Tue·Oct 18, 2016Tuesday·October 18, 2016

1. 01*

   Amplitude analysis of resonant production in three pions

   Andrew Jackura🇺🇸 · Mikhail Mikhasenko🇩🇪 · Adam Szczepaniak🇺🇸

   We present some results on the analysis of three pion resonances. The analyses are motivated by the recent release of the largest data set on diffractively produced three pions by the COMPASS collaboration. We construct reaction amplitudes that satisfy fundamental $S$-matrix principles, which allows the use of models that have physical constraints to be used in fitting data. The models are motivated by the isobar model that satisfy unitarity constraints. The model consist of a Deck production amplitude with which final state interactions are constrained by unitarity. We employ the isobar model where two of the pions form a quasi-stable particle. The analysis is performed in the high-energy, single Regge limit. We specifically discuss the examples of the three pion $J^{PC}=2^{-+}$ resonance in the $\rho \pi$ and $f_2\pi$ channels.

   hep-phEPJ Web Conf.(2016)·10 citations
2. 02*

   Make Dark Matter Charged Again

   Prateek Agrawal🇺🇸 · Francis-Yan Cyr-Racine🇺🇸 · Lisa Randall🇺🇸 · Jakub Scholtz🇺🇸

   We revisit constraints on dark matter that is charged under a $U(1)$ gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large, a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model.

   hep-phastro-ph.COJCAP(2017)·160 citations
3. 03*

   Dark Matter interpretation of low energy IceCube MESE excess

   M. Chianese🇮🇹 · G. Miele🇮🇹 · S. Morisi🇮🇹

   The 2-years MESE IceCube events show a slightly excess in the energy range 10-100 TeV with a maximum local statistical significance of 2.3$\sigma$, once a hard astrophysical power-law is assumed. A spectral index smaller than 2.2 is indeed suggested by multi-messenger studies related to $p$-$p$ sources and by the recent IceCube analysis regarding 6-years up-going muon neutrinos. In the present paper, we propose a two-components scenario where the extraterrestrial neutrinos are explained in terms of an astrophysical power-law and a Dark Matter signal. We consider both decaying and annihilating Dark Matter candidates with different final states (quarks and leptons) and different halo density profiles. We perform a likelihood-ratio analysis that provides a statistical significance up to 3.9$\sigma$ for a Dark Matter interpretation of the IceCube low energy excess.

   hep-phastro-ph.COastro-ph.HEJCAP(2017)·51 citations
4. 04*

   Novel Spectral Features in MeV Gamma Rays from Dark Matter

   Torsten Bringmann🇳🇴 · Ahmad Galea🇳🇴 · Andrzej Hryczuk🇳🇴 · Christoph Weniger🇳🇱

   Astrophysical searches for gamma rays are one of the main strategies to probe the annihilation or decay of dark matter particles. We present a new class of distinct sub-GeV spectral features that generically appear in kinematical situations where the available center-of-mass energy in such processes is just above threshold to produce excited meson states. Using a Fisher forecast with realistic astrophysical backgrounds, we demonstrate that for upcoming experiments like e-ASTROGAM and ComPair these signals can turn out to be the smoking gun in the search for particle dark matter.

   hep-phPRD(2017)·11 citations
5. 05*

   QCD next-to-leading-order predictions matched to parton showers for vector-like quark models

   Benjamin Fuks🇫🇷 · Hua-Sheng Shao🇨🇭

   Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair-production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks thanks to an accurate control of the shapes of the relevant observables and emphasize the extra handles that could be provided by novel vector-like-quark probes never envisaged so far

   hep-phhep-exEPJC(2017)·92 citations
6. 06*

   A Radiative Neutrino Model with $SU(2{)}_L$ Triplet Fields

   Takaaki Nomura🇰🇷 · Hiroshi Okada🇰🇷 · Yuta Orikasa🇰🇷

   We propose a loop induced neutrino mass model, in which we introduce several exotic fermions and bosons with $SU(2{)}_L$ multiplet, and discuss various phenomenologies such as lepton flavor violations, muon anomalous magnetic moment, nonstandard interacting neutrinoless double beta decay, relic density of dark matter, and the possibility of the spin independent direct detection searches, imposing the constraints of oblique parameters. And we show a benchmark point to satisfy all the constraints and discuss our predictions.

   hep-phPRD(2016)·19 citations
7. 07*

   On thermal production of self-interacting dark matter

   Soo-Min Choi🇰🇷 · Yoo-Jin Kang🇰🇷 · Hyun Min Lee🇰🇷

   We consider thermal production mechanisms of self-interacting dark matter in models with gauged $Z_3$ symmetry. A complex scalar dark matter is stabilized by the $Z_3$, that is the remnant of a local dark $U(1{)}_d$. Light dark matter with large self-interaction can be produced from thermal freeze-out in the presence of SM-annihilation, SIMP and/or forbidden channels. We show that dark photon and/or dark Higgs should be relatively light for unitarity and then assist the thermal freeze-out. We identify the constraints on the parameter space of dark matter self-interaction and mass in cases that one or some of the channels are important in determining the relic density.

   hep-phastro-ph.COJHEP(2016)·54 citations
8. 08*

   On the frequency distribution of neutral particles from low-energy strong interactions

   Federico Colecchia🇬🇧 · Akram Khan🇬🇧

   The rejection of the contamination, or background, from low-energy strong interactions at hadron collider experiments is a topic that has received significant attention in the field of particle physics. This article builds on a particle-level view of collision events, in line with recently-proposed subtraction methods. While conventional techniques in the field usually concentrate on probability distributions, our study is, to our knowledge, the first attempt at estimating the frequency distribution of background particles across the kinematic space inside individual collision events. In fact, while the probability distribution can generally be estimated given a model of low-energy strong interactions, the corresponding frequency distribution inside a single event typically deviates from the average and cannot be predicted a priori. We present preliminary results in this direction, and establish a connection between our technique and the particle weighting methods that have been the subject of recent investigation at the Large Hadron Collider.

   hep-phhep-exphysics.data-anAdv.High Energy Phys.(2017)·0 citations
9. 09*

   High energy effects in multi-jet production at LHC

   F. Caporale🇪🇸 · F.G. Celiberto🇮🇹 · G. Chachamis🇪🇸 · D. Gordo Gomez🇪🇸 · B. Murdaca🇮🇹 · A. Sabio Vera🇪🇸

   We study differential cross sections for the production of three and four jets in multi-Regge kinematics, the main interest lying on azimuthal angle dependences. The theoretical setup is the jet production from a single BFKL ladder with a convolution of two/three BFKL Green functions, where two forward/backward jets are always tagged in the final state. Furthermore, we require the tagging of one/two further jets in more central regions of the detectors with a relative separation in rapidity. We found, as result, that the dependence on transverse momenta and rapidities of the central jets can be considered as a distinct signal of the onset of BFKL dynamics.

   hep-phJournal of Central European Green Innovat…·21 citations
10. 10*

    Coupled-channel Dalitz plot analysis of $D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}$ decay

    Satoshi X. Nakamura (Osaka Univ.)🇯🇵

    We demonstrate that partial wave amplitudes extracted from $D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}$ Dalitz plot with a unitary coupled-channel model are significantly different from those obtained with an isobar model. The unitary coupled-channel model takes account of hadronic rescattering mechanisms involving all three mesons that have been missed in conventioanl isobar model analyses. The rescattering mechanisms contribute largely, and can triplicate the $D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}$ decay width within our analysis. These findings deliver a warning that analysis results obtained with isobar models should be looked with a caution. The determination of the CKM angle $\gamma /{\varphi }_3$ is a highly relevant problem.

    hep-phhep-exnucl-thPoS(2016)·0 citations
11. 11*

    $WWV$ $(V=\gamma ,Z)$ vertex in the Georgi-Machacek model

    M. A. Arroyo-Ureña🇲🇽 · G. Hernández-Tomé🇲🇽 · G. Tavares-Velasco🇲🇽

    The CP-even static form factors $\Delta {\kappa }_V^{\prime }$ and $\Delta Q_V$ ($V=\gamma ,Z$) associated with the $WWV$ vertex are studied in the context of the Georgi-Machacek model (GMM), which predicts nine new scalar bosons accommodated in a singlet, a triplet and a fiveplet. General expressions for the one-loop contributions to $\Delta {\kappa }_V^{\prime }$ and $\Delta Q_V$ arising from neutral, singly and doubly charged scalar bosons are obtained in terms of both parametric integrals and Passarino-Veltman scalar functions, which can be numerically evaluated. It is found that the GMM yields 15 (28) distinct contributions to $\Delta {\kappa }_{\gamma }^{\prime }$ and $\Delta Q_{\gamma }$ ($\Delta {\kappa }_Z^{\prime }$ and $\Delta Q_Z$), though several of them are naturally suppressed. A numerical analysis is done in the region of parameter space still consistent with current experimental data and it is found that the largest contributions to $\Delta {\kappa }_V^{\prime }$ arise from Feynman diagrams with two nondegenerate scalar bosons in the loop, with values of the order of $a=g^2/(96{\pi }^2)$ reached when there is a large splitting between the masses of these scalar bosons. As for $\Delta Q_V$, it reaches values as large as $10^{-2}a$ for the lightest allowed scalar bosons, but it decreases rapidly as one of the masses of the scalar bosons becomes large. Among the new contributions of the GMM to the $\Delta {\kappa }_V^{\prime }$ and $\Delta Q_V$ form factors are those induced by the $H_5^{\pm }{W}^{\mp }Z$ vertex, which arises at the tree-level and is a unique prediction of this model.

    hep-phPRD(2016)·10 citations
12. 12*

    Large-p_T production of D mesons at the LHCb in the parton Reggeization approach

    Anton Karpishkov🇷🇺 · Vladimir Saleev🇷🇺 · Alexandera Shipilova🇷🇺

    The production of D mesons in proton-proton collisions at the LHCb detector is studied. We consider the single production of D^0, D^+, D^star, and D_s^+ mesons and correlation spectra in the production of DbarD and DD pairs at the sqrt{S}=7 TeV and sqrt{S}=13 TeV. In case of the single D-meson production we calculate differential cross sections over transverse momentum p_T while in the pair DbarD,DD-meson production the cross sections are calculated over the azimuthal angle difference, rapidity difference, invariant mass of the pair M and over the p_T of the one meson from a pair. The cross sections are obtained at the leading order of the parton Reggeization approach using Kimber-Martin-Ryskin unintegrated parton distribution functions in a proton. To describe the D-meson production we use universal scale-dependent c-quark and gluon fragmentation functions fitted to e^+e^- annihilation data from CERN LEP1. Our predictions find a good agreement with the LHCb Collaboration data within uncertainties and without free parameters.

    hep-phPhys. Rev. D 94, 114012 (2016)·23 citations
13. 13*

    A Three-loop Neutrino Mass Model with a Colored Triplet Scalar

    Kingman Cheung🇹🇼 · Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

    We study a variation of the Krauss-Nasri-Trodden (KNT) model with a colored triplet scalar field and a colored singlet scalar field, in which we discuss the anomaly coming from $b\to s\mu \bar{\mu }$, fitting to the muon anomalous magnetic moment and the relic density of the Majorana-type dark matter candidate, as well as satisfying various constraints such as lepton-flavor violations and flavor-changing neutral currents. Also, we discuss the direct constraints from the collider searches and the possibilities of detecting the new fields at the LHC.

    hep-phPRD(2017)·25 citations
14. 14*

    Strong decays of $D_3^{\ast }(2760)$, $D_{s3}^{\ast }(2860)$, $B_3^{\ast }$, and $B_{s3}^{\ast }$

    Tianhong Wang🇨🇳 · Zhi-Hui Wang🇨🇳 · Yue Jiang🇨🇳 · Libo Jiang🇺🇸 · Guo-Li Wang🇨🇳

    In this paper, we study the OZI-allowed two-body strong decays of $3^{-}$ heavy-light mesons. Experimentally the charmed $D_3^{\ast }(2760)$ and the charm-strange $D_{s3}^{\ast }(2860)$ states with these quantum numbers have been discovered. For the bottomed $B(5970)$ state, which was found by the CDF Collaboration recently, its quantum number has not been decided yet and we assume its a $3^{-}$ meson in this paper. The theoretical prediction for the strong decays of bottom-strange state $B_{s3}^{\ast }$ is also given. The relativistic wave functions of $3^{-}$ heavy mesons are constructed and their numerical values are obtained by solving the corresponding Bethe-Salpeter equation with instantaneous approximation. The transition matrix is calculated by using the PCAC and low energy theorem, following which, the decay widths are obtained. For $D_3^{\ast }(2760)$ and $D_{s3}^{\ast }(2860)$, the total strong decay widths are 72.6 MeV and 47.6 MeV, respectively. For $B_3^{\ast }$ with $M=5978$ MeV and $B_{s3}^{\ast }$ with $M=6178$ MeV, their strong decay widths are 22.9 MeV and 40.8 MeV, respectively.

    hep-phEPJC(2017)·15 citations
15. 15*

    Two-loop corrections to the triple Higgs boson production cross section

    Daniel de Florian🇦🇷 · Javier Mazzitelli🇦🇷

    In this paper we compute the QCD corrections for the triple Higgs boson production cross section via gluon fusion, within the heavy-top approximation. We present, for the first time, analytical results for the next-to-leading order corrections, and also compute the soft and virtual contributions of the next-to-next-to-leading order cross section. We provide predictions for the total cross section and the triple Higgs invariant mass distribution. We find that the QCD corrections are large at both perturbative orders, and that the scale uncertainty is substantially reduced when the second order perturbative corrections are included.

    hep-phJHEP(2017)·17 citations
16. 16*

    Nonlocal quark model description of a composite Higgs particle

    Aliaksei Kachanovich🇵🇱 · David Blaschke🇷🇺

    We propose a description of the Higgs boson as top-antitop quark bound state within a nonlocal relativistic quark model of Nambu - Jona-Lasinio type. In contrast to model with local four-fermion interaction, the mass of the scalar bound state can be lighter than the sum of its constituents. This is achieved by adjusting the interaction range and the value of the coupling constant to experimental data, for both the top quark mass and the scalar Higgs boson mass, which can simultaneously be described.

    hep-phPhys.Part.Nucl.Lett.(2017)·2 citations
17. 17*

    SM*A*S*H

    Andreas Ringwald🇩🇪

    We present a minimal model for particle physics and cosmology. The Standard Model (SM) particle content is extended by three right-handed SM-singlet neutrinos N_i and a vector-like quark Q, all of them being charged under a global lepton number and Peccei-Quinn (PQ) U(1) symmetry which is spontaneously broken by the vacuum expectation value v_sigma around 10^{11} GeV of a SM-singlet complex scalar field sigma. Five fundamental problems -- neutrino oscillations, baryogenesis, dark matter, inflation, strong CP problem -- are solved at one stroke in this model, dubbed "SM*A*S*H" (Standard Model*Axion*Seesaw*Higgs portal inflation). It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.

    hep-phastro-ph.COhep-th1 citation
18. 18*

    Double-parton scattering effects in double charm production within gluon fragmentation scenario

    Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

    We discuss charm $D^0{D}^0$ meson-meson pair production in the forward rapidity region related to the LHCb experimental studies at $\sqrt{s}$ = 7 TeV. We consider double-parton scattering mechanisms of double $c\bar{c}$ production and subsequent standard $cc\to D^0{D}^0$ scale-independent hadronization as well as new double $g$ and mixed $gc\bar{c}$ production mechanisms with $gg\to D^0{D}^0$ and $gc\to D^0{D}^0$ scale-dependent hadronization. The new scenario with gluon fragmentation components results also in a new single-parton scattering mechanism of $gg$ production which is also taken here into account. Results of the numerical calculations are compared with the LHCb data for several correlation observables. The new mechanisms lead to a larger cross sections and to slightly different shapes of the calculated correlation observables.

    hep-ph0 citations
19. 19*

    Four-jet production in the $k_t$-factorisation

    Antoni Szczurek🇵🇱 · Rafal Maciula🇵🇱

    We discuss the single-parton and double-parton scattering (SPS or DPS) effects in four-jet production at the LHC. The calculations of both single-parton and double-parton scattering components are done in the high-energy (or $k_T$)-factorization approach. Here we follow our recent developments of relevant methods and tools. The calculations are performed for kinematical situations relevant for two experimental measurements (ATLAS and CMS) at the LHC. We compare our results to those reported by the ATLAS and CMS collaborations for different sets of kinematical cuts. A special attention is given to the optimization of kinematical conditions in order to enhance the relative contribution of DPS in four-jet sample. Several differential distributions are calculated and carefully discussed in the context of recent and future searches for DPS effects at the LHC. The dependences of the relative DPS amount is studied as a function of rapidity of jets, rapidity distance, and various azimuthal correlations between jets. The regions with an enhanced DPS contribution are identified.

    hep-ph0 citations
20. 20*

    Drell-Yan production at forward rapidities: a hybrid factorization approach

    Wolfgang Schäfer🇵🇱 · Antoni Szczurek🇵🇱

    We discuss the Drell-Yan production of dileptons at high energies in the forward rapidity region of proton-proton collisions in a hybrid high-energy approach. This approach uses unintegrated gluon distributions in one proton and collinear quark/antiquark distributions in the second proton. We compute various distributions for the case of low-mass dilepton production and compare to the LHCb and ATLAS experimental data on dilepton mass distributions. In distinction to dipole approaches, we include four Drell-Yan structure functions as well as cuts at the level of lepton kinematics. The impact of the interference structure functions is rather small for typical experimental cuts. We find that both side contributions ($gq/\bar{q}$ and $q/\bar{q}g$) have to be included even for the LHCb rapidity coverage which is in contradiction with what is usually done in the dipole approach. We present results for different unintegrated gluon distributions from the literature. Some of them include saturation effects, but we see no clear hints of saturation even at small $M_{ll}$.

    hep-ph0 citations
21. 21*

    CP violation during the electroweak sphaleron transitions

    Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸

    We suggest a specific semiclassical background field, the so called pure gauge sphaleron explosion, to evaluate the magnitude of the CP violation stemming from the standard phase of the CKM matrix. We use it to evaluate the matrix elements of some next-to-leading order effective CP-violating operators suggested in the literature. We also derive the scale dependence of the corresponding coefficients. Finally, we discuss the expected magnitude of the CP violation in the cold electroweak scenario.

    hep-ph0 citations
22. 22*

    Comparison between the continuum threshold and the Polyakov loop as deconfinement order parameters

    J.P. Carlomagno🇦🇷 · M. Loewe🇿🇦

    We study the relation between the continuum threshold as function of the temperature $s_0(T)$ within finite energy sum rules and the trace of the Polyakov loop $\Phi$ in the framework of a nonlocal SU(2) chiral quark model, establishing a contact between both deconfinement order parameters at finite temperature $T$ and chemical potential $\mu$. In our analysis, we also include the order parameter for the chiral symmetry restoration, the chiral quark condensate. We found that $s_0$ and $\Phi$ providing us the same information for the deconfinement transition, both for the zero and finite chemical potential cases. At zero density, the critical temperatures for both quantities coincide exactly and, at finite $\mu$ both order parameters provide evidence for the appearance of a quarkyonic phase.

    hep-phPRD(2017)·11 citations
23. 23*

    New Searches for CPT Violation in Neutral-Meson Oscillations

    Ágnes Roberts🇺🇸

    Classic tests of CPT symmetry have been done in the neutral-meson system. These have been continued with new results in the framework of the Standard-Model Extension, where the coefficient for CPT violation is both boost and direction dependent. Recent contributions and new phenomenological improvements are discussed with possible new contributions for $b$ and $d$ specific correlated decays at the Belle II asymmetric energy collider.

    hep-ph0 citations
24. 24*

    Calculation of the Nucleon Axial Form Factor Using Staggered Lattice QCD

    Aaron S. Meyer🇺🇸 · Richard J. Hill🇺🇸 · Andreas S. Kronfeld🇺🇸 · Ruizi Li🇺🇸 · James N. Simone🇺🇸

    The nucleon axial form factor is a dominant contribution to errors in neutrino oscillation studies. Lattice QCD calculations can help control theory errors by providing first-principles information on nucleon form factors. In these proceedings, we present preliminary results on a blinded calculation of $g_A$ and the axial form factor using HISQ staggered baryons with 2+1+1 flavors of sea quarks. Calculations are done using physical light quark masses and are absolutely normalized. We discuss fitting form factor data with the model-independent $z$ expansion parametrization.

    ↳ hep-lathep-phPoS(2016)·15 citations
25. 25*

    Connected and leading disconnected hadronic light-by-light contribution to the muon anomalous magnetic moment with physical pion mass

    Thomas Blum🇺🇸 · Norman Christ🇺🇸 · Masashi Hayakawa🇯🇵 · Taku Izubuchi🇺🇸 · Luchang Jin🇺🇸 · Chulwoo Jung🇺🇸 · Christoph Lehner🇺🇸

    We report a lattice QCD calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment at physical pion mass. The calculation includes the connected diagrams and the leading, quark-line-disconnected diagrams. We incorporate algorithmic improvements developed in our previous work. The calculation was performed on the $48^3\times 96$ ensemble generated with a physical-pion-mass and a 5.5 fm spatial extent by the RBC and UKQCD collaborations using the chiral, domain wall fermion (DWF) formulation. We find $a_{\mu }^{\text{HLbL}}=5.35(1.35)\times 10^{-10}$, where the error is statistical only. The finite-volume and finite lattice-spacing errors could be quite large and are the subject of on-going research. The omitted disconnected graphs, while expected to give a correction of order 10\%, also need to be computed.

    ↳ hep-lathep-phPRL(2017)·128 citations
26. 26*

    Tests of Lorentz symmetry in the gravitational sector

    Aurélien Hees🇺🇸 · Quentin G. Bailey🇺🇸 · Adrien Bourgoin🇫🇷 · Hélène Pihan-Le Bars🇫🇷 · Christine Guerlin🇫🇷 · Christophe Le Poncin-Lafitte🇫🇷

    Lorentz symmetry is one of the pillars of both General Relativity and the Standard Model of particle physics. Motivated by ideas about quantum gravity, unification theories and violations of CPT symmetry, a significant effort has been put the last decades into testing Lorentz symmetry. This review focuses on Lorentz symmetry tests performed in the gravitational sector. We briefly review the basics of the pure gravitational sector of the Standard-Model Extension (SME) framework, a formalism developed in order to systematically parametrize hypothetical violations of the Lorentz invariance. Furthermore, we discuss the latest constraints obtained within this formalism including analyses of the following measurements: atomic gravimetry, Lunar Laser Ranging, Very Long Baseline Interferometry, planetary ephemerides, Gravity Probe B, binary pulsars, high energy cosmic rays,... In addition, we propose a combined analysis of all these results. We also discuss possible improvements on current analyses and present some sensitivity analyses for future observations.

    ↳ gr-qchep-phUniverse(2016)·92 citations
27. 27*

    Study of Lambda polarization in relativistic nuclear collisions at sqrt{s}_NN = 7.7-200 GeV

    Iu. Karpenko (INFN Florence)🇺🇦 · F. Becattini (U. Florence)🇮🇹

    We present a calculation of the global polarization of Lambda hyperons in relativistic Au-Au collisions at RHIC Beam Energy Scan range sqrt{s}_NN = 7.7 - 200 GeV with a 3+1 dimensional cascade + viscous hydro + cascade model, UrQMD+vHLLE. Within this model, the mean polarization of Lambda in the out-of-plane direction is predicted to decrease rapidly with collision energy from a top value of about 2% at the lowest energy examined. We explore the connection between the polarization signal and thermal vorticity and estimate the feed-down contribution to Lambda polarization due to the decay of higher mass hyperons.

    ↳ nucl-thhep-phEPJC(2017)·310 citations
28. 28*

    Niemeier Lattices in the Free Fermionic Heterotic-String Formulation

    Panos Athanasopoulos🇬🇧 · Alon E. Faraggi🇬🇧

    The spinor-vector duality was discovered in free fermionic constructions of the heterotic-string in four dimensions. It played a key role in the construction of heterotic-string models with an anomaly free extra $Z^{\prime }$ symmetry that may remain unbroken down to low energy scales. A generic signature of the low scale string derived $Z^{\prime }$ model is via di-photon excess that may be within reach of the LHC. A fascinating possibility is that the spinor-vector duality symmetry is rooted in the structure of the heterotic-string compactifications to two dimensions. The two dimensional heterotic-string theories are in turn related to the so-called moonshine symmetries that underlie the two dimensional compactifications. In this paper we embark on exploration of this connection by the free fermionic formulation to classify the symmetries of the two dimensional heterotic-string theories. We use two complementary approaches in our classification. The first utilises a construction which is akin to the one used in the spinor-vector duality. Underlying this method is the triality property of $SO(8)$ representations. In the second approach we use the free fermionic tools to classify the twenty four dimensional Niemeier lattices.

    ↳ hep-thhep-phAdv.Math.Phys.(2017)·11 citations
29. 29*

    Diffractive charmonium spectrum in high energy collisions in the basis light-front quantization approach

    Guangyao Chen🇺🇸 · Yang Li🇺🇸 · Pieter Maris🇺🇸 · Kirill Tuchin🇺🇸 · James P. Vary🇺🇸

    Using the charmonium light-front wavefunctions obtained by diagonalizing an effective Hamiltonian with the one-gluon exchange interaction and a confining potential inspired by light-front holography in the basis light-front quantization formalism, we compute production of charmonium states in diffractive deep inelastic scattering and ultra-peripheral heavy ion collisions within the dipole picture. Our method allows us to predict yields of all vector charmonium states below the open flavor thresholds in high-energy deep inelastic scattering, proton-nucleus and ultra-peripheral heavy ion collisions, without introducing any new parameters in the light-front wavefunctions. The obtained charmonium cross section is in reasonable agreement with experimental data at HERA, RHIC and LHC. We observe that the cross-section ratio ${\sigma }_{\Psi (2s)}/{\sigma }_{J/\Psi }$ reveals significant independence of model parameters.

    ↳ nucl-thhep-phPLB(2017)·34 citations
30. 30*

    Radiative corrections to the magnetic moments of the proton and the neutron

    N. Kaiser🇩🇪

    We estimate the radiative corrections of order $\alpha /\pi$ to the magnetic moments of the proton and the neutron. The photon-loop diagram of the vertex-correction type is evaluated with phenomenological nucleon vector form factors. Infrared-finiteness and gauge-invariance require the inclusion of the wave-function renormalization factor from the self-energy diagram. Using recent empirical form factor parametrizations the corrections amount to $\delta {\kappa }_p=-3.42\cdot 10^{-3}$ and $\delta {\kappa }_n=1.34\cdot 10^{-3}$. We study also the effects from photon-loops with internal $\Delta (1232)$-isobars. For two customary versions of the $\Delta N\gamma$-vertex and spin-3/2 propagator, these radiative corrections have values of $\delta {\kappa }_p^{(\Delta )}=(-0.9,0.0)\cdot 10^{-3}$ and $\delta {\kappa }_n^{(\Delta )}=(1.2,-0.8)\cdot 10^{-3}$, respectively.

    ↳ nucl-thhep-phJ.Phys.G(2017)·2 citations
31. 31*

    Metastable Dark Energy with Radioactive-like Decay

    Arman Shafieloo🇰🇷 · Dhiraj Kumar Hazra🇫🇷 · Varun Sahni🇮🇳 · Alexei A. Starobinsky🇷🇺

    We propose a new class of metastable dark energy (DE) phenomenological models in which the DE decay rate does not depend on external parameters such as the scale factor or the curvature of the Universe. Instead, the DE decay rate is assumed to be a constant depending only on intrinsic properties of DE and the type of a decay channel, similar to case of the radioactive decay of unstable particles and nuclei. As a consequence, the DE energy density becomes a function of the proper time elapsed since its formation, presumably in the very early Universe. Such a natural type of DE decay can profoundly affect the expansion history of the Universe and its age. Metastable DE can decay in three distinct ways: (i) exponentially, (ii) into dark matter, (iii) into dark radiation. Testing metastable DE models with observational data we find that the decay half-life must be many times larger than the age of the Universe. Models in which dark energy decays into dark matter lead to lower values of the Hubble parameter at large redshifts relative to $\Lambda$CDM. Consequently these models provide a better fit to cosmological BAO data (especially data from from high redshift quasars) than concordance ($\Lambda$CDM) cosmology.

    ↳ astro-ph.COgr-qchep-phMNRAS(2018)·57 citations
32. 32*

    Single-Transverse-Spin-Asymmetry studies with a fixed-target experiment using the LHC beams (AFTER@LHC)

    J.P. Lansberg🇫🇷 · M. Anselmino🇮🇹 · R. Arnaldi🇮🇹 · S.J. Brodsky🇺🇸 · V. Chambert🇫🇷 · C. Da Silva🇺🇸 · J.P. Didelez🇫🇷 · M.G Echevarria🇪🇸 · E.G. Ferreiro🇪🇸 · F. Fleuret🇫🇷 · Y. Gao🇨🇳 · B. Genolini🇫🇷 and 25 other authors

    We discuss the potential of AFTER@LHC to measure single-transverse-spin asymmetries in open-charm and bottomonium production. With a HERMES-like hydrogen polarised target, such measurements over a year can reach precisions close to the per cent level. This is particularly remarkable since these analyses can probably not be carried out anywhere else

    ↳ hep-exhep-phnucl-exnucl-thPoS(2016)·6 citations
33. 33*

    Production and Distribution of ${}^{44}$Ti and ${}^{56}$Ni in a Three-dimensional Supernova Model Resembling Cassiopeia A

    A. Wongwathanarat (1,2)🇯🇵 · H.-Th. Janka (2)🇩🇪 · E. Mueller (2)🇩🇪 · E. Pllumbi (2,3)🇩🇪 · S. Wanajo (4,5) ((1) RIKEN, ABB Lab, (2) MPI Astrophysics, (3) Physik Dept., TUM, (4) RIKEN, iTHES Research Group)🇯🇵

    The spatial and velocity distributions of nuclear species synthesized in the innermost regions of core-collapse supernovae can yield important clues about explosion asymmetries and the operation of the still disputed explosion mechanism. Recent observations of radioactive ${}^{44}$Ti with high-energy satellite telescopes (Nuclear Spectroscopic Telescope Array [NuSTAR], INTEGRAL) have measured gamma-ray line details, which provide direct evidence of large-scale explosion asymmetries in SN 1987A and in Cassiopeia A (Cas A) even by mapping of the spatial brightness distribution (NuSTAR). Here we discuss a 3D simulation of a neutrino-driven explosion, using a parameterized neutrino engine, whose ${}^{44}$Ti distribution is mostly concentrated in one hemisphere pointing opposite to the neutron star (NS) kick velocity. Both exhibit intriguing resemblance to the observed morphology of the Cas A remnant, although neither the progenitor nor the explosion was fine-tuned for a perfect match. Our results demonstrate that the asymmetries observed in this remnant can, in principle, be accounted for by a neutrino-driven explosion, and that the high ${}^{44}$Ti abundance in Cas A may be explained without invoking rapid rotation or a jet-driven explosion, because neutrino-driven explosions generically eject large amounts of high-entropy matter. The recoil acceleration of the NS is connected to mass ejection asymmetries and is opposite to the direction of the stronger explosion, fully compatible with the gravitational tugboat mechanism. Our results also imply that Cas A and SN 1987A could possess similarly "one-sided" Ti and Fe asymmetries, with the difference that Cas A is viewed from a direction with large inclination angle to the NS motion, whereas the NS in SN 1987A should have a dominant velocity component pointing toward us.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thApJ(2017)·169 citations
34. 34*

    Production of phi-mesons on nuclear targets in the Quark-Gluon String model

    G.H. Arakelyan🇦🇲 · C. Merino🇪🇸 · Yu.M. Shabelski🇷🇺

    We consider the experimental data on phi-meson production on nuclear targets, and we find that they present unusually small shadow corrections for the inclusive density in the midrapidity region. We also give a quantitatively consistent description of both the initial energy dependence and the A-dependence of the produced phi-mesons, obtained in the frame of the Quark-Gluon String Model.

    ↳ nucl-thhep-exhep-phPhys.Atom.Nucl.(2017)·2 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.