Mon·Feb 11, 2019Monday·February 11, 2019

1. 01*

   Threshold effects in heavy quarkonium spectroscopy

   J. Ferretti🇺🇸

   In this contribution, we discuss the possible importance of continuum-coupling (or threshold) effects in heavy quarkonium spectroscopy. Our calculations are carried out in a coupled-channel model, where meson-meson higher Fock (or molecular-type) components are introduced in $Q\bar{Q}$ bare meson wave functions by means of a pair-creation mechanism. After providing a quick resume of the main characteristics of the coupled-channel model, we briefly discuss its application to the calculation of the masses of heavy quarkonium-like ${\chi }_{\mathrm{c}}(2P)$ and ${\chi }_{\mathrm{b}}(3P)$ states with threshold corrections. We show that the introduction of pair-creation effects in the Quark Model (QM) formalism makes it possible to explain the deviations of ${\chi }_{\mathrm{c}}(2P)$ states' masses from the experimental data, without affecting the good QM description of the properties of ${\chi }_{\mathrm{b}}(3P)$ states.

   hep-phAIP Conf.Proc.(2019)·2 citations
2. 02*

   Electromagnetic properties of singly heavy baryons

   June-Young Kim🇰🇷 · Hyun-Chul Kim🇰🇷

   In the present talk, we report recent results on electromagnetic properties of the baryon decuplet within the SU(3) chiral quark-soliton model, taking into account the effects of explicit flavor SU(3) symmetry breaking. We focus on the comparison of the present results on the electromagnetic form factors of the ${\Delta }^{+}$ baryon with the lattice data.

   hep-phhep-exJPS Conf.Proc.(2019)·1 citation
3. 03*

   Structure of heavy baryons in a pion mean-field approach

   Hyun-Chul Kim🇰🇷

   In this talk, we briefly review a series of recent works on singly heavy baryons, based on a pion mean-field approach. In the limit of the infinitely heavy quark mass, heavy baryons are governed mainly by the light degress of freedom. Taking the number of colors to be infinity, a heavy baryon arises as a state consisting of $N_c-1$ valence quarks bound by the pion mean fields created self-consistently. Within this framework, we present the results of the mass spectra of the charmed and bottom baryons, and their magnetic moments. The behavior of the electromagnetic form factors will be also mentioned.

   hep-phhep-exJPS Conf.Proc.(2019)·3 citations
4. 04*

   Enhancing the hierarchy and octant sensitivity of ESS$\nu$SB in conjunction with T2K, NO$\nu$A and ICAL@INO

   Kaustav Chakraborty🇮🇳 · Srubabati Goswami🇮🇳 · Chandan Gupta🇮🇳 · Tarak Thakore🇪🇸

   The main aim of the ESS$\nu$SB proposal is the discovery of the leptonic CP phase ${\delta }_{CP}$ with a high significance ($5\sigma$ for 50% values of ${\delta }_{CP}$) by utilizing the physics at the second oscillation maxima of the $P_{\mu e}$ channel. It can achieve $3\sigma$ sensitivity to hierarchy for all values of ${\delta }_{CP}$. In this work, we concentrate on the hierarchy and octant sensitivity of the ESS$\nu$SB experiment. We show that combining the ESS$\nu$SB experiment with the atmospheric neutrino data from the proposed India-based Neutrino Observatory(INO) experiment can result in an increased sensitivity to mass hierarchy. In addition, we also combine the results from the ongoing experiments T2K and NO$\nu$A assuming their full runtime and present the combined sensitivity of ESS$\nu$SB + ICAL@INO + T2K + NO$\nu$A. We show that while by itself ESS$\nu$SB can have up to $3\sigma$ hierarchy sensitivity, the combination of all the experiments can give up to $5\sigma$ sensitivity depending on the true hierarchy-octant combination. The octant sensitivity of ESS$\nu$SB is low by itself. However the combined sensitivity of all the above experiments can give up to $3\sigma$ sensitivity depending on the choice of true hierarchy and octant. We discuss the various degeneracies and the synergies that lead to the enhanced sensitivity when combining different experimental data.

   hep-phhep-exJHEP(2019)·16 citations
5. 05*

   Search for single production of a top quark partner via the $T\to th$ and $h\to W{W}^{\ast }$ channels at the LHC

   Yao-Bei Liu🇨🇳 · Stefano Moretti🇬🇧

   Many scenarios of physics beyond the Standard Model that address the hierarchy problem also predict the existence of vector-like top quark partners, which are generally expected around the TeV scale. In this paper, we propose to search for a vector-like top quark partner with charge $2/3$ in a simplified model including only two free parameters, the coupling constant $g^{\ast }$ and top quark partner mass $m_T$. We investigate the observability of the top quark partner through the process $pp\to T(\to th)j\to t(\to b{W}^{+}\to b{\ell }^{+}{\nu }_{\ell })h(\to W{W}^{\ast }\to {\ell }^{+}\nu {\ell }^{-}\bar{\nu })j$, where $T$ is the heavy top quark partner and $h$ the SM-like Higgs boson, at the Large Hadron Collider (LHC). The discovery prospects and exclusion limits on the parameter plane defined by ($m_T,g^{\ast }$) are obtained for the already scheduled LHC runs as well as at the future High-Luminosity~LHC (HL-LHC). The constraints and projected sensitivities are also interpreted in a realistic model, i.e., the minimal Composite Higgs Model with singlet top quark partners. We finally also analyze the projected sensitivity in terms of the production cross section times branching fraction at the (HL-)LHC.

   hep-phPRD(2019)·28 citations
6. 06*

   A critical point in the distribution of lepton energies from the decay of a spin-1 resonance

   Lorenzo Bianchini🇮🇹 · Gigi Rolandi🇮🇹

   We consider a spin-$1$ resonance produced with an arbitrary spectrum of velocities and decaying into a pair of massless leptons, and we study the probability density function of the energy of the leptons in the laboratory frame. A special case is represented by the production of $W$ bosons in proton-proton collisions, for which the energy of the charged lepton from the decaying $W$ can be measured with sufficient accuracy for a high-precision measurement of $M_W$. We find that half of the resonance mass is a special value of the lepton energy, since the probability density function at this point is in general not analytic for a narrow-width resonance. In particular, the higher-order derivatives of the density function are likely to develop singularities, such as cusps or poles. A finite width of the resonance restores the regularity, for example by smearing cusps and poles into local stationary points. The quest for such points offers a handle to estimate the resonance mass with much reduced dependence on the underlying production and decay dynamics of the resonance.

   hep-phhep-exJHEP(2019)·5 citations
7. 07*

   Top quark anomalous FCNC production via $tqg$ couplings at FCC-hh

   K. Y. Oyulmaz🇹🇷 · A. Senol🇹🇷 · H. Denizli🇹🇷 · O. Cakir🇹🇷

   We investigate the top quark anomalous Flavor Changing Neutral Current (FCNC) $tqg$ interactions to probe limits on the couplings ${\zeta }_c$ and ${\zeta }_u$ through the $qg\to l\nu b$ signal suprocess at FCC-hh collider with center of mass energy of 100 TeV. To separate signal from relevant Standard Model background processes, selection criteria based on Boosted Decision Trees (BDT) is used with a set of useful kinematic variables. The sensitivities on the anomalous top FCNC couplings ${\zeta }_u$ and ${\zeta }_c$ are found to be $1.239\times 10^{-4}$ and $1.149\times 10^{-4}$ for FCC-hh with $L_{int}$=10 ab${}^{-1}$ at 95 \% C.L. including realistic detector effects of the FCC-hh baseline detector, respectively. The branchings $BR(t\to ug)$ and $BR(t\to cg)$ converted from obtained limits for FCNC couplings are at the order of $10^{-7}$ which is at least one order of magnitude better than the projected limits of HL-LHC with $L_{int}$= 3 ab${}^{-1}$.

   hep-phPRD(2019)·18 citations
8. 08*

   Heavy-quark spin and flavour symmetry partners of the X(3872) revisited: what can we learn from the one boson exchange model?

   Ming-Zhu Liu🇨🇳 · Tian-Wei Wu🇨🇳 · Manuel Pavon Valderrama🇨🇳 · Ju-Jun Xie🇨🇳 · Li-Sheng Geng🇨🇳

   Heavy-quark symmetry as applied to heavy hadron systems implies that their interactions are independent of their heavy-quark spin (heavy-quark spin symmetry) and heavy flavour contents (heavy flavour symmetry). In the molecular hypothesis the $X(3872)$ resonance is a $1^{++}$ $D^{\ast }\bar{D}$ bound state. If this is the case, the application of heavy-quark symmetry to a molecular $X(3872)$ suggests the existence of a series of partner states, the most obvious of which is a possible $2^{++}$ $D^{\ast }{\bar{D}}^{\ast }$ bound state for which the two-body potential is identical to that of the $1^{++}$ $D^{\ast }\bar{D}$ system, the reason being that these two heavy hadron-antihadron states have identical light-spin content. As already discussed in the literature this leads to the prediction of a partner state at $4012\mathrm{MeV}$, at least in the absence of other dynamical effects which might affect the location of this molecule. However the prediction of further heavy-quark symmetry partners cannot be done solely on the basis of symmetry and requires additional information. We propose to use the one boson exchange model to fill this gap, in which case we will be able to predict or discard the existence of other partner states. Besides the isoscalar $2^{++}$ $D^{\ast }{\bar{D}}^{\ast }$ bound state, we correctly reproduce the location and quantum numbers of the isovector hidden-bottom $Z_b(10610)$ and $Z_b(10650)$ molecular candidates. We also predict the hidden-bottom $1^{++}$ $B^{\ast }{\bar{B}}^{\ast }$ and $2^{++}$ $B^{\ast }{\bar{B}}^{\ast }$ partners of the $X(3872)$, in agreement with previous theoretical speculations, plus a series of other states. The isoscalar, doubly charmed $1^{+}$ $D{D}^{\ast }$ and $D^{\ast }{D}^{\ast }$ molecules and their doubly bottomed counterparts are likely to bind, providing a few instances of explicitly exotic systems.

   hep-phhep-exhep-latnucl-thPRD(2019)·144 citations
9. 09*

   BSM constraints from model-independent measurements: A Contur Update

   J. M. Butterworth🇬🇧

   Particle-level measurements, especially of differential cross-sections, made in fiducial regions of phase-space have a high degree of model-independence and can therefore be used to give information about a wide variety of Beyond the Standard Model (BSM) physics implemented in Monte Carlo generators, using a broad range of final states. The Contur package is used to make such comparisons. We summarise a snapshot of current results for a number of BSM scenarios; a UV complete model in which the global Baryon-number minus Lepton-number symmetry is gauged; several Dark Matter simplified models, and two generic light scalar models.

   hep-phhep-exJ.Phys.Conf.Ser.(2019)·8 citations
10. 10*

    Process dependence of the gluon Sivers function in inclusive $pp$ collisions: theory

    Cristian Pisano🇮🇹 · Umberto D'Alesio🇮🇹 · Carlo Flore🇮🇹 · Francesco Murgia🇮🇹 · Pieter Taels🇮🇹

    Within the color gauge invariant generalized parton model (CGI-GPM), which includes initial and final state interactions in a transverse momentum dependent formalism, we present the complete results, at leading order in perturbative QCD, for transverse single-spin asymmetries in the inclusive hadroproduction of $J/\psi$ and $D$ mesons, pions and direct photons.

    hep-phPoS(2019)·1 citation
11. 11*

    Chiral constraints on the isoscalar electromagnetic spectral functions of the nucleon from leading order vector meson couplings

    Y. Ünal🇹🇷 · Ulf-G. Meißner🇩🇪

    Using baryon chiral perturbation theory including vector mesons, we analyse various continuum contributions to the isoscalar electromagnetic spectral functions of the nucleon induced by the leading order couplings.

    hep-phnucl-thPLB(2019)·5 citations
12. 12*

    Thermal contribution of unstable states

    Pok Man Lo🇵🇱 · Francesco Giacosa🇵🇱

    Within the framework of the Lee model, we analyze in detail the difference between the energy derivative of the phase shift and the standard spectral function of the unstable state. The fact that the model is exactly solvable allows us to demonstrate the construction of these observables from various exact Green functions. The connection to a formula due to Krein, Friedal, and Lloyd is also examined. We also directly demonstrate how the derivative of the phase shift correctly identifies the relevant interaction contributions for consistently including an unstable state in describing the thermodynamics.

    hep-phcond-mat.stat-mechnucl-thEPJC(2019)·17 citations
13. 13*

    Jet quenching as a probe of the initial stages in heavy-ion collisions

    Carlota Andres🇺🇸 · Néstor Armesto🇪🇸 · Harri Niemi🇫🇮 · Risto Paatelainen🇨🇭 · Carlos A. Salgado🇪🇸

    Jet quenching provides a very flexible variety of observables which are sensitive to different energy- and time-scales of the strongly interacting matter created in heavy-ion collisions. Exploiting this versatility would make jet quenching an excellent chronometer of the yoctosecond structure of the evolution process. Here we show, for the first time, that a combination of jet quenching observables is sensitive to the initial stages of heavy-ion collisions, when the approach to local thermal equilibrium is expected to happen. Specifically, we find that in order to reproduce at the same time the inclusive particle production suppression, $R_{AA}$, and the high-$p_T$ azimuthal asymmetries, $v_2$, energy loss must be strongly suppressed for the first $\sim 0.6$ fm. This exploratory analysis shows the potential of jet observables, possibly more sophisticated than the ones studied here, to constrain the dynamics of the initial stages of the evolution.

    hep-phnucl-exnucl-thPLB(2020)·94 citations
14. 14*

    Bayesian and frequentist approaches to resonance searches

    Andrew Fowlie🇨🇳

    We investigate Bayesian and frequentist approaches to resonance searches using a toy model based on an ATLAS search for the Higgs boson in the diphoton channel. We draw pseudo-data from the background only model and background plus signal model at multiple luminosities, from $10^{-3}$/fb to $10^7$/fb. We chart the change in the Bayesian posterior of the background only model and the global p-value. We find that, as anticipated, the posterior converges to certainty about the model as luminosity increases. The p-value, on the other hand, randomly walks between 0 and 1 if the background only model is true, and otherwise converges to 0. After briefly commenting on the frequentist properties of the posterior, we make a direct comparison of the significances obtained in Bayesian and frequentist frameworks. We find that the well-known look-elsewhere effect reduces local significances by about 1$\sigma$. We furthermore find that significances from our Bayesian framework are typically about 1 to 2$\sigma$ smaller than the global significances, though the reduction depends on the prior, global significance and integrated luminosity. This suggests that even global significances could significantly overstate the evidence against the background only model. We checked that this effect --- the Bayes effect --- was robust with respect to fourteen choices of prior and investigated the Jeffreys-Lindley paradox for three of them.

    hep-phhep-exphysics.data-anJINST(2019)·9 citations
15. 15*

    Millicharged Particles in Liquid Argon Neutrino Experiments

    Roni Harnik🇺🇸 · Zhen Liu🇺🇸 · Ornella Palamara🇺🇸

    We investigate the potential of Liquid Argon (LAr) neutrino detectors to search for millicharged particles, a well-motivated extension of the standard model. Detectors located downstream of an intense proton beam that is striking a target may be exposed to a large flux of millicharged particles. Millicharged particles interact primarily through low momentum exchange producing electron recoil events near detector threshold. Recently, sub-MeV detection capabilities were demonstrated by the Fermilab ArgoNeuT detector, a small LAr detector which was exposed to the NuMI neutrino beam. Despite high background rates and its small size, we show that ArgoNeuT is capable of probing unexplored parameter space with its existing dataset. In particular, we show that the excellent spatial resolution in LAr detectors allows rejecting backgrounds by requiring two soft hits that are aligned with the upstream target. We further discuss the prospects of these types of searches in future larger LAr neutrino detectors such as the DUNE near detector.

    hep-phhep-exphysics.ins-detJHEP(2019)·81 citations
16. 16*

    f(R) and Brans-Dicke Theories and the Swampland

    Michal Artymowski🇮🇱 · Ido Ben-Dayan🇮🇱

    We discuss the viability of $f(R)$ and Brans-Dicke theories of gravity in light of the recent Swampland conjectures. We show that in the case of perfect fluid domination the swampland conjecture conditions may be easily satisfied and therefore we focus on the constraints in the vacuum theory. We derive the conditions for the swampland conjectures in $f(R)$ and Brans-Dicke framework, and find that a large portion of the parameter space is not allowed. Furthermore, we analyze particular $f(R)$ models of inflation and dark energy and in their case we set the allowed range of $R$.

    ↳ gr-qchep-phhep-thJCAP(2019)·33 citations
17. 17*

    Limits on contact interactions and leptoquarks at HERA

    ZEUS Collaboration

    High-precision HERA data corresponding to a luminosity of around 1 fb${}^{-1}$ have been used in the framework of $eeqq$ contact interactions (CI) to set limits on possible high-energy contributions beyond the Standard Model to electron-quark scattering. Measurements of the inclusive deep inelastic cross sections in neutral and charged current $ep$ scattering were considered. The analysis of the $ep$ data has been based on simultaneous fits of parton distribution functions including contributions of CI couplings to $ep$ scattering. Several general CI models and scenarios with heavy leptoquarks were considered. Improvements in the description of the inclusive HERA data were obtained for a few models. Since a statistically significant deviation from the Standard Model cannot be established, limits in the TeV range were set on all models considered.

    ↳ hep-exhep-phPRD(2019)·34 citations
18. 18*

    Non-sphericity of ultralight axion dark matter haloes in the Galactic dwarf spheroidal galaxies

    Kohei Hayashi🇯🇵 · Ippei Obata🇯🇵

    Ultralight-axion (ULA) dark matter is one of the possible solutions to resolve small-scale problems, especially the core-cusp problem. This is because ULA dark matter can create a central soliton core in all dark matter haloes stemmed from the quantum pressure against gravity below the de Broglie wavelength, which becomes manifest on astrophysical scales with axion mass range $\sim 10^{-22}$ eV. In this work, we apply our non-spherical dynamical models to the kinematic data of eight classical dwarf spheroidals (dSphs) to obtain more reliable and realistic limits on ULA particle mass. This is motivated by the reasons that the light distributions of the dSphs are not spherical, nor are the shapes of dark matter haloes predicted by ULA dark matter simulations. Compared with the previous studies on ULA dark matter assuming spherical mass models, our result is less stringent than those constraints due to the uncertainties on non-sphericity. On the other hand, remarkably, we find that the dSphs would prefer to have a flattened dark matter halo rather than a spherical one, especially Draco favours a strongly elongated dark matter halo caused naively by the assumption of a soliton-core profile. Moreover, our consequent non-spherical core profiles are much more flattened than numerical predictions based on ULA dark matter, even though there are still uncertainties on the estimation of dark matter halo structure. To alleviate this discrepancy, further understanding of baryonic and/or ULA dark matter physics on small mass scales might be needed.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2020)·16 citations
19. 19*

    Symmetries of spatial meson correlators in high temperature QCD

    C. Rohrhofer🇦🇹 · Y. Aoki🇯🇵 · G. Cossu🇬🇧 · H. Fukaya🇯🇵 · C. Gattringer🇦🇹 · L.Ya. Glozman🇦🇹 · S. Hashimoto🇯🇵 · C.B. Lang🇦🇹 · S. Prelovsek🇸🇮

    Based on a complete set of $J=0$ and $J=1$ spatial isovector correlation functions calculated with $N_F=2$ domain wall fermions we identify an intermediate temperature regime of $T\sim 220-500$ MeV ($1.2T_c$--$2.8T_c$), where chiral symmetry is restored but the correlators are not yet compatible with a simple free quark behavior. More specifically, in the temperature range $T\sim 220-500$ MeV we identify a multiplet structure of spatial correlators that suggests emergent $SU(2{)}_{CS}$ and $SU(4)$ symmetries, which are not symmetries of the free Dirac action. The symmetry breaking effects in this temperature range are less than 5%. Our results indicate that at these temperatures the chromo-magnetic interaction is suppressed and the elementary degrees of freedom are chirally symmetric quarks bound into color-singlet objects by the chromo-electric component of the gluon field. At temperatures between 500 and 660 MeV the emergent $SU(2{)}_{CS}$ and $SU(4)$ symmetries disappear and one observes a smooth transition to the regime above $T\sim 1$ GeV where only chiral symmetries survive, which are finally compatible with quasi-free quarks.

    ↳ hep-lathep-phhep-thnucl-thPRD(2019)·81 citations
20. 20*

    Baryon acoustic oscillation, Hubble parameter, and angular size measurement constraints on the Hubble constant, dark energy dynamics, and spatial curvature

    Joseph Ryan🇺🇸 · Yun Chen🇨🇳 · Bharat Ratra🇺🇸

    In this paper we use all available baryon acoustic oscillation, Hubble parameter, and quasar angular size data to constrain six dark energy cosmological models, both spatially flat and non-flat. Depending on the model and data combination considered, these data mildly favor closed spatial hypersurfaces (by as much as $1.7\sigma$) and dark energy dynamics (up to a little over $2\sigma$) over a cosmological constant $\Lambda$. The data also favor, at $1.8\sigma$ to $3.4\sigma$, depending on the model and data combination, a lower Hubble constant than what is measured from the local expansion rate.

    ↳ astro-ph.COgr-qchep-phhep-thMNRAS(2019)·128 citations
21. 21*

    Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T

    E. Aprile🇺🇸 · J. Aalbers🇳🇱 · F. Agostini🇮🇹 · M. Alfonsi🇩🇪 · L. Althueser🇩🇪 · F. D. Amaro🇵🇹 · M. Anthony🇺🇸 · V. C. Antochi🇸🇪 · F. Arneodo🇦🇪 · L. Baudis🇨🇭 · B. Bauermeister🇸🇪 · M. L. Benabderrahmane🇦🇪 and 118 other authors

    We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of $6.3\times 10^{-42}$ cm${}^2$ at 30 GeV/c${}^2$ and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.

    ↳ astro-ph.COhep-phPRL(2019)·340 citations
22. 22*

    Amplitudes' Positivity, Weak Gravity Conjecture, and Modified Gravity

    Brando Bellazzini🇫🇷 · Matthew Lewandowski🇫🇷 · Javi Serra🇩🇪

    We derive new positivity bounds for scattering amplitudes in theories with a massless graviton in the spectrum in four spacetime dimensions, of relevance for the weak gravity conjecture and modified gravity theories. The bounds imply that extremal black holes are self-repulsive, $M/|Q|<1$ in suitable units, and that they are unstable to decay to smaller extremal black holes, providing an S-matrix proof of the weak gravity conjecture. We also present other applications of our bounds to the effective field theory of axions, $P(X)$ theories, weakly broken galileons, and curved spacetimes.

    ↳ hep-thgr-qchep-phPRL(2019)·217 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.