Fri·Dec 8, 2017Friday·December 8, 2017

1. 01*

   Lepton Flavor Violation Induced by Dark Matter

   Giorgio Arcadi🇩🇪 · C. P. Ferreira🇧🇷 · Florian Goertz🇩🇪 · M. M. Guzzo🇧🇷 · Farinaldo S. Queiroz🇧🇷 · A.C.O. Santos🇧🇷

   Guided by gauge principles we discuss a predictive and falsifiable UV complete model where the Dirac fermion that accounts for the cold dark matter abundance in our universe induces the lepton flavor violation (LFV) decays $\mu \to e\gamma$ and $\mu \to eee$ as well as $\mu -e$ conversion. We explore the interplay between direct dark matter detection, relic density, collider probes and lepton flavor violation to conclusively show that one may have a viable dark matter candidate yielding flavor violation signatures expected to be fully probed in the upcoming of experiments. Interestingly, keeping the dark matter mass not far from the TeV, our model has an approximate prediction for the maximum LFV signal one could have while reproducing the correct dark matter relic density.

   hep-phPRD(2018)·26 citations
2. 02*

   Explain DAMPE Results by Dark Matter With Hierarchical Lepton-Specific Yukawa Interactions

   Guo-Li Liu🇨🇳 · Fei Wang🇨🇳 · Wenyu Wang🇨🇳 · Jin Min Yang🇨🇳

   We propose to interpret the DAMPE electron excess at 1.5 TeV through scalar or Dirac fermion dark matter (DM) annihilation with doubly charged scalar mediators that have lepton-specific Yukawa couplings. Hierarchy of such lepton-specific Yukawa couplings is generated through the Froggatt-Nielsen mechanism, so that the dark matter annihilation products can be dominantly electrons. Stringent constraints from LEP2 on intermediate vector boson production can be evaded in our scenarios. In the case of scalar DM, we discuss one scenario with DM annihilating directly to leptons and the other scenario with DM annihilating to scalar mediators followed by their decays. We also discuss the Breit-Wigner resonant enhancement and the Sommerfeld enhancement in case that the s-wave annihilation process is small or helicity suppressed. With both types of enhancement, constraints on the parameters can be relaxed and new ways for model building will be open in explaining the DAMPE results.

   hep-phastro-ph.COCPC(2018)·22 citations
3. 03*

   Studies on the anomalous magnetic and electric dipole moments of the tau-neutrino in $pp$ collisions at the LHC

   A. Gutierrez-Rodriguez🇲🇽 · M. Koksal🇹🇷 · A. A. Billur🇹🇷 · M. A. Hernandez-Ruiz🇲🇽

   In this paper the production cross section $pp\to (\gamma ,Z)\to {\nu }_{\tau }{\bar{\nu }}_{\tau }\gamma +X$ in $pp$ collisions at $\sqrt{s}=8,13,14,33TeV$ is presented. Furthermore, we estimate bounds at the $95\%C.L.$ on the dipole moments of the tau-neutrino using integrated luminosity of $\mathcal{L}=20,50,100,200,500,1000,3000f{b}^{-1}$ collected with the ATLAS detector at the LHC and we consider systematic uncertainties of ${\delta }_{sys}=0,5,10\%$. It is shown that the process under consideration is a good prospect for probing the dipole moments of the tau-neutrino at the LHC.

   hep-phEPJA(2019)·11 citations
4. 04*

   Chiral asymmetry during the EWPT from CP-violating scattering off bubble walls

   Alejandro Ayala🇲🇽 · L. A. Hernández🇲🇽 · Jordi Salinas🇲🇽

   We compute a net electric current during a first order EWPT arising from the asymmetric propagation of fermion chiral modes due to a CP-violating interaction with the Higgs. The interaction is quantified in terms of a CP-violating phase in the bubble wall that separate both false and true vacuum phases. We comment on the possibility of this current to generate a seed magnetic field and its implications for primordial magne- togenesis in the early Universe.

   hep-phEPJ Web Conf.(2018)·0 citations
5. 05*

   Using the Linear Sigma Model with quarks to describe the QCD phase diagram and to locate the critical end point

   Alejandro Ayala🇲🇽 · Jorge David Castaño-Yepes🇲🇽 · José Antonio Flores🇲🇽 · Saúl Hernández🇲🇽 · Luis Hernández🇲🇽

   We study the QCD phase diagram using the linear sigma model coupled to quarks. We compute the effective potential at finite temperature and quark chemical potential up to ring diagrams contribution. We show that, provided the values for the pseudo-critical temperature $T_c=155$ MeV and critical baryon chemical potential ${\mu }_{Bc}\simeq 1$ GeV, together with the vacuum sigma and pion masses. The model couplings can be fixed and that these in turn help to locate the region where the crossover transition line becomes first order.

   hep-phEPJ Web Conf.(2018)·1 citation
6. 06*

   Unruh effect and Schwinger pair creation under extreme acceleration by ultraintense lasers

   Chul Min Kim (IBS and GIST)🇰🇷 · Sang Pyo Kim (Kunsan Nat'l Univ.)🇰🇷

   A detector undergoing a huge acceleration measures a thermal distribution with the Unruh temperature out of the Minkowski vacuum. Though such huge accelerations occur naturally in astrophysics and gravity, one may design untraintense laser facility to detect the Unruh effect and simulate laboratory astrophysics. We derive the QED vacuum polarization and the vacuum persistence amplitude as well as the Schwinger pair creation in an accelerating frame when a constant electric field exists in the Minkowski spacetime. We advance a thermal interpretation of Schwinger pair creation in the Rindler space.

   hep-phgr-qc4 citations
7. 07*

   Can we discover a light singlet-like NMSSM Higgs boson at the LHC?

   C. Beskidt (1)🇩🇪 · W. de Boer (1)🇩🇪 · D. I. Kazakov (1,2) ((1) Karlsruhe Institute of Technology, Germany, (2) Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia)🇷🇺

   In the next-to minimal supersymmetric standard model (NMSSM) one additional singlet-like Higgs boson with small couplings to standard model (SM) particles is introduced. Although the mass can be well below the discovered 125 GeV Higgs boson mass its small couplings may make a discovery at the LHC difficult. We use a novel scanning technique to efficiently scan the whole parameter space and determine the range of cross sections and branching ratios for the light singlet-like Higgs boson below 125 GeV. This allows to determine the perspectives for the future discovery potential at the LHC. Specific LHC benchmark points are selected representing the salient NMSSM features.

   hep-phPLB(2018)·24 citations
8. 08*

   Recent $\mathbf{B}$ Physics Anomalies - a First Hint for Compositeness?

   Adrián Carmona🇨🇭 · Florian Goertz🇩🇪

   We scrutinize the recently further strengthened hints for new physics in semileptonic $B$-meson decays, focusing on the 'clean' ratios of branching fractions $R_K$ and $R_{K^{\ast }}$ and examining to which pattern of new effects they point to. We explore in particular the hardly considered, yet fully viable, option of new physics in the right-handed electron sector and demonstrate how a recently proposed framework of leptons in composite Higgs setups naturally solves both the $R_K$ and $R_{K^{\ast }}$ anomalies via a peculiar structure of new physics effects, predicted by minimality of the model and the scale of neutrino masses. Finally, we also take into account further observables, such as $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$, $\Delta M_{B_s}$, and angular observables in $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ decays, to arrive at a comprehensive picture of the model concerning (semileptonic) $B$ decays. We conclude that -- since it is in good agreement with the experimental situation in flavor physics and also allows to avoid ultra-light top partners -- the model furnishes a very promising scenarios of Higgs compositeness in the light of LHC data.

   hep-phEPJC(2018)·34 citations
9. 09*

   Two-Loop Master Integrals for the Planar QCD Massive Corrections to Di-photon and Di-jet Hadro-production

   Matteo Becchetti🇮🇹 · Roberto Bonciani🇮🇹

   We present the analytic calculation of the Master Integrals necessary to compute the planar massive QCD corrections to Di-photon (and Di-jet) production at hadron colliders. The masters are evaluated by means of the differential equations method and expressed in terms of multiple polylogarithms and one- or two-fold integrals of polylogarithms and irrational functions, up to transcendentality four.

   hep-phhep-thJHEP(2018)·65 citations
10. 10*

    Revisiting the pseudoscalar meson and glueball mixing and key issues in the search for pseudscalar glueball state

    Wen Qin🇨🇳 · Qiang Zhao🇨🇳 · Xian-Hui Zhong🇨🇳

    We revisit the mixing mechanism for pesudscalar mesons and glueball which is introduced by the axial vector anomaly. We demonstrate that the physical mass of the pseudoscalar glueball does not favor to be lower than 1.8 GeV if all the parameters are reasonably constrained. This conclusion, on the one hand, can accommodate the pseudoscalar glueball mass calculated by Lattice QCD, and on the other hand, is consistent with the high-statistics analyses at BESIII that all the available measurements do not support the presence of two closely overlapping pseudoscalar states in any exclusive channel. Such a result is in agreement with the recent claim that the slightly shifted peak positions for two possible states $\eta (1405)$ and $\eta (1475)$ observed in different channels are actually originated from one single state with the triangle singularity interferences. By resolving this long-standing paradox, one should pay more attention to higher mass region for the purpose of searching for the pseudoscalar glueball candidate.

    hep-phhep-exnucl-exnucl-thPRD(2018)·25 citations
11. 11*

    Wounded quark emission function at the top RHIC energy

    Michał Barej🇵🇱 · Adam Bzdak🇵🇱 · Paweł Gutowski🇵🇱

    The wounded nucleon and quark emission functions are extracted for different centralities in d+Au collisions at $\sqrt{s}=200\text{GeV}$ using Monte Carlo simulations and experimental data. The shape of the emission function depends on centrality in the wounded nucleon model, whereas it is practically universal (within uncertainties) in the wounded quark model. Predictions for $d{N}_{ch}/d\eta$ distributions in p+Au and ${}^3$He+Au collisions are presented.

    hep-phhep-exnucl-exnucl-thPRC(2018)·19 citations
12. 12*

    Equilibration in finite Bose systems

    Georg Wolschin🇩🇪

    The equilibration of a finite Bose system is modelled using a gradient expansion of the collision integral that leads to a nonlinear transport equation. For constant transport coefficients, it is solved in closed form through a nonlinear transformation. Using schematic initial conditions, the exact solution and the equilibration time are derived and compared to the corresponding case for fermions. Applications to the equilibration of the gluon system created initially in relativistic heavy-ion collisions, and to cold quantum gases are envisaged.

    hep-phmath-phmath.MPPhysica A(2018)·18 citations
13. 13*

    Effect of an anisotropic escape mechanism on elliptic flow in relativistic heavy-ion collisions

    Amaresh Jaiswal🇮🇳 · Partha Pratim Bhaduri🇮🇳

    We study the effect of anisotropic escape mechanism on elliptic flow in relativistic heavy-ion collisions. We use Glauber model to generate initial conditions and ignore hydrodynamic expansion in the transverse direction. We employ Beer-Lambert law to allow for the transmittance of produced hadrons in the medium and calculate the anisotropy generated due to the suppression of particles traversing through the medium. In order to separate non-flow contribution due to surface bias effects, we ignore hydrodynamic expansion in the transverse direction and consider purely longitudinal boost-invariant expansion. We calculate the transverse momentum dependence of elliptic flow, generated from anisotropic escape mechanism due to surface bias effects, for various centralities in $\sqrt{s_{NN}}=200$ GeV Au$+$Au collisions at RHIC and $\sqrt{s_{NN}}=2.76$ TeV Pb$+$Pb collisions at LHC. We find that the surface bias effects have a sizable contribution to the total elliptic flow observed in heavy-ion collisions indicating that the viscosity of the QCD matter extracted from hydrodynamic simulations may be underestimated.

    hep-phnucl-thPRC(2018)·7 citations
14. 14*

    A Simple Testable Model of Baryon Number Violation: Baryogenesis, Dark Matter, Neutron-Antineutron Oscillation and Collider Signals

    Rouzbeh Allahverdi🇺🇸 · P. S. Bhupal Dev🇺🇸 · Bhaskar Dutta🇺🇸

    We study a simple TeV-scale model of baryon number violation which explains the observed proximity of the dark matter and baryon abundances. The model has constraints arising from both low and high-energy processes, and in particular, predicts a sizable rate for the neutron-antineutron ($n-\bar{n}$) oscillation at low energy and the monojet signal at the LHC. We find an interesting complementarity among the constraints arising from the observed baryon asymmetry, ratio of dark matter and baryon abundances, $n-\bar{n}$ oscillation lifetime and the LHC monojet signal. There are regions in the parameter space where the $n-\bar{n}$ oscillation lifetime is found to be more constraining than the LHC constraints, which illustrates the importance of the next-generation $n-\bar{n}$ oscillation experiments.

    hep-phastro-ph.COhep-exPLB(2018)·65 citations
15. 15*

    Reduction of the Parameters in MSSM

    S. Heinemeyer🇪🇸 · M. Mondragon🇲🇽 · N. Tracas🇬🇷 · G. Zoupanos🇬🇷

    In the present work we search for renormalization group invariant relations among the various massless and massive parameters of the Minimal Supersymmetric Standard Model. We find that indeed several of the previously free parameters of the model can be reduced in favor of few, the unique gauge coupling and the gaugino mass at the unification scale among them. Taking into account the various experimental constraints, including the B-physics ones, we predict the Higgs and the supersymmetric spectrum. We find that the lightest Higgs mass is in comfortable agreement with the measured value and its experimental and theoretical uncertainties, while the electroweak supersymmetric spectrum starts at 1.3 TeV and the colored at ~4 TeV. Thus the reduced MSSM is in natural agreement with all LHC measurements and searches. The supersymmetric and heavy Higgs particles will likely escape the detection at the LHC, as well as at ILC and CLIC. However, the FCC-hh will be able to fully test the predicted parameter space.

    hep-phhep-thJHEP(2018)·17 citations
16. 16*

    Single top production at linear $e^{-}{e}^{+}$ colliders

    Angel Escamilla🇲🇽 · Antonio O. Bouzas🇲🇽 · F. Larios🇲🇽

    We study single top production at linear lepton colliders with $\sqrt{s}=0.5$, 1 and 3 TeV. A preliminary analysis shows that despite the large $t\bar{t}$ background at $\sqrt{s}=0.5$ and 1 TeV it is possible to obtain a good sensitivity to the $tbW$ vertex; even more so at 3 TeV when single top becomes the dominant mode of production. Concerning the four dimension six operators involved, two of them simultaneously generate $ttZ$ couplings and their sensitivity decreases with energy. The opposite is true for the other two operators. Single top production at these machines is also useful to probe charged-current four fermion operators $e\nu bt$, some of which are related to $tbW$ operators through the equations of motion.

    hep-phPRD(2018)·10 citations
17. 17*

    Fermion Masses and Mixings and Dark Matter Constraints in a Model with Radiative Seesaw Mechanism

    Nicolás Bernal🇨🇴 · A. E. Cárcamo Hernández🇨🇱 · Ivo de Medeiros Varzielas🇵🇹 · Sergey Kovalenko🇨🇱

    We formulate a predictive model of fermion masses and mixings based on a $\Delta (27)$ family symmetry. In the quark sector the model leads to the viable mixing inspired texture where the Cabibbo angle comes from the down quark sector and the other angles come from both up and down quark sectors. In the lepton sector the model generates a predictive structure for charged leptons and, after radiative seesaw, an effective neutrino mass matrix with only one real and one complex parameter. We carry out a detailed analysis of the predictions in the lepton sector, where the model is only viable for inverted neutrino mass hierarchy, predicting a strict correlation between ${\theta }_{23}$ and ${\theta }_{13}$. We show a benchmark point that leads to the best-fit values of ${\theta }_{12}$, ${\theta }_{13}$, predicting a specific ${\sin }^2{\theta }_{23}\simeq 0.51$ (within the $3\sigma$ range), a leptonic CP-violating Dirac phase $\delta \simeq 281.6^{\circ }$ and for neutrinoless double-beta decay $m_{ee}\simeq 41.3$ meV. We turn then to an analysis of the dark matter candidates in the model, which are stabilized by an unbroken ${\mathbb{Z}}_2$ symmetry. We discuss the possibility of scalar dark matter, which can generate the observed abundance through the Higgs portal by the standard WIMP mechanism. An interesting possibility arises if the lightest heavy Majorana neutrino is the lightest ${\mathbb{Z}}_2$-odd particle. The model can produce a viable fermionic dark matter candidate, but only as a feebly interacting massive particle (FIMP), with the smallness of the coupling to the visible sector protected by a symmetry and directly related to the smallness of the light neutrino masses.

    hep-phJHEP(2018)·45 citations
18. 18*

    The Top Mass in Hadronic Collisions

    Paolo Nason🇮🇹

    I discuss theoretical issues related to the top mass measurements in hadronic collisions.

    hep-phhep-ex63 citations
19. 19*

    Non-unitary evolution of neutrinos in matter and the leptonic unitarity test

    Chee Sheng Fong🇧🇷 · Hisakazu Minakata🇪🇸 · Hiroshi Nunokawa🇧🇷

    We present a comprehensive study of the three-active plus $N$ sterile neutrino model as a framework for constraining leptonic unitarity violation induced at energy scales much lower than the electroweak scale. We formulate a perturbation theory with expansion in small unitarity violating matrix element $W$ while keeping (non-$W$ suppressed) matter effect to all orders. We show that under the same condition of sterile state masses $0.1{\text{eV}}^2\lesssim m_J^2\lesssim (1-10){\text{GeV}}^2$ as in vacuum, assuming typical accelerator based long-baseline neutrino oscillation experiment, one can derive a very simple form of the oscillation probability which consists only of zeroth-order terms with the unique exception of probability leaking term ${\mathcal{C}}_{\alpha \beta }$ of $\mathcal{O}(W^4)$. We argue, based on our explicit computation to fourth-order in $W$, that all the other terms are negligibly small after taking into account the suppression due to the mass condition for sterile states, rendering the oscillation probability {\em sterile-sector model independent}. Then, we identify a limited energy region in which this suppression is evaded and the effects of order $W^2$ corrections may be observable. Its detection would provide another way, in addition to detecting ${\mathcal{C}}_{\alpha \beta }$, to distinguish between low-scale and high-scale unitarity violation. We also solve analytically the zeroth-order system in matter with uniform density to provide a basis for numerical evaluation of non-unitary neutrino evolution.

    hep-phhep-exJHEP(2019)·50 citations
20. 20*

    Novel Gamma-Ray Signatures of PeV-Scale Dark Matter

    Carlos Blanco🇺🇸 · J. Patrick Harding🇺🇸 · Dan Hooper🇺🇸

    The gamma-ray annihilation and decay products of very heavy dark matter particles can undergo attenuation through pair production, leading to the development of electromagnetic cascades. This has a significant impact not only on the spectral shape of the gamma-ray signal, but also on the angular distribution of the observed photons. Such phenomena are particularly important in light of the new HAWC experiment, which provides unprecedented sensitivity to multi-TeV photons and thus to very heavy dark matter particles. In this study, we focus on dark matter in the 100 TeV-100 PeV mass range, and calculate the spectral and angular distribution of gamma-rays from dwarf galaxies and from nearby galaxy clusters in this class of models.

    hep-phastro-ph.COastro-ph.GAastro-ph.HEJCAP(2018)·24 citations
21. 21*

    The MSSM inflation and cosmological attractors

    M.N. Dubinin🇷🇺 · E.Yu. Petrova🇷🇺 · E.O. Pozdeeva🇷🇺 · S.Yu. Vernov (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)🇷🇺

    Inflationary scenarios motivated by the Minimal Supersymmetric Standard Model (MSSM) where five scalar fields are non-minimally coupled to gravity are considered. The potential of the model and the function of non-minimal coupling are polynomials of two Higgs doublet convolutions. We show that the use of the strong coupling approximation allows to obtain inflationary parameters in the case when a combination of the four scalar fields plays a role of inflaton. Numerical calculations show that the cosmological evolution leads to inflationary scenarios fully compatible with observational data for different values of the MSSM mixing angle $\beta$.

    hep-phastro-ph.COgr-qchep-thInt.J.Geom.Meth.Mod.Phys.(2018)·12 citations
22. 22*

    Double Charmonia Production in Exclusive $Z$ Boson Decays

    A. K. Likhoded🇷🇺 · A. V. Luchinsky🇷🇺

    This article is devoted to systematic analysis of double charmonium production in exclusive $Z$ boson decays in the framework of Nonrelativistic Quantum Chromodynamic (NRQCD) and leading twist light-cone (LC) models. Theoretical predictions for branching fractions of all considered decays are presented. According to obtained results in the case of allowed by helicity suppression rule processes the effect of internal quark motion increases the branching fraction by a factor 1.5, while for forbidden reactions LC predictions are strictly zero, while NRQCD ones are significantly smaller than for allowed.

    hep-phMod.Phys.Lett.A(2018)·22 citations
23. 23*

    Color superconductivity and charge neutrality in Yukawa theory

    Mark G. Alford🇺🇸 · Kamal Pangeni🇺🇸 · Andreas Windisch🇺🇸

    It is generally believed that when Cooper pairing occurs between two different species of fermions, their Fermi surfaces become locked together so that the resultant state remains 'neutral', with equal number densities of the two species, even when subjected to a chemical potential that couples to the difference in number densities. This belief is based on mean-field calculations in models with a zero-range interaction, where the anomalous self-energy is independent of energy and momentum. Following up on an early report of a deviation from neutrality in a Dyson-Schwinger calculation of color-flavor-locked quark matter, we investigate the neutrality of a two-species condensate using a Yukawa model which has a finite-range interaction. In a mean field calculation we obtain the full energy-momentum dependence of the self energy and find that the energy dependence leads to a population imbalance in the Cooper-paired phase when it is stressed by a species-dependent chemical potential. This gives some support to the suggestion that the color-flavor-locked phase of quark matter might not be an insulator.

    ↳ nucl-thhep-phPRL(2018)·10 citations
24. 24*

    Solitons and black hole in shift symmetric scalar-tensor gravity with cosmological constant

    Yves Brihaye🇧🇪 · Betti Hartmann🇧🇷 · Jon Urrestilla🇪🇸

    We demonstrate the existence of static, spherically symmetric globally regular, i.e. solitonic solutions of a shift-symmetric scalar-tensor gravity model with negative cosmological constant. The norm of the Noether current associated to the shift symmetry is finite in the full space-time. We also discuss the corresponding black hole solutions and demonstrate that the interplay between the scalar-tensor coupling and the cosmological constant leads to the existence of new branches of solutions. To linear order in the scalar-tensor coupling, the asymptotic space-time corresponds to an Anti-de Sitter space-time with a non-trivial scalar field on its conformal boundary. This allows the interpretation of our solutions in the context of the AdS/CFT correspondence. Finally, we demonstrate that - for physically relevant, small values of the scalar-tensor coupling - solutions with positive cosmological constant do not exist in our model.

    ↳ gr-qchep-phhep-thJHEP(2018)·14 citations
25. 25*

    The effect of the fluctuating proton size on the study of chiral magnetic effect in proton-nucleus collisions

    Dmitri Kharzeev🇺🇸 · Zhoudunming Tu🇺🇸 · Aobo Zhang🇺🇸 · Wei Li🇺🇸

    High energy proton-nucleus (pA) collisions provide an important constraint on the study of the chiral magnetic effect in QCD matter. Naively, in pA collisions one expects no correlation between the orientation of event plane as reconstructed from the azimuthal distribution of produced hadrons and the orientation of magnetic field. If this is the case, any charge-dependent hadron correlations can only result from the background. Nevertheless, in this paper we point out that in high multiplicity pA collisions a correlation between the magnetic field and the event plane can appear. This is because triggering on the high hadron multiplicity amounts to selecting Fock components of the incident proton with a large number of partons that are expected to have a transverse size much larger than the average proton size. We introduce the effect of the fluctuating proton size in the Monte Carlo Glauber model and evaluate the resulting correlation between the magnetic field and the second-order event plane in both pA and nucleus-nucleus (AA) collisions. The fluctuating proton size is found to result in a significant correlation between magnetic field and the event plane in pA collisions, even though the magnitude of the correlation is still much smaller than in AA collisions. This result opens a possibility of studying the chiral magnetic effect in small systems.

    ↳ nucl-thhep-phnucl-exPRC(2018)·9 citations
26. 26*

    Systematics of strong nuclear amplification of gluon saturation from exclusive vector meson production in high energy electron-nucleus collisions

    Heikki Mäntysaari🇺🇸 · Raju Venugopalan🇺🇸

    We show that gluon saturation gives rise to a strong modification of the scaling in both the nuclear mass number $A$ and the virtuality $Q^2$ of the vector meson production cross-section in exclusive deep-inelastic scattering off nuclei. We present qualitative analytic expressions for how the scaling exponents are modified as well as quantitative predictions that can be tested at an Electron-Ion Collider.

    ↳ nucl-thhep-phPLB(2018)·44 citations
27. 27*

    Hemisphere Mixing: a Fully Data-Driven Model of QCD Multijet Backgrounds for LHC Searches

    P. De Castro Manzano🇮🇹 · M. Dall'Osso🇮🇹 · T. Dorigo🇮🇹 · L. Finos🇮🇹 · G. Kotkowski🇮🇹 · G. Menardi🇮🇹 · B. Scarpa🇮🇹

    A novel method is proposed here to precisely model the multi-dimensional features of QCD multi-jet events in hadron collisions. The method relies on the schematization of high-pT QCD processes as 2->2 reactions made complex by sub-leading effects. The construction of libraries of hemispheres from experimental data and the definition of a suitable nearest-neighbor-based association map allow for the generation of artificial events that reproduce with surprising accuracy the kinematics of the QCD component of original data, while remaining insensitive to small signal contaminations. The method is succinctly described and its performance is tested in the case of the search for the hh->bbbb process at the LHC.

    ↳ hep-exhep-phPoS(2017)·8 citations
28. 28*

    Some aspects of global Lambda polarization in heavy-ion collisions

    Xiao-Liang Xia🇨🇳 · Hui Li🇨🇳 · Qun Wang🇨🇳

    Large orbital angular momentum can be generated in non-central heavy-ion collisions, and part of it is expected to be converted into final particle's polarization due to the spin-orbit coupling. Within the framework of A Multi-Phase Transport (AMPT) model, we studied the vorticity-induced polarization of $\Lambda$ hyperons at the midrapidity region $|\eta |<1$ in Au-Au collisions at energies $\sqrt{s_{NN}}=7.7\sim 200$ GeV. Our results show that the global polarization decreases with the collisional energies and is consistent with the recent STAR measurements. This behavior can be understood by less asymmetry of participant matter in the midrapidity region due to faster expansion of fireball at higher energies. As another evidence, we discuss how much the angular momentum is deposited in different rapidity region. The result supports our asymmetry argument.

    ↳ nucl-thhep-phPoS(2018)·5 citations
29. 29*

    Flavor Structure of the Cosmic-Ray Electron/Positron Excesses at DAMPE

    Shao-Feng Ge🇯🇵 · Hong-Jian He🇨🇳 · Yu-Chen Wang🇨🇳

    The Dark Matter Particle Explorer (DAMPE) satellite detector announced its first result for measuring the cosmic-ray electron/positron (CRE) energy spectrum up to 4.6TeV, including a tentative peak-like event excess at (1.3-1.5)TeV. In this work, we uncover a significant hidden excess in the DAMPE CRE spectrum over the energy range (0.6-1.1)TeV, which has a non-peak-like structure. We propose a new mechanism to explain this excess by a set of 1.5TeV ${\mu }^{\pm }$ events with subsequent decays into $e^{\pm }$ plus neutrinos. For explaining this new excess together with the peak excess around 1.4TeV, we demonstrate that the {\it flavor structure} of the original lepton final-state produced by dark matter (DM) annihilations (or other mechanism) should have a composition ratio $N_e:(N_{\mu }+\frac{1}{6}{N}_{\tau })=1:y$, with $y\simeq 2.6-10.8$. For lepton portal DM models, this puts important constraint on the lepton-DM-mediator couplings ${\lambda }_e:({\lambda }_{\mu }^4+\frac{1}{6}{\lambda }_{\tau }^4{)}^{\frac{1}{4}}=1:y^{\frac{1}{4}}$ with a narrow range $y^{\frac{1}{4}}\simeq 1.3-1.8$.

    ↳ astro-ph.HEhep-exhep-phPLB(2018)·36 citations
30. 30*

    Resurgence and Hydrodynamic Attractors in Gauss-Bonnet Holography

    Jorge Casalderrey-Solana🇬🇧 · Nikola I. Gushterov🇬🇧 · Ben Meiring🇬🇧

    We study the convergence of the hydrodynamic series in the gravity dual of Gauss-Bonnet gravity in five dimensions with negative cosmological constant via holography. By imposing boost invariance symmetry, we find a solution to the Gauss-Bonnet equation of motion in inverse powers of the proper time, from which we can extract high order corrections to Bjorken flow for different values of the Gauss-Bonnet parameter ${\lambda }_{GB}$. As in all other known examples the gradient expansion is, at most, an asymptotic series which can be understood through applying the techniques of Borel-Padé summation. As expected from the behaviour of the quasi-normal modes in the theory, we observe that the singularities in the Borel plane of this series show qualitative features that interpolate between the infinitely strong coupling limit of $\mathcal{N}=4$ Super Yang Mills theory and the expectation from kinetic theory. We further perform the Borel resummation to constrain the behaviour of hydrodynamic attractors beyond leading order in the hydrodynamic expansion. We find that for all values of ${\lambda }_{GB}$ considered, the convergence of different initial conditions to the resummation and its hydrodynamization occur at large and comparable values of the pressure anisotropy.

    ↳ hep-thhep-phnucl-thJHEP(2018)·65 citations
31. 31*

    Nonlinear Effective Theory of Dark Energy

    Giulia Cusin🇨🇭 · Matthew Lewandowski🇫🇷 · Filippo Vernizzi🇫🇷

    We develop an approach to parametrize cosmological perturbations beyond linear order for general dark energy and modified gravity models characterized by a single scalar degree of freedom. We derive the full nonlinear action, focusing on Horndeski theories. In the quasi-static, non-relativistic limit, there are a total of six independent relevant operators, three of which start at nonlinear order. The new nonlinear couplings modify, beyond linear order, the generalized Poisson equation relating the Newtonian potential to the matter density contrast. We derive this equation up to cubic order in perturbations and, in a companion article, we apply it to compute the one-loop matter power spectrum. Within this approach, we also discuss the Vainshtein regime around spherical sources and the relation between the Vainshtein scale and the nonlinear scale for structure formation.

    ↳ astro-ph.COgr-qchep-phJCAP(2018)·78 citations
32. 32*

    Dark Energy and Modified Gravity in the Effective Field Theory of Large-Scale Structure

    Giulia Cusin🇨🇭 · Matthew Lewandowski🇫🇷 · Filippo Vernizzi🇫🇷

    We develop an approach to compute observables beyond the linear regime of dark matter perturbations for general dark energy and modified gravity models. We do so by combining the Effective Field Theory of Dark Energy and Effective Field Theory of Large-Scale Structure approaches. In particular, we parametrize the linear and nonlinear effects of dark energy on dark matter clustering in terms of the Lagrangian terms introduced in a companion paper, focusing on Horndeski theories and assuming the quasi-static approximation. The Euler equation for dark matter is sourced, via the Newtonian potential, by new nonlinear vertices due to modified gravity and, as in the pure dark matter case, by the effects of short-scale physics in the form of the divergence of an effective stress tensor. The effective fluid introduces a counterterm in the solution to the matter continuity and Euler equations, which allows a controlled expansion of clustering statistics on mildly nonlinear scales. We use this setup to compute the one-loop dark-matter power spectrum.

    ↳ astro-ph.COgr-qchep-phJCAP(2018)·82 citations
33. 33*

    The Elliptic Double-Box Integral: Massless Amplitudes Beyond Polylogarithms

    Jacob L. Bourjaily🇩🇰 · Andrew J. McLeod🇩🇰 · Marcus Spradlin🇺🇸 · Matt von Hippel🇩🇰 · Matthias Wilhelm🇩🇰

    We derive an analytic representation of the ten-particle, two-loop double-box integral as an elliptic integral over weight-three polylogarithms. To obtain this form, we first derive a four-fold, rational (Feynman-)parametric representation for the integral, expressed directly in terms of dual-conformally invariant cross-ratios; from this, the desired form is easily obtained. The essential features of this integral are illustrated by means of a simplified toy model, and we attach the relevant expressions for both integrals in ancillary files. We propose a normalization for such integrals that renders all of their polylogarithmic degenerations pure, and we discuss the need for a new 'symbology' of iterated elliptic/polylogarithmic integrals in order to bring them to a more canonical form.

    ↳ hep-thhep-phPRL(2018)·154 citations
34. 34*

    Indirect dark matter searches in the dwarf satellite galaxy Ursa Major II with the MAGIC Telescopes

    MAGIC Collaboration: M. L. Ahnen (1) · S. Ansoldi (2,20) · L. A. Antonelli (3) · C. Arcaro (4) · D. Baack (5) · A. Babić (6) · B. Banerjee (7) · P. Bangale (8) · U. Barres de Almeida (8,9) · J. A. Barrio (10) · J. Becerra González (11) · W. Bednarek (12) and 133 other authors

    The dwarf spheroidal galaxy Ursa Major II (UMaII) is believed to be one of the most dark-matter dominated systems among the Milky Way satellites and represents a suitable target for indirect dark matter (DM) searches. The MAGIC telescopes carried out a deep observation campaign on UMaII between 2014 and 2016, collecting almost one hundred hours of good-quality data. This campaign enlarges the pool of DM targets observed at very high energy (E$\gtrsim$50GeV) in search for signatures of dark matter annihilation in the wide mass range between $\sim$100 GeV and $\sim$100 TeV. To this end, the data are analyzed with the full likelihood analysis, a method based on the exploitation of the spectral information of the recorded events for an optimal sensitivity to the explored dark matter models. We obtain constraints on the annihilation cross-section for different channels that are among the most robust and stringent achieved so far at the TeV mass scale from observations of dwarf satellite galaxies.

    ↳ astro-ph.HEhep-phJCAP(2018)·59 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.