Thu·Aug 3, 2023Thursday·August 3, 2023

1. 01*

   Theory of the (Heavy-Quark) Exotic Hadrons: A Primer for the Flavor Community

   Richard F. Lebed🇺🇸

   Scores of exotic hadrons, particularly tetraquarks and pentaquarks in the heavy-quark sector, have been observed in the past 20 years, and more continue to be discovered to this day. Unlike mesons and baryons, such exotics are not mandated to exist under our current understanding of QCD, meaning that each new discovery presents fresh insights into the expansive possibilities of strong-interaction physics. Even the basic architecture of these multiquark states remains an open question. Here we discuss the merits and deficiencies of their best-known dynamical descriptions, recognizing that the eventual universal model for exotics will almost certainly require the synthesis of more than one fundamental paradigm.

   hep-phhep-exnucl-thPoS(2023)·17 citations
2. 02*

   How Many Dark Neutrino Sectors Does Cosmology Allow?

   Alan Zander🇩🇪 · Manuel Ettengruber🇩🇪 · Philipp Eller🇩🇪

   We present the very first constraints on the number of Standard Model (SM) copies with an additional Dirac right-handed neutrino. From cosmology, we are able to pose strong limits on large regions of the parameter space. Moreover, we show that it is possible to account for the right dark matter density in form of stable particles from the dark sectors.

   hep-phEPJC(2024)·4 citations
3. 03*

   A high-energy QCD portal to exotic matter: Heavy-light tetraquarks at the HL-LHC

   Francesco Giovanni Celiberto🇪🇸 · Alessandro Papa🇮🇹

   By taking advantage of the natural stability of the high-energy resummation, recently discovered in the context of heavy-flavor studies, we investigate the inclusive hadroproduction of a neutral heavy-light, hidden-flavored tetraquark ($X_{cu\bar{c}\bar{u}}$ or $X_{bs\bar{b}\bar{s}}$ state), in association with a heavy (single $c$- or $b$-flavored) hadron or a light jet at the (HL-)LHC. We make use of the JETHAD multi-modular working package to provide predictions for rapidity, azimuthal-angle and transverse-momentum distributions calculated via the hybrid high-energy and collinear factorization, where the Balitsky--Fadin--Kuraev--Lipatov resummation of energy logarithms is supplemented by collinear parton densities and fragmentation functions. We rely upon the single-parton fragmentation mechanism, valid in the large transverse-momentum regime, to describe the tetraquark production. Our study represents a first attempt at bridging the gap between all-order calculations of high-energy QCD and the exotics.

   hep-phPLB(2024)·39 citations
4. 04*

   Search for an invisible scalar in $t\bar{t}$ final states at the LHC

   Duarte Azevedo🇩🇪 · Rodrigo Capucha🇵🇹 · Pedro Chaves🇵🇹 · João Bravo Martins🇵🇹 · António Onofre🇵🇹 · Rui Santos🇵🇹

   We use the current $t\bar{t}$ experimental analysis to look for Dark Matter (DM) particles hidden in the final state. We present a phenomenological study where we successfully perform the reconstruction of a $t\bar{t}$ system in the presence of a scalar mediator $Y_0$, that couples to both Standard Model (SM) and to DM particles. We use a \texttt{MadGraph5\_aMC@NLO} simplified DM model, where signal samples of $pp\to t\bar{t}{Y}_0$ are generated at the Large Hadron Collider (LHC) with both Charge-Parity (CP) -even and CP-odd couplings of $Y_0$ to the top quarks. Different mass scales for the $Y_0$ mediator are considered, from the low mass region ($\sim$ 0~GeV) to masses close to the Higgs boson mass (125~GeV). The dileptonic final states of the $t\bar{t}$ system were used in our analysis. The reconstruction of the $t\bar{t}$ system is done with a kinematic fit, without reconstructing the mediator. All relevant SM backgrounds for the dileptonic $t\bar{t}$ search at the LHC are considered. Furthermore, CP angular observables were used to probe the CP-nature of the coupling between the mediator and top-quarks, which allowed to set confidence level (CL) limits for those Yukawa couplings as a function of the mediator mass.

   hep-phhep-exJHEP(2023)·5 citations
5. 05*

   Axion-like particles and high-energy gamma rays: interconversion revisited

   Rafael Alves Batista🇪🇸 · Cristina Viviente🇪🇸 · Gaetano Di Marco🇪🇸 · Miguel A. Sánchez-Conde🇪🇸

   Axion-like particles (ALPs) are hypothetical entities often invoked to solve various problems in particle physics to cosmology. They are one of the most promising candidates to explain the elusive dark matter. A way to search for ALPs is through their effects on photons. In the presence of external magnetic fields, ALPs and photons can convert into one another, leading to measurable signals. In this contribution we present results of Monte Carlo simulations of ALP-photon interconversion in magnetised environments. We focus on high-energy gamma rays with TeV energies travelling over cosmological distances. We include a full treatment of the intergalactic electromagnetic cascades triggered by the gamma rays. Finally, we discuss the impact of this improved treatment of the propagation for current and future ALP searches.

   hep-phastro-ph.COastro-ph.HEPoS(2023)·5 citations
6. 06*

   Excitation spectra of heavy baryons in a quark-diquark model with relativistic corrections

   S. Kinutani🇯🇵 · H. Nagahiro🇯🇵 · D. Jido🇯🇵

   The excitation spectra of \Lambda_c and \Lambda_b baryons are investigated by using a quark-diquark model in which a single-heavy baryon is treated as the bound state of a heavy quark and a scalar diquark. We take two types of relativistic corrections into account for the quark-diquark potential. In the first type, we consider the one-gluon exchange between the heavy quark and one of the light quarks in the diquark. In the second, we consider the one-gluon exchange between a scalar particle and a heavy quark. We find that there is a large difference between two types of corrections due to different treatment of the internal color structure of the diquark. The relativistic corrections are important for the solution to the string tension puzzle, particularly, the Darwin term makes a large contribution.

   hep-phPRD(2023)·2 citations
7. 07*

   Molecular pentaquark states with open charm and bottom flavors

   Jia-Xin Lin🇨🇳 · Hua-Xing Chen🇨🇳 · Wei-Hong Liang🇨🇳 · Wen-Ying Liu🇨🇳 · Dan Zhou🇨🇳

   We study the possibly-existing molecular pentaquark states with open charm and bottom flavors, {\it i.e.}, the states with the quark contents $c\bar{b}qqq$ and $b\bar{c}qqq$ ($q=u,d,s$). We investigate the meson-baryon interactions through the coupled-channel unitary approach within the local hidden-gauge formalism, and extract the poles by solving the Bethe-Salpeter equation in coupled channels. These poles qualify as molecular pentaquark states, which are dynamically generated from the meson-baryon interactions through the exchange of vector mesons. Our results suggest the existence of the ${\Sigma }_c^{(\ast )}{B}^{(\ast )}$ and ${\Sigma }_b^{(\ast )}{\bar{D}}^{(\ast )}$ molecular states with isospin $I=1/2$, the ${\Xi }_c^{(\prime ,\ast )}{B}^{(\ast )}$ and ${\Xi }_b^{(\prime ,\ast )}{\bar{D}}^{(\ast )}$ molecular states with isospin $I=0$ and $I=1$, as well as the ${\Omega }_c^{(\ast )}{B}^{(\ast )}$ and ${\Omega }_b^{(\ast )}{\bar{D}}^{(\ast )}$ molecular states with isospin $I=1/2$.

   hep-phhep-exEPJA(2024)·13 citations
8. 08*

   Exploring CP Violation beyond the Standard Model and the PQ Quality with Electric Dipole Moments

   Kiwoon Choi🇰🇷 · Sang Hui Im🇰🇷 · Krzysztof Jodłowski🇰🇷

   In some models of physics beyond the Standard Model (SM), one of the leading low energy consequences of the model appears in the form of the chromo-electric dipole moments (CEDMs) of the gluons and light quarks. We examine if these CEDMs can be distinguished from the QCD $\theta$-term through the experimentally measurable nuclear and atomic electric dipole moments (EDMs) in both cases with and without the Peccei-Quinn (PQ) mechanism solving the strong CP problem. We find that the nucleon EDMs show a distinctive pattern when the EDMs are dominantly induced by the light quark CEDMs without the PQ mechanism. In the presence of the PQ mechanism, the QCD $\theta$-parameter corresponds to the vacuum value of the axion field, which might be induced either by CEDMs or by UV-originated PQ breaking other than the QCD anomaly, for instance the PQ breaking by quantum gravity effects. We find that in case with the PQ mechanism the nucleon EDMs have a similar pattern regardless of what is the dominant source of EDMs among the CEDMs and $\theta$-term, unless there is a significant cancellation between the contributions from different sources. In contrast, some nuclei or atomic EDMs can have characteristic patterns significantly depending on the dominant source of EDMs, which may allow identifying the dominant source among the CEDMs and $\theta$-term. Yet, discriminating the gluon CEDM from the QCD $\theta$-parameter necessitates additional knowledge of low energy parameters induced by the gluon CEDM, which is not available at the moment. Our results imply that EDMs can reveal unambiguous sign of CEDMs while identifying the origin of the axion vacuum value, however it requires further knowledge of low energy parameters induced by the gluon CEDM.

   hep-phhep-exhep-thJHEP(2024)·6 citations
9. 09*

   Weak interaction corrections to muon pair production via the photon fusion at the LHC

   S. I. Godunov🇷🇺 · E. K. Karkaryan🇷🇺 · V. A. Novikov🇷🇺 · A. N. Rozanov🇫🇷 · M. I. Vysotsky🇷🇺 · E. V. Zhemchugov🇷🇺

   Analytical formulas describing the correction due to the $Z$ boson exchange to the cross section of the reaction $pp\to p{\mu }^{+}{\mu }^{-}X$ are presented. When the invariant mass of the produced muon pair $W\gtrsim 150\text{GeV}$ and its total transverse momentum is large, the correction is of the order of 20%.

   hep-phhep-exPRD(2023)·7 citations
10. 10*

    Picturing QCD jets in anisotropic matter: from jet shapes to Energy Energy Correlators

    João Barata🇺🇸 · José Guilherme Milhano🇵🇹 · Andrey V. Sadofyev🇪🇸

    Recent theoretical developments in the description of jet evolution in the quark gluon plasma have allowed to account for the effects of hydrodynamic gradients in the medium modified jet spectra. These constitute a crucial step towards using jets as tomographic probes of the nuclear matter they traverse. In this work, we complement these studies by providing leading order calculations of widely studied jet observables, taking into account matter anisotropies. We show that the energy distribution inside a jet is pushed towards the direction of the largest matter anisotropy, while the away region is depleted. As a consequence, the jet mass and girth gain a non-trivial azimuthal dependence, with the average value of the distribution increasing along the direction of largest gradients. However, we find that, for these jet shapes, matter anisotropic effects can be potentially suppressed by vacuum Sudakov factors. We argue that the recently proposed measurements of energy correlations within jets do not suffer from such effects, with the azimuthal dependence being visible in a large angular window, regardless of the shape of the distribution.

    hep-phEPJC(2024)·80 citations
11. 11*

    Extragalactic TeV Photons and the Zero-point Vibration Spectrum Limit

    I. L. Zhogin🇷🇺

    There are observations indicating a possible anomalous transparency of intergalactic space (filled with infrared background light) for extragalactic gamma-rays of very high energy (> 100 GeV). The anomaly is usually associated with effects of some new physics. However, another explanation is possible -- as a manifestation relating to a cut-off of the zero-point vibration spectrum. It is assumed that this boundary U_{ZV} is isotropic in the reference frame, where the cosmic microwave background (CMB) radiation is isotropic, and an estimate is obtained: U_{ZV} ~7.4 TeV. The presence of a ZV boundary also leads to an increased beta decay time of accelerated particles with the Lorentz factor > 50. It is widely believed that the ZV-spectrum continues up to the Planck energy. There is, however, a 5D variant of the Absolute Parallelism theory (AP), free from singularities of solutions, where a large characteristic length L appears, which determines the thickness of expanding spherical S^3-shell (the cosmological solution as the longitudinal wave along the radius) in co-moving co-ordinates. Newton's Law 1/r^2 is replaced by 1/r at distances exceeding L, and the Planck length (a composite parameter) `arises' from L when switching to the conventional energy-momentum scale. The theory features are briefly exposed -- description of 15 polarizations (degrees of freedom), the energy-momentum tensor (in prolonged 4th order equations), topological charges and quasi-charges of localized field configurations.

    hep-phastro-ph.HEgr-qc0 citations
12. 12*

    Joint Track Functions: Expanding the Space of Calculable Correlations at Colliders

    Kyle Lee🇺🇸 · Ian Moult🇺🇸

    The theoretical description of observables at collider experiments relies on factorization theorems separating perturbative dynamics from universal non-perturbative matrix elements. Despite significant recent progress in extending these factorization theorems to increasingly differential jet substructure observables, the focus has been primarily on infrared safe observables sensitive only to correlations in the energy of final state hadrons. However, significant information about the dynamics of the underlying collision is encoded in how energy is correlated between hadrons of different quantum numbers. In this paper we extend the class of calculable correlations by deriving factorization theorems for a broad class of correlations, $⟨{\mathcal{E}}_{R_1}(n_1)\cdots {\mathcal{E}}_{R_k}(n_k)⟩$, between the energy flux carried by hadrons specified by quantum numbers, $R_1,\cdots ,R_k$. We show that these factorization theorems involve moments of a new class of universal non-perturbative functions, the "joint track functions", which extend the track function formalism to describe the fraction of energy carried by hadrons of multiple quantum numbers arising from the fragmentation of quarks or gluons. We study the general properties of these functions, and then apply this to the specific case of joint track functions for positive and negative electromagnetic charges. We extract these from parton shower Monte Carlo programs and use them to calculate correlations in electromagnetically charged energy flux. We additionally propose and study a C-odd ${\mathcal{E}}_{\mathcal{Q}}$ detector, which results in a qualitatively distinct scaling behavior compared to the standard energy correlators. Our formalism significantly extends the class of observables that can be computed at hadron colliders, with a wide range of applications from particle to nuclear physics.

    hep-phhep-exnucl-exnucl-th35 citations
13. 13*

    Boosted dark matter from a phantom fluid

    James M. Cline🇨🇦 · Matteo Puel🇨🇦 · Takashi Toma🇯🇵

    It is known that theories of phantom dark energy, considered as quantum fields, predict a continuous production of positive- plus negative-energy particles, from spontaneous decay of the vacuum. We show that this can be a new source of boosted dark matter or radiation, with consequences for direct detection. We set constraints on such models using data from the XENONnT experiment, and we show that recent excess events reported by the DAMIC experiment can be consistently described as coming from dark radiation, produced by vacuum decay, interacting with electrons.

    hep-phastro-ph.COPLB(2024)·11 citations
14. 14*

    Signatures of Primordial Energy Injection from Axion Strings

    Joshua N. Benabou🇺🇸 · Malte Buschmann🇺🇸 · Soubhik Kumar🇺🇸 · Yujin Park🇺🇸 · Benjamin R. Safdi🇺🇸

    Axion strings are horizon-size topological defects that may be produced in the early Universe. Ultra-light axion-like particles may form strings that persist to temperatures below that of big bang nucleosynthesis. Such strings have been considered previously as sources of gravitational waves and cosmic microwave background (CMB) polarization rotation. In this work we show, through analytic arguments and dedicated adaptive mesh refinement cosmological simulations, that axion strings deposit a sub-dominant fraction of their energy into high-energy Standard Model (SM) final states, for example, by the direct production of heavy radial modes that subsequently decay to SM particles. This high-energy SM radiation is absorbed by the primordial plasma, leading to novel signatures in precision big bang nucleosynthesis, the CMB power spectrum, and gamma-ray surveys. In particular, we show that CMB power spectrum data constrains axion strings with decay constants $f_a\lesssim 10^{12}$ GeV, up to model dependence on the ultraviolet completion, for axion masses $m_a\lesssim 10^{-29}$ eV; future CMB surveys could find striking evidence of axion strings with lower decay constants.

    hep-phastro-ph.COastro-ph.HEhep-thPRD(2024)·31 citations
15. 15*

    Excited bound states and their role in dark matter production

    Tobias Binder🇩🇪 · Mathias Garny🇩🇪 · Jan Heisig🇩🇪 · Stefan Lederer🇩🇪 · Kai Urban🇩🇪

    We explore the impact of highly excited bound states on the evolution of number densities of new physics particles, specifically dark matter, in the early Universe. Focusing on dipole transitions within perturbative, unbroken gauge theories, we develop an efficient method for including around a million bound state formation and bound-to-bound transition processes. This enables us to examine partial-wave unitarity and accurately describe the freeze-out dynamics down to very low temperatures. In the non-Abelian case, we find that highly excited states can prevent the particles from freezing out, supporting a continuous depletion in the regime consistent with perturbativity and unitarity. We apply our formalism to a simplified dark matter model featuring a colored and electrically charged $t$-channel mediator. Our focus is on the regime of superWIMP production which is commonly characterized by a mediator freeze-out followed by its late decay into dark matter. In contrast, we find that excited states render mediator depletion efficient all the way until its decay, introducing a dependence of the dark matter density on the mediator lifetime as a novel feature. The impact of bound states on the viable dark matter mass can amount to an order of magnitude, relaxing constraints from Lyman-$\alpha$ observations.

    hep-phastro-ph.COPRD(2023)·33 citations
16. 16*

    ALP-LEFT Interference and the Muon $(g-2)$

    Anne Mareike Galda🇩🇪 · Matthias Neubert (Johannes Gutenberg University, Mainz)🇺🇸

    The low-energy effective field theory (LEFT) provides the appropriate framework to describe particle interactions below the scale of electroweak symmetry breaking, ${\mu }_w\sim v$. By matching the Standard Model onto the LEFT, non-zero Wilson coefficients of higher-dimensional operators are generated, suppressed by the corresponding power of $1/v$. An axion or axion-like particle (ALP) with mass $m_a\ll {\mu }_w$ that interacts with the Standard Model via classically shift-invariant dimension-five operators would also contribute to the LEFT Wilson coefficients, since it can appear as a virtual particle in divergent Green's functions and thus has an impact on the renormalization of the LEFT operators. We present the full set of one-loop ALP-induced source terms modifying the renormalization-group evolution equations of the LEFT Wilson coefficients up to dimension-six order. Our framework allows for model-independent ALP searches at low energies from current bounds on LEFT Wilson coefficients. As a concrete application, we present an improved prediction for ALP effects on the anomalous magnetic moment of the muon.

    hep-phJHEP(2023)·12 citations
17. 17*

    Wrinkles in the Froggatt-Nielsen Mechanism and Flavorful New Physics

    Pouya Asadi🇺🇸 · Arindam Bhattacharya🇺🇸 · Katherine Fraser🇺🇸 · Samuel Homiller🇺🇸 · Aditya Parikh🇺🇸

    When the Froggatt-Nielsen mechanism is used to explain the Standard Model flavor hierarchy, new physics couplings are also determined by the horizontal symmetry. However, additional symmetries or dynamics in the UV can sometimes lead to a departure from this naïve scaling for the new physics couplings. We show that an effective way to keep track of these changes is by using the new spurions of the $\mathrm{U}(3{)}^5$ global flavor symmetry, where we parameterize extra suppression or enhancement factors, referred to as wrinkles, using the same power counting parameter as in the original Froggatt-Nielsen model. As a concrete realization, we consider two flavor spurions of the $S_1$ leptoquark, and demonstrate that wrinkles can be used to make an enhanced value of $\text{BR}(B^{+}\to K^{+}\nu \bar{\nu })$ consistent with other flavor observables. We also present example UV models that realize wrinkles, and comment on choosing consistent charges in ordinary Froggatt-Nielsen models without the typical monotonicity condition.

    hep-phJHEP(2023)·28 citations
18. 18*

    Thermal effects in freeze-in neutrino dark matter production

    A. Abada🇫🇷 · G. Arcadi🇮🇹 · M. Lucente🇮🇹 · G. Piazza🇫🇷 · S. Rosauro-Alcaraz🇫🇷

    We present a detailed study of the production of dark matter in the form of a sterile neutrino via freeze-in from decays of heavy right-handed neutrinos. Our treatment accounts for thermal effects in the effective couplings, generated via neutrino mixing, of the new heavy neutrinos with the Standard Model gauge and Higgs bosons and can be applied to several low-energy fermion seesaw scenarios featuring heavy neutrinos in thermal equilibrium with the primordial plasma. We find that the production of dark matter is not as suppressed as to what is found when considering only Standard Model gauge interactions. Our study shows that the freeze-in dark matter production could be efficient.

    hep-phJHEP(2023)·13 citations
19. 19*

    Revisiting semileptonic $B$ meson decays at next-to-next-to-leading order

    Manuel Egner🇩🇪 · Matteo Fael🇨🇭 · Kay Schönwald🇨🇭 · Matthias Steinhauser🇩🇪

    We compute next-to-next-to-leading order corrections to the semileptonic decay rate of $B$ mesons for arbitrary values of the final-state quark mass. For the contribution with one massive quark in the final state, we extend the literature result and obtain analytic expressions in terms of iterated integrals. For the complete contribution, which also includes contributions with three massive quarks in the final state, we present a semi-analytic method, which leads to a precise approximation formula for the decay rate. Our results agree with the expansions available for $b\to c\ell {\bar{\nu }}_{\ell }$ and $b\to u\ell {\bar{\nu }}_{\ell }$ in the literature. The main emphasize of this paper is on the technical aspects of the calculation which are useful for a wider range of applications.

    hep-phJHEP(2023)·18 citations
20. 20*

    Ultraviolet Running Constraints on Low Mass Dark Sectors

    Aidan Reilly🇺🇸 · Natalia Toro🇺🇸

    We analyze the UV breakdown of Sub-GeV dark matter models that live in a new, dark U(1) sector. Many of these models include a scalar field, which is either the dark matter itself or a dark Higgs field that generates mass terms for the dark matter particle via spontaneous symmetry breaking. A quartic self coupling of this scalar field is generically allowed, and we show that its running is largely governed by the strength of the U(1) gauge field, ${\alpha }_D$. Furthermore, it consistently has a lower Landau pole than the gauge coupling. Link fields, which couple to both the dark sector and the Standard Model (SM), connect these Landau poles to constraints on SM charged particles. Current LHC constraints on link fields are compatible with ${\alpha }_D\lesssim 0.5-1$ for most of the mass range in most models, while smaller values, ${\alpha }_D\lesssim 0.15$, are favored for Majorana DM.

    hep-phJHEP(2024)·10 citations
21. 21*

    Revisiting signatures of thermal axions in nonstandard cosmologies

    Paola Arias🇨🇱 · Nicolás Bernal🇦🇪 · Jacek K. Osiński🇵🇱 · Leszek Roszkowski🇵🇱 · Moira Venegas🇨🇱

    We revisit the formation of a thermal population of hadronic axions in nonstandard cosmologies, in light of the recent developments in obtaining continuous and smooth interaction rates for both the gluon and photon couplings. For certain cosmological histories, such as low-temperature reheating (LTR) and kination-like scenarios, the thermalization of the axion can be severely delayed to higher masses. In the case that thermal equilibrium is achieved, we improve the constraints on LTR for axion masses around the eV scale with respect to previous works and we constrain for the first time early matter-dominated (EMD) cosmologies. We also point out the possibility of having the co-existence of cold and warm dark matter populations of axions in kination-like scenarios in the eV mass range.

    hep-phastro-ph.COPRD(2024)·21 citations
22. 22*

    Reconstructing axion-like particles from beam dumps with simulation-based inference

    Alessandro Morandini🇩🇪 · Torben Ferber🇩🇪 · Felix Kahlhoefer🇩🇪

    Axion-like particles (ALPs) that decay into photon pairs pose a challenge for experiments that rely on the construction of a decay vertex in order to search for long-lived particles. This is particularly true for beam-dump experiments, where the distance between the unknown decay position and the calorimeter can be very large. In this work we use machine learning to explore the possibility to reconstruct the ALP properties, in particular its mass and lifetime, from such inaccurate observations. We use a simulation-based inference approach based on conditional invertible neural networks to reconstruct the posterior probability of the ALP parameters for a given set of events. We find that for realistic angular and energy resolution, such a neural network significantly outperforms parameter reconstruction from conventional high-level variables while at the same time providing reliable uncertainty estimates. Moreover, the neural network can quickly be re-trained for different detector properties, making it an ideal framework for optimizing experimental design.

    hep-phhep-exEPJC(2024)·8 citations
23. 23*

    Next-to-leading order electroweak corrections to $gg\to HH$ and $gg\to gH$ in the large-$m_t$ limit

    Joshua Davies🇬🇧 · Kay Schönwald🇨🇭 · Matthias Steinhauser🇩🇪 · Hantian Zhang🇩🇪

    We compute two-loop electroweak corrections to Higgs boson pair and Higgs plus jet production, taking into account all sectors of the Standard Model. All diagrams with virtual top quarks are computed in an expansion for large top quark mass up to order $1/m_t^8$ or more. We present analytic results for the form factors and discuss the convergence properties. For the process $gg\to gH$ we also consider QCD corrections in the large-$m_t$ limit.

    hep-phJHEP(2023)·57 citations
24. 24*

    Muon spin force

    Yohei Ema🇺🇸 · Ting Gao🇺🇸 · Maxim Pospelov🇺🇸

    Current discrepancy between the measurement and the prediction of the muon anomalous magnetic moment can be resolved in the presence of a long-range force created by ordinary atoms acting on the muon spin via axial-vector and/or pseudoscalar coupling, and requiring a tiny, $\mathcal{O}(10^{-13}\mathrm{eV})$ spin energy splitting between muon state polarized in the vertical direction. We suggest that an extension of the muon spin resonance ($\mu$SR) experiments can provide a definitive test of this class of models. We also derive indirect constraints on the strength of the muon spin force, by considering the muon-loop-induced interactions between nuclear spin and external directions. The limits on the muon spin force extracted from the comparison of ${}^{199}$Hg/${}^{201}$Hg and ${}^{129}$Xe/${}^{131}$Xe spin precession are strong for the pseudoscalar coupling, but are significantly relaxed for the axial-vector one. These limits suffer from significant model uncertainties, poorly known proton/neutron spin content of these nuclei, and therefore do not exclude the possibility of a muon spin force relevant for the muon $g-2$.

    hep-phhep-exnucl-thPRD(2024)·7 citations
25. 25*

    Tunnelling-induced cosmic bounce in the presence of anisotropies

    Jean Alexandre🇬🇧 · Katy Clough🇬🇧 · Silvia Pla🇬🇧

    If we imagine rewinding the universe to early times, the scale factor shrinks and the existence of a finite spatial volume may play a role in quantum tunnelling effects in a closed universe. It has recently been shown that such finite volume effects dynamically generate an effective equation of state that could support a cosmological bounce. In this work we extend the analysis to the case in which a (homogeneous) anisotropy is present, and identify a criteria for a successful bounce in terms of the size of the closed universe and the properties of the quantum field.

    ↳ gr-qchep-phhep-thPRD(2023)·5 citations
26. 26*

    Observable Primordial Gravitational Waves from Cosmic Inflation

    Konstantinos Dimopoulos🇬🇧

    I will review briefly how inflation is expected to generate a stochastic background of primordial gravitational waves (GWs). Then, I will discuss how such GWs can be enhanced by a stiff period following inflation, enough to be observable. I will present examples of this in the context of hybrid inflation with $\alpha$-attractors, or a period of hyperkination in Palatini gravity.

    ↳ gr-qcastro-ph.COhep-phhep-th1 citation
27. 27*

    Higgs vacuum metastability in $R+R^2$ gravity

    Andreas Mantziris🇬🇧

    Experimental data suggest that the Higgs potential has a lower ground state at high field values. Consequently, decaying from the electroweak to the true vacuum nucleates bubbles that expand rapidly and can have dire consequences for our Universe. This overview of our last study [1] regarding the cosmological implications of vacuum metastability during Starobinsky inflation was presented at the HEP2023 conference. Following the framework established in [2], we showcased our state-of-the-art lower bounds on the non-minimal coupling $\xi$, which resulted from a dedicated treatment of the effective Higgs potential in $R+R^2$ gravity. The effects of this consideration involved the generation of destabilising terms in the potential and the sensitive dependence of bubble nucleation on the last moments of inflation. In this regime, spacetime deviates increasingly from de Sitter and thus the validity of our approach reaches its limit, but at earlier times, we recover our result hinting against eternal inflation.

    ↳ astro-ph.COgr-qchep-phhep-th2 citations
28. 28*

    Open heavy flavors: Theory

    Santosh K. Das🇮🇳

    A brief overview of the theory of open heavy flavor dynamics in QCD matter produced in high energy heavy-ion collisions is presented. First, we will summarise the phenomenological efforts to estimate the heavy quark diffusion coefficients obtained within different models. Then, the recent theoretical developments from different groups to probe the medium properties using heavy quarks will be presented. Heavy quarks are also considered as an ideal probe for the initial stage of heavy-ion collisions. In the end, we present the recent theoretical progress made to probe the early-stage effects, pre-equilibrium phase, and electromagnetic fields.

    ↳ nucl-thhep-exhep-phPoS(2024)·3 citations
29. 29*

    Quantum Imprint of the Anharmonic Oscillator

    Prisco Lo Chiatto🇩🇪 · Sebastian Schenk🇩🇪 · Felix Yu🇩🇪

    We study the anharmonic double well in quantum mechanics using exact Wentzel-Kramers-Brillouin (WKB) methods in a 't Hooft-like double scaling limit where classical behavior is expected to dominate. We compute the tunneling action in this double scaling limit, and compare it to the transition amplitude from the vacuum to a highly excited state. Our results, exact in the semiclassical limit, show that the two expressions coincide, apart from an irreducible and surprising instanton contribution. Thus, the semiclassical limit of the anharmonic oscillator betrays its quantum origin as a rule, which we dub the "quantum imprint rule," showing that the quantum theory is intrinsically gapped from classical behavior. Besides an example of the failure of reductionism and an example of a resurgent connection between perturbative and nonperturbative physics, this work provides a possible classification of theories according to their quantum imprints.

    ↳ hep-thhep-phquant-ph5 citations
30. 30*

    Sphaleron rate of $N_f=2+1$ QCD

    Claudio Bonanno🇪🇸 · Francesco D'Angelo🇮🇹 · Massimo D'Elia🇮🇹 · Lorenzo Maio🇮🇹 · Manuel Naviglio🇮🇹

    We compute the sphaleron rate of $N_f=2+1$ QCD at the physical point for a range of temperatures $200$ MeV $\lesssim T\lesssim 600$ MeV. We adopt a strategy recently applied in the quenched case, based on the extraction of the rate via a modified version of the Backus-Gilbert method from finite-lattice-spacing and finite-smoothing-radius Euclidean topological charge density correlators. The physical sphaleron rate is finally computed by performing a continuum limit at fixed physical smoothing radius, followed by a zero-smoothing extrapolation. Dynamical fermions were discretized using the staggered formulation, which is known to yield large lattice artifacts for the topological susceptibility. However, we find them to be rather mild for the sphaleron rate.

    ↳ hep-lathep-phPRL(2024)·45 citations
31. 31*

    The chiral condensate of $N_f=2+1$ QCD from the spectrum of the staggered Dirac operator

    Claudio Bonanno🇪🇸 · Francesco D'Angelo🇮🇹 · Massimo D'Elia🇮🇹

    We compute the chiral condensate of $2+1$ QCD from the mode number of the staggered Dirac operator, performing controlled extrapolations to both the continuum and the chiral limit. We consider also alternative strategies, based on the quark mass dependence of the topological susceptibility and of the pion mass, and obtain consistent results within errors. Results are also consistent with phenomenological expectations and with previous numerical determinations obtained with different lattice discretizations.

    ↳ hep-lathep-phJHEP(2023)·14 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.