Mon·Mar 26, 2018Monday·March 26, 2018

1. 01*

   Flavour Conservation in Two Higgs Doublet Models

   Francisco J. Botella🇪🇸 · Fernando Cornet-Gomez (Valencia U. and IFIC)🇪🇸 · Miguel Nebot (Lisbon IST and CFTP)🇵🇹

   In extensions of the Standard Model with two Higgs doublets, flavour changing Yukawa couplings of the neutral scalars may be present at tree level. In this work we consider the most general scenario in which those flavour changing couplings are absent. We re-analyse the conditions that the Yukawa coupling matrices must obey for such \emph{general flavour conservation} (gFC), and study the one loop renormalisation group evolution of such conditions in both the quark and lepton sectors. We show that gFC in the leptonic sector is one loop stable under the Renormalization Group Evolution (RGE) and in the quark sector we present some new Cabibbo like solution also one loop RGE stable. At a phenomenological level, we obtain the regions for the different gFC parameters that are allowed by the existing experimental constraints related to the 125 GeV Higgs.

   hep-phhep-exPRD(2018)·39 citations
2. 02*

   Bound-state dark matter and Dirac neutrino mass

   M. Reig🇪🇸 · D. Restrepo🇨🇴 · J. W. F. Valle🇪🇸 · O. Zapata🇨🇴

   We propose a simple theory for the idea that cosmological dark matter (DM) may be present today mainly in the form of stable neutral hadronic thermal relics. In our model neutrino masses arise radiatively from the exchange of colored DM constituents, giving a common origin for both dark matter and neutrino mass. The exact conservation of $B-L$ symmetry ensures dark matter stability and the Dirac nature of neutrinos. The theory can be falsified by dark matter nuclear recoil direct detection experiments, leading also to possible signals at a next generation hadron collider.

   hep-phPRD(2018)·44 citations
3. 03*

   The Baryon Asymmetry from a Composite Higgs

   Sebastian Bruggisser🇩🇪 · Benedict von Harling🇩🇪 · Oleksii Matsedonskyi🇩🇪 · Geraldine Servant🇩🇪

   We study the nature of the electroweak phase transition (EWPT) in models where the Higgs emerges as a pseudo-Nambu-Goldstone boson of an approximate global symmetry of a new strongly-interacting sector confining around the TeV scale. Our analysis focusses for the first time on the case where the EWPT is accompanied by the confinement phase transition of the strong sector. We describe the confinement in terms of the dilaton, the pseudo-Nambu-Goldstone boson of spontaneously broken conformal invariance of the strong sector. The dilaton can either be a meson-like or a glueball-like state and we demonstrate a significant qualitative difference in their dynamics. We show that the EWPT can naturally be strongly first-order, due to the nearly-conformal nature of the dilaton potential. Furthermore, we examine the sizeable scale variation of the Higgs potential parameters during the EWPT. In particular, we consider in detail the case of a varying top quark Yukawa coupling, and show that the resulting CP violation is sufficient for successful electroweak baryogenesis. We demonstrate that this source of CP violation is compatible with existing flavour and CP constraints. Our scenario can be tested in complementary ways: by measuring the CP-odd top Yukawa coupling in electron EDM experiments, by searching for dilaton production and deviations in Higgs couplings at colliders, and through gravitational waves at LISA.

   hep-phPRL(2018)·109 citations
4. 04*

   Neutrino oscillations and Lorentz Invariance Violation in a Finslerian Geometrical model

   V. Antonelli🇮🇹 · L. Miramonti🇮🇹 · M.D.C. Torri🇮🇹

   Neutrino oscillations are one of the first evidences of physics beyond the Standard Model (SM). Since Lorentz Invariance is a fundamental symmetry of the SM, recently also neutrino physics has been explored to verify the eventual modification of this symmetry and its potential magnitude. In this work we study the consequences of the introduction of Lorentz Invariance Violation (LIV) in the high energy neutrinos propagation and evaluate the impact of this eventual violation on the oscillation predictions. An effective theory explaining these physical effects is introduced via Modified Dispersion Relations. This approach, originally introduced by Coleman and Glashow, corresponds in our model to a modification of the special relativity geometry. Moreover, the generalization of this perspective leads to the introduction of a maximum attainable velocity which is specific of the particle. This can be formalized in Finsler geometry, a more general theory of space-time. In the present paper the impact of this kind of LIV on neutrino phenomenology is studied, in particular by analyzing the corrections introduced in neutrino oscillation probabilities for different values of neutrino energies and baselines of experimental interest. The possibility of further improving the present constraints on CPT-even LIV coefficients by means of our analysis is also discussed.

   hep-phEPJC(2018)·35 citations
5. 05*

   Probing the gluonic structure of the nucleon through quarkonium production

   S. Joosten🇺🇸

   Heavy quarkonium production will provide for novel opportunities to study the gluonic structure of the nucleon in the near future. Near threshold quarkonium production allows for direct experimental access of the dynamic origin of the nucleon mass as well as the nature of the color Van der Waals force, while quarkonium production at high energies can be used to create a full three-dimensional tomographic image of the gluons inside the nucleon, constraining the gluonic radius of the nucleon.

   hep-phhep-exnucl-ex5 citations
6. 06*

   Photoproduction of dileptons and photons in p-p collisions at Large Hadron Collider energies

   Zhi-Lei Ma🇨🇳 · Jia-Qing Zhu🇨🇳

   The production of large $p_T$ dileptons and photons originating from photoproduction processes in p-p collisions at Large Hadron Collider energies is calculated. The comparisons between the exact treatment results and the ones of the equivalent photon approximation approach are expressed as the $Q^2$ (the virtuality of photon) and $p_T$ distributions. The method developed by Martin and Ryskin is used for avoiding double counting when the coherent and incoherent contributions are considered simultaneously. The numerical results indicate that, the equivalent photon approximation is only effective in small $Q^2$ region and can be used for coherent photoproduction processes with proper choice of $Q_{\text{max}}^2$ ( the choices $Q_{\text{max}}^2\sim \hat{s}$ or $\infty$ will cause obvious errors), but can not be used for incoherent photoproduction processes. The exact treatment is needed to deal accurately with the photoproduction of large $p_T$ dileptons and photons.

   hep-phPRD(2018)·8 citations
7. 07*

   Regge Trajectories of Radial Meson Excitations: Exploring the Dyson-Schwinger-- Bethe-Salpeter Approach

   R. Greifenhagen🇩🇪 · B. Kämpfer🇩🇪 · L. P. Kaptari🇩🇪

   The combined Dyson-Schwinger and Bethe-Salpeter equations in rainbow-ladder approximation are used to search for Regge trajectories of mesons in the pseudo-scalar and vector channels. We focus on the often employed Alkofer-Watson-Weigel kernel which is known to deliver good results for the ground state meson spectra; it provides linear Regge trajectories in the $J^P=0^{-}$ channel.

   hep-phnucl-thSpringer book, FIAS Interdisciplinary Sci…·2 citations
8. 08*

   Width of a two-body coupled-channel resonance

   H. Garcilazo🇲🇽 · A. Valcarce🇪🇸

   We study the width of a two-body resonance in a coupled-channel system. We demonstrate how the width does not come only determined by the available phase space for its decay to the detection channel, but it greatly depends on the relative position of the mass of the resonance with respect to the masses of the coupled-channels generating the state. Our results are consistent with the experimental observation of narrow hadrons lying well above their lowest decay threshold.

   hep-phnucl-thEPJC(2018)·12 citations
9. 09*

   Soft thermal contributions to 3-loop gauge coupling

   M. Laine🇨🇭 · P. Schicho🇨🇭 · Y. Schroder🇨🇱

   We analyze 3-loop contributions to the gauge coupling felt by ultrasoft ("magnetostatic") modes in hot Yang-Mills theory. So-called soft/hard terms, originating from dimension-six operators within the soft effective theory, are shown to cancel 1097/1098 of the IR divergence found in a recent determination of the hard 3-loop contribution to the soft gauge coupling. The remaining 1/1098 originates from ultrasoft/hard contributions, induced by dimension-six operators in the ultrasoft effective theory. Soft 3-loop contributions are likewise computed, and are found to be IR divergent, rendering the ultrasoft gauge coupling non-perturbative at relative order O(alphas^{3/2}). We elaborate on the implications of these findings for effective theory studies of physical observables in thermal QCD.

   hep-phJHEP(2018)·27 citations
10. 10*

    Low lying eigenmodes and meson propagator symmetries

    C. B. Lang🇦🇹

    In situations where the low lying eigenmodes of the Dirac operator are suppressed one observed degeneracies of some meson masses. Based on these results a hidden symmetry was conjectured, which is not a symmetry of the Lagrangian but emerges in the quantization process. We show here how the difference between classes of meson propagators is governed by the low modes and shrinks when they disappear.

    hep-phhep-lathep-thnucl-thPRD(2018)·10 citations
11. 11*

    The neutrino mass hierarchy from oscillation

    Luca Stanco🇮🇹

    The ordering of the neutrino mass eigenstates, also addressed as Mass Hierarchy (MH), is one of the most relevant issues in neutrino physics, currently under investigation by many proposals and experiments. In this short note focus will be given to the different ways to determine MH from neutrino oscillation data in the near future. A pragmatic strategy is suggested and two recent new methods of analysis are recalled. Statistical issues and concerns are also addressed, envisaging the necessity of more accurate studies and analyses.

    hep-ph1 citation
12. 12*

    New physics searches in nuclear and neutron $\beta$ decay

    Martin Gonzalez-Alonso🇨🇭 · Oscar Naviliat-Cuncic🇺🇸 · Nathal Severijns🇧🇪

    The status of tests of the standard electroweak model and of searches for new physics in allowed nuclear $\beta$ decay and neutron decay is reviewed including both theoretical and experimental developments. The sensitivity and complementarity of recent and ongoing experiments are discussed with emphasis on their potential to look for new physics. Measurements are interpreted using a model-independent effective field theory approach enabling to recast the outcome of the analysis in many specific new physics models. Special attention is given to the connection that this approach establishes with high-energy physics. A new global fit of available $\beta$-decay data is performed incorporating, for the first time in a consistent way, superallowed $0^{+}\to 0^{+}$ transitions, neutron decay and nuclear decays. The constraints on exotic scalar and tensor couplings involving left- or right-handed neutrinos are determined while a constraint on the pseudoscalar coupling from neutron decay data is obtained for the first time as well. The values of the vector and axial-vector couplings, which are associated within the standard model to $V_{ud}$ and $g_A$ respectively, are also updated. The ratio between the axial and vector couplings obtained from the fit under standard model assumptions is $C_A/C_V=-1.27510(66)$. The relevance of the various experimental inputs and error sources is critically discussed and the impact of ongoing measurements is studied. The complementarity of the obtained bounds with other low- and high-energy probes is presented including ongoing searches at the Large Hadron Collider.

    hep-phnucl-exnucl-thPPNP(2019)·297 citations
13. 13*

    Renormalizing the zero point energy in dense QCD

    Toru Kojo🇨🇳

    We analyze the zero point energy in a dense matter of quarks or hadrons with particular attention on the renormalization of the UV divergences. Besides divergences removable by the vacuum subtraction and counter terms, there are also UV divergences associated with non-perturbative modifications of quark bases appearing in the in-medium propagators. The latter would remain after the self-energies and vertices are renormalized, unless a proper set of medium contributions is included at a given truncation. We use the formalism of the two particle irreducible action to clarify how the UV divergences are assembled to cancel. An example is given for the thermodynamic potentials with mesons as composite particles whose zero point energies apparently diverge but can be cancelled by the quark self-energy contributions. Important applications of this work are quark matter with hadronic correlations which may be realized at the core of neutron stars.

    hep-phastro-ph.HEhep-thnucl-th0 citations
14. 14*

    On the decays $B\to K^{(\ast )}+$ leptonium

    Matteo Fael🇩🇪 · Thomas Mannel🇩🇪

    We determine the rates of the $B$ meson decays into a $K^{(\ast )}$ and an ${\ell }^{+}{\ell }^{-}$ bound state, the leptonium, where $\ell =e,\mu ,\tau$. The two spin states of the leptonium, the spin singlet and the spin triplet, couple to the axial current and to the vector current, respectively, thus probing different helicity structures of the underlying $b\to s{\ell }^{+}{\ell }^{-}$ effective Hamiltonian. Since ortho- and para-leptonia have different decay modes, a distinction between the two is relatively easy and these decays may become a cross check for the results of lepton-flavour-violation searches obtained with free leptons. We find that some of the decays involving muon and tau have a branching ratio of the order of $10^{-13}$ and they may become accessible at the LHCb with 50 fb${}^{-1}$ of integrated luminosity. In addition, since the tau-pair threshold lies right between the $J/\psi$ and the $\psi (2S)$ resonances, we estimate the charm-loop contribution to the decays $B\to K^{(\ast )}+$tauonium.

    hep-phNPB(2018)·14 citations
15. 15*

    CPT-Symmetric Universe

    Latham Boyle🇨🇦 · Kieran Finn🇨🇦 · Neil Turok🇨🇦

    We propose that the state of the universe does {\it not} spontaneously violate CPT. Instead, the universe after the big bang is the CPT image of the universe before it, both classically and quantum mechanically. The pre- and post-bang epochs comprise a universe/anti-universe pair, emerging from nothing directly into a hot, radiation-dominated era. CPT symmetry selects a unique QFT vacuum state on such a spacetime, providing a new interpretation of the cosmological baryon asymmetry, as well as a remarkably economical explanation for the cosmological dark matter. Requiring only the standard three-generation model of particle physics (with right-handed neutrinos), a ${\mathbb{Z}}_2$ symmetry suffices to render one of the right-handed neutrinos stable. We calculate its abundance from first principles: matching the observed dark matter density requires its mass to be $4.8\times 10^8\mathrm{GeV}$. Several other testable predictions follow: (i) the three light neutrinos are Majorana and allow neutrinoless double $\beta$ decay; (ii) the lightest neutrino is massless; and (iii) there are no primordial long-wavelength gravitational waves. We mention connections to the strong CP problem and the arrow of time.

    hep-phastro-ph.COgr-qchep-thPRL(2018)·141 citations
16. 16*

    The Big Bang, CPT, and neutrino dark matter

    Latham Boyle🇨🇦 · Kieran Finn🇨🇦 · Neil Turok🇨🇦

    We investigate the idea that the universe before the Big Bang is the $CPT$ reflection of the universe after the bang, both classically and quantum mechanically, so that the universe does {\it not} spontaneously violate $CPT$. We show how $CPT$ symmetry selects a preferred vacuum state for quantum fields on a $CPT$-invariant cosmological background spacetime. The universe before the bang and the universe after the bang may be viewed as a universe/anti-universe pair, emerging directly into the hot, radiation-dominated era we observe in our past. This, in turn, leads to a remarkably economical explanation of the cosmological dark matter. With no additional fields beyond Einstein gravity and the standard model of particle physics (including right-handed neutrinos), a ${\mathbb{Z}}_2$ symmetry stabilizes one of the right-handed neutrinos. We calculate its abundance in detail and show that, in order to match the observed dark matter density, its mass must be $4.8\times 10^8\mathrm{GeV}$. We obtain several further predictions, including: (i) that the three light neutrinos are majorana; (ii) that one of these is exactly massless; and (iii) that, in the absence of an epoch of cosmic inflation, there should be no primordial, long-wavelength gravitational waves. We also briefly discuss the natural origin of the matter-antimatter asymmetry within this picture and possibilities for explaining the cosmological perturbations.

    hep-phastro-ph.COgr-qchep-thAnnals Phys.(2022)·61 citations
17. 17*

    Probing the sterile neutrino portal to Dark Matter with $\gamma$ rays

    Miguel G. Folgado🇪🇸 · Germán A. Gómez-Vargas🇨🇱 · Nuria Rius🇪🇸 · Roberto Ruiz de Austri🇪🇸

    Sterile neutrinos could provide a link between the Standard Model particles and a dark sector, besides generating active neutrino masses via the seesaw mechanism type I. We show that, if dark matter annihilation into sterile neutrinos determines its observed relic abundance, it is possible to explain the Galactic Center $\gamma$-ray excess reported by the Fermi-LAT Collaboration as due to an astrophysical component plus dark matter annihilations. We observe that sterile neutrino portal to dark matter provides an impressively good fit, with a p-value of 0.78 in the best fit point, to the Galactic Center $\gamma$-ray flux, for DM masses in the range (40-80) GeV and sterile neutrino masses 20 GeV $\lesssim M_N<M_{DM}$. Such values are compatible with the limits from Fermi-LAT observations of the dwarfs spheroidal galaxies in the Milky Way halo, which rule out dark matter masses below $\sim$ 50 GeV (90 GeV), for sterile neutrino masses $M_N\lesssim M_{DM}$ ($M_N\ll M_{DM}$). We also estimate the impact of AMS-02 anti-proton data on this scenario.

    hep-phJCAP(2018)·31 citations
18. 18*

    Exercise: Dark Matter as fields that evolve backward in time

    Ezequiel Alvarez🇦🇷

    We do the exercise of thinking the qualitative features of a new model in which the problems of Dark Matter (DM) and the Cosmic Microwave Background (CMB) homogeneity are apparently simultaneously solved. We consider that DM consists of fields that evolve backward in time and have a positive defined energy to provide the correct observed curvature of space. We postulate that these fields do not interact with SM fields other than by sharing the same metric, therefore physics in small curvature regimes is causal, without contradictions with available experiments. In strongly curved space causality is lost and solutions must fulfill given equations. The homogeneity problem is naturally solved by these DM fields since, evolving from our future to our past, they bring patches that are currently thought to be causally disconnected into thermal equilibrium for $t\gtrsim 0$ by the Big Bang time. This thermal equilibrium of DM fields in a strongly curved regime must be shared by the metric and our fields, therefore we see these patches with the same CMB temperature. Although we find unlikely that Nature is described by this theory, we find interesting to conclude that there are not obvious logical nor observational inconsistencies and we explore its features. Hopefully some thoughts and results in this work may be useful for other ideas.

    ↳ gr-qchep-phquant-ph4 citations
19. 19*

    Muon content of extensive air showers: comparison of the energy spectra obtained by the Sydney University Giant Air-shower Recorder and by the Pierre Auger Observatory

    J.A. Bellido🇦🇺 · R.W. Clay🇦🇺 · N.N. Kalmykov🇷🇺 · I. S. Karpikov🇷🇺 · G.I. Rubtsov🇷🇺 · S.V. Troitsky🇷🇺 · J. Ulrichs🇦🇺

    The Sydney University Giant Air-shower Recorder (SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon-detector readings, while the Pierre Auger Observatory, looking at the same Southern sky, uses the calorimetric fluorescence method for the same purpose. Comparison of their two spectra allows us to reconstruct the empirical dependence of the number of muons in the shower on the primary energy for energies between $10^{17}$ and $10^{18.5}$ eV. We compare this dependence with the predictions of hadronic interaction models \mbox{QGSJET-II-04} and \mbox{EPOS-LHC}. The empirically determined number of muons with energies above 0.75 GeV exceeds the simulated one by the factors $\sim$1.67 and $\sim$1.28 for $10^{17}$ eV proton and iron primaries, respectively. The muon excess grows moderately with the primary energy, increasing by an additional factor of $\sim 1.2$ for $10^{18.5}$ eV primaries.

    ↳ astro-ph.HEhep-phPRD(2018)·46 citations
20. 20*

    Structure and Width of the d*(2380) Dibaryon

    Avraham Gal🇮🇱

    In this contribution, dedicated to the memory of Walter Greiner, we discuss the structure and width of the recently established d*(2380) dibaryon, confronting the consequences of our Pion Assisted Dibaryons hadronic model with those of quark motivated calculations. In particular, its relatively small width of about 70 MeV favors hadronic structure for the d*(2380) dibaryon rather than a six-quark structure.

    ↳ nucl-thhep-phnucl-ex6 citations
21. 21*

    Progress in measurements of 0.1--10 GeV neutrino-nucleus scattering and anticipated results from future experiments

    Kendall Mahn🇺🇸 · Chris Marshall🇺🇸 · Callum Wilkinson🇨🇭

    Neutrino interactions with nuclei have been the subject of intense interest over the last 15 years. Current and future measurements of neutrino oscillation and exotic physics use order 0.1--10 GeV neutrinos on a range of nuclear targets (${}^{12}$C, ${}^{16}$O, ${}^{40}$Ar). As the precision of these experiments has increased, information from their detectors and dedicated experiments indicate deficiencies in the modeling of neutrino interactions on nuclear targets. Here, we present the current state of knowledge about neutrino-nucleus interactions, the challenge of extracting the cross section of these processes, and current experimental puzzles in the field. We also look forward to new and novel measurements and efforts in the future which seek to resolve these questions.

    ↳ hep-exhep-phnucl-exAnn.Rev.Nucl.Part.Sci.(2018)·44 citations
22. 22*

    Effect of thresholds on the width of three-body resonances

    H. Garcilazo🇲🇽 · A. Valcarce🇪🇸

    It has been recently reported an intriguing theoretical result of a narrow three-body resonance with a large available phase space. The resonance was reported in the $N\Lambda \Lambda -\Xi NN$ system near the $\Xi d$ threshold, having a very small width in spite of the open $N\Lambda \Lambda$ channel lying around 23 MeV below the $\Xi NN$ channel. We use first-order perturbation theory as a plausible argument to explain this behavior. We apply our result to realistic local interactions. Other systems involving several thresholds are likely to follow the same behavior.

    ↳ nucl-thhep-phPLB(2017)·5 citations
23. 23*

    Entropy in the interior of a Kerr black hole

    Xin-Yang Wang🇨🇳 · Jie Jiang🇨🇳 · Wen-Biao Liu🇨🇳

    Christodoulou and Rovelli have shown that the maximal interior volume of a Schwarzschild black hole linearly grows with time. Recently, their conclusion has been extended to the Reissner{-}Nordstr$\ddot{\text{o}}$m and Kerr black holes. Meanwhile, the entropy of interior volume in a Schwarzschild black hole has also been calculated. Here, a new method calculating the entropy of interior volume of the black hole is given and it can be used in more general cases. Using this method, the entropy associated with the volume of a Kerr black hole is calculated and it is found that the entropy is proportional to the Bekenstein-Hawking entropy in the early stage of black hole evaporation. Using the differential form, the entropy of interior volume in a Schwarzschild black hole is recalculated. It is shown that the proportionality coefficient between the entropy and the Bekenstein-Hawking entropy is half of that given in the previous literature. Moreover, the black hole information paradox is brought up again and discussed.

    ↳ gr-qchep-phClass.Quant.Grav.(2018)·25 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.