Thu·Jun 22, 2017Thursday·June 22, 2017

1. 01*

   Impact of additional bosons on the exploration of the Higgs boson at the LHC

   Yaquan Fang🇨🇳 · Mukesh Kumar🇿🇦 · Bruce Mellado🇿🇦 · Yu Zhang🇨🇳 · Maosen Zhu🇨🇳

   The LHC is making strides in the exploration of the properties of the newly discoverd Higgs boson, $h$. In Refs.~\cite{vonBuddenbrock:2015ema,Kumar:2016vut,vonBuddenbrock:2016rmr} the compatibility of the proton-proton data reported in the Run I period with the presence of a heavy scalar, $H$, with a mass around 270\,GeV and its implications were explored. This boson would decay predominantly to $H\to Sh$, where $S$, is a lighter scalar boson. The production cross-section of $pp\to H(\to Sh)+X$ is considerable and it would significantly affect the inclusive rate of $h$. The contamination from this new production mechanism would depend strongly on the final state used to measure the rate of $h$. The contamination in the rate measurement of $Vh(\to b\overline{b}),V=Z,W$ is estimated to be small. This statement does not depend strongly on assumptions made on the decay of $S$.

   hep-phhep-exInt.J.Mod.Phys.A(2017)·11 citations
2. 02*

   Nuclear modification of forward $D$ production in pPb collisions at the LHC

   Hirotsugu Fujii🇯🇵 · Kazuhiro Watanabe🇺🇸

   We study nuclear modification factors for single $D$ meson and semileptonic decay lepton $l$ ($=e,\mu$) production in minimum bias proton-nucleus (p$A$) collisions at the LHC in the color-glass-condensate (CGC) framework at leading order in strong coupling. In our numerical computations, transverse momentum ($k_{\perp }$) dependent multi-point Wilson line correlators are employed for describing target nucleus for p$A$ and proton for pp. The projectile proton is treated with unintegrated gluon distribution function, which is also $k_{\perp }$-dependent. The rapidity evolutions of these functions in the small Bjorken $x$ region are taken into account by solving running coupling Balitsky-Kovchegov (BK) equation at leading logarithmic accuracy. For simplicity, we employ Kartvelishvili's type fragmentation function and a simple model for lepton energy distribution from seileptonic decay, respectively, to compute differential cross sections for $D$ and $l$ production. The gluon saturation scale inside the heavy nucleus is enhanced and dependent on $x$, which we take into account by replacing the initial saturation scale in the BK equation with a larger value for the heavy nucleus. We show that the saturation effect leads to perceptible nuclear suppression of $D$ production at forward rapidity. Our numerical results predict similar nuclear suppressions in p$A$ collisions for forward $l$ production at lower transverse momentum $p_{\perp }<2\mathrm{GeV}$. Numerical tables on the nuclear modifications of $D$ and $l$ are listed in this note.

   hep-phhep-exnucl-exnucl-th21 citations
3. 03*

   Quadratic Contributions of Softly Broken Supersymmetry in the Light of Loop Regularization

   Dong Bai🇨🇳 · Yue-Liang Wu🇨🇳

   Loop regularization (LORE) is a novel regularization scheme in modern quantum field theories. It makes no change to the spacetime structure and respects both gauge symmetries and supersymmetry. As a result, LORE should be useful in calculating loop corrections in supersymmetry phenomenology. To demonstrate further its power, in this article we revisit in the light of LORE the old issue of the absence of quadratic contributions (quadratic divergences) in softly broken supersymmetric field theories. It is shown explicitly by Feynman diagrammatic calculations that up to two loops the Wess-Zumino model with soft supersymmetry breaking terms (WZ' model), one of the simplest models with the explicit supersymmetry breaking, is free of quadratic contributions. All the quadratic contributions cancel with each other perfectly, which is consistent with results dictated by the supergraph techniques.

   hep-phhep-thEPJC(2017)·5 citations
4. 04*

   AdS gravity and glueball spectrum

   Vicente Vento🇪🇸

   The glueball spectrum has attracted much attention since the formulation of Quantum Chromodynamics. Different approaches give very different results for their masses. We revisit the problem from the perspective of the AdS/CFT correspondence.

   hep-phEPJA(2017)·9 citations
5. 05*

   Heavy stable charged tracks as signatures of non-thermal dark matter at the LHC : a study in some non-supersymmetric scenarios

   Avirup Ghosh🇮🇳 · Tanmoy Mondal🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   We consider two theoretical scenarios, each including a ${\mathbb{Z}}_2$-odd sector and leading to an elementary dark matter candidate. The first one is a variant of the Type-III seesaw model where one lepton triplet is ${\mathbb{Z}}_2$-odd, together with a heavy sterile neutrino. It leads to a fermionic dark matter, together with the charged component of the triplet being a quasi-stable particle which decays only via a higher-dimensional operator suppressed by a high scale. The second model consists of an inert scalar doublet together with a ${\mathbb{Z}}_2$-odd right-handed Majorana neutrino dark matter. A tiny Yukawa coupling delays the decay of the charged component of the inert doublet into the dark matter candidate, making the former long-lived on the scale of collider detectors. The parameter space of each model has been constrained by big-bang nucleosynthesis constraints, and also by estimating the contribution to the relic density through freeze-out of the long-lived charged particle as well the freeze-in production of the dark matter candidate. We consider two kinds of signals at the Large Hadron Collider for the first kind of models, namely two charged tracks and single track + MET. For the second kind, the characteristic signals are opposite as well as same-sign charged track pairs. We perform a detailed analysis using event selection criteria consistent with the current experimental programmes. It is found that the scenario with a lepton triplet can be probed upto 960(1190) GeV with an integrated luminosity of 300(3000) $f{b}^{-1}$, while the corresponding numbers for the inert doublet scenario are 630(800) GeV. Furthermore, the second kind of signal mentioned in each case allows us to differentiate different dark matter scenarios from each other.

   hep-phJHEP(2017)·27 citations
6. 06*

   Isospin splittings in baryons with two heavy quarks

   Marek Karliner🇮🇱 · Jonathan L. Rosner🇺🇸

   Isospin splittings in baryons with two heavy quarks and a $u$ or $d$ quark are calculated using simple methods proposed previously by the authors. The results are $M({\Xi }_{cc}^{++})-M({\Xi }_{cc}^{+})=1.41\pm 0.12^{+0.76}$ MeV, $M({\Xi }_{bb}^0)-M({\Xi }_{bb}^{-})=-4.78\pm 0.06^{+0.03}$ MeV, and $M({\Xi }_{bc}^{+})-M({\Xi }_{bc}^0)=-1.69\pm 0.07^{+0.39}$ MeV, where the statistical errors reflect uncertainties in input mass splittings, and the systematic errors are associated with the choice of constituent-quark masses.

   hep-phhep-exPRD(2017)·36 citations
7. 07*

   Chiral symmetry restoration at finite temperature within the Hamiltonian approach to QCD in Coulomb gauge

   Ehsan Ebadati🇩🇪 · Hugo Reinhardt🇩🇪 · Peter Vastag🇩🇪

   The chiral phase transition of the quark sector of QCD is investigated within the Hamiltonian approach in Coulomb gauge. Finite temperatures $T$ are introduced by compactifying one spatial dimension, which makes all thermodynamical quantities accessible from the ground state on the spatial manifold ${\mathbb{R}}^2\times S^1(1/T)$. In the limit of a vanishing quark-gluon coupling, the equations of motion of the quark sector are solved numerically and the chiral quark condensate is evaluated and compared to the results of the usual canonical approach to finite-temperature Hamiltonian QCD based on the density operator of the grand canonical ensemble. For zero bare quark masses, we find a second-order chiral phase transition with a critical temperature of about $107\mathrm{MeV}$.

   hep-phhep-thPhys. Rev. D 98, 034012 (2018)·1 citation
8. 08*

   Frame Covariant Nonminimal Multifield Inflation

   Sotirios Karamitsos🇬🇧 · Apostolos Pilaftsis🇬🇧

   We introduce a frame-covariant formalism for inflation of scalar-curvature theories by adopting a differential geometric approach which treats the scalar fields as coordinates living on a field-space manifold. This ensures that our description of inflation is both conformally and reparameterization covariant. Our formulation gives rise to extensions of the usual Hubble and potential slow-roll parameters to generalized fully frame-covariant forms, which allow us to provide manifestly frame-invariant predictions for cosmological observables, such as the tensor-to-scalar ratio $r$, the spectral indices $n_{\mathcal{R}}$ and $n_T$, their runnings ${\alpha }_{\mathcal{R}}$ and ${\alpha }_T$, the non-Gaussianity parameter $f_{NL}$, and the isocurvature fraction ${\beta }_{\mathrm{iso}}$. We examine the role of the field space curvature in the generation and transfer of isocurvature modes, and we investigate the effect of boundary conditions for the scalar fields at the end of inflation on the observable inflationary quantities. We explore the stability of the trajectories with respect to the boundary conditions by using a suitable sensitivity parameter. To illustrate our approach, we first analyze a simple minimal two-field scenario before studying a more realistic nonminimal model inspired by Higgs inflation. We find that isocurvature effects are greatly enhanced in the latter scenario and must be taken into account for certain values in the parameter space such that the model is properly normalized to the observed scalar power spectrum $P_{\mathcal{R}}$. Finally, we outline how our frame-covariant approach may be extended beyond the tree-level approximation through the Vilkovisky-De Witt formalism, which we generalize to take into account conformal transformations, thereby leading to a fully frame-invariant effective action at the one-loop level.

   hep-phgr-qchep-thNPB(2018)·72 citations
9. 09*

   Dark Matter, Neutrino mass, Cutoff for Cosmic-Ray Neutrino, and Higgs Boson Invisible Decay from a Neutrino Portal Interaction

   Wen Yin🇨🇳

   We study an effective theory beyond the standard model (SM) where either of two additional gauge singlets, a Majorana fermion and a real scalar, constitutes all or some fraction of dark matter. In particular, we focus on the masses of the two singlets in the range of O(10) MeV-O(10) GeV, with a neutrino portal interaction which plays important roles not only in particle physics but also in cosmology and astronomy. We point out that the dark matter abundance can be thermally explained with (co)annihilation, where the dark matter with a mass greater than 2 GeV can be tested in future lepton colliders, CEPC, ILC, FCC-ee and CLIC, in the light of the Higgs boson invisible decay. When the gauge singlets are lighter than O(100)MeV, the interaction can affect the neutrino propagation in the universe due to its annihilation with the cosmic background neutrino into the gauge singlets. Although can not be the dominant dark matter in this case, the singlets are produced by the invisible decay of the Higgs boson at a rate fully within the reach of the future lepton colliders. In particular, a high energy cutoff of cosmic-ray neutrino, which may account for the non-detection of Greisen-Zatsepin-Kuzmin (GZK) neutrinos or non-observation of Glashow resonance, can be set. Interestingly, given the cutoff and the mass (range) of the WIMP, a neutrino mass can be "measured" kinematically.

   hep-phastro-ph.HEhep-exCPC(2019)·5 citations
10. 10*

    ISR effects on loop corrections of a top pair-production at the ILC

    Junpei Fujimot · Yoshimasa Kurihara · Nhi M. U. Quach

    Precise predictions for an $e^{+}{e}^{-}\to t\bar{t}$ cross-section are presented in the energy region from 400 GeV to 800 GeV. Cross-sections are estimated including the beam-polarization effects with full $\mathcal{O}(\alpha )$, and also with the effects of the initial-state photon emission. A radiator technique is used for the initial-state photon emission up to two-loop orders. In this investigation, a weak correction is defined as the full electroweak corrections without the initial-state photonic corrections. As a result, it is determined that the total cross-section of a top quark pair-production receives the weak corrections of $+4\%$ over the trivial initial state corrections at a center of mass energy of 500 GeV. Among the initial state contributions, a contribution from two-loop diagrams gives less than $0.11\%$ correction over the one-loop ones at the center of mass energies of from $400$ GeV to $800$ GeV. In addition, the effect of a running coupling constant is also discussed.

    hep-phJ.Phys.Conf.Ser.(2017)·2 citations
11. 11*

    Thermal Dark Matter Below an MeV

    Asher Berlin🇺🇸 · Nikita Blinov🇺🇸

    We consider a class of models in which thermal dark matter is lighter than an MeV. If dark matter thermalizes with the Standard Model below the temperature of neutrino-photon decoupling, equilibration and freeze-out cools and heats the Standard Model bath comparably, alleviating constraints from measurements of the effective number of neutrino species. We demonstrate this mechanism in a model consisting of fermionic dark matter coupled to a light scalar mediator. Thermal dark matter can be as light as a few keV, while remaining compatible with existing cosmological and astrophysical observations. This framework motivates new experiments in the direct search for sub-MeV thermal dark matter and light force carriers.

    hep-phastro-ph.COPRL(2018)·109 citations
12. 12*

    A determination of the fragmentation functions of pions, kaons, and protons with faithful uncertainties

    Valerio Bertone🇳🇱 · Stefano Carrazza🇨🇭 · Nathan P. Hartland🇳🇱 · Emanuele R. Nocera🇬🇧 · Juan Rojo🇳🇱

    We present NNFF1.0, a new determination of the fragmentation functions (FFs) of charged pions, charged kaons, and protons/antiprotons from an analysis of single-inclusive hadron production data in electron-positron annihilation. This determination, performed at leading, next-to-leading, and next-to-next-to-leading order in perturbative QCD, is based on the NNPDF methodology, a fitting framework designed to provide a statistically sound representation of FF uncertainties and to minimise any procedural bias. We discuss novel aspects of the methodology used in this analysis, namely an optimised parametrisation of FFs and a more efficient ${\chi }^2$ minimisation strategy, and validate the FF fitting procedure by means of closure tests. We then present the NNFF1.0 sets, and discuss their fit quality, their perturbative convergence, and their stability upon variations of the kinematic cuts and the fitted dataset. We find that the systematic inclusion of higher-order QCD corrections significantly improves the description of the data, especially in the small-$z$ region. We compare the NNFF1.0 sets to other recent sets of FFs, finding in general a reasonable agreement, but also important differences. Together with existing sets of unpolarised and polarised parton distribution functions (PDFs), FFs and PDFs are now available from a common fitting framework for the first time.

    hep-phhep-exnucl-exnucl-thEPJC(2017)·219 citations
13. 13*

    Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

    Vincenzo Cirigliano🇺🇸 · Mark W. Paris🇺🇸 · Shashank Shalgar🇺🇸

    We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. We further consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavor instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength.

    hep-phastro-ph.COnucl-thPLB(2017)·21 citations
14. 14*

    Collider constraints and new tests of color octet vectors

    Malte Buschmann🇩🇪 · Felix Yu🇩🇪

    We analyze the collider sensitivity for new colored resonances in $t\bar{t}$, $b\bar{b}$, and $jj$ final states. While searches in the single production channel are model-dependent, the pair production rate is model independent and the existing $(JJ)(JJ)$ and $4t$ searches impose strong constraints on the relevant branching fractions, where $J=j$ or $b$. We point out the missing, complementary searches in the mixed decay modes, $t\bar{t}(jj)$, $t\bar{t}(b\bar{b})$, and $(b\bar{b})(jj)$. We propose analysis strategies for the $t\bar{t}(jj)$ and $t\bar{t}(b\bar{b})$ decays and find their sensivity surpasses that of existing searches when the decay widths to tops and light jets are comparable. If no other decays are present, collective lower limits on the resonance mass can be set at 1.5~TeV using 37~fb${}^{-1}$ of 13~TeV data.

    hep-phJHEP(2017)·3 citations
15. 15*

    Extended Hamiltonian Formalism and Lorentz-Violating Lagrangians

    Don Colladay🇺🇸

    A new perspective on the classical mechanical formulation of particle trajectories in lorentz-violating theories is presented. Using the extended hamiltonian formalism, a Legendre Transformation between the associated covariant Lagrangian and Hamiltonian varieties is constructed. This approach enables calculation of trajectories using hamilton's equations in momentum space and the Euler-Lagrange equations in velocity space away from certain singular points that arise in the theory. Singular points are naturally de-singularized by requiring the trajectories to be smooth functions of both velocity and momentum variables. In addition, it is possible to identify specific sheets of the dispersion relations that correspond to specific solutions for the lagrangian. Examples corresponding to bipartite Finsler functions are computed in detail. A direct connection between the lagrangians and the field-theoretic solutions to the Dirac equation is also established for a special case.

    ↳ hep-thhep-phPLB(2017)·26 citations
16. 16*

    Accuracy of the lepton-nucleus scattering models in the quasielastic region

    Joanna Ewa Sobczyk🇵🇱

    We present a discussion of models of nuclear effects used to describe an inclusive electron-nucleus scattering in the quasielastic (QE) peak region, aiming to compare them and draw conclusion of their reliability when applied in neutrino-nucleus interactions. A basic motivation is to reduce systematic errors in neutrino oscillation experiments. We concentrate on the neutrino energy profile of the T2K experiment, which provides us a region of the greatest importance in terms of the highest contribution to the charge-current quasielastic (CCQE) cross section. We choose only electron-nucleus data that overlaps with this region. In order to clearify the analysis, we split the data sets into three groups and draw conclusion separately from each one of them. We selected six models for this comparison: Benhar's spectral function with and without final state interaction (Benhar's SF+FSI), Valencia spectral function (Valencia SF), for higher energy transfer only with the hole spectral function; GiBUU and also the local and global Fermi gas models. The latter two are included as a benchmark to quantify the effect of various nuclear effects. All the six models are often used in neutrino scattering studies. A short theoretical description of each model is given. Although in the selected data sets the QE mechanism dominates, we also briefly discuss a possible impact of $2p2h$ and $\Delta$ contributions.

    ↳ nucl-thhep-exhep-phPRC(2017)·26 citations
17. 17*

    Linear scale bounds on dark matter--dark radiation interactions and connection with the small scale crisis of cold dark matter

    Maria Archidiacono🇩🇪 · Sebastian Bohr🇩🇪 · Steen Hannestad🇩🇰 · Jonas Helboe Jørgensen🇩🇰 · Julien Lesgourgues🇩🇪

    One of the open questions in modern cosmology is the small scale crisis of the cold dark matter paradigm. Increasing attention has recently been devoted to self-interacting dark matter models as a possible answer. However, solving the so-called "missing satellites" problem requires in addition the presence of an extra relativistic particle (dubbed dark radiation) scattering with dark matter in the early universe. Here we investigate the impact of different theoretical models devising dark matter dark radiation interactions on large scale cosmological observables. We use cosmic microwave background data to put constraints on the dark radiation component and its coupling to dark matter. We find that the values of the coupling allowed by the data imply a cut-off scale of the halo mass function consistent with the one required to match the observations of satellites in the Milky Way.

    ↳ astro-ph.COhep-phJCAP(2017)·42 citations
18. 18*

    Searching for sterile neutrinos in dynamical dark energy cosmologies

    Lu Feng🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    We investigate how the dark energy properties change the cosmological limits on sterile neutrino parameters by using recent cosmological observations. We consider the simplest dynamical dark energy models, the $w$CDM model and the holographic dark energy (HDE) model, to make an analysis. The cosmological observations used in this work include the Planck 2015 CMB temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova data, the Hubble constant direct measurement data, and the Planck CMB lensing data. We find that, $m_{\nu ,\mathrm{sterile}}^{\mathrm{eff}}<0.2675$ eV and $N_{\mathrm{eff}}<3.5718$ for $\Lambda$CDM cosmology, $m_{\nu ,\mathrm{sterile}}^{\mathrm{eff}}<0.5313$ eV and $N_{\mathrm{eff}}<3.5008$ for $w$CDM cosmology, and $m_{\nu ,\mathrm{sterile}}^{\mathrm{eff}}<0.1989$ eV and $N_{\mathrm{eff}}<3.6701$ for HDE cosmology, from the constraints of the combination of these data. Thus, without the addition of measurements of growth of structure, only upper limits on both $m_{\nu ,\mathrm{sterile}}^{\mathrm{eff}}$ and $N_{\mathrm{eff}}$ can be derived, indicating that no evidence of the existence of a sterile neutrino species with eV-scale mass is found in this analysis. Moreover, compared to the $\Lambda$CDM model, in the $w$CDM model the limit on $m_{\nu ,\mathrm{sterile}}^{\mathrm{eff}}$ becomes much looser, but in the HDE model the limit becomes much tighter. Therefore, the dark energy properties could significantly influence the constraint limits of sterile neutrino parameters.

    ↳ astro-ph.COgr-qchep-phSCPMA(2018)·48 citations
19. 19*

    High-Energy Gamma Rays and Neutrinos from Nearby Radio Galaxies

    Carlos Blanco🇺🇸 · Dan Hooper🇺🇸

    Multi-messenger data suggest that radio galaxies (i.e. non-blazar active galaxies) are perhaps the most likely class of sources for the diffuse flux of high-energy neutrinos reported by the IceCube Collaboration. In this study, we consider the gamma-ray spectrum observed from four nearby radio galaxies (Centaurus A, PKS 0625-35, NGC 1275 and IC 310) and constrain the intensity and spectral shape of the emission injected from these sources, accounting for the effects of attenuation and contributions from electromagnetic cascades (initiated both within the radio galaxy itself and during extragalactic propagation). Assuming that this gamma-ray emission is generated primarily through the interactions of cosmic-ray protons with gas, we calculate the neutrino flux predicted from each of these sources. Although this scenario is consistent with the constraints published by the IceCube and ANTARES Collaborations, the predicted fluxes consistently fall within an order of magnitude of the current point source sensitivity. The prospects appear very encouraging for the future detection of neutrino emission from the nearest radio galaxies.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phJCAP(2017)·16 citations
20. 20*

    The Tetraquark Candidate Zc(3900) from Dynamical Lattice QCD Simulations

    Yoichi Ikeda (1 and 2, for HAL QCD Collaboration) · ((1) RCNP, Osaka Univ. and (2) Nishina Center, RIKEN)

    The structure of the tetraquark candidate $Z_c(3900)$, which was experimentally reported in $e^{+}{e}^{-}$ collisions, is studied by the s-wave meson-meson coupled-channel scattering on the lattice. The s-wave interactions among the $\pi J/\psi$, $\rho {\eta }_c$ and $D{\bar{D}}^{\ast }$ channels are derived from (2+1)-flavor dynamical QCD simulations at $m_{\pi }=410$--$700$ MeV. It is found that the interactions are dominated by the off-diagonal $\pi J/\psi$-$D{\bar{D}}^{\ast }$ and $\rho {\eta }_c$-$D{\bar{D}}^{\ast }$ couplings. With the interactions obtained, the s-wave two-body amplitudes and the pole position in the $\pi J/\psi$-$\rho {\eta }_c$-$D{\bar{D}}^{\ast }$ coupled-channel scattering are calculated. The results show that the $Z_c(3900)$ is not a conventional resonance but a threshold cusp. A semiphenomenological analysis with the coupled-channel interaction to the experimentally observed decay mode is also presented to confirm the conclusion.

    ↳ hep-lathep-phnucl-thJ.Phys.G(2018)·46 citations
21. 21*

    Lagrangian and Hamiltonian formulations of the Palatini action

    SangChul Yoon🇰🇷

    We derive the Ashtekar-Barbero variables in Loop Quantum Gravity(LQG) starting from the Palatini action. We find that we need either the torsion-free condition or the compatibility condition for the Palatini action to describe General Relativity.

    ↳ gr-qchep-phhep-th0 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.