Thu·Feb 3, 2022Thursday·February 3, 2022

1. 01*

   Interpretation of the ${\eta }_1(1855)$ as a $K{\bar{K}}_1(1400)+$ c.c. molecule

   Xiang-Kun Dong🇨🇳 · Yong-Hui Lin🇩🇪 · Bing-Song Zou🇨🇳

   An exotic state with $J^{PC}=1^{-+}$, denoted by ${\eta }_1(1855)$, was observed by BESIII collaboration recently in $J/\psi \to \gamma \eta {\eta }^{\prime }$. The fact that its mass is just below the threshold of $K{\bar{K}}_1(1400)$ stimulates us to investigate whether this exotic state can be interpreted as a $K{\bar{K}}_1(1400)+$ c.c { molecule or not}. Using the one boson exchange model, we show that it is possible for $K{\bar{K}}_1(1400)$ with $J^{PC}=1^{-+}$ to bind together by taking the momentum cutoff $\Lambda \gtrsim 2$ GeV and yield the same binding energy as the experimental value when $\Lambda \approx 2.5$ GeV. In this molecular picture, the predicted branch ratio $\mathrm{Br}({\eta }_1(1855)\to \eta {\eta }^{\prime })\approx 15\%$ is consistent with the experimental results, which again supports the molecular explanation of ${\eta }_1(1855)$. Relevant systems, namely $K{\bar{K}}_1(1400)$ with $J^{PC}=1^{--}$ and $K{\bar{K}}_1(1270)$ with $J^{PC}=1^{-\pm }$, are also investigated, some of which can be searched for in the future experiments.

   hep-phhep-exhep-latSCPMA(2022)·47 citations
2. 02*

   Are neutrino oscillation mixings linked to the smallness of solar neutrino scale?

   Eduardo Becerra-García🇲🇽 · Abdel Pérez-Lorenzana🇲🇽

   Observed reactor and atmospheric neutrino oscillation mixing values appear to be related to the neutrino scale ratio $\sqrt{\Delta m_{sol}^2/{\Delta }_{ATM}^2}$ in a way that suggest that the neutrino mass matrix can be expanded as a power series by using this ratio as the smallness parameter. This approach provides a simple and natural way to expose the inner hierarchies among neutrino mass terms, which amounts to also explain the solar oscillation mixing as well as solar oscillation scale. We explore a class of mass matrix textures that realize this scenario, for both normal and inverted neutrino mass hierarchies, as well as CP violation and their stability under renormalization scaling.

   hep-phRev.Mex.Fis.(2024)·1 citation
3. 03*

   Heavy quark potential and jet quenching parameter in a rotating D-instanton background

   Jun-Xia Chen🇨🇳 · De-Fu Hou🇨🇳

   We get the dual gravity metric of the rotating nuclear matter by performing a standard Lorentz transformation on the static metric in the D-instanton background. Then, we study the effects of the angular velocity, the instanton density and the temperature on the heavy quark potential. It is shown that the angular velocity and the temperature promote dissociation of the quark-antiquark pair, and the instanton density suppresses dissociation. Similarly, according to the result of the jet quenching parameter, we found that the jet quenching parameter increases with the increase of angular velocity, instanton density and temperature, and the jet quenching parameter in the rotating D-instanton background is larger than that of N = 4 SYM theory.

   hep-phEPJC(2024)·15 citations
4. 04*

   Towards the establishment of the light $J^{P(C)}=1^{-(+)}$ hybrid nonet

   Lin Qiu🇨🇳 · Qiang Zhao🇨🇳

   The observation of the light hybrid candidate ${\eta }_1(1855)$ by the BESIII Collaboration brings great opportunities for advancing our knowledges about exotic hadrons in the light flavor sector. We show that this observation provides a crucial clue for establishing the $J^{P(C)}=1^{-(+)}$ hybrid nonet. Based on the flux tube model picture, the production and decay mechanisms for the $J^{P(C)}=1^{-(+)}$ hybrid nonet in the $J/\psi$ radiative decays into two pseudoscalar mesons are investigated. In the $I=0$ sector, we find that the SU(3) flavor octet and singlet mixing is non-negligible and apparently deviates from the flavor ideal mixing. Since only signals for one isoscalar ${\eta }_1(1855)$ are observed in the $\eta {\eta }^{\prime }$ channel, we investigate two schemes of the nonet structure in which ${\eta }_1(1855)$ can be either the higher or lower mass state that strongly couples to $\eta {\eta }^{\prime }$. Possible channels for detecting the multiplets are suggested. In particular, a combined analysis of the hybrid production in $J/\psi \to VH$, where $V$ and $H$ stand for the light vector mesons and $1^{-(+)}$ hybrid states, may provide further evidence for this nonet structure and finally establish these mysterious exotic species in experiment.

   hep-phCPC(2022)·52 citations
5. 05*

   Lower bounds on lepton flavor violating branching ratios in a radiative seesaw model

   Osamu Seto🇯🇵 · Tetsuo Shindou🇯🇵 · Takanao Tsuyuki🇯🇵

   We study the lepton flavor violating decays such as $\mu \to e\gamma$, $\tau \to e\gamma$, $\tau \to \mu \gamma$ in the three-loop radiative seesaw model proposed by Krauss, Nasri, and Trodden. In this model, the relevant coupling constants are larger for the heavier scalars that run inside loop diagrams to generate the appropriate magnitude of neutrino masses. Imposing a criterion that all the coupling constants must be small enough to be treated perturbatively, we find an upper bound on the mass of one of the scalars. By combining it with neutrino mass parameters, we derive lower bounds on the branching ratios of the lepton flavor violating processes. In a case with the inverted mass ordering and best-fit neutrino oscillation parameters, one of the lower bounds is $\text{Br}(\mu \to e\gamma )>1.1\times 10^{-13}$, which is within the reach of the MEG~II experiment.

   hep-phPRD(2022)·2 citations
6. 06*

   Power suppressed corrections show new features of infrared cancellations

   Paolo Ciafaloni🇮🇹 · Denis Comelli🇮🇹 · Alfredo Urbano🇮🇹

   The cancellation of infrared (IR) divergences is an old topic in quantum field theory whose main results are condensed into the celebrated Kinoshita-Lee-Nauenberg (KLN) theorem. In this paper, we consider mass-suppressed corrections to the leading (i.e. double-logarithmic) IR divergences in the context of spontaneously broken gauge theories. We work in a simplified theoretical set-up based on the spontaneously broken $U^{\prime }(1)\otimes U(1)$ gauge group. We analyze, at the one-loop level and including mass-suppressed terms, the double-logarithmic corrections to the decay channels of a hypothetical heavy $Z^{\prime }$ gauge boson coupled to light chiral fermions and mixed with a light massive $Z$ gauge boson. Limited to this theoretical framework, only final state IR corrections are relevant. We find that full exploitation of the KLN theorem requires non-trivial combinations of various decay channels in order to get rid of the mass-suppressed IR corrections. Based on this observation we show that, starting from any two-body decay of the heavy $Z^{\prime }$ gauge boson, the cancellation of the mass-suppressed double-logarithmic corrections requires the sum over the full decay width (thus enforcing the inclusion of final states which are na\"ıvely unrelated to the starting one). En route, we prove a number of technical results that are relevant for the computation of mass-suppressed double-logarithms of IR origin. Our results are relevant for models that enlarge the Standard Model by adding a heavy $Z^{\prime }$.

   hep-phhep-thJHEP(2022)·2 citations
7. 07*

   Towards precise collider predictions: the Parton Branching method

   Aleksandra Lelek🇧🇪

   The collinear factorization theorem, combined with finite-order calculations in perturbative QCD, provides a powerful framework to obtain predictions for many collider observables. However, for observables which involve multiple energy scales, transverse degrees of freedom cannot be neglected, and finite-order perturbative calculations have to be combined with resummed calculations to all orders in the QCD running coupling in order to obtain reliable theoretical predictions, capable of describing experimental measurements. This is traditionally done either by analytic resummation methods or by parton shower (PS) Monte Carlo (MC) methods. In this talk we present the Parton Branching (PB) MC method to obtain QCD collider predictions based on Transverse Momentum Dependent (TMD) factorization. The PB provides evolution equations for TMD Parton Distribution Functions (PDFs) which, upon fitting TMD PDFs to experimental data, can be used in TMD MC event generators. We present the basic concepts of the method and illustrate its applications to collider measurements focusing on Drell-Yan (DY) lepton-pair production in different kinematic ranges, from fixed-target to LHC energies. We discuss the latest developments of the method concentrating especially on the matching of next-to-leading-order (NLO) TMD evolution with MC-at-NLO calculations of NLO matrix elements.

   hep-phRev.Mex.Fis.Suppl.(2022)·0 citations
8. 08*

   Angular momentum and generalized parton distributions for the proton with basis light-front quantization

   Yiping Liu🇨🇳 · Siqi Xu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

   We study the unpolarized and the helicity dependent generalized parton distributions (GPDs) for the valence quarks of the proton in both momentum space and position space within the basis light-front quantization (BLFQ) framework. The GPDs for the valence quarks are computed from the eigenvectors of a light-front effective Hamiltonian in the valence Fock sector consisting of a three-dimensional confinement potential and a one-gluon exchange interaction with fixed coupling. Employing these GPDs, we obtain the spatial distributions of quark angular momentum inside the proton. In our BLFQ approach, we explore various definitions of angular momentum density and illustrate the differences between them arising from terms that integrate to zero. We also discuss the flavor contributions to the quark angular momentum densities.

   hep-phPRD(2022)·40 citations
9. 09*

   Minimal Consistent models for systematic Dark Matter exploration

   Alexander Belyaev🇬🇧 · Giacomo Cacciapaglia🇫🇷 · Daniel Locke🇬🇧

   Dark Matter searches in collider and non-collider experiments requires systematic and consistent approach. We suggest and perform classification of Minimal Consistent Dark Matter models which are aimed to create a solid framework for Dark Matter exploration.

   hep-ph0 citations
10. 10*

    Nuclear matter in 1+1 dimensions

    Robert M. Konik🇺🇸 · Marton Lajer🇺🇸 · Robert D. Pisarski🇺🇸 · Alexei M. Tsvelik🇺🇸

    We review the solution of QCD in two spacetime dimensions. Following the analysis of Baluni, for a single flavor the model can be analyzed using Abelian bosonization. The theory can be analyzed in strong coupling, when the quarks are much lighter than the gauge coupling. In this limit, the theory is given by a Luttinger liquid.

    hep-phcond-mat.str-elhep-thnucl-thUniverse(2021)·1 citation
11. 11*

    A pedagagical introduction to the Lifshitz regime

    Robert D. Pisarski🇺🇸 · Vladimir V. Skokov🇺🇸 · Alexei M. Tsvelik🇺🇸

    We give an elementary and pedagogical review of the phase diagrams which are possible in Quantum ChromoDynamics (QCD). Currently, the emphasis is upon the appearance of a critical endpoint, where disordered and ordered phases meet. In many models, though, a Lifshitz point also arises. At a Lifshitz point, three phases meet: disordered, ordered, and one where spatially inhomogeneous phases arise. At the level of mean field theory, the appearance of a Lifshitz point does not dramatically affect the phase diagram. We argue, however, that fluctuations about the Lifshitz point are very strong in the infrared, and significantly alter the phase diagram. We discuss at length the analogy to inhomogenous polymers, where the Lifshitz regime produces a bicontinuous microemulsion. We briefly mention the possible relevance to the phase diagram of QCD.

    hep-phnucl-thUniverse(2019)·18 citations
12. 12*

    Searching exotic Higgs bosons at the LHC

    Gautam Bhattacharyya🇮🇳 · Siddharth Dwivedi🇮🇳 · Dilip Kumar Ghosh🇮🇳 · Gourab Saha🇮🇳 · Subir Sarkar🇮🇳

    We analyse in a model independent way the possibilities of digging out neutral exotic Higgs states, should they exist endowed with unconventional couplings with ordinary matter and gauge fields, at the 14 TeV run of the Large Hadron Collider (LHC), adding some comparative studies for 13.6 and 13 TeV runs. Flavor models, based on some discrete symmetry groups, with extended scalar sectors are known to yield exotic spin-0 states, both CP-even and CP-odd, with purely flavor off-diagonal Yukawa couplings. The gauge interaction of one such CP-even state is also unusual that, unlike the Standard Model Higgs boson, it does not couple to gauge boson pairs. Such unconventional properties immune these exotic states from receiving traditional collider and electroweak constraints, and hence those states could be light. Without committing to any specific model, exploiting their peculiar Yukawa and gauge properties, we explore the discovery potential of those exotic Higgs states through some interesting topologies by figuring out some specific kinematic variables that suppress the backgrounds.

    hep-phPRD(2022)·4 citations
13. 13*

    Proton-PDF uncertainties in extracting nuclear PDFs from $W^{\pm }$ production in p+Pb collisions

    Kari J. Eskola🇫🇮 · Petja Paakkinen🇫🇮 · Hannu Paukkunen🇫🇮 · Carlos A. Salgado🇪🇸

    We discuss the recent CMS Collaboration measurement of $W^{\pm }$ boson production in p+Pb collisions at 8.16 TeV in terms of the constraining power on nuclear parton distribution functions (PDFs). The impact of the free-proton PDF uncertainties on the nuclear PDF extraction is quantified by using a theoretical covariance-matrix method and Hessian PDF reweighting. We discuss different ways to mitigate these theoretical uncertainties, including self-normalization, forward-to-backward ratios and nuclear-modification ratios. It is found that none of these methods offer perfect cancellation of the free-proton PDFs but, with the present data uncertainties, the residual free-proton-PDF dependence has, conveniently for the global analyses, little effect on the extraction of the nuclear modifications. Based on a simple estimate of obtainable statistics at the LHC Run 3, we argue that this will change in the near future and it becomes more important to propagate the proton-PDF uncertainties accordingly. Using the obtained information on the correlations of the free-proton uncertainties, we also identify a new charge asymmetry ratio, where the cancellation of the proton-PDF uncertainties is found to be extremely good.

    hep-phEPJC(2022)·13 citations
14. 14*

    The interplay between compact and molecular structures in tetraquarks

    Hagop Sazdjian🇫🇷

    Due to the cluster reducibility of multiquark operators, a strong interplay exists in tetraquarks between the compact structure, resulting from the direct confining forces acting on quarks and gluons, and the molecular structure, dominated by the mesonic clusters. This issue is studied within an effective field theory approach, where the compact tetraquark is treated as an elementary particle. The key ingredient of the analysis is provided by the primary coupling constant of the compact tetraquark to the two mesonic clusters. Under the influence of this coupling, an initially formed compact tetraquark bound state evolves towards a new structure, where a molecular configuration is also present. In the strong-coupling limit, the evolution may end with a shallow bound state of the molecular type. The strong-coupling regime is also favored by the large-$N_c$ properties of QCD. The interplay between compact and molecular structures may provide a natural explanation of the existence of many shallow bound states.

    hep-phSymmetry(2022)·23 citations
15. 15*

    Combining N3LO QCD calculations and parton showers for hadronic collision events

    Valerio Bertone🇫🇷 · Stefan Prestel🇸🇪

    Detailed and precise background predictions are the backbone of large parts of high-energy collider phenomenology. This requires to embed precision QCD calculations into detailed event generators, to produce comprehensive software simulations. Only continued progress in this direction will allow us to exploit the full potential of measurements at the Large Hadron Collider, or at a future Electron-Ion Collider. This work presents a method to combine third-order QCD calculations for hadronic scattering processes with Monte-Carlo event generators, thus enabling a new generation of precision predictions.

    hep-ph14 citations
16. 16*

    How an ${\omega }_0$ condensate can spike the speed of sound in cold quarkyonic matter

    Robert D. Pisarski🇺🇸

    I describe a novel mechanism where the variation of an ${\omega }_0$ condensate can generate a "spike" in the speed of sound in hadronic matter. An ${\omega }_0$ condensate naturally increases the speed of sound; the real problem is how to get the speed of sound to decrease. I suggest this can happen through the appearance of a Quantum Pion Liquid.

    hep-phnucl-thPoS(2022)·0 citations
17. 17*

    Exclusive nonleptonic Bc-meson decays to S-wave charmonium states

    Lopamudra Nayak🇮🇳 · P. C. Dash🇮🇳 · Susmita Kar🇮🇳 · N. Barik🇮🇳

    We study the exclusive two-body nonleptonic $B_c\to X_{c\bar{c}}M$ decays, where $X_{c\bar{c}}$ is either a ground(1S) or a radially excited (2S or 3S) charmonium and $M$ is a pseudoscalar $(P)$ or a vector $(V)$ meson. We consider here three categories of decays: $B_c\to PP,PV,VP$ decays within the framework of relativistic independent quark(RIQ) model based on a flavor-independent interaction potential in scalar-vector harmonic form. Using the factorization approximation, we calculate the weak form factors from the overlapping integrals of meson wave functions obtained in the RIQ model and predict the branching fractions for a set of exclusive nonleptonic $B_c$-decays in reasonable agreement with other model predictions. Some of the decays of interest are found to have branching fractions $\sim (10^{-3}-10^{-4})$ within the detection ability of the current experiments and can be precisely measured at LHCb in near future. In the wake of the recent measurement of $B_c\to J/\psi \pi (K)$, $B_c\to J/\psi \pi (D_s)$, $B_c\to \pi (J/\psi ,\psi (2S))$ and $B_c\to J/\psi (\pi ,\mu \nu )$ reported by the LHCb Collaborations, we predict the ratios: ${\mathcal{R}}_{K/\pi }$, ${\mathcal{R}}_{D_s/\pi }$ and ${\mathcal{R}}_{\psi (2S)/J/\psi }$ in broad agreement with the LHCb data though our predicted ratio ${\mathcal{R}}_{\pi /\mu \nu }$ is found to be underestimated. The results indicate that the present approach works well in the description of exclusive nonleptonic $B_c$-decays within the framework of the RIQ model.

    hep-phPRD(2022)·19 citations
18. 18*

    Testing Lorentz Invariance with Neutrinos

    Floyd W. Stecker🇺🇸

    The search for a theory that unifies general relativity and quantum theory has focused attention on models of physics at the Planck scale. One possible consequence of models such as string theory may be that Lorentz invariance is not an exact symmetry of nature. We discuss here some possible experimental and observational tests of Lorentz invariance involving neutrino physics and astrophysics.

    hep-phastro-ph.HE6 citations
19. 19*

    2D energy-momentum tensor distributions of nucleon in a large-$N_c$ quark model from ultra-relativistic to non-relativistic limit

    Cédric Lorcé🇫🇷 · Peter Schweitzer🇺🇸 · Kemal Tezgin🇺🇸

    Form factors of the energy-momentum tensor (EMT) can be interpreted in certain frames in terms of spatial distributions of energy, stress, linear and angular momentum, based on 2D or 3D Fourier transforms. This interpretation is in general subject to "relativistic recoil corrections", except when the nucleon moves at the speed of light like e.g. in the infinite-momentum frame. We show that it is possible to formulate a large-$N_c$ limit in which the probabilistic interpretation of the nucleon EMT distributions holds also in other frames. We use the bag model formulated in the large-$N_c$ limit as an internally consistent quark model framework to visualize the information content associated with the 2D EMT distributions. In order to provide more intuition, we present results in the physical situation and in three different limits: by considering a heavy-quark limit, a large system-size limit and a constituent-quark limit. The visualizations of the distributions in these extreme limits will help to interpret the results from experiments, lattice QCD, and other models or effective theories.

    hep-phPRD(2022)·35 citations
20. 20*

    Searching for Ultra-light Bosons and Constraining Black Hole Spin Distributions with Stellar Tidal Disruption Events

    Peizhi Du🇺🇸 · Daniel Egana-Ugrinovic🇨🇦 · Rouven Essig🇺🇸 · Giacomo Fragione🇺🇸 · Rosalba Perna🇺🇸

    Stars that pass close to the supermassive black holes located in the center of galaxies can be violently disrupted by tidal forces, leading to flares that are observed as bright transient events in sky surveys. The rate for these events to occur depends on the black hole spins, which in turn can be affected by ultra-light bosons due to superradiance. We perform a detailed analysis of these effects and show that searches for stellar tidal disruptions have a significant potential to uncover the existence of ultra-light bosons. In particular, we find that upcoming stellar tidal disruption rate measurements by the Vera Rubin Observatory's Legacy Survey of Space and Time can be used to either discover or rule out bosons with masses ranging from $10^{-20}$ to $10^{-18}$ eV. Our analysis also indicates that these measurements may be used to constrain a variety of supermassive black hole spin distributions and determine if close-to maximal spins are preferred.

    hep-phastro-ph.COastro-ph.HEgr-qcNature Commun.(2022)·32 citations
21. 21*

    Simple Rules for Evanescent Operators in One-Loop Basis Transformations

    Jason Aebischer🇨🇭 · Andrzej J. Buras🇩🇪 · Jacky Kumar🇩🇪

    Basis transformations often involve Fierz and other relations which are only valid in $D=4$ dimensions. In general $D$ space-time dimensions however, evanescent operators have to be introduced, in order to preserve such identities. Such evanescent operators contribute to one-loop basis transformations as well as to two-loop renormalization group running. We present a simple procedure on how to systematically change basis at the one-loop level by obtaining shifts due to evanescent operators. As an example we apply this method to derive the one-loop basis transformation from the BMU (Buras, Misiak and Urban) basis useful for NLO QCD calculations, to the JMS (Jenkins, Manohar and Stoffer) basis used in the matching to the SMEFT.

    hep-phhep-thPRD(2023)·25 citations
22. 22*

    Gegenbauer's Twin

    Gauthier Durieux🇨🇭 · Matthew McCullough🇨🇭 · Ennio Salvioni🇮🇹

    In Twin Higgs models the dominant source of fine-tuning is the cancellation of order $v^2/f^2$ required to obtain a Standard Model-like Higgs, where $v$ and $f$ are the electroweak and new physics scales, respectively. Recently proposed Gegenbauer Goldstone models naturally realise $v^2/f^2\ll 1$ and hence remove this source of fine-tuning. By combining the two into `Gegenbauer's Twin', we obtain a symmetry-based model for Higgs sector naturalness consistent with current collider measurements without fine-tuning of parameters. Single-Higgs coupling deviations of a few percent and trilinear self-coupling deviations of order one are irreducible in the natural parameter space. Thus, notably, the fingerprints of Gegenbauer's Twin could emerge first through di-Higgs measurements at the High-Luminosity LHC.

    hep-phhep-exJHEP(2022)·15 citations
23. 23*

    Uncovering a chirally suppressed mechanism of $0\nu \beta \beta$ decay with LHC searches

    Michael L. Graesser🇺🇸 · Gang Li🇺🇸 · Michael J. Ramsey-Musolf🇨🇳 · Tianyang Shen🇺🇸 · Sebastián Urrutia-Quiroga🇺🇸

    $\Delta L=2$ lepton number violation (LNV) at the TeV scale could provide an alternative interpretation of positive signal(s) in future neutrinoless double beta $(0\nu \beta \beta )$ decay experiments. An interesting class of models from this point of view are those that at low energies give rise to dimension-9 vector operators and a dimension-7 operator, both of whose $0\nu \beta \beta$-decay rates are "chirally suppressed". We study and compare the sensitivities of $0\nu \beta \beta$-decay experiments and LHC searches to a simplified model in this class of TeV-scale LNV that is also $SU(2{)}_L\times U(1{)}_Y$ gauge invariant. The searches for $0\nu \beta \beta$ decay, which are here diluted by a chiral suppression of the vector operators, are found to be less constraining than LHC searches whose reach is increased by the assumed kinematic accessibility of the mediator particles. For the chirally suppressed dimension-7 operator generated by TeV-scale mediators, in contrast, $0\nu \beta \beta$-decay searches place strong constraints on the size of the new Yukawa coupling. Signals of this model at the LHC and $0\nu \beta \beta$-decay experiments are entirely uncorrelated with the observed neutrinos masses, as these new sources of LNV give negligible contributions to the latter. We find the prospects for the high-luminosity LHC and ton-scale $0\nu \beta \beta$-decay experiments to uncover the chirally-suppressed mechanism with TeV-scale LNV to be promising. We also comment on the sensitivity of the $0\nu \beta \beta$-decay lifetime to certain unknown low-energy constants that in the case of dimension-9 {\it scalar} operators are expected to be large due to non-perturbative renormalization.

    hep-phhep-exnucl-exnucl-thJHEP(2022)·17 citations
24. 24*

    Resolving Extreme Jet Substructure

    Yadong Lu🇺🇸 · Alexis Romero🇺🇸 · Michael James Fenton🇺🇸 · Daniel Whiteson🇺🇸 · Pierre Baldi🇺🇸

    We study the effectiveness of theoretically-motivated high-level jet observables in the extreme context of jets with a large number of hard sub-jets (up to $N=8$). Previous studies indicate that high-level observables are powerful, interpretable tools to probe jet substructure for $N\le 3$ hard sub-jets, but that deep neural networks trained on low-level jet constituents match or slightly exceed their performance. We extend this work for up to $N=8$ hard sub-jets, using deep particle-flow networks (PFNs) and Transformer based networks to estimate a loose upper bound on the classification performance. A fully-connected neural network operating on a standard set of high-level jet observables, 135 $\text{N}$-subjetiness observables and jet mass, reach classification accuracy of 86.90\%, but fall short of the PFN and Transformer models, which reach classification accuracies of 89.19\% and 91.27\% respectively, suggesting that the constituent networks utilize information not captured by the set of high-level observables. We then identify additional high-level observables which are able to narrow this gap, and utilize LASSO regularization for feature selection to identify and rank the most relevant observables and provide further insights into the learning strategies used by the constituent-based neural networks. The final model contains only 31 high-level observables and is able to match the performance of the PFN and approximate the performance of the Transformer model to within 2\%.

    ↳ hep-exhep-phJHEP(2022)·15 citations
25. 25*

    Natural Inflation with non minimal coupling to gravity in $R^2$ gravity under the Palatini formalism

    M. AlHallak🇸🇾 · N. Chamoun🇸🇾 · M. S. Eldaher🇸🇾

    Natural Inflation with non-minimal coupling (NMC) to gravity, embodied by a Lagrangian term $\xi {\varphi }^{2}R$, is investigated in the context of an extended gravity of the form $R+\alpha R^2$. The treatment is performed in the Palatini formalism. We discuss various limits of the model ``$\alpha \gg 1$'' and ``$\alpha \ll 1$'' in light of two scenarios of inflation: a ``Slow roll'' and a ``Constant roll'' scenario. By analyzing the observational consequences of the model, our results show a significant improvement regarding compatibility between the theoretical results of this model and the observational constraints from Planck 2018 and BICEP/Keck 2018, as exemplified by the tensor-to-scalar ratio and spectral index. Furthermore, a broader range for the parameter space of natural inflation is now compatible with the confidence contours of Planck \& BICEP/Keck results. The joint effects of the contributions of both the NMC to gravity and the $\alpha R^2$ make a significant improvement: $\alpha R^2$ gravity influences scalar-tensor ratio values, whereas NMC to gravity has a more significant impact on the spectral index values. Contributions from both terms allow more previously excluded intervals to be included being compatible now with observational data. These conclusions about the roles of NMC to gravity and, particularly, the extended gravity remain mainly valid with a periodic NMC similar in form to the natural inflation potential.

    ↳ astro-ph.COhep-phJCAP(2022)·19 citations
26. 26*

    Nuclear Forces for Precision Nuclear Physics -- a collection of perspectives

    Ingo Tews🇺🇸 · Zohreh Davoudi🇺🇸 · Andreas Ekström🇸🇪 · Jason D. Holt🇨🇦 · Kevin Becker🇺🇸 · Raúl Briceño🇺🇸 · David J. Dean🇺🇸 · William Detmold🇺🇸 · Christian Drischler🇺🇸 · Thomas Duguet🇫🇷 · Evgeny Epelbaum🇩🇪 · Ashot Gasparyan🇩🇪 and 33 other authors

    This is a collection of perspective pieces contributed by the participants of the Institute of Nuclear Theory's Program on Nuclear Physics for Precision Nuclear Physics which was held virtually from April 19 to May 7, 2021. The collection represents the reflections of a vibrant and engaged community of researchers on the status of theoretical research in low-energy nuclear physics, the challenges ahead, and new ideas and strategies to make progress in nuclear structure and reaction physics, effective field theory, lattice QCD, quantum information, and quantum computing. The contributed pieces solely reflect the perspectives of the respective authors and do not represent the viewpoints of the Institute for Nuclear theory or the organizers of the program.

    ↳ nucl-thhep-lathep-phFew Body Syst.(2022)·66 citations
27. 27*

    Neutrino point source searches for dark matter spikes

    Katherine Freese🇺🇸 · Irina Galstyan🇸🇪 · Pearl Sandick🇺🇸 · Patrick Stengel🇸🇪

    Any dark matter spikes surrounding black holes in our Galaxy are sites of significant dark matter annihilation, leading to a potentially detectable neutrino signal. In this paper we examine $10-10^5{M}_{\odot }$ black holes associated with dark matter spikes that formed in early minihalos and still exist in our Milky Way Galaxy today, in light of neutrino data from the ANTARES and IceCube detectors. In various regions of the sky, we determine the minimum distance away from the solar system that a dark matter spike must be in order to have not been detected as a neutrino point source for a variety of representative dark matter annihilation channels. Given these constraints on the distribution of dark matter spikes in the Galaxy, we place significant limits on the formation of the first generation of stars in early minihalos -- stronger than previous limits from gamma-ray searches in Fermi Gamma-Ray Space Telescope data. The larger black holes considered in this paper may arise as the remnants of Dark Stars after the dark matter fuel is exhausted; thus neutrino observations may be used to constrain the properties of Dark Stars. The limits are particularly strong for heavier WIMPs. For WIMP masses $\sim 5$TeV, we show that $\lesssim 10\%$ of minihalos can host first stars that collapse into BHs larger than $10^3{M}_{\odot }$.

    ↳ astro-ph.COastro-ph.HEhep-phJCAP(2022)·5 citations
28. 28*

    NANOGrav Signal from the End of Inflation and the LIGO Mass and Heavier Primordial Black Holes

    Amjad Ashoorioon🇮🇷 · Kazem Rezazadeh🇮🇷 · Abasalt Rostami🇮🇷

    Releasing the 12.5-year pulsar timing array data, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has recently reported the evidence for a stochastic common-spectrum which would herald the detection of a stochastic gravitational wave background (SGWB) for the first time. We investigate if the signal could be generated from the end of a $\sim 10$ MeV but still phenomenologically viable double-field inflation when the field configuration settles to its true vacuum. During the double-field inflation at such scales, bubbles of true vacuum that can collapse to LIGO mass and heavier primordial black holes form. We show that only when this process happens with a first-order phase transition, the produced gravitational wave spectrum can match with the NANOGrav acclaimed SGWB signal. We show that the produced gravitational wave spectrum matches the NANOGrav SGWB signal only when this process happens through a first-order phase transition. Using LATTICEEASY, we also examine the previous observation in the literature that by lowering the scale of preheating, despite the shift of the peak frequency of the gravitational wave profile to smaller values, the amplitude of the SGWB could be kept almost constant. We notice that this observation breaks down at the preheating scale, $M\lesssim 10^{-14}{m}_{{}_{\mathrm{Pl}}}$.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2022)·136 citations
29. 29*

    Muon lateral distribution function of extensive air showers: results of the Sydney University Giant Air-shower Recorder versus modern Monte-Carlo simulations

    N.N. Kalmykov🇷🇺 · I.S. Karpikov🇷🇺 · G.I. Rubtsov🇷🇺 · S.V. Troitsky🇷🇺

    The Sydney University Giant Air-shower Recorder (SUGAR) measured the muon component of extensive air showers with a unique array of muon detectors. The SUGAR data allow us to reconstruct the empirical dependence of muon density on the distance from the axis of the shower, the lateral distribution function (LDF). We compare the shape of this function with the predictions of hadronic-interaction models, QGSJET-II-04 and EPOS-LHC, in the energy range 10^17.6 - 10^18.6 eV. We find a difference between the observed data and the simulation: the observed muon density falls faster with the increased core distance than it is predicted in simulations. This observation may be important for interpretation of the energy-dependent discrepancies in the simulated and observed numbers of muons in air showers, known as the "muon excess".

    ↳ astro-ph.HEhep-phPRD(2022)·3 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.