Thu·Nov 16, 2023Thursday·November 16, 2023

1. 01*

   Emission of twisted photons by a Dirac electron in a strong magnetic field

   I. Pavlov🇷🇺 · D. Karlovets🇷🇺

   We study spontaneous emission of a photon during the transitions between relativistic Landau states of an electron in a constant magnetic field that can reach the Schwinger value of $H_c=4.4\times 10^9$ T. In contrast to the conventional method in which detection of both the final electron and the photon is implied in a certain basis, here we derive the photon state as it evolves from the process itself. It is shown that the emitted photon state represents a twisted Bessel beam propagating along the field axis with a total angular momentum (TAM) projection onto this axis $\ell -{\ell }^{\prime }$ where $\ell$ and ${\ell }^{\prime }$ are the TAM of the initial electron and of the final one, respectively. Thus, the majority of the emitted photons turn out to be twisted with $\ell -{\ell }^{\prime }\gtrsim 1$, even when the magnetic field reaches the critical value of $H\sim H_c$. The transitions without a change of the electron angular momentum, ${\ell }^{\prime }=\ell$, are possible, yet much less probable. We also compare our findings with those for a spinless charged particle and demonstrate their good agreement for the transitions without change of the electron spin projection even in the critical fields, while the spin-flip transitions are generally suppressed. In addition, we argue that whereas the ambiguous choice of an electron spin operator affects the differential probability of emission, this problem can partially be circumvented for the photon evolved state because it is the electron TAM rather than the spin alone that defines the TAM of the emitted twisted photon.

   hep-phquant-phPRD(2024)·5 citations
2. 02*

   Pion distribution functions from low-order Mellin moments

   Ya Lu🇨🇳 · Yin-Zhen Xu🇪🇸 · Khépani Raya🇪🇸 · Craig D. Roberts🇨🇳 · José Rodríguez-Quintero🇪🇸

   Exploiting an evolution scheme for parton distribution functions (DFs) that is all-orders exact, contemporary lattice-QCD (lQCD) results for low-order Mellin moments of the pion valence quark DF are shown to be mutually consistent. The analysis introduces a means by which key odd moments can be obtained from the even moments in circumstances where only the latter are available. Combining these elements, one arrives at parameter-free lQCD-based predictions for the pointwise behaviour of pion valence, glue, and sea DFs, with sound uncertainty estimates. The behaviour of the pion DFs at large light-front momentum fraction, $x>0.85$, is found to be consistent with QCD expectations and continuum analyses of pion structure functions, i.e., damping like $(1-x{)}^{{\beta }_{\mathrm{parton}}}$, with ${\beta }_{\mathrm{valence}}\approx 2.4$, ${\beta }_{\mathrm{glue}}\approx 3.6$, ${\beta }_{\mathrm{sea}}\approx 4.6$. It may be possible to test these predictions using data from forthcoming experiments.

   hep-phhep-exhep-latnucl-ex+1PLB(2024)·35 citations
3. 03*

   The Cosmology of Dark Energy Radiation

   Kim V. Berghaus🇺🇸 · Tanvi Karwal🇺🇸 · Vivian Miranda🇺🇸 · Thejs Brinckmann🇮🇹

   In this work, we quantify the cosmological signatures of dark energy radiation -- a novel description of dark energy, which proposes that the dynamical component of dark energy is comprised of a thermal bath of relativistic particles sourced by thermal friction from a slowly rolling scalar field. For a minimal model with particle production emerging from first principles, we find that the abundance of radiation sourced by dark energy can be as large as ${\Omega }_{\text{DER}}=0.03$, exceeding the bounds on relic dark radiation by three orders of magnitude. Although the background and perturbative evolution of dark energy radiation is distinct from Quintessence, we find that current and near-future cosmic microwave background and supernova data will not distinguish these models of dark energy. We also find that our constraints on all models are dominated by their impact on the expansion rate of the Universe. Considering extensions that allow the dark radiation to populate neutrinos, axions, and dark photons, we evaluate the direct detection prospects of a thermal background comprised of these candidates consistent with cosmological constraints on dark energy radiation. Our study indicates that a resolution of $\sim 6\text{meV}$ is required to achieve sensitivity to relativistic neutrinos compatible with dark energy radiation in a neutrino capture experiment on tritium. We also find that dark matter axion experiments lack sensitivity to a relativistic thermal axion background, even if enhanced by dark energy radiation, and dedicated search strategies are required to probe new parameter space. We derive constraints arising from a dark photon background from oscillations into visible photons, and find that viable parameter space can be explored with the LAte Dark Energy RAdiation (LADERA) experiment.

   hep-phastro-ph.COPRD(2024)·11 citations
4. 04*

   A guide to the QCD light-cone sum rule for $b$-quark decays

   Alexander Khodjamirian🇩🇪 · Blaženka Melić🇭🇷 · Yu-Ming Wang🇨🇳

   We overview the current status and future perspectives of the QCD-based method of light-cone sum rules. The two main versions of these sum rules, using light-meson and $B$-meson distribution amplitudes are introduced and the most important applications of the method are discussed. We also outline open problems and future perspectives of this method.

   hep-phhep-exhep-latEur.Phys.J.ST(2024)·45 citations
5. 05*

   Analysis of HERA data with a PDF parametrization inspired by quantum statistical mechanics

   Marco Bonvini🇮🇹 · Franco Buccella🇮🇹 · Francesco Giuli🇨🇭 · Federico Silvetti🇬🇧

   We present a determination of the parton distribution functions (PDFs) of the proton from HERA data using a PDF parametrization inspired by a quantum statistical model of the proton dynamics. This parametrization is characterised by a very small number of parameters, yet it leads to a reasonably good description of the data, comparable with other parametrizations on the market. It may thus provide an alternative to standard parametrizations, useful for studying parametrization bias and to possibly simplify the fit procedure thanks to the small number of parameters. Interestingly, the model reproduces key physical features, such as a $\bar{d}$ distribution larger than $\bar{u}$, that HERA data alone are not able to constrain when using more flexible parametrizations. Moreover, polarized distributions are described in the model by the same parameters of the unpolarized ones, giving us the possibility of extracting both types of distributions within the same fit.

   hep-phEPJC(2024)·4 citations
6. 06*

   Unraveling Proton Strangeness: Determination of the Strangeness Sigma Term with Statistical Significance

   Wei Kou🇨🇳 · Xurong Chen🇨🇳

   This study delves into the contribution of the strange quark within the proton, which influences several fundamental proton properties. By establishing a robust relationship between the proton's quantum anomalous energy and the sigma term, we successfully extract the contribution of the strangeness sigma term in the proton, obtaining it from parameterized fits of the differential cross-section using exponential and dipole forms. The extracted sigma term values are estimated to be $455.62\pm 64.60$ MeV (exponential fit) and $337.74\pm 106.79$ MeV (dipole fit). Additionally, we present novel results for the proton trace anomalous energy, observing values of $0.13\pm 0.02$ (exponential fit) and $0.15\pm 0.03$ (dipole fit). Our analysis integrates the novel data from the $J/\psi -007$ and GlueX collaborations, to some extent providing an experimental phenomenological window into the non-zero strange quark content inside proton, with the statistical significances: $7.1\sigma$ (exponential fit) and $3.2\sigma$ (dipole fit), respectively. Furthermore, we discussed the possibility of scheme-independence in the extraction results and examine the uniformity of sigma terms obtained from the datasets provided by the two collaborations. Our analysis may reveals compatibility between the extracted results of the respective experiments.

   hep-phPRD(2024)·3 citations
7. 07*

   Status of the superweak extension of the standard model and muon g-2

   Zoltan Trocsanyi🇭🇺

   The super-weak force is a minimal, anomaly-free U(1) extension of the standard model, designed to explain the origin of (i) neutrino masses and mixing matrix elements, (ii) dark matter, (iii) cosmic inflation, (iv) stabilization of the electroweak vacuum and (v) leptogenesis. In this talk we discuss the phenomenological status of the model and provide viable scenarios for the physics of the items in this list.

   hep-phActa Phys.Polon.Supp.(2024)·3 citations
8. 08*

   Dark energy with the help of interacting dark sectors

   Joaquim M. Gomes🇬🇧 · Edward Hardy🇬🇧 · Susha Parameswaran🇬🇧

   We analyse theories that do not have a de Sitter vacuum and cannot lead to slow-roll quintessence, but which nevertheless support a transient era of accelerated cosmological expansion due to interactions between a scalar $\varphi$ and either a hidden sector thermal bath, which evolves as Dark Radiation, or an extremely-light component of Dark Matter. We show that simple models can explain the present-day Dark Energy of the Universe consistently with current observations. This is possible both when $\varphi$'s potential has a hilltop form and when it has a steep exponential run-away, as might naturally arise from string theory. We also discuss a related theory of multi-field quintessence, in which $\varphi$ is coupled to a sector that sources a subdominant component of Dark Energy, which overcomes many of the challenges of slow-roll quintessence.

   hep-phastro-ph.COhep-thPRD(2024)·14 citations
9. 09*

   Neutrino Mass Model and Dark Matter with $Y=0$ Inert Triplet Scalar

   Shilpa Jangid🇰🇷 · Keiko I. Nagao🇯🇵 · Hiroshi Okada🇯🇵

   We study a one-loop induced neutrino mass model with an inert isospin triplet scalar field of $Y=0$ and heavier isospin doublet vector-like leptons and singlet Majorana right-handed fermions. In addition to the neutrino mass matrix, We explain sizable scale of muon anomalous magnetic dipole moment $10^{-9}$ by introducing a singly-charged boson $S^{\pm }$. We show numerical analysis of neutrino oscillation, lepton flavor violations, Z boson decays, and demonstrate our allowed regions in cases of normal and inverted hierarchies. We find the sizable scale of muon anomalous magnetic dipole moment for both cases. Then, we move on to the discussion of dark matter candidates to satisfy the relic density where we have two candidates; fermionic dark matter and bosonic one. And, we classify four cases fermionic dark matter with normal and inverted hierarchies, bosonic one with normal and inverted hierarchies and search for each of the allowed points in the model.

   hep-phPLB(2024)·0 citations
10. 10*

    Leptogenesis driven by majoron

    Eung Jin Chun🇰🇷 · Tae Hyun Jung🇰🇷

    We propose a leptogenesis scenario where baryon asymmetry generation is assisted by the kinetic motion of the majoron, $J$, in the process of lepton-number violating inverse decays of a right-handed neutrino, $N$. We investigate two distinct scenarios depending on the sources of majoron kinetic motion: 1) the misalignment mechanism, and 2) the kinetic misalignment mechanism. The former case can naturally generate the observed baryon asymmetry for the majoron mass $m_J\gtrsim \mathrm{TeV}$ and the right-handed neutrino's mass $M_N\gtrsim 10^{11}\mathrm{GeV}$. However, an additional decay channel of the majoron is required to avoid the overclosure problem of the majoron oscillation. The later scenario works successfully for $m_J\lesssim 100\mathrm{keV}$, and $M_N\lesssim 10^9\mathrm{GeV}$ while $M_N$ can be even far below the temperature of the electroweak phase transition as long as sufficiently large kinetic misalignment is provided. We also find that a sub-$100\mathrm{keV}$ majoron is a viable candidate for dark matter.

    hep-phPRD(2024)·32 citations
11. 11*

    Estimation of the chances to find new phenomena at the LHC in a model-agnostic combinatorial analysis

    S. V. Chekanov🇺🇸

    In this paper, we estimate the number of event topologies that have the potential to be produced in $pp$ collisions at the Large Hadron Collider (LHC) without violating kinematic and other constraints. We use numerical calculations and combinatorics, guided by large-scale Monte Carlo simulations of Standard Model (SM) processes. Then, we set the upper limit on the probability that new physics may escape detection, assuming a model-agnostic approach. The calculated probability is unexpectedly large, and the fact that the LHC has not found new physics until now is not entirely surprising. We argue that the optimal direction for maximizing the chances of finding new physics is to use unsupervised machine learning for anomaly detection or algorithms designed for event classification.

    hep-phUniverse(2024)·7 citations
12. 12*

    Decoding Fermion Mass Pattern from Mass Hierarchy

    Ying Zhang🇨🇳

    Building an organized Yukawa structure of quarks and leptons is an essential mission to understand fermion mass hierarchy and flavor mixing in particle physics. Inspired by the similarity of CKM and PMNS mixings, a common mass pattern for up-type and down-type quarks, charged leptons, and Dirac neutrinos is realized in terms of hierarchal masses. An organized structure of Yukawa couplings can be expressed on a Yukawa basis. The CKM mixing and PMNS mixing have the same mathematical forms due to $SO(2)$ family symmetry. By fitting the CKM/PMNS mixing experiment, the flat pattern becomes a successful flavor structure. The fundamental fermions can be explained by a new picture to show the relationship between gauge structure and flavor structure.

    hep-phEPL(2024)·1 citation
13. 13*

    Breakdown of collinear factorization in the exclusive photoproduction of a ${\pi }^0\gamma$ pair with large invariant mass

    Saad Nabeebaccus🇫🇷 · Jakob Schoenleber🇩🇪 · Lech Szymanowski🇵🇱 · Samuel Wallon🇫🇷

    We study the exclusive photoproduction of a ${\pi }^0\gamma$ pair with large invariant mass $M_{\gamma \pi }^2$, which is sensitive to the exchange of either two quarks or two gluons in the $t$-channel. In this paper, we show that the process involving two-gluon exchanges does not factorize in the Bjorken limit at the leading twist. This can be explicitly demonstrated by the fact that there exist diagrams, which contribute at the leading twist, for which Glauber gluons are trapped, due to the pinching of the contour integration of both the plus and minus component of the Glauber gluon momentum. For the same reason, ${\pi }^0$-nucleon scattering to two photons also suffers from the same issue. On the other hand, we stress that there are no issues with respect to collinear factorization for the quark channels. By considering an analysis of all potential reduced diagrams of leading pinch-singular surfaces, we argue that the quark channel is safe from Glauber pinches, and therefore, a collinear factorization in that case follows through without any problems. This means that processes where gluon exchanges are forbidden, such as the exclusive photoproduction of ${\pi }^{\pm }\gamma$ and ${\rho }^{0,\pm }\gamma$, are unaffected by the factorization breaking effects we point out in this paper.

    hep-phnucl-thPRD(2025)·24 citations
14. 14*

    Exclusive diffractive J/psi and Psi(2S) production in dipole model using a holographic AdS/QCD light front wavefunction with longitudinal confinement

    Neetika Sharma🇮🇳

    We use an anti-de Sitter/Quantum Chromodynamics (AdS/QCD) based holographic light-front wavefunction (LFWF) for vector meson, in conjunction with the dipole model to investigate the cross-sections data for the diffractive and exclusive J/psi and Psi(2S) production. We confront the experimental data using a new explicit form of the holographic LFWF, where the longitudinal confinement dynamics in light-front Schrodinger equation is captured by 't Hooft equation of (1+1)-dim, in large Nc approximation, in addition to the transverse confinement dynamics governed by the confining mass scale parameter, kappa in vector mesons. We obtain the LFWF parameters from fitting to the exclusive J/psi electro production data from electron-proton collision at HERA collider for m_c = 1.27 GeV. Our results suggest that the dipole model together with holographic meson LFWFs with longitudinal confinement is able to give a successful description for differential scattering cross-section for exclusive J/psi electro production for H1 and ZEUS data. We also predict the rapidity distributions of differential scattering cross-section and total photo production of J/psi and Psi(2S) states in proton-proton ultra-peripheral collisions(UPCs) at center of mass energy sqrt s = 7, 13 TeV. Using the minimum set of parameters, our predictions for the UPCs are in good agreement with the recent experimental observations of UPCs at ALICE and LHCb Collaborations.

    hep-phPRD(2024)·5 citations
15. 15*

    Optimizing Fictitious States for Bell Inequality Violation in Bipartite Qubit Systems

    Kun Cheng🇨🇳 · Tao Han🇺🇸 · Matthew Low🇺🇸

    There is a significant interest in testing quantum entanglement and Bell inequality violation in high-energy experiments. Since the analyses in high-energy experiments are performed with events statistically averaged over phase space, the states used to determine observables depend on the choice of coordinates through an event-dependent basis and are thus not genuine quantum states, but rather "fictitious states." We prove that if Bell inequality violation is observed with a fictitious state, then it implies the same for a quantum sub-state. We further show analytically that the basis which diagonalizes the spin-spin correlations is optimal for constructing fictitious states, and for maximizing the violation of Bell's inequality.

    hep-phquant-phPRD(2024)·64 citations
16. 16*

    Neutrino Mass and Mixing with Modular Symmetry

    Gui-Jun Ding🇨🇳 · Stephen F. King🇬🇧

    This is a review article about neutrino mass and mixing and flavour model building strategies based on modular symmetry. After an introduction to neutrino mass and lepton mixing, we then turn to the main subject of this review, namely a pedagogical introduction to modular symmetry as a candidate for family symmetry, from the bottom-up point of view. After an informal introduction to modular symmetry, we introduce the modular group, and discuss its fixed points and residual symmetry, assuming supersymmetry throughout. We then introduce finite modular groups of level $N$ and modular forms with integer or rational modular weights, corresponding to simple geometric groups or their double or metaplectic covers, including the most general finite modular groups and vector-valued modular forms, with detailed results for $N=2,3,4,5$. The interplay between modular symmetry and generalized CP symmetry is discussed, deriving CP transformations on matter multiplets and modular forms, highlighting the CP fixed points and their implications. In general, compactification of extra dimensions generally leads to a number of moduli, and modular invariance with factorizable and non-factorizable multiple moduli based on symplectic modular invariance and automorphic forms is reviewed. Modular strategies for understanding fermion mass hierarchies are discussed, including the weighton mechanism, small deviations from fixed points, and texture zeroes. Then examples of modular models are discussed based on single modulus $A_4$ models, a minimal $S_4^{\prime }$ model of leptons (and quarks), and a multiple moduli model based on three $S_4$ groups capable of reproducing the Littlest Seesaw model. We then extend the discussion to include Grand Unified Theories (GUTs) based on modular (flipped) $SU(5)$ and $SO(10)$. Finally we discuss top-down approaches, including eclectic flavour symmetry and moduli stabilisation.

    hep-phRept.Prog.Phys.(2024)·142 citations
17. 17*

    Extremal Higgs couplings

    Joan Elias Miro🇮🇹 · Andrea Guerrieri🇮🇹 · Mehmet Asim Gumus🇮🇹

    We critically assess to what extent it makes sense to bound the Wilson coefficients of dimension-six operators. In the context of Higgs physics, we establish that a closely related observable, $c_H$, is well-defined and satisfies a two-sided bound. $c_H$ is derived from the low momentum expansion of the scattering amplitude, or the derivative of the amplitude at the origin with respect to the Mandelstam variable $s$, expressed as $M(H_i{H}_i\to H_j{H}_j)=c_{H}s+O(g_{\text{SM}},s^{-2})$ where $g_{\text{SM}}$ represents all Standard Model couplings. This observable is non-dispersive and, as a result, not sign-definite. We also determine the conditions under which the bound on $c_H$ is equivalent to a bound on the dimension-six operator $O_H=\partial |H{|}^2\partial |H{|}^2$.

    hep-phhep-thPRD(2024)·32 citations
18. 18*

    Instanton NDA and Applications to Axion Models

    Csaba Csáki🇺🇸 · Raffaele Tito D'Agnolo🇫🇷 · Eric Kuflik🇮🇱 · Maximilian Ruhdorfer🇺🇸

    We present a simple set of power counting rules which allows us to easily estimate calculable instanton effects up to $O(1)$ factors. We apply the resulting Instanton NDA to examine the effects of small instantons on various axion models. We confirm that mechanisms that increase the axion mass via small instantons generically also lead to an enhancement of misaligned instanton contributions to the axion potential, deepening the axion quality problem. For generic models, new sources of CP violation in the UV must be absent in order to raise the axion mass above the QCD prediction. However, we find that $Z_N$ and composite axions are UV-safe against these misalignment effects. Axion GUT models are also insensitive to UV contributions at the GUT scale, unless a very large number of extra states are introduced below this scale.

    hep-phhep-thJHEP(2024)·29 citations
19. 19*

    U(2) is Right for Leptons and Left for Quarks

    Stefan Antusch🇨🇭 · Admir Greljo🇨🇭 · Ben A. Stefanek🇬🇧 · Anders Eller Thomsen🇨🇭

    We posit that the distinct patterns observed in fermion masses and mixings are due to a minimally broken $\mathrm{U}(2{)}_{q+e}$ flavor symmetry acting on left-handed quarks and right-handed charged leptons, giving rise to an accidental $\mathrm{U}(2{)}^5$ symmetry at the renormalizable level without imposing selection rules on the Weinberg operator. We show that the symmetry can be consistently gauged by explicit examples and comment on realizations in $\mathrm{SU}(5)$ unification. Via a model-independent SMEFT analysis, we find that selection rules due to $\mathrm{U}(2{)}_{q+e}$ enhance the importance of charged lepton flavor violation as a probe, where significant experimental progress is expected in the near future.

    hep-phhep-exPRL(2024)·25 citations
20. 20*

    Towards a data-driven model of hadronization using normalizing flows

    Christian Bierlich🇸🇪 · Phil Ilten🇺🇸 · Tony Menzo🇺🇸 · Stephen Mrenna🇺🇸 · Manuel Szewc🇺🇸 · Michael K. Wilkinson🇺🇸 · Ahmed Youssef🇺🇸 · Jure Zupan🇺🇸

    We introduce a model of hadronization based on invertible neural networks that faithfully reproduces a simplified version of the Lund string model for meson hadronization. Additionally, we introduce a new training method for normalizing flows, termed MAGIC, that improves the agreement between simulated and experimental distributions of high-level (macroscopic) observables by adjusting single-emission (microscopic) dynamics. Our results constitute an important step toward realizing a machine-learning based model of hadronization that utilizes experimental data during training. Finally, we demonstrate how a Bayesian extension to this normalizing-flow architecture can be used to provide analysis of statistical and modeling uncertainties on the generated observable distributions.

    hep-phhep-exSciPost Phys.(2024)·36 citations
21. 21*

    Bounds on Quartic Gauge Couplings in HEFT from Electroweak Gauge Boson Pair Production at the LHC

    O. J. P. Eboli🇧🇷 · M. C. Gonzalez-Garcia🇺🇸 · Matheus Martines🇧🇷

    Precision measurements of anomalous quartic couplings of electroweak gauge bosons allow us to search for deviations of the Standard Model predictions and signals of new physics. Here, we obtain the constraints on anomalous quartic gauge couplings using the presently available data on the production of gauge-boson pairs via vector boson fusion. We work in the Higgs effective theory framework and obtain the present bounds on the operator's Wilson coefficients. Anomalous quartic gauge boson couplings lead to rapidly growing cross sections and we discuss the impact of a unitarization procedure on the attainable limits.

    hep-phPRD(2024)·7 citations
22. 22*

    Mesonic decay constant and mass ratios and the conformal window

    Hee Sok Chung🇰🇷 · Daniel Nogradi🇭🇺

    Two particular ratios related to mesons are proposed for the study of the conformal window in $SU(3)$ gauge theory and fundamental fermions. Lattice and other studies indicate that the lower end, $N_f^{\ast }$, is at around 7 - 13 flavors which is a wide range without a clear consensus. Here we propose the decay constant to mass ratios of mesons, $f_{PS,V}/m_V$, as a proxy since below the conformal window lattice studies have shown that they are largely $N_f$-independent while at the upper end of the conformal window they are vanishing. The drop from the non-zero constant value to zero at $N_f=16.5$ might be indicative of $N_f^{\ast }$. We compute $f_V/m_V$ to N${}^3$LO and $f_{PS}/m_V$ to NNLO order in (p)NRQCD. The results are unambiguously reliable just below $N_f=16.5$, hence the results are expanded á la Banks-Zaks in $\epsilon =16.5-N_f$. The convergence properties of the series and matching with the non-perturbative infinite volume, continuum and chiral extrapolated lattice results at $N_f=10$ suggest that the perturbative results might be reliable down to $N_f=12$. A sudden drop is observed at $N_f=12$ and $N_f=13$ in $f_V/m_V$ and $f_{PS}/m_V$, respectively.

    ↳ hep-lathep-phPoS(2024)·3 citations
23. 23*

    Post-inflationary structure formation boosted by parametric self-resonance

    Benedikt Eggemeier🇩🇪 · Peter Hayman🇳🇿 · Jens C. Niemeyer🇩🇪 · Richard Easther🇳🇿

    The post-inflationary Universe can pass through a long epoch of effective matter-dominated expansion. This era may allow for both the parametric amplification of initial fluctuations and the gravitational collapse of inflaton perturbations. We perform first-of-their-kind high-resolution simulations that span the resonant phase and the subsequent gravitational collapse of the inflaton field by seguing from a full Klein-Gordon treatment of resonance to a computationally efficient Schrödinger-Poisson description that accurately captures the gravitational dynamics when most quanta are nonrelativistic. We consider a representative example in which resonance generates $\mathcal{O}(10^{-1})$ overdensities and gravitational collapse follows promptly as resonance ends. We observe the formation of solitonic cores inside inflaton halos and complex gravitational dynamics on scales of $10^{-27}\mathrm{m}$, greatly extending the possible scope of nonlinear post-inflationary gravitational dynamics.

    ↳ astro-ph.COhep-phPRD(2024)·8 citations
24. 24*

    Constraints on Density Dependent MIT Bag Model Parameters for Quark and Hybrid Stars

    Soumen Podder🇮🇳 · Suman Pal🇮🇳 · Debashree Sen🇰🇷 · Gargi Chaudhuri🇮🇳

    We compute the equation of state (EoS) of strange quark stars (SQSs) with the MIT Bag model using density dependent bag pressure, characterized by a Gaussian distribution function. The bag pressure's density dependence is controlled by three key parameters namely the asymptotic value ($B_{as}$), $\Delta B(=B_0-B_{as})$, and $\beta$. We explore various parameter combinations ($B_{as}$, $\Delta B$, $\beta$) that adhere to the Bodmer-Witten conjecture, a criterion for the stability of SQSs. Our primary aim is to analyze the effects of these parameter variations on the structural properties of SQSs. However we find that none of the combinations can satisfy the NICER data for PSR J0030+0451 and the constraint on tidal deformability from GW170817. So it can be emphasized that this model cannot describe reasonable SQS configurations. We also extend our work to calculate structural properties of hybrid stars (HSs). With the density dependent bag model (DDBM), these astrophysical constraints are fulfilled by the HSs configurations within a very restricted range of the three parameters. The present work is the first to constrain the parameters of DDBM for both SQS and HSs using the recent astrophysical constraints on tidal deformabiity from GW170817 and that on mass-radius relationship from NICER data.

    ↳ nucl-thhep-phNPA(2024)·26 citations
25. 25*

    Mass and wind luminosity of young Galactic open clusters in Gaia DR2

    Silvia Celli🇮🇹 · Andreas Specovius🇩🇪 · Stefano Menchiari🇮🇹 · Alison Mitchell · Giovanni Morlino🇮🇹

    Context. Star clusters constitute a significant part of the stellar population in our Galaxy. The feedback processes they exert on the interstellar medium impact multiple physical processes from the chemical to the dynamical evolution of the Galaxy. In addition, young and massive stellar clusters might act as efficient particle accelerators and contribute to the production of cosmic rays. Aims. We aim at evaluating the wind luminosity driven by the young (< 30 Myr) Galactic open stellar clusters observed by the Gaia space mission. This is crucial for determining the energy channeled into accelerated particles. Methods. To do this, we developed a method relying on the number, magnitude, and line-of-sight extinction of the stars observed per cluster. Assuming that the stellar mass function follows a Kroupa mass distribution and accounting for the maximum stellar mass allowed by the age and mass of the parent cluster, we conservatively estimated the mass and wind luminosity of 387 local clusters within the second data release of Gaia. Results. We compared the results of our computation with recent estimates of young cluster masses. With respect to these, our sample is three times more abundant, particularly above a few thousand solar masses. This is of the utmost relevance for predicting the gamma-ray emission resulting from the interaction of accelerated particles. The cluster wind luminosity distribution we obtained extends up to 3x10^38 erg/s. This is a promising feature in terms of potential particle acceleration scenarios.

    ↳ astro-ph.GAastro-ph.SRhep-phAstron.Astrophys.(2024)·26 citations
26. 26*

    Hints of Neutrino Dark Matter scattering in the CMB? Constraints from the Marginalized and Profile Distributions

    William Giarè🇬🇧 · Adrià Gómez-Valent🇪🇸 · Eleonora Di Valentino🇬🇧 · Carsten van de Bruck🇬🇧

    We study scatter-like interactions between neutrinos and dark matter in light of different combinations of temperature, polarization and lensing data released by three independent CMB experiments - the Planck satellite, the Atacama Cosmology Telescope (ACT), and the South Pole Telescope (SPT) - in conjunction with Baryon Acoustic Oscillation (BAO) measurements. We apply two different statistical methodologies. Alongside the usual marginalization technique, we cross-check all the results through a Profile Likelihood analysis. As a first step, working under the assumption of massless neutrinos, we perform a comprehensive (re-)analysis aimed at assessing the validity of some recent results hinting at a mild preference for non-vanishing interactions from small-scale CMB data. We find compelling resilience in the results already documented in the literature, confirming that interactions with a strength $u_{\nu \mathrm{DM}}\sim 10^{-5}-10^{-4}$ appear to be globally favored by ACT (both alone and in combination with Planck). This result is corroborated by the inclusion of additional data, such as the recent ACT-DR6 lensing likelihood, as well as by the Profile Likelihood analysis. Interestingly, a fully consistent preference for interactions emerges from SPT, as well, although it is weaker than the one obtained from ACT. As a second step, we repeat the same analysis considering neutrinos as massive particles. Despite the larger parameter space, all the hints pointing towards interactions are confirmed also in this more realistic case. In addition, we report a very mild preference for interactions in Planck+BAO alone (not found in the massless case) which aligns with small-scale data. While this latter result is not fully confirmed by the Profile Likelihood analysis, the profile distribution does confirm that interactions are not disfavoured by Planck.

    ↳ astro-ph.COhep-phPRD(2024)·24 citations
27. 27*

    Compact Scalars at the Cosmological Collider

    Priyesh Chakraborty🇺🇸 · John Stout🇺🇸

    We study the dynamics of scalar fields with compact field spaces, or axions, in de Sitter space. We argue that the field space topology can qualitatively affect the physics of these fields beyond just which terms are allowed in their actions. We argue that the sharpest difference is for massless fields -- the free massless noncompact scalar field does not admit a two-point function that is both de Sitter-invariant and well-behaved at long distances, while the massless compact scalar does. As proof that this difference can be observable, we show that the long-distance behavior of a heavy scalar field, and thus its cosmological collider signal, can qualitatively change depending on whether it interacts with a light compact or noncompact scalar field. We find an interesting interplay between the circumference of the field space and the Hubble scale. When the field space is much larger than Hubble, the compact field behaves similarly to a light noncompact field and forces the heavy field to dilute much faster than any free field can. However, depending on how much smaller the field space is compared to Hubble, the compact field can cause the heavy scalar to decay either faster or slower than any free field and so we conclude that there can be qualitative and observable consequences of the field space's topology in inflationary correlation functions.

    ↳ hep-thhep-phJHEP(2024)·36 citations
28. 28*

    Gravitational-wave constraints on scalar-tensor gravity from a neutron star and black-hole binary GW200115

    Hiroki Takeda🇯🇵 · Shinji Tsujikawa🇯🇵 · Atsushi Nishizawa🇯🇵

    In nonminimally coupled theories where a scalar field is coupled to the Ricci scalar, neutron stars (NSs) can have scalar charges through an interaction with matter mediated by gravity. On the other hand, the same theories do not give rise to hairy black hole (BH) solutions. The observations of gravitational waves (GWs) emitted from an inspiralling NS-BH binary system allows a possibility of constraining the NS scalar charge. Moreover, the nonminimally coupled scalar-tensor theories generate a breathing scalar mode besides two tensor polarizations. Using the GW200115 data of the coalescence of a BH-NS binary, we place observational constraints on the NS scalar charge as well as the nonminimal coupling strength for a subclass of massless Horndeski theories with a luminal GW propagation. Unlike past related works, we exploit a waveform for a mixture of tensor and scalar polarizations. Taking the breathing mode into account, the scalar charge is more tightly constrained in comparison to the analysis of the tensor GWs alone. In nonminimally coupled theories including Brans-Dicke gravity and spontaneous scalarization scenarios with/without a kinetic screening, we put new bounds on model parameters of each theory.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2024)·26 citations
29. 29*

    Pole-Skipping and Chaos in Hot $\mathcal{M}$QCD

    Gopal Yadav🇮🇳 · Shivam Singh Kushwah🇮🇳 · Aalok Misra🇮🇳

    We address the question of whether thermal QCD at high temperature is chaotic from the $\mathcal{M}$ theory dual of QCD-like theories at intermediate coupling as constructed in arXiv: 2004.07259. The equations of motion of the gauge-invariant combination $Z_s(r)$ of scalar metric perturbations is shown to possess an irregular singular point at the horizon radius $r_h$. Very interestingly, at a specific value of the imaginary frequency and momentum used to read off the analogs of the ''Lyapunov exponent'' ${\lambda }_L$ and ''butterfly velocity'' $v_b$ not only does $r_h$ become a regular singular point, but truncating the incoming mode solution of $Z_s(r)$ as a power series around $r_h$, yields a ''missing pole'', i.e., $C_{n,n+1}=0,\det M^{(n)}=0,n\in {\mathbb{Z}}^{+}$ is satisfied for a single $n\ge 3$ depending on the values of the string coupling $g_s$, number of (fractional) $D3$ branes $(M)N$ and flavor $D7$-branes $N_f$ in the parent type IIB set (arXiv:hep-th/0902.1540), e.g., for the QCD(EW-scale)-inspired $N=100,M=N_f=3,g_s=0.1$, one finds a missing pole at $n=3$. For integral $n>3$, truncating $Z_s(r)$ at $\mathcal{O}((r-r_h{)}^n)$, yields $C_{n,n+1}=0$ at order $n,\forall n\ge 3$. Incredibly, (assuming preservation of isotropy in ${\mathbb{R}}^3$ even with the inclusion of higher derivative corrections) the aforementioned gauge-invariant combination of scalar metric perturbations receives no $\mathcal{O}(R^4)$ corrections. Hence, (the aforementioned analogs of) ${\lambda }_L,v_b$ are unrenormalized up to $\mathcal{O}(R^4)$ in $\mathcal{M}$ theory.

    ↳ hep-thgr-qchep-phJHEP(2024)·10 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.