Fri·Aug 3, 2018Friday·August 3, 2018

1. 01*

   Minimally Extended Left-Right Symmetric Model for Dark Matter with U(1) Portal

   M. J. Neves🇧🇷 · J. A. Helaÿel-Neto🇧🇷 · Rabindra N. Mohapatra🇺🇸 · Nobuchika Okada🇺🇸

   A minimal extension of the left-right symmetric model for neutrino masses that includes a vector-like singlet fermion dark matter (DM) is presented with the DM connected to the visible sector via a gauged U(1) portal. We discuss the symmetry breaking in this model and calculate the mass and mixings of the extra heavy neutral gauge boson at the TeV scale. The extra gauge boson can decay to both standard model particles as well to dark matter. We calculate the relic density of the singlet fermion dark matter and its direct detection cross section and use these constraints to obtain the allowed parameter range for the new gauge coupling and the dark matter mass.

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

   Vacuum Induced CP Violation Generating a Complex CKM Matrix with Controlled Scalar FCNC

   Miguel Nebot (Lisbon IST and CFTP)🇵🇹 · Francisco J. Botella (Valencia U. and IFIC)🇪🇸 · Gustavo C. Branco (Lisbon IST and CFTP)🇵🇹

   We propose a viable minimal model with spontaneous CP violation in the framework of a Two Higgs Doublet Model. The model is based on a generalised Branco-Grimus-Lavoura model with a flavoured ${\mathbb{Z}}_2$ symmetry, under which two of the quark families are even and the third one is odd. The lagrangian respects CP invariance, but the vacuum has a CP violating phase, which is able to generate a complex CKM matrix, with the rephasing invariant strength of CP violation compatible with experiment. The question of scalar mediated flavour changing neutral couplings is carefully studied. In particular we point out a deep connection between the generation of a complex CKM matrix from a vacuum phase and the appearance of scalar FCNC. The scalar sector is presented in detail, showing that the new scalars are necessarily lighter than 1 TeV. A complete analysis of the model including the most relevant constraints is performed, showing that it is viable and that it has definite implications for the observation of New Physics signals in, for example, flavour changing Higgs decays or the discovery of the new scalars at the LHC. We give special emphasis to processes like $t\to \mathrm{h}c,\mathrm{h}u$, as well as $\mathrm{h}\to bs,bd$, which are relevant for the LHC and the ILC.

   hep-phhep-exEPJC(2019)·26 citations
3. 03*

   Transversity in inclusive DIS and novel TMD sum rules

   Alberto Accardi (Hampton U. and Jefferson Lab)🇺🇸 · Andrea Signori (Jefferson Lab)🇺🇸

   A reanalysis of collinear factorization for inclusive Deep Inelastic Scattering shows that a novel, non perturbative spin-flip term associated with the invariant mass of the produced hadrons couples, at large enough Bjorken $x_B$, to the target's transversity distribution function. The resulting new contribution to the $g_2$ structure function can potentially explain the discrepancy between recent calculations and fits of this quantity. The new term also breaks the Burkhardt-Cottingham sum rule, now featuring an interplay between the $g_2$ and $h_1$ functions that calls for a re-examination of their small-$x$ behavior. As part of the calculation leading to these results, a new set of TMD sum rules is derived by relating the single-hadron quark fragmentation correlator to the fully dressed quark propagator by means of integration over the hadronic momenta and spins. A complete set of momentum sum rules is obtained for transverse-momentum-dependent quark fragmentation functions up to next-to-leading twist.

   hep-phPoS(2018)·7 citations
4. 04*

   Transition radiation as a probe of chiral anomaly

   Xu-Guang Huang🇨🇳 · Kirill Tuchin🇺🇸

   A fast charged particle crossing the boundary between the chiral matter and vacuum radiates the transition radiation. Its most remarkable features --- the resonant behavior at a certain emission angle and the circular polarization of the spectrum --- depend on the parameters of the chiral anomaly in a particular material/matter. The chiral transition radiation can be used to investigate the chiral anomaly in such diverse media as the quark-gluon plasma, the Weyl semimetals, and the axionic dark matter.

   hep-phcond-mat.mes-hallnucl-thPRL(2018)·20 citations
5. 05*

   Prospects of Neutral Higgs boson decays in the NMSSM

   M. M. Almarashi🇸🇦

   In this paper, we present the branching ratios of the two lightest CP-even Higgses, $h_1$ and $h_2$, and of the lightest CP-odd Higgs, $a_1$, in the context of the Non-Minimal Supersymmetric Standard Model (NMSSM). We find that for some regions of the parameter space, the branching fractions of $a_1$ into the lightest charginos ($a_1\to {\chi }_1^{+}{\chi }_1^{-})$ and neutralinos ($a_1\to {\chi }_1^0{\chi }_1^0)$ are larger than $50\%$, and can reach a $100\%$ level in the latter case. Furthermore, the branching ratio of the $h_2\to a_1{a}_1$ can be equal to unity for all masses of $h_2$ when it is a pure singlet. The above unusual channels are hallmarks of the existence of the NMSSM.

   hep-phResults Phys.(2018)·4 citations
6. 06*

   Nucleon dissociation and incoherent $J/\psi$ photoproduction on nuclei in ion ultraperipheral collisions at the CERN Large Hadron Collider

   V. Guzey (Jyvaskyla U., Helsinki Inst. of Phys, St. Petersburg, INP)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (St. Petersburg, INP)🇷🇺

   Using the general notion of cross section fluctuations in hadron--nucleus scattering at high energies, we derive an expression for the cross section of incoherent $J/\psi$ photoproduction on heavy nuclei $d{\sigma }_{\gamma A\to J/\psi Y}/dt$, which includes both elastic $d{\sigma }_{\gamma p\to J/\psi p}/dt$ and proton-dissociation $d{\sigma }_{\gamma p\to J/\psi Y}/dt$ photoproduction on target nucleons. We find that with good accuracy, $d{\sigma }_{\gamma A\to J/\psi Y}/dt$ can be expressed as a product of the sum of the $d{\sigma }_{\gamma p\to J/\psi p}/dt$ and $d{\sigma }_{\gamma p\to J/\psi Y}/dt$ cross sections, which have been measured at HERA, and the common nuclear shadowing factor, which is calculated using the leading twist nuclear shadowing model. Our prediction for the cross section of incoherent $J/\psi$ photoproduction in Pb-Pb UPCs at $\sqrt{s_{NN}}=2.76$ TeV and $y=0$, $d{\sigma }_{AA\to J/\psi AY}(y=0)/dy=0.59-1.24$ mb, agrees within significant theoretical uncertainties with the data of the ALICE collaboration.

   hep-phnucl-exPRC(2019)·32 citations
7. 07*

   Models with Extended Higgs Sectors at Future $e^{+}{e}^{-}$ Colliders

   Duarte Azevedo🇵🇹 · Pedro Ferreira🇵🇹 · M. Margarete Mühlleitner🇩🇪 · Rui Santos🇵🇹 · Jonas Wittbrodt🇩🇪

   We discuss the phenomenology of several Beyond the Standard Model (SM) extensions that include extended Higgs sectors. The models discussed are: the SM extended by a complex singlet field (CxSM), the 2-Higgs-Doublet Model with a CP-conserving (2HDM) and a CP-violating (C2HDM) scalar sector, the singlet extension of the 2-Higgs-Doublet Model (N2HDM), and the Next-to-Minimal Supersymmetric SM extension (NMSSM). All the above models have at least three neutral scalars, with one being the 125 GeV Higgs boson. This common feature allows us to compare the production and decay rates of the other two scalars and therefore to compare their behaviour at future electron-positron colliders. Using predictions on the expected precision of the 125 GeV Higgs boson couplings at these colliders we are able to obtain the allowed admixtures of either a singlet or a pseudoscalar to the observed 125 GeV scalar. Therefore, even if no new scalar is found, the expected precision at future electron-positron colliders, such as CLIC, will certainly contribute to a clearer picture of the nature of the discovered Higgs boson.

   hep-phPRD(2019)·30 citations
8. 08*

   Thermal production of light Dirac right-handed sneutrino dark matter

   Ki-Young Choi🇰🇷 · Jongkuk Kim🇰🇷 · Osamu Seto🇯🇵

   We consider the production of right-handed (RH) sneutrino dark matter in a model of Dirac neutrino where neutrino Yukawa coupling constants are very small. Dark matter RH sneutrinos are produced by scatterings and decays of thermal particles in the early Universe without reaching thermal equilibrium due to the small Yukawa couplings. We show that not only decays of thermal particles but also the thermal scatterings can be a dominant source as well as non-thermal production in a scenario with light sneutrinos and charged sleptons while other supersymmetric particles are heavy. We also discuss the cosmological implications of this scenario.

   hep-phPhys.Dark Univ.(2018)·9 citations
9. 09*

   Initial correlations of the Glasma energy-momentum tensor

   Javier L. Albacete🇪🇸 · Pablo Guerrero-Rodríguez🇪🇸 · Cyrille Marquet🇫🇷

   We present an analytical calculation of the covariance of the energy-momentum tensor associated to the gluon field produced in ultra-relativistic heavy ion collisions at early times, the Glasma. This object involves the two-point and single-point correlators of the energy-momentum tensor ($⟨T^{\mu \nu }(x_{\perp })T^{\sigma \rho }(y_{\perp })⟩$ and $⟨T^{\mu \nu }(x_{\perp })⟩$, respectively) at proper time $\tau =0^{+}$. Our approach is based on the Color Glass Condensate effective theory, which allows us to map the fluctuations of the valence color sources in the colliding nuclei to those of the energy-momentum tensor of the produced gluon fields via the solution of the classical equations of motion in the presence of external currents. The color sources in the two colliding nuclei are characterized by Gaussian correlations, albeit in more generality than in the McLerran-Venugopalan model, allowing for non-trivial impact parameter and transverse dependence of the two-point correlator. We compare our results to those obtained under the Glasma Graph approximation, finding agreement in the limit of short transverse separations. However, important differences arise at larger transverse separations, where our result displays a slower fall-off than the Glasma Graph result ($r^{-2}$ vs $r^{-4}$ power-law decay), indicating that the color screening of the correlations in the transverse plane occurs at distances larger than $1/Q_s$ by a logarithmic factor sensitive to the infrared. In the Glasma flux tube picture, this implies that the color domains are larger than originally estimated.

   hep-phnucl-thJHEP(2019)·34 citations
10. 10*

    Double charmonium productions in electron-positron annihilation using Bethe-Salpeter approach

    Hluf Negash🇷🇺 · Shashank Bhatnagar🇮🇳

    We calculate the double charmonium production cross section within the framework of $4\times 4$ Bethe-Salpeter Equation in the electron-positron annihilation, at center of mass energy $\sqrt{s}=10.6$GeV, that proceeds through the exchange of a single virtual photon. In this calculation, we make use of the full Dirac structure of 4D BS wave functions of these charmonia, with the incorporation of all the Dirac covariants (both leading and sub-leading). The calculated cross-sections for the double charmonium productions for final states, ($J/\Psi ,{\eta }_c$); (${\Psi }^{\prime },{\eta }_c$) ; ($J/\Psi ,{\eta }_c^{\prime }$); and (${\Psi }^{\prime },{\eta }_c^{\prime }$) are close to experimental data, and in broad agreement with results of other theoretical models.

    hep-phAdv.High Energy Phys.(2019)·5 citations
11. 11*

    Shadowing corrections to the evolution of singlet structure function

    Mayuri Devee🇮🇳

    We report a semi-analytical approach for the solution of the nonlinear Gribov-Levin-Ryskin-Mueller-Qiu (GLR-MQ) evolution equation for sea quark distribution and investigate the effect of gluon shadowing on the small-x and moderate-Q^2 behaviour of singlet structure function, F_2^S(x,Q^2). The predicted values of singlet structure functions with shadowing corrections are comparable with different experimental data as well as parametrizations. It is very fascinating to observe signatures of gluon recombination in our predictions. We note that, with decreasing x the the rapid growth of singlet structure function is eventually tamed by the shadowing or nonlinear term appeared in the QCD evolution due to gluon recombination. This taming behaviour of shadowing singlet structure function towards small-x become significant at the hot spots, at R=2 GeV^{-1}. Further the computed values of the ratio of {F_2^S(x,Q^2)} with shadowing to that without shadowing clearly indicate that towards smaller values of x and Q^2 the nonlinear effects play an increasingly important role.

    hep-phPhys.Scripta(2023)·5 citations
12. 12*

    The $Z_c$ structures in a coupled-channels model

    Pablo G. Ortega🇪🇸 · Jorge Segovia🇪🇸 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸

    The $Z_c(3900{)}^{\pm }/Z_c(3885{)}^{\pm }$ and $Z_c(4020{)}^{\pm }$ are two charmonium-like structures discovered in the $\pi J/\psi$ and $D^{\ast }{\bar{D}}^{(\ast )}+h.c.$ invariant mass spectra. Their nature is puzzling due to their charge, which forces its minimal quark content to be $c\bar{c}u\bar{d}$ ($c\bar{c}d\bar{u}$). Thus, it is necessary to explore four-quark systems in order to understand their inner structure. Additionally, their strong coupling to channels such as $\pi J/\psi$ and the closeness of their mass to $D^{\ast }{\bar{D}}^{(\ast )}$-thresholds stimulates both a molecular interpretation or a coupled-channels threshold effect. In this work we perform a coupled-channels calculation of the $I^G(J^{PC})=1^{+}(1^{+-})$ sector including $D^{(\ast )}{\bar{D}}^{\ast }+h.c.$, $\pi J/\psi$ and $\rho {\eta }_c$ channels in the framework of a constituent quark model which satisfactorily describes a wide range of properties of (non-)conventional hadrons containing heavy quarks. The meson-meson interactions are dominated by the non-diagonal $\pi J/\psi -D^{\ast }{\bar{D}}^{(\ast )}$ and $\rho {\eta }_c-D^{\ast }{\bar{D}}^{(\ast )}$ couplings which indicates that the $Z_c(3900{)}^{\pm }/Z_c(3885{)}^{\pm }$ and $Z_c(4020{)}^{\pm }$ are unusual structures. The study of the analytic structure of the $S$-matrix allows us to conclude that the point-wise behavior of the line shapes in the $\pi J/\psi$ and $D{\bar{D}}^{\ast }$ invariant mass distributions is due to the presence of two virtual states that produce the $Z_c$ peaks.

    hep-phEPJC(2019)·54 citations
13. 13*

    Electron-photon deep inelastic scattering at small x in holographic QCD

    Akira Watanabe🇨🇳 · Hsiang-nan Li🇹🇼

    We study the electron-photon deep inelastic scattering at small Bjorken variable x in the framework of holographic QCD, employing the Pomeron exchange to describe the involved strong interaction. With the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel and appropriate wave functions for the incident and target particles, which are defined in the five-dimensional AdS space, we obtain the photon structure functions. It is shown that our predictions agree with the experimental data measured at LEP and with those derived from a known parameterization of the photon parton distribution functions.

    hep-phnucl-thPoS(2018)·0 citations
14. 14*

    Gauge-invariant decomposition of meson energy in two-dimensional QCD

    Yu Jia🇨🇳 · Rui Yu🇨🇳 · Xiaonu Xiong🇩🇪

    This work is driven by our curiosity towards some basic questions in QCD: how is the energy of a moving hadron partitioned among different gauge-invariant sectors in QCD Hamiltonian? How is the energy of an massless pion separated between quark and gluon sectors, particularly in the soft pion limit? Is it possible to decompose the celebrated Gell-Mann-Oakes-Renner (GOR) relation? To what extent can we justify the quark potential model from the field-theoretical mass decomposition for heavy quarkonium? Due to limitation of contemporary nonperturbative tools, we do not yet know answers to these questions in realistic QCD. In this work, we take the 't Hooft model (two-dimensional QCD in large-$N$ limit) as a prototype model that mimics some essential aspects of the true QCD. We investigate the gauge-invariant energy decomposition of a flavor-neutral meson that can carry an arbitrary momentum (including stationary case), with meson species ranging from massless pion to bottomonium. All the aforementioned questions can be addressed satisfactorily within this model, in particular some unexpected patterns related to pion are discovered for the first time in two-dimensional QCD. We hope that our study can offer some useful clues and stimulation for future investigations on hadron energy decomposition in realistic QCD.

    hep-phhep-lathep-thPRD(2018)·4 citations
15. 15*

    Group Theoretic Approach to Fermion Production

    Ui Min🇰🇷 · Minho Son🇰🇷 · Han Gyeol Suh🇰🇷

    We propose a universal group theoretic description of the fermion production through any type of interaction to scalar or pseudo-scalar. Our group theoretic approach relies on the group $SU(2)\times U(1)$, corresponding to the freedom in choosing representations of the gamma matrices in Clifford algebra, under which a part of the Dirac spinor function transforms like a fundamental representation. In terms of a new $SO(3)$ ($\sim SU(2)$) vector constructed out of spinor functions, we show that fermion production mechanism can be analogous to the classical dynamics of a vector precessing with the angular velocity. In our group theoretic approach, the equation of motion takes a universal form for any system, and choosing a different type of interaction or a different basis amounts to selecting the corresponding angular velocity. The expression of the particle number density is greatly simplified, compared to the traditional approach, and it provides us with a simple geometric interpretation of the fermion production dynamics. For the purpose of the demonstration, we focus on the fermion production through the derivative coupling to the pseudo-scalar.

    hep-phhep-thJHEP(2019)·5 citations
16. 16*

    Maximal Flavour Violation: a Cabibbo mechanism for leptoquarks

    Luca Di Luzio🇬🇧 · Javier Fuentes-Martin🇨🇭 · Admir Greljo🇩🇪 · Marco Nardecchia🇨🇭 · Sophie Renner🇩🇪

    We propose a mechanism that allows for sizeable flavour violation in quark-lepton currents, while suppressing flavour changing neutral currents in quark-quark and lepton-lepton sectors. The mechanism is applied to the recently proposed 4321 renormalizable model, which can accommodate the current experimental anomalies in $B$-meson decays, both in charged and neutral currents, while remaining consistent with all other indirect flavour and electroweak precision measurements and direct searches at high-$p_T$. To support this claim, we present an exhaustive phenomenological survey of this fully calculable UV complete model and highlight the rich complementarity between indirect and direct searches.

    hep-phhep-exJHEP(2018)·159 citations
17. 17*

    Displaced vertex signatures of doubly charged scalars in the type-II seesaw and its left-right extensions

    P. S. Bhupal Dev🇺🇸 · Yongchao Zhang🇺🇸

    The type-II seesaw mechanism with an isospin-triplet scalar ${\Delta }_L$ provides one of the most compelling explanations for the observed smallness of neutrino masses. The triplet contains a doubly-charged component $H_L^{\pm \pm }$, which dominantly decays to either same-sign dileptons or to a pair of $W$ bosons, depending on the size of the triplet vacuum expectation value. However, there exists a range of Yukawa couplings $f_L$ of the triplet to the charged leptons, wherein a relatively light $H_L^{\pm \pm }$ tends to be long-lived, giving rise to distinct displaced-vertex signatures at the high-energy colliders. We find that the displaced vertex signals from the leptonic decays $H_L^{\pm \pm }\to {\ell }_{\alpha }^{\pm }{\ell }_{\beta }^{\pm }$ could probe a broad parameter space with $10^{-10}\lesssim |f_L|\lesssim 10^{-6}$ and 45.6 GeV $<M_{H_L^{\pm \pm }}\lesssim 200$ GeV at the high-luminosity LHC. Similar sensitivity can also be achieved at a future 1 TeV $e^{+}{e}^{-}$ collider. The mass reach can be extended to about 500 GeV at a future 100 TeV proton-proton collider. Similar conclusions apply for the right-handed triplet $H_R^{\pm \pm }$ in the TeV-scale left-right symmetric models, which provide a natural embedding of the type-II seesaw. We show that the displaced vertex signals are largely complementary to the prompt same-sign dilepton pair searches at the LHC and the low-energy, high-intensity/precision measurements, such as neutrinoless double beta decay, charged lepton flavor violation, electron and muon anomalous magnetic moments, muonium oscillation and Møller scattering.

    hep-phhep-exJHEP(2018)·103 citations
18. 18*

    Grand Unified Theory with a Stable Proton

    Bartosz Fornal🇺🇸 · Benjamin Grinstein🇺🇸

    We demonstrate that a phenomenologically viable four-dimensional grand unified theory with no proton decay can be constructed. This is done in the framework of the minimal non-supersymmetric SU(5) GUT by introducing new representations and separating the physical quark and lepton fields into different multiplets. In such a theory all beyond Standard Model particles are naturally heavy, but one can tune the parameters of the model such that gauge coupling unification is achieved and some of the new particles are at the TeV scale and accessible at the LHC.

    hep-phInt.J.Mod.Phys.A(2018)·6 citations
19. 19*

    Semi-inclusive back-to-back production of a hadron pair and a single hadron in $e^{+}{e}^{-}$ annihilation

    Hrayr H. Matevosyan🇦🇺 · Aram Kotzinian🇦🇲 · Anthony W. Thomas🇦🇺

    Inclusive hadron production in $e^{+}{e}^{-}$ annihilation has long been used to study both single hadron fragmentation functions (FF) and dihadron fragmentation functions (DiFF). In particular, the polarized DiFFs can be accessed in electron-positron annihilation by measuring azimuthal correlations between two back-to-back pairs of hadrons in the center of mass system, where the relevant structure functions can be expressed as convolutions of two (polarized) DiFFs. Here we explore the advantages of measuring the inclusive back-to-back production of a single hadron on one side against a hadron pair on the opposite side of the detector in two jet events. The leading twist cross section for this process contains convolutions of the corresponding single hadron FFs on one side and the DiFFs for the hadron pair on the other side, which furnishes several interesting new opportunities. A measurement of the unpolarized cross section with a number of different types of observed hadrons will help in untangling the quark flavor dependence of the unpolarized DiFFs, when the results are analyzed together with the inclusive measurements of dihadron pairs, such as those recently performed by the $\text{BELLE}$ collaboration. Even more interesting, with a polarized hyperon on one side we can study the quark spin-dependent DiFFs of an unpolarized hadron pair on the other side. This, in turn, will allow us to test the universality of the spin-dependent DiFFs entering the cross sections of electron-positron annihilation and semi-inclusive deep inelastic scattering processes.

    hep-phhep-exnucl-thJHEP(2018)·10 citations
20. 20*

    On Lepton Flavor Universality in Top Quark Decays

    Jernej F. Kamenik🇸🇮 · Andrey Katz🇨🇭 · Daniel Stolarski🇨🇦

    We propose a novel strategy to test lepton flavor universality (LFU) in top decays, applicable to top pair production at colliders. Our proposal exploits information in kinematic distributions and mostly hinges on data-driven techniques, thus having very little dependence on our theoretical understanding of top pair production. Based on simplified models accommodating recent hints of LFU violation in charged current B meson decays, we show that existing LHC measurements already provide non-trivial information on the flavor structure and the mass scale of such new physics (NP). We also project that the measurements of LFU in top decays at the high-luminosity LHC could reach a precision at the percent level or below, improving the sensitivity to LFU violating NP in the top sector by more than an order of magnitude compared to existing approaches.

    hep-phhep-exJHEP(2019)·13 citations
21. 21*

    Adding Pseudo-Observables to the Four-Lepton Experimentalist's Toolbox

    James S. Gainer🇺🇸 · Martín González-Alonso🇨🇭 · Admir Greljo🇩🇪 · Senad Isaković🇧🇦 · Gino Isidori🇨🇭 · Andrey Korytov🇺🇸 · Joseph Lykken🇺🇸 · David Marzocca🇮🇹 · Konstantin T. Matchev🇺🇸 · Predrag Milenović🇨🇭 · Guenakh Mitselmakher🇺🇸 · Stephen Mrenna🇺🇸 and 3 other authors

    The "golden" channel, in which the newly-discovered Higgs boson decays to four leptons by means of intermediate vector bosons, is important for determining the properties of the Higgs boson and for searching for subtle new physics effects. Different approaches exist for parametrizing the relevant Higgs couplings in this channel; here we relate the use of pseudo-observables to methods based on specifying the most general amplitude or Lagrangian terms for the $HVV$ interactions. We also provide projections for sensitivity in this channel in several novel scenarios, illustrating the use of pseudo-observables, and analyze the role of kinematic distributions and (ratios of) rates in such $H\to 4\ell$ studies.

    hep-phJHEP(2018)·9 citations
22. 22*

    Heavy quarkonium production through the top quark rare decays via the channels involving flavor changing neutral currents

    Juan-Juan Niu🇨🇳 · Lei Guo🇨🇳 · Hong-Hao Ma🇧🇷 · Shao-Ming Wang🇨🇳

    In the paper, we discuss the possibility of observation of heavy quarkoniums via the processes involving flavor changing neutral currents (FCNC). More explicitly, we systematically calculate the production of heavy charmonium and $(c\bar{b})$-quarkonium through the top quark semi-exclusive rare FCNC decays in the framework of the non-relativistic QCD (NRQCD) factorization theory. Our results show that the total decay widths ${\Gamma }_{t\to {\eta }_c}=1.20_{-0.51-0.45}^{+1.04+1.14}\times 10^{-16}$ GeV, ${\Gamma }_{t\to J/\psi }=1.37_{-0.51-0.51}^{+1.03+1.30}\times 10^{-16}$ GeV, ${\Gamma }_{t\to B_c}=2.06_{-0.17-0.54}^{+0.17+0.91}\times 10^{-18}$ GeV, and ${\Gamma }_{t\to B_c^{\ast }}=6.27_{-0.62-1.64}^{+0.63+2.78}\times 10^{-18}$ GeV, where the uncertainties are from variation of quark masses and renormalization scales. Even though the decay widths are small, it is important to make a systematic study on the production of charmonium and $(c\bar{b})$-quarkonium through the top-quark decays via FCNC in the Standard Model, which will provide useful guidance for future new physics research from the heavy quarkonium involved processes.

    hep-phhep-exEPJC(2018)·4 citations
23. 23*

    $a$-theorem at large $N_f$

    Oleg Antipin🇭🇷 · Nicola Andrea Dondi🇩🇰 · Francesco Sannino🇩🇰 · Anders Eller Thomsen🇩🇰

    We determine the Jack and Osborn a-function and related metric for gauge-fermion theories to leading order in the large number of fermions and to all orders in the gauge coupling, demonstrating that the strong a-theorem is violated for the minimal choice of the a-function.

    ↳ hep-thhep-lathep-phPRD(2019)·7 citations
24. 24*

    Searching for ultra-light dark matter with optical cavities

    Andrew A. Geraci🇺🇸 · Colin Bradley🇺🇸 · Dongfeng Gao🇨🇳 · Jonathan Weinstein🇺🇸 · Andrei Derevianko🇺🇸

    We discuss the use of optical cavities as tools to search for dark matter (DM) composed of virialized ultra-light fields (VULFs). Such fields could lead to oscillating fundamental constants, resulting in oscillations of the length of rigid bodies. We propose searching for these effects via differential strain measurement of rigid and suspended-mirror cavities. We estimate that more than two orders of magnitude of unexplored phase space for VULF DM couplings can be probed at VULF Compton frequencies in the audible range of 0.1-10 kHz.

    ↳ astro-ph.IMgr-qchep-phphysics.atom-ph+1PRL(2019)·84 citations
25. 25*

    Critical behavior of the QED${}_3$-Gross-Neveu-Yukawa model at four loops

    Nikolai Zerf🇩🇪 · Peter Marquard🇩🇪 · Rufus Boyack🇨🇦 · Joseph Maciejko🇨🇦

    We study the universal critical properties of the QED${}_3$-Gross-Neveu-Yukawa model with $N$ flavors of four-component Dirac fermions coupled to a real scalar order parameter at four-loop order in the $ϵ$ expansion below four dimensions. For $N=1$, the model is conjectured to be infrared dual to the $SU(2)$-symmetric noncompact $\mathbb{C}$P${}^1$ model, which describes the deconfined quantum critical point of the Néel-valence-bond-solid transition of spin-1/2 quantum antiferromagnets on the two-dimensional square lattice. For $N=2$, the model describes a quantum phase transition between an algebraic spin liquid and a chiral spin liquid in the spin-1/2 kagomé antiferromagnet. For general $N$ we determine the order parameter anomalous dimension, the correlation length exponent, the stability critical exponent, as well as the scaling dimensions of $SU(N)$ singlet and adjoint fermion mass bilinears at the critical point. We use Padé approximants to obtain estimates of critical properties in 2+1 dimensions.

    ↳ cond-mat.str-elhep-phhep-thPRB(2018)·46 citations
26. 26*

    Gravitational waves and the polarizations in Hořava gravity after GW170817

    Yungui Gong🇨🇳 · Shaoqi Hou🇨🇳 · Eleftherios Papantonopoulos🇬🇷 · Dimitrios Tzortzis🇬🇷

    The gravitational waves of Hořava gravity, their polarization states and their possible observational signatures are discussed. Using the gauge-invariant variable formalism, we found the three polarization modes in Hořava gravity excited by the three physical degrees of freedom contained in this theory. In particular, the scalar degree of freedom excites a mix of the transverse breathing and the longitudinal polarizations. The constraints from the previous experimental observations are taken into account, especially including the speed bound from the observations of GW170817 and GRB 170817A. It was found that Hořava theory is highly constrained. Within the experimentally allowed parametric space, we studied whether the pulsar timing arrays and the Gaia mission can be used to distinguish the different polarizations. After calculating the cross-correlation functions between the redshifts of photons and the astrometric positions of stars, one concludes that it is possible to tell whether there exits the scalar polarization using pulsar timing arrays and the Gaia mission.

    ↳ gr-qchep-phhep-thPRD(2018)·50 citations
27. 27*

    The Effect of Vorticity on QGP Thermodynamics

    Brett McInnes🇸🇬

    Currently there is intense interest in the properties of the Quark-Gluon Plasma produced in peripheral collisions of heavy ions at various facilities, such as the RHIC. In particular, it is essential to understand the difference between such plasmas and their more readily understood counterparts produced in nearly central collisions. The differences arise primarily from the intense magnetic and vorticity fields generated in the QGP in the peripheral case. It has been argued that the magnetic fields might have a profound effect on QGP thermodynamics. Here we will argue, using a gauge-gravity model incorporating the recently proposed holographic vorticity bound, that vorticity also has important consequences for the plasma thermodynamics, in particular, for the entropy density at a given impact energy. A crucial point in our analysis is the need to determine the fate of bulk gravitational parameters when the duality translates them to the boundary.

    ↳ hep-thhep-ph5 citations
28. 28*

    First data at Belle II and Dark Sector physics

    Giacomo De Pietro🇮🇹

    Belle II is a major upgrade of the Belle experiment and operates at the $B$-factory SuperKEKB in Japan. Since the SuperKEKB collider has a design luminosity of 8$\times$10${}^{35}$ cm${}^{-2}$s${}^{-1}$, about 40 times larger than that of KEKB, Belle II aims to collect 50 ab${}^{-1}$ of data over a period of 8 years. The first data taking runs for physics analyses have started in April 2018, with a lower luminosity than the designed one for commissioning purposes. Even with the early dataset, having an integrated luminosity up to 20 fb${}^{-1}$, Belle II can improve the current results in the Dark Sector field. In this paper we will present the expected sensitivity of Belle II for invisibly decaying Dark Photons, for Axion-Like Particles and for invisibly decaying $Z^{\prime }$ assuming a $L_{\mu }-L_{\tau }$ model.

    ↳ hep-exhep-phPoS(2018)·10 citations
29. 29*

    Effective Field Theory of Black Hole Echoes

    C.P. Burgess🇨🇦 · Ryan Plestid🇨🇦 · Markus Rummel🇨🇦

    Gravitational wave `echoes' during black-hole merging events have been advocated as possible signals of modifications to gravity in the strong-field (but semiclassical) regime. In these proposals the observable effect comes entirely from the appearance of nonzero reflection probability at the horizon, which vanishes for a standard black hole. We show how to apply EFT reasoning to these arguments, using and extending earlier work for localized systems that relates choices of boundary condition to the action for the physics responsible for these boundary conditions. EFT reasoning applied to this action argues that linear `Robin' boundary conditions dominate at low energies, and we determine the relationship between the corresponding effective coupling (whose value is the one relevant low-energy prediction of particular modifications to General Relativity for these systems) and the phenomenologically measurable near-horizon reflection coefficient. Because this connection involves only near-horizon physics it is comparatively simple to establish, and we do so for perturbations in both the Schwarzschild geometry (which is the one most often studied theoretically) and the Kerr geometry (which is the one of observational interest for post-merger ring down). In passing we identify the renormalization-group evolution of the effective couplings as a function of a regularization distance from the horizon, that enforces how physics does not depend on the precise position where the boundary conditions are imposed. We show that the perfect-absorber/perfect-emitter boundary conditions of General Relativity correspond to the only fixed points of this evolution. Nontrivial running of all other RG evolution reflects how modifications to gravity necessarily introduce new physics near the horizon.

    ↳ gr-qchep-phhep-thJHEP(2018)·46 citations
30. 30*

    The light-quark contribution to the leading HVP term of the muon $g-2$ from twisted-mass fermions

    D. Giusti🇮🇹 · F. Sanfilippo🇮🇹 · S. Simula🇮🇹

    We present a lattice calculation of the leading Hadronic Vacuum Polarization (HVP) contribution of the light u- and d-quarks to the anomalous magnetic moment of the muon, $a_{\mu }^{\mathrm{HVP}}(ud)$, adopting the gauge configurations generated by the European Twisted Mass Collaboration with $N_f=2+1+1$ dynamical quarks at three values of the lattice spacing with pion masses in the range 210 - 450 MeV. Thanks to several lattices at fixed values of the light-quark mass and scale but with different sizes we perform a careful investigation of finite-volume effects (FVEs). In order to remove FVEs we develop an analytic representation of the vector correlator, which describes the lattice data for time distances larger than $\simeq 0.2$ fm. The representation is based on quark-hadron duality at small and intermediate time distances and on the two-pion contributions in a finite box at larger time distances. After extrapolation to the physical pion point and to the continuum limit we obtain $a_{\mu }^{\mathrm{HVP}}(ud)=619.0(17.8)\cdot 10^{-10}$. Adding the contribution of strange and charm quarks, obtained by ETMC, and an estimate of the isospin-breaking corrections and quark-disconnected diagrams from the literature we get $a_{\mu }^{\mathrm{HVP}}(udsc)=683(19)\cdot 10^{-10}$, which is consistent with recent results based on dispersive analyses of the experimental cross section data for $e^{+}{e}^{-}$ annihilation into hadrons. Using our analytic representation of the vector correlator, taken at the physical pion mass in the continuum and infinite volume limits, we provide the first eleven moments of the polarization function and we compare them with recent results of the dispersive analysis of the ${\pi }^{+}{\pi }^{-}$ channels. We estimate also the light-quark contribution to the missing part of $a_{\mu }^{\mathrm{HVP}}$ not covered in the MUonE experiment.

    ↳ hep-lathep-exhep-phPRD(2018)·90 citations
31. 31*

    Gauge invariance and the Englert-Brout-Higgs mechanism in non-Hermitian field theories

    Jean Alexandre🇬🇧 · John Ellis🇬🇧 · Peter Millington🇬🇧 · Dries Seynaeve🇬🇧

    We discuss $\mathcal{P}\mathcal{T}$-symmetric Abelian gauge field theories, as well as their extension to the Englert-Brout-Higgs mechanism for generating a mass for a vector boson. Gauge invariance is not straightforward, and we discuss the different related problems, as well as a solution which consists in coupling the gauge field to a current that is not conserved. Non-Hermiticity then necessarily precludes the Lorenz gauge condition but nevertheless allows for a consistent formulation of the theory. We therefore generalise the Englert-Brout-Higgs mechanism to $\mathcal{P}\mathcal{T}$-symmetric field theories, opening the way to constructing non-Hermitian extensions of the Standard Model and new scenarios for particle model-building.

    ↳ hep-thhep-phPRD(2019)·51 citations
32. 32*

    Likelihood-free inference with an improved cross-entropy estimator

    Markus Stoye🇬🇧 · Johann Brehmer🇺🇸 · Gilles Louppe🇧🇪 · Juan Pavez🇨🇱 · Kyle Cranmer🇺🇸

    We extend recent work (Brehmer, et. al., 2018) that use neural networks as surrogate models for likelihood-free inference. As in the previous work, we exploit the fact that the joint likelihood ratio and joint score, conditioned on both observed and latent variables, can often be extracted from an implicit generative model or simulator to augment the training data for these surrogate models. We show how this augmented training data can be used to provide a new cross-entropy estimator, which provides improved sample efficiency compared to previous loss functions exploiting this augmented training data.

    ↳ stat.MLcs.LGhep-phphysics.data-an53 citations
33. 33*

    M-Theory Exotic Scalar Glueball Decays to Mesons at Finite Coupling

    Vikas Yadav🇮🇳 · Aalok Misra🇮🇳

    Using the pull-back of the perturbed type IIA metric corresponding to the perturbation of arXiv:hep-th/1306.4339's M-theory uplift of arXiv:hep-th/0902.1540's UV-complete top-down type IIB holographic dual of large-$N$ thermal QCD, at finite coupling, we obtain the interaction Lagrangian corresponding to exotic scalar glueball($G_E$)-$\rho /\pi$-meson interaction, linear in the exotic scalar glueball and up to quartic order in the $\pi$ mesons. In the Lagrangian, the coupling constants are determined as (radial integrals of) arXiv:hep-th/1306.4339's M-theory uplift's metric components and six radial functions appearing in the M-theory metric perturbations. Assuming $M_G>2M_{\rho }$, we then compute $\rho \to 2\pi ,G_E\to 2\pi ,2\rho ,\rho +2\pi$ decay widths as well as the direct and indirect (mediated via $\rho$ mesons) $G_E\to 4\pi$ decays. For numerics, we choose $f0[1710]$ and compare with previous calculations. We emphasize that our results can be made to match PDG data (and improvements thereof) exactly by appropriate tuning of some constants of integration appearing in the solution of the M-theory metric perturbations and the $\rho$ and $\pi$ meson radial profile functions - a flexibility that our calculations permits.

    ↳ hep-thhep-phnucl-thJHEP(2018)·15 citations
34. 34*

    Cosmic acceleration and de Sitter expansion in hybrid mass varying neutrino model

    H. Mohseni Sadjadi🇮🇷 · V. Anari🇮🇷

    A nonminimally coupled hybrid dark energy model is introduced. The dark energy evolution is triggered by mass varying neutrinos. Quintessence evolution begins from an initial point, with an insignificant dark energy density, and arrives at a final de Sitter attractor. While initially, for a Higgs-like potential, the non-minimal coupling keeps the system in a state with negligible dark energy density, finally the second quintessence conducts the evolution to a stable fixed point. These evolutions occur through successive $Z_2$ symmetry breakings.

    ↳ gr-qchep-phhep-thJCAP(2018)·21 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.