Thu·Dec 21, 2017Thursday·December 21, 2017

1. 01*

   Zero-Range Effective Field Theory for Resonant Wino Dark Matter III. Annihilation Effects

   Eric Braaten🇺🇸 · Evan Johnson🇺🇸 · Hong Zhang🇺🇸

   Near a critical value of the wino mass where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold, low-energy winos can be described by a zero-range effective field theory (ZREFT) in which the winos interact nonperturbatively through a contact interaction and through Coulomb interactions. The effects of wino-pair annihilation into electroweak gauge bosons are taken into account through the analytic continuation of the real parameters for the contact interaction to complex values. The parameters of ZREFT can be determined by matching wino-wino scattering amplitudes calculated by solving the Schrödinger equation for winos interacting through a real potential due to the exchange of electroweak gauge bosons and an imaginary potential due to wino-pair annihilation into electroweak gauge bosons. ZREFT at leading order gives an accurate analytic description of low-energy wino-wino scattering, inclusive wino-pair annihilation, and a wino-pair bound state. ZREFT can also be applied to partial annihilation rates, such as the Sommerfeld enhancement of the annihilation rate of wino pairs into monochromatic photons.

   hep-phJHEP(2018)·26 citations
2. 02*

   Combining initial-state resummation with fixed-order calculations of electroweak corrections

   Christian W. Bauer🇺🇸 · Nicolas Ferland🇺🇸 · Bryan R. Webber🇬🇧

   We present a resummation of those double-logarithmically enhanced electroweak correction that arise in pp colliders because protons are not SU(2) singlets, by solving DGLAP equations in the full Standard Model. We then show how to match these results with those of fixed-order electroweak calculations. At a 100 TeV pp collider, contributions beyond order alpha are ~ 10% at partonic center-of-mass energies of a few TeV. These are mainly due to initial states with massive vector bosons.

   hep-phhep-exJHEP(2018)·33 citations
3. 03*

   Collider phenomenology of Hidden Valley mediators of spin 0 or 1/2 with semivisible jets

   Hugues Beauchesne🇧🇷 · Enrico Bertuzzo🇧🇷 · Giovanni Grilli di Cortona🇧🇷 · Zahra Tabrizi🇧🇷

   Many models of Beyond the Standard Model physics contain particles that are charged under both Standard Model and Hidden Valley gauge groups, yet very little effort has been put into establishing their experimental signatures. We provide a general overview of the collider phenomenology of spin 0 or 1/2 mediators with non-trivial gauge numbers under both the Standard Model and a single new confining group. Due to the possibility of many unconventional signatures, the focus is on direct production with semivisible jets. For the mediators to be able to decay, a global $U(1)$ symmetry must be broken. This is best done by introducing a set of operators explicitly violating this symmetry. We find that there is only a finite number of such renormalizable operators and that the phenomenology can be classified into five distinct categories. We show that large regions of the parameter space are already excluded, while others are unconstrained by current search strategies. We also discuss how searches could be modified to better probe these unconstrained regions by exploiting special properties of semivisible jets.

   hep-phJHEP(2018)·57 citations
4. 04*

   In-Medium $K^{+}$ Electromagnetic Form Factor with a Symmetric Vertex in a Light Front Approach

   George H. S. Yabusaki (Instituto Tecnológico de Aeronáutica - ITA and LFTC - Cruzeiro do Sul)🇧🇷 · J. P. B. C. de Melo (LFTC - Cruzeiro do Sul)🇧🇷 · Wayne de Paula (Instituto Tecnológico de Aeronáutica - ITA)🇧🇷 · K. Tsushima (LFTC - Cruzeiro do Sul)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica - ITA)🇧🇷

   Using the light-front kaon wave function based on a Bethe-Salpeter amplitude model for the quark-antiquark bound state, we study the Electromagnetic Form Factor (EMFF) of the kaon in nuclear medium within the framework of light-front field theory. The kaon model we adopt is well constrained by previous and recent studies to explain its properties in vacuum. The in-medium kaon EMFF is evaluated for the + component of the electromagnetic current, $J^{+}$, in the Breit frame. In order to consistently incorporate the constituent up and antistrange quarks of the kaon immersed in symmetric nuclear matter, we use the Quark-Meson Coupling (QMC) model, which has been widely applied to various hadronic and nuclear phenomena in a nuclear medium with success. We predict the in-medium modification of the kaon EMFF in symmetric nuclear matter. It is found that, after a fine tuning of the regulator mass, i.e. $m_R=0.600$ GeV, the model is suitable to fit the available experimental data in vaccum within the theoretical uncertainties, and based on this we predict the in-medium modification of the EMFF.

   hep-phhep-exnucl-exnucl-thFew Body Syst.(2018)·7 citations
5. 05*

   Study of top quark dipole interactions in $t\bar{t}$ production associated with two heavy gauge bosons at the LHC

   Seyed Mohsen Etesami🇮🇷 · Sara Khatibi🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

   In this paper, we investigate the prospects of measuring the strong and weak dipole moments of the top quark at the Large Hadron Collider (LHC). Measurements of these couplings provide an excellent opportunity to probe new physics interactions as they have quite small magnitudes in the Standard Model. Our analyses are through studying the production cross sections of $t\bar{t}WW$ and $t\bar{t}ZZ$ processes in the same sign dilepton and four-lepton final states, respectively. The sensitivities to strong and weak top quark dipole interactions at the $95\%$ confidence level for various integrated luminosity scenarios are derived and compared with other studies. In addition to using the total cross sections, a novel handle based on an angular observable is introduced which is found to be sensitive to variations of the top quark strong dipole moments. We also investigate the sensitivity of the invariant mass of the system to the strong and weak dipole moments of the top quark.

   hep-phPRD(2018)·15 citations
6. 06*

   TASI 2016 Lectures: Electroweak Symmetry Breaking and Effective Field Theory

   S. Dawson🇺🇸

   I give a pedagogical introduction to the physics of electroweak symmetry breaking and the uses of effective field theory in the context of Higgs physics. Higgs boson production and decay at the LHC and the consistency of the Higgs measurements with triviality arguments, vacuum stability, and precision electroweak measurements are discussed. Effective Lagrangian techniques are used to understand potential deviations from the Standard Model (SM) predictions. Finally, I end with a brief discussion of the future of Higgs physics.

   hep-ph9 citations
7. 07*

   Exposing Dark Sector with Future Z-Factories

   Jia Liu🇺🇸 · Lian-Tao Wang🇺🇸 · Xiao-Ping Wang🇺🇸 · Wei Xue🇺🇸

   We investigate the prospects of searching dark sector models via exotic Z-boson decay at future $e^{+}{e}^{-}$ colliders with Giga Z and Tera Z options. Four general categories of dark sector models: Higgs portal dark matter, vector portal dark matter, inelastic dark matter and axion-like particles, are considered. Focusing on channels motivated by the dark sector models, we carry out a model independent study of the sensitivities of Z-factories in probing exotic decays. The limits on branching ratios of the exotic Z decay are typically $\mathcal{O}(10^{-6}-10^{-8.5})$ for the Giga Z and $\mathcal{O}(10^{-7.5}-10^{-11})$ for the Tera Z, and they are compared with the projection for the high luminosity LHC. We demonstrate that future Z-factories can provide its unique and leading sensitivity, and highlight the complementarity with other experiments, including the indirect and direct dark matter search limits, and the existing collider limits. Future Z factories will play a leading role to uncover the hidden sector of the universe in the future.

   hep-phPRD(2018)·51 citations
8. 08*

   Fermion mass hierarchy from nonuniversal abelian extensions of the Standard Model

   Carlos E. Díaz🇨🇴 · S.F Mantilla🇨🇴 · R. Martinez🇨🇴

   A nonuniversal abelian extension ${\mathrm{U}(1)}_X$ free from chiral anomalies is introduced into the Standard Model (SM), in order to evaluate its suitability in addressing the fermion mass hierarchy (FMH) by using seesaw mechanisms (SSM). In order to break the electroweak symmetry, three Higgs doublets are introduced, which give mass at tree-level to the top and bottom quarks, and the muon lepton. With an electroweak singlet scalar field, the $U(1{)}_X$ symmetry is broken and the exotic particles acquire masses. The light particles in the SM obtain their masses via SSM and Yukawa couplings differences. Active neutrino masses are generated through inverse seesaw mechanisms (ISM). Additionally, the algebraic expressions for the mixing angles for quarks and leptons are also shown in the article. Keywords: Flavor Problem, Neutrino Physics, Extended Scalar Sectors, Beyond Standard Model, Fermion masses, Inverse seesaw Mechanism.

   hep-phPRD(2018)·8 citations
9. 09*

   Strong decays of the 1P and 2D doubly charmed states

   Li-Ye Xiao🇨🇳 · Qi-Fang Lü🇨🇳 · Shi-Lin Zhu🇨🇳

   We perform a systematical investigation of the strong decay properties of the low-lying $1P$- and $2D$-wave doubly charmed baryons with the ${}^3{P}_0$ quark pair creation model. The main predictions include: (i) in the ${\Xi }_{cc}$ and ${\Omega }_{cc}$ family, the $1P\rho$ mode excitations with $J^P=1/2^{-}$ and $3/2^{-}$ should be the fairly narrow states. (ii) For the $1P\lambda$ mode excitations, ${|}^2{P}_{\lambda }{\frac{3}{2}}^{-}⟩$ and ${|}^4{P}_{\lambda }{\frac{3}{2}}^{-}⟩$ have a width of $\Gamma \sim 150$ MeV, and mainly decay into the $J^P=3/2^{+}$ ground state. Meanwhile, ${|}^2{P}_{\lambda }{\frac{1}{2}}^{-}⟩$ and ${|}^4{P}_{\lambda }{\frac{5}{2}}^{-}⟩$ are the narrow states with a width of $\Gamma \sim 40$ MeV, and mainly decay into the ground state with $J^P=1/2^{+}$. (iii) The $2D_{\rho \rho }$ states mainly decay via emitting a heavy-light meson if their masses are above the threshold of ${\Lambda }_{c}D$ or ${\Xi }_{c}D$, respectively. Their strong decay widths are sensitive to the masses and can reach several tens MeV. (iv) The $2D_{\lambda \lambda }$ states may be broad states with a width of $\Gamma >100$ MeV. It should be emphasized that the states with $J^P=3/2^{+}$ and $5/2^{+}$ mainly decay into the ground state with $J^P=3/2^{+}$ plus a light-flavor meson, while the states with $J^P=1/2^{+}$ and $7/2^{+}$ mainly decay into the ground state with $J^P=1/2^{+}$ plus a light-flavor meson.

   hep-phPRD(2018)·42 citations
10. 10*

    Effects of BSMs on ${\theta }_{23}$ determination

    C.R. Das🇷🇺 · Jukka Maalampi🇫🇮 · Joao Pulido🇫🇮 · Sampsa Vihonen🇫🇮

    We investigate the prospects for determining the octant of ${\theta }_{23}$ in the future long baseline oscillation experiments. We present our results as contour plots on the (${\theta }_{23}-45^{\circ }$, $\delta$)--plane, where $\delta$ is the CP phase, showing the true values of ${\theta }_{23}$ for which the octant can be experimentally determined at 3$\sigma$, 2$\sigma$ and 1$\sigma$ confidence level, in particular, the impact of the non-unitarity of neutrino mixing.

    hep-phhep-ex0 citations
11. 11*

    Dark Matter Freeze-in Production in Fast-Expanding Universes

    Francesco D'Eramo🇮🇹 · Nicolas Fernandez🇺🇸 · Stefano Profumo🇺🇸

    If the dark matter is produced in the early universe prior to Big Bang nucleosynthesis, a modified cosmological history can drastically affect the abundance of relic dark matter particles. Here, we assume that an additional species to radiation dominates at early times, causing the expansion rate at a given temperature to be larger than in the standard radiation-dominated case. We demonstrate that, if this is the case, dark matter production via freeze-in (a scenario when dark matter interacts very weakly, and is dumped in the early universe out of equilibrium by decay or scattering processes involving particles in the thermal bath) is dramatically suppressed. We illustrate and quantitatively and analytically study this phenomenon for three different paradigmatic classes of freeze-in scenarios. For the frozen-in dark matter abundance to be as large as observations, couplings between the dark matter and visible-sector particles must be enhanced by several orders of magnitude. This sheds some optimistic prospects for the otherwise dire experimental and observational outlook of detecting dark matter produced by freeze-in.

    hep-phastro-ph.COJCAP(2018)·117 citations
12. 12*

    Subleading-power N-jet operators and the LBK amplitude in SCET

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

    We construct a complete and minimal basis of subleading-power N-jet operators in position-space soft-collinear effective theory (SCET) and discuss how the Low-Burnett-Kroll amplitude is recovered in this framework. We begin a systematic investigation of the anomalous dimension of next-to-leading power N-jet operators in view of resummation of logarithmically enhanced terms in partonic cross sections and discuss the explicit result at the one-loop order for fermion-number two N-jet operators at the second order in the power expansion parameter of SCET.

    hep-phhep-thPoS(2017)·14 citations
13. 13*

    $\Lambda (1405)$ production in the process ${\chi }_{c0}(1P)\to \bar{\Lambda }\Sigma \pi$

    Li-Juan liu🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Kai-Lan Song🇨🇳 · Jing-Yu Zhu🇨🇳

    We have performed a theoretical study on the process ${\chi }_{c0}(1P)\to \bar{\Lambda }\Sigma \pi$, by taking into account the final state interactions of $\pi \Sigma$ and $\pi \bar{\Lambda }$ based on the chiral unitary approach. As the isospin filters of $I=0$ in the $\pi \Sigma$ channel and $I=1$ in the $\pi \bar{\Lambda }$ channel, this process can be used to study the molecular structure of the $\Lambda (1405)$ resonance, and to test the existence of the predicted states $\Sigma (1380)$ and $\Sigma (1430)$ with spin-parity $J^P=1/2^{-}$. Our results show that there is a peak around $1350\sim 1400$~MeV, and a cusp around the $\bar{K}N$ threshold in the $\pi \Sigma$ invariant mass distribution, which should be the important feature of the molecular state $\Lambda (1405)$. We also find a peak around $1380$~MeV, and a cusp around $\bar{K}N$ threshold in the $\pi \bar{\Lambda }$ invariant mass distribution, which are associated to the $\Sigma (1380)$ and $\Sigma (1430)$ resonances.

    hep-phhep-exPRD(2018)·24 citations
14. 14*

    Precise prediction for the Higgs-Boson Masses in the $\mu \nu$SSM

    T. Biekötter🇪🇸 · S. Heinemeyer🇪🇸 · C. Muñoz🇪🇸

    The $\mu \nu$SSM is a simple supersymmetric extension of the Standard Model (SM) capable of predicting neutrino physics in agreement with experiment. In this paper we perform the complete one-loop renormalization of the neutral scalar sector of the $\mu \nu$SSM with one generation of right-handed neutrinos in a mixed on-shell/$\overline{\mathrm{DR}}$ scheme. The renormalization procedure is discussed in detail, emphasizing conceptual differences to the minimal (MSSM) and next-to-minimal (NMSSM) supersymmetric standard model regarding the field renormalization and the treatment of non-flavor-diagonal soft mass parameters, which have their origin in the breaking of $R$-parity in the $\mu \nu$SSM. We calculate the full one-loop corrections to the neutral scalar masses of the $\mu \nu$SSM. The one-loop contributions are supplemented by available MSSM higher-order corrections. We obtain numerical results for a SM-like Higgs boson mass consistent with experimental bounds. We compare our results to predictions in the NMSSM to obtain a measure for the significance of genuine $\mu \nu$SSM-like contributions. We only find minor corrections due to the smallness of the neutrino Yukawa couplings, indicating that the Higgs boson mass calculations in the $\mu \nu$SSM are at the same level of accuracy as in the NMSSM. Finally we show that the $\mu \nu$SSM can accomodate a Higgs boson that could explain an excess of $\gamma \gamma$ events at $\sim 96\mathrm{GeV}$ as reported by CMS, as well as the $2\sigma$ excess of $b\bar{b}$ events observed at LEP at a similar mass scale.

    hep-phEPJC(2018)·85 citations
15. 15*

    On the use of a running coupling in the NLO calculation of forward hadron production

    B. Ducloué🇫🇮 · E. Iancu🇫🇷 · T. Lappi🇫🇮 · A. H. Mueller🇺🇸 · G. Soyez🇫🇷 · D. N. Triantafyllopoulos🇮🇹 · Y. Zhu🇫🇮

    We address and solve a puzzle raised by a recent calculation [1] of the cross-section for particle production in proton-nucleus collisions to next-to-leading order: the numerical results show an un- reasonably large dependence upon the choice of a prescription for the QCD running coupling, which spoils the predictive power of the calculation. Specifically, the results obtained with a prescription formulated in the transverse coordinate space differ by one to two orders of magnitude from those obtained with a prescription in momentum space. We show that this discrepancy is an artefact of the interplay between the asymptotic freedom of QCD and the Fourier transform from coordinate space to momentum space. When used in coordinate space, the running coupling can act as a fictitious potential which mimics hard scattering and thus introduces a spurious contribution to the cross-section. We identify a new coordinate-space prescription which avoids this problem and leads to results consistent with those obtained with the momentum-space prescription.

    hep-phPRD(2018)·44 citations
16. 16*

    Asymmetric dark matter: residual annihilations and self-interactions

    Iason Baldes🇩🇪 · Marco Cirelli🇫🇷 · Paolo Panci🇨🇭 · Kalliopi Petraki🇫🇷 · Filippo Sala🇩🇪 · Marco Taoso🇪🇸

    Dark matter (DM) coupled to light mediators has been invoked to resolve the putative discrepancies between collisionless cold DM and galactic structure observations. However, $\gamma$-ray searches and the CMB strongly constrain such scenarios. To ease the tension, we consider asymmetric DM. We show that, contrary to the common lore, detectable annihilations occur even for large asymmetries, and derive bounds from the CMB, $\gamma$-ray, neutrino and antiproton searches. We then identify the viable space for self-interacting DM. Direct detection does not exclude this scenario, but provides a way to test it.

    hep-phSciPost Phys.(2018)·65 citations
17. 17*

    Constraining Composite Higgs Models using LHC data

    Avik Banerjee🇮🇳 · Gautam Bhattacharyya🇮🇳 · Nilanjana Kumar🇮🇳 · Tirtha Sankar Ray🇮🇳

    We systematically study the modifications in the couplings of the Higgs boson, when identified as a pseudo Nambu-Goldstone boson of a strong sector, in the light of LHC Run 1 and Run 2 data. For the minimal coset SO(5)/SO(4) of the strong sector, we focus on scenarios where the standard model left- and right-handed fermions (specifically, the top and bottom quarks) are either in 5 or in the symmetric 14 representation of SO(5). Going beyond the minimal 5L-5R representation, to what we call here the 'extended' models, we observe that it is possible to construct more than one invariant in the Yukawa sector. In such models, the Yukawa couplings of the 125 GeV Higgs boson undergo nontrivial modifications. The pattern of such modifications can be encoded in a generic phenomenological Lagrangian which applies to a wide class of such models. We show that the presence of more than one Yukawa invariant allows the gauge and Yukawa coupling modifiers to be decorrelated in the 'extended' models, and this decorrelation leads to a relaxation of the bound on the compositeness scale (f > 640 GeV at 95% CL, as compared to f > 1 TeV for the minimal 5L-5R representation model). We also study the Yukawa coupling modifications in the context of the next-to-minimal strong sector coset SO(6)/SO(5) for fermion-embedding up to representations of dimension 20. While quantifying our observations, we have performed a detailed chi-square fit using the ATLAS and CMS combined Run 1 and available Run 2 data.

    hep-phhep-exJHEP(2018)·41 citations
18. 18*

    Exploring ALPs beyond the canonical

    Gonzalo Alonso-Álvarez🇩🇪 · Joerg Jaeckel🇩🇪

    Axion-like particles (ALPs) are interesting dark matter candidates both from the theoretical as well as from the experimental perspective. Usually they are motivated as pseudo-Nambu-Goldstone bosons. In this case one of their most important features is that their coupling to other particles is suppressed by a large scale, the vacuum expectation value of the field breaking the symmetry that gives rise to them. This naturally endows them with very weak interactions but also restricts the maximal field value and therefore the regions where sufficient dark matter is produced. In this paper we investigate deviations from this simplest setup, where the potential and interactions are as expected for a pseudo-Nambu-Goldstone boson, but the kinetic term has singularities. This leads to a significantly increased area in parameter space where such particles can be dark matter and can be probed by current and near future experiments. We discuss cosmological limits and in the course of this give a simple derivation of a formula for isocurvature fluctuations in models with general anharmonic potentials. As an application of this formula we give an update of the isocurvature constraints for QCD axion dark matter models, using the most recent results for the QCD topological susceptibility and the newest Planck data.

    hep-phastro-ph.COPRD(2018)·19 citations
19. 19*

    Search for Singly Charged Higgs in Vector Boson Scattering at the ep Colliders

    Georges Azuelos🇨🇦 · Hao Sun🇨🇳 · Kechen Wang🇨🇳

    We search for a five-plet singly charged Higgs $H_5^{\pm }$ in the Georgi-Machacek model at the ep colliders. The charged Higgs bosons are produced via the $Z{W}^{\pm }$ fusion process $p{e}^{-}\to j{e}^{-}{H}_5^{\pm }$, and decay as $H_5^{\pm }\to Z{W}^{\pm }\to (l^{+}{l}^{-})(jj)$. With a detector-level simulation at the FCC-eh and LHeC, a multi-variate analysis is performed to yield limits on the production cross section times branching ratio $\sigma (p{e}^{-}\to j{e}^{-}{H}_5^{\pm })\times \mathrm{BR}(H_5^{\pm }\to Z{W}^{\pm })$ and on the model parameter $\sin {\theta }_H$ for charged Higgs masses between 200 and 1000 GeV. The effects of electron beam polarization are also investigated.

    hep-phhep-exPRD(2018)·15 citations
20. 20*

    Cristal and Azurite: new tools for integration-by-parts reductions

    Alessandro Georgoudis🇸🇪 · Kasper J. Larsen🇬🇧 · Yang Zhang🇩🇪

    Scattering amplitudes computed at a fixed loop order, along with any other object computed in perturbative quantum field theory, can be expressed as a linear combination of a finite basis of loop integrals. To compute loop amplitudes in practice, such a basis of integrals must be determined. We discuss Azurite (A ZURich-bred method for finding master InTEgrals), a publicly available package for finding bases of loop integrals. We also discuss Cristal (Complete Reduction of IntegralS Through All Loops), a future package that produces the complete integration-by-parts reductions.

    hep-phPoS(2017)·10 citations
21. 21*

    NNLO QCD corrections to the transverse momentum distribution of weak gauge bosons

    A. Gehrmann-De Ridder🇨🇭 · T. Gehrmann🇨🇭 · E. W. N. Glover🇬🇧 · A. Huss🇨🇭 · D. M. Walker🇬🇧

    The transverse momentum spectra of weak gauge bosons and their ratios probe the underlying dynamics and are crucial in testing our understanding of the Standard Model. They are an essential ingredient in precision measurements, such as the $\mathrm{W}$-boson mass extraction. To fully exploit the potential of the LHC data, we compute the second-order (NNLO) QCD corrections to the inclusive-$p_{\mathrm{T}}^{\mathrm{W}}$ spectrum as well as to the ratios of spectra for ${\mathrm{W}}^{-}/{\mathrm{W}}^{+}$ and $\mathrm{Z}/\mathrm{W}$. We find that the inclusion of NNLO QCD corrections considerably improves the theoretical description of the experimental CMS data and results in a substantial reduction of the residual scale uncertainties.

    hep-phPRL(2018)·99 citations
22. 22*

    Equivalence between massless neutrinos and lepton number conservation in fermionic singlet extensions of the Standard Model

    K. Moffat🇬🇧 · S. Pascoli🇬🇧 · C. Weiland🇬🇧

    We discuss the most general necessary and sufficient condition for three massless light neutrinos in variants of the type I seesaw mechanism in which we introduce an arbitrary number of fermionic gauge singlets. We find that having massless light neutrinos is equivalent to enforcing the conservation of lepton number. As a consequence, any symmetry that leads to massless light neutrinos will contain as an unbroken subgroup a conserved lepton number. This will be important for searches for heavy sterile neutrinos since in general the light neutrino masses will be proportional to small lepton number violating parameters that will also suppress lepton number violating signatures.

    hep-ph88 citations
23. 23*

    How to prove that the LHC did not discover dark matter

    Doojin Kim🇨🇭 · Konstantin T. Matchev🇺🇸

    If the LHC is able to produce dark matter particles, they would appear at the end of cascade decay chains, manifesting themselves as missing transverse energy. However, such "dark matter candidates" may decay invisibly later on. We propose to test for this possibility by studying the effect of particle widths on the observable invariant mass distributions of the visible particles seen in the detector. We consider the simplest non-trivial case of a two-step two-body cascade decay and derive analytically the shapes of the invariant mass distributions, for generic values of the widths of the new particles. We demonstrate that the resulting distortion in the shape of the invariant mass distribution can be significant enough to measure the width of the dark matter "candidate", ruling it out as the source of the cosmological dark matter.

    hep-phhep-exPRD(2018)·6 citations
24. 24*

    $W^{+}{W}^{-}H$ Production at Lepton Colliders: A New Hope for Heavy Neutral Leptons

    Julien Baglio🇩🇪 · Silvia Pascoli🇬🇧 · Cedric Weiland🇬🇧

    We present the first study of the production of a Standard Model Higgs boson at a lepton collider in association with a pair of W bosons, $e_{}^{+}{e}_{}^{-}\to W_{}^{+}{W}_{}^{-}H$, in the inverse seesaw model. Taking into account all relevant experimental and theoretical constraints, we find sizable effects due to the additional heavy neutrinos up to -38% on the total cross-section at a center-of-mass energy of 3 TeV, and even up to -66% with suitable cuts. This motivates a detailed sensitivity analysis of the process $e_{}^{+}{e}_{}^{-}\to W_{}^{+}{W}_{}^{-}H$ as it could provide a new, very competitive experimental probe of low-scale neutrino mass models.

    hep-phhep-exEPJC(2018)·5 citations
25. 25*

    Improved determination of $\bar{d}(x)-\bar{u}(x)$ flavor asymmetry in the proton by BONuS experiment at JLAB and using an approach by Brodsky, Hoyer, Peterson, and Sakai

    Maral Salajegheh🇮🇷 · Hamzeh Khanpour🇮🇷 · S. Mohammad Moosavi Nejad🇮🇷

    The experimental data taken from both Drell-Yan and deep-inelastic scattering (DIS) experiments suggest a sign-change in $\bar{d}(x)-\bar{u}(x)$ flavor asymmetry in the proton at large values of momentum fraction $x$. In this work, we present a phenomenological study of $\bar{d}(x)-\bar{u}(x)$ flavor asymmetry. First, we extract the $\bar{d}(x)-\bar{u}(x)$ distribution using the more recent data from the BONuS experiment at Jefferson Lab on the ratio of neutron to proton structure functions, $F_2^n/F_2^p$, and show that it undergoes a sing-change and becomes negative at large values of momentum fraction $x$, as expected. The stability and reliability of our obtained results have been examined by including target mass corrections (TMCs) as well as higher twist (HT) terms which are particularly important at the large-$x$ region at low Q${}^2$. Then, we calculate the $\bar{d}(x)-\bar{u}(x)$ distribution using the Brodsky, Hoyer, Peterson, and Sakai (BHPS) model and show that if one chooses a mass for the down quark smaller than the one for the up quark it leads to a better description for the Fermilab E866 data. In order to prove this claim, we determine the masses of down and up sea quarks by fitting to the available and up-to-date experimental data for the $\bar{d}(x)-\bar{u}(x)$ distribution. In this respect, unlike the previous performed theoretical studies, we have shown that this distribution has a sign-change at $x>0.3$ after evolution to the scale of available experimental data.

    hep-phPRC(2017)·6 citations
26. 26*

    Extended Dark Matter EFT

    Tommi Alanne🇩🇪 · Florian Goertz🇩🇪

    Conventional approaches to describe dark matter phenomenology at collider and (in)direct detection experiments in the form of dark matter effective field theory or simplified models suffer in general from drawbacks regarding validity at high energies and/or generality, limiting their applicability. In order to avoid these shortcomings, we propose a hybrid framework in the form of an effective theory, including, however, both the dark matter states and a mediator connecting the former to the Standard Model fields. Since the mediation can be realized through rather light new dynamical fields allowing for non-negligible collider signals in missing energy searches, the framework remains valid for the phenomenologically interesting parameter region, while retaining correlations dictated by gauge symmetry. Moreover, a richer new-physics sector can be consistently included via higher-dimensional operators. Interestingly, for fermionic and scalar dark matter with a (pseudo-)scalar mediator, the leading effects originate from dimension-five operators, allowing to capture them with a rather small set of new couplings. We finally examine the correlations between constraints from reproducing the correct relic density, direct-detection experiments, and mono-jet and Higgs+missing energy signatures at the LHC.

    hep-phhep-exEPJC(2020)·39 citations
27. 27*

    A warped relaxion

    Nayara Fonseca🇩🇪 · Benedict von Harling🇩🇪 · Leonardo de Lima🇧🇷 · Camila S. Machado🇩🇪

    We construct a UV completion of the relaxion in a warped extra dimension. We identify the relaxion with the zero mode of the fifth component of a bulk gauge field and show how hierarchically different decay constants for this field can be achieved by different localizations of anomalous terms in the warped space. This framework may also find applications for other axion-like fields. The cutoff of the relaxion model is identified as the scale of the IR brane where the Higgs lives, which can be as high as $10^6$ GeV, while above this scale warping takes over in protecting the Higgs mass.

    hep-phJHEP(2018)·14 citations
28. 28*

    Flavor Physics and Flavor Anomalies in Minimal Fundamental Partial Compositeness

    Francesco Sannino🇩🇰 · Peter Stangl🇩🇪 · David M. Straub🇩🇪 · Anders Eller Thomsen🇩🇰

    Partial compositeness is a key ingredient of models where the electroweak symmetry is broken by a composite Higgs state. Recently, a UV completion of partial compositeness was proposed, featuring a new strongly coupled gauge interaction as well as new fundamental fermions and scalars. We work out the full flavor structure of the minimal realization of this idea and investigate in detail the consequences for flavor physics. While CP violation in kaon mixing represents a significant constraint on the model, we find many viable parameter points passing all precision tests. We also demonstrate that the recently observed hints for a violation of lepton flavor universality in $B\to K^{(\ast )}\ell \ell$ decays can be accommodated by the model, while the anomalies in $B\to D^{(\ast )}\tau \nu$ cannot be explained while satisfying LEP constraints on $Z$ couplings.

    hep-phPRD(2018)·64 citations
29. 29*

    Light Dark Matter from Leptogenesis

    Adam Falkowski🇫🇷 · Eric Kuflik🇺🇸 · Noam Levi🇮🇱 · Tomer Volansky🇮🇱

    We consider the implications of a shared production mechanism between the baryon asymmetry of the universe and the relic abundance of dark matter, that does not result in matching asymmetries. We present a simple model within a two sector leptogenesis framework, in which right handed sterile neutrinos decay out of equilibrium to both the Standard Model and the dark sector, generating an asymmetry in one and populating the other. This realization naturally accommodates light dark matter in the keV mass scale and above. Interactions in the dark sector may or may not cause the sector to thermalize, leading to interesting phenomenological implications, including hot, warm or cold thermal relic dark matter, while evading cosmological constraints. Under minimal assumptions the model provides a novel non-thermal production mechanism for sterile neutrino dark matter and predicts indirect detection signatures which may address the unexplained 3.5 keV line observed in various galaxy clusters.

    hep-phPRD(2019)·47 citations
30. 30*

    Probing Transverse-Momentum Dependent Evolution With Groomed Jets

    Yiannis Makris🇺🇸 · Duff Neill🇺🇸 · Varun Vaidya🇺🇸

    We propose an observable which involves measuring the properties (transverse momentum $p_{h\perp }$ and energy fraction $z_h$) of an identified hadron inside a groomed jet. The jet is identified with an anti-kT/CA algorithm and is groomed by implementing the modified mass drop procedure with an energy cut-off parameter $z_{cut}$. The transverse momentum of the hadron inside the jet is measured with respect to the groomed jet axis. We obtain a factorization theorem in the framework of Soft Collinear Effective Theory (SCET), to define a Transverse Momentum Dependent Fragmenting Jet Function (TMDFJF). The TMDFJF is factorized into collinear and collinear soft modes by matching onto SCET${}_{+}$. We resum large logarithms in $E_J/p_{h\perp }$, where $E_J$ is the ungroomed jet energy, to NLL accuracy and apply this formalism for computing the shape of the $p_{h\perp }$ distribution of a pion produced in an $e^{+}+e^{-}$ collision. We observe that the introduction of grooming makes this observable insensitive to non-global logarithms and particularly sensitive to non-perturbative physics of the transverse momentum dependent evolution at low values of $p_{h\perp }$, which can be probed in the variation of the cut-off parameter $z_{cut}$ of the groomer. We discuss how this observable can be used to distinguish between non-perturbative models that describe universal TMD evolution and provide a window into the three dimensional structure of hadrons.

    hep-phnucl-thJHEP(2018)·38 citations
31. 31*

    Resummed Photon Spectra for WIMP Annihilation

    Matthew Baumgart🇺🇸 · Timothy Cohen🇺🇸 · Ian Moult🇺🇸 · Nicholas L. Rodd🇺🇸 · Tracy R. Slatyer🇺🇸 · Mikhail P. Solon🇺🇸 · Iain W. Stewart🇺🇸 · Varun Vaidya🇺🇸

    We construct an effective field theory (EFT) description of the hard photon spectrum for heavy WIMP annihilation. This facilitates precision predictions relevant for line searches, and allows the incorporation of non-trivial energy resolution effects. Our framework combines techniques from non-relativistic EFTs and soft-collinear effective theory (SCET), as well as its multi-scale extensions that have been recently introduced for studying jet substructure. We find a number of interesting features, including the simultaneous presence of SCET${}_{\text{I}}$ and SCET${}_{\text{II}}$ modes, as well as collinear-soft modes at the electroweak scale. We derive a factorization formula that enables both the resummation of the leading large Sudakov double logarithms that appear in the perturbative spectrum, and the inclusion of Sommerfeld enhancement effects. Consistency of this factorization is demonstrated to leading logarithmic order through explicit calculation. Our final result contains both the exclusive and the inclusive limits, thereby providing a unifying description of these two previously-considered approximations. We estimate the impact on experimental sensitivity, focusing for concreteness on an SU(2)${}_W$ triplet fermion dark matter - the pure wino - where the strongest constraints are due to a search for gamma-ray lines from the Galactic Center. We find numerically significant corrections compared to previous results, thereby highlighting the importance of accounting for the photon spectrum when interpreting data from current and future indirect detection experiments.

    hep-phastro-ph.COastro-ph.HEnucl-thJHEP(2018)·75 citations
32. 32*

    Black Hole Genesis of Dark Matter

    Olivier Lennon🇬🇧 · John March-Russell🇬🇧 · Rudin Petrossian-Byrne🇬🇧 · Hannah Tillim🇬🇧

    We present a purely gravitational infra-red-calculable production mechanism for dark matter (DM). The source of both the DM relic abundance and the hot Standard Model (SM) plasma is a primordial density of micro black holes (BHs), which evaporate via Hawking emission into both the dark and SM sectors. The mechanism has four qualitatively different regimes depending upon whether the BH evaporation is `fast' or `slow' relative to the initial Hubble rate, and whether the mass of the DM particle is `light' or `heavy' compared to the initial BH temperature. For each of these regimes we calculate the DM yield, $Y$, as a function of the initial state and DM mass and spin. In the `slow' regime $Y$ depends on only the initial BH mass over a wide range of initial conditions, including scenarios where the BHs are a small fraction of the initial energy density. The DM is produced with a highly non-thermal energy spectrum, leading in the `light' DM mass regime ($\sim 260\mathrm{eV}$ and above depending on DM spin) to a strong constraint from free-streaming, but also possible observational signatures in structure formation in the spin 3/2 and 2 cases. The `heavy' regime ($\sim 1.2\times 10^8\mathrm{GeV}$ to $M_{\mathrm{Pl}}$ depending on spin) is free of these constraints and provides new possibilities for DM detection. In all cases there is a dark radiation component predicted.

    hep-phastro-ph.COgr-qcJCAP(2018)·183 citations
33. 33*

    Strong magnetic fields in compact stars as a macroscopic parity violation phenomenon

    Maxim Dvornikov (IZMIRAN, Tomsk State University)🇷🇺

    We review the results in our recent works on the generation of strong magnetic fields in compact stars driven by the parity violating electroweak interactions between background fermions. The cases of a neutron star, a hybrid star, and a quark star are considered. We formulate the system of kinetic equations for the description of the spectra of the magnetic energy and the magnetic helicity, as well as for the chiral imbalances. Turbulence effects, which can be important for the evolution of small-scale magnetic field, are also taken into account. We find the numerical solution of these equations in case of large- and small-scale magnetic fields in quark matter. The applications of the obtained results for the generation of large-scale magnetic fields in magnetars and for the explanation of magnetar bursts are discussed.

    ↳ astro-ph.HEhep-ph0 citations
34. 34*

    Dual representation of lattice QCD with worldlines and worldsheets of abelian color fluxes

    Carlotta Marchis🇦🇹 · Christof Gattringer🇦🇹

    We present a new dual representation for lattice QCD in terms of wordlines and worldsheets. The exact reformulation is carried out using the recently developed abelian color flux method where the action is decomposed into commuting minimal terms that connect different colors on neighboring sites. Expanding the Boltzmann factors for these commuting terms allows one to reorganize the gauge field contributions according to links such that the gauge fields can be integrated out in closed form. The emerging constraints give the dual variables the structure of worldlines for the fermions and worldsheets for the gauge degrees of freedom. The partition sum has the form of a strong coupling expansion and with the abelian color flux approach discussed here all coefficients of the expansion are known in closed form. We present the dual form for three cases: pure SU(3) lattice gauge theory, strong coupling QCD and full QCD, and discuss in detail the constraints for the color fluxes and their physical interpretation.

    ↳ hep-lathep-phhep-thPRD(2018)·29 citations
35. 35*

    The nonplanar cusp and collinear anomalous dimension at four loops in $\mathcal{N}=4$ SYM theory

    Rutger H. Boels🇩🇪 · Tobias Huber🇩🇪 · Gang Yang🇨🇳

    We present numerical results for the nonplanar lightlike cusp and collinear anomalous dimension at four loops in $\mathcal{N}=4$ SYM theory, which we infer from a calculation of the Sudakov form factor. The latter is expressed as a rational linear combination of uniformly transcendental integrals for arbitrary colour factor. Numerical integration in the nonplanar sector reveals explicitly the breakdown of quadratic Casimir scaling at the four-loop order. A thorough analysis of the reported numerical uncertainties is carried out.

    ↳ hep-thhep-phPoS(2017)·9 citations
36. 36*

    Riemann-Theta Boltzmann Machine

    Daniel Krefl🇨🇭 · Stefano Carrazza🇨🇭 · Babak Haghighat🇨🇳 · Jens Kahlen🇩🇪

    A general Boltzmann machine with continuous visible and discrete integer valued hidden states is introduced. Under mild assumptions about the connection matrices, the probability density function of the visible units can be solved for analytically, yielding a novel parametric density function involving a ratio of Riemann-Theta functions. The conditional expectation of a hidden state for given visible states can also be calculated analytically, yielding a derivative of the logarithmic Riemann-Theta function. The conditional expectation can be used as activation function in a feedforward neural network, thereby increasing the modelling capacity of the network. Both the Boltzmann machine and the derived feedforward neural network can be successfully trained via standard gradient- and non-gradient-based optimization techniques.

    ↳ stat.MLcs.LGhep-phhep-th+1Neurocomput.(2020)·4 citations
37. 37*

    Probing large-scale magnetism with the Cosmic Microwave Background

    Massimo Giovannini🇨🇭

    Prior to photon decoupling magnetic random fields of comoving intensity in the nano-Gauss range distort the temperature and the polarization anisotropies of the microwave background, potentially induce a peculiar B-mode power spectrum and may even generate a frequency-dependent circularly polarized V-mode. We critically analyze the theoretical foundations and the recent achievements of an interesting trialogue involving plasma physics, general relativity and astrophysics.

    ↳ astro-ph.COgr-qchep-phClass.Quant.Grav.(2018)·24 citations
38. 38*

    Medium effects on freeze-out of light clusters at NICA energies

    G. Roepke🇩🇪 · D. Blaschke🇷🇺 · Yu. B. Ivanov🇷🇺 · Iu. Karpenko🇫🇷 · O. V. Rogachevsky🇷🇺 · H. H. Wolter🇩🇪

    We estimate the chemical freeze-out of light nuclear clusters for NICA energies of above 2 A GeV. On the one hand we use results from the low energy domain of about 35 A MeV, where medium effects have been shown to be important to explain experimental results. On the high energy side of LHC energies the statistical model without medium effects has provided results for the chemical freeze-out. The two approaches extrapolated to NICA energies show a discrepancy that can be attributed to medium effects and that for the deuteron/proton ratio amounts to a factor of about three. These findings underline the importance of a detailed investigation of light cluster production at NICA energies.

    ↳ nucl-thhep-phPhys.Part.Nucl.Lett.(2018)·11 citations
39. 39*

    Loop-Induced Stochastic Bias at Small Wavevectors

    Michael McAneny🇺🇸 · Alexander K. Ridgway🇺🇸 · Mikhail P. Solon🇺🇸 · Mark B. Wise🇺🇸

    Primordial non-Gaussianities enhanced at small wavevectors can induce a power spectrum of the galaxy overdensity that differs greatly from that of the matter overdensity at large length scales. In previous work, it was shown that "squeezed" three-point and "collapsed" four-point functions of the curvature perturbation $\zeta$ can generate these non-Gaussianities and give rise to so-called scale-dependent and stochastic bias in the galaxy overdensity power spectrum. We explore a third way to generate non-Gaussianities enhanced at small wavevectors: the infrared behavior of quantum loop contributions to the four-point correlations of $\zeta$. We show that these loop effects lead to stochastic bias, which can be observable in the context of quasi-single field inflation.

    ↳ astro-ph.COhep-phPLB(2018)·8 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.