Fri·Oct 21, 2022Friday·October 21, 2022

1. 01*

   Implications of a matter-antimatter mass asymmetry in Penning-trap experiments

   Ting Cheng🇩🇪 · Manfred Lindner🇩🇪 · Manibrata Sen🇩🇪

   The Standard Model (SM) of particle physics, being a local, unitary and Lorentz-invariant quantum field theory, remains symmetric under the combined action of Charge, Parity, and Time Reversal (CPT) symmetry. This automatically implies that fundamental properties of particles and antiparticles should be equal in magnitude. These fundamental tenets of the CPT principle have been put to stringent tests in recent Penning-trap experiments, where the matter-antimatter mass asymmetry has been measured. In light of these recent advances, we compare the bounds arising on CPT invariance from kaon systems with those from Penning-trap experiments. Using a simple yet powerful argument of mass decomposition of hadrons, we show that bounds on quark-antiquark mass differences from kaon oscillations are way beyond the reach of Penning-trap experiments. We lay out a roadmap to discuss possible reformulations of our understanding of the SM in the case of a discovery of CPT violation by these precision experiments.

   hep-phhep-exPLB(2023)·4 citations
2. 02*

   J/$\psi$ yields in low energy nuclear collisions at SPS and FAIR: A baseline estimation

   S. Chatterjee🇮🇳 · P. P. Bhaduri🇮🇳 · S. Chattopadhyay🇮🇳

   The yield of $J/\psi$ mesons, produced in proton-nucleus ($p+A$) and nucleus-nucleus ($A+A$) collisions are estimated within a Glauber model ansatz for the upcoming low energy heavy-ion collision experiments at SPS and FAIR. A data driven parametrization is employed to incorporate the effects of Cold Nuclear Matter (CNM) on the $J/\psi$ production cross-section.

   hep-phnucl-thNPA(2023)·5 citations
3. 03*

   Asymmetric Leptoquark Pair Production at LHC

   Ilja Doršner🇭🇷 · Ajla Lejlić🇭🇷 · Shaikh Saad🇨🇭

   We investigate asymmetric leptoquark pair production mechanism at the Large Hadron Collider to advocate its potential relevance to establish reliable constraints on the leptoquark parameter space and its ability to aid in correct identification of these attractive sources of new physics. The main feature of asymmetric pair production that genuinely distinguishes it from the usual leptoquark pair production is given by the fact that the two leptoquarks that are produced in proton-proton collisions through a $t$-channel lepton exchange are not charge conjugates of each other. Hence the proposed name of asymmetric leptoquark pair production for this type of process. We spell out prerequisite conditions for the asymmetric leptoquark pair production mechanism to be operational and enumerate all possible combinations of leptoquark multiplets that can potentially generate it. We finally reinterpret existing leptoquark pair production search results within several simple scalar leptoquark extensions of the Standard Model, assuming that the leptoquarks exclusively couple to either electrons or muons and the first generation quarks, to demonstrate proper inclusion of asymmetric pair production. We consequently present accurate parameter space constraints for the $S_1$, $S_3$, $R_2$, $S_1$+$S_3$, and $S_1$+$R_2$ leptoquark scenarios.

   hep-phhep-exJHEP(2023)·9 citations
4. 04*

   Exploring the cosmological dark matter coincidence using infrared fixed points

   Alexander C. Ritter🇦🇺 · Raymond R. Volkas🇦🇺

   The asymmetric dark matter (ADM) paradigm is motivated by the apparent coincidence between the cosmological mass densities of visible and dark matter, ${\Omega }_{\mathrm{DM}}\simeq 5{\Omega }_{\mathrm{VM}}$. However, most ADM models only relate the number densities of visible and dark matter, and do not motivate the similarity in their particle masses. One exception is a framework introduced by Bai and Schwaller, where the dark matter is a confined state of a dark QCD-like gauge group, and the confinement scales of visible and dark QCD are related by a dynamical mechanism utilising infrared fixed points of the two gauge couplings. We build upon this framework by properly implementing the dependence of the results on the initial conditions for the gauge couplings in the UV. We then reassess the ability of this framework to naturally explain the cosmological mass density coincidence, and find a reduced number of viable models. We identify features of the viable models that allow them to naturally relate the masses of the dark baryon and the proton while also avoiding collider constraints on the new particle content introduced.

   hep-phPRD(2023)·14 citations
5. 05*

   Missing beauty of proton-proton interactions

   Iakov Aizenberg🇮🇱 · Zvi Citron🇮🇱 · Alexander Milov🇮🇱

   From first principles, particles with the same quark content and similar masses should have similar kinematic distributions. Transverse mass scaling may be employed to estimate possible differences in the momentum distribution of such particles. Based on this scaling the excited bottomonium states measured at the LHC are found to be significantly different from ${\rm Y}$(1S) to the extent that the integrated yield of ${\rm Y}$(2S) is 1.6 times less and ${\rm Y}$(3S) 2.4 times less than would be explained by the mass difference. This proceeding explains how the estimate is worked out and relates it to other measurements performed at the LHC.

   hep-phhep-exnucl-exActa Phys.Polon.Supp.(2023)·0 citations
6. 06*

   Lepton anomaly from QED diagrams with vacuum polarization insertions within the Mellin-Barnes representation

   O.P. Solovtsova🇷🇺 · V.I. Lashkevich🇧🇾 · L.P. Kaptari🇷🇺

   The contributions to the anomalous magnetic moment of the lepton $L$ ($L=e,\mu$ or $\tau$) generated by a specific class of QED diagrams are evaluated analytically up to the eighth order of the electromagnetic coupling constant. The considered class of the Feynman diagrams involves the vacuum polarization insertions into the electromagnetic vertex of the lepton $L$ up to three closed lepton loops. The corresponding analytical expressions are obtained as functions of the mass ratios $r=m_l/m_L$ in the whole region $0<r<\infty$. Our consideration is based on a combined use of the dispersion relations for the polarization operators and the Mellin-Barnes integral transform for the Feynman parametric integrals. This method is widely used in the literature in multi-loop calculations in relativistic quantum field theories. For each order of the radiative correction, we derive analytical expressions as functions of $r$, separately at $r<1$ and $r>1$. We argue that in spite of the obtained explicit expressions in these intervals which are quite different, at first glance, they represent two branches of the same analytical function. Consequently, for each order of corrections there is a unique analytical function defined in the whole range of~$r\in (0,\infty )$. The results of numerical calculations of the $4th$, $6th$ and $8th$ order corrections to the anomalous magnetic moments of leptons ($L=e,\mu ,\tau$) with all possible vacuum polarization insertions are represented as functions of the ratio $r=m_l/m_L$. Whenever pertinent, we compare our analytical expressions and the corresponding asymptotic expansions with the known results available in the literature.

   hep-phhep-thEur.Phys.J.Plus(2023)·5 citations
7. 07*

   Precision ${\mu }^{+}{\mu }^{+}$ and ${\mu }^{+}{e}^{-}$ elastic scatterings

   Yu Hamada🇯🇵 · Ryuichiro Kitano🇯🇵 · Ryutaro Matsudo🇯🇵 · Hiromasa Takaura🇯🇵

   Expected precisions of measurements of the elastic scattering cross sections are estimated for ${\mu }^{+}{\mu }^{+}$ and ${\mu }^{+}{e}^{-}$ colliders, which are recently proposed as future realistic possibilities ($\mu$TRISTAN). Comparing with contributions from possible new physics represented by higher dimensional operators, we find that the measurements at a TeV energy ${\mu }^{+}{\mu }^{+}$ collider can probe the scale of new physics up to $O(100)$~TeV. A ${\mu }^{+}{e}^{-}$ collider for the Higgs boson factory can also improve the electroweak precision test.

   hep-phPTEP(2023)·26 citations
8. 08*

   Non-universal gauged lepton number for charged lepton masses hierarchy and $(g-2{)}_{e,\mu }$

   We-Fu Chang🇹🇼

   We construct a novel flavor-dependent gauged lepton number $U(1{)}_{\ell }$ model for the hierarchical charged lepton masses and the observed $(g-2{)}_{e,\mu }$. Only tau participates in the tree-level Standard Model ( SM ) Yukawa interaction. At the same time, the masses of electron and muon are light due to radiative generation and(or) the heavy-mediator-suppressed Yukawa coupling to the SM Higgs. Not only can the measured anomalous magnetic dipole moment of the muon, $△a_{\mu }$, be explained, but the positive (or negative) $△a_e$ can also be accommodated in this model. Without additional discrete symmetries introduced, charged lepton flavor violation is highly suppressed by the $U(1{)}_{\ell }$ symmetry. Corresponding to two equally viable $U(1{)}_{\ell }$ charge assignments, this model predicts either $A_{FB}^{\mu }<A_{FB}^{\tau }<A_{FB}^e$ or $A_{FB}^{\mu }>A_{FB}^{\tau }>A_{FB}^e$, which can be tested at the $e^{+}{e}^{-}$ machines before discovering the $U(1{)}_{\ell }$ gauge boson. Moreover, the effective muon and electron Yukawa couplings can depart significantly from the SM predictions, and those deviations could be probed at future $e^{+}{e}^{-}$ colliders and High-Luminosity LHC.

   hep-ph7 citations
9. 09*

   On new $k_{\perp }$-dependent (quasi)parton distribution functions

   I.V. Anikin🇷🇺

   We advocate the existence of a new type of $k_{\perp }$-dependent functions. In contrast to the well-known Boer-Mulders function, the presented new functions can be associated with the collective alignment of quark spin vectors. Moreover, the new functions are sensitive to the transverse motion of partons inside hadrons, which are linked to the spin alignment of partons, and they are initiated by the interactions encoded in the corresponding correlators.

   hep-phThe extended version of Phys. Part. Nucl.…·0 citations
10. 10*

    SMEFT effects on gravitational wave spectrum from electroweak phase transition

    Katsuya Hashino🇯🇵 · Daiki Ueda🇨🇳

    Future gravitational wave observations are potentially sensitive to new physics corrections to the Higgs potential once the first-order electroweak phase transition arises. We study the SMEFT dimension-six operator effects on the Higgs potential, where three types of effects are taken into account: (i) SMEFT tree level effect on ${\phi }^6$ operator, (ii) SMEFT tree level effect on the wave function renormalization of the Higgs field, and (iii) SMEFT top-quark one-loop level effect. The sensitivity of future gravitational wave observations to these effects is numerically calculated by performing a Fisher matrix analysis. We find that the future gravitational wave observations can be sensitive to (ii) and (iii) once the first-order electroweak phase transition arises from (i). The dimension-eight ${\phi }^8$ operator effects on the first-order electroweak phase transition are also discussed. The sensitivities of the future gravitational wave observations are also compared with those of future collider experiments.

    hep-phastro-ph.COhep-exhep-thPRD(2023)·25 citations
11. 11*

    Pomeron and Reggeon contributions to elastic proton-proton and proton-antiproton scattering in holographic QCD

    Zhibo Liu🇨🇳 · Wei Xie🇨🇳 · Akira Watanabe🇨🇳

    The total and differential cross sections of elastic proton-proton and proton-antiproton scattering are studied in a holographic QCD model, considering the Pomeron and Reggeon exchanges in the Regge regime. In our model setup, the Pomeron and Reggeon exchanges are described by the Reggeized spin-2 glueball and vector meson propagators, respectively. How those contributions change with the energy is explicitly shown, focusing on the contribution ratios. The adjustable parameters included in the model are determined with the experimental data, and it is presented that the resulting total and differential cross sections are consistent with the data in a wide kinematic region.

    hep-phhep-exnucl-exnucl-thPRD(2023)·13 citations
12. 12*

    Extraction of $\omega$n, $\omega$p and $\varphi$N scattering lengths from $\omega$ and $\varphi$ differential photoproduction cross sections on the deuterium target

    Chengdong Han🇨🇳 · Wei Kou🇨🇳 · Rong Wang🇨🇳 · Xurong Chen🇨🇳

    In this study, we try to extract $\omega n$, $\omega p$ and $\varphi$N scattering lengths from the differential cross-section data of near-threshold $\omega$ and $\varphi$ photoproductions not only to the energy at threshold t${}_{thr}$, but also in t to t = 0. The incoherent data of $\omega$ and $\varphi$ photoproductions on deuterium target for scattering length extractions are provided by CBELSA/TAPS Collaboration and LEPS Collaboration respectively, where the deuteron is usually approximated as a weakly bound state of a quasi-free neutron plus a quasi-free proton. Under the Vector Meson Doninance model and the assumption of energy independence of the differential cross-section, we obtained the $|{\alpha }_{\omega n^{\ast }}|$ and $|{\alpha }_{\omega p^{\ast }}|$ of loosely bound neutron and proton in the deuteron to be 0.709 $\pm$ 0.078 fm and 0.621 $\pm$ 0.022 fm respectively at threshold t${}_{thr}$ (1.258 $\pm$ 0.130 fm and 1.056 $\pm$ 0.032 fm respectively in t to t = 0) for the first time by fitting the near-threshold data of $\gamma$d $\to$ $\omega$n(p) and $\gamma$d $\to$ $\omega$p(n). For a comparison study, we also extracted the scattering length $|{\alpha }_{\omega p}|$ of the free proton from the $\omega$ photoproduction on the hydrogen target by CBELSA/TAPS Collaboration. With the near-threshold and incoherent $\varphi$ photoproduction data of $\gamma$d $\to$ $\varphi$pn by LEPS Collaboration, we obtained scattering length $|{\alpha }_{\varphi N}|$ of the bound nucleon inside the deuteron to be 0.109 $\pm$ 0.008 fm at threshold t${}_{thr}$ and 0.276 $\pm$ 0.010 fm in t to t = 0, respectively. The obtained $|{\alpha }_{\omega p}|$ and $|{\alpha }_{\varphi N}|$ are basically in agreement with the experimental indications and the theoretical predictions within the current uncertainties.

    hep-phPRC(2023)·10 citations
13. 13*

    Neutrinoless double-beta decay at colliders: interference between Majorana states

    Jonathan L. Schubert🇩🇰 · Oleg Ruchayskiy🇩🇰

    Heavy neutral leptons (HNLs) are hypothetical particles able to explain several puzzles of fundamental physics, first and foremost - neutrino oscillations. Being sterile with respect to Standard Model interactions, these particles admit Majorana masses, allowing for violation of the total lepton number. Lepton number violating (LNV) processes thus become a key signature of HNLs, pursued by many experiments. In this work, we demonstrate that if HNLs are the sole origin of neutrino masses, destructive interference between Majorana states suppresses the same-sign di-lepton signal. In the phenomenologically interesting case of large HNL couplings, such suppression is akin to the cancellation of HNLs' contributions to neutrino masses. Nevertheless, the signal can be much larger than coming from the Weinberg operator alone. We identify regions of the parameter space of such realistic HNL models where the LNV signal is maximised at the LHC and future FCC-hh. Our results are obtained within the effective W approximation which allows for analytic treatment and gives a clear dependence on the model parameters. Although approximate, they are argued to be correct within a factor of a few.

    hep-phhep-ex6 citations
14. 14*

    Modelling uncertainties of $t\overline{t}W$ in multi-lepton channel

    Jasmina Nasufi🇩🇪

    We compare fixed order and parton shower matched predictions for the process $pp\to {\ell }^{+}{\nu }_{\ell }{\ell }^{-}{\bar{\nu }}_{\ell }{\ell }^{\pm }{\nu }_{\ell }b\bar{b}+X$ at NLO in QCD, including the orders $\mathcal{O}({\alpha }_s^3{\alpha }^6)$ and $\mathcal{O}({\alpha }_s{\alpha }^8)$. The comparison is performed at the integrated and differential fiducial level at the LHC with $\sqrt{s}=13$ TeV. In the absence of parton shower matching procedure that includes the full off-shell effects for this process at NLO in QCD, we propose a new prescription. It enables the inclusion of approximate full off-shell effects to currently available parton shower matched predictions at NLO in QCD.

    hep-ph0 citations
15. 15*

    Machine-Learning Compression for Particle Physics Discoveries

    Jack H. Collins🇺🇸 · Yifeng Huang🇺🇸 · Simon Knapen🇺🇸 · Benjamin Nachman🇺🇸 · Daniel Whiteson🇺🇸

    In collider-based particle and nuclear physics experiments, data are produced at such extreme rates that only a subset can be recorded for later analysis. Typically, algorithms select individual collision events for preservation and store the complete experimental response. A relatively new alternative strategy is to additionally save a partial record for a larger subset of events, allowing for later specific analysis of a larger fraction of events. We propose a strategy that bridges these paradigms by compressing entire events for generic offline analysis but at a lower fidelity. An optimal-transport-based $\beta$ Variational Autoencoder (VAE) is used to automate the compression and the hyperparameter $\beta$ controls the compression fidelity. We introduce a new approach for multi-objective learning functions by simultaneously learning a VAE appropriate for all values of $\beta$ through parameterization. We present an example use case, a di-muon resonance search at the Large Hadron Collider (LHC), where we show that simulated data compressed by our $\beta$-VAE has enough fidelity to distinguish distinct signal morphologies.

    hep-phcs.LGhep-exphysics.data-an5 citations
16. 16*

    Inference finds consistency between a neutrino flavor evolution model and Earth-based solar neutrino measurements

    Caroline Laber-Smith🇺🇸 · A. A. Ahmetaj🇺🇸 · Eve Armstrong🇺🇸 · A. Baha Balantekin🇺🇸 · Amol V. Patwardhan🇺🇸 · M. Margarette Sanchez🇺🇸 · Sherry Wong🇺🇸

    We continue examining statistical data assimilation (SDA), an inference methodology, to infer solutions to neutrino flavor evolution, for the first time using real - rather than simulated - data. The model represents neutrinos streaming from the Sun's center and undergoing a Mikheyev-Smirnov-Wolfenstein (MSW) resonance in flavor space, due to the radially-varying electron number density. The model neutrino energies are chosen to correspond to experimental bins in the Sudbury Neutrino Observatory (SNO) and Borexino experiments, which measure electron-flavor survival probability at Earth. The procedure successfully finds consistency between the observed fluxes and the model, if the MSW resonance - that is, flavor evolution due to solar electrons - is included in the dynamical equations representing the model.

    ↳ astro-ph.SRhep-exhep-phPRD(2023)·6 citations
17. 17*

    Adjoint Majorana QCD${}_2$ at Finite $N$

    Ross Dempsey🇺🇸 · Igor R. Klebanov🇺🇸 · Loki L. Lin🇺🇸 · Silviu S. Pufu🇺🇸

    The mass spectrum of $1+1$-dimensional $\mathrm{SU}(N)$ gauge theory coupled to a Majorana fermion in the adjoint representation has been studied in the large $N$ limit using Light-Cone Quantization. Here we extend this approach to theories with small values of $N$, exhibiting explicit results for $N=2,3$, and $4$. In the context of Discretized Light-Cone Quantization, we develop a procedure based on the Cayley-Hamilton theorem for determining which states of the large $N$ theory become null at finite $N$. For the low-lying bound states, we find that the squared masses divided by $g^{2}N$, where $g$ is the gauge coupling, have very weak dependence on $N$. The coefficients of the $1/N^2$ corrections to their large $N$ values are surprisingly small. When the adjoint fermion is massless, we observe exact degeneracies that we explain in terms of a Kac-Moody algebra construction and charge conjugation symmetry. When the squared mass of the adjoint fermion is tuned to $g^{2}N/\pi$, we find evidence that the spectrum exhibits boson-fermion degeneracies, in agreement with the supersymmetry of the model at any value of $N$.

    ↳ hep-thhep-phJHEP(2023)·37 citations
18. 18*

    The search for new physics in $B\to K{\ell }^{+}{\ell }^{-}$ and $B\to K\nu \bar{\nu }$ using precise lattice QCD form factors

    W. G. Parrott🇬🇧 · C. Bouchard🇬🇧 · C. T. H. Davies🇬🇧

    We present HPQCD's improved scalar, vector and tensor form factors for $B\to K$ semileptonic decays, using the heavy-HISQ formalism for more accurate normalisation of the weak currents. Working with masses close to the physical $b$ on the finest ensemble and including three ensembles with physical light quarks, we cover the full physical $q^2$ range with good precision. Our uncertainties at $q^2=0$ are a factor of three better than earlier work. We compare Standard Model observables using our form factors to experimental measurements for the rare flavour changing neutral current processes $B\to K{\ell }^{+}{\ell }^{-}$ and $B\to K\nu \bar{\nu }$ and discuss the significance of the tensions that arise.

    ↳ hep-lathep-phPoS(2023)·10 citations
19. 19*

    Developments in Performance and Portability for MadGraph5_aMC@NLO

    Andrea Valassi🇨🇭 · Taylor Childers🇺🇸 · Laurence Field🇨🇭 · Stefan Hageböck🇨🇭 · Walter Hopkins🇺🇸 · Olivier Mattelaer🇧🇪 · Nathan Nichols🇺🇸 · Stefan Roiser🇨🇭 · David Smith🇨🇭

    Event generators simulate particle interactions using Monte Carlo techniques, providing the primary connection between experiment and theory in experimental high energy physics. These software packages, which are the first step in the simulation worflow of collider experiments, represent approximately 5 to 20% of the annual WLCG usage for the ATLAS and CMS experiments. With computing architectures becoming more heterogeneous, it is important to ensure that these key software frameworks can be run on future systems, large and small. In this contribution, recent progress on porting and speeding up the Madgraph5_aMC@NLO event generator on hybrid architectures, i.e. CPU with GPU accelerators, is discussed. The main focus of this work has been in the calculation of scattering amplitudes and "matrix elements", which is the computational bottleneck of an event generation application. For physics processes limited to QCD leading order, the code generation toolkit has been expanded to produce matrix element calculations using C++ vector instructions on CPUs and using CUDA for NVidia GPUs, as well as using Alpaka, Kokkos and SYCL for multiple CPU and GPU architectures. Performance is reported in terms of matrix element calculations per time on NVidia, Intel, and AMD devices. The status and outlook for the integration of this work into a production release usable by the LHC experiments, with the same functionalities and very similar user interfaces as the current Fortran version, is also described.

    ↳ physics.comp-phcs.SEhep-exhep-phPoS(2022)·19 citations
20. 20*

    Utilizing Theory and Experiment to Search for new structures of Fundamental Particles

    Jürgen Ulbricht · Minghui Liu

    Our current understanding of the Big Bang indicates that the universe was not a dimensionless point at $t=0$ but already had four dimensions. This work, exploring physics beyond the Standard Model, abandons the point-like nature of fundamental particles. It comprises theoretical and experimental parts. Theoretically, we present the Empirical Toy Ansatz about a Microstructure of Fundamental Particles (ETAMFP), using the numerical coincidence of strong, weak, and electromagnetic interactions and their corresponding charges (color, weak, electric) to develop a common ground state for all fundamental particles. The time coordinate is used to interpret higher states as vibrational modes of $x,y,z$ (monopole, dipole, quadrupole). We focus on the electron, with lifetime $6.6\times 10^{28}$ years, longer than the universe's age. We investigate a Lorentz-contracted gyroscope, a soliton in GR, and the Gross--Pitaevskii equation to derive an electron wave function, yielding an upper size limit, while ETAMFP gives a lower limit. Experimentally, the $e^{+}{e}^{-}\to \gamma \gamma$ reaction probes long-range QED, and the $e^{+}{e}^{-}\to e^{+}{e}^{-}(\gamma )$ Bhabha reaction probes short-range weak interaction. The theoretical outer electron radius is $3.2\times 10^{-14}$~m, experimental $3.18\times 10^{-14}$~m; the inner kernel radius is theoretically $3.3\times 10^{-15}$~m and experimentally $3.9\times 10^{-15}$~m. The agreement between our investigations in the theoretical and experimental domains of our work generally shows that it is possible to combine all fundamental particles into a common scheme--the ETAMPF model, especially the electron as a geometrically extended object with two fundamental boundaries. These findings open a window to the fusion of General Relativity and Quantum Mechanics and an explanation of the wave-particle duality.

    ↳ hep-exhep-phPhysics(2023)·1 citation
21. 21*

    Singlet Mesons in Dark $Sp(4)$ Theories

    Fabian Zierler🇦🇹 · Jong-Wan Lee🇰🇷 · Axel Maas🇦🇹 · Felix Pressler🇦🇹

    We explore some aspects of $Sp(4)$ gauge theory with two fundamental fermions in the context of composite Goldstone Dark Matter. We present preliminary lattice results for the mass of the pseudoscalar iso-singlet meson ${\eta }^{\prime }$ using unimproved Wilson fermions and the standard plaquette action. We find that the ${\eta }^{\prime }$ is slightly heavier than the pseudoscalar non-singlets $\pi$ and lighter than the vector mesons $\rho$ for multiple ensembles with $m_{\pi }/m_{\rho }\ge 0.77$. This pattern is potentially relevant for Beyond the Standard Model physics model building. Furthermore, we show that for $N_f=1+1$ flavours the disconnected contributions to the unflavoured pseudoscalar ${\pi }^0$ are small. We supplement this measurement by a calculation of the $\pi \pi$ scattering length $a_0$ which shows that the ensemble studied might be phenomenologically relevant for Dark Matter models such as the Strongly Interacting Massive Particles paradigm.

    ↳ hep-lathep-phPoS(2023)·11 citations
22. 22*

    Possible Evidence for Lorentz Invariance Violation in Gamma-ray Burst 221009A

    Justin D. Finke🇺🇸 · Soebur Razzaque🇿🇦

    The preliminary detections of the gamma-ray burst 221009A up to 18 TeV by LHAASO and up to 251 TeV by Carpet 2 have been reported through Astronomer's Telegrams and Gamma-ray Coordination Network circulars. Since this burst is at redshift $z=0.1505$, these photons may at first seem to have a low probability to avoid pair production off of background radiation fields and survive to reach detectors on Earth. By extrapolating the reported $0.1-1.0$\ GeV LAT spectrum from this burst to higher energies and using this to limit the intrinsic spectrum of the burst, we show that the survival of the 18 TeV photon detected by LHAASO is not unlikely with many recent extragalactic background light models, although the detection of a 251 TeV event is still very unlikely. This can be resolved if Lorentz invariance is violated at an energy scale $E_{\mathrm{QG}}<49E_{\mathrm{Planck}}$\ in the linear ($n=1$) case, and $E_{\mathrm{QG}}<10^{-6}{E}_{\mathrm{Planck}}$\ in the quadratic ($n=2$) case (95\% confidence limits), where $E_{\mathrm{Planck}}$ is the Planck energy. This could potentially be the first evidence for subluminal Lorentz invariance violation.

    ↳ astro-ph.HEhep-phApJL(2023)·56 citations
23. 23*

    Axion Quality Problem and Non-Minimal Gravitational Coupling in the Palatini Formulation

    Dhong Yeon Cheong🇰🇷 · Koichi Hamaguchi🇯🇵 · Yoshiki Kanazawa🇯🇵 · Sung Mook Lee🇰🇷 · Natsumi Nagata🇯🇵 · Seong Chan Park🇰🇷

    In axion models, the global U(1) Peccei-Quinn (PQ) symmetry is explicitly broken by non-perturbative effects of gravity, such as axionic wormholes. The gravitational violation of the PQ symmetry due to wormholes is large enough to invalidate the PQ mechanism, which is entitled as the axion quality problem. Recently, a novel solution to this quality problem was suggested, where the non-minimal coupling of the axion field to gravity $\xi$ is introduced to suppress the wormhole contribution. In this work, we revisit the problem in a different but equally valid formulation of gravity, namely the Palatini formulation, where the Ricci scalar is solely determined by connection. We first find the axionic wormhole solution in the Palatini formulation, taking the full dynamical radial mode as well as the axial mode, then show that the quality problem is still resolved with the non-minimal coupling $\xi$. The requested lower bound of $\xi$ in the Palatini formulation turns out to be slightly higher than that in the metric formulation.

    ↳ hep-thhep-phPRD(2023)·10 citations
24. 24*

    Light speed variation from GRB 221009A

    Jie Zhu🇨🇳 · Bo-Qiang Ma🇨🇳

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed, and a series of studies on high-energy photon events from gamma-ray bursts (GRBs) and active galactic nuclei (AGNs) suggest a light speed variation $v(E)=c\left(1-E/E_{\mathrm{LV}}\right)$ with $E_{\mathrm{LV}}=3.6\times 10^{17}\mathrm{GeV}$ or a bound $E_{\mathrm{LV}}\ge 3.6\times 10^{17}\mathrm{GeV}$. From the newly observed gamma-ray burst GRB 221009A, we find that a 99.3~GeV photon detected by Fermi-LAT is coincident with the sharp spike in the light curves detected by both Fermi-GBM and HEBS under the above scenario of light speed variation, suggesting an option that this high-energy photon was emitted at the same time as a sharp spike of low-energy photon emission at the GRB source. Thus this highest energy photon event detected by Fermi-LAT during the prompt emission of gamma-ray bursts might be considered as an optional signal for the linear form modification of light speed in cosmological space.

    ↳ astro-ph.HEgr-qchep-phJ.Phys.G(2023)·32 citations
25. 25*

    Promise of Future Searches for Cosmic Topology

    Yashar Akrami🇺🇸 · Stefano Anselmi🇮🇹 · Craig J. Copi🇺🇸 · Johannes R. Eskilt🇳🇴 · Andrew H. Jaffe🇬🇧 · Arthur Kosowsky🇺🇸 · Pip Petersen🇺🇸 · Glenn D. Starkman🇺🇸 · Kevin González-Quesada🇺🇸 · Özenç Güngör🇺🇸 · Deyan P. Mihaylov🇺🇸 · Samanta Saha🇺🇸 and 3 other authors

    The shortest distance around the Universe through us is unlikely to be much larger than the horizon diameter if microwave background anomalies are due to cosmic topology. We show that observational constraints from the lack of matched temperature circles in the microwave background leave many possibilities for such topologies. We evaluate the detectability of microwave background multipole correlations for sample cases. Searches for topology signatures in observational data over the large space of possible topologies pose a formidable computational challenge.

    ↳ astro-ph.COgr-qchep-phhep-thPRL(2024)·47 citations
26. 26*

    Emergent higher-form symmetry in Higgs phases with superfluidity

    Yoshimasa Hidaka🇯🇵 · Dan Kondo🇯🇵

    We address emergent higher-form symmetry in Higgs phases with superfluidity. The emergent symmetry appears if a matter field is invariant under a transformation of a common subgroup of gauge and global $\mathrm{U}(1)$ symmetries. We explicitly construct the symmetry generator that is topological and gauge invariant in a low-energy effective theory. Such emergent symmetry is helpful to distinguish the Higgs and other phases with superfluidity, such as phases of QCD at finite density. We also discuss the possibility of phase transition between these phases.

    ↳ hep-thcond-mat.str-elhep-phnucl-th10 citations
27. 27*

    Snowmass Early Career

    Garvita Agarwal🇺🇸 · Joshua L. Barrow🇺🇸 · Mateus F. Carneiro🇺🇸 · Thomas Y. Chen🇺🇸 · Erin Conley🇺🇸 · Rob Fine🇺🇸 · Julia Gonski🇺🇸 · Erin V. Hansen🇺🇸 · Sam Hedges🇺🇸 · Christian Herwig🇺🇸 · Samuel Homiller🇺🇸 · Tiffany R. Lewis🇺🇸 and 7 other authors

    The Snowmass 2021 strategic planning process provided an essential opportunity for the United States high energy physics and astroparticle (HEPA) community to come together and discuss upcoming physics goals and experiments. As this forward-looking perspective on the field often reaches far enough into the future to surpass the timescale of a single career, consideration of the next generation of physicists is crucial. The 2021 Snowmass Early Career (SEC) organization aimed to unite this group, with the purpose of both educating the newest generation of physicists while informing the senior generation of their interests and opinions. SEC is the latest in a series of the previously dubbed "Snowmass Young" organizations, from 2013 and 2001. This iteration has expanded on these efforts to significantly increase involvement and broaden the representation of the early career community in the process. Early career physicists are the future of the field. They will design, build, and operate next-generation experiments, and put in the work to usher in new discoveries. They are also disproportionately involved in work to improve the climate within HEPA. This document summarizes the work of SEC in consolidating a huge variety of physics perspectives and community opinions towards a bright, strategic future.

    ↳ hep-exhep-ph2 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.