Mon·Apr 2, 2018Monday·April 2, 2018

1. 01*

   Is natural higgsino-only dark matter excluded?

   Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Dibyashree Sengupta🇺🇸 · Xerxes Tata🇺🇸

   The requirement of electroweak naturalness in supersymmetric (SUSY) models of particle physics necessitates light higgsinos not too far from the weak scale characterized by m(weak)~ m(W,Z,h)~100 GeV. On the other hand, LHC Higgs mass measurements and sparticle mass limits point to a SUSY breaking scale in the multi-TeV regime. Under such conditions, the lightest SUSY particle is expected to be a mainly higgsino-like neutralino with non-negligible gaugino components (required by naturalness). The computed thermal WIMP abundance in natural SUSY models is then found to be typically a factor 5-20 below its measured value. To gain concordance with observations, either an additional DM particle (the axion is a well-motivated possibility) must be present or additional non-thermal mechanisms must augment the neutralino abundance. We compare present direct and indirect WIMP detection limits to three natural SUSY models based on gravity-, anomaly- and mirage-mediation. We show that the case of natural higgsino-only dark matter where non-thermal production mechanisms augment its relic density, is essentially excluded by a combination of direct detection constraints from PandaX-II, LUX and Xenon-1t experiments, and by bounds from Fermi-LAT/MAGIC observations of gamma rays from dwarf spheroidal galaxies.

   hep-phastro-ph.COEPJC(2018)·61 citations
2. 02*

   Semileptonic decay of $B_c^{-}$ into $X(3930)$, $X(3940)$, $X(4160)$

   Natsumi Ikeno🇯🇵 · Melahat Bayar🇹🇷 · Eulogio Oset🇪🇸

   We study the semileptonic decay of $B_c^{-}$ meson into $\bar{\nu }{l}^{-}$ and the isospin zero $X(3930)(2^{++})$, $X(3940)(0^{++})$, $X(4160)(2^{++})$ resonances. We look at the reaction from the perspective that these resonaces appear as dynamically generated from the vector-vector interaction in the charm sector, and couple strongly to $D^{\ast }\overline{D^{\ast }}$ and $D_s^{\ast }\overline{D_s^{\ast }}$. We also look into the $B_c^{-}\to {\bar{\nu }}_l{l}^{-}{D}^{\ast }\overline{D^{\ast }}$ and $B_c^{-}\to {\bar{\nu }}_l{l}^{-}{D}_s^{\ast }\overline{D_s^{\ast }}$ reactions close to threshold and relate the $D^{\ast }\overline{D^{\ast }}$ and $D_s^{\ast }\overline{D_s^{\ast }}$ mass distribution to the rate of production of the $X$ resonances.

   hep-phnucl-thEPJC(2018)·5 citations
3. 03*

   LSZ-reduction, resonances and non-diagonal propagators: gauge fields

   Adrian Lewandowski (Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern)🇨🇭

   We analyze in the Landau gauge mixing of bosonic fields in gauge theories with exact and spontaneously broken symmetries, extending to this case the Lehmann-Symanzik-Zimmermann (LSZ) formalism of the asymptotic fields. Factorization of residues of poles (at real and complex values of the variable $p^2$) is demonstrated and a simple practical prescription for finding the "square-rooted" residues, necessary for calculating $S$-matrix elements, is given. The pseudo-Fock space of asymptotic (in the LSZ sense) states is explicitly constructed and its BRST-cohomological structure is elucidated. Usefulness of these general results, obtained by investigating the relevant set of Slavnov-Taylor identities, is illustrated on the one-loop examples of the $Z^0$-photon mixing in the Standard Model and the $G_Z$-Majoron mixing in the singlet Majoron model.

   hep-phhep-thNPB(2018)·6 citations
4. 04*

   The $B_c(B_c^{\ast })$ meson production via the proton-nucleus and the nucleus-nucleus collision modes at the colliders RHIC and LHC

   Gu Chen🇨🇳 · Chao-Hsi Chang🇨🇳 · Xing-Gang Wu🇨🇳

   In the paper, we make a comprehensive study on the hadroproduction of the $B_c(B_c^{\ast })$ meson via the gluon-gluon fusion mechanism at the RHIC and LHC colliders. Total and differential cross sections via the proton-nucleus ($p$-N) and nucleus-nucleus (N-N) collision modes have been discussed under various collision energies. To compare with those via the proton-proton collision mode at the LHC, we observe that sizable number of $B_c(B_c^{\ast })$-meson events can also be produced via the $p$-N and N-N collision modes at the RHIC and LHC. If assuming the spin-triplet $B_c^{\ast }$ meson directly decays to the spin-singlet $B_c$ meson with $100\%$ probability, $1.2\times 10^5$ and $4.7\times 10^5$ $B_c$-meson events can be produced via the $p$-Au and Au-Au collision modes at the RHIC in one operation year; $5.8\times 10^6$ and $4.6\times 10^6$ $B_c$-meson events can be produced via the $p$-Pb and Pb-Pb collision modes at the LHC in one operation year.

   hep-phPRD(2018)·23 citations
5. 05*

   Radiative transitions between $0^{-+}$ and $1^{--}$ heavy quarkonia on the light front

   Meijian Li🇺🇸 · Yang Li🇺🇸 · Pieter Maris🇺🇸 · James P. Vary🇺🇸

   We present calculations of radiative transitions between vector and pseudoscalar quarkonia in the light-front Hamiltonian approach. The valence sector light-front wavefunctions of heavy quarkonia are obtained from the Basis Light-Front Quantization (BLFQ) approach in a holographic basis. We study the transition form factor with both the traditional "good current" $J^{+}$ and the transverse current ${\vec{J}}_{\perp }$ (in particular, $J^R=J^x+i{J}^y$). This allows us to investigate the role of rotational symmetry by considering vector mesons with different magnetic projections ($m_j=0,\pm 1$). We use the $m_j=0$ state of the vector meson to obtain the transition form factor, since this procedure employs the dominant spin components of the light-front wavefunctions and is more robust in practical calculations. While the $m_j=\pm 1$ states are also examined, transition form factors depend on subdominant components of the light-front wavefunctions and are less robust. Transitions between states below the open-flavor thresholds are computed, including those for excited states. Comparisons are made with the experimental measurements as well as with Lattice QCD and quark model results. In addition, we apply the transverse current to calculate the decay constant of vector mesons where we obtain consistent results using either $m_j=0$ or $m_j=1$ light-front wavefunctions. This consistency provides evidence for features of rotational symmetry within the model.

   hep-phnucl-thPRD(2018)·47 citations
6. 06*

   Upgoing ANITA events as evidence of the CPT symmetric universe

   Luis A. Anchordoqui🇺🇸 · Vernon Barger🇺🇸 · John G. Learned🇺🇸 · Danny Marfatia🇺🇸 · Thomas J. Weiler🇺🇸

   We explain the two upgoing ultra-high energy shower events observed by ANITA as arising from the decay in the Earth's interior of the quasi-stable dark matter candidate in the CPT symmetric universe. The dark matter particle is a 480 PeV right-handed neutrino that decays into a Higgs boson and a light Majorana neutrino. The latter interacts in the Earth's crust to produce a tau lepton that in turn initiates an atmospheric upgoing shower. The fact that both events emerge at the same angle from the Antarctic ice-cap suggests an atypical dark matter density distribution in the Earth.

   hep-phastro-ph.HELHEP(2018)·59 citations
7. 07*

   Self-Organized Higgs Criticality

   Cem Eröncel🇺🇸 · Jay Hubisz🇺🇸 · Gabriele Rigo🇺🇸

   The critical point for a Higgs sector can be a point of interest in the potential for a modulus field such as the radion of an extra dimensional construction, or the dilaton of spontaneously broken approximate conformal invariance. In part motivated by conjectures about the self-organized critical state in statistical physics, we construct a 5D model in which there is an infrared emergent Higgs instability due to violation of the Breitenlohner-Freedman bound deep in the interior of a near AdS geometry. This is holographically dual to a "running" scaling dimension transitioning from real to complex with decreasing scale. The complex scaling indicates an instability to be resolved by condensates which modify the interior geometry and backreact on the 5D radion potential. Studying the model at small gravitational backreaction, we find a rich possible vacuum structure and uncover evidence that resolution of the instability requires a non-trivial cosmology.

   hep-phcond-mat.str-elhep-thJHEP(2019)·16 citations
8. 08*

   Minimal Models for Dark Matter and the Muon g-2 Anomaly

   Lorenzo Calibbi🇨🇳 · Robert Ziegler🇩🇪 · Jure Zupan🇺🇸

   We construct models with minimal field content that can simultaneously explain the muon g-2 anomaly and give the correct dark matter relic abundance. These models fall into two general classes, whether or not the new fields couple to the Higgs. For the general structure of models without new Higgs couplings, we provide analytical expressions that only depend on the $SU(2{)}_L$ representation. These results allow to demonstrate that only few models in this class can simultaneously explain $(g-2{)}_{\mu }$ and account for the relic abundance. The experimental constraints and perturbativity considerations exclude all such models, apart from a few fine-tuned regions in the parameter space, with new states in the few 100 GeV range. In the models with new Higgs couplings, the new states can be parametrically heavier by a factor $\sqrt{1/y_{\mu }}$, with $y_{\mu }$ the muon Yukawa coupling, resulting in masses for the new states in the TeV regime. At present these models are not well constrained experimentally, which we illustrate on two representative examples.

   hep-phhep-exJHEP(2018)·104 citations
9. 09*

   Probing confinement by direct photons and dileptons

   V.V. Goloviznin🇺🇦 · A.V. Nikolskii🇷🇺 · A.M. Snigirev🇷🇺 · G.M. Zinovjev🇺🇦

   The intensive synchrotron radiation resulting from quarks interacting with the collective confining color field in relativistic heavy ion collisions is discussed. The spectrum of photons with large transverse momentum is calculated and compared with the experimental data to demonstrate the feasibility of this type of radiation. A study of the earlier predicted azimuthal anisotropy in the angular distribution of dileptons with respect to the three-momentum of the pair is performed as well. This boundary-induced mechanism of lepton pair production is shown to possess the features that are distinctly different from the standard mechanisms and can potentially provide an efficient probe of quark-gluon plasma formation.

   hep-phnucl-exnucl-thEPJA(2019)·6 citations
10. 10*

    Correlations and Event-by-Event Fluctuations in High Multiplicity Events Produced in ${}^{208}$Pb-${}^{208}$Pb Collisions

    Shakeel Ahmad🇮🇳 · Shaista Khan🇮🇳 · Ashwini Kumar🇮🇳 · Arpit Singh🇮🇳 · A. Ahmad🇮🇳 · B. K. Singh🇮🇳

    Analysis of high multiplicity events produced in 158A GeV/c ${}^{208}$Pb-${}^{208}$Pb collisions is carried out to study the event-by-event fluctuations. The findings reveal that the method of scaled factorial moments can be used to identify the events having densely populated narrow phase space bins. A few events sorted out adopting this approach are individually analyzed. It is observed that these events do exhibit large fluctuations in their pseudorapidity, $\eta$ and azimuthal angle, $\varphi$ distributions arising out due to some dynamical reasons. Two particle $\Delta \eta$-$\Delta \varphi$ correlation study applied to these events too indicates that some complex two-dimensional structure of significantly high magnitude are present in these events which might have some dynamical origin. The findings reveal that the method of scaled factorial moments may be used as an effective triggering for events with large dynamical fluctuations.

    ↳ hep-exhep-phnucl-exAdv.High Energy Phys.(2018)·2 citations
11. 11*

    Quantum Sensing for High Energy Physics

    Zeeshan Ahmed🇺🇸 · Yuri Alexeev🇺🇸 · Giorgio Apollinari🇺🇸 · Asimina Arvanitaki🇨🇦 · David Awschalom🇺🇸 · Karl K. Berggren🇺🇸 · Karl Van Bibber🇺🇸 · Przemyslaw Bienias🇺🇸 · Geoffrey Bodwin🇺🇸 · Malcolm Boshier🇺🇸 · Daniel Bowring🇺🇸 · Davide Braga🇺🇸 and 104 other authors

    Report of the first workshop to identify approaches and techniques in the domain of quantum sensing that can be utilized by future High Energy Physics applications to further the scientific goals of High Energy Physics.

    ↳ hep-exhep-phphysics.ins-det24 citations
12. 12*

    Damping of gravitational waves in a viscous Universe and its implication for dark matter self-interactions

    Bo-Qiang Lu🇨🇳 · Da Huang🇵🇱 · Yue-Liang Wu🇨🇳 · Yu-Feng Zhou🇨🇳

    It is well known that a gravitational wave (GW) experiences the damping effect when it propagates in a fluid with nonzero shear viscosity. In this paper, we propose a new method to constrain the GW damping rate and thus the fluid shear viscosity. By defining the effective distance which incorporates damping effects, we can transform the GW strain expression in a viscous Universe into the same form as that in a perfect fluid. Therefore, the constraints of the luminosity distances from the observed GW events by LIGO and Virgo can be directly applied to the effective distances in our formalism. We exploit the lognormal likelihoods for the available GW effective distances and a Gaussian likelihood for the luminosity distance inferred from the electromagnetic radiation observation of the binary neutron star merger event GW170817. Our fittings show no obvious damping effects in the current GW data, and the upper limit on the damping rate with the combined data is $6.75\times 10^{-4}{\mathrm{Mpc}}^{-1}$ at 95\% confidence level. By assuming that the dark matter self-scatterings are efficient enough for the hydrodynamic description to be valid, we find that a GW event from its source at a luminosity distance $D\gtrsim 10^4\mathrm{Mpc}$ can be used to put a constraint on the dark matter self-interactions.

    ↳ astro-ph.HEhep-ph15 citations
13. 13*

    Problems With the MINOS/MINOS+ Sterile Neutrino Muon-Neutrino Disappearance Result

    William C. Louis🇺🇸

    The MINOS/MINOS+ experiment has recently reported stringent limits on ${\nu }_{\mu }$ disappearance that appear to rule out the 3+1 sterile neutrino model. However, in this paper we wish to point out problems associated with the MINOS/MINOS+ analysis. In particular, we find that MINOS/MINOS+ has either underestimated their systematic errors and/or has obtained evidence for physics beyond the 3-neutrino paradigm. Either case would invalidate the limits on ${\nu }_{\mu }$ disappearance.

    ↳ hep-exhep-ph8 citations
14. 14*

    Critical Points at Infinity, Non-Gaussian Saddles, and Bions

    Alireza Behtash🇺🇸 · Gerald V. Dunne🇺🇸 · Thomas Schaefer🇺🇸 · Tin Sulejmanpasic🇫🇷 · Mithat Unsal🇺🇸

    It has been argued that many non-perturbative phenomena in quantum mechanics (QM) and quantum field theory (QFT) are determined by complex field configurations, and that these contributions should be understood in terms of of Picard-Lefschetz theory. In this work we compute the contribution from non-BPS multi-instanton configurations, such as instanton-anti-instanton $[I\bar{I}]$ pairs, and argue that these contributions should be interpreted as exact critical points at infinity. The Lefschetz thimbles associated with such critical points have a specific structure arising from the presence of non-Gaussian, quasi-zero mode (QZM), directions. When fermion degrees of freedom are present, as in supersymmetric theories, the effective bosonic potential can be written as the sum of a classical and a quantum potential. We show that in this case the semi-classical contribution of the critical point at infinity vanishes, but there is a non-trivial contribution that arises from its associated non-Gaussian QZM-thimble. This approach resolves several puzzles in the literature concerning the semi-classical contribution of correlated $[I\bar{I}]$ pairs. It has the surprising consequence that the configurations that dominate the expansion of observables, and the critical points that define the Lefschetz thimble decomposition need not be the same, a feature not present in the traditional Picard-Lefschetz approach.

    ↳ hep-thhep-phJHEP(2018)·39 citations
15. 15*

    Neutrino properties from cosmology

    Martina Gerbino🇸🇪

    Precision cosmology enables to test fundamental physics, including neutrino properties, with unprecedented accuracy. In this work, I review the basics of neutrino cosmology. I briefly describe how neutrinos affect cosmological observables, such as anisotropies in the cosmic microwave background and fluctuations in the matter field. I show current constraints and projected sensitivities on the sum of the neutrino masses $\Sigma m_{\nu }$ and on the number of relativistic species $N_{\mathrm{eff}}$ from a selection of cosmological data. I finally comment about the implications of those bounds for neutrino physics.

    ↳ astro-ph.COgr-qchep-phhep-th11 citations
16. 16*

    On decay width of heavy quarkonia in QGP

    Saumen Datta🇮🇳

    Quarkonia are some of the most important probes of the medium created in relativistic heavy ion collision experiments, but it is still difficult to get quantitative results for its behavior in the plasma. Here I discuss the decay width of a heavy quarkonium system, and calculate the gluodissociation width of bottomonia. In the end I comment on study of quarkonia as open quantum systems.

    ↳ hep-lathep-ph1 citation
17. 17*

    $\gamma$-Cascade: A Simple Program to Compute Cosmological Gamma-Ray Propagation

    Carlos Blanco🇺🇸

    Modeling electromagnetic cascades during gamma-ray transport is important in many applications within astrophysics. This document introduces $\gamma$-Cascade, a publicly available Mathematica package which allows users to calculate observed gamma-ray fluxes from point sources as well as from a distribution of sources. $\gamma$-Cascade semi-analytically computes the effects of electromagnetic interactions during gamma-ray transport.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phJCAP(2019)·34 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.