Natsue Abe et al. (+81 more)
The fourth "Mineral Detection of
Neutrinos and Dark Matter" (MDvDM'26) meeting was held April 14-17, 2026 in Karlsruhe, Germany, hosted by the Institute for Astroparticle Physics (IAP) at Karlsruhe Institute of Technology (KIT). These proceedings detail the contributions that were presented during MDvDM'26, illustrating the unprecedented progress in theoretical, computational and experimental studies towards the realization of the concept of mineral detectors. Mineral detectors represent an emerging particle detection concept that has risen in prominence in recent years due to the advent of modern computational and high-resolution microscopy techniques. Natural and synthetic
crystals are capable of retaining microscopic damage features induced by nuclear recoils, which could be then read out with a variety of micrometer and nanometer resolution microscopy techniques. On laboratory time scales mineral detectors could be employed for reactor
neutrino monitoring and dark matter detection, with the potential to measure the directions as well as the energies of the induced nuclear recoils. Uniquely, ancient natural
crystals (so-called paleo-detectors) that have been recording nuclear recoils over geological timescales could be used for studying astrophysical
neutrinos,
cosmic rays, dark matter and heavy exotic particles, as well as the variation of their fluxes over our
Galaxy's lifetime. In recent years the international MDvDM community has been successfully tackling the challenges associated with realizing the concept of mineral detectors, opening the pathway towards a fully fledged experimental program and potential future discoveries.
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All authors Alexey Elykov, Patrick Stengel, Natsue Abe, Daniel Ang, Lorenzo Apollonio, Levente Balogh, Laura Baudis, Chinmay Bharathulwar, Priyanshu Bhattacharya, Yilda Boukhtouchen, Joseph Bramante, Vincent Breton, Andrew Buchanan, Jens Burkhart, Lorenzo Caccianiga, Andrew Calabrese-Day, Mason Camp, Jordan Chapman, Anson Cook, Reza Ebadi, Denis Erkal, Katherine Freese, Audrey Fung, Shota Futamura, Claudio Galelli, Kevin Gao, Peter W. Graham, Thomas Haddock, Minako Hashiguchi, Alexander Hayes, Adam A. Hecht, Samuel C. Hedges, Shigenobu Hirose, Luisa M. Hötzsch, Patrick Huber, Yohei Igami, Vsevolod Ivanov, Florian Jörg, Ayuki Kamada, Takenori Kato, Yoji Kawamura, Katharina Kehl, Chris Kelso, Holger Kluck, Emilie M. LaVoie-Ingram, Matthew Leybourne, Gavishta H. M. Liyanage, Thalles Lucas, Brenden A. Magill, Paolo Magnani, Jennika McIntosh, Naoki Mizutani, Kohta Murase, Tatsuhiro Naka, Lina Necib, Pranav Parvathaneni, Andre Peterson, Zachary S. C. Picker, Rabeya Rabu, Harikrishnan Ramani, Anupam Ray, Morteza Roostaeinia, Hannah Ross, Issei Saikyo, Lukas Scherne, Maximilian Shen, Aaron Shugar, Joshua Spitz, Kai Sun, Jiashen Tang, Erwin H. Tanin, Dionysios P. Theodosopoulos, Yoichi Usui, Pieter Vermeesch, Aaron Vincent, Ronald Walsworth, Jin-Wei Wang, David Waters, Samuel S. Y. Wong, Audrey Wu, Gregory Wurtz, Wen Yin, Xiuyuan Zhang, Zhexian Zhang
High Energy Physics (Phenomenology) · Cross-listed from hep-lat
Computability of GPDs near $x=\pm\xi$ in Lattice QCD
Yushan Su, Xiangdong Ji, Yizhuang Liu et al. (+1 more)
In
lattice QCD computations of generalized parton distributions (GPDs), the large momentum expansion generally requires all hard scales, $2|x\pm\xi|P^z$ and $2|1\pm x|P^z$, to be much larger than $\Lambda_{\rm QCD}$. We show that this condition can be relaxed for $2|x\pm\xi|P^z$ at large $\xi$, making the important $x\sim\pm\xi$ regions accessible to
lattice calculations and considerably expanding the region of computability. Revisiting previous
lattice results with complete one-loop matching, we obtain the expected partonic threshold behavior—GPDs continuous at $x=\pm\xi$ but with discontinuous derivatives—which has not previously been observed on the
lattice. We thus obtain, for the first time, important prediction for GPDs in the distribution-amplitude-like region, which smoothly connects the
quark and antiquark PDF-like behaviors.
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All authors Yushan Su, Xiangdong Ji, Yizhuang Liu, Rui Zhang
High Energy Physics (Phenomenology)
Particle Physics Driven by Quantum Technology - Quantum Simulations and Quantum Sensing
Itay M. Bloch, Marcela Carena, Yifan Chen et al. (+3 more)
We review recent advances in particle physics enabled and motivated by the rapid progress of
quantum technologies. The continued development of
quantum computing toward large-scale, fault-tolerant systems has the potential to address dynamical problems that remain extremely challenging for classical computational approaches, opening new avenues for studying nonperturbative dynamical processes. Tabletop detectors and
quantum-enhanced technologies have reached unprecedented sensitivities, enabling novel searches for ultralight particles, gravitational waves, and other physics beyond the Standard Model in parameter regimes previously inaccessible to conventional instrumentation. Taken together, these developments highlight a rapidly evolving landscape in which
quantum technologies are beginning to reshape fundamental physics. We aim to synthesize recent progress and illuminate the opportunities they present for advancing particle physics in the coming years.
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All authors Itay M. Bloch, Marcela Carena, Yifan Chen, Xinran Li, Ying-Ying Li, Jing Shu
High Energy Physics (Phenomenology) · Cross-listed from nucl-th
A comprehensive theory framework for perturbative calculations of $\delta_C$ in superallowed beta decays
Chien-Yeah Seng
The present high precision determination of $|V_{ud}|$ from superallowed beta decays of $J^P=0^+$, $T=1$
nuclei is largely built on top of the “standard” calculation of the isospin breaking correction $\delta_C$ to the Fermi
matrix element, which assumes the splitting $\delta_C=\delta_{C1}+\delta_{C2}$, where $\delta_{C1}$ and $\delta_{C2}$ represent the “isospin mixing” correction and the “radial mismatch” correction, respectively. In this paper I show that this formalism violates the rule of nucleon basis independence, similar to the gauge invariance requirement in
quantum field theory, therefore its outcome is inevitably subject to uncontrolled systematic errors. I further argue that the perturbative formalism is the only approach that allows the computation of $\delta_C$ at the precision level required for the test of the Cabibbo unitarity. Advancing from existing literature, I develop the full “generating function approach” to compute $\delta_C$ perturbatively, with connections to nuclear mass splittings and the isospin breaking in nuclear charge radii as theory
benchmarks.
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High Energy Physics (Phenomenology)
Investigation of low-lying $\Omega_b(1P)$ states in an unquenched coupled-channel framework
Zi-Le Zhang, Si-Qiang Luo, Shuai-Wei Wang et al. (+1 more)
In this work, we study the unquenched effects on the low-lying $\Omega_b(1P)$ states with a coupled-channel equations. We reveal how the unquenched effects affect the $\Omega_b(1P)$ spectroscopy and component mixing. The numerical results indicate that the $J^P=1/2^-$ $\Omega_b(1P)$ state dominated by the $j_\ell=0$ configuration exhibits significant coupled-channel effects due to its $S$-wave coupling to the $\Xi_b\bar{K}$ channel, where $j_\ell$ denotes the total angular momentum of the light flavor degrees-of-freedom. In this scenario, the mass of this state may be shifted close to or below the $\Xi_b\bar{K}$ threshold, making the radiative and isospin-breaking channels kinematically allowed decay processes. The present analysis provides a coupled-channel perspective on the low-lying $\Omega_b(1P)$ spectrum and offers guidance for future experimental studies of excited bottom baryons.
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All authors Zi-Le Zhang, Si-Qiang Luo, Shuai-Wei Wang, Qin Chang
High Energy Physics (Phenomenology)
Comparing theoretical descriptions of Drell-Yan angular coefficients
Nikita Gramotkov and Oleg Teryaev
A quantitative comparison of the predictions of three theoretical descriptions (TMD, pQCD and geometrical) of the angular coefficients in Drell-Yan Z-
boson production with new experimental data on angular coefficients obtained by the ATLAS, CMS and LHCb collaborations has been performed. In the central rapidity region at low-$Q_T$, the TMD calculation provides a better description of the $A_0$ and $A_2$ coefficients among the descriptions considered. The differences between the approaches are less pronounced for $A_1$,$A_3$ and $A_4$ coefficients. The results identify $A_0$,$A_2$ and the Lam–Tung relation as the most sensitive observables at low-QT and illustrate the domains of applicability of the three descriptions.
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High Energy Physics (Phenomenology)
On the Maximal CP Violation in Leptogenesis with Two Right Handed Neutrinos
Swapnil Dutta
We present a generalized exact analytical expression for the upper bound on the CP-violating decay asymmetry in the case of standard vanilla leptogenesis within the minimal type-I seesaw with two Right Handed
Neutrinos (RHNs) case scenario as a function of the effective
neutrino mass in the hierarchical limit. We derive the bound using a novel analytical treatment of the roots of a quartic equation arising from the conditions for successful leptogenesis, in which the CP asymmetry, effective
neutrino mass, and other physical quantities enter as parameters. We find that the upper bound on CP asymmetry is a monotonically increasing function of the effective
neutrino mass, asymptotically saturating to a global maximum at the large effective mass regime. We find that our exact analytical expression of the upper bound as a function of the effective
neutrino mass is smaller than the previous analytical results in the literature. We also find that the global maximum on CP asymmetry with two RHNs obtained at the large effective mass regime is less than the Davidson-Ibarra bound corresponding to the standard vanilla leptogenesis scenario with three RHNs, leading to a more stringent bound on the lightest RHN mass for the scenario with two RHNs, as expected from some previous results in literature. We find that the deviation from the standard Davidson-Ibarra bound becomes most dramatic for inverted
neutrino mass hierarchy, by nearly two orders of magnitude.
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High Energy Physics (Phenomenology)
Paired charmonium and bottomonium production in rare exclusive decays of Z boson
F. A. Martynenko, A. P. Martynenko and A. A. Skakun
The processes of paired charmonium and bottomonium production in Z-
boson decays are investigated within the relativistic
quark model. Various decay mechanisms are examined, and relativistic decay amplitudes are constructed, taking into account the relative momenta of heavy
quarks. Decay widths are calculated for various mechanisms in the nonrelativistic approximation and taking into account relativistic corrections.
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High Energy Physics (Phenomenology)
Study of the $e^+e^- \to \phi K^+K^-$ reaction within triangle dynamics and its implications for the $\phi(2170)$
Xiang Wei, Cheng Chen, Si-Wei Liu et al. (+4 more)
We revisit the $e^+e^- \to \phi \pi^+\pi^-$ reaction within the $K_1$-$\bar{K}$-$K$ triangle dynamics framework, in which the $e^+e^-$ pair annihilates through one-
photon exchange approximation to produce a $K_1\bar{K}$ pair, followed by the $K_1 \to\phi K$ decay and the final-state $K\bar{K} \to \pi^+\pi^-$ rescattering. With the same theoretical formalism and model parameters, the $e^+e^- \to \phi K^+K^-$ reaction is investigated, and it is found that the predicted total cross sections for the $e^+ e^- \to \phi K^+ K^-$ reaction are in good agreement with the existing BESIII measurements. Our study shows that the triangle singularity in the $\phi K^+K^-$ channel is strongly suppressed, because the higher $K^+K^-$ mass threshold shifts the kinematics away from the triangle singularity condition and the phase space near the $K_1\bar{K}$ threshold is very limited. Moreover, the interference between the tree-level and loop amplitudes eliminates the remaining signal. These combined effects naturally explain the absence of a distinct $\phi(2170)$ signal in the $e^+ e^- \to \phi K^+ K^-$ reaction, provide a strong test of the model, and reinforce the picture that both reactions are governed by the same underlying mechanism, in which the $\phi(2170)$ state is produced in the $e^+ e^-$ annihilation from the $K_1$-$\bar{K}$-$K$ triangle loop.
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All authors Xiang Wei, Cheng Chen, Si-Wei Liu, Zu-Xin Cai, Gang Li, Xiao-Hai Liu, Ju-Jun Xie
High Energy Physics (Phenomenology)
New massive resonances at the LHC
Rosy Caliri
We investigate composite
Higgs models arising from a gauge-fermionic UV completion with partial compositeness, where the
Higgs boson emerges as a pseudo-Nambu-Goldstone
boson (pNGB), and top-partners appear as bound states of three hyperfermions, with $\mathrm{SU}(2)_L \times \mathrm{SU}(2)_R$ as the unbroken global subgroup. A bunch of new bound states is predicted by composite
Higgs models:
spin-0,
spin-1/2 and
spin-1 resonances. In this work we focus on the phenomenology of the
spin-1 resonances. We demonstrate that a generic prediction of these models is the existence of two neutral and one charged
spin-1 resonances, which mix significantly with the SM gauge
bosons. This mixing allows their single production in Drell-Yan processes at the LHC. We study the LHC phenomenology of these states and identify scenarios where their masses could be as low as $1.5~\mathrm{TeV}$, consistent with the existing LHC data.
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High Energy Physics (Phenomenology)
Colour sextet baryons in composite Higgs models
Manuel Kunkel
Composite
Higgs models with underlying fermionic descriptions predict a rich spectrum beyond the Standard Model. Besides the colour triplet fermionic resonances that act as top partners, also exotically coloured baryons can appear. In this contribution we summarise the phenomenology of colour sextet baryons. The dominant decay channel proceeds via a colour octet scalar, resulting in pair production signatures with four or six top
quarks. In an alternative mass hierarchy, the sextets produce bottom
quarks and a
collider-stable colour singlet. We derive recasting bounds on the sextet mass, which reach up to $2.64$ TeV.
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High Energy Physics (Phenomenology)
Measure of the kaon structure: generalized valence quark distribution functions and form factors
H. Nematollahi and K. Azizi
We investigate the structure of the $K^+$
meson through calculating its valence-
quark (anti
quark) generalized parton distribution functions (GPDs) and form factors (FFs). For this purpose, we use a theoretical framework which is based on the exponential representation scheme (ERS). In this scheme the valence-
quark GPDs of the light
mesons, including the kaon, are considered as the valence
quark distribution function crossed by the exponential of a profile function, at zero skewness. We apply the modified chiral
quark model ($\chi QM$ ) to obtain the input valence distribution functions of the kaon in above scheme and calculate its valence GPDs. The kaon's electromagnetic and gravitational form factors are also determined and compared with existing experimental data and the results of some theoretical and phenomenological models.
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High Energy Physics (Phenomenology)
FLARE: an open-source data workflow orchestration tool
Cameron Cooper Harris, Aman Desai and Paul Jackson
Flare is an open-source Python-based data workflow orchestration tool powered by b2luigi. It automates the workflow of Monte Carlo (MC) generators inside the Key4HEP stack, such as Whizard, MadGraph5 and Pythia8, together with fast detector simulation using Delphes. It also automates the Future Circular
Collider (FCC) physics analysis software workflow. These workflows are combined, giving a user an automated pipeline from MC production to final FCCAnalyses histograms. With its customisation options and Python API,
Flare simplifies executing FCC-ee analyses, especially when custom MC events are required.
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High Energy Physics (Phenomenology)
Hidden charm pentaquarks and the nature of $P_{c}$ states observed at LHCb
Zhi-Biao Liang, Jun-Jie Liu, Mu-Yang Chen et al. (+2 more)
We carry out a unified study of the low-lying $1S$-wave compact states and hadronic molecules composed of hidden charm pentaquarks $qqqc\bar{c}$ ($q=u,d$) within a semirelativistic potential
quark model. Apart from the linear confinement and one-gluon exchange potential between
quarks and/or antiquarks, one-
boson exchange potential is also included for baryon and
meson clusters within the pentaquark system. We also evaluate the fall-apart decays by combining the obtained spectra within the
quark exchange model. It is found that the $P_c (4312)^+$, $P_c (4440)^+$, and $P_c (4457)^+$ observed by the LHCb Collaboration in 2019 can be well explained by the hadronic molecules of $[\Sigma_c\bar{D}]_{1/2^-}^{1/2}(4318)$, $[\Sigma_c\bar{D}^*]_{1/2^-}^{1/2}(4437)$, and $[\Sigma_c\bar{D}^*]_{3/2^-}^{1/2}(4458)$, respectively. Meanwhile, $P_c(4380)^+$ reported by LHCb in 2015 may be assigned as the molecule $[\Sigma_c^*\bar{D}]_{3/2^-}^{1/2}(4382)$, except that it turns to be a narrow state other than a broad one shown by the experimental data. Our study shows that the $\sigma$- and $\rho$-
meson exchanges are crucial for the formation of $\Sigma_c^{(*)}\bar{D}^{(*)}$ bound states with isospin $I=1/2$. Depending on the potential strength of the $\sigma$ exchange, there may exist very shallow bound states of $\Lambda_c\bar{D}^{(*)}$ with isospin $I=1/2$ and $\Sigma_c^{(*)}\bar{D}^{(*)}$ with isospin $I=3/2$. Our study may provide useful information for further exploring the hidden-charm pentaquarks in future experiments.
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All authors Zhi-Biao Liang, Jun-Jie Liu, Mu-Yang Chen, Xian-Hui Zhong, Qiang Zhao
High Energy Physics (Phenomenology)
Neutralino Dark Matter in SU(5) after H.E.S.S. and Direct-Detection Searches
M. Adeel Ajaib and Fariha Nasir
We examine the impact of gamma-ray line and direct-detection searches on neutralino dark matter in supersymmetric SU(5) with non-universal gaugino masses. Under the assumption that neutralinos constitute all
halo dark matter, a nearly pure wino
benchmark at 1 TeV is essentially excluded by the H.E.S.S. line limits for both cusped and cored density profiles. Higgsino and wino-Higgsino
benchmarks are independently excluded by direct detection. In contrast, a bino
benchmark near thermal saturation combines suppressed present-day line emission with scattering below the displayed experimental limits. Mixed bino-wino solutions illustrate the complementarity of the two searches and the dependence of the line interpretation on the Galactic
halo profile. We relate these results to the GUT-scale gaugino hierarchy and the SU(5) scalar and
Higgs boundary conditions. Thermally underabundant solutions require additional production to realize the full-density assumption. Comparing the calculated signals with published electroweakino predictions, we identify the spectrum-dependent corrections and
collider tests needed to determine the surviving parameter space.
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High Energy Physics (Phenomenology)
Clarifying the puzzling mass shift of the $\psi(4160)$ via a reanalysis of $R$-value data with unquenched charmonium spectroscopy
Tian-Cai Peng and Xiang Liu
The long-standing upward shift of the extracted $\psi(4160)$ mass, from about $4.16$~GeV to $4.19$~GeV in later analyses, remains a puzzling issue in charmonium spectroscopy. In our previous study, this problem was investigated through the $B^+\to K^+\mu^+\mu^-$ process within an unquenched charmonium framework, where the lower-mass $\psi(4160)$ assignment was found to be compatible with the data. Here we revisit the BESII $R$-value data, which played an important role in the historical extraction of the higher $\psi(4160)$ mass, and provide an independent examination. In contrast to the conventional quenched picture with $\psi(4040)$, $\psi(4160)$, and $\psi(4415)$, the unquenched vector-charmonium spectrum contains six states: $\psi(4040)$, $\psi(4160)$, $\psi(4220)$, $\psi(4380)$, $\psi(4415)$, and $\psi(4500)$. Including these states together with the near-threshold $\psi(3770)$, we find that the BESII $R$-value line shape can be well reproduced over the full energy range while retaining the lower-mass $\psi(4160)$ assignment. The enhancement around $4.19$~GeV then arises from the coherent interplay among the nearby $\psi(4040)$, $\psi(4160)$, and $\psi(4220)$ amplitudes, rather than requiring an upward shift of the $\psi(4160)$ mass itself. The additional higher states also naturally describe the line-shape structure in the $4.4$~GeV region. We further show that the seven-resonance coherent amplitude contains six complex zeros, yielding $2^6=64$ mathematically equivalent solutions with identical line shapes but substantially different di-electron widths and relative phases. Comparing these solutions with available experimental information and representative unquenched charmonium predictions, we provide a qualitative assessment of their phenomenological consistency and highlight several solutions that appear more compatible with present information.
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High Energy Physics (Phenomenology)
Strange Two-Photon Exchange in Time-Like Electromagnetic Form Factors
Xu Cao, Yong-Hui Lin and Hai-Qing Zhou
While two-
photon exchange (TPE) effects in space-like nucleon electromagnetic form factors have been extensively studied for over two decades, their manifestations in the time-like region have yet to be definitively established. We propose the isospin-violating decay $J/\psi \to \bar{\Sigma}^{0}\Lambda$ and its charge-conjugate process as a sensitive probe of TPE contributions to time-like hyperon electromagnetic form factors. This channel provides a clean laboratory for isolating TPE effects through sensitive and robust polarization and
spin-correlation observables, which are particularly enhanced by the $\Lambda$-$\Sigma^0$ mass splitting. Combining a dispersion-relation analysis of the one-
photon-exchange contribution with explicit loop calculations of the TPE amplitudes, we perform a quantitative study of TPE effects in the threshold region. Our results demonstrate that the considered observables can provide unambiguous signatures of TPE contributions and present predictions for their size together with the associated theoretical uncertainties.
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High Energy Physics (Phenomenology)
Higher twists in QCD
W. Melnitchouk
Higher twists in deep-inelastic scattering (DIS) and related hard scattering processes provide a unique window on nonperturbative QCD dynamics, encoding
quark-gluon correlations and multiparton interactions beyond the leading-twist parton model. We present an overview of the theoretical foundations of higher twists in QCD, based on the operator product expansion, and discuss their intimate connection with
quark-
hadron duality in the transition between the resonance and scaling regimes. We review the phenomenology of higher-twist effects in unpolarized and polarized DIS, emphasizing their extraction from precision data through modern global QCD analyses that simultaneously determine both leading-twist parton distribution functions and higher-twist contributions. Finally, we discuss recent developments in the study of higher twists in semi-inclusive and exclusive reactions, and conclude by highlighting future opportunities to study QCD dynamics beyond leading twist at Jefferson Lab and the Electron-Ion
Collider that promise to deepen our understanding of
hadron structure.
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High Energy Physics (Phenomenology)
T-odd Effect from Two-Photon Exchange in SIDIS at Low Transverse Momentum
J.P. Ma and G.P. Zhang
We study T-odd effects through two-
photon exchange in semi-inclusive deeply inelastic scattering in the kinematic region where the produced
hadron has a low transverse momentum. The absorptive part of lepton-
quark scattering amplitude is calculated. Transverse momentum dependent factorization is performed with the absorptive part. Although the absorptive part is divergent, the physical results, i.e., the obtained differential cross-section, is finite. Including the T-odd effects, the differential cross section receives new contributions which have different angular dependence than that obtained with one-
photon exchange. Certain asymmetries can be introduced to detect the T-odd effects. Our results here are not only relevant to detecting new effect beyond the one-
photon approximation in the process but also relevant to searching for new physics at lepton-
proton colliders.
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High Energy Physics (Phenomenology)
Generalized parton distributions: Theory meets experiment
Yuxun Guo, Xiangdong Ji, Yao Ji et al. (+1 more)
Over the past three decades, generalized parton distributions (GPDs) have emerged as one of the most active and important areas of research in nucleon structure and
quantum chromodynamics (QCD). Since the last comprehensive review two decades ago, substantial progress has been made in experimental measurements of hard exclusive processes, such as deeply virtual Compton scattering and near-threshold $J/\psi$ production, as well as in increasingly sophisticated phenomenological analyses of GPDs that enable three-dimensional nucleon
tomography. Theoretical advances in perturbative coefficient functions, scale evolutions, and kinematic and power corrections have considerably improved the precision of GPD phenomenology, while new hard exclusive processes for probing GPDs have been explored. More interestingly,
lattice QCD can now directly access GPDs at fixed parton momentum fractions $x$ and skewness $\xi$ through large-momentum expansions, in addition to the traditional calculations of their moments, or generalized form factors. Significant progress has also been made in exploring the QCD energy-momentum tensor that encodes fundamental information on the nucleon's mass distribution, complete
spin structure, and spatial distributions of momentum current and color-Lorentz forces acting on
quarks and gluons.
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All authors Yuxun Guo, Xiangdong Ji, Yao Ji, Jialu Zhang