Mon·Sep 19, 2016Monday·September 19, 2016

1. 01*

   Spontaneous CP violation in the 2HDM: physical conditions and the alignment limit

   B. Grzadkowski🇵🇱 · O. M. Ogreid🇳🇴 · P. Osland🇳🇴

   For the general Two-Higgs-Doublet model, we present conditions for having spontaneous CP violation, in terms of physical masses and couplings. These relations involve the charged-Higgs mass, its cubic couplings with neutral scalars and quartic coupling, and become particularly simple in the alignment limit. In the simplified model with softly broken $Z_2$ symmetry, some deviation from alignment is required for spontaneous CP violation to be present.

   hep-phPRD(2016)·39 citations
2. 02*

   Patterns of Flavour Violation in Models with Vector-Like Quarks

   Christoph Bobeth🇩🇪 · Andrzej J. Buras🇩🇪 · Alejandro Celis🇩🇪 · Martin Jung🇩🇪

   We study the patterns of flavour violation in renormalisable extensions of the Standard Model (SM) that contain vector-like quarks (VLQs) in a single complex representation of either the SM gauge group $G_{SM}$ or $G_{SM}^{\prime }=G_{SM}\times U(1{)}_{L_{\mu }-L_{\tau }}$. We first decouple VLQs in the $M=(1-10)$ TeV range and then at the electroweak scale also $Z,Z^{\prime }$ gauge bosons and additional scalars to study the resulting phenomenology that depends on the relative size of $Z$- and $Z^{\prime }$-induced flavour-changing neutral currents, as well as the size of $\Delta F=2$ contributions including the effects of renormalisation group Yukawa evolution from $M$ to the electroweak scale that turn out to be very important for models with right-handed currents through the generation of left-right operators. In addition to rare decays like $P\to \ell \bar{\ell }$, $P\to P^{\prime }\ell \bar{\ell }$, $P\to P^{\prime }\nu \bar{\nu }$ with $P=K,B_s,B_d$ and $\Delta F=2$ observables we analyze the ratio ${\epsilon }^{\prime }/\epsilon$ which appears in the SM to be significantly below the data. We study patterns and correlations between these observables which taken together should in the future allow for differentiating between VLQ models. In particular the patterns in models with left-handed and right-handed currents are markedly different from each other. Among the highlights are large $Z$-mediated new physics effects in Kaon observables in some of the models and significant effects in $B_{s,d}$-observables. ${\epsilon }^{\prime }/\epsilon$ can easily be made consistent with the data, implying then uniquely the suppression of $K_L\to {\pi }^0\nu \bar{\nu }$. Significant enhancements of $Br(K^{+}\to {\pi }^{+}\nu \bar{\nu })$ are still possible. We point out that the combination of $\Delta F=2$ and $\Delta F=1$ observables in a given meson system generally allows to determine the masses of VLQs independently of the size of VLQ couplings.

   hep-phhep-exhep-latJHEP(2017)·138 citations
3. 03*

   Gluon fusion contribution to $HBB$ ($B=H,\gamma ,Z$) at the LHC

   Ambresh Shivaji🇮🇹 · Pankaj Agrawal🇮🇳 · Debashis Saha🇮🇳

   We have calculated one-loop amplitudes for the production of Higgs boson in association with two electroweak bosons ($H,\gamma ,Z$) via gluon-gluon fusion. We present preliminary results for the total cross section at 8, 13 and 100 TeV center-of-mass energies at $pp$ colliders. We study the interference effect and, also comment on the effect of new physics in terms of anomalous couplings of the Higgs boson in these processes.

   hep-phEPJ Web Conf.(2016)·2 citations
4. 04*

   Late decaying 2-component dark matter scenario as an explanation of the AMS-02 positron excess

   Jatan Buch🇮🇳 · Pranjal Ralegankar🇮🇳 · Vikram Rentala🇮🇳

   The long standing anomaly in the positron flux as measured by the PAMELA and AMS-02 experiments could potentially be explained by dark matter (DM) annihilations. This scenario typically requires a large "boost factor" to be consistent with a thermal relic dark matter candidate produced via freeze-out. However, such an explanation is disfavored by constraints from CMB observations on energy deposition during the epoch of recombination. We discuss a scenario called late-decaying two-component dark matter (LD2DM), where the entire DM consists of two semi-degenerate species. Within this framework, the heavier species is produced as a thermal relic in the early universe and decays to the lighter species over cosmological timescales. Consequently, the lighter species becomes the DM which populates the universe today. We show that annihilation of the lighter DM species with an enhanced cross-section, produced via such a non-thermal mechanism, can explain the observed AMS-02 positron flux while avoiding CMB constraints. The observed DM relic density can be correctly reproduced as well with simple s-wave annihilation cross-sections. We demonstrate that the scenario is safe from CMB constraints on late-time energy depositions during the cosmic "dark ages". Interestingly, structure formation constraints force us to consider small mass splittings between the two dark matter species. We explore possible cosmological and particle physics signatures in a toy model that realizes this scenario.

   hep-phastro-ph.COastro-ph.HEJCAP(2017)·19 citations
5. 05*

   Higgs-Stoponium Mixing Near the Stop-Antistop Threshold

   Geoffrey T. Bodwin🇺🇸 · Hee Sok Chung🇺🇸 · Carlos E. M. Wagner🇺🇸

   Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop production threshold. Existing work in the literature has examined the digluon-to-diphoton cross section near threshold and has focused on enhancements in the cross section that might arise either from the perturbative contributions to the Higgs-to-digluon and Higgs-to-diphoton form factors or from mixing of the Higgs boson with stoponium states. Near threshold, enhancements in the relevant amplitudes that go as inverse powers of the stop-antistop relative velocity require resummations of perturbation theory and/or nonperturbative treatments. We present a complete formulation of threshold effects at leading order in the stop-antistop relative velocity in terms of nonrelativistic effective field theory. We give detailed numerical calculations for the case in which the stop-antistop Green's function is modeled with a Coulomb-Schrödinger Green's function. We find several general effects that do not appear in a purely perturbative treatment. Higgs-stop-antistop mixing effects displace physical masses from the threshold region, thereby rendering the perturbative threshold enhancements inoperative. In the case of large Higgs-stop-antistop couplings, the displacement of a physical state above threshold substantially increases its width, owing to its decay width to a stop-antistop pair, and greatly reduces its contribution to the cross section.

   hep-phPRD(2017)·9 citations
6. 06*

   Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

   Celine Degrande🇨🇭 · Benjamin Fuks🇫🇷 · Kentarou Mawatari🇫🇷 · Ken Mimasu🇬🇧 · Veronica Sanz🇬🇧

   We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run~I data can be further constrained by LHC Run~II future results.

   hep-phEPJC(2017)·93 citations
7. 07*

   Augmenting Collider Searches and Enhancing Discovery Potentials through Stochastic Jet Grooming

   Tuhin S. Roy🇮🇳 · Arun M. Thalapillil🇺🇸

   The jet Trimming procedure has been demonstrated to greatly improve event reconstruction in hadron collisions, by mitigating contamination due initial state radiation, multiple interactions, and event pileup. Meanwhile, Qjets -- a nondeterministic approach to tree-based jet substructure has been shown to be a powerful technique in decreasing random statistical fluctuations, yielding significant effective luminosity improvements. This manifests through an improvement in the significance $S/\delta B$, relative to conventional methods. Qjets also provide novel observables in many cases, like mass-volatility, that could be used to further discriminate between signal and background events. The statistical robustness and volatility observables, for tagging, are obtained simultaneously. We explore here a combination of the two techniques, and demonstrate that significant enhancements in discovery potentials may be obtained in non-trivial ways. We will illustrate this by considering a diboson resonance analysis as a case study -- enabling us to interpolate between scenarios where the gains are purely due to statistical robustness and scenarios where the gains are also reinforced by volatility variable discriminants. The former, for instance, is applicable to digluon/diquark resonances, while the latter will be of relevance to di-$W^{\pm }$/di-$Z^0$ resonances, where the boosted vector bosons are decaying hadronically and have an intrinsic mass scale attached to them. We argue that one can enhance signal significance and discovery potentials markedly through stochastic grooming, and help augment studies at the Large Hadron Collider and future hadron colliders.

   hep-phhep-exPRD(2017)·2 citations
8. 08*

   Photon initiated single top quark production via flavor-changing neutral currents at the LHC

   Reza Goldouzian🇧🇪 · Barbara Clerbaux🇧🇪

   Single top quark production is a powerful process to search for new physics signs. In this work we propose and investigate a search for top quark flavor changing neutral currents (FCNC) via a photon using direct single top quark production events in proton-proton collisions at the LHC at CERN. We show that the direct single top quark final state can provide constraints on the strengths of tq$\gamma$ (top-quark-$\gamma$) and tqg (top-quark-gluon) FCNC couplings simultaneously. Results of a search for direct single top quark production at the LHC at a center-of-mass energy of 8 TeV performed by the ATLAS collaboration are used to set first experimental limits on the anomalous FCNC top decay branching fractions $\mathcal{B}$(t$\to$ u$\gamma$) $<$ 0.05% and $\mathcal{B}$(t$\to$ c$\gamma$) $<$ 0.14% via direct single top quark production. Finally, the sensitivity of the proposed channel for probing the tq$\gamma$ couplings at 13 TeV is presented.

   hep-phPRD(2017)·16 citations
9. 09*

   Psi(2S) Production at the LHC

   Xiaojian Du🇺🇸 · Ralf Rapp🇺🇸

   We calculate the production of $\psi (2S)$ and the pertinent double ratio of its nuclear modification factor ($R_{\mathrm{AA}}$) over that of the $J/\psi$ in Pb-Pb collisions at the LHC. Based on a transport model with temperature dependent reaction rates, a sequential regeneration pattern emerges: the larger $\psi (2S)$ width, relative to the $J/\psi$, around and below the critical temperature, implies that most of the $\psi (2S)$ states are regenerated later in the evolution of the fireball. This has noticeable consequences for the transverse-momentum ($p_T$) spectra of the regenerated charmonia. While the total yield of $\psi (2S)$ meson remains smaller than those of $J/\psi$'s, their harder $p_T$ spectra can produce a double ratio above unity for a $p_T>3$GeV cut, as applied by the CMS collaboration. A significant uncertainty in our calculations is associated with the values of the temperature where most of the $\psi (2S)$ regeneration occurs, the quantitative temperature dependence of its inelastic width.

   hep-phnucl-thJ.Phys.Conf.Ser.(2017)·10 citations
10. 10*

    Directional Searches at DUNE for Sub-GeV Monoenergetic Neutrinos Arising from Dark Matter Annihilation in the Sun

    Carsten Rott🇰🇷 · Seongjin In🇰🇷 · Jason Kumar🇺🇸 · David Yaylali🇺🇸

    We consider the use of directionality in the search for monoenergetic sub-GeV neutrinos arising from the decay of stopped kaons, which can be produced by dark matter annihilation in the core of the Sun. When these neutrinos undergo charged-current interactions with a nucleus at a neutrino detector, they often eject a proton which is highly peaked in the forward direction. The direction of this track can be measured at DUNE, allowing one to distinguish signal from background by comparing on-source and off-source event rates. We find that directional information can enhance the signal to background ratio by up to a factor of 5.

    hep-phJCAP(2017)·25 citations
11. 11*

    $T$-Matrix Approach to Strongly Coupled QGP

    Shuai Y.F. Liu🇺🇸 · Ralf Rapp🇺🇸

    Based on a thermodynamic $T$-matrix approach we extract the potential $V$ between two static charges in the quark-gluon plasma (QGP) from fits to the pertinent lattice-QCD free energy. With suitable relativistic corrections we utilize this new potential to compute heavy-quark transport coefficients and compare the results to previous calculations using either $F$ or $U$ as potential. We then discuss a generalization of the $T$-matrix re-summation to a "matrix $\log$" re-summation of $t$-channel diagrams for the grand partition function of the QGP in the Luttinger-Ward skeleton diagram formalism. With $V$ as a non-perturbative driving kernel in the light-parton sector, we obtain the QGP equation of state from fits to lattice-QCD data. The resulting light-parton spectral functions are characterized by large thermal widths at small momenta, indicating the dissolution of quasi-particles in a strongly coupled QGP.

    hep-phnucl-thJ.Phys.Conf.Ser.(2017)·6 citations
12. 12*

    Heavy flavor production in heavy-ion collisions from soft collinear effective theory

    Zhong-Bo Kang🇺🇸 · Felix Ringer🇺🇸 · Ivan Vitev🇺🇸

    We review a new approach to open heavy flavor production in heavy ion collisions based on Soft Collinear Effective Theory (SCET). We include both finite heavy quark masses in the SCET Lagrangian and Glauber gluons that describe the interaction of collinear partons with the hot and dense QCD medium. From the new effective field theory, we derive massive in-medium splitting kernels and propose a new framework for including in-medium interactions consistent with next-to-leading order calculations in QCD. We present numerical results for the suppression of $D$- and $B$-mesons and compare to results obtained within the traditional approach to parton energy loss. We find good agreement when comparing to existing data from the LHC at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and 2.76 TeV.

    hep-phhep-exnucl-exJ.Phys.Conf.Ser.(2017)·3 citations
13. 13*

    Theory overview of Heavy Ion collisions

    T. Lappi🇫🇮

    This presentation discusses some recently active topics in the theoretical interpretation of high energy heavy ion collisions at the LHC and at RHIC. We argue that the standard paradigm for understanding the spacetime evolution of the bulk of the matter produced in the collision is provided by viscous relativistic hydrodynamics, which can be used to systematically extract properties of the QCD medium from experimental results. The initial conditions of this hydrodynamical evolution are increasingly well understood in terms of gluon saturation, and can be quantified using Classical Yang-Mills fields and QCD effective kinetic theory. Hard and electromagnetic probes of the plasma provide additional constraints. A particularly fascinating subject are high multiplicity proton-proton and proton-nucleus collisions, where some of the characteristics previously attributed to only nucleus-nucleus collisions have been observed.

    hep-phnucl-thPoS(2016)·3 citations
14. 14*

    Photon polarization tensor in a magnetized plasma system

    Jingyi Chao🇨🇳 · Mei Huang🇨🇳

    We investigate the photon polarization tensor at finite temperature in the presence of a static and homogeneous external magnetic field. In our scheme, the Matsubara frequency summation is performed after Poisson summation, which will be taken easily and convergent quickly in the frame of proper time representation. Moreover, the dependence of Landau levels is expressed explicitly. It demonstrates the convergence of summing Landau levels as it has to be. Consequently, there is no necessary to truncate the Landau level in a numerical estimation. At zero temperature, the Lowest Landau Level (LLL) approximation is analytically satisfied for the imaginary parts of the vacuum photon polarization tensor. Our results examine that, the LLL approximation is not enough for the thermal photon polarization tensor, it gains the contribution not only from the lowest Landau level but also up to the finite-$n$ levels. Such large imaginary ones only show up at finite temperatures, which is the so called Landau damping. It originates from the absorption of soft fields by hard plasma constituents, which is a universal feature of plasma systems. Finally, it was argued that the summation of Matsubara frequency is not commuted with Landau level ones, such conjecture is excluded in our calculations.

    hep-phhep-thCommun.Theor.Phys.(2020)·4 citations
15. 15*

    Predicting the neutralino relic density in the MSSM more precisely

    Julia Harz🇫🇷 · Björn Herrmann🇫🇷 · Michael Klasen🇩🇪 · Karol Kovařík🇩🇪 · Patrick Steppeler🇩🇪

    The dark matter relic density being a powerful observable to constrain models of new physics, the recent experimental progress calls for more precise theoretical predictions. On the particle physics side, improvements are to be made in the calculation of the (co)annihilation cross-section of the dark matter particle. We present the project DM@NLO which aims at calculating the neutralino (co)annihilation cross-section in the MSSM including radiative corrections in QCD. In the present document, we briefly review selected results for different (co)annihilation processes. We then discuss the estimation of the associated theory uncertainty obtained by varying the renormalization scale. Finally, perspectives are discussed.

    hep-phPoS(2016)·1 citation
16. 16*

    Primordial Lepton Oscillations and Baryogenesis

    Yuta Hamada🇯🇵 · Ryuichiro Kitano🇯🇵

    The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the $CP$ violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.

    hep-phastro-ph.COJHEP(2016)·15 citations
17. 17*

    Phenomenology of minimal Z' models: from the LHC to the GUT scale

    Elena Accomando🇬🇧 · Claudio Coriano🇮🇹 · Luigi Delle Rose🇬🇧 · Juri Fiaschi🇬🇧 · Carlo Marzo🇮🇹 · Stefano Moretti🇬🇧

    We consider a class of minimal abelian extensions of the Standard Model with an extra neutral gauge boson $Z^{\prime }$ at the TeV scale. In these scenarios an extended scalar sector and heavy right-handed neutrinos are naturally envisaged. We present some of their striking signatures at the Large Hadron Collider, the most interesting arising from a $Z^{\prime }$ decaying to heavy neutrino pairs as well as a heavy scalar decaying to two Standard Model Higgses. Using renormalisation group methods, we characterise the high energy behaviours of these extensions and exploit the constraints imposed by the embedding into a wider GUT scenario.

    hep-phEPJ Web Conf.(2016)·5 citations
18. 18*

    Isospin breaking in the decay constants of heavy mesons from QCD sum rules

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

    We present a study of the strong isospin-breaking (IB) effect, due in QCD to the difference between $u$- and $d$-quark masses, in the leptonic decay constants of charmed and beauty pseudoscalar and vector mesons using the method of QCD sum rules. We apply the sum-rule analysis to the decay constants of mesons containing one heavy quark and one light quark with the light mass in the range from the average $u/d$ quark mass to the strange-quark mass. We then analyse the dependence of the decay constants on the light quark mass and extract with good accuracy the IB ratios of decay constants at leading order in the mass difference $(m_d-m_u)$, obtaining: $(f_{D^{+}}-f_{D^0})/f_D=0.0047(6)$, $(f_{D^{\ast +}}-f_{D^{\ast 0}})/f_{D^{\ast }}=0.0068(9)$, $(f_{B^0}-f_{B^{+}})/f_B=0.0047(6)$, and $(f_{B^{\ast 0}}-f_{B^{\ast +}})/f_{B^{\ast }}=0.0045(5)$, which yield: $f_{D^{+}}-f_{D^0}=0.97\pm 0.13$ MeV, $f_{D^{\ast +}}-f_{D^{\ast 0}}=1.73\pm 0.27$ MeV, $f_{B^0}-f_{B^{+}}=0.90\pm 0.13$ MeV, $f_{B^{\ast 0}}-f_{B^{\ast +}}=0.81\pm 0.11$ MeV. In the case of the $D$-meson our finding is consistent with recent lattice QCD results, whereas it is much lower in the case of the $B$-meson showing a tension of $\approx 3$ standard deviations.

    hep-phhep-latPLB(2017)·14 citations
19. 19*

    Matching uncertainties in the prediction of the Higgs boson transverse momentum in the SM and beyond

    Emanuele Bagnaschi🇩🇪

    We present the results of our recent study (arXiv:1510.08850) of the theoretical uncertainties that affect the predictions for the Higgs-boson transverse-momentum in gluon fusion when fixed- and all-order results are matched. Our investigation consists of a twofold analysis: first we present a detailed comparison of two recently introduced prescriptions for the determination of the matching scale (arXiv:1409.0531, arXiv:1505.00735), then we apply the results of these methods to three widely used matching frameworks, namely the aMC@NLO and POWHEG Monte Carlo approaches and analytic resummation. The results of our study are applied to the production of the SM Higgs boson and of the neutral Higgs bosons of the Two-Higgs-Doublet Model in a variety of scenarios.

    hep-phPoS(2016)·0 citations
20. 20*

    STAX. An Axion-like Particle Search with Microwave Photons

    J. Ferretti🇮🇹

    We discuss an improved detection scheme for a light-shining-through-wall (LSW) experiment for axion-like particle searches. We propose to use: gyrotrons or klystrons, which can provide extremely intense photon fluxes at frequencies around 30 GHz; transition-edge-sensors (TES) single photon detectors in this frequency domain, with efficiency $\approx 1$; high quality factor Fabry-Perot cavities in the microwave domain, both on the photon-axion conversion and photon regeneration sides. We compute that present laboratory exclusion limits on axion-like particles might be improved by at least four orders of magnitude for axion masses $\lesssim 0.02$ meV.

    hep-ph4 citations
21. 21*

    Photoproduction of a large invariant mass $\gamma \rho$ pair at small momentum transfer

    R. Boussarie🇫🇷 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷

    The collinear factorization framework allows to describe the exclusive photoproduction of a $\gamma \rho$ pair in the generalized Bjorken regime in terms of a perturbatively calculable coefficient function and universal generalized parton distributions. The kinematics are defined by a large invariant mass of the $\gamma \rho$ pair and a small transverse momentum of the final nucleon. We calculate the scattering amplitude at leading order in ${\alpha }_s$ and the differential cross sections for the process where the $\rho -$meson is either longitudinally or transversely polarized, in the kinematics of the near future Jlab experiments. Our estimate of the cross section demonstrates that this process is measurable at JLab 12-GeV.

    hep-phhep-exnucl-exnucl-thPoS(2016)·0 citations
22. 22*

    Review of the electric dipole moment of light nuclei

    Nodoka Yamanaka🇯🇵

    In this review, we summarize the theoretical development on the electric dipole moment of light nuclei. We first describe the nucleon level CP violation and its parametrization. We then present the results of calculations of the EDM of light nuclei in the ab initio approach and in the cluster model. The analysis of the effect of several models beyond standard model is presented, together with the prospects for its discovery. The advantage of the electric dipole moment of light nuclei is focused in the point of view of the many-body physics. The evaluations of the nuclear electric dipole moment generated by the $\theta$-term and by the CP phase of the Cabibbo-Kobayashi-Maskawa matrix are also reviewed.

    ↳ nucl-thhep-exhep-phnucl-exIJMPE(2017)·60 citations
23. 23*

    Two-point correlators revisited: Fast and slow scales in multifield models of inflation

    José T. Gálvez Ghersi🇨🇦 · Andrei V. Frolov🇨🇦

    We study the structure of two-point correlators of the inflationary field fluctuations in order to improve the accuracy and efficiency of the existing methods to calculate primordial spectra. We present a description motivated by the separation of the fast and slow evolving components of the spectrum which is based on Cholesky decomposition of the field correlator matrix. Our purpose is to rewrite all the relevant equations of motion in terms of slowly varying quantities. This is important in order to consider the contribution from high-frequency modes to the spectrum without affecting computational performance. The slow-roll approximation is not required to reproduce the main distinctive features in the power spectrum for each specific model of inflation.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2017)·7 citations
24. 24*

    Hydrodynamization in kinetic theory: Transient modes and the gradient expansion

    Michal P. Heller🇨🇦 · Aleksi Kurkela🇨🇭 · Michal Spalinski🇵🇱 · Viktor Svensson🇵🇱

    We explore the transition to hydrodynamics in a weakly-coupled model of quark-gluon plasma given by kinetic theory in the relaxation time approximation with conformal symmetry. We demonstrate that the gradient expansion in this model has a vanishing radius of convergence due to the presence of a transient (nonhydrodynamic) mode, in a way similar to results obtained earlier in strongly-coupled gauge theories. This suggests that the mechanism by which hydrodynamic behaviour emerges is the same, which we further corroborate by a novel comparison between solutions of different weakly and strongly coupled models. However, in contrast with other known cases, we find that not all the singularities of the analytic continuation of the Borel transform of the gradient expansion correspond to transient excitations of the microscopic system: some of them reflect analytic properties of the kinetic equation when the proper time is continued to complex values.

    ↳ nucl-thhep-phhep-thphysics.flu-dynPRD(2018)·199 citations
25. 25*

    WIMP capture by the Sun in the effective theory of dark matter self-interactions

    Riccardo Catena🇸🇪 · Axel Widmark🇸🇪

    We study the capture of WIMP dark matter by the Sun in the non-relativistic effective theory of dark matter self-interactions. The aim is to assess the impact of self-interactions on the expected neutrino flux from the annihilation of WIMPs trapped in the Sun in a model independent manner. We consider all non-relativistic Galilean invariant self-interaction operators that can arise from the exchange of a heavy particle of spin less than or equal to 1 for WIMPs of spin equal to 0, 1/2 and 1. We show that for interaction operators depending at most linearly on the momentum transfer, the WIMP-induced neutrino flux can be enhanced by several orders of magnitude compared to the same flux in absence of self-interactions. This is true even for standard values of the thermally averaged annihilation cross-section. This conclusion impacts the analysis of present and future observations performed at neutrino telescopes.

    ↳ astro-ph.COhep-phJCAP(2016)·24 citations
26. 26*

    Updates to the p+p and A+A chemical freeze-out lines from the new experimental data

    V. V. Begun🇵🇱 · V. Vovchenko🇩🇪 · M. I. Gorenstein🇺🇦

    We show that the new data on mean multiplicities measured in p+p and A+A collisions together with the updated list of resonances lead to the significant changes of the obtained freeze-out lines. The new A+A line gives much smaller temperatures at high collision energies and agrees with the values obtained at the LHC. The newly obtained p+p line is much closer to the A+A line than previously expected, and even touches it in the region where the $K^{+}/{\pi }^{+}$ horn appears in the data. It indicates that the temperatures that will be obtained in the beam energy and system size scan by the NA61/SHINE Collaboration might be very close. However, our analysis shows that the chemical potentials could be very different for the same energies in A+A and p+p. It adds more puzzles to the set of surprising coincidences at the energies close to the possible onset of deconfinement.

    ↳ nucl-thhep-exhep-phnucl-exJ.Phys.Conf.Ser.(2017)·12 citations
27. 27*

    A new observable in extensive air showers

    C.A. García Canal🇦🇷 · J.I. Illana🇪🇸 · M. Masip🇪🇸 · S.J. Sciutto🇦🇷

    We find that the ratio r_{mu e} of the muon to the electromagnetic component of an extended air shower at the ground level provides an indirect measure of the depth X_{max} of the shower maximum. This result, obtained with the air-shower code AIRES, is independent of the hadronic model used in the simulation. We show that the value of r_{mu e} in a particular shower discriminates its proton or iron nature with a 98% efficiency. We also show that the eventual production of forward heavy quarks inside the shower may introduce anomalous values of r_{mu e} in isolated events.

    ↳ astro-ph.HEhep-phAstropart.Phys.(2016)·3 citations
28. 28*

    On Effective Degrees of Freedom in the Early Universe

    Lars Husdal🇳🇴

    We explore the effective degrees of freedom in the early universe, from before the electroweak scale at a few femtoseconds after the Big Bang, until the last positrons disappeared a few minutes later. We first look at the established concepts of effective degrees of freedom for energy density, pressure and entropy density, and introduce effective degrees of freedom for number density as well. We discuss what happens with particle species as their temperature cools down from relativistic to semi- and non-relativistic temperatures, and then annihilates completely. This will affect the pressure as well as the entropy per particle. We also look at the transition from a quark-gluon plasma to a hadron gas. Using a list of known hadrons, we use a "cross-over" temperature of 214 MeV where the effective degrees of freedom for a quark-gluon plasma equals that of a hadron gas.

    ↳ astro-ph.COhep-phGalaxies(2016)·306 citations
29. 29*

    The $A^2$ asymmetry and propagators in lattice $SU(2)$ gluodynamics at $T>T_c$

    V. G. Bornyakov🇷🇺 · V. K. Mitrjushkin🇷🇺 · R. N. Rogalyov🇷🇺

    We study numerically the chromoelectric-chromomagnetic asymmetry of the dimension two $A^2$ gluon condensate as well as the transverse and longitudinal gluon propagators at $T>T_c$ in the Landau-gauge $SU(2)$ lattice gauge theory with a particular emphasis on finite-volume effects. We show that previously found so called symmetric point at which asymmetry changes sign is an artifact of the finite volume effects. We find that with increasing temperature the asymmetry decreases approaching zero value from above in agreement with perturbative result. Instead of the asymmetry we suggest the ratio of the transverse to longitudinal propagator taken at zero momentum as an indicator of the boundary of the postconfinement domain and find it at $T\simeq 1.7T_c$.

    ↳ hep-lathep-phPRD(2019)·7 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.