Wed·Oct 26, 2016Wednesday·October 26, 2016

1. 01*

   Implication of the ALEPH 30 GeV dimuon resonance at the LHC

   P. Ko🇰🇷 · Jinmian Li🇰🇷 · Chaehyun Yu🇰🇷

   Recent reanalysis of ALEPH data on Z -> b bar{b} + X seems to indicate an existence of the dimuon excess around 30 GeV with a branching fraction for Z -> b bar{b} mu^+ mu^- around 1.1 X 10^{-5}. In this letter, we discuss three different types of simplified models for this possible excess. In the first class of models, we assume a new resonance couples to both b bar{b} and mu^+ mu^-. Within the allowed parameter space for the ALEPH data, this type of models is excluded because of too large Drell-Yan production of dimuon from the b bar{b} collision at the LHC. In the second model, we assume that the 30 GeV excess is a new gauge boson Z' that couples to the SM b and a new vectorlike singlet B quark heavier than Z and not to b bar{b}. Then one can account for the ALEPH data without conflict with the DY constraint. The new vectorlike quark B can be pair produced at the LHC 8/13 TeV by QCD with sigma(BB) ~ O(100-1000) pb, and Bq production rate is sigma(Bq) ~ a few pb which is larger than sigma(Bb) roughly by an order of magnitude. Their signatures at the LHC would be 2b + 4mu, bj + 2mu and 2b + 2mu, respectively, which however might have been excluded already by LHC run I and II data since the multi-muon events have low SM background and are rare at the LHC. In the third model, we consider Z -> Z' phi followed by Z' -> mu^+ mu^- and phi -> b bar{b} assuming that the Higgs field for Z' mass is also charged under the SM U(1)_Y gauge symmetry. In this class of model, we could accommodate the Br(Z -> b bar{b} mu^+ mu^-) ~ 1.1 X 10^{-5} if we assume very large U(1)' charge for the U(1)' breaking Higgs field. Finally, we study various kinematic distributions of muons and b jets in all the three models, and find that none of the models we consider in this paper are not compatible with the kinematic distributions extracted from the ALEPH data.

   hep-phhep-ex2 citations
2. 02*

   Dark Matter characterization at the LHC in the Effective Field Theory approach

   Alexander Belyaev🇬🇧 · Luca Panizzi🇬🇧 · Alexander Pukhov🇷🇺 · Marc Thomas🇬🇧

   We have studied the complete set of dimension 5 and dimension 6 effective operators involving the interaction of scalar, fermion and vector Dark Matter (DM) with SM quarks and gluons, to explore the possibility to distinguish these operators and characterise the spin of DM at the LHC. We have found that three factors - the effective dimension of the operator, the structure of the SM part of the operator and the parton densities of the SM particles connected to the operator - uniquely define the shape of the (unobservable) invariant mass distribution of the DM pair and, consequently, the shape of the (observable) MET distribution related to it. Using ${\chi }^2$ analysis, we found that at the LHC, with a luminosity of 300 fb${}^{-1}$, certain classes of EFT operators can be distinguished from each other. Hence, since DM spin is partly correlated with the factors defining the shape of MET, the LHC can potentially shed a light also on DM spin. We have also observed a drastic difference in the efficiencies (up to two orders of magnitude) for large MET cuts scenarios with different DM spin, thus indicating that the DM discovery potential strongly depends on it. The study we perform here can be applied more generally than within the EFT paradigm, where the DM mediator is not produced on-the-mass-shell, such as the case of t-channel mediator or mediator with mass below $2M_{DM}$, where the invariant mass of the DM pair is not fixed.

   hep-phJHEP(2017)·30 citations
3. 03*

   Detection prospects for conformally constrained vector-portal dark matter

   Frederick S. Sage🇨🇦 · Zhi-Wei Wang🇩🇰 · Rainer Dick🇨🇦 · T.G. Steele🇨🇦 · R.B. Mann🇨🇦

   We work with a UV conformal U(1)' extension of the Standard Model, motivated by the hierarchy problem and recent collider anomalies. This model admits fermionic vector portal WIMP dark matter charged under the U(1)' gauge group. The asymptotically safe boundary conditions can be used to fix the coupling parameters, which allows the observed thermal relic abundance to constrain the mass of the dark matter particle. This highly restricts the parameter space, allowing strong predictions to be made. The parameter space of several UV conformal U(1)' scenarios will be explored, and both bounds and possible signals from direct and indirect detection observation methods will be discussed.

   hep-phastro-ph.HEPoS(2016)·1 citation
4. 04*

   Redefining the Axion Window

   Luca Di Luzio🇬🇧 · Federico Mescia🇪🇸 · Enrico Nardi🇮🇹

   A major goal of axion searches is to reach inside the parameter space region of realistic axion models. Currently, the boundaries of this region depend on somewhat arbitrary criteria, and it would be desirable to specify them in terms of precise phenomenological requirements. We consider hadronic axion models and classify the representations $R_Q$ of the new heavy quarks $Q$. By requiring that $i)$ the $Q$ are sufficiently short lived to avoid issues with long lived strongly interacting relics, $ii)$ no Landau poles are induced below the Planck scale, fifteen cases are selected, which define a phenomenologically preferred axion window bounded by a maximum (minimum) value of the axion-photon coupling about twice (four times) larger than commonly assumed. Allowing for more than one $R_Q$, larger couplings, as well as complete axion-photon decoupling, become possible.

   hep-phPRL(2017)·261 citations
5. 05*

   Multi-component Dark Matter through a Radiative Higgs Portal

   Anthony DiFranzo🇺🇸 · Gopolang Mohlabeng🇺🇸

   We study a multi-component dark matter model where interactions with the Standard Model are primarily via the Higgs boson. The model contains vector-like fermions charged under $SU(2{)}_W\times U(1{)}_Y$ and under the dark gauge group, $U(1{)}^{\prime }$. This results in two dark matter candidates. A spin-1 and a spin-1/2 candidate, which have loop and tree-level couplings to the Higgs, respectively. We explore the resulting effect on the dark matter relic abundance, while also evaluating constraints on the Higgs invisible width and from direct detection experiments. Generally, we find that this model is highly constrained when the fermionic candidate is the predominant fraction of the dark matter relic abundance.

   hep-phJHEP(2017)·38 citations
6. 06*

   Capture and Decay of Electroweak WIMPonium

   Pouya Asadi🇺🇸 · Matthew Baumgart🇺🇸 · Patrick J. Fitzpatrick🇺🇸 · Emmett Krupczak🇺🇸 · Tracy R. Slatyer🇺🇸

   The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. The presence of these bound states enhances the annihilation rate via resonances in the Sommerfeld enhancement, but they can also be produced directly with the emission of a low-energy photon. In this work we compute the rate for SU(2) triplet dark matter (the wino) to bind into WIMPonium -- which is possible via single-photon emission for wino masses above 5 TeV for relative velocity v < O(10^{-2}) -- and study the subsequent decays of these bound states. We present results with applications beyond the wino case, e.g. for dark matter inhabiting a nonabelian dark sector; these include analytic capture and transition rates for general dark sectors in the limit of vanishing force carrier mass, efficient numerical routines for calculating positive and negative-energy eigenstates of a Hamiltonian containing interactions with both massive and massless force carriers, and a study of the scaling of bound state formation in the short-range Hulthen potential. In the specific case of the wino, we find that the rate for bound state formation is suppressed relative to direct annihilation, and so provides only a small correction to the overall annihilation rate. The soft photons radiated by the capture process and by bound state transitions could permit measurement of the dark matter's quantum numbers; for wino-like dark matter, such photons are rare, but might be observable by a future ground-based gamma-ray telescope combining large effective area and a low energy threshold.

   hep-phastro-ph.COastro-ph.HEJCAP(2017)·90 citations
7. 07*

   Interpretation of Lepton Flavor Violation

   Julian Heeck🇧🇪

   The observation of a charged-lepton flavor violating process would be a definite sign for physics beyond the Standard Model, but would actually only prove that one particular linear combination of lepton numbers is violated. We categorize lepton-flavor-violating processes by their quantum numbers and show how their discovery can be interpreted model independently, studying in particular which processes are required to establish that the entire flavor group is broken. We also comment on total lepton number, seeing as lepton number violation practically implies lepton flavor violation as well.

   hep-phhep-exPRD(2017)·46 citations
8. 08*

   Excited weak bosons and their decays

   Harald Fritzsch🇩🇪

   The weak bosons are bound states of fermions. Here the excitations of the weak bosons are discussed. Especially we study the decays of these excited states into weak bosons and photons.

   hep-phMod.Phys.Lett.A(2017)·3 citations
9. 09*

   Evaluation of the general 3-loop vacuum Feynman integral

   Stephen P. Martin🇺🇸 · David G. Robertson🇺🇸

   We discuss the systematic evaluation of 3-loop vacuum integrals with arbitrary masses. Using integration by parts, the general integral of this type can be reduced algebraically to a few basis integrals. We define a set of modified finite basis integrals that are particularly convenient for expressing renormalized quantities. The basis integrals can be computed numerically by solving coupled first-order differential equations, using as boundary conditions the analytically known special cases that depend on only one mass scale. We provide the results necessary to carry this out, and introduce an implementation in the form of a public software package called 3VIL (3-loop Vacuum Integral Library), which efficiently computes the numerical values of the basis integrals for any specified masses. 3VIL is written in C, and can be linked from C, C++, or FORTRAN code.

   hep-phPRD(2017)·63 citations
10. 10*

    Supersymmetric models on magnetized orbifolds with flux-induced Fayet-Iliopoulos terms

    Hiroyuki Abe🇯🇵 · Tatsuo Kobayashi🇯🇵 · Keigo Sumita🇯🇵 · Yoshiyuki Tatsuta🇯🇵

    We study supersymmetric (SUSY) models derived from the ten-dimensional SUSY Yang- Mills theory compactified on magnetized orbifolds, with nonvanishing Fayet-Iliopoulos (FI) terms induced by magnetic fluxes in extra dimensions. Allowing the presence of FI-terms relaxes a constraint on flux configurations in SUSY model building based on magnetized backgrounds. In this case, charged fields develop their vacuum expectation values (VEVs) to cancel the FI-terms in the D-flat directions of fluxed gauge symmetries, which break the gauge symmetries and lead to a SUSY vacuum. Based on this idea, we propose a new class of SUSY magnetized orbifold models with three generations of quarks and leptons. Especially, we construct a model where the right-handed sneutrinos develop their VEVs which restore the supersymmetry but yield lepton number violating terms below the compactification scale, and show their phenomenological consequences.

    hep-phhep-thPRD(2017)·12 citations
11. 11*

    Momentum transfer dependence of generalized parton distributions

    Neetika Sharma🇮🇳

    We revisit the model for parametrization of momentum dependence of nucleon generalized parton distributions in the light of recent MRST measurements of parton distribution functions. Our parametrization method with minimum set of free parameters give a sufficiently good description of data for Dirac and Pauli electromagnetic form factors of proton and neutron at small and intermediate values of momentum transfer. We also calculate the GPDs for up and down quark by decomposing the electromagnetic form factors for nucleon using the charge and isospin symmetry and also study the evolution of GPDs to a higher scale. We further investigate the transverse charge densities for both the unpolarized and transversely polarized nucleon and compare our results with the Kelly's distribution.

    hep-phEPJA(2016)·12 citations
12. 12*

    Heavy Higgs boson resonances and their decay into top quarks at the LHC

    Werner Bernreuther🇩🇪 · Peter Galler🇩🇪 · Clemens Mellein🇩🇪 · Zong-Guo Si🇨🇳 · Peter Uwer🇩🇪

    We investigate, within the type-II two-Higgs-doublet extension of the standard model (SM), the impact of heavy neutral Higgs boson resonances with unsuppressed Yukawa couplings to top quarks on top-quark pair production at the LHC at next-to-leading order (NLO) in the strong coupling constant. We take into account the resonant Higgs boson contributions, the non-resonant SM $t\bar{t}$ continuum and the interference of these two contributions. The NLO QCD corrections to heavy Higgs production and the interference contributions are calculated in the large top-quark mass ($m_t$) limit, including an effective K-factor rescaling. Our evaluation of the QCD-Higgs interference is focused on the Higgs resonance region. Using representative CP-conserving as well as CP-violating parameter scenarios phenomenological results are presented for different observables.

    hep-phPoS(2016)·1 citation
13. 13*

    Rho meson decay in presence of magnetic field

    Aritra Bandyopadhyay🇮🇳 · S. Mallik🇮🇳

    We find a general expression for the one-loop self-energy function of neutral $\rho$-meson due to ${\pi }^{+}{\pi }^{-}$ intermediate state in a background magnetic field, valid for arbitrary magnitudes of the field. The pion propagator used in this expression is given by Schwinger, which depends on a proper-time parameter. Restricting to weak fields, we calculate the decay rate $\Gamma ({\rho }^0\to {\pi }^{+}+{\pi }^{-})$, which changes negligibly from the vacuum value.

    hep-phEPJC(2017)·26 citations
14. 14*

    Top-quark pair production at next-to-next-to-leading order QCD in electron positron collisions

    Long Chen🇩🇪 · Oliver Dekkers🇩🇪 · Dennis Heisler🇩🇪 · Werner Bernreuther🇩🇪 · Zong-Guo Si🇨🇳

    We set up a formalism, within the antenna subtraction framework, for computing the production of a massive quark-antiquark pair in electron positron collisions at next-to-next-to-leading order in the coupling ${\alpha }_s$ of quantum chromodynamics at the differential level. Our formalism applies to the calculation of any infrared-safe observable. We apply this set-up to the production of top-quark top antiquark pairs in the continuum. We compute the production cross section and several distributions. We determine, in particular, the top-quark forward-backward asymmetry at order ${\alpha }_s^2$. Our result agrees with previous computations of this observable.

    hep-phhep-exJHEP(2016)·37 citations
15. 15*

    The interference effects of multi-channel pion-pion scattering contributions to the final states of $\Psi$- and ${\rm Y}$-meson family decays

    Yu.S. Surovtsev🇷🇺 · P. Bydžovský🇨🇿 · T. Gutsche🇩🇪 · R. Kamiński🇵🇱 · V.E. Lyubovitskij🇩🇪 · M. Nagy🇸🇰

    It is shown that the basic shape of dipion mass distributions in the two-pion transitions of both charmonia and bottomonia states are explained by an unified mechanism based on the contribution of the $\pi \pi$, $K\overline{K}$ and $\eta \eta$ coupled channels including their interference.

    hep-phEPJ Web Conf.(2016)·0 citations
16. 16*

    Residual $Z_2$ symmetries and leptonic mixing patterns from finite discrete subgroups of $U(3)$

    Anjan S. Joshipura🇮🇳 · Ketan M. Patel🇮🇳

    We study embedding of non-commuting $Z_2$ and $Z_m$, $m\ge 3$ symmetries in discrete subgroups (DSG) of $U(3)$ and analytically work out the mixing patterns implied by the assumption that $Z_2$ and $Z_m$ describe the residual symmetries of the neutrino and the charged lepton mass matrices respectively. Both $Z_2$ and $Z_m$ are assumed to be subgroups of a larger discrete symmetry group $G_f$ possessing three dimensional faithful irreducible representation. The residual symmetries predict the magnitude of a column of the leptonic mixing matrix $U_{\mathrm{PMNS}}$ which are studied here assuming $G_f$ as the DSG of $SU(3)$ designated as type C and D and large number of DSG of $U(3)$ which are not in $SU(3)$. These include the known group series $\Sigma (3n^3)$, $T_n(m)$, $\Delta (3n^2,m)$, $\Delta (6n^2,m)$ and ${\Delta }^{\prime }(6n^2,j,k)$. It is shown that the predictions for a column of $|U_{\mathrm{PMNS}}|$ in these group series and the C and D types of groups are all contained in the predictions of the $\Delta (6N^2)$ groups for some integer $N$. The $\Delta (6N^2)$ groups therefore represent a sufficient set of $G_f$ to obtain predictions of the residual symmetries $Z_2$ and $Z_m$.

    hep-phJHEP(2017)·13 citations
17. 17*

    Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector

    D. de Florian🇦🇷 · C. Grojean🇩🇪 · F. Maltoni🇧🇪 · C. Mariotti🇮🇹 · A. Nikitenko🇬🇧 · M. Pieri🇺🇸 · P. Savard🇨🇦 · M. Schumacher🇩🇪 · R. Tanaka (eds.)🇫🇷 · R. Aggleton🇬🇧 · M. Ahmad🇨🇳 · B. Allanach🇬🇧 and 364 other authors

    This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.

    hep-phhep-exCERN Yellow Rep.Monogr.(2017)·2903 citations
18. 18*

    Unexpected properties of interactions of high energy protons

    I.M. Dremin🇷🇺

    Experimental data on proton-proton interactions in high energy collisions show quite a special and unexpected behaviour of the proportion of elastic scattering compared to inelastic processes with increasing energy. It decreases at the beginning (at comparatively low energies) but then starts increasing. From Intersecting Storage Rings (ISR) energies of 23.5 - 62.5 GeV up to higher energies 7 - 13 TeV at the Large Hadron Collider (LHC) it increases by a factor more than 1.5! According to intuitive classical ideas we would expect a stable tendency with increasing proportion of the break-down of protons compared to their survival probability. One can assume that either the asymptotic freedom or the extremely short time of flight of high energy protons through each other are in charge of such a surprising effect. The unquestionable principle of unitarity combined with the available experimental data on elastic scattering is used to get new conclusions about the shape of the interaction region of colliding protons. Its evolution at present energies is considered. Some predictions about its behaviour at even higher energies are described with different assumptions on relative roles of elastic scattering and inelastic processes. The shape can transform rather drastically if the proportion of elastic processes keeps rising. This unexpected property leads to an unexpected corollary. The possible origin of the effect and its interrelation to the strong interaction dynamics are speculated.

    hep-phhep-exnucl-exnucl-thPhys.Usp.(2017)·22 citations
19. 19*

    Theory Overview

    Alexander Lenz🇬🇧

    We set the scene for theoretical issues in charm physics that were discussed at CHARM 2016 in Bologna. In particular we emphasize the importance of improving our understanding of standard model contributions to numerous charm observables and we discuss also possible tests of our theory tools, like the Heavy Quark Expansion via the lifetime ratios of $D$-mesons

    hep-phhep-exPoS(2017)·5 citations
20. 20*

    Analytical On-shell Calculation of Higher Order Scattering: Massive Particles

    Barry R. Holstein🇺🇸

    We demonstrate that the use of on-shell methods, involving calculation of the discontinuity across the t-channel cut associated with the exchange of a pair of massless particles, can be used to evaluate loop contributions to both the electromagnetic and gravitational scattering of massive systems. In the gravitational case, the use of factorization permits a straightforward and algebraic calculation of higher order scattering results, which were obtained previously by much more arduous Feynman diagram techniques.

    hep-phgr-qchep-thnucl-th9 citations
21. 21*

    Constraints on Axion couplings from the CDEX-1 experiment at the China Jinping Underground Laboratory

    S.K. Liu🇨🇳 · Q. Yue🇨🇳 · K.J. Kang🇨🇳 · J.P. Cheng🇨🇳 · H.T. Wong🇹🇼 · Y.J. Li🇨🇳 · H.B. Li🇹🇼 · S.T. Lin🇨🇳 · J.P. Chang🇨🇳 · J.H. Chen🇹🇼 · N. Chen🇨🇳 · Q.H. Chen🇨🇳 and 62 other authors

    We report the results of searches for solar axions and galactic dark matter axions or axion-like particles with CDEX-1 experiment at the China Jinping Underground Laboratory, using 335.6 kg-days of data from a p-type point-contact germanium detector. The data are compatible with the background model and no excess signals are observed. Limits of solar axions on the model independent coupling $g_{Ae}<2.5\times 10^{-11}$ from Compton, bremsstrahlung, atomic-recombination and deexcitation channel and $g_{AN}^{\text{eff}}\times g_{Ae}<6.1\times 10^{-17}$ from ${}^{57}$Fe M1 transition at 90 % confidence level are derived. Within the framework of the DFSZ and KSVZ models, our results exclude the axion mass heavier than 0.9 eV/c${}^2$ and 173 eV/c${}^2$, respectively. The derived constraints for dark matter axions below 1 keV improves over the previous results.

    ↳ hep-exhep-phphysics.ins-detPRD(2017)·39 citations
22. 22*

    Radial acceleration relation from symmetron fifth forces

    Clare Burrage🇬🇧 · Edmund J. Copeland🇬🇧 · Peter Millington🇬🇧

    We show that the radial acceleration relation for rotationally-supported galaxies may be explained, in the absence of cold dark matter, by a non-minimally coupled scalar field, whose fifth forces are partially screened on galactic scales by the symmetron mechanism. In addition, we show that sufficient energy is stored in the symmetron field to explain the dynamic stability of galactic disks.

    ↳ astro-ph.COastro-ph.GAgr-qchep-phPRD(2017)·70 citations
23. 23*

    Model Selection for Pion Photoproduction

    J. Landay🇺🇸 · M. Döring🇺🇸 · C. Fernández-Ramírez🇲🇽 · B. Hu🇺🇸 · R. Molina🇺🇸

    Partial-wave analysis of meson and photon-induced reactions is needed to enable the comparison of many theoretical approaches to data. In both energy-dependent and independent parametrizations of partial waves, the selection of the model amplitude is crucial. Principles of the $S$-matrix are implemented to different degree in different approaches, but a many times overlooked aspect concerns the selection of undetermined coefficients and functional forms for fitting, leading to a minimal yet sufficient parametrization. We present an analysis of low-energy neutral pion photoproduction using the Least Absolute Shrinkage and Selection Operator (LASSO) in combination with criteria from information theory and $K$-fold cross validation. These methods are not yet widely known in the analysis of excited hadrons but will become relevant in the era of precision spectroscopy. The principle is first illustrated with synthetic data, then, its feasibility for real data is demonstrated by analyzing the latest available measurements of differential cross sections ($d\sigma /d\Omega$), photon-beam asymmetries ($\Sigma$), and target asymmetry differential cross sections ($d{\sigma }_T/d\Omega$) in the low energy regime.

    ↳ nucl-thhep-phnucl-exPRC(2017)·41 citations
24. 24*

    Functional renormalization group studies of nuclear and neutron matter

    Matthias Drews🇩🇪 · Wolfram Weise🇩🇪

    Functional renormalization group (FRG) methods applied to calculations of isospin-symmetric and asymmetric nuclear matter as well as neutron matter are reviewed. The approach is based on a chiral Lagrangian expressed in terms of nucleon and meson degrees of freedom as appropriate for the hadronic phase of QCD with spontaneously broken chiral symmetry. Fluctuations beyond mean-field approximation are treated solving Wetterich's FRG flow equations. Nuclear thermodynamics and the nuclear liquid-gas phase transition are investigated in detail, both in symmetric matter and as a function of the proton fraction in asymmetric matter. The equations of state at zero temperature of symmetric nuclear matter and pure neutron matter are found to be in good agreement with advanced ab-initio many-body computations. Contacts with perturbative many-body approaches (in-medium chiral perturbation theory) are discussed. As an interesting test case, the density dependence of the pion mass in the medium is investigated. The question of chiral symmetry restoration in nuclear and neutron matter is addressed. A stabilization of the phase with spontaneously broken chiral symmetry is found to persist up to high baryon densities once fluctuations beyond mean-field are included. Neutron star matter including beta equilibrium is discussed under the aspect of the constraints imposed by the existence of two-solar-mass neutron stars.

    ↳ nucl-thhep-phPPNP(2017)·79 citations
25. 25*

    Multi-Boson Interactions at the LHC

    Daniel R. Green🇺🇸 · Patrick Meade🇺🇸 · Marc-Andre Pleier🇺🇸

    This review covers results on the production of all possible electroweak boson pairs and 2-to-1 vector boson fusion at the CERN Large Hadron Collider (LHC) in proton-proton collisions at a center of mass energy of 7 and 8 TeV. The data were taken between 2010 and 2012. Limits on anomalous triple gauge couplings (aTGCs) then follow. In addition, data on electroweak triple gauge boson production and 2-to-2 vector boson scattering yield limits on anomalous quartic gauge boson couplings (aQGCs). The LHC hosts two general purpose experiments, ATLAS and CMS, which have both reported limits on aTGCs and aQGCs which are herein summarized. The interpretation of these limits in terms of an effective field theory is reviewed, and recommendations are made for testing other types of new physics using multi-gauge boson production.

    ↳ hep-exhep-phRMP(2017)·101 citations
26. 26*

    Baryon-Strangeness Correlations in Au+Au Collisions at $\sqrt{s_{\mathrm{NN}}}$=7.7-200 GeV from the UrQMD model

    Zhenzhen Yang🇨🇳 · Xiaofeng Luo🇨🇳 · Bedangadas Mohanty🇮🇳

    Fluctuations and correlations of conserved charges are sensitive observables for studying the QCD phase transition and critical point in high-energy heavy-ion collisions. We have studied the centrality and energy dependence of mixed-cumulants (up to fourth order) between net-baryon and net-strangeness in Au+Au collisions at $\sqrt{s_{NN}}$= 7.7, 11.5, 19.6, 27, 39, 62.4, 200 GeV from UrQMD model. To compare with other theoretical calculations, we normalize these mixed-cumulants by various order cumulants of net-strangeness distributions. We found that the results obtained from UrQMD calculations are comparable with the results from Lattice QCD at low temperature and hadron resonance gas model. The ratios of mixed-cumulants ($R_{11}^{BS},R_{13}^{BS},R_{22}^{BS}$,~$R_{31}^{BS}$) from UrQMD calculations show weak centrality dependence. However, the mixed-cumulant ratios $R_{11}^{BS}$ and $R_{31}^{BS}$ show strong increase at low energy, while the $R_{13}^{BS}$ snd $R_{22}^{BS}$ are similar at different energies. Furthermore, we have also studied the correlations between different hadron species and their contributions to the net-baryon and net-strangeness correlations. These models studies can provide baselines for searching for the signals of QCD phase transition and critical point in heavy-ion collisions.

    ↳ nucl-exhep-exhep-phnucl-thPRC(2017)·14 citations
27. 27*

    Gamma Rays From Dark Matter Subhalos Revisited: Refining the Predictions and Constraints

    Dan Hooper🇺🇸 · Samuel J. Witte🇺🇸

    Utilizing data from the ELVIS and Via Lactea-II simulations, we characterize the local dark matter subhalo population, and use this information to refine the predictions for the gamma-ray fluxes arising from annihilating dark matter in this class of objects. We find that the shapes of nearby subhalos are significantly altered by tidal effects, and are generally not well described by NFW density profiles, instead prefering power-law profiles with an exponential cutoff. From the subhalo candidates detected by the Fermi Gamma-Ray Space Telescope, we place limits on the dark matter annihilation cross section that are only modestly weaker than those based on observations of dwarf galaxies. We also calculate the fraction of observable subhalos that are predicted to be spatially extended at a level potentially discernible to Fermi.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phJCAP(2017)·43 citations
28. 28*

    Quasiparticle anisotropic hydrodynamics

    Mubarak Alqahtani🇺🇸 · Michael Strickland🇺🇸

    We study an azimuthally-symmetric boost-invariant quark-gluon plasma using quasiparticle anisotropic hydrodynamics including the effects of both shear and bulk viscosities. We compare results obtained using the quasiparticle method with the standard anisotropic hydrodynamics and viscous hydrodynamics. We consider the predictions of the three methods for the differential particle spectra and mean transverse momentum. We find that the three methods agree for small shear viscosity to entropy density ratio, $\eta /s$, but show differences at large $\eta /s$. Additionally, we find that the standard anisotropic hydrodynamics method shows suppressed production at low transverse-momentum compared to the other two methods, and the bulk-viscous correction can drive the primordial particle spectra negative at large $p_T$ in viscous hydrodynamics.

    ↳ nucl-thhep-phJ.Phys.Conf.Ser.(2017)·4 citations
29. 29*

    In-medium dispersion relations of charmonia studied by maximum entropy method

    Atsuro Ikeda🇯🇵 · Masayuki Asakawa🇯🇵 · Masakiyo Kitazawa🇯🇵

    We study in-medium spectral properties of charmonia in the vector and pseudoscalar channels at nonzero momenta on quenched lattices, especially focusing on their dispersion relation and weight of the peak. We measure the lattice Euclidean correlation functions with nonzero momenta on the anisotropic quenched lattices and study the spectral functions with the maximum entropy method. The dispersion relations of charmonia and the momentum dependence of the weight of the peak are analyzed with the maximum entropy method together with the errors estimated probabilistically in this method. We find significant increase of the masses of charmonia in medium. It is also found that the functional form of the charmonium dispersion relations is not changed from that in the vacuum within the error even at $T\simeq 1.6T_c$ for all the channels we analyzed.

    ↳ hep-lathep-phnucl-thPRD(2017)·21 citations
30. 30*

    Equation of State for SU(3) Gauge Theory via the Energy-Momentum Tensor under Gradient Flow

    Masakiyo Kitazawa🇯🇵 · Takumi Iritani🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsuo Hatsuda🇯🇵 · Hiroshi Suzuki🇯🇵

    The energy density and the pressure of SU(3) gauge theory at finite temperature are studied by direct lattice measurements of the renormalized energy-momentum tensor obtained by the gradient flow. Numerical analyses are carried out with $\beta =6.287$--$7.500$ corresponding to the lattice spacing $a=0.013$--$0.061\mathrm{fm}$. The spatial (temporal) sizes are chosen to be $N_s=64$, $96$, $128$ ($N_{\tau }=12$, $16$, $20$, $22$, $24$) with the aspect ratio, $5.33\le N_s/N_{\tau }\le 8$. Double extrapolation, $a\to 0$ (the continuum limit) followed by $t\to 0$ (the zero flow-time limit), is taken using the numerical data. Above the critical temperature, the thermodynamic quantities are obtained with a few percent precision including statistical and systematic errors. The results are in good agreement with previous high-precision data obtained by using the integral method.

    ↳ hep-lathep-phnucl-thPRD(2016)·102 citations
31. 31*

    Unified description of dark energy and dark matter in mimetic matter model

    Jiro Matsumoto🇷🇺

    The existence of dark matter and dark energy in cosmology is implied by various observations, however, they are still unclear because they have not been directly detected. In this Letter, an unified model of dark energy and dark matter that can explain the evolution history of the Universe later than inflationary era, the time evolution of the growth rate function of the matter density contrast, the flat rotation curves of the spiral galaxies, and the gravitational experiments in the solar system is proposed in mimetic matter model.

    ↳ astro-ph.COgr-qchep-phhep-th15 citations
32. 32*

    Spectator Higgs, large-scale gauge fields and the non-minimal coupling to gravity

    Massimo Giovannini🇨🇭

    Even if the Higgs field does not affect the evolution of the background geometry, its massive inhomogeneities induce large-scale gauge fields whose energy density depends on the slow-roll parameters, on the effective scalar mass and, last but not least, on the dimensionless coupling to the space-time curvature. Since the non-Abelian gauge modes are screened, the non-minimal coupling to gravity predominantly affects the evolution of the hypercharge and electromagnetic fields. While in the case of minimal coupling the obtained constraints are immaterial, as soon as the coupling increases beyond one fourth the produced fields become overcritical. We chart the whole parameter space of this qualitatively new set of bounds. Whenever the limits on the curvature coupling are enforced, the magnetic field may still be partially relevant for large-scale magnetogenesis and exceed $10^{-20}$ G for the benchmark scale of the protogalactic collapse.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2017)·4 citations
33. 33*

    Dynamics of Anti-Proton -- Protons and Anti-Proton -- Nucleus Reactions

    A. Galoyan🇷🇺 · A. Ribon🇨🇭 · V. Uzhinsky🇷🇺

    A short review of simulation results of anti-proton-proton and anti-proton-nucleus interactions within the framework of Geant4 FTF (Fritiof) model is presented. The model uses the main assumptions of the Quark-Gluon-String Model or Dual Parton Model. The model assumes production and fragmentation of quark-anti-quark and diquark-anti-diquark strings in the mentioned interactions. Key ingredients of the model are cross sections of string creation processes and an usage of the LUND string fragmentation algorithm. They allow one to satisfactory describe a large set of experimental data, especially, a strange particle production, Lambda hyperons and K mesons.

    ↳ nucl-thhep-phNucl.Theor.(2016)·4 citations
34. 34*

    Charge conservation effects for high order fluctuations

    Viktor Begun🇵🇱

    The exact charge conservation significantly impacts multiplicity fluctuations. The result depends strongly on the part of the system charge carried by the particles of interest. Along with the expected suppression of fluctuations for large systems, charge conservation may lead to negative skewness or kurtosis for small systems.

    ↳ nucl-thhep-phnucl-exActa Phys.Polon.Supp.(2017)·1 citation

* 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.