Wed·Feb 27, 2019Wednesday·February 27, 2019

1. 01*

   Mesons with Beauty and Charm: New Horizons in Spectroscopy

   Estia J. Eichten🇺🇸 · Chris Quigg🇺🇸

   The $B_c^{+}$ family of $(c\bar{b})$ mesons with beauty and charm is of special interest among heavy quarkonium systems. The $B_c^{+}$ mesons are intermediate between $(c\bar{c})$ and $(b\bar{b})$ states both in mass and size, so many features of the $(c\bar{b})$ spectrum can be inferred from what we know of the charmonium and bottomonium systems. The unequal quark masses mean that the dynamics may be richer than a simple interpolation would imply, in part because the charmed quark moves faster in $B_c$ than in the $J/\psi$. Close examination of the $B_c^{+}$ spectrum can test our understanding of the interactions between heavy quarks and antiquarks and may reveal where approximations break down. ...

   hep-phPRD(2019)·96 citations
2. 02*

   Particlization with local event-by-event conservation laws

   Dmytro Oliinychenko🇺🇸 · Volker Koch🇺🇸

   We present a sampling method for the transition from relativistic hydrodynamics to particle transport, commonly referred to as particlization, which preserves the local event-by-event conservation of energy, momentum, baryon number, strangeness, and electric charge. The proposed method is essential for studying fluctuations and correlations by means of stochastic hydrodynamics. It is also useful for studying small systems. The method is based on Metropolis sampling applied to particles within distinct patches of the hypersurface, where hydrodynamics and kinetic evolutions are matched.

   hep-phnucl-thPRL(2019)·55 citations
3. 03*

   Few-body insights of multiquark exotic hadrons

   Javier Vijande🇪🇸 · Jean-Marc Richard🇫🇷 · Alfredo Valcarce🇪🇸

   In this contribution we discuss the adequate treatment of the $4-$ and $5-$body dynamics within a constituent quark framework. We stress that the variational and Born-Oppenheimer approximations give energies rather close to the exact ones, while the diquark approximation might be rather misleading. Hall-Post inequalities provide very useful lower bounds that exclude possible stable states for some mass ratios and color wave functions.

   hep-phSpringer Proc.Phys.(2020)·3 citations
4. 04*

   The top-quark polarization beyond the Standard Model in electron-positron annihilation

   I.V. Truten🇺🇦 · A.Yu. Korchin🇺🇦

   Electron-positron annihilation into a pair of top quarks is considered at the energy of the future collider CLIC. Polarization components of the top quark are calculated with the $\gamma t\bar{t}$ and $Zt\bar{t}$ interactions which follow from the Lagrangian of the effective field theory of the Standard Model. The polarization vector as a function of the scattering angle is calculated and averaged components of polarization are analyzed as functions of anomalous coupling constants. Extrema of these observables (maxima, minima and saddle points) are studied as functions of the $e^{+}{e}^{-}$ energy.

   hep-phInt.J.Mod.Phys.A(2019)·5 citations
5. 05*

   The Machine Learning Landscape of Top Taggers

   G. Kasieczka (ed)🇩🇪 · T. Plehn (ed)🇩🇪 · A. Butter🇩🇪 · K. Cranmer🇺🇸 · D. Debnath🇺🇸 · B. M. Dillon🇸🇮 · M. Fairbairn🇬🇧 · D. A. Faroughy🇸🇮 · W. Fedorko🇨🇦 · C. Gay🇨🇦 · L. Gouskos🇺🇸 · J. F. Kamenik🇸🇮 and 15 other authors

   Based on the established task of identifying boosted, hadronically decaying top quarks, we compare a wide range of modern machine learning approaches. Unlike most established methods they rely on low-level input, for instance calorimeter output. While their network architectures are vastly different, their performance is comparatively similar. In general, we find that these new approaches are extremely powerful and great fun.

   hep-phSciPost Phys.(2019)·297 citations
6. 06*

   A chiral gauge-invariant model for Majorana neutrinos

   I. Alikhanov🇷🇺 · E. A. Paschos🇩🇪

   The article investigates the possibility that right-handed neutrinos are Majorana particles embedded in an abelian multiplicative $U(1{)}_R$ factor, with the Lagrangian in the new factor being invariant under chiral gauge transformations. Majorana neutrinos couple to charged and neutral currents, producing new signatures to (anti)neutrino-electron elastic scattering and an additional term to coherent scattering of neutrinos on atomic nuclei. The model is ultraviolet complete and depends on one extra hypercharge correlating the reactions and providing upper bounds for the new coupling constant.

   hep-ph5 citations
7. 07*

   Elliptic polylogarithms and Feynman parameter integrals

   Johannes Broedel🇩🇪 · Claude Duhr🇨🇭 · Falko Dulat🇺🇸 · Brenda Penante🇨🇭 · Lorenzo Tancredi🇨🇭

   In this paper we study the calculation of multiloop Feynman integrals that cannot be expressed in terms of multiple polylogarithms. We show in detail how certain types of two- and three-point functions at two loops, which appear in the calculation of higher order corrections in QED, QCD and in the electroweak theory (EW), can naturally be expressed in terms of a recently introduced elliptic generalisation of multiple polylogarithms by direct integration over their Feynman parameter representation. Moreover, we show that in all examples that we considered a basis of pure Feynman integrals can be found.

   hep-phhep-thJHEP(2019)·112 citations
8. 08*

   The Puzzle of Muons in Extensive Air Showers

   Maciej Rybczynski🇵🇱 · Zbigniew Wlodarczyk🇵🇱

   In order to examine a muon excess observed by the Pierre Auger Observatory, detailed Monte Carlo simulations were carried out for primary protons, iron nuclei and strangelets (hypothetical stable lumps of strange quark matter). We obtained a rough agreement between the simulations and the data for ordinary nuclei without any contribution of strangelets in primary flux of cosmic rays. Our simulations suggest that the shower observables are dominated by details of hadronic interaction models.

   hep-phastro-ph.HEInt.J.Mod.Phys.D(2019)·3 citations
9. 09*

   Beyond the Standard Model physics at CLIC

   Roberto Franceschini🇮🇹

   A summary of the recent results from CERN Yellow Report on the CLIC potential for new physics is presented, with emphasis on the direct search for new physics scenarios motivated by the open issues of the Standard Model.

   hep-phhep-exInt.J.Mod.Phys.A(2020)·31 citations
10. 10*

    Probing strong dynamics with cosmic neutrinos

    Luis A. Anchordoqui🇺🇸 · Carlos Garcia Canal🇦🇷 · Jorge F. Soriano🇺🇸

    IceCube has observed 80 astrophysical neutrino candidates in the energy range 0.02 < E_\nu/PeV < 2. Deep inelastic scattering of these neutrinos with nucleons on Antarctic ice sheet probe center-of-mass energies $\sqrt{s}\sim$ 1 TeV. By comparing the rates for two classes of observable events, any departure from the benchmark (perturbative QCD) neutrino-nucleon cross section can be constrained. Using the projected sensitivity of South Pole next generation neutrino telescope we show that this facility will provide a unique probe of strong interaction dynamics. In particular, we demonstrate that the high-energy high-statistics data sample to be recorded by IceCube-Gen2 in the very near future will deliver a direct measurement of the neutrino-nucleon cross section at $\sqrt{s}\sim 1$ TeV, with a precision comparable to perturbative QCD informed by HERA data. We also use IceCube data to extract the neutrino-nucleon cross section at $\sqrt{s}\sim 1$ TeV through a likelihood analysis, considering (for the first time) both the charged-current and neutral-current contributions as free parameters of the likelihood function.

    hep-phastro-ph.HEPRD(2019)·16 citations
11. 11*

    Preheating in Palatini Higgs inflation

    Javier Rubio🇫🇮 · Eemeli S. Tomberg🇫🇮

    We study the details of preheating in Palatini Higgs inflation. We show, that contrary to what happens in the metric formulation of the model, the Universe does not reheat through the creation of gauge bosons only, but also through the tachyonic production of Higgs excitations. The latest entropy production channel turns out to be very efficient and leads to an almost instantaneous onset of radiation domination after the end of inflation. As compared to the metric case, this reduces the number of e-folds needed to solve the usual hot big bang problems while leading to a smaller spectral index for the primordial spectrum of density perturbations.

    hep-phastro-ph.COgr-qcJCAP(2019)·138 citations
12. 12*

    Quark mass dependence of ${\gamma }^{\ast }\pi \to \pi \pi$

    Malwin Niehus🇩🇪 · Martin Hoferichter🇺🇸 · Bastian Kubis🇩🇪

    Usually the simulation of scattering processes in lattice QCD is carried out at unphysically high values of the quark masses. Hence, a method to extrapolate data obtained in lattice calculations to physical masses is needed to allow for comparison between theory and experiment. To obtain a sound extrapolation, dispersion relations and chiral perturbation theory can be invoked. While a simple combined approach known as the inverse amplitude method allows for a successful extrapolation of $\pi \pi \to \pi \pi$ data, a more complicated framework is needed for inelastic processes such as ${\gamma }^{\ast }\pi \to \pi \pi$. By employing a well-established dispersive description, the extrapolation can be performed for ${\gamma }^{\ast }\pi \to \pi \pi$ both for on-shell as well as virtual photons, the decay ${\gamma }^{\ast }\to \pi \pi \pi$ is also within the range of applicability. This particular process is interesting due to both its contribution to the anomalous magnetic moment of the muon and its connection to the axial anomaly.

    hep-phhep-latnucl-thPoS(2019)·13 citations
13. 13*

    Searching new physics in rare $B$-meson decays into multiple muons

    Mikael Chala🇬🇧 · Ulrik Egede🇬🇧 · Michael Spannowsky🇬🇧

    New heavy vector bosons and light scalars are predicted in a plethora of models of new physics. In particular, in new strongly interacting sectors they play the role of the $\rho$ and $\pi$ mesons in QCD. We show that some of their interactions, for example those required for the explanation of the $B$ anomalies and the $g-2$ of the muon, can be only probed in $B$ meson decays. We highlight new golden channels not yet studied experimentally, including $B^{+}\to K^{+}(D^{+}){\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ and $B^0\to K^{\ast 0}{\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$. Relying on generator level simulations for data taking with the LHCb detector, we determine the reach of this facility to the aforementioned processes. We show that branching ratios as small as $9\times 10^{-12}$ ($3.2\times 10^{-10}$) and $2.7\times 10^{-11}$ can be tested at the $95\%$ CL respectively.

    hep-phhep-exEPJC(2019)·17 citations
14. 14*

    Stochastic Particle Production in a de Sitter Background

    Marcos A. G. Garcia🇺🇸 · Mustafa A. Amin🇺🇸 · Scott G. Carlsten🇺🇸 · Daniel Green🇺🇸

    We explore non-adiabatic particle production in a de Sitter universe for a scalar spectator field, by allowing the effective mass $m^2(t)$ of this field and the cosmic time interval between non-adiabatic events to vary stochastically. Two main scenarios are considered depending on the (non-stochastic) mass $M$ of the spectator field: the conformal case with $M^2=2H^2$, and the case of a massless field. We make use of the transfer matrix formalism to parametrize the evolution of the system in terms of the "occupation number", and two phases associated with the transfer matrix; these are used to construct the evolution of the spectator field. Assuming short-time interactions approximated by Dirac-delta functions, we numerically track the change of these parameters and the field in all regimes: sub- and super-horizon with weak and strong scattering. In all cases a log-normally distributed field amplitude is observed, and the logarithm of the field amplitude approximately satisfies the properties of a Wiener process outside the horizon. We derive a Fokker-Planck equation for the evolution of the transfer matrix parameters, which allows us to calculate analytically non-trivial distributions and moments in the weak-scattering limit.

    ↳ astro-ph.COhep-phhep-thJCAP(2019)·15 citations
15. 15*

    Influence functionals, decoherence and conformally coupled scalars

    Clare Burrage🇬🇧 · Christian Käding🇬🇧 · Peter Millington🇬🇧 · Jiří Minář🇳🇱

    Some of the simplest modifications to general relativity involve the coupling of additional scalar fields to the scalar curvature. By making a Weyl rescaling of the metric, these theories can be mapped to Einstein gravity with the additional scalar fields instead being coupled universally to matter. The resulting couplings to matter give rise to scalar fifth forces, which can evade the stringent constraints from local tests of gravity by means of so-called screening mechanisms. In this talk, we derive evolution equations for the matrix elements of the reduced density operator of a toy matter sector by means of the Feynman-Vernon influence functional. In particular, we employ a novel approach akin to the LSZ reduction more familiar to scattering-matrix theory. The resulting equations allow the analysis, for instance, of decoherence induced in atom-interferometry experiments by these classes of modified theories of gravity.

    ↳ hep-thastro-ph.COgr-qchep-ph+1J.Phys.Conf.Ser.(2019)·20 citations
16. 16*

    Are starburst galaxies a common source of high energy neutrinos and cosmic rays?

    Cecilia Lunardini🇺🇸 · Gregory S. Vance🇺🇸 · Kimberly L. Emig🇳🇱 · Rogier A. Windhorst🇺🇸

    A recent analysis of cosmic ray air showers observed at the Pierre Auger Observatory indicates that nearby starburst galaxies (SBGs) might be the cause of ~10% of the Ultra-High-Energy Cosmic Ray flux at energies E > 39 EeV. Since high energy neutrinos are a direct product of cosmic ray interactions, we investigate SBGs as a possible source of some of the ~ 10^-2 - 1 PeV neutrinos observed at IceCube. A statistical analysis is performed to establish the degree of positional correlation between the observed neutrinos and a set of 45 nearby radio- and infrared-bright SBGs. Our results are consistent with no causal correlation. However, a scenario where ~10% of the High Energy Starting Events (HESE) in the detector are coming from the candidate SBGs is not excluded. The same conclusion is reached for different data subsets, as well as two different subsets of SBGs motivated by the Pierre Auger Observatory analysis.

    ↳ astro-ph.HEhep-phJCAP(2019)·50 citations
17. 17*

    Prehistory of Neutrino Oscillations

    S.M. Bilenky🇷🇺

    First ideas of neutrino masses, mixing and oscillations proposed by Bruno Pontecorvo in 1957 and later development of these ideas are considered in some details. Original ideas of the two-neutrino mixing proposed by Maki, Nakagawa and Sakata in 1962 are also discussed.

    ↳ physics.hist-phhep-ph9 citations
18. 18*

    Open problems on classical de Sitter solutions

    David Andriot🇨🇭

    Classical 10d string backgrounds with a 4d de Sitter space-time, D-brane and orientifold sources, are commonly believed to satisfy the following: 1. There is no classical de Sitter solution with parallel sources. 2. Classical de Sitter solutions with intersecting sources are unstable. 3. Classical de Sitter solutions cannot have at the same time a large internal volume, a small string coupling, a bounded number of orientifolds and quantized fluxes. These three conjectures are of particular relevance to the swampland program, and if true, they challenge the connection of string theory to cosmology. We restrict here to a standard solution ansatz for which the problem is well-defined, and we still fail to prove analytically any of these conjectures. While developing new tools and obtaining new constraints, we identify remaining corners of parameter space where counter-examples to these conjectures could be found.

    ↳ hep-thastro-ph.COgr-qchep-ph+1Fortsch.Phys.(2019)·96 citations
19. 19*

    High-redshift Mini-haloes from Modulated Preheating

    Zhiqi Huang🇨🇳

    Intermittent type of primordial non-Gaussian fluctuations from modulated preheating can produce an overabundance of $\sim 10^8{M}_{\odot }$ mini-haloes at high redshift $z\gtrsim 20$. This may have a significant impact on the formation of high-redshift supermassive black holes.

    ↳ astro-ph.COgr-qchep-phPRD(2019)·5 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.