Wed·Nov 16, 2016Wednesday·November 16, 2016

1. 01*

   Quark Matter Equation of State from Perturbative QCD

   Aleksi Vuorinen🇫🇮

   In this proceedings contribution, we discuss recent developments in the perturbative determination of the Equation of State of dense quark matter, relevant for the microscopic description of neutron star cores. First, we introduce the current state of the art in the problem, both at zero and small temperatures, and then present results from two recent perturbative studies that pave the way towards extending the EoS to higher orders in perturbation theory.

   hep-phEPJ Web Conf.(2017)·15 citations
2. 02*

   One Leptoquark to unify them? Neutrino masses and unification in the light of $(g-2{)}_{\mu }$, $R_{D^{(\star )}}$ and $R_K$ anomalies

   Oleg Popov🇺🇸 · Graham A White🇦🇺

   Leptoquarks have been proposed as a possible explanation of anomalies in $\bar{B}\mapsto D^{\ast }\tau \bar{\nu }$ decays, the apparent anomalies in $(g-2{)}_{\mu }$ experiments and a violation of lepton universality. Motivated by this, we examine other motivations of leptoquarks: radiatively induced neutrino masses in the presence of a discrete symmetry that prevents a tree level see-saw mechanism, gauge coupling unification, and vacuum stability at least up to the unification scale. We present a new model for radiatively generating a neutrino mass which can significantly improve gauge coupling unification at one loop. We discuss this, and other models in the light of recent work on flavour anomalies.

   hep-phNPB(2017)·76 citations
3. 03*

   Heavy quarkonium moving in hot and dense deconfined nuclear matter

   Lata Thakur🇮🇳 · Najmul Haque🇩🇪 · Hiranmaya Mishra🇮🇳

   We study the behavior of the complex potential between a heavy quark and its antiquark, which are in relative motion with respect to a hot and dense medium. The heavy quark-antiquark complex potential is obtained by correcting both the Coulombic and the linear terms in the Cornell potential through a dielectric function estimated within the real-time formalism using the hard thermal loop approximation. We show the variation of both the real and the imaginary parts of the potential for different values of velocities when the bound state ($Q\bar{Q}$ pair) is aligned in the direction parallel as well as perpendicular to the relative velocity of the $Q\bar{Q}$ pair with the thermal medium. With an increase of the relative velocity the screening of the real part of the potential becomes weaker at short distances and stronger at large distances for the parallel case. However, for the perpendicular case the potential decreases with an increase of the velocity at all distances which results in the larger screening of the potential. In addition, the inclusion of the string term makes the screening of the potential weaker as compared to the Coulombic term alone for both cases. Therefore, by combining all these effects we expect a stronger binding of a $Q\bar{Q}$ pair in a moving medium in the presence of the string term as compared to the Coulombic term alone. The imaginary part decreases (in magnitude) with an increase of the relative velocity, leading to a decrease of the width of the quarkonium state at higher velocities. The inclusion of the string term increases the magnitude of the imaginary part, which results in an increase of the width of the quarkonium states. All of these effects lead to the modification in the dissolution of quarkonium states.

   hep-phPRD(2017)·28 citations
4. 04*

   Three-family left-right symmetry with low-scale seesaw mechanism

   Mario Reig🇪🇸 · José W.F. Valle🇪🇸 · C.A. Vaquera-Araujo🇪🇸

   We suggest a new left-right symmetric model implementing a low-scale seesaw mechanism in which quantum consistency requires three families of fermions. The symmetry breaking route to the Standard Model determines the profile of the "next" expected new physics, characterized either by the simplest left-right gauge symmetry or by the 3-3-1 scenario. The resulting $Z^{\prime }$ gauge bosons can be probed at the LHC and provide a production portal for the right-handed neutrinos. On the other hand, its flavor changing interactions would affect the K, D and B neutral meson systems.

   hep-phJHEP(2017)·16 citations
5. 05*

   Seesaw Scale and CP Phases in a Minimal Model of Leptogenesis

   Kim Siyeon🇰🇷

   The seesaw mechanism to derive the light masses of left-handed neutrinos using heavy masses of right-handed neutrinos gives rise to a connection between low-energy measurables and GUT-scale mechanism. We expresses the neutrino mixing angles in terms of a single variable $\sin {\theta }_{13}$, whose size was measured recently. The lepton asymmetry from heavy neutrinos via Yukawa coupling is described by CP phases in both Dirac and Majorana type. It is shown that the seesaw scale relevant to the lepton asymmetry can be constrained by CP phase in this minimal model.

   hep-phJ.Korean Phys.Soc.(2016)·8 citations
6. 06*

   Simplified Models for Dark Matter Face their Consistent Completions

   Dorival Goncalves🇬🇧 · Pedro A. N. Machado🇺🇸 · Jose Miguel No🇬🇧

   Simplified dark matter models have been recently advocated as a powerful tool to exploit the complementarity between dark matter direct detection, indirect detection and LHC experimental probes. Focusing on pseudoscalar mediators between the dark and visible sectors, we show that the simplified dark matter model phenomenology departs significantly from that of consistent $SU(2{)}_{\mathrm{L}}\times U(1{)}_{\mathrm{Y}}$ gauge invariant completions. We discuss the key physics simplified models fail to capture, and its impact on LHC searches. Notably, we show that resonant mono-Z searches provide competitive sensitivities to standard mono-jet analyses at $13$ TeV LHC.

   hep-phhep-exPRD(2017)·116 citations
7. 07*

   Sterile Neutrinos and Flavor Ratios in IceCube

   Vedran Brdar🇩🇪 · Joachim Kopp🇩🇪 · Xiao-Ping Wang (MITP, Johannes Gutenberg University Mainz)🇩🇪

   The flavor composition of astrophysical neutrinos observed in neutrino telescopes is a powerful discriminator between different astrophysical neutrino production mechanisms and can also teach us about the particle physics properties of neutrinos. In this paper, we investigate how the possible existence of light sterile neutrinos can affect these flavor ratios. We consider two scenarios: (i) neutrino production in conventional astrophysical sources, followed by partial oscillation into sterile states; (ii) neutrinos from dark matter decay with a primary flavor composition enhanced in tau neutrinos or sterile neutrinos. Throughout the paper, we constrain the sterile neutrino mixing parameters from a full global fit to short and long baseline data. We present our results in the form of flavor triangles and, for scenario (ii), as exclusion limits on the dark matter mass and lifetime, derived from a fit to IceCube high energy starting events and through-going muons. We argue that identifying a possible flux of neutrinos from dark matter decay may require analyzing the flavor composition as a function of neutrino energy.

   hep-phastro-ph.HEJCAP(2017)·44 citations
8. 08*

   Dark Cosmic Rays

   Ping-Kai Hu🇺🇸 · Alexander Kusenko🇯🇵 · Volodymyr Takhistov🇺🇸

   If dark matter particles have an electric charge, as in models of millicharged dark matter, such particles should be accelerated in the same astrophysical accelerators that produce ordinary cosmic rays, and their spectra should have a predictable rigidity dependence. Depending on the charge, the resulting "dark cosmic rays" can be detected as muon-like or neutrino-like events in Super-Kamiokande, IceCube, and other detectors. We present new limits and propose several new analyses, in particular, for the Super-Kamiokande experiment, which can probe a previously unexplored portion of the millicharged dark matter parameter space. Most of our results are fairly general and apply to a broad class of dark matter models.

   hep-phastro-ph.COastro-ph.HEhep-exPLB(2017)·53 citations
9. 09*

   Looking for possible new physics in $B\to D^{(\ast )}\tau {\nu }_{\tau }$ in light of recent data

   Srimoy Bhattacharya🇮🇳 · Soumitra Nandi🇮🇳 · Sunando K. Patra🇮🇳

   We study the decays $B\to D^{(\ast )}\tau {\nu }_{\tau }$ in light of the available data from BABAR, Belle and LHCb. We divide our analysis into two parts: in one part we fit the form-factors in these decays directly from the data without adding any additional new physics (NP) contributions and compare our fit results with those available from the decays $B\to D^{(\ast )}\ell {\nu }_{\ell }$. We find that the $q^2$-distributions of the form-factors associated with the pseudo-vector current, obtained from $B\to D^{(\ast )}\tau {\nu }_{\tau }$ and $B\to D^{(\ast )}\ell {\nu }_{\ell }$ respectively, do not agree with each other, whereas the other form-factors are consistent with each other. In the next part of our analysis, we look for possible new effective operators of dimension 6 amongst new vector, scalar, and tensor-type that can best explain the current data in the decays $B\to D^{(\ast )}\tau {\nu }_{\tau }$. We use the information-theoretic approaches, especially of `Second-order Akaike Information Criterion' (AIC${}_c$) in the analysis of empirical data. Normality tests for the distribution of residuals are done after selecting the best possible scenarios, for cross-validation. We find that it is the contribution from the operator involving left or right-handed vector current that passes all the selection criteria defined for the best-fit scenario and can successfully accommodate all the available data set.

   hep-phhep-exPRD(2017)·70 citations
10. 10*

    Selection Rule for Enhanced Dark Matter Annihilation

    Anirban Das (Tata Inst., Mumbai)🇮🇳 · Basudeb Dasgupta (Tata Inst., Mumbai)🇮🇳

    We point out a selection rule for enhancement (suppression) of odd (even) partial waves of dark matter coannihilation or annihilation using Sommerfeld effect. Using this, the usually velocity-suppressed p-wave annihilation can dominate the annihilation signals in the present Universe. The selection mechanism is a manifestation of the exchange symmetry of identical incoming particles, and generic for multi-state DM with off-diagonal long-range interactions. As a consequence, the relic and late-time annihilation rates are parametrically different and a distinctive phenomenology, with large but strongly velocity-dependent annihilation rates, is predicted.

    hep-phastro-ph.COastro-ph.HEPRL(2017)·30 citations
11. 11*

    Light-by-light scattering sum rules in light of new data

    Igor Danilkin🇩🇪 · Marc Vanderhaeghen🇩🇪

    We evaluate the light-quark meson contributions to three exact light-by-light scattering sum rules in light of new data by the Belle Collaboration, which recently has extracted the transition form factors of the tensor meson $f_2(1270)$ as well as of the scalar meson $f_0(980)$. We confirm a previous finding that the $\eta ,{\eta }^{\prime }$ and helicity-2 $f_2(1270)$ contributions saturate one of these sum rules up to photon virtualities around 1 GeV${}^2$. At larger virtualities, our sum rule analysis shows an important contribution of the $f_2(1565)$ meson and provides a first empirical extraction of its helicity-2 transition form factor. Two further sum rules allow us to predict the helicity-0 and helicity-1 transition form factors of the $f_2(1270)$ meson. Furthermore, our analysis also provides an update for the scalar and tensor meson hadronic light-by-light contributions to the muon's anomalous magnetic moment.

    hep-phPRD(2017)·184 citations
12. 12*

    Finite-Energy Sum Rules in Eta Photoproduction off the Nucleon

    JPAC Collaboration: J. Nys🇧🇪 · V. Mathieu🇺🇸 · C. Fernández-Ramírez🇲🇽 · A. N. Hiller Blin🇪🇸 · A. Jackura🇺🇸 · M. Mikhasenko🇩🇪 · A. Pilloni🇺🇸 · A. P. Szczepaniak🇺🇸 · G. Fox🇺🇸 · J. Ryckebusch🇧🇪

    The reaction $\gamma N\to \eta N$ is studied in the high-energy regime (with photon lab energies $E_{\gamma }^{\text{lab}}>4$ GeV) using information from the resonance region through the use of finite-energy sum rules (FESR). We illustrate how analyticity allows one to map the t-dependence of the unknown Regge residue functions. We provide predictions for the energy dependence of the beam asymmetry at high energies.

    hep-phPRD(2017)·51 citations
13. 13*

    Constraints on generalized non-standard $tbW$ couplings

    Zenro Hioki (U. Tokushima)🇯🇵 · Kazumasa Ohkuma (Okayama U. Science)🇯🇵 · Akira Uejima (Okayama U. Science)🇯🇵

    General non-standard $tbW$ couplings are studied as model independently as possible based on the effective Lagrangian consisting of the dimension-6 operators, which is an extension of the standard-model Lagrangian. The $tbW$-interaction Lagrangian in this framework includes four kinds of couplings, which could be complex. Constraints on those non-standard $tbW$ couplings are obtained by comparing the experimental data related to the $t\to bW$ process with the corresponding theoretical formulas derived from the effective Lagrangian. The constraints on some sets of the non-standard couplings are shown not to be so strong because those couplings balance out each other as we treat all the non-standard couplings as complex numbers at the same time.

    hep-phhep-exPoS(2016)·0 citations
14. 14*

    Asymmetric Dark Matter Models in SO(10)

    Natsumi Nagata🇯🇵 · Keith A. Olive🇺🇸 · Jiaming Zheng🇺🇸

    We systematically study the possibilities for asymmetric dark matter in the context of non-supersymmetric SO(10) models of grand unification. Dark matter stability in SO(10) is guaranteed by a remnant ${\mathbb{Z}}_2$ symmetry which is preserved when the intermediate scale gauge subgroup of SO(10) is broken by a $126$ dimensional representation. The asymmetry in the dark matter states is directly generated through the out-of-equilibrium decay of particles around the intermediate scale, or transferred from the baryon/lepton asymmetry generated in the Standard Model sector by leptogenesis. We systematically classify possible asymmetric dark matter candidates in terms of their quantum numbers, and derive the conditions for each case that the observed dark matter density is (mostly) explained by the asymmetry of dark matter particles.

    hep-phJCAP(2017)·40 citations
15. 15*

    Single spin asymmetry in forward $pA$ collisions II: Fragmentation contribution

    Yoshitaka Hatta🇯🇵 · Bo-Wen Xiao🇨🇳 · Shinsuke Yoshida🇺🇸 · Feng Yuan🇺🇸

    We compute the twist-three fragmentation contribution to the transverse single spin asymmetry (SSA) in light hadron production $p^{\uparrow }p\to hX$ and $p^{\uparrow }A\to hX$ including the gluon saturation effect in the unpolarized nucleon/nucleus. Together with the results in our previous paper, this completes the full evaluation of the SSA in this process in the "hybrid" formalism. We argue that the dependence of SSAs on the atomic mass number in the forward region can elucidate the relative importance of the soft gluon pole contribution from the twist-three quark-gluon-quark correlation in the polarized nucleon and the twist-three fragmentation contribution from the final state hadron.

    hep-phhep-exPRD(2017)·26 citations
16. 16*

    Heavy Hybrids: decay to and mixing with Heavy Quarkonium

    Rubén Oncala🇪🇸 · Joan Soto🇪🇸

    We report on a recent QCD based research on hybrid mesons containing $c\bar{c}$ or $b\bar{b}$ quarks. We present results for the spectrum, the decay widths to heavy quarkonium, and the role of mixing with the latter. We point out that mixing with heavy quarkonium provides a potentially large source of spin symmetry breaking. We identify candidates to hybrid mesons among the so called XYZ states in the charmonium and bottomonium spectrum.

    hep-phEPJ Web Conf.(2017)·5 citations
17. 17*

    Modelling theoretical uncertainties in phenomenological analyses for particle physics

    Jérôme Charles🇫🇷 · Sébastien Descotes-Genon🇫🇷 · Valentin Niess🇫🇷 · Luiz Vale Silva🇫🇷

    The determination of the fundamental parameters of the Standard Model (and its extensions) is often limited by the presence of statistical and theoretical uncertainties. We present several models for the latter uncertainties (random, nuisance, external) in the frequentist framework, and we derive the corresponding $p$-values. In the case of the nuisance approach where theoretical uncertainties are modeled as biases, we highlight the important, but arbitrary, issue of the range of variation chosen for the bias parameters. We introduce the concept of adaptive $p$-value, which is obtained by adjusting the range of variation for the bias according to the significance considered, and which allows us to tackle metrology and exclusion tests with a single and well-defined unified tool, which exhibits interesting frequentist properties. We discuss how the determination of fundamental parameters is impacted by the model chosen for theoretical uncertainties, illustrating several issues with examples from quark flavour physics.

    hep-phhep-exphysics.data-anEPJC(2017)·24 citations
18. 18*

    On the relation between the CP phases in the PMNS matrix, CP-violation with sterile neutrinos and leptogenesis

    Marco Drewes🇩🇪 · Bjorn Garbrecht🇩🇪 · Dario Gueter🇩🇪 · Juraj Klaric🇩🇪

    We discuss the connection between observable CP violation in the lepton sector, the properties of heavy neutrinos and the baryon asymmetry of the universe in the minimal seesaw model. A measurement of the Dirac phase $\delta$ would allow to make testable predictions for the couplings of the heavy neutrinos to individual Standard Model lepton flavours. If any heavy neutral leptons are experimentally discovered in the future, this provides a powerful test for the mechanism of neutrino mass generation and baryogenesis.

    hep-phhep-ex3 citations
19. 19*

    Mixed QCD-QED corrections to DGLAP equations

    German F. R. Sborlini🇪🇸 · Daniel de Florian🇦🇷 · German Rodrigo🇪🇸

    We study the mixed effect of QCD and QED corrections to the evolution of parton distribution functions (PDFs). The Altarelli-Parisi splitting functions are extended to one order higher in QED, reaching $\mathcal{O}(\alpha {\alpha }_S^2)$ accuracy. This also involves extending DGLAP equations to include charge separation effects, that are ignored for pure QCD corrections. Besides that, these effects are crucial for the determination of the photon distribution, which plays an increasingly important role in nowadays phenomenological analysis.

    hep-phPoS(2016)·6 citations
20. 20*

    Relativistic effects in model calculations of double parton distribution function

    Matteo Rinaldi🇪🇸 · Federico Alberto Ceccopieri🇧🇪

    In this paper we consider double parton distribution functions (dPDFs) which are the main non perturbative ingredients appearing in the double parton scattering cross section formula in hadronic collisions. By using recent calculation of dPDFs by means of constituent quark models within the so called Light-Front approach, we investigate the role of relativistic effects on dPDFs. We find, in particular, that the so called Melosh operators, which allow to properly convert the LF spin into the canonical one and incorporate a proper treatment of boosts, produce sizeable effects on dPDFs. We discuss specific partonic correlations induced by these operators in transverse plane which are relevant to the proton structure and study under which conditions these results are stable against variations in the choice of the proton wave function.

    hep-phnucl-thPRD(2017)·35 citations
21. 21*

    Dihadron Production at LHC: BFKL Predictions for Cross Sections and Azimuthal Correlations

    Francesco G. Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Beatrice Murdaca🇮🇹 · Alessandro Papa🇮🇹

    A study of the inclusive production of a pair of hadrons (a "dihadron" system), having high transverse momenta and separated by a large interval of rapidity, is presented. This process has much in common with the widely discussed Mueller--Navelet jet production and can be also used to access the BFKL dynamics at proton colliders. Large contributions enhanced by logarithms of energy can be resummed in perturbation theory within the BFKL formalism in the next-to-leading logarithmic accuracy. The experimental study of dihadron production would provide with an additional clear channel to test the BFKL dynamics. The first theoretical predictions for cross sections and azimuthal angle correlations of the two hadrons produced with LHC kinematics are presented.

    hep-phAIP Conf.Proc.(2017)·39 citations
22. 22*

    Inclusive three- and four-jet production in multi-Regge kinematics at the LHC

    Francesco Caporale🇪🇸 · Francesco G. Celiberto🇮🇹 · Grigorios Chachamis🇪🇸 · David Gordo Gomez🇪🇸 · Agustin Sabio Vera🇪🇸

    A study of differential cross sections for the production of three and four jets in multi-Regge kinematics is presented. The main focus lies on the azimuthal angle dependences in events with two forward/backward jets are tagged in the final state. Furthermore, the tagging of one or two extra jets in more central regions of the detector with a relative separation in rapidity from each other is requested. It is found that the dependence of the cross sections on the transverse momenta and the rapidities of the central jet(s) can offer new means of studying the onset of BFKL dynamics.

    hep-phAIP Conf.Proc.(2017)·35 citations
23. 23*

    Theoretical motivations for precision measurements of oscillation parameters

    Silvia Pascoli🇬🇧 · Ye-Ling Zhou🇬🇧

    We discuss two theoretical motivations of precision measurements of oscillation parameters. One is the guidance for flavour model building with flavour symmetries, and the other is the connection with the origin of matter-antimatter asymmetry. We also present our recent progress in these aspects, a new approach of flavour model building based on cross coupling in the flavon potential and a novel mechanism of leptogenesis via phase transition.

    hep-phPoS(2016)·2 citations
24. 24*

    Towards regularized higher-order computations in QFT without DREG

    German F. R. Sborlini🇪🇸 · Felix Driencourt-Mangin🇪🇸 · Roger Hernandez-Pinto🇲🇽 · German Rodrigo🇪🇸

    In this talk, we review the basis of the loop-tree duality theorem, which allows to rewrite loop scattering amplitudes in terms of tree-level like objects. Since the loop measure is converted into a phase-space one, both virtual and real contributions are expressible using the same integration variables. A physically motivated momentum mapping allows to generate the real emission process starting from the Born kinematics and the loop momenta. The integrand-level combination leads to regular functions, which can be integrated without using dimensional regularization (DREG) and correctly reproduce the finite higher-order corrections to physical observables. We explain the implementation of this novel approach to compute some benchmark physical processes, and we show how to deal with both infrared and ultraviolet divergences in four space-time dimensions.

    hep-phhep-thPoS(2016)·5 citations
25. 25*

    Three-point vertex functions in Yang-Mills Theory and QCD in Landau gauge

    Adrian L. Blum🇦🇹 · Reinhard Alkofer🇦🇹 · Markus Q. Huber🇦🇹 · Andreas Windisch🇺🇸

    Solutions for the three-gluon and quark-gluon vertices from Dyson-Schwinger equations and the three-particle irreducible formalism are discussed. Dynamical quarks (``unquenching'') change the three-gluon vertex via the quark-triangle diagrams which themselves include fully dressed quark-gluon vertex functions. On the other hand, the quark-swordfish diagram is, at least with the model used for the two-quark-two-gluon vertex employed here, of minor importance. For the leading tensor structure of the three-gluon vertex the "unquenching" effect can be summarized for the nonperturbative part as a shift of the related dressing function towards the infrared.

    hep-phEPJ Web Conf.(2017)·16 citations
26. 26*

    Analytic Solutions of Transverse Magneto-hydrodynamics under Bjorken Expansion

    Shi Pu🇩🇪 · Di-Lun Yang🇯🇵

    We review the recent developments of analytic solutions in transverse magneto-hydrodynamics under Bjorken expansion. It is found that the time dependence of magnetic fields can either increase or reduce the energy density depending on the decay exponent of magnetic fields. Moreover, perturbative solutions under weak magnetic fields with spatial inhomogeneity results in transverse flow, where the directions of flow also depend on the decay exponent of magnetic fields in time.

    hep-phnucl-thEPJ Web Conf.(2017)·16 citations
27. 27*

    Direct-Photon Spectra and Anisotropic Flow in Heavy Ion Collisions from Holography

    Ioannis Iatrakis🇳🇱 · Elias Kiritsis🇫🇷 · Chun Shen🇨🇦 · Di-Lun Yang🇯🇵

    The thermal-photon emission from strongly coupled gauge theories at finite temperature is calculated by using holographic models for QCD in the Veneziano limit (V-QCD). These emission rates are then embedded in hydrodynamic simulations combined with prompt photons from hard scattering and the thermal photons from hadron gas to analyze the spectra and anisotropic flow of direct photons at RHIC and LHC. The results from different sources responsible for the thermal photons in the quark gluon plasma (QGP) including the weakly coupled QGP (wQGP) from perturbative calculations, strongly coupled $\mathcal{N}$=4 super Yang-Mills (SYM) plasma (as a benchmark for reference), and Gubser's phenomenological model mimicking the strongly coupled QGP (sQGP) are then compared. It is found that the direct-photon spectra are enhanced in the strongly coupled scenario compared with the ones in the wQGP, especially at intermediate and high momenta, which improve the agreements with data. Moreover, by using IP-glassma initial states, both the elliptic flow and triangular flow of direct photons are amplified at high momenta ($p_T$>2.5 GeV) for V-QCD, while they are suppressed at low momenta compared to wQGP. The distinct results in holography stem from the blue-shift of emission rates in strong coupling. In addition, the spectra and flow in small collision systems were evaluated for future comparisons. It is found that thermal photons from the deconfined phase are substantial to reconcile the spectra and flow at high momenta.

    hep-phhep-thnucl-thEPJ Web Conf.(2017)·3 citations
28. 28*

    B-decay Anomalies in a Composite Leptoquark Model

    Riccardo Barbieri🇮🇹 · Christopher W. Murphy🇺🇸 · Fabrizio Senia🇮🇹

    The collection of a few anomalies in semileptonic $B$-decays, especially in $b\to c\tau \bar{\nu }$, invites to speculate about the emergence of some striking new phenomena, perhaps interpretable in terms of a weakly broken $U(2{)}^n$ flavor symmetry and of leptoquark mediators. Here we aim at a partial UV completion of this interpretation by generalizing the minimal composite Higgs model to include a composite vector leptoquark as well.

    hep-phhep-exEPJC(2017)·236 citations
29. 29*

    Inflation and pseudo-Goldstone Higgs boson

    Tommi Alanne🇩🇰 · Francesco Sannino🇩🇰 · Tommi Tenkanen🇬🇧 · Kimmo Tuominen🇫🇮

    We consider inflation within a model framework where the Higgs boson arises as a pseudo-Goldstone boson associated with the breaking of a global symmetry at a scale significantly larger than the electroweak one. We show that in such a model the scalar self-couplings can be parametrically suppressed and, consequently, the non-minimal couplings to gravity can be of order one or less, while the inflationary predictions of the model remain compatible with the precision cosmological observations. Furthermore, in the model we study, the existence of the electroweak scale is entirely due to the inflaton field. Our model therefore suggests that inflation and low energy particle phenomenology may be more entwined than assumed so far.

    hep-phastro-ph.COPRD(2017)·10 citations
30. 30*

    Possibility of hypothetical stable micro black hole production at future 100 TeV collider

    Anton V. Sokolov🇷🇺 · Maxim S. Pshirkov🇷🇺

    We study the phenomenology of TeV-scale black holes predicted in theories with large extra dimensions, under the further assumption that they are absolutely stable. Our goal is to present an exhaustive analysis of safety of the proposed 100 TeV collider, as it was done in the case of the LHC. We consider the theories with different number of extra dimensions and identify those for which a possible accretion to macroscopic size would have timescales shorter than the lifetime of the Solar system. We calculate the cross sections of the black hole production at the proposed 100 TeV collider, the fraction of the black holes trapped inside the Earth and the resulting rate of capture inside the Earth via an improved method. We study the astrophysical consequences of stable micro black holes existence, in particular its influence on the stability of white dwarfs and neutron stars. We obtain constraints for the previously unexplored range of higher-dimensional Planck mass values. Several astrophysical scenarios of the micro black hole production, which were not considered before, are taken into account. Finally, using the astrophysical constraints we consider the implications for future 100 TeV terrestrial experiments. We exclude the possibility of the charged stable micro black holes production.

    hep-phastro-ph.HEgr-qcEPJC(2017)·8 citations
31. 31*

    Role of the strange quark in the rho(770) meson

    R. Molina🇺🇸 · D. Guo🇺🇸 · B. Hu🇺🇸 · A. Alexandru🇺🇸 · M. Doring🇺🇸

    Recently, the GWU lattice group has evaluated high-precision phase-shift data for $\pi \pi$ scattering in the $I=1$, $J=1$ channel. Unitary Chiral Perturbation Theory describes these data well around the resonance region and for different pion masses. Moreover, it allows to extrapolate to the physical point and estimate the effect of the missing $K\bar{K}$ channel in the two-flavor lattice calculation. The absence of the strange quark in the lattice data leads to a lower $\rho$ mass, and the analysis with U$\chi$PT shows that the $K\bar{K}$ channel indeed pushes the $\pi \pi$-scattering phase shift upward, having a surprisingly large effect on the $\rho$-mass. The inelasticity is shown to be compatible with the experimental data. The analysis is then extended to all available two-flavor lattice simulations and similar mass shifts are observed. Chiral extrapolations of $N_f=2+1$ lattice simulations for the $\rho (770)$ are also reported.

    ↳ hep-lathep-phEPJ Web Conf.(2017)·2 citations
32. 32*

    O($N$) Invariance of the Multi-Field Bounce

    Kfir Blum🇮🇱 · Masazumi Honda🇮🇱 · Ryosuke Sato🇮🇱 · Masahiro Takimoto🇯🇵 · Kohsaku Tobioka🇮🇱

    In his 1977 paper on vacuum decay in field theory: The Fate of the False Vacuum, Coleman considered the problem of a single scalar field and assumed that the minimum action tunnelling field configuration, the bounce, is invariant under O(4) rotations in Euclidean space. A proof of the O(4) invariance of the bounce was provided later by Coleman, Glaser, and Martin (CGM), who extended the proof to $N>2$ Euclidean dimensions but, again, restricted non-trivially to a single scalar field. As far as we know a proof of O($N$) invariance of the bounce for the tunnelling problem with multiple scalar fields has not been reported, even though it was assumed in many works since, being of phenomenological interest. We make progress towards closing this gap. Following CGM we define the reduced problem of finding a field configuration minimizing the kinetic energy at fixed potential energy. Given a solution of the reduced problem, the minimum action bounce can always be obtained from it by means of a scale transformation. We show that if a solution of the reduced problem exists, then it and the minimum action bounce derived from it are indeed O($N$) symmetric.

    ↳ hep-thhep-phmath-phmath.MPJHEP(2017)·42 citations
33. 33*

    Cores in Dwarf Galaxies from Fermi Repulsion

    Lisa Randall🇺🇸 · Jakub Scholtz🇺🇸 · James Unwin🇺🇸

    We show that Fermi repulsion can lead to cored density profiles in dwarf galaxies for sub-keV fermionic dark matter. We treat the dark matter as a quasi-degenerate self-gravitating Fermi gas and calculate its density profile assuming hydrostatic equilibrium. We find that suitable dwarf galaxy cores of larger than 130 pc can be achieved for fermion dark matter with mass in the range 70 eV - 400 eV. While in conventional dark matter scenarios, such sub-keV thermal dark matter would be excluded by free streaming bounds, the constraints are ameliorated in models with dark matter at lower temperature than conventional thermal scenarios, such as the Flooded Dark Matter model that we have previously considered. Modifying the arguments of Tremaine and Gunn we derive a conservative lower bound on the mass of fermionic dark matter of 70 eV and a stronger lower bound from Lyman-$\alpha$ clouds of about 470 eV, leading to slightly smaller cores than have been observed. We comment on this result and how the tension is relaxed in dark matter scenarios with non-thermal momentum distributions.

    ↳ astro-ph.GAastro-ph.COhep-phMNRAS(2017)·71 citations
34. 34*

    Hints of new physics from stars

    Maurizio Giannotti🇺🇸

    We review and update the current status of the observed anomalies in stellar cooling and their interpretation in terms of axions and axion like particles.

    ↳ astro-ph.HEhep-phPoS(2016)·12 citations
35. 35*

    IAXO, next-generation of helioscopes

    Maurizio Giannotti🇺🇸 · Jaime Ruz🇺🇸 · Julia K. Vogel🇺🇸

    The International Axion Observatory (IAXO) is a forth generation axion helioscope designed to detect solar axions and axion-like particles (ALPs) with a coupling to the photon $g_{a\gamma }$ down to a few $10^{-12}$ GeV${}^{-1}$, 1.5 orders of magnitude beyond the current best astrophysical and experimental upper bounds. This range includes parameter values invoked in the context of the observed anomalies in light propagation over astronomical distances and to explain the excessive cooling observed in a number of stellar objects. Here we review the status of the IAXO project and of its potential to probe the most physically motivated regions of the axion/ALPs parameter space.

    ↳ physics.ins-detastro-ph.IMastro-ph.SRhep-ex+1PoS(2016)·19 citations
36. 36*

    Pseudoscalar condensation induced by chiral anomaly and vorticity for massive fermions

    Ren-hong Fang🇨🇳 · Jin-yi Pang🇩🇪 · Qun Wang🇨🇳 · Xin-nian Wang🇨🇳

    We derive the pseudoscalar condensate induced by anomaly and vorticity from the Wigner function for massive fermions in homogeneous electromagnetic fields. It has an anomaly term and a force-vorticity coupling term. As a mass effect, the pseudoscalar condensate is linearly proportional to the fermion mass in small mass expansion. By a generalization to two-flavor and three-flavor cases, the neutral pion and eta meson condensates are calculated from the Wigner function and have anomaly parts as well as force-vorticity parts, in which the anomaly part of the neutral pion condensate is consistent to the previous result. We also discuss about possible observables of the condensates in heavy ion collisions such as collective flows of neutral pions and eta mesons which may be influenced by the electromagnetic field and vorticity profiles.

    ↳ nucl-thhep-phPRD(2017)·40 citations
37. 37*

    Light-by-light scattering in the Lamb shift and the bound electron g factor

    Andrzej Czarnecki🇨🇦 · Robert Szafron🇨🇦

    We compute an $\mathcal{O}\left({\alpha }^2(Z\alpha {)}^6\right)$ contribution to the hydrogen-atom Lamb shift arising from the light-by-light scattering. Analogous diagrams, with one atomic electric field insertion replaced by an external magnetic field, contribute to the gyromagnetic factor of the bound electron at $\mathcal{O}\left({\alpha }^2(Z\alpha {)}^4\right)$. We also calculate the contribution to the gyromagnetic factor from the muon magnetic loop.

    ↳ physics.atom-phhep-phPRA(2016)·47 citations
38. 38*

    The Fate of the Higgs Vacuum

    Ruth Gregory🇬🇧 · Ian G. Moss🇬🇧

    This talk reviews our recent work showing how tiny black holes can act as nucleation sites for the decay of the metastable Higgs vacuum. We start by discussing the formation of thin wall bubbles of true vacuum inside a false vacuum, and show how adding a black hole lowers the action of the Euclidean tunneling solution, thus strongly enhancing the probability of vacuum decay. We then review numerical results for the Higgs vacuum showing that the decay rate is even higher for these "thick wall" bubbles. The results imply either tiny black holes are not a component of our universe, or BSM corrections to the Higgs potential must stabilise our vacuum.

    ↳ hep-thhep-phPoS(2016)·14 citations
39. 39*

    Observational Properties of Feebly Coupled Dark Matter

    Matti Heikinheimo🇫🇮 · Tommi Tenkanen🇫🇮 · Kimmo Tuominen🇫🇮 · Ville Vaskonen🇫🇮

    We show that decoupled hidden sectors can have observational consequences. As a representative model example, we study dark matter production in the Higgs portal model with one real singlet scalar $s$ coupled to the Standard Model Higgs via ${\lambda }_{\mathrm{hs}}{\Phi }^{†}\Phi s^2$ and demonstrate how the combination of non-observation of cosmological isocurvature perturbations and astrophysical limits on dark matter self-interactions imply stringent bounds on the magnitude of the scalar self-coupling ${\lambda }_{\mathrm{s}}{s}^4$. For example, for dark matter mass $m_{\mathrm{s}}=10$ MeV and Hubble scale during cosmic inflation $H_{\ast }=10^{12}$ GeV, we find $10^{-4}\lesssim {\lambda }_{\mathrm{s}}\lesssim 0.2$.

    ↳ astro-ph.COhep-phPoS(2016)·6 citations
40. 40*

    Mass generation from a non-perturbative correction: Massive NS-field and graviton in $(3+1)$-dimensions

    Supriya Kar🇮🇳 · R. Nitish🇮🇳

    We show that the massless form fields, in $(4+1)$-dimensional non-perturbation theory of emergent gravity, become massive in a perturbative phase without Higgs mechanism. In particular an axionic scalar sourced by a non-perturbative dynamical correction is absorbed by the form fields to describe a massive NS field theory on an emergent gravitational pair of $(3\bar{3})$-brane. Arguably the novel idea of Higgs mechanism is naturally invoked in an emergent gravity underlying a ${\mathrm{CFT}}_6$. Analysis reveals "gravito-weak" and "electro-weak" phases respectively on a vacuum pair in $(4+1)$ and $(3+1)$-dimensions. It is argued that the massive NS field quanta may govern an emergent graviton on a gravitational $3$-brane.

    ↳ hep-thgr-qchep-phPTEP(2019)·1 citation
41. 41*

    The muon g-2 experiment at Fermilab

    W. Gohn🇺🇸

    A new measurement of the anomalous magnetic moment of the muon, $a_{\mu }\equiv (g-2)/2$, will be performed at the Fermi National Accelerator Laboratory with data taking beginning in 2017. The most recent measurement, performed at Brookhaven National Laboratory and completed in 2001, shows a 3.5 standard deviation discrepancy with the standard model prediction of $a_{\mu }$. The new measurement will accumulate 21 times those statistics using upgraded detection and storage ring systems, enabling a measurement of $a_{\mu }$ to 140 ppb, a factor of 4 improvement in the uncertainty the previous measurement. This improvement in precision, combined with recent and ongoing improvements in the evaluation of the QCD contributions to the $a_{\mu }$, could provide a 7.5$\sigma$ discrepancy from the standard model if the current difference between experiment and theory is confirmed, a possible indication of new physics.

    ↳ hep-exhep-phphysics.ins-det9 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.