Thu·Aug 3, 2017Thursday·August 3, 2017

1. 01*

   Gluon-fusion Higgs production in the Standard Model Effective Field Theory

   Nicolas Deutschmann🇧🇪 · Claude Duhr🇨🇭 · Fabio Maltoni🇧🇪 · Eleni Vryonidou🇳🇱

   We provide the complete set of predictions needed to achieve NLO accuracy in the Standard Model Effective Field Theory at dimension six for Higgs production in gluon fusion. In particular, we compute for the first time the contribution of the chromomagnetic operator ${\bar{Q}}_L\Phi \sigma q_{R}G$ at NLO in QCD, which entails two-loop virtual and one-loop real contributions, as well as renormalisation and mixing with the Yukawa operator ${\Phi }^{†}\Phi {\bar{Q}}_L\Phi q_R$ and the gluon-fusion operator ${\Phi }^{†}\Phi GG$. Focusing on the top-quark-Higgs couplings, we consider the phenomenological impact of the NLO corrections in constraining the three relevant operators by implementing the results into the MadGraph5_aMC@NLO framework. This allows us to compute total cross sections as well as to perform event generation at NLO that can be directly employed in experimental analyses.

   hep-phJHEP(2017)·69 citations
2. 02*

   Bulk Viscosity of Quark-Gluon Plasma in Strong Magnetic Fields

   Koichi Hattori🇨🇳 · Xu-Guang Huang🇨🇳 · Dirk H. Rischke🇩🇪 · Daisuke Satow🇩🇪

   We investigate the viscosities of the quark-gluon plasma in strong magnetic fields within the leading-log and lowest Landau level (LLL) approximations. We first show that the bulk viscosity in the direction parallel to the magnetic field is the only component that has a contribution from the quarks occupying the LLL. We then compute the bulk viscosity from the Kubo formula and find an intriguing quark-mass dependence as a consequence of a competition between the suppression of the bulk viscosity by conformal symmetry and an enhancement of the mean-free path by chirality conservation, which governs the behavior in the massless limit. The quark contribution to the viscosity along the magnetic field becomes larger than the one in the absence of a magnetic field. We also briefly estimate the other transport coefficients by considering the contribution of gluons. We show that the shear viscosities are suppressed compared to their values in the absence of a magnetic field.

   hep-phnucl-thPRD(2017)·89 citations
3. 03*

   Low-energy meson phenomenology with Resonance Chiral Lagrangians

   Adolfo Guevara🇲🇽

   The low energy behaviour of Quantum Chromodynamics makes unreliable an expansion in terms of its coupling strength, since nothing guarantees the convergence of such expansion. To overcomer such difficulty one resorts to Lattice QCD or Effective Field Theories. In this thesis we compute hadronic processes at low energies, using Resonance Chiral Lagrangians as the effective theory of QCD. The processes we study are important background on the search for Lepton Flavor Violation, Lepton Universality Violation, Lepton Number Violation, Second Class Currents and study the Hadronic light-by-light contribution to the Anomalous Magnetic Moment of the muon. All such processes are of great interest since all of them are to be studied with an increased precision in the very near future by different experiments.

   hep-ph4 citations
4. 04*

   Lambda beta-decay in-medium

   P.A.M. Guichon🇫🇷 · A.W. Thomas🇦🇺

   Under the working hypothesis that the structure of a bound hadron is modified by its interactions with other hadrons, one may expect to see changes in carefully chosen observables. In the light of a recent proposal to measure the axial charge in the strangeness changing beta-decay of a bound Lambda hyperon, we examine the size of the change expected within the quark-meson coupling model. It is predicted to be significant.

   hep-phnucl-thPLB(2017)·6 citations
5. 05*

   Interacting dyon ensemble and confinement by particle mesh Ewald's method

   Motahareh Kiamari🇮🇷 · Sedigheh Deldar (University of Tehran)🇮🇷

   The free energy of a static quark-antiquark pair is obtained in an interacting dyon ensemble near the deconfinement temperature. Comparing the results with the noninteracting case, we observe that the string tension between the quark-antiquark pair increases for the interacting ensemble. As a result, the confinement temperature decreases.

   hep-phPRD(2017)·1 citation
6. 06*

   NLO electroweak corrections to vector-boson scattering at the LHC

   Benedikt Biedermann🇩🇪 · Ansgar Denner🇩🇪 · Mathieu Pellen🇩🇪

   Recently, a measurement of the vector-boson scattering process with same-sign W bosons has been reported by the CMS collaboration. Hence it is of prime importance to have precise predictions with next-to-leading order (NLO) accuracy. In these proceedings, we report on a recent NLO electroweak computation to the full process $\mathrm{p}\mathrm{p}\to {\mu }^{+}{\nu }_{\mu }{\mathrm{e}}^{+}{\nu }_{\mathrm{e}}\mathrm{j}\mathrm{j}$. As realistic experimental event selections are applied to the final state, it can directly be compared with experimental measurements. This is particularly important as the corrections turn out to be surprisingly large and even exceed the NLO QCD corrections. The NLO electroweak predictions are presented at the cross-section and differential distribution level.

   hep-phhep-exPoS(2018)·1 citation
7. 07*

   Decay chain information on the newly discovered double charm baryon state ${\Xi }_{cc}^{++}$

   Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jürgen G. Körner🇩🇪 · Valery E. Lyubovitskij🇩🇪

   We interprete the new double charm baryon state found by the LHCb Collaboration in the invariant mass distribution of the set of final state particles $({\Lambda }_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+})$ as being at the origin of the decay chain ${\Xi }_{cc}^{++}\to {\Sigma }_c^{++}(\to {\Lambda }_c^{+}{\pi }^{+})+{\bar{K}}^{\ast 0}(\to K^{-}{\pi }^{+})$. The nonleptonic decay ${\Xi }_{cc}^{++}\to {\Sigma }_c^{++}+{\bar{K}}^{\ast 0}$ belongs to a class of decays where the quark flavor composition is such that the decay proceeds solely via the factorizing contribution precluding a contamination from internal $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the four helicity amplitudes that describe the dynamics of the transition ${\Xi }_{cc}^{++}\to {\Sigma }_c^{++}$ induced by the effective $(c\to u)$ current. We then proceed to calculate the rate of the decay as well as the polarization of the ${\Sigma }_c^{++}$ and ${\Lambda }_c^{+}$ baryons and the longitudinal/transverse composition of the ${\bar{K}}^{\ast 0}$. We estimate the decay ${\Xi }_{cc}^{++}\to {\Sigma }_c^{++}{\bar{K}}^{\ast 0}$ to have a branching rate of $B({\Xi }_{cc}^{++}\to {\Sigma }_c^{++}{\bar{K}}^{\ast 0})\sim 10.5\%$. As a byproduct of our investigation we have also analyzed the decay ${\Xi }_{cc}^{++}\to {\Sigma }_c^{++}{\bar{K}}^0$ for which we find a branching ratio of $B({\Xi }_{cc}^{++}\to {\Sigma }_c^{++}{\bar{K}}^0)\sim 2.5\%$.

   hep-phPRD(2017)·61 citations
8. 08*

   Spacelike and timelike form factors for the $({\pi }^0,\eta ,{\eta }^{\prime })\to {\gamma }^{\ast }\gamma$ transitions in the light-front quark model

   Ho-Meoyng Choi (1)🇰🇷 · Hui-Young Ryu (2)🇰🇷 · Chueng-Ryong Ji (3) ((1) Kyungpook National Univ., (2) Pusan National Univ., (3) North Carolina State Univ.)🇺🇸

   We investigate the $({\pi }^0,\eta ,{\eta }^{\prime })\to {\gamma }^{\ast }\gamma$ transitions both for the spacelike region and the timelike region using the light-front quark model (LFQM). In particular, we present the new direct method to explore the timelike region without resorting to mere analytic continuation from the spacelike region to the timelike region. Our direct calculation in timelike region shows the complete agreement not only with the analytic continuation result from the spacelike region but also with the result from the dispersion relation between the real and imaginary parts of the form factor. For the low energy regime, we compare our LFQM results of the transition form factors (TFFs) for the low timelike momentum transfer region and the slope parameters at $q^2=0$ with the recent experimental data from the Dalitz decays of $({\pi }^0,\eta ,{\eta }^{\prime })$. For the high energy regime, we incorporate the QCD factorization in our LFQM to examine the asymptotic behavior of TFFs both for the spacelike region and the timelike region. We compare our results with the available experimental data.

   hep-phPRD(2017)·31 citations
9. 09*

   Measuring the neutron star compactness and binding energy with supernova neutrinos

   Andrea Gallo Rosso🇮🇹 · Francesco Vissani🇮🇹 · Maria Cristina Volpe🇫🇷

   We investigate the precision with which a neutron star gravitational binding energy can be measured through the supernova neutrino signal, without assuming any prior such as the energy equipartition hypothesis, mean energies hierarchy or constraints on the pinching parameters that characterize the neutrino spectra. We consider water Cherenkov detectors and prove that combining inverse beta decay with elastic scattering on electrons is sufficient to reach $11\%$ precision on the neutron star gravitational binding energy already with Super-Kamiokande. The inclusion of neutral current events on oxygen in the analysis does not improve the precision further. We show that $3\%$ precision can be achieved if priors are introduced, such as energy equipartition. We discuss the implications of our findings on the properties of the newly formed neutron star, in particular concerning the assessment of the compactness or mass--radius relation.

   hep-phJCAP(2017)·29 citations
10. 10*

    QCD

    E. Laenen🇳🇱

    In these lecture notes I describe the theory of QCD and its application, through perturbation theory, at particle colliders.

    hep-phCERN Yellow Report CERN 2016-003, pp. 1-58·1 citation
11. 11*

    Flavour Physics and CP Violation

    J. F. Kamenik🇸🇮

    These notes represent a summary of three lectures on flavour and CP violation, given at the CERNs European School of High Energy Physics in 2014. They cover flavour physics within the standard model, phenomenology of CP violation in meson mixing and decays, as well as constraints of flavour observableson physics beyond the standard model. In preparing the lectures (and consequently this summary) I drew heavily from several existing excellent and exhaustive sets of lecture notes and reviews on flavour physics and CP violation [1]. The reader is encouraged to consult those as well as the original literature for a more detailed study.

    hep-phCERN Yellow Report CERN 2016-003, pp. 79-…·10 citations
12. 12*

    Introduction to Supersymmetry

    Y. Shadmi🇮🇱

    These lectures are a brief introduction to supersymmetry.

    hep-phCERN Yellow Report CERN 2016-003, pp. 95-…·6 citations
13. 13*

    Higgs Physics

    C. Grojean🇩🇪

    The cause of the screening of the weak interactions at long distances puzzled the high-energy community for more nearly half a century. With the discovery of the Higgs boson a new era started with direct experimental information on the physics behind the breaking of the electroweak symmetry. This breaking plays a fundamental role in our understanding of particle physics and sits at the high-energy frontier beyond which we expect new physics that supersedes the Standard Model. The Higgs boson (inclusive and differential) production and decay rates offer a new way to probe this frontier.

    hep-phCERN Yellow Report CERN 2016-005, pp. 143…·8 citations
14. 14*

    ${ϵ}^{\prime }$ from right-handed currents

    W. Dekens🇺🇸

    Recent lattice determinations of direct CP violation in kaon decays, parametrized by ${ϵ}^{\prime }$, suggest a discrepancy of several sigma between experiment and the standard model. Assuming that this situation is due to new physics, we investigate a solution in terms of right-handed charged currents. Chiral perturbation theory, in combination with lattice QCD results, allows one to accurately determine the effect of right-handed interactions on ${ϵ}^{\prime }$. In addition, similar techniques provide a direct link between the right-handed contributions to ${ϵ}^{\prime }$ and hadronic electric dipole moments. We demonstrate that the ${ϵ}^{\prime }$ discrepancy can be resolved with right-handed charged currents, and that this scenario can be falsified by next-generation hadronic electric dipole moment experiments.

    hep-ph0 citations
15. 15*

    Physics Beyond the Standard Model

    R. Rosenfeld🇧🇷

    In these three lectures I review the need to go beyond the Standard Glashow- Weinberg-Salam Model and discuss some of the approaches that are explored in this direction.

    hep-phCERN Yellow Report CERN 2016-005, pp. 159…·7 citations
16. 16*

    Discovering intermediate mass sterile neutrinos through ${\tau }^{-}\to {\pi }^{-}{\mu }^{-}{e}^{+}\nu$ (or $\bar{\nu }$) decay

    C. S. Kim🇰🇷 · G. López Castro🇲🇽 · Dibyakrupa Sahoo🇰🇷

    Distinguishing the Dirac and Majorana nature of neutrinos remains one of the most important tasks in neutrino physics. By assuming that the ${\tau }^{-}\to {\pi }^{-}{\mu }^{-}{e}^{+}\nu$ (or $\bar{\nu }$) decay is resonantly enhanced by the exchange of an intermediate mass sterile neutrino $N$, we show that the energy spectrum of emitted pions and muons can be used to easily distinguish between the Dirac and Majorana nature of $N$. This method takes advantage of the fact that the flavor of light neutrinos is not identified in the tau decay under consideration. We find that it is particularly advantageous, because of no competing background events, to search for $N$ in the mass range $m_e+m_{\mu }⩽m_N⩽m_{\mu }+m_{\pi }$, where $m_X$ denotes the mass of particle $X\in \{e,\mu ,\pi ,N\}$.

    hep-phPRD(2017)·22 citations
17. 17*

    A case study of quark-gluon discrimination at NNLL' in comparison to parton showers

    Jonathan Mo🇳🇱 · Frank J. Tackmann🇩🇪 · Wouter J. Waalewijn🇳🇱

    Predictions for our ability to distinguish quark and gluon jets vary by more than a factor of two between different parton showers. We study this problem using analytic resummed predictions for the thrust event shape up to NNLL' using $e^{+}{e}^{-}\to Z\to q\bar{q}$ and $e^{+}{e}^{-}\to H\to gg$ as proxies for quark and gluon jets. We account for hadronization effects through a nonperturbative shape function, and include an estimate of both perturbative and hadronization uncertainties. In contrast to previous studies, we find reasonable agreement between our results and predictions from both Pythia and Herwig parton showers. We find that this is due to a noticeable improvement in the description of gluon jets in the newest Herwig 7.1 compared to previous versions.

    hep-phhep-exEPJC(2017)·29 citations
18. 18*

    Improved limits on axion-like-particle-mediated P,T-violating interactions between electrons and nucleons from electric dipole moments of atoms and molecules

    Y. V. Stadnik🇦🇺 · V. A. Dzuba🇦🇺 · V. V. Flambaum🇦🇺

    In the presence of P,T-violating interactions, the exchange of axion-like particles between electrons and nucleons in atoms and molecules induces electric dipole moments (EDMs) of atoms and molecules. We perform calculations of such axion-exchange-induced atomic EDMs using the relativistic Hartree-Fock-Dirac method including electron core polarisation (RPA) corrections. We present analytical estimates to explain the dependence of these induced atomic EDMs on the axion mass and atomic parameters. From the experimental bounds on the EDMs of atoms and molecules, including ${}^{133}$Cs, ${}^{205}$Tl, ${}^{129}$Xe, ${}^{199}$Hg, ${}^{171}$Yb${}^{19}$F, ${}^{180}$Hf${}^{19}$F${}^{+}$ and ${}^{232}$Th${}^{16}$O, we constrain the P,T-violating scalar-pseudoscalar nucleon-electron and electron-electron interactions mediated by a generic axion-like particle of arbitrary mass. Our limits improve on existing laboratory bounds from other experiments by many orders of magnitude for $m_a\gtrsim 10^{-2}\text{eV}$. We also place constraints on CP violation in certain types of relaxion models.

    ↳ physics.atom-phhep-phPRL(2018)·89 citations
19. 19*

    The Casimir-Polder interaction between two neutrons and possible relevance to tetraneutron states

    M. S. Hussein🇧🇷 · J. Babb🇺🇸 · R. Higa🇧🇷

    We present a summary of our recent publication concerning the derivation of the extended Casimir-Polder dispersive interaction between two neutrons. Dynamical polarizations of the neutrons, recently derived within Chiral Effective Theory are used for the purpose. An account of the higher frequency/energy behavior of these entities related to the opening of one-pion production channel and the excitation of the $\Delta$ resonance are taken into consideration in our derivation of the CP interaction. The neutron-neutron system in free space is treated in details so are the neutron-wall and the wall-neutron-wall systems. The case of tetraneutron (a 4 neutron system) in a resonant state is then briefly considered. The 4n CP interaction is evaluated to assess its potential relevance to the ongoing debate concerning the nature of the tetraneutron.

    ↳ nucl-thhep-phnucl-exActa Phys.Polon.B(2017)·2 citations
20. 20*

    Experimental Facilities at the High Energy Frontier

    P. Jenni🇩🇪

    The main theme of the lectures covered the experimental work at hadron colliders, with a clear focus on the Large Hadron Collider (LHC) and on the roadmap that led finally to the discovery of the Higgs boson. The lectures were not a systematic course on machine and detector technologies, but rather tried to give a physics-motivated overview of many experimental aspects that were all relevant for making the discovery. The actual lectures covered a much broader scope than what is documented here in this writeup. The successful concepts for the experiments at the LHC have benefitted from the experience gained with previous generations of detectors at lower-energy machines. The lectures included also an outlook to the future experimental programme at the LHC, with its machine and experiments upgrades, as well as a short discussion of possible facilities at the high energy frontier beyond LHC.

    ↳ hep-exhep-phCERN Yellow Report CERN 2016-005, pp. 213…·0 citations
21. 21*

    Comment on "Acceleration of particles to high energy via gravitational repulsion in the Schwarzschild field" [Astropart. Phys. 86 (2017) 18-20]

    Alessandro D. A. M. Spallicci🇫🇷

    Comments are due on a recent paper by McGruder III (2017) in which the author deals with the concept of gravitational repulsion in the context of the Schwarzschild-Droste solution. Repulsion (deceleration) for ingoing particles into a black hole is a concept proposed several times starting from Droste himself in 1916. It is a coordinate effect appearing to an observer at a remote distance from the black hole and when coordinate time is employed. Repulsion has no bearing and relation to the local physics of the black hole, and moreover it cannot be held responsible for accelerating outgoing particles. Thereby, the energy boost of cosmic rays cannot be produced by repulsion.

    ↳ gr-qcastro-ph.HEhep-phAstropart.Phys.(2017)·4 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.