Wed·Nov 8, 2017Wednesday·November 8, 2017

1. 01*

   Searching for Weak Singlet Charged Scalar at the Large Hadron Collider

   Qing-Hong Cao🇨🇳 · Gang Li🇹🇼 · Ke-Pan Xie🇨🇳 · Jue Zhang🇨🇳

   Weak singlet charged scalar exists in many new physics models beyond the Standard Model. In this work we show that a light singlet charged scalar with mass above 65~GeV is still allowed by the LEP and LHC data. The interactions of the singlet charged scalar with the Standard Model particles are described by operators up to dimension-5. Dominant decay modes of the singlet charged scalar are obtained, and a subtlety involving field redefinition and gauge fixing due to a dimension-5 operator is also clarified. We demonstrate that it is promising to observe the singlet charged scalar at the LHC.

   hep-phPRD(2018)·34 citations
2. 02*

   Large NLO corrections in $t\bar{t}{W}^{\pm }$ and $t\bar{t}t\bar{t}$ hadroproduction from supposedly subleading EW contributions

   Rikkert Frederix🇩🇪 · Davide Pagani🇩🇪 · Marco Zaro🇳🇱

   We calculate the complete-NLO predictions for $t\bar{t}{W}^{\pm }$ and $t\bar{t}t\bar{t}$ production in proton--proton collisions at 13 and 100 TeV. All the non-vanishing contributions of $\mathcal{O}({\alpha }_s^i{\alpha }^j)$ with $i+j=3,4$ for $t\bar{t}{W}^{\pm }$ and $i+j=4,5$ for $t\bar{t}t\bar{t}$ are evaluated without any approximation. For $t\bar{t}{W}^{\pm }$ we find that, due to the presence of $tW\to tW$ scattering, at 13(100) TeV the $\mathcal{O}({\alpha }_s{\alpha }^3)$ contribution is about 12(70)\% of the LO, i.e., it is larger than the so-called NLO EW corrections (the $\mathcal{O}({\alpha }_s^2{\alpha }^2)$ terms) and has opposite sign. In the case of $t\bar{t}t\bar{t}$ production, large contributions from electroweak $tt\to tt$ scattering are already present at LO in the $\mathcal{O}({\alpha }_s^3\alpha )$ and $\mathcal{O}({\alpha }_s^2{\alpha }^2)$ terms. For the same reason we find that both NLO terms of $\mathcal{O}({\alpha }_s^4\alpha )$, i.e., the NLO EW corrections, and $\mathcal{O}({\alpha }_s^3{\alpha }^2)$ are large ($\pm 15\%$ of the LO) and their relative contributions strongly depend on the values of the renormalisation and factorisation scales. However, large accidental cancellations are present (away from the threshold region) between these two contributions. Moreover, the NLO corrections strongly depend on the kinematics and are particularly large at the threshold, where even the relative contribution from $\mathcal{O}({\alpha }_s^2{\alpha }^3)$ terms amounts to tens of percents.

   hep-phJHEP(2018)·304 citations
3. 03*

   Re-running the QCD shear viscosity

   Greg Jackson🇿🇦 · Andre Peshier🇿🇦

   The remarkably small shear viscosity to entropy density ratio $\eta /s<0.5$ of the quark-gluon plasma (QGP) is a key insight from heavy ion experiments. Nonetheless, the basic understanding of this `observable' still seems to be rudimentary, with existing perturbative QCD estimates suggesting $\eta /s>1$, a view that we scrutinize here. In order to extrapolate the available perturbative approach to phenomenologically relevant temperatures, we consider carefully controllable higher-order corrections: We adapt the leading-order effective kinetic scheme (instead of the catchy next-to-leading log formula ${\eta }_{{}_{\mathrm{NLL}}}\propto [{\alpha }^2\log (c/\alpha ){]}^{-1}$), by using cross sections with a running coupling. This effect should be pertinent (for a QGP) and we argue for a choice of scale-dependence that makes it consistent with thermal screening. We conclude that $\eta /s\approx 0.2$ does not indicate genuine non-perturbative effects, it may rather be understood within resummation-improved perturbative QCD, with some uncertainties from deploying kinetic theory near to its limit.

   hep-phJ.Phys.G(2018)·8 citations
4. 04*

   Charm, Bottom, Strange Baryon Masses Using QCD Sum Rules

   Leonard S. Kisslinger🇺🇸 · Bijit Singha🇺🇸

   We use the method of QCD Sum Rules to estimate the masses of the charm baryon, ${\Lambda }_c^{+}$, bottom baryon ${\Lambda }_b^0$, strange baryon ${\Lambda }_s^0$ and compare them to their experimental values.

   hep-phInt.J.Mod.Phys.A(2018)·3 citations
5. 05*

   Lepton Number Violation: Seesaw Models and Their Collider Tests

   Yi Cai🇨🇳 · Tao Han🇺🇸 · Tong Li🇦🇺 · Richard Ruiz🇬🇧

   The Majorana nature of neutrinos is strongly motivated from the theoretical and phenomenological point of view. A plethora of neutrino mass models, known collectively as Seesaw models, exist that could generate both a viable neutrino mass spectrum and mixing pattern. They can also lead to rich, new phenomenology, including lepton number non-conservation as well as new particles, that may be observable at collider experiments. It is therefore vital to search for such new phenomena and the mass scale associated with neutrino mass generation at high energy colliders. In this review, we consider a number of representative Seesaw scenarios as phenomenological benchmarks, including the characteristic Type I, II, and III Seesaw mechanisms, their extensions and hybridizations, as well as radiative constructions. We present new and updated predictions for analyses featuring lepton number violation and expected coverage in the theory parameter space at current and future colliders. We emphasize new production and decay channels, their phenomenological relevance and treatment across different facilities in $e^{+}{e}^{-}$, $e^{-}p$ and $pp$ collisions, as well as the available Monte Carlo tools available for studying Seesaw partners in collider environments.

   hep-phhep-exFront.in Phys.(2018)·378 citations
6. 06*

   Anomalous effects of dense matter under rotation

   Xu-Guang Huang🇨🇳 · Kentaro Nishimura🇯🇵 · Naoki Yamamoto🇯🇵

   We study the anomaly induced effects of dense baryonic matter under rotation. We derive the anomalous terms that account for the chiral vortical effect in the low-energy effective theory for light Nambu-Goldstone modes. The anomalous terms lead to new physical consequences, such as the anomalous Hall energy current and spontaneous generation of angular momentum in a magnetic field (or spontaneous magnetization by rotation). In particular, we show that, due to the presence of such anomalous terms, the ground state of the quantum chromodynamics (QCD) under sufficiently fast rotation becomes the "chiral soliton lattice" of neutral pions that has lower energy than the QCD vacuum and nuclear matter. We briefly discuss the possible realization of the chiral soliton lattice induced by a fast rotation in noncentral heavy ion collisions.

   hep-phcond-mat.mes-hallhep-thnucl-thJHEP(2018)·93 citations
7. 07*

   Clebsch-Gordan coefficients of discrete groups in subgroup bases

   Gaoli Chen🇺🇸

   We express each Clebsch-Gordan (CG) coefficient of a discrete group as a product of a CG coefficient of its subgroup and a factor, which we call an embedding factor. With an appropriate definition, such factors are fixed up to phase ambiguities. Particularly, they are invariant under basis transformations of irreducible representations of both the group and its subgroup. We then impose on the embedding factors constraints, which relate them to their counterparts under complex conjugate and therefore restrict the phases of embedding factors. In some cases, the phase ambiguities are reduced to sign ambiguities. We describe the procedure of obtaining embedding factors and then calculate CG coefficients of the group \mathcal{PSL}_{2}\left(7\right) in terms of embedding factors of its subgroups S_{4} and \mathcal{T}_{7}.

   hep-phhep-thmath-phmath.MPInt.J.Mod.Phys.A(2018)·0 citations
8. 08*

   Tests of the Higgs and top quark properties through inclusive $t\bar{t}$ production

   Fernand Renard🇫🇷

   We show how the inclusive $t\bar{t}$ production in $e^{+}{e}^{-}$, gluon~gluon and photon~photon collisions could reveal the presence of new (visible or invisible) particles connected to the Higgs sector and/or to the top quark.

   hep-ph3 citations
9. 09*

   Jets and threshold summation in Deductor

   Zoltan Nagy🇩🇪 · Davison E. Soper🇺🇸

   We explore jet physics in hadron collisions using the parton shower event generator Deductor. Of particular interest is the one jet inclusive cross section dsigma/dpT for jets of very high pT. Compared to the Born level, the cross section decreases substantially because of pT loss from the jet during showering. We compare to the same effect in Pythia and Dire. The cross section then increases substantially because of the summation of threshold logarithms included in Deductor. We also study the cross section to have a gap with no jets between two hard jets that are widely separated in rapidity. Here we compare Deductor with virtuality based ordering with Deductor with kT ordering and we check whether adding an underlying event and hadronization has a significant effect beyond that found with just a parton shower.

   hep-phPRD(2018)·22 citations
10. 10*

    Unitary symmetry of DDK sum rules for hadron photoproduction on octet baryons

    V.S.Zamiralov🇷🇺

    Dubnicka-Dubnickova-Kuraev (DDK) sum rules are considered. It is shown that integrals over differences of the total photoproduction cross-sections on octet baryons could be understood in terms of unitary symmetry approach. All the DDK sum rules for these quantities are expressed in terms of only three parameters.

    hep-ph0 citations
11. 11*

    Single pion production in neutrino-nucleon Interactions

    M. Kabirnezhad🇵🇱

    This work represents an extension of the single pion production model proposed by D. Rein. The model consists of resonant pion production and nonresonant background contributions coming from three Born diagrams in the helicity basis. The new work includes lepton mass effects, and nonresonant interaction is described by five diagrams based on a nonlinear {\sigma} model. This work provides a full kinematic description of single pion production in the neutrino-nucleon interactions, including resonant and nonresonant interactions in the helicity basis, in order to study the interference effect.

    hep-phPRD(2018)·78 citations
12. 12*

    Analysis of the anomalous electromagnetic moments of the tau lepton in $\gamma p$ collisions at the LHC

    M. Köksal🇹🇷 · S. C. İnan🇹🇷 · A. A. Billur🇹🇷 · M. K. Bahar🇹🇷 · Y. Özgüven🇹🇷

    In this study, we investigate the potential of the process $pp\to p{\gamma }^{\ast }p\to p\tau {\bar{\nu }}_{\tau }{q}^{\prime }X$ at the LHC to examine the anomalous electromagnetic moments of the tau lepton. We obtain $95\%$ confidence level bounds on the anomalous coupling parameters with various values of the integrated luminosity and center-of-mass energy. The improved bounds have been obtained on the anomalous coupling parameters of electric and magnetic moments of the tau lepton $a_{\tau }$ and $|$$d_{\tau }$$|$ compared to the current experimental sensitivity bounds. The $\gamma p$ mode of photon reactions at the LHC have shown that it has great potential for the electromagnetic dipole moments studies of the tau lepton.

    hep-phPLB(2018)·24 citations
13. 13*

    Common Origin of Non-zero ${\theta }_{13}$ and Baryon Asymmetry of the Universe in a TeV scale Seesaw Model with $A_4$ Flavour Symmetry

    Debasish Borah🇮🇳 · Mrinal Kumar Das🇮🇳 · Ananya Mukherjee🇮🇳

    We study the possibility of generating non-zero reactor mixing angle ${\theta }_{13}$ and baryon asymmetry of the Universe within the framework of an $A_4$ flavour symmetric model. Using the conventional type I seesaw mechanism we construct the Dirac and Majorana mass matrices which give rise to the correct light neutrino mass matrix. Keeping the right handed neutrino mass matrix structure trivial so that it gives rise to a (quasi) degenerate spectrum of heavy neutrinos suitable for resonant leptogenesis at TeV scale, we generate the non-trivial structure of Dirac neutrino mass matrix that can lead to the light neutrino mixing through type I seesaw formula. Interestingly, such a setup naturally leads to non-zero ${\theta }_{13}$ due to the existence of anti-symmetric contraction of the product of two triplet representations of $A_4$. Such antisymmetric part of triplet products usually vanish for right handed neutrino Majorana mass terms, leading to $\mu -\tau$ symmetric scenarios in the most economical setups. We constrain the model parameters from the requirement of producing the correct neutrino data as well as baryon asymmetry of the Universe for right handed neutrino mass scale around TeV. The $A_4$ symmetry is augmented by additional $Z_3\times Z_2$ symmetry to make sure that the splitting between right handed neutrinos required for resonant leptogenesis is generated only by next to leading order terms, making it naturally small. We find that the inverted hierarchical light neutrino masses give more allowed parameter space consistent with neutrino and baryon asymmetry data.

    hep-phPRD(2018)·24 citations
14. 14*

    WIMP Theory Review

    Farinaldo S. Queiroz🇧🇷

    The complementarity of direct, indirect and collider searches for dark matter has improved our understanding concerning the properties of the dark matter particle. In this short review, we present a step toward the fundamental nature of dark matter with direct detection experiments only, go through some of the potential dark matter signals in gamma-rays, x-rays, and anti-matter, and lastly discuss the prospects of WIMPs in the next decade.

    hep-phastro-ph.COastro-ph.HEPoS(2017)·15 citations
15. 15*

    On UltraViolet Freeze-in Dark Matter during Reheating

    Shao-Long Chen🇨🇳 · Zhaofeng Kang🇨🇳

    The absence of any confirmative signals from extensive DM searching motivates us to go beyond the conventional WIMPs scenario. The feebly interacting massive particles (FIMPs) paradigm provides a good alternative which, despite of its feebly interaction with the thermal particles, still could correctly produce relic abundance without conventional DM signals. The Infrared-FIMP based on the renormalizable operators is usually suffering the very tiny coupling drawback, which can be overcome in the UltraViolet-FIMP scenario based on high dimensional effective operators. However, it is sensitive to the history of the very early Universe. The previous works terminates this sensitivity at the reheating temperature $T_{RH}$. We, motivated by its UV-sensitivity, investigate the effects from the even earlier Universe, reheating era. We find that in the usual case with $T_{RH}\gg m_{\mathrm{DM}}$, the production rate during reheating is very small as long as the effective operators dimension $d\le 8$. Besides, we consider the contribution from the mediator, which may be produced during reheating. Moreover, we study the situation when $T_{RH}$ is even lower than $m_{\mathrm{DM}}$ and DM can be directly produced during reheating if its mass does not exceed $T_{MAX}$.

    hep-phastro-ph.COJCAP(2018)·63 citations
16. 16*

    Single top-quark production with SHERPA

    Enrico Bothmann🇬🇧 · Frank Krauss🇬🇧 · Marek Schönherr🇨🇭

    We present results at next-to-leading order accuracy in QCD for single top-quark production in the $t$, $s$ and $tW$ channels at the LHC at a centre-of-mass energy of 8 TeV, obtained with the SHERPA event generator. We find them in very good agreement with measured values and quantify their theory uncertainties. Uncertainties stemming from the choice between the four- and the five-flavour scheme are found to be typically of the order of 5-10 % over large ranges of phase space. We discuss the impact of parton distribution functions, and in particular of the bottom PDF. We also show how different cuts on QCD radiation patterns improve the signal-to-background ratio in realistic fiducial volumes.

    hep-phEPJC(2018)·25 citations
17. 17*

    Rescattering effects in jet-gap-jet processes

    Rafał Staszewski🇵🇱 · Izabela Babiarz🇵🇱 · Antoni Szczurek🇵🇱

    We discuss the process of colour-singlet parton-parton scattering, which in hadron-hadron collision can lead to production of jet events, where a rapidity gap between the jets is present. The dynamics of the process is calculated within LL BFKL approximation. Using Pythia MC generator, hadronic shapes of jet-gap-jet events are studied, in particular the distributions of the rapidity gap size resulting from the jet formation processes. Using Pythia's modelling of multiple parton interactions, the rescattering effects are simulated. It is shown how these effects influence the gap size distributions. The kinematic dependence of the gap survival probability is discussed.

    hep-ph0 citations
18. 18*

    Charged Higgs-boson pair production in association with the $Z^0$ boson at electron-positron colliders

    Nasuf Sonmez🇹🇷

    In this paper, the production of the charged Higgs pair associated with the $Z^0$ boson is analyzed in the minimal extension of the standard model the so-called two-Higgs-doublet model (2HDM). The process $e^{+}{e}^{-}\to H^{+}{H}^{-}{Z}^0$ is calculated at the tree level including all the possible diagrams in 2HDM. The numerical analysis is performed in consideration of the current experimental constraints and various scenarios for the free parameters of the model. The results are presented as a function of center-of-mass energy, the charged Higgs mass ($m_{H^{\pm }}$), and the ratio of the vacuum expectation values ($t_{\beta }$). The unpolarized cross section, taking into account the results in the flavor physics, gets up to $0.278\text{ fb}$ for $m_{H^{\pm }}=175\text{ GeV}$, and it declines with decreasing $m_{H^{\pm }}$ in Type-I. However, it gets down to $0.073\text{ fb}$ for $m_{H^{\pm }}=500\text{ GeV}$ in Type-II. Further, the calculation is also carried out in the non-alignment scenario and low-$m_{h^0}$ scenario. The effect of the polarized incoming $e^{+}$ and $e^{-}$ beams shows that the cross section is enhanced by a factor up to 2.5 at P(+0.60,-0.80) polarization configuration. Decay channels of the charged Higgs, possible final states of the process, and some differential distributions belong to the charged Higgs and $Z^0$ boson are examined for each scenario. The analysis shows that some channels have higher branching ratio such as $H^{+}\to t\bar{b}$, $H^{+}\to W^{+}{h}^0$, and $H^{+}\to W^{+}{H}^0$. These decay channels are essential for the charged Higgs searches in the lepton colliders regarding the scenarios interested. The detection of the charged Higgs is a powerful sign for the extended scalar sectors, and the results show the potential of a future lepton collider.

    hep-phPRD(2018)·0 citations
19. 19*

    Recursive Neural Networks in Quark/Gluon Tagging

    Taoli Cheng🇨🇳

    Since the machine learning techniques are improving rapidly, it has been shown that the image recognition techniques in deep neural networks can be used to detect jet substructure. And it turns out that deep neural networks can match or outperform traditional approach of expert features. However, there are disadvantages such as sparseness of jet images. Based on the natural tree-like structure of jet sequential clustering, the recursive neural networks (RecNNs), which embed jet clustering history recursively as in natural language processing, have a better behavior when confronted with these problems. We thus try to explore the performance of RecNNs in quark/gluon discrimination. The results show that RecNNs work better than the baseline boosted decision tree (BDT) by a few percent in gluon rejection rate. However, extra implementation of particle flow identification only increases the performance slightly. We also experimented on some relevant aspects which might influence the performance of the networks. It shows that even taking only particle flow identification as input feature without any extra information on momentum or angular position is already giving a fairly good result, which indicates that the most of the information for quark/gluon discrimination is already included in the tree-structure itself. As a bonus, a rough up/down quark jets discrimination is also explored.

    hep-phhep-exstat.MLComput.Softw.Big Sci.(2018)·113 citations
20. 20*

    Bose-Einstein enhancement in the evolution of the double parton densities at high energy

    E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U./UTFSM)🇮🇱

    In the paper we include Bose-Einsten correlations for identical gluons, in the evolution of the double parton densities at low $x$ (high energies). We show that these correlations result in a faster increase of the double densities, in comparison with the product of two single parton densities. In addition, we find that the typical momentum in the double parton cross section, is of the order of the hard scales in the process, including the saturation momentum. This result is in agreement with recently published experimental data.

    hep-ph0 citations
21. 21*

    Duality relations in proton diffraction dissociation and in DIS

    László Jenkovszky🇺🇦 · István Szanyi🇺🇦

    We use duality to relate resonances in missing mass $M$ to the large-mass diffraction dissociation of protons. In deep inelastic lepton-hadron scattering (DIS), hadronic resonances are related by duality in $Q^2$ to the low-$x$, smooth behaviour of the DIS structure functions.

    hep-ph0 citations
22. 22*

    Remarks on the Z' Drell-Yan cross section

    Gil Paz🇺🇸 · Joydeep Roy🇺🇸

    Many extension of the standard model contain an extra U(1)' gauge group with a heavy Z' gauge boson. Perhaps the most clear signal for such a Z' would be a resonance in the invariant mass spectrum of the lepton pairs to which it decays. In the absence of such a signal, experiments can set limits on the couplings of such a Z', using a standard formula from theory. We repeat its derivation and find that, unfortunately, the standard formula in the literature is a factor of 8 too small. We briefly explore the implication for existing experimental searches and encourage the high energy physics community to re-examine analyses that have used this formula.

    hep-phPRD(2018)·8 citations
23. 23*

    Neutrino Pair Cerenkov Radiation for Tachyonic Neutrinos

    Ulrich D. Jentschura🇺🇸 · Istvan Nandori🇭🇺

    The emission of a charged light lepton pair by a superluminal neutrino has been identified as a major factor in the energy loss of highly energetic neutrinos. The observation of PeV neutrinos by IceCube implies their stability against lepton pair Cerenkov radiation. Under the assumption of a Lorentz-violating dispersion relation for highly energetic superluminal neutrinos, one may thus constrain the Lorentz-violating parameters. A kinematically different situation arises when one assumes a Lorentz-covariant, space-like dispersion relation for hypothetical tachyonic neutrinos, as an alternative to Lorentz-violating theories. We here discuss a hitherto neglected decay process, where a highly energetic tachyonic neutrinos may emit other (space-like, tachyonic) neutrino pairs. We find that the space-like dispersion relation implies the absence of a q^2 threshold for the production of a tachyonic neutrino-antineutrino pair, thus leading to the dominant additional energy loss mechanism for an oncoming tachyonic neutrino in the medium-energy domain. Surprisingly, the small absolute value of the decay rate and energy loss rate in the tachyonic model imply that these models, in contrast to the Lorentz-violating theories, are not pressured by the cosmic PeV neutrinos registered by the IceCube collaboration.

    hep-phAdv.High Energy Phys.(2017)·0 citations
24. 24*

    Non-Gaussian Enhancements of Galactic Halo Correlations in Quasi-Single Field Inflation

    Haipeng An🇨🇳 · Michael McAneny🇺🇸 · Alexander K. Ridgway🇺🇸 · Mark B. Wise🇺🇸

    We consider a quasi-single field inflation model in which the inflaton interacts with a massive scalar field called the isocurvaton. Due to the breaking of time translational invariance by the inflaton background, these interactions induce kinetic mixing between the inflaton and isocurvaton, which is parameterized by a constant $\mu$. We derive analytic formulae for the curvature perturbation two-, three-, four-, five-, and six-point functions explicitly in terms of the external wave-vectors in the limit where $\mu$ and the mass of the isocurvaton $m$ are both much smaller than $H$. In previous work, it has been noted that when $m/H$ and $\mu /H$ are small, the non-Gaussianities predicted by quasi-single field inflation give rise to long wavelength enhancements of the power spectrum for biased objects (e.g., galactic halos). We review this calculation, and calculate the analogous enhanced contribution to the bispectrum of biased objects. We determine the scale at which these enhanced terms are larger than the Gaussian piece. We also identify the scaling of these enhanced parts to the $n$-point function of biased objects.

    hep-phastro-ph.COhep-thPRD(2018)·75 citations
25. 25*

    Search for the standard model deviations in top quark precision studies at CMS

    Kirill Skovpen (on behalf of the CMS Collaboration)🇧🇪

    Precision studies of top quark properties provide a unique playground to test the predictions of the standard model and to search for new physics. Reviewed results from the CMS experiment done with the data collected at 8 TeV include studies of top quark Wtb anomalous and FCNC couplings, polarization, CP-violation, and spin correlation effects. No significant deviations from the SM predictions are observed.

    ↳ hep-exhep-ph2 citations
26. 26*

    Searches for Axion-Like Particles with NGC1275: Current and Future Bounds

    Nicholas Jennings🇬🇧

    Galaxy clusters contain large magnetic fields that make them excellent targets to search for ultralight Axion-Like Particles (ALPs). ALP-photon interconversion imprints quasi-sinusoidal oscillations on the X-ray spectra of point sources in or behind the cluster. The absence of substantial oscillations allows us to place bounds on $g_{a\gamma \gamma }$. Here the bounds from the {\it Chandra} X-ray observations of NGC1275 are presented, as well as those predicted for the {\it Athena} X-ray observatory, due to launch in 2028.

    ↳ astro-ph.HEhep-ph0 citations
27. 27*

    Exploratory studies for the position-space approach to hadronic light-by-light scattering in the muon $g-2$

    Nils Asmussen🇩🇪 · Antoine Gérardin🇩🇪 · Harvey B. Meyer🇩🇪 · Andreas Nyffeler🇩🇪

    The well-known discrepancy in the muon $g-2$ between experiment and theory demands further theory investigations in view of the upcoming new experiments. One of the leading uncertainties lies in the hadronic light-by-light scattering contribution (HLbL), that we address with our position-space approach. We focus on exploratory studies of the pion-pole contribution in a simple model and the fermion loop without gluon exchanges in the continuum and in infinite volume. These studies provide us with useful information for our planned computation of HLbL in the muon $g-2$ using full QCD.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·25 citations
28. 28*

    Anomalous Chiral Transport in Heavy Ion Collisions from Anomalous-Viscous Fluid Dynamics

    Shuzhe Shi🇺🇸 · Yin Jiang🇨🇳 · Elias Lilleskov🇺🇸 · Jinfeng Liao🇺🇸

    Chiral anomaly is a fundamental aspect of quantum theories with chiral fermions. How such microscopic anomaly manifests itself in a macroscopic many-body system with chiral fermions, is a highly nontrivial question that has recently attracted significant interest. As it turns out, unusual transport currents can be induced by chiral anomaly under suitable conditions in such systems, with the notable example of the Chiral Magnetic Effect (CME) where a vector current (e.g. electric current) is generated along an external magnetic field. A lot of efforts have been made to search for CME in heavy ion collisions, by measuring the charge separation effect induced by the CME transport. A crucial challenge in such effort, is the quantitative prediction for the CME signal. In this paper, we develop the Anomalous-Viscous Fluid Dynamics (AVFD) framework, which implements the anomalous fluid dynamics to describe the evolution of fermion currents in QGP, on top of the neutral bulk background described by the VISH2+1 hydrodynamic simulations for heavy ion collisions. With this new tool, we quantitatively and systematically investigate the dependence of the CME signal to a series of theoretical inputs and associated uncertainties. With realistic estimates of initial conditions and magnetic field lifetime, the predicted CME signal is quantitatively consistent with measured change separation data in 200GeV Au-Au collisions. Based on analysis of Au-Au collisions, we further make predictions for the CME observable to be measured in the planned isobaric (Ru-Ru v.s. Zr-Zr ) collision experiment, which could provide a most decisive test of the CME in heavy ion collisions.

    ↳ nucl-thhep-phAnnals Phys.(2018)·142 citations
29. 29*

    Prospects of Indirect Searches for Dark Matter at INO

    Sandhya Choubey🇮🇳 · Anushree Ghosh🇨🇱 · Deepak Tiwari🇮🇳

    The annihilation of Weakly Interactive Massive Particles (WIMP) in the centre of the sun could give rise to neutrino fluxes. We study the prospects of searching for these neutrinos at the upcoming Iron CALorimeter (ICAL) detector to be housed at the India-based Neutrino Observatory (INO). We perform ICAL simulations to obtain the detector efficiencies and resolutions in order to simulate muon events in ICAL due to neutrinos coming from annihilation of WIMP in the mass range $m_{\chi }=(3-100)$ GeV. The atmospheric neutrinos pose a major background for these indirect detection studies and can be reduced using the fact that the signal comes only from the direction of the sun. For a given WIMP mass, we find the opening angle ${\theta }_{90}$ such that 90 \% of the signal events are contained within this angle and use this cone-cut criteria to reduce the atmospheric neutrino background. The reduced background is then weighted by the solar exposure function at INO to obtain the final background spectrum for a given WIMP mass. We perform a ${\chi }^2$ analysis and present expected exclusion regions in the ${\sigma }_{SD}-m_{\chi }$ and ${\sigma }_{SI}-m_{\chi }$, where ${\sigma }_{SD}$ and ${\sigma }_{SI}$ are the WIMP-nucleon Spin-Dependent (SD) and Spin-Independent (SI) scattering cross-section, respectively. For a 10 years exposure and $m_{\chi }=25$ GeV, the expected 90 \% C.L. exclusion limit is found to be ${\sigma }_{SD}<6.87\times 10^{-41}$ cm${}^2$ and ${\sigma }_{SI}<7.75\times 10^{-43}$ cm${}^2$ for the ${\tau }^{+}{\tau }^{-}$ annihilation channel and ${\sigma }_{SD}<1.14\times 10^{-39}$ cm${}^2$ and ${\sigma }_{SI}<1.30\times 10^{-41}$ cm${}^2$ for the $b\bar{b}$ channel, assuming 100 \% branching ratio for each of the WIMP annihilation channel.

    ↳ hep-exastro-ph.HEhep-phJCAP(2018)·11 citations
30. 30*

    Finite temperature gluon propagator in Landau gauge: non-zero Matsubara frequencies and spectral densities

    Paulo J. Silva🇵🇹 · Orlando Oliveira🇵🇹 · David Dudal🇧🇪 · Martin Roelfs🇧🇪

    We report on the lattice computation of the Landau gauge gluon propagator at finite temperature, including the non-zero Matsubara frequencies. Moreover, the corresponding Källén-Lehmann spectral density is computed, using a Tikhonov regularisation together with the Morozov discrepancy principle. Implications for gluon confinement are also discussed.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·4 citations
31. 31*

    Gravitational-wave constraints on the neutron-star-matter Equation of State

    Eemeli Annala🇫🇮 · Tyler Gorda🇫🇮 · Aleksi Kurkela🇨🇭 · Aleksi Vuorinen🇫🇮

    The LIGO/Virgo detection of gravitational waves originating from a neutron-star merger, GW170817, has recently provided new stringent limits on the tidal deformabilities of the stars involved in the collision. Combining this measurement with the existence of two-solar-mass stars, we generate a generic family of neutron-star-matter Equations of State (EoSs) that interpolate between state-of-the-art theoretical results at low and high baryon density. Comparing the results to ones obtained without the tidal-deformability constraint, we witness a dramatic reduction in the family of allowed EoSs. Based on our analysis, we conclude that the maximal radius of a 1.4-solar-mass neutron star is 13.6 km, and that smallest allowed tidal deformability of a similar-mass star is $\Lambda (1.4M_{\odot })=120$.

    ↳ astro-ph.HEhep-phnucl-thPRL(2018)·1022 citations
32. 32*

    A generalized non-Gaussian consistency relation for single field inflation

    Rafael Bravo🇨🇱 · Sander Mooij🇨🇭 · Gonzalo A. Palma🇨🇱 · Bastián Pradenas🇨🇱

    We show that a perturbed inflationary spacetime, driven by a canonical single scalar field, is invariant under a special class of coordinate transformations together with a field reparametrization of the curvature perturbation in co-moving gauge. This transformation may be used to derive the squeezed limit of the 3-point correlation function of the co-moving curvature perturbations valid in the case that these do not freeze after horizon crossing. This leads to a generalized version of Maldacena's non-Gaussian consistency relation in the sense that the bispectrum squeezed limit is completely determined by spacetime diffeomorphisms. Just as in the case of the standard consistency relation, this result may be understood as the consequence of how long-wavelength modes modulate those of shorter wavelengths. This relation allows one to derive the well known violation to the consistency relation encountered in ultra slow-roll, where curvature perturbations grow exponentially after horizon crossing.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·75 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.