Wed·Jul 29, 2015Wednesday·July 29, 2015

1. 01*

   Electroweak relaxation from finite temperature

   Edward Hardy🇮🇹

   We study theories which naturally select a vacuum with parametrically small Electroweak Scale due to finite temperature effects in the early universe. In particular, there is a scalar with an approximate shift symmetry broken by a technically natural small coupling to the Higgs, and a temperature dependent potential. As the temperature of the universe drops, the scalar follows the minimum of its potential altering the Higgs mass squared parameter. The scalar also has a periodic potential with amplitude proportional to the Higgs expectation value, which traps it in a vacuum with a small Electroweak Scale. The required temperature dependence of the potential can occur through strong coupling effects in a hidden sector that are suppressed at high temperatures. Alternatively, it can be generated perturbatively from a one-loop thermal potential. In both cases, for the scalar to be displaced, a hidden sector must be reheated to temperatures significantly higher than the visible sector. However this does not violate observational constraints provided the hidden sector energy density is transferred to the visible sector without disrupting big bang nucleosynthesis. We also study how the mechanism can be implemented when the visible sector is completed to the Minimal Supersymmetric Standard Model at a high scale. Models with a UV cutoff of 10 TeV and no fields taking values over a range greater than 10^12 GeV are possible, although the scalar must have a range of order 10^8 times the effective decay constant in the periodic part of its potential.

   hep-phJHEP(2015)·69 citations
2. 02*

   Good NEWS for GeV Dark Matter Searches

   Stefano Profumo🇺🇸

   The proposed NEWS apparatus, a spherical detector with a small central electrode sensor operating as a proportional counter, promises to explore new swaths of the direct detection parameter space in the GeV and sub-GeV Dark Matter particle mass range by employing very light nuclear targets, such as H and He, and by taking advantage of a very low (sub-keV) energy threshold. Here we discuss and study two example classes of Dark Matter models that will be tested with NEWS: GeV-scale millicharged Dark Matter, and a GeV-Dirac Fermion Dark Matter model with a light (MeV-GeV) scalar or vector mediator, and indicate the physical regions of parameter space the experiment can probe.

   hep-phastro-ph.COastro-ph.HEPRD(2016)·24 citations
3. 03*

   Off-shell Currents and Color-Kinematics Duality

   Pierpaolo Mastrolia🇮🇹 · Amedeo Primo🇮🇹 · Ulrich Schubert🇩🇪 · William J. Torres Bobadilla🇮🇹

   We elaborate on the color-kinematics duality for off-shell diagrams in gauge theories coupled to matter, by investigating the scattering process $gg\to ss,q\bar{q},gg$, and show that the Jacobi relations for the kinematic numerators of off-shell diagrams, built with Feynman rules in axial gauge, reduce to a color-kinematics violating term due to the contributions of sub-graphs only. Such anomaly vanishes when the four particles connected by the Jacobi relation are on their mass shell with vanishing squared momenta, being either external or cut particles, where the validity of the color-kinematics duality is recovered. We discuss the role of the off-shell decomposition in the direct construction of higher-multiplicity numerators satisfying color-kinematics identity in four as well as in $d$ dimensions, for the latter employing the Four Dimensional Formalism variant of the Four Dimensional Helicity scheme. We provide explicit examples for the QCD process $gg\to q\bar{q}g$.

   hep-phhep-thPLB(2016)·30 citations
4. 04*

   Linear polarization of gluons and Higgs plus jet production at the LHC

   Cristian Pisano🇧🇪

   We show that the production of a Higgs boson in association with a jet in proton-proton collisions is sensitive to the linear polarization of gluons inside unpolarized protons. We present the analytical expressions, at leading order in perturbative QCD, for various transverse momentum dependent observables, which can be measured at the LHC. Since there are no experimental constraints on the linearly polarized gluon distribution, its effects are studied by adopting two different models. In particular, we find that the $\cos 2\varphi$ azimuthal asymmetry is a very promising observable because it could give access to the sign of this new distribution.

   hep-phPoS(2015)·0 citations
5. 05*

   On the Viability of Minimal Neutrinophilic Two-Higgs-Doublet Models

   P. A. N. Machado🇪🇸 · Y. F. Perez🇧🇷 · O. Sumensari🇫🇷 · Z. Tabrizi🇮🇷 · R. Zukanovich Funchal🇧🇷

   We study the constraints that electroweak precision data can impose, after the discovery of the Higgs boson by the LHC, on neutrinophilic two-Higgs-doublet models which comprise one extra $SU(2)\times U(1)$ doublet and a new symmetry, namely a spontaneously broken ${\mathbb{Z}}_2$ or a softly broken global $U(1)$. In these models the extra Higgs doublet, via its very small vacuum expectation value, is the sole responsible for neutrino masses. We find that the model with a ${\mathbb{Z}}_2$ symmetry is basically ruled out by electroweak precision data, even if the model is slightly extended to include extra right-handed neutrinos, due to the presence of a very light scalar. While the other model is still perfectly viable, the parameter space is considerably constrained by current data, specially by the $T$ parameter. In particular, the new charged and neutral scalars must have very similar masses.

   hep-phJHEP(2015)·39 citations
6. 06*

   Composite spin-1 resonances at the LHC

   Matthew Low🇺🇸 · Andrea Tesi🇺🇸 · Lian-Tao Wang🇺🇸

   In this paper, we discuss the signal of composite spin-1 resonances at the LHC. Motivated by the possible observation of a diboson resonance in the 8 TeV LHC data, we demonstrate that vector resonances from composite Higgs models are able to describe the data. We pay particular attention to the role played by fermion partial compositeness, which is a common feature in composite Higgs models. The parameter space that is both able to account for the diboson excess and passes electroweak precision and flavor tests is explored. Finally, we make projections for signals of such resonances at the 13 TeV run of the LHC.

   hep-phhep-exPRD(2015)·38 citations
7. 07*

   A perturbed lepton-specific two-Higgs-doublet model facing experimental hints for physics beyond the Standard Model

   Andreas Crivellin🇨🇭 · Julian Heeck🇧🇪 · Peter Stoffer🇩🇪

   The BaBar, Belle, and LHCb collaborations have reported evidence for new physics in $B\to D\tau \nu$ and $B\to D^{\ast }\tau \nu$ of approximately $3.8\sigma$. There is also the long lasting discrepancy of about $3\sigma$ in the anomalous magnetic moment of the muon, and the branching ratio for $\tau \to \mu \nu \nu$ is $1.8\sigma$ ($2.4\sigma$) above the Standard Model expectation using the HFAG (PDG) values. Furthermore, CMS found hints for a non-zero decay rate of $h\to \mu \tau$. Interestingly, all these observations can be explained by introducing new scalars. In this article we consider these processes within a lepton-specific two-Higgs doublet model (i.e. of type X) with additional non-standard Yukawa couplings. It is found that one can accommodate $\tau \to \mu \nu \nu$ with modified Higgs--$\tau$ couplings. The anomalous magnetic moment of the muon can be explained if the additional neutral CP-even Higgs $H$ is light (below 100 GeV). Also $R(D)$ and $R(D^{\ast })$ can be easily explained by additional $t$--$c$--Higgs couplings. Combining these $t$--$c$ couplings with a light $H$ the decay rate for $t\to Hc$ can be in a testable range for the LHC. Effects in $h\to \mu \tau$ are also possible, but in this case a simultaneous explanation of the anomalous magnetic moment of the muon is difficult due to the unavoidable $\tau \to \mu \gamma$ decay.

   hep-phhep-exPRL(2016)·247 citations
8. 08*

   Self-induced flavor conversion of supernova neutrinos on small scales

   Sovan Chakraborty🇩🇪 · Rasmus Sloth Hansen🇩🇰 · Ignacio Izaguirre🇩🇪 · Georg Raffelt🇩🇪

   Self-induced flavor conversion of supernova (SN) neutrinos is a generic feature of neutrino-neutrino dispersion. The corresponding run-away modes in flavor space can spontaneously break the original symmetries of the neutrino flux and in particular can spontaneously produce small-scale features as shown in recent schematic studies. However, the unavoidable "multi-angle matter effect" shifts these small-scale instabilities into regions of matter and neutrino density which are not encountered on the way out from a SN. The traditional modes which are uniform on the largest scales are most prone for instabilities and thus provide the most sensitive test for the appearance of self-induced flavor conversion. As a by-product we clarify the relation between the time evolution of an expanding neutrino gas and the radial evolution of a stationary SN neutrino flux. Our results depend on several simplifying assumptions, notably stationarity of the solution, the absence of a "backward" neutrino flux caused by residual scattering, and global spherical symmetry of emission.

   hep-phastro-ph.HEastro-ph.SRJCAP(2016)·79 citations
9. 09*

   New or $\nu$ Missing Energy? Discriminating Dark Matter from Neutrino Interactions at the LHC

   Diogo Buarque Franzosi🇩🇰 · Mads T. Frandsen🇩🇰 · Ian M. Shoemaker🇩🇰

   Missing energy signals such as monojets are a possible signature of Dark Matter (DM) at colliders. However, neutrino interactions beyond the Standard Model may also produce missing energy signals. In order to conclude that new "missing particles" are observed the hypothesis of BSM neutrino interactions must be rejected. In this paper, we first derive new limits on these Non-Standard neutrino Interactions (NSIs) from LHC monojet data. For heavy NSI mediators, these limits are much stronger than those coming from traditional low-energy $\nu$ scattering or $\nu$ oscillation experiments for some flavor structures. Monojet data alone can be used to infer the mass of the "missing particle" from the shape of the missing energy distribution. In particular, 13 TeV LHC data will have sensitivity to DM masses greater than $\sim$ 1 TeV. In addition to the monojet channel, NSI can be probed in multi-lepton searches which we find to yield stronger limits at heavy mediator masses. The sensitivity offered by these multi-lepton channels provide a method to reject or confirm the DM hypothesis in missing energy searches.

   hep-phPRD(2016)·26 citations
10. 10*

    Stable or Unstable Light Dark Matter

    Ernest Ma🇺🇸 · M. V. N. Murthy🇮🇳 · G. Rajasekaran🇮🇳

    We consider the case of light dark matter ($\sim 10$ GeV). We discuss a simple $Z_2$ model of scalar self-interacting dark matter, as well as a related model of unstable long-lived dark matter which can explain the anomalous Kolar events observed decades ago.

    hep-ph0 citations
11. 11*

    Naturalness-guided Gluino Mass Bound from the Minimal Mixed Mediation of SUSY Breaking

    Doyoun Kim🇰🇷 · Bumseok Kyae🇰🇷

    In order to significantly reduce the fine-tuning associated with the electroweak symmetry breaking in the minimal supersymmetric standard model (MSSM), we consider not only the minimal gravity mediation effects but also the minimal gauge mediation ones for a common supersymmetry breaking source at a hidden sector. In this "Minimal Mixed Mediation model," the minimal forms for the Kahler potential and the gauge kinetic function are employed at tree level. The MSSM gaugino masses are radiatively generated through the gauge mediation. Since a "focus point" of the soft Higgs mass parameter, m_{h_u}^2 appears around 3-4 TeV energy scale in this case, m_{h_u}^2 is quite insensitive to stop masses. Instead, the naturalness of the small m_{h_u}^2 is more closely associated with the gluino mass rather than the stop mass unlike the conventional scenario. As a result, even a 3-4 TeV stop mass, which is known to explain the 125 GeV Higgs mass at three-loop level, can still be compatible with the naturalness of the electroweak scale. On the other hand, the requirements of various fine-tuning measures much smaller than 100 and |\mu| < 600 GeV constrain the gluino mass to be 1.6 TeV < M_3 < 2.2 TeV, which is well-inside the discovery potential range of LHC RunII.

    hep-phPRD(2015)·3 citations
12. 12*

    Deviation of yukawa coupling and Higgs decay in gauge-Higgs Unification

    Yuki Adachi🇯🇵 · Nobuhito Maru🇯🇵

    We study the deviation of yukawa coupling in the gauge-Higgs unification scenario from the Standard Model one. Applying the obtained results to the tau and bottom yukawa couplings, we numerically calculate the signal strength of $gg\to H\to \bar{b}b,\bar{\tau }\tau$in the gauge-Higgs unification.

    hep-ph0 citations
13. 13*

    Family Gauge Boson Mass Estimated from $K^{+}\to {\pi }^{+}\nu \bar{\nu }$

    Yoshio Koide🇯🇵

    It is emphasized that a rare decay $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ becomes promising in a future search for a new particle, because the theoretical treatment is well established and the value of the branching ratio $Br(K^{+}\to {\pi }^{+}\nu \bar{\nu })$ is sensitive to a search for a new particle with a TeV scale mass. As an example, according to a U(3) family gauge boson model which predicts the lowest family gauge boson with a few TeV mass $M_{11}$, the branching ratio $Br(K^{+}\to {\pi }^{+}\nu \bar{\nu })$ is discussed. If we can obtain, in future, a slightly lower value $B{r}^{obs}\sim 0.9\times 10^{-10}$ compared with the present observed value $B{r}^{obs}=(1.7\pm 1.1)\times 10^{-10}$, we can conclude $M_{11}\sim$ a few TeV.

    hep-phPRD(2015)·0 citations
14. 14*

    Hemisphere jet mass distribution at finite $N_c$

    Yoshikazu Hagiwara🇯🇵 · Yoshitaka Hatta🇯🇵 · Takahiro Ueda🇳🇱

    We perform the leading logarithmic resummation of nonglobal logarithms for the single-hemisphere jet mass distribution in $e^{+}{e}^{-}$ annihilation including the finite-$N_c$ corrections. The result is compared with the previous all-order result in the large-$N_c$ limit as well as fixed-order perturbative calculations.

    hep-phPLB(2016)·47 citations
15. 15*

    Pentaquarks and resonances in the $pJ/\psi$ spectrum

    V.V. Anisovich🇷🇺 · M.A. Matveev🇷🇺 · J. Nyiri🇭🇺 · A.V. Sarantsev🇩🇪 · A.N. Semenova🇷🇺

    We consider exotic baryons with hidden charm as antiquark-diquark-diquark composite systems. Spin and isospin structure of such exotic states is given and masses are estimated. The data for production of pentaquarks in the reaction ${\Lambda }_b\to K^{-}pJ/\psi$ are discussed. We suggest that the narrow peak in $pJ/\psi$ spectra at 4450 MeV is antiquark-diquark-diquark state with negative parity, $5/2^{-}(4450)$, while the broad bump $3/2^{+}(4380)$ is the result of rescatterings in the ($pJ/\psi$)-channel. Positions of other pentaquarks with negative parity are estimated.

    hep-ph134 citations
16. 16*

    Chiral Dynamics and S-wave contributions in Semileptonic $D_s/B_s$ decays into ${\pi }^{+}{\pi }^{-}$

    Yu-Ji Shi🇨🇳 · Wei Wang🇨🇳

    In this work, we study the semileptonic decay modes $B_s^0\to {\pi }^{+}{\pi }^{-}{\ell }^{+}{\ell }^{-}$ and $D_s^{+}\to {\pi }^{+}{\pi }^{-}{\ell }^{+}\nu$ in the kinematics region where the ${\pi }^{+}{\pi }^{-}$ system has a invariant mass in the range $0.5$-$1.3$ GeV. These processes are valuable towards the determination of S-wave ${\pi }^{+}{\pi }^{-}$ light-cone distribution amplitudes whose normalizations are scalar form factors. We compare the results for scalar form factors predicted in unitarized chiral perturbation theory and extracted from the data on the $B_s\to J/\psi {\pi }^{+}{\pi }^{-}$. Then the $B_s\to {\pi }^{+}{\pi }^{-}$ and $D_s\to {\pi }^{+}{\pi }^{-}$ form factors are calculated in light-cone sum rules, based on which predictions for differential decay widths are made. The results are in good agreement with the experimental data on the $B_s$ and $D_s$ decays into ${\pi }^{+}{\pi }^{-}$. More accurate measurements at BEPC, LHC and KEKB in future will be helpful to examine our formalism and constrain the input parameters more precisely.

    hep-phhep-exPRD(2015)·29 citations
17. 17*

    Revealing the jet substructure in a compressed spectrum

    Chengcheng Han🇰🇷 · Myeonghun Park🇰🇷

    The physics beyond the Standard Model with parameters of the compressed spectrum is well motivated both in a theory side and with phenomenological reasons, especially related to dark matter phenomenology. In this letter, we propose a method to tag soft final state particles from a decaying process of a new particle in this parameter space. By taking a supersymmetric gluino search as an example, we demonstrate how the Large Hadron Collider experimental collaborations can improve a sensitivity in these non-trivial search regions.

    hep-phhep-exPRD(2016)·9 citations
18. 18*

    Chiral electric field in relativistic heavy-ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider

    Yang Zhong🇨🇳 · Chun-Bin Yang🇨🇳 · Xu Cai🇨🇳 · Sheng-Qin Feng🇨🇳

    It was proposed that the electric fields may lead to chiral separation in QGP, which is called the chiral electric separation effect. The strong electromagnetic field and the QCD vacuum can both completely be produced in the off-central nuclear-nuclear collision. We used the Wood-Saxon nucleon distribution to calculate the electric field distributions of the off-central collisions. The chiral electro field spatial distribution at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) energy regions are systematically studied in this paper. Compared with magnetic field spatial distribution, electric field shows some different features in relativistic heavy-ion collisions. The dependence of the electric field produced by the thermal quark in the central position with different impact parameters on the proper time with different collision energies in the RHIC and LHC energy region are studied in this paper.

    hep-phnucl-thCPC(2016)·1 citation
19. 19*

    Gluon saturation and Feynman scaling in leading neutron production

    F. Carvalho🇧🇷 · V.P. Gonçalves🇧🇷 · D. Spiering🇧🇷 · F.S. Navarra🇧🇷

    In this paper we extend the color dipole formalism to the study of leading neutron production in $e+p\to e+n+X$ collisions at high energies and estimate the related observables, which were measured at HERA and may be analysed in future electron-proton ($ep$) colliders. In particular, we calculate the Feynman $x_F$ distribution of leading neutrons, which is expressed in terms of the pion flux and the photon-pion total cross section. In the color dipole formalism, the photon-pion cross section is described in terms of the dipole-pion scattering amplitude, which contains information about the QCD dynamics at high energies and gluon saturation effects. We consider different models for the scattering amplitude, which have been used to describe the inclusive and diffractive $ep$ HERA data. Moreover, the model dependence of our predictions with the description of the pion flux is analysed in detail. We show that the recently released H1 leading neutron spectra can be reproduced using the color dipole formalism and that these spectra could help us to observe more clearly gluon saturation effects in future $ep$ colliders.

    hep-phPLB(2016)·22 citations
20. 20*

    Holographic Oddballs

    L. Bellantuono🇮🇹 · P. Colangelo🇮🇹 · F. Giannuzzi🇮🇹

    The spectrum of the glueball with $J^{PC}=0^{--}$ is computed using different bottom-up holographic models of QCD. The results indicate a lowest-lying state lighter than in the determination by other methods, with mass $m\simeq 2.8$ GeV. The in-medium properties of this gluonium are investigated, and stability against thermal and density effects is compared to other hadronic systems. Production and decay modes are identified, useful for searching the $J^{PC}=0^{--}$ glueball.

    hep-phJHEP(2015)·23 citations
21. 21*

    Photons emerging as Goldstone bosons from spontaneous Lorentz symmetry breaking: The Abelian Nambu model

    C. A. Escobar🇲🇽 · L. F. Urrutia🇲🇽

    After imposing current conservation together with the Gauss law as initial conditions on the Abelian Nambu model, we prove that the resulting theory is equivalent to standard QED in the non-linear gauge $\left(A_{\mu }{A}^{\mu }-n^2{M}^2\right)=0$, to all orders in perturbation theory. We show this by writing both models in terms of the same variables, which produce identical Feynman rules for the interactions and propagators. A crucial point is to verify that the Faddeev-Popov ghosts arising from the gauge fixing procedure in the QED sector decouple to all orders. We verify this decoupling by following a method like that employed in Yang-Mills theories when investigating the behavior of axial gauges. The equivalence between the two theories supports the idea that gauge particles can be envisaged as the Goldstone bosons originating from spontaneous Lorentz symmetry breaking.

    hep-phhep-thPRD(2015)·19 citations
22. 22*

    Critical Schwinger pair production

    Holger Gies🇩🇪 · Greger Torgrimsson🇸🇪

    We investigate Schwinger pair production in spatially inhomogeneous electric backgrounds. A critical point for the onset of pair production can be approached by fields that marginally provide sufficient electrostatic energy for an off-shell long-range electron-positron fluctuation to become a real pair. Close to this critical point, we observe features of universality which are analogous to continuous phase transitions in critical phenomena with the pair-production rate serving as an order parameter: electric backgrounds can be subdivided into universality classes and the onset of pair production exhibits characteristic scaling laws. An appropriate design of the electric background field can interpolate between power-law scaling, essential BKT-type scaling and a power-law scaling with log corrections. The corresponding critical exponents only depend on the large-scale features of the electric background, whereas the microscopic details of the background play the role of irrelevant perturbations not affecting criticality.

    hep-phcond-mat.stat-mechhep-thPRL(2016)·52 citations
23. 23*

    Analytic solution of the Boltzmann equation in an expanding system

    D. Bazow (Ohio State U.)🇺🇸 · G. S. Denicol (Brookhaven & McGill U.)🇨🇦 · U. Heinz (Ohio State U.)🇺🇸 · M. Martinez (Ohio State U.)🇺🇸 · J. Noronha (Sao Paulo U. & Columbia U.)🇧🇷

    For a massless gas with constant cross section in a homogeneous, isotropically expanding spacetime we reformulate the relativistic Boltzmann equation as a set of non-linear coupled moment equations. For a particular initial condition this set can be solved exactly, yielding the first analytical solution of the Boltzmann equation for an expanding system. The non-equilibrium behavior of this relativistic gas can be mapped onto that of a homogeneous, static non-relativistic gas of Maxwell molecules.

    hep-phgr-qchep-thnucl-th+1PRL(2016)·73 citations
24. 24*

    Regions of Applicability of Approximate Formulations of Neutrino Oscillations in Matter

    Mikkel B. Johnson🇺🇸 · Ernest M. Henley🇺🇸 · Leonard S. Kisslinger🇺🇸

    We examine the reliability of the theoretical methods presently used for analysis and prediction of neutrino oscillation phenomena. Of particular interest are the limitations imposed by branch points when expansions in one of the small parameters of the Standard Neutrino Model (SNM) are made to obtain tractable results. Our evaluation compares the approximate oscillation probabilities for flavor-changing transitions in the $({\nu }_e,{\nu }_{\mu })$ sector to exact results obtained from of a recently-developed exact analytical representation of neutrino oscillations in matter within the SNM. From our numerical comparisons, we are able to identify regions where the existing approaches can be improved to take full advantage of the higher quality data expected at future neutrino facilities.

    hep-ph2 citations
25. 25*

    Three-photon-annihilation contributions to positronium energies at order $m{\alpha }^7$

    Gregory S. Adkins🇺🇸 · Minji Kim🇺🇸 · Christian Parsons🇺🇸 · Richard N. Fell🇺🇸

    Positronium spectroscopy (n=1 hyperfine splitting, n=2 fine structure, and the 1S-2S interval) has reached a precision of order 1 MHz. Vigorous ongoing efforts to improve the experimental results motivate the calculation of the positronium energy levels at order $m{\alpha }^7$. In this work we present the result for a complete class of such contributions--those involving virtual annihilation of positronium to three photons in an intermediate state. We find an energy shift of $2.6216(11)m{\alpha }^7/(n\pi {)}^3$ for the spin-triplet S state with principal quantum number n.

    hep-phPRL(2015)·34 citations
26. 26*

    Single and double diffractive dissociation and the problem of extraction of the proton-Pomeron cross-section

    V.A. Petrov🇷🇺 · R.A. Ryutin🇷🇺

    Diffractive dissociation processes are analysed in the framework of covariant reggeization. We have considered the general form of hadronic tensor and its asymptotic behaviour for $t\to 0$ in the case of conserved tensor currents before reggeization. Resulting expressions for differential cross-section of single dissociation (SD) process ($pp\to pM$), double dissociation (DD) ($pp\to M_1{M}_2$) and for the proton-Pomeron cross-section are given in detail, and corresponding problems of the approach are discussed.

    hep-phhep-thstat.APInt.J.Mod.Phys.A(2016)·6 citations
27. 27*

    The QCD phase diagram from analytic continuation

    R. Bellwied🇺🇸 · S. Borsanyi🇩🇪 · Z. Fodor🇩🇪 · J. Günther🇩🇪 · S. D. Katz🇭🇺 · C. Ratti🇺🇸 · K. K. Szabo🇩🇪

    We present the crossover line between the quark gluon plasma and the hadron gas phases for small real chemical potentials. First we determine the effect of imaginary values of the chemical potential on the transition temperature using lattice QCD simulations. Then we use various formulas to perform an analytic continuation to real values of the baryo-chemical potential. Our data set maintains strangeness neutrality to match the conditions of heavy ion physics. The systematic errors are under control up to ${\mu }_B\approx 300$ MeV. For the curvature of the transition line we find that there is an approximate agreement between values from three different observables: the chiral susceptibility, chiral condensate and strange quark susceptibility. The continuum extrapolation is based on $N_t=$ 10, 12 and 16 lattices. By combining the analysis for these three observables we find, for the curvature, the value $\kappa =0.0149\pm 0.0021$.

    ↳ hep-lathep-phnucl-thPLB(2015)·292 citations
28. 28*

    Matching pion-nucleon Roy-Steiner equations to chiral perturbation theory

    Martin Hoferichter🇺🇸 · Jacobo Ruiz de Elvira🇩🇪 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪

    We match the results for the subthreshold parameters of pion-nucleon scattering obtained from a solution of Roy-Steiner equations to chiral perturbation theory up to next-to-next-to-next-to-leading order, to extract the pertinent low-energy constants including a comprehensive analysis of systematic uncertainties and correlations. We study the convergence of the chiral series by investigating the chiral expansion of threshold parameters up to the same order and discuss the role of the \Delta(1232) resonance in this context. Results for the low-energy constants are also presented in the counting scheme usually applied in chiral nuclear effective field theory, where they serve as crucial input to determine the long-range part of the nucleon-nucleon potential as well as three-nucleon forces.

    ↳ nucl-thhep-phnucl-exPRL(2015)·216 citations
29. 29*

    (MS)SM-like models on smooth Calabi-Yau manifolds from all three heterotic string theories

    Stefan Groot Nibbelink🇩🇪 · Orestis Loukas🇩🇪 · Fabian Ruehle🇩🇪

    We perform model searches on smooth Calabi-Yau compactifications for both the supersymmetric E8xE8 and SO(32) as well as for the non-supersymmetric SO(16)xSO(16) heterotic strings simultaneously. We consider line bundle backgrounds on both favorable CICYs with relatively small h_11 and the Schoen manifold. Using Gram matrices we systematically analyze the combined consequences of the Bianchi identities and the tree-level Donaldson-Uhlenbeck-Yau equations inside the Kahler cone. In order to evaluate the model building potential of the three heterotic theories on the various geometries, we perform computer-aided scans. We have generated a large number of GUT-like models (up to over a few hundred thousand on the various geometries for the three heterotic theories) which become (MS)SM-like upon using a freely acting Wilson line. For all three heterotic theories we present tables and figures summarizing the potentially phenomenologically interesting models which were obtained during our model scans.

    ↳ hep-thhep-phFortsch.Phys.(2015)·53 citations
30. 30*

    Phantom Dark Ghost in Einstein-Cartan Gravity

    Yu-Chiao Chang🇹🇼 · Mariam Bouhmadi-López🇵🇹 · Pisin Chen🇹🇼

    A class of dynamical dark energy models is constructed through an extended version of fermion fields corresponding to phantom dark ghost spinors, which are spin one half with mass dimension one. We find that if these spinors interact with torsion fields in a homogeneous and isotropic universe, then it does not imply any future dark energy singularity or any abrupt event, though the fermion has a negative kinetic energy. In fact, the equation of state of this dark energy model will asymptotically approach the value $w=-1$ from above without crossing the phantom divide and inducing therefore a de Sitter state. Consequently, we expect the model to be stable because no real phantom fields will be created. At late time, the torsion fields will vanish as the corresponding phantom dark ghost spinors dilute. As would be expected, intuitively, this result is unaffected by the presence of cold dark matter although the proof is not as straightforward as in general relativity.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2017)·5 citations
31. 31*

    Encyclopaedia Curvatonis

    Vincent Vennin🇬🇧 · Kazuya Koyama🇬🇧 · David Wands🇬🇧

    We investigate whether the predictions of single-field models of inflation are robust under the introduction of additional scalar degrees of freedom, and whether these extra fields change the potentials for which the data show the strongest preference. We study the situation where an extra light scalar field contributes both to the total curvature perturbations and to the reheating kinematic properties. Ten reheating scenarios are identified, and all necessary formulas allowing a systematic computation of the predictions for this class of models are derived. They are implemented in the public library ASPIC, which contains more than 75 single-field potentials. This paves the way for a forthcoming full Bayesian analysis of the problem. A few representative examples are displayed and discussed.

    ↳ astro-ph.COhep-phhep-thJCAP(2015)·78 citations
32. 32*

    Constraints on the Early and Late Integrated Sachs-Wolfe effects from Planck 2015 Cosmic Microwave Background Anisotropies angular power spectra

    Giovanni Cabass🇮🇹 · Martina Gerbino🇮🇹 · Elena Giusarma🇮🇹 · Alessandro Melchiorri🇮🇹 · Luca Pagano🇮🇹 · Laura Salvati🇮🇹

    The Integrated Sachs-Wolfe (ISW) effect predicts additional anisotropies in the Cosmic Microwave Background due to time variation of the gravitational potential when the expansion of the universe is not matter dominated. The ISW effect is therefore expected in the early universe, due to the presence of relativistic particles at recombination, and in the late universe, when dark energy starts to dominate the expansion. Deviations from the standard picture can be parameterized by $A_{e\text{ISW}}$ and $A_{l\text{ISW}}$, which rescale the overall amplitude of the early and late ISW effects. Analyzing the most recent CMB temperature spectra from the Planck 2015 release, we detect the presence of the early ISW at high significance with $A_{e\mathrm{ISW}}=1.06\pm 0.04$ at 68% CL and an upper limit for the late ISW of $A_{l\mathrm{ISW}}<1.1$ at 95% CL. The inclusion of the recent polarization data from the Planck experiment results in $A_{e\mathrm{ISW}}=0.999\pm 0.028$ at 68% CL, in better agreement with the value $A_{e\mathrm{ISW}}=1$ of a standard cosmology. When considering the recent detections of the late ISW coming from correlations between CMB temperature anisotropies and weak lensing, a value of $A_{l\mathrm{ISW}}=0.85\pm 0.21$ is predicted at 68% CL, showing a $4\sigma$ evidence. We discuss the stability of our result in the case of an extra relativistic energy component parametrized by the effective neutrino number $N_{\mathrm{eff}}$ and of a CMB lensing amplitude $A_{\mathrm{L}}$.

    ↳ astro-ph.COhep-phPRD(2015)·33 citations
33. 33*

    Interplay among transversity induced asymmetries in hadron leptoproduction

    Compass Collaboration: C. Adolph🇩🇪 · R. Akhunzyanov🇷🇺 · M.G. Alexeev🇮🇹 · G.D. Alexeev🇷🇺 · A. Amoroso🇮🇹 · V. Andrieux🇫🇷 · V. Anosov🇷🇺 · W. Augustyniak🇵🇱 · A. Austregesilo🇩🇪 · C.D.R. Azevedo🇵🇹 · B. Badelek🇵🇱 · F. Balestra🇮🇹 and 197 other authors

    In the fragmentation of a transversely polarized quark several left-right asymmetries are possible for the hadrons in the jet. When only one unpolarized hadron is selected, it exhibits an azimuthal modulation known as Collins effect. When a pair of oppositely charged hadrons is observed, three asymmetries can be considered, a di-hadron asymmetry and two single hadron asymmetries. In lepton deep inelastic scattering on transversely polarized nucleons all these asymmetries are coupled with the transversity distribution. From the high statistics COMPASS data on oppositely charged hadron-pair production we have investigated for the first time the dependence of these three asymmetries on the difference of the azimuthal angles of the two hadrons. The similarity of transversity induced single and di-hadron asymmetries is discussed. A new analysis of the data allows to establish quantitative relationships among them, providing for the first time strong experimental indication that the underlying fragmentation mechanisms are all driven by a common physical process.

    ↳ hep-exhep-phPLB(2016)·20 citations
34. 34*

    Reply to "Comment on `Lattice determination of Sigma - Lambda mixing' "

    R. Horsley🇬🇧 · J. Najjar🇩🇪 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · D. Pleiter🇩🇪 · P.E.L. Rakow🇬🇧 · G. Schierholz🇩🇪 · A. Schiller🇩🇪 · H. Stüben🇩🇪 · J.M. Zanotti🇦🇺

    In this Reply, we respond to the above Comment. Our computation [Phys. Rev. D 91 (2015) 074512] only took into account pure QCD effects, arising from quark mass differences, so it is not surprising that there are discrepancies in isospin splittings and in the Sigma - Lambda mixing angle. We expect that these discrepancies will be smaller in a full calculation incorporating QED effects.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2015)·11 citations
35. 35*

    Properties of Nilpotent Supergravity

    E. Dudas🇫🇷 · S. Ferrara🇨🇭 · A. Kehagias🇬🇷 · A. Sagnotti🇨🇭

    We construct Supergravity models where the goldstino multiplet has a gravitational origin, being dual to the chiral curvature superfield. Supersymmetry is nonlinearly realized due to a nilpotent constraint, while the goldstino arises from $\gamma$-traces of the gauge-invariant gravitino field strength. After duality transformations one recovers, as expected, the standard Volkov-Akulov Lagrangian coupled to Supergravity, but the gravitational origin of the goldstino multiplet restricts the available types of matter couplings. We also construct explicitly some inflationary models of this type, which contain both the inflaton and the nilpotent superfield.

    ↳ hep-thgr-qchep-phmath-ph+1JHEP(2015)·109 citations
36. 36*

    Tetraquarks as Diquark Antidiquark Bound Systems

    M. Monemzadeh🇮🇷 · N. Tazimi🇮🇷 · P. Sadeghi🇮🇷

    In this paper, we study four-body systems consisting of diquark antidiquark, and we analyze diquark-antidiquark in the framework of a two body (pseudo point) problem. We solve Lippman Schwinger equation numerically for charm diquark antidiquark systems and find the eigenvalues to calculate the binding energies and masses of heavy tetraquarks with hidden charms. Our results are in good agreement with theoretical and experimental data.

    ↳ physics.comp-phhep-phPLB(2015)·26 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.