Mon·Aug 21, 2017Monday·August 21, 2017

1. 01*

   Quantifying finite-momentum effects in meson quasi-PDFs

   T. J. Hobbs🇺🇸

   The recently proposed large momentum effective theory (LaMET) of Ji has led to a burst of activity among lattice practitioners to perform and control the first pioneering calculations of the quasi-PDFs of the nucleon. These calculations represent approximations to the standard PDFs defined as correlation functions of fields with lightlike separation, being instead correlations along a longitudinal direction of the operator ${\gamma }^z$; as such, they differ from standard PDFs by power-suppressed $1/p_z^2$ corrections, becoming exact in the limit $p_z\to \infty$. Investigating the systematics of this behavior thus becomes crucial to understanding the validity of LaMET calculations. While this has been done using models for the nucleon, an analogous dedicated study has not been carried out for the $\pi$ and $\rho$ quark distribution functions. Using a constituent quark model, a systematic calculation is performed to estimate the size and $x$ dependence of the finite-$p_z$ effects in these quasi-PDFs, finding them to be potentially tamer for lighter mesons than for the collinear quasi-PDFs of the nucleon.

   hep-phhep-latnucl-thPRD(2018)·38 citations
2. 02*

   Decoherence, matter effect, neutrino hierarchy signature in long baseline experiments

   João A. B. Coelho🇫🇷 · W. Anthony Mann🇺🇸

   Environmental decoherence of oscillating neutrinos of strength $\Gamma =(2.3\pm 1.1)\times 10^{-23}$ GeV can explain how maximal ${\theta }_{23}$ mixing observed at 295 km by T2K appears to be non-maximal at longer baselines. As shown recently by R. Oliveira, the MSW matter effect for neutrinos is altered by decoherence: In normal (inverted) mass hierarchy, a resonant enhancement of ${\nu }_{\mu }({\bar{\nu }}_{\mu })\to {\nu }_e({\bar{\nu }}_e)$ occurs for $6<E_{\nu }<20$ GeV. Thus decoherence at the rated strength may be detectable as an excess of charged-current ${\nu }_e$ events in the full ${\nu }_{\mu }$ exposures of MINOS+ and OPERA.

   hep-phhep-exPRD(2017)·43 citations
3. 03*

   Measuring properties of a Heavy Higgs boson in the $H\to ZZ\to 4\ell$ decay

   Jung Chang🇰🇷 · Kingman Cheung🇹🇼 · Jae Sik Lee🇰🇷 · Chih-Ting Lu🇹🇼 · Jubin Park🇰🇷

   In many extensions of the standard model, there exist a few extra Higgs bosons. Suppose a heavy neutral Higgs boson H is discovered at the LHC, one could then investigate CP and CPT~ properties of its couplings to a pair of $Z$ bosons through $H\to ZZ\to 4\ell$. We use the helicity-amplitude method to write down the most general form for the angular distributions of the four final-state leptons, which can cover the case of CP-even, -odd, and -mixed state for the Higgs boson. We figure out there are 9 types of angular observables and all the $H$ couplings to $Z$ bosons can be fully determined by exploiting them. A Higgs-boson mass of 260 GeV below the $t\bar{t}$ threshold is illustrated with full details. With a total of $10^3$ events of $H\to ZZ\to 4\ell$, one can determine the couplings up to 12-20\% uncertainties.

   hep-phhep-exJHEP(2017)·2 citations
4. 04*

   Impact of LHC data on muon $g-2$ solutions in vector-like extension of the Constrained MSSM

   Arghya Choudhury🇬🇧 · Soumya Rao🇵🇱 · Leszek Roszkowski🇵🇱

   The long-standing discrepancy between the experimental determination by the Muon $g-2$ Collaboration at Brookhaven and the Standard Model predictions for the anomalous magnetic moment of the muon cannot be explained within simple unified framework like the Constrained Minimal Supersymmetric Standard Model, but it can within its extension with vector-like fermions. In this paper we consider a model with an additional vector-like $5+\bar{5}$ pair of $SU(5)$. Within this model we first identify its parameter space that is consistent with the current discrepancy and show that this implies the lighter chargino mass in the range of $700-1200$ GeV. We examine how it is affected by constraints from electroweak sparticle search at the LHC based on 13 TeV search with 36.1 ${fb}^{-1}$ integrated luminosity. We show that null trilepton signal searches coming from chargino-neutralino pair production significantly constrains the allowed parameter space except when the chargino-neutralino mass difference is relatively small, below about 10 GeV. Next we consider the expected impact of the New Muon $g-2$ experiment at Fermilab with its projected sensitivity reach of $7\sigma$ and, assuming it confirms the current discrepancy, show that the remaining parameter space of the considered model will be in strong tension with the current LHC limits.

   hep-phhep-exPRD(2017)·19 citations
5. 05*

   Threshold resummation of the rapidity distribution for Higgs production at NNLO+NNLL

   Pulak Banerjee🇮🇳 · Goutam Das🇮🇳 · Prasanna K. Dhani🇮🇳 · V. Ravindran🇮🇳

   We present a formalism that resums threshold-enhanced logarithms to all orders in perturbative QCD for the rapidity distribution of any colorless particle produced in hadron colliders. We achieve this by exploiting the factorization properties and K+G equations satisfied by the soft and virtual parts of the cross section. We compute for the first time compact and most general expressions in two-dimensional Mellin space for the resummed coefficients. Using various state-of-the-art multiloop and multileg results, we demonstrate the numerical impact of our resummed results up to next-to-next-to-leading order for the rapidity distribution of the Higgs boson at the LHC. We find that inclusion of these threshold logs through resummation improves the reliability of perturbative predictions.

   hep-phhep-exPRD(2018)·37 citations
6. 06*

   Higgs mass prediction in the MSSM at three-loop level in a pure $\overline{\text{DR}}$ context

   Robert V. Harlander🇩🇪 · Jonas Klappert🇩🇪 · Alexander Voigt🇩🇪

   The impact of the three-loop effects of order ${\alpha }_t{\alpha }_s^2$ on the mass of the light CP-even Higgs boson in the MSSM is studied in a pure $\overline{\text{DR}}$ context. For this purpose, we implement the results of Kant et al. into the C++ module Himalaya and link it to FlexibleSUSY, a Mathematica and C++ package to create spectrum generators for BSM models. The three-loop result is compared to the fixed-order two-loop calculations of the original FlexibleSUSY and of FeynHiggs, as well as to the result based on an EFT approach. Aside from the expected reduction of the renormalization scale dependence with respect to the lower order results, we find that the three-loop contributions significantly reduce the difference from the EFT prediction in the TeV-region of the SUSY scale $M_S$. Himalaya can be linked also to other two-loop $\overline{\text{DR}}$ codes, thus allowing for the elevation of these codes to the three-loop level.

   hep-phEPJC(2017)·54 citations
7. 07*

   Computation of hybrid static potentials in SU(3) lattice gauge theory

   Christian Reisinger🇩🇪 · Stefano Capitani🇩🇪 · Owe Philipsen🇩🇪 · Marc Wagner🇩🇪

   We compute hybrid static potentials in SU(3) lattice gauge theory. We present a method to generate a large set of suitable creation operators with defined quantum numbers from elementary building blocks. We show preliminary results for several channels and discuss, which structures of the gluonic flux tube seem to be realized by the ground states in these channels.

   ↳ hep-lathep-phEPJ Web Conf.(2018)·16 citations
8. 08*

   Enhancement of elliptic flow can signal a first order phase transition in high energy heavy ion collisions

   Yasushi Nara🇯🇵 · Harri Niemi🇩🇪 · Akira Ohnishi🇯🇵 · Jan Steinheimer🇩🇪 · Xiaofeng Luo🇨🇳 · Horst Stoecker🇩🇪

   The beam energy dependence of the elliptic flow,$v_2$, is studied in mid-central Au+Au collisions in the energy range of $3\le \sqrt{s_{NN}}\le 30$ GeV within the microscopic transport model JAM. The results of three different modes of JAM are compared; cascade-,hadronic mean field-, and a new mode with modified equations of state, with a first order phase transition (1.O.P.T.) and with a crossover transition. The standard hadronic mean field suppresses $v_2$, while the inclusion of the effects of a 1.O.P.T. (and also of a crossover transition) does enhance $v_2$ at $\sqrt{s_{NN}}<30$ GeV. The enhancement or suppression of the scaled energy flow, dubbed "elliptic flow"is understood as being due to out of plane- flow, i.e. $v_2<0$, dubbed out of plane - "squeeze-out", which occurs predominantly in the early, compression stage. Subsequently, the in-plane flow dominates, in the expansion stage, $v_2>0$. The directed flow, dubbed "bounce- off", is an independent measure of the pressure, which quickly builds up the transverse momentum transfer in the reaction plane. When the spectator matter leaves the participant fireball region, where the highest compression occurs, a hard expansion leads to larger $v_2$. A combined analysis of the three transverse flow coefficients, radial $v_0$-, directed $v_1$- and elliptic $v_2$- flow, in the beam energy range of $3\le \sqrt{s_{NN}}\le 10$ GeV, distinguishes the different compression and expansion scenarios: a characteristic dependence on the early stage equation of state is observed. The enhancement of both the elliptic and the transverse radial flow and the simultaneous collapse of the directed flow of nucleons offers a clear signature if 1.O.P.T. is realized at the highest baryon densities created in high energy heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exEPJA(2018)·29 citations
9. 09*

   Using the Full Power of the Cosmic Microwave Background to Probe Axion Dark Matter

   Renée Hlozek🇨🇦 · David J. E. Marsh🇬🇧 · Daniel Grin🇺🇸

   The cosmic microwave background (CMB) places strong constraints on models of dark matter (DM) that deviate from standard cold DM (CDM), and on initial conditions beyond the scalar adiabatic mode. Here, the full \textit{Planck} data set (including temperature, $E$-mode polarisation, and lensing deflection) is used to test the possibility that some fraction of the DM is composed of ultralight axions (ULAs). This represents the first use of CMB lensing to test the ULA model. We find no evidence for a ULA component in the mass range $10^{-33}\le m_a\le 10^{-24}\text{ eV}$. We put percent-level constraints on the ULA contribution to the DM, improving by up to a factor of two compared to the case with temperature anisotropies alone. Axion DM also provides a low-energy window onto the high-energy physics of inflation through the interplay between the vacuum misalignment production of axions and isocurvature perturbations. We perform the first systematic investigation into the parameter space of ULA isocurvature, using an accurate isocurvature transfer function at all $m_a$ values. We precisely identify a "window of co-existence" for $10^{-25}\text{ eV}\le m_a\le 10^{-24}\text{ eV}$ where the data allow, simultaneously, a $\sim 10\%$ contribution of ULAs to the DM, and $\sim 1\%$ contributions of isocurvature and tensors to the CMB power. ULAs in this window (and \textit{all} lighter ULAs) are shown to be consistent with a large inflationary Hubble parameter, $H_I\sim 10^{14}\text{ GeV}$. The window of co-existence will be fully probed by proposed CMB-S4 observations with increased accuracy in the high-$\ell$ lensing power and low-$\ell$ $E$ and $B$-mode polarisation. If ULAs in the window exist, this could allow for two independent measurements of $H_I$ in the CMB using the axion DM content and isocurvature, and the tensor contribution to $B$-modes.

   ↳ astro-ph.COhep-phMNRAS(2018)·222 citations
10. 10*

    Strongly-coupled anisotropic gauge theories and holography

    Dimitrios Giataganas🇹🇼 · Umut Gürsoy🇳🇱 · Juan F. Pedraza🇳🇱

    We initiate a non-perturbative study of anisotropic, non-conformal and confining gauge theories that are holographically realized in gravity by generic Einstein-Axion-Dilaton systems. In the vacuum our solutions describe RG flows from a conformal field theory in the UV to generic scaling solutions in the IR with generic hyperscaling violation and dynamical exponents $\theta$ and $z$. We formulate a generalization of the holographic c-theorem to the anisotropic case. At finite temperature, we discover that the anisotropic deformation reduces the confinement-deconfinement phase transition temperature suggesting a possible alternative explanation of inverse magnetic catalysis solely based on anisotropy. We also study transport and diffusion properties in anisotropic theories and observe in particular that the butterfly velocity that characterizes both diffusion and growth of chaos transverse to the anisotropic direction, saturates a constant value in the IR which can exceed the bound given by the conformal value.

    ↳ hep-thhep-phnucl-thPRL(2018)·143 citations
11. 11*

    Massive Spin-2 Scattering and Asymptotic Superluminality

    Kurt Hinterbichler🇺🇸 · Austin Joyce🇺🇸 · Rachel A. Rosen🇺🇸

    We place model-independent constraints on theories of massive spin-2 particles by considering the positivity of the phase shift in eikonal scattering. The phase shift is an asymptotic $S$-matrix observable, related to the time delay/advance experienced by a particle during scattering. Demanding the absence of a time advance leads to constraints on the cubic vertices present in the theory. We find that, in theories with massive spin-2 particles, requiring no time advance means that either: (i) the cubic vertices must appear as a particular linear combination of the Einstein-Hilbert cubic vertex and an $h_{\mu \nu }^3$ potential term or (ii) new degrees of freedom or strong coupling must enter at parametrically the mass of the massive spin-2 field. These conclusions have implications for a variety of situations. Applied to theories of large-$N$ QCD, this indicates that any spectrum with an isolated massive spin-2 at the bottom must have these particular cubic self-couplings. Applied to de Rham-Gabadadze-Tolley massive gravity, the constraint is in accord with and generalizes previous results obtained from a shockwave calculation: of the two free dimensionless parameters in the theory there is a one parameter line consistent with a subluminal phase shift.

    ↳ hep-thgr-qchep-phJHEP(2018)·69 citations
12. 12*

    Asymptotic Dynamics in Perturbative Quantum Gravity and BMS Supertranslations

    Sangmin Choi🇺🇸 · Uri Kol🇺🇸 · Ratindranath Akhoury🇺🇸

    Recently it has been shown that infrared divergences in the conventional S-matrix elements of gauge and gravitational theories arise from a violation of the conservation laws associated with large gauge symmetries. These infrared divergences can be cured by using the Faddeev-Kulish (FK) asymptotic states as the basis for S-matrix elements. Motivated by this connection, we study the action of BMS supertranslations on the FK asymptotic states of perturbative quantum gravity. We compute the BMS charge of the FK states and show that it characterizes the superselection sector to which the state belongs. Conservation of the BMS charge then implies that there is no transition between different superselection sectors, hence showing that the FK graviton clouds implement the necessary vacuum transition induced by the scattering process.

    ↳ hep-thgr-qchep-phJHEP(2018)·61 citations
13. 13*

    Causality and existence of solutions of relativistic viscous fluid dynamics with gravity

    Fabio S. Bemfica (Rio Grande do Norte U.)🇧🇷 · Marcelo M. Disconzi (Vanderbilt U.)🇺🇸 · Jorge Noronha (Sao Paulo U.)🇧🇷

    A new approach is described to help improve the foundations of relativistic viscous fluid dynamics and its coupling to general relativity. Focusing on neutral conformal fluids constructed solely in terms of hydrodynamic variables, we derive the most general viscous energy-momentum tensor yielding equations of motion of second order in the derivatives, which is shown to provide a novel type of generalization of the relativistic Navier-Stokes equations for which causality holds. We show how this energy-momentum tensor may be derived from conformal kinetic theory. We rigorously prove existence, uniqueness, and causality of solutions of this theory (in the full nonlinear regime) both in a Minkowski background and also when the fluid is dynamically coupled to Einstein's equations. Linearized disturbances around equilibrium in Minkowski spacetime are stable in this causal theory. A numerical study reveals the presence of an out-of-equilibrium hydrodynamic attractor for a rapidly expanding fluid. Further properties are also studied and a brief discussion of how this approach can be generalized to non-conformal fluids is presented.

    ↳ gr-qchep-phhep-thmath-ph+2PRD(2018)·289 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.