Fri·Jul 28, 2017Friday·July 28, 2017

1. 01*

   Pileup Mitigation with Machine Learning (PUMML)

   Patrick T. Komiske🇺🇸 · Eric M. Metodiev🇺🇸 · Benjamin Nachman🇺🇸 · Matthew D. Schwartz🇺🇸

   Pileup involves the contamination of the energy distribution arising from the primary collision of interest (leading vertex) by radiation from soft collisions (pileup). We develop a new technique for removing this contamination using machine learning and convolutional neural networks. The network takes as input the energy distribution of charged leading vertex particles, charged pileup particles, and all neutral particles and outputs the energy distribution of particles coming from leading vertex alone. The PUMML algorithm performs remarkably well at eliminating pileup distortion on a wide range of simple and complex jet observables. We test the robustness of the algorithm in a number of ways and discuss how the network can be trained directly on data.

   hep-phhep-exstat.MLJHEP(2017)·120 citations
2. 02*

   Dark Matter and the elusive ${\mathbf{Z}}^{\prime }$ in a dynamical Inverse Seesaw scenario

   Valentina De Romeri🇪🇸 · Enrique Fernandez-Martinez🇪🇸 · Julia Gehrlein🇪🇸 · Pedro A. N. Machado🇺🇸 · Viviana Niro🇩🇪

   The Inverse Seesaw naturally explains the smallness of neutrino masses via an approximate $B-L$ symmetry broken only by a correspondingly small parameter. In this work the possible dynamical generation of the Inverse Seesaw neutrino mass mechanism from the spontaneous breaking of a gauged $U(1)$ $B-L$ symmetry is investigated. Interestingly, the Inverse Seesaw pattern requires a chiral content such that anomaly cancellation predicts the existence of extra fermions belonging to a dark sector with large, non-trivial, charges under the $U(1)$ $B-L$. We investigate the phenomenology associated to these new states and find that one of them is a viable dark matter candidate with mass around the TeV scale, whose interaction with the Standard Model is mediated by the $Z^{\prime }$ boson associated to the gauged $U(1)$ $B-L$ symmetry. Given the large charges required for anomaly cancellation in the dark sector, the $B-L$ $Z^{\prime }$ interacts preferentially with this dark sector rather than with the Standard Model. This suppresses the rate at direct detection searches and thus alleviates the constraints on $Z^{\prime }$-mediated dark matter relic abundance. The collider phenomenology of this elusive $Z^{\prime }$ is also discussed.

   hep-phJHEP(2017)·48 citations
3. 03*

   Effects of ultra-light dark matter on the gravitational quantum well

   Paolo Castorina🇮🇹 · Alfredo Iorio🇨🇿 · Michal Malinský🇨🇿

   We study the influence of a periodic perturbation of the effective masses of the nucleons, due to the assumed semi-classical ultra-light dark matter background, on the motion of neutrons in a gravitational quantum well. Our focus is on the transition probability between the lowest two energy states, with the Rabi frequency in the kHz region corresponding to the series of "sweet spot" dark matter masses in the $10^{-11}$eV ballpark. The relevant probability is written in terms of the specific mass and of the effective coupling to the ordinary matter. These parameters can be constrained by the non-observation of any significant deviations of the measured transition probabilities from the dark-matter-free picture.

   hep-phInt.J.Mod.Phys.D(2018)·0 citations
4. 04*

   Quarkonium Polarization and the Long Distance Matrix Elements Hierarchies using Jet Substructure

   Lin Dai🇺🇸 · Prashant Shrivastava🇺🇸

   We investigate the quarkonium production mechanisms in jets at the LHC, using the Fragmenting Jet Functions (FJF) approach. Specifically, we discuss the jet energy dependence of the $J/\psi$ production cross section at the LHC. By comparing the cross sections for the different NRQCD production channels (${}^1{S}_0^{[8]}$,${}^3{S}_1^{[8]}$,${}^3{P}_J^{[8]}$, and ${}^3{S}_1^{[1]}$), we find that at fixed values of energy fraction $z$ carried by the $J/\psi$, if the normalized cross section is a decreasing function of the jet energy, in particular for $z>0.5$, then the depolarizing ${}^1{S}_0^{[8]}$ must be the dominant channel. This makes the prediction made in [Baumgart et al., JHEP 1411, 003 (2014)] for the FJF's also true for the cross section. We also make comparisons between the long distance matrix elements extracted by various groups. This analysis could potentially shed light on the polarization properties of the $J/\psi$ production in high $p_T$ region.

   hep-phnucl-thPRD(2017)·10 citations
5. 05*

   A Minimal Fermion-Scalar Preonic Model

   U. Kaya🇹🇷 · B. B. Oner🇹🇷 · S. Sultansoy

   A minimal fermion-scalar preonic model containing two fermionic and one scalar preons is proposed. This scheme allows to prevent the occurrence of undesired SM-level particles, namely leptons and quarks with unusual electric charges. Similar to the previous FS models, color-octet leptons and color-sextet quarks, which are expected to have masses much lower than the compositeness scale, are predicted. Observation of these particles could provide first indications of preonic models. FCC (SppC) pp option will give opportunity to probe $m_{q_6}$ up to 48 (75) TeV and $m_{l_8}$ up to 15 (27) TeV within one year operation at nominal luminosity. FCC/SppC based ep and $\mu$p colliders will essentially enlarge covered mass region, namely, $m_{e_8}$ up to 23/27 TeV and $m_{{\mu }_8}$ up to 68/80 TeV.

   hep-phTurk.J.Phys.(2018)·5 citations
6. 06*

   Gravitino Production Suppressed by Dynamics of Sgoldstino

   Raymond T. Co🇺🇸 · Keisuke Harigaya🇺🇸

   In supersymmetric theories, the gravitino is abundantly produced in the early Universe from thermal scattering, resulting in a strong upper bound on the reheat temperature after inflation. We point out that the gravitino problem may be absent or very mild due to the early dynamics of a supersymmetry breaking field, i.e. a sgoldstino. In models of low scale mediation, the field value of the sgoldstino determines the mediation scale and is in general different in the early Universe from the present one. A large initial field value since the era of the inflationary reheating suppresses the gravitino production significantly. We investigate in detail the cosmological evolution of the sgoldstino and show that the reheat temperature may be much higher than the conventional upper bound, restoring the compatibility with thermal leptogenesis.

   hep-phJHEP(2017)·5 citations
7. 07*

   Deep-learned Top Tagging with a Lorentz Layer

   Anja Butter🇩🇪 · Gregor Kasieczka🇨🇭 · Tilman Plehn🇩🇪 · Michael Russell🇬🇧

   We introduce a new and highly efficient tagger for hadronically decaying top quarks, based on a deep neural network working with Lorentz vectors and the Minkowski metric. With its novel machine learning setup and architecture it allows us to identify boosted top quarks not only from calorimeter towers, but also including tracking information. We show how the performance of our tagger compares with QCD-inspired and image-recognition approaches and find that it significantly increases the performance for strongly boosted top quarks.

   hep-phhep-exSciPost Phys.(2018)·189 citations
8. 08*

   Neutrino oscillations in the galactic dark matter halo

   R. A. Lineros🇪🇸

   The observation of PeV neutrinos is an open window to study New Physics processes. Among all possible neutrino observables, the neutrino flavor composition can reveal underlying interactions during the neutrino propagation. We study the effects on neutrino oscillations of dark matter-neutrino interactions. We estimate the size of the interaction strength to produce a sizable deviation with respect to the flavor composition from oscillations in vacuum. We found that the dark matter distribution produces flavor compositions non reproducible by other New Physics phenomena. Besides, the dark matter effect predicts flavor compositions which depend on the neutrino's arrival direction. This feature might be observed in neutrino telescopes like IceCube and KM3NET with access to different sky sections. This effect presents a novel way to test Dark Matter particle models.

   hep-phastro-ph.HE1 citation
9. 09*

   Phenomenology of collinear photon emission from quark-gluon plasma in $AA$ collisions

   B.G. Zakharov🇷🇺

   We study the role of running coupling and the effect of variation of the thermal quark mass on contribution of the collinear bremsstrahlung and annihilation to photon emission in $AA$ collisions in a scheme similar to that used in our previous jet quenching analyses. We find that for a scenario with the thermal quark mass $m_q\sim 50-100$ MeV contribution of the higher order collinear processes summed with the $2\to 2$ processes can explain a considerable part ($\sim 50$\%) of the experimental photon spectrum at $k_T\sim 2-3$ GeV for Au+Au collisions at $\sqrt{s}=0.2$ TeV. But for $m_q=300$ MeV and for the thermal quark mass predicted by the HTL scheme the theoretical predictions underestimate considerably the experimental spectrum.

   ↳ nucl-thhep-phJETP Lett.(2017)·5 citations
10. 10*

    Towards de Sitter from 10D

    Jakob Moritz🇩🇪 · Ander Retolaza🇩🇪 · Alexander Westphal🇩🇪

    Using a 10D lift of non-perturbative volume stabilization in type IIB string theory we study the limitations for obtaining de Sitter vacua. Based on this we find that the simplest KKLT vacua with a single Kahler modulus stabilized by a gaugino condensate cannot be uplifted to de Sitter. Rather, the uplift flattens out due to stronger backreaction on the volume modulus than has previously been anticipated, resulting in vacua which are meta-stable and SUSY breaking, but that are always AdS. However, we also show that setups such as racetrack stabilization can avoid this issue. In these models it is possible to obtain supersymmetric AdS vacua with a cosmological constant that can be tuned to zero while retaining finite moduli stabilization. In this regime, it seems that de Sitter uplifts are possible with negligible backreaction on the internal volume. We exhibit this behavior also from the 10D perspective.

    ↳ hep-thastro-ph.COhep-phPRD(2018)·160 citations
11. 11*

    Holographic constraints on Bjorken hydrodynamics at finite coupling

    Brandon S. DiNunno🇺🇸 · Sašo Grozdanov🇳🇱 · Juan F. Pedraza🇳🇱 · Steve Young🇺🇸

    In large-$N_c$ conformal field theories with classical holographic duals, inverse coupling constant corrections are obtained by considering higher-derivative terms in the corresponding gravity theory. In this work, we use type IIB supergravity and bottom-up Gauss-Bonnet gravity to study the dynamics of boost-invariant Bjorken hydrodynamics at finite coupling. We analyze the time-dependent decay properties of non-local observables (scalar two-point functions and Wilson loops) probing the different models of Bjorken flow and show that they can be expressed generically in terms of a few field theory parameters. In addition, our computations provide an analytically quantifiable probe of the coupling-dependent validity of hydrodynamics at early times in a simple model of heavy-ion collisions, which is an observable closely analogous to the hydrodynamization time of a quark-gluon plasma. We find that to third order in the hydrodynamic expansion, the convergence of hydrodynamics is improved and that generically, as expected from field theory considerations and recent holographic results, the applicability of hydrodynamics is delayed as the field theory coupling decreases.

    ↳ hep-thgr-qchep-phnucl-thJHEP(2017)·22 citations
12. 12*

    QCD on a small circle

    Kyle Aitken🇺🇸 · Aleksey Cherman🇺🇸 · Erich Poppitz🇨🇦 · Laurence G. Yaffe🇺🇸

    QCD-like theories can be engineered to remain in a confined phase when compactified on an arbitrarily small circle, where their features may be studied quantitatively in a controlled fashion. Previous work has elucidated the generation of a non-perturbative mass gap and the spontaneous breaking of chiral symmetry in this regime. Here, we study the rich spectrum of hadronic states, including glueball, meson, and baryon resonances. We find an exponentially growing Hagedorn density of states, as well as the emergence of non-perturbative energy scales given by iterated exponentials of the inverse Yang-Mills coupling $g^2$.

    ↳ hep-thhep-phPRD(2017)·52 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.