Thu·Oct 25, 2018Thursday·October 25, 2018

1. 01*

   Revisiting spin-dependent forces mediated by new bosons: Potentials in the coordinate-space representation for macroscopic- and atomic-scale experiments

   Pavel Fadeev🇩🇪 · Yevgeny V. Stadnik🇩🇪 · Filip Ficek🇵🇱 · Mikhail G. Kozlov🇷🇺 · Victor V. Flambaum🇦🇺 · Dmitry Budker🇩🇪

   The exchange of spin-0 or spin-1 bosons between fermions or spin-polarised macroscopic objects gives rise to various spin-dependent potentials. We derive the coordinate-space non-relativistic potentials induced by the exchange of such bosons, including contact terms that can play an important role in atomic-scale phenomena, and correct for errors and omissions in the literature. We summarise the properties of the potentials and their relevance for various types of experiments. These potentials underpin the interpretation of experiments that search for new bosons, including spectroscopy, torsion-pendulum measurements, magnetometry, parity nonconservation and electric dipole moment experiments.

   hep-phphysics.atom-phPRA(2019)·129 citations
2. 02*

   $Z\to {\pi }^{+}{\pi }^{-},K^{+}{K}^{-}$: A touchstone of the PQCD approach

   Shan Cheng🇨🇳 · Qin Qin🇩🇪

   We study two rare decays, $Z\to {\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$, in the perturbative QCD approach up to the next-to-leading order of the strong coupling and the leading power of $1/m_Z$, $m_Z$ being the $Z$ boson mass. The branching ratios $\mathcal{B}(Z\to {\pi }^{+}{\pi }^{-})=(0.83\pm 0.02\pm 0.02\pm 0.04)\times 10^{-12}$ and $\mathcal{B}(Z\to K^{+}{K}^{-})=(1.74_{-0.05}^{+0.03}\pm 0.04\pm 0.02)\times 10^{-12}$ are obtained and can be measured at a tera-$Z$ factory. Because the subleading-power contributions to the branching ratios are negligible, and the leading one does not depend on any free parameter, the two channels can serve as a touchstone for the applicability of the perturbative QCD approach.

   hep-phhep-exPRD(2019)·13 citations
3. 03*

   Novel direct detection constraints on light dark matter

   Torsten Bringmann🇳🇴 · Maxim Pospelov🇨🇦

   All attempts to directly detect particle dark matter (DM) scattering on nuclei suffer from the partial or total loss of sensitivity for DM masses in the GeV range or below. We derive novel constraints from the inevitable existence of a subdominant, but highly energetic, component of DM generated through collisions with cosmic rays. Subsequent scattering inside conventional DM detectors, as well as neutrino detectors sensitive to nuclear recoils, limits the DM-nucleon scattering cross section to be below $10^{-31}$ cm${}^2$ for both spin-independent and spin-dependent scattering of light DM.

   hep-phastro-ph.COPRL(2019)·375 citations
4. 04*

   Colorful Imprints of Heavy States in the Electroweak Effective Theory

   Claudius Krause🇺🇸 · Antonio Pich🇪🇸 · Ignasi Rosell🇪🇸 · Joaquín Santos🇪🇸 · Juan José Sanz-Cillero🇪🇸

   We analyze heavy states from generic ultraviolet completions of the Standard Model in a model-independent way and investigate their implications on the low-energy couplings of the electroweak effective theory. We build a general effective Lagrangian, implementing the electroweak symmetry breaking $SU(2{)}_L\otimes SU(2{)}_R\to SU(2{)}_{L+R}$ with a non-linear Nambu-Goldstone realization, which couples the known particles to the heavy states. We generalize the formalism developed in previous works~[1,2] to include colored resonances, both of bosonic and fermionic type. We study bosonic heavy states with $J^P=0^{\pm }$ and $J^P=1^{\pm }$, in singlet or triplet $SU(2{)}_{L+R}$ representations and in singlet or octet representations of $SU(3{)}_C$, and fermionic resonances with $J=\frac{1}{2}$ that are electroweak doublets and QCD triplets or singlets. Integrating out the heavy scales, we determine the complete pattern of low-energy couplings at the lowest non-trivial order. Some specific types of (strongly- and weakly-coupled) ultraviolet completions are discussed to illustrate the generality of our approach and to make contact with current experimental searches.

   hep-phJHEP(2019)·40 citations
5. 05*

   Prescaling and far-from-equilibrium hydrodynamics in the quark-gluon plasma

   Aleksas Mazeliauskas🇩🇪 · Jürgen Berges🇩🇪

   Prescaling is a far-from-equilibrium phenomenon which describes the rapid establishment of a universal scaling form of distributions much before the universal values of their scaling exponents are realized. We consider the example of the spatio-temporal evolution of the quark-gluon plasma explored in heavy-ion collisions at sufficiently high energies. Solving QCD kinetic theory with elastic and inelastic processes, we demonstrate that the gluon and quark distributions very quickly adapt a self-similar scaling form, which is independent of initial condition details and system parameters. The dynamics in the prescaling regime is then fully encoded in a few time-dependent scaling exponents, whose slow evolution gives rise to far-from-equilibrium hydrodynamic behavior.

   hep-phnucl-thPRL(2019)·82 citations
6. 06*

   S-Matrix approach to Compton scattering at the tree level in a strong magnetic field

   Jitendra Pal🇮🇳 · Binoy Krishna Patra🇮🇳

   We have studied the Compton scattering ($\gamma e^{-}⟶\gamma e^{-}$) at the tree level in a homogeneous background of strong magnetic field ($|eB|\gg m^2,\text{m is the mass of electron}$) through the S-matrix approach. For that purpose, using the Schwinger propagator for the electron, we have first calculated the square of the S-matrix element in the Landau gauge by summing over the final states of electron and photon and averaging over the initial states of the same. In the strong magnetic field, only the lowest Landau level for electron is considered. Finally we have computed the crosssection for Compton scattering as a function of initial photon energy for the different strengths of strong magnetic fields, where we have found that the crosssection in vacuum gets decreased due to the presence of strong magnetic field. However, for a fixed initial photon energy, the crosssection increases linearly with the magnetic field.

   hep-phhep-thnucl-th2 citations
7. 07*

   Origin of fermion generations from extended noncommutative geometry

   Hefu Yu🇨🇳 · Bo-Qiang Ma🇨🇳

   We propose a way to understand the 3 fermion generations by the algebraic structures of noncommutative geometry, which is a promising framework to unify the standard model and general relativity. We make the tensor product extension and the quaternion extension on the framework. Each of the two extensions alone keeps the action invariant, and we consider them as the almost trivial structures of the geometry. We combine the two extensions, and show the corresponding physical effects, i.e., the emergence of 3 fermion generations and the mass relationships among those generations. We define the coordinate fiber space of the bundle of the manifold as the space in which the classical noncommutative geometry is expressed, then the tensor product extension explicitly shows the contribution of structures in the non-coordinate base space of the bundle to the action. The quaternion extension plays an essential role to reveal the physical effect of the structure in the non-coordinate base space.

   ↳ hep-thgr-qchep-phmath-ph+1Int.J.Mod.Phys.A(2018)·0 citations
8. 08*

   Linear confinement and stress-energy tensor around static quark and anti-quark pair -- Lattice simulation with Yang-Mills gradient flow --

   Ryosuke Yanagihara🇯🇵 · Takumi Iritani🇯🇵 · Masakiyo Kitazawa🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsuo Hatsuda🇯🇵

   We study the spatial distribution of the stress tensor around static quark-anti-quark pair in SU(3) lattice gauge theory. In particular, we reveal the transverse structure of the stress tensor distribution in detail by taking the continuum limit. The Yang-Mills gradient flow plays a crucial role to make the stress tensor well-defined and derivable from the numerical simulations on the lattice.

   ↳ hep-lathep-phPoS(2019)·0 citations
9. 09*

   Observation of $e^{+}{e}^{-}\to \gamma {\chi }_{c1}$ and search for $e^{+}{e}^{-}\to \gamma {\chi }_{c0},\gamma {\chi }_{c2},$ and $\gamma {\eta }_c$ at $\sqrt{s}$ near 10.6 GeV at Belle

   Belle Collaboration: S. Jia · X. L. Wang · C. P. Shen · C. Z. Yuan · I. Adachi · H. Aihara · S. Al Said · D. M. Asner · H. Atmacan · V. Aulchenko · T. Aushev · R. Ayad and 180 other authors

   Using data samples of 89.5~fb${}^{-1}$, 711.0~fb${}^{-1}$, and 121.4~fb${}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider at center-of-mass energies 10.52 GeV, 10.58 GeV, and 10.867 GeV, respectively, we study the exclusive reactions $e^{+}{e}^{-}\to \gamma {\chi }_{cJ}$ ($J=0,1,2$) and $e^{+}{e}^{-}\to \gamma {\eta }_c$. A significant $\gamma {\chi }_{c1}$ signal is observed for the first time at $\sqrt{s}=10.58$ GeV with a significance of $5.1\sigma$ including systematic uncertainties. No significant excesses for $\gamma {\chi }_{c0}$, $\gamma {\chi }_{c2}$, and $\gamma {\eta }_c$ final states are found, and we set 90\% credibility level upper limits on the Born cross sections (${\sigma }_{\mathrm{B}}$) at 10.52 GeV, 10.58 GeV, and 10.867~GeV. Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of ${\sigma }_{\mathrm{B}}(e^{+}{e}^{-}\to \gamma {\chi }_{c1})$ is obtained.

   ↳ hep-exhep-phPRD(2018)·26 citations
10. 10*

    Can we probe Planckian corrections at the horizon scale with gravitational waves?

    Andrea Addazi🇨🇳 · Antonino Marciano🇨🇳 · Nicolas Yunes🇺🇸

    Future detectors could be used as a gravitational microscope to probe the horizon structure of merging black holes with gravitational waves. But can this microscope probe the quantum regime? We study this interesting question and find that (i) the error in the distance resolution is exponentially sensitive to errors in the Love number, and (ii) the uncertainty principle of quantum gravity forces a fundamental resolution limit. Thus, although the gravitational microscope can distinguish between black holes and other exotic objects, it is resolution limited well above the Planckian scale.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRL(2019)·40 citations
11. 11*

    Palatini inflation in models with an $R^2$ term

    I. Antoniadis🇫🇷 · A. Karam🇬🇷 · A. Lykkas🇬🇷 · K. Tamvakis🇬🇷

    The Starobinsky model, considered in the framework of the Palatini formalism, in contrast to the metric formulation, does not provide us with a model for inflation, due to the absence of a propagating scalar degree of freedom that can play the role of the inflaton. In the present article we study the Palatini formulation of the Starobinsky model coupled, in general nonminimally, to scalar fields and analyze its inflationary behavior. We consider scalars, minimally or nonminimally coupled to the Starobinsky model, such as a quadratic model, the induced gravity model or the standard Higgs-like inflation model and analyze the corresponding modifications favorable to inflation. In addition we examine the case of a classically scale-invariant model driven by the Coleman-Weinberg mechanism. In the slow-roll approximation, we analyze the inflationary predictions of these models and compare them to the latest constraints from the Planck collaboration. In all cases, we find that the effect of the $R^2$ term is to lower the value of the tensor-to-scalar ratio.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2018)·139 citations
12. 12*

    Observation of a time lag in solar modulation of cosmic rays in the heliosphere

    Miguel Orcinha🇵🇹 · Nicola Tomassetti🇮🇹 · Fernando Barão🇵🇹 · Bruna Bertucci🇮🇹

    The solar modulation effect of Galactic cosmic rays is a time-dependent phenomenon that is caused by the transport of these particles through the magnetized plasma of the heliosphere. Using a data-driven model of cosmic-ray transport in the heliosphere, in combination with a large collection of data, we report the evidence for a eight-month time lag between observations of solar activity and measurements of cosmic-ray fluxes in space. As we will discuss, this result enables us to forecast the cosmic ray flux at Earth well in advance by monitoring solar activity. We also compare our predictions with the new multi-channel measurements of cosmic rays operated by the AMS experiment in space.

    ↳ astro-ph.HEhep-phJ.Phys.Conf.Ser.(2019)·3 citations
13. 13*

    Evidence for charm-bottom tetraquarks and the mass dependence of heavy-light tetraquark states from lattice QCD

    Anthony Francis🇨🇭 · Renwick J. Hudspith🇨🇦 · Randy Lewis🇨🇦 · Kim Maltman🇨🇦

    We continue our study of heavy-light four-quark states and find evidence from lattice QCD for the existence of a strong-interaction-stable $I(J^P)=0(1^{+})$ $ud\bar{c}\bar{b}$ tetraquark with mass in the range of 15 to 61 MeV below $\bar{D}{B}^{\ast }$ threshold. Since this range includes the electromagnetic $\bar{D}B\gamma$ decay threshold, current uncertainties do not allow us to determine whether such a state would decay electromagnetically, or only weakly. We also perform a study at fixed pion mass, with NRQCD for the heavy quarks, simulating $q{q}^{\prime }{\bar{b}}^{\prime }\bar{b}$ and $q{q}^{\prime }{\bar{b}}^{\prime }{\bar{b}}^{\prime }$ tetraquarks with $q,q^{\prime }=ud$ or $\ell s$ and variable, unphysical $m_{b^{\prime }}$ in order to investigate the heavy mass-dependence of such tetraquark states. We find that the dependence of the binding energy follows a phenomenologically-expected form and that, though NRQCD breaks down before $m_{b^{\prime }}=m_c$ is reached, the results at higher $m_{b^{\prime }}$ clearly identify the $ud{\bar{b}}^{\prime }\bar{b}$ channel as the most likely to support a strong-interaction-stable tetraquark state at $m_{b^{\prime }}=m_c$. This observation serves to motivate the direct $ud\bar{c}\bar{b}$ simulation. Throughout we use dynamical $n_f=2+1$ ensembles with pion masses $m_{\pi }=$415, 299, and 164 MeV reaching down almost to the physical point, a relativistic heavy quark prescription for the charm quark, and NRQCD for the bottom quark(s).

    ↳ hep-lathep-phnucl-thPRD(2019)·140 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.