Tue·Dec 4, 2018Tuesday·December 4, 2018

1. 01*

   Selected updates on semileptonic $B$ decays and $|V_{xb}|$ determination

   Giulia Ricciardi🇮🇹

   We summarize selected up-to-date results related to semileptonic $B$ meson decays, namely results on the exclusive determination of the parameter $|V_{cb}|$ of the CKM matrix, on the inclusive determination of $|V_{ub}|$, and on $R(D^{(\ast )})$.

   hep-phPoS(2019)·3 citations
2. 02*

   Searching for the dead cone effects with iterative declustering of heavy-flavor jets

   Leticia Cunqueiro🇺🇸 · Mateusz Ploskon🇺🇸

   We present a new method to expose the dead cone effect at colliders using iterative declustering techniques. Iterative declustering allows to unwind the jet clustering and to access the subjets or branches at different depths of the jet tree. Our method consists on declustering the heavy flavour-tagged jet using Cambridge-Achen algorithm following the branch containing the heavy flavour at each step and registering the kinematics of the complementary untagged prong. The kinematics of the complementary untagged prong fill a Lund map representing the gluon radiation off the heavy flavour quark at each step of the vacuum shower. Using Pythia8 MC, we show that a simple cut on the Lund plane introduced by log($k_T$) $>0$, suppresses hadronisation effects and the angular separation between the jet prongs becomes very sensitive to flavour effects. A clear suppression for heavy flavour jets relative to inclusive jets in the region of splitting angles delimited by the relation $\theta <m_Q/E$ is observed, where $m_Q$ is the mass of the heavy quark and $E$ is the energy of the radiator or splitting prong.

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

   A Light Scalar in the Minimal Dilaton Model in Light of LHC Constraints

   Lijia Liu🇨🇳 · Haoxue Qiao🇨🇳 · Kun Wang🇨🇳 · Jingya Zhu🇨🇳

   Whether an additional light scalar exists is an interesting topic beyond the Standard Model (SM), while nowadays we do not know exactly physics beyond the SM in the low mass region, e.g., the Atlas and CMS collaborations get inconsistent results at around 95 GeV in searching for light resonances in diphoton channel. Considering these, we study a light scalar in the Minimal Dilaton Model (MDM). Under the theoretical and latest experimental constraints, we sort the surviving samples into two scenarios according to the diphoton rate of the light scalar: the large-diphoton scenario (with $/SM\gtrsim 0.2$) and the small-diphoton scenario (with $/SM\lesssim 0.2$), which are favored by CMS and Atlas results respectively. We compare the two scenarios, check the characteristics in model parameters, scalar couplings, production and decay, and consider further distinguishing them at colliders. Finally, we get the following conclusions for the two scenarios: (i) The formal usually has small Higgs-dilaton mixing angle ($|\sin {\theta }_S|\lesssim 0.2$) and small dilaton vacuum expectation value (VEV) $f$ ($0.5\lesssim \eta \equiv v/f\lesssim 1$), and the later usually has large mixing ($|\sin {\theta }_S|\gtrsim 0.4$) or large VEV ($\eta \equiv v/f\lesssim 0.3$). (ii) The former usually predicts small $s\gamma \gamma$ coupling ($|C_{s\gamma \gamma }/SM|\lesssim 0.3$) and large $sgg$ coupling ($0.6\lesssim |C_{sgg}/SM|\lesssim 1.2$), while the later usually predicts small $sgg$ coupling ($|C_{sgg}/SM|\lesssim 0.5$). (iii) The former can interpret the small diphoton excess by CMS at its central value, when $m_s\simeq$95GeV, $\eta \simeq 0.6$ and $|\sin {\theta }_S|\simeq 0$. (iv) The former usually predicts a negative correlation between Higgs couplings $|C_{h\gamma \gamma }/SM|$ and $|C_{hgg}/SM|$, while the later usually predicts the two couplings both smaller than 1, or $|C_{h\gamma \gamma }/SM|\lesssim 0.9\lesssim |C_{hgg}/SM|$.

   hep-phhep-exCPC(2019)·29 citations
4. 04*

   Tensor pomeron, vector odderon and diffractive production of meson and baryon pairs in proton-proton collisions

   Piotr Lebiedowicz🇵🇱 · Otto Nachtmann🇩🇪 · Antoni Szczurek🇵🇱

   We review some selected results of the tensor-pomeron and vector-odderon model of soft high-energy proton-proton scattering and central exclusive production of meson and baryon pairs in proton-proton collisions. We discuss the theoretical aspects of this approach and consider the phenomenological implications in a variety of processes at high energies, comparing to existing experimental data. We consider the diffractive dipion and dikaon production including the continuum and the dominant scalar and tensor resonance contributions as well as the photoproduction processes. The theoretical results are compared with existing CDF experimental data and predictions for planned or current LHC experiments, ALICE, ATLAS, CMS, LHCb are presented.

   hep-phEPJ Web Conf.(2019)·5 citations
5. 05*

   Impact of final state interactions on neutrino-nucleon pion production cross sections extracted from neutrino-deuteron reaction data

   S.X. Nakamura (Univ. Science and Technology of China, Univ. Cruzeiro do Sul)🇧🇷 · H. Kamano (RCNP)🇯🇵 · T. Sato (RCNP, J-PARC)🇯🇵

   The current and near-future neutrino oscillation experiments require significantly improved neutrino-nucleus reaction models. Neutrino-nucleon pion production data play a crucial role to validate corresponding elementary amplitudes that go into such neutrino-nucleus models. Thus the currently available data extracted from charged-current neutrino-deuteron reaction data (${\nu }_{\mu }d\to {\mu }^{-}\pi NN$) must be corrected for nuclear effects such as the Fermi motion and final state interactions (FSI). We study ${\nu }_{\mu }d\to {\mu }^{-}\pi NN$ with a theoretical model including the impulse mechanism supplemented by FSI from $NN$ and $\pi N$ rescatterings. An analysis of the spectator momentum distributions reveals that the FSI effects significantly reduce the spectra over the quasi-free peak region, and leads to a useful recipe to extract information of elementary ${\nu }_{\mu }N\to {\mu }^{-}\pi N$ processes using ${\nu }_{\mu }d\to {\mu }^{-}\pi NN$ data, with the important FSI corrections taken into account. We provide ${\nu }_{\mu }N\to {\mu }^{-}\pi N$ total cross sections by correcting the deuterium bubble chamber data for the FSI and Fermi motion. The results will bring a significant improvement on neutrino-nucleus reaction models for the near-future neutrino-oscillation experiments.

   hep-phhep-exnucl-thPRD(2019)·24 citations
6. 06*

   Two-photon decay of P-wave positronium: a tutorial

   Abhijit Sen🇷🇺 · Zurab K. Silagadze🇷🇺

   A detailed exposition of two-photon decays of P-wave positronium is given to fill an existing gap in the pedagogical literature. Annihilation decay rates of P-wave positronium are negligible compared to the rates of radiative electric dipole transitions to the ground state. This circumstance makes such decays experimentally inaccessible. However the situation is different for quarkonium and the experimental and theoretical research of two-photon and two-gluon decays of P-wave quarkonia is a still flourishing field.

   hep-phhep-thCan.J.Phys.(2019)·7 citations
7. 07*

   Bounds on rare decays of $\eta$ and ${\eta }^{\prime }$ mesons from the neutron EDM

   Alexey S. Zhevlakov🇷🇺 · Mikhail Gorchtein🇩🇪 · Astrid N. Hiller Blin🇩🇪 · Thomas Gutsche🇩🇪 · Valery E. Lyubovitskij🇩🇪

   We provide model-independent bounds on the rates of rare decays $\eta ({\eta }^{\prime })\to \pi \pi$ based on experimental limits on the neutron electric dipole moment (nEDM). Starting from phenomenological $\eta ({\eta }^{\prime })\pi \pi$ couplings, the nEDM arises at two loop level. The leading-order relativistic ChPT calculation with the minimal photon coupling to charged pions and a proton inside the loops leads to a finite, counter term-free result. This is an improvement upon previous estimates which used approximations in evaluating the two loop contribution and were plagued by divergences. While constraints on the $\eta ({\eta }^{\prime })\pi \pi$ couplings in our phenomenological approach are somewhat milder than in the picture with the QCD $\theta$-term, our calculation means that whatever the origin of these couplings, The decays $\eta ({\eta }^{\prime })\to 2\pi$ will remain unobservable in the near future.

   hep-phPRD(2019)·24 citations
8. 08*

   Coupled-Channel-Induced $S-D$ mixing of Charmonia and Testing Possible Assignments for $Y(4260)$ and $Y(4360)$

   Hui-feng Fu🇨🇳 · Libo Jiang🇺🇸

   The mass spectrum and the two-body open-charm decays of the $J^{PC}=1^{--}$ charmonium states are studied with the coupled-channel effects taken into account. The coupled-channel-induced mixing effects among the excited vector charmonia are studied. Based on our calculations of the masses and the decay widths, we find that the tension between the observed properties of $Y(4260)/Y(4360)$ and their conventional charmonia interpretations could be softened.

   hep-phEPJC(2019)·13 citations
9. 09*

   Gravitational production of super-Hubble-mass particles: an analytic approach

   Daniel J. H. Chung🇺🇸 · Edward W. Kolb🇺🇸 · Andrew J. Long🇺🇸

   Through a mechanism similar to perturbative particle scattering, particles of mass $m_{\chi }$ larger than the Hubble expansion rate $H_{\inf }$ during inflation can be gravitationally produced at the end of inflation without the exponential suppression powers of $\exp (-m_{\chi }/H_{\inf })$. Here we develop an analytic formalism for computing particle production for such massive particles. We apply our formalism to specific models that have been previously been studied only numerically, and we find that our analytical approximations reproduce those numerical estimates well.

   hep-phastro-ph.COhep-thJHEP(2019)·89 citations
10. 10*

    NLO Effects in EFT Fits to $W^{+}{W}^{-}$ Production at the LHC

    Julien Baglio🇩🇪 · Sally Dawson🇺🇸 · Ian M. Lewis🇺🇸

    We study the impact of anomalous gauge boson and fermion couplings on the production of $W^{+}{W}^{-}$ pairs at potential future LHC upgrades and estimate the sensitivity at $\sqrt{S}=14$ TeV with $3a{b}^{-1}$ and $\sqrt{S}=27$ TeV with $15a{b}^{-1}$. A general technique for including NLO QCD effects in effective field theory (EFT) fits to kinematic distributions is presented, and numerical results are given for $\sqrt{S}=13$ TeV $W^{+}{W}^{-}$ production. Our method allows fits to anomalous couplings at NLO accuracy in any EFT basis and has been implemented in a publicly available version of the POWHEG-BOX. Analytic expressions for the $K$-factors relevant for $13$ TeV total cross sections are given for the HISZ and Warsaw EFT bases and differential $K$-factors can be obtained using the supplemental material. Our study demonstrates the necessity of including anomalous $Z$- fermion couplings in the extraction of limits on anomalous 3-gauge-boson couplings.

    hep-phPRD(2019)·59 citations
11. 11*

    See-Saw Mechanism in the 2HDM through the simultaneous introduction of a singlet and triplet of Majorana

    Julian Steven Gutierrez🇨🇴 · Carlos Jose Quimbay🇨🇴

    We consider the minimum extension of the SM denominated 2HDM-III, in which,it new coupling constants to the new Higgs field in the Lagrangian of Yukawa are added furtheremore a Majorana mass in generated via See-Saw mechanism SSM-I thus, the effective masses of the Dirac and Majorana neutrinos will be sensitive to te VEV of Higgs doublets and to the structure of the Yukawa constants. Then we consider the MSS-III,in which a $Z_2$ symmetry is imposed to Lagrangian 2HDM-III to attach a doublet to the particles of the SM, and the other doublet to the triplet of fermions included in this mechanism. Finally, the MSS-I+III is simultaneously implemented in the M2DH-III. This is important because the additional heavy fermions in the adjoint representation of the weak isoespin group $SU(2)$ allows them to interact with the gauge bosons, facilitating their production in the colliding experiments.

    hep-ph0 citations
12. 12*

    Longitudinal structure function FL at small x extracted from the Berger-Block-Tan parametrization of F2

    L.P. Kaptari🇨🇳 · A.V. Kotikov🇨🇳 · N.Yu. Chernikova🇷🇺 · Pengming Zhang🇨🇳

    The longitudinal structure function FL(x,Q2) is extracted at low values of the Bjorken variable x from the Berger-Block-Tan parametrization of F2(x,Q2). The obtained FL(x,Q2) does not violate the high-energy asymptotic Froissart boundary and is in a reasonable good agreement with the available experimental data.

    hep-phJETP Lett.(2019)·17 citations
13. 13*

    Recent Progress in QCD Condensate Evaluations and Sum Rules

    Philipp Gubler🇯🇵 · Daisuke Satow🇯🇵

    We review the recent status of the QCD sum rule approach to study the properties of hadrons in vacuum and in hot or dense matter. Special focus is laid on the progress made in the evaluation of the QCD condensates, which are the input of all QCD sum rule calculations, and for which much new information has become available through high precision lattice QCD calculations, chiral perturbation theory and experimental measurements. Furthermore, we critically examine common analysis methods for QCD sum rules and contrast them with potential alternative strategies. The status of QCD sum rule studies investigating the modification of hadrons at finite density as well as recent derivations of exact sum rules applicable to finite temperature spectral functions, are also reviewed.

    hep-phhep-exhep-latnucl-ex+1PPNP(2019)·136 citations
14. 14*

    How to measure the linear polarization of gluons in unpolarized proton using the heavy-quark pair production

    N. Ya. Ivanov🇦🇲 · A. V. Efremov🇷🇺 · O. V. Teryaev🇷🇺

    In recent papers [1,2], two new ways have been proposed to probe the linear polarization of gluons in unpolarized proton: using the azimuthal asymmetries and Callan-Gross ratio in heavy-quark pair leptoproduction, $lN\to l^{\prime }Q\bar{Q}X$. In this talk, we discuss in details the sensitivity of the QCD predictions for the azimuthal $\cos \phi$ and $\cos 2\phi$ asymmetries to the contribution of linearly polarized gluons inside unpolarized proton, where the azimuth $\phi$ is the angle between the lepton scattering plane $(l,l^{\prime })$ and the heavy quark production plane $(N,Q)$. Our analysis shows that the azimuthal distributions under consideration vary from 0 to 1 depending on the transverse-momentum dependent gluonic counterpart of the Boer-Mulders function, $h_1^{\perp g}$. We conclude that the $\cos \phi$ and $\cos 2\phi$ asymmetries in heavy-quark pair production in DIS processes are predicted to be large in wide kinematic ranges and sensitive to the contribution of linearly polarized gluons.

    hep-phEPJ Web Conf.(2019)·3 citations
15. 15*

    Study of the isospin breaking decay $\mathbf{Y}(2175)\to \mathbf{\varphi }{\mathbf{f}}_0(980)\to \mathbf{\varphi \eta }{\mathbf{\pi }}^0$ at BESIII

    Xiao-Dong Cheng🇨🇳 · Hai-Bo Li🇨🇳 · Ru-Min Wang🇨🇳 · Mao-Zhi Yang🇨🇳

    Using measured branching fraction of the decay $J/\psi \to \eta Y(2175))\to \eta \varphi f_0(980)\to \eta \varphi {\pi }^{+}{\pi }^{-}$ from the BESIII experiment, we estimate branching fraction of $J/\psi \to \eta Y(2175))\to \eta \varphi f_0(980)\to \eta \varphi \eta {\pi }^0$ decay, which proceeds via the $f_0(980)$-$a_0^0(980)$ mixing and the ${\pi }^0$-$\eta$ mixing. The branching fraction is predicted to be about $O(10^{-6})$, which can be accessed with $10^{10}$ $J/\psi$ events collected at the BESIII. The decay is dominated by the contribution from $f_0(980)$-$a_0^0(980)$ mixing. We find that the interference between the amplitudes due to $f_0(980)$-$a_0^0(980)$ mixing and that due to ${\pi }^0$-$\eta$ mixing is destructive. The branching fraction can be decreased by about $10\%$ owing to the interference effect. We also study the $\eta {\pi }^0$ mass squared spectrum, and find that a narrow peak due to the $f_0(980)$-$a_0^0(980)$ mixing in the $\eta {\pi }^0$ mass squared spectrum should be observed. The observation of this decay in experiment will be helpful to determine the $f_0(980)$-$a_0^0(980)$ mixing intensity and get information about the structures of the light scalar mesons.

    hep-phPRD(2019)·6 citations
16. 16*

    Electromagnetic dipole moment and time reversal invariance violating interactions for high energy short-lived particles in bent and straight crystals at Large Hadron Collider

    V.G. Baryshevsky🇧🇾

    A channelled particle, which moves in a crystal, alongside with electromagnetic interaction also experiences weak interaction with electrons and nuclei, as well as strong interaction with nuclei. Measurements of polarization vector and angular distribution of particles scattered by axes (planes) of unbent crystal enable to obtain limits for the EDM value and for values of constants describing P- and T-odd interactions. The same measurements also allow studying magnetic dipole moment of charged and neutral particles. Investigation of left-right asymmetry by the use of two unbent crystals makes it possible to measure EDM, MDM and other constants without studying the angular distribution of decay products of scattered particles: it is sufficient to measure the intensity of flow of particles experienced double scattering. Spin precession of channelled particles in bent crystals at the LHC gives unique possibility for measurement of constants determining T-odd, P-odd (CP) violating interactions and P-odd, T-even interactions of baryons with electrons and nucleus (nucleons), similarly to the possibility of measuring electric and magnetic moments of charm, beauty and strange charged baryons. Methods to separate P-noninvariant rotation from the MDM- and EDM-induced (T-odd) spin rotations are discussed.

    hep-phhep-exPhys.Rev.Accel.Beams(2019)·8 citations
17. 17*

    Diffractive gauge boson production at the LHC as a probe of the flavour content of the Pomeron

    E. A. F. Basso🇧🇷 · V. P. Goncalves🇧🇷 · D. E. Martins🇧🇷 · M. S. Rangel🇧🇷

    The production of the $W$ and $Z$ bosons in single diffractive processes at the LHC is investigated taking into account the ATLAS, CMS and LHCb acceptances and considering different assumptions for the flavour content of the Pomeron. The total cross sections and pseudorapidity distributions are estimated for $pp$ collisions at $\sqrt{s}=13$ TeV. Our results indicate that a future experimental analysis of the ratio between the $W$ and $Z$ cross sections can be used to probe the flavour content of the Pomeron.

    hep-phPRD(2019)·1 citation
18. 18*

    Finite-energy dressed string-inspired Dirac-like monopoles

    Nick E. Mavromatos🇬🇧 · Sarben Sarkar🇬🇧

    On extending the Standard Model (SM) Lagrangian, through a non-linear Born-Infeld (BI) hypercharge term with a parameter $\beta$ (of dimensions of [mass]${}^2$), a finite energy monopole solution was claimed by Arunasalam and Kobakhidze [1]. We report on a new class of solutions within this framework which was missed in the earlier analysis. This new class was discovered on performing consistent analytic asymptotic analyses of the nonlinear differential equations describing the model; the shooting method used in numerical solutions to boundary value problems for ordinary differential equations is replaced in our approach by a method which uses diagonal Padé approximants. Our work uses the ansatz proposed by Cho and Maison to generate a static and spherically symmetric monopole with finite energy and differs from that used in the solution of [1]. Estimates of the total energy of the monopole are given, and detection prospects at colliders are briefly discussed.

    hep-phhep-thUniverse(2018)·28 citations
19. 19*

    Spontaneous CPT Violation and Quantum Anomalies in a Model for Matter-Antimatter Asymmetry in the Cosmos

    Nick E. Mavromatos🇬🇧 · Sarben Sarkar🇬🇧

    We review scenarios of baryogenesis through leptogenesis at early epochs of the universe, in string-inspired minimal extensions of the Standard Model (SM), involving heavy right-handed Majorana neutrinos. Spontaneous violation of CPT symmetry is induced by appropriate (in general, temperature-dependent) backgrounds of the Kalb-Ramond (KR) axion field, which has its origins in the (bosonic) massless string multiplet. As interesting features of the model, we also discuss two issues associated with quantum (chiral) anomalies: (i) the non-contribution of the KR axion background to the (anomalous) chiral magnetic effect, which arises in the presence of external electromagnetic fields and non-zero chiral chemical potentials of charged fermions and (ii) the potential rôle of quantum fluctuations of the KR axion on the (anomalous) radiative generation of a Majorana mass for the right-handed neutrinos themselves.

    hep-phgr-qchep-thUniverse(2018)·25 citations
20. 20*

    Review of phenomenological analyses of ${\eta }^{(\prime )}\pi$ resonances

    A. Rodas🇪🇸 · A. Pilloni🇺🇸 · A. Szczepaniak🇺🇸

    We present a robust analysis of the ${\eta }^{(\prime )}\pi$ system in COMPASS data. We fit the extracted relative phases and intensities with a coupled-channel formalism enforcing both unitarity and analyticity. We provide a robust extraction of a single exotic ${\pi }_1(1600)$ decaying to both ${\eta }^{(\prime )}\pi$ final states, and the resonance parameters of the $a_2(1320)$ and $a_2^{\prime }(1700)$. We find no evidence for a second exotic state, which is compatible with recent Lattice QCD estimates.

    hep-phhep-exPoS(2018)·0 citations
21. 21*

    Consistent origin of neutrino mass and freeze-in dark matter in large N theories

    Zhi-Long Han🇨🇳 · Bin Zhu🇨🇳 · Ligong Bian🇨🇳 · Ran Ding🇨🇳

    Most of what we concern in beyond standard phenomenology are the existence of tiny numbers. The well-defined principle for protecting the tiny number to be large from quantum correction is supersymmetry. However, such a nice framework is challenged by the non-observation of superpartners at LHC. Instead, we propose a new principle to realize a natural framework to explain the smallness of feebly interaction dark matter coupling and neutrino mass. The scalar sector as well as gauge sector must be extended to include $N$ copies as a price. It is found in this paper that the yukawa coupling $y$ as well as quartic coupling $\lambda$ scales with inverse power of $N$ to maintain perturbativity. In terms of the scaling behavior of couplings, the freeze-in dark matter becomes compatible with neutrino mass requirement. The biggest observation is that $y$ has to be evaluated by $1/N^{3/2}$ in type-I seesaw mechanism in order to obtain a large $N$ suppressed neutrino mass. The intrinsic hierarchy between $1/\sqrt{N}$ and $1/N^{3/2}$ for yukawa coupling $y$ can be improved if we focus on the loop generated neutrino mass which can be relaxed to be $1/N$. The underlying reason for not use $1/\sqrt{N}$ is that freeze-in dark matter provides a lower bound for the scaling. Therefore the only choice of scaling for yukawa coupling is left to be $1/N$. Based on this simple scaling, we realiza an unified framework for explaining FIMP and neutrino mass.

    hep-ph4 citations
22. 22*

    Properties of protons in nuclear medium with AdS/QCD model with a quadratic modified dilaton

    Alfredo Vega🇨🇱 · M. A. Martin Contreras🇨🇱

    A modified version of the usual soft wall quadratic dilaton, a dilaton which catches the variation of the proton mass inside nucleons in the nuclear medium is used. With this dilaton, called nuclear dilaton, we have calculated the electromagnetic form factors and magnetic moments associated with the in-medium proton following the AdS/QCD prescription.

    hep-phhep-thEPJA(2021)·7 citations
23. 23*

    Gamma-rays and LHC-inspired dark matter

    Geoff Beck🇿🇦 · Sergio Colafrancesco🇿🇦

    The Madala hypothesis was formulated to explain anomalies in LHC data from run-1. Subsequently, these anomalies have endured into run-2 and been strengthened. This makes the analysis of the proposal highly pertinent, and, since some of the properties of the model are beyond the reach of current collider data it is also important to determine alternative means of analysis. Here, we examine the consequences of WIMPs linked to the Madala hypothesis providing a dark matter candidate and annihilating in the galactic centre of the Milky-Way and the Andromeda galaxy. These targets have been observed to have similar gamma-ray spectra by Fermi-LAT and their emissions have been widely discussed in terms of dark matter annihilation in the literature. We show that, when the decay branchings of the hidden-sector mediator in the Madala hypothesis are assumed Higgs-like, the emissions of Andromeda and the Milky-Way are not compatible with both being produced by dark matter annihilation, apart from when a steeply contracted NFW profile is assumed for the halos or the WIMP has a mass above 1 TeV. Additionally, similar results are displayed for a wide variety of model independent cases

    hep-phPoS(2018)·1 citation
24. 24*

    Searching for production of dark matter in association with top quarks at the LHC

    Ulrich Haisch🇩🇪 · Giacomo Polesello🇮🇹

    In the framework of spin-0 $s$-channel dark matter (DM) simplified models, we reassess the sensitivity of future LHC runs to the production of DM in association with top quarks. We consider two different missing transverse energy ($E_T^{\mathrm{miss}}$) signatures, namely production of DM in association with either a $t\bar{t}$ pair or a top quark and a $W$ boson, where the latter channel has not been the focus of a dedicated analysis prior to this work. Final states with two leptons are studied and a realistic analysis strategy is developed that simultaneously takes into account both channels. Compared to other existing search strategies the proposed combination of $t\bar{t}+E_T^{\mathrm{miss}}$ and $tW+E_T^{\mathrm{miss}}$ production provides a significantly improved coverage of the parameter space of spin-0 $s$-channel DM simplified models.

    hep-phhep-exJHEP(2019)·29 citations
25. 25*

    Three Neutrino Oscillations in Uniform Matter

    Ara Ioannisian🇦🇲 · Stefan Pokorski🇵🇱

    Following similar approaches in the past, the Schrodinger equation for three neutrino propagation in matter of constant density is solved analytically by two successive diagonalizations of 2x2 matrices. The final result for the oscillation probabilities is obtained directly in the conventional parametric form as in the vacuum but with explicit simple modification of two mixing angles (${\theta }_{12}$ and ${\theta }_{13}$) and mass eigenvalues.

    hep-phPoS(2019)·0 citations
26. 26*

    On the amplitudes for the CP-conserving $K^{\pm }(K_S)\to {\pi }^{\pm }({\pi }^0){\ell }^{+}{\ell }^{-}$ rare decay modes

    Giancarlo D'Ambrosio🇮🇹 · David Greynat🇫🇷 · Marc Knecht🇫🇷

    The amplitudes for the rare decay modes $K^{\pm }\to {\pi }^{\pm }{\ell }^{+}{\ell }^{-}$ and $K_S\to {\pi }^0{\ell }^{+}{\ell }^{-}$ are studied with the aim of obtaining predictions for them, such as to enable the possibility to search for violations of lepton-flavour universality in the kaon sector. The issue is first addressed from the perspective of the low-energy expansion, and a two-loop representation of the corresponding form factors is constructed, leaving as unknown quantities their values and slopes at vanishing momentum transfer. In a second step a phenomenological determination of the latter is proposed. It consists of the contribution of the resonant two-pion state in the $P$ wave, and of the leading short-distance contribution determined by the operator-product expansion. The interpolation between the two energy regimes is described by an infinite tower of zero-width resonances matching the QCD short-distance behaviour. Finally, perspectives for future improvements in the theoretical understanding of these amplitudes are discussed.

    hep-phhep-exhep-latJHEP(2019)·37 citations
27. 27*

    Chiral imbalanced hot and dense quark matter: NJL analysis at the physical point and comparison with lattice QCD

    T. G. Khunjua🇷🇺 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

    Hot and dense quark matter with isospin and chiral imbalances is investigated in the framework of the (3+1)-dimensional Nambu--Jona-Lasinio model (NJL) in the large-$N_c$ limit ($N_c$ is the number of quark colors). Its phase structure is considered in terms of baryon -- ${\mu }_B$, isospin -- ${\mu }_I$ and chiral isospin -- ${\mu }_{I5}$ chemical potentials. It is shown in the paper that (i) in the chiral limit there is a duality between chiral symmetry breaking (CSB) and charged pion condensation (PC) phenomena. (ii) At the physical point, i.e. at nonzero bare quark mass $m_0$, and temperature this duality relation is only approximate, although rather accurate. (iii) We have shown that the chiral isospin chemical potential ${\mu }_{I5}$ in dense quark matter generates charged pion condensation both at zero and nonzero $m_0$, and at ${\mu }_{I5}\ne 0$ this phase might be observed up to temperatures as high as 100 MeV. (iv) Pseudo-critical temperature of the chiral crossover transition rises in the NJL model with increasing ${\mu }_{I5}$. (v) It has been found an agreement between particular sections of the phase diagram in the framework of NJL model and corresponding ones in lattice QCD simulations. Two different plots from different lattice simulations that are completely independent and are not connected at the first sight are in reality dual to each other, it means that lattice QCD simulations support the hypothesis that in real quark matter there exists the (approximate) duality between CSB and charged PC. Moreover, we can reverse the logic and we can predict the increase of pseudo-critical temperature with chiral chemical potential, the much debated effect recently, just by the duality notion, hence bolster confidence in this result (lattice QCD showed this feature for unphysically large pion mass) and put it on the considerably more solid ground.

    hep-phhep-latEPJC(2019)·49 citations
28. 28*

    Lepton collider signatures of dark CP violation

    A. Cordero-Cid🇲🇽 · J. Hernández-Sánchez🇲🇽 · V. Keus🇫🇮 · S. Moretti🇬🇧 · D. Rojas🇲🇽 · D. Sokołowska🇵🇱

    We study an extension of the Standard Model (SM) in which two copies of the SM Higgs doublet are added to the scalar sector. These extra doublets do not develop a vacuum expectation value, hence, they are \textit{inert}. This essentially leads to a 3-Higgs Doublet Model (3HDM) with 2 inert and 1 active scalar doublets, which we denote as I(2+1)HDM. We allow for CP-violation in the \textit{inert} sector, where the lightest \textit{inert} state is protected from decaying to SM particles through the conservation of a $Z_2$ symmetry, so that it is a Dark Matter (DM) candidate. For this scenario, we identify a smoking gun signature of dark CP-violation in the form of production thresholds of pairs of \textit{inert} neutral Higgs bosons at an $e^{+}{e}^{-}$ collider.

    hep-phEPJC(2020)·30 citations
29. 29*

    Revisiting constraints on 3+1 active-sterile neutrino mixing using IceCube data

    Luis Salvador Miranda🇿🇦 · Soebur Razzaque🇿🇦

    Recent IceCube search results for sterile neutrino increased tension between the combined appearance and disappearance experiments. On the other hand, MiniBooNE latest data confirms at $4.9\sigma$ CL the short-baseline oscillation anomaly. We analyze published IceCube data based on two different active-sterile mixing schemes using one additional sterile neutrino flavor. We present exclusion regions in the parameter ranges $0.01\le {\sin }^2{\theta }_{24}\le 0.1$ and $0.1{\mathrm{eV}}^2\le \Delta m_{42}^2\le 10{\mathrm{eV}}^2$ for the mass-mixing and flavor-mixing schemes. Under the more conservative mass-mixing scheme, $3\sigma$ CL allowed regions for the appearance experiment and MiniBooNE latest result are excluded at $\gtrsim 3\sigma$ CL. In case of less-restrictive flavor-mixing scheme, results from the appearance experiments are excluded at $\gtrsim 2\sigma$ CL. We also find that including prompt component of the atmospheric neutrino flux relaxes constraints on sterile mixing for $\Delta m_{42}^2\gtrsim 1{\mathrm{eV}}^2$.

    hep-phJHEP(2019)·15 citations
30. 30*

    Forward particle production in proton-nucleus collisions at NLO

    B. Ducloué🇫🇷

    Reaching next-to-leading order accuracy in perturbative calculations of particle production in QCD at high energy is essential for reliable phenomenological applications. In recent years, the Color Glass Condensate effective theory (the natural framework for such calculations) has indeed been promoted to NLO accuracy. However, the first NLO calculation of single-inclusive hadron production met with an unexpected difficulty: the cross-section suddenly turns negative at transverse momenta of the order of a few GeV, in a range where perturbation theory is expected to be reliable. We summarize recent efforts to understand and solve this issue, as well as to develop a running coupling scheme that can be used to consistently describe various processes in this formalism.

    hep-phPoS(2018)·0 citations
31. 31*

    Threshold Resummation at NNLL for Single-particle Production in Hadronic Collisions

    Patriz Hinderer🇩🇪 · Felix Ringer🇺🇸 · George Sterman🇺🇸 · Werner Vogelsang🇩🇪

    We develop threshold resummation for single-particle inclusive cross sections in hadron-hadron collisions to the level of next-to-next-to-leading logarithm, up to full matching with two-loop hard functions. We define and calculate all one-loop soft functions for all partonic channels. This enables us to separate the hard and soft functions at one loop. Along with these results, the one-loop finite parts of jet functions are used to check that the full soft, collinear and virtual corrections are reproduced to one loop for all partonic reactions. We exhibit these NLO results explicitly. NLO expansions of the resummed cross section match the exact NLO results extremely well numerically, and two loop expansions result in substantial corrections over many kinematic configurations. Explicit results are given in Mellin moment space, and a number of options for generating resummed cross sections are discussed.

    hep-phPRD(2019)·33 citations
32. 32*

    Leptoquark solution for both the flavor and ANITA anomalies

    Bhavesh Chauhan🇮🇳 · Subhendra Mohanty🇮🇳

    The ANITA experiment has seen anomalous Earth emergent showers of EeV energies which cannot be explained with Standard Model interactions. In addition, tests of lepton flavor universality in $R(D^{(\ast )})$ and $R(K^{(\ast )})$ have shown significant deviations from theoretical predictions. It is known that, among single leptoquark solutions, only the chiral vector leptoquark $U_1\sim (3,1,2/3)$ can simultaneously address the discrepancies. In this paper, we show that the leptoquark motivated by flavor anomalies coupled to a sterile neutrino can also explain the ANITA Anomalous Events. We consider two scenarios, (a) the sterile neutrino, produced via resonant leptoquark mediated neutrino-nucleon interactions, propagates through the Earth without significant attenuation and decays near the surface to a $\tau$ lepton; and (b) a cosmogenic sterile neutrino interacts with the matter near the surface of Earth and generates a $\tau$ lepton. These two scenarios give significantly large survival probabilities even when regeneration effects are not taken into account. In the second scenario, the distribution of emergent tau energy peaks in the same energy range as seen by ANITA.

    hep-phPRD(2019)·43 citations
33. 33*

    Neutral meson properties in hot and magnetized quark matter: a new magnetic field independent regularization scheme applied to NJL-type model

    Sidney S. Avancini🇧🇷 · Ricardo L. S. Farias🇧🇷 · William R. Tavares🇧🇷

    A magnetic field independent regularization scheme (zMFIR) based on the Hurwitz-Riemann zeta function is introduced. The new technique is applied to the regularization of the mean-field thermodynamic potential and mass gap equation within the SU(2) Nambu-Jona-Lasinio model in a hot and magnetized medium. The equivalence of the new and the standard MFIR scheme is demonstrated. The neutral meson pole mass is calculated in a hot and magnetized medium and the advantages of using the new regularization scheme are shown.

    hep-phhep-thnucl-thPRD(2019)·81 citations
34. 34*

    EFT determination of the heavy-hybrid spin potential

    Wai Kin Lai🇩🇪

    We study the spin splitting in the heavy quarkonium hybrid spectrum within the framework of an nonrelativistic effective field theory. We derive for the first time the spin-dependent part of the heavy-quark-antiquark potential for heavy quarkonium hybrids to order $1/m^2$ in the heavy-quark-mass expansion. We find that several operators that are not found in standard quarkonia appear, most remarkably an operator suppressed by only one power of the heavy-quark mass. By matching the weakly-coupled pNRQCD to the effective field theory in the regime of short heavy-quark-antiquark distances, we work out the matching coefficients of the spin-dependent operators, which are factorized into a perturbative and a nonperturbative part. The nonperturbative part can be expressed in terms of purely gluonic correlators. We fit the nonperturbative parts of the matching coefficients to lattice data of the charmonium hybrid spectrum and obtain results that respect the power counting. Using the obtained nonperturbative pieces, we compute the bottomonium hybrid spectrum with the spin-dependent potential, for which results from the lattice are still sparse.

    hep-phhep-exhep-latPoS(2019)·0 citations
35. 35*

    XYZ -- spectra from QCD Laplace Sum Rules at Higher Orders

    R. Albuquerque (FAT, UERJ, Rio de Janeiro-BR)🇧🇷 · S. Narison (LUPM, CNRS-IN2P3, Montpellier-FR)🇫🇷 · A. Rabemananjara🇲🇬 · D. Rabetiarivony🇲🇬 · G. Randriamanatrika (IHEPMAD, Antananarivo-MG)🇲🇬

    We review our results in Refs.[1,2] for the masses and couplings of heavy-light DD(BB)-like molecules and (Qq)(Qq)-like four-quark states from relativistic QCD Laplace sum rules (LSR) where next-to-next-to-leading order (N2LO) PT corrections in the chiral limit, next-to-leading order (NLO) SU3 PT corrections and non-perturbative contributions up to dimension d=6-8 are included. The factorization properties of molecule and four-quark currents have been used for the estimate of the higher order PT corrections. New integrated compact expressions of the spectral functions at leading order (LO) of perturbative QCD and up to dimensions d< (6 - 8) non-perturbative condensates are presented. The results are summarized in Tables 5 to 10, from which we conclude, within the errors, that the observed XZ states are good candidates for being 1^{++} and 0^{++} molecules or/and four-quark states, contrary to the observed Y states which are too light compared to the predicted 1^{-\pm} and 0^{-\pm} states. We find that the SU3 breakings are relatively small for the masses (< 10(resp. 3)%) for the charm (resp. bottom) channels while they are large (< 20%) for the couplings which decrease faster (1/m_{b}^{3/2}) than 1/m_{b}^{1/2} of HQET. QCD spectral sum rules (QSSR) approach cannot clearly separate (within the errors) molecules from four-quark states having the same quantum numbers. Results for the BK (DK)-like molecules and (Qq)(us)-like four-quark states from [3] are also reviewed which do not favour the molecule or/and four-quark interpretation of the X(5568). We suggest to scan the charm (2327 ~ 2444) MeV and bottom (5173 ~ 5226) MeV regions for detecting the (unmixed)(cu)ds and (bu)ds states. We expect that future experimental data and lattice results will check our predictions.

    hep-phhep-exhep-latNucl.Part.Phys.Proc.(2018)·1 citation
36. 36*

    Topological Susceptibility and QCD Axion Mass: QED and NNLO corrections

    Marco Gorghetto🇮🇹 · Giovanni Villadoro🇮🇹

    We improve the precision of the topological susceptibility of QCD, and therefore of the QCD axion mass, by including $O({\alpha }_{\mathrm{em}})$ and NNLO corrections in the chiral expansion, which amount to 0.65(21)% and -0.71(29)% respectively. Both corrections are one order of magnitude smaller than the known NLO ones, confirming the very good convergence of the chiral expansion and its reliability. Using the latest estimates for the light quark masses the current uncertainty is dominated by the one of the low-energy constant ${\ell }_7$. When combined with possible improvements on the light quark mass ratio and ${\ell }_7$ from lattice QCD, our computation could allow to determine the QCD axion mass with per-mille accuracy.

    hep-phhep-latJHEP(2019)·171 citations
37. 37*

    Electroweak Sector Under Scrutiny: A Combined Analysis of LHC and Electroweak Precision Data

    Eduardo da Silva Almeida🇧🇷 · Alexandre Alves🇧🇷 · N. Rosa Agostinho🇪🇸 · Oscar J. P. Éboli🇧🇷 · M.C.Gonzalez-Garcia🇪🇸

    We perform a comprehensive study of the Higgs couplings, gauge-boson couplings to fermions and triple gauge boson vertices. We work in the framework of effective theories including the effects of the dimension-six operators contributing to these observables. We determine the presently allowed range for the coefficients of these operators via a 20 parameter global fit to the electroweak precision data, as well as electroweak diboson and Higgs production data from LHC Run 1 and 2. We quantify the improvement on the determination of the 20 Wilson coefficients by the inclusion of the Run 2 results. In particular we present a novel analysis of the ATLAS Run 2 36.1 $\mathrm{f}{\mathrm{b}}^{-1}$ data on the transverse mass distribution of $W^{+}{W}^{-}$ and $W^{\pm }Z$ in the leptonic channel which allow for stronger tests of the triple gauge boson vertices. We discuss the discrete (quasi)-degeneracies existing in the parameter space of operator coefficients relevant for the Higgs couplings to fermions and gauge bosons. In particular we show how the inclusion of the incipient $tH$ data can break those degeneracies in the determination of the top-Higgs coupling. We also discuss and quantify the effect of keeping the terms quadratic in the Wilson coefficients in the analysis and we show the importance of the Higgs data to constrain some of the operators that modify the triple gauge boson couplings in the linear regime.

    hep-phPRD(2019)·113 citations
38. 38*

    A Basic Introduction to the Physics of Solar Neutrinos

    Mike Guidry🇺🇸 · Jay Billings🇺🇸

    A comprehensive introduction to the theory of the solar neutrino problem is given that is aimed at instructors who are not experts in quantum field theory but would like to incorporate these ideas into instruction of advanced undergraduate or beginning graduate students in courses like astrophysics or quantum mechanics, it is also aimed at the inquisitive student who would like to learn this topic on their own. The presentation assumes as theoretical preparation only that the reader is familiar with the basics of quantum mechanics in Dirac notation and elementary differential equations and matrices.

    ↳ astro-ph.SRhep-ph2 citations
39. 39*

    $\eta$ photoproduction off the deuteron and low-energy $\eta$-nucleon interaction

    S.X. Nakamura (Univ. Cruzeiro do Sul)🇧🇷 · H. Kamano (RCNP, Osaka Univ.)🇯🇵 · T. Ishikawa (ELPH, Tohoku Univ.)🇯🇵

    We study $\eta$ photoproduction off the deuteron ($\gamma d\to \eta pn$) at a special kinematics: $\sim 0.94$ GeV of the photon beam energy and $\sim 0^{\circ }$ of the scattering angle of the proton. This kinematics is ideal to extract the low-energy $\eta$-nucleon scattering parameters such as $a_{\eta N}$ (scattering length) and $r_{\eta N}$ (effective range) because the $\eta$-nucleon elastic scattering is significantly enhanced. We show that if a ratio $R$, the $\gamma d\to \eta pn$ cross section divided by the $\gamma p\to \eta p$ cross section convoluted with the proton momentum distribution in the deuteron, is measured with 5% error, $\mathrm{Re}[a_{\eta N}]$ ($\mathrm{Re}[r_{\eta N}]$) can be determined at the precision of $\sim \pm$0.1 fm ($\sim \pm$0.5 fm), significantly narrowing down the currently estimated range of the parameters. The measurement is ongoing at the Research Center for Electron Photon Science (ELPH), Tohoku University.

    ↳ nucl-thhep-phnucl-exJPS Conf.Proc.(2019)·0 citations
40. 40*

    Wigner function approach to polarization-vorticity coupling and hydrodynamics with spin

    Avdhesh Kumar🇵🇱

    Newly introduced equilibrium Wigner functions for particles with spin one-half are used in the semi-classical kinetic equations to study a possible relation between thermal vorticity and spin polarization. It is shown that in global equilibrium both the thermal-vorticity and spin polarization tensors are constant but not necessarily equal. In the case of local equilibrium, we define a procedure leading to hydrodynamic equations with spin. We introduce such equations for the de~Groot, van~Leeuwen, and van~Weert (GLW) formalism as well as for the canonical scheme (these two frameworks differ by the definitions of the energy-momentum and spin tensors). It is found that the GLW and canonical versions are connected by a pseudo-gauge transformation.

    ↳ nucl-thhep-phPoS(2018)·6 citations
41. 41*

    Models of vacuum energy interacting with cold dark matter: Constraints and comparison

    Hai-Li Li🇨🇳 · Lu Feng🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    In this paper, we investigate the observational constraints on the scenario of vacuum energy interacting with cold dark matter. We consider eight typical interaction forms in such an interacting vacuum energy scenario. The observational data used in this work to constrain these models include the JLA sample of type Ia supernovae observation, the Planck 2015 distance priors data of cosmic microwave background anisotropies observation, the baryon acoustic oscillations data, and the Hubble constant direct measurement. We find that the current observational data almost equally favor these interacting vacuum energy models. We also find that for all these models of vacuum energy interacting with cold dark matter the case of no interaction is actually well consistent with the current observational data within 1$\sigma$ range.

    ↳ astro-ph.COgr-qchep-phSCPMA(2019)·34 citations
42. 42*

    (Semi-)leptonic decays of D Mesons at BESIII

    Youhua Yang🇨🇳

    Leptonic and semi-leptonic $D$ decays at BESIII contribute the most precise experimental measurement of $|V_{cs(d)}|$ and form factor $f_{D_{(s)}}$ in the world based on 2.93 fb${}^{-1}$ and 3.19 fb${}^{-1}$ data taken at center-of-mass energies $\sqrt{s}=3.773$ and 4.180~GeV, respectively. The largest samples at the mass threshold of the charmed hardons $D_{(s)}$ also provide chances to extract form factors of some semi-electronic decays for the first time and together with the semi-muonic decays we could understand lepton flavour universality better.

    ↳ hep-exhep-ph9 citations
43. 43*

    The production of $b\bar{b}$ dijet in heavy-ion collisions at the LHC

    Sa Wang🇨🇳 · Wei Dai🇨🇳 · Shan-Liang Zhang🇨🇳 · Ben-Wei Zhang🇨🇳 · Enke Wang🇨🇳

    We report our recent theoretical calculations for $b\bar{b}$ dijet production in high-energy nuclear collisions. The NLO+parton shower (PS) event generator SHERPA has been employed to provide the pp baseline of $b\bar{b}$ dijet production. A framework which combines Langevin transport equation to describe the evolution of heavy quarks and the higher-twist scheme to consider the inelastic energy loss of both light and heavy partons has been implemented. Within this framework, we present the theoretical result of transverse momentum imbalance $x_J=p_{T1}/p_{T2}$ both for inclusive dijet and $b\bar{b}$ dijet in Pb+Pb collision at 5.02 TeV. The energy loss of b jet would shift $x_J$ to smaller value relative to p+p reference which is consistent with the CMS data. In addition, we show the medium modification for angular correlation of $b\bar{b}$ dijet in A+A collision at $\sqrt{s_{NN}}=5.02$~TeV. We observe a stronger suppression in small $\Delta \varphi =|{\varphi }_{b1}-{\varphi }_{b2}|$ region where the gluon splitting processes dominate relative to large $\Delta \varphi$ region. The difference leads to a modest suppression on near side ($\Delta \varphi \sim 0$) and enhancement on away side ($\Delta \varphi \sim \pi$).

    ↳ nucl-thhep-phPoS(2018)·3 citations
44. 44*

    Firewalls in General Relativity

    David E. Kaplan🇺🇸 · Surjeet Rajendran🇺🇸

    We present spherically symmetric solutions to Einstein's equations which are equivalent to canonical Schwarzschild and Reissner-Nordstrom black holes on the exterior, but with singular (Planck-density) shells at their respective event and inner horizons. The locally measured mass of the shell and the singularity are much larger than the asymptotic ADM mass. The area of the shell is equal to that of the corresponding canonical black hole, but the physical distance from the shell to the singularity is a Planck length, suggesting a natural explanation for the scaling of the black hole entropy with area. The existence of such singular shells enables solutions to the black hole information problem of Schwarzschild black holes and the Cauchy horizon problem of Reissner-Nordstrom black holes. While we cannot rigorously address the formation of these solutions, we suggest plausibility arguments for how normal black hole solutions may evolve into such states. We also comment on the possibility of negative mass Schwarzschild solutions that could be constructed using our methods. Requirements for the non-existence of negative-mass solutions may put restrictions on the types of singularities allowed in an ultraviolet theory of gravity.

    ↳ hep-thgr-qchep-phPRD(2019)·35 citations
45. 45*

    On the possibility to study antiproton production at the SPD detector at NICA collider for dark matter search in astrophysical experiments

    A. Guskov🇷🇺 · R. El-Kholy🇪🇬

    Dark matter is an important component of the Standard model of cosmology but its nature is still unknown. One of the most common explanations is that dark matter consists of Weakly Interacting Massive Particles (WIMPs), supposed to be cold thermal relics of the Big Bang and to build up the galactic dark halos. Indirect search of dark matter could be performed via the study of an anomalous antiproton component in cosmic rays originating from possible annihilation of dark matter pairs in the galactic halo, on top of the standard astrophysical production. The measurements performed by the AMS-02 and PAMELA spectrometers have shown that limited knowledge of antiproton-production cross sections in $pp$, $pD$, $pHe$ and $HeHe$ collisions is one of the main uncertainties of background subtraction. The planned SPD experiment at the NICA collider could provide a precision measurement of antiproton yield in wide kinematic range in $pp$ and $pD$ collisions at the energy scale from the threshold to $\sqrt{s}=26$ GeV/$c$.

    ↳ hep-exhep-phPhys.Part.Nucl.Lett.(2019)·4 citations
46. 46*

    Neutrino Properties and the Cosmological Tensions in the $\Lambda$CDM Model

    Stefano Gariazzo🇪🇸

    In this talk I will review the current status of the constraints on the neutrino properties from cosmological measurements, with a particular focus on their mass and effective number. I will also discuss the existing tensions within the context of the \lcdm\ model, including the discrepancies on the Hubble parameter and on the matter fluctuations at small scales, and how neutrinos could help to alleviate the aforementioned problems.

    ↳ astro-ph.COhep-ph2 citations
47. 47*

    $F(R)$ gravity in the early Universe: Electroweak phase transition and chameleon mechanism

    Taishi Katsuragawa🇨🇳 · Shinya Matsuzaki🇨🇳 · Eibun Senaha🇰🇷

    It is widely believed that the screening mechanism is an essential feature for the modified gravity theory. Although this mechanism has been examined thoroughly in the past decade, their analyses are based on the classical configuration of the matter fields. In this paper, we demonstrate a new formulation of the chameleon mechanism in $F(R)$ gravity theory, to shed light on quantum-field theoretical effects on the chameleon mechanism as well as the related scalaron physics, induced by the matter sector. We show a potential absence of the chameleon mechanism in the cosmic history based on a scale-invariant-extended scenario beyond the standard model of particle physics, in which a realistic electroweak phase transition, possibly yielding the right amount of baryon asymmetry of Universe today, simultaneously breaks the scale invariance in the early Universe. Remarkably enough, the matter sector contribution to the trace of energy-momentum tensor turns out to be on the same order of magnitude as that computed in the classical perfect-fluid approximation, even though the theory involves the nontrivial electroweak-phase transition environment. We also briefly discuss the oscillation of the scalaron field and indirect generation of non-tensorial gravitational waves induced by the electroweak phase transition.

    ↳ gr-qchep-phhep-thCPC(2019)·16 citations
48. 48*

    Gravitational waves induced by scalar perturbations as probes of the small-scale primordial spectrum

    Keisuke Inomata🇯🇵 · Tomohiro Nakama🇨🇳

    Compared to primordial perturbations on large scales, roughly larger than $1$ megaparsec, those on smaller scales are not severely constrained. We revisit the issue of probing small-scale primordial perturbations using gravitational waves (GWs), based on the fact that, when large-amplitude primordial perturbations on small scales exist, GWs with relatively large amplitudes are induced at second order in scalar perturbations, and these induced GWs can be probed by both existing and planned gravitational-wave projects. We use accurate methods to calculate these induced GWs and take into account sensitivities of different experiments to induced GWs carefully, to report existing and expected limits on the small-scale primordial spectrum.

    ↳ astro-ph.COgr-qchep-phPRD(2019)·263 citations
49. 49*

    Insight into primordial magnetic fields from 21-cm line observation with EDGES experiment

    Teppei Minoda🇯🇵 · Hiroyuki Tashiro🇯🇵 · Tomo Takahashi🇯🇵

    The recent observation of the 21-cm global absorption signal by EDGES suggests that the intergalactic medium (IGM) gas has been cooler than the cosmic microwave background during $15\lesssim z\lesssim 20$. This result can provide a strong constraint on heating sources for the IGM gas at these redshifts. In this paper we study the constraint on the primordial magnetic fields (PMFs) by the EDGES result. The PMFs can heat the IGM gas through their energy dissipation due to the magnetohydrodynamic effects. By numerically solving the thermal evolution of the IGM gas with the PMFs, we find that the EDGES result gives a stringent limit on the PMFs as $B_{1\mathrm{Mpc}}\lesssim 10^{-10}$ G.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2019)·43 citations
50. 50*

    Prospect for top quark FCNC searches at the FCC-hh

    Petr Mandrik (for the FCC study group)🇷🇺

    FCC-hh is a proposed future energy-frontier hadron collider, which goal is to provide high luminosity proton collisions at a centre-of-mass energy of 100 TeV. The FCC-hh has an extremely rich physics program ranging from standard model (SM) measurements to direct searches for physics beyond the standard model (BSM). One of the processes sensitive to new physics is flavour-changing neutral currents (FCNC) that extremely rare in the SM but have enhanced behavior in several BSM scenarios. In this report we present results of projections of FCNC searches in top quark interactions to the FCC-hh conditions based on Monte-Carlo simulation of FCC-hh detector.

    ↳ hep-exhep-phJ.Phys.Conf.Ser.(2019)·16 citations
51. 51*

    Chiral torsional effect

    Z.V.Khaidukov🇷🇺 · M.A.Zubkov🇮🇱

    We propose the new nondissipative transport effect - the appearance of axial current of thermal quasiparticles in the presence of background gravity with torsion. For the non-interacting model of massless Dirac fermions the response of the axial current to torsion is derived. The chiral vortical effect appears to be the particular case of the chiral torsional effect. The proposed effect may be observed in the condensed matter systems with emergent relativistic invariance (Weyl/Dirac semimetals and the ${}^3$He-A superfluid).

    ↳ cond-mat.mes-hallhep-phJETP Lett.(2018)·43 citations
52. 52*

    Nonlinear Dynamics of Tensor Modes in Conformal Real Relativistic Fluids

    Nahuel Mirón-Granese🇦🇷 · Esteban Calzetta🇦🇷 · Alejandra Kandus🇧🇷

    In the Second Order Theories (SOT) of real relativistic fluids, the non-ideal properties are described by a new set of dynamical tensor variables. In this work we explore the non-linear dynamics of those modes in a conformal fluid. Among all possible SOTs, we choose to work with the Divergence Type Theories (DTT) formalism, which ensures that the second law of thermodynamics is satisfied non-perturbatively. In considering a perturbative scheme within this formalism, at next to leading order a set of Maxwell-Cattaneo equations is obtained, as in e.g. Israel-Stewart theories. The tensor modes include two divergence-free modes which have no analog in theories based on covariant Navier-Stokes equations, and that are particularly relevant because they may couple linearly to a gravitational field. To study the dynamics of this irreducible tensor sector, we observe that in causal theories such as DTTs, thermal fluctuations induce a stochastic stirring force in the equations of motion, which excites the tensor modes while preserving energy momentum conservation. From fluctuation-dissipation considerations, it follows that the random force is Gaussian with a white spectrum. The irreducible tensor modes in turn excite vector modes, which back-react on the tensor sector, thus producing a consistent non-linear, second order description of the divergence-free tensor dynamics. Using the Martin-Siggia-Rose (MSR) formalism we obtain the two-point correlation function for these tensor modes at next to leading order, and the induced stochastic component of the energy-momentum tensor. We find that the thermal fluctuations induce a scale invariant spectrum at short scales, while preserving a white spectrum at large scales. This result suggests that tensor modes could sustain an entropy cascade.

    ↳ hep-thgr-qchep-ph0 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.