Wed·Jun 2, 2021Wednesday·June 2, 2021

1. 01*

   Response to Comment on "Dark Matter Annihilation Can Produce a Detectable Antihelium Flux through ${\bar{\Lambda }}_b$ Decays"

   Martin Wolfgang Winkler🇸🇪 · Tim Linden🇸🇪

   In a recent paper we showed that the decay of intermediate ${\bar{\Lambda }}_b$ baryons can dramatically enhance the antihelium flux from dark matter annihilation. Our antihelium predictions were derived using several implementations of the Pythia and Herwig event generators which were calibrated to existing data on antideuteron and antihelium formation. Kachelriess et al. have argued for a smaller antihelium flux compared to our most optimistic Monte Carlo model. However, we show that the arguments by Kachelriess et al. are either incorrect or irrelevant for antihelium formation. Thus, the results of our original paper remain unchanged.

   hep-ph11 citations
2. 02*

   Axion model with the $\mathrm{SU}(6)$ unification

   Ning Chen🇨🇳 · Yutong Liu🇨🇳 · Zhaolong Teng🇨🇳

   We propose an $\mathrm{SU}(6)$ unified theory that solves the strong $CP$ problem with a high-quality axion. This is achieved by an automatic global Peccei-Quinn $\mathrm{U}(1{)}_{\mathrm{PQ}}$ symmetry and the gauged discrete ${\mathbb{Z}}_{4\mathcal{R}}$ symmetry. With the axion mass predictions of $m_a\sim \mathcal{O}(10^{-3})-\mathcal{O}(0.1)\mathrm{eV}$, as well as a universal axion-photon coupling in the unification models, the QCD axion can be probed in the upcoming experiments of IAXO. An intermediate gauge symmetry breaking scale characterized by the axion decay constant is obtained by the Peccei-Quinn quality argument, which is likely to achieve a successful leptogenesis through the type-I seesaw mechanism. The Higgs sector at the electroweak scale is a type-II two-Higgs-doublet model. The gauge coupling unification is possible with the supersymmetric extension.

   hep-phhep-thPRD(2021)·22 citations
3. 03*

   Reexamination of local spin polarization beyond global equilibrium in relativistic heavy ion collisions

   Cong Yi🇨🇳 · Shi Pu🇨🇳 · Di-Lun Yang🇹🇼

   We study local spin polarization in the relativistic hydrodynamic model. Generalizing the Wigner functions previously obtained from chiral kinetic theory by Y. Hidaka et al. [Phys. Rev. D 97, 016004 (2018)] to the massive case, we present the possible contributions up to the order of $\hslash$ from thermal vorticity, shear viscous tensor, other terms associated with the temperature and chemical-potential gradients, and electromagnetic fields to the local spin polarization. We then implement the (3+1)-dimensional viscous hydrodynamic model to study the spin polarizations from these sources with a small chemical potential and ignorance of electromagnetic fields by adopting an equation of state different from those in other recent studies. Although the shear correction alone upon the local polarization results in a sign and azimuthal-angle dependence more consistent with experimental observations, as also discovered in other recent studies, it is mostly suppressed by the contributions from thermal vorticity and other terms that yield an opposite trend. It is found that the total local spin polarization can be very sensitive to the equation of states, the ratio of shear viscosity to entropy density, and the freeze-out temperature.

   hep-phnucl-thPRC(2021)·119 citations
4. 04*

   Infrared Renormalons in Collider Processes

   Silvia Ferrario Ravasio🇬🇧

   Precise theoretical predictions are a key ingredient for an accurate determination of the structure of the Langrangian of particle physics, including its free parameters, which summarizes our understanding of the fundamental interactions among particles. Furthermore, due to the absence of clear new-physics signals, precise theoretical calculations are required in order to pin down possible subtle deviations from the Standard Model predictions. The error associated with such calculations must be scrutinized, as non-perturbative power corrections, dubbed infrared renormalons, can limit the ultimate precision of truncated perturbative expansions in quantum chromodynamics. In this review we focus on linear power corrections that can arise in certain kinematic distributions relevant for collider phenomenology where an operator product expansion is missing, e.g. those obtained from the top-quark decay products, shape observables and the transverse momentum of massive gauge bosons. Only the last one is found to be free from such corrections, while the mass of the system comprising the top decay products has a larger power correction if the perturbative expansion is expressed in terms of a short-distance mass instead of the pole mass. A proper modelization of non-perturbative corrections is crucial in the context of shape observables to obtain reliable strong coupling constant extractions.

   hep-phEur.Phys.J.ST(2021)·2 citations
5. 05*

   Decay of the vortex muon

   Pengcheng Zhao🇨🇳 · Igor P. Ivanov🇨🇳 · Pengming Zhang🇨🇳

   Muon decay is self-analyzing: the spectral-angular distribution of the emitted electron reveals the spin orientation of the polarized muon. Here, we show that the same feature applies to muons in non-plane-wave states and helps reveal the rich polarization opportunities available. We focus on the so-called vortex states, in which the muon carries a non-zero orbital angular momentum with respect to the average propagation direction and exhibits a cone structure in the momentum distribution. We compute the spectrum and the angular distribution of the electrons emitted in decays of vortex muons and show that the most revealing observable is not the angular distribution but the fixed-angle electron spectra. Even for very small cone opening angles of the vortex muons, it will be easy to observe significant modifications of the electron spectra which would allow one to distinguish vortex muons from approximately plane wave muons, as well as to differentiate among various polarization states. These features will be the key to tracking the evolution of vortex muons in external magnetic fields.

   hep-phquant-phPRD(2021)·15 citations
6. 06*

   Dark matter in a charged variant of the Scotogenic model

   Valentina De Romeri🇪🇸 · Miguel Puerta🇪🇸 · Avelino Vicente🇪🇸

   Scotogenic models are among the most popular possibilities to link dark matter and neutrino masses. In this work we discuss a variant of the Scotogenic model that includes charged fermions and a doublet with hypercharge $3/2$. Neutrino masses are induced at the one-loop level thanks to the states belonging to the dark sector. However, in contrast to the standard Scotogenic model, only the scalar dark matter candidate is viable in this version. After presenting the model and explaining some particularities about neutrino mass generation, we concentrate on its dark matter phenomenology. We show that the observed dark matter relic density can be correctly reproduced in the usual parameter space regions found for the standard Scotogenic model or the Inert Doublet model. In addition, the presence of the charged fermions may open up new regions, provided some tuning of the parameters is allowed.

   hep-phEPJC(2022)·19 citations
7. 07*

   Search for lepton-flavor-violating ALPs at a future muon collider and utilization of polarization-induced effects

   Gholamhossein Haghighat🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

   Axion-Like Particles (ALPs) are pseudo Nambu-Goldstone bosons associated with spontaneously broken global $U(1)$ symmetries. Such particles can have lepton-flavor-violating (LFV) couplings to the SM charged leptons. LFV ALPs provide the possibility to address some of the SM long-lasting problems. We investigate the sensitivity of a future muon collider suggested by the Muon Accelerator Program (MAP) to the production of LFV ALPs in the ALP mass range $m_a\le 1$ MeV. ALPs are assumed to be produced through the LFV decay $\tau \text{ra}\ell a$ ($\ell =e,\mu$) of one of the tau leptons produced in the muon-anti muon annihilation. Performing a realistic detector simulation and deploying a multivariate technique, we constrain the LFV couplings $c_{\tau e}$ and $c_{\tau \mu }$ for both the cases of unpolarized and polarized muon beams. Three different chiral structures are considered for the LFV ALP coupling and the muon collider is assumed to operate at the center-of-mass energies of 126, 350 and 1500 GeV. We present a procedure to search for LFV ALPs at colliders which takes advantage of tau polarization-induced effects. Polarized tau leptons which produce such effects can be produced when the initial muon beams are polarized. Utilizing the properties of polarized tau decays, the main SM background which overwhelms the ALP production in the case of unpolarized muon beams can be significantly suppressed. We present 95$\%$ CL expected limits on the LFV couplings and show that the present analysis can improve current experimental limits on the ALP LFV couplings by roughly one order of magnitude.

   hep-phNPB(2022)·29 citations
8. 08*

   ALP-portal majorana dark matter

   Shivam Gola🇮🇳 · Sanjoy Mandal🇪🇸 · Nita Sinha🇮🇳

   Axion like particles(ALPs) and right handed neutrinos~(RHNs) are two well-motivated dark matter(DM) candidates. However, these two particles have a completely different origin. Axion was proposed to solve the Strong CP problem, whereas RHNs were introduced to explain light neutrino masses through seesaw mechanisms. We study the case of ALP portal RHN DM taking into account existing constraints on ALPs. We consider the leading effective operators mediating interactions between the ALP and SM particles and three RHNs to generate light neutrino masses through type-I seesaw. Further, ALP-RHN neutrino coupling is introduced to generalize the model which is restricted by the relic density and indirect detection constraint.

   hep-phInt.J.Mod.Phys.A(2022)·26 citations
9. 09*

   A survey of machine learning-based physics event generation

   Yasir Alanazi🇺🇸 · N. Sato🇺🇸 · Pawel Ambrozewicz🇺🇸 · Astrid N. Hiller Blin🇺🇸 · W. Melnitchouk🇺🇸 · Marco Battaglieri🇺🇸 · Tianbo Liu🇨🇳 · Yaohang Li🇺🇸

   Event generators in high-energy nuclear and particle physics play an important role in facilitating studies of particle reactions. We survey the state-of-the-art of machine learning (ML) efforts at building physics event generators. We review ML generative models used in ML-based event generators and their specific challenges, and discuss various approaches of incorporating physics into the ML model designs to overcome these challenges. Finally, we explore some open questions related to super-resolution, fidelity, and extrapolation for physics event generation based on ML technology.

   hep-phcs.LGnucl-exProceedings of the 30th International Joi…·20 citations
10. 10*

    The KATRIN neutrino mass results: An alternative interpretation

    Robert Ehrlich🇺🇸

    The KATRIN experiment has recently reported a new upper limit to the mass of the electron neutrino of $m<0.8eV$ (90\%CL), and a best value of $m^2=0.26\pm 0.34e{V}^2/c^4$ based on a fit to the observed tritium beta decay spectrum. Here another interpretation of their results is discussed.

    hep-ph1 citation
11. 11*

    The proton radius (puzzle?) and its relatives

    Clara Peset🇩🇪 · Antonio Pineda🇪🇸 · Oleksandr Tomalak🇺🇸

    We review determinations of the electric proton charge radius from a diverse set of low-energy observables. We explore under which conditions it can be related to Wilson coefficients of appropriate effective field theories. This discussion is generalized to other low-energy constants. This provides us with a unified framework to deal with a set of low-energy constants of the proton associated with its electromagnetic interactions. Unambiguous definitions of these objects are given, as well as their relation with expectation values of QCD operators. We show that the proton radius obtained from spectroscopy and lepton-proton scattering (when both the lepton and proton move with nonrelativistic velocities) is related to the same object of the underlying field theory with $\mathcal{O}(\alpha )$ precision. The model dependence of these analyses is discussed. The prospects of constructing effective field theories valid for the kinematic configuration of present, or near-future, lepton-proton scattering experiments are discussed.

    hep-phnucl-thphysics.atom-phPPNP(2021)·33 citations
12. 12*

    Upper limits on branching ratios of the lepton-flavor-violating decays $\tau \to \ell \gamma \gamma$ and $\tau \to \ell X$

    Douglas A. Bryman🇨🇦 · Shintaro Ito🇯🇵 · Robert Shrock🇺🇸

    From analysis of data produced by the BABAR experiment, the first upper bounds (90% C.L.) were obtained on the branching ratios $Br(\tau \to e\gamma \gamma )<2.5\times 10^{-4}$ and $Br(\tau \to \mu \gamma \gamma )<5.8\times 10^{-4}$. In addition, improved upper bounds (95% C.L.) were found on branching ratios $Br(\tau \to eX)<1.4\times 10^{-3}$ and $Br(\tau \to \mu X)<2.0\times 10^{-3}$, where $X$ is an undetected weakly interacting boson with mass $m_X<1.6$ GeV/$c^2$.

    hep-phhep-exPRD(2021)·19 citations
13. 13*

    Primordial black holes from a cosmic phase transition: The collapse of Fermi-balls

    Kiyoharu Kawana🇰🇷 · Ke-Pan Xie🇰🇷

    We propose a novel primordial black hole (PBH) formation mechanism based on a first-order phase transition (FOPT). If a fermion species gains a huge mass in the true vacuum, the corresponding particles get trapped in the false vacuum as they do not have sufficient energy to penetrate the bubble wall. After the FOPT, the fermions are compressed into the false vacuum remnants to form non-topological solitons called Fermi-balls, and then collapse to PBHs due to the Yukawa attractive force. We derive the PBH mass and abundance, showing that for a $\mathcal{O}(\mathrm{GeV})$ FOPT the PBHs could be $\sim 10^{17}$ g and explain all of dark matter. If the FOPT happens at higher scale, PBHs are typically overproduced and extra dilution mechanism is necessary to satisfy current constraints.

    ↳ astro-ph.COhep-phPLB(2022)·182 citations
14. 14*

    Implication of the swampland distance conjecture on the Cohen-Kaplan-Nelson bound in de Sitter space

    Min-Seok Seo🇰🇷

    The Cohen-Kaplan-Nelson (CKN) bound formulates the condition that black hole is not produced by the low energy effective field theory dynamics. In de Sitter space it also constrains the maximal size of the matter distribution to be smaller than the cosmological horizon determined by black hole. On the other hand, the swampland distance conjecture (SDC) predicts that de Sitter space becomes unstable by the descent of the low energy degrees of freedom from UV. This results in the rapid increase in the energy inside the cosmological horizon, the distribution of which can be constrained by the CKN bound. We study the CKN bound in de Sitter space in detail and point out that when compared with the slow-roll in the inflation, the bound on the slow-roll parameter which forbids the eternal inflation is obtained.

    ↳ hep-thastro-ph.COgr-qchep-phEPJC(2022)·11 citations
15. 15*

    Millisecond Pulsars from Accretion Induced Collapse as the Origin of the Galactic Centre Gamma-ray Excess Signal

    Anuj Gautam🇦🇺 · Roland M. Crocker🇦🇺 · Lilia Ferrario🇦🇺 · Ashley J. Ruiter🇦🇺 · Harrison Ploeg🇳🇿 · Chris Gordon🇳🇿 · Oscar Macias🇯🇵

    Gamma-ray data from the Fermi-Large Area Telescope reveal an unexplained, apparently diffuse, signal from the Galactic bulge that peaks near 2 GeV with an approximately spherical intensity profile $\propto r^{-2.4}$ that extends to angular radial scales of at least 10 degrees, possibly to 20 degrees. The origin of this "Galactic Centre Excess" (GCE) has been debated with proposed sources prominently including self-annihilating dark matter and a hitherto undetected population of millisecond pulsars (MSPs). However, the conventional channel for the generation of MSPs has been found to predict too many low mass X-ray binary (LMXB) systems and, because of the expected large natal kicks, may not accommodate the close spatial correspondence between the GCE signal and stars in the bulge. Here we report a binary population synthesis forward model that demonstrates that an MSP population arising from the accretion induced collapse (AIC) of O-Ne white dwarfs in Galactic bulge binaries can naturally reproduce the morphology, spectral shape, and intensity of the GCE signal while also obeying LMXB constraints. Synchrotron emission from MSP-launched cosmic ray electrons and positrons may simultaneously explain the mysterious, microwave "haze" from the inner Galaxy

    ↳ astro-ph.HEhep-phNature Astron.(2022)·77 citations
16. 16*

    Medium effects in antikaon-induced ${\Xi }^{-}$ hyperon production on nuclei near threshold

    E. Ya. Paryev🇷🇺

    We study the antikaon-induced inclusive cascade ${\Xi }^{-}$ hyperon production from ${}^{12}$C and ${}^{184}$W target nuclei near threshold within a nuclear spectral function approach. The approach describes incoherent direct ${\Xi }^{-}$ hyperon production in elementary $K^{-}p\to K^{+}{\Xi }^{-}$ and $K^{-}n\to K^0{\Xi }^{-}$ processes as well as takes into account the influence of the scalar nuclear $K^{-}$, $K^{+}$, $K^0$, ${\Xi }^{-}$ and their Coulomb potentials on these processes. We calculate the absolute differential and total cross sections for the production of ${\Xi }^{-}$ hyperons off these nuclei at laboratory angles $\le$ 45${}^{\circ }$ by $K^{-}$ mesons with momenta of 1.0 and 1.3 GeV/c, which are close to the threshold momentum (1.05 GeV/c) for ${\Xi }^{-}$ hyperon production on the free target nucleon at rest. We also calculate the momentum dependence of the transparency ratio for the ${}^{184}$W/${}^{12}$C combination for ${\Xi }^{-}$ hyperons at these $K^{-}$ beam momenta. We show that the ${\Xi }^{-}$ differential and total (absolute and relative) production cross sections at the considered initial momenta reveal a distinct sensitivity to the variations in the scalar ${\Xi }^{-}$ nuclear potential at saturation density ${\rho }_0$, studied in the paper, in the low-momentum region of 0.1--0.6 GeV/c. We also demonstrate that for the subthreshold $K^{-}$ meson momentum of 1.0 GeV/c there is a strong sensitivity of the transparency ratio for ${\Xi }^{-}$ hyperons to the considered changes in the ${\Xi }^{-}$ nuclear potential at all outgoing ${\Xi }^{-}$ momenta as well. Therefore, the measurement of these absolute and relative observables in a dedicated experiment at the J-PARC will provide valuable information on the ${\Xi }^{-}$ in-medium properties, which will be complementary to that deduced from the study of the inclusive ($K^{-}$,$K^{+}$) reactions at incident momenta of 1.6--1.8 GeV/c in the ${\Xi }^{-}$ bound and quasi-free regions.

    ↳ nucl-thhep-phnucl-exNPA(2021)·3 citations
17. 17*

    SU(N) gauge theories in 3+1 dimensions: glueball spectrum, string tensions and topology

    Andreas Athenodorou🇨🇾 · Michael Teper🇬🇧

    We calculate the low-lying glueball spectrum, some string tensions and some properties of topology and the running coupling for SU(N) lattice gauge theories in 3+1 dimensions. We do so for N = 2,3,...12, using lattice simulations with the Wilson plaquette action, and for glueball states in all the representations of the cubic rotation group, for both values of parity and charge conjugation. We extrapolate these results to the continuum limit of each theory and then to N=infinity. For a number of these states we are able to identify their continuum spins with very little ambiguity. We calculate the fundamental string tension and k=2 string tension and investigate the N dependence of the ratio. Using the string tension as the scale, we calculate the running of a lattice coupling and confirm that g(a)**2 varies as 1/N for constant physics as N->oo. We fit our calculated values of the string tension with the 3-loop beta-function, and extract a value for Lambda-MSbar, in units of the string tension, for all our values of N, including SU(3). We calculate the topological charge Q for N=2,..,6 where it fluctuates sufficiently for a plausible estimate of the continuum topological susceptibility. We also calculate the renormalisation of the lattice topological charge, ZQ(beta), for all our SU(N) gauge theories, using a standard definition of the charge, and we provide interpolating formulae, which may be useful in estimating the renormalisation of the lattice theta parameter. We provide quantitative results for how the topological charge `freezes' with decreasing lattice spacing and with increasing N, and show how we cicumvent this issue in our calculations.

    ↳ hep-lathep-phhep-thJHEP(2021)·117 citations
18. 18*

    On the consistency of (partially-)massless matter couplings in de Sitter space

    Charlotte Sleight🇬🇧 · Massimo Taronna🇮🇹

    We study the consistency of the cubic couplings of a (partially-)massless spinning field to two scalars in $\left(d+1\right)$-dimensional de Sitter space. Gauge invariance of observables with external (partially)-massless spinning fields translates into Ward-Takahashi identities on the boundary. Using the Mellin-Barnes representation for boundary correlators in momentum space, we give a systematic study of Ward-Takahashi identities for tree-level 3- and 4-point processes involving a single external (partially-)massless field of arbitrary integer spin-$J$. 3-point Ward-Takahashi identities constrain the mass of the scalar fields to which a (partially-)massless spin-$J$ field can couple. 4-point Ward-Takahashi identities then constrain the corresponding cubic couplings. For massless spinning fields, we show that Weinberg's flat space results carry over to $\left(d+1\right)$-dimensional de Sitter space: For spins $J=1,2$ gauge-invariance implies charge-conservation and the equivalence principle while, assuming locality, higher-spins $J>2$ cannot couple consistently to scalar matter. This result also applies to anti-de Sitter space. For partially-massless fields, restricting for simplicity to those of depth-2, we show that there is no consistent coupling to scalar matter in local theories. Along the way we give a detailed account of how contact amplitudes with and without derivatives are represented in the Mellin-Barnes representation. Various new explicit expressions for 3- and 4-point functions involving (partially-)massless fields and conformally coupled scalars in dS${}_4$ are given.

    ↳ hep-thgr-qchep-phJHEP(2021)·62 citations
19. 19*

    Machine Learning improved fits of the sound horizon at the baryon drag epoch

    Andoni Aizpuru🇪🇸 · Rubén Arjona🇪🇸 · Savvas Nesseris🇪🇸

    The baryon acoustic oscillations (BAO) have proven to be an invaluable tool in constraining the expansion history of the Universe at late times and are characterized by the comoving sound horizon at the baryon drag epoch $r_{\mathrm{s}}(z_{\mathrm{d}})$. The latter quantity can be calculated either numerically using recombination codes or via fitting functions, such as the one by Eisenstein and Hu (EH), made via grids of parameters of the recombination history. Here we quantify the accuracy of these expressions and show that they can strongly bias the derived constraints on the cosmological parameters using BAO data. Then, using a machine learning approach, called the genetic algorithms, we proceed to derive new analytic expressions for $r_{\mathrm{s}}(z_{\mathrm{d}})$ which are accurate at the $\sim 0.003\%$ level in a range of $10\sigma$ around the Planck 2018 best-fit or $\sim 0.018\%$ in a much broader range, compared to $\sim 2-4\%$ for the EH expression, thus obtaining an improvement of two to three orders of magnitude. Moreover, we also provide fits that include the effects of massive neutrinos and an extension to the concordance cosmological model assuming variations of the fine structure constant. Finally, we note that our expressions can be used to ease the computational cost required to compute $r_{\mathrm{s}}(z_{\mathrm{d}})$ with a Boltzmann code when deriving cosmological constraints using BAO data from current and upcoming surveys.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·49 citations
20. 20*

    Space-average electromagnetic fields and EM anomaly weighted by energy density in heavy-ion collisions

    Irfan Siddique🇨🇳 · Xin-Li Sheng🇨🇳 · Qun Wang🇨🇳

    We study the space-average electromagnetic (EM) fields weighted by the energy density in the central regions of heavy ion collisions. These average quantities can serve as a barometer for the magnetic-field induced effects such as the magnetic effect, the chiral separation effect and the chiral magnetic wave. Comparing with the magnetic fields at the geometric center of the collision, the space-average fields weighted by the energy density are smaller in the early stage but damp slower in the later stage. The space average of squared fields as well as the EM anomaly $\mathbf{E}\cdot \mathbf{B}$ weighted by the energy density are also calculated. We give parameterized analytical formula for these average quantities as functions of time by fitting numerical results for collisions in the collision energy range $7.7-200$ GeV with different impact parameters.

    ↳ nucl-thhep-phnucl-exPRC(2021)·22 citations
21. 21*

    Search for a Higgs portal scalar decaying to electron-positron pairs in the MicroBooNE detector

    MicroBooNE collaboration: P. Abratenko🇺🇸 · R. An🇺🇸 · J. Anthony🇬🇧 · J. Asaadi🇺🇸 · A. Ashkenazi🇺🇸 · S. Balasubramanian🇺🇸 · B. Baller🇺🇸 · C. Barnes🇺🇸 · G. Barr🇬🇧 · V. Basque🇬🇧 · L. Bathe-Peters🇺🇸 · O. Benevides Rodrigues🇺🇸 and 171 other authors

    We present a search for the decays of a neutral scalar boson produced by kaons decaying at rest, in the context of the Higgs portal model, using the MicroBooNE detector. We analyze data triggered in time with the Fermilab NuMI neutrino beam spill, with an exposure of $1.93\times 10^{20}$ protons on target. We look for monoenergetic scalars that come from the direction of the NuMI hadron absorber, at a distance of 100 m from the detector, and decay to electron-positron pairs. We observe one candidate event, with a Standard Model background prediction of $1.9\pm 0.8$. We set an upper limit on the scalar-Higgs mixing angle of $\theta <(3.3-4.6)\times 10^{-4}$ at the 95% confidence level for scalar boson masses in the range $(100-200)$ MeV$/c^2$. We exclude at the 95% confidence level the remaining model parameters required to explain the central value of a possible excess of $K_L^0\to {\pi }^0\nu \bar{\nu }$ decays reported by the KOTO collaboration. We also provide a model-independent limit on a new boson $X$ produced in $K\to \pi X$ decays and decaying to $e^{+}{e}^{-}$.

    ↳ hep-exhep-phPRL(2021)·87 citations
22. 22*

    Proposal for the ILC Preparatory Laboratory (Pre-lab)

    International Linear Collider International Development Team

    During the preparatory phase of the International Linear Collider (ILC) project, all technical development and engineering design needed for the start of ILC construction must be completed, in parallel with intergovernmental discussion of governance and sharing of responsibilities and cost. The ILC Preparatory Laboratory (Pre-lab) is conceived to execute the technical and engineering work and to assist the intergovernmental discussion by providing relevant information upon request. It will be based on a worldwide partnership among laboratories with a headquarters hosted in Japan. This proposal, prepared by the ILC International Development Team and endorsed by the International Committee for Future Accelerators, describes an organisational framework and work plan for the Pre-lab. Elaboration, modification and adjustment should be introduced for its implementation, in order to incorporate requirements arising from the physics community, laboratories, and governmental authorities interested in the ILC.

    ↳ physics.acc-phhep-exhep-phnucl-ex11 citations
23. 23*

    CMB anisotropies and linear matter power spectrum in models with non-thermal neutrinos and primordial magnetic fields

    Kerstin E. Kunze🇪🇸

    Angular power spectra of temperature anisotropies and polarization of the cosmic microwave background (CMB) as well as the linear matter power spectra are calculated for models with three light neutrinos with non-thermal phase-space distributions in the presence of a primordial stochastic magnetic field. The non-thermal phase-space distribution function is assumed to be the sum of a Fermi-Dirac and a gaussian distribution. It is found that the known effective description of the non-thermal model in terms of a twin thermal model with extra relativistic degrees of freedom can also be extended to models including a stochastic magnetic field. Numerical solutions are obtained for a range of magnetic field parameters.

    ↳ astro-ph.COhep-phJCAP(2021)·8 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.