Tue·Jul 19, 2016Tuesday·July 19, 2016

1. 01*

   Two-loop corrections to the $\rho$ parameter in Two-Higgs-Doublet Models

   Stephan Hessenberger🇩🇪 · Wolfgang Hollik🇩🇪

   Models with two scalar doublets are among the simplest extensions of the Standard Model which fulfill the relation $\rho =1$ at lowest order for the $\rho$ parameter as favored by experimental data for electroweak observables allowing only small deviations from unity. Such small deviations $\Delta \rho$ originate exclusively from quantum effects with special sensitivity to mass splittings between different isospin components of fermions and scalars. In this paper the dominant two-loop electroweak corrections to $\Delta \rho$ are calculated in the $CP$-conserving THDM, resulting from the top-Yukawa coupling and the self-couplings of the Higgs bosons in the gauge-less limit. The on-shell renormalization scheme is applied. With the assumption that one of the $CP$-even neutral scalars represents the scalar boson observed by the LHC experiments, with standard properties, the two-loop non-standard contributions in $\Delta \rho$ can be separated from the standard ones. These contributions are of particular interest since they increase with mass splittings between non-standard Higgs bosons and can be additionally enhanced by $\tan \beta$ and ${\lambda }_5$, an additional free coefficient of the Higgs potential, and can thus modify the one-loop result substantially. Numerical results are given for the dependence on the various non-standard parameters, and the influence on the calculation of electroweak precision observables is discussed.

   hep-phEPJC(2017)·30 citations
2. 02*

   Photon-initiated processes at high mass

   L.A. Harland-Lang🇬🇧 · V.A. Khoze🇬🇧 · M.G. Ryskin🇷🇺

   We consider the influence of photon-initiated processes on high-mass particle production. We discuss in detail the photon PDF at relatively high parton $x$, relevant to such processes, and evaluate its uncertainties. In particular we show that, as the dominant contribution to the input photon distribution is due to coherent photon emission, at phenomenologically relevant scales the photon PDF is already well determined in this region, with the corresponding uncertainties under good control. We then demonstrate the implications of this result for the example processes of high-mass lepton and $W$ boson pair production at the LHC and FCC. While for the former process the photon-initiated contribution is expected to be small, in the latter case we find that it is potentially significant, in particular at larger masses.

   hep-phhep-exPRD(2016)·45 citations
3. 03*

   Chiral heavy fermions in a two Higgs doublet model: 750 GeV resonance or not

   Shaouly Bar-Shalom🇮🇱 · Amarjit Soni🇺🇸

   We revisit models where a heavy chiral 4th generation doublet of fermions is embedded in a class of two Higgs doublets models (2HDM) with a discrete $Z_2$ symmetry, which couples the "heavy" scalar doublet only to the 4th generation fermions and the "light" one to the Standard Model (SM) fermions - the so-called 4G2HDM introduced by us several years ago. We study the constraints imposed on the 4G2HDM from direct searches of heavy fermions, from precision electroweak data (PEWD) and from the measured production and decay signals of the 125 GeV scalar, which in the 4G2HDM corresponds to the lightest CP-even scalar h. We then show that the recently reported excess in the $\gamma \gamma$ spectrum around 750 GeV can be accommodated by the heavy CP-even scalar of the 4G2HDM, H, resulting in a unique choice of parameter space: negligible mixing (sin\alpha ~ O(0.001)) between the two CP-even scalars h,H and heavy 4th generation quark and lepton masses m_t',m_b' < 400 GeV and $m_{{\nu }^{\prime }},m_{{\tau }^{\prime }}$ > 900 GeV, respectively. Whether or not the 750 GeV \gamma \gamma resonance is confirmed, interesting phenomenology emerges in q' - Higgs systems (q'=t',b'), that can be searched for at the LHC. For example, the heavy scalar states of the model, S=H,A,H^+, may have BR(S -> q'q') ~ O(1), giving rise to observable q'q' signals on resonance, followed by the flavor changing q' decays t'->uh (u=u,c) and/or b'->dh (d=d,s,b). This leads to distinct high jet-multiplicity signatures, with or without charged leptons, of the form q'q' -> (nj + mb + lW)_S (j and b being light and b-quark jets, respectively), with n+m+l =6-8 and unique kinematic features. It is also shown that the 4G2HDM can easily accommodate the interesting recent indications of a percent-level branching ratio in the lepton-flavor-violating (LFV) decay $h\to \tau \mu$ of the 125 GeV Higgs, if confirmed.

   hep-phhep-exPLB(2017)·6 citations
4. 04*

   Matter Neutrino Resonance Transitions above a Neutron Star Merger Remnant

   Yong-Lin Zhu🇺🇸 · Albino Perego🇩🇪 · Gail C. McLaughlin🇺🇸

   The Matter-Neutrino Resonance (MNR) phenomenon has the potential to significantly alter the flavor content of neutrinos emitted from compact object mergers. We present the first calculations of MNR transitions using neutrino self interaction potentials and matter potentials generated selfconsistently from a dynamical model of a three-dimensional neutron star merger. In the context of the single angle approximation, we find that Symmetric and Standard MNR transitions occur in both normal and inverted hierarchy scenarios. We examine the spatial regions above the merger remnant where propagating neutrinos will encounter the matter neutrino resonance and find that a significant fraction of the neutrinos are likely to undergo MNR transitions.

   hep-phastro-ph.HEnucl-thPRD(2016)·86 citations
5. 05*

   Spectrum and electromagnetic transitions of bottomonium

   Wei-Jun Deng🇨🇳 · Hui Liu🇨🇳 · Long-Cheng Gui🇨🇳 · Xian-Hui Zhong🇨🇳

   Stimulated by the exciting progress in the observation of new bottomonium states, we study the bottomonium spectrum. To calculate the mass spectrum, we adopt a nonrelativistic screened potential model. The radial Schrödinger equation is solved with the three-point difference central method, where the spin-dependent potentials are dealt with non-perturbatively. With this treatment, the corrections of the spin-dependent potentials to the wave functions can be included successfully. Furthermore, we calculate the electromagnetic transitions of the $nS$ ($n\le 4$), $nP$ ($n\le 3$), and $nD$ ($n\le 2$) bottomonium states with a nonrelativistic electromagnetic transition operator widely applied to meson photoproduction reactions. Our predicted masses, hyperfine and fine splittings, electromagnetic transition widths and branching ratios of the bottomonium states are in good agreement with the available experimental data. Especially, the EM transitions of ${\rm Y}(3S)\to {\chi }_{b1,2}(1P)\gamma$, which were not well understood in previous studies, can be reasonably explained by considering the corrections of the spin-dependent interactions to the wave functions. We also discuss the observations of the missing bottomonium states by using radiative transitions. Some important radiative decay chains involving the missing bottomonium states are suggested to be observed. We hope our study can provide some useful references to observe and measure the properties of bottomonium mesons in forthcoming experiments.

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

   Forward Hadron Productions in Proton-Proton Collisions in Small-$x$ Formalism

   Kazuhiro Watanabe🇨🇳 · Bo-Wen Xiao🇨🇳

   Employing the so-called hybrid formalism, we calculate the cross section of inclusive hadron production in proton-proton collisions at forward rapidity in small-$x$ formalism at one-loop order. For the case of hadron production at forward rapidity, we can uses collinear parton distributions for projectile proton and $k_{\perp }$ dependent gluon distribution for target proton. We show that collinear divergences associated with initial and final state parton radiations are renormalized into parton distributions and fragmentation functions in terms of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equation, respectively. Furthermore, rapidity divergence can be absorbed into the wave function of target proton which gives rise to the well-known Balitsky-Fadin-Kuraev-Lipatov equation. These divergences are completely separated from the short distance partonic hard parts, which is now finite at the next-to-leading order accuracy. The result presented in this paper can be reckoned as a baseline calculation without any non-linear QCD effects in small-$x$ formalism. As a consistency check, we compare our results with the previous calculation for non-linear proton-nucleus collisions in the small-$x$ formalism and find complete agreement in the dilute and large $N_c$ limit. In phenomenology, the direct comparison of the above two separate calculations can reveal the role and strength of the non-linear dynamics in high energy QCD, and thus help us reliably study the onset of gluon saturation when genuine non-linear interactions become important.

   hep-phnucl-thPRD(2016)·4 citations
7. 07*

   New physics in neutral $\text{D}\to \text{VV}$ modes

   Aritra Biswas🇮🇳 · Sanjoy Mandal🇮🇳

   We show that it is possible to construct observables to test the existence of new physics in a model independent way for the $D^0\to VV$ modes using a time-dependent analysis of the neutral $D$ meson. We show that it is possible to identify whether the NP is due to decay, mixing or a combination of both. We also provide numerical estimates for the polarization amplitudes for the $D^0\to \overline{K^{\ast 0}}{\rho }^0$ mode and show that our analysis is consistent with the present data.

   hep-phInt.J.Mod.Phys.A(2016)·0 citations
8. 08*

   Reanalysis of the $X(3915)$, $X(4500)$ and $X(4700)$ with QCD sum rules

   Zhi-Gang Wang🇨🇳

   In this article, we study the $C{\gamma }_5\otimes {\gamma }_{5}C$ type and $C\otimes C$ type scalar $cs\bar{c}\bar{s}$ tetraquark states with the QCD sum rules by calculating the contributions of the vacuum condensates up to dimension 10 in a consistent way. The ground state masses $M_{C{\gamma }_5\otimes {\gamma }_{5}C}=3.89\pm 0.05\mathrm{GeV}$ and $M_{C\otimes C}=5.48\pm 0.10\mathrm{GeV}$ support assigning the $X(3915)$ to be the ground state $C{\gamma }_5\otimes {\gamma }_{5}C$ type tetraquark state with $J^{PC}=0^{++}$, but do not support assigning the $X(4700)$ to be the ground state $C\otimes C$ type $cs\bar{c}\bar{s}$ tetraquark state with $J^{PC}=0^{++}$. Then we tentatively assign the $X(3915)$ and $X(4500)$ to be the 1S and 2S $C{\gamma }_5\otimes {\gamma }_{5}C$ type scalar $cs\bar{c}\bar{s}$ tetraquark states respectively, and obtain the 1S mass $M_{1S}=3.85_{-0.17}^{+0.18}\mathrm{GeV}$ and 2S mass $M_{2S}=4.35_{-0.11}^{+0.10}\mathrm{GeV}$ from the QCD sum rules, which support assigning the $X(3915)$ to be the 1S $C{\gamma }_5\otimes {\gamma }_{5}C$ type tetraquark state, but do not support assigning the $X(4500)$ to be the 2S $C{\gamma }_5\otimes {\gamma }_{5}C$ type tetraquark state.

   hep-phEPJA(2017)·28 citations
9. 09*

   Explanation of $B\to K^{(\ast )}{\ell }^{+}{\ell }^{-}$ and muon $g-2$, and implications at the LHC

   Chuan-Hung Chen🇹🇼 · Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

   More than $3\sigma$ deviations from the standard model are observed in the angular observable $P_5^{\prime }$ of $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ and muon $g-2$. To resolve these anomalies, we extend the standard model by adding two leptoquarks. It is found that the signal strength of the diphoton Higgs decay can exhibit a significant deviation from unity and is within the data errors. Although ${\ell }_i\to {\ell }_j\gamma$ puts severe bounds on some couplings, it is found that the excesses of $P_5^{\prime }$ and muon $g-2$ can still be explained and can be accommodated to the measurement of $B_s\to {\mu }^{+}{\mu }^{-}$ in this model. In addition, the leptoquark effects can also explain the LHCb measurement of $R_K=BR(B^{+}\to K^{+}{\mu }^{+}{\mu }^{-})/BR(B^{+}\to K^{+}{e}^{+}{e}^{-})=0.745_{-0.074}^{+0.090}\pm 0.036$, which shows a $2.6\sigma$ deviation from the standard model prediction.

   hep-phhep-exPRD(2016)·51 citations
10. 10*

    Two charmoniumlike charged axial resonances near 3885 MeV

    M.B. Voloshin🇺🇸

    It is argued that the charged $Z_c^{+}(3885)$ resonance, treated as a `molecular' state of charmed $D$ and $D^{\ast }$ mesons, is likely to consist of two peaks unequally coupled to the $D^{\ast +}{\bar{D}}^0$ and $D^{+}{\bar{D}}^{\ast 0}$ channels. The peaks should be split in mass by at least approximately 1.5 MeV. This behavior arises from an enhancement of the effect of isospin violation in the masses of the $D$ and $D^{\ast }$ mesons due to apparent suppression of forces between the mesons depending on the spins of the heavy as well as of the light quarks. The suggested double-peak structure can be studied either by direct shape measurement in the channels with heavy mesons, or by isospin-violating transitions from $Z_c^{\pm }(3885)$ to the states of charmonium plus a light meson.

    hep-phhep-exPRD(2016)·2 citations
11. 11*

    Rare B-Meson Decays at the Crossroads

    Ahmed Ali🇩🇪

    Experimental era of rare $B$-decays started with the measurement of $B\to K^{\ast }\gamma$ by CLEO in 1993, followed two years later by the measurement of the inclusive decay $B\to X_s\gamma$, which serves as the standard candle in this field. The frontier has moved in the meanwhile to the experiments at the LHC, in particular, LHCb, with the decay $B^0\to {\mu }^{+}{\mu }^{-}$ at about 1 part in $10^{10}$ being the smallest branching fraction measured so far. Experimental precision achieved in this area has put the standard model to unprecedented stringent tests and more are in the offing in the near future. I review some key measurements in radiative, semileptonic and leptonic rare $B$-decays, contrast them with their estimates in the SM, and focus on several mismatches reported recently. They are too numerous to be ignored, yet , standing alone, none of them is significant enough to warrant the breakdown of the SM. Rare $B$-decays find themselves at the crossroads, possibly pointing to new horizons, but quite likely requiring an improved theoretical description in the context of the SM. An independent precision experiment such as Belle II may help greatly in clearing some of the current experimental issues.

    hep-phhep-exhep-latInt.J.Mod.Phys.A(2016)·7 citations
12. 12*

    Single-inclusive jet production in electron-nucleon collisions through next-to-next-to-leading order in perturbative QCD

    Gabriel Abelof🇺🇸 · Radja Boughezal🇺🇸 · Xiaohui Liu🇺🇸 · Frank Petriello🇺🇸

    We compute the $\mathcal{O}({\alpha }^2{\alpha }_s^2)$ perturbative corrections to inclusive jet production in electron-nucleon collisions. This process is of particular interest to the physics program of a future Electron Ion Collider (EIC). We include all relevant partonic processes, including deep-inelastic scattering contributions, photon-initiated corrections, and parton-parton scattering terms that first appear at this order. Upon integration over the final-state hadronic phase space we validate our results for the deep-inelastic corrections against the known next-to-next-to-leading order (NNLO) structure functions. Our calculation uses the $N$-jettiness subtraction scheme for performing higher-order computations, and allows for a completely differential description of the deep-inelastic scattering process. We describe the application of this method to inclusive jet production in detail, and present phenomenological results for the proposed EIC. The NNLO corrections have a non-trivial dependence on the jet kinematics and arise from an intricate interplay between all contributing partonic channels.

    hep-phnucl-thPLB(2016)·51 citations
13. 13*

    Heavy meson spectroscopy under strong magnetic field

    Tetsuya Yoshida🇯🇵 · Kei Suzuki🇰🇷

    Spectra of the neutral heavy mesons, ${\eta }_c(1S,2S)$, $J/\psi$, $\psi (2S)$, ${\eta }_b(1S,2S,3S)$, ${\rm Y}(1S,2S,3S)$, $D$, $D^{\ast }$, $B$, $B^{\ast }$, $B_s$ and $B_s^{\ast }$, in a homogeneous magnetic field are analyzed in a potential model of constituent quarks. To obtain anisotropic wave functions and the corresponding eigenvalues, the cylindrical Gaussian expansion method is applied, where the wave functions for transverse and longitudinal directions in the cylindrical coordinate are expanded by the Gaussian bases separately. Energy level structures in the wide range of magnetic fields are obtained and the deformation of the wave functions is shown, which reflects effects of the spin mixing, the Zeeman splitting and quark Landau levels. The contribution from the magnetic catalysis in heavy-light mesons is discussed as a change of the light constituent quark mass.

    hep-phhep-latnucl-thPRD(2016)·67 citations
14. 14*

    The $\rho$-meson longitudinal leading-twist distribution amplitude within QCD background field theory

    Hai-Bing Fu🇨🇳 · Xing-Gang Wu🇨🇳 · Wei Cheng🇨🇳 · Tao Zhong🇨🇳

    We revisit the $\rho$-meson longitudinal leading-twist distribution amplitude (DA) ${\varphi }_{2;\rho }^{\Vert }$ by using the QCD sum rules approach within the background field theory. To improve the accuracy of the sum rules for its moments $⟨{\xi }_{n;\rho }^{\Vert }⟩$, we include the next-to-leading order QCD correction to the perturbative part and keep all non-perturbative condensates up to dimension-six consistently within the background field theory. The first two moments read $⟨{\xi }_{2;\rho }^{\Vert }⟩{|}_{1\mathrm{GeV}}=0.241(28)$ and $⟨{\xi }_{4;\rho }^{\Vert }⟩{|}_{1\mathrm{GeV}}=0.109(10)$, indicating a double humped behavior for ${\varphi }_{2;\rho }^{\Vert }$ at small energy scale. As an application, we apply them to the $B\to \rho$ transition form factors within the QCD light-cone sum rules, which are key components for the decay width $\Gamma (B\to \rho \ell {\nu }_{\ell })$. To compare with the world-average of $\Gamma (B\to \rho \ell {\nu }_{\ell })$ issued by Particle Data Group, we predict $|V_{\mathrm{ub}}|=3.19_{-0.62}^{+0.65}$, which agrees with the BABAR and Omnès parameterization prediction within errors.

    hep-phPRD(2016)·21 citations
15. 15*

    An Extended Colored Zee-Babu Model

    Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

    We study the extended colored Zee-Babu model introducing a vector-like quark and singlet scalar. The active neutrino mass matrix and muon anomalous magnetic moment are analyzed, which can be fitted to experimental data satisfying the constraints from flavor changing neutral current. Then we discuss signature of our model via vector-like quark production. In addition, the diphoton excess can be explained with the contribution from vector-like quark

    hep-phPRD(2016)·28 citations
16. 16*

    Effective Theory for Electroweak Doublet Dark Matter

    Athanasios Dedes🇬🇷 · Dimitrios Karamitros🇬🇷 · Vassilis C. Spanos🇬🇷

    We perform a detailed study of an effective field theory which includes the Standard Model particle content extended by a pair of Weyl fermionic SU(2)-doublets with opposite hypercharges. A discrete symmetry guarantees that a linear combination of the doublet components is stable and can act as a candidate particle for Dark Matter. The dark sector fermions interact with the Higgs and gauge bosons through renormalizable $d=4$ operators, and non-renormalizable $d=5$ operators that appear after integrating out extra degrees of freedom above the TeV scale. We study collider, cosmological and astrophysical probes for this effective theory of Dark Matter. We find that a WIMP with a mass nearby to the electroweak scale, and thus observable at LHC, is consistent with collider and astrophysical data only when fairly large magnetic dipole moment transition operators with the gauge bosons exist, together with moderate Yukawa interactions.

    hep-phastro-ph.COPRD(2016)·14 citations
17. 17*

    Decuplets, glueballs and nonet anomalies

    Michal Majewski🇵🇱

    A new approach to problem of glueball search is presented. It refers to early J. Rosner's attempts to detect the tensor glueball. In the present description the glueball state is treated on equal footing with singlet $q\bar{q}$ one. Mixing glueball with $q\bar{q}$ nonet creates decuplet. Glueball can be detected as its component. Our approach is based on hypothesis of vanishing exotic commutators described as VEC model. The model describes all multiplets of light mesons. This makes possible to compare the mass patterns of different multiplets. According to VEC description some abnormal nonets can be interpreted as incomplete decuplets. This makes possible to relate the anomaly of the nonet to a glueball component of decuplet. The model reflects rich diversity of strong interaction properties. The treatment presented is quite elementary: only masses of physical states are required to be known.

    hep-phhep-ex0 citations
18. 18*

    Adaptive Integrand Decomposition

    Pierpaolo Mastrolia🇮🇹 · Tiziano Peraro🇬🇧 · Amedeo Primo🇮🇹 · William J. Torres Bobadilla🇮🇹

    We present a simplified variant of the integrand reduction algorithm for multiloop scattering amplitudes in $d=4-2ϵ$ dimensions, which exploits the decomposition of the integration momenta in parallel and orthogonal subspaces, $d=d_{\parallel }+d_{\perp }$, where $d_{\parallel }$ is the dimension of the space spanned by the legs of the diagrams. We discuss the advantages of a lighter polynomial division algorithm and how the orthogonality relations for Gegenbauer polynomilas can be suitably used for carrying out the integration of the irreducible monomials, which eliminates spurious integrals. Applications to one- and two-loop integrals, for arbitrary kinematics, are discussed.

    hep-phPoS(2016)·22 citations
19. 19*

    BFKL evolution and the growth with energy of exclusive J/Psi and Upsilon photo-production cross-sections

    I. Bautista🇲🇽 · A. Fernandez Tellez🇲🇽 · M. Hentschinski🇲🇽

    We investigate whether the Balitsky-Fadin-Kuraev-Lipatov (BFKL) low x evolution equation is capable to describe the energy dependence of the exclusive photo-production cross-section of vector mesons J/Psi and Upsilon on protons. Such cross-sections have been measured by both HERA experiments H1 and ZEUS in electron-proton collisions and by LHC experiments ALICE, CMS and LHCb in ultra-peripheral proton-proton and ultra-peripheral proton-lead collisions. Our approach provides a perturbative description of the rise with energy and relies only on a fit of the initial transverse momentum profile of the proton impact factor, which can be extracted from BFKL fits to inclusive HERA data. We find that BFKL evolution is capable to provide a very good description of the energy dependence of the current data set, while the available fits of the proton impact factor require an adjustment in the overall normalization.

    hep-phPRD(2016)·93 citations
20. 20*

    Spacetime Variation of Lorentz-Violation Coefficients at Nonrelativistic Scale

    Charles D. Lane🇺🇸

    When the Standard-Model Extension (SME) is applied in curved spacetime, the Lorentz-violation coefficients must depend on spacetime position. This work describes some of the consequences of this spacetime variation. We focus on effects that appear at a nonrelativistic scale and extract sensitivity of completed experiments to derivatives of SME coefficient fields.

    hep-ph1 citation
21. 21*

    Planar Zeros in Gauge Theories and Gravity

    Diego Medrano Jimenez🇪🇸 · Agustin Sabio Vera🇪🇸 · Miguel A. Vazquez-Mozo🇪🇸

    Planar zeros are studied in the context of the five-point scattering amplitude for gauge bosons and gravitons. In the case of gauge theories, it is found that planar zeros are determined by an algebraic curve in the projective plane spanned by the three stereographic coordinates labelling the direction of the outgoing momenta. This curve depends on the values of six independent color structures. Considering the gauge group SU(N) with N=2,3,5 and fixed color indices, the class of curves obtained gets broader by increasing the rank of the group. For the five-graviton scattering, on the other hand, we show that the amplitude vanishes whenever the process is planar, without imposing further kinematic conditions. A rationale for this result is provided using color-kinematics duality.

    ↳ hep-thhep-phJHEP(2016)·4 citations
22. 22*

    Inference of Unresolved Point Sources At High Galactic Latitudes Using Probabilistic Catalogs

    Tansu Daylan🇺🇸 · Stephen K. N. Portillo🇺🇸 · Douglas P. Finkbeiner🇺🇸

    Detection of point sources in images is a fundamental operation in astrophysics, and is crucial for constraining population models of the underlying point sources or characterizing the background emission. Standard techniques fall short in the crowded-field limit, losing sensitivity to faint sources and failing to track their covariance with close neighbors. We construct a Bayesian framework to perform inference of faint or overlapping point sources. The method involves probabilistic cataloging, where samples are taken from the posterior probability distribution of catalogs consistent with an observed photon count map. In order to validate our method we sample random catalogs of the gamma-ray sky in the direction of the North Galactic Pole (NGP) by binning the data in energy and Point Spread Function (PSF) classes. Using three energy bins spanning $0.3-1$, $1-3$ and $3-10$ GeV, we identify $270\begin{array}{c}+30\\ -10\end{array}$ point sources inside a $40^{\circ }\times 40^{\circ }$ region around the NGP above our point-source inclusion limit of $3\times 10^{-11}$/cm${}^2$/s/sr/GeV at the $1-3$ GeV energy bin. Modeling the flux distribution as a power law, we infer the slope to be $-1.92\begin{array}{c}+0.07\\ -0.05\end{array}$ and estimate the contribution of point sources to the total emission as $18\begin{array}{c}+2\\ -2\end{array}$\%. These uncertainties in the flux distribution are fully marginalized over the number as well as the spatial and spectral properties of the unresolved point sources. This marginalization allows a robust test of whether the apparently isotropic emission in an image is due to unresolved point sources or of truly diffuse origin.

    ↳ astro-ph.IMastro-ph.COastro-ph.GAastro-ph.HE+1ApJ(2017)·20 citations
23. 23*

    Electrified magnetic catalysis in three-dimensional topological insulators

    E. V. Gorbar🇺🇦 · V. A. Miransky🇨🇦 · I. A. Shovkovy🇺🇸 · P. O. Sukhachov🇨🇦

    The gap equations for the surface quasiparticle propagators in a slab of three-dimensional topological insulator in external electric and magnetic fields perpendicular to the slab surfaces are analyzed and solved. A different type of magnetic catalysis is revealed with the dynamical generation of both Haldane and Dirac gaps. Its characteristic feature manifests itself in the crucial role that the electric field plays in dynamical symmetry breaking and the generation of a Dirac gap in the slab. It is argued that, for a sufficiently large external electric field, the ground state of the system is a phase with a homogeneous surface charge density.

    ↳ cond-mat.mes-hallhep-phPRB(2016)·5 citations
24. 24*

    Frequency Shifts Induced by Field Gradients in Muon $g-2$ Experiments

    N. Nouri🇺🇸 · M.A. Brown🇺🇸 · R. Golub🇺🇸 · B. Plaster🇺🇸

    Two prominent efforts aimed at probing beyond Standard Model physics, searches for a neutron electric dipole moment (EDM) and measurements of the muon $g-2$ anomalous magnetic moment, employ spin precession techniques. In the most recent neutron EDM experiment, frequency shifts induced by magnetic field gradients and $\mathbf{E}\times \mathbf{v}$ motional fields were a significant source of systematic error. We consider the possibility of a similar effect in the most recent muon $g-2$ experiment, and find that such an effect could potentially be as large as $\sim 1$ ppm fractional error, to be compared with the reported $\sim 0.5$ ppm error.

    ↳ nucl-exhep-exhep-ph1 citation
25. 25*

    Test the chiral magnetic effect with isobaric collisions

    Wei-Tian Deng🇨🇳 · Xu-Guang Huang🇨🇳 · Guo-Liang Ma🇨🇳 · Gang Wang🇺🇸

    The quark-gluon matter produced in relativistic heavy-ion collisions may contain local domains in which P and CP symmetries are not preserved. When coupled with an external magnetic field, such P- and CP-odd domains will generate electric currents along the magnetic field --- a phenomenon called the chiral magnetic effect (CME). Recently, the STAR Collaboration at RHIC and the ALICE Collaboration at the LHC released data of charge-dependent azimuthal-angle correlators with features consistent with the CME expectation. However, the experimental observable is contaminated with significant background contributions from elliptic-flow-driven effects, which makes the interpretation of the data ambiguous. In this Letter, we show that the collisions of isobaric nuclei, ${}_{44}^{96}$Ru + ${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr + ${}_{40}^{96}$Zr, provide an ideal tool to disentangle the CME signal from the background effects. Our simulation demonstrates that the two collision types at $\sqrt{s_{\mathrm{NN}}}=200$ GeV have more than $10\%$ difference in the CME signal and less than $2\%$ difference in the elliptic-flow-driven backgrounds for the centrality range of $20-60\%$.

    ↳ nucl-thhep-phnucl-exPRC(2016)·121 citations
26. 26*

    Properties of strongly magnetized ultradense matter and their imprints on magnetar pulsations

    C. Vásquez Flores🇧🇷 · L. B. Castro🇧🇷 · G. Lugones🇧🇷

    We investigate the effect of strong magnetic fields on the adiabatic radial oscillations of hadronic stars. We describe magnetized hadronic matter within the framework of the relativistic nonlinear Walecka model and integrate the equations of relativistic radial oscillations to determine the fundamental pulsation mode. We consider that the magnetic field increases, in a density dependent way, from the surface, where it has a typical magnetar value of $10^{15}$ G, to the interior of the star where it can be as large as $3\times 10^{18}$ G. We show that magnetic fields of the order of $10^{18}$ G at the stellar core produce a significant change in the frequency of neutron star pulsations with respect to unmagnetized objects. If radial pulsations are excited in magnetar flares, they can leave an imprint in the flare lightcurves and open a new window for the study of highly magnetized ultradense matter.

    ↳ astro-ph.HEhep-phnucl-thPRC(2016)·7 citations
27. 27*

    Bulk viscosity for pion and nucleon thermal fluctuation in the hadron resonance gas model

    Sabyasachi Ghosh🇮🇳 · Sandeep Chatterjee🇮🇳 · Bedangdas Mohanty🇮🇳

    We have calculated microscopically bulk viscosity of hadronic matter, where equilibrium thermodynamics for all hadrons in medium are described by Hadron Resonance Gas (HRG) model. Considering pions and nucleons as abundant medium constituents, we have calculated their thermal widths, which inversely control the strength of bulk viscosities for respective components and represent their in-medium scattering probabilities with other mesonic and baryonic resonances, present in the medium. Our calculations show that bulk viscosity increases with both temperature and baryon chemical potential, whereas viscosity to entropy density ratio decreases with temperature and with baryon chemical potential, the ratio increases first and then decreases. The decreasing nature of the ratio with temperature is observed in most of the earlier investigations with few exceptions. We find that the temperature dependence of bulk viscosity crucially depends on the structure of the relaxation time. Along the chemical freeze-out line in nucleus-nucleus collisions with increasing collision energy, bulk viscosity as well as the bulk viscosity to entropy density ratio decreases, which also agrees with earlier references. Our results indicate the picture of a strongly coupled hadronic medium.

    ↳ nucl-thhep-phPRC(2016)·12 citations
28. 28*

    The Shear Viscosity in an Anisotropic Unitary Fermi Gas

    Rickmoy Samanta🇮🇳 · Rishi Sharma🇮🇳 · Sandip P. Trivedi🇮🇳

    We consider a system consisting of a strongly interacting, ultracold unitary Fermi gas under harmonic confinement. Our analysis suggests the possibility of experimentally studying, in this system, an anisotropic shear viscosity tensor driven by the anisotropy in the trapping potential. In particular, we suggest that this experimental setup could mimic some features of anisotropic geometries that have recently been studied for strongly coupled field theories which have a gravitational dual. Results using the AdS/CFT correspondence in these theories show that in systems with a background linear potential, certain viscosity components can be made much smaller than the entropy density, parametrically violating the bound proposed by Kovtun, Son and Starinets (KSS). This intuition, along with results from a Boltzmann analysis that we perform, suggests that a violation of the KSS bound can perhaps occur in the unitary Fermi gas system when it is subjected to a suitable anisotropic trapping potential which may be approximated to be linear in a suitable range of parameters. We give a concrete proposal for an experimental setup where an anisotropic shear viscosity tensor may arise. In such situations, it may also be possible to observe a reduction in the spin one component of the shear viscosity from its lowest value observed so far in ultracold Fermi gases. In extreme anisotropic situations, the reduction may be enough to reduce the shear viscosity to entropy ratio below the proposed KSS bound, although this regime is difficult to analyze in a theoretically controlled manner.

    ↳ cond-mat.quant-gashep-phhep-thPRA(2017)·17 citations
29. 29*

    Phases of kinky holographic nuclear matter

    Matthew Elliot-Ripley🇬🇧 · Paul Sutcliffe🇬🇧 · Marija Zamaklar🇬🇧

    Holographic QCD at finite baryon number density and zero temperature is studied within the five-dimensional Sakai-Sugimoto model. We introduce a new approximation that models a smeared crystal of solitonic baryons by assuming spatial homogeneity to obtain an effective kink theory in the holographic direction. The kink theory correctly reproduces a first order phase transition to lightly bound nuclear matter. As the density is further increased the kink splits into a pair of half-kink constituents, providing a concrete realization of the previously suggested dyonic salt phase, where the bulk soliton splits into constituents at high density. The kink model also captures the phenomenon of baryonic popcorn, in which a first order phase transition generates an additional soliton layer in the holographic direction. We find that this popcorn transition takes place at a density below the dyonic salt phase, making the latter energetically unfavourable. However, the kink model predicts only one pop, rather than the sequence of pops suggested by previous approximations. In the kink model the two layers produced by the single pop form the surface of a soliton bag that increases in size as the baryon chemical potential is increased. The interior of the bag is filled with abelian electric potential and the instanton charge density is localized on the surface of the bag. The soliton bag may provide a holographic description of a quarkyonic phase.

    ↳ hep-thhep-phnucl-thJHEP(2016)·35 citations
30. 30*

    Magnetic fields and chiral asymmetry in the early hot universe

    Maksym Sydorenko🇺🇦 · Oleksandr Tomalak🇩🇪 · Yuri Shtanov🇺🇦

    In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of `inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.

    ↳ astro-ph.COgr-qchep-phJCAP(2016)·11 citations
31. 31*

    Search for the effect of massive bodies on atomic spectra and constraints on Yukawa-type interactions of scalar particles

    N. Leefer🇩🇪 · A. Gerhardus🇩🇪 · D. Budker🇩🇪 · V. V. Flambaum🇦🇺 · Y. V. Stadnik🇦🇺

    We propose a new method to search for hypothetical scalar particles that have feeble interactions with Standard-Model particles. In the presence of massive bodies, these interactions produce a non-zero Yukawa-type scalar-field magnitude. Using radio-frequency spectroscopy data of atomic dysprosium, as well as atomic clock spectroscopy data, we constrain the Yukawa-type interactions of a scalar field with the photon, electron, and nucleons for a range of scalar-particle masses corresponding to length scales $>10$ cm. In the limit as the scalar-particle mass $m_{\varphi }\to 0$, our derived limits on the Yukawa-type interaction parameters are: ${\Lambda }_{\gamma }\gtrsim 8\times 10^{19}$ GeV, ${\Lambda }_e\gtrsim 1.3\times 10^{19}$ GeV, and ${\Lambda }_N\gtrsim 6\times 10^{20}$ GeV. Our measurements also constrain combinations of interaction parameters, which cannot otherwise be probed with traditional anomalous-force measurements. We suggest further measurements to improve on the current level of sensitivity.

    ↳ physics.atom-phhep-exhep-phPRL(2016)·51 citations
32. 32*

    Jet reconstruction at high-energy lepton colliders

    M. Boronat🇪🇸 · J. Fuster🇪🇸 · I. Garcia🇪🇸 · Ph. Roloff🇨🇭 · R. Simoniello🇨🇭 · M. Vos🇪🇸

    In this paper we study the performance in $e^{+}{e}^{-}$ collisions of classical $e^{+}{e}^{-}$ jet reconstruction algorithms, longitudinally invariant algorithms and the recently-proposed Valencia algorithm. The study includes a comparison of perturbative and non-perturbative jet energy corrections and the response under realistic background conditions. Several algorithms are benchmarked with a detailed detector simulation at $\sqrt{s}=3$~\tev. We find that the classical $e^{+}{e}^{-}$ algorithms, with or without beam jets, have the best response, but are inadequate in environments with non-negligible background. The Valencia algorithm and longitudinally invariant $k_t$ algorithms have a much more robust performance, with a slight advantage for the former.

    ↳ hep-exhep-phEPJC(2018)·97 citations
33. 33*

    Determination of the muonic branching ratio of the W boson and its total width via cross-section measurements at the Tevatron and LHC

    Stefano Camarda🇨🇭 · Jakub Cuth🇩🇪 · Matthias Schott🇩🇪

    The total $W$-boson decay width ${\Gamma }_W$ is an important observable which allows testing of the standard model. The current world average value is based on direct measurements of final state kinematic properties of $W$-boson decays, and has a relative uncertainty of 2%. The indirect determination of ${\Gamma }_W$ via the cross-section measurements of vector-boson production can lead to a similar accuracy. The same methodology leads also to a determination of the leptonic branching ratio. This approach has been successfully pursued by the CDF and D0 experiments at the Tevatron collider, as well as by the CMS collaboration at the LHC. In this paper we present for the first time a combination of the available measurements at hadron colliders, accounting for the correlations of the associated systematic uncertainties. Our combination leads to values of $\text{BR}(W\to \mu \nu )=(10.72\pm 0.16)\%$ and ${\Gamma }_W=2113\pm 31$ MeV, respectively, both compatible with the current world averages.

    ↳ hep-exhep-phEPJC(2016)·9 citations
34. 34*

    Double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions

    Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱

    We present first measurable predictions for electromagnetic (two-photon) double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions at LHC. Measureable cross sections are obtained with realistic cuts on electron/positron (pseudo)rapidities and transverse momenta for the ALICE and ATLAS or CMS experiments. The predictions for total and differential cross sections are presented. We show also two-dimensional distributions in rapidities of the opposite-sign (from the same or different subcollisions) and of the same-sign ($e^{+}{e}^{+}$ or $e^{-}{e}^{-}$) electrons and in rapidity distance between them. Expected number of events are presented and discussed. Our calculations strongly suggest that relevant measurements with the help of ATLAS, CMS and ALICE detectors are possible in a near future.

    ↳ nucl-thhep-exhep-phPLB(2016)·19 citations
35. 35*

    Universal MOND relation between the baryonic and `dynamical' central surface densities of disc galaxies

    Mordehai Milgrom🇮🇱

    I derive a new MOND relation for pure-disc galaxies: The `dynamical' central surface density, ${\Sigma }_D^0$, deduced from the measured velocities, is a universal function of only the true, `baryonic' central surface density, ${\Sigma }_B^0$: ${\Sigma }_D^0={\Sigma }_M\mathcal{S}({\Sigma }_B^0/{\Sigma }_M)$, where ${\Sigma }_M\equiv a_0/2\pi G$ is the MOND surface density constant. This surprising result is shown to hold in both existing, nonrelativistic MOND theories. $\mathcal{S}(y)$ is derived: $\mathcal{S}(y)={\int }_0^y\nu (y^{\prime })d{y}^{\prime }$, with $\nu (y)$ the interpolating function of the theory. The relation aymptotes to ${\Sigma }_D^0={\Sigma }_B^0$ for ${\Sigma }_B^0\gg {\Sigma }_M$, and to ${\Sigma }_D^0=(4{\Sigma }_M{\Sigma }_B^0{)}^{1/2}$ for ${\Sigma }_B^0\ll {\Sigma }_M$. This study was prompted by the recent finding of a correlation between related attributes of disc galaxies by Lelli et al. (2016). The MOND central-surface-densities relation agrees very well with these results.

    ↳ astro-ph.GAastro-ph.COgr-qchep-phPRL(2016)·53 citations
36. 36*

    Fundamental fields around compact objects: Massive spin-2 fields, Superradiant instabilities and Stars with dark matter cores

    Richard Brito🇵🇹

    Fundamental bosonic fields of arbitrary spin are predicted by generic extensions of the Standard Model and of General Relativity, and are well-motivated candidates to explain the dark components of the Universe. One of most promising channels to look for their presence is through their gravitational interaction with compact objects. Within this context, in this thesis I study several mechanisms by which bosonic fields may affect the dynamics and structure of black holes and neutron stars. The first part of the thesis is devoted to the study of massive spin-2 fields around spherically symmetric black-hole spacetimes. Massive spin-2 fields can be consistently described within theories of massive gravity, making it possible to perform a systematic study of the propagation of these fields in curved spacetimes. In particular, I show that due to the presence of additional degrees of freedom in these theories, the structure of black-hole solutions is richer than in General Relativity. In the second part of the thesis, I discuss in detail superradiant instabilities in the context of black-hole physics. I show that several mechanisms, such as massive bosonic fields and magnetic fields, can turn spinning black holes unstable against superradiant modes, which has important implications for astrophysics and for physics beyond the Standard Model. In the last part of this thesis, I present a study of how bosonic dark matter condensates interact gravitationally with compact stars. In particular, I show that stable stellar configurations formed by a perfect fluid and a bosonic condensate exist and can describe the late stages of dark matter accretion onto stars, in dark matter rich environments.

    ↳ gr-qcastro-ph.COastro-ph.SRhep-ph+19 citations
37. 37*

    Lattice Prediction for Deeply Bound Doubly Heavy Tetraquarks

    Anthony Francis🇨🇦 · Renwick J. Hudspith🇨🇦 · Randy Lewis🇨🇦 · Kim Maltman🇦🇺

    We investigate the possibility of $q{q}^{\prime }\bar{b}\bar{b}$ tetraquark bound states using $n_f=2+1$ lattice QCD ensembles with pion masses $\simeq 164$, $299$, and $415$ MeV. Motivated by observations from heavy baryon phenomenology, we consider two lattice interpolating operators both of which are expected to couple efficiently to tetraquark states: one with diquark-antidiquark and one with a meson-meson structure. Using nonrelativistic QCD to simulate the bottom quarks, we study the $ud\bar{b}\bar{b}$, $\ell s\bar{b}\bar{b}$ channels with $\ell =u,d$, and find unambiguous signals for strong-interaction-stable $J^P=1^{+}$ tetraquarks. These states are found to lie $189(10)$ and $98(7)$ MeV below the corresponding free two-meson thresholds.

    ↳ hep-lathep-exhep-phnucl-thPRL(2017)·244 citations
38. 38*

    Strong-coupling scale and frame-dependence of the initial conditions for chaotic inflation in models with modified (coupling to) gravity

    Dmitry Gorbunov🇷🇺 · Alexander Panin🇷🇺

    A classical evolution in chaotic inflationary models starts at high energy densities with semi-classical initial conditions presumably consistent with universal quantum nature of all the fundamental forces. That is each quantum contributes the same amount to the energy density. We point out the upper limit on this amount inherent in this approach, so that all the quanta are inside the weak-coupling domain. We discuss this issue in realistic models with modified gravity, $R^2$- and Higgs-inflations, emphasizing the specific change of the initial conditions with metric frame, while all the quanta still contribute equal parts. The analysis can be performed straightforwardly in any model with modified gravity ($F(R)$-gravity, scalars with non-minimal couplings to gravity, etc).

    ↳ gr-qcastro-ph.COhep-ph1 citation
39. 39*

    Test of non-Newtonian gravitational force at micrometer range

    Pengshun Luo🇨🇳 · Jianbo Wang🇨🇳 · Shengguo Guan🇨🇳 · Wenjie Wu🇨🇳 · Zhaoyang Tian🇨🇳 · Shanqing Yang🇨🇳 · Chenggang Shao🇨🇳 · Jun Luo🇨🇳

    We report an experimental test of non-Newtonian gravitational forces at mi- crometer range. To experimentally subtract off the Casimir force and the electrostatic force background, differential force measurements were performed by sensing the lateral force between a gold sphere and a density modulated source mass using a soft cantilever. The current sensitivity is limited by the patch electrostatic force, which is further improved by two dimensional (2D) force mapping. The preliminary result sets a model independent constraint on the Yukawa type force at this range.

    ↳ gr-qchep-ph1 citation

* 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.