HEP Phenomenology·hep-ph

Thu·Dec 19, 2024Thursday·December 19, 2024

57 papers—40 primary·17 cross-listed·reconstructed*

01*
HQET sum rules for matrix elements of dimension-six four-quark operators for meson lifetimes within and beyond the Standard Model
Matthew Black🇩🇪 · Martin Lang🇩🇪 · Alexander Lenz🇩🇪 · Zachary Wüthrich🇩🇪
Theory predictions of heavy-hadron lifetime ratios critically depend on precise determinations of the dimension-six spectator effects arising from the double insertion of the weak effective $∣Δ B ∣ = 1$ Hamiltonian. In the presence of beyond-standard-model (BSM) operators, the resulting $Δ B = 0$ Hamiltonian features additional four-quark operators whose matrix elements need to be determined using non-perturbative methods. We present for the first time results for the non-perturbative hadronic matrix elements of the four-quark operators relevant for the description of the meson lifetime ratio $τ (B^{+}) / τ (B_{d})$ , obtained using heavy-quark effective theory (HQET) sum rules with the full BSM effective Hamiltonian. In addition, we recompute and update the bag parameters for the Standard Model operators.
hep-phJHEP(2025)·13 citations
02*
On T-Invariance Violation in Neutrino Oscillations and Matter Effects
Olivia M. Bitter🇺🇸 · André de Gouvêa🇺🇸 · Kevin J. Kelly🇺🇸
We investigate the impact of matter effects on T (time-reversal)-odd observables, making use of the quantum-mechanical formalism of neutrino-flavor evolution. We attempt to be comprehensive and pedagogical. Matter-induced T-invariance violation (TV) is qualitatively different from, and more subtle than, matter-induced CP (charge-parity)-invariance violation. If the matter distribution is symmetric relative to the neutrino production and detection points, matter effects will not introduce any new TV. However, if there is intrinsic TV, matter effects can modify the size of the T-odd observable. On the other hand, if the matter distribution is not symmetric, there is genuine matter-induced TV. For Earth-bound long-baseline oscillation experiments, these effects are small. This remains true for unrealistically-asymmetric matter potentials (for example, we investigate the effects of ''hollowing out'' 50% of the DUNE neutrino trajectory). More broadly, we explore consequences, or lack thereof, of asymmetric matter potentials on oscillation probabilities. While fascinating in their own right, T-odd observables are currently of limited practical use, due in no small part to a dearth of intense, well-characterized, high-energy electron-neutrino beams. Further in the future, however, intense, high-energy muon storage rings might become available and allow for realistic studies of T invariance in neutrino oscillations.
hep-phhep-exPRD(2025)·2 citations
03*
Aspects of Gravitational Portals and Freeze-in during Reheating
Stephen E. Henrich🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸
We conduct a systematic investigation of freeze-in during reheating while taking care to include both direct and indirect production of dark matter (DM) via gravitational portals and inflaton decay. Direct production of DM can occur via gravitational scattering of the inflaton, while indirect production occurs through scattering in the Standard Model radiation bath. We consider two main contributions to the radiation bath during reheating. The first, which may dominate at the onset of the reheating process, is produced via gravitational scattering of the inflaton. The second (and more standard contribution) comes from inflaton decay. We consider a broad class of DM production rates parameterized as $R_{χ} \propto T^{n + 6} / Λ^{n + 2}$ , and inflaton potentials with a power-law form $V (ϕ) \propto ϕ^{k}$ about the minimum. We find the relic density produced by freeze-in for each contribution to the Standard Model bath for arbitrary $k$ and $n$ , and compare these with the DM density produced gravitationally by inflaton scattering. We find that freeze-in production from the gravitationally-produced radiation bath can exceed that of the conventional decay bath and account for the observed relic density provided that $m_{χ} > T_{RH}$ , with additional $k$ - and $n$ -dependent constraints. For each freeze-in interaction considered, we also find $m_{χ}$ - and $T_{RH}$ -dependent limits on the BSM scale, $Λ$ , for which gravitational production will exceed ordinary freeze-in production.
hep-phastro-ph.COPRD(2025)·17 citations
04*
New Physics at the Muon (Synchrotron) Ion Collider: MuSIC for several scales
Hooman Davoudiasl🇺🇸 · Hongkai Liu🇮🇱 · Roman Marcarelli🇺🇸 · Yotam Soreq🇮🇱 · Sokratis Trifinopoulos🇺🇸
A Muon (Synchrotron) Ion Collider (MuSIC) can be the successor to the Electron-Ion Collider at Brookhaven National Laboratory, as well as the ideal demonstrator facility for a future multi-TeV Muon Collider. Besides its rich nuclear physics and Standard Model particle physics programs, in this work we show that the MuSIC with a TeV-scale muon beam offers also a unique opportunity to probe New Physics. In particular, the relevant searches have the potential to surpass current experimental limits and explore new regimes of the parameter space for a variety of Beyond the Standard Model scenarios including: lepton-flavor violating leptoquarks, muonphilic vector boson interactions, axion-like particles coupling to photons, and heavy sterile neutrinos. Depending on the particular case, the sensitivity of the searches in the MuSIC may span a wide range of energy scales, namely from sub-GeV particles to the few TeV New Physics mediators. Our analysis demonstrates that the MuSIC can strike a powerful chord in the search for New Physics, thanks to unique combination of features that amplify its capabilities.
hep-phhep-exJHEP(2025)·11 citations
05*
Dark Matter Escaping Direct Detection Runs into Higgs Mass Hierarchy Problem
Praveen Bharadwaj🇮🇳 · Ranjeet Kumar🇮🇳 · Hemant Kumar Prajapati🇮🇳 · Rahul Srivastava🇮🇳 · Sushant Yadav🇮🇳
The current generation of Dark Matter Direct Detection Experiments has ruled out a large region of parameter space for dark matter, particularly in the ( $10 - 1000$ ) GeV mass range. However, due to very low event rates, searching for dark matter in the heavy mass range, $O$ (TeV), is a daunting task requiring even larger volume detectors and long exposure times. We show that for a broad class of dark matter models of the type that these experiments are searching, including some of the most popular candidates, the heavy dark matter mass range can be ruled out in its entirety once we take into account the large corrections to Higgs mass imparted by such heavy dark matter. We show that such a limit is applicable to all types of dark matter i.e. scalar, vector, and fermionic, provided they couple directly with Higgs. By taking some simple and well studied dark matter models we show that the latest LZ limits can completely rule out such a dark matter except in a narrow range around $M_{h} /2$ mass.
hep-phastro-ph.COastro-ph.HEhep-ex8 citations
06*
Unpolarized valence GPDs and form factors of pion in the modified chiral quark model
H. Nematollahi🇮🇷 · K. Azizi🇮🇷
We calculate the valence generalized parton distribution functions (GPDs) of pion at zero skewness applying a theoretical approach in which the valence GPDs are related to valence quark distribution functions, directly. To this end, we use the results of modified chiral quark model ( $χ QM$ ) for the valence quark distributions of pion obtained in our previous work. We also determine the electromagnetic and gravitational form factors of pion and compare the results of our theoretical model for valence GPDs and form factors of pion with the results of some other models and available experimental data.
hep-phhep-exhep-latPRD(2025)·4 citations
07*
Neutrino nucleus Quasi-Elastic and resonant Neutral Current scatterings with Non-Standard Interactions
Saeed Abbaslu🇮🇷 · Mehran Dehpour🇨🇿 · Yasaman Farzan🇮🇷 · Sahar Safari🇩🇪
As well known, the cross sections of the resonance and Quasi-Elastic (QE) scattering off nucleons depend on quantities known as form factors that describe the nucleon structure. There are alternative approaches to determine the values of these non-perturbative quantities, some of them relying on the Neutral Current (NC) scattering of neutrinos off nucleons. In the presence of NC Non-Standard Interactions (NSI), such derivations must be revisited. The aim of the present paper is to discuss how information on NSI can be extracted by combining alternative approaches for deriving the form factors. We discuss how the KamLAND atmospheric neutrino data with $E_{ν} < GeV$ (used to determine the axial strange form factor $g_{A}^{s}$ ) can already constrain the axial NSI of $ν_{τ}$ with nucleons. We also argue that if the precision measurement of $ν_{μ}$ NC QE scattering establishes unexpectedly large vector strange form factor ({\it e.g.,} $F_{1}^{s} (Q^{2}) \sim 0.01$ ), it will be an indication for nonzero NSI coupling with $u$ and $d$ quarks ( $ϵ_{μμ}^{A u / d} \sim 0.01$ ). We study the QE and resonance scattering cross sections of $ν_{τ}$ and $ν_{e}$ off Argon and show that if their axial NSI is of the order of (but of course below) the present bounds, the deviation of QE cross sections from the SM prediction will be sizable and distinct from the uncertainties induced by the form factors.
hep-phnucl-thJHEP(2025)·7 citations
08*
Kernel methods for evolution of generalized parton distributions
A. Freese🇺🇸 · D. Adamiak🇺🇸 · I. Cloët🇺🇸 · W. Melnitchouk🇺🇸 · J.-W. Qiu🇺🇸 · N. Sato🇺🇸 · M. Zaccheddu🇺🇸
Generalized parton distributions (GPDs) characterize the 3-dimensional structure of hadrons, combining information about their internal quark and gluon longitudinal momentum distributions and transverse position within the hadron. The dependence of GPDs on the factorization scale $Q^{2}$ allows one to connect hard exclusive processes involving GPDs at disparate energy and momentum scales, which is needed in global analyses of experimental data. In this work we explore how finite element methods can be used to construct fast and differentiable $Q^{2}$ evolution codes for GPDs in momentum space, which can be used in a machine learning framework. We show numerical benchmarks of the methods' accuracy, including a comparison to an existing evolution code from PARTONS/APFEL++, and provide a repository where the code can be accessed.
hep-phhep-exhep-latnucl-thComput.Phys.Commun.(2025)·8 citations
09*
Decoding spin-parity quantum numbers and decay widths of double $J / ψ$ exotic states
Kaiwen Chen🇨🇳 · Feng-Xiao Liu🇨🇳 · Qiang Zhao🇨🇳 · Xian-Hui Zhong🇨🇳 · Ruilin Zhu🇨🇳 · Bing-Song Zou🇨🇳
We derive helicity amplitudes for the fully charmed tetraquark states decays into vector meson pair under two types of models, where the one is from quark model and the other one is from diquark model. The decay angular distributions have been given by the cascade decays $T_{4 c} \to J / ψ (D_{(s)}^{*}) + J / ψ (D ˉ_{(s)}^{*})$ along with $J / ψ \to μ^{+} + μ^{-}$ or $D_{(s)}^{*} \to D_{(s)} + π$ , showing that spin-0 and spin-2 states can be distinguished. We also find that the spin-0 state decay to $J / ψ$ -pair exhibits a higher degree of quantum entanglement than that in spin-2 state decays. These findings will assist in experimentally differentiating various spin-parity states, determining decay widths and unveiling undiscovered hadronic states within existing structures, thereby shedding light on the internal properties of double $J / ψ$ exotic states.
hep-phhep-exhep-lat11 citations
10*
A simple way to reduce the number of contours in the multi-fold Mellin-Barnes integrals
Mauricio Diaz🇨🇱 · Ivan Gonzalez🇨🇱 · Igor Kondrashuk🇨🇱 · Eduardo A. Notte-Cuello🇨🇱
Mellin-Barnes integral representation of one-loop off-shell box massless diagram is five-fold by construction. On the other hand, it is known from the year 1992 that it may be reduced to certain two-fold Mellin-Barnes integral. We propose a way to reduce the number of the Mellin-Barnes integration contours from five to two by using the Mellin-Barnes integral representation only in combination with basic methods of mathematical analysis such as analytical regularization. We do not use any Barnes lemma to prove the reduction but we use the integral Cauchy formula instead. We recover first the well-known two-fold Mellin-Barnes representation for the one-loop triangle massless diagram and then show how the five-fold Mellin-Barnes integral representation of one-loop box diagram with all the indices 1 in four spacetime dimensions may be reduced to the two-fold Mellin-Barnes representation for one-loop triangle diagram. Singular integrals over Feynman parameters appear in the integrand of the five-fold Mellin-Barnes integral representation at the intermediate step. Such integrals should be treated as distributions with respect to certain linear combinations of the initial Mellin-Barnes integration variables in the Mellin-Barnes integrands. These distributions may be integrated out with a finite number of residues in the limit of removing the analytical regularization. We explain how to apply this strategy to an arbitrary Feynman diagram in order to reduce the number of Mellin-Barnes integration contours. On the practical side, we analyze connections between the obtained results and the knot theory, Trotter integrals, quantum computing.
hep-phmath-phmath.MP4 citations
11*
The Baryon-Baryon Interaction in the Large- $N_{c}$ Limit
Thomas Vonk🇩🇪 · Ulf-G. Meißner🇩🇪
We analyze the large- $N_{c}$ structure of the baryon-baryon potential derived in the framework of SU(3) chiral perturbation theory up to next-to-leading order including contact interactions as well as one-meson and two-meson exchange diagrams. Moreover, we assess the impact of SU(3) symmetry breaking from a large- $N_{c}$ perspective and show that the leading order results can successfully be applied to the hyperon-nucleon potential. Our results include a reduction of the number of relevant low-energy constants of the leading order contact interaction from fifteen to three, and we show that consistency is preserved if the $F / D$ ratio is given by $2/3$ and the $C / D$ ratio for the baryon decuplet-to-octet coupling is given by 2.
hep-phhep-lathep-thnucl-thEPJA(2025)·6 citations
12*
Taming flavour violation in the Inverse Seesaw
Jonathan Kriewald🇸🇮 · Ana M. Teixeira🇫🇷
The Inverse Seesaw mechanism remains one of the most attractive explanations for the lightness of neutrino masses, allowing for natural low-scale realisations. We consider the prospects of a simple extension via 3 generations of sterile fermions - the so called ISS(3,3) - in what concerns numerous lepton flavour observables. In order to facilitate a connection between the Lagrangian parameters and low-energy data, we systematically develop new parametrisations of the Yukawa couplings. Relying on these new parametrisations to explore the parameter space, we discuss the complementary role of charged lepton flavour violation searches in dedicated facilities, as well as in lepton colliders (FCC-ee and $μ$ TRISTAN). Our results reveal the strong synergy of the different indirect searches in probing the distinct flavour sectors of the model. In particular, we show that in the absence of radiative decays $ℓ_{α} \to ℓ_{β} γ$ , sizeable rates for $Z$ -penguin dominated observables could hint at a non-trivially mixed and non-degenerate heavy spectrum.
hep-phhep-exJHEP(2025)·5 citations
13*
$e^{+} e^{-} \to μ^{+} μ^{-}$ in the Asymptotically Safe Standard Model
Álvaro Pastor-Gutiérrez🇩🇪 · Jan M. Pawlowski🇩🇪 · Manuel Reichert🇬🇧 · Giacomo Ruisi🇩🇪
We study the electron-positron to muon--anti-muon cross-section in the asymptotically safe Standard Model. In particular, we include the graviton contributions to the scattering amplitude, which is computed from momentum-dependent timelike one-particle-irreducible correlation functions. Specifically, we employ reconstruction techniques for the graviton spectral functions. We find that the full asymptotically safe quantum cross section decreases in the ultraviolet with the centre-of-mass energy, and is compatible with unitarity bounds. Importantly, our findings provide non-trivial evidence for the unitarity of the asymptotically safe Standard Model.
hep-phgr-qchep-thPRD(2025)·24 citations
14*
Minimal extension of the Standard Model with a mirror symmetry between fundamental fermions and a possible origin of dark matter
Jakub Rembieliński🇵🇱
In this paper, we propose a specific, nontrivial extension of the Standard Model of weak interactions based on the $S U (2)_{L} \times U (1)_{Y} \times U (1)_{C}$ group. Our motivation follows from the identification of the globally conserved charge $Ω = B - L - Q$ as a neutrino charge. An intriguing feature of the model is the emergence of a mirror symmetry between neutrinos and electrically charged leptons, as well as between up and down quarks. Following the spontaneous breaking of the weak gauge symmetry with the use of the Goldstone-Higgs iso-doublet, all elementary fermions acquire Dirac masses from Yukawa interaction. The $W^{\pm}$ and $Z$ bosons also acquire masses, although with a modified relationship between their respective masses, as compared to the Standard Model. Our model accounts for both chiral components of the neutrino and offers an explanation for the non-observability of the right-chiral neutrino. Additionally, it forbids neutrinoless double-beta decay. Spontaneous breaking of the local $U (1)$ symmetry leads to the new gauge boson $Ω_{μ}$ mass $M_{Ω}$ , which we assume to be greater than the mass $m_{χ}$ of a new scalar, Higgs-like field $χ$ . The cosmological stability of $χ$ , predicted under this condition, allows for its interpretation as dark matter, interacting exclusively with $Ω_{μ}$ and gravity. From this perspective, we solve and analyze a system of Boltzmann equations that describe the thermal evolution of the number density of $χ$ dark matter and the $Ω_{μ}$ mediator field within the context of the $ΛCDM$ cosmological model. Specifically, we estimate the coupling constant $q$ to be in the range of $\sim 1 0^{- 8.5} g$ to $\sim 1 0^{- 6} g$ which ensures cosmological stability of the $χ$ particles.
hep-phgr-qc0 citations
15*
Numerical evaluation of two-loop QCD helicity amplitudes for $g g \to t t ˉ g$ at leading colour
Simon Badger🇮🇹 · Matteo Becchetti🇮🇹 · Colomba Brancaccio🇮🇹 · Heribertus Bayu Hartanto🇰🇷 · Simone Zoia🇨🇭
We present the first benchmark evaluation of the two-loop finite remainders for the production of a top-quark pair in association with a jet at hadron colliders in the gluon channel. We work in the leading colour approximation, and perform the numerical evaluation in the physical phase space. To achieve this result, we develop a new method for expressing the master integrals in terms of a (over-complete) basis of special functions that enables the infrared and ultraviolet poles to be cancelled analytically despite the presence of elliptic Feynman integrals. The special function basis makes it manifest that the elliptic functions appear solely in the finite remainder, and can be evaluated numerically through generalised series expansions. The helicity amplitudes are constructed using four dimensional projectors combined with finite-field techniques to perform integration-by-parts reduction, mapping to special functions and Laurent expansion in the dimensional regularisation parameter.
hep-phhep-thJHEP(2025)·25 citations
16*
Q-ball perturbations with more details: linear analysis vs lattice
Aleksandr Azatov🇮🇹 · Quoc Trung Ho🇮🇹 · Mohamed Mahdi Khalil🇮🇹
We analyze in detail the interactions between non-topological soliton (Q-ball) and its perturbations. We extend the previous literature by carefully identifying the domain of applicability of linear analysis as well discussion of the FLS Q-balls. Applications to the early universe physics are briefly commented.
hep-phPRD(2025)·7 citations
17*
Notes on recasting the ATLAS-EXOT-2019-23 search for pairs of displaced hadronic jets in the ATLAS calorimeter
Louie Corpe🇫🇷 · Thomas Chehab🇫🇷 · Andreas Goudelis🇫🇷
This note describes the validation of material allowing the reinterpretation of an ATLAS search for decays of pair-produced neutral long-lived particles decaying in the hadronic part of the calorimeter, or at the edge of the electromagnetic calorimeter, using the full Run-2 ATLAS dataset. This reinterpretation material includes an efficiency map linking truth-level kinematic information (decay position, transverse momentum and decay products of the LLPs) to the probability of the reconstructed event being selected in the analysis signal region. In this document we describe the validation procedure, i.e. how the map was used to recover the limits presented in the ATLAS publication using events generated with MadGraph5_aMC@NLO and hadronised using Pythia8, and we identify some limitations of this approach. We moreover comment upon issues concerning the validation procedure itself, in particular with regards to whether or not the information included in the existing, published material allows for an external user to test recasting methods.
hep-phhep-ex0 citations
18*
LeStrat-Net: Lebesgue style stratification for Monte Carlo simulations powered by machine learning
Kayoung Ban🇰🇷 · Myeonghun Park🇰🇷 · Raymundo Ramos🇰🇷
We develop a machine learning algorithm to turn around stratification in Monte Carlo sampling. We use a different way to divide the domain space of the integrand, based on the height of the function being sampled, similar to what is done in Lebesgue integration. This means that isocontours of the function define regions that can have any shape depending on the behavior of the function. We take advantage of the capacity of neural networks to learn complicated functions in order to predict these complicated divisions and preclassify large samples of the domain space. From this preclassification we can select the required number of points to perform a number of tasks such as variance reduction, integration and even event selection. The network ultimately defines the regions with what it learned and is also used to calculate the multi-dimensional volume of each region.
hep-phcs.LGComput.Phys.Commun.(2026)·1 citation
19*
Triple real-emission contribution to the zero-jettiness soft function at N3LO in QCD
Daniel Baranowski🇨🇭 · Maximilian Delto🇩🇪 · Kirill Melnikov🇩🇪 · Andrey Pikelner🇩🇪 · Chen-Yu Wang🇩🇪
Recently, we have presented the result for the zero-jettiness soft function at next-to-next-to-next-to-leading order (N3LO) in perturbative QCD [arXiv:2409.11042], without providing technical details of the calculation. The goal of this paper is to describe the most important element of that computation, the triple real-emission contribution. We present a detailed discussion of the many technical aspects of the calculation, for which a number of methodological innovations was required. Although some elements of the calculation were discussed earlier [arXiv:2004.03285,arXiv:2206.12323,arXiv:2111.13594,arXiv:2204.09459,arXiv:2401.05245], this paper is intended to provide a complete summary of the methods used in the computation of the triple real-emission contribution to the soft function.
hep-phJHEP(2025)·13 citations
20*
Total decay rates of $B$ mesons at NNLO-QCD
Manuel Egner🇩🇪 · Matteo Fael🇮🇹 · Alexander Lenz🇩🇪 · Maria Laura Piscopo🇩🇪 · Aleksey V. Rusov🇩🇪 · Kay Schönwald🇨🇭 · Matthias Steinhauser🇩🇪
We update the Standard Model (SM) predictions for the lifetimes of the $B^{+}$ , $B_{d}$ and $B_{s}$ mesons within the heavy quark expansion (HQE), including the recently determined NNLO-QCD corrections to non-leptonic decays of the free $b$ -quark. In addition, we update the HQE predictions for the lifetime ratios $τ (B^{+}) / τ (B_{d})$ and $τ (B_{s}) / τ (B_{d})$ , and provide new results for the semileptonic branching fractions of the three mesons entirely within the HQE. We obtain a considerable improvement of the theoretical uncertainties, mostly due to the reduction of the renormalisation scale dependence when going from LO to NNLO, and for all the observables considered, we find good agreement, within uncertainties, between the HQE predictions and the corresponding experimental data. Our results read, respectively, $Γ (B^{+}) = 0.58 7_{- 0.035}^{+ 0.025} ps^{- 1}$ , $Γ (B_{d}) = 0.63 6_{- 0.037}^{+ 0.028} ps^{- 1}$ , $Γ (B_{s}) = 0.62 8_{- 0.035}^{+ 0.027} ps^{- 1}$ , for the total decay widths, $τ (B^{+}) / τ (B_{d}) = 1.08 1_{- 0.016}^{+ 0.014}$ , $τ (B_{s}) / τ (B_{d}) = 1.01 3_{- 0.007}^{+ 0.007}$ , for the lifetime ratios, and $B_{sl} (B^{+}) = (11.4 6_{- 0.32}^{+ 0.47}) %$ , $B_{sl} (B_{d}) = (10.5 7_{- 0.27}^{+ 0.47}) %$ , $B_{sl} (B_{s}) = (10.5 2_{- 0.29}^{+ 0.50}) %$ , for the semileptonic branching ratios. Finally, we also provide an outlook for further improvements of the HQE determinations of the $B$ -meson decay widths and of their ratios.
hep-phhep-exJHEP(2025)·17 citations
21*
What can we learn from the Parton Branching method in QCD?
S. Taheri Monfared🇩🇪
This work reviews recent developments in the Parton Branching (PB) method, focusing on its application to Transverse Momentum Dependent (TMD) parton distributions and the implementation of TMD evolution equations in Monte Carlo generators. Key advancements include the inclusion of photon and heavy electroweak boson radiation in the evolution equations and their impact on collinear and TMD distributions. A detailed comparison of PB and Collins-Soper-Sterman formalisms highlights improvements in the accuracy of PB Sudakov form factors. The role of soft gluons, intrinsic transverse momentum, and the $z_{M}$ parameter in modelling non-perturbative effects is emphasized, with implications for inclusive distributions and Drell-Yan transverse momentum spectra. This review also addresses challenges in achieving consistency between forward and backward evolution.
hep-ph1 citation
22*
Freeze-in leptogenesis with sterile neutrino self-interactions
Maria Dias Astros🇩🇪 · Stefan Vogl🇩🇪
Sterile neutrinos are a simple yet compelling addition to the Standard Model. For right-handed neutrinos with masses below the electroweak scale, leptogenesis can proceed through CP-violating oscillations of the sterile neutrinos. This is known as ARS or freeze-in leptogenesis. However, the ARS scenario requires the right-handed neutrinos to have a high degree of mass degeneracy. In this work, we study an extension of the SM that introduces a scalar singlet in addition to the two sterile neutrinos required to generate the baryon asymmetry. The new scalar interacts with the sterile neutrinos via a Yukawa interaction. This leads to an additional rate for the production and destruction of the sterile neutrinos and to a novel contribution to the effective potential. For the case in which the mass and the new Yukawa matrices are not diagonal in the same basis, we find that the effective potential can boost the baryon asymmetry of the universe by several orders of magnitude. This significantly alleviates the fine-tuned mass condition required in vanilla ARS leptogenesis.
hep-phJHEP(2025)·1 citation
23*
The Neutrino Slice at Muon Colliders
Luc Bojorquez-Lopez🇺🇸 · Matheus Hostert🇺🇸 · Carlos A. Argüelles🇺🇸 · Zhen Liu🇺🇸
Muon colliders provide an exciting new direction to expand the energy frontier of particle physics. We point out a new use of these facilities for neutrino and beyond the Standard Model physics using their main detectors. Muon decays along the accelerator rings create an intense and highly collimated neutrino beam that crosses a thin slice of the kt-scale detector. As a result, it would induce an unprecedented number of neutrino interactions, with $O (1 0^{4})$ events per second for a 10 TeV $μ^{+} μ^{-}$ collider. These interactions are highly energetic and possess a distinct timing signature and a large transverse displacement. We discuss promising applications of these events for instrumentation, electroweak, and beyond-the-Standard Model physics. For instance, a sub-percent measurement of the neutrino-electron scattering rate enables new precision measurements of the Weak angle and a novel detection of the neutrino charge radius.
hep-phhep-exPRL(2025)·11 citations
24*
Leptogenesis with Majoron Dark Matter
Stephen F. King🇬🇧 · Soumen Kumar Manna🇮🇳 · Rishav Roshan🇬🇧 · Arunansu Sil🇮🇳
We discuss a model of neutrino mass based on the type I seesaw mechanism embedded in a spontaneously broken global lepton number framework with a $Z_{2}$ symmetry. We show that the resulting Majoron is a viable freeze-in dark matter candidate. Two right-handed neutrinos are assumed to have dominant off-diagonal masses suggesting resonant leptogenesis as the origin of baryon asymmetry of the Universe. Explicit higher dimensional lepton number violating operators, are shown to play a crucial role in simultaneously controlling both the Majoron production in the early Universe and the right handed neutrino mass splitting relevant for resonant leptogenesis. We perform a combined analysis of Majoron dark matter and leptogenesis, discussing the relative importance of self energy and vertex contributions to CP asymmetry, and explore the parameter space, leading to an intricate relation between neutrino mass, dark matter and baryon asymmetry.
hep-phastro-ph.COPRD(2025)·9 citations
25*
$B_{c} \to η_{c}$ form factors at large recoil: Interplay of soft-quark and soft-gluon dynamics
Guido Bell🇩🇪 · Philipp Böer🇨🇭 · Thorsten Feldmann🇩🇪 · Dennis Horstmann🇩🇪 · Vladyslav Shtabovenko🇩🇪
We perform an all-order analysis of double-logarithmic corrections to the so-called soft-overlap contribution to heavy-to-light transition form factors at large hadronic recoil. Specifically, we study $B_{c} \to η_{c}$ transitions within a perturbative non-relativistic framework, treating both the bottom and charm quarks as heavy with the hierarchy $m_{b} ≫ m_{c} ≫ Λ_{QCD}$ . Our diagrammatic analysis shows that double-logarithmic corrections arise from two distinct sources: Exponentiated soft-gluon effects described by standard Sudakov factors, and rapidity-ordered soft-quark configurations, leading to implicit integral equations, which so far have only been studied in the context of energetic muon-electron backward scattering. We find that the all-order structure of the double logarithms is governed by a novel type of coupled integral equations, which encode the non-trivial interplay between these two effects. Whereas a closed-form solution to these equations is currently unknown, we present useful iteration formulas, and derive the asymptotic behaviour of the soft-overlap form factor for infinitely large recoil energies, showing that the Sudakov suppression is somewhat weakened by the intertwined soft-quark and soft-gluon corrections. In a broader context, our findings shed light onto the physical origin and mathematical structure of endpoint divergences arising from soft-collinear factorization and the related Feynman mechanism for power-suppressed hard exclusive processes.
hep-phJHEP(2025)·9 citations
26*
Small- $x$ Asymptotics of the Leading-Twist Flavor Singlet Quark TMDs
M. Gabriel Santiago🇺🇸 · Daniel Adamiak🇺🇸 · Yossathorn Tawabutr🇫🇮
In this paper, we investigate the small- $x$ behavior of the flavor-singlet, leading-twist quark Transverse Momentum Dependent parton distribution functions (TMDs) using the Light-Cone Operator Treatment. This formalism allows us to express TMD operators at small $x$ in terms of polarized dipole amplitudes, enabling a systematic approach to their small- $x$ evolution. We derive the evolution equations for these TMDs and solve them within the large- $N_{c}$ approximation under the linearized, Double-Logarithmic Approximation (DLA), where $N_{c}$ represents the number of quark colors. Expanding on previous work on unpolarized and helicity TMDs, we present the small- $x$ asymptotics for a comprehensive set of TMDs, including the Sivers function, helicity worm-gear, transversity, pretzelosity, Boer-Mulders, and transversity worm-gear distributions. Our results provide a complete picture of the small- $x$ asymptotic behavior for all leading-twist flavor-singlet quark TMDs. We also discuss the implications of our findings for phenomenological applications and outline potential avenues for further research, particularly in understanding non-linear effects and extending beyond the DLA and large- $N_{c}$ approximations.
hep-phnucl-thPRD(2026)·4 citations
27*
Towards the HEFT-hedron: the complete set of positivity constraints at NLO
Debsubhra Chakraborty🇮🇳 · Susobhan Chattopadhyay🇮🇳 · Rick S. Gupta🇮🇳
We present the complete set of positivity bounds on the Higgs Effective Field Theory (HEFT) at next-to-leading order (NLO). We identify the 15 operators that can be constrained by positivity, as they contribute to $s^{2}$ -growth in the amplitude for longitudinal gauge-Higgs scattering, that is to all possible 2-to-2 scattering processes involving longitudinal gauge bosons, $V_{L} = W_{L}^{\pm}, Z_{L}$ , and the Higgs boson, $h$ . We find two sets of constraints: (i) specific linear combinations of CP-even Wilson coefficients (WCs) must be positive, and (ii) the magnitudes of some WCs -- including all CP-odd ones -- must be smaller than products of other CP-even WCs. We present our final constraints on the 15 dimensional HEFT space and show how known positivity bounds on the 3 dimensional space of dimension 8 SMEFT can be recovered from them. We find that only about $5%$ of the parameter space for WCs of HEFT operators at NLO complies with these positivity constraints. Additionally, we obtain double-sided bounds on these WCs by fully exploiting the implications of unitarity and $s t$ -crossing symmetry. For WCs contributing to the vector boson scattering process our final constraints are in most cases significantly stronger than the experimental ones. For the $V_{L} V_{L}, hh \to hh$ and $V_{L} V_{L}, hh \to V_{L} h$ process, there are no reported experimental limits and our theoretical constraints provide the first bounds.
hep-phhep-exhep-thPRD(2026)·11 citations
28*
$2 ν β β$ Spectrum in Chiral Effective Field Theory
Saad el Morabit🇳🇱 · Ryan Bouabid🇺🇸 · Vincenzo Cirigliano🇺🇸 · Jordy de Vries🇳🇱 · Lukáš Gráf🇳🇱 · Emanuele Mereghetti🇺🇸
We investigate two-neutrino double beta decay ( $2 ν β β$ ) in chiral effective field theory. We find contributions from weak magnetism and double-weak pion-exchange at next-to-leading-order in the chiral power counting. We discuss the impact of the chiral corrections on the electron spectra and find that they should be included in analyses of $2 ν β β$ decay that aim to uncover new physics signatures in the electron spectrum. We illustrate this point by revisiting the effect of sterile neutrinos and non-standard charged interactions. We also find that the pion-exchange contributions involve nuclear matrix elements that are related to those appearing in neutrinoless double beta decay ( $0 ν β β$ ). We investigate whether the $0 ν β β$ nuclear matrix elements can be obtained from detailed measurements of the energy spectrum of the outgoing electrons in $2 ν β β$ transitions.
hep-phhep-exnucl-exnucl-thJHEP(2025)·13 citations
29*
On the EFT validity for Drell-Yan tails at the LHC
Lukas Allwicher🇩🇪 · Darius A. Faroughy🇺🇸 · Matheus Martines🇧🇷 · Olcyr Sumensari🇫🇷 · Felix Wilsch🇩🇪
In this article, we examine the validity range of the Effective Field Theory (EFT) description of high-energy Drell-Yan processes at the LHC. To this purpose, we consider explicit mediators that contribute to these processes in the $s$ - and $t$ -channels, comparing their effects in Drell-Yan distributions with the ones obtained by matching onto the corresponding EFT. We determine the conditions for the EFT results to accurately describe these scenarios. In particular, we explore the impact of including dimension-eight $(d = 8)$ operators in the faster convergence of the EFT series, at the analytical and numerical level, considering contributions to the cross section up to the square of $d = 8$ EFT operator insertions. Moreover, we discuss the possible implications of clipping LHC data and illustrate results for a specific New-Physics scenario motivated by low-energy flavor data.
hep-phEPJC(2025)·12 citations
30*
Fermion-Portal Dark Matter at a High-Energy Muon Collider
Pouya Asadi🇺🇸 · Samuel Homiller🇺🇸 · Aria Radick🇺🇸 · Tien-Tien Yu🇺🇸
In this work, we provide a comprehensive study of fermion-portal dark matter models in the freeze-in regime at a future muon collider. For different possible non-singlet fermion portals, we calculate the upper bound on the mediator's mass arising from the relic abundance calculation and discuss the reach of a future muon collider in probing their viable parameter space in prompt and long-lived particle search strategies. In particular, we develop rudimentary search strategies in the prompt region and show that cuts on the invariant dilepton or dijet masses, the missing transverse mass $M_{T 2}$ , pseudorapidity and energy of leptons or jets, and the opening angle between the lepton or the jet pair can be employed to subtract the Standard Model background. In the long-lived particle regime, we discuss the signals of each model and calculate their event counts. In this region, the lepton-(quark-)portal model signal consists of charged tracks ( $R$ -hadrons) that either decay in the detector to give rise to a displaced lepton (jet) signature, or are detector stable and give rise to heavy stable charged track signals. As a byproduct, a pipeline is developed for including the non-trivial parton distribution function of a muon component inside a muon beam; it is shown that this leads to non-trivial effects on the kinematic distributions and attainable significances. We also highlight phenomenological features of all models unique to a muon collider and hope our results, for this motivated and broad class of dark matter models, inform the design of a future muon collider detector. We also speculate on suggestions for improving the sensitivity of a muon collider detector to long-lived particle signals in fermion-portal models.
hep-phhep-exPRD(2025)·7 citations
31*
The Two Scales of New Physics in Loop-Induced Higgs Couplings
Florian Nortier🇫🇷 · Gabriele Rigo🇫🇷 · Pablo Sesma🇫🇷
Probing new physics through precise measurements of Higgs boson couplings is a central objective of the particle collider program at the high-energy frontier. An anomaly in Higgs couplings induced solely by new fermions allows one to compute an upper bound on the mass scale of new bosons. This new bosonic scale is necessary to prevent Landau poles or vacuum instability. Consequently, a single anomalous measurement can provide insight into two distinct new physics scales. In this article, we apply this approach to the loop-induced couplings of the Higgs boson to digluons ( $g g$ ), diphotons ( $γ γ$ ), and $Z γ$ , and we compare our results to the projected sensitivities of the HL-LHC and future lepton colliders. This work naturally extends our previous analysis of Higgs couplings to weak dibosons ( $W W$ and $Z Z$ ).
hep-phhep-exhep-thJHEP(2025)·2 citations
32*
Monopole Catalyzed Baryogenesis with a $θ$ angle
T. Daniel Brennan🇺🇸 · Lian-Tao Wang🇺🇸 · Huangyu Xiao🇺🇸
Monopoles are generally expected in Grand Unified Theories (GUTs) where they can catalyze baryon decay at an unsuppressed rate by the Callan-Rubakov effect. For the first time, we show this catalysis effect can generate the observed baryon asymmetry at GeV scale temperatures. We study the minimal SU(5) GUT model and demonstrate that monopoles-fermion scattering with a $C P$ -violating $θ$ -term leads to realistic baryogenesis even when $θ ≲ 1 0^{- 10}$ is below the neutron EDM bound, potentially detectable in the future measurements. Our calculation also shows that to generate the observed baryon asymmetry, the abundance of the monopoles is below the current experiential bounds.
hep-phhep-th5 citations
33*
Noble Dark Matter: Surprising Elusiveness of Dark Baryons
Pouya Asadi🇺🇸 · Austin Batz🇺🇸 · Graham D. Kribs🇺🇸
Dark matter could be a baryonic composite of strongly-coupled constituents transforming under SU(2) $_{L}$ . We classify the SU(2) $_{L}$ representations of baryons in a class of simple confining dark sectors and find that the lightest state can be a pure singlet or a singlet that mixes with other neutral components of SU(2) $_{L}$ representations, which strongly suppresses the dark matter candidate's interactions with the Standard Model. We focus on models with a confining $SU (N_{c})$ and heavy dark quarks constituting vector-like $N_{f}$ -plet of SU(2) $_{L}$ . For benchmark $N_{c}$ and $N_{f}$ , we calculate baryon mass spectra, incorporating electroweak gauge boson exchange in the non-relativistic quark model, and demonstrate that above TeV mass scales, dark matter is dominantly a singlet state. The combination of this singlet nature with the recently discovered $H$ -parity results in an inert state analogous to noble gases, hence we coin the term Noble Dark Matter. Our results can be understood in the non-relativistic effective theory that treats the dark baryons as elementary states, where we find singlets accompanying triplets, 5-plets, or more exotic representations. This generalization of WIMP-like theories is more difficult to find or rule out than dark matter models that include only a single SU(2) $_{L}$ multiplet (such as a Wino), motivating new searches in colliders and a re-analysis of direct and indirect detection prospects in astrophysical observations.
hep-phPRD(2025)·7 citations
34*
Accuracy complements energy: electroweak precision tests at Tera-Z
Victor Maura🇬🇧 · Ben A. Stefanek🇪🇸 · Tevong You🇬🇧
A Tera- $Z$ factory, such as FCC-ee or CEPC, will have indirect sensitivity to heavy new physics up to the tens of TeV scale through higher-order loop contributions to precision measurements at the $Z$ pole. These indirect quantum effects may provide complementary, or even better, sensitivity to potential deviations from the Standard Model that are typically thought to best be constrained at leading order at higher energies above the $Z$ pole. We show in the SMEFT framework how accuracy complements energy for operators that modify the Higgs and gauge boson two- and three-point functions, leading to improved projected sensitivities for models such as the real singlet scalar, weakly interacting massive particles, and a custodial weak quadruplet. A thorough Tera- $Z$ programme may thus anticipate aspects of physics runs at higher energies and provide a wider scope of quantum exploration of the TeV scale than had previously been appreciated.
hep-phhep-exJHEP(2025)·33 citations
35*
Matching Z $\to$ Hadrons at NNLO with Sector Showers
Basem Kamal El-Menoufi🇦🇺 · Christian T. Preuss🇩🇪 · Ludovic Scyboz🇦🇺 · Peter Skands🇦🇺
We present a detailed technical derivation of matching conditions at next-to-next-to-leading order in the sectorised VINCIA parton shower, by considering leading-colour 2-, 3- and 4-jet rates in hadronic Z-boson decays. In particular, we introduce a full subtraction-based calculation of the matching coefficient required to obtain the NLO 3-jet rate. This is achieved through a judicious choice of the counter-terms, which optimises the numerical evaluation of the subtracted double-real matrix element. We additionally give a consistent prescription for incorporating interference effects due to higher-order mixing between Born states with different flavour contents. Finally, we briefly comment on higher-order uncertainty estimates.
hep-phJHEP(2025)·7 citations
36*
A common origin of the Higgs boson and the flavor hierarchies
Javier M. Lizana🇪🇸
We present a model that extends the electroweak gauge symmetry of the Standard Model in a non-universal way to $S U (2)_{L}^{'} \times U (1)_{X} \times S U (2)_{L}^{q_{3}} \times S U (2)_{R}^{ℓ_{3}}$ . This symmetry is spontaneously broken to $S U (2)_{L} \times U (1)_{Y}$ near the TeV scale by a condensate of a new composite sector. Charging appropriately the fermionic degrees of freedom of the composite sector, anomaly cancellation enforces the Standard Model fermions to be charged in such a way that the extended gauge interactions respect a $U (2)_{q} \times U (2)_{e} \times U (3)_{u} \times U (3)_{d} \times U (3)_{ℓ}$ accidental flavor symmetry. In addition, from the same symmetry breaking, a composite Higgs boson emerges as a pseudo-Nambu-Goldstone boson of the strong dynamics of the new sector. Due to the extended gauge and the specific flavor symmetry, leading Yukawa couplings between Higgs and fermions can only be written for the third generation and higher dimension operators generate suppressed light-family Yukawa couplings. Furthermore, CKM mixing angles between third and light families are naturally suppressed while the PMNS ones, anarchic. The model thus provides a unified origin for the Higgs boson and the flavor hierarchies between third and light families.
hep-phJHEP(2025)·18 citations
37*
Secondary Lund jet plane as a gluon enriched sample
Cristian Baldenegro🇺🇸 · Alba Soto-Ontoso🇪🇸 · Gregory Soyez🇫🇷
We propose a new strategy to obtain a high-purity sample of gluon-initiated jets at the LHC. Our approach, inspired by the Lund jet plane picture, is to perform a dijet selection where the two jets are collinear to each other and their momentum fraction share is highly asymmetric, and to measure the primary Lund plane density of emissions of the subleading jet. The subleading jet in this topology is practically equivalent to a secondary Lund jet plane. We demonstrate by means of fixed-order calculations that such a simple setup yields gluon jet fractions of around 90% for the subleading jet for both quark- and gluon-initiated jets. This observation is confirmed using hadron-level Monte Carlo generated events. We also show that the extracted gluon purities are highly resilient to the overall colour structure of the event, to the flavour of the hard-scattering process, and to the parton distribution functions. This strategy is well-suited for constraining the radiation pattern of gluon-initiated jets using a set of fiducial cuts that can readily be tested at the LHC, without relying on taggers or statistical demixing.
hep-phhep-exnucl-thJHEP(2025)·5 citations
38*
From the EFT to the UV: the complete SMEFT one-loop dictionary
Guilherme Guedes🇩🇪 · Pablo Olgoso🇮🇹
Effective field theories (EFTs) provide an excellent framework for the search of heavy physics beyond the Standard Model, using the so-called bottom-up and top-down approaches. However, the vastness of possible UV scenarios makes the complete connection between the two approaches a difficult challenge at the loop-level. UV/IR dictionaries fill precisely this gap, efficiently connecting the EFT with the UV. In this work we present the complete one-loop dictionary for the Standard Model EFT at dimension six for completions with an arbitrary number of heavy fermions and scalars. Our results (as well as several new functionalities) are added to the previously partial package SOLD. In this new form, SOLD is prepared to serve as an important guiding tool for systematic and complete phenomenological studies. To illustrate this, we use the package to explore possible explanations for the tension on the measurement of $B (B \to K ν ν)$ .
hep-phSciPost Phys.(2026)·34 citations
39*
On the Interplay of Constraints from $B_{s}$ , $D$ , and $K$ Meson Mixing in $Z^{'}$ Models with Implications for $b \to s ν ν ˉ$ Transitions
Andrzej J. Buras🇩🇪 · Peter Stangl🇨🇭
Within $Z^{'}$ models, neutral meson mixing severely constrains beyond the Standard Model (SM) effects in flavour changing neutral current (FCNC) processes. However, in certain regions of the $Z^{'}$ parameter space, the contributions to meson mixing observables become negligibly small even for large $Z^{'}$ couplings. While this a priori allows for significant new physics (NP) effects in FCNC decays, we discuss how large $Z^{'}$ couplings in one neutral meson sector can generate effects in meson mixing observables of other neutral mesons, through correlations stemming from $SU(2)_{L}$ gauge invariance and through Renormalization Group (RG) effects in the SM Effective Field Theory (SMEFT). This is illustrated with the example of $B_{s}^{0} - B ˉ_{s}^{0}$ mixing, which in the presence of both left- and right-handed $Z^{'} b s$ couplings $Δ_{L}^{b s}$ and $Δ_{R}^{b s}$ remains SM-like for $Δ_{R}^{b s} \approx 0.1 Δ_{L}^{b s}$ . We show that in this case, large $Z^{'} b s$ couplings generate effects in $D$ and $K$ meson mixing observables, but that the $D$ and $K$ mixing constraints and the relation between $Δ_{R}^{b s}$ and $Δ_{L}^{b s}$ are fully compatible with a lepton flavour universality (LFU) conserving explanation of the most recent $b \to s ℓ^{+} ℓ^{-}$ experimental data without violating other constraints like $e^{+} e^{-} \to ℓ^{+} ℓ^{-}$ scattering. Assuming LFU, invariance under the $SU(2)_{L}$ gauge symmetry leads then to correlated effects in $b \to s ν ν ˉ$ observables presently studied intensively by the Belle II experiment, which allow to probe the $Z^{'}$ parameter space that is opened up by the vanishing NP contributions to $B_{s}^{0} - B ˉ_{s}^{0}$ mixing. In this scenario the suppression of $B \to K (K^{*}) μ^{+} μ^{-}$ branching ratios implies uniquely enhancements of $B \to K (K^{*}) ν ν ˉ$ branching ratios up to $20%$ .
hep-phhep-exhep-latEPJC(2025)·20 citations
40*
Quantum entropy and QCD factorization for low- $Q^{2}$ $ν$ DIS
Henry Bloss🇺🇸 · Brandon Kriesten🇺🇸 · T. J. Hobbs🇺🇸
Deeply inelastic scattering (DIS) is an essential process for exploring the structure of visible matter and testing the standard model. At the same time, the theoretical interpretation of DIS measurements depends on QCD factorization theorems whose validity deteriorates at the lower values of $Q^{2}$ and $W^{2}$ typical of neutrino DIS in accelerator-based oscillation searches. For this reason, progress in understanding the origin and limits of QCD factorization is invaluable to the accuracy and precision of predictions for these upcoming neutrino experiments. In these short proceedings, we introduce a novel approach based on the quantum entropy associated with continuous distributions in QCD, using it to characterize the limits of factorization theorems relevant for the description of neutrino DIS. This work suggests an additional avenue for dissecting factorization-breaking dynamics through the quantum entropy, which could also play a role in quantum simulations of related systems.
hep-phhep-thnucl-thquant-ph1 citation
41*
Nucleon- $Δ$ elastic cross section in isospin-asymmetric nuclear medium with inclusion of scalar-isovector $δ$ meson field
Manzi Nan🇨🇳 · Pengcheng Li🇨🇳 · Wei Zuo🇨🇳 · Qingfeng Li🇨🇳
The production, dynamic evolution, and decay of $Δ$ particles play a crucial role in understanding the properties of high baryon density nuclear matter in intermediate-energy heavy-ion collisions. In this work, the energy-, density-, and isospin-dependent nucleon- $Δ$ elastic cross section ( $σ_{N Δ}^{*}$ ) is studied within the relativistic Boltzmann-Uehling-Uhlenbeck framework, in which the $δ$ meson field is further considered. The results show that the $δ$ and $ρ$ meson related exchange terms have a nonnegligible contribution to the $σ_{N Δ}^{*}$ compared to only considering the $ρ$ meson exchange terms, although there is a significant cancellation on the cross section among these meson exchange terms. In addition, due to the different effects of the medium correction on the effective mass of neutrons, protons, and differently charged $Δ$ s, the individual $σ_{N Δ}^{*}$ exhibits an ordered isospin-asymmetry ( $α$ ) dependence, and $σ_{n Δ}^{*}$ and $σ_{p Δ}^{*}$ have opposite $α$ dependencies. And the $α$ dependence of the ratio $R (α) = σ^{*} (α) / σ^{*} (α = 0)$ for $n Δ$ reaction channels follow $n Δ^{++} > n Δ^{+} > n Δ^{0} > n Δ^{-}$ , while for $p Δ$ it is $p Δ^{-} > p Δ^{0} > p Δ^{+} > p Δ^{++}$ . Moreover, the results also indicate that the isospin effect on the $σ_{N Δ}^{*}$ , which is dominantly caused by the isovector $ρ$ and $δ$ meson fields, is still pronounced at densities up to 3 times normal nuclear density. Finally, a parametrization of the energy-, density-, and isospin-dependent $N Δ$ elastic cross section is proposed based on the microscopic calculated results, and the in-medium $σ_{N Δ}^{*}$ in the energy range of $s$ =2.3 $\sim$ 3.0 GeV can be well described.
↳ nucl-thhep-phCPC(2025)·3 citations
42*
Black Hole Shadow and other Observables away from the Horizon: Extending the Effective Metric Descriptions
Manuel Del Piano🇮🇹 · Stefan Hohenegger🇫🇷 · Francesco Sannino🇮🇹
In previous work we have developed a model-independent, effective description of quantum deformed, spherically symmetric and static black holes in four dimensions. The deformations of the metric are captured by two functions of the physical distance to the horizon, which are provided in the form of self-consistent Taylor series expansions. While this approach efficiently captures physical observables in the immediate vicinity of the horizon, it is expected to encounter problems of convergence at further distances. Therefore, we demonstrate in this paper how to use Padé approximants to extend the range of applicability of this framework. We provide explicit approximations of physical observables that depend on finitely many effective parameters of the deformed black hole geometry, depending on the order of the Padé approximant. By taking the asymptotic limit of this order, we in particular provide a closed-form expression for the black hole shadow of the (fully) deformed geometry, which captures the leading quantum corrections. We illustrate our results for a number of quantum black holes previously proposed in the literature and find that our effective approach provides excellent approximations in all cases.
↳ gr-qcastro-ph.SRhep-phhep-thPRD(2025)·9 citations
43*
An update on the determination of the sphaleron rate in finite temperature QCD
Nicolò Bellini🇮🇹 · Claudio Bonanno🇪🇸 · Francesco D'Angelo🇮🇹 · Massimo D'Elia🇮🇹 · Andrea Giorgieri🇮🇹 · Lorenzo Maio🇫🇷
The sphaleron rate is a key phenomenological quantity both for the axion thermal production in the Early Universe and the Chiral Magnetic Effect occurring in the Quark-Gluon Plasma in presence of a background magnetic field. In this talk we present an extension of our recent determination of the sphaleron rate, in the SU(3) gauge theory, based on the determination of the two-point function of the topological charge density at finite temperature.
↳ hep-lathep-phhep-thPoS(2025)·0 citations
44*
Progress in lattice simulations for two Higgs doublet models
Guilherme Catumba🇪🇸 · Atsuki Hiraguchi🇯🇵 · George W.-S Hou🇹🇼 · Karl Jansen🇩🇪 · Ying-Jer Kao🇹🇼 · C.-J. David Lin🇹🇼 · Alberto Ramos🇪🇸 · Mugdha Sarkar🇹🇼
The custodial Two-Higgs-Doublet-Model with SU(2) gauge fields is studied on the lattice. This model has the same global symmetry structure as the Standard Model but the additional Higgs field enlarges the scalar spectrum and opens the possibility for the occurrence of spontaneous symmetry breaking of the global symmetries. Both the spectrum and the running of the gauge coupling of the custodial 2HDM are studied on a line of constant Standard Model physics with cutoff ranging from 300 to 600 GeV. The lower bounds of the realizable masses for the additional BSM scalar states are found to be well bellow the W boson mass. In fact, for the choice of quartic couplings in this work the estimated lower mass for one of the BSM states is found to be about $\sim 0.2 m_{W}$ and independent of the cutoff.
↳ hep-lathep-phPoS(2025)·2 citations
45*
Gravitational wave astronomy and the expansion history of the Universe
Massimo Giovannini🇨🇭
The timeline of the expansion rate ultimately defines the interplay between high energy physics, astrophysics and cosmology. The guiding theme of this topical review is provided by the scrutiny of the early history of the space-time curvature through the diffuse backgrounds of gravitational radiation that are sensitive to all the stages of the evolution of the plasma. Due to their broad spectrum (extending from the aHz region to the THz domain) they bridge the macroworld described by general relativity and the microworld of the fundamental constituents of matter. It is argued that during the next score year the analysis of the relic gravitons may infirm or confirm the current paradigm where a radiation plasma is assumed to dominate the whole post-inflationary epoch. The role of high frequency and ultra-high frequency signals between the MHz and the THz is emphasized in the perspective of quantum sensing. The multiparticle final state of the relic gravitons and its macroscopic quantumness is also discussed with particular attention to the interplay between the entanglement entropy and the maximal frequency of the spectrum.
↳ gr-qcastro-ph.COhep-exhep-ph+1Int.J.Mod.Phys.A(2025)·4 citations
46*
Double sine-Gordon class of universal coarsening dynamics in a spin-1 Bose gas
Ido Siovitz🇩🇪 · Anna-Maria E. Glück🇩🇪 · Yannick Deller🇩🇪 · Alexander Schmutz🇩🇪 · Felix Klein🇩🇪 · Helmut Strobel🇩🇪 · Markus K. Oberthaler🇩🇪 · Thomas Gasenzer🇩🇪
Far from equilibrium, universal dynamics prevails in many different situations, from pattern coarsening to turbulence. A central longstanding problem concerns the development of a theory of coarsening that rests on the microscopic properties of the system and allows identifying the interaction mechanisms underlying a possible overarching universality class of the associated scaling dynamics. In quantum systems, this is complicated by the existence of nonlinear and topological excitations due to the compact nature of phase degrees of freedom. We show that the double sine-Gordon model as a noncompact low-energy effective model of the spin-1 Bose gas accounts for subdiffusive coarsening dynamics, identifying field configurations spread over multiple wells of the sinusoidal potential as a precondition for the slow scaling. This is in contrast to diffusion-type scaling which the model is known to exhibit as well, where field configurations are seen to not extend over more than two wells. Experimental observations of a spinor BEC support these characteristics, thus constituting a platform for the investigation of sine-Gordon dynamics. Our results point to a path towards a classification of pattern coarsening in many-body systems on the basis of microscopic models.
↳ cond-mat.quant-gashep-phPRA(2025)·7 citations
47*
Dynamics of Hot QCD Matter 2024 -- Hard Probes
Santosh K. Das · Prabhakar Palni · Amal Sarkar · Vineet Kumar Agotiya · Aritra Bandyopadhyay · Partha Pratim Bhaduri · Saumen Datta · Vaishnavi Desai · Debarshi Dey · Vincenzo Greco · Mohammad Yousuf Jamal · Gurleen Kaur and 15 other authors
The hot and dense QCD matter, known as the Quark-Gluon Plasma (QGP), is explored through heavy-ion collision experiments at the LHC and RHIC. Jets and heavy flavors, produced from the initial hard scattering, are used as hard probes to study the properties of the QGP. Recent experimental observations on jet quenching and heavy-flavor suppression have strengthened our understanding, allowing for fine-tuning of theoretical models in hard probes. The second conference, HOT QCD Matter 2024, was organized to bring the community together for discussions on key topics in the field. This article comprises 15 sections, each addressing various aspects of hard probes in relativistic heavy-ion collisions, offering a snapshot of current experimental observations and theoretical advancements. The article begins with a discussion on memory effects in the quantum evolution of quarkonia in the quark-gluon plasma, followed by an experimental review, new insights on jet quenching at RHIC and LHC, and concludes with a machine learning approach to heavy flavor production at the Large Hadron Collider.
↳ nucl-exhep-exhep-phnucl-thIJMPE(2025)·8 citations
48*
Is the formation of primordial black holes from single-field inflation compatible with standard cosmology?
Sasha Allegrini🇮🇹 · Loris Del Grosso🇮🇹 · Antonio J. Iovino🇮🇹 · Alfredo Urbano🇮🇹
In this work, we investigate the generation of primordial black holes (PBHs) within the framework of single-field inflationary models and their compatibility with the cosmological history of the Universe. Our results suggest that, depending on the masses of the formed PBHs, single-field inflation models require more than fine-tuning a potential to induce ultra-slow roll; it necessitates a comprehensive understanding of the post-inflationary cosmological evolution. As an explicative example, we introduce a new model, based on a double inflection point and consistent with Cosmic Microwave Background observations, capable of generating sub-solar PBHs, whose merger could be potentially detectable by the LVK experiment.
↳ astro-ph.COgr-qchep-phPRD(2025)·24 citations
49*
Anisotropic Photon and Dilepton Yield in a Thermalized Quark-Gluon Plasma under Magnetic Fluctuations
Jorge David Castaño-Yepes🇨🇱 · Enrique Muñoz🇨🇱
In this article, we analyze the effects of stochastic magnetic fluctuations with respect to an intense magnetic field background over the yields for photon and dilepton emission processes in a thermalized quark-gluon plasma phase. Such stochastic fluctuations model the effects of nearly random initial conditions for the nuclei participating in non-central heavy-ion collisions, which are the sources of the background magnetic field. Our theoretical results predict significant anisotropic effects due to stochastic magnetic noise over the angular distribution for photon and dilepton production rates in this scenario.
↳ hep-thhep-phPRD(2025)·8 citations
50*
Oscillators with imaginary coupling: spectral functions in quantum mechanics and quantum field theory
Bruno W. Mintz🇧🇷 · Itai Y. Pinheiro🇧🇷 · Rui Aquino🇧🇷
The axioms of Quantum Mechanics require that the hamiltonian of any closed system is self-adjoint, so that energy levels are real and time evolution preserves probability. On the other hand, non-hermitian hamiltonians with $P T$ -symmetry can have both real spectra and unitary time evolution. In this paper, we study in detail a pair of quantum oscillators coupled by an imaginary bilinear term, both in quantum mechanics and in quantum field theory. We discuss explicitly how such hamiltonians lead to perfectly sound physical theories with real spectra and unitary time evolution, in spite of their non-hermiticity. We also analyze two-point correlation functions and their associated Källen-Lehmann representation. In particular, we discuss the intimate relation between positivity violation of the spectral functions and the non-observability of operators in a given correlation function. Finally, we conjecture that positivity violation of some spectral functions of the theory could be a generic sign of the existence of complex pairs of energy eigenvalues (i.e., a $P T$ -broken phase) somewhere in its parameter space.
↳ quant-phcond-mat.str-elhep-phPRD(2025)·2 citations
51*
Sphere free energy of scalar field theories with cubic interactions
Simone Giombi🇺🇸 · Elizabeth Himwich🇺🇸 · Andrei Katsevich🇺🇸 · Igor Klebanov🇺🇸 · Zimo Sun🇺🇸
The dimensional continuation approach to calculating the free energy of $d$ -dimensional Euclidean CFT on the round sphere $S^{d}$ has been used to develop its $4 - ϵ$ expansion for a number of well-known non-supersymmetric theories, such as the $O (N)$ model. The resulting estimate of the sphere free energy $F$ in the 3D Ising model has turned out to be in good agreement with the numerical value obtained using the fuzzy sphere regularization. In this paper, we develop the $6 - ϵ$ expansions for CFTs on $S^{d}$ described by scalar field theory with cubic interactions and use their resummations to estimate the values of $F$ . In particular, we study the theories with purely imaginary coupling constants, which describe non-unitary universality classes arising when certain conformal minimal models are continued above two dimensions. The Yang-Lee model $M (2, 5)$ is described by a field theory with one scalar field, while the $D$ -series $M (3, 8)$ model is described by two scalar fields. We also study the $O S p (1∣2)$ symmetric cubic theory of one commuting and two anti-commuting scalar fields, which appears to describe the critical behavior of random spanning forests. In the course of our work, we revisit the calculations of beta functions of marginal operators containing the curvature. We also use another method for approximating $F$ , which relies on perturbation theory around the bilocal action near the long-range/short-range crossover. The numerical values it gives for $F$ tend to be in good agreement with other available methods.
↳ hep-thcond-mat.stat-mechhep-phJHEP(2025)·13 citations
52*
Machine Learning-Assisted Measurement of Lepton-Jet Azimuthal Angular Asymmetries in Deep-Inelastic Scattering at HERA
The H1 collaboration: V. Andreev (47) · M. Arratia (31)🇺🇸 · A. Baghdasaryan (43)🇦🇲 · A. Baty (8)🇺🇸 · K. Begzsuren (37)🇲🇳 · A. Bolz (15)🇩🇪 · V. Boudry (27)🇫🇷 · G. Brandt (14)🇩🇪 · D. Britzger (11)🇩🇪 · A. Buniatyan (6)🇬🇧 · L. Bystritskaya (47) · A.J. Campbell (15)🇩🇪 and 131 other authors
In deep-inelastic positron-proton scattering, the lepton-jet azimuthal angular asymmetry is measured using data collected with the H1 detector at HERA. When the average transverse momentum of the lepton-jet system, $∣ P_{⊥} ∣$ , is much larger than the total transverse momentum of the system, $∣ q_{⊥} ∣$ , the asymmetry between parallel and antiparallel configurations, $P_{⊥}$ and $q_{⊥}$ , is expected to be generated by initial and final state soft gluon radiation and can be predicted using perturbation theory. Quantifying the angular properties of the asymmetry therefore provides an additional test of the strong force. Studying the asymmetry is important for future measurements of intrinsic asymmetries generated by the proton's constituents through Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs), where this asymmetry constitutes a dominant background. Moments of the azimuthal asymmetries are measured using a machine learning method for unfolding that does not require binning.
↳ hep-exhep-phnucl-ex22 citations
53*
Intrinsic non-Gaussianity of ultra slow-roll inflation
Guillermo Ballesteros🇪🇸 · Jesús Gambín Egea🇪🇸 · Thomas Konstandin🇩🇪 · Alejandro Pérez Rodríguez🇪🇸 · Mathias Pierre🇩🇪 · Julián Rey🇩🇪
We study the non-Gaussian tail of the curvature fluctuation, $ζ$ , in an inflationary scenario with a transient ultra slow-roll phase that generates a localized large enhancement of the spectrum of $ζ$ . To do so, we implement a numerical procedure that provides the probability distribution of $ζ$ order by order in perturbation theory. The non-Gaussianities of $ζ$ can be shown to arise from its non-linear relation to the inflaton fluctuations and from the intrinsic non-Gaussianities of the latter, which stem from its self interactions. We find that intrinsic non-Gaussianities, which have often been ignored to estimate the abundance of primordial black holes in this kind of scenario, are important. The relevance of the intrinsic contribution depends on the rapidity with which the transient ultra slow-roll phase occurs, as well as on its duration. Our method cannot be used accurately when the perturbative in-in formalism fails to apply, highlighting the relevance of developing fully non-perturbative approaches to the problem.
↳ astro-ph.COgr-qchep-phhep-thJCAP(2026)·14 citations
54*
Path integral measure and RG equations for gravity
C. Branchina🇮🇹 · V. Branchina🇮🇹 · F. Contino🇮🇹 · A. Pernace🇮🇹
Considering the Einstein-Hilbert truncation for the running action in (euclidean) quantum gravity, we derive the renormalization group equations for the cosmological and Newton constant. We find that these equations admit only the Gaussian fixed point with a UV-attractive and a UV-repulsive eigendirection, and that there is no sign of the non-trivial UV-attractive fixed point of the asymptotic safety scenario. Crucial to our analysis is a careful treatment of the measure in the path integral that defines the running action and a proper introduction of the physical running scale $k$ . We also show why and how in usual implementations of the RG equations the aforementioned UV-attractive fixed point is generated.
↳ hep-thgr-qchep-phPRD(2025)·14 citations
55*
Gluon Unpolarized, Polarized, and Transversity GPDs from Lattice QCD: Lorentz-Covariant Parametrization (Part I)
Jakob Schoenleber🇺🇸 · Raza Sabbir Sufian🇺🇸 · Taku Izubuchi🇺🇸 · Yi-Bo Yang🇨🇳
We identify the matrix elements necessary to determine the leading-twist gluon generalized parton distributions (GPDs) $H_{g}, E_{g}, \wt H_{g}, \wt E_{g}, H_{g}^{T}, E_{g}^{T}, \wt H_{g}^{T}, \wt E_{g}^{T}$ in lattice QCD calculations. We present a method to achieve a Lorentz-covariant parameterization of the matrix elements in terms of a linearly independent basis of tensor structures. This parameterization is crucial for projecting lattice QCD matrix elements onto light cone distributions. For the first time, we determine the corresponding components that project onto the linear combinations of invariant amplitudes, which reduce to the different gluon GPDs in the light cone limit and enable their separation in a lattice QCD calculation for spin- $0$ and spin- $\frac{1}{2}$ hadrons. Hence, this work lays the foundation for the numerical determination of the gluon GPDs from first-principle lattice QCD calculations, directly advancing our understanding of the mass and spin structures and mechanical properties of the nucleon, as well as the physics underlying deeply virtual Compton scattering and deeply virtual meson production in a range of experimental processes.
↳ hep-lathep-phnucl-thPRD(2025)·5 citations
56*
Sweeping the Dust Away -- Correcting the Phase Space Density of the Milky Way with Unsupervised Machine Learning
Eric Putney🇺🇸 · David Shih🇺🇸 · Sung Hak Lim🇺🇸 · Matthew R. Buckley🇺🇸
The Boltzmann equation relates the equilibrium phase space distribution of stars in the Milky Way to the Galaxy's gravitational potential. However, observations of stellar populations are biased by extinction from foreground dust, which complicates measurements of the potential in the disk and towards the Galactic center. Using the kinematics of Red Clump and Red Branch stars in Gaia DR3, we use machine learning to simultaneously estimate both the unbiased stellar phase space density and the gravitational potential. The unbiased phase space density is obtained through a learned "dust efficiency factor" -- an observational selection function that accounts for dust extinction. The potential and the dust efficiency are parameterized by fully connected neural networks and are completely data driven. We validate the dust efficiency using a recent three-dimensional dust map in this work, and examine the potential in a companion paper.
↳ astro-ph.GAhep-ph8 citations
57*
Black hole spectroscopy and nonlinear echoes in Einstein-Maxwell-scalar theory
Marco Melis🇮🇹 · Fabrizio Corelli🇮🇹 · Robin Croft🇮🇹 · Paolo Pani🇮🇹
In the context of Einstein-Maxwell-scalar theory with a nonminimal coupling between the electromagnetic and scalar field, we study linear (non)radial perturbations and nonlinear radial dynamics of spherically symmetric black holes. In a certain region of the parameter space, this theory admits hairy black holes with a stable photon sphere. This has a counterpart in the effective potential of linear perturbations, featuring multiple maxima and minima. The corresponding quasinormal mode spectrum contains long-lived modes trapped in the potential cavity and the time-domain linear response displays echoes, as previously observed for horizonless compact objects. Interestingly, the black-hole dynamics in this theory can be studied at the nonlinear level. By performing fully-fledged 1+1 simulations, we show that echoes are present even when the nonlinearities are significant. To our knowledge, this is the first example of echoes appearing in a consistent theory beyond a linearized analysis. In a follow-up work we will study whether this feature is also present in the post-merger signal from black hole collisions in this theory.
↳ gr-qcastro-ph.HEhep-phhep-thPRD(2025)·8 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.