Fri·Mar 11, 2022Friday·March 11, 2022

1. 01*

   New Ideas in Baryogenesis: A Snowmass White Paper

   Gilly Elor🇩🇪 · Julia Harz🇩🇪 · Seyda Ipek🇨🇦 · Bibhushan Shakya🇩🇪 · Nikita Blinov🇨🇦 · Raymond T. Co🇺🇸 · Yanou Cui🇺🇸 · Arnab Dasgupta🇺🇸 · Hooman Davoudiasl🇺🇸 · Fatemeh Elahi🇩🇪 · Kåre Fridell🇩🇪 · Akshay Ghalsasi🇺🇸 and 12 other authors

   The Standard Model of Particle Physics cannot explain the observed baryon asymmetry of the Universe. This observation is a clear sign of new physics beyond the Standard Model. There have been many recent theoretical developments to address this question. Critically, many new physics models that generate the baryon asymmetry have a wide range of repercussions for many areas of theoretical and experimental particle physics. This white paper provides an overview of such recent theoretical developments with an emphasis on experimental testability.

   hep-phastro-ph.COhep-ex43 citations
2. 02*

   Three-loop QCD corrections to the electroweak boson masses

   Stephen P. Martin🇺🇸

   I find the three-loop corrections at leading order in QCD to the physical masses of the Higgs, W, and Z bosons in the Standard Model. The results are obtained as functions of the $\overline{\mathrm{MS}}$ Lagrangian parameters only, using the tadpole-free scheme for the vacuum expectation value. The dependences of the computed masses on the renormalization scale are found to be smaller than present experimental uncertainties in each case. In the case of the Higgs boson mass, the new result is the state-of-the-art, while the results for $W$ and $Z$ are in good numerical agreement with corresponding results in the on-shell and hybrid schemes. These results are now included in the SMDR (Standard Model in Dimensional Regularization) computer code.

   hep-phPRD(2022)·19 citations
3. 03*

   Benchmark Planes for Higgs-to-Higgs Decays in the NMSSM

   Ulrich Ellwanger🇫🇷 · Cyril Hugonie🇫🇷

   We present benchmark planes (or lines) with cross sections via gluon fusion for the processes $H\to h+H_S$, resonant Higgs pair and triple Higgs production, $A\to h+(A_S\to \gamma \gamma )$, $A\to Z+h$ and $A\to Z+H_S$ within the Next-to-Minimal Supersymmetric Standard Model. Moreover we propose new searches for $H\to h+(H_S\to t\bar{t})$, $A\to Z+(H_S\to h+h)$ and $A\to Z+(H_S\to t\bar{t})$ for which possible cross sections are given. These allow the experimental collaborations to verify in the future which search channels cover yet unexplored regions of the parameter space. Expressions for the dominant contributions to trilinear Higgs couplings and Higgs--Z couplings are discussed which allow to identify the dominant processes contributing to a given final state.

   hep-phhep-exEPJC(2022)·28 citations
4. 04*

   Evaluation of the three-flavor quark-disconnected contribution to the muon anomalous magnetic moment from experimental data

   Diogo Boito🇧🇷 · Maarten Golterman🇺🇸 · Kim Maltman🇨🇦 · Santi Peris🇪🇸

   We point out that the sum of the strange-quark-connected and full, three-flavor quark-disconnected contributions to the leading-order hadronic vacuum polarization contribution, $a_{\mu }^{\mathrm{LO},\mathrm{HVP}}$, to the anomalous magnetic moment of the muon, is a physical observable, and provide a data-based determination of this quantity in the isospin limit. The result, $40.1(1.5)\times 10^{-10}$, or $38.7(2.0)\times 10^{-10}$, depending on which data compilation is used, serves as a target of comparison for lattice calculations of the same isospin-limit combination. Subtracting from this result the average of lattice determinations of the strange-quark-connected contribution, one obtains also an alternate determination of the isospin-limit three-flavor disconnected contribution to $a_{\mu }^{\mathrm{LO},\mathrm{HVP}}$. The result of this determination, $-13.3(1.5)\times 10^{-10}$, or $-14.6(2.0)\times 10^{-10}$, depending on which data compilation is used, agrees well and is competitive with the most precise current lattice determination.

   hep-phhep-exhep-latPRD(2022)·24 citations
5. 05*

   Complete theory of radiative corrections to $K_{\ell 3}$ decays and the $V_{us}$ update

   Chien-Yeah Seng🇩🇪 · Daniel Galviz🇩🇪 · Mikhail Gorchtein🇩🇪 · Ulf-G. Meißner🇩🇪

   We fill up the missing piece in our own re-analysis of the long-distance electromagnetic radiative corrections to semileptonic kaon decays by performing a rigorous study in the $K\to \pi {\mu }^{+}{\nu }_{\mu }(\gamma )$ channels. With appropriate experimental and lattice inputs, we achieve a precision level of $10^{-4}$ in these channels. This is comparable to our previous analysis in the $K\to \pi e^{+}{\nu }_e(\gamma )$ channels. With this new result, we present an updated global analysis to extract the Standard Model parameter $|V_{us}|$ from semileptonic kaon decays. We obtain $|V_{us}|=0.22308(55)$ and $0.22356(73)$, using the lattice average of the $K^0\to {\pi }^{-}$ transition form factor at $N_f=2+1+1$ and $N_f=2+1$, respectively.

   hep-phhep-exhep-lathep-th+1JHEP(2022)·48 citations
6. 06*

   Physics of the tau lepton

   Jorge Portoles (IFIC, Valencia)🇪🇸

   Within our present knowledge, the tau is the heaviest lepton and the only one decaying into hadrons, a fact that makes it the source of a very rich phenomenology. It represents the third family of leptons in the Standard Model, a feature that helps its classification but whose real meaning is not asserted yet. The tau lepton provides: i) a clean and unique environment to study both the hadronization of QCD currents, in an energy region populated by resonances, and the phenomenological determination of relevant parameters of the Model; ii) together with the muon, they have a very constrained flavour dynamics (in the absence of neutrino masses) due to an accidental global symmetry of the Standard Model. In consequence, the tau lepton brings an excellent benchmark for the study of QCD at low energies and, at the same time, for the search of new physics.

   hep-phhep-exRev.Mex.Fis.Suppl.(2022)·1 citation
7. 07*

   Determination of the strong-coupling constant from the $Z$-boson transverse-momentum distribution

   Stefano Camarda🇨🇭 · Giancarlo Ferrera🇮🇹 · Matthias Schott🇩🇪

   The strong-coupling constant is determined from the low-momentum region of the transverse-momentum distribution of $Z$ bosons produced through the Drell-Yan process, using predictions at third order in perturbative QCD. The analysis employs a measurement performed in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=1.96$ TeV with the CDF experiment. The determined value of the strong coupling at the reference scale corresponding to the $Z$-boson mass is ${\alpha }_S(m_Z)=0.1191_{-0.0016}^{+0.0013}$.

   hep-phhep-exEPJC(2024)·33 citations
8. 08*

   Neutrino forces and the Sommerfeld enhancement

   Rupert Coy🇧🇪 · Xun-Jie Xu🇨🇳 · Bingrong Yu🇨🇳

   The Sommerfeld enhancement plays an important role in dark matter (DM) physics, and can significantly enhance the annihilation cross section of non-relativistic DM particles. In this paper, we study the effect of neutrino forces, which are generated by the exchange of a pair of light neutrinos, on the Sommerfeld enhancement. We demonstrate that in certain cases, a neutrino force can cause a significant correction to the Sommerfeld enhancement. Models that can realise DM-neutrino interactions and sizeable Sommerfeld enhancement are also briefly discussed, together with the impacts on DM phenomenology of neutrino forces.

   hep-phJHEP(2022)·14 citations
9. 09*

   Axion-Like Particles at High Energy Muon Colliders -- A White paper for Snowmass 2021

   Tao Han🇺🇸 · Tong Li🇨🇳 · Xing Wang🇺🇸

   We study the discovery potential for heavy axion-like particles (ALPs) and the perspectives for determining their coupling properties at a muon collider. Focusing on their couplings to the Standard Model (SM) gauge bosons $\gamma ,Z,W^{\pm }$, we show that a high-energy muon collider can substantially extend the mass coverage, essentially reaching the kinematic limit of the collider energy. The unique kinematics allow for non-ambiguous determination of the individual coupling strengths. The associated production via ${\mu }^{+}{\mu }^{-}$ annihilation and the VBF processes with the tagged outgoing muons can be utilized to verify the CP property of the ALPs. We illustrate our results for a muon collider running at 3 TeV and 10 TeV.

   hep-ph35 citations
10. 10*

    The PDF4LHC21 combination of global PDF fits for the LHC Run III

    Richard D. Ball🇬🇧 · Jon Butterworth🇬🇧 · Amanda M. Cooper-Sarkar🇬🇧 · Aurore Courtoy🇲🇽 · Thomas Cridge🇬🇧 · Albert De Roeck🇨🇭 · Joel Feltesse🇫🇷 · Stefano Forte🇮🇹 · Francesco Giuli🇨🇭 · Claire Gwenlan🇬🇧 · Lucian A. Harland-Lang🇬🇧 · T. J. Hobbs🇺🇸 and 10 other authors

    A precise knowledge of the quark and gluon structure of the proton, encoded by the parton distribution functions (PDFs), is of paramount importance for the interpretation of high-energy processes at present and future lepton-hadron and hadron-hadron colliders. Motivated by recent progress in the PDF determinations carried out by the CT, MSHT, and NNPDF groups, we present an updated combination of global PDF fits: PDF4LHC21. It is based on the Monte Carlo combination of the CT18, MSHT20, and NNPDF3.1 sets followed by either its Hessian reduction or its replica compression. Extensive benchmark studies are carried out in order to disentangle the origin of the differences between the three global PDF sets. In particular, dedicated fits based on almost identical theory settings and input datasets are performed by the three groups, highlighting the role played by the respective fitting methodologies. We compare the new PDF4LHC21 combination with its predecessor, PDF4LHC15, demonstrating their good overall consistency and a modest reduction of PDF uncertainties for key LHC processes such as electroweak gauge boson production and Higgs boson production in gluon fusion. We study the phenomenological implications of PDF4LHC21 for a representative selection of inclusive, fiducial, and differential cross sections at the LHC. The PDF4LHC21 combination is made available via the LHAPDF library and provides a robust, user-friendly, and efficient method to estimate the PDF uncertainties associated to theoretical calculations for the upcoming Run III of the LHC and beyond.

    hep-phhep-exJ.Phys.G(2022)·353 citations
11. 11*

    Phenomenology of the dark matter sector in the 2HDM extended with complex scalar singlet

    Juhi Dutta🇩🇪 · Gudrid Moortgat-Pick🇩🇪 · Merle Schreiber🇩🇪

    The two-Higgs-doublet model augmented with a complex scalar singlet (2HDMS) is a well-motivated candidate for Beyond Standard Model (BSM) Physics. We investigate the dark matter phenomenology of the 2HDMS with the complex scalar singlet as the dark matter candidate. We perform a study of the parameter space allowed by existing theoretical and experimental constraints from dark matter, flavour physics and collider searches. Further, we discuss a few benchmark scenarios to test the discovery potential for the 2HDMS at the HL-LHC and at future high-energy $e^{+}{e}^{-}$ colliders.

    hep-phEur.Phys.J.Plus(2025)·13 citations
12. 12*

    Review of Neutral Naturalness

    Brian Batell🇺🇸 · Matthew Low🇺🇸 · Ethan T. Neil🇺🇸 · Christopher B. Verhaaren🇺🇸

    The hierarchy between the mass parameter of the Higgs boson and larger mass scales becomes ever more puzzling as experiments explore higher energies. Neutral naturalness is the umbrella term for symmetry-based explanations for these hierarchies whose quark symmetry partners are not charged under the SU(3) color gauge group of the Standard Model. Though the first manifestations of this idea predate the physics runs of the Large Hadron Collider, since the Higgs discovery this paradigm has grown and developed to include a wide variety of concrete realizations with connections to intriguing collider signals. Determining the phenomenology of such models often requires the characterization - typically relying on lattice calculations - of a new confining gauge symmetry. This presents additional motivation to further develop our understanding of nonperturbative field theory as well as to pursue specific lattice studies. The wide range of suggested hidden sectors also produces a variety of dark matter candidates, intersections with astrophysics and cosmology, and ties to neutrinos and flavor. In this review, we orient the reader within both this growing collection of specific models and the physical phenomena they produce. We also survey the often less familiar dynamics of hidden-sector glueballs and quirks. In addition to providing a guide to past efforts, we reveal interesting directions for further study.

    hep-phPhys.Rept.(2026)·38 citations
13. 13*

    Non-zero ${\theta }_{13}$, CP-violation and Neutrinoless Double Beta Decay for Neutrino Mixing in the $A_4\times Z_2\times Z_3$ Flavor Symmetry Model

    Animesh Barman🇮🇳 · Ng. K. Francis🇮🇳 · Bikash Thapa🇮🇳 · Ankur Nath🇮🇳

    We study the modification of the Altarelli-Feruglio $A_4$ flavor symmetry model by adding three singlet flavons ${\xi }^{\prime }$, ${\xi }^{\prime \prime }$ and $\rho$ and the model is augmented with extra $Z_2\times Z_2^{\prime }$ symmetry to prevent the unwanted terms in our study. The addition of these three flavons lead to two higher order corrections in the form of two perturbation parameters $ϵ$ and ${ϵ}^{\prime }$. These corrections yield the deviation from exact tri-bimaximal (TBM) neutrino mixing pattern by producing a non-zero ${\theta }_{13}$ and other neutrino oscillation parameters which are consistent with the latest experimental data. In both the corrections, the neutrino masses are generated via Weinberg operator. The analysis of the perturbation parameters $ϵ$ and ${ϵ}^{\prime }$, shows that normal hierarchy (NH) and inverted hierarchy (IH) for $ϵ$ does not change much. However, as the values of ${ϵ}^{\prime }$ increases, ${\theta }_{23}$ occupies the lower octant for NH case. We further investigate the neutrinoless double beta decay parmeter $m_{\beta \beta }$ using the parameter space of the model for both normal and inverted hierarchies of neutrino masses.

    hep-phInt.J.Mod.Phys.A(2023)·5 citations
14. 14*

    B-physics anomalies: UV models

    Javier M. Lizana🇨🇭

    B-anomalies hint towards New Physics violating Lepton Flavor Universality at the TeV scale. The way they manifest points out to very particular structures for this New Physics. In this talk I review some UV-complete models to explain the B-anomalies, and possible directions these models suggest for Physics beyond the TeV scale.

    hep-ph1 citation
15. 15*

    Minimal realization of light thermal Dark Matter

    Johannes Herms🇩🇪 · Sudip Jana🇩🇪 · Vishnu P.K. · Shaikh Saad🇨🇭

    We propose a minimal UV-complete model for kinematically forbidden Dark Matter (DM) leading to a sub-GeV thermal relic. Our crucial realization is that the two-Higgs-doublet model can provide a light mediator through which the DM can annihilate into SM leptons, avoiding indirect detection constraints. The DM mass is predicted to be very close to the mass of the leptons, which can potentially be identified from DM annihilation into gamma-rays. Due to sizable couplings to muons in reproducing the DM relic abundance, this framework naturally favors a resolution to the $(g-2{)}_{\mu }$ anomaly. Furthermore, by embedding this setup to the Zee model, we show that the phenomenon of neutrino oscillations is inherently connected to the observed relic abundance of DM. All new physics involved in our framework lies at or below the electroweak scale, making it testable at upcoming colliders, beam-dump experiments, and future sub-GeV gamma-ray telescopes.

    hep-phhep-exPRL(2022)·19 citations
16. 16*

    Neutrino-Flux Variability, Nuclear-Decay Variability, and Their Apparent Relationship

    Peter A. Sturrock🇺🇸

    Homestake, Gallex and GNO data reveal variability of the solar neutrino flux. Kamiokande records for 1996-2001 reveal oscillations at 9.43 and 12.6 yr${}^{-1}$, well within a range (6-16 yr${}^{-1}$) that, according to helioseismology, may be related to internal solar rotation. A nuclear-decay experiment at Brookhaven National Laboratory (for 1982-86) reveals strong oscillations at 11.2 and 13.2 yr${}^{-1}$. Similar oscillations are found in nuclear-decay measurements conducted by A. Parkhomov. By contrast, S. Pomme points out that nuclear-decay experiments at standards laboratories tend not to exhibit variability. The most extensive series of nuclear-decay measurements comes from an experiment initiated by G. Steinitz at the Geological Survey of Israel (2007-16), which recorded 340,000 radon-related measurements from each of 3 gamma detectors and 3 environmental sensors. Analysis of a subset of 85,000 hourly gamma measurements reveals a number of oscillation frequencies compatible with influences of internal solar rotation. There is no correlation between the gamma and environmental measurements. The solar internal magnetic field may lead to neutrino modulation by the RSFP (Resonant Spin-Flavor Precession) mechanism. A triplet of oscillations (7.43, 8.43 and 9.43 yr${}^{-1}$) may be attributed to an internal region (presumably the core) with a sidereal rotation rate of 8.43 yr${}^{-1}$ and a rotation axis roughly orthogonal to that of the photosphere. This suggests that the Sun had its origin in more than one stage of condensation of interplanetary material (one on top of another), which could lead to present-day layers with different metallicities, rotation rates and axes. The peak modulation occurs near local midnight in early June, suggestive of a role of cosmic neutrinos. These neutrinos could provide the mass attributed to dark matter for a neutrino mass of order 0.1 eV.

    ↳ astro-ph.SRhep-phnucl-exSpace Sci.Rev.(2022)·3 citations
17. 17*

    The Forward Physics Facility at the High-Luminosity LHC

    Jonathan L. Feng · Felix Kling · Mary Hall Reno · Juan Rojo · Dennis Soldin · Luis A. Anchordoqui · Jamie Boyd · Ahmed Ismail · Lucian Harland-Lang · Kevin J. Kelly · Vishvas Pandey · Sebastian Trojanowski and 224 other authors

    High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.

    ↳ hep-exastro-ph.COastro-ph.HEhep-ph+1J.Phys.G(2023)·429 citations
18. 18*

    Shadow and weak deflection angle of a black hole in nonlocal gravity

    Qi-Ming Fu🇨🇳 · Shao-Wen Wei🇨🇳 · Li Zhao🇨🇳 · Yu-Xiao Liu🇨🇳 · Xin Zhang🇨🇳

    Black hole shadow and gravitational lensing play important roles in testing gravitational theories in the strong field regime. As the first-order modifications from quantum gravity, the nonlocality can be manifested by black hole shadow and gravitational lensing. For example, the cut-off parameter introduced by nonlocality will affect the shape and size of the black hole shadow, and also affect the deflection angle of light rays. In this paper, we mainly investigate the effects of the nonlocality on the black hole shadow and the gravitational lensing for two types of rotating black holes in nonlocal gravity. It is found that the size of the black hole shadow decreases with the cut-off parameter since the nonlocality weakens the gravitational constant, and the shape of the shadow gets more deformed with the increase of the cut-off parameter. However, if the rotation parameter is small, the shape of the shadow is almost a circle even though the cut-off parameter approaches its maximum. The energy emission rate in both models is also studied. The results show that there is a peak for each curve and the peak decreases and shifts to the low frequency with the increase of the cut-off parameter. Besides, we also explore the shadow of both types of black holes surrounded by a nonmagnetized pressureless plasma which satisfies the separability condition. It is found that the plasma has a frequency-dependent dispersive effect on the size and shape of the black hole shadow. For the gravitational lensing, we find that the cut-off parameter of model A makes a positive contribution to the deflection angle, which can be compared with the contribution of the rotation parameter, while the cut-off parameter of model B makes a negative contribution which can be ignored. These results may be helpful for probing nonlocal gravity in future observations.

    ↳ gr-qchep-phUniverse(2022)·14 citations
19. 19*

    Finite time effects in single and double Compton scattering

    V. Dubrovich🇷🇺 · T. Zalialiutdinov🇷🇺

    The process of Compton scattering by a free electron with subsequent reemission of one or two photons is considered in the assumption of finite interaction time. The corresponding cross sections are obtained in the framework of relativistic quantum electrodynamics using a modified form of fermion propagator with complex transmitted momentum. It is shown that finite time effects can be observable at sufficiently low energies of scattered photons. The proposed method also regularizes arising infrared divergence in the cross section of the double Compton effect. Possible experimental verification of considered theoretical approach is discussed.

    ↳ physics.atom-phastro-ph.HEhep-phJ.Exp.Theor.Phys.(2023)·0 citations
20. 20*

    Training and Projecting: A Reduced Basis Method Emulator for Many-Body Physics

    Edgard Bonilla · Pablo Giuliani🇺🇸 · Kyle Godbey🇺🇸 · Dean Lee🇺🇸

    We present the reduced basis method as a tool for developing emulators for equations with tunable parameters within the context of the nuclear many-body problem. The method uses a basis expansion informed by a set of solutions for a few values of the model parameters and then projects the equations over a well-chosen low-dimensional subspace. We connect some of the results in the eigenvector continuation literature to the formalism of reduced basis methods and show how these methods can be applied to a broad set of problems. As we illustrate, the possible success of the formalism on such problems can be diagnosed beforehand by a principal component analysis. We apply the reduced basis method to the one-dimensional Gross-Pitaevskii equation with a harmonic trapping potential and to nuclear density functional theory for ${}^{48}$Ca, achieving speed-ups of more than x150 in both cases when compared to traditional solvers. The outstanding performance of the approach, together with its straightforward implementation, show promise for its application to the emulation of computationally demanding calculations, including uncertainty quantification.

    ↳ nucl-thhep-phphysics.comp-phphysics.data-an+1PRC(2022)·70 citations
21. 21*

    Entangled sensor-networks for dark-matter searches

    Anthony J. Brady🇺🇸 · Christina Gao🇺🇸 · Roni Harnik🇺🇸 · Zhen Liu🇺🇸 · Zheshen Zhang🇺🇸 · Quntao Zhuang🇺🇸

    The hypothetical axion particle (of unknown mass) is a leading candidate for dark matter (DM). Many experiments search for axions with microwave cavities, where an axion may convert into a cavity photon, leading to a feeble excess in the output power of the cavity. Recent work [Nature 590, 238 (2021)] has demonstrated that injecting squeezed vacuum into the cavity can substantially accelerate the axion search. Here, we go beyond and provide a theoretical framework to leverage the benefits of quantum squeezing in a network setting consisting of many sensor-cavities. By forming a local sensor network, the signals among the cavities can be combined coherently to boost the axion search. Furthermore, injecting multipartite entanglement across the cavities -- generated by splitting a squeezed vacuum -- enables a global noise reduction. We explore the performance advantage of such a local, entangled sensor-network, which enjoys both coherence between the axion signals and entanglement between the sensors. Our analyses are pertinent to next-generation DM-axion searches aiming to leverage a network of sensors and quantum resources in an optimal way. Finally, we assess the possibility of using a more exotic quantum state, the Gottesman-Kitaev-Preskill (GKP) state. Despite a constant-factor improvement in the scan-time relative to a single-mode squeezed-state in the ideal case, the advantage of employing a GKP state disappears when a practical measurement scheme is considered.

    ↳ quant-phhep-phPRX Quantum(2022)·79 citations
22. 22*

    Non-metric geometry as the origin of mass in gauge theories of scale invariance

    D. M. Ghilencea🇷🇴

    We discuss gauge theories of scale invariance beyond the Standard Model (SM) and Einstein gravity. A consequence of gauging this symmetry is that their underlying 4D geometry is non-metric (${\nabla }_{\mu }{g}_{\alpha \beta }\ne 0$). Examples of such theories are Weyl's {\it original} quadratic gravity theory and its Palatini version. These theories have spontaneous breaking of the gauged scale symmetry to Einstein gravity. All mass scales have a geometric origin: the Planck scale ($M_p$), cosmological constant ($\Lambda$) and the mass of the Weyl gauge boson (${\omega }_{\mu }$) of scale symmetry are proportional to a scalar field vev that has an origin in the (geometric) ${\tilde{R}}^2$ term in the action. With ${\omega }_{\mu }$ of non-metric geometry origin, the SM Higgs field also has a similar origin, generated by Weyl boson fusion in the early Universe. This appears as a microscopic realisation of "matter creation from geometry" discussed in the thermodynamics of open systems applied to cosmology. Unlike in local scale invariant theories (no ${\omega }_{\mu }$ present) with an underlying pseudo-Riemannian geometry, in our case: 1) there are no ghosts and no additional fields beyond the SM and underlying Weyl or Palatini geometry, 2) the cosmological constant is positive and is small because gravity is weak, 3) the Weyl or Palatini connection shares the Weyl (gauge) symmetry of the action, and: 4) there exists a non-trivial, conserved Weyl current of this symmetry. An intuitive picture of non-metricity and its relation to mass generation is also provided from a solid state physics perspective where it is common and is associated with point defects (metric anomalies) of the crystalline structure.

    ↳ hep-thastro-ph.COgr-qchep-phEPJC(2023)·53 citations
23. 23*

    Novel counterexample to the Nelson-Seiberg theorem

    James Brister🇨🇳 · Zheng Sun🇨🇳

    We present a new type of counterexample to the Nelson-Seiberg theorem. It is a generic R-symmetric Wess-Zumino model with nine chiral superfields, including one field of R-charge 2 and no R-charge 0 field. As in previous counterexamples, the model gives a set of degenerate supersymmetric vacua with a non-zero expectation value for a pair of oppositely R-charged fields. However, one of these fields appears quadratically in the superpotential, and many other fields with non-zero R-charges gain non-zero expectation values at the vacuum, and so this model escapes the sufficient condition for counterexamples established in previous literature. Thus there are still open problems in the relation of R-symmetries to supersymmetry breaking in generic models.

    ↳ hep-thhep-phPRD(2022)·5 citations
24. 24*

    Searches for Long-Lived Particles at the Future FCC-ee

    J. Alimena🇨🇭 · P. Azzi🇮🇹 · M. Bauer🇬🇧 · A. Blondel🇫🇷 · M. Drewes🇧🇪 · R. Gonzalez Suarez🇸🇪 · J. Klaric🇧🇪 · S. Kulkarni🇦🇹 · O. Mikulenko🇳🇱 · M. Neubert🇩🇪 · M. Ovchynnikov🇳🇱 · C. Rizzi🇨🇭 and 6 other authors

    The electron-positron stage of the Future Circular Collider, FCC-ee, is a frontier factory for Higgs, top, electroweak, and flavour physics. It is designed to operate in a 100 km circular tunnel built at CERN, and will serve as the first step towards $\ge$ 100 TeV proton-proton collisions. In addition to an essential and unique Higgs program, it offers powerful opportunities to discover direct or indirect evidence of physics beyond the Standard Model. Direct searches for long-lived particles at FCC-ee could be particularly fertile in the high-luminosity $Z$ run, where $5\times 10^{12}$ $Z$ bosons are anticipated to be produced for the configuration with two interaction points. The high statistics of Higgs bosons, $W$ bosons and top quarks in very clean experimental conditions could offer additional opportunities at other collision energies. Three physics cases producing long-lived signatures at FCC-ee are highlighted and studied in this paper: heavy neutral leptons (HNLs), axion-like particles (ALPs), and exotic decays of the Higgs boson. These searches motivate out-of-the-box optimization of experimental conditions and analysis techniques, that could lead to improvements in other physics searches.

    ↳ hep-exhep-phhep-thFront.in Phys.(2022)·118 citations
25. 25*

    Testing Lepton Flavor Universality and CKM Unitarity with Rare Pion Decays in the PIONEER experiment

    PIONEER Collaboration: W. Altmannshofer🇺🇸 · H. Binney🇺🇸 · E. Blucher🇺🇸 · D. Bryman🇨🇦 · L. Caminada🇨🇭 · S. Chen🇨🇳 · V. Cirigliano🇺🇸 · S. Corrodi🇺🇸 · A. Crivellin🇨🇭 · S. Cuen-Rochin🇲🇽 · A. Di Canto🇺🇸 · L. Doria🇩🇪 and 48 other authors

    The physics motivation and the conceptual design of the PIONEER experiment, a next-generation rare pion decay experiment testing lepton flavor universality and CKM unitarity, are described. Phase I of the PIONEER experiment, which was proposed and approved at Paul Scherrer Institut, aims at measuring the charged-pion branching ratio to electrons vs.\ muons, $R_{e/\mu }$, 15 times more precisely than the current experimental result, reaching the precision of the Standard Model (SM) prediction at 1 part in $10^4$. Considering several inconsistencies between the SM predictions and data pointing towards the potential violation of lepton flavor universality, the PIONEER experiment will probe non-SM explanations of these anomalies through sensitivity to quantum effects of new particles up to the PeV mass scale. The later phases of the PIONEER experiment aim at improving the experimental precision of the branching ratio of pion beta decay (BRPB), ${\pi }^{+}\to {\pi }^0{e}^{+}\nu (\gamma )$, currently at $1.036(6)\times 10^{-8}$, by a factor of three (Phase II) and an order of magnitude (Phase III). Such precise measurements of BRPB will allow for tests of CKM unitarity in light of the Cabibbo Angle Anomaly and the theoretically cleanest extraction of $|V_{ud}|$ at the 0.02\% level, comparable to the deduction from superallowed beta decays.

    ↳ hep-exhep-phphysics.ins-det32 citations
26. 26*

    Model reduction methods for nuclear emulators

    J. A. Melendez🇺🇸 · C. Drischler🇺🇸 · R. J. Furnstahl🇺🇸 · A. J. Garcia🇺🇸 · Xilin Zhang🇺🇸

    The field of model order reduction (MOR) is growing in importance due to its ability to extract the key insights from complex simulations while discarding computationally burdensome and superfluous information. We provide an overview of MOR methods for the creation of fast & accurate emulators of memory- and compute-intensive nuclear systems. As an example, we describe how "eigenvector continuation" is a special case of a much more general and well-studied MOR formalism for parameterized systems. We continue with an introduction to the Ritz and Galerkin projection methods that underpin many such emulators, while pointing to the relevant MOR theory and its successful applications along the way. We believe that this will open the door to broader applications in nuclear physics and facilitate communication with practitioners in other fields.

    ↳ nucl-thhep-lathep-phphysics.data-anJ.Phys.G(2022)·64 citations
27. 27*

    neos: End-to-End-Optimised Summary Statistics for High Energy Physics

    Nathan Simpson🇸🇪 · Lukas Heinrich🇩🇪

    The advent of deep learning has yielded powerful tools to automatically compute gradients of computations. This is because training a neural network equates to iteratively updating its parameters using gradient descent to find the minimum of a loss function. Deep learning is then a subset of a broader paradigm; a workflow with free parameters that is end-to-end optimisable, provided one can keep track of the gradients all the way through. This work introduces neos: an example implementation following this paradigm of a fully differentiable high-energy physics workflow, capable of optimising a learnable summary statistic with respect to the expected sensitivity of an analysis. Doing this results in an optimisation process that is aware of the modelling and treatment of systematic uncertainties.

    ↳ physics.data-ancs.LGhep-exhep-phJ.Phys.Conf.Ser.(2023)·38 citations
28. 28*

    Constraints on Early Dark Energy from the Axion Weak Gravity Conjecture

    Tom Rudelius🇺🇸

    A popular proposal for resolving the Hubble tension involves an early phase of dark energy, driven by an axion field with a periodic potential. In this paper, we argue that these models are tightly constrained by the axion weak gravity conjecture: for typical parameter values, the axion decay constant must satisfy $f<0.008M_{\text{Pl}}$, which is smaller than the axion decay constants appearing in the vast majority of early dark energy models to date. We discuss possible ways to evade or loosen this constraint, arguing that its loopholes are small and difficult to thread. This suggests that it may prove challenging to realize early dark energy models in a UV complete theory of quantum gravity.

    ↳ hep-thastro-ph.COhep-phJCAP(2023)·35 citations
29. 29*

    Quantum information with top quarks in QCD

    Yoav Afik🇨🇭 · Juan Ramón Muñoz de Nova🇪🇸

    Top quarks represent unique high-energy systems since their spin correlations can be measured, thus allowing to study fundamental aspects of quantum mechanics with qubits at high-energy colliders. We present here the general framework of the quantum state of a top-antitop ($t\bar{t}$) quark pair produced through quantum chromodynamics (QCD) in a high-energy collider. We argue that, in general, the total quantum state that can be probed in a collider is given in terms of the production spin density matrix, which necessarily gives rise to a mixed state. We compute the quantum state of a $t\bar{t}$ pair produced from the most elementary QCD processes, finding the presence of entanglement and CHSH violation in different regions of phase space. We show that any realistic hadronic production of a $t\bar{t}$ pair is a statistical mixture of these elementary QCD processes. We focus on the experimentally relevant cases of proton-proton and proton-antiproton collisions, performed at the LHC and the Tevatron, analyzing the dependence of the quantum state with the energy of the collisions. We provide experimental observables for entanglement and CHSH-violation signatures. At the LHC, these signatures are given by the measurement of a single observable, which in the case of entanglement represents the violation of a Cauchy-Schwarz inequality. We extend the validity of the quantum tomography protocol for the $t\bar{t}$ pair proposed in the literature to more general quantum states, and for any production mechanism. Finally, we argue that a CHSH violation measured in a collider is only a weak form of violation of Bell's theorem, necessarily containing a number of loopholes.

    ↳ quant-phhep-phhep-thQuantum(2022)·188 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.