Fri·Oct 9, 2020Friday·October 9, 2020

1. 01*

   Searching for New Interactions at Sub-micron Scale Using the Mossbauer Effect

   Giorgio Gratta🇺🇸 · David E. Kaplan🇺🇸 · Surjeet Rajendran🇺🇸

   A new technique to search for new scalar and tensor interactions at the sub-micrometer scale is presented. The technique relies on small shifts of nuclear gamma lines produced by the coupling between matter and the nuclei in the source or absorber of a Mossbauer spectrometer. Remarkably, such energy shifts are rather insensitive to electromagnetic interactions that represent the largest background in searches for new forces using atomic matter. This is because nuclei are intrinsically shielded by the electron clouds. Additionally, electromagnetic interactions cause energy shifts by coupling to nuclear moments that are suppressed by the size of the nuclei, while new scalar interactions can directly affect these shifts. Finally, averaging over unpolarized nuclei, further reduces electromagnetic interactions. We discuss several possible configurations, using the traditional Mossbauer effect as well as nuclear resonant absorption driven by synchrotron radiation. For this purpose, we examine the viability of well known Mossbauer nuclides along with more exotic ones that result in substantially narrower resonances. We find that the technique introduced here could substantially improve the sensitivity to a variety of new interactions and could also be used, in conjunction with mechanical force measurements, to corroborate a discovery or explore the new physics that may be behind a discovery.

   hep-phhep-exhep-thnucl-exPRD(2020)·9 citations
2. 02*

   Revisiting Generalized Two Higgs Doublet Model in the Light of Muon Anomaly and Lepton Flavor Violating Decays at HL-LHC

   Nivedita Ghosh🇮🇳 · Jayita Lahiri🇮🇳

   One of the main motivations to look beyond the SM is the discrepancy between the theoretical prediction and observation of anomalous magnetic moment of muon. Alleviating this tension between theory and experiment and satisfying the bounds from lepton flavor violation data simultaneously is a challenging task. In this paper, we consider generalised Two Higgs Doublet Model, with a Yukawa structure as a perturbation of Type X Two Higgs Doublet Model. In view of this model, we explore muon anomaly and lepton flavor violation along with constraints coming from B-physics, theoretical constraints, electroweak observables and collider data which can restrict the model parameter space significantly. We find that within the framework of this model it is possible to obtain regions allowed by all constraints, that can provide an explanation for the observed muon anomaly and at the same time predicts interesting signatures of lepton flavor violation. Furthermore, we consider the flavor violating decay of low-mass CP-odd scalar to probe the allowed parameter space at future runs of the LHC. With simple cut-based analysis we show that part of that parameter space can be probed with significance $>5\sigma$. We also provide Artificial Neural Network analysis which definitely improves our cut-based results significantly.

   hep-phPRD(2021)·23 citations
3. 03*

   Establishing limits for the monopole production in pp accelerators

   B. M. Carlos🇧🇷 · M. B. Gay Ducati🇧🇷

   The spin 1/2 magnetic monopole pair production and the spin 0 monopolium production are studied in proton-proton collisions. For the pair production, the velocity-dependent coupling model and the additional effective coupling with a magnetic moment parameter are used for the calculation of photon fusion and Drell Yan cross sections. Since the monopole mass is unknown, the mass range employed is based on the last results of ATLAS and the MoEDAL experiment, which set a minimal value of around 2 TeV. The cross sections are calculated for the center of mass energies of the LHC, for its successor, the HE-LHC and for the future collider FCC. As a result, the estimated mass limits for observation in LHC and the other accelerators are obtained and the advantages in using both effective couplings and the monopolium as an indirect measure are discussed.

   hep-phhep-exhep-th3 citations
4. 04*

   An effective field theory approach for electroweak interactions in the high energy limit

   Melina Gómez Bock🇲🇽 · Martin Hentschinski🇲🇽 · Agustín Sabio Vera🇪🇸

   We present an effective action for the electroweak sector of the Standard Model valid for the calculation of scattering amplitudes in the high energy (Regge) limit. Gauge invariant Wilson lines are introduced to describe reggeized degrees of freedom whose interactions are generated by effective emission vertices. From this approach previous results at leading logarithmic accuracy for electroweak boson Regge trajectories are reproduced together with the corresponding interaction kernels. The proposed framework lays the path for calculations at higher orders in perturbation theory.

   hep-phhep-thEPJC(2020)·3 citations
5. 05*

   Dark matter, electroweak phase transition and gravitational wave in the type-II two-Higgs-doublet model with a singlet scalar field

   Xiao-Fang Han🇨🇳 · Lei Wang🇨🇳 · Yang Zhang🇨🇳

   In the framework of type-II two-Higgs-doublet model with a singlet scalar dark matter $S$, we study the dark matter observables, the electroweak phase transition, and the gravitational wave signals by such strongly first order phase transition after imposing the constraints of the LHC Higgs data. We take the heavy CP-even Higgs $H$ as the only portal between the dark matter and SM sectors, and find the LHC Higgs data and dark matter observables require $m_S$ and $m_H$ to be larger than 130 GeV and 360 GeV for $m_A=600$ GeV in the case of the 125 GeV Higgs with the SM-like coupling. Next, we carve out some parameter space where a strongly first order electroweak phase transition can be achieved, and find benchmark points for which the amplitudes of gravitational wave spectra reach the sensitivities of the future gravitational wave detectors.

   hep-phPRD(2021)·38 citations
6. 06*

   Linear Breit-Wheeler pair production by high-energy bremsstrahlung photons colliding with an intense X-ray laser pulse

   Alina Golub🇩🇪 · Selym Villalba-Chávez🇩🇪 · Hartmut Ruhl🇩🇪 · Carsten Müller🇩🇪

   A possible setup for the experimental verification of linear Breit-Wheeler pair creation of electrons and positrons in photon-photon collisions is studied theoretically. It combines highly energetic bremsstrahlung photons, which are assumed to be generated by an incident beam of GeV electrons penetrating through a high-$Z$ target, with keV photons from an X-ray laser field, which is described as a focused Gaussian pulse. We discuss the dependencies of the pair yields on the incident electron energy, target thickness, laser parameters, and collision geometry. It is shown that, for suitable conditions which are nowadays in reach at X-ray laser facilities, the resulting number of created particles seems to be well accessible for enabling the first experimental observation of the linear Breit-Wheeler process $\gamma \gamma \to e^{+}{e}^{-}$.

   hep-phPRD(2021)·23 citations
7. 07*

   Cornering the axion with CP-violating interactions

   Ciaran A. J. O'Hare🇦🇺 · Edoardo Vitagliano🇺🇸

   Besides CP-preserving interactions, axions and axion-like particles may also have small CP-violating scalar Yukawa interactions with nucleons and electrons. Any such interaction will generate macroscopic monopole-dipole forces which can be searched for experimentally. When the best experimental limits on scalar interactions are combined with stellar energy-loss arguments constraining pseudoscalar interactions, strong bounds can be set on CP-violating axion couplings which almost intersect the expectation for QCD models. Over the years, both astrophysical and laboratory tests have improved. We provide a much-needed up-to-date compilation of these constraints, showing improvements in some regions of parameter space by factors between 40 and 130. We advocate experimental opportunities, without astrophysical or dark-matter assumptions, to track down the axion in the lesser-explored corners of its parameter space.

   hep-phPRD(2020)·111 citations
8. 08*

   High-intensity scaling in UV-modified QED

   Robin Ekman🇬🇧 · Tom Heinzl🇬🇧 · Anton Ilderton🇬🇧

   QED perturbation theory in a background field has been conjectured to break down for sufficiently high field intensity. The high-intensity behavior of a field theory is however intertwined with its high-energy (UV) behavior. Here we show that a UV modification of QED changes the high-intensity behaviour of observables. Specifically we study non-linear Compton scattering in a constant crossed field in QED with an additional Pauli term. In the UV modified theory the cross section exhibits a faster power-law scaling with intensity than in ordinary QED.

   hep-phPRD(2020)·5 citations
9. 09*

   Top pair production at ultra-high energies

   V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺

   The top quark, the heaviest quark and, indeed, the heaviest elementary particle known today, constitutes a novel probe of the long-lived medium in quark-gluon phase which, as expected, can be produced even in light nuclei collisions at ultra-high energies. Some distinctive features are considered for particle production in the top sector in ultra-high energy domain. The antitop-top pair production is studied within the quantum chromodynamics and effective field theory approach used for calculations of total partonic cross sections. Predictions for all observables are computed at NNLO in quantum chromodynamics and at LO in effective field theory. These quantitative results can be important for both the future collider experiments at center-of-mass energy frontier and the improvement of the phenomenological models for development of the cosmic ray cascades in ultra-high energy domain. Thus the study allows the better understanding of heavy particle production and emphasizes the exciting interrelation between the high-energy physics on accelerators and ultra-high energy cosmic ray measurements.

   hep-phJ.Phys.Conf.Ser.(2020)·5 citations
10. 10*

    Phenomenological constraints on the transport properties of QCD matter with data-driven model averaging

    D. Everett🇺🇸 · W. Ke🇺🇸 · J.-F. Paquet🇺🇸 · G. Vujanovic🇺🇸 · S. A. Bass🇺🇸 · L. Du🇺🇸 · C. Gale🇨🇦 · M. Heffernan🇨🇦 · U. Heinz🇺🇸 · D. Liyanage🇺🇸 · M. Luzum🇧🇷 · A. Majumder🇺🇸 and 36 other authors

    Using combined data from the Relativistic Heavy Ion and Large Hadron Colliders, we constrain the shear and bulk viscosities of quark-gluon plasma (QGP) at temperatures of $\sim 150-350$ MeV. We use Bayesian inference to translate experimental and theoretical uncertainties into probabilistic constraints for the viscosities. With Bayesian Model Averaging we account for the irreducible model ambiguities in the transition from a fluid description of the QGP to hadronic transport in the final evolution stage, providing the most reliable phenomenological constraints to date on the QGP viscosities.

    hep-phnucl-exnucl-thPRL(2021)·256 citations
11. 11*

    Neural-network analysis of Parton Distribution Functions from Ioffe-time pseudodistributions

    Luigi Del Debbio🇬🇧 · Tommaso Giani🇬🇧 · Joseph Karpie🇺🇸 · Kostas Orginos🇺🇸 · Anatoly Radyushkin🇺🇸 · Savvas Zafeiropoulos🇫🇷

    We extract two nonsinglet nucleon Parton Distribution Functions from lattice QCD data for reduced Ioffe-time pseudodistributions. We perform such analysis within the NNPDF framework, considering data coming from different lattice ensembles and discussing in detail the treatment of the different source of systematics involved in the fit. We introduce a recipe for taking care of systematics and use it to perform our extraction of light-cone PDFs.

    hep-phhep-latJHEP(2021)·80 citations
12. 12*

    X(2900) in a chiral quark model

    Yue Tan🇨🇳 · Jialun Ping🇨🇳

    Recently, the LHCb Collaboration reported their observation of the first two fully open-flavor tetraquark states named $X_0(2900)$ and $X_1(2900)$ with unknown parity. Inspired by the report, we consider all of possible four-quark candidates of $X(2900)$ including molecular structure and diquark structure in a chiral quark model with the help of Gaussian expansion method. Two different structures coupling is also considered. To identify the genuine resonances, real-scaling method (stabilization method) was employed. The results show that no candidate of $X(2900)$ is founded in $00^{+}$ and $01^{+}$ $cs\bar{q}\bar{q}$ system below the threshold of $D^{\ast }{\bar{K}}^{\ast }$, while there are two states in the $P$-wave excited $cs\bar{q}\bar{q}$ system, $D_1\bar{K}$ and $D_J\bar{K}$, which could be candidates of $X(2900)$. In this way, we assign negative parity to $X_1(2900)$, and $X_0(2900)$ maybe a resonance state above the threshold of $D^{\ast }{\bar{K}}^{\ast }$, more calculation is needed.

    hep-phCPC(2021)·32 citations
13. 13*

    Polarized QED cascades

    Daniel Seipt🇩🇪 · Christopher P. Ridgers🇬🇧 · Dario Del Sorbo🇺🇸 · Alec G. R. Thomas🇺🇸

    By taking the spin and polarization of the electrons, positrons and photons into account in the strong-field QED processes of nonlinear Compton emission and pair production, we find that the growth rate of QED cascades in ultra-intense laser fields can be substantially reduced. While this means that fewer particles are produced, we also found them to be highly polarized. We further find that the high-energy tail of the particle spectra is polarized opposite to that expected from Sokolov-Ternov theory, which cannot be explained by just taking into account spin-asymmetries in the pair production process, but results significantly from "spin-straggling". We employ a kinetic equation approach for the electron, positron and photon distributions, each of them spin/polarization-resolved, with the QED effects of photon emission and pair production modelled by a spin/polarization dependent Boltzmann-type collision operator. For photon-seeded cascades, depending on the photon polarization, we find an excess or a shortage of particle production in the early stages of cascade development, which provides a path towards a controlled experiment. Throughout this paper we focus on rotating electric field configuration, which represent an idealized model and allows for a straightforward interpretation of the observed effects.

    hep-phphysics.plasm-phNew J.Phys.(2021)·42 citations
14. 14*

    A Step Toward Model Comparison: Connecting Electroweak-Scale Observables to BSM through EFT and Bayesian Statistics

    Anisha🇮🇳 · Supratim Das Bakshi🇮🇳 · Joydeep Chakrabortty🇮🇳 · Sunando Kumar Patra🇮🇳

    Recognizing the potential of effective field theories to posit multiple BSM scenarios in similar footing, with a possibility to compare them, we inspect the effects of 11 single scalar-multiplet extensions of the SM on the combined set of electroweak precision observables and Higgs signal strength data, by systematically integrating out the heavy multiplets and computing the resulting SMEFT operators and Wilson coefficients (WCs) up to one-loop level. Noting that multiple BSM models give rise to a degenerate set of WCs, we then perform Bayesian statistical inference both directly on the BSM parameters and on the associated set of independent WCs. Using the posteriors of the BSM parameters, we infer the respective (correlated) WC-distributions and compare both the model-independent and dependent analyses by overlaying the 2-D marginal WC-posteriors from both processes, thus laying the ground for a data-driven attempt to compare diverse BSM theories of different origins, and hopefully, a possible way to approach the intractable inverse problem. We also demonstrate, with an example model, the crucial role of theoretical constraints to rule out large chunks of BSM parameter spaces. The entirety of numerical results is available in GitHub.

    hep-phhep-exPRD(2021)·32 citations
15. 15*

    The universal function of the diffractive process in color dipole picture

    Z.Jalilian🇮🇷 · G.R.Boroun🇮🇷

    In this presentation, we obtain the corresponding universal function to the diffractive process and show the cross section exhibits the geometrical scaling. It is observed the diffractive theory according to the color dipole approach at small-$x$ is a convenient framework that reveals the color transparency and the saturation phenomena. Also we calculate the contribution of heavy quark productions in the diffractive cross section for high energy that is determined by the small size dipole configuration. The ratio of the diffractive cross section to the total cross section in the electron-proton collision is the other important quantity that is computed in this work.

    hep-phCPC(2021)·2 citations
16. 16*

    Simultaneous extraction of ${\alpha }_s$ and $m_t$ from LHC $t\bar{t}$ differential distributions

    Amanda M. Cooper-Sarkar🇬🇧 · Michal Czakon🇩🇪 · Matthew A. Lim🇮🇹 · Alexander Mitov🇬🇧 · Andrew S. Papanastasiou🇬🇧

    We present a joint extraction of the strong coupling ${\alpha }_s$ and the top-quark pole mass $m_t$ from measurements of top-quark pair production performed by the ATLAS and CMS experiments at the 8 TeV LHC. For the first time, differential NNLO theory predictions for different values of the top-quark mass are utilised for four kinematic distributions: the average transverse momentum of the top-quark, its average rapidity and the pair invariant mass and rapidity. The use of fastNLO tables for these distributions allows rapid evaluation of the differential theory predictions for different PDF sets. We consider the single differential distributions from the experiments both separately and in combination in order to obtain the best fit to theory. Our final values are ${\alpha }_s=0.1159_{-0.0014}^{+0.0013}$ and $m_t=173.8_{-0.8}^{+0.8}$ GeV which are compatible with previous extractions using top-quark measurements. In the case of $m_t$, our value is also compatible with the world average value collated by the Particle Data Group.

    hep-phhep-ex26 citations
17. 17*

    The RGB tip of galactic globular clusters and the revision of the bound of the axion-electron coupling

    O. Straniero🇮🇹 · C. Pallanca🇮🇹 · E. Dalessandro🇮🇹 · I. Dominguez🇪🇸 · F. R. Ferraro🇮🇹 · M. Giannotti🇺🇸 · A. Mirizzi🇮🇹 · L. Piersanti🇮🇹

    By combining Hubble Space Telescope (HST) and ground based optical and near-infrared photometric samples, we derive the RGB tip absolute magnitude of 22 galactic globular clusters (GGCs). The effects of varying the distance and the metallicity scales are also investigated. Then we compare the observed tip luminosities with those predicted by state-of-the-art stellar models that include the energy-loss due to the axion production in the degenerate core of red giant stars. We find that theoretical predictions including only the energy-loss by plasma neutrinos are, in general, in good agreement with the observed tip bolometric magnitudes, even though the latter are about 0.04 mag brighter, on the average. This small shift may be the result of systematic errors affecting the evaluation of the RGB tip bolometric magnitudes or, alternatively, it could be ascribed to an axion-electron coupling causing a non-negligible thermal production of axions. In order to estimate the strength of this possible axion sink, we perform a cumulative likelihood analysis using the RGB tips of the whole set of 22 GGCs. All the possible source of uncertainties affecting both the measured bolometric magnitudes and the corresponding theoretical predictions are carefully considered. As a result, we find that the value of the axion-electron coupling parameter that maximizes the likelihood probability is gae/10^13=0.60(+0.32;-0.58). This hint is valid, however, if the dominant energy sinks operating in the core of red giant stars are standard neutrinos and axions coupled with electrons. Any additional energy-loss process, not included in the stellar models, would reduce such a hint. Nevertheless, we find that values gae/10^13 > 1.48 can be excluded with a 95% of confidence.

    ↳ astro-ph.SRhep-phAstron.Astrophys.(2020)·103 citations
18. 18*

    Cosmological constraints on multi-interacting dark matter

    Niklas Becker🇩🇪 · Deanna C. Hooper🇧🇪 · Felix Kahlhoefer🇩🇪 · Julien Lesgourgues🇩🇪 · Nils Schöneberg🇩🇪

    The increasingly significant tensions within $\Lambda$CDM, combined with the lack of detection of dark matter (DM) in laboratory experiments, have boosted interest in non-minimal dark sectors, which are theoretically well-motivated and inspire new search strategies for DM. Here we consider, for the first time, the possibility of DM having simultaneous interactions with photons, baryons, and dark radiation (DR). We have developed a new and efficient version of the Boltzmann code CLASS that allows for one DM species to have multiple interaction channels. With this framework we reassess existing cosmological bounds on the various interaction coefficients in multi-interacting DM scenarios. We find no clear degeneracies between these different interactions and show that their cosmological effects are largely additive. We further investigate the possibility of these models to alleviate the cosmological tensions, and find that the combination of DM-photon and DM-DR interactions can at the same time reduce the $S_8$ tension (from $2.3\sigma$ to $1.2\sigma$) and the $H_0$ tension (from $4.3\sigma$ to $3.1\sigma$). The public release of our code will pave the way for the study of various rich dark sectors.

    ↳ astro-ph.COhep-phJCAP(2021)·88 citations
19. 19*

    String Memories ... openly retold

    Alice Aldi🇮🇹 · Massimo Bianchi🇮🇹 · Maurizio Firrotta🇮🇹

    We identify string corrections to the EM memory effect. Though largely negligible in the low-energy limit, the effect become relevant in high-energy collisions and in extreme events. We illustrate our findings in a simple unoriented bosonic string model. Thanks to the coherent effect of the infinite tower of open string resonances, the corrections are non-perturbative in ${\alpha }^{\prime }$, modulated in retarded time and slowly decaying even at large distances from the source. Remarkably compact expressions obtain for special choices of the kinematics in tree-level 4-point amplitudes. We discuss further corrections occurring at higher-points and the exponential damping resulting from broadening and shifting of the massive poles due to loops. Finally we estimate the range of the parameters and masses for detectability in semi-realistic (Type I) contexts and propose a rationale for this string memory effect.

    ↳ hep-thastro-ph.HEhep-phPLB(2021)·16 citations
20. 20*

    Phase Transitions from the Fifth Dimension

    Kaustubh Agashe🇺🇸 · Peizhi Du🇺🇸 · Majid Ekhterachian🇺🇸 · Soubhik Kumar🇺🇸 · Raman Sundrum🇺🇸

    We study the cosmological transition of 5D warped compactifications, from the high-temperature black-brane phase to the low-temperature Randall-Sundrum I phase. The transition proceeds via percolation of bubbles of IR-brane nucleating from the black-brane horizon. The violent bubble dynamics can be a powerful source of observable stochastic gravitational waves. While bubble nucleation is non-perturbative in 5D gravity, it is amenable to semiclassical treatment in terms of a "bounce" configuration interpolating between the two phases. We demonstrate how such a bounce configuration can be smooth enough to maintain 5D effective field theory control, and how a simple ansatz for it places a rigorous lower-bound on the transition rate in the thin-wall regime, and gives plausible estimates more generally. When applied to the Hierarchy Problem, the minimal Goldberger-Wise stabilization of the warped throat leads to a slow transition with significant supercooling. We demonstrate that a simple generalization of the Goldberger-Wise potential modifies the IR-brane dynamics so that the transition completes more promptly. Supercooling determines the dilution of any (dark) matter abundances generated before the transition, potentially at odds with data, while the prompter transition resolves such tensions. We discuss the impact of the different possibilities on the strength of the gravitational wave signals. Via AdS/CFT duality the warped transition gives a theoretically tractable holographic description of the 4D Composite Higgs (de)confinement transition. Our generalization of the Goldberger-Wise mechanism is dual to, and concretely models, our earlier proposal in which the composite dynamics is governed by separate UV and IR RG fixed points. The smooth 5D bounce configuration we introduce complements the 4D dilaton/radion dominance derivation presented in our earlier work.

    ↳ hep-thgr-qchep-phJHEP(2021)·54 citations
21. 21*

    Dilatonic states near holographic phase transitions

    Daniel Elander🇫🇷 · Maurizio Piai🇬🇧 · John Roughley🇬🇧

    The spectrum of bound states of special strongly coupled confining field theories might include a parametrically light dilaton, associated with the formation of enhanced condensates that break (approximate) scale invariance spontaneously. It has been suggested in the literature that such a state may arise in connection with the theory being close to the unitarity bound in holographic models. We extend these ideas to cases where the background geometry is non-AdS, and the gravity description of the dual confining field theory has a top-down origin in supergravity. We exemplify this programme by studying the circle compactification of Romans six-dimensional half-maximal supergravity. We uncover a rich space of solutions, many of which were previously unknown in the literature. We compute the bosonic spectrum of excitations, and identify a tachyonic instability in a region of parameter space for a class of regular background solutions. A tachyon only exists along an energetically disfavoured (unphysical) branch of solutions of the gravity theory; we find evidence of a first-order phase transition that separates this region of parameter space from the physical one. Along the physical branch of regular solutions, one of the lightest scalar particles is approximately a dilaton, and it is associated with a condensate in the underlying theory. Yet, because of the location of the phase transition, its mass is not parametrically small, and it is, coincidentally, the next-to-lightest scalar bound state, rather than the lightest one.

    ↳ hep-thhep-lathep-phPRD(2021)·24 citations
22. 22*

    Quasielastic Electromagnetic Scattering Cross Sections and World Data Comparisons in the {\fontfamily{qcr}\selectfont GENIE} Monte Carlo Event Generator

    Joshua L. Barrow🇺🇸 · Steven Gardiner🇺🇸 · Saori Pastore🇺🇸 · Minerba Betancourt🇺🇸 · Joseph Carlson🇺🇸

    The usage of Monte Carlo neutrino event generators (MC$\nu$EGs) is a norm within the high-energy $\nu$ scattering community. The relevance of quasielastic (QE) energy regimes to $\nu$ oscillation experiments implies that accurate calculations of $\nu A$ cross sections in this regime will be a key contributor to reducing the systematic uncertainties affecting the extraction of oscillation parameters. In spite of this, many MC$\nu$EGs utilize highly phenomenological, parameterized models of QE scattering cross sections. Moreover, a culture of validation of MC$\nu$EGs against prolific electron ($e$) scattering data has been historically lacking. In this work, we implement new $eA$ cross sections obtained from nuclear ab initio approaches in GENIE, the primary MC$\nu$EG utilized by the FNAL community. In particular, we utilize results from Quantum MC methods which solve the many-body nuclear problem in the Short-Time Approximation (STA), allowing consistent retention of two-nucleon dynamics which are crucial to explain available nuclear electromagnetic (electroweak) data over a wide range of energy and momentum transfers. This new implementation in GENIE is fully tested against the world QE electromagnetic data, finding agreement with available data below $\sim 2$GeV of beam energy with the aid of a scaling function formalism. The STA is currently limited to study $A\le 12$ nuclei, however, its semi-inclusive multibody identity components are exportable to other many-body computational techniques such as Auxiliary Field Diffusion MC which can reach $A\le 40$ systems while continuing to realize the factorization contained within the STA's multinucleon dynamics. Together, these developments promise to make future experiments such as DUNE more accurate in their assessment of MC$\nu$EG systematics, $\nu$ properties, and potentially empower the discovery of physics beyond the Standard Model.

    ↳ nucl-thhep-exhep-phnucl-exPRD(2021)·13 citations
23. 23*

    Why reducing the cosmic sound horizon alone can not fully resolve the Hubble tension

    Karsten Jedamzik🇫🇷 · Levon Pogosian🇨🇦 · Gong-Bo Zhao🇨🇳

    The mismatch between the locally measured expansion rate of the universe and the one inferred from the cosmic microwave background measurements by Planck in the context of the standard $\Lambda$CDM, known as the Hubble tension, has become one of the most pressing problems in cosmology. A large number of amendments to the $\Lambda$CDM model have been proposed in order to solve this tension. Many of them introduce new physics, such as early dark energy, modifications of the standard model neutrino sector, extra radiation, primordial magnetic fields or varying fundamental constants, with the aim of reducing the sound horizon at recombination $r_{\star }$. We demonstrate here that any model which only reduces $r_{\star }$ can never fully resolve the Hubble tension while remaining consistent with other cosmological datasets. We show explicitly that models which achieve a higher Hubble constant with lower values of matter density ${\Omega }_m{h}^2$ run into tension with the observations of baryon acoustic oscillations, while models with larger ${\Omega }_m{h}^2$ develop tension with galaxy weak lensing data.

    ↳ astro-ph.COhep-phCommun.in Phys.(2021)·255 citations
24. 24*

    Nonminimal Couplings and the Forgotten Field of Axion Inflation

    Evan McDonough🇺🇸 · Alan H. Guth🇺🇸 · David I. Kaiser🇺🇸

    We study the multifield dynamics of axion models nonminimally coupled to gravity. As usual, we consider a canonical $U(1)$ symmetry-breaking model in which the axion is the phase of a complex scalar field. If the complex scalar field has a nonminimal coupling to gravity, then the (oft-forgotten) radial component can drive a phase of inflation prior to an inflationary phase driven by the axion field. In this setup, the mass of the axion field is dependent on the radial field because of the nonminimal coupling, and the axion remains extremely light during the phase of radial inflation. As the radial field approaches the minimum of its potential, there is a transition to a second phase of inflation during which the axion field contributes a substantial fraction of the system's total energy density, yielding a phase of "natural inflation." This system exhibits ultra-light isocurvature perturbations, which are converted to adiabatic perturbations by a turning field-space trajectory. For models wherein the CMB pivot scale exited the horizon well before the turn, this acts to suppress the tensor-to-scalar ratio $r$, without generating CMB non-Gaussianity or observable isocurvature perturbations. Finally, we note that for certain parameters the interaction strength between axion and gauge fields can be suppressed during the first phase of inflation relative to its value during the second phase by several orders of magnitude. This decouples the constraints on the inflationary production of gauge fields (e.g., from primordial black holes) from the constraints on their production during (p)reheating.

    ↳ hep-thastro-ph.COgr-qchep-ph34 citations
25. 25*

    Axion-like particle searches with MeerKAT and SKA

    Ahmed Ayad🇿🇦 · Geoff Beck🇿🇦

    In the past few years, the search for axion-like particles (ALPs) has grown significantly due to their potential to account for the total abundance of the cold dark matter (CDM) in the universe. The coupling between ALPs and photons allows the spontaneous decay of ALPs into pairs of photons. For ALPs condensed in CDM halos around galaxies, the stimulated decay of ALPs is also possible. In this work, we examine the detectability of the radio emissions produced from this process with forthcoming radio telescopes such as the Square Kilometer Array (SKA) and MeerKAT. Our results, using recent more realistic sensitivity estimates, show that previous non-observation upper-limits projected for the SKA were highly optimistic, with the limits from dwarf galaxy observations being weakened by an order of magnitude at least. Notably, our results also depend far more strongly on ALP mass than previously, due to the inclusion of frequency dependent degradation effects. We show that the strongest potential environment to probe ALPs is nearby radio galaxies (due to the strong photon enhancement factor). In addition, with the use of a visibility taper, ALPs in the mass range of $4.96\times 10^{-7}\text{–}1.04\times 10^{-4}\mathrm{eV}$ would have non-observation upper limits on the ALP-photon $g_{a\gamma }$ in the range of $1.83\times 10^{-12}\text{–}7.69\times 10^{-10}{\mathrm{GeV}}^{-1}$ with SKA. MeerKAT can only produce limits similar to the CAST experiment within 50 hours of observation. Finally, we demonstrate that magnetic conversion of CDM ALPs to photons, in galactic magnetic fields, is highly sub-dominant, even to spontaneous decay.

    ↳ astro-ph.HEhep-phJCAP(2022)·5 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.