Tue·Jun 13, 2017Tuesday·June 13, 2017

1. 01*

   Thermal dark matter via the flavon portal

   Carlos Alvarado🇺🇸 · Fatemeh Elahi🇺🇸 · Nirmal Raj🇺🇸

   Dark matter (DM) is added to the Froggatt-Nielsen (FN) mechanism, and conditions for its successful freezeout identified. Requesting the FN scale ${\Lambda }_{\text{FN}}$ to be the cutoff of the theory renders freezeout scenarios surprisingly few. Fermionic DM is typically charged under $U(1{)}_{\text{FN}}$, with the dominant annihilation channel a CP-even flavon + CP-odd flavon. A minimal case is when the DM-flavon coupling strength is $\mathcal{O}(1)$, with several implications: (1) the DM mass is $\mathcal{O}$(100 GeV - 1 TeV), thanks to the WIMP coincidence, (2) requiring perturbativity of couplings puts a lower $and$ upper limit on the flavor scale, 2 TeV $\lesssim {\Lambda }_{\text{FN}}\lesssim 14$TeV, on account of its relation to DM mass and couplings, (3) DM is a "secluded WIMP" effectively hidden from collider and direct detection searches. Limits on the masses of dark matter and mediators from kaon mixing measurements constitute the best constraints, surpassing Xenon1T, Fermi-LAT, and the LHC. Future direct detection searches, and collider searches for missing energy plus a single jet/bottom/top, are promising avenues for discovery.

   hep-phPRD(2017)·8 citations
2. 02*

   A Model of Comprehensive Unification

   Mario Reig🇪🇸 · José W.F. Valle🇪🇸 · C.A. Vaquera-Araujo🇪🇸 · Frank Wilczek🇺🇸

   Comprehensive - that is, gauge and family - unification using spinors has many attractive features, but it has been challenged to explain chirality. Here, by combining an orbifold construction with more traditional ideas, we address that difficulty. Our candidate model features three chiral families and leads to an acceptable result for quantitative unification of couplings. A potential target for accelerator and astronomical searches emerges.

   hep-phhep-thPLB(2017)·30 citations
3. 03*

   QCD predictions for the azimuthal asymmetry in charm leptoproduction for the COMPASS kinematics

   A.V. Efremov🇷🇺 · N.Ya. Ivanov🇦🇲 · O.V. Teryaev🇷🇺

   We present the QCD predictions for the azimuthal $\cos 2\phi$ asymmetry in charm leptoproduction for the kinematics of the COMPASS experiment at CERN. The asymmetry is predicted to be large, about 15%. The radiative corrections to the QCD predictions for the $\cos 2\phi$ distribution are estimated to be small, less than 10%. Our calculations show that the azimuthal asymmetry in charm production is well defined in pQCD: it is stable both perturbatively and parametrically, and practically insensitive to theoretical uncertainties in the input parameters. We analyze the nonperturbative contributions to the $\cos 2\phi$ distribution due to the gluon transverse motion in the target and the $c$-quark fragmentation. Because of the $c$-quark low mass, the nonperturbative contributions are expected to be sizable, about (30--40)%. We conclude that extraction of the azimuthal asymmetries from available COMPASS data will provide valuable information about the transverse momentum dependent distribution of the gluon in the proton and the $c$-quark hadronization mechanism. Finally, we discuss the $\cos 2\phi$ asymmetry as a probe of the gluonic analogue of the Boer-Mulders function, $h_1^{\perp g}$, describing the linear polarization of gluons inside unpolarized proton.

   hep-phPLB(2017)·7 citations
4. 04*

   Standard model effective potential from trace anomalies

   Renata Jora🇷🇴

   By analogy with the low energy QCD effective linear sigma model we construct a standard model effective potential based entirely on the requirement that the tree level and quantum level trace anomalies must be satisfied. We discuss a particular realization of this potential in connection to the Higgs boson mass and Higgs boson effective couplings to two photons and two gluons. We find that this kind of potential may describe well the knwon phenomenology of the Higgs boson.

   hep-phAdv.High Energy Phys.(2018)·0 citations
5. 05*

   Implications of texture zeros for a variant of tribimaximal Mixing

   Sanjeev Kumar🇮🇳 · Radha Raman Gautam🇮🇳

   We study the phenomenological implications of the presence of two texture zeros in the neutrino mass matrix assuming that the neutrino mixing matrix has its first column identical to that of the tribimaximal mixing matrix. Only two patterns of this kind are compatible with the experimental data. These textures have definite predictions for the neutrino observables that are testable in future neutrino experiments.

   hep-phPRD(2017)·12 citations
6. 06*

   Transverse polarization of the $\Lambda$ hyperon from unpolarized quark fragmentation in the diquark model

   Yongliang Yang🇨🇳 · Zhun Lu🇨🇳 · Ivan Schmidt🇨🇱

   We investigate the spin-dependent (naive) T-odd fragmentation function $D_{1T}^{\perp }$, which can provide an explanation on the transverse polarization of the ${\Lambda }^0$ hyperon produced in an unpolarized process. We calculate $D_{1T}^{\perp }$ for light flavors in the spectator diquark model, with a Gaussian form factor at the hyperon-quark-diquark vertex. We include in the calculation both the scalar diquark and axial-vector diquark spectators. We determine the values of the model parameters by fitting the unpolarized fragmentation function $D_1^{\Lambda }$ to the DSV parametrization for $D_1^{\Lambda }$. In addition, we compute the longitudinal polarization fragmentation function $G_1^{\Lambda }$ and compare it with the known parametrization of $G_1^{\Lambda }$. We also estimate the transverse polarizations of $\Lambda$ production, in both semi-inclusive deep inelastic scattering and single inclusive $e^{+}{e}^{-}$ annihilation.

   hep-phhep-exPRD(2017)·22 citations
7. 07*

   Fast flavor conversions of supernova neutrinos: Classifying instabilities via dispersion relations

   Francesco Capozzi (1)🇺🇸 · Basudeb Dasgupta (2)🇮🇳 · Eligio Lisi (3)🇮🇹 · Antonio Marrone (3,4)🇮🇹 · Alessandro Mirizzi (3,4) ((1) Ohio State U., (2) TIFR, (3) INFN (4) Bari U.)🇮🇹

   Supernova neutrinos can exhibit a rich variety of flavor conversion mechanisms. In particular, they can experience "fast" self-induced flavor conversions almost immediately above the core. Very recently, a novel method has been proposed to investigate these phenomena, in terms of the dispersion relation for the complex frequency and wave number ($\omega$,$k$) of disturbances in the mean field of the ${\nu }_e{\nu }_x$ flavor coherence. We discuss a systematic approach to such instabilities, originally developed in the context of plasma physics, and based of the time-asymptotic behavior of the Green's function of the system. Instabilities are typically seen to emerge for complex $\omega$, and can be further characterized as convective (moving away faster than they spread) and absolute (growing locally), depending on $k$-dependent features. Stable cases emerge when $k$ (but not $\omega$) is complex, leading to disturbances damped in space, or when both $\omega$ and $k$ are real, corresponding to complete stability. The analytical classification of both unstable and stable modes leads not only to qualitative insights about their features but also to quantitative predictions about the growth rates of instabilities. Representative numerical solutions are discussed in a simple two-beam model of interacting neutrinos. As an application, we argue that supernova and binary neutron star mergers exhibiting a "crossing" in the electron lepton number would lead to an absolute instability in the flavor content of the neutrino gas.

   hep-phPRD(2017)·117 citations
8. 08*

   Testing CPT violation with correlated neutral mesons

   Agnes Roberts🇺🇸

   This work gives a general overview of phenomenology developed for neutral-meson searches for CPT violation in the framework of the Standard-Model Extension with focus on meson factories. It gives a comparison of notations and fundamental approach in the formalism used by the different experiments. Asymmetries and possible experimental investigations are presented for tests of the momentum-dependent phenomenological parameter of CPT violation in neutral-meson oscillations. The general results apply to any mesons produced as correlated meson pairs and addresses the issue of decoherence as a consequence of direction dependence. An analysis is given considering kinematics and orientation of the improved Belle II experiment.

   hep-phPRD(2017)·17 citations
9. 09*

   Beam polarization effects on top-pair production at the ILC

   Nhi M. U. Quach🇯🇵 · Yoshimasa Kurihara🇯🇵 · Khiem H. Phan🇻🇳 · Takahiro Ueda🇳🇱

   Full one-loop electroweak-corrections for an $e^{-}{e}^{+}\to t\bar{t}$ process associated with sequential $t\to b\mu {\nu }_{\mu }$ decay are discussed. At the one-loop level, the spin-polarization effects of the initial electron and positron beams are included in the total and differential cross sections. A narrow-width approximation is used to treat the top-quark production and decay while including full spin correlations between them. We observed that the radiative corrections due to the weak interaction have a large polarization dependence on both the total and differential cross sections. Therefore, experimental observables that depend on angular distributions such as the forward-backward asymmetry of the top production angle must be treated carefully including radiative corrections. We also observed that the energy distribution of bottom quarks is majorly affected by the radiative corrections.

   hep-phEPJC(2018)·4 citations
10. 10*

    Gauge-Higgs Seesaw Mechanism in Six-Dimensional Grand Unification

    Yutaka Hosotani🇯🇵 · Naoki Yamatsu🇯🇵

    $SO(11)$ gauge-Higgs grand unification is formulated in the six-dimensional hybrid warped space in which the fifth and sixth dimensions play as the electroweak and grand-unification dimensions. Fermions are introduced in $32$, $11$ and $1$ of $SO(11)$. Small neutrino masses naturally emerge as a result of a new seesaw mechanism in the gauge-Higgs unification which is characterized by a $3\times 3$ mass matrix.

    hep-phhep-thPTEP(2017)·37 citations
11. 11*

    NLO QCD+EW predictions for HV and HV+jet production including parton-shower effects

    Federico Granata🇮🇹 · Jonas M. Lindert🇬🇧 · Carlo Oleari🇮🇹 · Stefano Pozzorini🇨🇭

    We present the first NLO QCD+EW predictions for Higgs boson production in association with a l nu or l+ l- pair plus zero or one jets at the LHC. Fixed-order NLO QCD+EW calculations are combined with a QCD+QED parton shower using the recently developed resonance-aware method in the POWHEG framework. Moreover, applying the improved MINLO technique to H l nu and H l+ l- production at NLO QCD+EW, we obtain predictions that are NLO accurate for observables with both zero or one resolved jet. This approach permits also to capture higher-order effects associated with the interplay of EW corrections and QCD radiation. The behavior of EW corrections is studied for various kinematic distributions, relevant for experimental analyses of Higgsstrahlung processes at the 13 TeV LHC. Exact NLO EW corrections are complemented with approximate analytic formulae that account for the leading and next-to-leading Sudakov logarithms in the high-energy regime. In the tails of transverse-momentum distributions, relevant for analyses in the boosted Higgs regime, the Sudakov approximation works well, and NLO EW effects can largely exceed the ten percent level. Our predictions are based on the POWHEX BOX RES + OpenLoops framework in combination with the Pythia 8.1 parton shower.

    hep-phJHEP(2017)·83 citations
12. 12*

    Next-to-leading-order QCD corrections to $e^{+}{e}^{-}\to H+\gamma$

    Wen-Long Sang🇨🇳 · Wen Chen🇨🇳 · Feng Feng🇨🇳 · Yu Jia🇨🇳 · Qing-Feng Sun🇨🇳

    The associated production of Higgs boson with a hard photon at lepton collider, i.e., $e^{+}{e}^{-}\to H\gamma$, is known to bear a rather small cross section in Standard Model, and can serve as a sensitive probe for the potential new physics signals. Similar to the loop-induced Higgs decay channels $H\to \gamma \gamma ,Z\gamma$, the $e^{+}{e}^{-}\to H\gamma$ process also starts at one-loop order provided that the tiny electron mass is neglected. In this work, we calculate the next-to-leading-order (NLO) QCD corrections to this associated $H+\gamma$ production process, which mainly stem from the gluonic dressing to the top quark loop. The QCD corrections are found to be rather modest at lower center-of-mass energy range ($\sqrt{s}<300$ GeV), thus of negligible impact on Higgs factory such as CEPC. Nevertheless, when the energy is boosted to the ILC energy range ($\sqrt{s}\approx 400$ GeV), QCD corrections may enhance the leading-order cross section by $20\%$. In any event, the $e^{+}{e}^{-}\to H\gamma$ process has a maximal production rate ${\sigma }_{\max }\approx 0.08$ fb around $\sqrt{s}=250$ GeV, thus CEPC turns out to be the best place to look for this rare Higgs production process. In the high energy limit, the effect of NLO QCD corrections become completely negligible, which can be simply attributed to the different asymptotic scaling behaviors of the LO and NLO cross sections, where the former exhibits a milder decrement $\propto 1/s$ , but the latter undergoes a much faster decrease $\propto 1/s^2$.

    hep-phhep-exPLB(2017)·6 citations
13. 13*

    NuSTEC White Paper: Status and Challenges of Neutrino-Nucleus Scattering

    L. Alvarez-Ruso🇪🇸 · M. Sajjad Athar🇮🇳 · M. B. Barbaro🇮🇹 · D. Cherdack🇺🇸 · M. E. Christy🇺🇸 · P. Coloma🇺🇸 · T. W. Donnelly🇺🇸 · S. Dytman🇺🇸 · A. de Gouvêa🇺🇸 · R. J. Hill🇺🇸 · P. Huber🇺🇸 · N. Jachowicz🇧🇪 and 13 other authors

    The precise measurement of neutrino properties is among the highest priorities in fundamental particle physics, involving many experiments worldwide. Since the experiments rely on the interactions of neutrinos with bound nucleons inside atomic nuclei, the planned advances in the scope and precision of these experiments requires a commensurate effort in the understanding and modeling of the hadronic and nuclear physics of these interactions, which is incorporated as a nuclear model in neutrino event generators. This model is essential to every phase of experimental analyses and its theoretical uncertainties play an important role in interpreting every result. In this White Paper we discuss in detail the impact of neutrino-nucleus interactions, especially the nuclear effects, on the measurement of neutrino properties using the determination of oscillation parameters as a central example. After an Executive Summary and a concise Overview of the issues, we explain how the neutrino event generators work, what can be learned from electron-nucleus interactions and how each underlying physics process - from quasi-elastic to deep inelastic scattering - is understood today. We then emphasize how our understanding must improve to meet the demands of future experiments. With every topic we find that the challenges can be met only with the active support and collaboration among specialists in strong interactions and electroweak physics that include theorists and experimentalists from both the nuclear and high energy physics communities.

    hep-phPPNP(2018)·505 citations
14. 14*

    Investigating the collision energy dependence of $\eta$/s in RHIC beam energy scan using Bayesian statistics

    Jussi Auvinen🇺🇸 · Iurii Karpenko🇮🇹 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸

    We determine the probability distributions of shear viscosity over the entropy density ratio $\eta /s$ in Au+Au collisions at $\sqrt{s_{NN}}=19.6,39$, and $62.4$ GeV, using Bayesian inference and Gaussian process emulators for a model-to-data statistical analysis that probes the full input parameter space of a transport+viscous hydrodynamics hybrid model. We find the most likely value of $\eta /s$ to be larger at smaller $\sqrt{s_{NN}}$, although the uncertainties still allow for a constant value between 0.10 and 0.15 for the investigated collision energy range.

    hep-phPRC(2018)·69 citations
15. 15*

    Determination of the NNLO low-energy constant $C_{93}$

    Maarten Golterman🇺🇸 · Kim Maltman🇨🇦 · Santiago Peris🇪🇸

    Experimental data from hadronic $\tau$ decays allow for a precision determination of the slope of the $I=1$ vacuum polarization at zero momentum. We use this information to provide a value for the next-to-next-to-leading order (NNLO) low-energy constant $C_{93}$ in chiral perturbation theory. The largest systematic error in this determination results from the neglect of terms beyond NNLO in the effective chiral Lagrangian, whose presence in the data will, in general, make the effective $C_{93}$ determined in an NNLO analysis mass dependent. We estimate the size of this effect by using strange hadronic $\tau$-decay data to perform an alternate $C_{93}$ determination based on the slope of the strange vector polarization at zero momentum, which differs from that of the $I=1$ vector channel only through $SU(3)$ flavor-breaking effects. We also comment on the impact of such higher order effects on ChPT-based estimates for the hadronic vacuum polarization contribution to the muon anomalous magnetic moment.

    hep-phhep-latPRD(2017)·6 citations
16. 16*

    Compilation of low-energy constraints on 4-fermion operators in the SMEFT

    Adam Falkowski🇫🇷 · Martín González-Alonso🇫🇷 · Kin Mimouni🇨🇭

    We compile information from low-energy observables sensitive to flavor-conserving 4-fermion operators with two or four leptons. Our analysis includes data from e+e- colliders, neutrino scattering on electron or nucleon targets, atomic parity violation, parity-violating electron scattering, and the decay of pions, neutrons, nuclei and tau leptons. We recast these data as tree-level constraints on 4-fermion operators in the Standard Model Effective Field Theory (SMEFT) where the SM Lagrangian is extended by dimension-6 operators. We allow all independent dimension-6 operators to be simultaneously present with an arbitrary flavor structure. The results are presented as a multi-dimensional likelihood function in the space of dimension-6 Wilson coefficients, which retains information about the correlations. In this form, the results can be readily used to place limits on masses and couplings in a large class of new physics theories.

    hep-phhep-exJHEP(2017)·203 citations
17. 17*

    Heavy Quarks in Turbulent QCD Plasmas

    Stanislaw Mrowczynski🇵🇱

    The quark-gluon plasma, which is produced at an early stage of ultrarelativistic heavy-ion collisions, is expected to be initially strongly populated with chromodynamic fields. We address the question how heavy quarks interact with such a turbulent plasma in comparison with an equilibrated one of the same energy density. For this purpose we derive a Fokker-Planck transport equation of heavy quarks embedded in a plasma of light quarks and gluons. We first discuss the equilibrium plasma and then the turbulent one applying the same approach, where the heavy quarks interact not with the plasma constituents but rather with the long wavelength classical fields. We first consider the three schematic models of isotropic trubulent plasma and then the simplified model of glasma with the chromodynamic fields only along the beam direction. The momentum broadening and collisional energy loss of a test heavy quark are computed and compared to those of equilibrium plasma of the same energy density.

    ↳ nucl-thhep-phEPJA(2018)·57 citations
18. 18*

    The Spectrum of the Axion Dark Sector

    Matthew J. Stott🇬🇧 · David J. E. Marsh🇬🇧 · Chakrit Pongkitivanichkul🇬🇧 · Layne C. Price🇺🇸 · Bobby S. Acharya🇬🇧

    Axions arise in many theoretical extensions of the Standard Model of particle physics, in particular the "string axiverse". If the axion masses, $m_a$, and (effective) decay constants, $f_a$, lie in specific ranges, then axions contribute to the cosmological dark matter and dark energy densities. We compute the background cosmological (quasi-)observables for models with a large number of axion fields, $n_{\mathrm{ax}}\sim \mathcal{O}(10-100)$, with the masses and decay constants drawn from statistical distributions. This reduces the number of parameters from $2n_{\mathrm{ax}}$ to a small number of "hyperparameters". We consider a number of distributions, from those motivated purely by statistical considerations, to those where the structure is specified according to a class of M-theory models. Using Bayesian methods we are able to constrain the hyperparameters of the distributions. In some cases the hyperparameters can be related to string theory, e.g. constraining the number ratio of axions to moduli, or the typical decay constant scale needed to provide the correct relic densities. Our methodology incorporates the use of both random matrix theory and Bayesian networks.

    ↳ astro-ph.COhep-phhep-thPRD(2017)·69 citations
19. 19*

    Six indications of radical new physics in supernovae Ia

    L. Clavelli🇺🇸

    After more than forty years since the basic standard model for supernovae Ia was proposed many astronomers are still hopeful that this phenomenon will ultimately be understood in terms of Newtonian gravity plus nuclear and particle physics as they existed in the 1930's. In spite of this fact there are at least six nagging puzzles in supernova physics that suggest some radical new physics input may be necessary. "Radical" in this context means a physics idea that did not exist in the 1930's and that is still not experimentally confirmed in 2017.

    ↳ astro-ph.HEhep-phhep-thInt.J.Mod.Phys.A(2017)·2 citations
20. 20*

    Gaugid inflation

    Federico Piazza🇫🇷 · David Pirtskhalava🇨🇭 · Riccardo Rattazzi🇨🇭 · Olivier Simon🇨🇭

    The spectrum of primordial gravitational waves is one of the most robust inflationary observables, often thought of as a direct probe of the energy scale of inflation. We present a simple model, where the dynamics controlling this observable is very different than in the standard paradigm of inflation. The model is based on a peculiar finite density phase---the magnetic gaugid---which stems from a highly non-linear effective theory of a triplet of abelian gauge fields. The gaugid extends the notion of homogeneous isotropic solid, in that its spectrum of fluctuations includes helicity-2 phonons. We show how, upon implementing the gaugid to drive inflation, the helicity-2 phonon mixes with the graviton, significantly affecting the size of the primordial tensor spectrum. The rest of the features of the theory, in particular the vector and scalar perturbations, closely resemble those of solid inflation.

    ↳ hep-thastro-ph.COhep-phJCAP(2017)·30 citations
21. 21*

    The localization transition in SU(3) gauge theory

    Tamas G. Kovacs (1)🇭🇺 · Reka A Vig (1) ((1) Debrecen, Inst. Nucl. Res.)🇭🇺

    We study the Anderson-like localization transition in the spectrum of the Dirac operator of quenched QCD. Above the deconfining transition we determine the temperature dependence of the mobility edge separating localized and delocalized eigenmodes in the spectrum. We show that the temperature where the mobility edge vanishes and localized modes disappear from the spectrum, coincides with the critical temperature of the deconfining transition. We also identify topological charge related close to zero modes in the Dirac spectrum and show that they account for only a small fraction of localized modes, a fraction that is rapidly falling as the temperature increases.

    ↳ hep-latcond-mat.dis-nnhep-phPRD(2018)·40 citations
22. 22*

    Extraction of $|V_{cd}|$ and $|V_{cs}|$ from experimental decay rates using lattice QCD $D\to \pi (K)\ell \nu$ form factors

    L. Riggio🇮🇹 · G. Salerno🇮🇹 · S. Simula🇮🇹

    We present a determination of the Cabibbo-Kobayashi-Maskawa matrix elements $|V_{cd}|$ and $|V_{cs}|$ obtained by combining the momentum dependence of the semileptonic vector form factors $f_{+}^{D\to \pi }(q^2)$ and $f_{+}^{D\to K}(q^2)$, recently determined from lattice QCD simulations, with the differential rates measured for the semileptonic $D\to \pi \ell \nu$ and $D\to K\ell \nu$ decays. Our analysis is based on the results for the semileptonic form factors produced by the European Twisted Mass Collaboration with $N_f=2+1+1$ flavors of dynamical quarks in the whole range of values of the squared 4-momentum transfer accessible in the experiments. The statistical and systematic correlations between the lattice data as well as those present in the experimental data are properly taken into account. With respect to the standard procedure based on the use of only the vector form factor at zero 4-momentum transfer, we obtain more precise and consistent results: $|V_{cd}|=0.2341(74)$ and $|V_{cs}|=0.970(33)$. The second-row CKM unitarity is fulfilled within the current uncertainties: $|V_{cd}{|}^2+|V_{cs}{|}^2+|V_{cb}{|}^2=0.996(64)$. Moreover, using for the first time hadronic inputs determined from first principles, we have calculated the ratio of the semileptonic $D\to \pi (K)$ decay rates into muons and electrons, which represent a test of lepton universality within the SM, obtaining in the isospin-symmetric limit of QCD: ${\mathcal{R}}_{LU}^{D\pi }=0.985(2)$ and ${\mathcal{R}}_{LU}^{DK}=0.975(1)$.

    ↳ hep-lathep-exhep-phEPJC(2018)·64 citations
23. 23*

    Refined Holonomic Summation Algorithms in Particle Physics

    Johannes Blümlein🇩🇪 · Mark Round🇦🇹 · Carsten Schneider🇦🇹

    An improved multi-summation approach is introduced and discussed that enables one to simultaneously handle indefinite nested sums and products in the setting of difference rings and holonomic sequences. Relevant mathematics is reviewed and the underlying advanced difference ring machinery is elaborated upon. The flexibility of this new toolbox contributed substantially to evaluating complicated multi-sums coming from particle physics. Illustrative examples of the functionality of the new software package RhoSum are given.

    ↳ cs.SChep-phSpringer Proc.Math.Stat.(2018)·9 citations
24. 24*

    Discriminating Local Sources of High-Energy Cosmic Electrons and Positrons by Current and Future Anisotropy Measurements

    Kun Fang🇨🇳 · Xiao-Jun Bi🇨🇳 · Peng-fei Yin🇨🇳

    The Fermi-LAT detects no significant anisotropy of the cosmic-ray (CR) electrons and positrons ($e^{-}+e^{+}$) with seven years of data, which provides the strongest restriction to the $e^{-}+e^{+}$ anisotropy up to now. As next generation CR observatory, HERD is expected to have a better capability of anisotropy detection than Fermi-LAT. In this paper, we discuss several models aimed to explain the AMS-02 data by the present and future anisotropy measurements. We find that the upper limits of Fermi-LAT disfavor Vela SNR as the dominant source in sub-TeV, while other cases that remain safe under the constraint of Fermi-LAT are expected to be distinguished from each other by HERD. We then discuss the possibilities of remarkable TeV spectral features, and test the corresponding anisotropies. We find the conditions under which the TeV model can have a prominent spectral feature and avoid the constraint of Fermi-LAT at the same time. Furthermore, the expected performance of HERD is sensitive enough to detect the anisotropies of all these TeV models, and even for the case of a featureless TeV spectrum. Thus HERD may play a crucial part in the study of the origin of cosmic electrons and positrons.

    ↳ astro-ph.HEhep-phMNRAS(2018)·15 citations
25. 25*

    Primordial black holes from inflaton and spectator field perturbations in a matter-dominated era

    Bernard Carr🇬🇧 · Tommi Tenkanen🇬🇧 · Ville Vaskonen🇪🇪

    We study production of primordial black holes (PBHs) during an early matter-dominated phase. As a source of perturbations, we consider either the inflaton field with a running spectral index or a spectator field that has a blue spectrum and thus provides a significant contribution to the PBH production at small scales. First, we identify the region of the parameter space where a significant fraction of the observed dark matter can be produced, taking into account all current PBH constraints. Then, we present constraints on the amplitude and spectral index of the spectator field as a function of the reheating temperature. We also derive constraints on the running of the inflaton spectral index, $\mathrm{d}n/\mathrm{d}\ln k\lesssim -0.002$, which are comparable to those from the Planck satellite for a scenario where the spectator field is absent.

    ↳ astro-ph.COhep-phPRD(2017)·139 citations
26. 26*

    A Novel Foamy Origin for Singlet Fermion Masses

    John Ellis🇬🇧 · Nick E. Mavromatos🇬🇧 · Dimitri V. Nanopoulos🇺🇸

    We show how masses for singlet fermions can be generated by interactions with a D-particle model of space-time foam inspired by brane theory. It has been shown previously by one of the authors (N.E.M.) such interactions may generate generate dynamically small masses for charged fermions via the recoils of D-particle defects interacting with photons. In this work we consider the direct interactions of D-particle with uncharged singlet fermions such as right-handed neutrinos. Quantum fluctuations of the lattice of D-particles have massless vector (spin-one) excitations that are analogues of phonons. These mediate forces between the singlet fermions, generating large dynamical masses that may be communicated to light neutrinos via the seesaw mechanism.

    ↳ gr-qchep-phhep-thPRD(2017)·3 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.