Mon·May 11, 2020Monday·May 11, 2020

1. 01*

   Implications of $b\to s\mu \mu$ Anomalies for Future Measurements of $B\to K^{(\ast )}\nu \bar{\nu }$ and $K\to \pi \nu \bar{\nu }$

   Sébastien Descotes-Genon🇫🇷 · Svjetlana Fajfer🇸🇮 · Jernej F. Kamenik🇸🇮 · Martín Novoa-Brunet🇫🇷

   We investigate the consequences of deviations from the Standard Model observed in $b\to s\mu \mu$ transitions for flavour-changing neutral-current processes involving down-type quarks and neutrinos. We derive the relevant Wilson coefficients within an effective field theory approach respecting the SM gauge symmetry, including right-handed currents, a flavour structure based on approximate $U(2)$ symmetry, and assuming only SM-like light neutrinos. We discuss correlations among $B\to K^{(\ast )}\nu \bar{\nu }$ and $K\to \pi \nu \bar{\nu }$ branching ratios in the case of linear Minimal Flavour Violation and in a more general framework, highlighting in each case the role played by various New Physics scenarios proposed to explain $b\to s\mu \mu$ deviations.

   hep-phhep-exPLB(2020)·47 citations
2. 02*

   Stellar energy loss rates beyond the standard model

   A. Llamas-Bugarin🇲🇽 · A. Gutierrez-Rodriguez🇲🇽 · A. Gonzalez-Sanchez🇲🇽 · M. A. Hernandez-Ruiz🇲🇽 · A. Espinoza-Garrido🇲🇽 · A. Chubikalo🇲🇽

   It is known that the dipole moments of the neutrino lead to important astrophysical and cosmological effects. In this regard, within the context of a $U(1{)}_{B-L}$ model, we develop and present novel analytical formulas to assess the effects of the anomalous magnetic moment and electric dipole moment of the neutrino on the stellar energy loss rates through some common physical process of pair-annihilation $e^{+}{e}^{-}\to (\gamma ,Z,Z^{\prime })\to \nu \bar{\nu }$. Our results show that the stellar energy loss rates strongly depends on the effective magnetic moment of the neutrino, but also on the parameters which characterize the adopted $U(1{)}_{B-L}$ model.

   hep-phEur.Phys.J.Plus(2020)·4 citations
3. 03*

   Muon $g-2$ and CKM Unitarity in Extra Lepton Models

   Motoi Endo🇯🇵 · Satoshi Mishima🇯🇵

   We investigate the impact of extra leptons on observed tensions in the muon $g-2$ and the first-row CKM unitarity. By introducing a new SU(2)${}_L$ doublet lepton and a SU(2)${}_L$ triplet lepton, we find that both of the tensions can be explained simultaneously under constraints from electroweak precision observables and Higgs-boson decays. Our model could be tested by measurements of $h\to \mu \mu$ at future collider experiments.

   hep-phhep-exJHEP(2020)·54 citations
4. 04*

   Neutrino Mixing by modifying the Yukawa coupling structure of constrained sequential dominance

   Joy Ganguly🇮🇳 · Raghavendra Srikanth Hundi🇮🇳

   In the constrained sequential dominance (CSD), tri-bimaximal mixing (TBM) pattern in the neutrino sector has been explained, by proposing a certain Yukawa coupling structure for the right-handed neutrinos of the model. However, from the current experimental data it is known that the values of neutrino mixing angles are deviated from the TBM values. In order to explain this neutrino mixing, we first propose a phenomenological model where we consider Yukawa couplings which are modified from that of CSD. Essentially, we add small complex parameters to the Yukawa couplings of CSD. Using these modified Yukawa couplings, we demonstrate that neutrino mixing angles can deviate from their TBM values. We also construct a model, based on a flavor symmetry, in order to justify the modified form of Yukawa couplings of our work.

   hep-phPRD(2021)·6 citations
5. 05*

   Gravitational Imprints from Heavy Kaluza-Klein Resonances

   Eugenio Megias🇪🇸 · Germano Nardini🇳🇴 · Mariano Quiros🇪🇸

   We systematically study the holographic phase transition of the radion field in a five-dimensional warped model which includes a scalar potential with a power-like behavior. We consider Kaluza-Klein (KK) resonances with masses $m_{\mathrm{KK}}$ at the TeV scale or beyond. The backreaction of the radion field on the gravitational metric is taken into account by using the superpotential formalism. The confinement/deconfinement first order phase transition leads to a gravitational wave stochastic background which mainly depends on the scale $m_{\mathrm{KK}}$ and the number of colors, $N$, in the dual theory. Its power spectrum peaks at a frequency that depends on the amount of tuning required in the electroweak sector. It turns out that the present and forthcoming gravitational wave observatories can probe scenarios where the KK resonances are very heavy. Current aLIGO data already rule out vector boson KK resonances with masses in the interval $m_{\mathrm{KK}}\sim (1-10)\times 10^5$ TeV. Future gravitational experiments will be sensitive to resonances with masses $m_{\mathrm{KK}}\lesssim 10^5$ TeV (LISA), $10^8$ TeV (aLIGO Design) and $10^9$ TeV (ET). Finally, we also find that the Big Bang Nucleosynthesis bound in the frequency spectrum turns into a lower bound for the nucleation temperature as $T_n\gtrsim 10^{-4}\sqrt{N}{m}_{\mathrm{KK}}$.

   hep-phgr-qchep-thPRD(2020)·33 citations
6. 06*

   Phenomenological consequences of an interacting multicomponent dark sector

   Jan Tristram Acuña🇮🇹 · Marco Fabbrichesi🇮🇹 · Piero Ullio🇮🇹

   We consider a dark sector model containing stable fermions charged under an unbroken $U(1)$ gauge interaction, with a massless dark photon as force carrier, and interacting with ordinary matter via scalar messengers. We study its early Universe evolution by solving a set of coupled Boltzmann equations that track the number density of the different species, as well as entropy and energy exchanges between the dark and visible sectors. Phenomenologically viable realizations include: i) a heavy (order 1 TeV or more) lepton-like dark fermion playing the role of the dark matter candidate, with various production mechanisms active depending on the strength of the dark-visible sector portal; ii) light (few GeV to few tens of GeV) quark-like dark fermions, stable but with suppressed relic densities; iii) an extra radiation component in Universe due to dark photons, with temperature constrained by cosmic microwave background data, and in turn preventing dark fermions to be lighter than about 1 GeV. Extra constraints on our scenario stem from dark matter direct detection searches: the elastic scattering on nuclei is driven by dipole or charge radius interactions mediated by either Standard Model or dark photons, providing long-range effects which, however, are not always dominant, as usually assumed in this context. Projected sensitivities for next-generation detectors cover a significant portion of the viable parameter space and are competitive with respect to the model-dependent constraints derived from the magnetic dipole moments of leptons and cooling of stellar systems.

   hep-phPRD(2020)·6 citations
7. 07*

   Two-Loop Integrals for Planar Five-Point One-Mass Processes

   S. Abreu🇧🇪 · H. Ita🇩🇪 · F. Moriello🇨🇭 · B. Page🇫🇷 · W. Tschernow🇩🇪 · M. Zeng🇨🇭

   We present the computation of a full set of planar five-point two-loop master integrals with one external mass. These integrals are an important ingredient for two-loop scattering amplitudes for two-jet-associated W-boson production at leading color in QCD. We provide a set of pure integrals together with differential equations in canonical form. We obtain analytic differential equations efficiently from numerical samples over finite fields, fitting an ansatz built from symbol letters. The symbol alphabet itself is constructed from cut differential equations and we find that it can be written in a remarkably compact form. We comment on the analytic properties of the integrals and confirm the extended Steinmann relations, which govern the double discontinuities of Feynman integrals, to all orders in $ϵ$. We solve the differential equations in terms of generalized power series on single-parameter contours in the space of Mandelstam invariants. This form of the solution trivializes the analytic continuation and the integrals can be evaluated in all kinematic regions with arbitrary numerical precision.

   hep-phJHEP(2020)·132 citations
8. 08*

   Probing the Nature of Neutrinos with a New Force

   Pavel Fileviez Perez🇺🇸 · Alexis D. Plascencia🇺🇸

   We discuss the possibility to distinguish between Dirac and Majorana neutrinos in the context of the minimal gauge theory for neutrino masses, the B-L gauge extension of the Standard Model. We revisit the possibility to observe lepton number violation at the Large Hadron Collider and point out the importance of the decays of the new gauge boson to discriminate between the existence of Dirac or Majorana neutrinos.

   hep-phhep-exPRD(2020)·14 citations
9. 09*

   Dark Matter Capture by Atomic Nuclei

   Bartosz Fornal🇺🇸 · Benjamin Grinstein🇺🇸 · Yue Zhao🇺🇸

   We propose a new strategy to search for a particular type of dark matter via nuclear capture. If the dark matter particle carries baryon number, as motivated by a class of theoretical explanations of the matter-antimatter asymmetry of the universe, it can mix with the neutron and be captured by an atomic nucleus. The resulting state de-excites by emitting a single photon or a cascade of photons with a total energy of up to several MeV. The exact value of this energy depends on the dark matter mass. We investigate the prospects for detecting dark matter capture signals in current and future neutrino and dark matter direct detection experiments.

   hep-phhep-exnucl-exPLB(2020)·13 citations
10. 10*

    Resonant Conversion of Dark Matter Oscillons in Pulsar Magnetospheres

    Anirudh Prabhu🇺🇸 · Nicholas M. Rapidis🇺🇸

    Due to their high magnetic fields and plasma densities, pulsars provide excellent laboratories for tests of beyond Standard Model (BSM) physics. When axions or axion-like particles (ALPs) approach closely enough to pulsars, they can be resonantly converted to photons, yielding dramatic electromagnetic signals. We discuss the possibility of detecting such signals from bound configurations of axions, colliding with pulsar magnetospheres. We find that all but the densest axion stars, $\text{oscillons}$, are tidally destroyed well before resonant conversion can take place. Oscillons can be efficiently converted to photons, leading to bright, ephemeral radio flashes. Observation of the galactic bulge using existing (Very Large Array and LOFAR) and forthcoming (Square Kilometer Array) radio missions has the potential to detect such events for axion masses in the range $m_a\in \left[0.1\mu \text{eV},200\mu \text{eV}\right]$, even if oscillons make up a negligible fraction of dark matter.

    ↳ astro-ph.COastro-ph.HEhep-phJCAP(2020)·32 citations
11. 11*

    Quantifying the $S_8$ tension with the Redshift Space Distortion data set

    David Benisty🇮🇱

    One problem of the $\Lambda$CDM model is the tension between the $S_8$ found in Cosmic Microwave Background (CMB) experiments and the smaller one obtained from large-scale observations in the late Universe. The ${\sigma }_8$ quantifies the relatively high level of clustering. Bayesian Analysis of the Redshift Space Distortion (RSD) selected data set yields: $S_8=0.700_{-0.037}^{+0.038}$. The fit has $3\sigma$ tension with the Planck 2018 results. With Gaussian processes method a model-independent reconstructions of the growth history of matter in-homogeneity is studied. The fit yields $S_8=0.707_{-0.085}^{+0.085},0.701_{-0.089}^{+0.089}$, and $0.731_{-0.062}^{+0.063}$ for different kernels. The tension reduces and being smaller then $1.5\sigma$. With future measurements the tension may be reduced, but the possibility the tension is real is a plausible situation.

    ↳ astro-ph.COgr-qchep-phPhys.Dark Univ.(2021)·123 citations
12. 12*

    Finite temperature effects in modular cosmology

    Diego Gallego🇨🇴

    We revisit the cosmological history in the presence of light moduli by including possible thermal effects in the scalar potential. The well known cosmological moduli problem regards initial energy stored in the moduli due to a misalignment from its final position during inflation. We show that finite temperature corrections to the scalar potential, in general, induce similar effects and these are likely to overcome the ones from the misalignment. This changes important parameters like the preferred window for the numbers of e-fold during inflation and the final reheating temperature in a model-dependent manner. The general implications are a longer late modulus dominated epoch and a larger final reheating temperature. We explore all the discussed elements in type-IIB superstring Large Volume Compactification with a Kähler inflationary scenario, where zero temperature results are known. An instability analysis, using a Floquet approach, is also performed for this explicit case finding strong indications of possible oscillon production around a nearly universal normalized critical temperature, where the Floquet exponents show a divergent behaviour.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2020)·6 citations
13. 13*

    Predicting the dark matter velocity distribution in galactic structures: tests against hydrodynamic cosmological simulations

    Thomas Lacroix🇪🇸 · Arturo Núñez-Castiñeyra🇫🇷 · Martin Stref🇫🇷 · Julien Lavalle🇫🇷 · Emmanuel Nezri🇫🇷

    Reducing theoretical uncertainties in Galactic dark matter (DM) searches is an important challenge as several experiments are now delving into the parameter space relevant to popular (particle or not) candidates. Since many DM signal predictions rely on the knowledge of the DM velocity distribution---direct searches, capture by stars, p-wave-suppressed or Sommerfeld-enhanced annihilation rate, microlensing of primordial black holes, etc.---it is necessary to assess the accuracy of our current theoretical handle. Beyond Maxwellian approximations or ad-hoc extrapolations of fits on cosmological simulations, approaches have been proposed to self-consistently derive the DM phase-space distribution only from the detailed mass content of the Galaxy and some symmetry assumptions (e.g. the Eddington inversion and its anisotropic extensions). Although theoretically sound, these methods are still based on simplifying assumptions and their relevance to real galaxies can be questioned. In this paper, we use zoomed-in cosmological simulations to quantify the associated uncertainties. Assuming isotropy, we predict the speed distribution and its moments from the DM and baryonic content measured in simulations, and compare them with the true ones. Taking as input galactic mass models fitted on full simulation data, we reach a predictivity down to ~ 10% for some velocity-related observables, significantly better than some Maxwellian models. This moderate theoretical error is particularly encouraging at a time when stellar surveys like the Gaia mission should allow us to improve constraints on Galactic mass models.

    ↳ astro-ph.GAastro-ph.COhep-phJCAP(2020)·29 citations
14. 14*

    Primordial dark matter from curvature induced symmetry breaking

    Laura Laulumaa🇫🇮 · Tommi Markkanen🇪🇪 · Sami Nurmi🇫🇮

    We demonstrate that adiabatic dark matter can be generated by gravity induced symmetry breaking during inflation. We study a $Z_2$ symmetric scalar singlet that couples to other fields only through gravity and for which the symmetry is broken by the spacetime curvature during inflation when the non-minimal coupling $\xi$ is negative. We find that the symmetry breaking leads to the formation of adiabatic dark matter with the observed abundance for the singlet mass $m\sim \mathrm{MeV}$ and $|\xi |\sim 1$.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·13 citations
15. 15*

    Partial Deconfinement at Strong Coupling on the Lattice

    Hiromasa Watanabe🇯🇵 · Georg Bergner🇩🇪 · Norbert Bodendorfer🇩🇪 · Shotaro Shiba Funai🇯🇵 · Masanori Hanada🇬🇧 · Enrico Rinaldi🇯🇵 · Andreas Schäfer🇩🇪 · Pavlos Vranas🇺🇸

    We provide evidence for partial deconfinement -- the deconfinement of a SU($M$) subgroup of the SU($N$) gauge group -- by using lattice Monte Carlo simulations. We take matrix models as concrete examples. By appropriately fixing the gauge, we observe that the $M\times M$ submatrices deconfine. This gives direct evidence for partial deconfinement at strong coupling. We discuss the applications to QCD and holography.

    ↳ hep-thhep-lathep-phJHEP(2021)·30 citations
16. 16*

    Extracting a model quark propagator's spectral density

    Zehao Zhu🇨🇳 · Khépani Raya🇨🇳 · Lei Chang🇨🇳

    We propose a practical procedure to extrapolate the space-like quark propagator onto the complex plane, which follows the Schlessinger Point Method and the spectral representation of the propagator. As a feasible example, we employ quark propagators for different flavors, obtained from the solutions of the corresponding Dyson-Schwinger equation (DSE). Two different truncations are employed. Thus, the analytical structure of the quark propagator is studied, capitalizing on the current-quark mass dependence of the observed features.

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

    Short flow-time coefficients of CP-violating operators

    Matthew D. Rizik🇺🇸 · Christopher J. Monahan🇺🇸 · Andrea Shindler🇺🇸

    Measurements of a permanent neutron electric dipole moment (EDM) potentially probe Beyond-the-Standard Model (BSM) sources of CP-violation. At low energy the CP-violating BSM interactions are parametrized by flavor-conserving CP-violating operators of dimension higher than four. QCD calculations of the nucleon matrix elements of these operators are required to fully reconstruct the sources and magnitudes of the different CP-violating contributions to the nucleon EDM. Herein we study the quark-chromo electric dipole moment (qCEDM) operator and the three-gluon Weinberg operator. The non-perturbative determination, using lattice QCD, of the nucleon matrix elements of these CP-violating operators is hampered by their short-distance behavior. Under renormalization these operators mix with lower dimensional operators, which induces power divergences in the lattice spacing, as the continuum limit is approached. We study the short-distance behavior of the qCEDM and the Weinberg operators using the gradient flow. We perform a short flow time expansion and determine, in perturbation theory, the expansion coefficients of the linearly-divergent terms stemming from the mixing with the pseudoscalar density and the topological charge, confirming the expectations of the operator product expansion. We introduce a new method to perform calculations at non-zero flow-time for arbitrary values of the external momenta. This method allows us to work in four dimensions for most of the calculations described in this paper, avoiding the complications associated with defining ${\gamma }_5$ in generic d dimensions. We show that leading contributions in the external momenta can be reproduced by defining ${\gamma }_5$ using the 't Hooft-Veltman-Breitenlohner-Maison scheme.

    ↳ hep-lathep-phPRD(2020)·46 citations
18. 18*

    The Cosmological Bootstrap: Spinning Correlators from Symmetries and Factorization

    Daniel Baumann🇳🇱 · Carlos Duaso Pueyo🇳🇱 · Austin Joyce🇳🇱 · Hayden Lee🇺🇸 · Guilherme L. Pimentel🇳🇱

    We extend the cosmological bootstrap to correlators involving massless particles with spin. In de Sitter space, these correlators are constrained both by symmetries and by locality. In particular, the de Sitter isometries become conformal symmetries on the future boundary of the spacetime, which are reflected in a set of Ward identities that the boundary correlators must satisfy. We solve these Ward identities by acting with weight-shifting operators on scalar seed solutions. Using this weight-shifting approach, we derive three- and four-point correlators of massless spin-1 and spin-2 fields with conformally coupled scalars. Four-point functions arising from tree-level exchange are singular in particular kinematic configurations, and the coefficients of these singularities satisfy certain factorization properties. We show that in many cases these factorization limits fix the structure of the correlators uniquely, without having to solve the conformal Ward identities. The additional constraint of locality for massless spinning particles manifests itself as current conservation on the boundary. We find that the four-point functions only satisfy current conservation if the s, t, and u-channels are related to each other, leading to nontrivial constraints on the couplings between the conserved currents and other operators in the theory. For spin-1 currents this implies charge conservation, while for spin-2 currents we recover the equivalence principle from a purely boundary perspective. For multiple spin-1 fields, we recover the structure of Yang-Mills theory. Finally, we apply our methods to slow-roll inflation and derive a few phenomenologically relevant scalar-tensor three-point functions.

    ↳ hep-thastro-ph.COgr-qchep-phSciPost Phys.(2021)·292 citations
19. 19*

    Extremal black hole scattering at O(G^3): graviton dominance, eikonal exponentiation, and differential equations

    Julio Parra-Martinez🇺🇸 · Michael S. Ruf🇩🇪 · Mao Zeng🇨🇭

    We use $\mathcal{N}=8$ supergravity as a toy model for understanding the dynamics of black hole binary systems via the scattering amplitudes approach. We compute the conservative part of the classical scattering angle of two extremal (half-BPS) black holes with minimal charge misalignment at $\mathcal{O}(G^3)$ using the eikonal approximation and effective field theory, finding agreement between both methods. We construct the massive loop integrands by Kaluza-Klein reduction of the known $D$-dimensional massless integrands. To carry out integration we formulate a novel method for calculating the post-Minkowskian expansion with exact velocity dependence, by solving velocity differential equations for the Feynman integrals subject to modified boundary conditions that isolate conservative contributions from the potential region. Motivated by a recent result for universality in massless scattering, we compare the scattering angle to the result found by Bern et. al. in Einstein gravity and find that they coincide in the high-energy limit, suggesting graviton dominance at this order.

    ↳ hep-thgr-qchep-phJHEP(2020)·224 citations
20. 20*

    Dark matter or correlated errors: Systematics of the AMS-02 antiproton excess

    Jan Heisig🇧🇪 · Michael Korsmeier🇮🇹 · Martin Wolfgang Winkler🇸🇪

    Several studies have pointed out an excess in the AMS-02 antiproton spectrum at rigidities of 10-20 GV. Its spectral properties were found to be consistent with a dark-matter particle of mass 50-100 GeV which annihilates hadronically at roughly the thermal rate. In this work, we reinvestigate the antiproton excess including all relevant sources of systematic errors. Most importantly, we perform a realistic estimate of the correlations in the AMS-02 systematic error which could potentially "fake" a dark-matter signal. The dominant systematics in the relevant rigidity range originate from uncertainties in the cross sections for absorption of cosmic rays within the detector material. For the first time, we calculate their correlations within the full Glauber-Gribov theory of inelastic scattering. The AMS-02 correlations enter our spectral search for dark matter in the form of covariance matrices which we make publicly available for the cosmic-ray community. We find that the global significance of the antiproton excess is reduced to below 1 $\sigma$ once all systematics, including the derived AMS-02 error correlations, are taken into account. No significant preference for a dark-matter signal in the AMS-02 antiproton data is found in the mass range 10-10000 GeV.

    ↳ astro-ph.HEhep-phnucl-thPRResearch(2020)·102 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.