Fri·Aug 24, 2018Friday·August 24, 2018

1. 01*

   PDF Flavor Determination and the nCTEQ PDFs

   nCTEQ Collaboration: E. Godat🇺🇸 · D. B. Clark🇺🇸 · T. J. Hobbs🇺🇸 · T. Jezo🇨🇭 · J. Kent🇺🇸 · C. Keppel🇺🇸 · K. Kovarik🇩🇪 · A. Kusina🇵🇱 · F. Lyonnet🇺🇸 · J.G. Morfin🇺🇸 · F. I. Olness🇺🇸 · J.F. Owens🇺🇸 · I. Schienbein🇫🇷 · J. Y. Yu🇺🇸

   Recent LHC W/Z vector boson production data in proton-lead collisions are quite sensitive to the heavier flavors (especially the strange PDF), and this complements the information from neutrino-DIS data. As the proton flavor determination is dependent on nuclear corrections (from heavy target DIS, for example), LHC heavy ion measurements can also help improve proton PDFs. We introduce a new implementation of the nCTEQ code (nCTEQ++) based on C++ which has a modular strucure and enables us to easily integrate programs such as HOPPET, APPLgrid, and MCFM. Using ApplGrids generated from MCFM, we use nCTEQ++ to perform a fit including the $pPb$ LHC W/Z vector boson data.

   hep-phPoS(2018)·1 citation
2. 02*

   Dark matter in (partially) composite Higgs models

   Tommi Alanne🇩🇪 · Diogo Buarque Franzosi🇩🇪 · Mads T. Frandsen🇩🇰 · Martin Rosenlyst🇩🇰

   We construct composite and partially composite Higgs models with complex pseudo-Nambu--Goldstone (pNGB) dark matter states from four-dimensional gauge-Yukawa theories with strongly interacting fermions. The fermions are partially gauged under the electroweak symmetry, and the dynamical electroweak symmetry breaking sector is minimal. The pNGB dark matter particle is stable due to a $\mathrm{U}(1)$ technibaryon-like symmetry, also present in the technicolor limit of the models. However, the relic density is particle anti-particle symmetric and due to thermal freeze-out as opposed to the technicolor limit where it is typically due to an asymmetry. The pNGB Higgs is composite or partially composite depending on the origin of the Standard Model fermion masses, which impacts the dark matter phenomenology. We illustrate the important features with a model example invariant under an SU(4)$\times$ SU(2) $\times$ $\mathrm{U}(1)$ global symmetry.

   hep-phJHEP(2018)·24 citations
3. 03*

   A functional RG approach for the BFKL Pomeron

   J. Bartels🇩🇪 · C. Contreras🇨🇱 · G. P. Vacca🇮🇹

   In this paper we encode the perturbative BFKL leading logarithmic resummation, relevant for the Regge limit behavior of QCD scattering amplitudes, in the IR-regulated effective action which satisfies exact functional renormalization group equations. This is obtained using a truncation with a specific infinite set of non local vertices describing the multi-Regge kinematics (MRK). The goal is to use this framework to study, in the high energy limit and at larger transverse distances the transition to a much simpler effective local reggeon field theory, whose critical properties were recently investigated in the same framework. We perform a numerical analysis of the spectrum of the BFKL Pomeron deformed by the introduction of a Wilsonian infrared regulator to understand the properties of the leading poles (states) contributing to the high energy scattering.

   hep-phhep-thJHEP(2019)·9 citations
4. 04*

   MSSM Higgs Boson Searches at the LHC: Benchmark Scenarios for Run 2 and Beyond

   Emanuele Bagnaschi🇨🇭 · Henning Bahl🇩🇪 · Elina Fuchs🇮🇱 · Thomas Hahn🇩🇪 · Sven Heinemeyer🇪🇸 · Stefan Liebler🇩🇪 · Shruti Patel🇩🇪 · Pietro Slavich🇫🇷 · Tim Stefaniak🇩🇪 · Carlos E.M. Wagner🇺🇸 · Georg Weiglein🇩🇪

   We propose six new benchmark scenarios for Higgs boson searches in the Minimal Supersymmetric Standard Model. Our calculations follow the recommendations of the LHC Higgs Cross Section Working Group, and benefit from recent developments in the predictions for the Higgs-boson masses and mixing. All of the proposed scenarios are compatible with the most recent results from Run 2 of the LHC. In particular, they feature a scalar with mass and couplings compatible with those of the observed Higgs boson, and a significant portion of their parameter space is allowed by the limits from the searches for SUSY particles and additional Higgs bosons. We define a scenario where all SUSY particles are relatively heavy, and two scenarios with light colorless SUSY particles (charginos, neutralinos and, in one case, staus). In addition, we present two scenarios featuring alignment without decoupling, realized with either the lighter or the heavier scalar being SM-like, and a scenario with CP violation.

   hep-phEPJC(2019)·154 citations
5. 05*

   $B_u$ $\to$ $\psi M$ decays and $S$-$D$ wave mixing effects

   Yueling Yang🇨🇳 · Yupei Guo🇨🇳 · Junfeng Sun🇨🇳 · Na Wang🇨🇳 · Qin Chang🇨🇳 · Gongru Lu🇨🇳

   The $B_u$ $\to$ $\psi M$ decays are studied with the perturbative QCD approach, where the psion $\psi$ $=$ $\psi (2S)$, $\psi (3770)$, $\psi (4040)$ and $\psi (4160)$, and the light meson $M$ $=$ $\pi$, $K$, $\rho$ and $K^{\ast }$. The factorizable and nonfactorizable contributions, and the $S$-$D$ wave mixing effects on the psions are considered in the calculation. With appropriate inputs, the branching ratios for the $B_u$ $\to$ $\psi K$ decays are generally coincident with the experimental data within errors. However, due to the large theoretical and experimental errors, it is impossible for the moment to give a severe constraint on the $S$-$D$ wave mixing angles.

   hep-phCPC(2018)·3 citations
6. 06*

   Two-loop effective potential for generalized gauge fixing

   Stephen P. Martin🇺🇸 · Hiren H. Patel🇺🇸

   We obtain the two-loop effective potential for general renormalizable theories, using a generalized gauge-fixing scheme that includes as special cases the background-field $R_{\xi }$ gauges, the Fermi gauges, and the familiar Landau gauge, and using dimensional regularization in the bare and \MSbar renormalization schemes. As examples, the results are then specialized to the Abelian Higgs model and to the Standard Model. In the case of the Standard Model, we study how the vacuum expectation value and the minimum vacuum energy depend numerically on the gauge-fixing parameters. The results at fixed two-loop order exhibit non-convergent behavior for sufficiently large gauge-fixing parameters; this can presumably be addressed by a resummation of higher-order contributions.

   hep-phPRD(2018)·40 citations
7. 07*

   Interface effects of strange quark matter with density dependent quark masses

   Cheng-Jun Xia🇨🇳 · Guang-Xiong Peng🇨🇳 · Ting-Ting Sun🇨🇳 · Wan-Lei Guo🇨🇳 · Ding-Hui Lu🇨🇳 · Prashanth Jaikumar🇺🇸

   We study the interface effects in strangelets adopting mean-field approximation (MFA). Based on an equivparticle model, the linear confinement and leading-order perturbative interactions are included with density-dependent quark masses. By increasing the confinement strength, the surface tension and curvature term of strange quark matter (SQM) become larger, while the perturbative interaction does the opposite. For those parameters constrained according to the 2$M_{\odot }$ strange star, the surface tension is $\sim$2.4 MeV/fm${}^2$, while unstable SQM indicates a slightly larger surface tension. The obtained results are then compared with those predicted by the multiple reflection expansion (MRE) method. In contrast to the bag model case, it is found that MRE method overestimates the surface tension and underestimates the curvature term. To reproduce our results, the density of states in the MRE approach should be modified by proper damping factors.

   hep-phPRD(2018)·28 citations
8. 08*

   Sector-improved residue subtraction: Improvements and Applications

   Arnd Behring🇩🇪 · Michal Czakon🇩🇪 · Rene Poncelet🇩🇪

   We discuss two recent developments of the sector-improved residue subtraction scheme for handling real radiation at NNLO in QCD. We present a new phase space construction which minimizes the number phase space configurations for subtraction terms and we rederive the four-dimensional formulation of the scheme.

   hep-phPoS(2018)·4 citations
9. 09*

   The Tsallis entropy and the BKT-like phase transition in the impact parameter space for $pp$ and $\bar{p}p$ collisions

   S. D. Campos (Universidade Federal de São Carlos Sorocaba)🇧🇷 · V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺 · C. V. Moraes (Universidade Federal de São Carlos Sorocaba)🇧🇷

   In this paper, one uses the Tsallis entropy in the impact parameter space to study $pp$ and $\bar{p}p$ inelastic overlap function and the energy density filling up mechanism responsible by the so-called black disk limit as the energy increases. The Tsallis entropy is non-additive and non-extensive and these features are of fundamental importance since the internal constituents of $pp$ and $\bar{p}p$ are strongly correlated and also the existence of the multifractal character of the total cross-section. The entropy approach presented here takes into account a phase transition occurring inside the hadrons as the energy increases. This phase transition in the impact parameter space is quite similar to the Berezinskii-Kosterlitz-Thouless phase transition, possessing also a topological feature due to the multifractal dimension of the total cross-sections in $pp$ and $\bar{p}p$ scattering.

   hep-phPhys.Scripta(2020)·8 citations
10. 10*

    Strong Isospin Breaking in Heavy-Meson Decay Constants: Employing Borelized QCD Sum Rules in Local-Duality Limit

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇦🇹 · Silvano Simula🇮🇹

    Applying the QCD sum-rule machinery in the so-called local-duality shape to heavy-light mesons reveals that, as a consequence of the non-zero mass gap between up and down quarks, the leptonic decay constants of the neutral and charged versions of the $D,$ $D^{\ast },$ $B$ and $B^{\ast }$ mesons differ by approximately 1 MeV.

    hep-phhep-latnucl-thEPJ Web Conf.(2018)·1 citation
11. 11*

    Dynamical generation of neutrino mass scales

    Alfredo Aranda🇲🇽 · Cesar Bonilla🇩🇪 · Eduardo Peinado🇲🇽

    In this letter we present a simple scenario where the mass scales associated to atmospheric and solar neutrino oscillations are obtained through the dynamical generation of neutrino masses. The main idea is that the two different scales are the result of two independent mechanisms, namely a type-I seesaw generating the atmospheric scale and a radiative 1-loop process providing the solar one. A relation of the two scales, reminiscent of the so-called sequential dominance, is thus obtained.

    hep-phPLB(2019)·12 citations
12. 12*

    Sterile Neutrino Shortcuts in Asymmetrically Warped Extra Dimensions

    Dominik Döring🇩🇪 · Heinrich Päs🇩🇪

    Light sterile neutrinos are a popular extension of the Standard Model and are being discussed as a possible explanation for various neutrino oscillation anomalies, including the LSND, MiniBooNE, Reactor and Gallium anomalies. In order to avoid inconsistencies with constraints derived from disappearance experiments and cosmology, altered dispersion relations - which may originate from extra dimensions - have been proposed as a possible solution, dubbed as "neutrino shortcuts in the extra dimension". In this paper we develop a neutrino mass model with an asymmetrically warped extra dimension and two additional gauge singlet neutrinos, one being responsible for neutrino mass generation, while the other one is allowed to propagate in the extra dimension, giving rise to the desired change of the dispersion relation on the brane. By compactifying the extra-dimensional theory on an $S^1/{\mathbb{Z}}_2$ orbifold, deriving the shape of the Kaluza-Klein tower and identifying the effective sterile neutrino dispersion relation on the brane, we can demonstrate that the earlier, phenomenological models are recovered as the 4-dimensional effective field theory limit of the model discussed here.

    hep-phEPJC(2019)·10 citations
13. 13*

    Search for vector charmonium(-like) states in $e^{+}{e}^{-}\to \omega {\chi }_{cJ}$

    Jielei Zhang🇨🇳 · Limin Yuan🇨🇳

    The cross sections of $e^{+}{e}^{-}\to \omega {\chi }_{cJ(J=0,1,2)}$ have been measured by BESIII. We try to search for vector charmonium(-like) states $Y(4220)$, $Y(4360)$, $\psi (4415)$ and $Y(4660)$ in the $e^{+}{e}^{-}\to \omega {\chi }_{cJ(J=0,1,2)}$ line shapes. The $\omega {\chi }_{c0}$ mainly comes from $Y(4220)$, $\omega {\chi }_{c1}$ mainly comes from $Y(4660)$ and $\omega {\chi }_{c2}$ mainly comes from $\psi (4415)$, maybe partly comes from $Y(4360)$ or $Y(4660)$. For the charmonium(-like) states that are not significant in the $e^{+}{e}^{-}\to \omega {\chi }_{cJ(J=0,1,2)}$ line shape, we also give the $90\%$ confidence level upper limits on the electron partial width multiplied by branching fraction. These results are helpful to study the nature of charmonium(-like) states in this energy region.

    hep-phActa Phys.Polon.B(2018)·0 citations
14. 14*

    Reweighting a parton shower using a neural network: the final-state case

    Enrico Bothmann🇬🇧 · Luigi Del Debbio🇬🇧

    The use of QCD calculations that include the resummation of soft-collinear logarithms via parton-shower algorithms is currently not possible in PDF fits due to the high computational cost of evaluating observables for each variation of the PDFs. Unfortunately the interpolation methods that are otherwise applied to overcome this issue are not readily generalised to all-order parton-shower contributions. Instead, we propose an approximation based on training a neural network to predict the effect of varying the input parameters of a parton shower on the cross section in a given observable bin, interpolating between the variations of a training data set. This first publication focuses on providing a proof-of-principle for the method, by varying the shower dependence on ${\alpha }_{\text{S}}$ for both a simplified shower model and a complete shower implementation for three different observables, the leading emission scale, the number of emissions and the Thrust event shape. The extension to the PDF dependence of the initial-state shower evolution that is needed for the application to PDF fits is left to a forthcoming publication.

    hep-phJHEP(2019)·52 citations
15. 15*

    Fermionic dark matter in leptoquark portal

    Rusa Mandal🇮🇳

    We investigate a beyond standard model (SM) portal scenario for dark matter (DM) particle with leptoquark being the mediator field. Leptoquark, a colored particle having both baryon and lepton number, allows the DM to interact with the SM fields via renormalizable interaction. By focusing on a vector leptoquark portal with Majorana fermion DM candidate, we find the only unknown coupling in the model is sensitive to all three main features of a DM model namely, relic density, direct detection as well as indirect detection, while being consistent with collider data. We explore the parameter space of the portal with minimum of its field content and find that AMS-02 data for antiproton flux imposes stringent bound till date and excludes the DM mass up to 400GeV. The LUX 2016 data for DM-neutron scattering cross section allows the region compatible with relic density, however the future sensitivity of LUX-ZEPLIN experiment can probe the model up to its perturbative limit.

    hep-phEPJC(2018)·31 citations
16. 16*

    $e^{+}{e}^{-}$ angularity distributions at NNLL${}^{\prime }$ accuracy

    Guido Bell🇩🇪 · Andrew Hornig🇺🇸 · Christopher Lee🇺🇸 · Jim Talbert🇩🇪

    We present predictions for the $e^{+}{e}^{-}$ event shape angularities at NNLL${}^{\prime }$ resummed and $\mathcal{O}({\alpha }_s^2)$ matched accuracy and compare them to LEP data at center-of-mass energies $Q=91.2$ GeV and $Q=197$ GeV. We perform the resummation within the framework of Soft-Collinear Effective Theory, and make use of recent results for the two-loop angularity soft function. We determine the remaining NNLL${}^{\prime }$ and $\mathcal{O}({\alpha }_s^2)$ ingredients from a fit to the EVENT2 generator, and implement a shape function with a renormalon-free gap parameter to model non-perturbative effects. Using values of the strong coupling ${\alpha }_s(m_Z)$ and the universal non-perturbative shift parameter ${\Omega }_1$ that are consistent with those obtained in previous fits to the thrust and $C$-parameter distributions, we find excellent agreement between our predictions and the LEP data for all angularities with $a\in [-1,0.5]$. This provides a robust test of the predictions of QCD, factorization, and the universal scaling of the non-perturbative shift across different angularities. Promisingly, our results indicate that current degeneracies in the $\{{\alpha }_s(m_Z),{\Omega }_1\}$ parameter space could be be alleviated upon fitting these parameters to experimental data for the angularity distributions.

    hep-phhep-exnucl-thJHEP(2019)·69 citations
17. 17*

    Scaling of P-wave excitation energies in heavy-quark systems

    Marek Karliner🇮🇱 · Jonathan L. Rosner🇺🇸

    A simple regularity in anticipating P-wave excitation energies of states with heavy quarks is noted. It can apply to systems such as the negative-parity ${\Sigma }_c$, ${\Sigma }_b$, and ${\Omega }_c$, $\bar{Q}Q$ quarkonia, and the bottom-charmed meson $B_c$. When one subtracts a term accounting for phenomenological energies of heavy quarks binding with one another in S-waves, the residual excitation energies display an approximately linear behavior in the reduced mass of constituents, all the way from the $\Lambda$ to the ${\rm Y}$.

    hep-phhep-exPRD(2018)·22 citations
18. 18*

    Polarization Effects in Standard Model Parton Distributions at Very High Energies

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

    We update the earlier work of Refs. arXiv:1703.08562 and arXiv:1712.07147 on parton distribution functions in the full Standard Model to include gauge boson polarization, non-zero input electroweak boson PDFs and next-to-leading-order resummation of large logarithms.

    hep-phhep-exJHEP(2019)·32 citations
19. 19*

    Flavor diagonal tensor charges of the nucleon from 2+1+1 flavor lattice QCD

    Rajan Gupta🇺🇸 · Boram Yoon🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Vincenzo Cirigliano🇺🇸 · Yong-Chull Jang🇺🇸 · Huey-Wen Lin🇺🇸

    We present state-of-the-art results for the matrix elements of flavor diagonal tensor operators within the nucleon state. The calculation of the dominant connected contribution is done using eleven ensembles of gauge configurations generated by the MILC Collaboration using the highly improved staggered quark (HISQ) action with 2+1+1 dynamical flavors. The calculation of the disconnected contributions is done using seven (six) ensembles for the strange (light) quarks. These high-statistics simulations allowed us to address various systematic uncertainties. A simultaneous fit in the lattice spacing and the light-quark mass is used to extract the tensor charges in the continuum limit and at $M_{\pi }=135$ MeV. Results for the proton in the $\overline{MS}$ scheme at 2~GeV are: $g_T^u=0.784(28)(10)$, $g_T^d=-0.204(11)(10)$ and $g_T^s=-0.0027(16)$. Implications of these results for constraining the quark electric dipole moments and their contributions to the neutron electric dipole moment are discussed.

    ↳ hep-lathep-phPRD(2018)·153 citations
20. 20*

    Diffusive Nambu-Goldstone modes in quantum time-crystals

    Tomoya Hayata🇯🇵 · Yoshimasa Hidaka🇯🇵

    We study the Nambu-Goldstone (NG) modes associated with spontaneous breaking of the continuous time-translation symmetry. To discuss a quantum time-crystal with the spontaneously-broken continuous time-translation symmetry, we introduce the van der Pol type nonlinear-friction to open quantum systems. By considering small fluctuations around a time-periodic mean-field solution, we show that a gapless collective mode necessarily appears; this is nothing but the NG mode associated with a time crystal. We show that its dispersion relation becomes $\omega =-iC{\mathbf{p}}^2$. We also show that noncommutative breaking of the time-translation and U(1) symmetries results in mixing of the NG modes, and the (typically) propagating NG mode appears, whose dispersion relation becomes $\omega =(\pm C_1-i{C}_2){\mathbf{p}}^2$.

    ↳ hep-thcond-mat.mes-hallcond-mat.quant-gashep-ph19 citations
21. 21*

    Dynamical quantum phase transitions in $U(1)$ quantum link models

    Yi-Ping Huang🇨🇳 · Debasish Banerjee🇩🇪 · Markus Heyl🇩🇪

    Quantum link models are extensions of Wilson-type lattice gauge theories which realize exact gauge invariance with finite-dimensional Hilbert spaces. Quantum link models not only reproduce the standard features of Wilson's lattice gauge theories, but also host new phenomena such as crystalline confined phases. We study the non-equilibrium quench dynamics for two representative cases, $U(1)$ quantum link models in (1+1)d and (2+1)d, through the lens of dynamical quantum phase transitions. Finally, we discuss the connection to the high-energy perspective and the experimental feasibility to observe the discussed phenomena in recent quantum simulator settings such as trapped ions, ultra-cold atoms, and Rydberg atoms.

    ↳ cond-mat.str-elhep-lathep-phhep-thPRL(2019)·73 citations
22. 22*

    New infra-red enhancements in 4-derivative gravity

    Alberto Salvio🇨🇭 · Alessandro Strumia🇮🇹 · Hardi Veermae🇪🇪

    4-derivative gravity provides a renormalizable theory of quantum gravity at the price of introducing a physical ghost, which could admit a sensible positive-energy quantization. To understand its physics, we compute ghost-mediated scatterings among matter particles at tree-level, finding a new power-like infra-red enhancement typical of 4-derivative theories, that we dub '$ghostrahlung$'. Super-Planckian scatterings get downgraded to Planckian by radiating hard gravitons and ghosts, which are weakly coupled and carry away the energy.

    ↳ hep-thgr-qchep-phEPJC(2018)·33 citations
23. 23*

    Dynamical topological transitions in the massive Schwinger model with a {\theta}-term

    T. V. Zache🇩🇪 · N. Mueller🇺🇸 · J. T. Schneider🇩🇪 · F. Jendrzejewski🇩🇪 · J. Berges🇩🇪 · P. Hauke🇩🇪

    Aiming at a better understanding of anomalous and topological effects in gauge theories out-of-equilibrium, we study the real-time dynamics of a prototype model for CP-violation, the massive Schwinger model with a $\theta$-term. We identify dynamical quantum phase transitions between different topological sectors that appear after sufficiently strong quenches of the $\theta$-parameter. Moreover, we establish a general dynamical topological order parameter, which can be accessed through fermion two-point correlators and, importantly, which can be applied for interacting theories. Enabled by this result, we show that the topological transitions persist beyond the weak-coupling regime. Finally, these effects can be observed with table-top experiments based on existing cold-atom, superconducting-qubit, and trapped-ion technology. Our work, thus, presents a significant step towards quantum simulating topological and anomalous real-time phenomena relevant to nuclear and high-energy physics.

    ↳ quant-phcond-mat.quant-gascond-mat.str-elhep-ph+1PRL(2019)·121 citations
24. 24*

    Tensor Bounds on the Hidden Universe

    Adrian del Rio🇪🇸 · Ruth Durrer🇨🇭 · Subodh P. Patil🇩🇰

    During single clock inflation, hidden fields (i.e. fields coupled to the inflaton only gravitationally) in their adiabatic vacua can ordinarily only affect observables through virtual effects. After renormalizing background quantities (fixed by observations at some pivot scale), all that remains are logarithmic runnings in correlation functions that are both Planck and slow roll suppressed. In this paper we show how a large number of hidden fields can partially compensate this suppression and generate a potentially observable running in the tensor two point function, consistently inferable courtesy of a large $N$ resummation. We detour to address certain subtleties regarding loop corrections during inflation, extending the analysis of [1]. Our main result is that one can extract bounds on the hidden field content of the universe from bounds on violations of the consistency relation between the tensor spectral index and the tensor to scalar ratio, were primordial tensors ever detected. Such bounds are more competitive than the naive bound inferred from requiring inflation to occur below the strong coupling scale of gravity if deviations from the consistency relation can be bounded to within the sub-percent level. We discuss how one can meaningfully constrain the parameter space of various phenomenological scenarios and constructions that address naturalness with a large number of species (such as `N-naturalness') with CMB observations up to cosmic variance limits, and possibly future 21cm and gravitational wave observations.

    ↳ gr-qcastro-ph.COhep-phhep-thJHEP(2018)·31 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.