Thu·Apr 13, 2017Thursday·April 13, 2017

1. 01*

   On the lepton CP violation in a $\nu$2HDM with flavor

   E. Barradas-Guevara🇲🇽 · O. Félix-Beltrán🇲🇽 · F. Gonzalez-Canales🇲🇽 · M. Zeleny-Mora🇲🇽

   In this work we propose an extension to the Standard Model in which we consider the model 2HDM type-III plus massive neutrinos and the horizontal flavor symmetry $S_3$ $(\nu$2HDM$\otimes S_3)$. In the above framework and with the explicit breaking of flavor symmetry $S_3$, the Yukawa matrices in the flavor adapted basis are represented by means of a matrix with two texture zeroes. Also, the active neutrinos are considered as Majorana particles and their masses are generated through type-I seesaw mechanism. The unitary matrices that diagonalize the mass matrices, as well as the flavor mixing matrices, are expressed in terms of fermion mass ratios. Consequently, in the mass basis the entries of the Yukawa matrices naturally acquire the form of the so-called {\it Cheng-Sher ansatz}. For the leptonic sector of $\nu$2HDM$\otimes S_3$, we compare, through a ${\chi }^2$ likelihood test, the theoretical expressions of the flavor mixing angles with the masses and flavor mixing leptons current experimental data. The results obtained in this ${\chi }^2$ analysis are in very good agreement with the current experimental data. We also obtained an allowed value ranges for the "Dirac-like" phase factor, as well as for the two Majorana phase factors. Furthermore, we study the phenomenological implications of these numerical values of the CP-violation phases on the neutrinoless double beta decay, and for Long Base-Line neutrino oscillation experiments such as T2K, NO$\nu$A, and DUNE.

   hep-phPRD(2018)·11 citations
2. 02*

   Effective field theories for van der Waals interactions

   Nora Brambilla🇩🇪 · Vladyslav Shtabovenko🇩🇪 · Jaume Tarrús Castellà🇩🇪 · Antonio Vairo🇩🇪

   Van der Waals interactions between two neutral but polarizable systems at a separation $R$ much larger than the typical size of the systems are at the core of a broad sweep of contemporary problems in settings ranging from atomic, molecular and condensed matter physics to strong interactions and gravity. We reexamine the dispersive van der Waals interactions between two hydrogen atoms. The novelty of the analysis resides in the usage of nonrelativistic EFTs of QED. In this framework, the van der Waals potential acquires the meaning of a matching coefficient in an EFT suited to describe the low energy dynamics of an atom pair. It may be computed systematically as a series in $R$ times some typical atomic scale and in the fine structure constant $\alpha$. The van der Waals potential gets short range contributions and radiative corrections, which we compute in dimensional regularization and renormalize here for the first time. Results are given in $d$ spacetime dimensions. One can distinguish among different regimes depending on the relative size between $1/R$ and the typical atomic bound state energy $m{\alpha }^2$. Each regime is characterized by a specific hierarchy of scales and a corresponding tower of EFTs. The short distance regime is characterized by $1/R\gg m{\alpha }^2$ and the LO van der Waals potential is the London potential. We compute also NNNLO corrections. In the long distance regime we have $1/R\ll m{\alpha }^2$. In this regime, the van der Waals potential contains contact terms, which are parametrically larger than the Casimir-Polder potential that describes the potential at large distances. In the EFT the Casimir-Polder potential counts as a NNNLO effect. In the intermediate distance regime, $1/R\sim m{\alpha }^2$, a significantly more complex potential is obtained which we compare with the two previous limiting cases. We conclude commenting on the hadronic van der Waals case.

   hep-phnucl-thphysics.atom-phPRD(2017)·22 citations
3. 03*

   False Vacuum Decay in Gauge Theory

   Motoi Endo🇯🇵 · Takeo Moroi🇯🇵 · Mihoko M. Nojiri🇯🇵 · Yutaro Shoji🇯🇵

   The decay rate of a false vacuum is studied in gauge theory, paying particular attention to its gauge invariance. Although the decay rate should not depend on the gauge parameter $\xi$ according to the Nielsen identity, the gauge invariance of the result of a perturbative calculation has not been clearly shown. We give a prescription to perform a one-loop calculation of the decay rate, with which a manifestly gauge-invariant expression of the decay rate is obtained. We also discuss the renormalization necessary to make the result finite, and show that the decay rate is independent of the gauge parameter even after the renormalization.

   hep-phhep-thJHEP(2017)·28 citations
4. 04*

   Probing the CP nature of the Higgs coupling in $t\bar{t}h$ events at the LHC

   S. Amor dos Santos🇵🇹 · M.C.N. Fiolhais🇺🇸 · R. Frederix🇩🇪 · R. Gonçalo🇵🇹 · E. Gouveia🇵🇹 · R. Martins🇵🇹 · A. Onofre🇵🇹 · C.M. Pease🇵🇹 · H. Peixoto🇵🇹 · A. Reigoto🇵🇹 · R. Santos🇵🇹 · J. Silva🇵🇹

   The determination of the CP nature of the Higgs coupling to top quarks is addressed in this paper, using $t\bar{t}h$ events produced in $\sqrt{s}=13$ TeV proton-proton collisions at the LHC. Dileptonic final states are employed, with two oppositely charged leptons and four jets, corresponding to the decays $t\to b{W}^{+}\to b{\ell }^{+}{\nu }_{\ell }$, $\bar{t}\to \bar{b}{W}^{-}\to \bar{b}{\ell }^{-}{\bar{\nu }}_{\ell }$ and $h\to b\bar{b}$. Pure scalar ($h=H$), pure pseudo-scalar ($h=A$) and CP-violating Higgs boson signal events, generated with MadGraph5_aMC@NLO, are fully reconstructed through a kinematic fit. We furthermore generate samples that have both a CP-even and a CP-odd component in the $t\bar{t}h$ coupling in order to probe the ratio of the two components. New angular distributions of the decay products, as well as CP angular asymmetries, are explored in order to separate the scalar from the pseudo-scalar components of the Higgs boson and reduce the contribution from the dominant irreducible background, $t\bar{t}b\bar{b}$. Significant differences between the angular distributions and asymmetries are observed, even after the full kinematic fit reconstruction of the events, allowing to define the best observables for a global fit of the Higgs couplings parameters.

   hep-phPRD(2017)·61 citations
5. 05*

   Contribution of Orbital Angular Momentum to the Nucleon Spin

   Maryam Momeni-Feili🇮🇷 · Firooz Arash🇮🇷 · Fatemeh Taghavi-Shahri🇮🇷 · Abolfazl Shahveh🇬🇧

   We have calculated the Orbital Angular Momentum of quarks and gluons in the nucleon. The calculations are carried out in the next to leading order utilizing the so-called valon model. It is found that the average quark orbital angular momentum is positive, but small, and the average gluon orbital angular momentum is negative and large. We also report on some regularities about the total angular momentum of the quarks and the gluon, as well as on the orbital angular momentum of the separate partons. We have also provided partonic angular momentum, $L^{q,g}$ as a function of $Q^2$.

   hep-phInt.J.Mod.Phys.A(2017)·1 citation
6. 06*

   Low-Scale D-term Inflation and the Relaxion

   Jason L. Evans🇰🇷 · Tony Gherghetta🇺🇸 · Natsumi Nagata🇯🇵 · Marco Peloso🇺🇸

   We present a dynamical cosmological solution that simultaneously accounts for the early inflationary stage of the Universe and solves the supersymmetric little hierarchy problem via the relaxion mechanism. First, we consider an inflationary potential arising from the $D$-term of a new $U(1)$ gauge symmetry with a Fayet--Iliopolous term, that is independent of the relaxion. A technically natural, small $U(1)$ gauge coupling, $g\lesssim 10^{-8}$, allows for a low Hubble scale of inflation, $H_I\lesssim 10^5$ GeV, which is shown to be consistent with Planck data. This feature is then used to realize a supersymmetric two-field relaxion mechanism, where the second field is identified as the inflaton provided that $H_I\lesssim 10$ GeV. The inflaton controls the relaxion barrier height allowing the relaxion to evolve in the early Universe and scan the supersymmetric soft masses. After electroweak symmetry is broken, the relaxion settles at a local supersymmetry-breaking minimum with a range of $F$-term values that can naturally explain supersymmetric soft mass scales up to $10^6$ GeV.

   hep-phPRD(2017)·31 citations
7. 07*

   Introduction to Flavour Physics and CP Violation

   Monika Blanke🇩🇪

   These lecture notes provide an introduction to the theoretical concepts of flavour physics and CP violation, based on a series of lectures given at the ESHEP 2016 summer school. In the first lecture we review the basics of flavour and CP violation in the Standard Model. The second lecture is dedicated to the phenomenology of K and B meson decays, where we focus on a few representative observables. In the third lecture we give an introduction to flavour physics beyond the Standard Model, both within the framework of Minimal Flavour Violation and beyond.

   hep-phCERN Yellow Rep.School Proc.(2017)·16 citations
8. 08*

   Probing extra Yukawa couplings by precision measurements of Higgs properties

   Wei-Shu Hou🇹🇼 · Mariko Kikuchi🇹🇼

   If one removes any \emph{ad hoc} symmetry assumptions, the general two Higgs doublet model should have additional Yukawa interactions independent from fermion mass generation, in general involving flavor changing neutral Higgs couplings. These extra couplings can affect the discovered Higgs boson $h$ through fermion loop contributions. We calculate the renormalized $hZZ$ coupling at one-loop level %by on-shell and minimal subtraction scheme, and evaluate the dependence on heavy Higgs boson mass and extra Yukawa coupling ${\rho }_{tt}$. Precision measurements at future colliders can explore the parameter space, and can give stronger bound on ${\rho }_{tt}$ than the current bound from flavor experiments. As a side result, we find that if ${\rho }_{tt}\cos \gamma <0$, where $\cos \gamma$ is the exotic Higgs component of $h$, the ${\rho }_{tt}$-induced top loop contribution cancels against bosonic loop contributions, and one may have alignment without decoupling, namely $\sin (-\gamma )\simeq 1$, but exotic scalar bosons could have masses at several hundred GeV.

   hep-phPRD(2017)·10 citations
9. 09*

   Baryonic Higgs at the LHC

   Michael Duerr🇩🇪 · Pavel Fileviez Perez🇺🇸 · Juri Smirnov🇮🇹

   We investigate the possible collider signatures of a new Higgs in simple extensions of the Standard Model where baryon number is a local symmetry spontaneously broken at the low scale. We refer to this new Higgs as "Baryonic Higgs". This Higgs has peculiar properties since it can decay into all Standard Model particles, the leptophobic gauge boson, and the vector-like quarks present in these theories to ensure anomaly cancellation. We investigate in detail the constraints from the $\gamma \gamma$, $Z\gamma$, $ZZ$, and $WW$ searches at the Large Hadron Collider, needed to find a lower bound on the scale at which baryon number is spontaneously broken. The di-photon channel turns out to be a very sensitive probe in the case of small scalar mixing and can severely constrain the baryonic scale. We also study the properties of the leptophobic gauge boson in order to understand the testability of these theories at the LHC.

   hep-phhep-exJHEP(2017)·11 citations
10. 10*

    Quasi-distribution amplitudes for pion and kaon via the nonlocal chiral-quark model

    Seung-il Nam🇰🇷

    We investigate the pseudoscalar (PS) meson ($\pi$ and $K$) quasi-distribution amplitude (QDA), which is supposed to be an asymptotic analog to the meson distribution amplitude (DA) ${\varphi }_{\pi ,K}(x)$ in the limit of the large longitudinal PS-meson momentum, i.e. $p_3\to \infty$, in the nonperturbative region. For this purpose, we employ the nonlocal chiral-quark model (NLChQM) in the light-front formalism with a minimal Fock-state for the mesons $\sim q\bar{q}$ at the low-energy scale parameter of the model $\Lambda \sim 1$ GeV. As a trial, we extract the transverse-momentum distribution amplitude (TMDA) from the light-front wave function within the model, and convert it to QDA with help of the virtuality-distribution amplitude. By doing that, we derive an analytical expression for the nonperturbative QDA with the current-quark mass correction up to $\mathcal{O}(\Delta m_q)$. Numerically, we confirm that the obtained TMDA reproduces the experimental data for the photon-pion transition form factor $F_{\gamma {\gamma }^{\ast }{\pi }^0}(Q^2)$ at the low-$Q^2$ qualitatively well. We also observe that the obtained QDA approaches to DA as $p_3$ increases, showing the symmetric and asymmetric curves with respect to $x$ for the pion and kaon, respectively, due to the current-quark mass difference $m_{u,d}\ll m_s$. Assigning $\xi \equiv 2x-1$, the moments $⟨{\xi }^n{⟩}_{\pi ,K}$ are computed, using the pion and kaon QDAs, and there appear only a few percent deviations in the moments for $p_3\gtrsim 30\Lambda$ in comparison to the values calculated directly from DAs. It turns out that the higher moments are more sensitive to the change of $p_3$, whereas the lower ones depend less on it.

    hep-phhep-latnucl-thMod.Phys.Lett.A(2017)·28 citations
11. 11*

    Multi-loop calculations: numerical methods and applications

    S. Borowka🇨🇭 · G. Heinrich🇩🇪 · S. Jahn🇩🇪 · S.P. Jones🇩🇪 · M. Kerner🇩🇪 · J. Schlenk🇬🇧

    We briefly review numerical methods for calculations beyond one loop and then describe new developments within the method of sector decomposition in more detail. We also discuss applications to two-loop integrals involving several mass scales.

    hep-phJ.Phys.Conf.Ser.(2017)·1 citation
12. 12*

    Anomaly-Free Dark Matter Models are not so Simple

    John Ellis🇬🇧 · Malcolm Fairbairn🇬🇧 · Patrick Tunney🇬🇧

    We explore the anomaly-cancellation constraints on simplified dark matter (DM) models with an extra U(1)${}^{\prime }$ gauge boson $Z^{\prime }$. We show that, if the Standard Model (SM) fermions are supplemented by a single DM fermion $\chi$ that is a singlet of the SM gauge group, and the SM quarks have non-zero U(1)${}^{\prime }$ charges, the SM leptons must also have non-zero U(1)${}^{\prime }$ charges, in which case LHC searches impose strong constraints on the $Z^{\prime }$ mass. Moreover, the DM fermion $\chi$ must have a vector-like U(1)${}^{\prime }$ coupling. If one requires the DM particle to have a purely axial U(1)${}^{\prime }$ coupling, which would be the case if $\chi$ were a Majorana fermion and would reduce the impact of direct DM searches, the simplest possibility is that it is accompanied by one other new singlet fermion, but in this case the U(1)${}^{\prime }$ charges of the SM leptons still do not vanish. This is also true in a range of models with multiple new singlet fermions with identical charges. Searching for a leptophobic model, we then introduce extra fermions that transform non-trivially under the SM gauge group. We find several such models if the DM fermion is accompanied by two or more other new fermions with non-identical charges, which may have interesting experimental signatures. We present benchmark representatives of the various model classes we discuss.

    hep-phhep-exJHEP(2017)·65 citations
13. 13*

    Theory of rare charm decays into leptons

    Alexey A Petrov🇺🇸

    Studies of rare decays of charmed mesons into the final states containing leptons is an important vehicle in low-energy searches for new physics. I review theoretical implications of those studies involving transitions with and without lepton flavor conservation. I argue that lepton-flavor violation (LFV) could be successfully studied in heavy quarkonium transitions yielding more sensitive results than similar searches involving $D$ mesons.

    hep-phhep-exPoS(2017)·3 citations
14. 14*

    Systematics of quark/gluon tagging

    Philippe Gras🇫🇷 · Stefan Höche🇺🇸 · Deepak Kar🇿🇦 · Andrew Larkoski🇺🇸 · Leif Lönnblad🇸🇪 · Simon Plätzer🇬🇧 · Andrzej Siódmok🇨🇭 · Peter Skands🇦🇺 · Gregory Soyez🇫🇷 · Jesse Thaler🇺🇸

    By measuring the substructure of a jet, one can assign it a "quark" or "gluon" tag. In the eikonal (double-logarithmic) limit, quark/gluon discrimination is determined solely by the color factor of the initiating parton (C_F versus C_A). In this paper, we confront the challenges faced when going beyond this leading-order understanding, using both parton-shower generators and first-principles calculations to assess the impact of higher-order perturbative and nonperturbative physics. Working in the idealized context of electron-positron collisions, where one can define a proxy for quark and gluon jets based on the Lorentz structure of the production vertex, we find a fascinating interplay between perturbative shower effects and nonperturbative hadronization effects. Turning to proton-proton collisions, we highlight a core set of measurements that would constrain current uncertainties in quark/gluon tagging and improve the overall modeling of jets at the Large Hadron Collider.

    hep-phhep-exJHEP(2017)·185 citations
15. 15*

    Local and global $\Lambda$ polarization in a vortical fluid

    Hui Li🇨🇳 · Hannah Petersen🇩🇪 · Long-Gang Pang🇺🇸 · Qun Wang🇨🇳 · Xiao-Liang Xia🇨🇳 · Xin-Nian Wang🇨🇳

    We compute the fermion spin distribution in the vortical fluid created in off-central high-energy heavy-ion collisions. We employ the event-by-event (3+1)D viscous hydrodynamic model. The spin polarization density is proportional to the local fluid vorticity in quantum kinetic theory. As a result of strong collectivity, the spatial distribution of the local vorticity on the freeze-out hyper-surface strongly correlates to the rapidity and azimuthal angle distribution of fermion spins. We investigate the sensitivity of the local polarization to the initial fluid velocity in the hydrodynamic model and compute the global polarization of {\Lambda} hyperons by the AMPT model. The energy dependence of the global polarization agrees with the STAR data.

    ↳ nucl-thhep-exhep-phNPA(2017)·19 citations
16. 16*

    Collective flow from AA, pA to pp collisions - Toward a unified paradigm

    Wei Li🇺🇸

    I give an overview of the latest development in understanding collective phenomena in high-multiplicity hadronic final state from relativistic nucleus-nucleus, proton-nucleus and proton-proton collisions. Upon reviewing the experimental data and confronting them with theoretical models, a unified paradigm in describing the observed collectivity across all hadronic collision systems is emerging. Potential future paths toward addressing key open questions, especially on collectivity in small systems (pp, pA), are discussed.

    ↳ nucl-exhep-exhep-phnucl-thNPA(2017)·22 citations
17. 17*

    Two-photon exchange corrections to ${\gamma }^{\ast }N\Delta$ form factors for $Q^2\le 4$ (Gev/$c$)${}^2$

    Hai-Qing Zhou🇨🇳 · Shin Nan Yang🇹🇼

    We evaluate the corrections of the two-photon exchange (TPE) process on the ${\gamma }^{\ast }N\Delta$ transition form factors. The contributions of the TPE process to the $eN\to e\Delta (1232)\to eN\pi$ are calculated in a hadronic model with the inclusion of only the elastic nucleon intermediate states, to estimate its effects on the multipoles $M_{1^{+}}^{(3/2)},E_{1^{+}}^{(3/2)},S_{1^{+}}^{(3/2)}$ at the $\Delta$ peak. We find that TPE effects on $G_M^{\ast }$ is very small. $G_E^{\ast },$ and $G_C^{\ast }$ are also little affected at small $Q^2$. For $G_E^{\ast }$, the TPE effects reach about $3-8\%$ near $Q^2\sim 4$ GeV${}^2$, depending on the model, MAID or SAID, used to emulate the data. For $G_C^{\ast }$, the TPE effects decrease rapidly with increasing $ϵ$ while growing with increasing $Q^2$ to reach $\sim 6-15\%$ with $Q^2\sim 4$ GeV${}^2$ at $ϵ=0.2$. Sizeable TPE corrections to $G_E^{\ast }$ and $G_C^{\ast }$ found here points to the need of including TPE effects in the multipole analysis in the region of high $Q^2$ and small $ϵ$. The TPE corrections to $R_{EM}$ and $R_{SM}$ obtained in our hadronic calculation are compared with those obtained in a partonic calculation for moderate momentum transfer of $2<Q^2<4$ GeV${}^2$.

    ↳ nucl-thhep-phnucl-exPRC(2017)·14 citations
18. 18*

    Examination of $N^{\ast }(1535)$ as a probe to observe the partial restoration of chiral symmetry in nuclear matter

    Daiki Suenaga🇯🇵

    We investigate modifications of mass and decay width of $N^{\ast }(1535)$ in nuclear matter in a chiral symmetric way. The nucleon and $N^{\ast }(1535)$ are introduced by a parity doublet model, and nuclear matter is constructed by one-loop diagrams of the nucleon and $N^{\ast }(1535)$. The decay width of $N^{\ast }(1535)$ is studied respecting chiral symmetry. Our calculations show that the partial width of ${\Gamma }_{N^{\ast }\to N\pi }$ is slightly broadened by a collisional broadening, and that of ${\Gamma }_{N^{\ast }\to N\eta }$ is drastically suppressed at density. As a result, the total decay width ${\Gamma }_{\mathrm{tot}}$ gets small at density. These modifications, especially the drastic narrowing of partial width of ${\Gamma }_{N^{\ast }\to N\eta }$, together with the dropping of mass of $N^{\ast }(1535)$ provide experiments for observing the partial restoration of chiral symmetry in nuclear matter by means of $N^{\ast }(1535)$ resonance with useful information.

    ↳ nucl-thhep-phPRC(2018)·32 citations
19. 19*

    Effects of jet-induced medium excitation in $\gamma$-hadron correlation in A+A collisions

    Wei Chen🇨🇳 · Shanshan Cao🇺🇸 · Tan Luo🇨🇳 · Long-Gang Pang🇺🇸 · Xin-Nian Wang🇨🇳

    Coupled Linear Boltzmann Transport and hydrodynamics (CoLBT-hydro) is developed for co-current and event-by-event simulations of jet transport and jet-induced medium excitation (j.i.m.e.) in high-energy heavy-ion collisions. This is made possible by a GPU parallelized (3+1)D hydrodynamics that has a source term from the energy-momentum deposition by propagating jet shower partons and provides real time update of the bulk medium evolution for subsequent jet transport. Hadron spectra in $\gamma$-jet events of A+A collisions at RHIC and LHC are calculated for the first time that include hadrons from both the modified jet and j.i.m.e.. CoLBT-hydro describes well experimental data at RHIC on the suppression of leading hadrons due to parton energy loss. It also predicts the enhancement of soft hadrons from j.i.m.e. The onset of soft hadron enhancement occurs at a constant transverse momentum due to the thermal nature of soft hadrons from j.i.m.e. which also have a significantly broadened azimuthal distribution relative to the jet direction. Soft hadrons in the $\gamma$ direction are, on the other hand, depleted due to a diffusion wake behind the jet.

    ↳ nucl-thhep-phPLB(2018)·186 citations
20. 20*

    Low-$x$ Physics in $pA$ Collisions and at the EIC

    Bo-Wen Xiao🇨🇳

    In this proceeding, I review what we have learned, and what we will be able to learn, about low-$x$ physics from proton-nucleus ($pA$) collisions at RHIC and the LHC, and how this complements future Electron-Ion Collider (EIC) measurements. EIC not only will provide us essential and complementary information about the gluon saturation to the knowledge that we have learned from $pA$ collisions at RHIC and the LHC, it will also allow us to visualize the internal structure of protons and nuclei in a multi-dimensional fashion with unprecedented precision.

    ↳ nucl-thhep-phnucl-exNPA(2017)·3 citations
21. 21*

    Prescriptions on antiproton cross section data for precise theoretical antiproton flux predictions

    Fiorenza Donato🇮🇹 · Michael Korsmeier🇩🇪 · Mattia Di Mauro🇺🇸

    After the breakthrough from the satellite-borne PAMELA detector, the flux of cosmic-ray (CR) antiprotons has been provided with unprecedented accuracy by AMS-02 on the International Space Station. Its data spans an energy range from below 1 GeV up to 400 GeV and most of the data points contain errors below the amazing level of 5%. The bulk of the antiproton flux is expected to be produced by the scatterings of CR protons and helium off interstellar hydrogen and helium atoms at rest. The modeling of these interactions, which requires the relevant production cross sections, induces an uncertainty in the determination of the antiproton source term that can even exceed the uncertainties in the CR $\bar{p}$ data itself. The aim of the present analysis is to determine the uncertainty required for $p+p\to \bar{p}+X$ cross section measurements such that the induced uncertainties on the $\bar{p}$ flux are at the same level. Our results are discussed both in the center-of-mass reference frame, suitable for collider experiments, and in the laboratory frame, as occurring in the Galaxy. We find that cross section data should be collected with accuracy better that few percent with proton beams from 10 GeV to 6 TeV and a pseudorapidity $\eta$ ranging from 2 to almost 8 or, alternatively, with $p_T$ from 0.04 to 2 GeV and $x_R$ from 0.02 to 0.7. Similar considerations hold for the $p$He production channel. The present collection of data is far from these requirements. Nevertheless, they could, in principle, be reached by fixed target experiments with beam energies in the reach of CERN accelerators.

    ↳ astro-ph.HEhep-exhep-phPRD(2017)·42 citations
22. 22*

    Disentangling flow and signals of Chiral Magnetic Effect in U+U, Au+Au and p+Au collisions

    Prithwish Tribedy (for the STAR Collaboration)🇺🇸

    We present STAR measurements of the charge-dependent three-particle correlator ${\gamma }^{a,b}=⟨\cos ({\varphi }_1^a+{\varphi }_2^b-2{\varphi }_3)⟩/v_2\{2\}$ and elliptic flow $v_2\{2\}$ in U+U, Au+Au and p+Au collisions at RHIC. The difference $\Delta \gamma =\gamma (\mathrm{opposite}-\mathrm{sign})-\gamma (\mathrm{same}-\mathrm{sign})$ measures charge separation across the reaction plane, a predicted signal of the Chiral Magnetic Effect (CME). Although charge separation has been observed, it has been argued that the measured separation can also be explained by elliptic flow related backgrounds. In order to separate the two effects, we perform measurements of the $\gamma$-correlator where background expectations differ from magnetic field driven effects. A differential measurement of $\gamma$ with the relative pseudorapidity ($\Delta \eta$) between the first and second particles indicate that $\Delta \gamma$ in peripheral A+A and p+A collisions are dominated by short-range correlations in $\Delta \eta$. However, a relatively wider component of the correlation in $\Delta \eta$ tends to vanish the same way as projected magnetic field as predicted by MC-Glauber simulations.

    ↳ nucl-exhep-phnucl-thNPA(2017)·24 citations
23. 23*

    Investigating the X-ray counterparts to unidentified sources in the 1000-orbit INTEGRAL/IBIS catalogue

    R. Landi🇮🇹 · L. Bassani🇮🇹 · A. Bazzano🇮🇹 · A. J. Bird🇬🇧 · M. Fiocchi🇮🇹 · A. Malizia🇮🇹 · F. Panessa🇮🇹 · V. Sguera🇮🇹 · P. Ubertini🇮🇹

    The latest INTEGRAL/IBIS all-sky survey lists 219 hard X-ray sources whose nature is still unknown. We report on our ongoing campaign aimed at identifying these high-energy emitters by exploiting the focusing capabilities of the X-ray Telescope (XRT, 0.2-10 keV) on board Swift, which allow an enhancement of the source localisation to arcsec level, thus facilitating the identification of the likely counterpart. By cross-correlating the list of the unidentified IBIS sources included in the latest IBIS catalogue with Swift/XRT archival data, we found a set of 14 objects, not yet reported in the literature, for which XRT data were available. We found no detection in only one case, a single X-ray association in 9 sources, and 2/3 associations in the remaining objects. We then made use of multi-waveband archives to search for counterparts at other wavelengths of these XRT detections and exploited X-ray spectral information in an attempt to determine their nature and association with the IBIS object. As a result of our analysis, we identified a single counterpart for 13 sources, although in some cases its nature/class could not be assessed on the basis of the information collected. More specifically, we found that SWIFT J0924.2-3141 and SWIFT J1839.1-5717 are absorbed AGN, while SWIFT J0800.7-4309 and 1SWXRT J230642.8+550817 are Cataclysmic Variable binary systems. Finally, we found that IGR J14059-6116 is likely associated with the Fermi source 3FGL J1405.4-6119. In the case of XMMSL1 J030715.5-545536 no XRT counterpart was detected. In all the other cases, optical/infrared spectroscopy is necessary to classify properly each X-ray counterpart and confirm their association with the INTEGRAL/IBIS detection.

    ↳ astro-ph.HEhep-phMNRAS(2017)·16 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.