Wed·Sep 6, 2017Wednesday·September 6, 2017

1. 01*

   NNLO QCD corrections to event orientation in e+e- annihilation

   Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Jan Niehues🇨🇭 · Hantian Zhang🇨🇭

   We present a new implementation of the NNLO QCD corrections to three-jet final states and related event-shape observables in electron--positron annihilation. Our implementation is based on the antenna subtraction method, and is performed in the NNLOJET framework. The calculation improves upon earlier results by taking into account the full kinematical information on the initial state momenta, thereby allowing the event orientation to be computed to NNLO accuracy. We find the event-orientation distributions at LEP and SLC to be very robust under higher order QCD corrections.

   hep-phPLB(2017)·28 citations
2. 02*

   Explaining Dark Matter and Neutrino Mass in the light of TYPE-II Seesaw Model

   Anirban Biswas🇮🇳 · Avirup Shaw🇮🇳

   With the motivation of simultaneously explaining dark matter and neutrino masses, mixing angles, we have invoked the Type-II seesaw model extended by an extra $SU(2)$ doublet $\Phi$. Moreover, we have imposed a ${\mathbb{Z}}_2$ parity on $\Phi$ which remains unbroken as the vacuum expectation value of $\Phi$ is zero. Consequently, the lightest neutral component of $\Phi$ becomes naturally stable and can be a viable dark matter candidate. On the other hand, light Majorana masses for neutrinos have been generated following usual Type-II seesaw mechanism. Further in this framework, for the first time, we have derived the full set of vacuum stability and unitarity conditions, which must be satisfied to obtain a stable vacuum as well as to preserve the unitarity of the model respectively. Thereafter, we have performed extensive phenomenological studies of both dark matter and neutrino sectors considering all possible theoretical and current experimental constraints. Finally, we have also discussed a qualitative collider signatures of dark matter and associated odd particles at the 13 TeV Large Hadron Collider.

   hep-phJCAP(2018)·7 citations
3. 03*

   The pion in holographic light-front QCD

   M. Ahmady🇨🇦 · F. Chishtie🇨🇦 · R. Sandapen🇨🇦

   We report that the pion radius, decay constant, EM and transition form factors can simultaneously and accurately be predicted in light-front holographic QCD with a universal AdS/QCD mass scale, provided dynamical spin effects are taken into account.

   hep-phNucl.Part.Phys.Proc.(2018)·1 citation
4. 04*

   Inclusive charged light di-hadron production at 7 and 13 TeV LHC in the full NLA BFKL approach

   Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Beatrice Murdaca🇮🇹 · Alessandro Papa🇮🇹

   We give the first phenomenological predictions of cross sections and azimuthal correlations for the inclusive di-hadron production in the full NLA BFKL approach. This process shares the same theoretical framework with the well konwn Mueller-Navelet jet production and can be considered a novel and complementary channel to access the BFKL dynamics at proton colliders.

   hep-ph18 citations
5. 05*

   xFitter 2.0.0: An Open Source QCD Fit Framework

   V. Bertone🇳🇱 · M. Botje🇳🇱 · D. Britzger🇩🇪 · S. Camarda🇨🇭 · A. Cooper-Sarkar🇬🇧 · F. Giuli🇬🇧 · A. Glazov🇩🇪 · A. Luszczak🇵🇱 · F. Olness🇺🇸 · R. Placakyte🇩🇪 · V. Radescu🇨🇭 · W. Słomiński · O. Zenaiev (xFitter Developers' Team)🇩🇪

   xFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton for many different kinds of analyses in Quantum Chromodynamics (QCD). xFitter version 2.0.0 has recently been released, and offers an expanded set of tools and options. It incorporates experimental data from a wide range of experiments including fixed-target, Tevatron, HERA, and LHC. xFitter can analyze this data up to next-to-next-to-leading-order (NNLO) in perturbation theory with a variety of theoretical calculations including numerous methodological options for carrying out PDF fits and plotting tools which help visualize the results. While primarily based on the collinear factorization foundation, xFitter also provides facilities for fits of dipole models and transverse-momentum dependent (TMD) PDFs. The package can be used to study the impact of new precise measurements from hadron colliders, and also assess the impact of future colliders. This paper provides a brief overview of xFitter with emphasis of the new version 2.0.0 features.

   hep-phPoS(2018)·58 citations
6. 06*

   Color Confinement, Hadron Dynamics, and Hadron Spectroscopy from Light-Front Holography and Superconformal Algebra

   Stanley J. Brodsky🇺🇸

   The QCD light-front Hamitonian equation derived from quantization at fixed LF time provides a causal, frame-independent, method for computing hadron spectroscopy and dynamical observables. de Alfaro, Fubini, and Furlan (dAFF) have made an important observation that a mass scale can appear in the equations of motion without affecting the conformal invariance of the action if one adds a term to the Hamiltonian proportional to the dilatation operator or the special conformal operator. If one applies the dAFF procedure to the QCD light-front Hamiltonian, it leads to a color confining potential ${\kappa }^4{\zeta }^2$ for mesons, where ${\zeta }^2$ is the LF radial variable conjugate to the $q\bar{q}$ invariant mass squared. The same result, including spin terms, is obtained using light-front holography if one modifies the AdS${}_5$ action by the dilaton $e^{{\kappa }^2{z}^2}$ in the fifth dimension $z$. When one generalizes this procedure using superconformal algebra, the resulting light-front eigensolutions provide a unified Regge spectroscopy of meson, baryon, and tetraquarks, including remarkable supersymmetric relations between the masses of mesons and baryons and a universal Regge slope. The pion $q\bar{q}$ eigenstate has zero mass at $m_q=0.$ The superconformal relations also can be extended to heavy-light quark mesons and baryons. AdS/QCD also predicts the analytic form of the nonperturbative running coupling in agreement with the effective charge measured from measurements of the Bjorken sum rule. The mass scale underlying hadron masses can be connected to the mass parameter in the QCD running coupling. The result is an effective coupling ${\alpha }_s(Q^2)$ defined at all momenta. One also obtains empirically viable predictions for spacelike and timelike hadronic form factors, structure functions, distribution amplitudes, and transverse momentum distributions.

   hep-phhep-thAdv.High Energy Phys.(2018)·7 citations
7. 07*

   Phenomenological Analysis of an ${\mathrm{E}}_6$-inspired Seesaw Model

   Joshua P. Ellis🇦🇺 · Raymond R. Volkas🇦🇺

   We analyse the phenomenology of a model of neutrino masses inspired by ${\mathrm{E}}_6$ GUT unification in which the exotic neutrinos can be present at low scales. The model introduces vector-like isosinglet down-type quarks, vector-like isodoublet leptons, neutrino singlets and two $Z^{\prime }$ bosons. The seesaw mechanism can be achieved with exotic neutrino masses as low as 100 GeV and Yukawa couplings of order $10^{-3}$. We find that the lightest $Z^{\prime }$ boson mass is required to be above 2.8 TeV, the exotic quark masses are required to be above 1.3 TeV (810 GeV) if they are collider stable (promptly decaying), and the exotic lepton mass bounds remain at the LEP value of 102 GeV. The model also presents a type-II two-Higgs-doublet model (2HDM) along with two heavy singlet scalars. The 2HDM naturally has the alignment limit enforced thanks to the large VEVs of the exotic scalars, thereby avoiding most constraints.

   hep-phPRD(2017)·1 citation
8. 08*

   Revisiting Big-Bang Nucleosynthesis Constraints on Long-Lived Decaying Particles

   Masahiro Kawasaki🇯🇵 · Kazunori Kohri🇯🇵 · Takeo Moroi🇯🇵 · Yoshitaro Takaesu🇯🇵

   We study effects of long-lived massive particles, which decay during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundances of light elements. Compared to the previous studies, (i) the reaction rates of the standard BBN reactions are updated, (ii) the most recent observational data of light element abundances and cosmological parameters are used, (iii) the effects of the interconversion of energetic nucleons at the time of inelastic scatterings with background nuclei are considered, and (iv) the effects of the hadronic shower induced by energetic high energy anti-nucleons are included. We compare the theoretical predictions on the primordial abundances of light elements with latest observational constraints, and derive upper bounds on relic abundance of the decaying particle as a function of its lifetime. We also apply our analysis to unstable gravitino, the superpartner of the graviton in supersymmetric theories, and obtain constraints on the reheating temperature after inflation.

   hep-phastro-ph.COPRD(2018)·309 citations
9. 09*

   Gravitino Problem in Inflation Driven by Inflaton-Polonyi Kähler Coupling

   Fuminori Hasegawa🇯🇵 · Kazunori Nakayama🇯🇵 · Takahiro Terada🇯🇵 · Yusuke Yamada🇺🇸

   We discuss the cosmological gravitino problem in inflation models in which the inflaton potential is constructed from Kähler potential rather than superpotential: a representative model is $\overline{\text{D}3}$-induced geometric inflation. A critical ingredient in this type of models is the coupling of the inflaton and Polonyi (supersymmetry-breaking) field in the Kähler potential, which is needed to build the inflaton potential. We point out the same coupling let the inflaton dominantly decay into a pair of inflatino and gravitino causing the gravitino problem. We propose some possible solutions to this problem.

   hep-phastro-ph.COhep-thPLB(2018)·10 citations
10. 10*

    ElectroWeak BaryoGenesis via Top Transport

    George W.-S. Hou🇹🇼

    We study electroweak baryogenesis driven by the top quark in two Higgs doublet model that allows flavor-changing neutral Higgs couplings. Taking Higgs sector couplings and the additional top Yukawa coupling ${\rho }_{tt}$ to be $\mathcal{O}$(1), one naturally has first order electroweak phase transition and sufficient $CP$ violation to fuel the cosmic baryon asymmetry. Even if ${\rho }_{tt}$ vanishes, the favor-changing coupling ${\rho }_{tc}$ can still achieve baryogenesis. Phenomenological consequences such as $t\to ch$, $\tau \to \mu \gamma$, electron electric dipole moment, $h\to \gamma \gamma$, and $hhh$ coupling are discussed. The extra scalars $H^0$, $A^0$ and $H^{\pm }$ are sub-TeV in mass, and can be searched for at the LHC.

    hep-phPoS(2017)·1 citation
11. 11*

    Loopedia, a Database for Loop Integrals

    C. Bogner🇩🇪 · S. Borowka🇨🇭 · T. Hahn🇩🇪 · G. Heinrich🇩🇪 · S.P. Jones🇩🇪 · M. Kerner🇩🇪 · A. von Manteuffel🇺🇸 · M. Michel🇧🇪 · E. Panzer🇬🇧 · V. Papara🇩🇪

    Loopedia is a new database at loopedia.org for information on Feynman integrals, intended to provide both bibliographic information as well as results made available by the community. Its bibliometry is complementary to that of SPIRES or arXiv in the sense that it admits searching for integrals by graph-theoretical objects, e.g. its topology.

    hep-phComput.Phys.Commun.(2018)·38 citations
12. 12*

    S- and D-wave vector charmonia

    A. Krassnigg🇦🇹 · T. Hilger🇦🇹

    We revisit earlier calculations of leptonic decay constants of vector charmonia and present and illustrate our decomposition of the corresponding covariant Bethe-Salpeter amplitudes in terms of orbital angular momentum as interpreted in the meson's rest frame. Our results confirm our previous conclusions drawn from the magnitudes of vector-meson leptonic decay constants, identifying the Psi(3770) and Psi(4160) as D-wave states in our setup.

    hep-phhep-exJ.Phys.Conf.Ser.(2018)·3 citations
13. 13*

    On the binding of the $BD\bar{D}$ and $BDD$ systems

    J. M. Dias🇪🇸 · V. R. Debastiani🇪🇸 · L. Roca🇪🇸 · S. Sakai🇪🇸 · E. Oset🇪🇸

    We study theoretically the $BD\bar{D}$ and $BDD$ systems to see if they allow for possible bound or resonant states. The three-body interaction is evaluated implementing the Fixed Center Approximation to the Faddeev equations which considers the interaction of a $D$ or $\bar{D}$ particle with the components of a $BD$ cluster, previously proved to form a bound state. We find an $I(J^P)=1/2(0^{-})$ bound state for the $BD\bar{D}$ system at an energy around $8925-8985$ MeV within uncertainties, which would correspond to a bottom--hidden-charm meson. In contrast, the $BDD$ system, which would be bottom--double-charm and hence manifestly exotic, we have found hints of a bound state in the energy region $8935-8985$ MeV, but the results are not stable under the uncertainties of the model, and we cannot assure, neither rule out, the possibility of a $BDD$ three-body state.

    hep-phPRD(2017)·25 citations
14. 14*

    Forward $J/\psi$ and very backward jet inclusive production at the LHC

    R. Boussarie🇵🇱 · B. Ducloué🇫🇮 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷

    In the spirit of Mueller-Navelet dijet production, we propose and study the inclusive production of a forward $J/\psi$ and a very backward jet at the LHC as an observable to reveal high-energy resummation effects à la BFKL. We obtain several predictions, which are based on the various mechanisms discussed in the literature to describe the production of the $J/\psi$, namely, NRQCD singlet and octet contributions, and the color evaporation model.

    hep-phhep-exPRD(2018)·79 citations
15. 15*

    Triangular singularity and a possible $\varphi p$ resonance in the ${\Lambda }_c^{+}\to {\pi }^0\varphi p$ decay

    Ju-Jun Xie🇨🇳 · Feng-Kun Guo🇨🇳

    We study the ${\Lambda }_c^{+}\to {\pi }^0\varphi p$ decay by considering a triangle singularity mechanism. In this mechanism, the ${\Lambda }_c^{+}$ decays into the $K^{\ast }{\Sigma }^{\ast }(1385)$, the ${\Sigma }^{\ast }(1385)$ decays into the ${\pi }^0\Sigma$ (or $\Lambda$), and then the $K^{\ast }\Sigma$ (or $\Lambda$) interact to produce the $\varphi p$ in the final state. This mechanism produces a peak structure around $2020$ MeV. In addition, the possibility that there is a hidden-strange pentaquark-like state is also considered by taking into account the final state interactions of $K^{\ast }\Lambda$, $K^{\ast }\Sigma$, and $\varphi p$. We conclude that it is difficult to search for the hidden-strange analogue of the $P_c$ states in this decay. However, we do expect nontrivial behavior in the $\varphi p$ invariant mass distribution. The predictions can be tested by experiments such as BESIII, LHCb and Belle-II.

    hep-phhep-exnucl-thPLB(2017)·42 citations
16. 16*

    The continuum threshold and the Polyakov loop: A comparison between two deconfinement order parameters

    J. P. Carlomagno🇦🇷 · M. Loewe🇿🇦

    We compare two order parameters for the deconfinement transition, induced by thermal and density effects, commonly used in the literature, namely the thermal and density evolution of the continuum threshold $s_0$, within the frame of the QCD sum rules, and the trace of the Polyakov loop $\Phi$ in the framework of a nonlocal $SU(2)$ chiral quark model. We include in our discussion the evolution of the chiral quark condensate, the parameter that characterizes the chiral symmetry restoration. We found that essentially both order parameters, $s_0$ and $\Phi$, provide the same information for the deconfinement transition, both for the zero and finite chemical potential cases. At zero density, the critical temperatures in both cases coincide exactly and, in the case of finite baryonic chemical potential $\mu$, we find evidence for the appearance of a quarkyonic phase.

    hep-phNucl.Part.Phys.Proc.(2018)·0 citations
17. 17*

    The PDFLattice2017 workshop: a summary report

    Emanuele R. Nocera🇬🇧 · Huey-Wen Lin🇺🇸 · Fred Olness🇺🇸 · Kostas Orginos🇺🇸 · Juan Rojo🇳🇱

    The workshop on Parton Distributions and Lattice Calculations in the LHC era (PDFLattice2017) was hosted at Balliol College, Oxford (UK), from 22${}^{\mathrm{nd}}$ to 24${}^{\mathrm{th}}$ March 2017. The workshop brought together the lattice-QCD and the global-fit physicists who devote their efforts to determine the parton distribution functions (PDFs) of the proton. The goals were to make the two communities more familiar between each other, review developments from both sides, and set precision targets for lattice calculations so that they can contribute, together with the forthcoming experimental input, to the next generation of PDF determinations. This contribution summarises the relevant outcome of the workshop, in anticipation of a thorough white paper.

    hep-phhep-latPoS(2018)·7 citations
18. 18*

    Electromagnetic trace anomaly in a generalized linear sigma model

    Amir H. Fariborz🇺🇸 · Renata Jora🇷🇴

    We build the electromagnetic trace anomaly effective term for a generalized linear sigma model with two chiral nonets, one with a quark-antiquark structure, the other one with a four quark content. In the leading order of this framework, we study the decays into two photons of the lowest isosinglet scalar mesons. We find that the direct inclusion of underlying mixing among two- and four-quark components in the trace anomaly term is essential in order for the model prediction to agree with the available experimental data on decay width of $f_0(980)$ to two photons. Consequently, this sets a lower bound of 0.5 KeV on the decay with of $f_0(500)$ to two photons.

    hep-phPRD(2017)·7 citations
19. 19*

    Expectations for Inflationary Observables: Simple or Natural?

    Nathan Musoke🇳🇿 · Richard Easther🇳🇿

    We describe the general inflationary dynamics that can arise with a single, canonically coupled field where the inflaton potential is a 4-th order polynomial. This scenario yields a wide range of combinations of the empirical spectral observables, $n_s$, $r$ and ${\alpha }_s$. However, not all combinations are possible and next-generation cosmological experiments have the ability to rule out all inflationary scenarios based on this potential. Further, we construct inflationary priors for this potential based on physically motivated choices for its free parameters. These can be used to determine the degree of tuning associated with different combinations of $n_s$, $r$ and ${\alpha }_s$ and will facilitate treatments of the inflationary model selection problem. Finally, we comment on the implications of these results for the naturalness of the overall inflationary paradigm. We argue that ruling out all simple potentials would not necessarily imply that the inflationary paradigm itself was unnatural, but that this eventuality would increase the importance of building inflationary scenarios in the context of broader paradigms of ultra-high energy physics.

    ↳ astro-ph.COhep-phhep-thJCAP(2017)·13 citations
20. 20*

    Scattering amplitudes of massive Nambu-Goldstone bosons

    Tomas Brauner🇳🇴 · Martin F. Jakobsen🇳🇴

    Massive Nambu-Goldstone (mNG) bosons are quasiparticles whose gap is determined exactly by symmetry. They appear whenever a symmetry is broken spontaneously in the ground state of a quantum many-body system, and at the same time explicitly by the system's chemical potential. In this paper, we revisit mNG bosons and show that apart from their gap, symmetry also protects their scattering amplitudes. Just like for ordinary gapless NG bosons, the scattering amplitudes of mNG bosons vanish in the long-wavelength limit. Unlike for gapless NG bosons, this statement holds for any scattering process involving one or more external mNG states; there are no kinematic singularities associated with the radiation of a soft mNG boson from an on-shell initial or final state.

    ↳ hep-thcond-mat.quant-gascond-mat.stat-mechhep-phPRD(2018)·9 citations
21. 21*

    Untwisting twisted NJL${}_2$-kinks by a bare fermion mass

    Michael Thies🇩🇪

    Twisted kinks in the massless NJL${}_2$ model interpolate between two distinct vacua on the chiral circle. If one approaches the chiral limit from finite bare fermion masses $m_0$, the vacuum is unique and twist cannot exist. This issue is studied analytically in the non-relativistic limit, using a no-sea effective theory. We conclude that even in the massless limit, the interpretation of the twisted kink has to be revised. One has to attribute the fermion number of the valence state to the twisted kink. Fermion density is spread out over the whole space due to the massless pion field. The result can be pictured as a composite of a twisted kink (carrying energy, but no fermion number) and a partial winding of the chiral spiral (carrying fermion number, but no energy). This solves at the same time the puzzle of missing baryons with fermion number $N_f<N$ in the massless NJL${}_2$ model.

    ↳ hep-thcond-mat.str-elhep-phPRD(2017)·4 citations
22. 22*

    CMB anisotropies from patchy reionisation and diffuse Sunyaev-Zel'dovich effects

    Christian Fidler🇧🇪 · Christophe Ringeval🇧🇪

    Anisotropies in the Cosmic Microwave Background (CMB) can be induced during the later stages of cosmic evolution, and in particular during and after the Epoch of Reionisation. Inhomogeneities in the ionised fraction, but also in the baryon density, in the velocity fields and in the gravitational potentials are expected to generate correlated CMB perturbations. We present a complete relativistic treatment of all these effects, up to second order in perturbation theory, that we solve using the numerical Boltzmann code SONG. The physical origin and relevance of all second order terms are carefully discussed. In addition to collisional and gravitational contributions, we identify the diffuse analogue of the blurring and kinetic Sunyaev-Zel'dovich (SZ) effects. Our approach naturally includes the correlations between the imprint from patchy reionisation and the diffuse SZ effects thereby allowing us to derive reliable estimates of the induced temperature and polarisation CMB angular power spectra. In particular, we show that the B-modes generated at intermediate length-scales (l~100) have the same amplitude as the B-modes coming from primordial gravitational waves with a tensor-to-scalar ratio r=10^{-4}.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2017)·4 citations
23. 23*

    Tetraquark operators in lattice QCD and exotic flavour states in the charm sector

    Gavin K. C. Cheung🇬🇧 · Christopher E. Thomas🇬🇧 · Jozef J. Dudek🇺🇸 · Robert G. Edwards🇺🇸

    We present a general class of operators resembling compact tetraquarks which have a range of colour-flavour-spin structures, transform irreducibly under the symmetries of the lattice and respect other relevant symmetries. These constructions are demonstrated in lattice QCD calculations with light quarks corresponding to $m_{\pi }=$ 391 MeV. Using the distillation framework, correlation functions involving large bases of meson-meson and tetraquark operators are computed in the isospin-1 hidden-charm and doubly-charmed sectors, and finite-volume spectra are extracted with the variational method. We find the spectra are insensitive to the addition of tetraquark operators to the bases of meson-meson operators. For the first time, through using diverse bases of meson-meson operators, the multiple energy levels associated with meson-meson levels which would be degenerate in the non-interacting limit are extracted reliably. The number of energy levels in each spectrum is found to be equal to the number of expected non-interacting meson-meson levels in the energy region considered and the majority of energies lie close to the non-interacting levels. Therefore, there is no strong indication for any bound state or narrow resonance in the channels we study.

    ↳ hep-lathep-phJHEP(2017)·118 citations
24. 24*

    The Dark Matter Programme of the Cherenkov Telescope Array

    A.Morselli (for the CTA Consortium)🇮🇹

    In the last decades a vaste amount of evidence for the existence of dark matter has been accumulated. At the same time, many efforts have been undertaken to try to identify what dark matter is. Indirect searches look at places in the Universe where dark matter is believed to be abundant and seek for possible annihilation or decay signatures. The Cherenkov Telescope Array (CTA) represents the next generation of imaging Cherenkov telescopes and, with one site in the Southern hemisphere and one in the Northern hemisphere, will be able to observe all the sky with unprecedented sensitivity and angular resolution above a few tens of GeV. The CTA Consortium will undertake an ambitious program of indirect dark matter searches for which we report here the brightest prospects.

    ↳ astro-ph.IMastro-ph.HEhep-exhep-phPoS(2018)·24 citations
25. 25*

    What can be learned from a future supernova neutrino detection?

    Shunsaku Horiuchi🇺🇸 · James P Kneller🇺🇸

    This year marks the thirtieth anniversary of the only supernova from which we have detected neutrinos - SN 1987A. The twenty or so neutrinos that were detected were mined to great depth in order to determine the events that occurred in the explosion and to place limits upon all manner of neutrino properties. Since 1987 the scale and sensitivity of the detectors capable of identifying neutrinos from a Galactic supernova have grown considerably so that current generation detectors are capable of detecting of order ten thousand neutrinos for a supernova at the Galactic Center. Next generation detectors will increase that yield by another order of magnitude. Simultaneous with the growth of neutrino detection capability, our understanding of how massive stars explode and how the neutrino interacts with hot and dense matter has also increased by a tremendous degree. The neutrino signal will contain much information on all manner of physics of interest to a wide community. In this review we describe the expected features of the neutrino signal, the detectors which will detect it, and the signatures one might try to look for in order to get at these physics.

    ↳ astro-ph.HEhep-exhep-phJ.Phys.G(2018)·172 citations
26. 26*

    Chiral Global Embedding of Fibre Inflation Models

    Michele Cicoli🇮🇹 · David Ciupke🇮🇹 · Victor A. Diaz🇮🇹 · Veronica Guidetti🇮🇹 · Francesco Muia🇬🇧 · Pramod Shukla🇮🇹

    We construct explicit examples of fibre inflation models which are globally embedded in type IIB orientifolds with chiral matter on D7-branes and full closed string moduli stabilisation. The minimal setup involves a Calabi-Yau threefold with h^{1,1}=4 Kaehler moduli which features multiple K3 fibrations and a del Pezzo divisor supporting non-perturbative effects. We perform a consistent choice of orientifold involution, brane setup and gauge fluxes which leads to chiral matter and a moduli-dependent Fayet-Iliopoulos term. After D-term stabilisation, the number of Kaehler moduli is effectively reduced to 3 and the internal volume reduces to the one of fibre inflation models. The inflationary potential is generated by suitable string loop corrections in combination with higher derivative effects. We analyse the inflationary dynamics both in the single-field approximation and by numerically deriving the full multi-field evolution in detail. Interestingly, we find that the Kaehler cone conditions set strong constraints on the allowed inflaton field range.

    ↳ hep-thastro-ph.COhep-phJHEP(2017)·69 citations
27. 27*

    Tests for the existence of horizons through gravitational wave echoes

    Vitor Cardoso🇵🇹 · Paolo Pani🇮🇹

    The existence of black holes and of spacetime singularities is a fundamental issue in science. Despite this, observations supporting their existence are scarce, and their interpretation unclear. We overview how strong a case for black holes has been made in the last few decades, and how well observations adjust to this paradigm. Unsurprisingly, we conclude that observational proof for black holes is impossible to come by. However, just like Popper's black swan, alternatives can be ruled out or confirmed to exist with a single observation. These observations are within reach. In the next few years and decades, we will enter the era of precision gravitational-wave physics with more sensitive detectors. Just as accelerators require larger and larger energies to probe smaller and smaller scales, more sensitive gravitational-wave detectors will be probing regions closer and closer to the horizon, potentially reaching Planck scales and beyond. What may be there, lurking?

    ↳ gr-qcastro-ph.HEhep-phhep-thNature Astron.(2017)·478 citations
28. 28*

    Semianalytic calculation of cosmic microwave background anisotropies from wiggly and superconducting cosmic strings

    I. Yu. Rybak🇵🇹 · A. Avgoustidis🇬🇧 · C. J. A. P. Martins🇵🇹

    We study how the presence of world-sheet currents affects the evolution of cosmic string networks, and their impact on predictions for the cosmic microwave background (CMB) anisotropies generated by these networks. We provide a general description of string networks with currents and explicitly investigate in detail two physically motivated examples: wiggly and superconducting cosmic string networks. By using a modified version of the CMBact code, we show quantitatively how the relevant network parameters in both of these cases influence the predicted CMB signal. Our analysis suggests that previous studies have overestimated the amplitude of the anisotropies for wiggly strings. For superconducting strings the amplitude of the anisotropies depends on parameters which presently are not well known - but which can be measured in future high-resolution numerical simulations.

    ↳ astro-ph.COhep-phPRD(2017)·19 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.