Mon·Mar 12, 2018Monday·March 12, 2018

1. 01*

   Axion energy density, bottle neck period, and $\bar{\theta }$ ratios between early and late times

   Jihn E. Kim🇰🇷 · Se-Jin Kim · Soonkeon Nam🇰🇷

   The possibility of the "invisible" axion being cold dark matter relies on the acceptable estimates of the current axion energy density. The estimate depends on the nature of QCD phase transition at a few hundred MeV and the evolution of the misalignment angle $\bar{\theta }$. The onset of $\bar{\theta }$ oscillation undergoes a bottleneck period which occurred during the QCD phase transition. In addition, the anharmonic coupling of order $a^4$ affects the $\bar{\theta }$ evolution. From the time that the anharmonic effect is negligible, it is rather simple to calculate the ratio of $\bar{\theta }$'s between early and late times. For multi GHz oscillations, the current age of the Universe needs at least $10^{27}$ oscillations which limits an exact calculation of $\bar{\theta }$ . We establish a stepwise approximation for numerical solutions of the differential equation and obtain ${\bar{\theta }}_{\mathrm{now}}/{\bar{\theta }}_f\approx 3\times 10^{-17}$ for $m_a\simeq 10^{-4}$eV, where $t_f$ is the first time that the full hadronic phase (after the QCD phase transition) was established.

   hep-phastro-ph.COhep-exhep-lat5 citations
2. 02*

   Probing heavy ion collisions using quark and gluon jet substructure

   Yang-Ting Chien🇺🇸 · Raghav Kunnawalkam Elayavalli🇺🇸

   We study the phenomenon of jet quenching utilizing quark and gluon jet substructures as independent probes of heavy ion collisions. We exploit jet and subjet features to highlight differences between quark and gluon jets in vacuum and in a medium with the jet-quenching model implemented in JEWEL. We begin with a physics-motivated, multivariate analysis of jet substructure observables including the jet mass, the radial moments, the $p_T^D$ and the pixel multiplicity. In comparison, we employ state-of-the-art image-recognition techniques by training a deep convolutional neutral network on jet images. To systematically extract jet substructure information, we introduce the telescoping deconstruction framework exploiting subjet kinematics at multiple angular scales. We draw connections to the soft-drop subjet distribution and illuminate medium-induced jet modifications using Lund diagrams. We find that the quark gluon discrimination performance worsens in heavy ion jets due to significant soft event activity affecting the soft jet substructure. Our work suggests a systematically improvable framework for studying modifications to quark and gluon jet substructures and facilitating direct comparisons between theoretical calculations, simulations and measurements in heavy ion collisions.

   hep-ph63 citations
3. 03*

   Constraining Extended Scalar Sectors at the LHC and beyond

   Agnieszka Ilnicka🇨🇭 · Tania Robens🇭🇺 · Tim Stefaniak🇩🇪

   We give a brief overview of beyond the Standard Model (BSM) theories with an extended scalar sector and their phenomenological status in the light of recent experimental results. We discuss the relevant theoretical and experimental constraints, and show their impact on the allowed parameter space of two specific models: the real scalar singlet extension of the Standard Model (SM) and the Inert Doublet Model. We emphasize the importance of the LHC measurements, both the direct searches for additional scalar bosons, as well as the precise measurements of properties of the Higgs boson of mass 125 GeV. We show the complementarity of these measurements to electroweak and dark matter observables.

   hep-phMod.Phys.Lett.A(2018)·108 citations
4. 04*

   A Ranking Method For Selection Of $\mathrm{H}$ Mesons In High Multiplicity Events

   A. Bingül🇹🇷 · U. Şaşmaz🇹🇷 · A. J. Beddall🇹🇷

   The selection of $\eta$ mesons with a high efficiency and a high purity can be important in the formation of statistically significant invariant mass spectra in the reconstruction of short-lived particles such as ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}\eta$. In this study, a cut-based standard method and a Ranking method to reduce combinatorial background in the reconstruction of $\eta \to \gamma \gamma$ decays in high multiplicity hadronic events are presented. By using recorded ALEPH data and fully simulated events, the performances of the methods are compared. Results show that the Ranking method yields significant improvements in the purity of the selected $\eta$ meson relative to the standard method.

   hep-phhep-exActa Phys.Polon.B(2018)·0 citations
5. 05*

   The groomed and ungroomed jet mass distribution for inclusive jet production at the LHC

   Zhong-Bo Kang🇺🇸 · Kyle Lee🇺🇸 · Xiaohui Liu🇨🇳 · Felix Ringer🇺🇸

   We study jet mass distributions measured in the single inclusive jet production in proton-proton collisions $pp\to \text{jet}+X$ at the LHC. We consider both standard ungroomed jets as well as soft drop groomed jets. Within the Soft Collinear Effective Theory (SCET), we establish QCD factorization theorems for both cases and we study their relation. The developed framework allows for the joint resummation of several classes of logarithmic corrections to all orders in the strong coupling constant. For the ungroomed case, we resum logarithms in the jet radius parameter and in the small jet mass. For the groomed case, we resum in addition the logarithms in the soft threshold parameter $z_{\text{cut}}$ which is introduced by the soft drop grooming algorithm. In this way, we are able to reliably determine the absolute normalization of the groomed jet mass distribution in proton-proton collisions. All logarithmic corrections are resummed to the next-to-leading logarithmic accuracy. We present numerical results and compare with the available data from the LHC. For both the groomed and ungroomed jet mass distributions we find very good agreement after including non-perturbative corrections.

   hep-phhep-exnucl-exnucl-thJHEP(2018)·64 citations
6. 06*

   The Hyperbolic Higgs

   Timothy Cohen🇺🇸 · Nathaniel Craig🇺🇸 · Gian F. Giudice🇨🇭 · Matthew McCullough🇨🇭

   We introduce the Hyperbolic Higgs, a novel solution to the little hierarchy problem that features Standard Model neutral scalar top partners. At one-loop order, the protection from ultraviolet sensitivity is due to an accidental non-compact symmetry of the Higgs potential that emerges in the infrared. Once the general features of the effective description are detailed, a completion that relies on a five dimensional supersymmetric framework is provided. Novel phenomenology is compared and contrasted with the Twin Higgs scenario.

   hep-phJHEP(2018)·74 citations
7. 07*

   Neutrino Discovery Limit of Dark Matter Direct Detection Experiments in the Presence of Non-Standard Interactions

   M. C. Gonzalez-Garcia🇪🇸 · Michele Maltoni🇪🇸 · Yuber F. Perez-Gonzalez🇧🇷 · Renata Zukanovich Funchal🇧🇷

   The detection of coherent neutrino-nucleus scattering by the COHERENT collaboration has set on quantitative grounds the existence of an irreducible neutrino background in direct detection searches of Weakly Interacting Massive Dark Matter candidates. This background leads to an ultimate discovery limit for these experiments: a minimum Dark Matter interaction cross section below which events produced by the coherent neutrino scattering will mimic the Dark Matter signal, the so-called \emph{neutrino floor}. In this work we study the modification of such neutrino floor induced by non-standard neutrino interactions within their presently allowed values by the global analysis of oscillation and COHERENT data. By using the full likelihood information of such global analysis we consistently account for the correlated effects of non-standard neutrino interactions both in the neutrino propagation in matter and in its interaction in the detector. We quantify their impact on the neutrino floor for five future experiments: DARWIN (Xe), ARGO (Ar), Super-CDMS HV (Ge and Si) and CRESST phase III (CaWO${}_4$). Quantitatively, we find that non-standard neutrino interactions allowed at the $3\sigma$ level can result in an increase of the neutrino floor of up to a factor $\sim 5$ with respect to the Standard Model expectations and impact the expected sensitivities of the ARGO, CRESST phase III and DARWIN experiments.

   hep-phJHEP(2018)·74 citations
8. 08*

   Singlet Scalar Top Partners from Accidental Supersymmetry

   Hsin-Chia Cheng🇺🇸 · Lingfeng Li🇺🇸 · Ennio Salvioni🇩🇪 · Christopher B. Verhaaren🇺🇸

   We present a model wherein the Higgs mass is protected from the quadratic one-loop top quark corrections by scalar particles that are complete singlets under the Standard Model (SM) gauge group. While bearing some similarity to Folded Supersymmetry, the construction is purely four dimensional and enjoys more parametric freedom, allowing electroweak symmetry breaking to occur easily. The cancelation of the top loop quadratic divergence is ensured by a $Z_3$ symmetry that relates the SM top sector and two hidden top sectors, each charged under its own hidden color group. In addition to the singlet scalars, the hidden sectors contain electroweak-charged supermultiplets below the TeV scale, which provide the main access to this model at colliders. The phenomenology presents both differences and similarities with respect to other realizations of neutral naturalness. Generally, the glueballs of hidden color have longer decay lengths. The production of hidden sector particles results in quirk or squirk bound states, which later annihilate. We survey the possible signatures and corresponding experimental constraints.

   hep-phJHEP(2018)·67 citations
9. 09*

   Off-equilibrium corrections to energy and conserved charge densities in the relativistic fluid in heavy-ion collisions

   Akihiko Monnai🇫🇷

   Dissipative processes in relativistic fluids are known to be important in the analyses of the hot QCD matter created in high-energy heavy-ion collisions. In this work, I consider dissipative corrections to energy and conserved charge densities, which are conventionally assumed to be vanishing but could be finite. Causal dissipative hydrodynamics is formulated in the presence of those dissipative currents. The relation between hydrodynamic stability and transport coefficients is discussed. I then study their phenomenological consequences on the observables of heavy-ion collisions in numerical simulations. It is shown that particle spectra and elliptic flow can be visibly modified.

   ↳ nucl-thhep-phnucl-exPRC(2018)·11 citations
10. 10*

    Quantum-Classical Computation of Schwinger Model Dynamics using Quantum Computers

    N. Klco🇺🇸 · E. F. Dumitrescu🇺🇸 · A. J. McCaskey🇺🇸 · T. D. Morris🇺🇸 · R. C. Pooser🇺🇸 · M. Sanz🇪🇸 · E. Solano🇪🇸 · P. Lougovski🇺🇸 · M. J. Savage🇺🇸

    We present a quantum-classical algorithm to study the dynamics of the two-spatial-site Schwinger model on IBM's quantum computers. Using rotational symmetries, total charge, and parity, the number of qubits needed to perform computation is reduced by a factor of $\sim 5$, removing exponentially-large unphysical sectors from the Hilbert space. Our work opens an avenue for exploration of other lattice quantum field theories, such as quantum chromodynamics, where classical computation is used to find symmetry sectors in which the quantum computer evaluates the dynamics of quantum fluctuations.

    ↳ quant-phhep-lathep-phhep-th+1PRA(2018)·524 citations
11. 11*

    Bounds on Dark Matter annihilations from 21 cm data

    Guido D'Amico🇨🇭 · Paolo Panci🇨🇭 · Alessandro Strumia🇮🇹

    The observation of an absorption feature in the 21 cm spectrum at redshift $z\approx 17$ implies bounds on Dark Matter annihilations for a broad range of masses, given that significant heating of the intergalactic medium would have erased such feature. The resulting bounds on the DM annihilation cross sections are comparable to the strongest ones from all other observables.

    ↳ astro-ph.COhep-phPRL(2018)·134 citations
12. 12*

    Converting non-relativistic dark matter to radiation

    Torsten Bringmann🇳🇴 · Felix Kahlhoefer🇩🇪 · Kai Schmidt-Hoberg🇩🇪 · Parampreet Walia🇳🇴

    Dark matter in the cosmological concordance model is parameterised by a single number, describing the covariantly conserved energy density of a non-relativistic fluid. Here we test this assumption in a model-independent and conservative way by considering the possibility that, at any point during the cosmological evolution, dark matter may be converted into a non-interacting form of radiation. This scenario encompasses, but is more general than, the cases where dark matter decays or annihilates into these states. We show that observations of the cosmic microwave background allow to strongly constrain this scenario for any conversion time after big bang nucleosynthesis. We discuss in detail, both from a Bayesian and frequentist point of view, in which sense adding large-scale structure observations may even provide a certain preference for a conversion of dark matter to radiation at late times. Finally we apply our general results to a specific particle physics realisation of such a scenario, featuring late kinetic decoupling and Sommerfeld-enhanced dark matter annihilation. We identify a small part of parameter space that both mitigates the tension between cosmic microwave and large-scale structure data and allows for velocity-dependent dark matter self-interactions strong enough to address the small-scale problems of structure formation.

    ↳ astro-ph.COhep-phPRD(2018)·129 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.