Wed·Aug 15, 2018Wednesday·August 15, 2018

1. 01*

   Challenges with Large Transverse Momentum in Semi-Inclusive Deeply Inelastic Scattering

   J. O. Gonzalez-Hernandez🇺🇸 · T. C. Rogers🇺🇸 · N. Sato🇺🇸 · B. Wang🇺🇸

   We survey the current phenomenological status of semi-inclusive deep inelastic scattering at moderate hard scales and in the limit of very large transverse momentum. As the transverse momentum becomes comparable to or larger than the overall hard scale, the differential cross sections should be calculable with fixed order pQCD methods, while small transverse momentum (TMD factorization) approximations should eventually break down. We find large disagreement between HERMES and COMPASS data and fixed order calculations done with modern parton densities, even in regions of kinematics where such calculations should be expected to be very accurate. Possible interpretations are suggested.

   hep-phhep-exPRD(2018)·50 citations
2. 02*

   On the Rotational Invariance and Non-Invariance of Lepton Angular Distributions in Drell-Yan and Quarkonium Production

   Jen-Chieh Peng🇺🇸 · Daniel Boer🇳🇱 · Wen-Chen Chang🇹🇼 · Randall Evan McClellan🇺🇸 · Oleg Teryaev🇷🇺

   Several rotational invariant quantities for the lepton angular distributions in Drell-Yan and quarkonium production were derived several years ago, allowing the comparison between different experiments adopting different reference frames. Using an intuitive picture for describing the lepton angular distribution in these processes, we show how the rotational invariance of these quantities can be readily obtained. This approach can also be used to determine the rotational invariance or non-invariance of various quantities specifying the amount of violation for the Lam-Tung relation. While the violation of the Lam-Tung relation is often expressed by frame-dependent quantities, we note that alternative frame-independent quantities are preferred.

   hep-phnucl-thPLB(2019)·17 citations
3. 03*

   CoDEx: Wilson coefficient calculator connecting SMEFT to UV theory

   Supratim Das Bakshi🇮🇳 · Joydeep Chakrabortty🇮🇳 · Sunando Kumar Patra🇮🇳

   CoDEx is a Mathematica package that calculates the Wilson Coefficients (WCs) corresponding to effective operators up to mass dimension-6. Once the part of the Lagrangian involving single as well as multiple degenerate heavy fields, belonging to some Beyond Standard Model (BSM) theory, is given, the package can then integrate out propagators from the tree as well as 1-loop diagrams of that BSM theory. It then computes the associated WCs up to 1-loop level, for two different bases: "Warsaw" and "SILH". CoDEx requires only very basic information about the heavy field(s), e.g., Colour, Isospin, Hyper-charge, Mass, and Spin. The package first calculates the WCs at the high scale (mass of the heavy field(s)). We then have an option to perform the renormalisation group evolutions (RGEs) of these operators in "Warsaw" basis, a complete one (unlike "SILH"), using the anomalous dimension matrix. Thus, one can get all effective operators at the electro-weak scale, generated from any such BSM theory, containing heavy fields of spin: 0, 1/2, and 1. We have provided many example models (both here and in the package-documentation) that more or less encompass different choices of heavy fields and interactions. Relying on the status of the present day precision data, we restrict ourselves up to dimension-6 effective operators. This will be generalised for any dimensional operators in a later version. Site: https://effexteam.github.io/CoDEx

   hep-phhep-exhep-thEPJC(2019)·122 citations
4. 04*

   Unitarized HEFT for strongly interacting longitudinal electroweak gauge bosons with resonances

   Rafael L. Delgado🇩🇪 · Antonio Dobado🇪🇸 · Felipe J. Llanes-Estrada🇪🇸

   Higgs Effective Field Theory can be used to study vector-boson elastic scattering at the high energies relevant for the LHC. For most of the parameter space, the scattering is strongly interacting, with the minimal Standard Model being a remarkable exception. From its one-loop treatment complemented with dispersion relations and the Equivalence Theorem, we derive two different unitarization methods which produce analytical amplitudes corresponding to different approximate solutions to the dispersion relations: the Inverse Amplitude method (IAM) and the N/D method. The partial waves obtained can show poles in the second Riemann sheet whose natural interpretation is that of dynamical resonances with masses and widths a function of the starting HEFT parameters. We compare the different unitarizations and we find that they are qualitatively, and in many cases quantitatively, very similar. However, for different reason it is more interesting to use one of the two methods depending on the particular channel for WW, ZZ, WZ, Zh, Wh or hh scattering. In this note we briefly describe the possible I and J channels for these reactions and give the unitarization method of choice in each case. The amplitudes obtained provide realistic resonant and nonresonant cross sections to be compared with and to be used for a proper interpretation of the LHC data.

   hep-phPoS(2018)·1 citation
5. 05*

   Threshold and jet radius joint resummation for single-inclusive jet production

   Sven-Olaf Moch🇩🇪 · Engin Eren🇩🇪 · Katerina Lipka🇩🇪 · Xiaohui Liu🇨🇳 · Felix Ringer🇺🇸

   The QCD predictions for single-inclusive jet production are computed with joint resummation of threshold and jet radius logarithms. The results are compared to those based on fixed order perturbation theory up to next-to-next-to-leading order and to data by the CMS collaboration measured in proton-proton collisions at the LHC at $\sqrt{S}=8$ TeV. The joint resummation results are in remarkable agreement with the data.

   hep-phPoS(2018)·3 citations
6. 06*

   The Space-Time Structure of Hadronization in the Lund Model

   Silvia Ferreres-Solé🇮🇹 · Torbjörn Sjöstrand🇸🇪

   The assumption of linear confinement leads to a proportionality of the energy-momentum and space-time pictures of fragmentation for a simple qqbar system in the Lund string model. The hadronization of more complicated systems is more difficult to describe, and in the past only the energy-momentum picture has been implemented. In this article also the space-time picture is worked out, for open and closed multiparton topologies, for junction systems, and for massive quarks. Some first results are presented, for toy systems but in particular for LHC events. The density of hadron production is quantified under different conditions. The (not unexpected) conclusion is that this density can become quite high, and thereby motivate the observed collective behaviour in high-multiplicity pp collisions. The new framework, made available as part of the Pythia event generator, offers a starting point for future model building in a number of respects, such as hadronic rescattering.

   hep-phEPJC(2018)·113 citations
7. 07*

   The Generalized Abelian and Non-Abelian Gauge Theories and their Particle Physics Applications

   Tianjun Li🇨🇳

   Gauge theory is the foundation of the particle physics Standard Model (SM). Considering the multiple gauge sectors for one gauge transformation, we study the generalized Abelian and non-Abelian (Yang-Mills theory) gauge theories. We first point out that the U(1) gauge theory has a few unique properties, which provide the motivations for the generalized Yang-Mills theory. Also, we consider the generalized Abelian gauge theory, and study the Higgs mechanism with new interesting properties. In addition, we propose the simple and generic generalizations of Yang-Mills theory. In the simple generalization, we realize two specific properties in the Abelian gauge theory. For applications in particle physics, we propose the invisible axion model with TeV-scale Peceei-Quinn symmetry breaking. We can solve the strong CP problem, and obtain the effective decay constant around the intermediate scale. Moreover, we study the SM electroweak symmetry breaking induced from the symmetry breaking in the other gauge Sector. In particular, we can easily obtain the strong first order electroweak phase transition in the SM, which is important for electroweak baryogenesis and gravitational wave.

   hep-phhep-th0 citations
8. 08*

   Probing heavy ion collisions using quark and gluon jet substructure with machine learning

   Yang-Ting Chien🇺🇸

   Understanding the inner working of the quark-gluon plasma requires complete and precise jet substructure studies in heavy ion collisions. In this proceeding we discuss the use of quark and gluon jets as independent probes, and how their classification allows us to uncover regions of QCD phase space sensitive to medium dynamics. We introduce the telescoping deconstruction (TD) framework to capture complete jet information and show that TD observables reveal fundamental properties of quark and gluon jets and their modifications in the medium. We draw connections to soft-drop subjet distributions and illuminate medium-induced jet modifications using Lund diagrams. The classification is also studied using a physics-motivated, multivariate analysis of jet substructure observables. Moreover, we apply image-recognition techniques by training a deep convolutional neural network on jet images to benchmark classification performances. We find that the quark gluon discrimination performance worsens in \textsc{Jewel}-simulated heavy ion collisions due to significant soft radiation affecting soft jet substructures. This work suggests a systematic framework for jet studies and facilitates direct comparisons between theoretical calculations and measurements in heavy ion collisions.

   hep-phnucl-exnucl-thNPA(2019)·8 citations
9. 09*

   Anomalous dimension of subleading-power $N$-jet operators II

   Martin Beneke🇩🇪 · Mathias Garny🇩🇪 · Robert Szafron🇩🇪 · Jian Wang🇩🇪

   We continue the investigation of the anomalous dimension of subleading-power $N$-jet operators. In this paper, we focus on the operators with fermion number one in each collinear direction, corresponding to quark (antiquark) initiated jets in QCD. We investigate the renormalization effects induced by the soft loop and compute the one-loop mixing of time-ordered products involving power-suppressed SCET Lagrangian insertions into $N$-jet currents through soft loops. We discuss fermion number conservation in collinear directions and provide explicit results for the collinear anomalous dimension matrix of the currents. The Feynman rules for the power-suppressed SCET interactions in the position-space formalism are collected in an appendix.

   hep-phhep-thJHEP(2018)·90 citations
10. 10*

    Signature of light sterile neutrinos at IceCube

    Bhavesh Chauhan🇮🇳 · Subhendra Mohanty🇮🇳

    The MiniBooNe collaboration has recently reported evidence for a light sterile neutrino with large mixing angles thus corroborating the measurement by LSND twenty years ago. Such a state would be directly in conflict with Planck measurement of BBN $N_{eff}$ unless there is self-interaction in the sterile sector. Our objective is to investigate if such interactions could result in resonant absorption in the cosmogenic neutrino spectrum and its consequences for the IceCube experiment. We show that it is possible to give independent bounds on sterile neutrino parameter space from IceCube observations with the dips in the spectrum corresponding to the neutrino masses.

    hep-phPRD(2018)·19 citations
11. 11*

    Goldstone Boson Emission From Nucleon Cooper Pairing in Neutron Stars and Constraints on the Higgs Portal Models

    Huitzu Tu🇹🇼

    When a neutron star cools to below the critical temperature for the onset of superfluidity, nucleon pair breaking and formation (PBF) processes become the dominant mechanism for neutrino emission, while the modified URCA and the nuclear bremsstrahlung processes are suppressed. The PBF processes in neutron stars have also been used to set upper limits on the properties of axions, which are comparable to those set by supernova SN 1987A. We apply this constraint on Weinberg's Higgs portal model, in which the dark radiation particles (the Goldstone bosons) and the dark matter candidate (a Majorana fermion) interact with the Standard Model (SM) fields solely through the mixing of the SM Higgs boson and a light Higgs boson. We compare the Goldstone boson emissivity with that of the neutrinos by considering several superfluid gap models for the neutron singlet-state pairing in the neutron star inner crust, as well as in the core region. We find that the PBF processes in the superfluid neutron star interior can indeed probe Weinberg's Higgs portal model in a new parameter space region. Together with our previous works on the constraints from supernovae and gamma-ray bursts, this study demonstrates further the competitiveness and complementarity of astrophysics to laboratory particle physics experiments.

    hep-phastro-ph.HE0 citations
12. 12*

    Heavy quark mass effects in associated production

    Davide Napoletano🇫🇷

    Processes involving heavy quarks in associated production, are usually described in two factorisation schemes: one in which the heavy quark is treated as an infinitely massive object, decoupled from QCD evolution, and one in which it is treated on the same footing of a light quark. These two approaches only differ by the inclusion of mass suppressed terms or in the resummation of a certain class of logarithms. In view of recent results, in this talk, we present recent developments that extend a phenomenological scheme, that tries to incorporate the best of both worlds, to \NLO in Monte Carlo event generation.

    hep-phPoS(2018)·1 citation
13. 13*

    Dispersion relation for hadronic light-by-light scattering: pion pole

    Martin Hoferichter🇺🇸 · Bai-Long Hoid🇩🇪 · Bastian Kubis🇩🇪 · Stefan Leupold🇸🇪 · Sebastian P. Schneider🇩🇪

    The pion-pole contribution to hadronic light-by-light scattering in the anomalous magnetic moment of the muon $(g-2{)}_{\mu }$ is fully determined by the doubly-virtual pion transition form factor. Although this crucial input quantity is, in principle, directly accessible in experiment, a complete measurement covering all kinematic regions relevant for $(g-2{)}_{\mu }$ is not realistic in the foreseeable future. Here, we report in detail on a reconstruction from available data, both space- and time-like, using a dispersive representation that accounts for all the low-lying singularities, reproduces the correct high- and low-energy limits, and proves convenient for the evaluation of the $(g-2{)}_{\mu }$ loop integral. We concentrate on the systematics of the fit to $e^{+}{e}^{-}\to 3\pi$ data, which are key in constraining the isoscalar dependence, as well as the matching to the asymptotic limits. In particular, we provide a detailed account of the pion transition form factor at low energies in the time- and space-like region, including the error estimates underlying our final result for the pion-pole contribution, $a_{\mu }^{{\pi }^0\text{-pole}}=62.6_{-2.5}^{+3.0}\times 10^{-11}$, and demonstrate how forthcoming singly-virtual measurements will further reduce its uncertainty.

    hep-phhep-exhep-latnucl-thJHEP(2018)·537 citations
14. 14*

    Hunting for Heavy Winos in the Galactic Center

    Lucia Rinchiuso🇫🇷 · Nicholas L. Rodd🇺🇸 · Ian Moult🇺🇸 · Emmanuel Moulin🇫🇷 · Matthew Baumgart🇺🇸 · Timothy Cohen🇺🇸 · Tracy R. Slatyer🇺🇸 · Iain W. Stewart🇺🇸 · Varun Vaidya🇺🇸

    Observing gamma rays using ground-based atmospheric Cherenkov telescopes provides one of the only probes of heavy weakly interacting dark matter. A canonical target is the thermal wino, for which the strongest limits come from searches for photon lines from annihilations in the Galactic Center. Irreducible finite energy resolution effects motivate refining the prediction for a wino signal beyond the photon line approximation; recently, modern effective field theory techniques have been utilized to obtain a precise calculation of the full photon energy spectrum from wino annihilation. In this paper, we investigate the implications for a realistic mock H.E.S.S.-like line search. We emphasize the impact of including the non-trivial spectral shape, and we carefully treat the region of interest, presenting results for choices between $1^{\circ }$ and $4^{\circ }$ from the Galactic Center. Projected limits for wino masses from $1$-$70$ TeV are interpreted as a constraint on the wino annihilation rate, or alternatively as the minimum core size required such that the wino is not excluded. If there is a thermal wino, H.E.S.S. will be able to probe cores of several kpc, which would begin to cause tension between this dark matter candidate and astrophysical observations/simulations.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2018)·44 citations
15. 15*

    In medium properties of $K^0$ and $\varphi$ mesons under an external magnetic field

    R. M. Aguirre🇦🇷

    The one loop polarization insertions for the kaon and the $\varphi$ mesons are evaluated in a hadronic medium as functions of the field intensity and the baryonic density. For this purpose an effective chiral model of the hadronic interaction is used, supplemented with a phenomenological $K-\varphi$ interaction. The propagators of the charged particles include the full effect of the coupling to the magnetic field which induces the quantum Landau levels. Consequently, the vacuum diagrams are defined within a zeta function regularization scheme. The effective masses as well as the decay widths are introduced and examined as functions of matter density and the magnetic intensity.

    ↳ nucl-thhep-phEPJA(2019)·17 citations
16. 16*

    The Pauli sum rules imply BSM physics

    Matt Visser (Victoria University of Wellington)🇳🇿

    Some 67 years ago (1951) Wolfgang Pauli mooted the three sum rules: \[ \sum_n (-1)^{2S_n} g_n = 0; \qquad \sum_n (-1)^{2S_n} g_n \; m_n^2 =0; \qquad \sum_n (-1)^{2S_n} g_n \; m_n^4=0. \] These three sum rules are intimately related to both the Lorentz invariance and the finiteness of the zero-point stress-energy tensor. Further afield, these three constraints are also intimately related to the existence of finite QFTs ultimately based on fermi--bose cancellations. (Supersymmetry is neither necessary nor sufficient for the existence of these finite QFTs; though softly but explicitly broken supersymmetry or mis-aligned supersymmetry can be used as a book-keeping device to keep the calculations manageable.) In the current article I shall instead take these three Pauli sum rules as given, assume their exact non-perturbative validity, contrast them with the observed standard model particle physics spectrum, and use them to extract as much model-independent information as possible regarding beyond standard model (BSM) physics.

    ↳ hep-thhep-phPLB(2019)·6 citations
17. 17*

    Axion star collisions with black holes and neutron stars in full 3D numerical relativity

    Katy Clough🇩🇪 · Tim Dietrich🇳🇱 · Jens C. Niemeyer🇩🇪

    Axions are a potential dark matter candidate, which may condense and form self gravitating compact objects, called axion stars (ASs). In this work, we study for the first time head-on collisions of relativistic ASs with black holes (BHs) and neutron stars (NSs). In the case of BH-AS mergers we find that, in general, the largest scalar clouds are produced by mergers of low compactness ASs and spinning BHs. Although in most of the cases which we study the majority of the mass is absorbed by the BH within a short time after the merger, in favourable cases the remaining cloud surrounding the final BH remnant can be as large as 30% of the initial axion star mass, with a bosonic cloud mass of order ~ 0.1 M_BH and peak energy density comparable to that obtained in a superradiant build up. This provides a dynamical mechanism for the formation of long lived scalar hair, which could lead to observable signals in cases where the axion interacts with baryonic matter around the BH, or where it forms the seed of a future superradiant build up in highly spinning cases. Considering NS-AS collisions we find two possible final states (i) a BH surrounded by a (small) scalar cloud, or (ii) a stable NS enveloped in an axion cloud of roughly the same mass as the initial AS. Whilst for low mass ASs the NS is only mildly perturbed by the collision, a larger mass AS gives rise to a massive ejection of baryonic mass from the system, purely due to gravitational effects. Therefore, even in the absence of a direct axion coupling to baryonic matter, NS-AS collisions could give rise to electromagnetic observables in addition to their gravitational wave signatures.

    ↳ gr-qcastro-ph.HEhep-phPRD(2018)·76 citations
18. 18*

    X, Y, Z Search at Belle II

    Elisabetta Prencipe🇩🇪

    Search for exotics has increased importance since the observation of the X(3872), 13 years ago, announced by the Belle Collaboration. The observation of pentaquark states by LHCb, and the Z-charged states observed at Belle and BES III have raised even more the attention to the field. Presently several states are observed that do not fit potential models, and looking for them in different production mechanisms and search for their decay modes it is important, as well as to do precise measurement of their mass, width, lineshape. We shortly report in this note about the plan in searching for exotics at Belle II at KEK (Tsukuba, Japan), that just ended the Phase-II running period, and show the first re-discovery results using 5 pb${}^{-1}$ integrated luminosity.

    ↳ hep-exhep-phEPJ Web Conf.(2019)·1 citation
19. 19*

    Neutron star -- axion star collisions in the light of multi-messenger astronomy

    Tim Dietrich🇳🇱 · Francesca Day🇬🇧 · Katy Clough🇩🇪 · Michael Coughlin🇺🇸 · Jens Niemeyer🇩🇪

    Axions are increasingly favoured as a candidate particle for the dark matter in galaxies, since they satisfy the observational requirements for cold dark matter and are theoretically well motivated. Fluctuations in the axion field give rise to stable localised overdensities known as axion stars, which, for the most massive, compact cases, are potential neutron star mimickers. In principle, there are no fundamental arguments against the multi-messenger observations of GW170817/GRB170817A/AT2017gfo arising from the merger of a neutron star with a neutron star mimicker, rather than from a binary neutron star. To constrain this possibility and better understand the astrophysical signatures of a neutron star--axion star (NSAS) merger, we present in this work a detailed example case of a NSAS merger based on full 3D numerical relativity simulations, and give an overview of the many potential observables - ranging from gravitational waves, to optical and near-infrared electromagnetic signals, radio flares, fast radio bursts, gamma ray bursts, and neutrino emission. We discuss the individual channels and estimate to which distances current and future observatories might be able to detect such a NSAS merger. Such signals could constrain the unknown axion mass and its couplings to standard baryonic matter,thus enhancing our understanding of the dark matter sector of the Universe.

    ↳ astro-ph.HEgr-qchep-phMNRAS(2019)·57 citations
20. 20*

    Anyonic particle-vortex statistics and the nature of dense quark matter

    Aleksey Cherman🇺🇸 · Srimoyee Sen🇺🇸 · Laurence G. Yaffe🇺🇸

    We show that ${\mathbb{Z}}_3$-valued particle-vortex braiding phases are present in high density quark matter. Certain mesonic and baryonic excitations, in the presence of a superfluid vortex, have orbital angular momentum quantized in units of $\hslash /3$. Such non-local topological features can distinguish phases whose realizations of global symmetries, as probed by local order parameters, are identical. If ${\mathbb{Z}}_3$ braiding phases and angular momentum fractionalization are absent in lower density hadronic matter, as is widely expected, then the quark matter and hadronic matter regimes of dense QCD must be separated by at least one phase transition.

    ↳ hep-thhep-phnucl-thPRD(2019)·63 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.