Tue·Nov 28, 2017Tuesday·November 28, 2017

1. 01*

   Power Counting and Modes in SCET

   Raymond Goerke🇨🇦 · Michael Luke🇨🇦

   We present a formulation of soft-collinear effective theory (SCET) in the two-jet sector as a theory of decoupled sectors of QCD coupled to Wilson lines. The formulation is manifestly boost-invariant, does not require the introduction of ultrasoft modes at the hard matching scale Q, and has manifest power counting in inverse powers of Q. The spurious infrared divergences which arise in SCET when ultrasoft modes are not included in loops disappear when the overlap between the sectors is correctly subtracted, in a manner similar to the familiar zero-bin subtraction of SCET. We illustrate this approach by analyzing deep inelastic scattering in the endpoint region in SCET and comment on other applications.

   hep-phJHEP(2018)·17 citations
2. 02*

   Renormalization of Dijet Operators at Order $1/Q^2$ in Soft-Collinear Effective Theory

   Raymond Goerke🇨🇦 · Matthew Inglis-Whalen🇨🇦

   We make progress towards resummation of power-suppressed logarithms in dijet event shapes such as thrust, which have the potential to improve high-precision fits for the value of the strong coupling constant. Using a newly developed formalism for Soft-Collinear Effective Theory (SCET), we identify and compute the anomalous dimensions of all the operators that contribute to event shapes at order $1/Q^2$. These anomalous dimensions are necessary to resum power-suppressed logarithms in dijet event shape distributions, although an additional matching step and running of observable-dependent soft functions will be necessary to complete the resummation. In contrast to standard SCET, the new formalism does not make reference to modes or $\lambda$-scaling. Since the formalism does not distinguish between collinear and ultrasoft degrees of freedom at the matching scale, fewer subleading operators are required when compared to recent similar work. We demonstrate how the overlap subtraction prescription extends to these subleading operators.

   hep-phJHEP(2018)·30 citations
3. 03*

   Solar flares and their associated processes

   O.M.Boyarkin🇧🇾 · I.O.Boyarkina🇮🇹

   The evolution of the solar neutrino flux which is described by the wave function ${\Psi }^T=({\nu }_{eL},{\nu }_{XL},{\overline{\nu }}_{eL},{\overline{\nu }}_{XL})$ is examined. Our treatment of the problem holds for any standard model (SM) extensions possessing nonzero dipole magnetic and anapole moments. When the solar neutrino flux moves through the solar flare (SF) region in the preflare period, then it undergoes the additional (compared with the SM) resonance conversions. As a result, the weakening the electron neutrinos flux takes place. On the other hand, existence of the additional resonances lead to appearance of the ${\overline{\nu }}_{eL}$ and ${\overline{\nu }}_{XL}$ neutrinos that could be detected by the terrestrial detectors. The hypothesis of the ${\nu }_e$-induced $\beta$-decays is also discussed. According to it, before the large SF, decreasing the $\beta$-decay rate for some elements takes place. The possible influence of the electron antineutrino flux produced in the superflares on the regime of the hypothetical georeactor is considered.

   hep-ph0 citations
4. 04*

   Top-quark mass determination at the LHC: a theory overview

   Gennaro Corcella🇮🇹

   I briefly overview the methods employed at the LHC to extract the top-quark mass, taking particular care about the theory uncertainty and the dependence on the Monte Carlo hadronization parameters.

   hep-phPoS(2017)·2 citations
5. 05*

   IceCube's astrophysical neutrino energy spectrum from CPT violation

   Jiajun Liao🇺🇸 · Danny Marfatia🇺🇸

   The 6-year dataset of high-energy starting events (HESE) at IceCube indicates a spectrum of astrophysical neutrinos much softer than expected from the Fermi shock acceleration mechanism. On the other hand, IceCube's up-going muon neutrino dataset and Fermi-LAT's gamma-ray spectrum point to an $E^{-2}$ neutrino spectrum. If the HESE data above 200 TeV are fit with the latter flux, an excess at lower energies ensues, which then suggests a multicomponent spectrum. We show that the HESE dataset can be explained by a single $E^{-2}$ power-law neutrino flux from a muon-damped $p\gamma$ source if neutrino interactions are modified by CPT violation. The low-energy excess is naturally explained by the pileup of events from superluminal neutrino decay, and there is no cutoff at high energies due to the contribution of subluminal antineutrinos. The best-fit scenario with CPT violation also predicts the observation of Glashow resonance events in the near future.

   hep-phastro-ph.HEhep-exPRD(2018)·20 citations
6. 06*

   Partonic quasi-distributions of the pion in chiral quark models

   Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸

   The evaluation of partonic distributions presents a challenge for QCD, and in particular for its Euclidean lattice realization. Recently, objects called quasi-distributions (which become standard distributions in a limit of the longitudinal momentum of the target hadron going to infinity) have been proposed. We present a non-perturbative, dynamical evaluation of the quark quasi-distribution amplitude (QDA) of the pion in the framework of chiral quark models (the Nambu--Jona-Lasinio model and the spectral quark model). We arrive at simple but nontrivial analytic expressions, where the dependence on the longitudinal momentum, the momentum fraction, or the transverse-momentum (for the unintegrated objects) can be explicitly assessed. For the parton distribution amplitude (PDA), we carry out the necessary QCD evolution from the constituent quark model scale to higher scales accessible on the lattice, and compare favorably to the LaMET data.

   hep-phhep-latPoS(2018)·4 citations
7. 07*

   Role of repulsive interactions in the interplay with missing strange resonances

   Paolo Alba🇩🇪

   The standard implementation of the HRG model has been shown to be unable to describe all the available data on QCD matter. Here we show the balance of repulsive and attractive hadronic interactions on QCD thermodynamics through observables both calculated by lattice simulations and measured in experiment. Attractive interactions are mediated by resonance formation, which are here implemented through extra states predicted by the Quark Model, while repulsive interactions are modelled by means of Excluded Volume (EV) effects. Informations on flavour dependent effective sizes are extracted. It is found that EV effects are present in lattice QCD thermodynamics, and are essential for a comprehensive description of higher order fluctuations of conserved charges.

   hep-phEPJ Web Conf.(2018)·0 citations
8. 08*

   The C2HDM revisited

   Duarte Fontes🇵🇹 · Margarete Mühlleitner🇩🇪 · Jorge C. Romão🇵🇹 · Rui Santos🇵🇹 · João P. Silva🇵🇹 · Jonas Wittbrodt🇩🇪

   The complex two-Higgs doublet model is one of the simplest ways to extend the scalar sector of the Standard Model to include a new source of CP-violation. The model has been used as a benchmark model to search for CP-violation at the LHC and as a possible explanation for the matter-antimatter asymmetry of the Universe. In this work, we re-analyse in full detail the softly broken ${\mathbb{Z}}_2$ symmetric complex two-Higgs doublet model (C2HDM). We provide the code C2HDM_HDECAY implementing the C2HDM in the well-known HDECAY program which calculates the decay widths including the state-of-the-art higher order QCD corrections and the relevant off-shell decays. Using C2HDM_HDECAY together with the most relevant theoretical and experimental constraints, including electric dipole moments (EDMs), we review the parameter space of the model and discuss its phenomenology. In particular, we find cases where large CP-odd couplings to fermions are still allowed and provide benchmark points for these scenarios. We examine the prospects of discovering CP-violation at the LHC and show how theoretically motivated measures of CP-violation correlate with observables.

   hep-phJHEP(2018)·95 citations
9. 09*

   Femtoscopy of stopped protons

   Andrzej Bialas🇵🇱 · Adam Bzdak🇵🇱 · Volker Koch🇺🇸

   The longitudinal proton-proton femtoscopy (HBT) correlation function, based on the idea that in a heavy ion collision at $\sqrt{s}\lesssim 20$ GeV stopped protons are likely to be separated in configuration space, is evaluated. It shows a characteristic oscillation which appears sufficiently pronounced to be accessible in experiment. The proposed measurement is essential for estimating the baryon density in the central rapidity region, and can be also viewed as an (almost) direct verification of the Lorentz contraction of the fast-moving nucleus.

   hep-phhep-exnucl-exnucl-thPRC(2019)·1 citation
10. 10*

    Recent Developments in Higher-Order Calculations: Hard Functions at NLO with GoSam

    Alessandro Broggio🇩🇪 · Andrea Ferroglia🇺🇸 · Nicolas Greiner🇨🇭 · Giovanni Ossola🇺🇸

    In this presentation, we will focus on a recent applications of the GoSam 2.0 automated framework which goes beyond the official scope of this code, originally designed for one-loop fixed order calculations. In particular, we describe a customized version of GoSam that has been recently employed to study the production of a top-antitop pair in association with a vector boson or with the Higgs boson to next-to-next-to-leading logarithmic accuracy. In the context of these calculations, the modified version of GoSam was used to evaluate the NLO hard functions which are needed to carry out the resummation of soft gluon emission effects. We also briefly comment on the ongoing efforts to generalize integrand reduction and unitarity for higher order calculation, towards the goal of developing efficient alternative computational techniques for the evaluation of scattering amplitudes beyond one loop.

    hep-phPoS(2017)·3 citations
11. 11*

    Lepton universality violation and right-handed currents in $b\to c\tau \nu$

    Xiao-Gang He🇹🇼 · German Valencia🇦🇺

    We consider the recent LHCb result for $B_c\to J/\psi \tau \nu$ in conjunction with the existing anomalies in $R(D)$ and $R(D^{\star })$ within the framework of a right-handed current with enhanced couplings to the third generation. The model predicts a linear relation between the observables and their SM values in terms of two combinations of parameters. The strong constraints from $b\to s\gamma$ on $W-W^{\prime }$ mixing effectively remove one of the combinations of parameters resulting in an approximate proportionality between all three observables and their SM values. To accommodate the current averages for $R(D)$ and $R(D^{\star })$, the $W^{\prime }$ mass should be near 1 TeV, and possibly accessible to direct searches at the LHC. In this scenario we find that $R(J/\psi )$ is enhanced by about 20\% with respect to its SM value and about 1.5$\sigma$ below the central value of the LHCb measurement. The predicted $d\Gamma /d{q}^2$ distribution for $B\to D(D^{\star })\tau \nu$ is in agreement with the measurement and the model satisfies the constraint from the $B_c$ lifetime.

    hep-phhep-exPLB(2018)·58 citations
12. 12*

    Study of rare semileptonic $B_c^{+}\to D^{+}\nu \bar{\nu }$ decay in the light-cone quark model

    Nisha Dhiman🇮🇳 · Harleen Dahiya🇮🇳

    We study the exclusive semileptonic rare $B_c^{+}\to D^{+}\nu \bar{\nu }$ decay in the framework of light-cone quark model. The transition form factors $f_{+}(q^2)$ and $f_T(q^2)$ are evaluated in the time-like region using the analytic continuation method in $q^{+}=0$ frame. The analytic solutions of these form factors are compared with the results obtained from the double pole parametric form. The branching ratio for $B_c^{+}\to D^{+}\nu \bar{\nu }$ decay is calculated and compared with the other theoretical model predictions. The predicted results in this model can be tested at the LHCb experiments in near future which will help in testing the unitarity of CKM quark mixing matrix, thus, providing an insight into the phenomenon of CP violation.

    hep-phAdv.High Energy Phys.(2018)·1 citation
13. 13*

    A Systematic and Efficient Method to Compute Multi-loop Master Integrals

    Xiao Liu🇨🇳 · Yan-Qing Ma🇨🇳 · Chen-Yu Wang🇨🇳

    We propose a novel method to compute multi-loop master integrals by constructing and numerically solving a system of ordinary differential equations, with almost trivial boundary conditions. Thus it can be systematically applied to problems with arbitrary kinematic configurations. Numerical tests show that our method can not only achieve results with high precision, but also be much faster than the only existing systematic method sector decomposition. As a by product, we find a new strategy to compute scalar one-loop integrals without reducing them to master integrals.

    hep-phPLB(2018)·282 citations
14. 14*

    Production of $\rho (770)$, $\eta$ pairs in the decays $\rho (1450)\to \rho (770)\eta$, $\tau \to \rho (770)\eta {\nu }_{\tau }$, and in the process of $e^{+}{e}^{-}\to \rho (770)\eta$ in the Extended Nambu - Jona-Lasinio model

    M. K. Volkov🇷🇺 · K. Nurlan🇷🇺 · A . A. Pivovarov🇷🇺

    Production of $\rho (770)$, $\eta$ pairs at colliding of electron-positron beams and in the decays $\rho (1450)\to \rho (770)\eta$, $\tau \to \rho (770)\eta {\nu }_{\tau }$ is calculated in the framework of the Nambu - Jona-Lasinio model. In the process of electron-positron annihilation and the $\tau$ - lepton decay the contributions of the intermediate $\rho (770)$ vector meson in the ground and first radially excited state are taken into account. The theoretical prediction for the decay $\tau \to \rho (770)\eta {\nu }_{\tau }$ is given. The obtained results for other processes are in satisfactory agreement with the experimental data.

    hep-phJETP Lett.(2017)·9 citations
15. 15*

    Prediction of triple-charm molecular pentaquarks

    Rui Chen🇨🇳 · Atsushi Hosaka🇯🇵 · Xiang Liu🇨🇳

    In a one-boson-exchange model, we study molecular states of double-charm baryon (${\Xi }_{cc}(3621)$) and a charmed meson ($D$ and $D^{\ast }$). Our model indicates that there exist two possible triple-charm molecular pentaquarks, a ${\Xi }_{cc}D$ state with $I(J^P)=0(1/2^{-})$ and a ${\Xi }_{cc}{D}^{\ast }$ state with $I(J^P)=0(3/2^{-})$. In addition, we also extend our formula to explore ${\Xi }_{cc}{\bar{B}}^{(\ast )}$, ${\Xi }_{cc}{\bar{D}}^{(\ast )}$, and ${\Xi }_{cc}{B}^{(\ast )}$ systems, and find more possible heavy flavor molecular pentaquarks, a ${\Xi }_{cc}\bar{B}$ state with $I(J^P)=0(1/2^{-})$, a ${\Xi }_{cc}{\bar{B}}^{\ast }$ state with $I(J^P)=0(3/2^{-})$, and ${\Xi }_{cc}{\bar{D}}^{\ast }/{\Xi }_{cc}{B}^{\ast }$ states with $I(J^P)=0(1/2^{-})$. Experimental search for these predicted triple-charm molecular pentaquarks is encouraged.

    hep-phPRD(2017)·47 citations
16. 16*

    Top Quark Properties

    Cen Zhang🇨🇳

    Recently, experimental collaborations have reported $\mathcal{O}(10)$ upper limits on the signal strength of four-top production at the LHC, which already leads to competitive constraints on certain type of top-quark operators. On the other hand, developments in the $b$-jet charge tagging algorithms open up new possibilities for the direct measurement of the top-quark width. In this talk, we briefly discuss some recent studies in these two directions.

    hep-phhep-ex0 citations
17. 17*

    Inferring type and scale of noncommutativity from the PTOLEMY experiment

    Raul Horvat🇭🇷 · Josip Trampetic🇭🇷 · Jiangyang You🇭🇷

    If neutrinos are Dirac particles and their right-handed component can be copiously produced in the early universe, then they could influence a direct observation of the cosmic neutrino background, which, most likely, will come about with the recently proposed PTOLEMY experiment. For the production mechanism of right-handed neutrinos we use a state-of-the-art version of gauge field theory deformed by the spacetime noncommutativity, to disclose by it not only the decoupling temperature for the said neutrino component, but also the otherwise hidden coupling temperature. Considering two relevant processes, the plasmon decay and the neutrino elastic scattering, we study the interplay between the structure of the noncommutativity parameter ${\theta }^{\mu \nu }$ (type of noncommutativity) and the reheating temperature after inflation to obtain otherwise elusive upper bound on the scale of noncommutativity ${\Lambda }_{\mathrm{NC}}$. If PTOLEMY enhanced capture rate is due to spacetime noncommutativity, we verify that a nontrivial maximum upper bound on ${\Lambda }_{\mathrm{NC}}$ (a way below the Planck scale) emerges for a space-like ${\theta }^{\mu \nu }$ and sufficiently high reheating temperature.

    hep-phhep-thEPJC(2018)·8 citations
18. 18*

    Calculation of resonances from $K\pi$ scattering

    A. Rodas🇪🇸 · J.R. Pelaez🇪🇸 · J. Ruiz de Elvira🇨🇭

    We present a determination of the mass, width and coupling of the strange resonances appearing in pion-kaon scattering below 1.8 GeV, namely the much debated $K_0^{\ast }(800)$ or $\kappa$, the scalar $K_0^{\ast }(1430)$, the $K^{\ast }(892)$ and $K^{\ast }(1410)$ vectors, the spin-two $K_2^{\ast }(1430)$ as well as the spin-three $K_3^{\ast }(1780)$. The parameters of each resonance are determined using a direct analytic continuation of the pion-kaon partial waves by means of Padé approximants, thus avoiding any particular model description of their pole positions and residues, while taking into account the analytic requirements imposed by dispersion relations.

    hep-phPoS(2018)·0 citations
19. 19*

    Iterative and Iterative-Noniterative Integral Solutions in 3-Loop Massive QCD Calculations

    J. Ablinger · A. Behring · J. Blümlein · A. De Freitas · E. Imamoglu · M. van Hoeij A. von Manteuffel · C.G. Raab · C.-S. Radu · C. Schneider

    Various of the single scale quantities in massless and massive QCD up to 3-loop order can be expressed by iterative integrals over certain classes of alphabets, from the harmonic polylogarithms to root-valued alphabets. Examples are the anomalous dimensions to 3-loop order, the massless Wilson coefficients and also different massive operator matrix elements. Starting at 3-loop order, however, also other letters appear in the case of massive operator matrix elements, the so called iterative non-iterative integrals, which are related to solutions based on complete elliptic integrals or any other special function with an integral representation that is definite but not a Volterra-type integral. After outlining the formalism leading to iterative non-iterative integrals,we present examples for both of these cases with the 3-loop anomalous dimension ${\gamma }_{qg}^{(2)}$ and the structure of the principle solution in the iterative non-interative case of the 3-loop QCD corrections to the $\rho$-parameter.

    hep-phhep-thmath-phmath.AG+1PoS(2017)·9 citations
20. 20*

    A simple model to explain the observed muon sector anomalies and small neutrino masses

    Lobsang Dhargyal🇮🇳

    Since its inception, no decisive departure from the predictions of Standard Model (SM) has been reported. But recently various experiments have observed few hints of possible departure from SM predictions in lepton flavor universality observables such as $R_{K^{(\ast )}}$, $P_5^{{}^{\prime }}$, muon (g-2), $R(D^{(\ast )})$ etc. Many of these observable where deviation from SM in the range of (2-4)$\sigma$ were observed are related to muon ($\mu$) lepton. So these deviations may be some hint of a possible New Physics (NP) in the muon sector. In this work we extend the SM by introducing two SM singlet heavy charged leptons ($F_e,F_{\mu }$) whose left handed components are charged under a new $U(1{)}_F$ gauge symmetry, one color triplet lepto-quark (${\varphi }_Q$) doublet under $SU(2{)}_L$, one inert Higgs doublet (${\varphi }_l$), three very heavy Majorana neutrinos ($N_{iR}$), all of which are odd under a $Z_2$ discrete symmetry. One more scalar ($\varphi$) charged only under the $U(1{)}_F$ whose VEV give masses to the $U(1{)}_F$ gauge boson as well as the heavy leptons. With these new particles, we show that the observed anomalies in the muon sector as well as small neutrino masses can be explained with taking into account all the other experimental and theoretical constrains till date.

    hep-phJ.Phys.G(2019)·9 citations
21. 21*

    COHERENT constraints to conventional and exotic neutrino physics

    D. K. Papoulias🇬🇷 · T. S. Kosmas🇬🇷

    The process of neutral-current coherent elastic neutrino-nucleus scattering, consistent with the Standard Model (SM) expectation, has been recently measured by the COHERENT experiment at the Spallation Neutron Source. On the basis of the observed signal and our nuclear calculations for the relevant Cs and I isotopes, the extracted constraints on both conventional and exotic neutrino physics are updated. The present study concentrates on various SM extensions involving vector and tensor nonstandard interactions as well as neutrino electromagnetic properties, with an emphasis on the neutrino magnetic moment and the neutrino charge radius. Furthermore, models addressing a light sterile neutrino state and scenarios with new propagator fields---such as vector $Z^{\prime }$ and scalar bosons---are examined, and the corresponding regions excluded by the COHERENT experiment are presented.

    hep-phPRD(2018)·168 citations
22. 22*

    Predictions for multiplicities and flow harmonics in 5.44 TeV Xe+Xe collisions at the CERN Large Hadron Collider

    K. J. Eskola🇫🇮 · H. Niemi🇩🇪 · R. Paatelainen🇫🇮 · K. Tuominen🇫🇮

    We present the next-to-leading-order event-by-event EKRT model predictions for the centrality dependence of the charged hadron multiplicity in the pseudorapidity interval $|\eta |\le 0.5$, and for the centrality dependence of the charged hadron flow harmonics $v_n\{2\}$ obtained from 2-particle cumulants, in $\sqrt{s_{NN}}=5.44$ TeV Xe+Xe collisions at the CERN Large Hadron Collider. Our prediction for the 0-5 \% central charged multiplicity is $d{N}_{\mathrm{ch}}/d\eta =1218\pm 46$. We also predict $v_n\{2\}$ in Xe+Xe collisions to increase more slowly from central towards peripheral collisions than those in a Pb+Pb system. We find that at $10\dots 50$\% centralities $v_2\{2\}$ is smaller and $v_3\{2\}$ is larger than in the Pb+Pb system while $v_4\{2\}$ is of the same magnitude in both systems. We also find that the ratio of flow harmonics in Xe+Xe collisions and in Pb+Pb collisions shows a slight sensitivity to the temperature dependence of the shear-viscosity-to-entropy ratio. As we discuss here, the new nuclear mass-number systematics especially in the flow harmonics serves as a welcome further constraint for describing the space-time evolution of a heavy-ion system and for determining the shear viscosity and other transport properties of strongly interacting matter.

    hep-phnucl-thPRC(2018)·52 citations
23. 23*

    Thermodynamic characterizations of exotic and missing states

    Eugenio Megias🇪🇸 · Enrique Ruiz Arriola🇪🇸 · Lorenzo Luis Salcedo🇪🇸

    Thermal shifts and fluctuations at finite temperature below the deconfinement crossover of QCD from hadronic matter to the Quark-Gluon Plasma provide a viable way to look for exotic and missing states with given quantum numbers in the hadronic spectrum. We study a realization of the Hadron Resonance Gas model in the light quark ($uds$) flavor sector of QCD to study: i) the entropy shifts, and ii) the fluctuations of electric charge, baryon number and strangeness; and extract from them the possible existence of missing and exotic states from a comparison with lattice data. The analysis of the entropy shift based on the free energy of the Polyakov loop suggests the existence of exotic hybrids $gq\bar{q}$ and $gqqq$.

    hep-phhep-latnucl-thPoS(2018)·3 citations
24. 24*

    Probing the Dark Sector through Mono-Z Boson Leptonic Decays

    Daneng Yang🇨🇳 · Qiang Li🇨🇳

    Collider search for dark matter production has been performed over the years based on high pT standard model signatures balanced by large missing transverse energy. The mono-Z boson production with leptonic decay has a clean signature with the advantage that the decaying electrons and muons can be precisely measured. This signature not only enables reconstruction of the Z boson rest frame, but also makes possible recovery of the underlying production dynamics through the decaying lepton angular distribution. In this work, we exploit full information carried by the leptonic Z boson decays to set limits on coupling strength parameters of the dark sector. We study simplified dark sector models with scalar, vector, and tensor mediators and observe among them different signatures in the distribution of angular coefficients.Specifically, we show that angular coefficients can be used to distinguish different scenarios of the spin-0 and spin-1 models, including the ones with parity-odd and charge conjugation parity-odd operators. To maximize the statistical power, we perform a matrix element method study with a dynamic construction of event likelihood function. We parametrize the test statistic such that sensitivity from the matrix element is quantified through a term measuring the shape difference. Our results show that the shape differences provide significant improvements in the limits, especially for the scalar mediator models. We also present an example application of a matrix-element-kinematic-discriminator, an easier approach that is applicable for experimental data.

    hep-phJHEP(2018)·9 citations
25. 25*

    Nonperturbative Analysis of the Electroweak Phase Transition in the Two Higgs Doublet Model

    Jens O. Andersen🇳🇴 · Tyler Gorda🇫🇮 · Andreas Helset🇩🇰 · Lauri Niemi🇫🇮 · Tuomas V. I. Tenkanen🇫🇮 · Anders Tranberg🇳🇴 · Aleksi Vuorinen🇫🇮 · David J. Weir🇫🇮

    We perform a nonperturbative study of the electroweak phase transition (EWPT) in the two Higgs doublet model (2HDM) by deriving a dimensionally reduced high-temperature effective theory for the model, and matching to known results for the phase diagram of the effective theory. We find regions of the parameter space where the theory exhibits a first-order phase transition. In particular, our findings are consistent with previous perturbative results suggesting that the primary signature of a first-order EWPT in the 2HDM is $m_{A_0}>m_{H_0}+m_Z$.

    hep-phPRL(2018)·106 citations
26. 26*

    Non-minimal quartic inflation in classically conformal U(1)${}_X$ extended Standard Model

    Satsuki Oda🇯🇵 · Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸 · Dai-suke Takahashi🇯🇵

    We propose quartic inflation with non-minimal gravitational coupling in the context of the classically conformal U(1)_X extension of the SM. In this model, the U(1)_X gauge symmetry is radiatively broken through the Coleman-Weinberg (CW) mechanism, by which the U(1)_X gauge boson (Z' boson) and the right-handed neutrinos (RHNs) acquire their masses. We consider their masses in the range of O(10 GeV)-O(10 TeV), which are accessible to high energy collider experiments. The radiative U(1)_X gauge symmetry breaking also generates a negative mass squared for the SM Higgs doublet, and the electroweak symmetry breaking occurs subsequently. We identify the U(1)_X Higgs field with inflaton and calculate the inflationary predictions. Due to the CW mechanism, the inflaton quartic coupling during inflation, which determines the inflationary predictions, is correlated to the U(1)_X gauge coupling. With this correlation, we investigate complementarities between the inflationary predictions and the current constraint from the Z' boson resonance search at the LHC Run-2 as well as the prospect of the search for the Z' boson and the RHNs at the future collider experiments. The radiative U(1)_X gauge symmetry breaking also generates a negative mass squared for the SM Higgs doublet, and the electroweak symmetry breaking occurs subsequently. We identify the U(1)_X Higgs field with inflaton and calculate the inflationary predictions. Due to the Coleman-Weinberg mechanism, the inflaton quartic coupling during inflation, which determines the inflationary predictions, is correlated to the U(1)_X gauge coupling. With this correlation, we investigate complementarities between the inflationary predictions and the current constraint from the Z' boson resonance search at the LHC Run-2 as well as the prospect of the search for the Z' boson and the RHNs at the future collider experiments.

    hep-phastro-ph.COhep-exPRD(2018)·29 citations
27. 27*

    On Landau pole in the minimal 3-3-1 model

    Edison T. Franco🇧🇷 · V. Pleitez🇧🇷

    We show that in 3-3-1 models the existence of a Landau-like pole in the coupling constant related to the $U(1{)}_X$ factor, $g_X$, in a certain value of ${\sin }^2{\theta }_W$, arises only assuming that the condition to match the gauge coupling constants of the standard model, $g_{2L}$, with that of the 3-3-1 model, $g_{3L}$, is valid for all energies. However, if we impose that this matching condition is valid only at a given energy, say $\mu =M_Z$, the pole arises when ${\sin }^2{\theta }_X({\mu }_{LP})=1$, which is the only weak mixing angle in the models. The value of ${\mu }_{LP}$ depends on the energy scales, ${\mu }_m$ and ${\mu }_{331}$, in which the matching and the 3-3-1 symmetry is fully realized, respectively. We also show that $g_{2L}$ and $g_{3L}$ have different running with energy. Therefore, differently from what is usually assumed in the literature, these couplings can not be considered equal for all energies. As a consequence, the fermion couplings with neutral vector bosons are different if we write them in terms of $\sin {\theta }_X$ instead of $\sin {\theta }_W$.

    hep-phhep-exhep-th1 citation
28. 28*

    The HiggsTools Handbook: Concepts and observables for deciphering the Nature of the Higgs Sector

    M. Boggia (Freiburg U.)🇩🇪 · J. M. Cruz-Martinez (Durham U., IPPP)🇬🇧 · Hjalte Frellesvig (KIT-TTP)🇬🇷 · E. W. N. Glover (Durham U., IPPP)🇬🇧 · Raquel Gomez-Ambrosio (Durham U., IPPP)🇬🇧 · Giulia Gonella (Freiburg U.)🇩🇪 · Y. Haddad (Durham U., IPPP)🇬🇧 · Agnieszka Ilnicka (Zurich U., ETH and PSI Villigen)🇨🇭 · S. P. Jones (MPI Munich)🇩🇪 · Z. Kassabov (Milano U., INFN)🇮🇹 · F. Krauss (Durham U., IPPP)🇬🇧 · T. Megy (Freiburg U.)🇩🇪 and 6 other authors

    This Report summarizes some of the activities of the HiggsTools Initial Training Network working group in the period 2015-2017. The main goal of this working group was to produce a document discussing various aspects of state-of-the-art Higgs physics at the Large Hadron Collider (LHC) in a pedagogic manner. The first part of the Report is devoted to a description of phenomenological searches for New Physics at the LHC. As the experimental measurements become more and more precise, there is a pressing need for a consistent framework in which deviations from the SM predictions can be computed precisely. We critically review the use of the ąppa}-framework, fiducial and simplified template cross sections, effective field theories, pseudo-observables and phenomenological Lagrangians. In the second part of the Report, we propose ${\phi }_{\eta }^{\ast }$ as a new and complementary observable for studying Higgs boson production at large transverse momentum in the case where the Higgs boson decays to two photons. We make a detailed study of the phenomenology of the ${\phi }_{\eta }^{\ast }$ variable, contrasting the behaviour with the Higgs transverse momentum distribution using a variety of theoretical tools including event generators and fixed order perturbative computations.

    hep-phhep-exJ.Phys.G(2018)·30 citations
29. 29*

    Heavy Majorana neutrino pair productions at the LHC in minimal U(1) extended Standard Model

    Arindam Das🇰🇷 · Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸

    In our recent paper [1], we explored a prospect of discovering the heavy Majorana right-handed neutrinos (RHNs) at the future LHC in the context of the minimal non-exotic U(1) extended Standard Model (SM), where a pair of RHNs are created via decay of resonantly produced massive U(1) gauge boson ($Z^{\prime }$). We pointed out that this model can yield a significant enhancement of the branching ratio of the $Z^{\prime }$ boson to a pair of RHNs, which is crucial for discovering the RHNs under the very severe LHC Run-2 constraint from the search for the $Z^{\prime }$ boson with dilepton final states. In this paper, we perform a general parameter scan to evaluate the maximum production rate of the same-sign dilepton final states (smoking gun signature of Majorana RHNs production) at the LHC, while reproducing the neutrino oscillation data. We also consider the minimal non-exotic U(1) model with an alternative charge assignment. In this case, we find a further enhancement of the branching ratio of the $Z^{\prime }$ boson to a pair of RHNs compared to the conventional case, which opens up a possibility of discovering the RHNs even before the $Z^{\prime }$ boson at the future LHC experiment.

    hep-phhep-exEPJC(2018)·75 citations
30. 30*

    Review of the empirical evidence for superluminal particles and the $3+3$ model of the neutrino masses

    Robert Ehrlich🇺🇸

    A review is given of hypothetical faster-than-light tachyons and the development of the author's $3+3$ model of the neutrino mass states, which includes one tachyonic mass state doublet. Published empirical evidence for the model is summarized, including an interpretation of the mysterious Mont Blanc neutrino burst from SN 1987A as being due to tachyonic neutrinos having $m^2=-0.38e{V}^2.$ This possibility requires an 8 MeV antineutrino line from SN 1987A, which a new dark matter model has been found to support. Furthermore, this dark matter model is supported by several data sets: $\gamma -$rays from the galactic center, and the Kamiokande-II neutrino data on the day of SN 1987A. The KATRIN experiment should serve as the unambiguous test of the $3+3$ model and its tachyonic mass state.

    hep-phAdv.Astron.(2019)·6 citations
31. 31*

    Vector boson tagged jets and jet substructure

    Ivan Vitev🇺🇸

    In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. $Z^0$-tagging and $\gamma$-tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.

    hep-phnucl-exnucl-thEPJ Web Conf.(2018)·1 citation
32. 32*

    Directly detecting sub-GeV dark matter with electrons from nuclear scattering

    Matthew J. Dolan🇦🇺 · Felix Kahlhoefer🇩🇪 · Christopher McCabe🇬🇧

    Dark matter (DM) particles with mass in the sub-GeV range are an attractive alternative to heavier weakly-interacting massive particles, but direct detection of such light particles is challenging. If however DM-nucleus scattering leads to ionisation of the recoiling atom, the resulting electron may be detected even if the nuclear recoil is unobservable. We demonstrate that including this effect significantly enhances direct detection sensitivity to sub-GeV DM. Existing experiments set world-leading limits, and future experiments may probe the cross sections relevant for thermal freeze-out.

    hep-phastro-ph.COhep-exPRL(2018)·202 citations
33. 33*

    Statistical Analyses of Higgs- and Z-Portal Dark Matter Models

    John Ellis🇬🇧 · Andrew Fowlie🇦🇺 · Luca Marzola🇪🇪 · Martti Raidal🇪🇪

    We perform frequentist and Bayesian statistical analyses of Higgs- and Z-portal models of dark matter particles with spin 0, 1/2 and 1. Our analyses incorporate data from direct detection and indirect detection experiments, as well as LHC searches for monojet and monophoton events, and we also analyze the potential impacts of future direct detection experiments. We find acceptable regions of the parameter spaces for Higgs-portal models with real scalar, neutral vector, Majorana or Dirac fermion dark matter particles, and Z-portal models with Majorana or Dirac fermion dark matter particles. In many of these cases, there are interesting prospects for discovering dark matter particles in Higgs or Z decays, as well as dark matter particles weighing $\gtrsim 100$ GeV. Negative results from planned direct detection experiments would still allow acceptable regions for Higgs- and Z-portal models with Majorana or Dirac fermion dark matter particles.

    hep-phPRD(2018)·52 citations
34. 34*

    Dedicated Strategies for Triboson Signals from Cascade Decays of Vector Resonances

    Kaustubh Agashe🇺🇸 · Jack H. Collins🇺🇸 · Peizhi Du🇺🇸 · Sungwoo Hong🇺🇸 · Doojin Kim🇨🇭 · Rashmish K. Mishra🇮🇹

    New colorless electroweak (EW) charged spin-1 particles with mass of a few TeV arise in numerous extensions of the Standard Model (SM). Decays of such a vector into a pair of SM particles, either fermions or EW bosons, are well studied. Many of these models have an additional scalar, which can lead to (and even dominate in certain parameter regions) a novel decay channel for the heavy vector particles instead - into a SM EW boson and the scalar, which subsequently decays into a SM EW boson pair. In this work, we focus on the scalar being relatively heavy, roughly factor of two lighter than the vector particles, rendering its decay products well separated. Such a cascade decay results in a final state with three isolated bosons. We argue that for this "triboson" signal the existing diboson searches are not quite optimal due to combinatorial ambiguity for three identical bosons, and in addition, due to a relatively small signal cross-section determined by the heaviness of the decaying vector particle. In order to isolate the signal, we demonstrate that tagging all three bosons, followed by use of the full triboson invariant mass distribution as well as that of appropriate subsets of dibosons, is well motivated. We develop these general strategies in detail within the context of a specific class of models that are based on extensions of the standard warped extra-dimensional scenario. We also point out that a similar analysis would apply to models with an enlarged EW gauge sector in four dimensions, even if they involve a different Lorentz structure for the relevant couplings.

    hep-phhep-exPRD(2019)·48 citations
35. 35*

    Quantum no-scale regimes in string theory

    Thibaut Coudarchet🇫🇷 · Claude Fleming🇫🇷 · Herve Partouche🇫🇷

    We show that in generic no-scale models in string theory, the flat, expanding cosmological evolutions found at the quantum level can be attracted to a "quantum no-scale regime", where the no-scale structure is restored asymptotically. In this regime, the quantum effective potential is dominated by the classical kinetic energies of the no-scale modulus and dilaton. We find that this natural preservation of the classical no-scale structure at the quantum level occurs when the initial conditions of the evolutions sit in a subcritical region of their space. On the contrary, supercritical initial conditions yield solutions that have no analogue at the classical level. The associated intrinsically quantum universes are sentenced to collapse and their histories last finite cosmic times. Our analysis is done at 1-loop, in perturbative heterotic string compactified on tori, with spontaneous supersymmetry breaking implemented by a stringy version of the Scherk-Schwarz mechanism.

    ↳ hep-thgr-qchep-phNPB(2018)·24 citations
36. 36*

    The 2PI effective theory at next-to-leading order using the functional renormalization group

    M.E. Carrington🇨🇦 · S.A. Friesen🇨🇦 · B.A. Meggison🇨🇦 · C.D. Phillips🇨🇦 · D. Pickering🇨🇦 · K. Sohrabi🇨🇦

    We consider a symmetric scalar theory with quartic coupling in 4-dimensions. We show that the 4 loop 2PI calculation can be done using a renormalization group method. The calculation involves one bare coupling constant which is introduced at the level of the Lagrangian and is therefore conceptually simpler than a standard 2PI calculation, which requires multiple counterterms. We explain how our method can be used to do the corresponding calculation at the 4PI level, which can not be done using any known method by introducing counterterms.

    ↳ hep-thhep-phPRD(2018)·15 citations
37. 37*

    A Further Test of Lorentz Violation from the Rest-Frame Spectral Lags of Gamma-Ray Bursts

    Jun-Jie Wei🇨🇳 · Xue-Feng Wu🇨🇳

    Lorentz invariance violation (LIV) can manifest itself by an energy-dependent vacuum dispersion of light, which leads to arrival-time differences of photons with different energies originating from the same astronomical source. The spectral lags of gamma-ray bursts (GRBs) have been widely used to investigate the possible LIV effect. However, all current investigations used lags extracted in the observer frame only. In this work, we present, for the first time, an analysis of the LIV effect and its redshift dependence in the cosmological rest frame. Using a sample of 56 GRBs with known redshifts, we obtain a robust limit on LIV by fitting their rest-frame spectral lag data both using a maximization of the likelihood function and a minimum ${\chi }^2$ statistic. Our analysis indicates that there is no evidence of LIV. Additionally, we test the LIV in different redshift ranges by dividing the full sample into four redshift bins. We also find no evidence for the redshift variation of the LIV effect.

    ↳ astro-ph.HEgr-qchep-phApJ(2017)·25 citations
38. 38*

    Structure of quantum corrections in $\mathcal{N}=1$ supersymmetric gauge theories

    K.V.Stepanyantz🇷🇺

    Some recent research of quantum corrections in $\mathcal{N}=1$ supersymmetric theories is briefly reviewed. The most attention is paid to the theories regularized by higher covariant derivatives. In particular, we discuss, how the NSVZ and NSVZ-like relations appear with this regularization and how one can construct the NSVZ scheme in all orders.

    ↳ hep-thhep-phBled Workshops Phys.(2017)·26 citations
39. 39*

    Worldline colour fields and non-Abelian quantum field theory

    James P. Edwards🇲🇽 · Olindo Corradini🇮🇹

    In the worldline approach to non-Abelian field theory the colour degrees of freedom of the coupling to the gauge potential can be incorporated using worldline "colour" fields. The colour fields generate Wilson loop interactions whilst Chern-Simons terms project onto an irreducible representation of the gauge group. We analyse this augmented worldline theory in phase space focusing on its supersymmetry and constraint algebra, arriving at a locally supersymmetric theory in superspace. We demonstrate canonical quantisation and the path integral on $S^1$ for simple representations of $SU(N)$.

    ↳ hep-thhep-phmath-phmath.MPEPJ Web Conf.(2018)·8 citations
40. 40*

    Novel Soft-Pion Theorem for Long-Range Nuclear Parity Violation

    Xu Feng🇨🇳 · Feng-Kun Guo🇨🇳 · Chien-Yeah Seng🇨🇳

    The parity-odd effect in the Standard Model weak neutral current reveals itself in the long-range parity-violating nuclear potential generated by the pion exchanges in the $\Delta I=1$ channel with the parity-odd pion-nucleon coupling constant $h_{\pi }^1$. Despite decades of experimental and theoretical efforts, the size of this coupling constant is still not well-understood. In this Letter we derive a soft-pion theorem relating $h_{\pi }^1$ and the neutron-proton mass-splitting induced by an artificial parity-even counterpart of the $\Delta I=1$ weak Lagrangian, and demonstrate that the theorem still holds exact at the next-to-leading order in chiral perturbation theory. A considerable amount of simplification is expected in the study of $h_{\pi }^1$ by using either lattice or other QCD models following its reduction from a parity-odd proton-neutron-pion matrix element to a simpler spectroscopic quantity. The theorem paves the way to much more precise calculations of $h_{\pi }^1$, and thus a quantitative test of the strangeness-conserving neutral current interaction of the Standard Model is foreseen.

    ↳ nucl-thhep-lathep-phPRL(2018)·12 citations
41. 41*

    Comment on "Relation between scattering amplitude and Bethe-Salpeter wave function in quantum field theory"

    Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Noriyoshi Ishii🇯🇵

    We invalidate the arguments given in [T.Yamazaki and Y.Kuramashi, Phys. Rev. D96, 114511 (2017)] over the HAL QCD method for hadron-hadron interactions on the lattice. We also pose questions on the practical usefulness of the method proposed in this reference.

    ↳ hep-lathep-phnucl-thPRD(2018)·12 citations
42. 42*

    Recoil effect on the g factor of Li-like ions

    V. M. Shabaev🇷🇺 · D. A. Glazov🇷🇺 · A. V. Malyshev🇷🇺 · I. I. Tupitsyn🇷🇺

    The nuclear recoil effect on the $g$ factor of Li-like ions is evaluated. The one-electron recoil contribution is treated within the framework of the rigorous QED approach to first order in the electron-to-nucleus mass ratio $m/M$ and to all orders in the parameter $\alpha Z$. These calculations are performed in a range $Z=3-92$. The two-electron recoil term is calculated for low- and middle-$Z$ ions within the Breit approximation using a four-component approach. The results for the two-electron recoil part obtained in the paper strongly disagree with the previous calculations performed using an effective two-component Hamiltonian. The obtained value for the recoil effect is used to calculate the isotope shift of the $g$ factor of Li-like ${}^A$Ca${}^{17+}$ with $A=40$ and $A=48$ which was recently measured. It is found that the new theoretical value for the isotope shift is closer to the experimental one than the previously obtained value.

    ↳ physics.atom-phhep-phPRL(2017)·29 citations
43. 43*

    Nuclear recoil effect on $g$ factor of heavy ions: prospects for tests of quantum electrodynamics in a new region

    A. V. Malyshev🇷🇺 · V. M. Shabaev🇷🇺 · D. A. Glazov🇷🇺 · I. I. Tupitsyn🇷🇺

    The nuclear recoil effect on the $g$ factor of H- and Li-like heavy ions is evaluated to all orders in $\alpha Z$. The calculations include an approximate treatment of the nuclear size and the electron-electron interaction corrections to the recoil effect. As the result, the second largest contribution to the theoretical uncertainty of the $g$-factor values of ${}^{208}$Pb${}^{79+}$ and ${}^{238}$U${}^{89+}$ is strongly reduced. Special attention is paid to tests of the QED recoil effect on the $g$ factor in experiments with heavy ions. It is found that, while the QED recoil effect on the $g$-factor value is masked by the uncertainties of the nuclear size and nuclear polarization contributions, it can be probed on a few-percent level in the specific difference of the $g$ factors of H- and Li-like heavy ions. This provides a unique opportunity to test QED in a new region --- strong-coupling regime beyond the Furry picture.

    ↳ physics.atom-phhep-phPisma Zh.Eksp.Teor.Fiz.(2017)·14 citations
44. 44*

    Universality of multi-field $\alpha$-attractors

    Ana Achúcarro🇳🇱 · Renata Kallosh🇺🇸 · Andrei Linde🇺🇸 · Dong-Gang Wang🇳🇱 · Yvette Welling🇳🇱

    We study a particular version of the theory of cosmological $\alpha$-attractors with $\alpha =1/3$, in which both the dilaton (inflaton) field and the axion field are light during inflation. The kinetic terms in this theory originate from maximal $\mathcal{N}=4$ superconformal symmetry and from maximal $\mathcal{N}=8$ supergravity. We show that because of the underlying hyperbolic geometry of the moduli space in this theory, it exhibits double attractor behavior: their cosmological predictions are stable not only with respect to significant modifications of the dilaton potential, but also with respect to significant modifications of the axion potential: $n_s\simeq 1-\frac{2}{N}$, $r\simeq \frac{4}{N^2}$. We also show that the universality of predictions extends to other values of $\alpha \lesssim \mathcal{O}(1)$ with general two-field potentials that may or may not have an embedding in supergravity. Our results support the idea that inflation involving multiple, not stabilized, light fields on a hyperbolic manifold may be compatible with current observational constraints for a broad class of potentials.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2018)·103 citations
45. 45*

    Bound states and the classical double copy

    Walter D. Goldberger🇺🇸 · Alexander K. Ridgway🇺🇸

    We extend the perturbative classical double copy to the analysis of bound systems. We first obtain the leading order perturbative gluon radiation field sourced by a system of interacting color charges in arbitrary time dependent orbits, and test its validity by taking relativistic bremsstrahlung and non-relativistic bound state limits. By generalizing the color to kinematic replacement rules recently used in the context of classical bremsstrahlung, we map the gluon emission amplitude to the radiation fields of dilaton gravity sourced by interacting particles in generic (self-consistent) orbits. As an application, we reproduce the leading post-Newtonian radiation fields and energy flux for point masses in non-relativistic orbits from the double copy of gauge theory.

    ↳ hep-thgr-qchep-phPRD(2018)·151 citations
46. 46*

    Universal scaling of non-equilibrium critical fluctuations from Langevin dynamics of model A

    Shanjin Wu🇨🇳 · Huichao Song🇨🇳

    Within the framework of the Kibble-Zurek Mechanism, we investigate the universal behavior of the non-equilibrium critical fluctuations, using the Langevin dynamics of model A. With properly located typical time, length and angle scales, ${\tau }_{\text{mbox}KZ}$, $l_{\text{mbox}KZ}$, and ${\theta }_{\text{mbox}KZ}$, the constructed functions ${\bar{f}}_n((\tau -{\tau }_c)/{\tau }_{\text{mbox}KZ},{\theta }_{\text{mbox}KZ})$ (n=1...4) for the cumulants of the sigma field show universal behavior near the critical point, which are independent from some non-universal factors, such as the relaxation time or the evolution trajectory.

    ↳ nucl-thhep-phPoS(2018)·1 citation
47. 47*

    Violation of the KSS Bound in Holographic Bjorken-Flow

    Shingo Takeuchi🇻🇳

    In a system with a Bjorken-flow (BF), considering the inside of a BF as a subsystem for the reason explained in the body text, we compute entanglement entropy appearing in our side holographically . BF consists of many concentrically scattering quark-gluon plasmas created by colliding two masses of hadrons. Our BF is defined in the boundary space in an asymptoticly five-dimensional Anti de-Sitter space with a growing Schwartzshild black hole. %, where its Hawking temperature diminishes with time. In our analysis we can get a parameter prescribing our bulk space-time in terms of the boundary QCD's variables. Using this, we find that the $\eta /s$ dips from $1/4\pi$ just for a moment before asymptoting to $1/4\pi$ at infinitely large time. Since $1/4\pi$ is the KSS bound, this result is intriguing as an example of violation of the KSS bound.

    ↳ hep-thhep-ph1 citation
48. 48*

    Topology of the ${}^3$He-A film on corrugated graphene substrate

    G.E. Volovik🇫🇮

    Thin film of superfluid ${}^3$He on a corrugated graphene substrate represents topological matter with a smooth disorder. It is possible that the atomically smooth disorder produced by the corrugated graphene does not destroy the superfluidity even in a very thin film, where the system can be considered as quasi two-dimensional topological material. This will allow us to study the effect of disorder on different classes of the $2+1$ topological materials: the chiral ${}^3$He-A with intrinsic quantum Hall effect and the time reversal invariant planar phase with intrinsic spin quantum Hall effect. In the limit of smooth disorder, the system can be considered as a Chern mosaic -- a collection of domains with different values of Chern numbers. In this limit, the quantization of the Hall conductance is determined by the percolated domain, while the density of the fermionic states is determined by the edge modes on the boundaries of the finite domains. This system can be useful for the general consideration of disorder in the topological matter.

    ↳ cond-mat.str-elhep-phJETP Lett.(2018)·3 citations
49. 49*

    A statistical method to estimate low-energy hadronic cross sections

    Gábor Balassa🇭🇺 · Péter Kovács🇭🇺 · György Wolf🇭🇺

    In this article we propose a model based on the Statistical Bootstrap approach to estimate the cross sections of different hadronic reactions up to a few GeV in c.m.s energy. The method is based on the idea, when two particles collide a so called fireball is formed, which after a short time period decays statistically into a specific final state. To calculate the probabilities we use a phase space description extended with quark combinatorial factors and the possibility of more than one fireball formation. In a few simple cases the probability of a specific final state can be calculated analytically, where we show that the model is able to reproduce the ratios of the considered cross sections. We also show that the model is able to describe proton\,-\,antiproton annihilation at rest. In the latter case we used a numerical method to calculate the more complicated final state probabilities. Additionally, we examined the formation of strange and charmed mesons as well, where we used existing data to fit the relevant model parameters.

    ↳ nucl-thhep-phEPJA(2018)·10 citations
50. 50*

    Recent Results on Light-Meson Spectroscopy from COMPASS

    Stefan Wallner (for the COMPASS Collaboration)🇩🇪

    The main goal of the spectroscopy program at COMPASS is to explore the light-meson spectrum below about $2\text{GeV}/c^2$ in diffractive production. Our flagship channel is the decay into three charged pions: $p+{\pi }^{-}\to {\pi }^{-}{\pi }^{-}{\pi }^{+}+p_{\text{recoil}}$, for which COMPASS has acquired the so far world's largest dataset of roughly $50\text{M}$ exclusive events using an $190\text{GeV}/c$ ${\pi }^{-}$ beam. Based on this dataset, we performed an extensive partial-wave analysis. In order to extract the resonance parameters of the ${\pi }_J$ and $a_J$ states that appear in the ${\pi }^{-}{\pi }^{-}{\pi }^{+}$ system, we performed the so far largest resonance-model fit, using Breit-Wigner resonances and non-resonant contributions. This method in combination with the high statistical precision of our measurement allows us to study ground and excited states. We have found an evidence of the $a_1(1640)$ and $a_2(1700)$ in our data, which are the first excitations of the $a_1(1260)$ and $a_2(1320)$, respectively. The relative strength of the excited states with respect to the corresponding ground state is larger in the $f_2(1270)\pi$ decay mode compared to the $\rho (770)\pi$ decay mode. We also study the spectrum of ${\pi }_2$ states in our data. Therefore, we simultaneously describe four $J^{PC}=2^{-+}$ waves in the resonance-model fit by using three ${\pi }_2$ resonances, the ${\pi }_2(1670)$, the ${\pi }_2(1880)$, and the ${\pi }_2(2005)$. Within the limits of our model, we can conclude that the ${\pi }_2(2005)$ is required to describe all four $2^{-+}$ waves properly.

    ↳ hep-exhep-phPoS(2018)·4 citations
51. 51*

    (Anti-)Symmetrizing Wave Functions

    Chethan Krishnan🇮🇳 · K.V. Pavan Kumar🇮🇳 · P. N. Bala Subramanian🇮🇳

    The construction of fully (anti-)symmetric states with many particles, when the single particle state carries multiple quantum numbers, is a problem that seems to have not been systematically addressed in the literature. A quintessential example is the construction of ground state baryon wave functions where the color singlet condition reduces the problem to just two (flavor and spin) quantum numbers. In this paper, we address the general problem by noting that it can be re-interpreted as an eigenvalue equation, and provide a formalism that applies to generic number of particles and generic number of quantum numbers. As an immediate result, we find a complete solution to the two quantum number case, from which the baryon wave function problem with arbitrary number of flavors follows. As a more elaborate illustration that reveals complications not visible in the two quantum number case, we present the complete class of states possible for a system of five fermionic particles with three quantum numbers each. Our formalism makes systematic use of properties of the symmetric group and Young tableaux. Even though our motivations to consider this question have their roots in SYK-like tensor models and holography, the problem and its solution should have broader applications.

    ↳ hep-thhep-phmath-phmath.MP+1J.Math.Phys.(2019)·4 citations
52. 52*

    Lattice QCD investigation of the structure of the $a_0(980)$ meson

    Constantia Alexandrou🇨🇾 · Joshua Berlin🇩🇪 · Mattia Dalla Brida🇮🇹 · Jacob Finkenrath🇨🇾 · Theodoros Leontiou🇨🇾 · Marc Wagner🇩🇪

    We investigate the quark content of the scalar meson $a_0(980)$ using lattice QCD. To this end we consider correlation functions of six different two- and four-quark interpolating fields. We evaluate all diagrams, including diagrams, where quarks propagate within a timeslice, e.g. with closed quark loops. We demonstrate that diagrams containing such closed quark loops have a drastic effect on the final results and, thus, may not be neglected. Our analysis shows that in addition to the expected spectrum of two-meson scattering states there is an additional energy level around the two-particle thresholds of $K+\bar{K}$ and $\eta +\pi$. This additional state, which is a candidate for the $a_0(980)$ meson, couples to a quark-antiquark as well as to a diquark-antidiquark interpolating field, indicating that it is a superposition of an ordinary $\bar{q}q$ and a tetraquark structure. The analysis is performed using AMIAS, a novel statistical method based on the sampling of all possible spectral decompositions of the considered correlation functions, as well as solving standard generalized eigenvalue problems.

    ↳ hep-lathep-phPRD(2018)·26 citations
53. 53*

    Constant-Roll (Quasi-)Linear Inflation

    Alexandros Karam🇬🇷 · Luca Marzola🇪🇪 · Thomas Pappas🇬🇷 · Antonio Racioppi🇪🇪 · Kyriakos Tamvakis🇬🇷

    In constant-roll inflation, the scalar field that drives the accelerated expansion of the Universe is rolling down its potential at a constant rate. Within this framework, we highlight the relations between the Hubble slow-roll parameters and the potential ones, studying in detail the case of a single-field Coleman-Weinberg model characterised by a non-minimal coupling of the inflaton to gravity. With respect to the exact constant-roll predictions, we find that assuming an approximate slow-roll behaviour yields a difference of $\Delta r=0.001$ in the tensor-to-scalar ratio prediction. Such a discrepancy is in principle testable by future satellite missions. As for the scalar spectral index $n_s$, we find that the existing 2-$\sigma$ bound constrains the value of the non-minimal coupling to ${\xi }_{\varphi }\sim 0.29-0.31$ in the model under consideration.

    ↳ astro-ph.COgr-qchep-phJCAP(2018)·75 citations
54. 54*

    van der Waals Interactions and Hadron Resonance Gas: Role of resonance widths modeling on conserved charges fluctuations

    Volodymyr Vovchenko🇩🇪 · Paolo Alba🇩🇪 · Mark I. Gorenstein🇺🇦 · Horst Stoecker🇩🇪

    The quantum van der Waals (QvdW) extension of the ideal hadron resonance gas (HRG) model which includes the attractive and repulsive interactions between baryons -- the QvdW-HRG model -- is applied to study the behavior of the baryon number related susceptibilities in the crossover temperature region. Inclusion of the QvdW interactions leads to a qualitatively different behavior of susceptibilities, in many cases resembling lattice QCD simulations. It is shown that for some observables, in particular for ${\chi }_{11}^{BQ}/{\chi }_2^B$, effects of the QvdW interactions essentially cancel out. It is found that the inclusion of the finite resonance widths leads to an improved description of ${\chi }_2^B$, but it also leads to a worse description of ${\chi }_{11}^{BQ}/{\chi }_2^B$, as compared to the lattice data. On the other hand, inclusion of the extra, unconfirmed baryons into the hadron list leads to a simultaneous improvement in the description of both observables.

    ↳ nucl-thhep-phEPJ Web Conf.(2018)·4 citations
55. 55*

    $\varphi$ meson in nuclear matter and nuclei

    J. J. Cobos-Martínez🇲🇽 · K.Tsushima🇧🇷 · G. Krein🇧🇷 · A. W. Thomas🇦🇺

    The mass and decay width of the $\varphi$ meson in cold nuclear matter are computed in an effective Lagrangian approach, with the medium dependence of these properties obtained by evaluating kaon-antikaon loop contributions to the $\varphi$ self-energy. At normal nuclear matter density, we find a downward shift of the $\varphi$ mass by a few percent, while the decay width is enhanced by an order of magnitude. We also present $\varphi$--nucleus bound state energies and absorption widths for some selected nuclei, using complex optical potentials obtained in the local density approximation. Our results suggest that the $\varphi$ should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths.

    ↳ nucl-thhep-phnucl-exPoS(2018)·3 citations
56. 56*

    Gluons and gravitons at one loop from ambitwistor strings

    Yvonne Geyer🇺🇸 · Ricardo Monteiro🇺🇸

    We present new and explicit formulae for the one-loop integrands of scattering amplitudes in non-supersymmetric gauge theory and gravity, valid for any number of particles. The results exhibit the colour-kinematics duality in gauge theory and the double-copy relation to gravity, in a form that was recently observed in supersymmetric theories. The new formulae are expressed in a particular representation of the loop integrand, with only one quadratic propagator, which arises naturally from the framework of the loop-level scattering equations. The starting point in our work are the expressions based on the scattering equations that were recently derived from ambitwistor string theory. We turn these expressions into explicit formulae depending only on the loop momentum, the external momenta and the external polarisations. These formulae are valid in any number of spacetime dimensions for pure Yang-Mills theory (gluon) and its natural double copy, NS-NS gravity (graviton, dilaton, B-field), and we also present formulae in four spacetime dimensions for pure gravity (graviton). We perform several tests of our results, such as checking gauge invariance and directly matching our four-particle formulae to previously known expressions. While these tests would be elaborate in a Feynman-type representation of the loop integrand, they become straightforward in the representation we use.

    ↳ hep-thhep-phJHEP(2018)·71 citations
57. 57*

    Phase Space description of Nonlocal Teleparallel Gravity

    Kazuharu Bamba🇯🇵 · Davood Momeni🇴🇲 · Mudhahir Al Ajmi🇴🇲

    We study cosmological solutions in nonlocal teleparallel gravity or $f(T)$ theory, where $T$ is the torsion scalar in teleparallel gravity. This is a natural extenstion of the usual teleparallel gravity with nonlocal terms. In this work the phase space portrait proposed to describe the dynamics of an arbitrary flat, homogeneous cosmological background with a number of matter contents, both in early and late time epochs. The aim was to convert the system of the equations of the motion to a first order autonomous dynamical system and to find fixed points and attractors using numerical codes. For this purpose, firstly we derive effective forms of cosmological field equations describing the whole cosmic evolution history in a homogeneous and isotropic cosmological background and construct the autonomous system of the first order dynamical equations. In addition, we investigate the local stability in the dynamical systems called "the stable/unstable manifold" by introducing a specific form of the interaction between matter, dark energy, radiation and a scalar field. Furthermore, we explore the exact solutions of the cosmological equations in the case of de Sitter spacetime. In particular, we examine the role of an auxiliary function called "gauge" $\eta$ in the formation of such cosmological solutions and show whether the de Sitter solutions can exist or not. Moreover, we study the stability issue of the de Sitter solutions both in vacuum and non-vacuum spacetimes. It is demonstrated that for nonlocal $f(T)$ gravity, the stable de Sitter solutions can be produced even in vacuum spacetime.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2018)·17 citations
58. 58*

    Axial anomaly and nesting in the inhomogeneous chiral phase

    Ryo Yoshiike🇯🇵 · Toshitaka Tatsumi🇯🇵

    Axial anomaly and nesting is elucidated in the context of the inhomogeneous chiral phase. Using the Gross-Neveu models in 1+1 dimensions, we shall discuss axial anomaly and nesting from two different points of view: one is homogeneous chiral transition and the other is the Ferrel-Fulde-Larkin-Ovchinnikov (FFLO) state in superconductivity, which are closely related to each other by way of duality. It is shown that axial anomaly leads to a particular kind of the FFLO state within the two dimensional Nambu-Jona Lasinio model, where axial anomaly is manifested in a different mode. Nesting is a driving mechanism for both phenomena, but its realization has different features. We reconsider the effect of nesting in the context of duality.

    ↳ hep-thcond-mat.str-elhep-phPRD(2018)·1 citation

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