Mon·Apr 12, 2021Monday·April 12, 2021

1. 01*

   Flavour mixing transport theory and resonant leptogenesis

   Henri Jukkala🇫🇮 · Kimmo Kainulainen🇫🇮 · Pyry M. Rahkila🇫🇮

   We derive non-equilibrium quantum transport equations for flavour-mixing fermions. We develop the formalism mostly in the context of resonant leptogenesis with two mixing Majorana fermions and one lepton flavour, but our master equations are valid more generally in homogeneous and isotropic systems. We give a hierarchy of quantum kinetic equations, valid at different approximations, that can accommodate helicity and arbitrary mass differences. In the mass-degenerate limit the equations take the familiar form of density matrix equations. We also derive the semiclassical Boltzmann limit of our equations, including the CP-violating source, whose regulator corresponds to the flavour coherence damping rate. Boltzmann equations are accurate and insensitive to the particular form of the regulator in the weakly resonant case $\Delta m\gg \Gamma$, but for $\Delta m\lesssim \Gamma$ they are qualitatively correct at best, and their accuracy crucially depends on the form of the CP-violating source.

   hep-phastro-ph.COhep-thJHEP(2021)·27 citations
2. 02*

   Fermion mass and width in QED in a magnetic field

   Alejandro Ayala🇲🇽 · Jorge David Castaño-Yepes🇲🇽 · M. Loewe🇨🇱 · Enrique Muñoz🇨🇱

   We revisit the calculation of the fermion self-energy in QED in the presence of a magnetic field. We show that, after carrying out the renormalization procedure and identifying the most general perturbative tensor structure for the modified fermion {mass operator} in the large field limit, the mass develops an imaginary part. This happens when account is made of the sub-leading contributions associated to Landau levels other than the lowest one. The imaginary part is associated to a spectral density describing the spread of the mass function in momentum. The center of the distribution corresponds to the magnetic-field modified mass. The width becomes small as the field intensity increases in such a way that for asymptotically large values of the field, when the separation between Landau levels becomes also large, the mass function describes a stable particle occupying only the lowest Landau level. For large but finite values of the magnetic field, the spectral density represents a finite probability for the fermion to occupy Landau levels other than the LLL.

   hep-phPRD(2021)·16 citations
3. 03*

   Mapping out the Space for New Physics with Leptonic and Semileptonic $B_{(c)}$ Decays

   Robert Fleischer🇳🇱 · Ruben Jaarsma🇳🇱 · Gilberto Tetlalmatzi-Xolocotzi🇩🇪

   Decays of $B$ mesons with leptons in the final state offer an interesting laboratory to search for possible effects of physics from beyond the Standard Model. In view of puzzling patterns in experimental data, the violation of lepton flavour universality is an interesting option. We present a strategy, utilising ratios of leptonic and semileptonic $B$ decays, where the elements $|V_{ub}|$ and $|V_{cb}|$ of the Cabibbo--Kobayashi--Maskawa (CKM) matrix cancel, to constrain the short-distance coefficients of (pseudo)-scalar, vector and tensor operator contributions. The individual branching ratios allow us then to extract also the CKM matrix elements, even in the presence of new-physics contributions. Bounds on unmeasured leptonic and semileptonic decays offer important additional constraints. In our comprehensive analysis, we give also predictions for decays which have not yet been measured in a variety of scenarios.

   hep-phhep-exEPJC(2021)·24 citations
4. 04*

   Fast flavor instabilities and the search for neutrino angular crossings

   Lucas Johns🇺🇸 · Hiroki Nagakura🇺🇸

   With the recognition that fast flavor instabilities likely affect supernova and neutron-star-merger neutrinos, using simulation data to pin down when and where the instabilities occur has become a high priority. The effort faces an interesting problem. Fast instabilities are related to neutrino angular crossings, but simulations often employ moment methods, sacrificing momentum-space angular resolution in order to allocate resources elsewhere. How can limited angular information be used most productively? The main aims here are to sharpen this question and examine some of the available answers. A recently proposed method of searching for angular crossings is scrutinized, the limitations of moment closures are highlighted, and two ways of reconstructing angular distributions solely from the flux factors (based respectively on maximum-entropy and sharp-decoupling assumptions) are compared. In (semi)transparent regions, the standard closure prescriptions likely miss some crossings that should be there and introduce others that should not.

   hep-phastro-ph.HEPRD(2021)·50 citations
5. 05*

   Modeling (anti)deuteron formation at RHIC with a geometric coalescence model

   Apiwit Kittiratpattana🇹🇭 · Michael Florian Wondrak🇩🇪 · Medina Hamzic🇧🇦 · Marcus Bleicher🇩🇪 · Ayut Limphirat🇹🇭 · Christoph Herold🇹🇭

   We study (anti)deuteron formation rates in heavy-ion collisions in the framework of a wave-function based coalescence model. The main feature of our model is that nucleons are emitted from the whole spherically symmetric fireball volume, while antinucleons are emitted only from a spherical shell close to the surface. In this way, the model accounts for nucleon-antinucleon annihilations in the center of the reaction at lower beam energies. Comparison with experimental data on the coalescence parameter in the range $\sqrt{s_{NN}}=4.7-200$ GeV allows us to extract radii of the respective source geometries. Our results are qualitatively supported by data from the UrQMD transport model which shows a comparable trend in the geometric radii as a function of beam energy. In line with our expectations, we find that at lower energies, the central region of the fireball experiences stronger annihilation than at higher energies.

   hep-phnucl-thPhys.Scripta(2021)·3 citations
6. 06*

   The gravitational form factor D(t) of the electron

   Andreas Metz🇺🇸 · Barbara Pasquini🇮🇹 · Simone Rodini🇮🇹

   The electron-graviton interaction can be described in terms of the gravitational form factors of the QED energy momentum tensor. Here we focus on the form factor D(t), and we examine its properties and its interpretation in terms of internal forces at one-loop accuracy in QED. We perform the calculation by keeping separate the contributions due to the electron and the photon parts of the energy momentum tensor. We also study the case of a nonzero photon mass. Furthermore, we discuss similarities with and differences to the form factor D(t) of hadronic bound states.

   hep-phhep-thPLB(2021)·30 citations
7. 07*

   Probing the CP structure of the top quark Yukawa coupling: Loop sensitivity vs. on-shell sensitivity

   Till Martini🇩🇪 · Ren-Qi Pan🇨🇳 · Markus Schulze🇩🇪 · Meng Xiao🇨🇳

   The question whether the Higgs boson is connected to additional CP violation is one of the driving forces behind precision studies at the Large Hadron Collider. In this work, we investigate the CP structure of the top quark Yukawa interaction-one of the most prominent places for searching for New Physics-through Higgs boson loops in top quark pair production. We calculate the electroweak corrections including arbitrary CP mixtures at next-to-leading-order in the Standard Model Effective Field Theory. This approach of probing Higgs boson degrees of freedom relies on the large $t\bar{t}$ cross section and the excellent perturbative control. In addition, we consider all direct probes with on-shell Higgs boson production in association with a single top quark or top quark pair. This allows us to contrast loop sensitivity versus on-shell sensitivity in these fundamentally different process dynamics. We find that loop sensitivity in $t\bar{t}$ production and on-shell sensitivity in $t\bar{t}H$ and $tH$ provide complementary handles over a wide range of parameter space.

   hep-phhep-exPRD(2021)·44 citations
8. 08*

   Probing non-unitary neutrino mixing via long-baseline neutrino oscillation experiments based at J-PARC

   C Soumya🇮🇳

   This paper investigates the capability of long-baseline experiments, which are making use of neutrinos that are coming from Japan Proton Accelerator Research Complex (J-PARC), in establishing the unitarity of active-neutrino mixing by ruling out the non-unitary mixing scheme as a function of true values of CP-violating phase ${\delta }_{\mathrm{CP}}$. It is found that T2HK can establish unitarity of active neutrino mixing at above 2$\sigma$ C.L. irrespective of neutrino mass hierarchy and true value of ${\delta }_{CP}$, if non-unitary (NU) parameter ${\alpha }_{21}$ is of the order of $10^{-2}$. Further, this paper is also discuss the bound on NU parameter in 21 sector and sensitivity limit of these experiments in determining NU parameter. It is found that the bounds on $\left({\alpha }_{21}/2\right)$ are 0.028, 0.0026, 0.005 at 2$\sigma$ C.L. respectively for T2K, T2HK, and T2HKK. Moreover, it is also found that the sensitivity limit of T2HK on NU parameter is far better than that of both T2HKK and T2K.

   hep-phPRD(2022)·10 citations
9. 09*

   Gravitino Dark matter, Non Thermal Leptogenesis and Low reheating temperature in No-scale Higgs Inflation

   Waqas Ahmed🇨🇳 · Athanasios Karozas🇬🇷 · George K. Leontaris🇬🇷

   We revisit Higgs inflation in the framework of a minimal extension of the Standard Model gauge symmetry by a $U(1{)}_{B-L}$ factor. Various aspects are taken into account with particular focus on the role of the supersymmetry breaking (SUSY) scale and the cosmological constraints associated with the gravitino. The scalar potential of the model is considered in the context of no-scale supergravity consisting of the F-part constructed from the Kähler function, the D-terms and soft SUSY contributions. We investigate several limiting cases and by varying the SUSY scale from a few TeV up to intermediate energies, for a spectral index around $n_s\sim 0.9655$ and reheating temperature $T_r\le 10^9$ GeV we find that the value of the tensor-to-scalar ratio ranges from $r\approx 10^{-3}$ to $10^{-2}$. Furthermore, it is shown that for certain regions of the parameter space the gravitino can live sufficiently long and as such is a potential candidate for a dark matter component. In general, the inflationary scenario is naturally implemented and it is consistent with non-thermal leptogenesis whereas the dominant decay channel of the inflaton yields right-handed neutrinos. Other aspects of cosmology and particle physics phenomenology are briefly discussed. Finally, we investigate the case where the inflaton is initially relaxed in a false minimum and estimate its probability to decay to the true vacuum.

   hep-phgr-qcPRD(2021)·13 citations
10. 10*

    Right Handed Neutrinos, TeV Scale BSM Neutral Higgs and FIMP Dark Matter in EFT Framework

    Geneviève Bélanger🇫🇷 · Sarif Khan🇩🇪 · Rojalin Padhan🇮🇳 · Manimala Mitra🇮🇳 · Sujay Shil🇮🇳

    We consider an effective field theory framework with three standard model (SM) gauge singlet right handed neutrinos, and an additional SM gauge singlet scalar field. The framework successfully generates eV masses of the light neutrinos via seesaw mechanism, and accommodates a feebly interacting massive particle (FIMP) as dark matter candidate. Two of the gauge singlet neutrinos participate in neutrino mass generation, while the third gauge singlet neutrino is a FIMP dark matter. We explore the correlation between the $\text{vev}$ of the gauge singlet scalar field which translates as mass of the BSM Higgs, and the mass of dark matter, which arises due to relic density constraint. We furthermore explore the constraints from the light neutrino masses in this set-up. We chose the gauge singlet BSM Higgs in this framework in the TeV scale. We perform a detailed collider analysis to analyse the discovery prospect of the TeV scale BSM Higgs through its di-fatjet signature, at a future $pp$ collider which can operate with $\sqrt{s}=100$ TeV c.m.energy.

    hep-phPRD(2021)·15 citations
11. 11*

    On the perturbative expansion at high temperature and implications for cosmological phase transitions

    Oliver Gould🇬🇧 · Tuomas V. I. Tenkanen🇸🇪

    We revisit the perturbative expansion at high temperature and investigate its convergence by inspecting the renormalisation scale dependence of the effective potential. Although at zero temperature the renormalisation group improved effective potential is scale independent at one-loop, we show how this breaks down at high temperature, due to the misalignment of loop and coupling expansions. Following this, we show how one can recover renormalisation scale independence at high temperature, and that it requires computations at two-loop order. We demonstrate how this resolves some of the huge theoretical uncertainties in the gravitational wave signal of first-order phase transitions, though uncertainties remain stemming from the computation of the bubble nucleation rate.

    hep-phastro-ph.COgr-qchep-thJHEP(2021)·140 citations
12. 12*

    What does a 4.2$\sigma$ discrepancy mean? A brief remark on the statistics of the Muon g-2 Experiment

    Oliver Passon🇩🇪

    On April 7, 2001 the Muon g-2 Experiment at Fermilab presented its first results which lead to a 4.2$\sigma$ discrepancy between the world average of the muon anomalous magnetic dipole moment and the standard model prediction of this quantity. I take issue with the statistical meaning of this finding.

    hep-ph1 citation
13. 13*

    Direct detection of non-galactic light dark matter

    Gonzalo Herrera🇩🇪 · Alejandro Ibarra🇩🇪

    A fraction of the dark matter in the solar neighborhood might be composed of non-galactic particles with speeds larger than the escape velocity of the Milky Way. The non-galactic dark matter flux would enhance the sensitivity of direct detection experiments, due to the larger momentum transfer to the target. In this note, we calculate the impact of the dark matter flux from the Local Group and the Virgo Supercluster diffuse components in nuclear and electron recoil experiments. The enhancement in the signal rate can be very significant, especially for experiments searching for dark matter induced electron recoils.

    hep-phastro-ph.COhep-exhep-thPLB(2021)·36 citations
14. 14*

    A 2HDM for the g-2 and Dark Matter

    Giorgio Arcadi🇮🇹 · Álvaro S. de Jesus🇧🇷 · Téssio B. de Melo🇧🇷 · Farinaldo S. Queiroz🇧🇷 · Yoxara S. Villamizar🇧🇷

    The Muon g-2 experiment at FERMILAB has confirmed the muon anomalous magnetic moment anomaly with an error bar 15% smaller and a different central value compared with the previous Brookhaven result. The combined results from FERMILAB and Brookhaven show a difference with theory at a significance of $4.2\sigma$, strongly indicating the presence of new physics. In light of this new result, we discuss a Two Higgs Doublet model augmented by an Abelian gauge symmetry that can simultaneously accommodate a light dark matter candidate and $(g-2{)}_{\mu }$, in agreement with existing bounds.

    hep-phhep-exNPB(2022)·35 citations
15. 15*

    GUT-constrained supersymmetry and dark matter in light of the new $(g-2{)}_{\mu }$ determination

    Manimala Chakraborti🇵🇱 · Leszek Roszkowski🇵🇱 · Sebastian Trojanowski🇵🇱

    The recent confirmation by the Fermilab-based Muon g-2 experiment of the $(g-2{)}_{\mu }$ anomaly has important implications for allowed particle spectra in softly broken supersymmetry (SUSY) models with neutralino dark matter (DM). Generally, the DM has to be quite light, with the mass up to a few hundred GeV, and bino-dominated if it is to provide most of DM in the Universe. Otherwise, a higgsino or wino dominated DM is also allowed but only as a strongly subdominant component of at most a few percent of the total density. These general patterns can easily be found in the phenomenological models of SUSY but in GUT-constrained scenarios this proves much more challenging. In this paper we revisit the issue in the framework of some unified SUSY models with different GUT boundary conditions on the soft masses. We study the so-called non-universal gaugino model (NUGM) in which the mass of the gluino is disunified from those of the bino and the wino and an SO(10) and an SU(5) GUT-inspired models as examples. We find that in these unified frameworks the above two general patterns of DM can also be found, and thus the muon anomaly can also be accommodated, unlike in the simplest frameworks of the CMSSM or the NUHM. We show the resulting values of direct detection cross-section for points that do and do not satisfy the muon anomaly. On the other hand, it will be challenging to access those solutions at the LHC because the resulting spectra are generally very compressed.

    hep-phJHEP(2021)·77 citations
16. 16*

    Taming the pinch singularities in the two-loop neutrino self-energy in a medium

    José F. Nieves🇺🇸 · Sarira Sahu🇲🇽

    We consider the calculation of the thermal self-energy of a neutrino that propagates in a medium composed of fermions and scalars interacting via a Yukawa-type coupling, in the case that the neutri no energy is much larger than the fermion and scalar masses, as well as the temperature and chemical potentials of the background. In this kinematic regime the one-loop contribution to the imaginary part of the self-energy is negligible. We consider the two-loop contribution and we encounter the so-called pinch singularities which are known to arise in higher loop self-energy calculations in Thermal Field Theory. With a judicious use of the properties and parametrizations of the thermal propagators the singularities are treated effectively and actually disappear. From the imaginary part of the self-energy, we obtain a precise formula for the damping matrix expressed in terms of integrals over the background particle distributions. The formulas predict a specific dependence of the damping terms on the neutrino energy, depending on the background conditions. For guidance to estimating the effects in specific contexts, we compute the damping terms for several limiting cases of the momentum distribution functions of the background particles. We discuss briefly the connection between the results of our calculations for the damping matrix and the decoherence effects described in terms of the Lindblad equation.

    hep-phPRD(2021)·2 citations
17. 17*

    $\ge 4\mu$ signal from a vector-like lepton decaying to a muon-philic $Z^{\prime }$ boson at the LHC

    Junichiro Kawamura🇰🇷 · Stuart Raby🇺🇸

    We propose a novel possibility to detect a very distinctive signal with more than four muons originating from pair-produced vector-like leptons decaying to a muon-philic $Z^{\prime }$ boson. These new particles are good candidates to explain the anomalies in the muon anomalous magnetic moment and the $b\to s\ell \ell$ processes. The doublet (singlet) vector-like leptons lighter than 1.3 (1.0) TeV are excluded by the latest data at the LHC if $\mathrm{BR}(E\to Z^{\prime }\mu )=1$. We also show that the excess in the signal region with more than five leptons can be explained by this scenario if the vector-like lepton is a weak singlet, with mass about 400 GeV and $\mathrm{BR}(E\to Z^{\prime }\mu )=0.25$. The future prospects at the HL-LHC are discussed.

    hep-phhep-exPRD(2021)·24 citations
18. 18*

    Charged lepton flavor violation in light of the muon magnetic moment anomaly and colliders

    Tong Li🇨🇳 · Michael A. Schmidt🇦🇺 · Chang-Yuan Yao🇨🇳 · Man Yuan🇨🇳

    Any observation of charged lepton flavor violation (CLFV) implies the existence of new physics beyond the SM in charged lepton sector. CLFV interactions may also contribute to the muon magnetic moment and explain the discrepancy between the SM prediction and the recent muon $g-2$ precision measurement at Fermilab. We consider the most general SM gauge invariant Lagrangian of $\Delta L=0$ bileptons with CLFV couplings and investigate the interplay of low-energy precision experiments and colliders in light of the muon magnetic moment anomaly. We go beyond previous work by demonstrating the sensitivity of the LHC, the MACE experiment, a proposed muonium-antimuonium conversion experiment, and a muon collider. Currently-available LHC data is already able to probe unexplored parameter space via the CLFV process $pp\to {\gamma }^{\ast }/Z^{\ast }\to {\ell }_1^{\pm }{\ell }_1^{\pm }{\ell }_2^{\mp }{\ell }_2^{\mp }$.

    hep-phEPJC(2021)·40 citations
19. 19*

    Removal of singularities from the covariant spectator theory

    Franz Gross🇺🇸

    A modification of the one boson exchange (OBE) kernel for the covariant spectator theory (CST) is presented and discussed. When applied to the scattering of two identical particles, the previously used kernels either introduced spurious singularities, or removed them in an ad-hoc way. The new modification not only removes these singularities, but also maintains the convergence of the two-body CST equation (sometimes called the Gross equation) when used to describe the scattering of two identical scalar particles.

    hep-phPRD(2021)·1 citation
20. 20*

    Shedding light on dark matter with recent muon $(g-2)$ and Higgs exotic decay measurements

    Chih-Ting Lu🇰🇷 · Raymundo Ramos🇹🇼 · Yue-Lin Sming Tsai🇨🇳

    Recently, we have witnessed two hints of physics beyond the standard model: A 3.3$\sigma$ local excess ($M_{A_0}=52$ GeV) in the search for $H_0\to A_0{A}_0\to b\bar{b}{\mu }^{+}{\mu }^{-}$ and a 4.2$\sigma$ deviation from the SM prediction in the $(g-2{)}_{\mu }$ measurement. The first excess was found by the ATLAS Collaboration using 139 fb${}^{-1}$ data at $\sqrt{s}=13$ TeV. The second deviation is a combination of the results from the Brookhaven E821 and the recently reported Fermilab E989 experiment. We attempt to explain these deviations in terms of a renormalizable simplified dark matter model. Inspired by the null signal result from dark matter (DM) direct detection, we interpret the possible new particle, $A_0$, as a pseudoscalar mediator connecting DM and the standard model. On the other hand, a new vector-like muon lepton can explain these two excesses at the same time while contributiong to the DM phenomenology.

    hep-phJHEP(2021)·17 citations
21. 21*

    Parton rescattering and gluon saturation in dijet production at EIC

    Yuan-Yuan Zhang🇨🇳 · Xin-Nian Wang🇨🇳

    Large angle gluon radiations induced by multiple parton scatterings contribute to dijet production in deeply inelastic scattering off a large nucleus at the Electron-Ion Collider. Within the generalized high-twist approach to multiple parton scattering, such contributions at the leading order in perturbative QCD and large Bjorken momentum fraction $x_B$ can be expressed as a convolution of the multiple parton scattering amplitudes and the transverse momentum dependent (TMD) two-parton correlation matrix elements. We study this medium-induced dijet spectrum and its azimuthal angle correlation under the approximation of small longitudinal momentum transfer in the secondary scattering and the factorization of two-parton correlation matrix elements as a product of quark and gluon TMD parton distribution function (PDF). Using a simple model for gluon saturation based on the parametrized gluon TMD PDF, we can calculate the $x_B$ and $Q^2$ dependence of the saturation scale and parton transport coefficient $\hat{q}$. Contributions to dijet cross section from double scattering are power-suppressed and only become sizable for mini-jets at small transverse momentum. We find that the total dijet correlation for these mini-jets, which also includes the contribution from single scattering, is sensitive to the transverse momentum broadening in the quark TMD PDF at large $x$ and saturation in the gluon TMD PDF at small $x$ inside the nucleus. The correlation from double scattering is also found to increase with the dijet rapidity gap and have a quadratic nuclear-size dependence because of the Landau-Pomeranchuk-Migdal (LPM) interference in gluon emission induced by multiple scattering. Experimental measurements of such unique features in the dijet correlation can shed light on the LPM interference in strong interaction and gluon saturation in large nuclei.

    hep-phnucl-thPRD(2022)·27 citations
22. 22*

    Bound State Solution Schrödinger Equation for Extended Cornell Potential at Finite Temperature

    A.I. Ahmadov🇦🇿 · K.H. Abasova🇦🇿 · M.Sh. Orucova🇦🇿

    In this paper, we study the finite temperature-dependent Schrödinger equation by using the Nikiforov-Uvarov method. We consider the sum of the Cornell, inverse quadratic, and harmonic-type potential as the potential part of the radial Schrödinger equation. Analytical expressions for the energy eigenvalues and the radial wave function are presented. Application of the results for the heavy quarkonia and $B_c$ meson masses are good agreement with the current experimental data except for zero angular momentum quantum numbers. Numerical results for the temperature dependence indicates a different behaviour for different quantum numbers. Temperature-dependent results are in agreement with some QCD sum rule results from the ground states.

    hep-phhep-thmath-phmath.MP+1Adv.High Energy Phys.(2021)·11 citations
23. 23*

    Compressing PDF sets using generative adversarial networks

    Stefano Carrazza🇮🇹 · Juan M. Cruz-Martinez🇮🇹 · Tanjona R. Rabemananjara🇮🇹

    We present a compression algorithm for parton densities using synthetic replicas generated from the training of a Generative Adversarial Network (GAN). The generated replicas are used to further enhance the statistics of a given Monte Carlo PDF set prior to compression. This results in a compression methodology that is able to provide a compressed set with smaller number of replicas and a more adequate representation of the original probability distribution. We also address the question of whether the GAN could be used as an alternative mechanism to avoid the fitting of large number of replicas.

    hep-phhep-exEPJC(2021)·18 citations
24. 24*

    Precision Calculation of Dark Radiation from Spinning Primordial Black Holes and Early Matter Dominated Eras

    Alexandre Arbey🇫🇷 · Jérémy Auffinger🇫🇷 · Pearl Sandick🇺🇸 · Barmak Shams Es Haghi🇺🇸 · Kuver Sinha🇺🇸

    We present precision calculations of dark radiation in the form of gravitons coming from Hawking evaporation of spinning primordial black holes (PBHs) in the early Universe. Our calculation incorporates a careful treatment of extended spin distributions of a population of PBHs, the PBH reheating temperature, and the number of relativistic degrees of freedom. We compare our precision results with those existing in the literature, and show constraints on PBHs from current bounds on dark radiation from BBN and the CMB, as well as the projected sensitivity of CMB Stage 4 experiments. As an application, we consider the case of PBHs formed during an early matter-dominated era (EMDE). We calculate graviton production from various PBH spin distributions pertinent to EMDEs, and find that PBHs in the entire mass range up to $10^9$g will be constrained by measurements from CMB Stage 4 experiments, assuming PBHs come to dominate the Universe prior to Hawking evaporation. We also find that for PBHs with monochromatic spins $a^{\ast }>0.81$, all PBH masses in the range $10^{-1}\mathrm{g}<M_{\mathrm{BH}}<10^9$g will be probed by CMB Stage 4 experiments.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2021)·91 citations
25. 25*

    Hubble tension in lepton asymmetric cosmology with an extra radiation

    Osamu Seto🇯🇵 · Yo Toda🇯🇵

    We study the fit of cosmological models with two additional free parameters $N_{\mathrm{eff}}$ and ${\xi }_e$ in addition to the parameters of $\Lambda$CDM. We introduce extra radiation components such as hot axions or sterile neutrinos in addition to the energy density of neutrinos with large neutrino degeneracy. Then, a larger $N_{\mathrm{eff}}$ is allowed without spoiling Big Bang Nucleosynthesis (BBN), as positive neutrino degeneracy ${\xi }_e$ could improve BBN fit. By analysing the data from Planck, baryon acoustic oscillation (BAO), BBN and type-Ia supernovae (SNeIa), it can be seen that the Hubble tension can be ameliorated for ${\xi }_e\simeq 0.04$ and $0.3\lesssim \Delta N_{\mathrm{eff}}\lesssim 0.6$.

    ↳ astro-ph.COhep-phPRD(2021)·36 citations
26. 26*

    Leggett-Garg inequalities and decays of unstable systems

    Francesco Giacosa🇵🇱 · Giuseppe Pagliara🇮🇹

    We apply the Leggett-Garg inequalities (LGI) to the case of classical and quantum unstable systems. For classical systems the two assumptions of macroscopic realism and non-invasive measurements imply that the three-measurement string $K_3$ is identically equal to one. Also for quantum mechanical systems -- for which the two assumptions are in general not valid -- we find that $K_3=1$ for purely exponential decays ($K_3\le 1$ is the general LGI). On the other hand, the necessary deviations from the exponential decay law at short and long times predicted by quantum mechanics lead to values of $K_3\ne 1$. Moreover, a strict violations $K_3>1$ occurs typically at short times. Thus, we conclude that experiments in which such deviations from the exponential decay law have been observed should also find in their data violations of the LGIs.

    ↳ quant-phhep-phPRA(2021)·5 citations
27. 27*

    Rigorous constraints on three-nucleon forces in chiral effective field theory from fast and accurate calculations of few-body observables

    S. Wesolowski🇺🇸 · I. Svensson🇸🇪 · A. Ekström🇸🇪 · C. Forssén🇸🇪 · R. J. Furnstahl🇺🇸 · J. A. Melendez🇺🇸 · D. R. Phillips🇺🇸

    We explore the constraints on the three-nucleon force (3NF) of chiral effective field theory ($\chi$EFT) that are provided by bound-state observables in the $A=3$ and $A=4$ sectors. Our statistically rigorous analysis incorporates experimental error, computational method uncertainty, and the uncertainty due to truncation of the $\chi$EFT expansion at next-to-next-to-leading order. A consistent solution for the ${}^3$H binding energy, the ${}^4$He binding energy and radius, and the ${}^3$H $\beta$-decay rate can only be obtained if $\chi$EFT truncation errors are included in the analysis. All of these except the $\beta$-decay rate give essentially degenerate constraints on the 3NF low-energy constants, so it is crucial for estimating these parameters. We use eigenvector continuation for fast and accurate emulation of No-Core Shell Model calculations of the considered few-nucleon observables. This facilitates sampling of the posterior probability distribution, allowing us to also determine the distributions of the hyperparameters that quantify the truncation error. We find a $\chi$EFT expansion parameter of $Q=0.33\pm 0.06$ for these observables.

    ↳ nucl-thhep-phnucl-exphysics.data-anPRC(2021)·103 citations
28. 28*

    Measurement Problem in Quantum Mechanics and the Surjection Hypothesis

    Fritz W. Bopp🇩🇪

    Starting with unitary quantum dynamics, we investigate how to add quantum measurements. Quantum measurements have four essential components: the furcation, the witness production, an alignment projection, and the actual choice decision. The first two components still lie in the domain of unitary quantum dynamics. The decoherence concept explains the third contribution. It can be based on the requirement that witnesses reaching the end of time on the wave function side and the conjugate one have to be identical. In this way, it also stays within the quantum dynamics domain. The surjection hypothesis explains the actual choice decision. It is based on a two boundary interpretation applied to the complete quantum universe. It offers a simple way to reduce these seemingly random projections to purely deterministic unitary quantum dynamics, eliminating the measurement problem.

    ↳ quant-phhep-phQuantum Rep.(2021)·0 citations
29. 29*

    Classical Gravity from Loop Amplitudes

    N. Emil J. Bjerrum-Bohr🇩🇰 · Poul H. Damgaard🇩🇰 · Ludovic Planté🇫🇷 · Pierre Vanhove🇫🇷

    We describe an efficient method for extracting the parts of $D$-dimensional loop integrals that are needed to derive observables in classical general relativity from scattering amplitudes. Our approach simplifies the soft-region method of integration by judiciously combining terms before the final integrations. We demonstrate the method by computing the required integrals for black-hole scattering to the second Post-Minkowskian order in Einstein gravity coupled to scalars. We also confirm recent results at the third Post-Minkowskian order regarding universality and high-energy behavior of gravitational interactions in maximal supergravity.

    ↳ hep-thgr-qchep-phPRD(2021)·140 citations
30. 30*

    A Compound Poisson Generator approach to Point-Source Inference in Astrophysics

    Gabriel H. Collin🇺🇸 · Nicholas L. Rodd🇺🇸 · Tyler Erjavec🇺🇸 · Kerstin Perez🇺🇸

    The identification and description of point sources is one of the oldest problems in astronomy; yet, even today the correct statistical treatment for point sources remains one of the field's hardest problems. For dim or crowded sources, likelihood based inference methods are required to estimate the uncertainty on the characteristics of the source population. In this work, a new parametric likelihood is constructed for this problem using Compound Poisson Generator (CPG) functionals which incorporate instrumental effects from first principles. We demonstrate that the CPG approach exhibits a number of advantages over Non-Poissonian Template Fitting (NPTF) - an existing method - in a series of test scenarios in the context of X-ray astronomy. These demonstrations show that the effect of the point-spread function, effective area, and choice of point-source spatial distribution cannot, generally, be factorised as they are in NPTF, while the new CPG construction is validated in these scenarios. Separately, an examination of the diffuse-flux emission limit is used to show that most simple choices of priors on the standard parameterisation of the population model can result in unexpected biases: when a model comprising both a point-source population and diffuse component is applied to this limit, nearly all observed flux will be assigned to either the population or to the diffuse component. A new parametrisation is presented for these priors which properly estimates the uncertainties in this limit. In this choice of priors, CPG correctly identifies that the fraction of flux assigned to the population model cannot be constrained by the data.

    ↳ astro-ph.IMastro-ph.COastro-ph.HEhep-phAstrophys.J.Supp.(2022)·14 citations

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