Fri·Sep 15, 2017Friday·September 15, 2017

1. 01*

   Final-state QED Multipole Radiation in Antenna Parton Showers

   Ronald Kleiss🇳🇱 · Rob Verheyen🇳🇱

   We present a formalism for a fully coherent QED parton shower. The complete multipole structure of photonic radiation is incorporated in a single branching kernel. The regular on-shell 2 to 3 kinematic picture is kept intact by dividing the radiative phase space into sectors, allowing for a definition of the ordering variable that is similar to QCD antenna showers. A modified version of the Sudakov veto algorithm is discussed that increases performance at the cost of the introduction of weighted events. Due to the absence of a soft singularity, the formalism for photon splitting is very similar to the QCD analogon of gluon splitting. However, since no color structure is available to guide the selection of a spectator, a weighted selection procedure from all available spectators is introduced.

   hep-phJHEP(2017)·12 citations
2. 02*

   Low-Energy Effective Field Theory below the Electroweak Scale: Operators and Matching

   Elizabeth E. Jenkins🇺🇸 · Aneesh V. Manohar🇺🇸 · Peter Stoffer🇺🇸

   The gauge-invariant operators up to dimension six in the low-energy effective field theory below the electroweak scale are classified. There are 70 Hermitian dimension-five and 3631 Hermitian dimension-six operators that conserve baryon and lepton number, as well as $\Delta B=\pm \Delta L=\pm 1$, $\Delta L=\pm 2$, and $\Delta L=\pm 4$ operators. The matching onto these operators from the Standard Model Effective Field Theory (SMEFT) up to order $1/{\Lambda }^2$ is computed at tree level. SMEFT imposes constraints on the coefficients of the low-energy effective theory, which can be checked experimentally to determine whether the electroweak gauge symmetry is broken by a single fundamental scalar doublet as in SMEFT. Our results, when combined with the one-loop anomalous dimensions of the low-energy theory and the one-loop anomalous dimensions of SMEFT, allow one to compute the low-energy implications of new physics to leading-log accuracy, and combine them consistently with high-energy LHC constraints.

   hep-phJHEP(2018)·468 citations
3. 03*

   TASI Lectures on Collider Physics

   Matthew D. Schwartz🇺🇸

   These lectures provide an introduction to the physics of particle colliders. Topics covered include a quantitative examination of the design and operational parameters of Large Hadron Collider, kinematics and observables at colliders, such as rapidity and transverse mass, and properties of distributions, such as Jacobian peaks. In addition, the lectures provide a practical introduction to the decay modes and signatures of important composite and elementary and particles in the Standard Model, from pions to the Higgs boson. The aim of these lectures is provide a bridge between theoretical and experimental particle physics. Whenever possible, results are derived using intuitive arguments and estimates rather than precision calculations.

   hep-ph20 citations
4. 04*

   Axion dark matter in a $3-3-1$ model

   J. C. Montero🇧🇷 · Ana R. Romero Castellanos🇧🇷 · B. L. Sánchez-Vega🇧🇷

   Slightly extending a right-handed neutrino version of the $3-3-1$ model, we show that it is not only possible to solve the strong CP problem but also to give the total dark matter abundance reported by the Planck collaboration. Specifically, we consider the possibility of introducing a $3-3-1$ scalar singlet to implement a gravity stable Peccei-Quinn mechanism in this model. Remarkably, for allowed regions of the parameter space, the arising axions with masses $m_a\approx$ meV can both make up the total dark matter relic density through non-thermal production mechanisms and be very close to the region to be explored by the IAXO helioscope.

   hep-phPRD(2018)·32 citations
5. 05*

   Heavy Quarkonium ($1^{--}$) Meson-Hybrid Mixing from QCD Sum Rules

   A. Palameta🇨🇦 · J. Ho🇨🇦 · D. Harnett🇨🇦 · T. G. Steele🇨🇦

   We use QCD Laplace sum-rules to explore mixing between conventional mesons and hybrids in the heavy quarkonium vector $J^{PC}=1^{--}$ channel. Our cross-correlator includes perturbation theory and contributions proportional to the four-dimensional and six-dimensional gluon condensates. We input experimentally determined charmonium and bottomonium hadron masses into both single and multi-resonance models in order to test them for conventional meson and hybrid components. In the charmonium sector we find evidence for meson-hybrid mixing in the $J/\psi$ and a $\approx 4.3$ GeV resonance. In the bottomonium sector, we find that the ${\rm Y}(1S)$, ${\rm Y}(2S)$, ${\rm Y}(3S)$, and ${\rm Y}(4S)$ all exhibit mixing.

   hep-phNucl.Part.Phys.Proc.(2018)·0 citations
6. 06*

   Vacuum of the Standard Model and its Cosmological Aspects

   Ahmad Mohamadnejad🇮🇷

   Recently, we have proposed a definition for the vacuum and suggest a mechanism for symmetry breaking. In this mechanism extra massless fields, vacuum fields, arise. We apply our method to the standard model of particle physics and obtain vacuum sector of this model. Vacuum field of the standard model is a four-vector with electromagnetic nature. This field is invariant under $U(1{)}_{em}$ gauge transformation. We speculate that it could be responsible for many cosmological phenomena like inflation, dark energy and cosmic magnetic fields.

   hep-phastro-ph.COgr-qchep-th1 citation
7. 07*

   Gravity Waves and Gravitino Dark Matter in $\mu$-Hybrid Inflation

   Nobuchika Okada🇺🇸 · Qaisar Shafi🇺🇸

   We propose a novel reformulation of supersymmetric (more precisely $\mu$-) hybrid inflation based on a local U(1) or any suitable extension of the minimal supersymmetric standard model (MSSM) which also resolves the $\mu$ problem. We employ a suitable Kahler potential which effectively yields quartic inflation with non-minimal coupling to gravity. Imposing the gravitino Big Bang Nucleosynthesis (BBN) constraint on the reheat temperature ($T_r\lesssim 10^6$ GeV) and requiring a neutralino LSP, the tensor to scalar ratio ($r$) has a lower bound $r\gtrsim 0.004$. The U(1) symmetry breaking scale lies between $10^8$ and $10^{12}$ GeV. We also discuss a scenario with gravitino dark matter whose mass is a few GeV.

   hep-phastro-ph.COPLB(2018)·14 citations
8. 08*

   Single top-quark production with the Matrix Element Method in next-to-leading order accuracy

   Till Martini🇩🇪 · Peter Uwer🇩🇪

   Single top-quark production offers a unique laboratory for precision tests of the Standard Model and searches of possible extensions. Furthermore, assuming the Standard Model, single top-quark production can be used to determine top-quark related couplings. For precise determinations of parameters like the electroweak gauge couplings or the mass of the top quark, efficient, unbiased, and theoretically unambiguous analysis methods are needed. Within this context, the Matrix Element Method (MEM) has been established in hadron collider analyses due to its possibility to top out at utilising the information available in experimental data. However, so far it has mostly been applied in Born approximation only. We discuss the extension to next-to-leading order (NLO) accuracy. As a necessary prerequisite we introduce an efficient method to calculate NLO QCD weights for jet events. As proof of concept and representative example we use the MEM at NLO to reproduce the top-quark mass in a toy experiment where we treat single top-quark events generated at NLO accuracy as pseudo-data. This is the first application of the MEM at NLO accuracy to the hadronic production of jets originating from coloured final state partons. We observe that analysing NLO events with Born likelihoods can introduce a pronounced bias in the extracted mass which would require significant calibration with associated uncertainties. Although we focus on parameter determinations, the methods presented here can also be used to search for new physics using likelihood ratios.

   hep-phhep-exPoS(2018)·1 citation
9. 09*

   Chiral magnetic currents with QGP medium response in heavy ion collisions at RHIC and LHC energies

   Duan She🇨🇳 · Sheng-Qin Feng🇨🇳 · Yang Zhong🇨🇳 · Zhong-Bao Yin🇨🇳

   We calculate the electromagnetic current with a more realistic approach in the RHIC and LHC energy regions in the article. We take the partons formation time as the initial time of the magnetic field response of QGP medium. The maximum electromagnetic current and the time-integrated current are two important characteristics of the chiral magnetic effect (CME), which can characterize the intensity and duration of fluctuations of CME. We consider the finite frequency response of CME to a time-varying magnetic field, find a significant impact from QGP medium feedback, and estimate the generated electromagnetic current as a function of time, beam energy and impact parameter.

   hep-phEPJA(2018)·27 citations
10. 10*

    Beyond the standard model with sum rules

    Damian Ejlli🇷🇺

    The possibility of physics beyond the standard model is studied. The requirement of finiteness of the zero point energy density and pressure or the requirement of the Lorentz invariance of the zero point stress-energy tensor in Minkowski space-time, implies regularization sum rules on the number of degrees of freedom and mass of fundamental particles spectrum. The consequences of these sum rules on the existence of particles beyond the standard model is studied. If these sum rules are to be satisfied, it is shown that some simple and minimal extensions of the standard model such as the two Higgs doublet model, right handed neutrinos, mirror symmetry can not be complete extensions in their current forms. The only exception is unbroken supersymmetry and maybe broken supersymmetry. A comparison between different regularization schemes is also done. It is shown that while all considered regularization schemes give a Lorentz invariant expression for the zero point stress-energy tensor in Minkowski space, their physical interpretations are quite different.

    hep-phhep-thInt.J.Mod.Phys.A(2019)·2 citations
11. 11*

    Majorana neutrinos in seesaw mechanism and Bogoliubov quasiparticles

    Kazuo Fujikawa🇯🇵 · Anca Tureanu🇫🇮

    The idea that the Majorana neutrino should be identified as a Bogoliubov quasiparticle is applied to the seesaw mechanism for the three generations of neutrinos in the Standard Model. A relativistic analogue of the Bogoliubov transformation in the present context is a CP-preserving canonical transformation but modifies charge conjugation properties in such a way that the C-noninvariant fermion number violating term (condensate) is converted to a Dirac mass term. Puzzling aspects associated with the charge conjugation of chiral Weyl fermions are clarified. By invoking the Coleman--Weinberg mechanism in the framework of dimensional regularization, it is also noted that seesaw models become unnatural in some parameter regions which induce the hierarchy problems in the bosonic sector.

    hep-phhep-thPRD(2018)·9 citations
12. 12*

    CP Violation in Leptonic Rare $B_s^0$ Decays as a Probe of New Physics

    Robert Fleischer🇳🇱 · Daniela Galárraga Espinosa🇳🇱 · Ruben Jaarsma🇳🇱 · Gilberto Tetlalmatzi-Xolocotzi🇳🇱

    The decay $B_s^0\to {\mu }^{+}{\mu }^{-}$ is a key probe for the search of physics beyond the Standard Model. While the current measurements of the corresponding branching ratio agree with the Standard Model within the uncertainties, significant New-Physics effects may still be hiding in $B_s^0\to {\mu }^{+}{\mu }^{-}$. In order to reveal them, the observable ${\mathcal{A}}_{\Delta {\Gamma }_s}^{\mu \mu }$, which is provided by the decay width difference $\Delta {\Gamma }_s$ of the $B_s^0$-meson system, plays a central role. We point out that a measurement of a CP-violating observable ${\mathcal{S}}_{\mu \mu }$, which is induced through interference between $B_s^0$-${\bar{B}}_s^0$ mixing and $B_s\to {\mu }^{+}{\mu }^{-}$ decay processes, is essential to obtain the full picture, in particular to establish new scalar contributions and CP-violating phases. We illustrate these findings with future scenarios for the upgrade(s) of the LHC, exploiting also relations which emerge within an effective field theory description of the Standard Model, complemented with New Physics entering significantly beyond the electroweak scale.

    hep-phhep-exEPJC(2018)·585 citations
13. 13*

    Strong magnetic fields in nonlocal chiral quark models

    D. Gomez Dumm🇦🇷 · M.F. Izzo Villafañe🇦🇷 · S. Noguera🇪🇸 · V.P. Pagura🇪🇸 · N.N. Scoccola🇦🇷

    We study the behavior of strongly interacting matter under a uniform intense external magnetic field in the context of nonlocal extensions of the Polyakov-Nambu-Jona-Lasinio model. A detailed description of the formalism is presented, considering the cases of zero and finite temperature. In particular, we analyze the effect of the magnetic field on the chiral restoration and deconfinement transitions, which are found to occur at approximately the same critical temperatures. Our results show that these models offer a natural framework to account for the phenomenon of inverse magnetic catalysis found in lattice QCD calculations.

    hep-phPRD(2017)·32 citations
14. 14*

    Inclusive dihadron production at the LHC in NLA BFKL

    Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Beatrice Murdaca🇮🇹 · Alessandro Papa🇮🇹

    A study of cross sections and azimuthal correlation moments for the inclusive production of two, light charged hadrons featuring large transverse momenta and well separated in rapidity at LHC energies, including BFKL resummation effects with NLA accuracy, is presented. This reaction shares the same theoretical setup with the well konwn Mueller-Navelet jet production and can be thought of as a new and complementary channel to access the BFKL dynamics at proton colliders.

    hep-ph24 citations
15. 15*

    A theoretical study of meson transition form factors

    Pablo Sanchez-Puertas🇩🇪

    In this thesis we discuss a rational and data-based description of the single- and double-virutal transition form factors of the lightest pseudoscalar mesons. We obtain an accurate description of these in the spacelike and low-energy timelike regions. The phenomenological applications are wide. Among them, we discuss, the eta-eta' mixing, the rare pseudoscalar decays into a lepton pair and the pseudoscalar-pole contribution to the hadronic light-by-light part of the anomalous magnetic moment of the muon. In all these cases we discuss and illustrate the relevance of employing a data-based approach in order not to incur in potential systematic errors.

    hep-ph12 citations
16. 16*

    The Structure of the Proton in the LHC Precision Era

    Jun Gao🇨🇳 · Lucian Harland-Lang🇬🇧 · Juan Rojo🇳🇱

    We review recent progress in the determination of the parton distribution functions (PDFs) of the proton, with emphasis on the applications for precision phenomenology at the Large Hadron Collider (LHC). First of all, we introduce the general theoretical framework underlying the global QCD analysis of the quark and gluon internal structure of protons. We then present a detailed overview of the hard-scattering measurements, and the corresponding theory predictions, that are used in state-of-the-art PDF fits. We emphasize here the role that higher-order QCD and electroweak corrections play in the description of recent high-precision collider data. We present the methodology used to extract PDFs in global analyses, including the PDF parametrization strategy and the definition and propagation of PDF uncertainties. Then we review and compare the most recent releases from the various PDF fitting collaborations, highlighting their differences and similarities. We discuss the role that QED corrections and photon-initiated contributions play in modern PDF analysis. We provide representative examples of the implications of PDF fits for high-precision LHC phenomenological applications, such as Higgs coupling measurements and searches for high-mass New Physics resonances. We conclude this report by discussing some selected topics relevant for the future of PDF determinations, including the treatment of theoretical uncertainties, the connection with lattice QCD calculations, and the role of PDFs at future high-energy colliders beyond the LHC.

    hep-phhep-exhep-latnucl-ex+1Phys.Rept.(2018)·316 citations
17. 17*

    Spin dependence of {\eta} meson production in proton-proton collisions close to threshold

    P. Adlarson🇵🇱 · W. Augustyniak🇵🇱 · W. Bardan🇵🇱 · M. Bashkanov🇬🇧 · S. D. Bass🇵🇱 · F.S. Bergmann🇩🇪 · M. Berlowski🇵🇱 · A. Bondar🇷🇺 · M.Buscher · H. Calen🇸🇪 · I. Ciepal🇵🇱 · H. Clement🇩🇪 and 80 other authors

    Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high degree of the polarized proton beam of COSY, the reaction pp{\to} pp{\eta} has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than one order of magnitude with respect to previous results allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q = 15 MeV signaling s wave production with no evidence for higher partial waves. At Q = 72 MeV the data reveals strong interference of P s and P p partial waves and cancellation of (P p) and Ss*Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the {\eta} meson.

    ↳ nucl-exhep-exhep-phnucl-thPRL(2018)·2 citations
18. 18*

    Partially Acoustic Dark Matter Cosmology and Cosmological Constraints

    Marco Raveri🇺🇸 · Wayne Hu🇺🇸 · Timothy Hoffman🇺🇸 · Lian-Tao Wang🇺🇸

    Observations of the cosmic microwave background (CMB) together with weak lensing measurements of the clustering of large scale cosmological structures and local measurements of the Hubble constant pose a challenge to the standard $\Lambda$CDM cosmological model. On one side CMB observations imply a Hubble constant that is lower than local measurements and an amplitude of the lensing signal that is higher than direct measurements from weak lensing surveys. We investigate a way of relieving these tensions by adding dark radiation tightly coupled to an acoustic part of the dark matter sector and compare it to massive neutrino solutions. While these models offer a way of separately relieving the Hubble and weak lensing tensions they are prevented from fully accommodating both at the same time since the CMB requires additional cold dark matter when adding acoustic dark matter or massive neutrinos to preserve the same sharpness of the acoustic peaks which counteracts the desired growth suppression.

    ↳ astro-ph.COhep-phPRD(2017)·59 citations
19. 19*

    Constraints and prospects on gravitational wave and neutrino emission using GW150914

    Krijn D. de Vries🇧🇪 · Gwenhaël de Wasseige🇧🇪 · Jean-Marie Frère🇧🇪 · Matthias Vereecken🇧🇪

    The recent LIGO observation of gravitational waves from a binary black hole merger triggered several follow-up searches from both electromagnetic wave as well as neutrino observatories. Since in general, it is expected that all matter has been removed from the binary black hole environment long before the merger, no neutrino emission is expected from such mergers. Still, it remains interesting to test this hypothesis. The ratio of the energy emitted in neutrinos with respect to gravitational waves represents a useful parameter to constrain the environment of such astrophysical events. In addition to putting constraints by use of the non-detection of counterpart neutrinos, it is also possible to consider the diffuse neutrino flux measured by the IceCube observatory as the maximum contribution from an extrapolated full class of BBHs. Both methods currently lead to similar bounds on the fraction of energy that can be emitted in neutrinos. Nevertheless, combining both methods should allow to strongly constrain the source population in case of a future neutrino counterpart detection. The proposed approach can and will be applied to potential upcoming LIGO events, including binary neutron stars and black hole-neutron star mergers, for which a neutrino counterpart is expected.

    ↳ astro-ph.HEhep-phPoS(2018)·1 citation
20. 20*

    Dark Energy and Dark Matter in Emergent Gravity

    Jungjai Lee🇰🇷 · Hyun Seok Yang🇰🇷

    Emergent gravity can be applied to a large $N$ matrix model by considering the vacuum of a noncommutative (NC) Coulomb branch that satisfies the Heisenberg algebra. Due to the fact that IR fluctuations in the NC Coulomb branch always pair with UV fluctuations, this UV/IR mixing is extendable to a macroscopic scale. These vacuum fluctuations in the NC Coulomb branch are described by a four-dimensional NC $U(1)$ gauge theory. The order parameter for the vacuum fluctuations is given by random four-vectors that have their own causal structure in the commutative limit unlike the conventional cosmological models based on a scalar field theory coupled to gravity. We show that their causal structure results in the different nature of gravitational interactions so that space-like fluctuations give rise to the repulsive gravitational force while time-like fluctuations generate the attractive gravitational force. Given the fact that the fluctuations are random in nature and we live in a (3+1)-dimensional spacetime, the ratio of the repulsive vs. attractive components ends up being 3:1 = 75:25, which is interestingly consistent with the dark components of the current universe. If we include ordinary matters acting as an attractive gravitational force, the emergent gravity could more accurately explain the dark side of our universe. This work is an expanded version of the conference proceedings (Yang in EPJ Web Conf 168:03006, 2018).

    ↳ hep-thgr-qchep-phJ.Korean Phys.Soc.(2022)·4 citations
21. 21*

    Interpretation of quantum mechanics with indefinite norm

    Alessandro Strumia🇨🇭

    The Born postulate can be reduced to its deterministic content that only applies to eigenvectors of observables: the standard probabilistic interpretation of generic states then follows from algebraic properties of repeated measurements and states. Extending this reasoning suggests an interpretation of quantum mechanics generalized with indefinite quantum norm.

    ↳ quant-phhep-phhep-thMDPI Physics(2019)·35 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.