Mon·Oct 17, 2016Monday·October 17, 2016

1. 01*

   Is Left-Right Symmetry the Key?

   Goran Senjanovic🇮🇹

   In collaboration with Jogesh Pati, Abdus Salam challenged the chiral gauge nature of the Standard Model by paving the road towards the Left-Right symmetric electro-weak theory. I describe here the logical and historical construction of this theory, by emphasising the pioneering and key role it played for neutrino mass. I show that it is a self-contained and predictive model with the Higgs origin of Majorana neutrino mass, in complete analogy with the SM situation regarding charged fermions.

   hep-phhep-exphysics.hist-phMod.Phys.Lett.A(2017)·25 citations
2. 02*

   Probing new physics in $B\to D{\ell }^{+}{\ell }^{-}$ decays by using angular asymmetries

   C. S. Kim🇰🇷 · Dibyakrupa Sahoo🇮🇳

   We present the fully general, model independent study of a few rare semileptonic $B$ decays that get dominant contributions from $W$-annihilation and $W$-exchange diagrams, in particular $B^0\to {\bar{D}}^0{\ell }^{+}{\ell }^{-}$, where $\ell =e,\mu$. We consider the most general Lagrangian for the decay, and define three angular asymmetries in the Gottfried-Jackson frame, which are sensitive to new physics. We show how these angular asymmetries can be easily extracted from the distribution of events in the Dalitz plot for $B\to D{\ell }^{+}{\ell }^{-}$ decays. Especially a non-zero forward-backward asymmetry within the frame would give the very first hint of possible new physics. These observations are also true for related decay modes, such as $B^{+}\to D^{+}{\ell }^{+}{\ell }^{-}$ and $B^0\to D^0{\ell }^{+}{\ell }^{-}$. Moreover, these asymmetry signatures are not affected by either $B^0$-${\bar{B}}^0$ or $D^0$-${\bar{D}}^0$ mixings. Then, this implies that both $B^0\to {\bar{D}}^0{\ell }^{+}{\ell }^{-}$ and $B^0\to D^0{\ell }^{+}{\ell }^{-}$ as well as their CP conjugate modes can all be considered together in our search for signature of new physics. Hence, it would be of great importance to look for and study these decays in the laboratory, LHCb and Belle II in particular.

   hep-phEPJC(2017)·1 citation
3. 03*

   Semileptonic and leptonic $B$ decays, circa 2016

   Giulia Ricciardi🇮🇹

   We summarize the status of semileptonic and leptonic $B$ decays, including $|V_{cb}|$ and $|V_{ub}|$ exclusive and inclusive determinations, decays to excited states of the charm meson spectrum and decays into $\tau$ leptons.

   hep-phMod.Phys.Lett.A(2017)·24 citations
4. 04*

   Updates of the MMHT2014 PDFs

   L.A. Harland-Lang🇬🇧 · A.D. Martin🇬🇧 · R.S. Thorne🇬🇧

   We briefly discuss some of the developments since the publication of the MMHT14 parton distributions. In particular we explore the impact of recent LHC data for $W^{\pm },Z$ and $t\bar{t}$ production, and perform a preliminary new analysis including these data. In this re-fit (which we tentatively call `MMHT16') there are few changes of significance in the central values of the PDFs, but some data reduce the uncertainties, mainly in the strange and valence quark distributions. We find that an extended $\bar{d}-\bar{u}$ parametrization only leads to minor changes, with the difference going to zero as $x\to 0$. We comment on the determination of the photon PDF.

   hep-phAIP Conf.Proc.(2017)·3 citations
5. 05*

   Comparing Production Cross Sections for QCD Matter, Higgs Boson, Neutrino with Dark Energy in Accelerating Universe

   Tooraj Ghaffary🇮🇷

   In this research, the production cross sections for QCD matter, neutrino and dark energy due to acceleration of Universe is calculated. To obtain these cross sections, the Universe production cross section is multiplied by the particle or dark energy distribution in accelerating Universe. Also missing cross section for each matter and dark energy due to formation of event horizon, is calculated. It is clear that the cross section of particles produced near event horizon of Universe is much larger for higher acceleration of Universe. This is because as the acceleration of Universe becomes larger, the Unruh temperature becomes larger and the thermal radiations of particles are enhanced. There are different channels for producing Higgs boson in accelerating Universe. Universe maybe decay to quark and gluons, and then these particles interact with each other and Higgs boson is produced. Also, some Higgs boson are emitted directly from event horizon of Universe. Comparing Higgs boson cross sections via different channels, it is observed that at lower acceleration, a_Universe<2.5 a_(early Universe), the Universe will not be able to emit Higgs, but is still able to produce a quark and eventually for a_Universe<1.5 a_(early Universe) the Universe can only emit massless gluons. As the acceleration of Universe at the LHC increases, a_Universe>2.5 a_(early Universe), most of Higgs boson production will be due to Unruh effect near event horizon of Universe. Finally comparing the production cross section for dark energy with particle cross sections, it is found that the cross section for dark energy is dominated by QCD matter, Higgs boson and neutrino. This result is consistent with previous predictions for dark energy cross section.

   hep-phInt.J.Geom.Meth.Mod.Phys.(2017)·1 citation
6. 06*

   Exotic Hadron Bound State Production at Hadronic Colliders

   Yi Jin🇨🇳 · Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Lu Meng🇨🇳 · Zong-Guo Si🇨🇳 · Xiao-Feng Zhang🇨🇳

   The non-relativistic wave function framework is applied to study the production and decay of the exotic hadrons which can be effectively described as bound states of other hadrons. Employing the factorized formulation, we investigate the production of exotic hadrons in the multiproduction processes at high energy hadronic colliders with the help of event generators. This study provides crucial information for the measurements of the relevant exotic hadrons.

   hep-phnucl-thCPC(2017)·14 citations
7. 07*

   What can we learn from NJL-type models about dense matter?

   Michael Buballa🇩🇪

   The merits and limitations of the Nambu--Jona-Lasinio model as a model for strong interactions at nonzero density are critically discussed. We present several examples, demonstrating that, while in general the results should not be trusted quantitatively, the NJL model is a powerful theoretical tool for getting new insights and ideas about the QCD phase diagram and the dense-matter equation of state.

   hep-phnucl-thBled Workshops Phys.(2016)·3 citations
8. 08*

   Light Stops from extra dimensions

   Mateo Garcia-Pepin🇪🇸

   In supersymmetric models the mass of the stops can be considered as the naturalness measure of the theory. Roughly, the lighter the stops are, the more natural the theory is. Both, the absence of supersymmetric signals at experiment and the measurement of the Higgs mass, put scenarios with light stops under increasing tension. I will present a supersymmetry breaking mechanism of the Scherk-Schwarz type that, by introducing extra $SU(2{)}_L$ triplets in the Higgs sector, is able to generate the correct Higgs mass while keeping stops light.

   hep-ph0 citations
9. 09*

   S-matrix approach to the Z resonance

   T. Riemann (Koenigs Wusterhausen)🇩🇪

   The proposed $e^{+}{e}^{-}$-collider FCC-ee aims at an unprecedented accuracy for $e^{+}{e}^{-}$ collisions into fermion pairs at the $Z$ peak, based on about $10^{13}$ events. The S-matrix approach to the $Z$ boson line shape allows the model-independent quantitative description of the reaction $e^{+}{e}^{-}\to \bar{f}f$ around the $Z$ peak in terms of few parameters, among them the mass $M_Z$ and width ${\Gamma }_Z$ of the $Z$-boson. While weak and strong corrections remain "black", a careful theoretical description of the photonic interactions is mandatory. I introduce the method and describe applications and the analysis tool SMATASY/ZFITTER.

   hep-phActa Phys.Polon.B(2015)·9 citations
10. 10*

    Heavy-Quark QCD Exotica

    Richard F. Lebed🇺🇸 · Ryan E. Mitchell🇺🇸 · Eric S. Swanson🇺🇸

    This review presents an overview of the remarkable progress in the field of heavy-quark exotic hadrons over the past 15 years. It seeks to be pedagogical rather than exhaustive, summarizing both the progress and specific results of experimental discoveries, and the variety of theoretical approaches designed to explain these new states.

    hep-phhep-exnucl-exnucl-thPPNP(2017)·854 citations
11. 11*

    Polarization of photons emitted by decaying dark matter

    W. Bonivento🇮🇹 · D. Gorbunov🇷🇺 · M. Shaposhnikov🇨🇭 · A. Tokareva🇷🇺

    Radiatively decaying dark matter may be searched through investigating the photon spectrum of galaxies and galaxy clusters. We explore whether the properties of dark matter can be constrained through the study of a polarization state of emitted photons. Starting from the basic principles of quantum mechanics we show that the models of symmetric dark matter are indiscernible by the photon polarization. However, we find that the asymmetric dark matter consisted of Dirac fermions is a source of circularly polarized photons, calling for the experimental determination of the photon state.

    hep-phPLB(2017)·16 citations
12. 12*

    The Supersymmetric Effective Field Theory of Inflation

    Luca V. Delacretaz🇺🇸 · Victor Gorbenko🇺🇸 · Leonardo Senatore🇺🇸

    We construct the Supersymmetric Effective Field Theory of Inflation, that is the most general theory of inflationary fluctuations when time-translations and supersymmetry are spontaneously broken. The non-linear realization of these invariances allows us to define a complete SUGRA multiplet containing the graviton, the gravitino, the Goldstone of time translations and the Goldstino, with no auxiliary fields. Going to a unitary gauge where only the graviton and the gravitino are present, we write the most general Lagrangian built out of the fluctuations of these fields, invariant under time-dependent spatial diffeomorphisms, but softly-breaking time diffeomorphisms and gauged SUSY. With a suitable Stückelberg transformation, we introduce the Goldstone boson of time translation and the Goldstino of SUSY. No additional dynamical light field is needed. In the high energy limit, larger than the inflationary Hubble scale for the Goldstino, these fields decouple from the graviton and the gravitino, greatly simplifying the analysis in this regime. We study the phenomenology of this Lagrangian. The Goldstino can have a non-relativistic dispersion relation. Gravitino and Goldstino affect the primordial curvature perturbations at loop level. The UV modes running in the loops generate three-point functions which are degenerate with the ones coming from operators already present in the absence of supersymmetry. Their size is potentially as large as corresponding to $f_{\mathrm{NL}}^{equil.,orthog.}\sim 1$ or, for particular operators, even $\gg 1$. The non-degenerate contribution from modes of order $H$ is estimated to be very small.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2017)·59 citations
13. 13*

    Pulsar timing can constrain primordial black holes in the LIGO mass window

    Katelin Schutz🇺🇸 · Adrian Liu🇺🇸

    The recent discovery of gravitational waves from merging black holes has generated interest in primordial black holes as a possible component of the dark matter. In this paper, we show that pulsar timing may soon have sufficient data to constrain $1$-$1000M_{\odot }$ primordial black holes via the non-detection of a third-order Shapiro time delay as the black holes move around the Galactic halo. We present the results of a Monte Carlo simulation which suggests that future data from known pulsars may be capable of constraining the PBH density more stringently than other existing methods in the mass range ~1-30$M_{\odot }$. We find that timing new pulsars discovered using the proposed Square Kilometre Array may constrain primordial black holes in this mass range to comprise less than ~1-10% of the dark matter.

    ↳ astro-ph.COhep-phPRD(2017)·77 citations
14. 14*

    Revisiting the Dark Matter - Comet Shower Connection

    Eric David Kramer🇺🇸 · Michael Rowan

    We revisit the question of whether the observed periodicity of comet impacts on Earth is consistent with Solar oscillation about the Galactic midplane and spiral arm crossings, here in the context of dissipative dark matter models. Consider whether a hypothetical thin dark disk, a signature of these models, is necessary to give the right periodicity, and whether such a dark disk is allowed given kinematic and other observational constraints on the Galaxy's gravitational potential, taking into account recent updates of these limits based on the vertical epicyclic oscillations of the tracer populations. Our analysis contains updated parameters for the Galactic disk, a self-consistent gravitational potential under the Poisson-Jeans equations, and includes prior probabilities from local stellar kinematics and the distribution of Milky Way interstellar gas. Moreover, our analysis also includes radial oscillations and Galactic spiral arm crossings. We find a dark disk explanation for the comet periodicity to be 10 times more likely than a constant average rate model. Moreover, we find that spiral arm crossing is necessary to correctly predict the date of the Chicxulub crater dated to 66 My ago.

    ↳ astro-ph.EPastro-ph.GAhep-ph4 citations
15. 15*

    A Bump in the Blue Axion Isocurvature Spectrum

    Daniel J. H. Chung🇺🇸 · Amol Upadhye🇺🇸

    Blue axion isocurvature perturbations are both theoretically well-motivated and interesting from a detectability perspective. These power spectra generically have a break from the blue region to a flat region. Previous investigations of the power spectra were analytic, which left a gap in the predicted spectrum in the break region due to the non-applicability of the used analytic techniques. We therefore compute the isocurvature spectrum numerically for an explicit supersymmetric axion model. We find a bump that enhances the isocurvature signal for this class of scenarios. A fitting function of three parameters is constructed that fits the spectrum well for the particular axion model we study. This fitting function should be useful for blue isocurvature signal hunting in data and making experimental sensitivity forecasts.

    ↳ astro-ph.COgr-qchep-phPRD(2017)·16 citations
16. 16*

    Complex angular momenta approach for scattering problems in the presence of both monopoles and short range potentials

    Fabrizio Canfora🇨🇱

    It is analyzed the quantum mechanical scattering off a topological defect (such as a Dirac monopole) as well as a Yukawa-like potential(s) representing the typical effects of strong interactions. This system, due to the presence of a short-range potential, can be analyzed using the powerful technique of the complex angular momenta which, so far, has not been employed in the presence of monopoles (nor of other topological solitons). Due to the fact that spatial spherical symmetry is achieved only up to internal rotations, the partial wave expansion becomes very similar to the Jacob-Wick helicity amplitudes for particles with spin. However, since the angular-momentum operator has an extra "internal" contribution, fixed cuts in the complex angular momentum plane appear. Correspondingly, the background integral in the Regge formula does not decrease for large values of cos(Theta) (namely, large values of the Mandelstam variable s). Hence, the experimental observation of this kind of behavior could be a direct signal of non-trivial topological structures in strong interactions. The possible relations of these results with the soft Pomeron are shortly analyzed.

    ↳ hep-thhep-phnucl-thPRD(2016)·1 citation
17. 17*

    New Projects on Dark Photon Search

    V. Kozhuharov🇧🇬 · M. Raggi🇮🇹 · P. Valente🇮🇹

    Despite the great success of the Standard Model of particle physics the nature of Dark Matter still remains unclear. Recently, the idea of the existence of a hidden sector coupling only weakly with the ordinary matter was revitalized and gained popularity. A simple mediator between the hidden and the visible sector could be a vector particle of a new gauge interaction, the so called dark photon. Numerous of activities were initiated to probe its parameter space. The present results and the foreseen experiments aimed to search for dark photons in few directions are reviewed and discussed.

    ↳ hep-exhep-phFrascati Phys.Ser.(2017)·3 citations
18. 18*

    $\eta$ bound state: theory and experiment

    Hartmut Machner🇩🇪

    The search for a quasi bound $\eta$ meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally.

    ↳ nucl-exhep-phnucl-thEPJ Web Conf.(2017)·1 citation
19. 19*

    Proton-proton fusion and tritium $\beta$-decay from lattice quantum chromodynamics

    Martin J. Savage🇺🇸 · Phiala E. Shanahan🇺🇸 · Brian C. Tiburzi🇺🇸 · Michael L. Wagman🇺🇸 · Frank Winter🇺🇸 · Silas R. Beane🇺🇸 · Emmanuel Chang🇺🇸 · Zohreh Davoudi🇺🇸 · William Detmold🇺🇸 · Kostas Orginos🇺🇸

    The nuclear matrix element determining the $pp\to d{e}^{+}\nu$ fusion cross section and the Gamow-Teller matrix element contributing to tritium $\beta$-decay are calculated with lattice Quantum Chromodynamics (QCD) for the first time. Using a new implementation of the background field method, these quantities are calculated at the SU(3)-flavor-symmetric value of the quark masses, corresponding to a pion mass of $m_{\pi }$ ~ 806 MeV. The Gamow-Teller matrix element in tritium is found to be 0.979(03)(10) at these quark masses, which is within $2\sigma$ of the experimental value. Assuming that the short-distance correlated two-nucleon contributions to the matrix element (meson-exchange currents) depend only mildly on the quark masses, as seen for the analogous magnetic interactions, the calculated $pp\to d{e}^{+}\nu$ transition matrix element leads to a fusion cross section at the physical quark masses that is consistent with its currently accepted value. Moreover, the leading two-nucleon axial counterterm of pionless effective field theory is determined to be $L_{1,A}=3.9(0.1)(1.0)(0.3)(0.9){\mathrm{fm}}^3$ at a renormalization scale set by the physical pion mass, also in agreement with the accepted phenomenological range. This work concretely demonstrates that weak transition amplitudes in few-nucleon systems can be studied directly from the fundamental quark and gluon degrees of freedom and opens the way for subsequent investigations of many important quantities in nuclear physics.

    ↳ hep-lathep-phnucl-thPRL(2017)·116 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.