Fri·Nov 4, 2022Friday·November 4, 2022

1. 01*

   A Complete Set of the Dimension-8 Green's Basis Operators in the Standard Model Effective Field Theory

   Zhe Ren🇨🇳 · Jiang-Hao Yu🇨🇳

   We present a complete and independent off-shell Green's basis of the dimension 8 operators in the Standard Model effective field theory (SMEFT). We propose an off-shell amplitude formalism such that this new kind of amplitudes has a one-to-one correspondence to general operators carrying all kinds of redundancies. The advantage of such formalism is that all kinds of redundancies can be formulated explicitly in terms of the off-shell spinors and thus be removed systematically from the exhaustive list of the general off-shell amplitudes. Following such procedure, redundant operators can be reduced to the ones with the only redundancy from the equation of motion kept, the Green's basis. We find there are (993+1649) independent (on-shell + off-shell) operators for one generation of fermions and (44807+66197) ones for three generations at the dimension 8. This systematic method can be applied to obtain the Green's basis at any mass dimension for general EFTs.

   hep-phhep-thJHEP(2024)·32 citations
2. 02*

   Modern Machine Learning for LHC Physicists

   Tilman Plehn🇩🇪 · Anja Butter🇩🇪 · Barry Dillon🇩🇪 · Theo Heimel🇩🇪 · Claudius Krause🇺🇸 · Ramon Winterhalder🇩🇪

   Depending on the point of view, modern machine learning is either providing an unprecedented boost to the numerical methods of particle physics, or it is transforming the way we do science with vast amounts of complex data. In any case, it is crucial for young researchers to stay on top of this development and apply cutting-edge methods and tools to all LHC physics tasks. These lecture notes lead students with basic knowledge of particle physics and significant enthusiasm for machine learning to relevant applications. They start with an LHC-specific motivation and a non-standard introduction to neural networks and then cover classification, unsupervised classification, generative networks, data representations, and inverse problems. Three themes defining much of the discussion are statistically defined loss functions, uncertainties, and accuracy. To understand the applications, the notes include some aspects of theoretical LHC physics. All examples are chosen from particle physics publications of the last few years, and many of them come with corresponding tutorials.

   hep-ph118 citations
3. 03*

   Invisible Charm Exotica

   Michał Praszałowicz🇵🇱 · Maciej Kucab🇵🇱

   One possible interpretation of two narrow ${\Omega }_c^0$ states reported by the LHCb Collaboration at CERN in 2017 is that they are pentaquarks belonging to a $\overline{15}$ exotic SU(3) representation, as predicted by the Chiral Quark--Soliton Model. If so, there must exist a number of other exotic states since the model predicts three different $\overline{15}$ multiplets of heavy baryons. We show, that depending on the soliton spin $J$, these states are either very narrow or very broad. This explains why they might have escaped experimental observation. Furthermore, we show that the lightest members of these multiplets are stable against two body strong decays.

   hep-phPRD(2023)·6 citations
4. 04*

   Custodial Symmetry Violation in Scalar Extensions of the Standard Model

   Huayang Song🇨🇳 · Xia Wan🇨🇳 · Jiang-Hao Yu🇨🇳

   The new measurement of the W boson mass from the CDF collaboration shows a significant tension with the Standard Model prediction, which evidences violation of custodial symmetry in the scalar sector. We study the scalar extensions of the Standard Model, which can be categorized into two classes, scalar sector with custodial symmetry (Georgi-Machacek model and its generalizations) and scalar sector without custodial symmetry, and explore how these extensions fit to the electroweak precision data and the CDF new $m_W$ . The favored oblique parameters are coming from either the large mass splitting in the multiplet via the loop contribution or the large vacuum expectation value which breaks custodial symmetry at the tree level. In particular, we find that $\mathcal{O}(100)$ GeV new particles are allowed in the scalar extension scenarios.

   hep-phCPC(2023)·17 citations
5. 05*

   Towards identifying the minimal flavor symmetry behind neutrino oscillations

   Zhi-zhong Xing🇨🇳

   Current neutrino oscillation data indicate that the $3\times 3$ Pontecorvo-Maki-Nakagawa-Sakata matrix $U$ exhibits a $\mu$-$\tau$ flavor interchange symmetry $|U_{\mu i}^{}|=|U_{\tau i}^{}|$ (for $i=1,2,3$) as a good approximation. In particular, the T2K measurement implies that the maximal neutrino mixing angle ${\theta }_{23}^{}$ and the CP-violating phase $\delta$ should be close to $\pi /4$ and $-\pi /2$, respectively. Behind these observations lies a minimal flavor symmetry -- - the effective Majorana neutrino mass term keeps invariant under the transformations ${\nu }_{e\mathrm{L}}^{}\to ({\nu }_{e\mathrm{L}}^{}{)}^c$, ${\nu }_{\mu \mathrm{L}}^{}\to ({\nu }_{\tau \mathrm{L}}^{}{)}^c$ and ${\nu }_{\tau \mathrm{L}}^{}\to ({\nu }_{\mu \mathrm{L}}^{}{)}^c$. Extending this flavor symmetry to the canonical seesaw mechanism, we find that the $R$-matrix describing the strength of weak charged-current interactions of heavy Majorana neutrinos satisfies $|R_{\mu i}^{}|=|R_{\tau i}^{}|$ as a consequence of $|U_{\mu i}^{}|=|U_{\tau i}^{}|$. This result can be used to set a new upper bound, which is about three orders of magnitude more stringent than before, on the flavor mixing factor associated with the charged-lepton-flavor-violating decay mode ${\tau }^{-}\to e^{-}+\gamma$.

   hep-ph0 citations
6. 06*

   Harmonics of Parton Saturation in Lepton-Jet Correlations at the EIC

   Xuan-Bo Tong🇨🇳 · Bo-Wen Xiao🇨🇳 · Yuan-Yuan Zhang🇨🇳

   Parton saturation is one of the most intriguing phenomena in the high energy nuclear physics research frontier, especially in the upcoming era of the Electron-Ion Collider (EIC). The lepton-jet correlation in deep inelastic scattering provides us with a new gateway to the parton saturation at the EIC. In particular, we demonstrate that azimuthal angle anisotropies of the lepton-jet correlation are sensitive to the strength of the saturation momentum in the EIC kinematic region. In contrast to the predictions based on the collinear framework calculation, significant nuclear modification of the anisotropies is observed when we compare the saturation physics results in e + p and e + Au scatterings. By measuring these harmonic coefficients at the EIC, one can conduct quantitative analysis in different collisional systems and unveil compelling evidence for saturation effects.

   hep-phPRL(2023)·41 citations
7. 07*

   Charmed-strange tetraquarks and their decays in a potential quark model

   Feng-Xiao Liu🇨🇳 · Ru-Hui Ni🇨🇳 · Xian-Hui Zhong🇨🇳 · Qiang Zhao🇨🇳

   In the framework of a nonrelativistic potential quark model, we investigate the mass spectrum of the $1S$-wave charmed-strange tetraquark states of $cn\bar{s}\bar{n}$ and $cs\bar{n}\bar{n}$ ($n=u$ or $d$) systems. The tetraquark system is solved by a correlated Gaussian method. With the same parameters fixed by the meson spectra, we obtained the mass spectra for the $1S$-wave tetraquark states. Furthermore, based on the predicted tetraquark spectra we estimate their rearrangement decays in a quark-exchange model. We find that the rearrangement decays of the tetraquarks may be mainly driven by the spin-spin interactions. The resonances $X_0(2900{)}^0$ and $T_{c\bar{s}0}^a(2900{)}^{++/0}$ reported from LHCb may be assigned to be the lowest $1S$-wave tetraquark states ${\bar{T}}_{cs0}^f(2818)$ and $T_{c\bar{s}0}^a(2828)$ classified in the quark model, respectively. It also allows us to extract the couplings for the initial tetraquark states to their nearby $S$-wave interaction channels. We find that some of these couplings turn out to be sizeable. Following the picture of the wavefunction renormalization for the near-threshold strong $S$-wave interactions, the sizeable coupling strengths can be regarded as an indication of their dynamic origins as candidates for hadronic molecules. Furthermore, our predictions suggest that signals for the $1S$-wave charmed-strange tetraquark states can also be searched in the other channels, such as $D^0{K}^{+}$, $D^{+}{K}^{+}$, $D^{\ast +}{K}^{-}$, $D^{\ast +}{K}^{+}$, $D^{\ast 0}{K}^{+}$, $D^0{\bar{K}}^{\ast 0}$, $D_s^{+}{\rho }^0$, etc.

   hep-phhep-exnucl-thPRD(2023)·47 citations
8. 08*

   A seesaw model for large neutrino masses in concordance with cosmology

   Miguel Escudero🇨🇭 · Thomas Schwetz🇩🇪 · Jorge Terol-Calvo🇪🇸

   Cosmological constraints on the sum of the neutrino masses can be relaxed if the number density of active neutrinos is reduced compared to the standard scenario, while at the same time keeping the effective number of neutrino species $N_{\mathrm{eff}}\approx 3$ by introducing a new component of dark radiation. We discuss a UV complete model to realise this idea, which simultaneously provides neutrino masses via the seesaw mechanism. It is based on a $U(1)$ symmetry in the dark sector, which can be either gauged or global. In addition to heavy seesaw neutrinos, we need to introduce $\mathcal{O}(10)$ generations of massless sterile neutrinos providing the dark radiation. Then we can accommodate active neutrino masses with $\sum m_{\nu }\sim 1$ eV, in the sensitivity range of the KATRIN experiment. We discuss the phenomenology of the model and identify the allowed parameter space. We argue that the gauged version of the model is preferred, and in this case the typical energy scale of the model is in the 10 MeV to few GeV range.

   hep-phastro-ph.COJHEP(2023)·32 citations
9. 09*

   Probing the hadron mass spectrum in dense two-color QCD with the linear sigma model

   Daiki Suenaga🇯🇵 · Kotaro Murakami🇯🇵 · Etsuko Itou🇯🇵 · Kei Iida🇯🇵

   We investigate modifications of hadron masses at finite quark chemical potential in two-flavor and two-color QCD, of which the data are available from lattice simulations, within a linear sigma model based on approximate Pauli-Gursey $SU(4)$ symmetry. The model describes not only ground-state scalar diquarks and pseudo-scalar mesons but also the excited pseudo-scalar diquarks and scalar mesons; each ground-state diquark (meson) has the corresponding excited diquark (hadron) with opposite parity as a chiral partner. Effects of chiral symmetry breaking and diquark condensates are incorporated by a mean-field treatment. We show that various mixings among the hadrons, which are triggered by the breakdown of baryon number conservation in the superfluid phase, lead to a rich hadron mass spectrum. We discuss the influence of $U(1{)}_A$ anomaly on the density dependence of the mass spectrum and also manifestations of the chiral partner structures as density increases in the superfluid phase. The predicted hadron masses are expected to provide future lattice simulations with useful information on such symmetry properties in dense two-color QCD.

   hep-phhep-latnucl-thPRD(2023)·22 citations
10. 10*

    Study of light sterile neutrino at the long-baseline experiment options at KM3NeT

    Dinesh Kumar Singha🇮🇳 · Monojit Ghosh🇭🇷 · Rudra Majhi🇮🇳 · Rukmani Mohanta🇮🇳

    In this paper, we study the capability of different long-baseline experiment options at the KM3NeT facility i.e., P2O, Upgraded P2O and P2SO to probe the light sterile neutrino and compare their sensitivities with DUNE. The P2O option will have neutrinos from a 90 KW beam at Protvino to be detected at the ORCA detector, the Upgraded P2O will have neutrinos from the upgraded 450 KW beam to be detected at the ORCA detector and the option P2SO will have neutrinos from a 450 KW beam to be detected at the upgraded Super-ORCA detector. All these options will have a baseline around 2595 km. Our results show that the experiments at the KM3NeT (DUNE) would be more sensitive if the value of $\Delta m_{41}^2$ is around 10 (1) eV${}^2$. Our results also show that the role of near detector is very important for the study of sterile neutrinos and addition of near detector improves the sensitivity as compared to only far detector for 3+1 scenario. Among the three options at KM3NeT, the sensitivity of P2O and upgraded P2O is limited and sensitivity of P2SO is either comparable or better than DUNE.

    hep-phPRD(2023)·19 citations
11. 11*

    Theoretical investigation of the molecular nature of $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ and the possibility of observing the $D\bar{D}K$ bound state $K_{c\bar{c}}(4180)$ in inclusive $e^{+}{e}^{-}\to c\bar{c}$ collisions

    Tian-Chen Wu🇨🇳 · Li-Sheng Geng🇨🇳

    Searching for exotic multiquark states and elucidating their nature remains a central topic in understanding quantum chromodynamics--the underlying theory of the strong interaction. Two of the most studied such states are the charm-strange states $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$. In this letter, we show for the first time that their prompt production yields in inclusive $e^{+}{e}^{-}\to c\bar{c}$ collisions near $\sqrt{s}=10.6$ GeV measured by the BABAR Collaboration, $Y(D_{s0}^{\ast }(2317))$ and $Y(D_{s1}(2460))$, in particular the ratio $R=Y(D_{s0}^{\ast }(2317))/Y(D_{s1}(2460))$, can be well explained in the molecular picture, which provide a highly nontrivial verification of their nature being $DK/D^{\ast }K$ molecules. On the contrary, treating them as pure $c\bar{s}$ $P-$wave states, the statistical model predicts a ratio $R$ smaller than unity, in contrast with the experimental central value, though in agreement with it considering its relatively large uncertainty. In addition, we predict the production yield of the $D\bar{D}K$ three-body bound state, $K_{c\bar{c}}(4180)$, in $e^{+}{e}^{-}\to c\bar{c}$ collisions and find that it is within the reach of the ongoing Belle II experiment. The present study demonstrates the feasibility of a novel method to unravel the nature of exotic hadrons and the potential of electron-positron collisions in this regard.

    hep-phhep-exhep-latPRD(2023)·14 citations
12. 12*

    Ultralight dark matter searches at the sub-Hz frontier with atom multigradiometry

    Leonardo Badurina🇬🇧 · Valerie Gibson🇬🇧 · Christopher McCabe🇬🇧 · Jeremiah Mitchell🇬🇧

    Single-photon atom gradiometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultralight scalar dark matter (ULDM). In the sub-Hz regime the background is expected to be dominated by gravity gradient noise (GGN), which arises as a result of mass fluctuations around the experiment. In this work we model the GGN as surface Rayleigh waves, and we construct a likelihood-based analysis that consistently folds GGN into the sensitivity estimates of vertical atom gradiometers in the frequency window between 1 mHz and 1 Hz. We show that in certain geological settings GGN can be significantly mitigated when operating a multigradiometer configuration, which consists of three or more atom interferometers in the same baseline. Multigradiometer experiments, such as future versions of AION and MAGIS-100, have the potential to probe regions of scalar ULDM parameter space in the sub-Hz regime that have not been excluded by existing experiments.

    hep-phastro-ph.COgr-qcPRD(2023)·44 citations
13. 13*

    $X(3872)$, $X(4014)$, and their bottom partners at finite temperature

    Gloria Montaña🇺🇸 · Angels Ramos🇪🇸 · Laura Tolos🇪🇸 · Juan M. Torres-Rincon🇪🇸

    The properties of the $X(3872)$ and its spin partner, the $X(4014)$, are studied both in vacuum and at finite temperature. Using an effective hadron theory based on the hidden-gauge Lagrangian, the $X(3872)$ is dynamically generated from the $s$-wave rescattering of a pair of pseudoscalar and vector charm mesons. By incorporating the thermal spectral functions of open charm mesons, the calculation is extended to finite temperature. Similarly, the properties of the $X(4014)$ are obtained out of the scattering of charm vector mesons. By applying heavy-quark flavor symmetry, the properties of their bottom counterparts in the axial-vector and tensor channels are also predicted. All the dynamically generated states show a decreasing mass and acquire an increasing decay width with temperature, following the trend observed in their meson constituents. These results are relevant in relativistic heavy-ion collisions at high energies, in analyses of the collective medium formed after hadronization or in femtoscopic studies, and can be tested in lattice-QCD calculations exploring the melting of heavy mesons at finite temperature.

    hep-phnucl-thPRD(2023)·23 citations
14. 14*

    $U(1{)}_{Y^{\prime }}$ universal seesaw

    Su-Ping Chen🇨🇳 · Pei-Hong Gu🇨🇳

    We extend the $SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y$ standard model by a $U(1{)}_{Y^{\prime }}$ gauge symmetry. Three right-handed neutrinos are introduced to cancel the gauge anomaly. One Higgs singlet is responsible for spontaneously breaking the $U(1{)}_{Y^{\prime }}$ symmetry while the standard model Higgs doublet does not carry any $U(1{)}_{Y^{\prime }}$ charges. The down-type quarks, up-type quarks, charged leptons and neutral neutrinos obtain their Dirac masses through four types of dimension-5 operators constructed by the fermion doublets and singlets with the Higgs doublet and singlet. This effective theory is realized in three renormalizable contexts with heavy fermion singlets, scalar doublets and fermion doublets. The heavy fermion singlets and doublets for generating the neutrino masses also accommodate a successful Dirac leptogenesis to explain the baryon asymmetry in the universe.

    hep-phNPB(2023)·7 citations
15. 15*

    Detecting nuclear mass distribution in isobar collisions via charmonium

    Jiaxing Zhao🇨🇳 · Shuzhe Shi🇺🇸

    The collective properties of final state hadrons produced in the high statistics ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ are found to be significantly different. Such differences were argued to be precise probes of the difference in nucleon distribution in the isobar nuclei. We investigate the $J/\psi$ production in the isobar collision via a relativistic transport approach. By comparing the isobar systems according to equal centrality bin and equal multiplicity bin, we find that the yield ratio of $J/\psi$ is sensitive to the differences in both the number of binary collisions and the medium evolution. Besides, the elliptic flow $v_2$ of $J/\psi$ is qualitatively different from the light hadrons, and the ratio between Ru+Ru and Zr+Zr collisions is sensitive to the medium evolution. The charmonium production provides an independent probe to study the nucleon distribution in the isobar system.

    hep-phnucl-thEPJC(2023)·8 citations
16. 16*

    Charged Higgs boson signatures via $pp\to H^{\pm }bj$ in 2HDM type-I

    R. Benbrik🇲🇦 · M. Krab🇲🇦 · B. Manaut🇲🇦 · M. Ouchemhou🇲🇦

    In this study, we investigate the light charged Higgs boson production via $pp\to H^{\pm }bj$ in the type-I configuration of the Two-Higgs Doublet Model (2HDM). In the viable parameter space, assuming either $h$ or $H$ is the SM-like Higgs boson observed at the Large Hadron Collider (LHC), we focus on the bosonic decays $H^{\pm }\to W^{\pm }A/h$ and examine the final states arising from the above charged Higgs production and decay. We show here that the suggested signatures can have sizable rates, reaching the pb level, when the top quark is produced on-shell and $\tan \beta$ is small.

    hep-phPoS·1 citation
17. 17*

    Neutrino Origin of LHAASO's 18 TeV GRB221009A Photon

    Vedran Brdar🇨🇭 · Ying-Ying Li🇨🇳

    LHAASO collaboration detected photons with energy above 10 TeV from the most recent gamma-ray burst (GRB), GRB221009A. Given the redshift of this event, $z\sim 0.15$, photons of such energy are expected to interact with the diffuse extragalactic background light (EBL) well before reaching Earth. In this paper we provide a novel neutrino-related explanation of the most energetic 18 TeV event reported by LHAASO. We find that the minimal viable scenario involves both mixing and transition magnetic moment portal between light and sterile neutrinos. The production of sterile neutrinos occurs efficiently via mixing while the transition magnetic moment portal governs the decay rate in the parameter space where tree-level decays via mixing to non-photon final states are suppressed. Our explanation of this event, while being consistent with the terrestrial constraints, points to the non-standard cosmology.

    hep-phastro-ph.COastro-ph.HEPLB(2023)·26 citations
18. 18*

    Optimal transport for a novel event description at hadron colliders

    Loukas Gouskos🇨🇭 · Fabio Iemmi🇨🇳 · Sascha Liechti🇨🇭 · Benedikt Maier🇨🇭 · Vinicius Mikuni🇺🇸 · Huilin Qu🇨🇭

    We propose a novel strategy for disentangling proton collisions at hadron colliders such as the LHC that considerably improves over the current state of the art. Employing a metric inspired by optimal transport problems as the cost function of a graph neural network, our algorithm is able to compare two particle collections with different noise levels and learns to flag particles originating from the main interaction amidst products from up to 200 simultaneous pileup collisions. We thereby sidestep the critical task of obtaining a ground truth by labeling particles and avoid arduous human annotation in favor of labels derived in situ through a self-supervised process. We demonstrate how our approach - which, unlike competing algorithms, is trivial to implement - improves the resolution in key objects used in precision measurements and searches alike and present large sensitivity gains in searching for exotic Higgs boson decays at the High-Luminosity LHC.

    hep-phPRD(2023)·9 citations
19. 19*

    Dimension-5 baryon-number violation in low-scale Pati-Salam

    Tomasz P. Dutka🇰🇷 · John Gargalionis🇪🇸

    The gauge bosons of Pati-Salam do not mediate proton decay at the renormalisable level, and for this reason it is possible to construct scenarios in which $SU(4)\otimes SU(2{)}_R$ is broken at relatively low scales. In this Letter we show that such low-scale models generate dimension-5 operators that can give rise to nucleon decays at unacceptably large rates, even if the operators are suppressed by the Planck scale. We find an interesting complementarity between the nucleon-decay limits and the usual meson-decay constraints. Furthermore, we argue that these operators are generically present when the model is embedded into $SO(10)$, lowering the suppression scale. Under reasonable assumptions, the lower limit on the breaking scale can be constrained to be as high as $\mathcal{O}(10^8)$ GeV.

    hep-phPRD(2023)·4 citations
20. 20*

    Dark matter production through a non-thermal flavon portal

    Andrew Cheek🇵🇱 · Jacek K. Osiński🇵🇱 · Leszek Roszkowski🇵🇱 · Sebastian Trojanowski🇵🇱

    The Froggatt-Nielsen (FN) mechanism provides an attractive way of generating the determined fermion mass hierarchy and quark mixing matrix elements in the Standard Model (SM). Here we extend it by coupling the FN field, the flavon, to a dark sector containing one or more dark matter particles which are produced non-thermally sequentially through flavon production. Non-thermal flavon production occurs efficiently via freeze-in and through field oscillations. We explore this in the regime of high-scale breaking $\Lambda$ of the global $U(1{)}_{\text{FN}}$ group and at the reheating temperature $T_R\ll \Lambda$ where the flavon remains out of equilibrium at all times. We identify phenomenologically acceptable regions of $T_R$ and the flavon mass where the relic abundance of dark matter and other cosmological constraints are satisfied. In the case of one-component dark matter we find an effective upper limit on the FN charges at high $\Lambda$, i.e. $Q_{\mathrm{FN}}^{\mathrm{DM}}\le 13$. In the multi-component dark sector scenario the dark matter can be the heaviest dark particle that can be effectively stable at cosmological timescales, alternatively it can be produced sequentially by decays of the heavier ones. For scenarios where dark decays occur at intermediate timescales, i.e. $t\sim 0.1-10^{28}\mathrm{s}$, we find that existing searches can effectively probe interesting regions of parameter space. These searches include indirect probes on decays such as $\gamma$-ray and neutrino telescopes as well as analyses of the Cosmic Microwave Background, as well as constraints on small scale structure formation from the Lyman-$\alpha$ forest. We comment on the future prospects of such probes, place projected sensitivities, and discuss how this scenario could accommodate the cosmological $S_8$ tension.

    hep-phastro-ph.COJHEP(2023)·11 citations
21. 21*

    Unbinned multivariate observables for global SMEFT analyses from machine learning

    Raquel Gomez Ambrosio🇮🇹 · Jaco ter Hoeve🇳🇱 · Maeve Madigan🇬🇧 · Juan Rojo🇳🇱 · Veronica Sanz🇪🇸

    Theoretical interpretations of particle physics data, such as the determination of the Wilson coefficients of the Standard Model Effective Field Theory (SMEFT), often involve the inference of multiple parameters from a global dataset. Optimizing such interpretations requires the identification of observables that exhibit the highest possible sensitivity to the underlying theory parameters. In this work we develop a flexible open source framework, ML4EFT, enabling the integration of unbinned multivariate observables into global SMEFT fits. As compared to traditional measurements, such observables enhance the sensitivity to the theory parameters by preventing the information loss incurred when binning in a subset of final-state kinematic variables. Our strategy combines machine learning regression and classification techniques to parameterize high-dimensional likelihood ratios, using the Monte Carlo replica method to estimate and propagate methodological uncertainties. As a proof of concept we construct unbinned multivariate observables for top-quark pair and Higgs+$Z$ production at the LHC, demonstrate their impact on the SMEFT parameter space as compared to binned measurements, and study the improved constraints associated to multivariate inputs. Since the number of neural networks to be trained scales quadratically with the number of parameters and can be fully parallelized, the ML4EFT framework is well-suited to construct unbinned multivariate observables which depend on up to tens of EFT coefficients, as required in global fits.

    hep-phhep-exJHEP(2023)·40 citations
22. 22*

    Black hole superradiance to search for new particles

    D. Blas🇪🇸

    Rotational superradiance generates the amplification of incoming waves of sufficiently low frequency when scattered with a rotating absorbing body. This may be used to discover new \emph{bosonic} particles of mass $m_b$ if the rotating body has a sufficiently strong gravitational field, that may confine the massive particle and turn amplification into exponential growth. As a result, the initial seed may be amplified until generating a large cloud around the body, which may have a number of phenomenological consequences. Rotating black holes are perfect candidates to source this effect, not only from their absorbing and gravitational properties (and hence confining mechanism), but also because for black holes of mass $M_{\mathrm{BH}}$, rotational superradiance is efficient for $m_b\sim 10^{-10}\left(\frac{M_{\odot }}{M_{\mathrm{BH}}}\right)\mathrm{eV}$. The wide range of astrophysical black hole masses brings about new opportunities to probe particles of low masses in a large span very hard to detect by any other known method. In this brief contribution I will comment on some of these opportunities.

    hep-phastro-ph.COastro-ph.HE2 citations
23. 23*

    The QCD topological susceptibility at high temperatures via staggered fermions spectral projectors

    Andreas Athenodorou🇨🇾 · Claudio Bonanno🇮🇹 · Claudio Bonati🇮🇹 · Giuseppe Clemente🇩🇪 · Francesco D'Angelo🇮🇹 · Massimo D'Elia🇮🇹 · Lorenzo Maio🇮🇹 · Guido Martinelli🇮🇹 · Francesco Sanfilippo🇮🇹 · Antonino Todaro🇨🇾

    The QCD topological observables are essential inputs to obtain theoretical predictions about axion phenomenology, which are of utmost importance for current and future experimental searches for this particle. Among them, we focus on the topological susceptibility, related to the axion mass. We present lattice results for the topological susceptibility in QCD at high temperatures obtained by discretizing this observable via spectral projectors on eigenmodes of the staggered Dirac operator, and we compare them with those obtained with the standard gluonic definition. The adoption of the spectral discretization is motivated by the large lattice artifacts affecting the standard gluonic susceptibility, related to the choice of non-chiral fermions in the lattice action.

    ↳ hep-lathep-phPoS·0 citations
24. 24*

    Study on $\Lambda nn$ Bound State and Resonance

    Thiri Yadanar Htun🇹🇭 · Yupeng Yan🇹🇭

    We perform the ab initio no-core shell model (NCSM) calculation to investigate the bound state problem of the three-body $\Lambda nn$ system in chiral next-to-next-to-leading-order NN and chiral leading-order YN interactions. The calculations show that no $\Lambda nn$ bound state exists, but predict a low-lying $\Lambda nn$ resonant state near the threshold with the energy of $E_r=0.124$ MeV and the width of about $\Gamma =1.161$ MeV. In searching for $\Lambda nn$ resonances, we extend the NCSM calculation to the continuum state by employing the J-matrix formalism in the scattering theory with the hyperspherical oscillator basis.

    ↳ nucl-thhep-phPRC(2022)·3 citations
25. 25*

    Primordial non-gaussianity up to all orders: theoretical aspects and implications for primordial black hole models

    Giacomo Ferrante🇫🇷 · Gabriele Franciolini🇮🇹 · Antonio Junior Iovino🇮🇹 · Alfredo Urbano🇮🇹

    We develop an exact formalism for the computation of the abundance of primordial black holes (PBHs) in the presence of local non-gaussianity (NG) in the curvature perturbation field. For the first time, we include NG going beyond the widely used quadratic and cubic approximations, and consider a completely generic functional form. Adopting threshold statistics of the compaction function, we address the computation of the abundance both for narrow and broad power spectra. While our formulas are generic, we discuss explicit examples of phenomenological relevance considering the physics case of the curvaton field. We carefully assess under which conditions the conventional perturbative approach can be trusted. In the case of a narrow power spectrum, this happens only if the perturbative expansion is pushed beyond the quadratic order (with the optimal order of truncation that depends on the width of the spectrum). Most importantly, we demonstrate that the perturbative approach is intrinsically flawed when considering broad spectra, in which case only the non-perturbative computation captures the correct result. Finally, we describe the phenomenological relevance of our results for the connection between the abundance of PBHs and the stochastic gravitational wave (GW) background related to their formation. As NGs modify the amplitude of perturbations necessary to produce a given PBHs abundance and boost PBHs production at large scales for broad spectra, modelling these effects is crucial to connect the PBH scenario to its signatures at current and future GWs experiments.

    ↳ astro-ph.COgr-qchep-phPRD(2023)·163 citations
26. 26*

    Discovering a new well: Decaying dark matter with profile likelihoods

    Emil Brinch Holm🇩🇰 · Laura Herold🇩🇪 · Steen Hannestad🇩🇰 · Andreas Nygaard🇩🇰 · Thomas Tram🇩🇰

    A large number of studies, all using Bayesian parameter inference from Markov Chain Monte Carlo methods, have constrained the presence of a decaying dark matter component. All such studies find a strong preference for either very long-lived or very short-lived dark matter. However, in this letter, we demonstrate that this preference is due to parameter volume effects that drive the model towards the standard $\Lambda$CDM model, which is known to provide a good fit to most observational data. Using profile likelihoods, which are free from volume effects, we instead find that the best-fitting parameters are associated with an intermediate regime where around $3\%$ of cold dark matter decays just prior to recombination. With two additional parameters, the model yields an overall preference over the $\Lambda$CDM model of $\Delta {\chi }^2\approx -2.8$ with \textit{Planck} and BAO and $\Delta {\chi }^2\approx -7.8$ with the SH0ES $H_0$ measurement, while only slightly alleviating the $H_0$ tension. Ultimately, our results reveal that decaying dark matter is more viable than previously assumed, and illustrate the dangers of relying exclusively on Bayesian parameter inference when analysing extensions to the $\Lambda$CDM model.

    ↳ astro-ph.COastro-ph.IMhep-phPRD(2023)·31 citations
27. 27*

    Impact of multiple modes on the evolution of self-interacting axion condensate around rotating black holes

    Hidetoshi Omiya🇯🇵 · Takuya Takahashi🇯🇵 · Takahiro Tanaka🇯🇵 · Hirotaka Yoshino🇯🇵

    Ultra-light particles, such as axions, form a macroscopic condensate around a highly spinning black hole by the superradiant instability. Due to its macroscopic nature, the condensate opens the possibility of detecting the axion through gravitational wave observations. However, the precise evolution of the condensate must be known for the actual detection. For future observation, we numerically study the influence of the self-interaction, especially interaction between different modes, on the evolution of the condensate in detail. First, we focus on the case when condensate starts with the smallest possible angular quantum number. For this case, we perform the non-linear calculation and show that the dissipation induced by the mode interaction is strong enough to saturate the superradiant instability, even if the secondary cloud starts with quantum fluctuations. Our result indicates that explosive phenomena such as bosenova do not occur in this case. We also show that the condensate settles to a quasi-stationary state mainly composed of two modes, one with the smallest angular quantum number for which the superradiant instability occurs and the other with the adjacent higher angular quantum number. We also study the case when the condensate starts with the dominance of the higher angular quantum number. We show that the dissipation process induced by the mode coupling does not occur for small gravitational coupling. Therefore, bosenova might occur in this case.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2023)·52 citations
28. 28*

    On ALP scenarios and GRB 221009A

    Pierluca Carenza🇸🇪 · M.C. David Marsh🇸🇪

    The extraordinarily bright gamma-ray burst GRB 221009A was observed by a large number of observatories, from radio frequencies to gamma-rays. Of particular interest are the reported observations of photon-like air showers of very high energy: an 18 TeV event in LHAASO and a 251 TeV event at Carpet-2. Gamma rays at these energies are expected to be absorbed by pair-production events on background photons when travelling intergalactic distances. Several works have sought to explain the observations of these events, assuming they originate from GRB 221009A, by invoking axion-like particles (ALPs). We reconsider this scenario and account for astrophysical uncertainties due to poorly known magnetic fields and background photon densities. We find that, robustly, the ALP scenario cannot simultaneously account for an 18 TeV and a 251 TeV photon from GRB 221009A.

    ↳ astro-ph.HEhep-ph29 citations
29. 29*

    Improved muon decay simulation with McMule and Geant4

    A. Gurgone🇮🇹 · A. Papa🇨🇭 · P. Schwendimann🇺🇸 · A. Signer🇨🇭 · Y. Ulrich🇬🇧 · A. M. Baldini🇮🇹 · F. Cei🇮🇹 · M. Chiappini🇮🇹 · M. Francesconi🇮🇹 · L. Galli🇮🇹 · M. Grassi🇮🇹 · D. Nicolò🇮🇹 · G. Signorelli🇮🇹

    The physics programme of the MEG II experiment can be extended with the search for new invisible particles produced in rare muon decays. The hunt for such elusive signals requires accurate simulations to characterise the detector response and estimate the experimental sensitivity. This work presents an improved simulation of muon decay in MEG II, based on McMule and Geant4.

    ↳ hep-exhep-phNucl.Instrum.Meth.A(2023)·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.