Fri·Jul 8, 2016Friday·July 8, 2016

1. 01*

   Degeneracy between ${\theta }_{23}$ octant and neutrino non-standard interactions at DUNE

   Sanjib Kumar Agarwalla🇮🇳 · Sabya Sachi Chatterjee🇮🇳 · Antonio Palazzo🇮🇹

   We expound in detail the degeneracy between the octant of ${\theta }_{23}$ and flavor-changing neutral-current non-standard interactions (NSI's) in neutrino propagation, considering the Deep Underground Neutrino Experiment (DUNE) as a case study. In the presence of such NSI parameters involving the $e-\mu$ (${\epsilon }_{e\mu }$) and $e-\tau$ (${\epsilon }_{e\tau }$) flavors, the ${\nu }_{\mu }\to {\nu }_e$ and ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ appearance probabilities in long-baseline experiments acquire an additional interference term, which depends on one new dynamical CP-phase ${\varphi }_{e\mu /e\tau }$. This term sums up with the well-known interference term related to the standard CP-phase $\delta$ creating a source of confusion in the determination of the octant of ${\theta }_{23}$. We show that for values of the NSI coupling (taken one at-a-time) as small as $few\%$ (relative to the Fermi coupling constant $G_{\mathrm{F}}$), and for unfavorable combinations of the two CP-phases $\delta$ and ${\varphi }_{e\mu /e\tau }$, the discovery potential of the octant of ${\theta }_{23}$ gets completely lost.

   hep-phhep-exphysics.ins-detPLB(2016)·84 citations
2. 02*

   Z+jet production at NNLO

   A. Gehrmann-De Ridder🇨🇭 · T. Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · A. Huss🇨🇭 · T.A. Morgan🇬🇧

   We give a brief overview of our calculation of the next-to-next-to-leading order (NNLO) QCD corrections to Z+jet production in hadronic collisions. Phenomenological results are presented which comprise various differential distributions for 8 TeV proton-proton collisions. A significant reduction of the scale uncertainties is observed throughout as we move from NLO to NNLO. We further discuss how this calculation can be used to describe the inclusive Z-boson production at large transverse momentum. To this end, the theory prediction is compared to the measurements performed by the ATLAS and CMS collaborations at a centre-of-mass energy of 8 TeV. Here, the inclusion of NNLO QCD effects are found to result in a substantial improvement in the agreement between theory and data for the normalised distributions.

   hep-phPoS(2016)·8 citations
3. 03*

   Relaxation from particle production

   Anson Hook🇺🇸 · Gustavo Marques-Tavares🇺🇸

   We consider using particle production as a friction force by which to implement a "Relaxion" solution to the electroweak hierarchy problem. Using this approach, we are able to avoid superplanckian field excursions and avoid any conflict with the strong CP problem. The relaxation mechanism can work before, during or after inflation allowing for inflationary dynamics to play an important role or to be completely decoupled.

   hep-phJHEP(2016)·115 citations
4. 04*

   Probing sub-GeV Dark Matter with conventional detectors

   Chris Kouvaris🇩🇰 · Josef Pradler🇦🇹

   The direct detection of Dark Matter particles with mass below the GeV-scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic Dark Matter nucleus scattering sets a principal limit on detectability. Here we propose to bypass the kinematic limitations by considering the inelastic channel of photon emission in the nuclear recoil. Our proposed method allows to set the first limits on Dark Matter below 500 MeV in the plane of Dark Matter mass and cross section with nucleons. In situations where a Dark Matter-electron coupling is suppressed, Bremsstrahlung may constitute the only path to probe low-mass Dark Matter awaiting new detector technologies with lowered recoil energy thresholds.

   hep-phPRL(2017)·191 citations
5. 05*

   Dark matter and observable Lepton Flavour Violation

   Lucien Heurtier🇧🇪 · Daniele Teresi🇧🇪

   Seesaw models with leptonic symmetries allow right-handed (RH) neutrino masses at the electroweak scale, or even lower, at the same time having large Yukawa couplings with the Standard Model leptons, thus yielding observable effects at current or near-future lepton-flavour-violation (LFV) experiments. These models have been previously considered also in connection to low-scale leptogenesis, but the combination of observable LFV and successful leptogenesis has appeared to be difficult to achieve unless the leptonic symmetry is embedded into a larger one. In this paper, instead, we follow a different route and consider a possible connection between large LFV rates and Dark Matter (DM). We present a model in which the same leptonic symmetry responsible for the large Yukawa couplings guarantees the stability of the DM candidate, identified as the lightest of the RH neutrinos. The spontaneous breaking of this symmetry, caused by a Majoron-like field, also provides a mechanism to produce the observed relic density via the decays of the latter. The phenomenological implications of the model are discussed, finding that large LFV rates, observable in the near-future $\mu \to e$ conversion experiments, require the DM mass to be in the keV range. Moreover, the active-neutrino coupling to the Majoron-like scalar field could be probed in future detections of supernova neutrino bursts.

   hep-phastro-ph.COPRD(2016)·20 citations
6. 06*

   Physics at a 100 TeV pp collider: Standard Model processes

   M.L. Mangano🇨🇭 · G. Zanderighi🇨🇭 · J.A. Aguilar Saavedra🇪🇸 · S. Alekhin🇩🇪 · S. Badger🇬🇧 · C.W. Bauer🇺🇸 · T. Becher🇨🇭 · V. Bertone🇬🇧 · M. Bonvini🇬🇧 · S. Boselli🇮🇹 · E. Bothmann🇩🇪 · R. Boughezal🇺🇸 and 64 other authors

   This report summarises the properties of Standard Model processes at the 100 TeV pp collider. We document the production rates and typical distributions for a number of benchmark Standard Model processes, and discuss new dynamical phenomena arising at the highest energies available at this collider. We discuss the intrinsic physics interest in the measurement of these Standard Model processes, as well as their role as backgrounds for New Physics searches.

   hep-phhep-exCERN Yellow Rep.(2017)·209 citations
7. 07*

   Spin polarization in high density quark matter under a strong external magnetic field

   Yasuhiko Tsue (Univ. de Coimbra, Portugal and Kochi Univ., Japan)🇯🇵 · Joao da Providencia (Univ. de Coimbra, Portugal)🇵🇹 · Constanca Providencia (Univ. de Coimbra, Portugal)🇵🇹 · Masatoshi Yamamura (Univ. de Coimbra, Portugal and Kansai Univ., Japan)🇯🇵 · Henrik Bohr (Danish Technical Univ., Denmark)🇩🇰

   In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interaction under the strong external magnetic field, it is shown that a quark spin polarized phase is realized in all regions of the quark chemical potential under consideration within the lowest Landau level approximation. In the axial-vector-type interaction, it is also shown that the quark spin polarized phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs.

   hep-phIJMPE(2016)·8 citations
8. 08*

   Resonance decay effect on conserved number fluctuations in a hadron resonance gas model

   D. K. Mishra🇮🇳 · P. Garg🇺🇸 · P. K. Netrakanti🇮🇳 · A. K. Mohanty🇮🇳

   We study the effect of charged secondaries coming from resonance decay on the net-baryon, net-charge and net-strangeness fluctuations in high energy heavy-ion collisions within the hadron resonance gas (HRG) model. We emphasize the importance of including weak decays along with other resonance decays in the HRG, while comparing with the experimental observables. The effect of kinematic cuts on resonances and primordial particles on the conserved number fluctuations are also studied. The HRG model calculations with the inclusion of resonance decays and kinematical cuts are compared with the recent experimental data from STAR and PHENIX experiments. We find a good agreement between our model calculations and the experimental measurements for both net-proton and net-charge distributions.

   hep-phnucl-exnucl-thPRC(2016)·31 citations
9. 09*

   Generalized weak-binding relations of compositeness in effective field theory

   Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵

   We study the compositeness of near-threshold states to investigate the internal structure of exotic hadron candidates. Within the framework of effective field theory, Weinberg's weak-binding relation is extended to more general cases by easing several preconditions. First, by evaluating the contribution from the decay channel, we obtain the generalized relation for unstable quasibound states. Next, we generalize the relation to include the nearby CDD (Castillejo-Dalitz-Dyson) pole contribution with the help of the Pade approximant. The validity of the estimation with the generalized weak-binding relations is examined by numerical calculations. The method to systematically evaluate the error in the weak-binding relation is presented. Finally, by applying the extended relation to Lambda(1405), f0(980) and a0(980), we discuss their internal structure, in comparison with other approaches.

   hep-phnucl-thPTEP(2017)·54 citations
10. 10*

    Neutrino Mass Generation and 750 GeV Diphoton excess via photon-photon fusion at the Large Hadron Collider

    Kirtiman Ghosh🇮🇳 · Sudip Jana🇺🇸 · S. Nandi🇺🇸

    We propose a new model for explaining the diphoton excess observed at the LHC. The uniqueness of our model is that this excess is being produced by photon-photon induced sub-process. The model includes an isospin $3/2$ scalar multiplet (having triply, doubly and singly charged scalars) at the electroweak (EW) scale to explain the observed neutrino masses via the effective dimension $7$ operator. The model also include a singlet scalar which is the di-photon resonance. The loop induced coupling of the singlet scalar with a pair of photons is enhanced due to contributions from multi-charged EW-scale scalars (component of isospin $3/2$ multiplet) in the loop. We examine the production of the singlet scalar at the LHC via photon-photon fusion sub-process and its subsequent decay to di-photon. We found that a large part of parameter space of the present model can explain the observed excess of di-photon events at the LHC. We also study the other decay modes of the singlet scalar and the ensuing predictions can be tested in the upcoming runs at the LHC.

    hep-ph13 citations
11. 11*

    Erratum for "Axion Dark Matter Coupling to Resonant Photons via Magnetic Field" [arXiv:1512.05547]

    Ben T. McAllister🇦🇺 · Stephen R. Parker🇦🇺 · Michael E. Tobar🇦🇺

    A recent comment highlights a discussion at the PATRAS Workshop on Axions, WIMPs and WISPs relating to a recent publication. We respond to this comment, and detail a calculation error in the original letter.

    hep-phPRL(2016)·39 citations
12. 12*

    Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions

    Lin Chen🇨🇳 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇨🇳 · Bo-Wen Xiao🇨🇳 · Han-Zhong Zhang🇨🇳

    Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in $pp$ and peripheral $AA$ collisions where the medium effect is negligible. We demonstrate that the medium-induced broadening $⟨p_{\perp }^2⟩$ and the so-called jet quenching parameter $\hat{q}$ can be extracted from the angular de-correlations observed in $AA$ collisions. A global ${\chi }^2$ analysis of dihadron and hadron-jet angular correlation data renders the best fit $⟨p_{\perp }^2⟩\sim 13{\text{GeV}}^2$ for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.

    hep-phnucl-exnucl-thPLB(2017)·91 citations
13. 13*

    Bounds on the Conformal Scale of a Minimally Coupled Dilaton and Multi-Leptonic Signatures at the LHC

    Priyotosh Bandyopadhyay🇮🇹 · Claudio Coriano🇮🇹 · Antonio Costantini🇮🇹 · Luigi Delle Rose🇬🇧

    We explore the potential for the discovery of a dilaton $\mathcal{O}(200-500)$ GeV in a classical scale/conformal invariant extension of the Standard Model by investigating the size of the corresponding breaking scale $\Lambda$ at the LHC, extending a previous analysis. In particular, we address the recent bounds on $\Lambda$ derived from Higgs boson searches. We investigate if such a dilaton can be produced via gluon-gluon fusion, presenting rates for its decay either into a pair of Higgs bosons or into two heavy gauge bosons, which can give rise to multi-leptonic final states. A detailed analysis via PYTHIA-FastJet has been carried out of the dominant Standard Model backgrounds, at a centre of mass energy of 14 TeV. We show that early data of $\sim 20$ fb${}^{-1}$ can certainly probe the region of parameter space where such a dilaton is allowed. A conformal scale of 5 TeV is allowed by the current data, for almost all values of the dilaton mass investigated.

    hep-phJHEP(2016)·7 citations
14. 14*

    Cracking Down on Fake Photons - A Case of 750 GeV Diphoton Resonance -

    Hajime Fukuda🇯🇵 · Masahiro Ibe🇯🇵 · Osamu Jinnouchi🇯🇵 · Mihoko Nojiri🇯🇵

    Among various models to explain the $750$ GeV diphoton resonance hinted at the LHC Run 2, a class of models where the resonance decays not into a pair of photons but into a pair of photon-jets is gathering definite attention. In this paper, we study how well we can distinguish the di-photon-jet resonance from the diphoton resonance by examining detector responses to the photon-jets. We find that the sum of $p_T$ of the first $e^{+}{e}^{-}$ pair from the photon conversion provides strong discrimination power. We also discuss determination of the lifetime of the light intermediate particle by measuring the photon conversion points.

    hep-phhep-exPTEP(2017)·8 citations
15. 15*

    Geometry and space-time extent of pion emission region at FCC energies

    V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺

    The energy dependence is investigated for a wide set of space-time characteristics derived from Bose - Einstein correlations of secondary pion pairs produced in proton-proton and nucleus-nucleus interactions. Analytic functions suggested for smooth approximations of the energy dependence of emission region parameters demonstrate reasonable agreement with all available experimental results for proton-proton collisions while the approximations correspond to most of experimental data for nucleus-nucleus collisions at energies above 5 GeV. Estimations for a wide set of space-time quantities are obtained for energies for the Future Circular Collider (FCC) project based on the smooth approximations. The space particle densities at freeze-out are derived also from estimations for the volume of the emission region and for total multiplicity at FCC energies. Estimations for charged particle density and its critical value allow the possibility of lasing behavior for secondary pions in nucleus-nucleus collisions at FCC energy. The mathematical formalism is presented for study of the peak shape of correlation function for general case of central-symmetrical Levy - Feldheim distribution.

    hep-phhep-exAdv.High Energy Phys.(2016)·8 citations
16. 16*

    Higgs boson mass from gauge invariant operators

    Renata Jora🇷🇴

    We make the assumption that the vacuum correlators of the gauge invariant kinetic term of the Higgs doublet are the same before and after the spontaneous symmetry breaking of the theory. Based on this we determine the mass of the standard model Higgs boson at $m_h\approx 125.07$ GeV by considering one loop and the most relevant two loop corrections. This result might suggest that there is a single Higgs boson doublet that contributes to the electroweak symmetry breaking.

    hep-ph0 citations
17. 17*

    Recent development in parton shower multijet merging

    Johannes Bellm🇬🇧

    Higher order calculations are necessary to predict and describe measurements in high energy collider physics. In recent years multiple approaches to combine multiple next-to-leading (NLO) order corrections with parton showers had been presented. We present on recent developments and future perspective. We highlight similarities and ambiguities in the procedure of achieving a multijet merging at NLO.

    hep-phPoS(2016)·0 citations
18. 18*

    On semi-exclusive measurement of $\gamma \gamma \to \gamma \gamma$ scattering

    Rafał Staszewski🇵🇱 · Janusz J. Chwastowski🇵🇱

    The two-photon production of photon pairs, i.e. the $\gamma \gamma \to \gamma \gamma$ process, is studied. Different production modes regarding the elastic or inelastic coupling of the intermediate-state photons to the protons are considered. The semi-exclusive measurement, where one intact proton is registered by a dedicated forward proton detector, is discussed. As an example, the signal and background simulations are performed for the $\gamma \gamma \to \gamma \gamma$ process mediated by the hypothetical 750 GeV resonance.

    hep-phhep-ex0 citations
19. 19*

    Universal scaling of gluon and ghost propagators in the infrared

    Fabio Siringo🇮🇹

    A universal behavior is predicted for ghost and gluon propagators in the infrared. The universal behavior is shown to be a signature of a one-loop approximation and emerges naturally by the massive expansion that predicts universal analytical functions for the inverse dressing functions that do not depend on any parameter or color number. By a scaling of units and by adding an integration constant, all lattice data, for different color numbers (and even quark content for the ghosts), collapse on the same universal curves predicted by the massive expansion.

    hep-phhep-lathep-thEPJ Web Conf.(2017)·17 citations
20. 20*

    Tests of quark-hadron duality in tau-decays

    C. A. Dominguez🇿🇦 · L. A. Hernandez🇿🇦 · K. Schilcher🇿🇦 · H. Spiesberger🇩🇪

    An exhaustive number of QCD finite energy sum rules for $\tau$-decay together with the latest updated ALEPH data is used to test the assumption of global duality. Typical checks are the absence of the dimension $d=2$ condensate, the equality of the gluon condensate extracted from vector or axial vector spectral functions, the Weinberg sum rules, the chiral condensates of dimensions $d=6$ and $d=8$, as well as the extraction of some low-energy parameters of chiral perturbation theory. Suitable pinched linear integration kernels are introduced in the sum rules in order to suppress potential quark-hadron duality violations and experimental errors. We find no compelling indications of duality violations in hadronic $\tau$-decay in the kinematic region above $s\simeq 2.2$ GeV${}^2$ for these kernels.

    hep-phhep-exhep-latMod.Phys.Lett.A(2016)·4 citations
21. 21*

    Scalar versus fermionic top partner interpretations of $t\bar{t}+E_T^{\mathrm{miss}}$ searches at the LHC

    Sabine Kraml🇫🇷 · Ursula Laa🇫🇷 · Luca Panizzi🇬🇧 · Hugo Prager🇬🇧

    We assess how different ATLAS and CMS searches for supersymmetry in the $t\bar{t}+E_T^{\mathrm{miss}}$ final state at Run 1 of the LHC constrain scenarios with a fermionic top partner and a dark matter candidate. We find that the efficiencies of these searches in all-hadronic, 1-lepton and 2-lepton channels are quite similar for scalar and fermionic top partners. Therefore, in general, efficiency maps for stop-neutralino simplified models can also be applied to fermionic top-partner models, provided the narrow width approximation holds in the latter. Owing to the much higher production cross-sections of heavy top quarks as compared to stops, masses up to $m_T\approx 850$ GeV can be excluded from the Run 1 stop searches. Since the simplified-model results published by ATLAS and CMS do not extend to such high masses, we provide our own efficiency maps obtained with CheckMATE and MadAnalysis 5 for these searches. Finally, we also discuss how generic gluino/squark searches in multi-jet final states constrain heavy top partner production.

    hep-phhep-exJHEP(2016)·41 citations
22. 22*

    On the structure observed in the in-flight ${}^3\text{He}(K^{-},\Lambda p)n$ reaction at J-PARC

    Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. amd Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U. and ICC, Barcelona U.)🇪🇸

    A theoretical investigation is done to clarify the origin of the peak structure observed near the $K^{-}pp$ threshold in the in-flight ${}^3\text{He}(K^{-},\Lambda p)n$ reaction of the J-PARC E15 experiment, which could be a signal of the lightest kaonic nuclei, that is, the $\bar{K}NN(I=1/2)$ state. For the investigation, we evaluate the $\Lambda p$ invariant mass spectrum assuming two possible scenarios to interpret the experimental peak. One assumes that the $\Lambda (1405)$ resonance is generated after the emission of an energetic neutron from the absorption of the initial $K^{-}$, not forming a bound state with the remaining proton. This uncorrelated $\Lambda (1405)p$ system subsequently decays into the final $\Lambda p$. The other scenario implies that, after the emission of the energetic neutron, a $\bar{K}NN$ bound state is formed, decaying eventually into a $\Lambda p$ pair. Our results show that the experimental signal observed in the in-flight ${}^3\text{He}(K^{-},\Lambda p)n$ reaction at J-PARC is qualitatively well reproduced by the assumption that a $\bar{K}NN$ bound state is generated in the reaction, definitely discarding the interpretation in terms of an uncorrelated $\Lambda (1405)p$ state.

    hep-phnucl-exnucl-thPTEP(2016)·59 citations
23. 23*

    Testing the running coupling $k_T$-factorization formula for the inclusive gluon production

    F.O. Durães🇧🇷 · A.V. Giannini🇧🇷 · V.P. Goncalves🇧🇷 · F.S. Navarra🇧🇷

    The inclusive gluon production at midrapidities is described in the Color Glass Condensate formalism using the $k_T$ - factorization formula, which was derived at fixed coupling constant considering the scattering of a dilute system of partons with a dense one. Recent analysis demonstrated that this approach provides a satisfactory description of the experimental data for the inclusive hadron production in $pp/pA/AA$ collisions. However, these studies are based on the fixed coupling $k_T$ - factorization formula, which does not take into account the running coupling corrections, which are important to set the scales present in the cross section. In this paper we consider the running coupling corrected $k_T$ - factorization formula conjectured some years ago and investigate the impact of the running coupling corrections on the observables. In particular, the pseudorapidity distributions and charged hadrons multiplicity are calculated considering $pp$, $dAu/pPb$ and $AuAu/PbPb$ collisions at RHIC and LHC energies. We compare the corrected running coupling predictions with those obtained using the original $k_T$ - factorization assuming a fixed coupling or a prescription for the inclusion of the running of the coupling. Considering the Kharzeev - Levin - Nardi unintegrated gluon distribution and a simplified model for the nuclear geometry, we demonstrate that the distinct predictions are similar for the pseudorapidity distributions in $pp/pA/AA$ collisions and for the charged hadrons multiplicity in $pp/pA$ collisions. On the other hand, the running coupling corrected $k_T$ - factorization formula predicts a smoother energy dependence for $dN/d\eta$ in $AA$ collisions.

    hep-phhep-exnucl-exnucl-thPRD(2016)·17 citations
24. 24*

    Changes in extensive air showers from isotropic Lorentz violation in the photon sector

    J.S. Diaz🇩🇪 · F.R. Klinkhamer🇩🇪 · M. Risse🇩🇪

    We consider a theory with isotropic nonbirefringent Lorentz violation in the photon sector and explore the effects on the development of the electromagnetic component of extensive air showers in the Earth atmosphere. Specifically, we consider the case of a "fast" photon with a phase velocity larger than the maximum attainable velocity of a massive Dirac fermion (this case corresponds to a negative Lorentz-violating parameter $\kappa$ in the action). Shower photons with above-threshold energies decay promptly into electron-positron pairs, instead of decaying by the conventional production of electron-positron pairs in the background fields of atomic nuclei. This rapid production of charged leptons accelerates the shower development, decreasing the atmospheric depth of the shower maximum ($X_{\text{max}}$) by an amount which could be measured by cosmic-ray observatories. Precise measurements of $X_{\text{max}}$ could then improve existing limits on the negative Lorentz-violating parameter $\kappa$ by several orders of magnitude.

    hep-phastro-ph.HEPRD(2016)·28 citations
25. 25*

    Looking for bound states and resonances in the ${\eta }^{\prime }K\bar{K}$ system

    A. Martínez Torres🇧🇷 · K. P. Khemchandani🇧🇷

    Motivated by the continuous experimental investigations of $X(1835)$ in three-body decay channels like ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$, we investigate the ${\eta }^{\prime }K\bar{K}$ system with the aim of searching for bound states and/or resonances when the dynamics involved in the $K\bar{K}$ subsystem can form the resonances: $f_0(980)$ in isospin 0 or $a_0(980)$ in isospin 1. For this, we solve the Faddeev equations for the three-body system. The input two-body $t$-matrices are obtained by solving Bethe-Salpeter equations in a coupled channel formalism. As a result, no signal of a three-body bound state or resonance is found.

    hep-phnucl-thPRD(2016)·4 citations
26. 26*

    Hydrodynamic flow amplitude correlations in event-by-event fluctuating heavy-ion collisions

    Jing Qian🇨🇳 · Ulrich Heinz🇺🇸

    The effects of event-by-event fluctuations in the initial geometry of the colliding nuclei are important in the analysis of final flow observables in relativistic heavy-ion collisions. We use hydrodynamic simulations to study the amplitude correlations between different orders of event-by-event fluctuating anisotropic flow harmonics. While the general trends seen in the experimental data are qualitatively reproduced by the model, deviations in detail, in particular for peripheral collisions, point to the need for more elaborate future calculations with a hybrid approach that describes the late hadronic stage of the evolution microscopically. It is demonstrated explicitly that the observed anti-correlation between $v_2$ and $v_3$ is the consequence of approximately linear hydrodynamic response to a similar anti-correlation of the corresponding initial eccentricities ${ϵ}_2$ and ${ϵ}_3$. For $n>3$, the hydrodynamic correlations between $v_{2,3}$ and $v_n$ deviate from the rescaled correlations among the corresponding initial eccentricities, demonstrating nonlinear mode coupling effect in higher order flows.

    ↳ nucl-thhep-phnucl-exPRC(2016)·39 citations
27. 27*

    Belle II early physics program of bottomonium spectroscopy

    Hua Ye🇩🇪

    The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK "$B$ factory" facility in Tsukuba, Japan. Phase 1 commissioning of the main ring of SuperKEKB has started in February 2016 and first physics data will be recorded in 2017 during the so-called Phase 2 commissioning, when the partial Belle II detector will be operated still without its vertex detector. In 2018, the full Belle II detector will be rolled in and physics run will start. In this proceeding, a possible physics program for this early data run at different center-of-mass energies is described, in particular at the ${\rm Y}(3S)$ and ${\rm Y}(6S)$ resonances, amongst other energy points.

    ↳ hep-exhep-phPoS(2016)·2 citations
28. 28*

    Super no-scale models in string theory

    Costas Kounnas🇫🇷 · Herve Partouche🇫🇷

    We consider "super no-scale models" in the framework of the heterotic string, where the N=4,2,1 --> 0 spontaneous breaking of supersymmetry is induced by geometrical fluxes realizing a stringy Scherk-Schwarz perturbative mechanism. Classically, these backgrounds are characterized by a boson/fermion degeneracy at the massless level, even if supersymmetry is broken. At the 1-loop level, the vacuum energy is exponentially suppressed, provided the supersymmetry breaking scale is small, m_{3/2} << M_{string}. We show that the "super no-scale string models" under consideration are free of Hagedorn-like tachyonic singularities, even when the supersymmetry breaking scale is large, m_{3/2} ~ M_{string}. The vacuum energy decreases monotonically and converges exponentially to zero, when m_{3/2} varies from M_{string} to 0. We also show that all Wilson lines associated to asymptotically free gauge symmetries are dynamically stabilized by the 1-loop effective potential, while those corresponding to non-asymtotically free gauge groups lead to instabilities and condense. The Wilson lines of the conformal gauge symmetries remain massless. When stable, the stringy super no-scale models admit low energy effective actions, where decoupling gravity yields theories in flat spacetime, with softly broken supersymmetry.

    ↳ hep-thgr-qchep-phNPB(2016)·69 citations
29. 29*

    Plus Charge Prevalence in Cosmic Rays: Room for Dark Matter in the Positron Spectrum

    M.A. Malkov🇺🇸 · P.H. Diamond🇺🇸 · R.Z. Sagdeev🇺🇸

    The unexpected energy spectrum of the positron/electron ratio is interpreted astrophysically, with a possible exception of the 100-300 GeV range. The data indicate that this ratio, after a decline between $0.5-8$ GeV, rises steadily with a trend towards saturation at 200-400GeV. These observations (except for the trend) appear to be in conflict with the diffusive shock acceleration (DSA) mechanism, operating in a \emph{single} supernova remnant (SNR) shock. We argue that $e^{+}/e^{-}$ ratio can still be explained by the DSA if positrons are accelerated in a \emph{subset} of SNR shocks which: (i) propagate in clumpy gas media, and (ii) are modified by accelerated CR \emph{protons}. The protons penetrate into the dense gas clumps upstream to produce positrons and, \emph{charge the clumps positively}. The induced electric field expels positrons into the upstream plasma where they are shock-accelerated. Since the shock is modified, these positrons develop a harder spectrum than that of the CR electrons accelerated in other SNRs. Mixing these populations explains the increase in the $e^{+}/e^{-}$ ratio at $E>8$ GeV. It decreases at $E<8$ GeV because of a subshock weakening which also results from the shock modification. Contrary to the expelled positrons, most of the antiprotons, electrons, and heavier nuclei, are left unaccelerated inside the clumps. Scenarios for the 100-300 GeV AMS-02 fraction exceeding the model prediction, including, but not limited to, possible dark matter contribution, are also discussed.

    ↳ astro-ph.HEhep-phPRD(2016)·19 citations
30. 30*

    Oscillating Chiral Tensor Spectrum from Axionic Inflation

    Ippei Obata🇯🇵 · Jiro Soda🇯🇵

    We study the axionic inflation with a modulated potential and examine if the primordial tensor power spectrum exhibits oscillatory feature, which is testable with future space-based gravitational wave experiments such as DECIGO and BBO. In the case of the single-field axion monodromy inflation, it turns out that it is difficult to detect the oscillation in the spectrum due to suppression of the sub-Planckian decay constant of axion. On the other hand, in the case of aligned chromo-natural inflation where the axion is coupled to a SU(2) gauge field, it turns out that the sizable oscillation in the tensor spectrum can occur due to the enhancement of chiral gravitational waves sourced by the gauge field. We expect that this feature will be a new probe to axion phenomenologies in early universe through the chiral gravitational waves.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2016)·50 citations
31. 31*

    Warped extra dimension and inclined events at Pierre Auger Observatory

    A.V. Kisselev🇷🇺 · L.A. Shkalina🇷🇺

    The generalized solution for the warp factor of the Randall-Sundrum metric is presented which is symmetric with respect to both branes and explicitly periodic in extra variable. Given that the curvature of the 5-dimensional space-time is small, the expected rate of neutrino-induced inclined events at the Surface Detector of the Pierre Auger Observatory is calculated. Both the "downward-going" (DG) and "Earth-skimming" (ES) neutrinos are considered. By comparing the expected event rate with the recent Auger data on searching for neutrino candidates, the lower bound on the fundamental gravity scale M_5 is obtained. The ratio of the number of the ES air showers to the number of the DG showers is estimated as a function of M_5.

    ↳ astro-ph.HEhep-phEPJ Web Conf.(2016)·2 citations
32. 32*

    Systematic Comparison of Tsallis Statistics for Charged Pions Produced In $pp$ Collisions

    A.S. Parvan🇷🇺 · O.V. Teryaev🇷🇺 · J. Cleymans🇿🇦

    The energy dependence of Tsallis statistics parameters is presented for charged pions produced at beam energies ranging between 6.3 GeV and 7 TeV. It is found that deviations from Boltzmann statistics are monotonically growing with beam energy. This may be attributed to the dominance of low $x$ at higher energies leading to the power-like NLO QCD spectra for which Tsallis statistics may serve as effective theory. At the same time, for larger $x$ at lower beam energies the Gaussian falloff of transverse-momentum-dependent distributions is crucial and correspondent effective description is provided by the Boltzmann distribution.

    ↳ nucl-thhep-phEPJA(2017)·48 citations
33. 33*

    Analysis of the Very Inner Milky Way Dark Matter Distribution and Gamma-Ray Signals

    V. Gammaldi🇮🇹 · V. Avila-Reese🇲🇽 · O. Valenzuela🇲🇽 · A. X. Gonzalez-Morales🇲🇽

    We analyze the possibility that the HESS gamma-ray source at the Galactic Center could be explained as the secondary flux produced by annihilation of TeV Dark Matter (TeVDM) particles with locally enhanced density, in a region spatially compatible with the HESS observations themselves. We study the inner 100 pc considering (i) the extrapolation of several density profiles from state-of-the-art N-body + Hydrodynamics simulations of Milky Way-like galaxies, (ii) the DM spike induced by the black hole, and (iii) the DM particles scattering off by bulge stars. We show that in some cases the DM spike may provide the enhancement in the flux required to explain the cut-off in the HESS J1745-290 gamma-ray spectra as TeVDM. In other cases, it may helps to describe the spatial tail reported by HESS II at angular scales < 0.54 degrees towards Sgr A.

    ↳ astro-ph.HEastro-ph.COastro-ph.IMhep-phPRD(2016)·19 citations
34. 34*

    Critical $O(N)$ models in the complex field plane

    Daniel F. Litim🇬🇧 · Edouard Marchais🇬🇧

    Local and global scaling solutions for $O(N)$ symmetric scalar field theories are studied in the complexified field plane with the help of the renormalisation group. Using expansions of the effective action about small, large, and purely imaginary fields, we obtain and solve exact recursion relations for all couplings and determine the $3d$ Wilson-Fisher fixed point analytically. For all $O(N)$ universality classes, we further establish that Wilson-Fisher fixed point solutions display singularities in the complex field plane, which dictate the radius of convergence for real-field expansions of the effective action. At infinite $N$, we find closed expressions for the convergence-limiting singularities and prove that local expansions of the effective action are powerful enough to uniquely determine the global Wilson-Fisher fixed point for any value of the fields. Implications of our findings for interacting fixed points in more complicated theories are indicated.

    ↳ hep-thcond-mat.stat-mechhep-phPRD(2017)·38 citations
35. 35*

    A no-go theorem for the dark matter interpretation of the positron anomaly

    Maxim Laletin🇧🇪

    The overabundance of high-energy cosmic positrons, observed by PAMELA and AMS-02, can be considered as the consequence of dark matter decays or annihilations. We show that recent FERMI/LAT measurements of the isotropic diffuse gamma-ray background impose severe constraints on dark matter explanations and make them practically inconsistent.

    ↳ astro-ph.HEhep-phFrascati Phys.Ser.(2016)·7 citations
36. 36*

    Belle II studies of missing energy decays and searches for dark photon production

    Gianluca Inguglia🇩🇪

    The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK "$B$ factory" facility in Tsukuba, Japan. The machine is designed for an instantaneous luminosity of $8\times 10^{35}$~cm${}^{-2}$\,s${}^{-1}$, and the experiment is expected to accumulate a data sample of about 50 ab${}^{-1}$ well within the next decade. With this amount of data, decays sensitive to physics beyond the Standard Model can be studied with unprecedented precision. One promising set of modes are physics processes with missing energy such as $B^{+}\to {\tau }^{+}{\nu }_{\tau }$, $B\to D^{(\ast )}\tau {\nu }_{\tau }$, and $B\to K^{(\ast )}\nu \bar{\nu }$ decays. The Belle II data also allows searches for candidates for the dark photon, the gauge mediator of a hypothetical dark sector, which has received much attention in the context of dark matter models.

    ↳ hep-exhep-phPoS(2016)·12 citations
37. 37*

    Magneto-optic effects of the Cosmic Microwave Background

    Damian Ejlli🇷🇺

    Generation of magneto-optic effects by the interaction of the CMB with cosmic magnetic fields is studied. Effects which generate polarization such as the Cotton-Mouton effect, vacuum polarization and photon-pseudoscalar mixing in external magnetic field are studied. Considering the CMB linearly polarized at decoupling time, it is shown that photon-pseudoscalar mixing in external magnetic field, the Cotton-Mouton effect in plasma and the vacuum polarization in cosmic magnetic field, would generate elliptic polarization of the CMB depending on the photon frequency and magnetic field strength. Among standard magneto-optic effects, the Cotton-Mouton effect in plasma turns out to be the dominant effect in the generation of CMB elliptic polarization in the low frequency part ${\nu }_0\sim 10^8-10^9$ Hz with degree of circular polarization $P_C(T_0)\simeq 10^{-10}-10^{-6}$ for magnetic field amplitude $B_{e0}\sim 100\text{nG}-1$ nG. The vacuum polarization in magnetic field is the dominant process in the high frequency part ${\nu }_0\ge 10^{10}$ Hz where the degree of circular polarization at present is $P_C(T_0)\lesssim 10^{-11}$ in the best scenario. It is shown that photon-pseudoscalar particle mixing in cosmic magnetic field generates elliptic polarization of the CMB as well and even in the case of initially unpolarized CMB. New limits/constraints on the pseudoscalar parameter space are found. By using current limit on the degree of circular polarization of the CMB, the upper limit of $|g_{\varphi \gamma }|<4.29\times 10^{-19}(\text{G}/B_{e0})$ GeV${}^{-1}$ for $m_{\varphi }<1.6\times 10^{-14}$ eV in the weak mixing case is found. If $|g_{\varphi \gamma }|<1.17\times 10^{-24}(\text{G}/B_{e0})$ GeV${}^{-1}$, a value of the order $|g_{\varphi \gamma }|\simeq 10^{-26}(\text{G}/B_{e0})$ GeV${}^{-1}$ for $m_{\varphi }\simeq 1.6\times 10^{-14}$ eV in the resonant case, from large scale temperature anisotropy is obtained.

    ↳ astro-ph.COgr-qchep-phquant-phNPB(2018)·23 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.