Mon·Sep 2, 2024Monday·September 2, 2024

1. 01*

   HEFT approach to investigate the muon g-2 anomaly at a muon collider

   Fabiola Fortuna🇲🇽 · Juan Manuel Márquez🇲🇽 · Pablo Roig🇲🇽

   In a previous work \cite{Buttazzo:2020ibd}, it has been pointed out that heavy new physics (NP) contributions to lepton dipole moments and high-energy cross-sections of lepton pairs into Higgs and $\gamma /Z$ bosons are connected, if the electroweak symmetry breaking is realized linearly. As a consequence, a multi-TeV muon collider would provide a unique test of NP in the muon $g$-2 through the study of high-energy processes such as ${\mu }^{+}{\mu }^{-}\to h+\gamma /Z$. Since the analysis involved a SMEFT approach to Higgs-processes, it could also be studied by the more general HEFT formulation. We compute the modification of the high-energy cross-section ${\mu }^{+}{\mu }^{-}\to h+\gamma /Z$ and $h\to {\mu }^{+}{\mu }^{-}+\gamma /Z$ decay using the dimension six HEFT Lagrangian and compare them with the SMEFT analysis. We find that, within the current HEFT analysis, there are plausible scenarios where the HEFT approach could lead to a higher sensitivity to test the NP contributions in the muon $g$-2. However, a more precise knowledge of the new HEFT parameters is needed for a definite conclusion, which motivates the search for complementary measurements.

   hep-phPRD(2025)·9 citations
2. 02*

   Inflation models with Peccei-Quinn symmetry and axion kinetic misalignment

   Hyun Min Lee🇰🇷 · Adriana G. Menkara🇰🇷 · Myeong-Jung Seong🇰🇷 · Jun-Ho Song🇰🇷

   We propose a consistent framework with the $U(1)$ Peccei-Quinn (PQ) symmetry for obtaining the initial condition for axion kinetic misalignment from inflation. We introduce a PQ complex scalar field and an extra Higgs doublet, which are conformally coupled to gravity, and three right-handed neutrinos for the seesaw mechanism. In the DFSZ type scenarios for the axion, we obtain the PQ anomalies from the Standard Model quarks carrying nonzero PQ charges in some of two Higgs doublet models, solving the strong CP problem by the QCD potential for the axion. Assuming that the PQ symmetry is explicitly violated in the scalar potential by quantum gravity effects, we show that a sufficiently large initial axion velocity can be obtained at the end inflation while avoiding the axion quality problem. As inflation is driven by the radial distance from the origin in the space of scalar fields close to the pole of the kinetic terms in the Einstein frame, we obtain successful inflationary predictions and set the initial axion velocity at the end of inflation. Focusing on the pure PQ inflation with a small running quartic coupling for the PQ field, we discuss the post-inflationary dynamics for the inflaton and the axion. As a result, we show that a sufficiently high reheating temperature, can be obtained dominantly from the Higgs-portal couplings to the PQ field, while being consistent with axion kinetic misalignment, the stability for the Higgs fields during inflation and the non-restoration of the PQ symmetry after reheating.

   hep-phastro-ph.COhep-thEPJC(2024)·9 citations
3. 03*

   Production potential of hidden-strange molecular pentaquarks through the ${\pi }^{-}p\to K^{\ast }\Sigma$ process

   Xiao-Yun Wang🇨🇳 · Yuan Gao🇨🇳 · Xiang Liu🇨🇳

   In this study, applying the effective Lagrangian approach, we investigate the reaction ${\pi }^{-}p\to K^{\ast }\Sigma$ to explore the production of the hidden-strange molecular pentaquarks $P_{s\bar{s}}$. Specifically, we analyze two scenarios, where the $J^P$ quantum numbers of $P_{s\bar{s}}$ are $3/2^{-}$ and $1/2^{-}$. Our results show that the contribution from $s$-channel $P_{s\bar{s}}$ exchange dominates the total cross section, surpassing those from $t$-channel $K^{(\ast )}$ exchange and $u$-channel $\Sigma$ exchange. Additionally, we present predictions for the differential cross section of the ${\pi }^{-}p\to K^{\ast }\Sigma$ process. Finally, we extend the 2-to-2 scattering process to the 2-to-3 Dalitz process and provide theoretical predictions for this scenario. Our findings suggest that the cross section for the ${\pi }^{-}p\to K^{\ast }\Sigma \to K^{+}{\pi }^{-}{\Sigma }^0$ process can reach several tens of $\mu b$ near the threshold, making it highly favorable for experimental measurement. However, the current scarcity of experimental data for the ${\pi }^{-}p\to K^{\ast }\Sigma$ reaction at threshold energy limits our ability to determine the properties of the hidden-strange molecular pentaquarks $P_{s\bar{s}}$ and related physical quantities. Therefore, additional experimental measurements of the ${\pi }^{-}p\to K^{\ast }\Sigma$ reaction at threshold are strongly encouraged, and correlation studies could be pursued at facilities such as J-PARC, AMBER, and upcoming HIKE and HIAF meson beam experiments.

   hep-phPRD(2025)·6 citations
4. 04*

   Pion Condensation and Pion Star from Holographic QCD

   Yidian Chen🇨🇳 · Mingshan Ding🇨🇳 · Danning Li🇨🇳 · Kazem Bitaghsir Fadafan🇮🇷 · Mei Huang🇨🇳

   The properties of QCD matter at finite isospin densities are investigated employing holographic hard-wall and soft-wall AdS/QCD models. It is confirmed that at high enough isospin densities, charged pions start to condense and the pion superfluid phase appears in the system. It is shown that the chiral condensate and the pion condensate can be transformed to each other and form a `chiral circle' in the superfluid phase. We derived the Equation of State (EoS) for pionic matter, calculated the normalized trace anomaly $\Delta$ and $(ϵ-3p)/m_{\pi }^4$, and analyzed the sound speed and adiabatic index. Additionally, we provided data on the mass-radius relation and tidal deformability of pion stars. The results indicate that the holographic models align well with lattice QCD concerning isospin density, axial-vector condensation, EoS, and trace anomaly, though discrepancies in sound speed and adiabatic index emerge at higher isospin chemical potentials. The holographic models closely match those from chiral perturbation theory ($\chi$PT), suggesting that they can be considered as five-dimensional description of $\chi$PT.

   hep-phPRD(2025)·7 citations
5. 05*

   Constraints on superheavy dark matter decaying into $h\nu$, $Z\nu$ and $W\ell$ -- Benchmark example within an extended seesaw framework

   O. Deligny🇫🇷

   Dark matter particles could be superheavy (mass $M_X\gtrsim 10^9$GeV) provided that their lifetime ${\tau }_X$ is extremely long, i.e. greater than $\simeq 10^{22}$yr. Such stringent constraints on ${\tau }_X$ are generally obtained by limiting the prompt emission of ultrahigh energy ($\gtrsim 10^9$GeV) gamma rays and neutrinos from the decay processes to below the corresponding flux upper bounds. In this paper, we show that even more severe bounds can be obtained for $M_X\gtrsim 10^{13}$GeV from the synchrotron radiation of electron decay byproducts in the Galaxy. We illustrate the power of these constraints using generic Higgs-induced $h\nu$ and gauge-induced $Z\nu /W\ell$ decay channels, motivated by particle-physics setups invoking right-handed neutrinos. As a concrete benchmark, we consider a superheavy dark-matter candidate within an extended type-I seesaw framework and show that the lower bounds on lifetime can be translated into upper bounds on a mass-mixing parameter $\delta M$, which must satisfy approximately $\delta M\lesssim 2\times 10^{-17}/[M_X/(10^9\mathrm{GeV}){]}^{0.5}$~GeV for $M_X\gtrsim 10^9$~GeV. Some implications in the context of inflationary cosmologies are discussed.

   hep-phEPJC(2025)·5 citations
6. 06*

   Energy dependence of deep-elastic scattering

   S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

   We discuss decreasing energy behavior of the differential cross-section of elastic hadron interactions at fixed large values of transferred momenta (deep--elastic scattering). This observable effect is relevant to the reflective scattering mode.

   hep-phMod.Phys.Lett.A(2025)·0 citations
7. 07*

   Estimating event-by-event multiplicity by a Machine Learning Method for Hadronization Studies

   Gábor Bíró🇭🇺 · Gábor Papp🇭🇺 · Gergely Gábor Barnaföldi🇭🇺

   Hadronization is a non-perturbative process, which theoretical description can not be deduced from first principles. Modeling hadron formation requires several assumptions and various phenomenological approaches. Utilizing state-of-the-art Deep Learning algorithms, it is eventually possible to train neural networks to learn non-linear and non-perturbative features of the physical processes. In this study, the prediction results of three trained ResNet networks are presented, by investigating charged particle multiplicities at event-by-event level. The widely used Lund string fragmentation model is applied as a training-baseline at $\sqrt{s}=7$ TeV proton-proton collisions. We found that neural-networks with $\gtrsim \mathcal{O}(10^3)$ parameters can predict the event-by-event charged hadron multiplicity values up to $N_{\mathrm{ch}}\lesssim 90$.

   hep-phphysics.comp-phInt.J.Mod.Phys.A(2025)·0 citations
8. 08*

   Local renormalisation from causal loop-tree duality

   German Sborlini🇪🇸 · Jose Rios-Sanchez🇪🇸

   We report recent progress on the development of a local renormalisation formalism based on causal loop-tree duality (cLTD). By performing an expansion around the UV-propagator in an Euclidean space, we manage to build counter-terms to cancel the non-integrable terms in the UV limit. This procedure is then combined with the so-called causal representation, and the UV expansion is performed at the level of on-shell energies. The resulting expressions are more compact, and they retain nice properties of the original causal representation. The proposed formalism is tested up to three-loops, with relevant families of topologies. In all the cases, we successfully cancel the UV divergences and achieve a smooth numerical implementation. These results constitute a first step towards a new renormalisation program in four space-time dimensions (by-passing DREG), perfectly suitable for fully numerical simulations.

   hep-phhep-thPoS(2025)·0 citations
9. 09*

   Semi-supervised permutation invariant particle-level anomaly detection

   Gabriel Matos🇺🇸 · Elena Busch🇺🇸 · Ki Ryeong Park🇺🇸 · Julia Gonski🇺🇸

   The development of analysis methods to distinguish potential beyond the Standard Model phenomena in a model-agnostic way can significantly enhance the discovery reach in collider experiments. However, the typical machine learning (ML) algorithms employed for this task require fixed length and ordered inputs that break the natural permutation invariance in collision events. To address this, a semi-supervised anomaly detection tool is presented that takes a variable number of particle-level inputs and leverages a signal model to encode this information into a permutation invariant, event-level representation via supervised training with a Particle Flow Network (PFN). Data events are then encoded into this representation and given as input to an autoencoder for unsupervised ANomaly deTEction on particLe flOw latent sPacE (ANTELOPE), classifying anomalous events based on a low-level and permutation invariant input modeling. Performance of the ANTELOPE architecture is evaluated on simulated samples of hadronic processes in a high energy collider experiment, showing good capability to distinguish disparate models of new physics.

   hep-phJHEP(2025)·8 citations
10. 10*

    Imprinting New Physics by using Angular profiles of the FCNC process $B_c\to D_s^{\ast }\left(\to D_s\pi \right){\ell }^{+}{\ell }^{-}$

    Hira Waseem🇵🇰 · Abdul Hafeez🇵🇰

    The decays governed by the flavor-changing-neutral-current transitions (FCNC), such as $b\to s{\ell }^{+}{\ell }^{-}$, provide an important tool to test the physics in and beyond the Standard Model (SM). This work focuses on investigating the FCNC process $B_c\to D_s^{\ast }\left(\to D_s\pi \right){\ell }^{+}{\ell }^{-}(\ell =e,\mu ,\tau )$. Being an exclusive process, the initial and final state meson matrix elements involve the form factors, which are non-perturbative quantities and need to be calculated using specific models. By using the form factors calculated in the covariant light-front quark model, we analyze the branching fractions and angular observables such as the forward-backward asymmetry $A_{FB}$, polarization fractions (Longitudinal and transverse) $F_{L(T)}$, CP asymmetry coefficients $A_i$ and CP-averaged angular coefficients $S_i$, both in the SM and some new physics (NP) scenarios. Some of these physical observables are a potential source of finding the physics beyond the SM and help us distinguish various NP scenarios.

    hep-phPTEP(2024)·0 citations
11. 11*

    Two-loop QCD corrections to Higgs radiative decay to vector quarkonium

    Yu Jia🇨🇳 · Zhewen Mo🇨🇳 · Jia-Yue Zhang🇨🇳

    The exclusive production of $J/\psi$ through Higgs boson radiative decay may serve a clean channel to extracting the charm quark Yukawa coupling. We calculate the two-loop QCD corrections to $H\to J/\psi ({\rm Y})+\gamma$ using an optimized nonrelativistic QCD (NRQCD) approach. We compute the $\mathcal{O}({\alpha }_s^2)$ correction in the direct channel, where Higgs directly couples to $c\bar{c}$, as well as the $\mathcal{O}({\alpha }_s)$ correction in the indirect channel, {\it viz.}, $H\to {\gamma }^{\ast }\gamma$ followed by the virtual photon fragmentation into $J/\psi$. Incorporating the destructive interference between the direct and indirect channels, we present to date the most accurate predictions for Higgs boson radiative decay into vector quarkonium, $\mathcal{B}(H\to J/\psi +\gamma )=3.27_{-0.07}^{+0.30}{}_{-0.06}^{+0.06}{}_{-0.13}^{+0.13}\times 10^{-6}$, and $\mathcal{B}(H\to {\rm Y}+\gamma )=1.34_{-0.31}^{+0.75}{}_{-0.20}^{+0.25}{}_{-0.05}^{+0.05}\times 10^{-8}$.

    hep-phhep-ex6 citations
12. 12*

    Undulators are ALP Factories

    Wen Yin🇯🇵 · Junya Yoshida🇯🇵

    Axion-like particles (ALPs) are known to be produced through axion-photon conversion in the presence of a stationary external magnetic field. Devices such as undulators and wigglers, which are used widely for photon production, e.g., in synchrotron radiation facilities, inherently possess strong magnetic fields, making them potential sources for ALP production. In this paper, we establish formalisms and formulas for studying ALP production in the ALP-photon-charged current system based on quantum field theory. We demonstrate that ALP production is inevitable in any undulator with the standard designs due to the electron Coulomb potential as well as a resonance effect depending on the ALP mass. In particular, ALPs are predominantly produced in a direction slightly misaligned with the photons' main direction. We propose placing detectors in the desired directions during operations of the originally planned experiments as an efficient approach to simultaneously probing ALPs. The calculation methods and formulas developed in this study are applicable to ALP production from other environments and productions of other particles beyond the standard model relevant to synchrotron radiations.

    hep-phhep-exphysics.ins-detPRD(2025)·6 citations
13. 13*

    CP-odd effects at NLO in SMEFT $WH$ and $ZH$ production

    Alejo N. Rossia🇬🇧 · Eleni Vryonidou🇬🇧

    CP-violation (CPV) is a rare phenomenon in the Standard Model whilst there is compelling indirect evidence for additional CPV sources in the Universe. The search for CPV effects at the LHC is thus one of the best-motivated precision tests of the Standard Model (SM) and an excellent probe of New Physics. NLO QCD corrections can affect the predictions for those measurements substantially. We study the impact of NLO QCD corrections in $WH$ and $ZH$ production in the Standard Model Effective Field Theory with bosonic CP-odd dimension-6 operators. We analyze the angular distributions at LO of those processes that can be used to probe CPV effects. We then show how NLO QCD effects modify those distributions. We encounter that the corrections have a clear angular dependence and differ between the SM, the dimension-6 squared and their interference, emphasising the need for an exact inclusion of NLO QCD in precision computations. We then perform a phenomenological analysis of $WH$ production at the LHC to study the impact of NLO QCD effects on the projected bounds on the CP-odd Wilson Coefficient $c_{\phi \tilde{W}}$. NLO QCD effects in the signal improve the bounds by $\sim 10\%$ but reduce the significance of the interference.

    hep-phJHEP(2024)·12 citations
14. 14*

    Discovering Dark Matter with the MUonE Experiment

    Gordan Krnjaic🇺🇸 · Duncan Rocha🇺🇸 · Isaac R. Wang🇺🇸

    The MUonE experiment aims to extract the hadronic contribution to the muon anomalous magnetic moment from a precise measurement of the muon-electron differential scattering cross section. We show that MUonE can also discover thermal relic dark matter using only its nominal experimental setup. Our search strategy is sensitive to models of dark matter in which pairs of pseudo-Dirac fermions are produced in muon-nucleus scattering in the target, and the heavier state decays semi-visibly to yield dilepton pairs displaced downstream from the interaction point. This approach can probe sub-GeV thermal-relic dark matter whose cosmological abundance is governed by the same model parameters that set the MUonE signal strength. Furthermore, our results show that the downstream ECAL plays a key role in rejecting backgrounds for this search, thereby providing strong motivation for the MUonE to keep this component in the final experimental design.

    hep-phPRL(2025)·9 citations
15. 15*

    Tunnelling and the Casimir effect on a $D$-dimensional sphere

    Jean Alexandre🇬🇧 · Drew Backhouse🇬🇧

    Two fundamental signatures of Quantum Mechanics are tunnelling and the Casimir effect. We examine the ground state energetic properties of a scalar field confined on a $D$-dimensional sphere, and subjected to these two effects. We focus on $D=2$ and $D=3$, with a non-minimal coupling of a massless scalar field to curvature, which provides a radius-dependent effective mass. This scenario allows tunnelling to be more important than the Casimir effect, in a certain regime of parameters, and potential implications in Early Cosmology are discussed for the case $D=3$, which could avoid a cosmological singularity.

    ↳ hep-thhep-phPRD(2024)·4 citations
16. 16*

    Scant evidence for thawing quintessence

    William J. Wolf🇬🇧 · Carlos García-García🇬🇧 · Deaglan J. Bartlett🇫🇷 · Pedro G. Ferreira🇬🇧

    New constraints on the expansion rate of the Universe seem to favor evolving dark energy in the form of thawing quintessence models, i.e., models for which a canonical, minimally coupled scalar field has, at late times, begun to evolve away from potential energy domination. We scrutinize the evidence for thawing quintessence by exploring what it predicts for the equation of state. We show that, in terms of the usual Chevalier-Polarski-Linder parameters, ($w_0$, $w_a$), thawing quintessence is, in fact, only marginally consistent with a compilation of the current data. Despite this, we embrace the possibility that thawing quintessence is dark energy and find constraints on the microphysics of this scenario. We do so in terms of the effective mass $m^2$ and energy scale $V_0$ of the scalar field potential. We are particularly careful to enforce un-informative, flat priors on these parameters so as to minimize their effect on the final posteriors. While the current data favors a large and negative value of $m^2$, when we compare these models to the standard $\Lambda$CDM model we find that there is scant evidence for thawing quintessence.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2024)·165 citations
17. 17*

    Magnetogenesis from axion-SU(2) inflation

    Axel Brandenburg🇸🇪 · Oksana Iarygina🇸🇪 · Evangelos I. Sfakianakis🇺🇸 · Ramkishor Sharma🇸🇪

    We describe a novel proposal for inflationary magnetogenesis by identifying the non-Abelian sector of Spectator Chromo Natural Inflation (SCNI) with the ${\mathrm{SU}(2)}_{\mathrm{L}}$ sector of the Standard Model. This mechanism relies on the recently discovered attractor of SCNI in the strong backreaction regime, where the gauge fields do not decay on super-horizon scales and their backreaction leads to a stable new trajectory for the rolling axion field. The large super-horizon gauge fields are partly transformed after the electroweak phase transition into electromagnetic fields. The strength and correlation length of the resulting helical magnetic fields depend on the inflationary Hubble scale and the details of the SCNI sector. For suitable parameter choices we show that the strength of the resulting magnetic fields having correlation lengths around $1\mathrm{Mpc}$ are consistent with the required intergalactic magnetic fields for explaining the spectra of high energy $\gamma$ rays from distant blazars.

    ↳ astro-ph.COhep-phhep-thJCAP(2024)·15 citations
18. 18*

    On the mass distribution of the LIGO-Virgo-KAGRA events

    Mehdi El Bouhaddouti🇺🇸 · Ilias Cholis🇺🇸

    The merging black hole binaries detected by the LIGO-Virgo-KAGRA (LVK) gravitational-wave observatories, may help us shed light on how such binaries form. In addition, these detections can help us probe the hypothesized primordial black holes, a candidate for the observed abundance of dark matter. In this work, we study the black-hole mass distribution obtained from the LVK binary black hole merger events. We obtain that distribution by first associating a skewed normal distribution to each event detected with a signal to noise ratio (SNR) $>$ 8 and then summing all such distributions. We also simulate black hole binaries from two separate populations of merging binaries. One of these is a stellar-origin population that follows a mass-distribution similar to the zero-age mass function of stars. The second population of black holes follows a Gaussian mass-distribution. Such a distribution could approximate a population of black hole binaries formed from earlier black hole mergers in dense stellar environments, or binaries of primordial black holes. For those populations, we evaluate the number of detectable events and fit their combination to the LVK observations. In our work, we rely on a wide range of stellar-origin black-hole mass distributions. We find that the observed LVK events can be fitted much better by the combination of such a stellar-origin mass distribution and a Gaussian distribution, than by the stellar-origin mass distribution alone.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2025)·8 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.