Fri·Oct 19, 2018Friday·October 19, 2018

1. 01*

   Interpreting the Electron EDM Constraint

   Cari Cesarotti🇺🇸 · Qianshu Lu🇺🇸 · Yuichiro Nakai🇺🇸 · Aditya Parikh🇺🇸 · Matthew Reece🇺🇸

   The ACME collaboration has recently announced a new constraint on the electron EDM, $|d_e|<1.1\times 10^{-29}e\mathrm{cm}$, from measurements of the ThO molecule. This is a powerful constraint on CP-violating new physics: even new physics generating the EDM at two loops is constrained at the multi-TeV scale. We interpret the bound in the context of different scenarios for new physics: a general order-of-magnitude analysis for both the electron EDM and the CP-odd electron-nucleon coupling; 1-loop SUSY, probing sleptons above 10 TeV; 2-loop SUSY, probing multi-TeV charginos or stops; and finally, new physics that generates the EDM via the charm quark or top quark Yukawa couplings. In the last scenario, new physics generates a "QULE operator" $(q_f{\bar{\sigma }}^{\mu \nu }{\bar{u}}_f)\cdot (\ell {\bar{\sigma }}_{\mu \nu }\bar{e})$, which in turn generates the EDM through RG evolution. If the QULE operator is generated at tree level, this corresponds to a previously studied leptoquark model. For the first time, we also classify scenarios in which the QULE operator is generated at one loop through a box diagram, which include SUSY and leptoquark models. The electron EDM bound is the leading constraint on a wide variety of theories of CP-violating new physics interacting with the Higgs boson or the top quark. We argue that any future nonzero measurement of an electron EDM will provide a strong motivation for constructing new colliders at the highest feasible energies.

   hep-phhep-exJHEP(2019)·117 citations
2. 02*

   Common explanation of the behavior of some $e^{+}{e}^{-}$ annihilation processes around $\sqrt{s}$ = 1.9 GeV

   Peter Lichard🇨🇿

   We show that the behavior of the excitation curves of some $e^{+}{e}^{-}$ annihilation processes close to the nucleon-antinucleon threshold can be explained either by the $\rho (1900)$ resonance itself or by its interference with other resonances. Besides the six-pion annihilation and the $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$ and $e^{+}{e}^{-}\to \Phi {\pi }^0$ processes, we also analyze the final states $\eta {\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}{\pi }^0$, and $K^{+}{K}^{-}{\pi }^0{\pi }^0$, the behavior of which around 1.6 GeV has not yet attracted attention. Analysis of the data on the $e^{+}{e}^{-}\to p\bar{p}$ and $e^{+}{e}^{-}\to n\bar{n}$ reactions clearly shows that the $\rho (1900)$ resides above the $n\bar{n}$ threshold.

   hep-phhep-exPRD(2018)·8 citations
3. 03*

   Tetraquarks, Pentaquarks and Dibaryons in the large $N$ QCD

   Luciano Maiani🇮🇹 · Veronica Riquer🇨🇳 · Wei Wang🇨🇳

   We study the multiquark hadrons in large $N$ QCD under the 't-Hooft limit, extending Witten's picture of the baryons. We explore the decay widths of tetraquarks, pentaquarks and dibaryons. Based on the decay behaviors, we point out in the $N\to \infty$ limit decay widths of tetraquarks stay constant, while those of pentaquarks and dibaryons above certain thresholds can diverge. In the large $N$ limit, we find that the ground states of the three spectroscopic series are stable or narrow and that the excited states of pentaquarks and dibaryons above the indicated thresholds are not observables. We compare our results with those obtained in a different large $N$ generalization of tetraquarks.

   hep-phhep-exEPJC(2018)·13 citations
4. 04*

   Study on the strong decays of $\varphi (2170)$ and a grand expectation for the future charm-tau factory

   Hong-Wei Ke🇨🇳 · Xue-Qian Li🇨🇳

   The present data imply that $\varphi (2170)$ may not be an excited state of $\varphi$, but is a four quark state with $ss\bar{s}\bar{s}$ constituents. Furthermore, there are no two mesons of $s\bar{s}$ available to form a molecule which fits the mass spectrum of $\varphi (2170)$, thus we suggest it should be an $ss\bar{s}\bar{s}$ tetraquark state. In this scenario, we estimate its decay rates through the fall-apart mechanism. Our theoretical estimates indicate that its main decay modes should be $\varphi (2170)$ into $\varphi f_0(980)$, $h_1\eta$, $h_1{\eta }^{\prime }$, $K_1(1270)K$ and $K_1(1400)K$. Under this hypothesis the modes $\varphi (2170)\to K^{\ast }(890{)}^0{\bar{K}}^{\ast }(890{)}^0$, $K^{+}{K}^{-}$ and $K_L^0{K}_S^0$ should be relatively suppressed. Since the width of $h_1$ is rather large, at present it is hard to gain precise data on $BR(\varphi (2170)\to h_1\eta )$ and $BR(\varphi (2170)\to h_1{\eta }^{\prime })$ whose measurements may be crucial for drawing a definite conclusion about the inner assignment of $\varphi (2170)$. We lay our expectation to the proposed charm-tau factory which will have much larger luminosity and better capacities.

   hep-phhep-exPRD(2019)·46 citations
5. 05*

   Impact of RGE-induced $\mu -\tau$ Reflection Symmetry Breaking on the Effective Majorana Neutrino Mass in $0\nu \beta \beta$ Decay

   Newton Nath🇨🇳

   We make an attempt to study the impact of renormalization-group equations (RGE) induced $\mu -\tau$ reflection symmetry breaking on the effective Majorana neutrino mass $|⟨m{⟩}_{ee}|$ in neutrinoless double beta ($0\nu \beta \beta$) decay. At present, the $0\nu \beta \beta$ decay serves as a unique process to address the Majorana nature of massive neutrinos. The rate of such decay process depends on $|⟨m{⟩}_{ee}|$. On the other hand, $\mu -\tau$ reflection symmetry predicts ${\theta }_{23}=45^{\circ }$ and $\delta =\pm 90^{\circ }$ together with trivial values of the Majorana CP-phases ($\rho ,\sigma$). Moreover, based on the recent global best-fit values which prefer higher octant of ${\theta }_{23}$ and third quadrant of $\delta$, it is hard to believe the exactness of such symmetry. Also, any non-trivial values of $\rho ,\sigma$ may have some significant impact on $|⟨m{⟩}_{ee}|$. In this context, we study the spontaneous breaking of the symmetry via one-loop RGE-running from a superhigh energy scale (${\Lambda }_{\mu \tau }$) down to the electroweak scale (${\Lambda }_{\mathrm{EW}}$). Given the broken symmetry, we perform some systematic analysis for $|⟨m{⟩}_{ee}|$ in substantial detail. Further, we also extend this analysis for other lepton-number violating effective Majorana masses.

   hep-phPRD(2019)·18 citations
6. 06*

   Bound state properties from the Functional Renormalisation Group

   Reinhard Alkofer🇦🇹 · Axel Maas🇦🇹 · Walid Ahmed Mian🇦🇹 · Mario Mitter🇦🇹 · Jordi París-López🇦🇹 · Jan M. Pawlowski🇩🇪 · Nicolas Wink🇩🇪

   We discuss an approach for accessing bound state properties, like mass and decay width, of a theory within the functional renormalisation group approach. An important cornerstone is the dynamical hadronization technique for resonant interaction channels. The general framework is exemplified and put to work within the two-flavour quark-meson model. This model provides a low-energy description of the dynamics of two-flavour QCD with quark and hadronic degrees of freedom. We compare explicitly the respective results for correlation functions and observables with first principle QCD results in a quantitative manner. This allows us to estimate the validity range of low energy effective models. We also present first results for pole masses and decay widths. Next steps involving real-time formulations of the functional renormalisation group are discussed.

   hep-phPRD(2019)·57 citations
7. 07*

   On the Existence of $N^{\ast }(890)$ Resonance in $S_{11}$ Channel of $\pi N$ Scatterings

   Yu-Fei Wang🇨🇳 · De-Liang Yao🇪🇸 · Han-Qing Zheng🇨🇳

   Low-energy partial-wave $\pi N$ scattering data is reexamined with the help of the production representation of partial-wave $S$ matrix, where branch cuts and poles are thoroughly under consideration. The left-hand cut contribution to the phase shift is determined, with controlled systematic error estimates, by using the results of $\mathcal{O}(p^3)$ chiral perturbative amplitudes obtained in the extended-on-mass-shell scheme. In $S_{11}$ and $P_{11}$ channels, severe discrepancies are observed between the phase shift data and the sum of all known contributions. Statistically satisfactory fits to the data can only be achieved by adding extra poles in the two channels. We find that a $S_{11}$ resonance pole locates at $\sqrt{z_r}=(0.895\pm 0.081)-(0.164\pm 0.023)i$ GeV, on the complex $s$-plane. On the other hand, a $P_{11}$ virtual pole, as an accompanying partner of the nucleon bound-state pole, locates at $\sqrt{z_v}=(0.966\pm 0.018)$ GeV, slightly above the nucleon pole on the real axis below threshold. Physical origin of the two newly established poles is explored to the best of our knowledge. It is emphasized that the $\mathcal{O}(p^3)$ calculation greatly improves the fit quality comparing with the previous $\mathcal{O}(p^2)$ one.

   hep-phnucl-thFront.Phys.(Beijing)(2019)·6 citations
8. 08*

   Pileup mitigation at the Large Hadron Collider with Graph Neural Networks

   Jesus Arjona Martinez🇬🇧 · Olmo Cerri🇺🇸 · Maurizio Pierini🇨🇭 · Maria Spiropulu🇺🇸 · Jean-Roch Vlimant🇺🇸

   At the Large Hadron Collider, the high transverse-momentum events studied by experimental collaborations occur in coincidence with parasitic low transverse-momentum collisions, usually referred to as pileup. Pileup mitigation is a key ingredient of the online and offline event reconstruction as pileup affects the reconstruction accuracy of many physics observables. We present a classifier based on Graph Neural Networks, trained to retain particles coming from high-transverse-momentum collisions, while rejecting those coming from pileup collisions. This model is designed as a refinement of the PUPPI algorithm, employed in many LHC data analyses since 2015. Thanks to an extended basis of input information and the learning capabilities of the considered network architecture, we show an improvement in pileup-rejection performances with respect to state-of-the-art solutions.

   hep-phcs.LGhep-exEur.Phys.J.Plus(2019)·101 citations
9. 09*

   Testing $WW\gamma$ vertex in radiative muon decay

   Anirban Karan🇮🇳 · Rusa Mandal🇪🇸 · Rahul Sinha🇮🇳

   Large numbers of muons will be produced at facilities developed to probe lepton flavor violating process $\mu \to e\gamma$. We show that by constructing a suitable asymmetry, radiative muon decay $\mu \to e\gamma {\nu }_{\mu }{\bar{\nu }}_e$ can also be used to test the $WW\gamma$ vertex at such facilities. The process has two missing neutrinos in the final state and on integrating their momenta, the partial differential decay rate shows no radiation-amplitude-zero. We establish, however, that an easily separable part of the normalized differential decay rate, odd under the exchange of photon and electron energies, does have a zero in the case of standard model (SM). This "new type of zero" has hitherto not been studied in literature. A suitably constructed asymmetry using this fact, enables a sensitive probe for the $WW\gamma$ vertex beyond the SM. With a simplistic analysis, we find that the $C$ and $P$ conserving dimension four $WW\gamma$ vertex can be probed at $\mathcal{O}(10^{-2})$ with satisfactory significance level.

   hep-phhep-exPRD(2019)·0 citations
10. 10*

    $J/\psi$-meson production within improved color evaporation model with the $k_T$-factorization approach for $c\bar{c}$ production

    Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱 · Anna Cisek🇵🇱

    We use a new approach to color evaporation model (CEM) for quarkonium production. The production of $c\bar{c}$ pairs is performed within $k_T$-factorization approach using different unintegrated gluon distribution functions (UGDF) from the literature. We include all recent improvements to color evaporation model. We cannot describe simultaneously mid and forward rapidity data measured at the LHC when using the KMR UGDF with the same normalization parameter. Furthermore we get somewhat too hard distribution in $J/\psi$ transverse momentum. Correcting the standard KMR distributions for saturation effects at small values of $x$ improves $J/\psi$ rapidity distributions, while taking correction for emissions hidden in the KMR UGDF in the evaluation of $x$ values improves a bit $J/\psi$ transverse momentum distributions. The modifications improve also description of the LHCb $D$-meson data.

    hep-phPRD(2019)·24 citations
11. 11*

    Confinement potentials for the study of heavy mesons

    Alfredo Vega🇨🇱 · Francisca Rojas🇨🇱

    We consider a Coulomb potential plus a confinement potential $A{r}^{\nu }$ and we study which of the two terms is dominant in the description of quarkonia. We find that in general the term of confinement is dominant, which allows us to understand why such potentials, like Martin's potential, are successful in describing of heavy mesons.

    hep-ph2 citations
12. 12*

    Pion-to-vacuum vector and axial vector amplitudes and weak decays of pions in a magnetic field

    M. Coppola🇦🇷 · D. Gomez Dumm🇦🇷 · S. Noguera🇪🇸 · N. N. Scoccola🇦🇷

    We propose a model-independent parametrization for the one-pion-to-vacuum matrix elements of the vector and axial vector hadronic currents in the presence of an external uniform magnetic field. It is shown that, in general, these hadronic matrix elements can be written in terms of several gauge covariant Lorentz structures and form factors. Within this framework we obtain a general expression for the weak decay ${\pi }^{-}\to l{\bar{\nu }}_l$ and discuss the corresponding limits of strong and weak external magnetic fields.

    hep-phPRD(2019)·23 citations
13. 13*

    flavio: a Python package for flavour and precision phenomenology in the Standard Model and beyond

    David M. Straub🇩🇪

    flavio is an open source tool for phenomenological analyses in flavour physics and other precision observables in the Standard Model and beyond. It consists of a library to compute predictions for a plethora of observables in quark and lepton flavour physics and electroweak precision tests, a database of experimental measurements of these observables, a statistics package that allows to construct Bayesian and frequentist likelihoods, and of convenient plotting and visualization routines. New physics effects are parameterised as Wilson coefficients of dimension-six operators in the weak effective theory below the electroweak scale or the Standard Model EFT above it. At present, observables implemented include numerous rare $B$ decays (including angular observables of exclusive decays, lepton flavour and lepton universality violating $B$ decays), meson-antimeson mixing observables in the $B_{d,s}$, $K$, and $D$ systems, tree-level semi-leptonic $B$, $K$, and $D$ decays (including possible lepton universality violation), rare $K$ decays, lepton flavour violating $\tau$ and $\mu$ decays, $Z$ pole electroweak precision observables, the neutron electric dipole moment, and anomalous magnetic moments of leptons. Not only central values but also theory uncertainties of all observables can be computed. Input parameters and their uncertainties can be easily modified by the user. Written in Python, the code does not require compilation and can be run in an interactive session. This document gives an overview of the features as of version 1.0 but does not represent a manual. The full documentation of the code can be found in its web site.

    hep-phhep-ex391 citations
14. 14*

    Probing pseudo Nambu-Goldstone boson dark matter at loop level

    Koji Ishiwata🇯🇵 · Takashi Toma🇩🇪

    In the standard model extended by a single complex scalar boson with a softly broken global U(1) symmetry, a pseudo Nambu-Goldstone boson becomes a candidate for dark matter. In this paper, we discuss the direct detection of the pseudo Nambu-Goldstone boson dark matter. Since the tree-level amplitude for dark matter-nucleon scattering vanishes, higher order quantum corrections for the amplitude should be taken into account. We perform the calculation at the next-to-leading order in QCD in a systematic manner.

    hep-phJHEP(2018)·76 citations
15. 15*

    $Z_c(4100)$ and $Z_c(4200)$ as hadrocharmonium

    M.B. Voloshin🇺🇸

    It is suggested that the recently reported charged charmoniumlike resonance $Z_c(4100)$ and the previously observed $Z_c(4200)$ are two states of hadrocharmonium, related by the charm quark spin symmetry in the same way as the lowest charmonium states ${\eta }_c$ and $J/\psi$. Namely, the $Z_c(4100)$ is (dominantly) the ${\eta }_c$ embedded in an light-quark excitation with quantum numbers of a pion, while the $Z_c(4200)$ is a similar four quark state containing $J/\psi$ instead of ${\eta }_c$. It is argued that this picture suggests certain relations between the properties of the two exotic resonances and a distinctive pattern of their decays that can be tested experimentally. It is also pointed out that due to the presence of a spatially compact $c\bar{c}$ charmonium the discussed exotic $Z_c$ states may be produced as resonances in the $s$ channel in $\bar{p}p$ annihilation.

    hep-phhep-exPRD(2018)·25 citations
16. 16*

    Baryogenesis from neutron-dark matter oscillations

    Torsten Bringmann🇳🇴 · James M. Cline🇨🇦 · Jonathan M. Cornell🇨🇦

    It was recently suggested that dark matter consists of ~GeV particles that carry baryon number and mix with the neutron. We demonstrate that this could allow for resonant dark matter-neutron oscillations in the early universe, at finite temperature, leading to low-scale baryogenesis starting from a primordial dark matter asymmetry. In this scenario, the asymmetry transfer happens around 30 MeV, just before big bang nucleosynthesis. We illustrate the idea using a model with a dark U(1)' gauge interaction, which has recently been suggested as a way of addressing the neutron lifetime anomaly. The asymmetric dark matter component of this model is both strongly self-interacting and leads to a suppression of matter density perturbations at small scales, allowing to mitigate the small-scale problems of cold dark matter cosmology. Future CMB experiments will be able to consistently probe, or firmly exclude, this scenario.

    hep-phastro-ph.COPRD(2019)·32 citations
17. 17*

    Large violation of the flavour SU(3) symmetry in $\eta$MAID2018 isobar model

    V. A. Kuznetsov🇷🇺 · M.V. Polyakov🇷🇺

    We demonstrate that the explanation of the neutron anomaly around $W\sim 1685$MeV in $\gamma N\to \eta N$ reactions provided by the $\eta$MAID2018 isobar model is based on large violation of the flavour SU(3) symmetry in hadron interactions. This is yet another example of how conventional explanation (without invoking exotic narrow nucleon resonance) of the neutron anomaly metamorphoses into unconventional physics picture of hadron interactions. A possibility to mend the flavour SU(3) symmetry for some of resonances in $\eta$MAID model is discussed.

    ↳ nucl-thhep-phnucl-ex1 citation
18. 18*

    Signature of a Cosmic String Wake at $z=3$

    Disrael Camargo Neves da Cunha🇨🇦

    In this paper, we describe the results of N-body simulation runs, which include a cosmic string wake of tension $G\mu =4\times 10^{-8}$ on top of the usual $\Lambda CDM$ fluctuations. To obtain a higher resolution of the wake in the simulations compared to previous work, we insert the effects of the string wake at a lower redshift and perform the simulations in a smaller volume. A curvelet analysis of the wake and no-wake maps is applied, indicating that the presence of a wake can be extracted at a three-sigma confidence level from maps of the two-dimensional dark matter projection down to a redshift of $z=3$.

    ↳ astro-ph.COhep-phJCAP(2020)·5 citations
19. 19*

    Most general cubic-order Horndeski Lagrangian allowing for scaling solutions and the application to dark energy

    Noemi Frusciante🇵🇹 · Ryotaro Kase🇯🇵 · Nelson J. Nunes🇵🇹 · Shinji Tsujikawa🇯🇵

    In cubic-order Horndeski theories where a scalar field $\varphi$ is coupled to nonrelativistic matter with a field-dependent coupling $Q(\varphi )$, we derive the most general Lagrangian having scaling solutions on the isotropic and homogenous cosmological background. For constant $Q$ including the case of vanishing coupling, the corresponding Lagrangian reduces to the form $L=X{g}_2(Y)-g_3(Y)\square \varphi$, where $X=-{\partial }_{\mu }\varphi {\partial }^{\mu }\varphi /2$ and $g_2,g_3$ are arbitrary functions of $Y=X{e}^{\lambda \varphi }$ with constant $\lambda$. We obtain the fixed points of the scaling Lagrangian for constant $Q$ and show that the $\varphi$-matter-dominated-epoch ($\varphi$MDE) is present for the cubic coupling $g_3(Y)$ containing inverse power-law functions of $Y$. The stability analysis around the fixed points indicates that the $\varphi$MDE can be followed by a stable critical point responsible for the cosmic acceleration. We propose a concrete dark energy model allowing for such a cosmological sequence and show that the ghost and Laplacian instabilities can be avoided even in the presence of the cubic coupling.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·20 citations
20. 20*

    Parameter discordance in Planck CMB and low-redshift measurements: projection in the primordial power spectrum

    Dhiraj Kumar Hazra🇫🇷 · Arman Shafieloo🇰🇷 · Tarun Souradeep

    We discuss the discordance between the estimated values of the cosmological parameters from Planck assuming the concordance $\Lambda$CDM model and low-redshift measurements. In particular, we consider the Hubble constant mismatch between Planck temperature constraint for the $\Lambda$CDM model and the Riess et. al. local measurements as well as the discordance between the estimated value of $S_8$ from Planck and some weak lensing surveys such as Kilo Degree Survey (KiDS-450) and Dark Energy Survey (DES) observations. The discordance can come from a wide range of non-standard cosmological or astrophysical processes as well as from some particular systematics of the observations. In this paper, without considering any particular astrophysical process or extension to the standard model at the background level, we seek solely to project the effect of these differences in the values of the key cosmological parameters on to the shape of the primordial power spectrum (PPS). In order to realise this goal, we uncover the shape of the PPS by implementing the Modified Richardson-Lucy algorithm (MRL) that fits the Planck temperature data as acceptably as the case of the standard model of cosmology, but with a Hubble constant consistent with local measurements as well as improving the consistency between the derived $S_8$ and ${\sigma }_8$ parameters with estimations of the weak lensing surveys.

    ↳ astro-ph.COgr-qchep-phJCAP(2019)·38 citations
21. 21*

    Non-thermal fixed points: Universal dynamics far from equilibrium

    Christian-Marcel Schmied🇩🇪 · Aleksandr N. Mikheev🇩🇪 · Thomas Gasenzer🇩🇪

    In this article we give an overview of the concept of universal dynamics near non-thermal fixed points in isolated quantum many-body systems. We outline a non-perturbative kinetic theory derived within a Schwinger-Keldysh closed-time path-integral approach, as well as a low-energy effective field theory which enable us to predict the universal scaling exponents characterizing the time evolution at the fixed point. We discuss the role of wave-turbulent transport in the context of such fixed points and discuss universal scaling evolution of systems bearing ensembles of (quasi) topological defects. This is rounded off by the recently introduced concept of prescaling as a generic feature of the evolution towards a non-thermal fixed point.

    ↳ cond-mat.quant-gascond-mat.stat-mechhep-phInt.J.Mod.Phys.A(2019)·62 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.