Mon·Jan 15, 2018Monday·January 15, 2018

1. 01*

   The non-triviality of the vacuum in light-front quantization: An elementary treatment

   John Collins🇺🇸

   It is often stated that the vacuum is trivial when light-front (null-plane) quantization is applied to a quantum field theory, in contrast to the situation with equal-time quantization. In fact, it is has long been known that the statement is false, and that in certain cases the standard rules for light-front perturbation theory need modification. This paper gives an elementary review of these issues, including an explanation of how and when there is a failure of the elementary derivation of the rules for light-front perturbation theory.

   hep-phhep-th42 citations
2. 02*

   Connecting Particle Physics and Cosmology: Measuring the Dark Matter Relic Density in Compressed Supersymmetry at the LHC

   Carlos Ávila🇨🇴 · Andrés Flórez🇨🇴 · Alfredo Gurrola🇺🇸 · Dale Julson🇺🇸 · Savanna Starko🇺🇸

   The identity of Dark Matter (DM) is one of the most captivating topics in particle physics today. The R-parity conserving Minimal Supersymmetric Standard Model (MSSM), which naturally provides a DM candidate in the form of the lightest neutralino (${\tilde{\chi }}_1^0$), is used as a benchmark scenario to show that a measurement of ${\Omega }_{{\tilde{\chi }}_1^0}{h}^2$ can be achieved from measurements at the CERN Large Hadron Collider. Focus is placed on compressed mass spectra regions, where the mass difference between the ${\tilde{\chi }}_1^0$ and the ${\tilde{\tau }}_1$ is small and where the ${\tilde{\tau }}_1$-${\tilde{\chi }}_1^0$ coannihilation (CA) mechanism of the early Universe plays an important role. The technique for measuring ${\Omega }_{{\tilde{\chi }}_1^0}{h}^2$ relies on two proposed searches for compressed Supersymmetry (SUSY): 1) production via Vector Boson Fusion (VBF) processes; and 2) production with associated energetic jets from initial state radiation (ISR). These approaches allow for the determination of the relic abundance at the LHC for any model where CA is an important DM reduction mechanism in the early Universe. Thus, it is possible to confirm that the DM we observe today were ${\tilde{\chi }}_1^0$'s created in the early Universe. We show that from measurements in the VBF and ISR SUSY searches at the LHC, the dark matter relic density can be measured with an uncertainty of 25\% with 3000 fb${}^{-1}$ of 13 TeV proton-proton data.

   hep-phPhys.Dark Univ.(2020)·11 citations
3. 03*

   Extraction of neutrino mixing parameters from experiments with multiple identical detectors

   Fu-Guang Cao🇳🇿 · William S. Marks🇳🇿

   The statistical method used in the analyses of measurements of neutrino oscillation mixing angle ${\theta }_{13}$ by the Daya Bay Collaboration is based on variational minimization of a ${\chi }^2$ function defined in terms of quantities of interest and pull factors which are introduced to deal with effects of systematic uncertainties. For both experiments, the number of parameters that need to be determined is great than the number of available data points (20 vs 6 for the Daya Bay and 12 vs 2 for the RENO). While the results for the mixing angle and the normalization factor were reported, results for the other parameters (pull factors) were omitted in their publications. There exist multiple sets of parameters from the minimization of the ${\chi }^2$ function. We investigate the sensitivity of the extracted mixing angle on this non-uniqueness of minimization results for the Daya Bay data using two methods of minimization. We report results for all parameters, including those of physics interest and pull factors. The obtained results for the mixing angle and the normalization factor are in agreement with those reported by the Daya Bay Collaboration. Furthermore, we present plots of confidence level contours in the space of the mixing angle and normalization factor. We also present results from fittings using a reduced ${\chi }^2$ function with fewer parameters than the one employed by the Daya Bay Collaboration.

   hep-phhep-exInt.J.Mod.Phys.A(2018)·0 citations
4. 04*

   Singlet fermionic dark matter with Veltman conditions

   Yeong Gyun Kim🇰🇷 · Kang Young Lee🇰🇷 · Soo-hyeon Nam🇰🇷

   We reexamine a renormalizable model of a fermionic dark matter with a gauge singlet Dirac fermion and a real singlet scalar which can ameliorate the scalar mass hierarchy problem of the Standard Model (SM). Our model setup is the minimal extension of the SM for which a realistic dark matter (DM) candidate is provided and the cancellation of one-loop quadratic divergence to the scalar masses can be achieved by the Veltman condition (VC) simultaneously. This model extension, although renormalizable, can be considered as an effective low-energy theory valid up to cut-off energies about 10 TeV. We calculate the one-loop quadratic divergence contributions of the new scalar and fermionic DM singlets, and constrain the model parameters using the VC and the perturbative unitarity conditions. Taking into account the invisible Higgs decay measurement, we show the allowed region of new physics parameters satisfying the recent measurement of relic abundance. With the obtained parameter set, we predict the elastic scattering cross section of the new singlet fermion into target nuclei for a direct detection of the dark matter. We also perform the full analysis with arbitrary set of parameters without the VC as a comparison, and discuss the implication of the constraints by the VC in detail.

   hep-phhep-exPLB(2018)·11 citations
5. 05*

   Boosted Top Tagging Method Overview

   Gregor Kasieczka🇩🇪

   We briefly review common tools and methods to identify boosted, hadronically decaying top quarks at the LHC experiments. This includes generic jet substructure variables, specific top identification algorithms, and recent developments in deep learning techniques.

   hep-ph7 citations
6. 06*

   Vector boson scattering: Recent experimental and theory developments

   C.F. Anders (1)🇩🇪 · A. Ballestrero (2) · J. Balz (3)🇩🇪 · R. Bellan (4)🇮🇹 · B. Biedermann (5)🇩🇪 · C. Bittrich (6)🇩🇪 · S. Braß (7)🇩🇪 · I. Brivio (8)🇩🇰 · L.S. Bruni (9)🇳🇱 · J. Butterworth (10)🇺🇸 · M. Cacciari (11)🇫🇷 · A. Cardini (12)🇮🇹 and 102 other authors

   This document summarises the talks and discussions happened during the VBSCan Split17 workshop, the first general meeting of the VBSCan COST Action network. This collaboration is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

   hep-phhep-exRev.Phys.(2018)·52 citations
7. 07*

   NA62 sensitivity to heavy neutral leptons in the low scale seesaw model

   Marco Drewes🇧🇪 · Jan Hajer🇧🇪 · Juraj Klaric🇩🇪 · Gaia Lanfranchi🇮🇹

   The sensitivity of beam dump experiments to heavy neutral leptons depends on the relative strength of their couplings to individual lepton flavours in the Standard Model. We study the impact of present neutrino oscillation data on these couplings in the minimal type I seesaw model and find that it significantly constrains the allowed heavy neutrino flavour mixing patterns. We estimate the effect that the DUNE experiment will have on these predictions. We then discuss implication that this has for the sensitivity of the NA62 experiment when operated in the beam dump mode and provide sensitivity estimates for different benchmark scenarios. We find that the sensitivity can vary by almost two orders of magnitude for general choices of the model parameters, but depends only weakly on the flavour mixing pattern within the parameter range that is preferred by neutrino oscillation data.

   hep-phhep-exJHEP(2018)·129 citations
8. 08*

   Weak mixing below the weak scale in dark-matter direct detection

   Joachim Brod🇩🇪 · Benjamin Grinstein🇺🇸 · Emmanuel Stamou🇺🇸 · Jure Zupan🇺🇸

   If dark matter couples predominantly to the axial-vector currents with heavy quarks, the leading contribution to dark-matter scattering on nuclei is either due to one-loop weak corrections or due to the heavy-quark axial charges of the nucleons. We calculate the effects of Higgs and weak gauge-boson exchanges for dark matter coupling to heavy-quark axial-vector currents in an effective theory below the weak scale. By explicit computation, we show that the leading-logarithmic QCD corrections are important, and thus resum them to all orders using the renormalization group.

   hep-phJHEP(2018)·15 citations
9. 09*

   Revisiting scalar leptoquark at the LHC

   Priyotosh Bandyopadhyay🇮🇳 · Rusa Mandal🇮🇳

   We investigate the Standard Model (SM) extended with a colored charged scalar, leptoquark, having fractional electromagnetic charge $-1/3$. We mostly focus on the decays of the leptoquark into second and third generations via $c\mu ,t\tau$ decay modes. We perform a PYTHIA-based simulation considering all the dominant SM backgrounds at the LHC with 14\,TeV center of mass energy. Limits have been calculated for the leptoquark mass that can be probed at the LHC with an integrated luminosity of 3000 fb${}^{-1}$. The leptoquark mass, reconstructed from its decay products into the third generation, has the maximum reach. However, the $\mu +c$ channel, comprising a very hard muon and $c$-jet produces a much cleaner mass peak. Single leptoquark production in association with a $\mu$ or $\nu$ provides some unique signatures that can also be probed at the LHC.

   hep-phEPJC(2018)·47 citations
10. 10*

    Higgs Inflation at the LC

    W. G. Hollik🇩🇪

    Most cosmological models of inflation are far away from providing a smoking gun at low energies. A model of Higgs inflation in the Next-to-Minimal Supersymmetric Standard Model, however, changes the NMSSM phenomenology drastically and may be well distinguished from the pure NMSSM or MSSM at a future Linear Collider. We point out certain differences of the inflationary model to the ordinary NMSSM and discuss the Higgs and neutralino/chargino sector in particular to identify the smoking gun of inflation at electroweak energies.

    hep-ph2 citations
11. 11*

    Understanding the Impact of Pythia Hadronization in Top Quark Mass Determinations at the LHC

    Doojin Kim🇨🇭

    Most of the methods to measure the top quark mass suffer from the jet energy scaling in achieving better precision. As a way to circumvent this issue, the study of $B$-hadron observables is motivated. While they do not involve such an issue, understanding underlying hadronization models is a key to achieve $\sim 0.5\%$ precision or better. In this presentation, we discuss the impact of the hadronization model parameters - for example, implemented in Pythia 8 - on precision measurements of the top quark mass through $B$-hadron observables. We study the sensitivity of the top quark mass to relevant hadronization and showering parameters, followed by a discussion on observables to be used for constraining the hadronization and showering parameters.

    hep-ph0 citations
12. 12*

    Absolute stability window and upper bound on the magnetic field strength in a strongly magnetized strange quark star

    A. A. Isayev🇺🇦

    Magnetized strange quark stars, composed of strange quark matter (SQM) and self-bound by strong interactions, can be formed if the energy per baryon of magnetized SQM is less than that of the most stable ${}^{56}$Fe nucleus under the zero external pressure and temperature. Utilizing the MIT bag model description of magnetized SQM under charge neutrality and beta equilibrium conditions, the corresponding absolute stability window in the parameter space of the theory is determined. It is shown that there exists the maximum magnetic field strength allowed by the condition of absolute stability of magnetized SQM. The value of this field, $H\sim 3\cdot 10^{18}$ G, represents the upper bound on the magnetic field strength which can be reached in a strongly magnetized strange quark star.

    hep-phastro-ph.HEInt.J.Mod.Phys.A(2014)·7 citations
13. 13*

    Noncommutative Black Holes at the LHC

    Elena Villhauer🇺🇸

    Based on the latest public results, 13 TeV data from the Large Hadron Collider at CERN has not indicated any evidence of hitherto tested models of quantum black holes, semiclassical black holes, or string balls. Such models have predicted signatures of particles with high transverse momenta. Noncommutative black holes remain an untested model of TeV- scale gravity that offers the starkly different signature of particles with relatively low transverse momenta. Considerations for a search for charged noncommutative black holes using the ATLAS detector will be discussed.

    hep-phhep-exJ.Phys.Conf.Ser.(2017)·1 citation
14. 14*

    UV self-completion of a theory of Superfluid Dark Matter

    Andrea Addazi🇨🇳 · Antonino Marciano🇨🇳

    We show that the model of superfluid dark matter developed in Refs.~\cite{Khoury:2014tka,Berezhiani:2015bqa,Berezhiani:2015pia}, which modifies the Newtonian potential and explains the galactic rotational curves, can be unitarized by the formation of classical configurations in the scattering amplitudes. The classicalization mechanism may also trigger the formation of the superfluid state from the early to the late Universe.

    ↳ hep-thgr-qchep-phEPJC(2019)·12 citations
15. 15*

    Spiked Monopoles

    Jarah Evslin🇨🇳

    We introduce the spiked monopole, which is a 't Hooft-Polyakov monopole with two charged scalar Higgs fields, of which one enjoys a quartic self-interaction. The free Higgs field behaves as in a BPS monopole, reducing the inter-monopole repulsion. The other Higgs has a spiked profile similar to a non-BPS monopole. Using the methods from numerical relativity recently adapted to the Yang-Mills-Higgs theory by Vachaspati, we simulate the interactions of such monopoles. During the long lifetime of these simulations the individual monopoles are stable. We find that they are always repulsive, with a small repulsion only when the interaction Higgs VEV is proportionately small. We briefly comment on implications for giant monopole dark matter models and on supermassive black hole seeding by the spikes.

    ↳ hep-thhep-phJHEP(2018)·4 citations
16. 16*

    Hadronic light-by-light scattering contribution to the muon g-2 on the lattice

    Nils Asmussen🇩🇪 · Antoine Gerardin🇩🇪 · Jeremy Green🇩🇪 · Oleksii Gryniuk🇩🇪 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Andreas Nyffeler🇩🇪 · Vladimir Pascalutsa🇩🇪 · Hartmut Wittig🇩🇪

    We briefly review several activities at Mainz related to hadronic light-by-light scattering (HLbL) using lattice QCD. First we present a position-space approach to the HLbL contribution in the muon g-2, where we focus on exploratory studies of the pion-pole contribution in a simple model and the lepton loop in QED in the continuum and in infinite volume. The second part describes a lattice calculation of the double-virtual pion transition form factor F_{pi^0 gamma^* gamma^*}(q_1^2, q_2^2) in the spacelike region with photon virtualities up to 1.5 GeV^2 which paves the way for a lattice calculation of the pion-pole contribution to HLbL. The third topic involves HLbL forward scattering amplitudes calculated in lattice QCD which can be described, using dispersion relations (HLbL sum rules), by gamma^* gamma^* -> hadrons fusion cross sections and then compared with phenomenological models.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·24 citations
17. 17*

    Cosmological Backgrounds of Gravitational Waves

    Chiara Caprini🇫🇷 · Daniel G. Figueroa🇨🇭

    Gravitational waves (GWs) have a great potential to probe cosmology. We review early universe sources that can lead to cosmological backgrounds of GWs. We begin by presenting definitions of GWs in flat space-time and in a cosmological setting, and discussing the reasons why GW backgrounds from the early universe are of a stochastic nature. We recap current observational constraints on stochastic backgrounds, and discuss some of the characteristics of present and future GW detectors including advanced LIGO, advanced Virgo, the Einstein Telescope, KAGRA, LISA. We then review in detail early universe GW generation mechanisms proposed in the literature, as well as the properties of the GW backgrounds they give rise to. We classify the backgrounds in five categories: GWs from quantum vacuum fluctuations during standard slow-roll inflation, GWs from processes that operate within extensions of the standard inflationary paradigm, GWs from post-inflationary preheating and related non-perturbative phenomena, GWs from first order phase transitions (related or not to the electroweak symmetry breaking), and GWs from topological defects, in particular from cosmic strings. The phenomenology of early universe processes that can generate a stochastic background of GWs is extremely rich, and some backgrounds are within the reach of near-future GW detectors. A future detection of any of these backgrounds will provide crucial information on the underlying high energy theory describing the early universe, probing energy scales well beyond the reach of particle accelerators.

    ↳ astro-ph.COgr-qchep-phClass.Quant.Grav.(2018)·1303 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.