Mon·Feb 18, 2019Monday·February 18, 2019

1. 01*

   Solving differential equations with neural networks: Applications to the calculation of cosmological phase transitions

   Maria Laura Piscopo🇬🇧 · Michael Spannowsky🇬🇧 · Philip Waite🇬🇧

   Starting from the observation that artificial neural networks are uniquely suited to solving optimisation problems, and most physics problems can be cast as an optimisation task, we introduce a novel way of finding a numerical solution to wide classes of differential equations. We find our approach to be very flexible and stable without relying on trial solutions, and applicable to ordinary, partial and coupled differential equations. We apply our method to the calculation of tunnelling profiles for cosmological phase transitions, which is a problem of relevance for baryogenesis and stochastic gravitational wave spectra. Comparing our solutions with publicly available codes which use numerical methods optimised for the calculation of tunnelling profiles, we find our approach to provide at least as accurate results as these dedicated differential equation solvers, and for some parameter choices even more accurate and reliable solutions. In particular, we compare the neural network approach with two publicly available profile solvers, \texttt{CosmoTransitions} and \texttt{BubbleProfiler}, and give explicit examples where the neural network approach finds the correct solution while dedicated solvers do not. We point out that this approach of using artificial neural networks to solve equations is viable for any problem that can be cast into the form $\mathcal{F}(\vec{x})=0$, and is thus applicable to various other problems in perturbative and non-perturbative quantum field theory.

   hep-phhep-thPRD(2019)·40 citations
2. 02*

   On $SU(3{)}_F$ Breaking through Final State Interactions and CP Asymmetries in $D\to PP$ Decays

   Franco Buccella🇮🇹 · Ayan Paul🇩🇪 · Pietro Santorelli🇮🇹

   We analyse $D$ decays to two pseudoscalars $(\pi ,K)$ assuming the dominant source of $\mathrm{SU}(3{)}_F$ breaking lies in final state interactions. We obtain an excellent agreement with experimental data and are able to predict CP violation in several channels based on current data on branching ratios and $\Delta {\mathrm{A}}_{\mathrm{CP}}$. We also make predictions for ${\delta }_{K\pi }$ and the branching fraction for the decay $D_s^{+}\to K^{+}{K}_L$.

   hep-phhep-exPRD(2019)·71 citations
3. 03*

   S-wave baryon nonleptonic decay amplitude in large-N_c chiral perturbation theory

   Ruben Flores-Mendieta🇲🇽

   The s-wave decay amplitude in the nonleptonic decay of baryons is analyzed within heavy baryon chiral perturbation theory in the large-N_c limit at one-loop order, where N_c is the number of color charges. Loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis and the effects of the decuplet-octet mass difference are accounted for. There are large-N_c cancellations between different one-loop graphs as a consequence of the large-N_c spin-flavor symmetry of QCD baryons. The predictions of large-N_c baryon chiral perturbation theory are in very good agreement both with the expectations from the 1/N_c expansion and with the experimental data.

   hep-phPRD(2019)·8 citations
4. 04*

   Elastic and diffractive scattering in the LHC era

   László Jenkovszky🇺🇦 · Rainer Schicker🇩🇪 · István Szanyi🇺🇦

   We review elastic and diffractive scattering of protons (called also "forward physics") with emphasis on the LHC data, especially those deviating from the expectations based on extrapolations from earlier measurements at the ISR, Fermilab and thus triggering searches for new ideas, models and theories. We list these new data and provide a brief introduction of available theoretical approaches, mainly those based on analyticity, crossing symmetry and unitarity, particularly the Regge-pole model realizing these concepts. Fits to the data are presented and tensions between theoretical predictions and the data that may indicate the way to further progress are in the focus of our paper.

   hep-phIJMPE(2018)·25 citations
5. 05*

   Revisiting the LHC reach in the displaced region of the minimal left-right symmetric model

   Giovanna Cottin🇹🇼 · Juan Carlos Helo🇨🇱 · Martin Hirsch🇪🇸 · Dario Silva🇨🇱

   We revisit discovery prospects for a long-lived sterile neutrino $N$ at the Large Hadron Collider (LHC) in the context of left-right symmetric theories. We focus on a displaced vertex search strategy sensitive to $\mathcal{O}$(GeV) neutrino masses produced via a right-handed $W_R$ boson. Both on-shell and off-shell Drell-Yan production of $W_R$ are considered. We estimate the reach as a function of $m_N$ and $m_{W_R}$. With $\sqrt{s}=13$ TeV and 300/fb of integrated luminosity, the LHC can probe neutrino masses as high as $\sim 30$ GeV and $m_{W_R}$ around 6 TeV. The reach goes up to 11.5 TeV with 3000/fb and $m_N\sim 45$ GeV. This represents an improvement of a factor of 2 in sensitivity with respect to earlier work.

   hep-phhep-exPRD(2019)·21 citations
6. 06*

   Open-string singlet interaction as pomeron in elastic $pp,p\bar{p}$ scattering

   Piyabut Burikham🇹🇭 · Daris Samart🇹🇭

   We consider contributions of the open-string singlet~(OSS) interaction to the proton-proton scattering. Modelling baryon and meson as instanton and open string in the effective QCD string model, the typical pomeron is identified with a massive spin-2 closed string. According to the open-closed string duality, the massive spin-2 closed string is accompanied by the open-string singlet interaction with universal coupling. The flat space 4-point open-string singlet amplitudes and cross sections are computed in the Regge limit. Including both the open and closed string pomerons, we fit the differential cross-section with experimental data of the proton-proton and proton-antiproton scattering from the CDF, E-710, D0, LHC-ATLAS and LHC-TOTEM collaborations. The fitting results show the universality of the string mass scale~(or string tension) and consistency of the string model between the open and closed string parameters in describing the $pp$ and $p\bar{p}$ scattering in the Regge limit. The fitting of the string model to experimental data gives the string scale $M_S\simeq 1.7-1.8$ GeV and the corresponding glueball pole mass $m_g\simeq 1.6-1.7$ GeV. This lies within experimental values of the observed $2^{++},I=0$ "meson" masses.

   hep-phhep-thEPJC(2019)·9 citations
7. 07*

   Production of $Z_c(3900$) and $Z_c(4020)$ in $B_c$ decay

   Qi Wu🇨🇳 · Dian-Yong Chen🇨🇳 · Xue-Jia Fan🇨🇳 · Gang Li🇨🇳

   In the present work, we propose to search the charmonium-like states $Z_c(3900$) and $Z_c(4020)$ in the $B_c$ decay. In an effective Lagrangian approach, the branching ratios of $B_c^{+}\to Z_c(3900{)}^{+}{\pi }^0$ and $B_c^{+}\to Z_c(4020{)}^{+}{\pi }^0$ are estimated to be of order of $10^{-4}$ and $10^{-7}$, respectively. The large production rate of $Z_c(3900)$ could provide an important source of the production of $Z_c(3900)$ from the semi-exclusive decay of $b$-flavored hadrons reported by D0 Collaboration, which can be tested by the exclusive measurements in LHCb.

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

   Investigating tetraquarks composed of $us\bar{d}\bar{b}$ and $ud\bar{s}\bar{b}$

   Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

   In the framework of the quark delocalization color screening model, we investigate tetraquarks composed of $us\bar{d}\bar{b}$ and $ud\bar{s}\bar{b}$ in two structures: meson-meson structure and diquark-antidiquark structure. Neither bound state nor resonance state is found in the system composed of $us\bar{d}\bar{b}$. The reported $X(5568)$ cannot be explained as a molecular state or a diquark-antidiquark resonance of $us\bar{d}\bar{b}$ in present calculation. However, two bound states of the diquark-antidiquark structure are obtained in the tetraquarks system composed of $ud\bar{s}\bar{b}$: an $IJ=00$ state with the mass of $5701$ MeV, and an $IJ=01$ state with the mass of $5756$ MeV, which maybe the partners of $X(5568)$ states. Our results indicate that the diquark-antidiquark configuration would be a good choice for the tetraquarks $ud\bar{s}\bar{b}$ with quantum numbers $IJ=00$ and $IJ=01$. The tetraquarks composed of $ud\bar{s}\bar{b}$ is more possible to form bound states than the one composed of $us\bar{d}\bar{b}$. These bound states are worth investigating in future experiments.

   hep-phEPJC(2019)·17 citations
9. 09*

   Alternative formulation of left-right symmetry with $B-L$ conservation and purely Dirac neutrinos

   Patrick D. Bolton🇬🇧 · Frank F. Deppisch🇬🇧 · Chandan Hati🇫🇷 · Sudhanwa Patra🇮🇳 · Utpal Sarkar🇮🇳

   We propose an alternative formulation of a Left-Right Symmetric Model (LRSM) where the difference between baryon number ($B$) and lepton number ($L$) remains an unbroken symmetry. This is unlike the conventional formulation, where $B-L$ is promoted to a local symmetry and is broken explicitly in order to generate Majorana neutrino masses. In our case $B-L$ remains a global symmetry after the left-right symmetry breaking, allowing only Dirac mass terms for neutrinos. In addition to parity restoration at some high scale, this formulation provides a natural framework to explain $B-L$ as an anomaly-free global symmetry of the Standard Model and the non-observation of $(B-L)$-violating processes. Neutrino masses are purely Dirac type and are generated either through a two loop radiative mechanism or by implementing a Dirac seesaw mechanism.

   hep-phPRD(2019)·39 citations
10. 10*

    Exploring SMEFT in VH with Machine Learning

    Felipe F. Freitas🇨🇳 · Charanjit K. Khosa🇬🇧 · Verónica Sanz🇬🇧

    In this paper we study the use of Machine Learning techniques to exploit kinematic information in VH, the production of a Higgs in association with a massive vector boson. We parametrise the effect of new physics in terms of the SMEFT framework. We find that the use of a shallow neural network allows us to dramatically increase the sensitivity to deviations in VH respect to previous estimates. We also discuss the relation between the usual measures of performance in Machine Learning, such as AUC or accuracy, with the more adept measure of Asimov significance. This relation is particularly relevant when parametrising systematic uncertainties. Our results show the potential of incorporating Machine Learning techniques to the SMEFT studies using the current datasets.

    hep-phhep-exPRD(2019)·45 citations
11. 11*

    Fully Heavy Tetraquark $bb\bar{c}\bar{c}$: Lifetimes and Weak Decays

    Gang Li🇨🇳 · Xiao-Feng Wang🇨🇳 · Ye Xing🇨🇳

    We study the lifetime and weak decays of the full-heavy S-wave $0^{+}$ tetraquark $T_{\{\bar{c}\bar{c}\}}^{\{bb\}}$. Using the operator product expansion rooted in heavy quark expansion, we find a rather short lifetime, at the order $(0.1-0.3)\times 10^{-12}s$ depending on the inputs. With the flavor SU(3) symmetry, we then construct the effective Hamiltonian at the hadron level, and derive relations between decay widths of different channels. According to the electro-weak effective operators, we classify different decay modes, and make a collection of the golden channels, such as $T_{\{\bar{c}\bar{c}\}}^{\{bb\}}\to B^{-}{K}^0{B}_c^{-}$ for the charm quark decay and $T_{\{\bar{c}\bar{c}\}}^{\{bb\}}\to B^{-}{D}^{-}$ for the bottom quark decay. Our results for the lifetime and golden channels are helpful to search for the fully-heavy tetraquark in future experiments.

    hep-phEPJC(2019)·22 citations
12. 12*

    Path to the $0.01\%$ Theoretical Luminosity Precision Requirement for the FCC-ee (and ILC)

    B.F.L. Ward (1)🇺🇸 · S. Jadach (2)🇵🇱 · W. Placzek (3)🇵🇱 · M. Skrzypek (2)🇵🇱 · S.A. Yost (4) ((1) Baylor University, Waco, TX, USA, (2), Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, PL,(3) Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow, PL, (4) The Citadel, Charleston, SC, USA)🇺🇸

    We present pathways to the required theoretical precision for the luminosity targeted by the FCC-ee precision studies. We put the discussion in context by reviewing briefly the situation at the time of LEP. We then present the current status and routes to the desired 0.01\% targeted by the FCC-ee (as well as by the ILC).

    hep-ph4 citations
13. 13*

    Coset Cosmology

    Luca Di Luzio🇮🇹 · Michele Redi🇮🇹 · Alessandro Strumia🇮🇹 · Daniele Teresi🇮🇹

    We show that the potential of Nambu-Goldstone bosons can have two or more local minima e.g. at antipodal positions in the vacuum manifold. This happens in many models of composite Higgs and of composite Dark Matter. Trigonometric potentials lead to unusual features, such as symmetry non-restoration at high temperature. In some models, such as the minimal $\mathrm{SO}(5)/SO(4)$ composite Higgs with fermions in the fundamental representation, the two minima are degenerate giving cosmological domain-wall problems. Otherwise, an unusual cosmology arises, that can lead to supermassive primordial black holes; to vacuum or thermal decays; to a high-temperature phase of broken $\mathrm{SU}(2{)}_L$, possibly interesting for baryogenesis.

    hep-phastro-ph.COJHEP(2019)·20 citations
14. 14*

    Which EFT

    Adam Falkowski🇫🇷 · Riccardo Rattazzi🇨🇭

    We classify effective field theory (EFT) deformations of the Standard Model (SM) according to the analyticity property of the Lagrangian as a function of the Higgs doublet H. Our distinction in analytic and non-analytic corresponds to the more familiar one between linearly and non-linearly realized electroweak symmetry, but offers deeper physical insight. From the UV perspective, non-analyticity occurs when the new states acquire mass from electroweak symmetry breaking, and thus cannot be decoupled to arbitrarily high scales. This is reflected in the IR by the anomalous growth of the interaction strength for processes involving many Higgs bosons and longitudinally polarized massive vectors, with a breakdown of the EFT description below a scale $O(4\pi v)$. Conversely, analyticity occurs when new physics can be pushed parametrically above the electroweak scale. We illustrate the physical distinction between these two EFT families by discussing Higgs boson self-interactions. In the analytic case, at the price of some unnaturalness in the Higgs potential, there exists space for $O(1)$ deviations of the cubic coupling, compatible with single Higgs and electroweak precision measurements, and with new particles out of the direct LHC reach. Larger deviations are possible, but subject to less robust assumptions about higher-dimensional operators in the Higgs potential. On the other hand, when the cubic coupling is produced by a non-analytic deformation of the SM, we show by an explicit calculation that the theory reaches strong coupling at $O(4\pi v)$, quite independently of the magnitude of the cubic enhancement.

    hep-phJHEP(2019)·142 citations
15. 15*

    Safe Clockwork

    Francesco Sannino🇩🇰 · Juri Smirnov🇩🇰 · Zhi-Wei Wang🇨🇦

    In this letter we demonstrate that safe quantum field theories can accommodate the clockwork mechanism upgrading it to a fundamental theory a lá Wilson. Additionally the clockwork mechanism naturally sources Yukawa hierarchies for safe completions of the Standard Model (SM). As proof of concept we investigate a safe Pati-Salam (PS) clockwork structure.

    hep-phPRD(2019)·23 citations
16. 16*

    Detecting dark photon dark matter with Gaia-like astrometry observations

    Huai-Ke Guo🇨🇳 · Yingqi Ma🇨🇳 · Jing Shu🇨🇳 · Xiao Xue🇨🇳 · Qiang Yuan🇨🇳 · Yue Zhao🇺🇸

    A class of dark photon dark matter models with ultralight masses would lead to oscillation of a test body through a coupling with baryons or $B-L$ charge. This periodical oscillation of an observer results in swing of a star's apparent position due to the effect of aberration of light, which could be probed with high-precision astrometry observations of stars in the Milky Way. We propose to use the observations of stellar positions of a number of stars by Gaia to search for this kind of dark photon dark matter. We show that this astrometry method is able to give promising sensitivities to search for the dark photon dark matter in the mass range of $10^{-23}\sim 10^{-21}$ eV.

    hep-phastro-ph.HEJCAP(2019)·16 citations
17. 17*

    On the Feynman Rules of Massive Gauge Theory in Physical Gauges

    Junmou Chen🇰🇷

    For a massive gauge theory with Higgs mechanism in a physical gauge, the longitudinal polarization of gauge bosons can be naturally identified as mixture of the goldstone component and a remnant gauge component that vanishes at the limit of zero mass, making the goldstone equivalence manifest. In light of this observation, we re-examine the Feynman rules of massive gauge theory by treating gauge fields and their corresponding goldstone fields as single objects, writing them uniformly as 5-component "vector" fields. The gauge group is taken to be $SU(2{)}_L$ to preserve custodial symmetry. We find the derivation of gauge-goldstone propagators becomes rather trivial by noticing there is a remarkable parallel between massless gauge theory and massive gauge theory in this notation. We also derive the Feynman rules of all vertices, finding the vertex for self-interactions of vector (gauge-goldstone) bosons are especially simplified. We then demonstrate that the new form of the longitudinal polarization vector and the standard form give the same results for all the 3-point on-shell amplitudes. This on-shell matching confirms similar results obtained with on-shell approach for massive scattering amplitudes by Arkani-Hamed et.al. Finally we calculate some $1\to 2$ collinear splitting amplitudes by making use of the new Feynman rules and the on-shell match condition.

    hep-ph7 citations
18. 18*

    Nuclear Transparency in Monte Carlo Neutrino Event Generators

    Kajetan Niewczas🇧🇪 · Jan T. Sobczyk🇵🇱

    Hadron cascade model is an essential part of Monte Carlo neutrino event generators that governs final state interactions of knocked-out nucleons and produced pions. It is shown that such model enriched with physically motivated modifications of nucleon-nucleon cross section and incorporation of nuclear correlation effects is able to reproduce experimental nuclear transparency data. Uncertainty of nucleon final state interactions effects is estimated and applied to recent neutrino-nucleus cross section measurements that include an outgoing proton in the experimental signal. Conclusions are drawn on a perspective of identification of events that originate from two-body current mechanism.

    ↳ hep-exhep-phPRC(2019)·53 citations
19. 19*

    Anisotropic $2$-form dark energy

    Juan P. Beltrán Almeida🇨🇴 · Alejandro Guarnizo🇨🇴 · Ryotaro Kase🇯🇵 · Shinji Tsujikawa🇯🇵 · César A. Valenzuela-Toledo🇨🇴

    We study the dynamics of dark energy in the presence of a 2-form field coupled to a canonical scalar field $\varphi$. We consider the coupling proportional to $e^{-\mu \varphi /M_{\mathrm{pl}}}{H}_{\alpha \beta \gamma }{H}^{\alpha \beta \gamma }$ and the scalar potential $V(\varphi )\propto e^{-\lambda \varphi /M_{\mathrm{pl}}}$, where $H_{\alpha \beta \gamma }$ is the 2-form field strength, $\mu ,\lambda$ are constants, and $M_{\mathrm{pl}}$ is the reduced Planck mass. We show the existence of an anisotropic matter-dominated scaling solution followed by a stable accelerated fixed point with a non-vanishing shear. Even if $\lambda \ge \mathcal{O}(1)$, it is possible to realize the dark energy equation of state $w_{\mathrm{DE}}$ close to $-1$ at low redshifts for $\mu \gg \lambda$. The existence of anisotropic hair and the oscillating behavior of $w_{\mathrm{DE}}$ are key features for distinguishing our scenario from other dark energy models like quintessence.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2019)·28 citations
20. 20*

    Non-local Lagrangians from Renormalons and Analyzable Functions

    Alessio Maiezza🇭🇷 · Juan Carlos Vasquez🇨🇱

    We embed in a generalized Borel procedure the notion of renormalization and renormalons. While there are several efforts in literature to have a semi-classical understanding of the renormalons, here we argue that this is not the fundamental issue and show how to deal with the problem. We find that the effective Lagrangians describing the effects of renormalons are non-local in space but local in time. The quark-antiquark potential in QCD with an infinite number of fermions is also analyzed. The connection between the analyzable functions, the Callan-Symanzyk equation and the renormalons, provides an insight of a non-perturbative renormalization from the standard perturbative renormalization approach.

    ↳ hep-thhep-phmath-phmath.MPAnnals Phys.(2019)·22 citations
21. 21*

    Viable inflationary magnetogenesis with helical coupling

    Yuri Shtanov🇺🇦

    We consider helical coupling to electromagnetism and present a simple scenario of evolution of the coupling function leading to a viable inflationary magnetogenesis without the problem of back-reaction. In this scenario, helical magnetic fields of strength of order up to $10^{-7}\text{G}$, when extrapolated to the current epoch, can be generated in a narrow spectral band centered at any reasonable wavenumber by adjusting the model parameters. We discuss implications of this model for baryogenesis, which impose additional constraints on the strength and correlation length of magnetic field.

    ↳ astro-ph.COgr-qchep-phJCAP(2019)·22 citations
22. 22*

    Multi-stage jet evolution through QGP using the JETSCAPE framework: inclusive jets, correlations and leading hadrons

    C. Park · A. Angerami · S. A. Bass · S. Cao · J. Coleman · L. Cunqueiro · T. Dai · L. Du · H. Elfner · D. Everett · W. Fan · R. Fries and 32 other authors

    The JETSCAPE Collaboration has recently announced the first release of the JETSCAPE package that provides a modular, flexible, and extensible Monte Carlo event generator. This innovative framework makes it possible to perform a comprehensive study of multi-stage high-energy jet evolution in the Quark-Gluon Plasma. In this work, we illustrate the performance of the event generator for different algorithmic approaches to jet energy loss, and reproduce the measurements of several jet and hadron observables as well as correlations between the hard and soft sector. We also carry out direct comparisons between different approaches to energy loss to study their sensitivity to those observables.

    ↳ nucl-thhep-phnucl-exPoS(2019)·13 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.