Fri·Oct 6, 2017Friday·October 6, 2017

1. 01*

   Exotic meson decays in the environment with chiral imbalance

   A. A. Andrianov🇷🇺 · V. A. Andrianov🇷🇺 · D. Espriu🇪🇸 · A. V. Iakubovich🇷🇺 · A. E. Putilova🇷🇺

   An emergence of Local Parity Breaking (LPB) in central heavy-ion collisions (HIC) at high energies is discussed. LPB in the fireball can be produced by a difference between the number densities of right- and left-handed chiral fermions (Chiral Imbalance) which is implemented by a chiral (axial) chemical potential. The effective meson lagrangian induced by QCD is extended to the medium with Chiral Imbalance and the properties of light scalar and pseudoscalar mesons ($\pi ,a_0$) are analyzed. It is shown that exotic decays of scalar mesons arise as a result of mixing of $\pi$ and $a_0$ vacuum states in the presence of chiral imbalance. The pion electromagnetic formfactor obtains an unusual parity-odd supplement which generates a photon polarization asymmetry in pion polarizability. We hope that the above pointed indications of LPB can be identified in experiments on LHC, RHIC, CBM FAIR and NICA accelerators.

   hep-phhep-thnucl-thEPJ Web Conf.(2017)·8 citations
2. 02*

   Multi-Component Dark Matter: the vector and fermion case

   Aqeel Ahmed🇩🇪 · Mateusz Duch🇵🇱 · Bohdan Grzadkowski🇵🇱 · Michal Iglicki🇵🇱

   Multi-component dark matter scenarios constitute natural extensions of standard single-component setups and offer attractive new dynamics that could be adopted to solve various puzzles of dark matter. In this work we present and illustrate properties of a minimal UV-complete vector-fermion dark matter model where two or three dark sector particles are stable. The model we consider is an extension of the Standard Model (SM) by spontaneously broken extra $U(1{)}_X$ gauge symmetry and a Dirac fermion. All terms in the Lagrangian which are consistent with the assumed symmetry are present, so the model is renormalizable and consistent. To generate mass for the dark-vector $X_{\mu }$ the Higgs mechanism with a complex singlet $S$ is employed in the dark sector. Dark matter candidates are the massive vector boson $X_{\mu }$ and two Majorana fermions ${\psi }_{\pm }$. All the dark sector fields are singlets under the SM gauge group. The set of three coupled Boltzmann equations has been solved numerically and discussed. We have performed scans over the parameter space of the model implementing the total relic abundance and direct detection constraints. The dynamics of the vector-fermion dark matter model is very rich and various interesting phenomena appear, in particular, when the standard annihilations of a given dark matter are suppressed then the semi-annihilations, conversions and decays within the dark sector are crucial for the evolution of relic abundance and its present value. Possibility of enhanced self-interaction has been also discussed.

   hep-phastro-ph.HEEPJC(2018)·81 citations
3. 03*

   The Pion Mass and Decay Constant at Three Loops in Two-Flavour Chiral Perturbation Theory

   Johan Bijnens🇸🇪 · Nils Hermansson Truedsson (Lund)🇸🇪

   A calculation of the pion mass and decay constant at NNNLO in two-flavour chiral perturbation theory is presented. The results are cross-checked by using both the exponential and square root parameterizations of the Goldstone matrix field, as well as by comparing to the known leading log coefficients of the two quantities. A small numerical study of the quark mass dependence is performed, and for a physical quark mass there is good agreement with lower order results.

   hep-phhep-latJHEP(2017)·18 citations
4. 04*

   Plasma-based wakefield accelerators as sources of axion-like particles

   David A. Burton🇬🇧 · Adam Noble🇬🇧

   We estimate the average flux density of minimally-coupled axion-like particles generated by a laser-driven plasma wakefield propagating along a constant strong magnetic field. Our calculations suggest that a terrestrial source based on this approach could generate a pulse of axion-like particles whose flux density is comparable to that of solar axion-like particles at Earth. This mechanism is optimal for axion-like particles with mass in the range of interest of contemporary experiments designed to detect dark matter using microwave cavities.

   hep-phphysics.acc-phNew J.Phys.(2018)·22 citations
5. 05*

   A perturbative study of the QCD phase diagram for heavy quarks at nonzero chemical potential: two-loop corrections

   J. Maelger🇫🇷 · U. Reinosa🇫🇷 · J. Serreau🇫🇷

   We extend a previous investigation of the QCD phase diagram with heavy quarks in the context of background field methods by including the two-loop corrections to the background field effective potential. The nonperturbative dynamics in the pure-gauge sector is modeled by a phenomenological gluon mass term in the Landau-DeWitt gauge-fixed action, which results in an improved perturbative expansion. We investigate the phase diagram at nonzero temperature and (real or imaginary) chemical potential. Two-loop corrections yield an improved agreement with lattice data as compared to the leading-order results. We also compare with the results of nonperturbative approaches. We further study the equation of state as well as the thermodynamic stability of the system at two-loop order. Finally, we show, using simple thermodynamic arguments, that the behavior of the Polyakov loops as functions of the chemical potential complies with their interpretation in terms of quark and anti-quark free energies.

   hep-phhep-lathep-thPRD(2018)·47 citations
6. 06*

   Applicability of transverse mass scaling in hadronic collisions at the LHC

   Lucas Altenkämper (1)🇳🇴 · Friederike Bock (2)🇨🇭 · Constantin Loizides (3)🇺🇸 · Nicolas Schmidt (3) ((1) UiB, (2) CERN, (3) ORNL)🇺🇸

   We present a study on the applicability of transverse mass scaling for identified particle spectra in proton-proton collisions at $\sqrt{s}=7$ TeV based on data taken by the ALICE experiment at the LHC. The measured yields are parametrized and compared to estimates obtained from a generalized transverse mass scaling approach applied to different reference particle spectra. It is found that generalized transverse mass scaling is not able to describe the measured spectra over the full range in transverse momentum. At low $p_{\mathrm{T}}$, deviations of $20$% or more are obtained, in particular if pions are used as reference particles. A better scaling performance is obtained, when kaons are used as reference particles. At high $p_{\mathrm{T}}$ all tested spectra with the possible exception of the charged kaons exhibit a scaling behavior. Investigating the feed-down contributions from resonance decays to the charged pion yields reveals, that using them as reference a general scaling may not be achievable. Our findings imply that for precision measurements of direct photon and di-electron spectra at low transverse momentum one should measure the relevant hadronic background, instead of relying on $m_{\mathrm{T}}$ scaling for its estimate.

   hep-phPRC(2017)·46 citations
7. 07*

   Testing the doubly charged charm-strange tetraquarks

   S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷

   The spectroscopic parameters and decay channels of the doubly charged scalar, pseudoscalar and axial-vector charm-strange tetraquarks $Z_{\overline{c}s}=[sd][\overline{u}\overline{c}]$ are explored within framework of the QCD sum rule. The masses and current couplings of these diquark-antidiquark states are calculated by means of two-point correlation functions and taking into account the vacuum condensates up to eight dimensions. To compute the strong couplings of $Z_{\overline{c}s}$ states with $D,D_s,D^{\ast },D_s^{\ast },D_{s1}(2460),D_{s0}^{\ast }(2317),\pi$ and $K$ mesons we use QCD light-cone sum rules and evaluate width of their $S$- and $P$-wave decays to a pair of negatively charged conventional mesons: For the scalar state $Z_{\overline{c}s}\to D_s\pi ,DK,D_{s1}(2460)\pi$, for the pseudoscalar state $Z_{\overline{c}s}\to D_s^{\ast }\pi ,D^{\ast }K,D_{s0}^{\ast }(2317)\pi ,$ and for the axial-vector state $Z_{\overline{c}s}\to D_s^{\ast }\pi ,D^{\ast }K,D_{s1}(2460)\pi$ decays are investigated. Obtained predictions for the spectroscopic parameters and decay widths of the $Z_{\overline{c}s}$ tetraquarks may be useful for experimental investigations of the doubly charged exotic hadrons.

   hep-phhep-exhep-latEPJC(2018)·21 citations
8. 08*

   Phenomenology of charged-particle multiplicity distributions

   Anton Alkin🇺🇦

   Charged-particle multiplicity distributions are an interesting tool to study both soft- and hard-QCD processes in hadronic collisions. Since last century a significant range of center-of-mass energies has been probed, ranging from a few GeV to 13 TeV in the latest LHC run. Common analysis of multiplicity distributions at different energies, in different phase space regions and from sufficiently different experiments provides a way to systematize and review existing phenomenological models of multiple particle production. In this work a phenomenological model is suggested, that can describe simultaneously charged-particle multiplicity distributions in different restricted pseudorapidity intervals for proton-proton collisions. The model is successfully applied to experimental results of ALICE experiment at LHC.

   hep-phUkr.J.Phys.(2017)·7 citations
9. 09*

   Revealing BSM composite dynamics via topological interactions at future colliders

   Natascia Vignaroli🇩🇰 · Emiliano Molinaro🇩🇰 · Francesco Sannino🇩🇰 · Anders Eller Thomsen🇩🇰

   In composite Higgs models, new composite pseudoscalars can interact with the Higgs and with electroweak gauge bosons via anomalous interactions, which stem from the topological structure of the underlying theory. A future 100 TeV pp collider (FCC-pp) will be able to test these anomalous interactions and thus shed light on the strong dynamics which generates the Higgs and other composite resonances. We will discuss the topological interactions of a minimal composite Higgs model with fermionic ultraviolet completion, based on the coset SU(4)/Sp(4). We will indicate the strategy to test these interactions at the FCC-pp and the expected reach.

   hep-phhep-exPoS(2017)·0 citations
10. 10*

    Prompt photon - jet angular correlations at central rapidities in p+A collisions

    Sanjin Benić🇭🇷 · Adrian Dumitru🇺🇸

    Photon-jet azimuthal correlations in proton-nucleus collisions are a promising tool for gaining information on the gluon distribution of the nucleus in the regime of non-linear color fields. We compute such correlations from the process $g+A\to q\bar{q}\gamma$ in the rapidity regime where both the projectile and target light-cone momentum fractions are small. By integrating over the phase space of the quark which emits the photon, subject to the restriction that the photon picks up most of the transverse momentum (to pass an isolation cut), we effectively obtain a $g+A\to q\gamma$ process. For nearly back-to-back photon-jet configurations we find that it dominates over the leading order process $q+A\to q\gamma$ by two less powers of $Q_{\perp }/Q_S$, where ${\mathbf{Q}}_{\perp }$ and $Q_S$ denote the net photon-jet pair momentum and the saturation scale of the nucleus, respectively. We determine the transverse momentum dependent gluon distributions involved in $g+A\to q\gamma$ and the scale where they are evaluated. Finally, we provide analytic expressions for $⟨\cos n\varphi ⟩$ moments, where $\varphi$ is the angle between ${\mathbf{Q}}_{\perp }$ and the average photon-jet transverse momentum ${\tilde{\mathbf{P}}}_{\perp }$, and first qualitative estimates of their transverse momentum dependence.

    hep-phPRD(2018)·25 citations
11. 11*

    Statistical approach to Higgs couplings in the standard model effective field theory

    Christopher W. Murphy🇺🇸

    We perform a parameter fit in the Standard Model Effective Field Theory (SMEFT) with an emphasis on using regularized linear regression to tackle the issue of the large number of parameters in the SMEFT. In regularized linear regression a positive definite function of the parameters of interest is added to the usual cost function. A cross-validation is performed to try to determine the optimal value of the regularization parameter to use, but it selects the Standard Model (SM) as the best model to explain the measurements. Nevertheless as proof of principle of this technique we apply it to fitting Higgs boson signal strengths in SMEFT, including the latest Run-2 results. Results are presented in terms of the eigensystem of the covariance matrix of the least squares estimators as it has a degree model-independent to it. We find several results in this initial work: the SMEFT predicts the total width of the Higgs boson to be consistent with the SM prediction; the ATLAS and CMS experiments at the LHC are currently sensitive to non-resonant double Higgs boson production. Constraints are derived on the viable parameter space for electroweak baryogenesis in the SMEFT, reinforcing the notion that a first order phase transition requires fairly low scale Beyond the SM physics. Finally, we study which future experimental measurements would give the most improvement on the global constraints on the Higgs sector of the SMEFT.

    hep-phhep-exPRD(2018)·27 citations
12. 12*

    Flavour alignment in multi-Higgs-doublet models

    Ana Peñuelas🇪🇸 · Antonio Pich🇪🇸

    Extended electroweak scalar sectors containing several doublet multiplets require flavour-aligned Yukawa matrices to prevent the appearance at tree level of unwanted flavour- changing neutral-current transitions. We analyse the misalignment induced by one-loop quantum corrections and explore possible generalizations of the alignment condition and their compatibility with current experimental constraints. The hypothesis of flavour alignment at a high scale turns out to be consistent with all known phenomenological tests.

    hep-phJHEP(2017)·71 citations
13. 13*

    Analysis of the $B^{+}\to J/\psi \varphi K^{+}$ data at low $J/\psi \varphi$ invariant masses and the $X(4140)$ and $X(4160)$ resonances

    En Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Li-Sheng Geng🇨🇳 · Eulogio Oset🇪🇸

    We have studied the $J/\psi \varphi$ mass distribution of the $B^{+}\to J/\psi \varphi K^{+}$ reaction from threshold to about 4250 MeV, and find that one needs the contribution of the $X(4140)$ with a narrow width, together with the $X(4160)$ which accounts for most of the strength of the distribution in that region. The existence of a clear cusp at the $D_s^{\ast }{\bar{D}}_s^{\ast }$ threshold indicates that the $X(4160)$ resonance is strongly tied to the $D_s^{\ast }{\bar{D}}_s^{\ast }$ channel, which finds a natural interpretation in the molecular picture of this resonance.

    hep-phhep-exPRD(2018)·37 citations
14. 14*

    Lepton Flavor Violation with Displaced Vertices

    Julian Heeck🇧🇪 · Werner Rodejohann🇩🇪

    If light new physics with lepton-flavor-violating couplings exists, the prime discovery channel might not be $\ell \to {\ell }^{\prime }\gamma$ but rather $\ell \to {\ell }^{\prime }X$, where the new boson $X$ could be an axion, majoron, familon or Z' gauge boson. The most conservative bound then comes from $\ell \to {\ell }^{\prime }+\mathrm{inv}$, but if the on-shell $X$ can decay back into leptons or photons, displaced-vertex searches could give much better limits. We show that only a narrow region in parameter space allows for displaced vertices in muon decays, $\mu \to eX,X\to \gamma \gamma ,ee$, whereas tauon decays can have much more interesting signatures.

    hep-phhep-exPLB(2018)·62 citations
15. 15*

    Coherent $\mu -e$ Conversion at Next-to-Leading Order

    Anthony Bartolotta🇺🇸 · Michael J. Ramsey-Musolf🇺🇸

    We analyze next-to-leading order (NLO) corrections and uncertainties for coherent $\mu -e$ conversion . The analysis is general but numerical results focus on ${}^{27}\text{Al}$, which will be used in the Mu2E experiment. We obtain a simple expression for the branching ratio in terms of Wilson coefficients associated with possible physics beyond the Standard Model and a set of model-independent parameters determined solely by Standard Model dynamics. For scalar-mediated conversion, we find that NLO two-nucleon contributions can significantly decrease the branching ratio, potentially reducing the rate by as much as 50%. The pion-nucleon $\sigma$-term and quark masses give the dominant sources of parametric uncertainty in this case. For vector-mediated conversion, the impact of NLO contributions is considerably less severe, while the present theoretical uncertainties are comparable to parametric uncertainties.

    hep-phhep-exnucl-thPRC(2018)·27 citations
16. 16*

    Large scale separation and hadronic resonances from a new strongly interacting sector

    Anna Hasenfratz🇺🇸 · Claudio Rebbi🇺🇸 · Oliver Witzel🇬🇧

    A large separation of scales is frequently required by theories describing physics beyond the Standard Model. In mass-split models with some massless (light) and some heavy flavors, large scale separation arises by construction if the system is conformal in the ultraviolet but chirally broken in the infrared. Due to the presence of a conformal fixed point, such chirally broken systems show hyperscaling and have a highly constrained resonance spectrum that is significantly different from the QCD spectrum. We present numerical evidence for hyperscaling of both light-light and heavy-heavy meson resonances and show that they only depend on the ratio of the light and heavy flavor masses. The heavy-heavy spectrum is qualitatively different from QCD. The mass of heavy-heavy quarkonia e.g. is not proportional to the constituent quark mass.

    hep-phhep-latPoS(2017)·3 citations
17. 17*

    $B$ decay anomalies and dark matter from vectorlike confinement

    James M. Cline🇨🇦

    Lepton flavor universality violating $B\to K\ell \ell$ and $K^{\ast }\ell \ell$ decays tentatively observed by LHCb can be explained by leptoquark exchange. We explore a simple model for the $B$ anomalies with a composite leptoquark from new strong dynamics at the TeV scale, a confining SU($N_{\mathrm{HC}}$) hypercolor interaction. The new matter fields, fundamentals under SU($N_{\mathrm{HC}}$), are heavy vectorlike fermions $\Psi ,S,$ and an inert scalar doublet $\varphi$. $\Psi$ is colored under QCD while $S$ is neutral, and the hyperbaryon $S^N$ is a dark matter candidate. The model is tightly constrained by meson-antimeson oscillations, lepton flavor violation, and LHC searches for resonant production of the exotic bound states. The dark matter may be detectable through its magnetic dipole moment. If $m_S$ is sufficiently small, composite leptoquarks and heavy lepton partners can be pair-produced at an observable level at LHC.

    hep-phPRD(2018)·81 citations
18. 18*

    Return of the X-rays: A New Hope for Fermionic Dark Matter at the keV Scale

    Vedran Brdar🇩🇪 · Joachim Kopp🇩🇪 · Jia Liu🇺🇸 · Xiao-Ping Wang🇺🇸

    A long time ago (in 2014), in galaxies and galaxy clusters far, far away, several groups have reported hints for a yet unidentified line in astrophysical X-ray signals at an energy of 3.5\,keV. While it is not unlikely that this line is simply a reflection of imperfectly modeled atomic transitions, it has renewed the community's interest in models of keV-scale dark matter, whose decay would lead to such a line. The alternative possibility of dark matter annihilation into monochromatic photons is far less explored, a lapse that we strive to amend in this paper. More precisely, we introduce a novel model of fermionic dark matter $\chi$ with $\mathcal{O}(\text{keV})$ mass, annihilating to a scalar state $\varphi$ which in turn decays to photons, for instance via loops of heavy vector-like quarks. The resulting photon spectrum is box-shaped, but if $\chi$ and $\varphi$ are nearly degenerate in mass, it can also resemble a narrow line. We discuss dark matter production via two different mechanisms -- misalignment and freeze-in -- which both turn out to be viable in vast regions of parameter space. We constrain the model using astrophysical X-ray data, and we demonstrate that, thanks to the velocity-dependence of the annihilation cross section, it has the potential to reconcile the various observations of the 3.5\,keV line. We finally address the $\varphi$-mediated force between dark matter particles and its possible impact on structure formation.

    hep-phastro-ph.HEPRL(2018)·37 citations
19. 19*

    Off-shell Higgs Probe to Naturalness

    Dorival Goncalves🇺🇸 · Tao Han🇺🇸 · Satyanarayan Mukhopadhyay🇺🇸

    Examining the Higgs sector at high energy scales through off-shell Higgs production can potentially shed light on the naturalness problem of the Higgs mass. We propose such a study at the LHC by utilizing a representative model with a new scalar field ($S$) coupled to the Standard Model Higgs doublet ($H$) in a form $|S{|}^2|H{|}^2$. In the process $pp\to h^{\ast }\to ZZ$, the dominant momentum-dependent part of the one-loop scalar singlet corrections, especially above the new threshold at $2m_S$, leads to a measurable deviation in the differential distribution of the $Z$-pair invariant mass, in accordance with the quadratic divergence cancellation to the Higgs mass. We find that it is conceivable to probe such new physics at the $5\sigma$ level at the high-luminosity LHC, improving further with the upgraded $27$ TeV LHC, without requiring the precise measurement of the Higgs boson total width. The discovery of such a Higgs portal could also have important implications for thermal dark matter as well as for electroweak baryogenesis.

    hep-phhep-exPRL(2018)·43 citations
20. 20*

    On the Role of Neutrinos Telescopes in the Search for Dark Matter Annihilations in the Sun

    Nicolao Fornengo🇮🇹 · Antonio Masiero🇮🇹 · Farinaldo S. Queiroz🇩🇪 · Carlos E. Yaguna🇨🇴

    The observation of GeV neutrinos coming from the Sun would be an unmistakable signal of dark matter. Current neutrino detectors have so far failed to detect such a signal, however, and bounds from direct and indirect dark matter searches may significantly restrict the possibility of observing it in future experiments such as Hyper-Kamiokande or IceCube-Gen2. In this work, we assess in the light of current data and of expected experimental sensitivities, the prospects for the detection of a neutrino signal from dark matter annihilations in the Sun. To be as general as possible, equilibrium between the capture and the annihilation rates in the Sun is not assumed in our analysis; instead, the dark matter scattering and annihilation cross sections are taken as free and independent parameters. We consider capture via both spin-dependent and spin-independent interactions, and annihilations into three representative final states: $b\bar{b}$, $W^{+}{W}^{-}$, and ${\tau }^{+}{\tau }^{-}$. We find that when the capture in the Sun is dominated by spin-independent interactions, current direct detection bounds already preclude the observation of a neutrino signal in future experiments. For capture via spin-dependent interactions, a strong complementarity is observed, over most of the parameter space, between future neutrino detectors and planned direct and indirect dark matter detection experiments, such as PICO-500 and CTA. In this case, we also identify some regions of the parameter space that can be probed, via the neutrino flux from the Sun, only by future neutrino experiments.

    hep-phastro-ph.HEhep-exJCAP(2017)·13 citations
21. 21*

    Symmetry and Emergence

    Edward Witten🇺🇸

    I discuss gauge and global symmetries in particle physics, condensed matter physics, and quantum gravity. In a modern understanding, global symmetries are approximate and gauge symmetries may be emergent. (Based on a lecture at the April, 2016 meeting of the American Physical Society in Salt Lake City, Utah.)

    ↳ hep-thcond-mat.otherhep-phNat.Phys.(2018)·117 citations
22. 22*

    Search for New Physics with Atoms and Molecules

    M.S. Safronova🇺🇸 · D. Budker🇩🇪 · D. DeMille🇺🇸 · Derek F. Jackson Kimball🇺🇸 · A. Derevianko🇺🇸 · C. W. Clark🇺🇸

    This article reviews recent developments in tests of fundamental physics using atoms and molecules, including the subjects of parity violation, searches for permanent electric dipole moments, tests of the CPT theorem and Lorentz symmetry, searches for spatiotemporal variation of fundamental constants, tests of quantum electrodynamics, tests of general relativity and the equivalence principle, searches for dark matter, dark energy and extra forces, and tests of the spin-statistics theorem. Key results are presented in the context of potential new physics and in the broader context of similar investigations in other fields. Ongoing and future experiments of the next decade are discussed.

    ↳ physics.atom-phhep-phRMP(2018)·1245 citations
23. 23*

    A study of how the particle spectra of SU(N) gauge theories with a fundamental Higgs emerge

    Axel Maas🇦🇹 · René Sondenheimer🇩🇪 · Pascal Törek🇦🇹

    In gauge theories, the physical, experimentally observable spectrum consists only of gauge-invariant states. In the standard model the Fröhlich-Morchio-Strocchi mechanism shows that these states can be adequately mapped to the gauge-dependent elementary W, Z, Higgs, and fermions. In theories with a more general gauge group and Higgs sector, appearing in various extensions of the standard model, this has not to be the case. In this work we determine analytically the physical spectrum of $\mathrm{SU}(N>2)$ gauge theories with a Higgs field in the fundamental representation. We show that discrepancies between the spectrum predicted by perturbation theory and the observable physical spectrum arise. We confirm these analytic findings with lattice simulations for $N=3$.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·14 citations
24. 24*

    3D simulations with boosted primordial power spectra and ultracompact minihalos

    Mateja Gosenca🇬🇧 · Julian Adamek🇫🇷 · Christian T. Byrnes🇬🇧 · Shaun Hotchkiss🇬🇧

    We perform three-dimensional simulations of structure formation in the early Universe, when boosting the primordial power spectrum on approximately kpc scales. We demonstrate that our simulations are capable of producing power-law profiles close to the steep $\rho \propto r^{-9/4}$ halo profiles that are commonly assumed to be a good approximation to ultracompact minihalos (UCMHs). However, we show that for more realistic initial conditions in which halos are neither perfectly symmetric nor isolated, the steep power-law profile is disrupted and we find that the Navarro-Frenk-White profile is a better fit to most halos. In the presence of background fluctuations even extreme, nearly spherical initial conditions do not remain exceptional. Nonetheless, boosting the amplitude of initial fluctuations causes all structures to form earlier and thus at larger densities. With sufficiently large amplitude of fluctuations we find that values for the concentration of typical halos in our simulations can become very large. However, despite the signal coming from dark matter annihilation inside the cores of these halos being enhanced, it is still orders-of-magnitude smaller compared to the usually assumed UCMH profile. The upper bound on the primordial power spectrum from the non-observation of UCMHs should therefore be re-evaluated.

    ↳ astro-ph.COhep-phPRD(2017)·59 citations
25. 25*

    Beyond standard models in cosmology (In French)

    Erwan Allys🇫🇷

    The current description of fundamental interactions is based on two theories with the status of standard models. The electromagnetic and nuclear interactions are described at a quantum level by the Standard Model of particle physics, using tools like gauge theories and spontaneous symmetry breaking by the Higgs mechanism. The gravitational interaction is described on the other hand by general relativity, based on a dynamical description of space-time at a classical level. Although these models are verified to high precision in the solar system experiments, they suffer from several theoretical weaknesses and a lack of predictive power at the Planck scale as well as at cosmological scales; they are thus not viewed anymore as fundamental theories. As its phenomenology involves both these extreme scales, cosmology is then a good laboratory to probe theories going beyond these standard models. The first part of this thesis focus on cosmic strings, topological defects forming during the spontaneous symmetry breaking of grand unified theories in the early universe. I show especially how to study these defects while taking into account the complete structure of the particles physics models leading to their formation, going beyond the standard descriptions in terms of simplified toy-models. The second part is devoted to the construction and the examination of different theories of modified gravity related to the Galileon model, a model which tries in particular to explain the dark energy phenomenology.

    ↳ astro-ph.COgr-qchep-phhep-th4 citations
26. 26*

    Helioseismic and Neutrino Data Driven Reconstruction of Solar Properties

    Ningqiang Song🇺🇸 · M.C. Gonzalez-Garcia🇪🇸 · Francesco L. Villante🇮🇹 · Nuria Vinyoles🇪🇸 · Aldo Serenelli🇪🇸

    In this work we use Bayesian inference to quantitatively reconstruct the solar properties most relevant to the solar composition problem using as inputs the information provided by helioseismic and solar neutrino data. In particular, we use a Gaussian process to model the functional shape of the opacity uncertainty to gain flexibility and become as free as possible from prejudice in this regard. With these tools we first readdress the statistical significance of the solar composition problem. Furthermore, starting from a composition unbiased set of standard solar models we are able to statistically select those with solar chemical composition and other solar inputs which better describe the helioseismic and neutrino observations. In particular, we are able to reconstruct the solar opacity profile in a data driven fashion, independently of any reference opacity tables, obtaining a 4% uncertainty at the base of the convective envelope and 0.8% at the solar core. When systematic uncertainties are included, results are 7.5% and 2% respectively. In addition we find that the values of most of the other inputs of the standard solar models required to better describe the helioseismic and neutrino data are in good agreement with those adopted as the standard priors, with the exception of the astrophysical factor $S_{11}$ and the microscopic diffusion rates, for which data suggests a 1% and 30% reduction respectively. As an output of the study we derive the corresponding data driven predictions for the solar neutrino fluxes.

    ↳ astro-ph.SRhep-phMNRAS(2018)·13 citations
27. 27*

    A Vacuum Phase Transition Solves $H_0$ Tension

    Eleonora Di Valentino🇬🇧 · Eric Linder🇺🇸 · Alessandro Melchiorri🇮🇹

    Taking the Planck cosmic microwave background data and the more direct Hubble constant measurement data as unaffected by systematic offsets, the values of the Hubble constant $H_0$ interpreted within the $\Lambda$CDM cosmological constant and cold dark matter cosmological model are in $\sim 3.3\sigma$ tension. We show that the Parker vacuum metamorphosis model, physically motivated by quantum gravitational effects and with the same number of parameters as $\Lambda$CDM, can remove the $H_0$ tension, and can give an improved fit to data (up to $\Delta {\chi }^2=-7.5$). It also ameliorates tensions with weak lensing data and the high redshift Lyman alpha forest data. We separately consider a scale dependent scaling of the gravitational lensing amplitude, such as provided by modified gravity, neutrino mass, or cold dark energy, motivated by the somewhat different cosmological parameter estimates for low and high CMB multipoles. We find that no such scale dependence is preferred.

    ↳ astro-ph.COgr-qchep-phPRD(2018)·201 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.