HEP Phenomenology·hep-ph
20 papers—12 primary·8 cross-listed·reconstructed*
Ferruccio Feruglio🇮🇹 · Saul Ramos-Sanchez🇲🇽
Quarks and leptons, the fundamental building blocks of the subatomic world, manifest in three families - replicas with identical quantum numbers that differ only in their masses. After summarizing the present data, an overview is presented of the main attempts to explain the origin of the observed patterns and trace it back to an as-yet-unknown fundamental principle.
Bei Zhou🇺🇸 · Pedro Machado🇺🇸
Nonzero neutrino masses guarantee new physics and neutrinos are excellent probes of extreme environments in the Universe. The recent collider neutrino experimental program, including FASER and SND@LHC, along with the planned Forward Physics Facility at the High-Luminosity Large Hadron Collider, is opening a new window into neutrino physics and astrophysics. In this article, we review recent achievements and prospects of collider neutrino experiments, including key achievements such as the first measurements of collider neutrino interactions at unprecedented energies and the exploration of new physics scenarios, like dark matter candidates, sterile neutrinos, and non-standard neutrino interactions. For concreteness, we will focus on the significant scientific opportunities presented by the Forward Physics Facility, which will enable precision measurements of neutrino cross sections and proton structure at low parton momentum fraction. Furthermore, collider neutrino studies will substantially reduce systematic uncertainties in calculating atmospheric neutrino fluxes, thereby improving astrophysical neutrino observations as well as advancing our understanding of cosmic-ray interactions.
We investigate the nucleon's chiral-odd generalized parton distribution functions (GPDs) in the large- limit of QCD. Extending previous work on the leading-order contribution in the expansion, we focus on the next-to-leading-order contributions and provide a complete set of flavor-singlet and flavor-non-singlet chiral-odd GPDs. This study includes the derivation of the spin-flavor structure of the baryon matrix element of the chiral-odd operator, the proof of the polynomiality property and associated sum rules, and numerical estimates based on the gradient expansion. The spin-flavor structure of the nucleon matrix element is interpreted through a multipole expansion in the transverse momentum transfer, leading to the definition of multipole mean-field GPDs. Using these GPDs as the basis of our analysis, we take their -th moments and demonstrate the polynomiality property within the mean-field framework, making use of discrete symmetries in the proof. In particular, the first moments () of the GPDs are related to the nucleon tensor form factors, as generally required. By performing a gradient expansion, we compute the chiral-odd GPDs and present numerical estimates. Our results show good agreement with lattice QCD predictions.
P.M. Ferreira🇵🇹 · B. Grzadkowski🇵🇱 · O.M. Ogreid🇳🇴
Recently, a hitherto unknown class of renormalization group stable relations between parameters of bosonic field theories have been identified and dubbed as the r0 or 'GOOFy' symmetries. Here, one-loop properties of the r0 invariant two-Higgs Doublet Model and a minimal symmetric model are discussed. It is concluded that the symmetry is present at the one-loop provided the UV cutoff squared transforms non-trivially under r0. The minimal model requires the presence of two real fields.
Jeonghak Han🇨🇳 · Hyun Min Lee🇰🇷 · Jun-Ho Song🇰🇷
We present the Coleman-Weinberg potential for the inflaton in the pole inflation scenarios such as the Higgs pole inflation and the Peccei-Quinn (PQ) pole inflation. The loop corrections stem from the Standard Model particles and extra singlet scalar fields in the former case, making the quartic coupling for the Higgs inflaton modified by the inflaton-dependent power corrections during inflation. We also obtain similar power corrections to the quartic coupling for the PQ inflaton, depending on the realizations of the PQ symmetry in KSVZ and DFSZ models. We show that the loop corrections can shift the spectral index in the pole inflation to a larger value in favor of the ACT results, while being compatible with the bound on the tensor-to-scalar ratio. For a positive one-loop beta function for the inflaton quartic coupling (namely, ), a sub-dominant contribution from the two-loop corrections can be accommodated. On the other hand, if the one-loop beta function for the inflaton coupling is negative (namely, ), we need sizable contributions from two-loops that are larger than the one-loop corrections due to the ACT results.
Satyabrata Datta🇨🇳 · Rome Samanta🇮🇹
Supercooled phase transitions, as predicted, e.g., in near-conformal and confining extensions of the Standard Model (SM), are established sources of strong stochastic gravitational wave backgrounds (SGWBs). In this work, we investigate another facet of such transitions: their significant and largely uncharted impact on gravitational wave spectra originating from independent cosmological sources. Focusing on gravitational waves produced by a metastable cosmic string network, we show that an intervening supercooled phase, initiating thermal inflation, can reshape and suppress the high-frequency part of the spectrum. This mechanism reopens regions of string parameter space previously excluded by LIGO's null results, while remaining compatible with the nanohertz SGWB signal reported by pulsar timing arrays (PTAs). The resulting total spectrum typically exhibits a dual-component structure, sourced by both string decay and the phase transition itself, rendering the scenario observationally distinctive. We systematically classify the viable parameter space and identify regions accessible to upcoming detectors such as Advanced LIGO, LISA, and ET.
Long-Shun Lu🇨🇳 · Cai-Dian Lü🇨🇳 · Yue-Long Shen🇨🇳 · Yan-Bing Wei🇨🇳
We construct light-cone sum rules for various types of effective form factors in the and decays by analyzing vacuum-to- (or -to-) correlation functions with the light -baryon interpolating current. These form factors, defined via hadronic matrix elements within soft-collinear effective theory (SCET), enter the next-to-leading-power QCD factorization formulas for large-recoil transitions. Implementing the perturbative matching from to heavy quark effective theory, we determine the hard-collinear functions at next-to-leading-order accuracy. Based on light-cone sum rule predictions for the form factors, we compute the -dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for decay, as well as the branching fraction for decay.
John Ellis🇬🇧 · Hong-Jian He🇨🇳 · Rui-Qing Xiao🇨🇳 · Shi-Ping Zeng🇨🇳
Neutral triple gauge couplings (nTGCs) first arise from the dimension-8 operators of the Standard Model Effective Field Theory (SMEFT), rather than the dimension-4 SM Lagrangian and dimension-6 SMEFT operators, opening up a unique window for probing new physics at the dimension-8 level. In this work, we formulate the nTGC form factors of () that are compatible with the spontaneous breaking of the SU(2)U(1) electroweak gauge symmetry and consistently match the dimension-8 nTGC operators in the broken phase. We study the sensitivities for probing both the form factors and the corresponding new physics scales through production (with visible/invisible fermionic decays) at high energy colliders including CEPC, FCC-ee, ILC and CLIC. In particular, we identify the dimension-8 operator that contributes to the pure triple boson coupling alone, but not the mixed coupling. We further study the correlations between probes of the and couplings. Using machine learning, we show that angular distributions of the final-state fermions can play key roles in suppressing the SM backgrounds. The sensitivities can be further improved by using polarized beams. We demonstrate that machine learning is advantageous for handling the 4-body final states from decays and improves significantly the sensitivity reaches of probes of nTGCs in collisions. We find that nTGC new physics scales can be probed up to the multi-TeV scale at the proposed colliders.
Yabo Dong🇨🇳 · Manqi Ruan🇨🇳 · Kun Wang🇨🇳 · Haijun Yang🇨🇳 · Jingya Zhu🇨🇳
Several possible excesses around 95 GeV hint at an additional light scalar beyond the Standard Model. We examine the capability of the CEPC to test this hypothesis in the Higgsstrahlung channel with and . Full detector simulation shows that the optimal center-of-mass energy to study the 95 GeV light scalar is 210 GeV. A deep neural network classifier reduces the luminosity required for discovery by half. At , the CEPC's sensitivity to the signal strength reaches 0.016 and 0.020 for 210 GeV and 240 GeV, respectively. The corresponding thresholds for a 5% precision measurement are and . At 210 GeV (240 GeV), coverage of all N2HDM-Flipped samples with requires (1.22 ). These results establish a 210 GeV run, augmented by machine-learning selection, as the most efficient strategy to confirm or refute the 95 GeV excess at future lepton colliders.
Biswajit Das🇮🇳 · Pramod Sharma🇮🇳 · Ambresh Shivaji🇮🇳
The single Higgs production in neutral-current (NC) and charged-current (CC) processes at an electron-proton () collider is a useful channel to probe new physics effects in the Higgs coupling to vector boson (). In this context, observables sensitive to non-standard couplings previously studied at leading order require improved theoretical precision through the inclusion of radiative corrections. In this work, we present a fully differential Higgs plus one jet production at next-to-leading-order (NLO) accuracy in QCD for both the NC and CC processes. For the proposed Large Hadron electron Collider (LHeC) configuration, with a 60~GeV electron beam and a 7~TeV proton beam, the total cross sections receive modest corrections with significantly reduced scale uncertainties. We find that in several kinematic distributions which are relevant to the analysis of couplings, the NLO K-factors are not flat. Within the Standard Model, the polar angle of the electron (for NC) and the azimuthal angular correlation (for both NC and CC processes) receive maximum corrections in the range of 8-10\% in certain bins. We also compute NLO QCD corrections in the presence of non-standard interactions. The corrections in the azimuthal angular correlations are similar to the standard model predictions. For the polar angle of the electron, the corrections are sensitive to the nature of the coupling.
F. C. N. Q. Pimenta🇵🇹 · C. J. A. P. Martins🇵🇹
The charge-velocity-dependent one-scale model is an extension of the canonical velocity-dependent one-scale model which explicitly incorporates additional degrees of freedom on the string worldsheet, such as arbitrary currents and charges, expected in physically realistic models. A previous paper [Pimenta and Martins, Phys. Rev. D 110, 023540 (2024)] started an in-depth classification of its possible asymptotic scaling solutions, with the goal of identifying distinguishing features which may be tested against numerical simulations or future observations. This earlier analysis restricted itself to unbiased solutions; in the present one we relax this assumption, allowing for the possibility of energy loss biases between the bare string and the charge/current, or between the charge and the current themselves. We find additional scaling solutions, some of which are parametric extensions of the unbiased ones while others are new scaling branches which do not exist in the unbiased case. Overall it remains the case that there are three broad classes of solutions, mainly depending on the balance between the expansion rate and the available energy loss mechanisms. Our results enable a quantitative calibration of the model, using forthcoming high-resolution numerical simulations.
Abhishek Banerjee🇺🇸 · Csaba Csáki🇺🇸 · Michael Geller🇮🇱 · Zamir Heller-Algazi🇮🇱 · Ameen Ismail🇺🇸
The dilaton, a pseudo-Nambu-Goldstone boson (pNGB) of broken scale invariance, is an appealing ultralight dark matter (DM) candidate. Its mass is protected by conformal invariance and it can be searched for in tabletop experiments. However, contrary to standard pNGBs of internal symmetries, the dilaton generically has a large non-derivative self-coupling, leading to radiative contributions to its mass of the order of its decay constant. Hence typical ultralight dilatons should also have sub-eV decay constants, which would incur significant deviations from standard DM behavior at structure formation times, in severe tension with observations. Therefore, a fine-tuning is required to generate a hierarchy between the mass and the decay constant. In this work, we consider whether supersymmetry (SUSY) can be used to protect this hierarchy from quantum corrections. To ensure an ultralight dilaton mass robust against realistic SUSY-breaking contributions, we must consider a novel dilaton stabilization mechanism. The observed DM abundance can be produced by the misalignment mechanism for dilaton masses ranging from to eV. Unfortunately, irreducible SUSY-breaking corrections due to gravity restrict the couplings between the dilaton and the Standard Model to be extremely small, beyond the reach of any current or proposed experiments. Our work demonstrates that constructing a consistent model of ultralight dilaton DM is quite involved.
Alessandro Georgoudis🇬🇧 · Vasco Goncalves🇵🇹 · Carlo Heissenberg🇫🇷 · Julio Parra-Martinez🇫🇷
We present the first computation of the nonlinear gravitational memory waveform for the scattering of two compact objects in General Relativity at leading order in the post-Minkowskian expansion. We use the scattering-amplitudes-based representation of the gravitational waveform, which naturally expresses the nonlinear memory as the contribution of soft gravitons emitted by the gravitational waves themselves. We perform the calculation by applying a multipolar decomposition to the waveform and using the reverse unitarity method to obtain explicit exact-in-velocity predictions. We validate the results by calculating the corresponding velocity-expanded post-Newtonian multipoles, finding perfect agreement. Our results complete the knowledge of the gauge-invariant non-analytic-in-frequency part of the multipolar waveform, thus providing a useful benchmark for future calculations of this quantity.
Payaswinee Arvikar (1 and 2)🇮🇳 · Sakshi Gautam (2 and 3)🇮🇳 · Anagh Venneti (2)🇮🇳 · Sarmistha Banik (2) ((1) Dharampeth M. P. Deo Memorial Science College, Nagpur, India (2) Department of Physics, BITS-Pilani Hyderabad Campus, Hyderabad, India (3) Department of Physics, Panjab University, Chandigarh, India)🇮🇳
We studied the properties of dark matter admixed-neutron stars (DMANS), considering fermionic dark matter (DM) that interacts gravitationally with hadronic matter (HM). Using relativistic mean-field equations of state (EoSs) for both components, we solved the two-fluid Tolman Oppenheimer Volkoff (TOV) equations to determine neutron star (NS) properties assuming that DM is confined within the stellar core. For hadronic matter, we employed realistic EoSs derived from low energy nuclear physics experiments, heavy-ion collision data, and NS observations. To constrain key dark matter parameters such as particle mass, mass fraction, and the coupling to mass ratio, we applied Bayesian inference, incorporating various astrophysical data including mass, radii, and NICER mass-radius distributions for PSR J0740+6620 and PSR J0030+0451. Additionally, we explored the influence of high-density HM EoSs and examined the impact of stiffer hadronic EoSs, excluding the vector meson self-interaction term. Our findings indicate that current astrophysical observations primarily constrain the dark matter fraction, while providing limited constraints on the particle mass or coupling. However, the dark matter fraction is largely insensitive to how astrophysical observations or uncertainties in the high-density EoS are incorporated. Instead, it is predominantly determined by the stiffness of the hadronic EoS at high densities, with stiffer hadronic EoSs yielding a higher dark matter mass fraction. Therefore, we conclude that the dark matter fraction plays a crucial role in shaping the properties of DMANS. Future investigations incorporating more realistic EoSs and astrophysical observations of other compact objects may provide deeper insights into dark matter.
In a talk at an IHEP-Beijing symposium celebrating the 50th anniversary of the discovery of the J/, I reminisced about some of the interesting phenomena that were observed in J/ decays in the BES, BESII, and BESIII detectors during the 35 year long BES experimental program. The three order of magnitude increase in the J/ event samples and the improved detector capabilities that occurred during this time led to a persistent series of interesting discoveries and new insights. As more J/ events were collected, the scientific interest in them increased and the breadth of physics topics that are addressed by them expanded. In addition, I speculated on what might happen if, in the next few decades, the magnitude of J/ data samples and the detector capabilities continued to increase at similar paces. In particular, I emphasize the possibilities of searches for CP violation in strange hyperon decays and testing the CPT~theorem with strangeness-tagged neutral kaon decays.
Shin'ichi Nojiri🇯🇵 · S.D. Odintsov🇪🇸 · V.K. Oikonomou🇬🇷
In this work, we shall consider how a dynamical oscillating and phantom crossing dark energy era can be realized in the context of gravity. We approach the topic from a theoretical standpoint considering all the conditions that may lead to a consistent phantom crossing behavior and separately how the gravity context may realize oscillating dark energy era. Apart from our qualitative considerations, we study in a quantitative way two gravity dark energy models which are viable cosmologically and also exhibit simultaneously phantom crossing behavior and also oscillating dark energy. We consider these models by solving numerically the field equations using appropriate statefinder parameters engineered for dark energy studies. As we show, provides a natural extension of Einstein's general relativity which can naturally realize a transition from a phantom era to a quintessential era, a feature supported by recent observational data, without resorting to phantom scalar fields to realize the phantom evolution.
Yuan-Kun Gao🇨🇳 · Da Huang🇨🇳 · Yue-Liang Wu🇨🇳
We investigate the production and detection of gravitational waves (GWs) within the framework of Gravitational Quantum Field Theory (GQFT). In this theory, GWs exhibit five propagating modes: one scalar, two vector, and two tensor modes. Unlike General Relativity, the gravitational field equations in GQFT involve both symmetric and antisymmetric tensors, governed by their respective energy-momentum tensors, both of which can act as sources for GW radiation. By solving the linearized gravitational equations, we derive general analytic expressions for the different GW degrees of freedom. Our analysis reveals that the symmetric energy-momentum tensor generates scalar and tensor GWs through the trace and traceless parts of the quadrupole moment, respectively. In contrast, the antisymmetric stress tensor induces scalar and vector GWs with enhanced coupling strengths. We examine two illustrative examples: a black hole binary with a slightly elliptical orbit, which produces scalar GWs, and a neutron star binary where one component has a net spin aligned with its velocity, leading to vector GW emission. Finally, we study the detectability of these GW polarizations by analyzing their signatures in GW detectors. Our findings indicate that current observatories can detect both scalar and tensor modes, while a newly designed detector would be required to probe vector GWs.
Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Gerd Röpke🇩🇪
Based on a generalized Beth-Uhlenbeck approach to thermodynamics of QCD motivated by cluster decomposition we present a unified equation of state of hot strongly interacting matter and analyze its properties in a wide range of temperatures. The hadrons are treated as color singlet multiquark clusters in medium with a background gluon field in the Polyakov gauge. The confining aspect of QCD is accounted for by the Polyakov loop mechanism and by a large vacuum quark mass motivated by a confining density functional approach. We demonstrate that an abrupt switching between hadronic and partonic degrees of freedom, which is one of striking manifestations of dynamical restoration of chiral symmetry, is accompanied by a smooth behavior of entropy density at chiral crossover. Individual contributions of different components of strongly interacting matter to its speed of sound are analyzed for the first time. It is shown that restoration of chiral symmetry drives speed of sound of hadron gas to negative values, manifesting its mechanical instability and being in a strike disagreements with the lattice QCD data. Accounting for the partonic excitations naturally resolves this contradiction.
Ioannis D. Gialamas🇪🇪 · Gert Hütsi🇪🇪 · Martti Raidal🇪🇪 · Juan Urrutia🇪🇪 · Martin Vasar🇪🇪 · Hardi Veermäe🇪🇪
We analyse DESI BAO, CMB, and supernova data to explore the physical origin of the DESI indication for dynamical dark energy. Beyond the standard CPL parametrization, we explore truncated alternatives and quintessence models. We conclude that there is compelling evidence for dark energy to be decaying in the late universe, but the evidence for a phantom behaviour is less significant. Models without phantom behaviour are compatible with the data at the CL. Furthermore, we examine a concrete quintessence scenario with a Higgs-like potential, allowing for a direct comparison with parametrized approaches and testing its consistency with current observations. This framework enables a broader investigation of late-time cosmic evolution and reveals a preference for a future transition into an anti-de Sitter space, which may ultimately lead to a cosmological collapse of our Universe.
Will Barker🇨🇿 · Carlo Marzo🇪🇪 · Alessandro Santoni🇦🇹
We systematically obtain all linear models which propagate a totally symmetric rank-three field without parity violation on a flat background. Each such model is defined exclusively by its gauge symmetry, a necessary property of effective field theories in the infrared limit. By comparison, models obtained by other means (tuning couplings or cherry-picking operators) may be unstable against radiative corrections. For each model, we compute the spectrum of massless and massive particles, and the no-ghost-no-tachyon constraints on the couplings. We conclude that foundational models exist which can propagate one massless particle of spin one or spin three in isolation, or both particles simultaneously, generalising the model of Campoleoni and Francia. Our algorithm for detecting symmetric models is grounded in particle physics methods, being based directly on the Wigner decomposition of the field. Compared to our recent analysis of the totally symmetric rank-three field (whose results we confirm and extend) our new algorithm does not require an ansatz for the symmetry transformation, and is not restricted to so-called 'free' symmetries.
* 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.