Fri·Mar 27, 2020Friday·March 27, 2020

1. 01*

   Novel angular dependence in Drell-Yan lepton production via dimension-8 operators

   Simone Alioli🇮🇹 · Radja Boughezal🇺🇸 · Emanuele Mereghetti🇺🇸 · Frank Petriello🇺🇸

   We study the effects of dimension-8 operators on Drell-Yan production of lepton pairs at the Large Hadron Collider (LHC). We identify a class of operators that leads to novel angular dependence not accounted for in current analyses. The observation of such effects would be a smoking-gun signature of new physics appearing at the dimension-8 level. We propose an extension of the currently used angular basis and show that these effects should be observable in future LHC analyses for realistic values of the associated dimension-8 Wilson coefficients.

   hep-phhep-exPLB(2020)·86 citations
2. 02*

   Nucleon elastic form factors at accessible large spacelike momenta

   Zhu-Fang Cui🇨🇳 · Chen Chen🇩🇪 · Daniele Binosi🇮🇹 · Feliciano De Soto🇪🇸 · Craig D. Roberts🇨🇳 · Jose Rodriguez-Quintero🇪🇸 · Sebastian M. Schmidt🇩🇪 · Jorge Segovia🇪🇸

   A Poincaré-covariant quark+diquark Faddeev equation is used to compute nucleon elastic form factors on $0\le Q^2\le 18m_N^2$ ($m_N$ is the nucleon mass) and elucidate their role as probes of emergent hadronic mass in the Standard Model. The calculations expose features of the form factors that can be tested in new generation experiments at existing facilities, e.g. a zero in $G_E^p/G_M^p$; a maximum in $G_E^n/G_M^n$; and a zero in the proton's $d$-quark Dirac form factor, $F_1^d$. Additionally, examination of the associated light-front-transverse number and anomalous magnetisation densities reveals, inter alia: a marked excess of valence $u$-quarks in the neighbourhood of the proton's centre of transverse momentum; and that the valence $d$-quark is markedly more active magnetically than either of the valence $u$-quarks. The calculations and analysis also reveal other aspects of nucleon structure that could be tested with a high-luminosity accelerator capable of delivering higher beam energies than are currently available.

   hep-phhep-latnucl-exnucl-thPRD(2020)·52 citations
3. 03*

   Diagonal reflection symmetries and universal four-zero texture

   Masaki J. S. Yang🇯🇵

   In this paper, we consider a set of new symmetries in the SM, {\it diagonal reflection} symmetries $R{m}_{u,\nu }^{\ast }R=m_{u,\nu },m_{d,e}^{\ast }=m_{d,e}$ with $R=$ diag $(-1,1,1)$. These generalized $CP$ symmetries predict the Majorana phases to be ${\alpha }_{2,3}/2\sim 0$ or $\pi /2$. A realization of reflection symmetries suggests a broken chiral $U(1{)}_{\mathrm{PQ}}$ symmetry and a flavored axion. The axion scale is suggested to be $⟨{\theta }_{u,d}⟩\sim {\Lambda }_{\mathrm{GUT}}\sqrt{m_{u,d}{m}_{c,s}}/v\sim 10^{12}$[GeV]. By combining the symmetries with the four-zero texture, the mass eigenvalues and mixing matrices of quarks and leptons are reproduced well. This scheme predicts the normal hierarchy, the Dirac phase ${\delta }_{CP}\simeq 203^{\circ },$ and $|m_1|\simeq 2.5$ or $6.2$[meV]. In this scheme, the type-I seesaw mechanism and a given neutrino Yukawa matrix $Y_{\nu }$ completely determine the structure of right-handed neutrino mass $M_R$. An $u-\nu$ unification predicts mass eigenvalues to be $(M_{R1},M_{R2},M_{R3})=(O(10^5),O(10^9),O(10^{14}))$[GeV].

   hep-phCPC(2021)·16 citations
4. 04*

   Production of hidden-charm and hidden-bottom pentaquark states in electron-proton collisions

   Ya-Ping Xie🇨🇳 · Xu Cao🇨🇳 · Yu-Tie Liang🇨🇳 · Xurong Chen🇨🇳

   Electro-production of several pentaquark states is investigated in this paper. eSTARlight package is adapted to study the electro-production of $J/\psi$ and ${\rm Y}(1S)$ via pentaquark $P_c$ and $P_b$ resonance channels in $ep\to eeJ/\psi p$ and $ep\to e{\rm Y}(1S)p$ scattering processes at proposed electron-ion colliders (EICs). The results in this paper are compared to the non-resonance $t$-channels, which is described in pomeron exchange model in our studies. Some pseudo-rapidity distributions rapidity distributions of $J/\psi$ and ${\rm Y}(1S)$ are presented for proposed EICs including EicC and EIC-US. It is found that EicC is a good platform to identify $P_b$ states in the future.

   hep-phCPC(2021)·18 citations
5. 05*

   Investigating the Production of Leptoquarks by Means of Zeros of Amplitude at Photon Electron Collider

   Priyotosh Bandyopadhyay🇮🇳 · Saunak Dutta🇮🇳 · Anirban Karan🇮🇳

   Leptoquarks are one of the possible candidates for explaining various anomalies in flavour physics. Nonetheless, their existence is yet to be confirmed from experimental side. In this paper we have shown how zeros of single photon tree-level amplitude can be used to extract information about leptoquarks in case of $e$-$\gamma$ colliders. Small number of standard model backgrounds keep the signal clean in this kind of colliders. Unlike other colliders, the zeros of single photon amplitude here depend on $\sqrt{s}$ as well as the mass of leptoquark along with its electric charge. We perform a PYTHIA based simulation for reconstructing the leptoquark from its decay products of first generation and estimating the background with luminosity of 100 fb${}^{-1}$. Our analysis is done for all the leptoquarks that can be seen at $e$-$\gamma$ collider with three different masses (70 GeV, 650 GeV and 1 TeV) and three different centre of momentum energy (200 GeV, 2 TeV and 3 TeV). The effects of non-monochromatic photons on the zeros of amplitude under laser backscattering and equivalent photon approximation have also been addressed.

   hep-phEPJC(2020)·16 citations
6. 06*

   Neural Network-based Top Tagger with Two-Point Energy Correlations and Geometry of Soft Emissions

   Amit Chakraborty🇮🇳 · Sung Hak Lim🇯🇵 · Mihoko M. Nojiri🇯🇵 · Michihisa Takeuchi🇯🇵

   Deep neural networks trained on jet images have been successful in classifying different kinds of jets. In this paper, we identify the crucial physics features that could reproduce the classification performance of the convolutional neural network in the top jet vs. QCD jet classification. We design a neural network that considers two types of substructural features: two-point energy correlations, and the IRC unsafe counting variables of a morphological analysis of jet images. The new set of IRC unsafe variables can be described by Minkowski functionals from integral geometry. To integrate these features into a single framework, we reintroduce two-point energy correlations in terms of a graph neural network and provide the other features to the network afterward. The network shows a comparable classification performance to the convolutional neural network. Since both networks are using IRC unsafe features at some level, the results based on simulations are often dependent on the event generator choice. We compare the classification results of Pythia 8 and Herwig 7, and a simple reweighting on the distribution of IRC unsafe features reduces the difference between the results from the two simulations.

   hep-phhep-exJHEP(2020)·48 citations
7. 07*

   Distinguishing Inert Higgs Doublet and Inert Triplet Scenarios

   Shilpa Jangid🇮🇳 · Priyotosh Bandyopadhyay🇮🇳

   In this article we consider a comparative study between Type-I 2HDM and $Y=0$, $SU(2)$ triplet extensions having one $Z_2$-odd doublet and triplet that render the desired dark matter(DM). For the inert doublet model (IDM) either a neutral scalar or pseudoscalar can be the DM, whereas for inert triplet model (ITM) it is a CP-even scalar. The bounds from perturbativity and vacuum stability are studied for both the scenarios by calculating the two-loop beta functions. While the quartic couplings are restricted to $0.1-0.2$ for a Planck scale perturbativity for IDM, these are much relaxed ($0.8$ ) for ITM. The RG-improved potentials by Coleman-Weinberg show the regions of stability, meta-stability and instability of the electroweak vacuum. The constraints coming from DM relic, the direct and indirect experiments like XENON1T, LUX and H.E.S.S., Fermi-LAT allow the DM mass $\gtrsim 700,1176$ GeV for IDM, ITM respectively. Though mass-splitting among $Z_2$-odd particles in IDM is a possibility for ITM we have to rely on loop-corrections. The phenomenological signatures at the LHC show that the mono-lepton plus missing energy with prompt and displaced decays in the case of IDM and ITM can distinguish such scenarios at the LHC along with other complementary modes.

   hep-phEPJC(2020)·31 citations
8. 08*

   Connecting between inflation and dark matter in models with gauged $Z_3$ symmetry

   Soo-Min Choi🇰🇷 · Jinsu Kim🇩🇪 · Hyun Min Lee🇰🇷 · Bin Zhu🇨🇳

   We investigate the possibility of unifying the inflation and dark matter physics in the minimal model for a complex scalar dark matter with gauged $Z_3$ symmetry. The dark local $U(1)$ symmetry is broken spontaneously into the $Z_3$ symmetry by the dark Higgs mechanism. As compared to dark matter models with $Z_2$ parity, the dark matter cubic self-interaction restricts the inflation with non-minimal couplings to take place beyond the pure dark matter direction and plays an important role in the loop corrections for the inflationary predictions as well as determining the correct dark matter relic density. Considering either of $2\to 2$, $3\to 2$ or forbidden channels to be a dominant production mechanism for dark matter, we show the viable parameter space of the model that is consistent with the theoretical and phenomenological constraints combined from inflation and dark matter.

   hep-phJHEP(2020)·17 citations
9. 09*

   Searching for New Physics in Two-Neutrino Double Beta Decay

   Frank F. Deppisch🇬🇧 · Lukas Graf🇩🇪 · Fedor Šimkovic🇸🇰

   Motivated by non-zero neutrino masses and the possibility of New Physics discovery, a number of experiments search for neutrinoless double beta decay. While hunting for this hypothetical nuclear process, a significant amount of two-neutrino double beta decay data has become available. Although these events are regarded and studied mostly as the background of neutrinoless double beta decay, they can be also used to probe physics beyond the Standard Model. In this paper we show how the presence of right-handed leptonic currents would affect the energy distribution and angular correlation of the outgoing electrons in two-neutrino double beta decay. Consequently, we estimate constraints imposed by currently available data on the existence of right-handed neutrino interactions without having to assume their nature. In this way our results complement the bounds coming from the non-observation of neutrinoless double beta decay as they limit also the exotic interactions of Dirac neutrinos. We perform a detailed calculation of two-neutrino double beta decay under the presence of exotic (axial-)vector currents and we demonstrate that current experimental searches can be competitive to existing limits.

   hep-phnucl-exnucl-thPRL(2020)·59 citations
10. 10*

    Shadowing in inelastic nucleon-nucleon cross section?

    Kari J. Eskola🇫🇮 · Ilkka Helenius🇫🇮 · Mikko Kuha🇫🇮 · Hannu Paukkunen🇫🇮

    Experimental results of inclusive hard-process cross sections in heavy-ion collisions conventionally lean on a normalization computed from Glauber models where the inelastic nucleon-nucleon cross section ${\sigma }_{\mathrm{nn}}^{\mathrm{inel}}$ -- a crucial input parameter -- is simply taken from proton-proton measurements. In this letter, using the computed electro-weak boson production cross sections in lead-lead collisions as a benchmark, we determine ${\sigma }_{\mathrm{nn}}^{\mathrm{inel}}$ from the recent ATLAS data. We find a significantly suppressed ${\sigma }_{\mathrm{nn}}^{\mathrm{inel}}$ relative to what is usually assumed, show the consequences for the centrality dependence of the cross sections, and address the phenomenon in an eikonal minijet model with nuclear shadowing.

    hep-phnucl-thPRL(2020)·25 citations
11. 11*

    Fermionic excitations at finite temperature and density

    Ralf-Arno Tripolt🇩🇪 · Dirk H. Rischke🇩🇪 · Lorenz von Smekal🇩🇪 · Jochen Wambach🇮🇹

    We study fermionic excitations in a hot and dense strongly interacting medium consisting of quarks and (pseudo-)scalar mesons. In particular, we use the two-flavor quark-meson model in combination with the Functional Renormalization Group approach, which allows to take into account the effects from thermal and quantum fluctuations. The resulting fermionic excitation spectrum is investigated by calculating the quark spectral function at finite temperature, quark chemical potential, and spatial momentum. This involves an analytic continuation from imaginary to real energies by extending the previously introduced analytically-continued FRG (aFRG) method to the present case. We identify three different collective excitations in the medium: the ordinary thermal quark, the plasmino mode, and an ultra-soft "phonino" mode. The dispersion relations of these modes are extracted from the quark spectral function. When compared to corresponding results from an FRG-improved one-loop calculation remarkable agreement is found.

    hep-phhep-thnucl-thPRD(2020)·15 citations
12. 12*

    The three-loop QED contributions to the $g-2$ of charged leptons with two internal fermion loops and a class of Kampé de Fériet series

    B. Ananthanarayan🇮🇳 · Samuel Friot🇫🇷 · Shayan Ghosh🇩🇪

    The three-loop QED mass-dependent contributions to the $g-2$ of each of the charged leptons with two internal closed fermion loops, sometimes called $A_3^{(6)}\left(\frac{m_1}{m_2},\frac{m_1}{m_3}\right)$ in the $g-2$ literature, is revisited using the Mellin-Barnes (MB) representation technique. Results for the muon and $\tau$ lepton anomalous magnetic moments $A_{3,\mu }^{(6)}$ and $A_{3,\tau }^{(6)}$, which were known as series expansions in the lepton mass ratios up to the first few terms only, are extended to their exact expressions. The contribution to the anomalous magnetic moment of the electron $A_{3,e}^{(6)}$ is also explicitly given in closed form. In addition to this, we show that the different series representations derived from the MB representation collectively converge for all possible values of the masses. Such unexpected behavior is related to the fact that these series bring into play double hypergeometric series that belong to a class of Kampé de Fériet series which we prove to have the same simple convergence and analytic continuation properties as the Appell $F_1$ double hypergeometric series.

    hep-phPRD(2020)·18 citations
13. 13*

    Implications of the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) with Liquid Argon

    O. G. Miranda🇲🇽 · D. K. Papoulias🇬🇷 · G. Sanchez Garcia🇲🇽 · O. Sanders🇲🇽 · M. Tórtola🇪🇸 · J. W. F. Valle🇪🇸

    The CENNS-10 experiment of the COHERENT collaboration has recently reported the first detection of coherent-elastic neutrino-nucleus scattering (CEvNS) in liquid Argon with more than $3\sigma$ significance. In this work, we exploit the new data in order to probe various interesting parameters which are of key importance to CEvNS within and beyond the Standard Model. A dedicated statistical analysis of these data shows that the current constraints are significantly improved in most cases. We derive a first measurement of the neutron rms charge radius of Argon, and also an improved determination of the weak mixing angle in the low energy regime. We also update the constraints on neutrino non-standard interactions, electromagnetic properties and light mediators with respect to those derived from the first COHERENT-CsI data.

    hep-phJHEP(2020)·108 citations
14. 14*

    CP Violation in Three-body $B$ Decays: A Model Ansatz

    Thomas Mannel🇩🇪 · Kevin Olschewsky🇩🇪 · K. Keri Vos🇩🇪

    The mechanism of CP violation remains one of the puzzles in particle physics. Key to understanding this phenomenon are nonleptonic $B$ decays, especially multibody decays which exhibit large CP asymmetries in various regions of phase space. A full QCD-based theoretical description of these decays is still missing, requiring the use of models to fit the data. In this paper, we suggest a model ansatz which reflects the underlying physics and the known mechanism of CP violation via the CKM matrix. In addition, since CP violation is driven by the interference between amplitudes with and without valence charm quarks, we argue that the opening of the open-charm threshold may play an important role in generating CP violation in the high invariant mass region. We present a natural extension of the isobar model to incorporate these effects. We suggest an analysis of nonleptonic three-body $B$ decay data including this extension, which would be interesting as it may give new hints to the sources of CP violation both at low and high invariant mass.

    hep-phhep-exJHEP(2020)·26 citations
15. 15*

    Resolving Hubble Tension by Self-Interacting Neutrinos with Dirac Seesaw

    Hong-Jian He🇨🇳 · Yin-Zhe Ma🇿🇦 · Jiaming Zheng🇨🇳

    Self-interacting neutrinos that begin to free-stream at close to matter-radiation equality can reduce the physical size of photon sound horizon at last scattering surface. This mechanism can be the reason why standard $\Lambda$CDM cosmology sees a lower value of the Hubble constant than local measurements from distance ladder. We propose a new realization of self-interacting Dirac neutrinos (SID$\nu$) with light-dark-photon mediator for a viable interaction mechanism. Our model is UV completed by a Dirac seesaw with anomaly-free dark $U(1{)}_X^{}$ gauge group which charges the right-handed neutrinos. This model naturally generates small masses for Dirac neutrinos and induces self-scattering of right-handed neutrinos. The scattering with left-handed neutrinos is suppressed by a chirality-flip mass insertion when the neutrino energy is much larger than its mass. The resultant neutrino self-scattering is not operative for $E_{\nu }\gtrsim O(\text{keV})$, which avoids the cosmological and laboratory constraints. By evolving Boltzmann equations for left- and right-handed neutrino number densities, we show that about $2/3$ of the left-handed neutrinos are converted into right-handed neutrinos in a short epoch between the Big-Bang Nucleosynthesis and the recombination, and interact with each other efficiently afterwards. The resultant neutrino non-free-streaming is the crucial ingredient to shrink down the comoving sound horizon at drag epoch, which can reconcile the Hubble tension between early and late time measurements.

    hep-phastro-ph.COgr-qcJCAP(2020)·54 citations
16. 16*

    Mutual assistance between the Schwinger mechanism and the dynamical Casimir effect

    Hidetoshi Taya🇨🇳

    We study massive charged particle production from the vacuum confined between two vibrating plates in the presence of a strong electric field. We analytically derive a formula for the production number based on the perturbation theory in the Furry picture, and show that the Schwinger mechanism by the strong electric field and the dynamical Casimir effect by the vibration assist with each other to dramatically enhance the production number by orders of the magnitude.

    hep-phhep-thnucl-thphysics.plasm-ph+1PRResearch(2020)·10 citations
17. 17*

    A scheme for neutrino mass generation through modified Higgs mechanism

    Yanbin Deng🇨🇳 · Changyu Huang🇺🇸 · Yong-Chang Huang🇨🇳

    We propose a new method for neutrino mass generation through a modified Higgs mechanism by introducing an additional tiny vacuum breaking to the charged Higgs field. With identical particle spectrum as standard electroweak model, this modified Higgs mechanism endows the lepton-Higgs Yukawa coupling Lagrangian with a modified lepton mass matrix. Inserting the latest data of particle experiments into this modified lepton mass matrix enable us to locate the value of the newly introduced parameter parametrizing the extra perturbative Higgs vacuum breaking and produce masses for neutrinos of three generations. We reach a sum of three-generation neutrino massess at: ${\Sigma }_{(\nu )}{m}_{\nu }\approx 0.104078eV$. This prediction is supported by the result of the latest cosmological observation, i.e. the 95\% C.L. upper bound ${\Sigma }_{(\nu )}{m}_{\nu }<0.176eV$ determined by the Planck data. In our proposal of the modified Higgs mechanism, the Higgs vacua break twice, such that, the very minuteness of the extra Higgs vacuum breaking explains the origin of the very minuteness of neutrino masses, while the relative greatness of the standard Higgs vacuum breaking is recognized as the origin of the relative greatness of charged lepton masses. This proposal can bring rich new physics to Higgs-relevant problems in particle physics, besides the massive neutrino problems.

    hep-ph1 citation
18. 18*

    Plasmon production from dark matter scattering

    Jonathan Kozaczuk🇺🇸 · Tongyan Lin🇺🇸

    We present a first calculation of the rate for plasmon production in semiconductors from nuclei recoiling against dark matter. The process is analogous to bremsstrahlung of transverse photon modes, but with a longitudinal plasmon mode emitted instead. For dark matter in the 10 MeV - 1 GeV mass range, we find that the plasmon bremsstrahlung rate is 4-5 orders of magnitude smaller than that for elastic scattering, but 4-5 orders of magnitude larger than the transverse bremsstrahlung rate. Because the plasmon can decay into electronic excitations and has characteristic energy given by the plasma frequency ${\omega }_p$, with ${\omega }_p\approx 16$ eV in Si crystals, plasmon production provides a distinctive signature and new method to detect nuclear recoils from sub-GeV dark matter.

    hep-phastro-ph.COhep-exPRD(2020)·32 citations
19. 19*

    Strong coupling constant and quark masses from lattice QCD

    Javad Komijani🇮🇷 · Peter Petreczky🇺🇸 · Johannes Heinrich Weber🇺🇸

    We review lattice determinations of the charm and bottom quark masses and the strong coupling constant obtained by different methods. We explain how effective field theory approaches, such as Non-Relativistic QCD (NRQCD), potential Non-Relativistic QCD (pNRQCD), Heavy Quark Effective Theory (HQET) and Heavy Meson rooted All-Staggered Chiral Perturbation Theory (HMrAS$\chi$PT) can help in these determinations. After critically reviewing different lattice results we determine lattice world averages for the strong coupling constant, ${\alpha }_s(M_Z,N_f=5)=0.11803_{-0.00068}^{+0.00047}$, as well as for the charm quark mass, $m_c(m_c,N_f=4)=1.2735(35)$ GeV, and the bottom quark mass, $m_b(m_b,N_f=5)=4.188(10)$ GeV. The above determinations are more precise than the ones obtained by Particle Data Group (PDG).

    ↳ hep-lathep-phPPNP(2020)·28 citations
20. 20*

    Deep learning and k-means clustering in heterotic string vacua with line bundles

    Hajime Otsuka🇯🇵 · Kenta Takemoto🇯🇵

    We apply deep-learning techniques to the string landscape, in particular, $SO(32)$ heterotic string theory on simply-connected Calabi-Yau threefolds with line bundles. It turns out that three-generation models cluster in particular islands specified by deep autoencoder networks and k-means++ clustering. Especially, we explore mutual relations between model parameters and the cluster with densest three-generation models (called "3-generation island"). We find that the 3-generation island has a strong correlation with the topological data of Calabi-Yau threefolds, in particular, second Chern class of the tangent bundle of the Calabi-Yau threefolds. Our results also predict a large number of Higgs pairs in the 3-generation island.

    ↳ hep-thhep-phJHEP(2020)·25 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.