Mon·Apr 16, 2018Monday·April 16, 2018

1. 01*

   Separation Of Edge Effects In Highly Non-Dipole Radiation Spectra

   M.V. Bondarenco🇺🇦

   Edge effects in spectra of non-dipole radiation from ultra-relativistic electrons passing through various finite targets are analyzed from a unified point of view. Examples include radiation in a finite magnet, bremsstrahlung at double scattering, and bremsstrahlung in an amorphous plate. A generalization of the encountered spectral decomposition property is proposed. The relevance of phenomena of jet-interjet radiation interference and electron time delay in the target is emphasized. Features produced by them in the radiation spectra are discussed.

   hep-phMod.Phys.Lett.A(2018)·1 citation
2. 02*

   Towards a complete study of central exclusive production of $K^{+}{K}^{-}$ pairs in proton-proton collisions within the tensor Pomeron approach

   Piotr Lebiedowicz🇵🇱 · Otto Nachtmann🇩🇪 · Antoni Szczurek🇵🇱

   We present a study of the central exclusive production of the $K^{+}{K}^{-}$ pairs in proton-proton collisions at high energies. We consider diffractive mechanisms including the $K^{+}{K}^{-}$ continuum, the dominant scalar $f_0(980)$, $f_0(1500)$, $f_0(1710)$ and tensor $f_2(1270)$, $f_2^{\prime }(1525)$ resonances decaying into the $K^{+}{K}^{-}$ pairs. We include also photoproduction mechanisms for the non-resonant (Drell-Söding) and the $\varphi (1020)$ resonance contributions. The theoretical results are calculated within the tensor-pomeron approach including both pomeron and reggeon exchanges. Predictions for planned or current experiments at RHIC and LHC are presented. We discuss the influence of the experimental cuts on the integrated cross section and on various differential distributions for outgoing particles. The distributions in two-kaon invariant mass, in a special `glueball filter variable', as well as examples of angular distributions in the $K^{+}{K}^{-}$ rest frame are presented. We compare the $\varphi (1020)$ and continuum photoproduction contributions to the $f_0(980)$ and continuum diffractive contributions and discuss whether the $\varphi (1020)$ resonance could be extracted experimentally. For the determination of some model parameters we also include a discussion of $K$-nucleon scattering, in particular total cross sections, and of $\varphi (1020)$ photoproduction.

   hep-phPRD(2018)·45 citations
3. 03*

   Inflation from a No-scale supersymmetric $SU(4{)}_c\times SU(2{)}_L\times SU(2{)}_R$ model

   Waqas Ahmed🇨🇳 · Athanasios Karozas🇬🇷

   We study inflation in a supersymmetric Pati-Salam model driven by a potential generated in the context of no-scale supergravity. The Pati-Salam gauge group $SU(4{)}_c\times SU(2{)}_L\times SU(2{)}_R$ , is supplemented with a $Z_2$ symmetry. Spontaneous breaking via the $SU(4)$ adjoint leads to the left-right symmetric group. Then the $SU(2{)}_R$ breaks at an intermediate scale and the inflaton is a combination of the neutral components of the $SU(2{)}_R$ doublets. We discuss various limits of the parameter space and we show that consistent solutions with the cosmological data for the a spectral index $n_s$ and the tensor-to-scalar ratio r are found for a wide range of the parameter space of the model. Regarding the latter, which is a canonical measure of primordial gravity waves, we find that $r\sim 10^{-3}-10^{-2}$. An alternative possibility where the adjoint scalar field $S$ has the role of the inflaton is also discussed.

   hep-phPRD(2018)·23 citations
4. 04*

   Semileptonic $B_{(s)}\to a_1(K_1){\ell }^{+}{\ell }^{-}$ decays via the light-cone sum rules with $B$-meson distribution amplitudes

   S. Momeni🇮🇷 · R. Khosravi🇮🇷

   The form factors of semileptonic $B_{(s)}\to a_1(K_1){\ell }^{+}{\ell }^{-}$, $\ell =\tau ,\mu ,e$ transitions are investigated in the framework of the light-cone sum rules with $B$-meson distribution amplitudes, which play an important role in exclusive $B$ decays. The $B$-meson distribution amplitudes, ${\phi }_{\pm }(\omega )$ are a model-dependent form, so we consider four different parameterizations which can provide a reasonable description of ${\phi }_{\pm }(\omega )$ from QCD corrections. The branching fractions of these transitions are calculated. For a better analysis, a comparison of our results with the prediction of other models is provided.

   hep-phPRD(2017)·6 citations
5. 05*

   Once more on the Higgs decay into two photons

   J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪

   We comment on the recently reiterated claim that the contribution of the W-boson loop to the Higgs boson decay into two photons leads to different expressions in the $R_{\xi }$ gauge and the unitary gauge. By applying a gauge-symmetry preserving regularization with higher-order covariant derivatives we reproduce once again the "classical" gauge-independent result.

   hep-phhep-thNPB(2018)·8 citations
6. 06*

   Analysis of ${\Lambda }_c(2595)$, ${\Lambda }_c(2625)$, ${\Lambda }_b(5912)$, ${\Lambda }_b(5920)$ based on a chiral partner structure

   Yohei Kawakami🇯🇵 · Masayasu Harada🇯🇵

   We construct an effective hadronic model including ${\Lambda }_c(2595)$, ${\Lambda }_c(2625)$, ${\Lambda }_b(5912)$ and ${\Lambda }_b(5920)$ regarding them as chiral partners to ${\Sigma }_c(2455)$, ${\Sigma }_c(2520)$, ${\Sigma }_b$ and ${\Sigma }_b^{\ast }$, respectively, with respecting the chiral symmetry and heavy-quark spin-flavor symmetry. We determine the model parameters from the experimental data for relevant masses and decay widths of ${\Sigma }_c^{(\ast )}$ and ${\Lambda }_c(2595)$. Then, we study the decay widths of ${\Lambda }_c(2625)$, ${\Lambda }_b(5912)$ and ${\Lambda }_b(5920)$. We find that, although the decay of ${\Lambda }_c(2595)$ is dominated by the resonant contribution through ${\Sigma }_c(2455)$, non-resonant contributions are important for ${\Lambda }_c(2625)$, ${\Lambda }_b(5912)$ and ${\Lambda }_b(5920)$, which reflects the chiral partner structure. We also study the radiative decays of the baryons, and show that each of their widths is determined from the radiative decay width of their chiral partners.

   hep-phnucl-thPRD(2018)·32 citations
7. 07*

   A Combined Astrophysical and Dark Matter Interpretation of the IceCube HESE and Throughgoing Muon Events

   Yicong Sui🇺🇸 · P. S. Bhupal Dev🇺🇸

   We perform a combined likelihood analysis for the IceCube 6-year high-energy starting events (HESE) and 8-year throughgoing muon events above 10 TeV using a two-component neutrino flux model. The two-component flux can be motivated either from purely astrophysical sources or due to a beyond Standard Model contribution, such as decaying heavy dark matter. We find that the astrophysical plus dark matter interpretation is mildly preferred by the current data over the purely astrophysical explanation. As for the astrophysical neutrinos, we consider two different source flavor compositions corresponding to the standard pion decay and muon-damped pion decay sources. We find that the latter is slightly preferred over the former as the high-energy component, while the low-energy component does not show any such preference. We also take into account the multi-messenger gamma-ray constraints and find that our two-component fit is compatible with these constraints, whereas the single-component power-law bestfit to the HESE data is ruled out. The astrophysical plus dark matter interpretation of the two-component flux is found to be mildly preferred by the current data and the gamma-ray constraints over the purely astrophysical explanation.

   hep-phastro-ph.HEJCAP(2018)·64 citations
8. 08*

   Stable Tetraquarks

   Chris Quigg🇺🇸

   For very heavy quarks, relations derived from heavy-quark symmetry imply novel narrow doubly heavy tetraquark states containing two heavy quarks and two light antiquarks. We predict that double-beauty states will be stable against strong decays, whereas the double-charm states and mixed beauty+charm states will dissociate into pairs of heavy-light mesons. Observing a new double-beauty state through its weak decays would establish the existence of tetraquarks and illuminate the role of heavy color-antitriplet diquarks as hadron constituents.

   hep-phhep-ex7 citations
9. 09*

   2HDM portal for Singlet-Doublet Dark Matter

   Giorgio Arcadi🇩🇪

   We present an extensive analysis of a model in which the (Majorana) Dark Matter candidate is a mixture between a SU(2) singlet and two SU(2) doublets. This kind of setup takes the name of singlet-doublet model. We will investigate in detail an extension of this model in which the Dark Matter sector interactions with a 2-doublet Higgs sector enforcing the complementarity between Dark Matter phenomenology and searches of extra Higgs bosons.

   hep-phEPJC(2018)·46 citations
10. 10*

    Radiative leptonic decay $B\to \gamma \ell {\nu }_{\ell }$ with subleading power corrections

    M. Beneke🇩🇪 · V. M. Braun🇩🇪 · Yao Ji🇩🇪 · Yan-Bing Wei🇨🇳

    We reconsider the QCD predictions for the radiative decay $B\to \gamma \ell {\nu }_{\ell }$ with an energetic photon in the final state by taking into account the $1/E_{\gamma },1/m_b$ power-suppressed hard-collinear and soft corrections from higher-twist $B$-meson light-cone distribution amplitudes (LCDAs). The soft contribution is estimated through a dispersion relation and light-cone QCD sum rules. The analysis of theoretical uncertainties and the dependence of the decay form factors on the leading-twist LCDA ${\varphi }_{+}(\omega )$ shows that the latter dominates. The radiative leptonic decay is therefore well suited to constrain the parameters of ${\varphi }_{+}(\omega )$, including the first inverse moment, $1/{\lambda }_B$, from the expected high-statistics data of the BELLE II experiment.

    hep-phJHEP(2018)·113 citations
11. 11*

    TMD gluon distributions at small x in the CGC theory

    Elena Petreska🇳🇱

    We review recent progress in the description of unpolarized transverse-momentum-dependent (TMD) gluon distributions at small $x$ in the color glass condensate (CGC) effective theory. We discuss the origin of the non-universality of TMD gluon distributions in the TMD factorization framework and in the CGC theory and the equivalence of the two approaches in their overlapping domain of validity. We show some applications of this equivalence, including recent results on the behavior of TMD gluon distributions at small $x$, and on the study of gluon saturation. We discuss recent advances in the unification of the TMD evolution and the non-linear small-$x$ evolution of gluon distributions.

    hep-phnucl-thIJMPE(2018)·47 citations
12. 12*

    Deconfinement Transition Effects on Cosmological Parameters and Primordial Gravitational Wave Spectrum

    P. Castorina🇮🇹 · D. Lanteri🇮🇹 · S. Mancani🇮🇹

    The cosmological evolution can be described in terms of directly measurable cosmological scalar parameters (deceleration $q$, jerk $j$, snap $s$, etc...) constructed out of high order derivatives of the scale factor. Their behavior at the critical temperature of the Quantum Chromodynamics (QCD) phase transition in early universe could be a specific tool to study the transition, analogously to the fluctuations of conserved charges in QCD. We analyze the effect of the crossover transition from quarks and gluons to hadrons in early universe on the cosmological scalars and on the gravitational wave spectrum, by using the recent lattice QCD equation of state and including the electroweak degrees of freedom and different models of dark matter. Near the transition the cosmological parameters follow the behavior of QCD trace anomaly and of the speed of sound of the entire system. The effects of deconfinement turn out to be more relevant for the modification of the primordial spectrum of gravitational waves and our complete analysis, based on lattice QCD simulations and on the hadron resonance gas below the critical temperature, refines previous results.

    hep-phastro-ph.HEnucl-thPRD(2018)·7 citations
13. 13*

    Quark mass dependent collective excitations and quark number susceptibilities within the hard thermal loop approximation

    Najmul Haque🇩🇪

    We calculate all those QCD $N$-point functions which are relevant for a three-loop QCD thermodynamics calculation with finite quark masses within the hard the thermal loop approximation. Using the effective quark propagator, we also calculate second order quark and baryon number susceptibilities within the hard thermal loop approximation and compare the results with available lattice data.

    hep-phPRD(2018)·13 citations
14. 14*

    Gluon poles and photon distribution amplitudes in Drell-Yan-like processes

    I.V. Anikin🇷🇺 · L. Szymanowski🇵🇱

    We calculate the hadron tensor related to the photon-induced Drell-Yan process, with incoming nucleon being transversally polarised. We predict the new single spin asymmetry which probes gluon poles and which is expressed in terms of photon (both chiral-odd and chiral-even) distribution amplitudes and chiral-odd nucleon function stemming from the nucleon transverse polarization.

    hep-phEPJA(2018)·2 citations
15. 15*

    Wilson: a Python package for the running and matching of Wilson coefficients above and below the electroweak scale

    Jason Aebischer🇩🇪 · Jacky Kumar🇮🇳 · David M. Straub🇩🇪

    Wilson is a Python library for matching and running Wilson coefficients of higher-dimensional operators beyond the Standard Model. Provided with the numerical values of the Wilson coefficients at a high new physics scale, it automatically performs the renormalization group evolution within the Standard Model effective field theory (SMEFT), matching onto the weak effective theory (WET) at the electroweak scale, and QCD/QED renormalization group evolution below the electroweak scale down to hadronic scales relevant for low-energy precision tests. The matching and running encompasses the complete set of dimension-six operators in both SMEFT and WET. The program builds on the Wilson coefficient exchange format (WCxf) and can thus be easily combined with a number of existing public codes.

    hep-phEPJC(2018)·257 citations
16. 16*

    Three-Flavoured Non-Resonant Leptogenesis at Intermediate Scales

    K. Moffat🇬🇧 · S. Pascoli🇬🇧 · S.T. Petcov🇮🇹 · H. Schulz🇺🇸 · J. Turner🇺🇸

    Leptogenesis can successfully explain the matter-antimatter asymmetry via out-of-equilibrium decays of heavy Majorana neutrinos in the early Universe. In this article, we focus on non-resonant thermal leptogenesis and the possibility of lowering its scale. In order to do so, we calculate the lepton asymmetry produced from the decays of one and two heavy Majorana neutrinos using three-flavoured density matrix equations in an exhaustive exploration of the model parameter space. We find regions of the parameter space where thermal leptogenesis is viable at intermediate scales, $T\sim 10^6$ GeV. However, the viability of thermal leptogenesis at such scales requires a certain degree of cancellation between the tree and one-loop level contribution to the light neutrino mass matrix and we quantify such fine-tuning.

    hep-phPRD(2018)·86 citations
17. 17*

    Top-philic Vector-Like Portal to Scalar Dark Matter

    Stefano Colucci🇩🇪 · Benjamin Fuks🇫🇷 · Federica Giacchino🇧🇪 · Laura Lopez Honorez🇧🇪 · Michel H.G. Tytgat🇧🇪 · Jérôme Vandecasteele🇧🇪

    We investigate the phenomenology of scalar singlet dark matter candidates that couple dominantly to the Standard Model via a Yukawa interaction with the top quark and a colored vector-like fermion. We estimate the viability of this vector-like portal scenario with respect to the most recent bounds from dark matter direct and indirect detection, as well as to dark matter and vector-like mediator searches at colliders. Moreover, we take QCD radiative corrections into account in all our theoretical calculations. This work complements analyses related both to models featuring a scalar singlet coupled through a vector-like portal to light quarks, and to scenarios in which the dark matter is a Majorana singlet coupled to the Standard Model through scalar colored particles (akin to simplified models inspired by supersymmetry). Our study puts especially forward the complementarity of different search strategies from different contexts, and we show that current experiments allow for testing dark matter masses ranging up to 700 GeV and mediator masses ranging up to 6 TeV.

    hep-phPRD(2018)·58 citations
18. 18*

    Centrality dependence of freeze-out temperature fluctuations in Pb-Pb collisions at the LHC

    Dariusz Prorok🇵🇱

    Many data in the High Energy Physics are, in fact, sample means. It is shown that when this exact meaning of the data is taken into account and the most weakly bound states are removed from the hadron resonance gas, the whole spectra of pions, kaons and protons measured at midrapidity in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV can be fitted simultaneously. The invariant distributions are predicted with the help of the single-freeze-out model in the chemical equilibrium framework. The method is applied to the measurements in centrality bins of Pb-Pb collisions and gives acceptable fits for all but peripheral bins. The comparison with the results obtained in the framework of the original single-freeze-out model is also presented. Some more general, possible implications of this approach are pointed out.

    hep-phhep-exnucl-exnucl-thEPJA(2019)·6 citations
19. 19*

    The Italian contributions to cosmic-ray physics from Bruno Rossi to the G-Stack. A new window into the inexhaustible wealth of nature

    Giulio Peruzzi🇮🇹 · Sofia Talas🇮🇹

    From the late 1920s to the early 1950s, cosmic rays were the main instrument to investigate what we now call "high-energy physics". In approximately 25 years, an intense experimental and theoretical work brought particle physics from its childhood to its maturity. The data collected at that time played a crucial role in order to outline the quantum theories of fundamental interactions - electromagnetic, weak and strong - and they were an excellent training field for many young scientists. The knowledge acquired on cosmic rays constituted the basis of the extraordinary progresses that were to be achieved in fundamental physics with the introduction of particles accelerators. Many papers on this subject have already been published, both by historians and by the scientists who personally worked at that time. However, a complete historical reconstruction of those 25 years of cosmic-ray researches has not been written yet. In particular, an overall description of the researches carried out with the contributions of Italian physicists is still missing. The present paper tries to outline such a description, taking into account the fact that in those very years, for scientific and non scientific reasons, physics researches were getting organised within international collaborations. Without pretending to be exhaustive at all, we would like this paper to be a stimulus for further researches on the subject.

    ↳ physics.hist-phhep-phRiv.Nuovo Cim.(2007)·2 citations
20. 20*

    Nuclear applications of ANL-Osaka amplitudes: pion photo-productions on deuteron

    S.X. Nakamura (Univ. Cruzeiro do Sul)🇧🇷 · H. Kamano (RCNP)🇯🇵 · T.-S. H. Lee (Argonne Nat'l Lab)🇺🇸 · T. Sato (RCNP, J-PARC)🇯🇵

    The Argonne National Laboratory-Osaka University (ANL-Osaka) amplitudes (http://www.phy.anl.gov/theory/research/anl-osaka-pwa/) are applied to study pion photo-production reactions on the deuteron target. Within the multiple scattering formulation, we predict the cross sections of $d(\gamma ,\pi )NN$ in the nucleon resonance region. The calculations include the impulse term and the final-state interaction (FSI) terms due to pion-exchange and nucleon-exchange. We show that the off-shell effects, calculated from the meson-exchange mechanisms, on the propagations of the exchanged nucleon and pion are significant in determining the reaction amplitudes. The FSI effects on the predicted cross sections are found to be important at energies near the $\Delta$(1232) resonance, and are still significant at higher energies. The results are in good agreement with most of the available data of $d(\gamma ,{\pi }^0)np$ and $d(\gamma ,{\pi }^{-})pp$ reactions.

    ↳ nucl-thhep-phnucl-ex15 citations
21. 21*

    Hydrodynamic attractor and the fate of perturbative expansions in Gubser flow

    Gabriel Denicol🇧🇷 · Jorge Noronha🇧🇷

    Perturbative expansions, such as the well-known gradient series and the recently proposed slow-roll expansion, have been recently used to investigate the emergence of hydrodynamic behavior in systems undergoing Bjorken flow. In this paper we determine for the first time the large order behavior of these perturbative expansions in relativistic hydrodynamics in the case of Gubser flow. While both series diverge, the slow-roll series can provide a much better overall description of the system's dynamics than the gradient expansion when both series are truncated at low orders. The truncated slow-roll series can also describe the attractor solution of Gubser flow as long as the system is sufficiently close to equilibrium near the origin (i.e., $\rho =0$) in $d{S}_3\otimes \mathbb{R}$. Differently than the case of Bjorken flow, here we show that the Gubser flow attractor solution is not solely a function of the effective Knudsen number ${\tau }_R\sqrt{{\sigma }_{\mu \nu }{\sigma }^{\mu \nu }}\sim {\tau }_R\tanh \rho$. Our results give further support to the idea that new \emph{resummed} constitutiv relations between dissipative currents and the gradients of conserved quantities can emerge in systems far from equilibrium that are beyond the regime of validity of the usual gradient expansion.

    ↳ nucl-thhep-phhep-thPRD(2019)·75 citations
22. 22*

    Searching for the Dark Force with 21-cm Spectrum in Light of EDGES

    Chunlong Li🇨🇳 · Yi-Fu Cai🇨🇳

    The EDGES Collaboration has recently announced the detection of the 21-cm spectrum with an absorption profile centred at $78$ megahertz, of which the depth is deeper than that expected by the standard cosmological paradigm. To enrich the heating process of baryons due to scattering with dark matter during dark ages, we in this Letter explore the possibility of extra heat transfer between dark sector compositions and their observational signatures on the 21-cm cosmological spectrum. By parameterizing interaction models of the dark Universe, we find that the observational constraint on the parameter space of dark matter can be slightly relaxed but the discrepancy with the commonly predicted parameter space of weakly interacting massive particles remains. Our analyses also reveal that the interaction between dark compositions may leave observational signatures on the 21-cm spectrum during dark ages and thus would become detectable in the forthcoming 21-cm cosmology.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2019)·28 citations
23. 23*

    Cosmology with Type II Supernovae

    Deng Wang🇨🇳

    With the recent progresses on the Type II supernovae, we attempt to investigate whether there does exist new physics beyond the standard cosmological paradigm, i.e., the cosmological constant $\Lambda$ plus cold dark matter ($\Lambda$CDM). Constraining four alternative cosmological models with a data combination of currently available Type II supernovae calibrated by the standard color method, Type Ia supernovae, baryon acoustic oscillations, cosmic microwave background and cosmic chronometers, at the $1\sigma$ confidence level, we find that: (i) a spatially flat universe is supported for the non-flat $\Lambda$CDM model; (ii) the constrained equation of state of dark energy $\omega$ is consistent with the $\Lambda$CDM hypothesis for the $\omega$CDM model where $\omega$ is a free parameter; (iii) for the decaying vacuum model, there is no evidence of interaction between dark matter and dark energy in the dark sector of the universe; (iv) there is also no hint of dynamical dark energy for the dark energy density-parametrization scenario. It is very obvious that a larger Type II supernovae sample is required, if we expect to draw definitive conclusions about the formation and evolution of the universe.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phInt.J.Mod.Phys.D(2019)·1 citation
24. 24*

    Interplay of drag by hot matter and electromagnetic force on the directed flow of heavy quarks

    Sandeep Chatterjee🇵🇱 · Piotr Bozek🇵🇱

    Rapidity-odd directed flow in heavy ion collisions can originate from two very distinct sources in the collision dynamics i. an initial tilt of the fireball in the reaction plane that generates directed flow of the constituents independent of their charges, and ii. the Lorentz force due to the strong primordial electromagnetic field that drives the flow in opposite directions for constituents carrying unlike sign charges. We study the directed flow of open charm mesons $D^0$ and $\overline{D^0}$ in the presence of both these sources of directed flow. The drag from the tilted matter dominates over the Lorentz force resulting in same sign flow for both $D^0$ and $\overline{D^0}$, albeit of different magnitudes. Their average directed flow is about ten times larger than their difference. This charge splitting in the directed flow is a sensitive probe of the electrical conductivity of the produced medium. We further study their beam energy dependence; while the average directed flow shows a decreasing trend, the charge splitting remains flat from $\sqrt{s_{NN}}=60$ GeV to $5$ TeV.

    ↳ nucl-thhep-phnucl-exPLB(2019)·76 citations
25. 25*

    Fluctuations about the Fubini-Lipatov instanton for false vacuum decay in classically scale invariant models

    Bjorn Garbrecht🇩🇪 · Peter Millington🇬🇧

    For a scalar theory whose classical scale invariance is broken by quantum effects, we compute self-consistent bounce solutions and Green's functions. Deriving analytic expressions, we find that the latter are similar to the Green's functions in the archetypal thin-wall model for tunneling between quasi-degenerate vacua. The eigenmodes and eigenspectra are, however, very different. Large infrared effects from the modes of low angular momentum $j=0$ and $j=1$, which include the approximate dilatational modes for $j=0$, are dealt with by a resummation of one-loop effects. For a parametric example, this resummation is carried out numerically.

    ↳ hep-thhep-phPRD(2018)·22 citations
26. 26*

    The importance of observing astrophysical tau neutrinos

    Andrea Palladino🇩🇪 · Carlo Mascaretti🇮🇹 · Francesco Vissani🇮🇹

    The evidence of a new population of diffuse high-energy neutrinos, obtained by IceCube, has opened a new era in the field of neutrino physics. Up to now the events detected are still without any source counterpart. The detected events are compatible with the standard picture of cosmic neutrinos undergoing 3-flavor neutrino oscillations. We analyze the implications of neutrino oscillations for the present and future experiments, focusing particularly on tau neutrinos. In fact tau neutrinos are very important: even if they are not produced in astrophysical sites, they have to exist due to oscillations and their observation should be regarded as a basic proof in support of this scenario. Moreover, IceCube's measurement of the flux of muon neutrinos implies that the flux of tau neutrinos is measured within $20\%$, just assuming standard neutrino oscillations. On this basis, after discussing the experimental signatures of tau neutrinos, we predict the rates for ${\nu }_{\tau }$ detection in the present and future neutrino telescopes. We show that the present IceCube detector is close to observe the first tau neutrinos, with a probability of about 90\%. Moreover the next generation of IceCube can identify about 2 neutrinos per year, reaching an evidence of 5$\sigma$ in about 10 years, despite the present uncertainty on the spectrum and on the production mechanism. The non observation of these neutrino events would have dramatic implications, such as the questioning of cosmic neutrino observations or the violation of neutrino oscillations over cosmological scales.

    ↳ astro-ph.HEhep-phJCAP(2018)·10 citations
27. 27*

    Gauge Assisted Quadratic Gravity: A Framework for UV Complete Quantum Gravity

    John F. Donoghue🇺🇸 · Gabriel Menezes🇺🇸

    We discuss a variation of quadratic gravity in which the gravitational interaction remains weakly coupled at all energies, but is assisted by a Yang-Mills gauge theory which becomes strong at the Planck scale. The Yang-Mills interaction is used to induce the usual Einstein-Hilbert term, which was taken to be small or absent in the original action. We study the spin-two propagator in detail, with a focus on the high mass resonance which is shifted off the real axis by the coupling to real decay channels. We calculate scattering in the $J=2$ partial wave and show explicitly that unitarity is satisfied. The theory will in general have a large cosmological constant and we study possible solutions to this, including a unimodular version of the theory. Overall, the theory satisfies our present tests for being a ultraviolet completion of quantum gravity.

    ↳ hep-thgr-qchep-phPRD(2018)·68 citations
28. 28*

    Charge symmetry violation in the doubly charmed cascade masses

    K. K. Cushman🇦🇺 · A. W. Thomas🇦🇺 · R. D. Young🇦🇺

    We investigate the electromagnetic contribution to the charge symmetry breaking in the ${\Xi }_{cc}$ baryon masses using a subtracted dispersion relation based on the Cottingham formula, following the formalism developed in an analysis of the octet baryon mass differences. In the absence of experimental information on the structure of charmed baryons, we use parameters for the electromagnetic structure of the ${\Xi }_{cc}$ and the difference in its charge states obtained from lattice QCD and estimates of SU(4) symmetry breaking. We report a conservative estimate for the mass splitting of the doubly charmed cascades to be 8 $\pm$ 9 MeV. While a smaller isospin splitting is compatible with this result, surprisingly it does not preclude the large splitting reported by the SELEX Collaboration. We identify those quantities which could be determined from lattice QCD and which would reduce the quoted theoretical uncertainty.

    ↳ nucl-thhep-ph2 citations
29. 29*

    On velocity-dependent dark matter annihilations in dwarf satellites

    Mihael Petac🇮🇹 · Piero Ullio🇮🇹 · Mauro Valli🇮🇹

    Milky Way dwarf spheroidal satellites are a prime target for Dark Matter (DM) indirect searches. There have been recent reassessments of the expected DM gamma-ray signals in case of long-range interactions, commonly known as Sommerfeld enhancement. Since details of the underlying DM phase-space distribution function become critical, there are potentially large uncertainties in the final result. We provide here a first attempt towards a comprehensive investigation of these systematics, addressing the impact on the expected DM flux from Milky Way dwarfs via Bayesian inference on the available stellar kinematic datasets. After reconsidering the study case of ergodic systems, we investigate for the first time scenarios where DM particle orbits may have a radial or tangential bias. We consider both cuspy and cored parametric DM density profiles, together with the case of a non-parametric halo modelling directly connected to line-of-sight observable quantities. The main findings of our work highlight the relevance of the assumed phase-space distribution: Referring to a generalized J-factor, namely the line-of-sight convolution of the spatial part in case of velocity-dependent annihilation rate, an enhancement (suppression) with respect to the limit of isotropic phase-space distributions is obtained for the case of tangentially (radially) biased DM particle orbits. We provide new estimates for J-factors for the eight brightest Milky Way dwarfs also in the limit of velocity-independent DM annihilation, in good agreement with previous results in literature, and derive data-driven lower-bounds based on the non-parametric modelling of the halo density. The outcome of our broad study stands out as a representative of the state-of-the-art in the field, and falls within the interest of current and future experimental collaborations involved in DM indirect detection programs.

    ↳ astro-ph.GAastro-ph.COastro-ph.HEhep-phJCAP(2018)·43 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.