Tue·Jun 4, 2024Tuesday·June 4, 2024

1. 01*

   Formation and decay of oscillons after inflation in the presence of an external coupling, Part-I: Lattice simulations

   Mohammed Shafi🇮🇳 · Edmund J. Copeland🇬🇧 · Rafid Mahbub🇺🇸 · Swagat S. Mishra🇬🇧 · Soumen Basak🇮🇳

   We investigate the formation and decay of oscillons during the post-inflationary reheating epoch from inflaton oscillations around asymptotically flat potentials $V(\phi )$ in the presence of an external coupling of the form $\frac{1}{2}{g}^2{\phi }^2{\chi }^2$. It is well-known that in the absence of such an external coupling, the attractive self-interaction term in the potential leads to the formation of copious amounts of long-lived oscillons both for symmetric and asymmetric plateau potentials. We perform a detailed numerical analysis to study the formation of oscillons in the $\alpha$-attractor E- and T-model potentials using the publicly available lattice simulation code $\mathcal{C}$osmo$\mathcal{L}$attice. We observe the formation of nonlinear oscillon-like structures with the average equation of state $⟨w_{\phi }⟩\simeq 0$ for a range of values of the inflaton self-coupling $\lambda$ and the external coupling $g^2$. Our results demonstrate that oscillons form even in the presence of an external coupling and we determine the upper bound on $g^2$ which facilitates oscillon formation. We also find that eventually, these oscillons decay into the scalar inflaton radiation as well as into the quanta of the offspring field $\chi$. Thus, we establish the possibility that reheating could have proceeded through the channel of oscillon decay, along with the usual decay of the oscillating inflaton condensate into $\chi$ particles. For a given value of the self-coupling $\lambda$, we notice that the lifetime of a population of oscillons decreases with an increase in the strength of the external coupling, following an (approximately) inverse power-law dependence on $g^2$.

   hep-phastro-ph.COgr-qchep-thJCAP(2024)·24 citations
2. 02*

   Cutting the Scotogenic loop: Adding flavor to Dark Matter

   Ranjeet Kumar🇮🇳 · Newton Nath🇮🇹 · Rahul Srivastava🇮🇳

   We introduce a framework for hybrid neutrino mass generation, wherein scotogenic dark sector particles, including dark matter, are charged non-trivially under the $A_4$ flavor symmetry. The spontaneous breaking of the $A_4$ group to residual ${\mathcal{Z}}_2$ subgroup results in the ``cutting" of the radiative loop. As a consequence the neutrinos acquire mass through the hybrid ``scoto-seesaw" mass mechanism, combining aspects of both the tree-level seesaw and one-loop scotogenic mechanisms, with the residual ${\mathcal{Z}}_2$ subgroup ensuring the stability of the dark matter. The flavor symmetry also leads to several predictions including the normal ordering of neutrino masses and ``generalized $\mu -\tau$ reflection symmetry" in leptonic mixing. Additionally, it gives testable predictions for neutrinoless double beta decay and a lower limit on the lightest neutrino mass. Finally, $A_4\to {\mathcal{Z}}_2$ breaking also leaves its imprint on the dark sector and ties it with the neutrino masses and mixing. The model allows only scalar dark matter, whose mass has a theoretical upper limit of $\lesssim$ 600 GeV, with viable parameter space satisfying all dark matter constraints, available only up to about 80 GeV. Conversely, fermionic dark matter is excluded due to constraints from the neutrino sector. Various aspects of this highly predictive framework can be tested in both current and upcoming neutrino and dark matter experiments.

   hep-phhep-exJHEP(2024)·26 citations
3. 03*

   Inhomogenuous instabilities at large chemical potential in a rainbow-ladder QCD model

   Theo F. Motta🇩🇪 · Julian Bernhardt🇩🇪 · Michael Buballa🇩🇪 · Christian S. Fischer🇩🇪

   In this work we continue our efforts to study the existence of a phase with an inhomogeneous, i.e., spatially varying, chiral condensate in QCD. To this end we employ a previously established method of stability analysis of the two-particle irreducible effective action in a truncation that corresponds to a rainbow-ladder approximation of the quark-gluon interaction of QCD. If the analysis is restricted to homogeneous phases, the phase diagram features a first-order chiral transition in the lower-temperature regime. Performing the stability analysis along the lower-chemical-potential border of the corresponding spinodal region, we find that below a certain temperature the homogeneous chirally symmetric solution is unstable against inhomogeneous condensation. We argue that this instability may persist to chemical potentials above the homogeneous first-order phase boundary, in which case it signals the existence of an inhomogeneous ground state. Our methodology is also applicable for more sophisticated truncations of the QCD effective action.

   hep-phnucl-thPRD(2024)·16 citations
4. 04*

   Looking for New Physics Through the Exclusive $b\to s\nu \bar{\nu }$ Modes

   Olcyr Sumensari🇫🇷

   The Belle-II experiment has recently measured $\mathcal{B}(B^{+}\to K^{+}\nu \bar{\nu })$, which appears to be almost $3\sigma$ larger than its Standard Model (SM) prediction. In this talk, I will critically revisit the status of the SM predictions for the $B\to K^{(\ast )}\nu \bar{\nu }$ decays, and discuss the interpretation of the recent Belle-II measurement in terms of a general Effective Field Theory, as well as concrete models of physics beyond the SM.

   hep-ph3 citations
5. 05*

   CP asymmetry from the effect of the isospin symmetry breaking during B-meson decay

   Wan-Ying Yao🇨🇳 · Gang Lü🇨🇳 · Xin-Heng Guo🇨🇳 · Hai-Feng Ou🇨🇳

   The direct CP asymmetry in quasi-two-body decays of $B\to (V\to {\pi }^{+}{\pi }^{-})P$ is investigated in the perturbative QCD method, where P represents a pseudoscalar meson and V refers to $\rho$, $\omega$ and $\varphi$ mesons, respectively. We present the amplitude of the quasi-two-body decay process and investigate the effects of mixed resonances involving ${\rho }^0-\omega$, ${\rho }^0-\varphi$ and $\omega -\varphi$, while considering the impact of isospin symmetry breaking. We observe a significant CP asymmetry when the invariant mass of the ${\pi }^{+}{\pi }^{-}$ pair is within the resonance ranges of $\rho$, $\omega$ and $\varphi$ mesons. Consequently, we proceed to quantify the regional CP asymmetry in these resonance regions. A significant difference is observed when comparing results obtained with and without interferences of the three vector mesons and isospin conservation. The CP asymmetry results obtained from the three-body decay process, without interference due to isospin conservation by the perturbative QCD method, are in agreement with the newly updated data acquired by the LHCb experiment.

   hep-phCPC(2025)·1 citation
6. 06*

   Unraveling Gluon TMDs in $J/\psi$ and Pion production at the EIC

   Khatiza Banu🇮🇳 · Asmita Mukherjee🇮🇳 · Amol Pawar🇮🇳 · Sangem Rajesh🇮🇳

   We investigate the azimuthal asymmetries such as $\cos 2{\varphi }_T$ and Sivers symmetry for $J/\psi$ and ${\pi }^{\pm }$ production in electron-proton scattering, focusing on scenarios where the $J/\psi$ and the pion are produced in an almost back-to-back configuration. The electron is unpolarized, while the proton can be unpolarized or transversely polarized. For the $J/\psi$ formation, we use non-relativistic QCD (NRQCD), while ${\pi }^{\pm }$ is formed due to parton fragmentation. In this kinematics, we utilize the transverse momentum-dependent factorization framework to calculate the cross sections and asymmetries. We consider both quark and gluon-initiated processes and show that the gluon contribution dominates. We provide numerical estimates of the upper bounds on the azimuthal asymmetries, as well as employ a Gaussian parametrization for the gluon transverse momentum distributions (TMDs), within the kinematical region accessible by the upcoming Electron-Ion Collider (EIC).

   hep-phPRD(2024)·8 citations
7. 07*

   Form factors of ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}$ within light-cone QCD sum rules

   Hui-Hui Duan🇨🇳 · Yong-Lu Liu🇨🇳 · Qin Chang🇨🇳 · Ming-Qiu Huang🇨🇳

   In this work, we calculated the form factors of the weak decay process ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}$, where the final charm baryon represents an excited state with spin-parity ${\frac{1}{2}}^{-}$. Utilizing the light-cone QCD sum rules approach, we incorporated the contributions of the lowest two charm baryon states: the ground state ${\Lambda }_c$ with $J^P={\frac{1}{2}}^{+}$ and the excited state ${\Lambda }_c(2595{)}^{+}$ with $J^P={\frac{1}{2}}^{-}$ in the hadronic representation of the ${\Lambda }_b\to {\Lambda }_c(2595{)}^{+}$ transition correlation function. This approach allows us to extract the form factors of the ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}$ from ${\Lambda }_b^0\to {\Lambda }_c^{+}$ transition. During the light-cone QCD sum rules procedure, we employed the light-cone distribution amplitudes (LCDAs) of the ${\Lambda }_b$ baryon. Furthermore, by combining these form factors with the helicity amplitudes of the bottom baryon transition matrix elements, we calculated the differential decay widths for the processes ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}{\ell }^{-}{\bar{\nu }}_{\ell }$ and provided the optimal choice of the interpolating current for ${\Lambda }_c$ in this process. Additionally, within the lifetime of ${\Lambda }_b^0$, we obtained the absolute branching fractions for the semileptonic decays ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}{\ell }^{-}{\bar{\nu }}_{\ell }$. With the branching fractions of ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}{\ell }^{-}{\bar{\nu }}_{\ell }$ calculated in this work, we also determined the parameter $R({\Lambda }_c(2595{)}^{+})$ which tests the lepton flavor universality. This parameter is defined as the ratio of branching fractions $Br({\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}{\tau }^{-}{\bar{\nu }}_{\tau })$ and $Br({\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}{\mu }^{-}{\bar{\nu }}_{\mu })$. Our results provide a valuable theoretical test for these decay channels and offer insights into the LCDAs of bottom baryons, paving the way for further in-depth investigations.

   hep-phhep-thEPJC(2024)·6 citations
8. 08*

   Analysis of three-body decays $B\to D(V\to )PP$ under the factorization-assisted topological-amplitude approach

   Si-Hong Zhou🇨🇳 · Run-Hui Li🇨🇳 · Xiao-Yao Lü🇨🇳

   Motived by the accumulated experimental results on three-body charmed $B$ decays with resonance contributions in Babar, LHCb and Belle (II), we systematically analyze $B_{(s)}\to D_{(s)}(V\to )P_1{P}_2$ decays with $V$ representing a vector resonance ($\rho ,K^{\ast },\omega$ or $\varphi$) and $P_{1,2}$ as a light pseudoscalar meson (pion or kaon). The intermediate subprocesses $B_{(s)}\to D_{(s)}V$ are calculated with the factorization-assisted topological-amplitude (FAT) approach and the intermediate resonant states $V$ described by the relativistic Breit-Wigner distribution successively decay to $P_1{P}_2$ via strong interaction. Taking all lowest resonance states ($\rho ,K^{\ast },\omega ,\varphi$) into account, we calculate the branching fractions of these decay modes as well as the Breit-Wigner-tail effects for $B_{(s)}\to D_{(s)}(\rho ,\omega \to )KK$. Our results agree with the data by Babar, LHCb and Belle (II). Among the predictions that are still not observed, there are some branching ratios of order $10^{-6}-10^{-4}$ which are hopeful to be measured by LHCb and Belle II. Our approach and the perturbative QCD approach (PQCD) adopt the compatible theme to deal with the resonance contributions. What's more, our data for the intermediate two-body charmed $B$-meson decays in FAT approach are more precise. As a result, our results for branching fractions have smaller uncertainties, especially for color-suppressed emission diagram dominated modes.

   hep-phPRD(2024)·8 citations
9. 09*

   Upper limit on the axion-photon coupling from Markarian 421

   Hai-Jun Li🇨🇳 · Wei Chao🇨🇳 · Yu-Feng Zhou🇨🇳

   Markarian 421 is a well-known nearby BL Lac blazar at the redshift $z=0.031$. Many previous works were investigated to constrain the axion-photon coupling from its TeV gamma-ray observations, showing the upper limit on the coupling constant $g_{a\gamma }\lesssim 2.0\times 10^{-11}\mathrm{Ge}{\mathrm{V}}^{-1}$ for the axion mass $[5.0\times 10^{-10}\mathrm{eV}\lesssim m_a\lesssim 5.0\times 10^{-7}\mathrm{eV}]$. While in this work, we obtain a more stringent upper limit on the axion-photon coupling from the 1038 days gamma-ray observations of the blazar Markarian 421. The long-term gamma-ray spectra are measured by the collaborations Large Area Telescope on board NASA's Fermi Gamma-ray Space Telescope (Fermi-LAT) and High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory from 2015 June to 2018 July. We show the best-fit spectral energy distributions (SEDs) of Markarian 421 under the null and axion hypotheses. Then we set the axion-photon limit in the $\{m_a,g_{a\gamma }\}$ plane. The 99% $C.L.$ upper limit set by Markarian 421 is $g_{a\gamma }\lesssim 4.0\times 10^{-12}\mathrm{Ge}{\mathrm{V}}^{-1}$ for the axion mass $[1.0\times 10^{-9}\mathrm{eV}\lesssim m_a\lesssim 1.0\times 10^{-8}\mathrm{eV}]$. It is the most stringent upper limit in this axion mass region.

   hep-phastro-ph.HEPLB(2024)·20 citations
10. 10*

    Nucleon Consumption and Mass-Energy Conversion Induced by Dark Matter

    Shao-Feng Ge🇨🇳 · Xiao-Dong Ma🇨🇳

    We propose the nucleon consumption induced by dark matter (DM) as a new scenario to overcome the energy threshold of direct detection. It can be realized with proton ($\chi +p\to \chi +{\ell }^{+}$) or neutron ($\chi +n\to \chi +\nu$) target. Both effective operators and concrete models are provided to illustrate the idea. Since the initial DM and nucleon velocity is only $10^{-3}$ and $1/4$ of the speed of light, respectively, the cross section and hence event rate are determined by the involved particle masses and not affected by the nucleon Fermi motion. Of the two realizations, the proton consumption has richer phenomena with both charged lepton and the daughter nuclei de-excitation to allow double or even triple coincidence to significantly suppress the background. We also illustrate the projected sensitivities at DM and neutrino experiments such as PandaX-4T, DUNE, JUNO, and Hyper-K.

    hep-phhep-exPRD(2024)·3 citations
11. 11*

    The new $Z^{\prime }$ boson of the Bestest Little Higgs Model as a portal to signatures of Higgs bosons $h_0$ and $H_0$ at the future muon collider

    J. M. Martínez-Martínez🇲🇽 · A. Gutiérrez-Rodríguez🇲🇽 · E. Cruz-Albaro🇲🇽 · M. A. Hernández-Ruíz🇲🇽

    We study the new $Z^{\prime }$ boson as a portal for the production of Higgs bosons $h_0$ and $H_0$ predicted by the Bestest Little Higgs Model through the Higgs-strahlung processes ${\mu }^{+}{\mu }^{-}\to (Z,Z^{\prime })\to Z{h}_0,Z{H}_0$. We focus on the resonance and non-resonance effects of the $Z{h}_0,Z{H}_0$ signals. In our analysis, we consider the center-of-mass energies of $\sqrt{s}=3,4,6,10,30$ TeV and integrated luminosities of $\mathcal{L}=2,4,6,10,30$ $\mathrm{a}{\mathrm{b}}^{-1}$ projected for a future muon collider. The possibility of performing precision measurements for the Higgs bosons $h_0$ and $H_0$ is very promising at the future muon collider. Furthermore, our results may be helpful to the High Energy Physics community. Complementarily, we generate and provide the Feynman rules necessary for studying the processes ${\mu }^{+}{\mu }^{-}\to (Z,Z^{\prime })\to Z{h}_0,Z{H}_0$.

    hep-phCPC(2025)·3 citations
12. 12*

    Majorana mass generation, gravitational waves and cosmological tensions

    Pasquale Di Bari🇬🇧

    A neutrino Majorana mass generation in the early universe might have left imprints in cosmological observables. It can source the production of a detectable stochastic background of primordial gravitational waves with a spectrum that combines a contribution from a first order phase transition production and from the vibration of global cosmic strings. An intriguing possibility is given by the split seesaw model. In this case, in addition to the traditional high scale seesaw, a low scale neutrino Majorana mass generation can solve a potential primordial deuterium problem and ameliorate the cosmological tensions of the $\Lambda$CDM model. At the same time, it can also produce subdominant contribution to the NANOGrav signal of a stochastic background of gravitational waves (GWs), in addition to the astrophysical dominant contribution from supermassive black hole mergers.

    hep-ph1 citation
13. 13*

    Neutrino oscillation with minimal length uncertainty relation via wave packet approach

    M.M. Ettefaghi🇮🇷

    Theories of Quantum Gravity as well as string theory suggest the existence of a minimal measurable length and the related Generalized Uncertainty Principle (GUP). The universality of Quantum Gravity implies that the GUP influences every quantum mechanical process. Neutrino oscillation as a quantum phenomenon exhibits quantumness at macroscopic distances and could provide potentially a suitable room for quantum foundation explorations. In this paper, we perturbatively derive the neutrino oscillation probability based on the GUP and by treating neutrinos as wave packets. We see that the GUP modifications are dependent on the effective position width of the transition amplitude ${\sigma }_x$ such that with the smaller ${\sigma }_x$ we can obtain a stronger bound on the minimal length scale in comparison to what is expected from standard model interactions. More explicitly, one can obtain an upper bound about $5\times 10^{25}$ for the deformation parameter, ${\beta }_0$, with accelerator neutrino experiments such as MINOS, provided that ${\sigma }_x\sim 10^{-15}\text{m}$ which is reasonable since the energy of these neutrinos is of the order of a few GeV.

    hep-phPLB(2024)·4 citations
14. 14*

    Cherenkov Telescope Arrays for High-Energy Neutrino Detection in Mountain Ranges

    Tariq Bitam🇩🇿 · Bouzid Boussaha🇩🇿 · Mossaab Messamah🇩🇿

    The present study investigates the feasibility of employing Cherenkov Telescope Array (CTA) technology for the detection of ultra-high-energy (UHE) neutrino-tau particles. By observing the Cherenkov light produced by charged particles resulting from neutrino-tau interactions within mountainous regions, the research seeks to assess the viability of detecting neutrinos within the PeV to EeV energy range. The present paper details the methodology used to calculate the effective detection area and the interaction probabilities of neutrino-tau within the mountains, as well as the flux of Cherenkov photons generated by tau leptons. Furthermore, the present paper addresses the selection of optimal parameters for the telescopes, including mountain dimensions, telescope height, the distance between telescopes, and the distance from the telescopes to the mountain. Strategic placement of the telescopes and the identification of mountain ranges in Algeria that are most suitable for detecting these elusive particles are also discussed. The findings and recommendations for the optimal distribution of telescopes across the selected mountain range are presented, aiming to enhance the detection capabilities for high-energy neutrino-tau particles.

    hep-phastro-ph.HE0 citations
15. 15*

    Compact dwarfs made of light-quark nuggets

    Hao-Song You🇨🇳 · Hao Sun🇨🇳 · Hong-Bo Li🇨🇳 · Cheng-Jun Xia🇨🇳 · Ren-Xin Xu🇨🇳

    Utilizing an equivparticle model with both linear confinement and leading-order perturbative interactions, we obtain systematically the properties of strangelets and nonstrange quark matter ($ud$QM) nuggets at various baryon ($A$) and charge ($Z$) numbers, where the detailed single-quark-energy levels are fixed by solving Dirac equations in mean-field approximation (MFA). We then examine the structures of compact dwarfs made of light strangelets or $ud$QM nuggets forming body-centered cubic lattices in a uniform electron background. Despite the strangelets and $ud$QM nuggets generally become more stable at larger $A$, the compact dwarfs are still stable since the fusion reactions between those objects do not take place in the presence of a Coulomb barrier, which is similar to the cases of light nuclei in normal white dwarfs. If $ud$QM dwarfs or strangelet dwarfs are covered with normal matter, their masses and radii become larger but do not exceed those of ordinary white dwarfs. Finally, we investigate the radial oscillation frequencies of $ud$QM dwarfs and strangelet dwarfs, and find that their frequencies are typically higher than traditional white dwarfs. The stability of compact dwarfs are then analysised by examining radial oscillation frequencies of the fundamental mode, where compact dwarfs covered by normal matter are still stable.

    hep-phnucl-thPRD(2024)·0 citations
16. 16*

    Extended Scotogenic Model of Neutrino Mass and Proton Decay

    Takaaki Nomura🇨🇳 · Oleg Popov🇨🇳

    The current article presents an extension of the classical scotogenic neutrino mass paradigm, where the three issues in particle physics: dark matter, smallness of neutrino mass, and stability of the proton are interconnected. The scenario encompasses the neutrino mass as well as the proton decay as a consequence of an existence of the dark matter. The study successfully achieves the correlation between the naturally small neutrino masses and naturally long proton lifetime in the present paradigm. Furthermore, all relevant cosmological, collider, and flavor physics constraints are incorporated in the detailed analysis. The scotogenic fermionic dark matter with the mass in the range from $100$ GeV to $10$ TeV successfully satisfies all relevant constraints. The valid range of $2.51\times 10^{-5}<\lambda <2\times 10^{-3}$ is obtained for the 2HDM $\lambda$ coupling. We give a brief discussion, as well as, outline some of the future prospects.

    hep-phhep-exPRD(2024)·8 citations
17. 17*

    Scalar boson stars: (thermo)dynamics and gravitational equilibria

    G.A. Kozlov🇷🇺

    We analyse the (thermo)dynamics of the scalar degrees of freedom in the scalar boson stars through the dark matter density under extreme conditions. The boson stars are studied in terms of a dark scalar sector in such a way this sector couples to the standard model Higgs boson doublet plus gravity.The stability of the BS is investigated at the level of the interaction between the scalars with the scale invariance breaking triggered by the electroweak symmetry breaking plus gravity. Analytic methods have been applied to an effective version of the theory, the scalar "tower" approximation, which should preserve an exact scale invariance. The production of the scalar dark matter and its decay have been discussed.

    hep-phPhys.Part.Nucl.(2025)·0 citations
18. 18*

    Intuitive study to the scalar boson stars formation

    G.A. Kozlov🇷🇺

    We study the feebly interacting dark matter with the Standard Model fields, where the preceding and the latter ones are the constituents of the bosonic cosmological objects, the scalar boson stars (BS). The scalar dark matter (SDM) massive fields can form the macroscopic scalar bound state when minimally coupled to gravity (GR). The star may have approximately a stationary form with an asymptotically flat geometry, and the maximal mass of the BS is larger than the solar mass. We consider an effective description of a more complete model with the (thermo)dynamic potential of the BS at finite temperature. The formation of the BS may also be explained in terms of the electric fluxes of the hidden vector field under the influence of the SDM field as the cosmological dynamical quantity minimally coupled to GR. The SDM fields may fluctuate with the temperature and is established around the equilibrium state at some weak background scale.

    hep-ph0 citations
19. 19*

    Critical dynamics of Model H within the real-time fRG approach

    Yong-rui Chen🇨🇳 · Yang-yang Tan🇨🇳 · Wei-jie Fu🇨🇳

    The critical dynamics of Model H with a conserved order parameter coupled to a transverse momentum density which describes the gas-liquid or binary-fluid transitions is investigated within the functional renormalization group approach formulated on the closed time path. According to the dynamic scaling analysis, Model H and QCD critical end point belong to the same dynamic universality class in the critical region. The higher-order correction of the transport coefficient $\bar{\lambda }$ and shear viscosity $\bar{\eta }$ arising from mode-couplings are obtained by calculating the two-point correlation functions. The flow equation of a dimensionless coupling constant for nondissipative interactions is derived to look for the fixed-point solution of the system. The scaling relation between the critical exponent of the transport coefficient and that of the shear viscosity is estimated. Finally, the dynamic critical exponent $z$ is obtained as a function of the spatial dimension $d$.

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

    Les Houches 2023: Physics at TeV Colliders: Standard Model Working Group Report

    J. Andersen🇬🇧 · B. Assi🇺🇸 · K. Asteriadis🇩🇪 · P. Azzurri🇮🇹 · G. Barone🇺🇸 · A. Behring🇨🇭 · A. Benecke🇧🇪 · S. Bhattacharya🇺🇸 · E. Bothmann🇩🇪 · S. Caletti🇨🇭 · X. Chen🇨🇳 · M. Chiesa🇮🇹 and 72 other authors

    This report presents a short summary of the activities of the "Standard Model" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 12-30 June, 2023).

    hep-ph40 citations
21. 21*

    An AI-Inspired Numerical Method in the Quark Model: Application to Finding the Wave Functions for Heavy Tetraquark States

    Daeho Park🇰🇷 · Su Houng Lee🇰🇷

    The current ongoing advancements in AI have shed light on the landscape of numerical analysis in science. Inspired by the path of achievement of AI, we have developed a method to construct accurate ground state wave functions of multiquark configurations within a quark model. We successfully tested our method through comparisons with meson-type two-body systems with analytic and numerical solutions. We then applied our method to find the ground-state solutions of $T_{cc}$($ud\bar{c}\bar{c}$) and $T_{bb}$($ud\bar{b}\bar{b}$) states. Our findings indicate that our approach outperforms existing methods, achieving greater accuracy in reproducing highly intricate configurations. Within the model parameters, we find that the $T_{cc}$ is a compact multiquark configuration.

    hep-ph3 citations
22. 22*

    Impact of Vector like quarks on $(g-2{)}_{\mu }$ with X-II-2HDM scenario and its phenomenological implications

    Md. Raju🇮🇳 · Abhi Mukherjee🇮🇳 · Jyoti Prasad Saha🇮🇳

    The recent observation of the muon $(g-2{)}_{\mu }$ anomaly continues to challenge the explanations provided by the Standard Model. However, this anomaly can potentially find reconciliation within the framework of two-Higgs doublet models, provided that the pseudoscalar mass remains low. The introduction of additional fermionic components, such as a generation of vector-like quarks, not only broadens the acceptable parameter range for elucidating the anomaly but also presents an opportunity to circumvent conflicts with constraints from B-decays and heavy Higgs searches. We demonstrate the efficacy of fitting the anomaly in the muon magnetic moment within these models, assuming that vector-like quarks do not undergo mixing with Standard Model quarks. With interactions following a type-X pattern for standard model quarks and a type-II pattern for vector-like quarks, results in models designated as type-XII2HDMVLQ. Additionally, we have explored double Higgs production within this model and observed when both the heavy Higgs and VLQ contribute the double Higgs production cross section significantly enhanced.

    hep-phhep-th1 citation
23. 23*

    Chiral Symmetry Breaking and Pion Decay in a Magnetic Field

    Prabal Adhikari🇺🇸 · Brian C. Tiburzi🇺🇸

    The pattern of chiral symmetry breaking is exploited to compute vector and axial-vector pion matrix elements in a uniform magnetic field. Our results are model independent, and thereby constitute low-energy theorems that must be obeyed by QCD in external magnetic fields. Chiral perturbation theory, lattice QCD and Nambu-Jona-Lasinio results are compared. While there is some tension between chiral perturbation theory and lattice QCD, the tension between low-energy QCD and the Nambu-Jona-Lasinio model is more acute. As an application, the matrix elements are utilized to compute pion decay rates in a magnetic field.

    hep-phhep-latPRD(2026)·9 citations
24. 24*

    Tau Data-Based Evaluations of the hadronic vacuum polarization contribution to the muon $g-2$

    Pere Masjuan🇪🇸 · Alejandro Miranda · Pablo Roig🇲🇽

    We review the tau data-driven computation of Euclidean windows for the hadronic vacuum polarization contribution to the muon anomalous magnetic moment (a_mu), which agree with the lattice results, making the difference of the $e^{+}{e}^{-}$ data-driven methods with them more intriguing. This conundrum needs to be solved by next year, when the final FNAL a_mu measurement will be published, in order to extract firm conclusions on possible new physics effects.

    hep-phhep-exhep-latSciPost Phys.Proc.(2025)·4 citations
25. 25*

    Higgs boson decays $h\to MZ$ in the TNMSSM

    Huai-cong Hu🇨🇳 · Zhao-Yang Zhang🇨🇳 · Ning-Yu Zhu🇨🇳 · Hai-Xiang Chen🇨🇳

    We study the SM-like Higgs boson decays $h\to MZ$ in the Triplet extended NMSSM (TNMSSM),where M is a vector meson ($\rho$, $\omega$, $\varphi$, $J/\Psi$, ${\rm Y}$). Compared to the minimal supersymmetric standard model (MSSM), the TNMSSM includes two new SU(2) triplets with hypercharge $\pm 1$ and a SM gauge singlet which are coupled to each other. The indirect contributions to the decays $h\to MZ$ are produced from the effective $h\gamma Z$ vertex, and they are more important than the direct contributions. The results of this work would encourage a detection on $h\to Z\gamma$ at the future high energy colliders for exploring new physics beyond the SM.

    hep-phCPC(2024)·8 citations
26. 26*

    The light quarkonium and charmonium mass shifts in an unquenched quark model

    Xiaoyun Chen🇨🇳 · Yue Tan🇨🇳

    The unquenched quark model for the light quarkonium and the charmonium states is explored in the present work. The quark-pair creation operator in the ${}^3{P}_0$ model, which mix the two-quark and four-quark components is modified by considering the effects of the created quark pair's energy, as well as the separation between the created quark pair and the valence quark pair. All the wave functions needed including the mesons and the relative motion between two mesons are all obtained by solving the corresponding Schrödinger equation with the help of the Gaussian expansion method. Our aim of the present work is to find a new set of parameters which can give a good description of the mass spectrum of the low-lying light quarkonium and charmonium states. Moreover, some exotic states, for example $X(3872)$ can be described well in the unquenched quark model.

    hep-phCPC(2024)·7 citations
27. 27*

    Understanding the nature of the $\Delta (1600)$ resonance

    Liam Hockley🇦🇺 · Curtis Abell🇦🇺 · Derek Leinweber🇦🇺 · Anthony Thomas🇦🇺

    We present a coupled-channel analysis of the $J^P=3/2^{+}\Delta$-baryon spectrum, based in the framework of Hamiltonian Effective Field Theory (HEFT). We construct a Hamiltonian which mixes quark model-like single-particle states and two-particle meson-baryon channels, and constrain this via experimentally measured $\pi N\to \pi N$ scattering observables. In the same vein as Lüscher's approach, we then connect this infinite-volume inspired Hamiltonian with finite-volume lattice QCD results. Drawing on lattice correlation-matrix eigenvectors identifying the $1s$ and $2s$ states in the finite-volume $\Delta (3/2^{+})$ spectrum, and utilising the HEFT eigenvectors describing the composition of the energy eigenstates, we resolve the structure of these states and their relation to the $\Delta (1600)$ resonance. We find the dominant contributions to this resonance come from strong rescattering in the $\pi N$ and $\pi \Delta$ channels. This contrasts the long-held view of a dominant quark model-like core for the $\Delta (1600)$. Further discussion of other contemporary lattice results for the $\Delta$ spectrum and $\pi N$ scattering states is also presented.

    hep-phhep-latnucl-thPRD(2025)·13 citations
28. 28*

    Neutrino observables in gauged $U(1{)}_{L_{\alpha }-L_{\beta }}$ models with two Higgs doublet and one singlet scalars

    Yuanchao Lou🇨🇳 · Takaaki Nomura🇨🇳

    We discuss neutrino sector in models with two Higgs doublet and one singlet scalar fields under local $U(1{)}_{L_{\alpha }-L_{\beta }}$ symmetry. A neutrino mass matrix is formulated for these models where the matrix is generated via type-I seesaw mechanism introducing right-handed neutrinos. The neutrino mass matrix has more degrees of freedom compared to minimal scenarios which have only one new scalar field, but its structure is still restricted by the symmetry. Then it is find that sum of neutrino mass can be lower than minimal scenarios and it is easier to satisfy observed constraints. In addition, we can fit neutrino data for $U(1{)}_{L_e-L_{\mu (\tau )}}$ cases which are disfavored in minimal models. Furthermore, some correlations among sum of neutrino mass and CP violating phases are still found although we have more free parameters.

    hep-phhep-exCPC(2025)·4 citations
29. 29*

    Transition from the shadow to reflective scattering

    S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

    We consider transition from shadow to relective scattering mode and behavior of the amplitude and cross--sections of hadron interactions in the both modes.

    hep-phPLB(2024)·3 citations
30. 30*

    Mapping the sources of CP violation in neutrino oscillations from the seesaw mechanism

    Zhi-zhong Xing🇨🇳

    We present the first complete calculation of the Jarlskog invariant, a working measure of the strength of CP violation in the flavor oscillations of three light neutrino species, with the help of a full Euler-like block parametrization of the flavor structure in the canonical seesaw mechanism. We find that this invariant depends on 240 linear combinations of the 6 original phase parameters that are responsible for CP violation in the decays of three heavy Majorana neutrinos in 27 linear combinations as a whole, and thus provides the first model-independent connection between the microscopic and macroscopic matter-antimatter asymmetries.

    hep-phhep-exhep-thPLB(2024)·11 citations
31. 31*

    The Covariant Approach for the Radiative Decay of the J/{\Psi} Meson and Relation to Amplitudes Extracted in the Helicity Basis

    A. V. Anisovich🇷🇺 · K. V. Nikonov🇷🇺 · A. V. Sarantsev🇷🇺

    We have developed the covariant approach for the partial wave analysis of the radiative decay of the vector meson into two pseudoscalar mesons based on the orbital momentum- intrinsic spin decomposition. This allowed us to include the data on the radiative J/{\Psi} decay into a large data base for analysis of the meson production reactions. The correspondence between partial wave amplitudes extracted in our approach and those extracted in the helicity basis is determined.

    hep-phPhys.Atom.Nucl.(2024)·2 citations
32. 32*

    Parton distribution functions and fragmentation functions of spin-1 hadrons

    S. Kumano🇯🇵

    Structure functions of the spin-1 deuteron will be investigated experimentally from the late 2020's at various facilities such as Thomas Jefferson National Accelerator Facility, Fermi National Accelerator Laboratory, nuclotron-based ion collider facility, and electron-ion colliders. We expect that a new high-energy spin-physics field could be created by these projects. In this paper, the current theoretical status is explained for the structure functions of spin-1 hadrons, especially on parton distribution functions, transverse-momentum dependent parton distributions, and fragmentation functions. Related multiparton distribution functions are also shown.

    hep-phhep-exhep-latnucl-ex+1EPJA(2024)·12 citations
33. 33*

    Theoretical study of $N(1535)$ and ${\Sigma }^{\ast }(1/2^{-})$ in the Cabibbo-favored process ${\Lambda }_c^{+}\to p{\bar{K}}^0\eta$

    Ying Li🇨🇳 · Si-Wei Liu🇨🇳 · En Wang🇨🇳 · De-Min Li🇨🇳 · Li-Sheng Geng🇨🇳 · Ju-Jun Xie🇨🇳

    Motivated by the recent experimental measurements, we have investigated the Cabibbo-favored process ${\Lambda }_c^{+}\to p{\bar{K}}^0\eta$, where the $N(1535)$ resonance is dynamically generated from the $S$-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach. The contributions from the intermediate $N(1650)$ and the predicted low-lying baryon ${\Sigma }^{\ast }(1/2^{-})$ are also considered. In addition, a Breit-Wigner amplitude for the $N(1535)$ resonance is checked. By comparing with the measured $\eta p$, ${\bar{K}}^0\eta$, and $p{\bar{K}}^0$ invariant mass squared distributions, our results support the interpretation of $N(1535)$ as a dynamically generated state. Furthermore, we demonstrate that, with the contribution from ${\Sigma }^{\ast }(1/2^{-})$ taken into account, the calculated invariant mass spectrum agrees with the Belle measurements. Future precise measurements of the ${\Lambda }_c^{+}\to p{\bar{K}}^0\eta$ process can further elucidate the existence of the low-lying baryon ${\Sigma }^{\ast }(1/2^{-})$.

    hep-phPRD(2024)·29 citations
34. 34*

    Probing flavored regimes of leptogenesis with gravitational waves from cosmic strings

    Marco Chianese🇮🇹 · Satyabrata Datta🇨🇳 · Gennaro Miele🇮🇹 · Rome Samanta🇮🇹 · Ninetta Saviano🇮🇹

    Cosmic strings radiate detectable gravitational waves in models featuring high-scale symmetry breaking, e.g., high-scale leptogenesis. In this Letter, for the first time, we show that different flavored regimes of high-scale leptogenesis can be tested with the spectral features in cosmic string-radiated gravitational waves. This is possible if the scalar field that makes right-handed neutrinos massive is feebly coupled to the Standard Model Higgs. Each flavored regime, sensitive to low-energy neutrino experiments, leaves a marked imprint on the gravitational waves spectrum. A three-flavor and a two-flavor regime could be probed by a characteristic fall-off of the gravitational wave spectrum at the LISA-DECIGO-ET frequency bands with preceding scale-invariant amplitudes bounded from above and below. We present Gravitational Waves windows for Flavored Regimes of Leptogenesis (GWFRL) testable in the upcoming experiments. We also provide the first construction of a leptogenesis framework where a testable distinction of flavor regimes is possible without constraining the flavor structure of the theory.

    hep-phastro-ph.COhep-thPRD(2025)·17 citations
35. 35*

    Spontaneous CP violation in Supersymmetric QCD

    Shota Nakagawa🇨🇳 · Yuichiro Nakai🇨🇳 · Yaoduo Wang🇨🇳

    We investigate a composite model of spontaneous CP violation based on a new supersymmetric QCD as a solution to the strong CP problem. The scalar components of the meson chiral superfields obtain complex vacuum expectation values to break CP symmetry spontaneously. Then, wavefunction renormalization for the quark kinetic terms provides the Cabibbo-Kobayashi-Maskawa (CKM) phase, while the strong CP phase $\bar{\theta }$ is protected by nonrenormalization of the superpotential and hermiticity of the wavefunction renormalization factor. In our model, the right-handed down-type quark multiplets are given by composite states, enhancing their couplings to CP breaking fields, which is essential to realize the observed CKM phase. The non-perturbative dynamics generates the scale of spontaneous CP violation hierarchically lower than the Planck scale. We discuss potential corrections to $\bar{\theta }$ and find a viable parameter space of the model to solve the strong CP problem without fine-tuning.

    hep-phhep-thJHEP(2024)·11 citations
36. 36*

    On the role of $J/\psi$ production in electron-ion collisions

    Zexuan Chu🇨🇳 · Jinhui Chen🇨🇳 · Xiang-Peng Wang🇩🇪 · Hongxi Xing🇨🇳

    Within the framework of non-relativistic QCD (NRQCD) effective field theory, we study the leptoproduction of $J/\psi$ at next-to-leading order in perturbative QCD for both unpolarized and polarized electron-ion collisions. We demonstrate that the $J/\psi$-tagged deep inelastic scattering in the future Electron-Ion Collider can be served as a golden channel for the reasons including constraining NRQCD long distance matrix elements, probing the nuclear gluon distribution functions, as well as investigating the gluon helicity distribution inside a longitudinal polarized proton.

    hep-phnucl-thPRD(2025)·4 citations
37. 37*

    Relic neutrino decay: a solution to the excess radio background

    Rishav Roshan🇬🇧

    The detection of excess radio background detected by ARCADE 2 suggests the presence of new physics as there exists no clear astrophysical solution. We find that the radiative decay of a relic neutrino into a sterile neutrino, assumed to be quasi-degenerate, provides a very good fit to ARCADE 2 data. The solution also predicts a stronger 21 cm absorption global signal than the predicted one from the $\Lambda$CDM model, with a contrast brightness temperature. The solution obtained is in mild tension with a much stronger signal claimed by the EDGES collaboration.

    hep-phastro-ph.CO0 citations
38. 38*

    The hydrodynamics of inverse phase transitions

    Giulio Barni🇮🇹 · Simone Blasi🇩🇪 · Miguel Vanvlasselaer🇧🇪

    First order phase transitions are violent phenomena that occur when the state of the universe evolves abruptly from one vacuum to another. A \emph{direct} phase transition connects a local vacuum to a deeper vacuum of the zero--temperature potential, and the energy difference between the two minima manifests itself in the acceleration of the bubble wall. In this sense, the transition is triggered by the release of vacuum energy. On the other hand, an \emph{inverse} phase transition connects a deeper minimum of the zero--temperature potential to a higher one, and the bubble actually expands against the vacuum energy. The transition is then triggered purely by thermal corrections. We study for the first time the hydrodynamics and the energy budget of inverse phase transitions. We find several modes of expansion for inverse bubbles, which are related to the known ones for direct transitions by a mirror symmetry. We finally investigate the friction exerted on the bubble wall and comment on the possibility of runaway walls in inverse phase transitions.

    hep-phastro-ph.COhep-thJCAP(2024)·33 citations
39. 39*

    On the extension of the SM through a scalar quadruplet

    Darius Jurčiukonis🇱🇹 · Luís Lavoura🇵🇹

    We consider the extension of the Standard Model (SM) through a scalar quadruplet with hypercharge either $1/2$ or $3/2$; in the first case, we assume $CP$ invariance of the scalar potential (SP). We write down the unitarity conditions on the SP. We use a partly numerical method to find the bounded-from-below conditions on the SP. We determine the masses of the new scalars of the model. We compute the three- and four-Higgs couplings and compare them to the ones of the SM.

    hep-ph7 citations
40. 40*

    A generalized statistical model for fits to parton distributions

    Mengshi Yan🇨🇳 · Tie-Jiun Hou🇨🇳 · Zhao Li🇨🇳 · Kirtimaan Mohan🇺🇸 · C.-P. Yuan🇺🇸

    Parton distribution functions (PDFs) form an essential part of particle physics calculations. Currently, the most precise predictions for these non-perturbative functions are generated through fits to global data. A problem that several PDF fitting groups encounter is the presence of tension in data sets that appear to pull the fits in different directions. In other words, the best fit depends on the choice of data set. Several methods to capture the uncertainty in PDFs in presence of seemingly inconsistent fits have been proposed and are currently in use. These methods are important to ensure that uncertainty in PDFs are not underestimated. Here we propose a novel method for estimating the uncertainty by introducing a generalized statistical model based on Bayesian Hierarchical models which is implemented via the Gaussian Mixture Model (GMM). The methodology is inspired by unsupervised machine learning techniques and is closely related to the statistical methods of Ensemble learning and Bayesian model averaging. Using a toy model of PDFs, we demonstrate how the GMM can be used to faithfully reconstruct the likelihood associated with PDF fits, which can in turn be used to accurately determine the uncertainty on PDFs, especially in the presence of tension in the fitted data sets. We further show how this statistical model reduces to the usual chi-squared likelihood function for a consistent data set and provide measures to optimize the number of Gaussians in the GMM.

    hep-phhep-exhep-thPRD(2025)·10 citations
41. 41*

    Searching for heavy millicharged particles from the atmosphere

    Han Wu🇨🇦 · Edward Hardy🇬🇧 · Ningqiang Song🇨🇳

    If millicharged particles (MCPs) exist they can be created in the atmosphere when high energy cosmic rays collide with nuclei and could subsequently be detected at neutrino experiments. We extend previous work, which considered MCPs from decays of light mesons and proton bremsstrahlung, by including production from ${\rm Y}$ meson decays and the Drell-Yan process. MCPs with masses below a GeV primarily arise from proton bremsstrahlung, while heavier MCPs predominantly originate from heavy meson decays and Drell-Yan. We analyse the resulting single scatter and multiple scatter signals at SuperK and JUNO. Searches for low energy coincident signals at JUNO will be sensitive to MCPs with milli-charges up to an order of magnitude beyond current constraints for MCP masses between 2 GeV and 10 GeV.

    hep-phastro-ph.COhep-exPRD(2024)·22 citations
42. 42*

    Measurement of CKM element $|V_{cb}|$ from $W$ boson decays at the future Higgs factories

    Hao Liang🇨🇳 · Lingfeng Li🇺🇸 · Yongfeng Zhu🇨🇳 · Xiaoyan Shen🇨🇳 · Manqi Ruan🇨🇳

    This study investigates the precision measurement of the CKM matrix element $|V_{cb}|$ through semileptonic $WW$ events at future Higgs factories, $i.e.$, FCC-ee, ILC, C${}^3$, and CEPC. We use full detector simulation to generate the $WW\to \ell \nu cb$ signal events and various backgrounds at $\sqrt{s}=240$ GeV with unpolarized beams. The relative statistical uncertainties are projected to be 0.91\% for the muon channel and 1.2\% for the electron channel, assuming a baseline integrated luminosity of 5 ab${}^{-1}$. The sensitivities at other Higgs factory scenarios are also projected. Possible contributors to systematic uncertainties are discussed, with the most prominent one being the systematics of flavor-tagging and mistagging rates. Combining with $WW$ threshold runs, the relative systematic uncertainty can be further reduced.

    hep-phhep-exJHEP(2024)·15 citations
43. 43*

    New insights into axion freeze-in

    Mudit Jain🇬🇧 · Angelo Maggi🇬🇧 · Wen-Yuan Ai🇬🇧 · David J.E. Marsh🇬🇧

    Freeze-in via the axion-photon coupling, $g_{\varphi \gamma }$, can produce axions in the early Universe. At low reheating temperatures close to the minimum allowed value $T_{\mathrm{reh}}\approx T_{\mathrm{BBN}}\approx 10\mathrm{MeV}$, the abundance peaks for axion masses $m_{\varphi }\approx T_{\mathrm{reh}}$. Such heavy axions are unstable and subsequently decay, leading to strong constraints on $g_{\varphi \gamma }$ from astrophysics and cosmology. In this work, we revisit the computation of the freeze-in abundance and clarify important issues. We begin with a complete computation of the collision terms for the Primakoff process, electron-positron annihilation, and photon-to-axion (inverse-)decay, while approximately taking into account plasma screening and threshold effects. We then solve the Boltzmann equation for the full axion distribution function. We confirm previous results about the importance of both processes to the effective "relic abundance" (defined as density prior to decay), and provide useful fitting formulae to estimate the freeze-in abundance from the equilibrium interaction rate. For the distribution function, we find an out-of-equilibrium population of axions and introduce an effective temperature for them. We follow the evolution right up until decay, and find that the average axion kinetic energy is larger than a thermal relic by between 20\% and 80\%, which may have implications for limits on decaying axions from X-ray spectra. We extend our study to a two-axion system with quartic cross-coupling, and find that for typical/expected couplings, freeze-in of a second axion flavour by annihilations leads to a negligibly small contribution to the relic density.

    hep-phastro-ph.COhep-thJHEP(2024)·13 citations
44. 44*

    Effects of Neutrino-Ultralight Dark Matter Interaction on the Cosmic Neutrino Background

    Pablo Martínez-Miravé🇩🇰 · Yuber F. Perez-Gonzalez🇬🇧 · Manibrata Sen🇩🇪

    Ultralight dark matter interacting with sterile neutrinos would modify the evolution and properties of the cosmic neutrino background through active-sterile neutrino mixing. We investigate how such an interaction would induce a redshift dependence in neutrino masses. We highlight that cosmological constraints on the sum of neutrino masses would require reinterpretation due to the effective mass generated by neutrino-dark matter interactions. Furthermore, we present an example where such interactions can alter the mass ordering of neutrinos in the early Universe, compared to what we expect today. We also address the expected changes in the event rates in a PTOLEMY-like experiment, which aims to detect the cosmic neutrino background via neutrino capture, and discuss projected constraints.

    hep-phastro-ph.COhep-exPRD(2024)·16 citations
45. 45*

    Color Glass Condensate meets High Twist Expansion

    Yu Fu🇺🇸 · Zhong-Bo Kang🇺🇸 · Farid Salazar🇺🇸 · Xin-Nian Wang🇨🇳 · Hongxi Xing🇨🇳

    We establish the correspondence between two well-known frameworks for QCD multiple scattering in nuclear media: the Color Glass Condensate (CGC) and the High-Twist (HT) expansion formalism. We argue that a consistent matching between both frameworks, in their common domain of validity, is achieved by incorporating the sub-eikonal longitudinal momentum phase in the CGC formalism, which mediates the transition between coherent and incoherent scattering. We perform a detailed calculation and analysis of direct photon production in proton-nucleus scattering as a concrete example to establish the matching between HT and CGC up to twist-4, including initial- and final-state interactions, as well as their interferences. The techniques developed in this work can be adapted to other processes in electron-nucleus and proton-nucleus collisions, and they provide a potential avenue for a unified picture of dilute-dense dynamics in nuclear media.

    hep-phnucl-thPRD(2025)·13 citations
46. 46*

    Solving the strong CP problem without axions

    Ferruccio Feruglio🇮🇹 · Matteo Parriciatu🇮🇹 · Alessandro Strumia🇮🇹 · Arsenii Titov🇮🇹

    We formulate general conditions under which the strong CP problem is solved by spontaneous CP violation. Quark-mass matrix elements are polynomials in the CP-breaking order parameters, engineered such that their determinant is a real constant. This scheme permits only a limited number of textures. These conditions can be realized in supersymmetric theories with CP as an anomaly-free local flavour symmetry, suggesting a unified solution to the strong CP problem and the flavour puzzle. Our solution can be implemented using either modular invariance or a local U(1) symmetry. We present modular-invariant realizations where matter fields are assigned small modular weights $\pm 2$ ($\pm 1$), utilising higher levels $N=2$ ($N=3$). Heavy quarks are in general not required, but their presence allows for models where colored particles fill non-singlet representations of the flavour group.

    hep-phhep-thJHEP(2024)·42 citations
47. 47*

    Solar chameleons: Novel channels

    Tomás O'Shea🇪🇸 · Anne-Christine Davis🇬🇧 · Maurizio Giannotti🇪🇸 · Sunny Vagnozzi🇮🇹 · Luca Visinelli🇨🇳 · Julia K. Vogel🇪🇸

    We revisit the flux of chameleons (light scalar particles which could play a role in the dark energy phenomenon) produced in the interior of the Sun. Our novel analysis incorporates various important details and new processes that have previously been overlooked, including the impact of the bulk magnetic field profile, as well as Primakoff production of chameleons in the electric fields of electrons and ions. In this paper we consider only the contributions of transverse photons. The production of chameleons from longitudinal electromagnetic excitations will be presented in a dedicated follow-up work. Demanding that the total flux of chameleons does not exceed 3% of the solar luminosity leads to the stringent upper limit on the chameleon-photon conformal coupling ${\beta }_{\gamma }\lesssim 10^{10}$, assuming that the height of the chameleon potential is set to the dark energy scale $\Lambda =2.4$ meV, and independently of other couplings to matter. Although this bound is tighter than current upper limits on ${\beta }_{\gamma }$ from the CAST helioscope, these limits will have to be reassessed in terms of the updated solar chameleon flux we have computed. We argue that solar chameleons, potentially detectable in next-generation helioscopes such as IAXO, can be used to probe a region of chameleon parameter space that has yet to be covered.

    hep-phastro-ph.HEastro-ph.SRgr-qcPRD(2024)·18 citations
48. 48*

    Neutrino Anarchy from Flavor Deconstruction

    Admir Greljo🇨🇭 · Gino Isidori🇨🇭

    Flavor deconstruction refers to non-universal gauge extensions where the original gauge symmetry is deconstructed into separate copies, one for each family. A hierarchical chain of symmetry breaking provides an attractive low-scale solution to the flavor puzzle, consistent with flavor-changing neutral currents and finite naturalness. Although successful in explaining the origin of flavor hierarchies in the quark and charged lepton sectors, existing models have struggled with the large and seemingly anarchic mixing observed in neutrino oscillations. This letter identifies conditions under which neutrino anarchy may arise from flavor deconstruction in generic models with right-handed neutrinos. When deconstruction is applied to carefully chosen subgroups of the extended gauge symmetry, hierarchies in the seesaw formula cancel out.

    hep-phhep-exhep-thPLB(2024)·18 citations
49. 49*

    Exploring doubly-heavy tetraquarks in constituent-quark-model based meson-meson coupled-channels approach

    P. G. Ortega🇪🇸 · D. R. Entem🇪🇸 · F. Fernandez🇪🇸 · J. Segovia🇪🇸

    The LHCb Collaboration announced in 2021 the discovery of a new tetraquark-like state, named $T_{cc}^{+}$, with minimum quark content $cc\bar{u}\bar{d}$, close to the $D^0{D}^{\ast +}$ threshold. This has motivated countless theoretical works trying to identify the dynamics which is responsible of the formation of such state; in particular, the one performed by us in Ref. \cite{Ortega:2022efc}, where a $D^0{D}^{\ast +}$ molecular candidate whose mass, width, scattering length and effective ranges are in reasonable agreement with experimental measurements. We explore herein the possibility of having $T_{cc}^{+}$ partners in all doubly-heavy tetraquark sectors, considering doubly represented light antiquarks $u$, $d$ or $s$, and taking into account all possible spin-parity quantum numbers. The computation is done using a constituent-quark-model based meson-meson coupled-channels framework which has been tested many times in the last fifteen years describing conventional heavy mesons and baryons, their coupling with hadron-hadron thresholds but also in exploring its application to compact multiquark structures. The advantage of using an approach with such a relatively large history is that it allows us to make predictions because all the parameters have already been constrained from our previous works. Then, from this perspective, we present a parameter-free model-dependent prediction of doubly-heavy tetraquarks that may be partners of the discovered $T_{cc}^{+}$ state.

    hep-phhep-exhep-latnucl-ex+1PRD(2024)·5 citations
50. 50*

    Timing-based mass measurement of exotic long-lived particles at the FCC-ee

    Roy Aleksan🇫🇷 · Emmanuel Perez🇨🇭 · Giacomo Polesello🇮🇹 · Nicolò Valle🇮🇹

    The very high luminosity run foreseen at the $Z$-pole for the FCC-ee will allow the detection in $Z$ decays of new particles with very low couplings to the Standard Model. These particles can have measurable flight paths before they decay. If the timing and the position of the decay vertex can be measured with high precision, the mass of such particles can be measured by exploiting the constrained kinematics of an $e^{+}{e}^{-}$ collider. The mass resolution achievable with this technique is studied through a detailed analysis in the framework of a parametrised simulation of the performance of the IDEA detector. The adopted benchmark model is the production of Heavy Neutral Leptons, which is one of the key channels for new physics discovery at the FCC-ee.

    hep-phhep-exEPJC(2025)·8 citations
51. 51*

    Observational test for $f(Q)$ gravity with weak gravitational lensing

    Qingqing Wang🇨🇳 · Xin Ren🇨🇳 · Yi-Fu Cai🇨🇳 · Wentao Luo🇨🇳 · Emmanuel N. Saridakis🇬🇷

    In this article we confront a class of $f(Q)$ gravity models with observational data of galaxy-galaxy lensing. Specifically, we consider the $f(Q)$ gravity models containing a small quadratic correction when compared with General Relativity (GR), and quantify this correction by a model parameter $\alpha$. To derive the observational constraints, we start by extracting the spherically symmetric solutions which correspond to the deviations from the Schwarzschild solution that depends on the model parameter in a two-fold way, i.e., a renormalized mass and a new term proportional to $r^{-2}$. Then, we calculate the effective lensing potential, the deflection angle, the shear component, and the effective Excess Surface Density (ESD) profile. After that, we employ the group catalog and shape catalog from the SDSS DR7 for the lens and source samples respectively. Moreover, we handle the off-center radius as a free parameter and constrain it using the MCMC. Concerning the deviation parameter from GR we derive $\alpha =1.202_{-0.179}^{+0.277}\times 10^{-6}{\mathrm{Mpc}}^{-2}$ at 1 $\sigma$ confidence level, and then compare the fitting efficiency with the standard $\Lambda$CDM paradigm by applying the AIC and BIC information criteria. Our results indicate that the $f(Q)$ corrections alongside off-center effects yield a scenario that is slightly favored.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1ApJ(2024)·30 citations
52. 52*

    Reassessing constant-roll Warm Inflation

    Sandip Biswas🇮🇳 · Kaushik Bhattacharya🇮🇳 · Suratna Das🇮🇳

    Departing from standard slow-roll conditions is one way of putting the inflationary paradigm to test, and constraining the dynamics of the inflaton field with a constant-rate of roll of the inflaton field, a.k.a. the constant-roll scenario, is one way of exploring such deviation from the standard slow-roll dynamics. In this manuscript we explore such a possibility in a variant inflationary scenario, known as Warm Inflation. We construct and derive the conditions for having constant-roll WI models where inflation lasts at least for 60 $e-$folds, gracefully exits the constant-roll inflation phase, and maintains near thermal equilibrium of the system which is an essential feature of WI in the slow-roll regime. We show that while certain models of WI (the ones with dissipative coefficient as a function of temperature alone) can accommodate constant-roll dynamics, others (with dissipative coefficient as a function of temperature and the inflaton field both) fail to maintain thermal equilibrium once the constant-roll condition is imposed and hence cannot produce a constant-roll WI phase.

    ↳ astro-ph.COgr-qchep-phPRD(2024)·6 citations
53. 53*

    Muon neutrinos and the cosmological abundance of primordial black holes

    Jiali Hao🇨🇳 · Yupeng Yang🇨🇳 · Qianyong Li🇨🇳 · Yankun Qu🇨🇳 · Shuangxi Yi🇨🇳

    In the mixed dark matter scenarios consisting of primordial black holes (PBHs) and particle dark matter (DM), PBHs can accrete surrounding DM particles to form ultracompact minihalos (UCMHs or clothed PBHs) even at an early epoch of the Universe. The distribution of DM particles in a UCMH follows a steeper density profile compared with a classical DM halo. It is expected that the DM annihilation rate is very large in UCMHs, resulting in a contribution to, e.g., the extragalactic neutrino flux. In this work, we investigate the extragalactic neutrino flux from clothed PBHs due to DM annihilation, and then the muon flux for neutrino detection. Compared with the atmospheric neutrino flux, we derive the upper limits on the cosmological abundance of PBHs for 10 years of exposure time of, e.g., the IceCube experiment. Compared with other constraints, although the upper limits obtained by us are not the strongest, it is a different way to study the cosmological abundance of PBHs.

    ↳ astro-ph.COhep-phPRD(2024)·4 citations
54. 54*

    Green's functions in the presence of a bubble wall

    Takahiro Kubota🇯🇵

    Field theoretical tools are developed so that one can analyze quantum phenomena such as transition radiation that must have occurred during the Higgs condensate bubble expansion through plasma in the early universe. Integral representations of Bosonic and Fermionic propagators are presented for the case that particle masses are varied continuously during the passage through the bubble wall interface between symmetry-restored and symmetry-broken regions. The construction of propagators is based on the so-called eigenfunction expansion method associated with self-adjoint differential operators, developed by Weyl, Stone, Titchmarsh, Kodaira and several others. A novel method of field quantization in the presence of the bubble wall is proposed by using the spectral functions introduced in constructing the two-point Green's functions.

    ↳ hep-thhep-phJHEP(2024)·6 citations
55. 55*

    Discrete $Z_4$ symmetry in quantum gravity

    G.E. Volovik🇫🇮

    We consider the discrete $Z_4$ symmetry $\hat{\mathbf{i}}$, which takes place in the scenario of quantum gravity where the gravitational tetrads emerge as the order parameter. Under this symmetry operation $\hat{\mathbf{i}}$, the emerging tetrads are multiplied by the imaginary unit, $\hat{\mathbf{i}}{e}_{\mu }^a=-i{e}_{\mu }^a$. The existence of such symmetry and the spontaneous breaking of this symmetry are also supported by the consideration of the symmetry breaking scheme in the topological superfluid ${}^3$He-B. The order parameter ${}^3$He-B is the analogue of the tetrad field, but it has complex values. The $\hat{\mathbf{i}}$-symmetry operation changes the phase of the complex order parameter by $\pi /2$, which corresponds to the $Z_4$ discrete symmetry in quantum gravity. We also considered the alternative scenario of the breaking of this $Z_4$ symmetry, in which the $\hat{\mathbf{i}}$-operation changes sign of the scalar curvature, $\hat{\mathbf{i}}\mathcal{R}=-\mathcal{R}$, and thus the Einstein-Hilbert action violates the $\hat{\mathbf{i}}$-symmetry. In the alternative scenario of symmetry breaking, the gravitational coupling $K=1/16\pi G$ plays the role of the order parameter, which changes sign under $\hat{\mathbf{i}}$-transformation.

    ↳ cond-mat.othergr-qchep-phSymmetry(2024)·3 citations
56. 56*

    Quark orbital angular momentum in the proton from a twist-3 generalized parton distribution

    M. Engelhardt🇺🇸 · N. Hasan🇩🇪 · S. Krieg🇩🇪 · S. Liuti🇺🇸 · S. Meinel🇺🇸 · J. Negele🇺🇸 · A. Pochinsky🇺🇸 · M. Rodekamp🇩🇪 · S. Syritsyn🇺🇸

    Quark orbital angular momentum in the proton is evaluated via a Lattice QCD calculation of the second Mellin moment of the twist-3 generalized parton distribution ${\tilde{E}}_{2T}$ in the forward limit. The connection between this approach to quark orbital angular momentum and approaches previously utilized in Lattice QCD calculations, via generalized transverse momentum-dependent parton distributions and via Ji's sum rule, is reviewed. This connection can be given in terms of Lorentz invariance and equation of motion relations. The calculation of the second Mellin moment of ${\tilde{E}}_{2T}$ proceeds via a finite-momentum proton matrix element of a quark bilocal operator with a straight-line gauge connection and separation in both the longitudinal and transverse directions. The dependence on the former component serves to extract the second Mellin moment, whereas the dependence on the latter component provides a transverse momentum cutoff for the matrix element. Furthermore, a derivative of the matrix element with respect to momentum transfer in the forward limit is required, which is obtained using a direct derivative method. The calculation utilizes a clover fermion ensemble at pion mass 317 MeV. The resulting quark orbital angular momentum is consistent with previous evaluations through alternative approaches, albeit with greater statistical uncertainty using a comparable number of samples.

    ↳ hep-lathep-phPoS(2024)·1 citation
57. 57*

    Quantum simulations of quantum electrodynamics in Coulomb gauge

    Tianyin Li🇨🇳

    In recent years, the quantum computing method has been used to address the sign problem in traditional Monte Carlo lattice gauge theory (LGT) simulations. We propose that the Coulomb gauge (CG) should be used in quantum simulations of LGT. This is because the redundant degrees of freedom can be eliminated in CG. Therefore, the Hamiltonian in CG does not need to be gauge invariance, allowing the gauge field to be discretized naively. We point out that discretized gauge fields and fermion fields should be placed on momentum and position lattices, respectively. Under this scheme, the CG condition and Gauss's law can be conveniently preserved by solving algebraic equations of polarization vectors. We also discuss the procedure for mapping gauge fields to qubits, and then demonstrate the polynomial scaling of qubits and the complexity of time evolution. Finally, we calculate the vacuum expectation value (VEV) of the U(1) plaquette operator and the Wilson loop on a classical device to test the performance of our discretization scheme.

    ↳ hep-lathep-phquant-phPRD(2025)·7 citations
58. 58*

    Reexamination of antinucleon-nucleon interactions in covariant chiral effective field theory

    Yang Xiao🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳

    Motivated by the recent progress in developing high-precision relativistic chiral nucleon-nucleon interactions, we study the antinucleon-nucleon interaction in a hybrid approach where the real part of the potential is constructed in the leading-order covariant chiral effective field theory, and the imaginary part is described following the procedure adopted in the heavy baryon chiral effective field theory. The phase shifts and inelasticities with $J\le 1$ are obtained and compared to those calculated in the next-to-leading order heavy baryon chiral effective field theory. For most partial waves, the descriptions of phase shifts and inelasticities in the hybrid approach are comparable to those in the next-to-leading order heavy baryon chiral effective field theory, confirming the relatively faster convergence of the relativistic approach observed in the nucleon-nucleon sector. In addition, we search for bound states/resonances near the $\bar{N}N$ threshold and find several structures that can be associated with those states recently observed by the BESIII Collaboration.

    ↳ nucl-thhep-phPRC(2024)·8 citations
59. 59*

    Constraints on the Axion-Photon Coupling Using Stellar Modelling

    David Fordham🇵🇹 · Ilídio Lopes🇵🇹

    Asteroseismology has been shown to be, together with stellar modelling, an invaluable tool in constraining properties of novel physics. In this work, we study for the first time the influence of axionic production in the evolution of a late main-sequence star, comparing computational models with observational data in order to constrain the axion-photon $g_{a\gamma }$ coupling parameter. We first perform a high-precision calibration of a stellar model to our target star, in order to obtain a benchmark for our other diagnostics. We then apply a two-stage test, first using global quantities and then resorting to precision seismic ratios. We find that seismology allows us to place an independent upper bound of $g_{a\gamma }\le 0.98\times 10^{-10}$ GeV${}^{-1}$ at a $68\%$ confidence level (CL), in the same order of magnitude as both the most recent constraints from the observation of globular clusters and previous bounds obtained through stellar modelling, but more stringent than most current direct axion detections. We also suggest a more conservative limit of $g_{a\gamma }\le 1.38\times 10^{-10}$ GeV${}^{-1}$ at a $95\%$ CL. Moreover, this new diagnostic method can be applied to stellar data that will be obtained in future asteroseismic projects.

    ↳ astro-ph.SRastro-ph.HEhep-phPRD(2024)·0 citations
60. 60*

    Review of the measurements of the strong coupling constant in CMS at 13 TeV. Contribution to the 2024 QCD session of the 58th Rencontres de Moriond

    Andris Potrebko🇱🇻

    The strong coupling constant is the least known of the coupling constants in the standard model. Nevertheless it appears in the calculations of cross sections of all the processes at the LHC. We present a review of the strong coupling constant measurements conducted at the CMS experiment, focusing on those performed at a center-of-mass of 13 TeV.

    ↳ hep-exhep-ph1 citation
61. 61*

    A Matrix Model Proposal for Quantum Gravity and the Quantum Mechanics of Black Holes

    Chong-Sun Chu🇹🇼

    We propose a quantum mechanical theory of quantum spaces described by large $N$ noncommutative geometry as a model for quantum gravity. The model admits fuzzy sphere as static solution. Over the fuzzy geometry, the quantum mechanics of the fermions is given by a sum of oscillators with equal frequency. The energy state where exactly half of the Fermi sea is filled contains the maximal amount of degeneracy. This state of the fuzzy sphere obeys the mass-radius relation of a Schwarzschild black hole if the fuzzy sphere is identified with the black hole horizon. Moreover the set of states in the Fermi sea gives precisely the Bekenstein-Hawking entropy. We thus propose that quantum black holes are described by fuzzy spheres with a half-filled Fermi sea in our model. We also consider a system of two fuzzy spheres by embedding them as blocks in the matrix quantum mechanics. When the distance $r$ between the two fuzzy spheres is small, the total energy of the system can be computed using perturbation theory. We show that in the leading order of large $N$ limit, the interaction energy depends on $-G{M}_1{M}_2$ exactly the manner as in Newton gravity. To reproduce the correct $r$ dependence in the long range, we expect the inclusion of large $N$ corrections and quantum effects will be needed.

    ↳ hep-thgr-qchep-phPRD(2025)·11 citations
62. 62*

    Towards Universal Unfolding of Detector Effects in High-Energy Physics using Denoising Diffusion Probabilistic Models

    Camila Pazos🇺🇸 · Shuchin Aeron🇺🇸 · Pierre-Hugues Beauchemin🇺🇸 · Vincent Croft🇳🇱 · Zhengyan Huan🇺🇸 · Martin Klassen🇺🇸 · Taritree Wongjirad🇺🇸

    Correcting for detector effects in experimental data, particularly through unfolding, is critical for enabling precision measurements in high-energy physics. However, traditional unfolding methods face challenges in scalability, flexibility, and dependence on simulations. We introduce a novel approach to multidimensional object-wise unfolding using conditional Denoising Diffusion Probabilistic Models (cDDPM). Our method utilizes the cDDPM for a non-iterative, flexible posterior sampling approach, incorporating distribution moments as conditioning information, which exhibits a strong inductive bias that allows it to generalize to unseen physics processes without explicitly assuming the underlying distribution. Our results highlight the potential of this method as a step towards a "universal" unfolding tool that reduces dependence on truth-level assumptions, while enabling the unfolding of a wide range of measured distributions with improved adaptability and accuracy.

    ↳ physics.data-anhep-exhep-phSciPost Phys.Core(2025)·10 citations
63. 63*

    Weyl Fermion Creation by Cosmological Gravitational Wave Background at 1-loop

    Azadeh Maleknejad🇬🇧 · Joachim Kopp🇨🇭

    Weyl fermions of spin $\frac{1}{2}$ minimally coupled to Einstein's gravity in 4 dimensions cannot be produced purely gravitationally in an expanding Universe at tree level. Surprisingly, as we showed in a recent letter [1], this changes at gravitational 1-loop when cosmic perturbations, like a gravitational wave background, are present. Such a background introduces a new scale, thereby breaking the fermions' conformal invariance. This leads to a non-vanishing gravitational self-energy for Weyl fermions at 1-loop and induces their production. In this paper, we present an extended study of this new mechanism, explicitly computing this effect using the in-in formalism. We work in an expanding Universe in the radiation-dominated era as a fixed background. Gravitational wave-induced fermion production has rich phenomenological consequences. Notably, if Weyl fermions eventually acquire mass, and assuming realistic - and potentially detectable - gravitational wave backgrounds, the mechanism can explain the abundance of dark matter in the Universe. More generally, gravitational-wave induced freeze-in is a new purely gravitational mechanism for generating other feebly interacting fermions, e.g. right-handed neutrinos. We show that this loop level effect can dominate over the conventional - tree-level - gravitational production of superheavy fermions in a sizable part of the parameter space.

    ↳ hep-thgr-qchep-phJHEP(2025)·16 citations
64. 64*

    Inflection Point of Minimally Coupled Tachyonic Scalar Field

    Jaskirat Kaur🇮🇳 · S.D.Pathak🇮🇳 · Maxim Khlopov🇷🇺 · Mananendra Sharma🇹🇭

    In this paper, we investigate the behaviour of a minimally coupled tachyonic scalar field at inflection points in an accelerating universe. We consider the different expansion factors and obtain potentials of tachyonic scalar field. Inflection points of homogeneous tachyonic scalar field is calculated for these potentials. We employ the tools of dynamical system analysis for the considered potentials and obtain the stable points.

    ↳ gr-qcastro-ph.COastro-ph.GAhep-phUniverse(2025)·3 citations
65. 65*

    Positive-Energy Dirac Particles and Dark Matter

    Eugene Bogomolny🇫🇷

    The relativistic positive-energy wave equation proposed by P. Dirac in 1971 is an old but largely forgotten subject. The purpose of this note is to speculate that particles described by this equation (called here Dirac particles) are natural candidates for the dark matter. The reasoning is based on a fact that the internal structure of such particles simply prohibits their interaction with electromagnetic fields (at least with the minimal coupling) which is exactly what is required for dark matter. Dirac particles have quite unusual properties. In particular, they are transformed by an infinite-dimensional representation of the homogeneous Lorentz group, which clearly distinguishes them from all known elementary particles described by finite-dimensional representations and hints to a physics beyond the Standard Model. To clarify the topic, a brief review of the main features of {the above-mentioned} Dirac equation is given.

    ↳ hep-thgr-qchep-phUniverse(2024)·6 citations
66. 66*

    Ringdown stability: greybody factors as stable gravitational-wave observables

    Romeo Felice Rosato🇮🇹 · Kyriakos Destounis🇮🇹 · Paolo Pani🇮🇹

    The quasinormal mode spectrum of black holes plays a crucial role in the modelling of post-merger ringdown signals. However, the spectrum is extremely sensitive to small deformations of the system and describes the linear response only in a certain (not precisely defined) timeframe after the merger. We argue here that the greybody factors, recently shown to describe the ringdown spectral amplitude at relatively high frequencies, are instead stable under small perturbations of the system and free of certain ambiguities that plague the quasinormal mode spectrum. Our analysis also unveils a nontrivial interplay: while certain ringdown quantities are dominated by the contribution of spectrally unstable quasinormal modes, these modes conspire to produce stable observables. Thus, we propose a complementary approach to ringdown studies, which circumvents some limitations of the standard quasinormal mode description.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2024)·99 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.