HEP Phenomenology·hep-ph
40 papers—21 primary·19 cross-listed·reconstructed*
An important class of observables in the heavy-ion collision programme concerns probes which are not sensitive to the prevailing strong interactions of QCD. The emission of photons, weak gauge bosons, and leptons fall into this category. Here I will describe the current status of such investigations, focusing on the emerging theoretical picture and its uncertainties.
Silvano Simula🇮🇹 · Ludovico Vittorio🇮🇹
We propose the implementation of two ingredients in the phenomenological applications of the unitary approach based on the -expansion of hadronic form factors, commonly referred to as the Boyd-Grinstein-Lebed (BGL) -expansion [1-4]. The first ingredient is the explicit addition of a unitarity filter applied to a given set of input data for the hadronic form factors. This further constraint is not usually taken into account in the phenomenological applications of the BGL -expansion. We show that it follows from the equivalence between the BGL approach and the Dispersion Matrix (DM) method [5]}, which also describes hadronic form factors in a completely model-independent and non-perturbative way. The second ingredient is represented by the introduction of suitable kernel functions in the evaluation of unitarity bounds, leading to the application of multiple dispersive bounds to hadronic form factors, whenever data and/or (non-)perturbative techniques allow to do so. This idea may be useful for the investigation of many physical processes, from the analysis of the electromagnetic form factors of mesons and baryons to the study of weak semileptonic decays of hadrons. An explicit numerical application will be presented in the companion paper [6], where the effects of sub-threshold branch-cuts are analyzed.
Silvano Simula🇮🇹 · Ludovico Vittorio🇮🇹
We apply the strategy proposed in the companion paper [1] for dealing with multiple dispersive bounds, to the case of sub-threshold branch-cuts, which is a topic addressed extensively in the literature (see, e.g., Refs. [2-8]). We consider the simultaneous application of a double dispersive bound as a proper way to take into account unitarity constraints within phenomenological analyses of hadronic form factors in the presence of sub-threshold branch-cuts. Accordingly, the standard -expansion of hadronic form factors, commonly referred to as the Boyd-Grinstein-Lebed approach [4, 9-11], is modified by including simultaneously the dispersive bounds related to the pair-production and to the sub-threshold regions. For the latter one the effects of above-threshold poles are described through a simple resonance model and the possible choices of the outer function outside the pair-production region are discussed. A detailed numerical analysis of the experimental data or lattice QCD results in the spacelike region for the charged kaon form factor is presented as a direct application of the procedure of double dispersive bound. The comparison with other methodologies present in literature and with the -expansion based on the single, total dispersive bound clearly shows that the -expansion including the double dispersive bound provides the most precise extrapolation at large momentum transfer as well as the most stable results with respect to the choice of the outer function outside the pair-production region.
Yifang Wang🇨🇳 · Zhi-zhong Xing🇨🇳 · Shun Zhou🇨🇳
We propose an unprecedented detection of reactor and oscillations by using elastic antineutrino-electron scattering processes (for ), among which the events can be singled out by accurately measuring the flux via the inverse beta decay . A proof-of-concept study shows that such measurements will not only be able to test the conservation of probability for reactor antineutrino oscillations, but also offer a new possibility to probe leptonic CP violation at the one-loop level.
It was recently proposed that predictions of Lorentz-breaking space-time foam models from string theory may be compatible with the suggestion of light-speed variation from gamma-ray burst studies. Our analysis of foam-modified kinematics shows that despite the subluminal photon velocities explaining photon time delays one may, and in certain circumstances does, keep intact the electromagnetic showers essential for the detection and identification of cosmic photons. In contrast to other~(mostly phenomenological) approaches to Lorentz violations with modified dispersions leading to drastic changes on the formation length for the cascade development in the atmosphere and in detectors, there is the possibility that the dispersion effect in the present string foam model avoids such modifications and the theory naturally escapes the shower formation constraints from recent observations.
Minxuan He🇨🇳 · Claudius Krause🇦🇹 · Daohan Wang🇦🇹
We present a dedicated graph neural network (GNN)-based methodology for the extraction of the Higgs boson signal strength , incorporating systematic uncertainties. The architecture features two branches: a deterministic GNN that processes kinematic variables unaffected by nuisance parameters, and an uncertainty-aware GNN that handles inputs modulated by systematic effects through gated attention-based message passing. Their outputs are fused to produce classification scores for signal-background discrimination. During training we sample nuisance-parameter configurations and aggregate the loss across them, promoting stability of the classifier under systematic shifts and effectively decorrelating its outputs from nuisance variations. The resulting binned classifier outputs are used to construct a Poisson likelihood, which enables profile likelihood scans over signal strength, with nuisance parameters profiled out via numerical optimization. We validate this framework on the FAIR Universe Higgs Uncertainty Challenge dataset, yielding accurate estimation of signal strength and its 68.27\% confidence interval, achieving competitive coverage and interval widths in large-scale pseudo-experiments. Our code "Systematics-Aware Graph Estimator" (SAGE) is publicly available.
In this letter, we demonstrate that products of third-order rephasing invariants of flavor mixing matrix reproduce all the nine angles of unitarity triangles and all the CP phases in the nine parameterizations of . The sum rules relating the CP phases and angles are also decomposed into terms of these rephasing invariants. Furthermore, through ninth-order invariants, these fourth- and fifth-order invariants become equivalent, which can be regarded as a certain duality. For the phase matrix and the angle matrix , are expressed in terms of even-permutations and odd-permutations of third-order invariant. As a result, these are represented by the two concise matrix equations and .
Raghunath Sahoo🇮🇳 · Kangkan Goswami🇮🇳 · Suraj Prasad🇮🇳
The study of heavy-flavor hadrons is topical in the era of precision measurements, which is useful to test theories based on pQCD. The heavy-flavor hadrons are produced initially during heavy-ion or hadronic collisions and are one of the best probes to understand the initial stages of the collisions as well as the system evolution. In experiments, the heavy-flavor sectors are studied directly via their decay to different hadrons or di-leptons or via their semi-leptonic decay, which is accompanied by additional neutrinos. However, their measurement in experiments is resource-intensive and requires input from different Monte-Carlo event generators. In this study, we provide an independent method based on Machine Learning algorithms to separate such leptons coming from heavy-flavor semi-leptonic decays. We use PYTHIA8 to generate events for this study, which gives a good qualitative and quantitative description of heavy-flavor production in collisions. We use the XGBoost model for this study, which is trained with collisions at ~TeV. We use \DCAXY, \DCAZ~and pseudo-rapidity as the input to the machine. The ML model provides an accuracy of 98\% for heavy-flavor decay electrons and almost 100\% for heavy-flavor decay muons.
Results are presented from numerical simulations of the flat-space nonlinear Maxwell-Klein-Gordon-Dirac equations. The introduction of a boson-fermion interaction allows a scalar vortex to act as a harmonic trap that can confine massive Dirac bound states. A parametric analysis is performed to understand the range of boson-fermion coupling strengths, Ginzburg-Landau parameters, and fermion effective masses that support the existence of bound state solutions; results are shown to be comparable to quasiparticle bound states in gapped Dirac materials. Solutions are time-evolved and are observed to be stable until the fermion field {\psi} becomes large enough to collapse the spontaneously broken vacuum of the condensate. Head-on scattering simulations are performed, and traditional vortex right-angle scattering is shown to break down with increased fermion field strength. For sufficiently large {\psi} and low velocity, the collision of two m = 1 vortices results in a pseudostable m= 2 bound state that eventually becomes unstable and decays back into two m= 1 vortices. For large {\psi} and collision velocity, vortex scattering is observed to produce nontopological (zero winding number) scalar bound states that are ejected from the collision. The scalar bubbles contain coherent fermion bound states in their interiors and interpolate between the spontaneously broken vacuum of the bulk and the modified vacuum induced by the boson-fermion interaction.
Transition generalized parton distributions (GPDs) describe matrix elements of nonlocal partonic QCD operators between the ground and excited baryon states and provide new tools for quantifying and interpreting the structure of baryon resonances in QCD. We discuss a description of non-diagonal Deeply Virtual Compton Scattering process involving a transition between a nucleon and a nucleon resonance in the system within the framework of transition GPDs. We address the physical content of and transition GPDs, review the existing theoretical models and present theoretical estimates of related observables for the kinematic conditions corresponding to the experimental studies with JLab@12GeV. We also discuss the perspective of exploring resonance production with help of transition GPDs and consider the application of the Froissart-Gribov projections to study excitation of nucleon resonances by means of QCD probes with spin-.
A. Amiri🇮🇷 · P. Eslami🇮🇷 · K. Azizi🇮🇷 · R. Jafariseyedabad🇮🇷
We employ the QCD sum rule method to study the semileptonic weak decay of the single bottom baryon with spin into the single charmed baryon with spin , corresponding to a weak transition. A three-point correlation function is calculated in both the physical and theoretical sides to derive the sum rules for the form factors of the transition. The analysis incorporates both the perturbative and non-perturbative contributions up to mass dimension six. After determining the working regions of the auxiliary parameters and performing numerical calculations of the sum rules of the form factors, we extract the -dependent fit functions for the form factors. The obtained fit functions are then applied to compute the decay widths of the transition in all lepton channels. Our results may serve as useful theoretical benchmarks for future experimental investigations of the semileptonic weak decays and the weak dynamics of excited heavy baryons.
Bhabana Kumar🇮🇳 · Mrinal Kumar Das🇮🇳
We present a model constructed within a non-supersymmetric framework capable of explaining both current neutrino oscillation data and the observed dark matter relic abundance. In this study, the Yukawa couplings are expressed as polyharmonic Maaß{} forms, and the non-supersymmetric left-right symmetric model is realized through the modular group, with neutrino masses generated via the Type II seesaw dominance mechanism. The analysis focuses on determining the neutrino oscillation parameters, the effective Majorana mass arising from the standard contribution, and the dark matter relic density. Our results indicate that the model strongly favours the normal mass hierarchy over the inverted one and prefers the lower octant for the mixing angle . Furthermore, the effective Majorana mass is predicted to lie in the range to . In addition, the lightest sterile neutrino present in the model is considered a viable dark matter candidate. A sterile neutrino mass in the range to is found to yield consistent results for both the relic density and active-sterile mixing angles.
We introduce two basic concepts: the compositeness for resonance and the Castillejo-Dalitz-Dyson (CDD) pole. Applying them to hadron states , and , and , we obtain their compositeness values and achieve deeper insights into their inner structure.
Marzieh Bahmani🇩🇪 · Alessandro Guida🇩🇪 · Maral Khandan · Heiko Markus Lacker🇩🇪 · Anupama Reghunath🇩🇪
The precise reconstruction of the mass peak of long-lived heavy neutral leptons (HNLs) helps to improve the sensitivity for sterile neutrino searches in both fixed-target and collider environments (e.g., SHiP and the LHC). We present an analytical framework for reconstructing the HNL mass peak in the semileptonic HNL decay channel \(N\rightarrow l\rho\) with \(\rho\to\pi\pi^0\), using only the lepton and the charged pion emerging from the decay vertex together with kinematic constraints and the known particle masses. Incorporating mass constraints from intermediate resonances (e.g., the \(\rho\) meson) or the parent particle (e.g., the \(W\) boson at the collider experiments), we propose two methods, suitable for experiments with displaced vertex tracking capabilities. The particle-level simulation's results demonstrate that the \(\rho\)-mass constraint method yields promising HNL mass resolution in both beam-dump and collider-based environments. The W-mass constraint method, limited to the HNLs produced via \(W\)-boson decays at the collider-based experiments, shows better HNL mass resolution than the \(\rho\)-mass constraint method.
Amir Subba🇮🇳 · Ritesh K. Singh🇮🇳
The upcoming electron-positron collider provides an ideal place to probe deviation from the Standard Model predictions with its clean environment, beam polarization and significant luminosity. We studied anomalous quartic gauge boson couplings~(), triple gauge couplings~(, and Higgs-gauge couplings ) induced by gauge invariant dimension-6 operators in final events with initial beam polarization. The phase space of two prominent amplitudes i.e, triple gauge boson production and vector boson scattering sub-processes, are selected with boosted decision trees. We employ the asymmetries related to polarization and spin correlation observables along with cross~section to constrain the anomalous couplings. The parity odd polarizations and spin correlations of jets from boson require flavor tagging which is done using artificial neural networks. We provide one parameter limits at confidence level combining cross~section and spin related observables. Finally, marginalized limits on all nine anomalous couplings are obtained with MCMC analysis. The limits are found to be insensitive to systematic errors and dominated by statistics. We find that the VBS-like events provides a tighter constraints to and Wilson coefficients (WCs) in comparison to limits from WWZ phase space. For the remaining WCs, WWZ contribute significantly to the overall limits.
The dynamics of a light fermion bound to a heavy one is expected to be described by the Dirac equation with an external potential. The potential breaks translation invariance, whereas the bound state momentum is well defined. Boosting the bound state determines the frame dependence of the light fermion dynamics. I study the Dirac limit of QCD in the limit of . The light quark wave function turns out to be independent of the frame of the bound state, up to an irrelevant Lorentz contraction. The discrete bound state spectrum determines corresponding discrete energies of the Dirac equation, which for a linear potential allows a continuous spectrum.
Wei Dai🇨🇳 · Yuanlin Gong🇨🇳 · Guanhua Gu🇨🇳 · Liangliang Su🇨🇳 · Li Wang🇨🇳 · Lei Wu🇨🇳 · Yongcheng Wu🇨🇳 · Litao Yang🇨🇳
Nuclear power plants are not only vital sources of clean energy but also powerful facilities for probing new physics beyond the Standard Model. Due to the intense gamma-ray flux and an appropriate energy conditions, they are particularly well-suited for searches of light hypothetical particles such as sub-MeV axions and axion-like particles (ALPs). In this work, we propose to search for the ALPs in the REactor Neutrino COherent scattering Detection Experiment (RECODE), where two low-threshold, high-purity germanium detectors are placed at 11 m (near point) and 22 m (far point) from a 3.4 GW nuclear reactor at Sanmen nuclear power plant. With a 10 kgyear exposure, we demonstrate that the expected sensitivities to the ALP couplings to the electrons and photons are competitive with or surpass the available results from the beam-dump experiments. A planned upgrade to 100 kgyear will fully cover the so-called { cosmological triangle} region, probing unexplored parameter space relevant to axions.
We investigate energy correlators in semi-inclusive electron-positron annihilation as precision probes of parton hadronization dynamics. Using soft-collinear effective theory, we analyze the correlation patterns between the examined hadron and the rest of QCD radiations in both large-angle and small-angle limits, which establishes a direct correspondence with transverse-momentum-dependent fragmentation functions and fragmentation energy correlators. The two complementary regimes encode the transition from perturbative parton branching to nonperturbative confinement, enabling a unified description of hadron formation across all kinematic regimes. Using renormalization group evolution, we obtain joint NLL/NNLL quantitative predictions for energy correlations both in the sudakov and jet fragmentation region. Our results demonstrate that semi-inclusive energy correlators provide direct, theoretically controlled access to QCD dynamics underlying hadronization, opening new avenues for precision studies at future lepton colliders as well as through reanalyses of archival LEP data.
We compute the twist-2 matching of transverse momentum dependent (TMD) helicity parton distribution and fragmentation functions at next-to-next-to-next-to-leading order (NLO) in QCD. This calculation entails the complete set of next-to-next-to-leading order (NNLO) Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) splitting functions govering the evolution of helicity-dependent parton distribution functions (PDFs) and fragmentation functions (FFs). Within TMD factorization framework, we quantify the impact of radiative corrections by completing the next-to-next-to-next-to-leading logarithmic (NLL) prediction for lepton-hadron transverse momentum imbalance in semi-inclusive deep inelastic scattering (SIDIS). Our results provide the most precise theoretical input for probing the helicity structure and confined motion of quarks and gluons at future electron-ion collider (EIC).
Duarte Feiteira🇫🇮 · Fotis Koutroulis🇨🇳 · Oleg Lebedev🇫🇮 · Stefan Pokorski🇵🇱
Inflationary expansion of space-time provides us with an efficient particle production mechanism in the Early Universe. The fermion production efficiency depends critically on the particle mass, which is generated via the Yukawa coupling and sensitive to the corresponding scalar field value. During inflation, scalar fields experience large quantum fluctuations driving the average field values to the Hubble scale and above. This applies, in particular, to the Higgs field, making the Standard Model fermions very heavy and facilitating their production. Using the Bogolyubov coefficient approach, we compute the corresponding fermion abundance taking into account time dependence of the mass term. We find that the Standard Model fermion and the right-handed neutrino production grows dramatically compared to the naive estimate based on the low energy masses. The inflationary production mechanism can be the leading source of the right handed neutrinos, if they gain a Majorana mass from the Yukawa coupling to a light scalar. We also find a lower bound on the mass of fermionic dark matter, which can be produced by inflation.
Rafael Boto🇵🇹 · Tiago P. Rebelo🇵🇹 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹
We introduce a two real scalar singlet extension of the two Higgs doublet model. We study the vacuum structure, the bounded from below conditions, the restrictions from the oblique parameters S,T and U, as well as the unitarity constraints. We submit the model to collider and Dark Matter experimental constraints and explore its allowed parameter space. We compare randomly populated simulations, simulations starting near the alignment limit, and a Machine Learning based exploration. Using Evolutionary Strategies, we efficiently search for regions with a viable Dark Matter candidate.
Dong Jo Kim🇫🇮 · Tero Lappeteläinen
This paper presents a data-driven analysis of Quark Matter conferences from 2011 to 2025, investigating trends in geographical representation, research emphasis, and methodological strategies. Using a dataset of over 10,000 presentations, the evolution of heavy-ion physics through its premier conference series is examined. The distribution of presentations across countries and institutions shows the global reach of the field while highlighting opportunities for broader international engagement. Research topics show clear temporal trends, with certain physics concepts rising and falling in prominence, and a gradual shift from facility-focused to phenomenon-focused research. The analysis reveals increasing integration between theoretical and experimental approaches over time, reflecting a maturing field where these complementary domains strengthen and enhance each other. These findings provide quantitative insights that the evolution of heavy-ion physics is strengthened by international collaboration at conferences. The analytical methods developed here could help other scientific communities understand their own patterns of knowledge sharing and development.
Large Momentum Effective Theory (LaMET) provides a general framework for computing the multi-dimensional partonic structure of the proton from first principles using lattice quantum chromodynamics (QCD). In this effective field theory approach, LaMET predicts parton distributions through a power expansion and perturbative matching of a class of Euclidean observables -- quasi-distributions -- evaluated at large proton momenta. Recent advances in lattice renormalization, such as the hybrid scheme with leading-renormalon resummation, together with improved matching kernel that incorporates higher-loop corrections and resummations, have enhanced both the perturbative and power accuracy of LaMET, enabling a reliable quantification of theoretical uncertainties. Moreover, the Coulomb-gauge correlator approach further simplifies lattice analyses and improves the precision of transverse-momentum-dependent structures, particularly in the non-perturbative region. State-of-the-art LaMET calculations have already yielded certain parton observables with important phenomenological impact. In addition, the recently proposed kinematically enhanced lattice interpolation operators promise access to unprecedented proton momenta with greatly improved signal-to-noise ratios, which will extend the range of LaMET prediction and further suppress the power corrections. The remaining challenges, such as controlling excited-state contamination in lattice matrix elements and extracting gluonic distributions, are expected to benefit from emerging lattice techniques for ground-state isolation and noise reduction. Thus, lattice QCD studies of parton physics have entered an exciting stage of precision control and systematic improvement, which will have a broader impact for nuclear and particle experiments.
Yong Gao🇩🇪 · Hao-Jui Kuan🇩🇪 · Cheng-Jun Xia🇨🇳 · Hector O. Silva🇺🇸 · Masaru Shibata🇩🇪
Dynamical tides of neutron stars in the late stages of binary inspirals provide a viable probe into dense matter through gravitational waves, and potentially trigger electromagnetic precursors. We model the tidal response as a set of driven harmonic oscillators, where the natural frequencies are given by the quasinormal modes of a nonrotating neutron star. These modes are calculated in general relativity by applying linear perturbation theory to stellar models that include a solid crust and compositional stratification. For the mode spectrum, we find that the canonical interface mode associated with the crust-core boundary vanishes in stratified neutron stars and is replaced by compositional gravity modes with mixed gravity-interfacial character, driven primarily by strong buoyancy in the outer core. We also find that fluid modes such as the core gravity mode and the fundamental mode can penetrate the crust, and we establish a criterion for such penetration. Regarding the tidal interaction, we find that transfer of binding energy to oscillations is dominated by the fundamental mode despite its frequency being too high to resonate with the tidal forcing. In general, we find that lower-frequency modes induce gravitational-wave phase shifts smaller than for the equation of state we consider. We discover that nonresonant fundamental and crustal shear modes can trigger crust breaking already near the first gravity-mode resonance, while gravity-mode resonance concentrates strain at the base of the crust and may marginally crack it. These results suggest that both resonant and nonresonant excitations can overstress the crust and may channel energy into the magnetosphere prior to merger, potentially powering electromagnetic precursors. Our work represents an important step toward realistic modeling of dynamical tides of neutron stars in multimessenger observations.
Viktor G. Czinner🇵🇹 · Hideo Iguchi🇯🇵
The Hawking-Rényi model requires the Rényi entropy thermodynamic temperature of a black hole to be identical with the surface gravity defined-, Hawking temperature. We investigate this approach for stationary black hole space-times, and show that a locally Kiselev-type behavior around the horizon with a coupled anisotropic fluid is sufficient to provide a solution to the problem. In addition, due to the rotating motion, an extra shift has also to be present in the effective mass of the black hole, which is determined by the rotation parameter, , and the Rényi parameter, . We consider space-times with and without electric charge, and show that the functional form of the solution is the same for both cases. A full thermodynamic analysis of the model falls beyond the scope of this Letter, the main achievements are the derivation and interpretation of the solution.
Cong Yi🇨🇳 · Shuo Fang🇨🇳 · Dong-Lin Wang🇨🇳 · Shi Pu🇨🇳
We have computed the second Fourier sine coefficient of the longitudinal spin polarization, , as a function of multiplicity or centrality in Au+Au collisions at GeV and in +Pb collisions at TeV using the CLVisc hydrodynamic framework. The numerical results successfully describe the data in Au+Au collisions. However, understanding the data in +Pb collisions remains a puzzle. Additionally, we have reported some recent developments in quantum kinetic theory and spin hydrodynamics.
Cheng-Jun Fang🇨🇳 · Han-Wen Hu🇨🇳 · Zong-Kuan Guo🇨🇳
Small-scale scalar perturbations amplified during inflation can induce primordial gravitational waves through tensor-scalar interactions. A long-standing controversial issue is whether the one-loop corrections to tensor perturbations exist on large scales. Firstly, we demonstrate through direct one-loop calculations that one-loop corrections cancel each other out on large scales. We then proceed from the symmetry of the interacting system and directly prove, based on the Ward identity, the absence of one-loop corrections on large scales-without the need for specific loop diagram calculations. This is consistent with the results we previously obtained for scalar perturbations.
Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸
Deuterons with different polarization states have distinct shapes for their wavefunctions. This offers a unique opportunity to experimentally control the initial-state collision geometry with the polarization of the light-ion targets in relativistic heavy-ion experiments. We study the charged hadron elliptic flow coefficients with respect to the polarization angle of deuterons in Pb + polarized deuteron collisions using a hydrodynamics + hadronic transport model. Hydrodynamic response to initial-state geometry predicts a distinct sign of correlated with the deuteron's polarization states, providing a clean test case for elucidating the collective origin in small collision systems.
David Chinellato🇧🇷 · Michael Lisa🇺🇸 · Willian Serenone🇧🇷 · Chun Shen🇺🇸 · Jun Takahashi🇧🇷 · Giorgio Torrieri🇧🇷
We present event-by-event simulations for central asymmetric p+Ar collisions at GeV to investigate the formation and evolution of vortex-ring structures from the early-stage longitudinal flow velocity profile. Our predictions for their imprints on Lambda hyperon's polarization observables are complementary to those presented in Ref. [Phys.Rev.C 110 (2024) 5, 054908] and can be explored in the future fixed-target collisions at the Large Hadron Collider beauty (LHCb) experiment.
Shu-Hua Yang🇨🇳 · Fridolin Weber🇺🇸
We show that the compact star XTE J1814-338 can be explained as a strange star admixed with self-interacting bosonic dark matter (BDM), provided the dark matter fraction exceeds approximately 70\%. This interpretation leads to a robust constraint on the BDM particle mass: MeV ( is the dimensionless coupling constant of the BDM). The result is independent of formation scenario and microphysical details and is falsifiable by future NICER and LIGO/Virgo observations.
These lectures aim to highlight the remarkable symbiosis that currently exists between the physics of the very small and the physics of the very large, using the unsolved puzzle of the nature of Dark Energy as a vehicle for so doing. The lectures first summarize what we know observationally about the properties of Dark Energy (and the Dark sector more broadly) and then discuss several approaches to explain them. Along the way this involves determining the types of interactions that would on general grounds be expected to be present in the low-energy limit of fundamental theories involving the many hierarchy of scales we see around us. This includes (but is not limited to) a discussion of technical naturalness (and `t Hooft naturalness) as well as the arguments for their use as a criterion for distinguishing amongst candidate theories. Some recent approaches I find promising are briefly summarized at the end.
The processes of splitting and merging of black holes obey the composition law generated by the Tsallis-Cirto statistics. The same composition law expresses the full entropy of the Reissner-Nordström black hole via the entropies of its outer and inner horizons. Here we apply this composition law to the thermodynamics of the Kerr black hole. As distinct from Reissner-Nordström black hole, where the full entropy depends only on mass and does not depend on its charge , the entropy of Kerr black hole is the sum of contributions from its mass and angular momentum , i.e. . Here is the entropy of the Schwarzschild black hole. This demonstrates that when the Kerr black hole with absorbs or emits a massless particle with spin , its entropy changes by . We also considered the quantization of entropy suggested by the toy model, in which the black hole thermodynamics is represented by the ensemble of the Planck-scale black holes -- Planckons. The Tsallis-Cirto composition law is also extended to the thermodynamics of Kerr-Newman black hole.
Dongdong Wei🇨🇳 · Zong-Kuan Guo🇨🇳 · Qiqi Fan🇨🇳
We investigate the evolution and formation of double-layered vacuum bubbles during cosmological phase transitions with multiple vacua. We employ lattice simulations to show that flyover transitions can produce double-layered vacuum bubbles by overcoming successive potential barriers, thereby suggesting a novel bubble vacuum configuration in cosmological phase transitions. The evolution of these bubbles, including wall acceleration, collisions, and the formation of trapped regions, is explored through numerical simulations. Our results show that the dynamics of double-layered bubbles differ significantly from standard single-wall bubbles, with implications for cosmological observables such as gravitational wave production and baryogenesis.
Anum Arslan🇨🇳 · Wen-Bo Dong🇨🇳 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Qun Wang🇨🇳 · Xiang-Yu Wu🇨🇦
We give an analytical expression for the in-plane polarization , in heavy-ion collisions that has, to our knowledge, not been measured in heavy-ion collision experiments. We also carry out a numerical study of using a hydrodynamic model simulation as a cross-check for the analytical formula. It is found that if the temperature-gradient contribution is neglected the simulation result for qualitatively agrees with the analytical one. The prediction of can be tested in experiments and will contribute to provide a complete and consistent picture of spin phenomena in heavy-ion collisions.
Kotaro Murakami🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Yan Lyu🇯🇵 · Wren Yamada🇯🇵
We investigate S-wave kaon-nucleon () interactions with strangeness in lattice QCD using the time-dependent HAL QCD method. Employing the -flavor gauge configuration with and , we calculate the potentials at the leading order in the derivative expansion. The potentials in both isospin channels ( and ) exhibit repulsion at short distances, while only the potential has a small attractive pocket at intermediate distances. From these potentials, we compute the phase shifts as well as the low-energy scattering parameters. The obtained phase shifts show no signals corresponding to resonances or bound states in both isospin channels, suggesting the absence of the pentaquark in the S-wave systems. The results for suggest that the scattering amplitudes in this channel are dominated by P-wave components rather than S-wave.
Jinhui Chen🇨🇳 · Diyu Shen🇨🇳 · Xu Sun🇨🇳 · Aihong Tang🇺🇸 · Baoshan Xi🇨🇳
The method in arXiv:2508.18409 constructs a ``data-driven correction'' from combinatorial (pseudo-) pairs and applies it to the signal. An explicit decomposition shows that the construction calibrates the background response rather than the signal: it is defined by the difference between an acceptance-free pseudo- surrogate and its data-level realization. Promoting a background-derived correction to a signal correction requires a strong physics proof that signal and background share identical detector response at the pair level -- including acceptance-anisotropy couplings and dependencies on parent kinematics -- which the manuscript does not establish. Consequently, local numerical proximity in a restricted region of phase space is incidental rather than evidentiary; validation must rest on mechanism, not numerical coincidence. Moreover, the pseudo- background is non-unique: with infinitely many admissible constructions, any apparent agreement for a few cases would not be dispositive -- no finite scan can substitute for a mechanism-level response equivalence. In the absence of such a demonstrated equivalence, the construction should be regarded as a background calibration rather than a signal correction.
Masanobu Kunitomo🇯🇵 · Gaël Buldgen🇧🇪 · Tristan Guillot🇫🇷
(abridged) Recent analyses have reported low lithium but high beryllium abundances on the solar surface; however, standard solar models (SSMs) predict Li abundances that are ~30 away from the observed value. In this study, we aim to develop solar models and compare them with the Li and Be abundance constraints. We examine the effect of protosolar accretion and turbulent mixing below the base of the surface convective zone. We compute ~200 solar evolutionary models for each case to optimize input parameters using target quantities, similar to the SSM framework. We confirm that turbulent mixing helps reproduce the surface Li and Be abundances within ~0.6 by enhancing burning. It suppresses gravitational settling, leading to a better matching of the He surface abundance (0.3) and a smaller compositional gradient. We derive a new protosolar helium abundance . Turbulent mixing decreases the central metallicity () by 4.4%, even though accretion increases by 4.4%, as suggested by our previous study. Unfortunately, the reduction in implies that our models do not reproduce constraints on observed neutrino fluxes by for and for CNO. Including turbulent mixing in solar models appears indispensable to reproduce the observed atmospheric abundances of Li and Be. However, the resulting tensions in terms of neutrino fluxes, even in the models with the protosolar accretion, show that the solar modeling problem remains, at least partly. We suggest that improved electron screening, as well as other microscopic properties, may help alleviate this problem. An independent confirmation of the neutrino fluxes measured by the Borexino experiment would also be extremely valuable.
S. Mohammadi · R. Gharaei · S. A. Alavi🇮🇷
We select 300 different parent nuclei in the range Z from 64 to 106. The proximity potentials Zhang 2013 and Guo 2013 are employed to calculate the nuclear potential. The influence of the nuclear surface diffuseness is applied in the calculations of interaction potential between the emitted alpha particle and daughter nucleus through the reduced radius parameter. The systematic analysis of the radial behavior of interaction potential with and without the surface diffuseness effect reveals that these effects play decisive role in the calculation of nucleus-nucleus potential at the touching radius of the two interacting nuclei. We indicate that its influence decreases outside the touching configuration. In addition, our results reveal that the barrier penetration probability of the alpha particle through the barrier decreases by imposing the mentioned physical effects. It is worth noting that the calculated alpha-decay half-lives using the Zhang 2013 and Guo 2013 proximity potentials accompanied by the surface effects agree very well with the available experimental data. The theoretical halflives are calculated for 50 super-heavy nuclei using the modified forms of the Zhang 2013 and Guo 2013 models. The comparison with available experimental data and also with different empirical formulas demonstrates that the Guo 2013 model is suitable to deal with the alpha decay half-lives of SHN. Then the predictions of alpha decay half-lives for 65 SHN with Z from 120 to 126 are made by using Guo 2013 model with the surface effects. We found that there is a good agreement between our predicted half-lives and those obtained from semi-empirical formulas such as Royer and UDL.
Matthias Vigl🇩🇪 · Lukas Heinrich🇩🇪
Recently, the benefit of heavily overparameterized models has been observed in machine learning tasks: models with enough capacity to easily cross the \emph{interpolation threshold} improve in generalization error compared to the classical bias-variance tradeoff regime. We demonstrate this behavior for the first time in particle physics data and explore when and where `double descent' appears and under which circumstances overparameterization results in a performance gain.
Alexei Starobinsky is one of the main authors of inflationary cosmology. Here I will discuss the Starobinsky model and its generalizations, including the theory of -attractors. I will then describe the current status of these models in light of the latest observational results from ACT, SPT, and DESI.
* 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.