Fri·Mar 25, 2022Friday·March 25, 2022

1. 01*

   Towards a Deep Learning Model for Hadronization

   Aishik Ghosh🇺🇸 · Xiangyang Ju🇺🇸 · Benjamin Nachman🇺🇸 · Andrzej Siodmok🇵🇱

   Hadronization is a complex quantum process whereby quarks and gluons become hadrons. The widely-used models of hadronization in event generators are based on physically-inspired phenomenological models with many free parameters. We propose an alternative approach whereby neural networks are used instead. Deep generative models are highly flexible, differentiable, and compatible with Graphical Processing Unit (GPUs). We make the first step towards a data-driven machine learning-based hadronization model by replacing a compont of the hadronization model within the Herwig event generator (cluster model) with a Generative Adversarial Network (GAN). We show that a GAN is capable of reproducing the kinematic properties of cluster decays. Furthermore, we integrate this model into Herwig to generate entire events that can be compared with the output of the public Herwig simulator as well as with $e^{+}{e}^{-}$ data.

   hep-phhep-exphysics.data-anPRD(2022)·52 citations
2. 02*

   Triple Higgs Couplings in the 2HDM: The Complete Picture

   F. Arco🇪🇸 · S. Heinemeyer🇪🇸 · M.J. Herrero🇪🇸

   The measurement of the triple Higgs coupling is one of the main tasks of the (HL-)LHC and future lepton colliders. Similarly, triple Higgs couplings involving BSM Higgs bosons are of high interest. Within the framework of Two Higgs Doublet Models (2HDM) we investigate the allowed ranges for all triple Higgs couplings involving at least one light, SM-like Higgs boson. We present newly the allowed ranges for 2HDM type III and IV and update the results within the type I and II. We take into account theoretical constraints from unitarity and stability, experimental constraints from direct BSM Higgs-boson searches, measurements of the rates of the SM-like Higgs-boson at the LHC, as well as flavor observables and electroweak precision data. For the SM-type triple Higgs coupling w.r.t. its SM value, ${\lambda }_{hhh}/{\lambda }_{hhh}^{\mathrm{SM}}$, we find allowed intervals of $\sim [-0.5,1.3]$ in type~I and $\sim [0.5,1.0]$ in the other Yukawa types. These allowed ranges have important implications for the experimental determination of this coupling at future collider experiments. We find the coupling ${\lambda }_{hhH}$ between $\sim -1.5$ and $\sim +1.5$ in the four Yukawa types. For the triple Higgs couplings involving two heavy neutral Higgs bosons, ${\lambda }_{hHH}$ and ${\lambda }_{hAA}$ we find values between $\sim -0.5$ and $\sim 16$, and between $\sim -1$ and $\sim 32$ for ${\lambda }_{h{H}^{+}{H}^{-}}$. These potentially large values could lead to strongly enhanced production of two Higgs-bosons at the HL-LHC or high-energy lepton colliders.

   hep-phEPJC(2022)·29 citations
3. 03*

   Rocks, Water and Noble Liquids: Unfolding the Flavor Contents of Supernova Neutrinos

   Sebastian Baum🇺🇸 · Francesco Capozzi🇺🇸 · Shunsaku Horiuchi🇺🇸

   Measuring core-collapse supernova neutrinos, both from individual supernovae within the Milky Way and from past core collapses throughout the Universe (the diffuse supernova neutrino background, or DSNB), is one of the main goals of current and next generation neutrino experiments. Detecting the heavy-lepton flavor (muon and tau types, collectively ${\nu }_x$) component of the flux is particularly challenging due to small statistics and large backgrounds. While the next galactic neutrino burst will be observed in a plethora of neutrino channels, allowing to measure a small number of ${\nu }_x$ events, only upper limits are anticipated for the diffuse ${\nu }_x$ flux even after decades of data taking with conventional detectors. However, paleo-detectors could measure the time-integrated flux of neutrinos from galactic core-collapse supernovae via flavor-blind neutral current interactions. In this work, we show how combining a measurement of the average galactic core-collapse supernova flux with paleo detectors and measurements of the DSNB electron-type neutrino fluxes with the next-generation water Cherenkov detector Hyper-Kamiokande and the liquid noble gas detector DUNE will allow to determine the mean supernova ${\nu }_x$ flux parameters with precision of order ten percent.

   hep-phastro-ph.GAastro-ph.HEhep-exPRD(2022)·18 citations
4. 04*

   Searches for New Particles, Dark Matter, and Gravitational Waves with SRF Cavities

   Asher Berlin🇺🇸 · Sergey Belomestnykh🇺🇸 · Diego Blas🇪🇸 · Daniil Frolov🇺🇸 · Anthony J. Brady🇺🇸 · Caterina Braggio🇮🇹 · Marcela Carena🇺🇸 · Raphael Cervantes🇺🇸 · Mattia Checchin🇺🇸 · Crispin Contreras-Martinez🇺🇸 · Raffaele Tito D'Agnolo🇫🇷 · Sebastian A. R. Ellis🇨🇭 and 24 other authors

   This is a Snowmass white paper on the utility of existing and future superconducting cavities to probe fundamental physics. Superconducting radio frequency (SRF) cavity technology has seen tremendous progress in the past decades, as a tool for accelerator science. With advances spear-headed by the SQMS center at Fermilab, they are now being brought to the quantum regime becoming a tool in quantum science thanks to the high degree of coherence. The same high quality factor can be leveraged in the search for new physics, including searches for new particles, dark matter, including the QCD axion, and gravitational waves. We survey some of the physics opportunities and the required directions of R&D. Given the already demonstrated integration of SRF cavities in large accelerator systems, this R&D may enable larger scale searches by dedicated experiments.

   hep-phhep-ex61 citations
5. 05*

   A new method for measurement of the Michel parameters that describe the daughter muon polarization in the ${\tau }^{-}\to {\mu }^{-}{\bar{\nu }}_{\mu }{\nu }_{\tau }$ decay

   D. Bodrov🇷🇺 · P. Pakhlov🇷🇺

   This paper provides a detailed description of the method for the first direct measurement of all Michel parameters in the ${\tau }^{-}\to {\mu }^{-}{\bar{\nu }}_{\mu }{\nu }_{\tau }$ decay related to the polarization of the daughter muon. An application of the suggested method in the existing and future experiments at $e^{+}{e}^{-}$ colliders is considered. We have performed a feasibility study for the future Super Charm-Tau Factory and Belle II experiments. For the first one, the sensitivity to the Michel parameters ${\xi }^{\prime }$, ${\xi }^{\prime \prime }$, ${\eta }^{\prime \prime }$, ${\alpha }^{\prime }/A$, and ${\beta }^{\prime }/A$ is estimated. For the latter, only one Michel parameter, ${\xi }^{\prime }$, for which the sensitivity is maximum, is considered.

   hep-phJHEP(2022)·11 citations
6. 06*

   COSE$\nu$: A Collective Oscillation Simulation Engine for Neutrinos

   Manu George🇹🇼 · Chun-Yu Lin🇹🇼 · Meng-Ru Wu🇹🇼 · Tony G. Liu🇹🇼 · Zewei Xiong🇩🇪

   We introduce the implementation details of the simulation code \cosenu, which numerically solves a set of non-linear partial differential equations that govern the dynamics of neutrino collective flavor conversions. We systematically provide the details of both the finite difference method supported by Kreiss-Oliger dissipation and the finite volume method with seventh order weighted essentially non-oscillatory scheme. To ensure the reliability of the code, we perform the comparison of the simulation results with theoretically obtainable solutions. In order to understand and characterize the error accumulation behavior of the implementations when neutrino self-interactions are switched on, we also analyze the evolution of the deviation of the conserved quantities for different values of simulation parameters. We report the performance of our code with both CPUs and GPUs. The public version of the \cosenu~package is available at \url{https://github.com/COSEnu/COSEnu}.

   hep-phastro-ph.HEphysics.comp-phComput.Phys.Commun.(2023)·24 citations
7. 07*

   Application of deep learning in top pair and single top quark production at the LHC

   Ijaz Ahmed🇵🇰 · Anwar Zada🇵🇰 · Muhammad Waqas🇵🇰 · M. U. Ashraf🇵🇰

   We demonstrate the performance of a very efficient tagger applies on hadronically decaying top quark pairs as signal based on deep neural network algorithms and compares with the QCD multi-jet background events. A significant enhancement of performance in boosted top quark events is observed with our limited computing resources. We also compare modern machine learning approaches and perform a multivariate analysis of boosted top-pair as well as single top quark production through weak interaction at $\sqrt{s}=$14 TeV proton-proton Collider. The most relevant known background processes are incorporated. Through the techniques of Boosted Decision Tree (BDT), likelihood and Multlayer Perceptron (MLP) the analysis is trained to observe the performance in comparison with the conventional cut based and count approach.

   hep-phEur.Phys.J.Plus(2023)·5 citations
8. 08*

   The semileptonic $B_s$ and ${\Lambda }_b$ widths

   Marzia Bordone🇨🇭 · Paolo Gambino🇮🇹

   We present estimates of the semileptonic widths of the $B_s$ and ${\Lambda }_b$ hadrons. We employ the latest fit to the $B$ inclusive semileptonic data, the heavy quark expansion and lattice QCD results. Our results suffer from large uncertainties that could be reduced with dedicated measurements and new lattice QCD calculations.

   hep-phhep-exPoS(2023)·8 citations
9. 09*

   Bremsstrahlung in chiral medium: anomalous magnetic contribution to the Bethe-Heitler formula

   Jeremy Hansen🇺🇸 · Kirill Tuchin🇺🇸

   We investigate photon bremsstrahlung in chiral media. The chiral medium response to the magnetic field is described by the chiral magnetic current $j=b_{0}B$, where $b_0$ is the chiral magnetic conductivity. This current modifies the photon dispersion relation producing a resonance in the scattering amplitude. We show that the resonant contribution is proportional to the magnetic moment $\mu$ of the target nucleus. We analytically compute the corresponding cross section. We argue that the anomalous contribution is enhanced by a factor $b_0^2/{\Gamma }^2$, where $\Gamma$ is a width of the resonance related to the chiral magnetic instability of the electromagnetic field. The most conspicuous feature of the anomalous contribution to the photon spectrum is the emergence of the knee-like structure at photon energies proportional to $b_0$. We argue that the phenomenological significance of the anomalous terms depends on the magnitude of the ratio of $b_0$ to the projectile fermion mass.

   hep-phPRD(2022)·8 citations
10. 10*

    Emergence of periodic in magnetic moment effective QED action

    Stefan Evans🇺🇸 · Johann Rafelski🇺🇸

    We evaluate for the inhomogeneous static electric Sauter step potential the imaginary part of the emerging homogeneous in electric field effective Euler-Heisenberg-Schwinger action sourced by vacuum fluctuations of a charged particle with magnetic moment of arbitrary strength. The result is convergent for all values of gyromagnetic ratio $g$, periodic in $g$, with a cusp at $g=2$. We consider the relation to the QED beta-function which is also found to be periodic in $g$. We confirm presence of asymptotic freedom conditions using this novel method and document a wider range of $g$-values for which asymptotic freedom is present.

    hep-phPLB(2022)·5 citations
11. 11*

    Mounting evidence for a 95 GeV Higgs boson

    Thomas Biekötter🇩🇪 · Sven Heinemeyer🇪🇸 · Georg Weiglein🇩🇪

    In 2018 CMS reported an excess in the light Higgs-boson search in the diphoton decay mode at about 95GeV based on Run 1 and first year Run 2 data. The combined local significance of the excess was $2.8\sigma$. The excess is compatible with the limits obtained in the ATLAS searches from the diphoton search channel. Recently, CMS reported another local excess with a significance of $3.1\sigma$ in the light Higgs-boson search in the di-tau final state, which is compatible with the interpretation of a Higgs boson with a mass of about 95GeV. We show that the observed results can be interpreted as manifestations of a Higgs boson in the Two-Higgs Doublet Model with an additional real singlet (N2HDM). We find that the lightest Higgs boson of the N2HDM can fit both excesses simultaneously, while the second-lightest state is such that it satisfies the Higgs-boson measurements at 125GeV, and the full Higgs-boson sector is compatible with all Higgs exclusion bounds from the searches at LEP, the Tevatron and the LHC as well as with other theoretical and experimental constraints. Finally, we demonstrate that it is furthermore possible to accommodate the excesses observed by CMS in the two search channels together with a local $2.3\sigma$ excess in the $b\bar{b}$ final state observed at LEP in the same mass range.

    hep-phJHEP(2022)·86 citations
12. 12*

    Snowmass 2021 White Paper: Electron Ion Collider for High Energy Physics

    R. Abdul Khalek🇺🇸 · U. D'Alesio🇮🇹 · M. Arratia🇺🇸 · A. Bacchetta🇮🇹 · M. Battaglieri🇮🇹 · M. Begel🇺🇸 · M. Boglione🇮🇹 · R. Boughezal🇺🇸 · R. Boussarie🇫🇷 · G. Bozzi🇮🇹 · S. V. Chekanov🇺🇸 · F. G. Celiberto🇮🇹 and 96 other authors

    Electron Ion Collider (EIC) is a particle accelerator facility planned for construction at Brookhaven National Laboratory on Long Island, New York by the United States Department of Energy. EIC will provide capabilities of colliding beams of polarized electrons with polarized beams of proton and light ions. EIC will be one of the largest and most sophisticated new accelerator facilities worldwide, and the only new large-scale accelerator facility planned for construction in the United States in the next few decades. The versatility, resolving power and intensity of EIC will present many new opportunities to address some of the crucial and fundamental open scientific questions in particle physics. This document provides an overview of the science case of EIC from the perspective of the high energy physics community.

    hep-phhep-exnucl-exnucl-th201 citations
13. 13*

    A global analysis of $b\to s\ell \ell$ data in heavy and light $Z^{\prime }$ models

    Ashutosh Kumar Alok🇮🇳 · Neetu Raj Singh Chundawat🇮🇳 · Shireen Gangal🇫🇷 · Dinesh Kumar🇮🇳

    We perform a model-independent global fit to all $b\to s\ell \ell$ data in the light of recent measurements of the lepton flavour universality violating (LFUV) observables $R_{K_S^0}$ and $R_{K^{\ast +}}$ as well as the updated measurements of observables in $B_s\to \varphi {\mu }^{+}{\mu }^{-}$ decay, by the LHCb collaboration. We obtain new physics (NP) solutions to the current anomalies in the data, assuming NP in the muon sector only. We find that the 1D NP scenarios $C_9^{\mathrm{NP}}<0$ and $C_9^{\mathrm{NP}}=-C_{10}^{\mathrm{NP}}$ continue to be the most favoured ones. However, the significance of the then favoured scenario $C_9^{\mathrm{NP}}=-C_9^{\prime }$ has reduced and the updated data now marginally prefers $C_{10}^{\mathrm{NP}}$ scenario over $C_9^{\mathrm{NP}}=-C_9^{\prime }$. The 2D scenarios $(C_9^{\mathrm{NP}},C_{10}^{\prime })$, $(C_9^{\mathrm{NP}},C_9^{\prime })$ and $(C_9^{\mathrm{NP}},C_{10}^{\mathrm{NP}})$, continue to be favoured by the data in the listed order. We also analyse generic TeV scale $Z^{\prime }$ models which can generate the favored 1D scenarios, $C_9^{\mathrm{NP}}$ and $C_9^{\mathrm{NP}}=-C_{10}^{\mathrm{NP}}$ along with the 2D NP scenarios $(C_9^{\mathrm{NP}},C_9^{\prime })$ and $(C_9^{\mathrm{NP}},C_{10}^{\mathrm{NP}})$. Using the additional constraints from $B_s-\overline{B_s}$ mixing and neutrino trident data, we find that all four models provide an equally good fit to the data. Further, we consider a model with a 25 MeV $Z^{\prime }$ that couples to muons and has a $q^2$ dependent $b-s$ coupling. We also study the implications of the current data on the LFUV observable $R_{\varphi }$, $Q_{4,5}$ along with $R_{K^{(\ast )}}$ in the high $q^2$. We find that a precise measurements of these observables can provide a good discrimination between a few favored model-independent solutions, and have a potential to disentangle different heavy and light $Z^{\prime }$ scenarios considered in this work.

    hep-phhep-exEPJC(2022)·27 citations
14. 14*

    Probing pre-BBN era with Scale Invariant FIMP

    Basabendu Barman🇨🇴 · Anish Ghoshal🇵🇱

    Detecting dark matter (DM) relic via freeze-in is difficult in laboratories due to smallness of the couplings involved. However, a non-standard cosmological history of the Universe, prior to Big Bang Nucleosynthesis (BBN), can dramatically change this scenario. In this context, we study the freeze-in production of dark matter in classically scale invariant $U(1{)}_X$ gauge extension of the Standard Model (SM), recently dubbed as the \textit{Scale Invariant FIMP Miracle}. We assume an additional species dominates the energy density of the Universe at early times, causing the expansion rate at a given temperature to be larger than that in the standard radiation-dominated case. We find, the \textit{out-of-equilibrium} scattering processes involving particles in the thermal bath lead to significantly suppressed DM production in this era, thereby enhancing the couplings between the visible and the dark sector (by several orders of magnitude) to satisfy the observed DM abundance, and improving the detection prospects for freeze-in in turn. Scale invariance of the underlying theory leaves only four free parameters in the model: the DM mass $m_X$, the gauge coupling $g_X$, the temperature of transition $T_R$ from early scalar-dominated to radiation-dominated era and the power-law dependence $n$ of this temperature. We show, within this minimal set-up, experiments like FASER, MATHUSLA, DUNE, SHiP will be probing various cosmological models depending on the choice of $\{n,T_R\}$ that also satisfy the PLANCK observed relic density bound. Moreover, due to the presence of a naturally light scalar mediator, the direct detection of the DM at XENON1T, PandaX-4T or XENONnT becomes relevant for Higgs-scalar mixing $\sin \theta \simeq \{10^{-5}-10^{-3}\}$, thus providing complementary probes for freeze-in, as well as for non-standard cosmological pre-BBN era.

    hep-phJCAP(2022)·25 citations
15. 15*

    Impact of event activity variable on the ratio of observables in isobar collisions

    Jiangyong Jia🇺🇸 · Gang Wang🇺🇸 · Chunjian Zhang🇺🇸

    The STAR isobar data of ${}^{96}$Ru+${}^{96}$Ru and ${}^{96}$Zr+${}^{96}$Zr collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV show that ratios of observables ($R_{\mathcal{O}}$) such as the multiplicity distribution, $p(N_{\mathrm{ch}})$, and the harmonic flow, $v_n$, deviate from unity, when presented as a function of centrality, $c$. These deviations have been attributed to the differences in the shape and radial profiles between ${}^{96}$Ru and ${}^{96}$Zr nuclei. In addition, the ratios $R_{\mathcal{O}}(x)$ depend on the choice of the event activity variable $x$, which could be either $N_{\mathrm{ch}}$ or centrality. We estimate the difference $\Delta R$ between these two choices, based on the published $p(N_{\mathrm{ch}})$, as well as those from a multiphase transport (AMPT) model with varied nuclear structure parameters: nuclear radius ($R_0$), surface diffuseness ($a_0$), quadrupole deformation (${\beta }_2$), and octupole deformation (${\beta }_3$). In contrary to $R_{v_n}(c)$, $R_{v_n}(N_{\mathrm{ch}})$ is nearly independent of the analysis approaches, suggesting that nonflow effects are better controlled by $N_{\mathrm{ch}}$ than $c$. The ratios of observables sensitive to the chiral magnetic effect (CME) are also much closer to unity for $x=N_{\mathrm{ch}}$ than $x=c$, indicating that the ratios calculated at the same $N_{\mathrm{ch}}$ provide a better baseline for the non-CME background. According to the AMPT results, the dominant parameter for $\Delta R$ is $a_0$, while $R_0$ and ${\beta }_n$ are only important in central collisions. The published $p(N_{\mathrm{ch}})$ is also used to estimate $\Delta R_{⟨p_{\mathrm{T}}⟩}$ for mean transverse momentum, which is non-negligible compared with $R_{⟨p_{\mathrm{T}}⟩}-1$.

    ↳ nucl-thhep-phnucl-exPLB(2022)·11 citations
16. 16*

    No evidence for EDE from Planck data in extended scenarios

    Emanuele Fondi🇪🇸 · Alessandro Melchiorri🇮🇹 · Luca Pagano🇮🇹

    The latest data release from the ACT CMB experiment (in combination with previous WMAP data) shows evidence for an Early Dark Energy component at more than $3$ standard deviations. The same conclusion has been recently shown to hold when temperature data from the Planck experiment limited to intermediate angular scales ($l\le 650$) are included while it vanishes when the full Planck dataset is considered. However, it has been shown that the full Planck dataset exhibits an anomalous lensing component and a preference for a closed universe at the level of three standard deviation. It is therefore of utmost importance to investigate if these anomalies could anti-correlate with an early dark energy component and hide its presence during the process of parameter extraction. Here we demonstrate that extended parameters choices as curvature, equation of state of dark energy and lensing amplitude $A_L$ have no impact on the Planck constraints on EDE. In practice, EDE does not solve Planck angular spectra anomalies. This indicates that current CMB evidence for an EDE component comes essentially from the ACT-DR4 dataset.

    ↳ astro-ph.COgr-qchep-phJHEAp(2023)·15 citations
17. 17*

    The SAGEX Review on Scattering Amplitudes

    Gabriele Travaglini🇬🇧 · Andreas Brandhuber🇬🇧 · Patrick Dorey🇬🇧 · Tristan McLoughlin🇮🇪 · Samuel Abreu🇨🇭 · Zvi Bern🇺🇸 · N. Emil J. Bjerrum-Bohr🇩🇰 · Johannes Blümlein🇩🇪 · Ruth Britto🇮🇪 · John Joseph M. Carrasco🇺🇸 · Dmitry Chicherin🇫🇷 · Marco Chiodaroli🇸🇪 and 26 other authors

    This is an introduction to, and invitation to read, a series of review articles on scattering amplitudes in gauge theory, gravity, and superstring theory. Our aim is to provide an overview of the field, from basic aspects to a selection of current (2022) research and developments.

    ↳ hep-thgr-qchep-exhep-phJ.Phys.A(2022)·173 citations
18. 18*

    The SAGEX Review on Scattering Amplitudes, Chapter 1: Modern Fundamentals of Amplitudes

    Andreas Brandhuber🇬🇧 · Jan Plefka🇩🇪 · Gabriele Travaglini🇬🇧

    This chapter introduces the foundational elements of scattering amplitudes. It is meant to be accessible to readers with only a basic understanding of quantum field theory. Topics covered include: the four-dimensional spinor-helicity formalism and the colour decomposition of Yang-Mills scattering amplitudes; the study of soft and collinear limits of Yang-Mills and gravity amplitudes; the BCFW recursion relation and generalised unitarity, also in the superamplitudes formalism of $\mathcal{N}=4$ supersymmetric Yang-Mills; an overview of standard and hidden symmetries of the $S$-matrix of $\mathcal{N}=4$ supersymmetric Yang-Mills, such as the conformal, dual conformal and Yangian symmetries; and a brief excursus on form factors of protected and non-protected operators in Yang-Mills theory. Several examples and explicit calculations are also provided.

    ↳ hep-thgr-qchep-exhep-phJ.Phys.A(2022)·27 citations
19. 19*

    The SAGEX Review on Scattering Amplitudes, Chapter 2: An Invitation to Color-Kinematics Duality and the Double Copy

    Zvi Bern🇺🇸 · John Joseph Carrasco🇺🇸 · Marco Chiodaroli🇸🇪 · Henrik Johansson🇸🇪 · Radu Roiban🇺🇸

    Advances in scattering amplitudes have exposed previously-hidden color-kinematics and double-copy structures in theories ranging from gauge and gravity theories to effective field theories such as chiral perturbation theory and the Born-Infeld model. These novel structures both simplify higher-order calculations and pose tantalizing questions related to a unified framework underlying relativistic quantum theories. This introductory mini-review article invites further exploration of these topics. After a brief introduction to color-kinematics duality and the double copy as they emerges at tree and loop-level in gauge and gravity theories, we present two distinct examples: 1) an introduction to the web of double-copy-constructible theories, and 2) a discussion on the application of the double copy to calculation relevant to gravitational-wave physics.

    ↳ hep-thgr-qchep-phJ.Phys.A(2022)·146 citations
20. 20*

    The SAGEX Review on Scattering Amplitudes, Chapter 3: Mathematical structures in Feynman integrals

    Samuel Abreu🇨🇭 · Ruth Britto🇮🇪 · Claude Duhr🇩🇪

    Dimensionally-regulated Feynman integrals are a cornerstone of all perturbative computations in quantum field theory. They are known to exhibit a rich mathematical structure, which has led to the development of powerful new techniques for their computation. We review some of the most recent advances in our understanding of the analytic structure of multiloop Feynman integrals in dimensional regularisation. In particular, we give an overview of modern approaches to computing Feynman integrals using differential equations, and we discuss some of the properties of the functions that appear in the solutions. We then review how dimensional regularisation has a natural mathematical interpretation in terms of the theory of twisted cohomology groups, and how many of the well-known ideas about Feynman integrals arise naturally in this context. This is Chapter 3 of a series of review articles on scattering amplitudes, of which Chapter 0 [arXiv:2203.13011] presents an overview and Chapter 4 [arXiv:2203.13015] contains closely related topics.

    ↳ hep-thhep-phJ.Phys.A(2022)·97 citations
21. 21*

    The SAGEX Review on Scattering Amplitudes, Chapter 4: Multi-loop Feynman Integrals

    Johannes Blümlein🇩🇪 · Carsten Schneider🇦🇹

    The analytic integration and simplification of multi-loop Feynman integrals to special functions and constants plays an important role to perform higher order perturbative calculations in the Standard Model of elementary particles. In this survey article the most recent and relevant computer algebra and special function algorithms are presented that are currently used or that may play an important role to perform such challenging precision calculations in the future. They are discussed in the context of analytic zero, single and double scale calculations in the Quantum Field Theories of the Standard Model and effective field theories, also with classical applications. These calculations play a central role in the analysis of precision measurements at present and future colliders to obtain ultimate information for fundamental physics.

    ↳ hep-thcs.SChep-phJ.Phys.A(2022)·32 citations
22. 22*

    The SAGEX Review on Scattering Amplitudes, Chapter 5: Analytic Bootstraps for Scattering Amplitudes and Beyond

    Georgios Papathanasiou🇩🇪

    One of the main challenges in obtaining predictions for collider experiments from perturbative quantum field theory, is the direct evaluation of the Feynman integrals it gives rise to. In this chapter, we review an alternative bootstrap method that instead efficiently constructs physical quantities by exploiting their analytic structure. We present in detail the setting where this method has been originally developed, six- and seven-particle amplitudes in the large-color limit of $\mathcal{N}=4$ super Yang-Mills theory. We discuss the class of functions these amplitudes belong to, and the strong clues mathematical objects known as cluster algebras provide for rendering this function space both finite and of relatively small dimension at each loop order. We then describe how to construct this function space, as well as how to locate the amplitude inside of it with the help of kinematic limits, and apply the general procedure to a concrete example: The determination of the two-loop correction to the first nontrivial six-particle amplitude. We also provide an overview of other areas where the realm of the bootstrap paradigm is expanding, including other scattering amplitudes, form factors and Feynman integrals, and point out the analytic properties of potentially wider applicability that it has revealed.

    ↳ hep-thhep-phJ.Phys.A(2022)·17 citations
23. 23*

    The SAGEX Review on Scattering Amplitudes, Chapter 6: Ambitwistor Strings and Amplitudes from the Worldsheet

    Yvonne Geyer🇹🇭 · Lionel Mason🇬🇧

    Starting with Witten's twistor string, chiral string theories have emerged that describe field theory amplitudes without the towers of massive states of conventional strings. These models are known as ambitwistor strings due to their target space; the space of complexified null geodesics, also called ambitwistor space. Correlators in these string theories directly yield compact formulae for tree-level amplitudes and loop integrands, in the form of worldsheet integrals fully localized on solutions to constraints known as the scattering equations. In this chapter, we discuss two incarnations of the ambitwistor string: a 'vector representation' starting in space-time and structurally resembling the RNS superstring, and a four-dimensional twistorial version closely related to, but distinct from Witten's original model. The RNS-like models exist for several theories, with 'heterotic' and type II models describing super-Yang-Mills and 10d supergravities respectively, and they manifest the double copy relations directly at the level of the worldsheet models. In the second half of the chapter, we explain how the underlying models lead to diverse applications, ranging from extensions to new sectors of theories, loop amplitudes and to scattering on curved backgrounds. We conclude with a brief discussion of connections to conventional strings and celestial holography.

    ↳ hep-thgr-qchep-phmath-ph+1J.Phys.A(2022)·31 citations
24. 24*

    The SAGEX Review on Scattering Amplitudes, Chapter 12: Amplitudes and collider physics

    Chris D. White🇬🇧

    We explore how various topics in modern scattering amplitudes research find application in the description of collider physics processes. After a brief review of experimentally measured quantities and how they are related to amplitudes, we summarise recent developments in perturbative QFT, and how they have impacted our ability to do precision physics with colliders. Next, we explain how the study of (next-to-)soft radiation is directly relevant to increasing theoretical precision for key processes at the LHC and related experiments. Finally, we describe the various techniques that are used to turn theoretical calculations into something more closely approaching the output of a particle accelerator.

    ↳ hep-thhep-exhep-phJ.Phys.A(2022)·8 citations
25. 25*

    The SAGEX Review on Scattering Amplitudes, Chapter 13: Post-Minkowskian expansion from Scattering Amplitudes

    N.E.J. Bjerrum-Bohr🇩🇰 · P.H. Damgaard🇩🇰 · L. Plante🇩🇰 · P. Vanhove🇫🇷

    The post-Minkowskian expansion of Einstein's general theory of relativity has received much attention in recent years due to the possibility of harnessing the computational power of modern amplitude calculations in such a classical context. In this brief review, we focus on the post-Minkowskian expansion as applied to the two-body problem in general relativity without spin, and we describe how relativistic quantum field theory can be used to greatly simplify analytical calculations based on the Einstein-Hilbert action. Subtleties related to the extraction of classical physics from such quantum mechanical calculations highlight the care which must be taken when both positive and negative powers of Planck's constant are at play. In the process of obtaining classical results in both Einstein gravity and supergravity, one learns new aspects of quantum field theory that are obscured when using units in which Planck's constant is set to unity. The scattering amplitude approach provides a self-contained framework for deriving the two-body scattering valid in all regimes of energy. There is hope that the full impact of amplitude computations in this field may significantly alter the way in which gravitational wave predictions will advance in the coming years.

    ↳ hep-thgr-qchep-phJ.Phys.A(2022)·130 citations
26. 26*

    The SAGEX Review on Scattering Amplitudes, Chapter 15: The Multi-Regge Limit

    Vittorio Del Duca🇨🇭 · Lance J. Dixon🇺🇸

    We review the Regge and multi-Regge limit of scattering amplitudes in gauge theory, focusing on QCD and its maximally supersymmetric cousin, planar $\mathcal{N}=4$ super-Yang-Mills theory. We identify the large logarithms that are developed in these limits, and the progress that has been made in resumming them, towards next-to-next-to-leading logarithms for BFKL evolution in QCD, as well as all-orders proposals in planar $\mathcal{N}=4$ super-Yang-Mills theory and the perturbative checks of those proposals. We also cover the application of single-valued multiple polylogarithms to this important kinematical limit of particle scattering.

    ↳ hep-thhep-phJ.Phys.A(2022)·18 citations
27. 27*

    Deuteron VVCS and nuclear structure effects in muonic deuterium at N3LO in pionless EFT

    Vadim Lensky🇩🇪 · Franziska Hagelstein🇨🇭 · Astrid Hiller Blin🇩🇪 · Vladimir Pascalutsa🇩🇪

    We present our studies of the forward unpolarised doubly-virtual Compton scattering (VVCS) off the deuteron and the closely related two-photon-exchange ($2\gamma$-exchange) corrections to the Lamb shift of muonic deuterium. The deuteron VVCS amplitude is calculated in the framework of pionless effective field theory, up to next-to-next-to-next-to-leading order (N3LO) for the longitudinal and next-to-leading order (NLO) for the transverse amplitude. The charge elastic form factor of the deuteron, obtained from the residue of the longitudinal VVCS amplitude, is used to extract the value of the single unknown two-nucleon one-photon contact coupling that enters the longitudinal amplitude at N3LO. The obtained deuteron VVCS amplitude serves as a high-precision model-independent input to examine the $2\gamma$-exchange corrections. Substantial differences with the recent dispersive evaluations are identified, namely, the elastic contribution appears to be larger by several standard deviations, thus ameliorating the current discrepancy between theory and experiment on the size of $2\gamma$-exchange effects. A correlation between the values of the deuteron charge and Friar radii is found that can be used to judge on the quality of a parametrisation of the deuteron charge elastic form factor. The discrepancy between the theory and the empirical result for the $2\gamma$-exchange correction in muonic deuterium appears to be completely eliminated. To further confirm this, we revisit the hydrogen-deuterium isotope shift in the same framework. Our work provides an alternative self-consistent and high-precision evaluation of the $2\gamma$-exchange correction in (muonic) deuterium.

    ↳ nucl-thhep-phnucl-exPoS(2024)·1 citation
28. 28*

    New determination of the production cross section for secondary positrons and electrons in the Galaxy

    Luca Orusa🇮🇹 · Mattia Di Mauro🇮🇹 · Fiorenza Donato🇮🇹 · Michael Korsmeier🇸🇪

    The cosmic-ray fluxes of electrons and positrons ($e^{\pm }$) are measured with high precision by the space-borne particle spectrometer AMS-02. To infer a precise interpretation of the production processes for $e^{\pm }$ in our Galaxy, it is necessary to have an accurate description of the secondary component, produced by the interaction of cosmic-ray proton and helium with the interstellar medium atoms. We determine new analytical functions of the Lorentz invariant cross section for the production of ${\pi }^{\pm }$ and $K^{\pm }$ by fitting data from collider experiments. We also evaluate the invariant cross sections for several other channels, involving for example hyperon decays, contributing at the few \% level on the total cross section. For all these particles, the relevant 2 and 3 body decay channels are implemented, with the polarized ${\mu }^{\pm }$ decay computed with next-to-leading order corrections. The cross section for scattering of nuclei heavier than protons is modeled by fitting data on $p+C$ collisions. The total differential cross section $d\sigma /d{T}_{e^{\pm }}(p+p\to e^{\pm }+X)$ is predicted from 10 MeV up to 10 TeV of $e^{\pm }$ energy with an uncertainty of about 5-7\% in the energies relevant for AMS-02 positron flux, thus dramatically reducing the precision of the theoretical model with respect to the state of the art. Finally, we provide a prediction for the secondary Galactic $e^{\pm }$ source spectrum with an uncertainty of the same level. As a service for the scientific community, we provide numerical tables and a script to calculate energy-differential cross sections.

    ↳ astro-ph.HEhep-phPRD(2022)·31 citations
29. 29*

    QCD equation of state via the complex Langevin method

    Felipe Attanasio🇩🇪 · Benjamin Jäger🇩🇰 · Felix P.G. Ziegler🇬🇧

    We present lattice simulations on the phase diagram of Quantum Chromodynamics (QCD) with two light quark flavours at finite chemical potential $\mu$. To circumvent the sign problem we use the complex Langevin method. In this study, we have carried out finite density lattice computations for a pion mass of $\sim 480$ MeV. We report on the pressure, energy and entropy equations of state in ab-initio lattice QCD calculations, as well as the observation of the Silver Blaze phenomenon.

    ↳ hep-lathep-ph24 citations
30. 30*

    Direct Photons in Hydrodynamic Modeling of Relativistic Nuclear Collisions

    Akihiko Monnai🇯🇵

    We review direct photons in the phenomenology of nuclear collisions at relativistic energies. Direct photons carry information about the space-time evolution of nuclear collisions because the QCD medium is transparent against colorless particles. After a status summary of theoretical and experimental studies, transverse momentum spectra and azimuthal momentum anisotropies of direct photons are studied in the context of the hydrodynamic modeling of relativistic nuclear collisions with emphasis on pre-equilibrium photons. It is implied that pre-equilibrium photons can be as important as thermal and prompt photons for comprehensive understanding of direct photon production.

    ↳ nucl-thhep-phnucl-exInt.J.Mod.Phys.A(2022)·16 citations
31. 31*

    Alternative explanation of Fermi Bubbles using Scalar Field Dark Matter

    Tonatiuh Matos🇲🇽 · Bryan Mendoza-Meza🇲🇽 · Leonardo San.-Hernandez · Abdel Perez-Lorenzana🇲🇽 · Maribel Hernandez-Marquez🇲🇽

    In recent times, the Scalar Field Dark Matter (SFDM) model (also called Fuzzy, Wave, Ultralight dark matter model) has received much attention due to its success in describing dark matter on both cosmological and galactic scales. Several challenges of the Cold Dark Matter (CDM) model can be explained very easily and naturally by the SFDM model. Two of these challenges are to describe the anomalous trajectories of satellite galaxies called the Vast Polar Structure (VPOS) and to explain the magnetic fields observed in our galaxy. In previous works an alternative explanation for VPOS and the magnetic fields of our galaxy was proposed using the SFDM excited states, explaining the anomalous trajectories in a natural and simple way. In this work we use the same dark matter endowed with a extremely small charge that explains the magnetic fields of our galaxy to show that these excited states of SFDM can provide a very simple and natural explanation for Fermi Bubbles (FBs). If this assumption is correct, we should see FBs in several more galaxies, these observations would take place in the near future and could be crucial to the ultimate answer to the nature of dark matter.

    ↳ astro-ph.GAgr-qchep-ph2 citations
32. 32*

    Hard probe path lengths and event-shape engineering of the quark-gluon plasma

    Caitlin Beattie🇺🇸 · Govert Nijs🇺🇸 · Mike Sas🇺🇸 · Wilke van der Schee🇨🇭

    As particles traverse the quark-gluon plasma (QGP) formed during a heavy ion collision they undergo energy loss depending on the distance travelled. We study several temperature- and velocity-weighted path length distributions of non-interacting particles as they traverse the plasma using the Trajectum heavy ion code, including those of back-to-back path lengths. We use event-shape engineering (ESE) in combination with in-plane versus out-of-plane selection to accurately control these path lengths. Lastly, we show how soft observables depend on the different ESE classes.

    ↳ nucl-thhep-phnucl-exPLB(2023)·13 citations
33. 33*

    Renormalizable and unitary Lorentz invariant model of quantum gravity

    S.A. Larin🇷🇺

    We analyze the R + R2 model of quantum gravity where terms quadratic in the curvature tensor are added to the General Relativity action. This model was recently proved to be a self-consistent quantum theory of gravitation, being both renormalizable and unitary. The model can be made practically indistinguishable from General Relativity at astrophysical and cosmological scales by the proper choice of parameters.

    ↳ hep-thhep-phUniverse(2021)·2 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.