HEP Phenomenology·hep-ph
23 papers—15 primary·8 cross-listed·reconstructed*
I present some memories of my Ph.D supervisor and, later, collaborator but always encouraging supporter Prof. G. Lazarides. Some of his contributions to our common and related scientific activities on the phenomenology of MSSM and inflation are also summarized.
Yu-Bin Zhang🇨🇳 · Yi-Heng Wang🇨🇳 · Hui-Hua Zhong🇨🇳 · Li-Ye Xiao🇨🇳
To shed light on the inner structure of the observed single-bottom strange baryons, in this work we systematically study the Okubo-Zweig-Iizuka allowed strong decay properties of - and -wave and baryons within the coupling scheme in the framework of the quark pair creation model. For a comparison, we also give the predictions of the chiral quark model. The calculations indicate that: (i) The -wave -mode states and are highly promising candidates for the observed state and , respectively. The -wave -mode states and are likely candidates for the state . Meanwhile, we cannot rule out the possibility that could be a candidate of the -wave -mode state or . (ii) For the other -wave -mode states and -wave -mode states, they may be moderate states with a width of several tens of MeV. Their main decay channels are , , or . The width of the -wave -mode states are slightly broader, approximately several tens to over one hundred MeV, and the dominant decay channels are , , or . (iii) The -wave -mode and states are most likely to be relatively narrow state with a width of only a few to around ten MeV, and they mainly decay into or . In addition, the -wave -mode states may also mainly decay into the -wave baryon via the pionic decay processes.
Yongsoo Jho🇰🇷 · Jeonghwan Park🇰🇷 · Min Gi Park🇰🇷 · Seong Chan Park🇰🇷
We examine Sommerfeld enhancement in dark matter annihilation as a potential origin of the halo-like gamma-ray excess near GeV reported by Totani. A minimal model with a light CP-even scalar mediator naturally produces a velocity-dependent annihilation cross section consistent with thermal freeze-out, the Milky Way excess, and limits from dwarf spheroidal galaxies.
Sheng-Qi Zhang🇨🇳 · Cong-Feng Qiao🇨🇳
Following the experimental confirmation of tetraquark and pentaquark states, the search for hexaquark states has emerged as a new frontier in hadron physics. The recent observation of and by BESIII collaboration has provided evidence for the predicted bound states. Such baryon-antibaryon configurations, encompassing both bound states and resonances, are commonly referred to as baryoniums and are regarded as promising hexaquark candidates. In this article, we provide a comprehensive review of the investigations into baryonium states and their constituents, i.e., baryons, within the framework of QCD sum rules. We delineate the fundamental calculation procedures of this method to facilitate its practical application and benchmark the theoretical predictions against alternative models as well as the latest experimental data.
An extension of the Standard Model with modular flavor symmetry is presented. We consider the construction of the lepton sector, augmented by two right-handed neutrino states, in the vicinity of the fixed points , and . Due to the residual symmetries at these points, and with the aid of nonholomorphic modular forms (which constitute representations of ) and by assigning specific transformation properties to the fermion fields, highly economical models (without flavon fields) are constructed with interesting Yukawa textures. All presented models strongly prefer the inverted ordering for the neutrino masses.
Wanyun Chen🇨🇳 · Chih-Ting Lu🇨🇳 · Hanxin Shen🇨🇳
The dark sector may possess a rich structure yet to be uncovered, and a QCD-like dark sector with GeV-scale dark hadrons can yield novel signatures at the Large Hadron Collider (LHC). In this work, we focus on a light singlet pseudoscalar mediator that connects the QCD-like dark sector to the Standard Model (SM) sector via the Higgs portal. Notably, when the lightest unstable dark meson has a mass of approximately GeV, it predominantly decays into a pair of gluons and behaves as a long-lived particle, a scenario that has received relatively little attention. We consider various Higgs production channels at the LHC and investigate two processes for generating dark mesons: (1) the cascade decay of the Higgs boson into a pair of light pseudoscalar mediators, which subsequently decay into four dark mesons; and (2) the dark shower and hadronization process whereby the Higgs boson decays into a pair of dark quarks that subsequently evolve into dark mesons. These processes give rise to novel gluon-rich dark jets composed of long-lived dark mesons. Notably, we find that appropriate trigger selection constitutes a crucial factor for detecting these signal signatures in both tracker system and CMS muon system. At the high-luminosity LHC, the exotic Higgs branching ratio to cascade decays (dark showers) can be constrained below [] for dark meson proper lifetimes ranging from mm to m.
Gabriel Rabelo-Soares🇧🇷 · Reinaldo Francener🇧🇷 · Gabriel S. Ramos🇧🇷 · Giorgio Torrieri🇧🇷
Recent studies have shown that hadronic multiplicity in deep inelastic scattering can be associated with entanglement entropy. However, such definitions are intrinsically longitudinal and do not capture the full phase-space structure of the proton. In this work, we investigate the proton Wehrl entropy constructed from the gluon Husimi distribution, which provides a positive phase-space description within the present definitions and model calculations. Within this framework, we employ a gluon light-front spectator model based on soft-wall AdS/QCD-inspired wave functions, with free parameters constrained by global NNPDF fits, allowing us to compute both parton distribution functions and Wigner distributions. The Husimi distribution is obtained via Gaussian smearing of the Wigner distribution with width given by the saturation scale in the GBW model. We show that from a normalized Husimi distribution one can decompose the Wehrl entropy into an entanglement entropy term and a residual term associated with transverse degrees of freedom. Numerical results for the proton entanglement entropy are shown and compared with CMS data, while the Wehrl entropy is presented for different values of the virtuality.
Guglielmo Coloretti🇨🇭 · Andreas Crivellin🇨🇭 · Howard E. Haber🇺🇸
The observation of resonant di-Higgs production, which would strongly suggest the existence of a new heavy neutral scalar , has been searched for extensively at the LHC. In the two-Higgs doublet model (2HDM) with , where is the Higgs boson of mass 125 GeV observed at the LHC, we show that a direct correlation emerges between and , with , which depends only on (and ). In particular, for heavy scalar masses between 500 GeV and 1 TeV, we find that . Moreover, is a dominant decay mode over a significant region of the parameter space and serves as the primary probe for a heavy scalar resonance at current and future hadron colliders. The origin of these predictions is most transparent in the Higgs basis, where the term in the scalar potential proportional to (and its hermitian conjugate) generates the leading contributions to the and couplings in the decoupling limit of the 2HDM. Additionally, the latter coupling governs the resonant prompt tri-Higgs production via , which is also directly correlated to (and ), and can yield rates large enough to be measured at the High-Luminosity LHC.
We analyze the mass spectra of hadrons and demonstrate that the physical spectra of mesons and baryons are well described by the exponential spectrum of open strings. The open-string spectrum, derived from string theory, is characterized by a unique Hagedorn temperature and free from any other parameters. Notably, our fitting to the physical spectra yields consistent values for both mesons and baryons, , which contrasts with previous phenomenological analyses that suggested different values. This obtained value aligns well with typical string tension derived from lattice-QCD calculations and the Regge slope. In the baryonic sector, our results indicate that diquarks play a crucial role in describing the mass spectrum, implying that baryons can be understood as a quark-diquark system, as anticipated by Regge phenomenology. These findings have significant implications for our understanding of quark deconfinement, especially in the possibly existing regime at high temperature and small baryon chemical potential within the QCD phase diagram.
Ashutosh Dwibedi🇮🇳 · Satyajit Puhan🇮🇳 · Sabyasachi Ghosh🇮🇳 · Harleen Dahiya🇮🇳
We calculate the in-medium valence quark distribution of the pion immersed in a finite baryon density using the light-cone quark model. The medium-modified pion properties are obtained by using the constituent quark mass-dependent light cone wave functions. To obtain the constituent quark masses at finite baryon density, we employ the two-flavor Nambu--Jona-Lasinio model. We primarily focus on the in-medium electromagnetic form factor, distribution amplitude, and the parton distribution function of the pion. The parton distribution functions are also evolved from the model scale to a perturbative scale using next to leading order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations. Furthermore, our calculated form factors are compared with available experimental measurements and lattice quantum chromodynamics studies. We also examine the Mellin moments derived from our parton distribution functions in comparison with existing extractions and theoretical model predictions.
Shufang Qiang🇨🇳 · Peiwen Wu🇨🇳 · Yongchao Zhang🇨🇳
The left-right symmetric model (LRSM) could not only restore parity of the weak interaction, but also provide natural explanations of the tiny active neutrino masses via the seesaw mechanisms. The -breaking scalar can induce lepton flavor violating (LFV) effects in the minimal version of LRSM at the 1-loop order, originating from the mixing of heavy right-handed neutrinos (RHNs). If is light, say below the GeV scale, it will lead to rich signals, e.g. the LFV muon and tauon decays ( being either visible or invisible final states) and the anomalous supernova signatures. Combined with the diphoton coupling of , and recasting the existing constraints onto the light scenario, the right-handed scale is excluded up to GeV. In the future, the scale can be probed up to GeV in high-precision muon experiments, if the Yukwa couplings for RHN masses are of order one and the RHN mixing is maximal, and further up to GeV by supernova observations, reaching the non-resonant leptogenesis scale in the LRSM.
K.S. Babu🇺🇸 · Sumit Biswas🇺🇸
We develop a universal seesaw version of the Pati-Salam model wherein quarks and leptons of each family are unified into common multiplets transforming as under the gauge symmetry. Parity symmetry is spontaneously broken in the model, which helps in solving the strong CP problem without the axion. The Higgs sector of the model is very simple, consisting of a single pair of fields. Fermion masses arise through mixing of the chiral fermions with vector-like quarks and leptons contained in as well as multiplets via a universal seesaw mechanism. Consistency of such a spectrum with the observed quark and lepton masses is established. The parity solution to the strong CP problem is shown to be effective in this framework, although there are new loop contributions to , compared to the analogous left-right symmetric model, arising from color sextet and octet fermions, as well as from diagrams mediated by leptoquark bosons. We also find that, in this setup, although lepton number is broken, neutrino masses remain zero at the tree-level. Small and finite Majorana neutrino masses are induced via one-loop diagrams, which we analyze and show to be compatible with oscillation experiments.
K. S. Babu🇺🇸 · P. S. Bhupal Dev🇺🇸 · Anil Thapa🇺🇸
We develop a general effective field theory (EFT) framework for neutrino-dark matter (DM) interactions, and apply it to systematically find all possible gauge-invariant ultraviolet (UV) completions at a given EFT operator dimension. Our goal here is to find simple UV-complete models that can realize potentially large neutrino-DM interactions, while being consistent with all existing theoretical and experimental constraints. We first construct the leading non-derivative operator basis for neutrino-DM scattering in a low-energy effective theory with neutrinos and DM (DM-LEFT), together with its gauge-invariant embedding in the Standard Model EFT (DM-SMEFT). We then construct all renormalizable tree-level UV completions that generate the relevant DM-SMEFT operators up to dimension-8 using a topology-based classification. Using this framework, we present minimal UV-complete models for different DM types that can yield effective neutrino-DM couplings up to several orders of magnitude larger than the Fermi coupling, while satisfying all constraints, most notably from neutrino mass and from the charged-lepton sector. This includes a pseudo-Dirac fermion DM realization in the scotogenic neutrino mass model and models of Majorana DM inspired by type-II and inverse seesaw-based neutrino mass models. Phenomenological implications for DM thermal relic abundance and direct detection prospects, as well as various cosmological and laboratory constraints on the model parameter space, are also analyzed.
Martin A. Mojahed🇮🇹 · Sascha Weber🇩🇪
We present an experimentally testable leptogenesis mechanism based on the standard type-I seesaw model that successfully operates at right-handed-neutrino (RHN) masses around the GeV scale. The mechanism takes place in a cosmological background with an asymmetry between right-handed electrons and left-handed positrons generated at high temperatures, and does not require oscillations between RHNs or any CP violation in the RHN sector. In contrast to standard leptogenesis via freeze-in, our mechanism works even in the presence of a single RHN around the GeV scale. The mechanism is illustrated for the minimal type-I seesaw with two RHNs, where we show that successful baryogenesis via leptogenesis is viable in large regions of parameter space even without a small mass splitting between the RHNs.
Reuven Balkin🇺🇸 · Ta'el Coren🇮🇱 · Alexander Jentsch🇺🇸 · Hongkai Liu🇺🇸 · Maksym Ovchynnikov🇨🇭 · Yotam Soreq🇮🇱 · Sokratis Trifinopoulos🇨🇭
We investigate the sensitivity of the Electron-Ion Collider~(EIC) to invisible final states in coherent exclusive electroproduction. The characteristic signal is a forward proton with reduced energy and little additional detector activity. Using the excellent particle detection capabilities and kinematics reconstruction at the EIC, we argue that backgrounds can be strongly suppressed. While our analysis applies to various states, we specifically focus on vector and pseudoscalar particles: (i)~neutral mesons (), whose invisible Standard Model decays are extremely suppressed, and (ii)~gluon-coupled axion-like particles~(ALPs) decaying invisibly to a dark sector. With the baseline detector and a conservative residual-background estimate, the EIC can improve the sensitivity to invisible , , , and decays by factors of about - and probe invisible decays for the first time. With further background reduction and optimized detector performance, the projected sensitivity may reach branching fractions as small as . In addition, under the same conditions, the EIC would directly probe invisibly decaying ALPs with the couplings up to and masses in the range -.
Vinicius Mikuni🇯🇵 · Ibrahim Elsharkawy🇺🇸 · Benjamin Nachman🇺🇸
Foundation models build an effective representations of data that can be deployed on diverse downstream tasks. Previous research developed the OmniLearned foundation model for collider physics and showed that it could significantly advance discovery potential across collider experiments. In this paper we go beyond collider physics and show that Foundation Models trained on collider data can help improve the prediction of cosmological parameters and to predict halo and galaxy velocities in different datasets from CosmoBench. This is the first time a collider physics model is shown to generalize across scientific fields.
Nitesh Kumar🇺🇸 · Giovanni Otalora🇨🇱 · Rodrigo Reyes🇨🇱 · Bastian Espinoza🇨🇱 · Manuel Gonzalez-Espinoza🇨🇱 · Emmanuel N. Saridakis🇬🇷
We study Higgs-like inflation in the framework of scalar-torsion gravity, focusing on the general class of theories in which gravitation is mediated by torsion rather than curvature. Motivated by the increasing precision of cosmic microwave background and large-scale-structure observations, we examine whether Higgs-like inflation remains compatible with current data in this extended gravitational setting. Working within the slow-roll approximation, we analyze the inflationary dynamics both analytically and numerically. In the dominant-coupling regime we derive closed-form expressions for the scalar spectral index and the tensor-to-scalar ratio as functions of the number of e-folds, and we subsequently relax this assumption by numerically solving the slow-roll equations. Confrontation with the latest constraints from Planck 2018, ACT DR6, DESI DR1, and BICEP/Keck shows that Higgs-like inflation in gravity is fully consistent with current bounds, naturally accommodating the preferred shift in the scalar spectral index and leading to distinctive tensor-sector signatures.
Tomohiro Fujita🇯🇵 · Tomo Takahashi🇯🇵 · Sora Yamashita🇯🇵
We develop an effective theory for biased tracers formulated at the level of the Boltzmann equation, providing a unified description of density and velocity bias. We introduce a general effective collision term in the tracer Boltzmann equation to encode tracer dynamics that are intrinsically different from those of dark matter. This collision operator leads to modified continuity and Euler equations, with source terms reflecting the collision-term physics. At linear order, this framework predicts time- and scale-dependent bias parameters in a self-consistent manner, encompassing peak bias as a special case while clarifying how velocity bias and higher-derivative effects arise. Applying the resulting bias model to redshift-space distortions, we show that the Boltzmann-equation approach reproduces the power spectrum of biased tracers obtained in the Effective Field Theory of Large-Scale Structure up to terms with fewer independent parameters.
Narasimha Reddy Gosala🇨🇦 · Arundhati Dasgupta🇨🇦
Quark-Gluon Plasma (QGP), a strongly interacting state of the early universe, exhibits remarkably fluid-like behavior despite its underlying non-Abelian dynamics. Motivated by these features, we explore time-dependent SU(2) Yang-Mills condensates as non-linear classical background fields to model QGP. We first study quarks in gluon backgrounds and show that quark back-reaction can break the isotropy of the condensate for certain initial conditions. We then compute the one-loop finite-temperature effective action using the background-field method and heat-kernel expansion. The resulting thermodynamic pressure increases with temperature but exhibits an approximately logarithmic dependence. This is expected, as this is the de-confined phase of QGP; it is not exactly an ideal gas due to self-interaction. We also perform lattice calculations for the system to contrast continuum and lattice perspectives. We then add the GW to the thermodynamic QGP model and show that certain frequencies of the GW can induce instabilities in the QGP. Our analysis explores the limitations and role of non-perturbative, time-dependent backgrounds in semi-classical description of Yang-Mills dynamics.
We investigate the -wave scattering up to next-to-leading order within a renormalizable framework of covariant chiral effective field theory. Using time-ordered perturbation theory, the scattering amplitude is obtained by treating the leading-order interaction non-perturbatively and including the higher-order corrections perturbatively via the subtractive renormalization. We demonstrate that the non-perturbative treatment is essential, at least at lowest order, in the SU(3) sector of scattering. Our NLO study achieves a good description of the empirical -wave phase shifts in the isospin channel. An analysis of the effective range expansion yields a negative effective range, consistent with some partial wave analyses but opposite in sign to earlier phenomenological summaries. For the counterpart, the interaction is found to be rather weak and exhibits large uncertainties. Further low-energy scattering experiments and lattice QCD simulations are needed to better constrain both -wave channels.
In this work, we compute quantum discord between two causally independent areas in dimensions global de Sitter Axiverse to investigate the signs of quantum entanglement. For this goal, we study a bipartite quantum field theoretic setting driven by an Axiverse that arises from the compactification of Type IIB strings on a Calabi-Yau three fold. We consider a spherical surface that separates the interior and exterior causally unconnected subregions of the spatial slice of the global de Sitter space. The Bunch-Davies state is the most straightforward initial quantum vacuum that may be used for computing purposes. Two observers are introduced, one in an open chart of de Sitter space and the other in a global chart. The observers calculate the quantum discord generated by each detecting a mode. The relationship between an observer in one of the two Rindler charts in flat space and another in a Minkowski chart is comparable to this circumstance. We see that when the curvature of the open chart increases, the state becomes less entangled. Nevertheless, we see that even in the limit when entanglement vanishes, the quantum discord never goes away.
Zi-Qiang Zhao🇨🇳 · Zhang-Yu Nie🇨🇳 · Xing-Kun Zhang🇺🇸 · Yu-Sen An🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang
We investigate the oscillation of the Kasner exponent near critical point of the hairy black holes dual to holographic superfluid and reveal a clear inverse periodicity in a large region below the critical temperature. We first introduce the fourth-power term with a coefficient to adjust the oscillatory behavior of the Kasner exponent near the critical point. Importantly, we show that the nonlinear coefficient provides accurate control of this periodicity: a positive stretches the region, while a negative compresses it. By contrast, the influence of another coefficient is more concentrated in regions away from the critical point. This work provides a new perspective for understanding the complex dynamical structure inside black holes and extends the actively control from the fourth- and sixth-power term into the black hole interior region.
Zheyan Wan🇨🇳 · Juven Wang🇬🇧
Discrete finite-group global symmetries may suffer from nonperturbative 't-Hooft anomalies. Such global anomalies can be canceled by anomalous symmetry-preserving topological quantum field theories (TQFTs), which contain no local point operators but only extended excitations such as line and surface operators. In this work, we study mixed gauge-gravitational nonperturbative global anomalies of Weyl fermions (or Weyl semimetals in condensed matter) charged under discrete Abelian internal symmetries in four-dimensional spacetime, with spacetime-internal fermionic symmetry Spin or Spin that contains fermion parity . We determine the minimal finite gauge group of anomalous -symmetric TQFTs that can match the fermionic anomaly via the symmetry-extension construction , where the anomaly in is trivialized upon pullback to , computed by Atiyah-Patodi-Singer eta invariant. This allows one to replace a -symmetric four-dimensional Weyl fermion by an anomalous -symmetric discrete--gauge TQFT as an alternative low-energy theory in the same deformation class. As an application, we show that the four-dimensional Standard Model with 15 Weyl fermions per family, in the absence of a sterile right-handed neutrino , exhibits mixed gauge-gravitational global anomalies between baryon and lepton number symmetries and spacetime diffeomorphisms. We identify the corresponding minimal -gauge fermionic TQFT that cancels these anomalies and can be interpreted as a gapped, topologically ordered dark sector replacing missing Weyl fermions via symmetry extension, without invoking conventional Anderson-Higgs symmetry breaking.
* 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.