Fri·Aug 18, 2017Friday·August 18, 2017

1. 01*

   Implications of Heavy Quark-Diquark Symmetry for Excited Doubly Heavy Baryons and Tetraquarks

   Thomas Mehen (Duke U.)🇺🇸

   We give heavy quark-diquark symmetry predictions for doubly heavy baryons and tetraquarks in light of the recent discovery of the ${\Xi }_{cc}^{++}$ by LHCb. For five excited doubly charm baryons that are predicted to lie below the ${\Lambda }_{c}D$ threshold, we give predictions for their electromagnetic and strong decays using a previously developed chiral Lagrangian with heavy quark-diquark symmetry. Based on the mass of the ${\Xi }_{cc}^{++}$, the existence of a doubly heavy bottom $I=0$ tetraquark that is stable to the strong and electromagnetic decays has been predicted. If the mass of this state is below 10405 MeV, as predicted in some models, we argue using heavy quark-diquark symmetry that the $J^P=1^{+}$ $I=1$ doubly bottom tetraquark state will lie just below the open bottom threshold and likely be a narrow state as well. In this scenario, we compute strong decay width for this state using a new Lagrangian for tetraquarks which is related to the singly heavy baryon Lagrangian by heavy quark-diquark symmetry.

   hep-phPRD(2017)·71 citations
2. 02*

   Backgrounds in the search for Second Class Currents in $\tau$ decays

   Adolfo Guevara🇲🇽

   As constructed, the Standard Model does not include genuine Second Class Currents, however these can be induced through the breaking of isospin or charge conjugation. The experimental limits from B-Factories are getting closer to the predictions made for induced Second Class Currents through isospin breaking in the processes $\tau \to \pi {\eta }^{(\prime )}{\nu }_{\tau }$, therefore a more careful analysis of the background in these decays becomes necessary. In this work we analyze the $\tau \to \pi {\eta }^{(\prime )}\gamma {\nu }_{\tau }$ decays as background of the non-radiative process. We find that the radiative processes are very important background for the non-radiative ones whenever the photon escapes detection. Photons cannot be completely excluded since they need to be kept for the identification of the eta and eta' in the final state. However, we find that making appropriate cuts in the energy of the photon, this process can be disregarded as an important background.

   hep-phJ.Phys.Conf.Ser.(2017)·0 citations
3. 03*

   On Thermal Gravitational Contribution to Particle Production and Dark Matter

   Yong Tang🇯🇵 · Yue-Liang Wu🇨🇳

   We investigate the particle production from thermal gravitational annihilation in the very early universe, which is an important contribution for particles that might not be in thermal equilibrium or/and only have gravitational interaction, such as dark matter (DM). For particles with spin 0, 1/2 and 1 we calculate the relevant cross sections through gravitational annihilation and give the analytic formulas with full mass-dependent terms. We find that DM with mass between TeV and $10^{16}$GeV could have the relic abundance that fits the observation, with small dependence on its spin. We also discuss the effects of gravitational annihilation from inflatons. Interestingly, contributions from inflatons could be dominant and have the same power dependence on Hubble parameter of inflation as that from vacuum fluctuation. Also, fermion production from inflatons, in comparison to boson, is suppressed by its mass due to helicity selection.

   hep-phastro-ph.COgr-qcPLB(2017)·122 citations
4. 04*

   Spectroscopy and production of doubly charmed tetraquarks

   Tetsuo Hyodo🇯🇵 · Yan-Rui Liu🇨🇳 · Makoto Oka🇯🇵 · Shigehiro Yasui🇯🇵

   We discuss the production of the exotic doubly-charmed tetraquark mesons ${\mathrm{T}}_{\mathrm{c}\mathrm{c}}(\mathrm{c}\mathrm{c}\bar{\mathrm{u}}\bar{\mathrm{d}})$ from electron-positron collisions. ${\mathrm{T}}_{\mathrm{c}\mathrm{c}}(\mathrm{c}\mathrm{c}\bar{\mathrm{u}}\bar{\mathrm{d}})$ is a compact exotic hadron whose binding energy is provided by the diquark correlations. We evaluate the production cross section in the electron-positron collisions using the nonrelativistic QCD framework, and investigate the difference of the production cross section for different color configurations in two charm quarks (antitriplet and sextet), where the mixing of different configurations is suppressed in the heavy quark limit. The total cross section is estimated by modeling the nonperturbative fragmentation process of the charm quark pair into the tetraquark by the wavefunction of the tetraquark and the probability of picking up the light quarks. We find that the internal color configurations are distinguishable by the qualitative features of the differential cross sections which are independent of the nonperturbative matrix elements.

   hep-ph20 citations
5. 05*

   Determination of the ${\theta }_{23}$ octant in long baseline neutrino experiments within and beyond the standard model

   C.R. Das🇷🇺 · Jukka Maalampi🇫🇮 · João Pulido🇵🇹 · Sampsa Vihonen🇫🇮

   The recent data indicate that the neutrino mixing angle ${\theta }_{23}$ deviates from the maximal-mixing value of 45${}^{\circ }$, showing two nearly degenerate solutions, one in the lower octant (LO) (${\theta }_{23}<45^{\circ }$) and one in the higher octant (HO) (${\theta }_{23}>45^{\circ }$). We investigate, using numerical simulations, the prospects for determining the octant of ${\theta }_{23}$ in the future long baseline oscillation experiments. We present our results as contour plots on the (${\theta }_{23}-45^{\circ }$, $\delta$)--plane, where $\delta$ is the $CP$ phase, showing the true values of ${\theta }_{23}$ for which the octant can be experimentally determined at 3$\sigma$, 2$\sigma$ and 1$\sigma$ confidence level. In particular, we study the impact of the possible nonunitarity of neutrino mixing on the experimental determination of ${\theta }_{23}$ in those experiments.

   hep-phPRD(2018)·19 citations
6. 06*

   Open Issues in Neutrino Reactions

   E. A. Paschos🇩🇪

   Numerous investigations discuss neutrino properties from low to ultra high energies. This review discusses several topics that are investigated in present day experiments. The first section covers the detection of $\tau$-neutrinos of cosmic origin and describes the significance of the results. The second topic points out that the reported reduction of the antineutrino flux in reactor experiments may be created by short wavelength oscillations where the detector averages over several wavelengths and observes only an average reduction of the antineutrino flux. In many theories the propagating particles are Majoranas and have an anapole moment; they scatter on atomic electrons with a distinct signature in ${\bar{\nu }}_e+e^{-}\to {\bar{\nu }}_e+e^{-}$ scattering.

   hep-ph0 citations
7. 07*

   Beam normal spin asymmetry for the $ep\to e\Delta (1232)$ process

   Carl E. Carlson (William and Mary)🇺🇸 · Barbara Pasquini (University of Pavia)🇮🇹 · Vladyslav Pauk (Jefferson Laboratory)🇺🇸 · Marc Vanderhaeghen (Johannes Gutenberg University)🇩🇪

   We calculate the single spin asymmetry for the $ep\to e\Delta (1232)$ process, for an electron beam polarized normal to the scattering plane. Such single spin asymmetries vanish in the one-photon exchange approximation, and are directly proportional to the absorptive part of a two-photon exchange amplitude. As the intermediate state in such two-photon exchange process is on its mass shell, the asymmetry allows one to access for the first time the on-shell $\Delta \to \Delta$ as well as $N^{\ast }\to \Delta$ electromagnetic transitions. We present the general formalism to describe the $ep\to e\Delta$ beam normal spin asymmetry, and provide a numerical estimate of its value using the nucleon, $\Delta (1232)$, $S_{11}(1535)$, and $D_{13}(1520)$ intermediate states. We compare our results with the first data from the Qweak@JLab experiment and give predictions for the A4@MAMI experiment.

   hep-phnucl-thPRD(2017)·25 citations
8. 08*

   Kinetic mixing between a Higgs and a nearly degenerate Dark scalar: oscillations and displaced vertices

   Daniel Boyanovsky🇺🇸 · Junmou Chen🇺🇸

   Extensions beyond the Standard Model allow for a gauge singlet scalar to be kinetically coupled with the Higgs. We consider kinetic mixing between a Dark scalar gauge singlet \emph{nearly degenerate} with the Higgs, focusing on the \emph{dynamical} aspects of the mixing phenomena. The renormalization program is carried out by obtaining the one-loop effective action which yields an effective non-hermitian Hamiltonian to study the dynamics of mixing. The scalar Higgs becomes a coherent superposition of the mass eigenstates, thus kinetic mixing leads to oscillations and common decay channels in striking similarity with neutral meson mixing. Near degeneracy yields an \emph{enhancement} of the kinetic coupling. For small kinetic mixing we find that the mass eigenstates feature different lifetimes which result in a wide separation of time scales of evolution along with important coherence aspects from Dark scalar-Higgs interference. The wide separation of scales is manifest as displaced decay vertices which could potentially be a telltale experimental signal of kinetic mixing.

   hep-phhep-thPRD(2017)·8 citations
9. 09*

   Non-unitary lepton mixing in an inverse seesaw and its impact on the physics potential of long-baseline experiments

   Soumya C🇮🇳 · Rukmani Mohanta🇮🇳

   In this paper, we consider the low-energy scale inverse seesaw mechanism in which the observed neutrino mass and lepton mixing are explained by introducing right handed neutrinos and the gauge-singlet fermions with experimentally testable energy scale. Moreover, the presence of such new fermions leads to unitarity violation in lepton mixing due to significantly large mixing between active neutrinos and the heavy fermions. In addition to this, such large lepton mixing also gives rise to potentially large lepton flavor violation, which allows to constrain the non-unitarity parameters via lepton flavor violating decays ($l_i\to l_j\gamma$). We make use of these constraints on non-unitarity parameters and investigate their effects on the determination of current unknown oscillation parameters at long-baseline experiments. We find that non-unitarity parameters are sensitive to NO$\nu$A experiment. However, it is observed that NO$\nu$A experiment is not expected to improve the current knowledge of non-unitarity parameter ${\eta }_{21}$. We also find that the sensitivities to current unknowns are deteriorated significantly in presence of non-unitary lepton mixing and these sensitivities crucially depend upon the new CP-violating phase in the non-unitary mixing. Further, we find that the degeneracy resolution capability of NO$\nu$A experiment is reduced in the presence of non-unitarity parameters. However, the synergy between the currently running experiments T2K and NO$\nu$A can improve the parameter degeneracy resolution and hence there is enhancement in the sensitivities of unknowns.

   hep-ph5 citations
10. 10*

    Searching for Confining Hidden Valleys at the LHC(b)

    Aaron Pierce🇺🇸 · Bibhushan Shakya🇺🇸 · Yuhsin Tsai🇺🇸 · Yue Zhao🇺🇸

    We explore strategies for probing Hidden Valley scenarios exhibiting confinement. Such scenarios lead to a multiplicity of light hidden hadrons from showering processes. Their decays are typically soft and displaced, making them challenging to probe with traditional LHC searches. We show the low trigger thresholds and excellent track and vertex reconstruction at LHCb provide an ideal environment to search for such signals -- in both muonic and hadronic channels. We also explore the potential of ATLAS/CMS and discuss modifications to present searches that might make these experiments competitive with the LHCb reach. Our proposed searches can probe $Z^{\prime }$ models with dominant decays to dark sectors as well as exotic Higgs boson decays in Twin Higgs models.

    hep-phhep-exPRD(2018)·82 citations
11. 11*

    Gravitino and Polonyi production in supergravity

    Andrea Addazi🇨🇳 · Sergei V. Ketov🇯🇵 · Maxim Yu. Khlopov🇷🇺

    We study production of gravitino and Polonyi particles in the minimal Starobinsky-Polonyi $\mathcal{N}=1$ supergravity with inflaton belonging to a massive vector supermultiplet. Our model has only one free parameter given by the scale of spontaneous SUSY breaking triggered by Polonyi chiral superfield. The vector supermultiplet generically enters the action non-minimally, via an arbitrary real function. This functon is chosen to generate the inflaton scalar potential of the Starobinsky model. Our supergravity model can be reformulated as an abelian supersymmetric gauge theory with the vector gauge superfield coupled to two (Higgs and Polonyi) chiral superfields interacting with supergravity, where the $U(1)$ gauge symmetry is spontaneously broken. We find that Polonyi and gravitino particles are efficiently produced during inflation. After inflation, perturbative decay of inflaton also produces Polonyi particles that rapidly decay into gravitinos. As a result, a coherent picture of inflation and dark matter emerges, where the abundance of produced gravitinos after inflation fits the CMB constraints as a Super Heavy Dark Matter (SHDM) candidate. Our scenario avoids the notorous gravitino and Polonyi problems with the Big Bang Nucleosynthesis (BBN) and DM overproduction.

    hep-phastro-ph.HEgr-qchep-thEPJC(2018)·34 citations
12. 12*

    Electron tunneling times

    N. G. Kelkar🇨🇴

    Tunneling is one of the most bizarre phenomena in quantum mechanics. An attempt to understand it led to the next natural question of how long does a particle need to tunnel a barrier. The latter gave rise to several definitions such as the phase, dwell, Larmor and traversal times among others. A short review of the evolution of these time concepts, followed by an account of experiments involving field-induced tunnel ionization and electron tunneling in a solid state junction is presented here. Whereas the former experiments use sophisticated techniques involving femtosecond laser pulses and determine the tunneling time by mapping the angle of rotation of the field vector to time, like the hands of a watch, the latter provides a simpler method through the measurement of current-voltage characteristics of the junction.

    ↳ quant-phcond-mat.otherhep-phphysics.atom-phActa Phys.Polon.B(2017)·3 citations
13. 13*

    Ghost-free vector superfield actions in supersymmetric higher-derivative theories

    Toshiaki Fujimori🇯🇵 · Muneto Nitta🇯🇵 · Keisuke Ohashi🇯🇵 · Yusuke Yamada🇺🇸 · Ryo Yokokura🇯🇵

    We systematically construct ghost-free higher-derivative actions of Abelian vector supermultiplets in four-dimensional $\mathcal{N}=1$ global supersymmetric theories. After giving a simple example which illustrates that a naive introduction of a higher-derivative term gives rise to a ghost, we discuss possible building blocks for a ghost-free action and explicitly show that their bosonic parts have no ghost mode and the auxiliary field $\mathbf{D}$ does not propagate. Higher-derivative terms yield higher powers of the auxiliary field $\mathbf{D}$ in the actions, and the D-term equations of motion consequently admit multiple solutions in general. We confirm that the well-known supersymmetric Dirac-Born-Infeld action falls into this class. We further give another example in which the standard quadratic kinetic term (Maxwell term) is corrected by a quartic term of the field strength. We also discuss possible couplings to matter fields and a deformed D-term potential.

    ↳ hep-thhep-phJHEP(2017)·16 citations
14. 14*

    Improved Parton Distribution Functions at Physical Pion Mass

    Huey-Wen Lin🇺🇸 · Jiunn-Wei Chen🇹🇼 · Tomomi Ishikawa🇨🇳 · Jian-Hui Zhang🇩🇪

    We present the first lattice results on isovector unpolarized and longitudinally polarized parton distribution functions (PDFs) at physical pion mass. The PDFs are obtained using the large-momentum effective field theory (LaMET) framework where the full Bjorken-$x$ dependence of finite-momentum PDFs, called "quasi-PDFs", can be calculated on the lattice. The quasi-PDF nucleon matrix elements are renormalized nonperturbatively in RI/MOM-scheme. However, the recent renormalized quasi-PDFs suffer from unphysical oscillations that alter the shape of the true distribution as a function of Bjorken-$x$. In this paper, we propose two possible solutions to overcome this problem, and demonstrate the efficacy of the methods on the 2+1+1-flavor lattice data at physical pion mass with lattice spacing 0.09~fm and volume $(5.76\text{mbox}fm{)}^3$.

    ↳ hep-lathep-phPRD(2018)·118 citations
15. 15*

    Measurement of the Lorentz-FitzGerald Body Contraction

    Johann Rafelski🇺🇸

    A complete foundational discussion of acceleration in context of Special Relativity is presented. Acceleration allows the measurement of a Lorentz-FitzGerald body contraction created. It is argued that in the back scattering of a probing laser beam from a relativistic flying electron cloud mirror generated by an ultra-intense laser pulse, a first measurement of a Lorentz-FitzGerald body contraction is feasible.

    ↳ physics.hist-phhep-phnucl-thphysics.opticsEPJA(2018)·1 citation
16. 16*

    Testing Lorentz Symmetry using High Energy Astrophysics Observations

    Floyd W. Stecker🇺🇸

    We discuss some of the tests of Lorentz symmetry made possible by astrophysical observations of ultrahigh energy cosmic rays, gamma-rays, and neutrinos. These are among the most sensitive tests of Lorentz symmetry violation because they are the highest energy phenomena known to man.

    ↳ astro-ph.HEgr-qchep-phSymmetry(2017)·18 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.