Thu·Jun 23, 2022Thursday·June 23, 2022

1. 01*

   Effects of Reheating on Charged Lepton Yukawa Equilibration and Leptogenesis

   Arghyajit Datta🇮🇳 · Rishav Roshan🇰🇷 · Arunansu Sil🇮🇳

   We show that the process of non-instantaneous reheating during the post-inflationary period can have a sizable impact on the charged lepton Yukawa equilibration temperature in the early Universe. This suggests relooking the effects of lepton flavors in the leptogenesis scenario where the production and decay of right-handed neutrinos take place within this prolonged era of reheating. We find this observation has the potential to shift the flavor regime(s) of leptogenesis compared to the standard thermal scenario.

   hep-phPRL(2024)·24 citations
2. 02*

   Lepton Flavour Violation in minimal grand-unified type II seesaw models

   Lorenzo Calibbi🇨🇳 · Xiyuan Gao🇨🇳

   We revisit minimal non-supersymmetric models of SU(5) Grand Unification with the type II seesaw mechanism as the origin of neutrino masses. Imposing the requirement of gauge coupling unification and the proton lifetime bounds, we perform a Bayesian fit and obtain robust quantitative information on the mass scales of the beyond the Standard Model particles. We then study lepton-flavour-violating (LFV) processes induced by the type II scalar triplet and its SU(5) partners, showing that the interplay of upcoming searches for different LFV observables can provide additional information on the masses of the new particles, as well as non-trivial constraints on neutrino parameters.

   hep-phhep-exPRD(2022)·17 citations
3. 03*

   On the determination of uncertainties in parton densities

   N.T. Hunt-Smith🇦🇺 · A. Accardi🇺🇸 · W. Melnitchouk🇺🇸 · N. Sato🇺🇸 · A.W. Thomas🇦🇺 · M.J. White🇦🇺

   We review various methods used to estimate uncertainties in quantum correlation functions, such as parton distribution functions (PDFs). Using a toy model of a PDF, we compare the uncertainty estimates yielded by the traditional Hessian and data resampling methods, as well as from explicitly Bayesian analyses using nested sampling or hybrid Markov chain Monte Carlo techniques. We investigate how uncertainty bands derived from neural network approaches depend on details of the network training, and how they compare to the uncertainties obtained from more traditional methods with a specific underlying parametrization. Our results show that utilizing a neural network on a simplified example of PDF data has the potential to inflate uncertainties, in part due to the cross validation procedure that is generally used to avoid overfitting data.

   hep-phhep-exnucl-thPRD(2022)·17 citations
4. 04*

   Searching for ultralight scalar dark matter with muonium and muonic atoms

   Yevgeny V. Stadnik🇦🇺

   Ultralight scalar dark matter may induce apparent oscillations of the muon mass, which may be directly probed via temporal shifts in the spectra of muonium and muonic atoms. Existing datasets and ongoing spectroscopy measurements with muonium are capable of probing scalar-muon interactions that are up to 12 orders of magnitude more stringent than astrophysical bounds. Ongoing free-fall experiments with muonium can probe forces associated with the exchange of virtual ultralight scalar bosons between muons and standard-model particles, offering up to 5 orders of magnitude improvement in sensitivity over complementary laboratory and astrophysical bounds.

   hep-phastro-ph.COgr-qcphysics.atom-phPRL(2023)·27 citations
5. 05*

   Double-heavy tetraquarks with strangeness in the chiral quark model

   Xiaoyun Chen🇨🇳 · Fu-Lai Wang🇨🇳 · Yue Tan🇨🇳 · Youchang Yang🇨🇳

   Recently, some progresses have been made on the double-heavy tetraquarks in the experiments, such as $T_{cc}$ reported by LHCb Collaboration, and $X_{cc\bar{s}\bar{s}}$ reported by the Belle Collaboration. Coming on the heels of our previous work about $T_{cc}$ and $T_{bb}$, we present a study on the bound states and the resonant states of its companions $QQ\bar{q}\bar{s}$ ($Q=c,b;q=u,s$) tetraquarks with strange flavor in the chiral quark model. Two pictures, one with meson-meson picture, another with diquark-antidiquark picture and their couplings are considered in our calculations. Isospin violation is neglected herein. Our numerical analysis indicates that only the state $bb\bar{u}\bar{s}$ with $\frac{1}{2}(1^{+})$ is bound, with the binding energy 3.5 MeV. Besides, we also find some resonant states for the double-heavy strange tetraquarks with the real scaling method.

   hep-phCPC(2023)·13 citations
6. 06*

   One-loop soft anomalous dimension matrices for $t\bar{t}j$ hadroproduction

   Bakar Chargeishvili🇩🇪 · Maria Vittoria Garzelli🇩🇪 · Sven-Olaf Moch🇩🇪

   We calculate the one-loop corrections to the soft anomalous dimension matrices for the production of a top-antitop quark pair in association with a jet at hadron colliders. This is a step forward towards implementing a procedure for the resummation of soft-gluon emission logarithms for the $t\bar{t}j+X$ hadroproduction process, that will enable the improvement of the accuracy of the $t\bar{t}j+X$ cross sections, beyond the current degree of knowledge. The latter, so far, has reached the next-to-leading order (NLO) level, complemented by the accuracy of the Shower Monte Carlo approaches used in matching the NLO computations to parton showers (PS) and by merging with matrix elements with a different number of light jets.

   hep-ph5 citations
7. 07*

   W-boson mass anomaly and vacuum structure in vector dark matter model with a singlet scalar mediator

   Seyed Yaser Ayazi🇮🇷 · Mojtaba Hosseini🇮🇷

   Motivated by the deviation of the W boson mass reported by the CDF collaboration, we study an extension of the Standard Model (SM) including a vector dark matter (VDM) candidate and a scalar mediator. In the model, the one-loop corrections induced by the new scalar, shift the W boson mass. We identify the parameter space of the model consistent with dark matter (DM) relic abundance, W mass boson anomaly, invisible Higgs decay at LHC, and direct detection of DM. It is shown that the W-mass anomaly can be explained for the large part of parameter space of VDM mass and scalar mediator mass between $100-124\mathrm{GeV}$ by the model. We also investigate the renormalization group equations (RGE) at one-loop order for the model. We show that the contribution of new scalar mediator to RGE, guarantees positivity and vacuum stability of SM Higgs up to Planck scale.

   hep-phInt.J.Mod.Phys.A(2023)·15 citations
8. 08*

   Cannibal dark matter decoupled from standard model: cosmological constraints

   Avirup Ghosh🇮🇳 · Sourav Gope🇮🇳 · Satyanarayan Mukhopadhyay🇮🇳

   An internally thermalized dark matter (DM) with only gravitational interaction with the standard model (SM) particles at low temperatures, may undergo number-changing self-scatterings in the early Universe, eventually freezing out to the observed DM abundance. If these reactions, such as a $3\to 2$ process, take place when the DM is non-relativistic, DM cannibalizes itself to cool much slower than standard non-relativistic matter during the cannibal phase. As shown in earlier studies, if the cannibal phase takes place during the matter-dominated epoch, there are very strong constraints from structure formation. Considering scenarios in which the cannibal phase freezes out in the radiation-dominated epoch instead, we show that cannibal DM decoupled from the SM can be viable, consistent with all present cosmological constraints. To this end, we solve the coupled evolution equations of the DM temperature and density, and determine its abundance for different DM self-couplings. We then evaluate the constraints on these parameters from the cosmic-microwave background power spectrum, the big-bang nucleosynthesis limits on the relativistic degrees of freedom, the Lyman-$\alpha$ limits on the DM free-streaming length and the theoretical upper bound on the $3\to 2$ annihilation rate from $S-$matrix unitarity. We find that depending upon the DM self-couplings, a scalar cannibal DM with mass in the range of around 80 eV to 700 TeV can make up the observed DM density and satisfy all the constraints, when the initial DM temperature ($T_{\mathrm{DM}}$) is lower than the SM one ($T_{\mathrm{SM}}$), with $T_{\mathrm{SM}}/9100\lesssim T_{\mathrm{DM}}\lesssim T_{\mathrm{SM}}/1.1$.

   hep-phastro-ph.COPRD(2022)·13 citations
9. 09*

   Neutrino-nucleus CC0$\pi$ cross-section tuning in GENIE v3

   Julia Tena-Vidal🇬🇧 · Costas Andreopoulos🇬🇧 · Adi Ashkenazi🇮🇱 · Joshua Barrow🇺🇸 · Steven Dytman🇺🇸 · Hugh Gallagher🇺🇸 · Alfonso Andres Garcia Soto🇺🇸 · Steven Gardiner🇺🇸 · Matan Goldenberg🇺🇸 · Robert Hatcher🇺🇸 · Or Hen🇺🇸 · Timothy J. Hobbs🇺🇸 and 11 other authors

   This article summarizes the state of the art of ${\nu }_{\mu }$ and ${\bar{\nu }}_{\mu }$ CC0$\pi$ cross-section measurements on carbon and argon and discusses the relevant nuclear models, parametrizations and uncertainties in GENIE v3. The CC0$\pi$ event topology is common in experiments at a few-GeV energy range. Although its main contribution comes from quasi-elastic interactions, this topology is still not well understood. The GENIE global analysis framework is exploited to analyze CC0$\pi$ datasets from MiniBooNE, T2K and MINERvA. A partial tune for each experiment is performed, providing a common base for the discussion of tensions between datasets. The results offer an improved description of nuclear CC0$\pi$ datasets as well as data-driven uncertainties for each experiment. This work is a step towards a GENIE global tune that improves our understanding of neutrino interactions on nuclei. It follows from earlier GENIE work on the analysis of neutrino scattering datasets on hydrogen and deuterium.

   hep-phPRD(2022)·31 citations
10. 10*

    Theory uncertainties in the fiducial Drell-Yan cross section and distributions

    Xuan Chen🇩🇪 · Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Pier Francesco Monni🇨🇭 · Emanuele Re🇫🇷 · Luca Rottoli🇨🇭 · Paolo Torrielli🇮🇹

    In these proceedings we study various sources of theoretical uncertainty in the Drell-Yan $p_T^{\ell \ell }$ spectrum focussing on the $p_T^{\ell \ell }\lesssim 100\mathrm{GeV}$ region. We consider several perturbative aspects related to the choice of the scale setting adopted in resummed calculations, and we assess their impact on the theoretical prediction both for the differential $p_T^{\ell \ell }$ spectrum and for the ${\mathrm{N}}^3\mathrm{LO}$ fiducial cross section. For both quantities, we find the results obtained with the different setups to be compatible with each other within the quoted uncertainty, highlighting the robustness of the theoretical prediction. In all cases, the experimental LHC data for the $p_T^{\ell \ell }$ spectrum is well described by our calculation.

    hep-phhep-ex5 citations
11. 11*

    Novel neutron decay mode inside neutron stars

    Wasif Husain🇦🇺 · Anthony W. Thomas🇦🇺

    We explore the suggestion that the neutron lifetime puzzle might be resolved by neutrons decaying into dark matter through the process, n \rightarrow \chi\chi\chi, with \chi having a mass one third of that of the neutron. In particular, we examine the consequences of such a decay mode for the properties of neutron stars. Unlike an earlier suggested decay mode, in order to satisfy the constraints on neutron star mass and tidal deformability, there is no need for a strong repulsive force between the dark matter particles. This study suggests the possibility of having hot dark matter at the core of the neutron star and presents a possible mechanism of dark matter cooling, and examines the possible signal of neutrons decaying in this way inside the neutron star right after its birth.

    hep-phastro-ph.HEJ.Phys.G(2023)·25 citations
12. 12*

    Semiexclusive dilepton production in proton-proton collisions with one forward proton measurement at the LHC

    Barbara Linek🇵🇱

    We discuss the mechanisms of photon-photon fusion triggering the dilepton production in proton-proton collisions with rapidity gap in the main detector and one forward proton in the forward proton detectors. This correspond to the LHC measurements made by ATLAS+AFP and CMS+PPS. Transverse momenta of the intermediate photons and photon fluxes expressed by the form factors and structure functions are included. Moreover the influence of proton measurement and cuts on the ${\xi }_{1/2}$, $M_{ll}$, $Y_{ll}$, $p_{t,ll}$ distributions, cross section and gap survival factor are considered for both double-elastic and single-dissociative processes. The analyzes used the SuperChic generator to calculate the soft gap survival factor and to compare the results obtained with its use to the results obtained on the owned codes available. It is shown that the gap survival factor for the single dissociative mechanism is related to the emission of a (mini)jet into the main detector depending on the type of contribution. The dependence between this value and the invariant mass as well as the transverse momentum of the leptons pair and its rapidity was also found.

    hep-ph0 citations
13. 13*

    Flatland: abelian extensions of the Standard Model with semi-simple completions

    Joe Davighi🇨🇭 · Joseph Tooby-Smith🇺🇸

    We parametrise the space of all possible flavour non-universal $\mathfrak{u}(1{)}_X$ extensions of the Standard Model that embed inside anomaly-free semi-simple gauge theories, including up to three right-handed neutrinos. More generally, we parametrise all abelian extensions (i.e.) by any number of $\mathfrak{u}(1)$'s) of the SM with such semi-simple completions. The resulting space of abelian extensions is a collection of planes of dimensions $\le 6$. Numerically, we find that roughly $2.5\%$ of anomaly-free $\mathfrak{u}(1{)}_X$ extensions of the SM with a maximum charge ratio of $\pm 10$ can be embedded in such semi-simple gauge theories. Any vector-like anomaly-free abelian extension embeds (at least) inside $\mathfrak{g}=\mathfrak{su}(12)\oplus \mathfrak{su}(2{)}_L\oplus \mathfrak{su}(2{)}_R$. We also provide a simple computer program that tests whether a given $\mathfrak{u}(1{)}_{X^1}\oplus \mathfrak{u}(1{)}_{X^2}\oplus \dots$ charge assignment has a semi-simple completion and, if it does, outputs a set of maximal gauge algebras in which the $\mathfrak{sm}\oplus \mathfrak{u}(1{)}_{X^1}\oplus \mathfrak{u}(1{)}_{X^2}\oplus \dots$ model may be embedded. We hope this is a useful tool in pointing the way from $\mathfrak{sm}\oplus \mathfrak{u}(1{)}_{X^1}\oplus \mathfrak{u}(1{)}_{X^2}\oplus \dots$ models, which have many phenomenological uses, to their unified gauge completions in the ultraviolet.

    hep-phhep-thJHEP(2022)·8 citations
14. 14*

    Constrained second-order power corrections in HQET: $R(D^{(\ast )})$, $|V_{cb}|$, and new physics

    Florian U. Bernlochner🇩🇪 · Zoltan Ligeti🇺🇸 · Michele Papucci🇺🇸 · Markus T. Prim🇩🇪 · Dean J. Robinson🇺🇸 · Chenglu Xiong🇩🇪

    We postulate a supplemental power counting within the heavy quark effective theory, that results in a small, highly-constrained set of second-order power corrections, compared to the standard approach. We determine all $\bar{B}\to D^{(\ast )}$ form factors, both within and beyond the standard model to $\mathcal{O}({\alpha }_s/m_{c,b},1/m_{c,b}^2)$, under truncation by this power counting. We show that the second-order power corrections to the zero-recoil normalization of the $\bar{B}\to D^{(\ast )}l\nu$ matrix elements ($l=e$, $\mu$, $\tau$) are fully determined by hadron mass parameters, and are in good agreement with lattice QCD (LQCD) predictions. We develop a parametrization of these form factors under the postulated truncation, that achieves excellent fits to the available LQCD predictions and experimental data, and we provide precise updated predictions for the $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$ decay rates, lepton flavor universality violation ratios $R(D^{(\ast )})$, and the CKM matrix element $|V_{cb}|$. We point out some apparent errors in prior literature concerning the $\mathcal{O}(1/m_c{m}_b)$ corrections, and note a tension between commonly-used simplified dispersive bounds and current data.

    hep-phPRD(2022)·62 citations
15. 15*

    Interpreting LHCb's ${\Lambda }_b\to {\Lambda }_c\tau \bar{\nu }$ measurement and puzzles in semileptonic ${\Lambda }_b$ decays

    Florian U. Bernlochner🇩🇪 · Zoltan Ligeti🇺🇸 · Michele Papucci🇺🇸 · Dean J. Robinson🇺🇸

    Normalizing the recent LHCb measurement of ${\Lambda }_b\to {\Lambda }_c\tau \bar{\nu }$ to the standard model (SM) prediction for the ${\Lambda }_b\to {\Lambda }_c\mu \bar{\nu }$ rate, instead of a LEP measurement, provides a more consistent comparison with the SM prediction for the lepton flavor universality ratio $R({\Lambda }_c)$. This modestly increases $R({\Lambda }_c)$ compared to the quoted LHCb result, such that it no longer hints at a suppression compared to the SM, which would be hard to accommodate in new physics scenarios that enhance $R(D^{(\ast )})$. We point out that the fraction of excited states in inclusive semileptonic ${\Lambda }_b$ decay may be significantly greater than the corresponding fraction in $B$ decays. Possible implications are speculated upon.

    hep-phPRD(2023)·22 citations
16. 16*

    Implications for the $\Delta A_{FB}$ anomaly in ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}\bar{\nu }$ using a new Monte Carlo Event Generator

    Bhubanjyoti Bhattacharya🇺🇸 · Thomas E. Browder🇺🇸 · Quinn Campagna🇺🇸 · Alakabha Datta🇺🇸 · Shawn Dubey🇺🇸 · Lopamudra Mukherjee🇺🇸 · Alexei Sibidanov🇺🇸

    Recent experimental results in $B$ physics from Belle, BaBar and LHCb suggest new physics (NP) in the weak $b\to c$ charged-current and the $b\to s$ neutral-current processes. Here we focus on the charged-current case and specifically on the decay modes ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}\bar{\nu }$ with $\ell =e$ and $\mu$. The world averages of the ratios $R_D$ and $R_D^{\ast }$ currently differ from the Standard Model (SM) predictions by $3.4\sigma$ while recently a new anomaly has been observed in the forward-backward asymmetry measurement, $A_{FB}$, in ${\bar{B}}^0\to D^{\ast +}{\mu }^{-}\bar{\nu }$ decay. It is found that $\Delta A_{FB}=A_{FB}(B\to D^{\ast }\mu \nu )-A_{FB}(B\to D^{\ast }e\nu )$ is around $4.1\sigma$ away from the SM prediction in an analysis of 2019 Belle data. In this work we explore possible solutions to the $\Delta A_{FB}$ anomaly and point out correlated NP signals in other angular observables. These correlations between angular observables must be present in the case of beyond the Standard Model physics. We stress the importance of $\Delta$ type observables that are obtained by taking the difference of the observable for the muon and the electron mode. These quantities cancel form factor uncertainties in the SM and allow for clean tests of NP. These intriguing results also suggest an urgent need for improved simulation and analysis techniques in ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}\bar{\nu }$ decays. Here we also describe a new Monte Carlo Event-generator tool based on EVTGEN that we developed to allow simulation of the NP signatures in ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}\nu$, which arise due to the interference between the SM and NP amplitudes. We then discuss prospects for improved observables sensitive to NP couplings with 1, 5, 50, and 250 ab${}^{-1}$ of Belle II data, which seem to be ideally suited for this class of measurements.

    hep-phhep-exPRD(2023)·17 citations
17. 17*

    On the Hamiltonian of gravity theories whose action is linear in spacetime curvature

    Yuri Bonder🇲🇽

    A straightforward method to compute Hamilton's density for theories that are linear in the spacetime curvature is provided. It is shown that the lapse function and shift vector still give rise to primary constraints, while the induced metric gives rise to nontrivial evolution equations. The corresponding Hamilton's density can always be obtained, albeit in a formal sense.

    ↳ gr-qchep-ph2 citations
18. 18*

    Boltzmann or Bogoliubov? Approaches Compared in Gravitational Particle Production

    Kunio Kaneta🇯🇵 · Sung Mook Lee🇰🇷 · Kin-ya Oda🇯🇵

    Gravitational particle production is a minimal contribution to reheating the Universe after the end of inflation. To study this production channel, two different approaches have commonly been considered, one of which is based on the Boltzmann equation, and the other is based on the Bogoliubov transformation. Each of these has pros and cons in practice. The collision term in the Boltzmann equation can be computed based on quantum field theory in the Minkowski spacetime, and thus many techniques have been developed so far. On the other hand, the Bogoliubov approach may deal with the particle production beyond the perturbation theory and is able to take into account the effect of the curved spacetime, whereas in many cases one should rely on numerical methods, such as lattice computation. We show by explicit numerical and analytical computations of the purely gravitational production of a scalar that these two approaches give consistent results for particle production with large momenta during reheating, whereas the Boltzmann approach is not capable of computing particle production out of vacuum during inflation. We also provide analytic approximations of the spectrum of produced scalar with/without mass for the low momentum regime obtained from the Bogoliubov approach.

    ↳ astro-ph.COhep-phhep-thJCAP(2022)·58 citations
19. 19*

    Investigating Hadronic Interactions at Ultra-High Energies with the Pierre Auger Observatory

    Isabel Goos (on behalf of the Pierre Auger Collaboration): P. Abreu · M. Aglietta · J.M. Albury · I. Allekotte · K. Almeida Cheminant · A. Almela · J. Alvarez-Muñiz · R. Alves Batista · J. Ammerman Yebra · G.A. Anastasi · L. Anchordoqui · B. Andrada and 363 other authors

    The development of an extensive air shower depends not only on the nature of the primary ultra-high-energy cosmic ray but also on the properties of the hadronic interactions. For energies above those achievable in human-made accelerators, hadronic interactions are only accessible through the studies of extensive air showers, which can be measured at the Pierre Auger Observatory. With its hybrid detector design, the Pierre Auger Observatory measures both the longitudinal development of showers in the atmosphere and the lateral distribution of particles that arrive at the ground. This way, observables that are sensitive to hadronic interactions at ultra-high energies can be obtained. While the hadronic interaction cross-section can be assessed from the longitudinal profiles, the number of muons and their fluctuations measured with the ground detectors are linked to other physical properties. In addition to these direct studies, we discuss here how measurements of the atmospheric depth of the maximum of air-shower profiles and the characteristics of the muon signal at the ground can be used to test the self-consistency of the post-LHC hadronic models.

    ↳ astro-ph.HEhep-ph0 citations
20. 20*

    Lorentz symmetry breaking and supersymmetry

    J. R. Nascimento🇧🇷 · A. Yu. Petrov🇧🇷

    We discuss three manners to implement Lorentz symmetry breaking in a superfield theory formulated within the superfield formalism, that is, deformation of the supersymmetry algebra, introducing of an extra superfield whose components can depend on Lorentz-violating (LV) vectors (tensors), and adding of new terms proportional to LV vectors (tensors) to the superfield action. We illustrate these methodologies with examples of quantum calculations.

    ↳ hep-thhep-phProceedings of the Ninth Meeting on CPT a…·0 citations
21. 21*

    A Possible Solution to the Helium Anomaly of EMPRESS VIII by Cuscuton Gravity Theory

    Kazunori Kohri🇯🇵 · Kei-ichi Maeda🇯🇵

    We discuss cosmology based on the cuscuton gravity theory to resolve the anomaly of the observational ${}^4$He abundance reported by the EMPRESS collaboration. We find that the gravitational constant $G_{\cos }$ in Friedmann equation should be smaller than the Newton's constant $G_{\mathrm{N}}$ such that $\Delta G_{\mathrm{N}}/G_{\mathrm{N}}\equiv (G_{\cos }-G_{\mathrm{N}})/G_{\mathrm{N}}=-0.085_{-0.028}^{+0.026}(68\%\text{ C.L. })$ in terms of big-bang nucleosynthesis, which excludes $\Delta G_{\mathrm{N}}=0$ at more than 95~$\%\text{ C.L. }$ To fit the data, we obtain a negative mass squared of a non-dynamical scalar field with the Planck-mass scale as $\sim -\mathcal{O}(1)M_{\mathrm{PL}}^2(\mu /0.5M_{\mathrm{PL}}{)}^4$ with the cuscuton mass parameter $\mu$. This fact could suggest the need for modified gravity theories such as the cuscuton gravity theory with a quadratic potential, which can be regarded as the low-energy Hořava-Lifshitz gravity and might give a hint of quantum gravity.

    ↳ gr-qcastro-ph.COhep-phhep-thPTEP(2022)·13 citations
22. 22*

    A step in the right direction? Analyzing the Wess Zumino Dark Radiation solution to the Hubble tension

    Nils Schöneberg🇪🇸 · Guillermo Franco Abellán🇫🇷

    The Wess Zumino Dark Radiation (WZDR) model first proposed in arXiv:2111.00014 shows great promise as a well-motivated simple explanation of the Hubble tension between local and CMB-based measurements. In this work we investigate the assumptions made in the original proposal and confront the model with additional independent data sets. We show that the original assumptions can have an impact on the overall results but are usually well motivated. We further demonstrate that the preference for negative ${\Omega }_k$ remains at a similar level as for the $\Lambda$CDM model, while the $A_L$ tension is slightly increased. Furthermore, the tension between Planck data for $\ell <800$ and $\ell \ge 800$ is significantly reduced for the WZDR model. The independent data sets show slightly more permissive bounds on the Hubble parameter, allowing the tension to be further reduced to $2.1\sigma$ (CMB-independent) or $1.9\sigma$ (ACT+WMAP). However, no combination shows a large preference for the presence of WZDR. We also investigate whether additional dark radiation -- dark matter interactions can help in easing the $S_8$ tension as well. Assuming all of the dark matter to be interacting and a temperature-independent scattering rate, we find that the CMB data are too restrictive on this additional component as to allow a significant decrease in the clustering.

    ↳ astro-ph.COhep-phJCAP(2022)·54 citations
23. 23*

    Fractional topological charge in $SU(N)$ gauge theories without dynamical quarks

    V. P. Nair🇺🇸 · Robert D. Pisarski🇺🇸

    In $SU(N)$ gauge theories without dynamical quarks, we discuss how configurations with fractional topological charge, $\sim 1/N$, can arise in the vacuum and dominate in the confining phase. They are not solutions of the classical equations of motion, but arise as quantum solutions of the effective Lagrangian. Their size is essentially fixed, on the order of the confinement scale. We give both a general mathematical analysis and illustrative solutions. Their presence can be measured through numerical simulations on the lattice using known methods. As they carry ${\mathbb{Z}}_N$ magnetic charge, the introduction of dynamical quarks significantly complicates their dynamics.

    ↳ hep-thhep-lathep-phPRD(2023)·11 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.