Mon·Dec 26, 2016Monday·December 26, 2016

1. 01*

   Scalar contributions to $b\to c(u)\tau \nu$ transitions

   Alejandro Celis🇩🇪 · Martin Jung🇩🇪 · Xin-Qiang Li🇨🇳 · Antonio Pich🇪🇸

   We perform a comprehensive analysis of scalar contributions in $b\to c\tau \nu$ transitions including the latest measurements of $R(D^{(\ast )})$, the $q^2$ differential distributions in $B\to D^{(\ast )}\tau \nu$, the $\tau$ polarization asymmetry for $B\to D^{\ast }\tau \nu$, and the bound derived from the total width of the $B_c$ meson. We find that scalar contributions with the simultaneous presence of both left- and right-handed couplings to quarks can explain the available data, specifically $R(D^{(\ast )})$ together with the measured differential distributions. However, the constraints from the total $B_c$ width present a slight tension with the current data on $B\to D^{\ast }\tau \nu$ in this scenario, preferring smaller values for $R(D^{\ast })$. We discuss possibilities to disentangle scalar new physics from other new-physics scenarios like the presence of only a left-handed vector current, via additional observables in $B\to D^{(\ast )}\tau \nu$ decays or additional decay modes like the baryonic ${\Lambda }_b\to {\Lambda }_c\tau \nu$ and the inclusive $B\to X_c\tau \nu$ decays. We also analyze scalar contributions in $b\to u\tau \nu$ transitions, including the latest measurements of $B\to \tau \nu$, providing predictions for ${\Lambda }_b\to p\tau \nu$ and $B\to \pi \tau \nu$ decays. The potential complementarity between the $b\to u$ and $b\to c$ sectors is finally investigated once assumptions about the flavour structure of the underlying theory are made.

   hep-phhep-exPLB(2017)·175 citations
2. 02*

   Helicity Evolution at Small x: Summary of Recent Developments

   Yuri V. Kovchegov🇺🇸 · Daniel Pitonyak🇺🇸 · Matthew D. Sievert🇺🇸

   We construct small-$x$ evolution equations which can be used to calculate quark and anti-quark helicity TMDs and PDFs, along with the $g_1$ structure function. These evolution equations resum powers of ${\alpha }_s{\ln }^2(1/x)$ in the polarization-dependent evolution along with the powers of ${\alpha }_s\ln (1/x)$ in the unpolarized evolution which includes saturation effects. The equations are written in an operator form in terms of polarization-dependent Wilson line-like operators. While the equations do not close in general, they become closed and self-contained systems of non-linear equations in the large-$N_c$ and large-$N_c\&N_f$ limits. We construct a numerical solution of the helicity evolution equations in the large-$N_c$ limit. Employing the extracted intercept, we are able to predict directly from theory the behavior of the quark helicity PDFs at small $x$, which should have important phenomenological consequences. We also give an estimate of how much of the proton's spin may be at small $x$ and what impact this has on the so-called "spin crisis." Based on JHEP 1601 (2016) 072 (arXiv:1511.06737), arXiv:1610.06197 and arXiv:1610.06188.

   hep-phnucl-th0 citations
3. 03*

   Joint short- and long-baseline constraints on light sterile neutrinos

   Francesco Capozzi🇮🇹 · Carlo Giunti🇮🇹 · Marco Laveder🇮🇹 · Antonio Palazzo🇮🇹

   Recent studies have evidenced that long-baseline (LBL) experiments are sensitive to the extra CP-phases involved with light sterile neutrinos, whose existence is suggested by several anomalous short-baseline (SBL) results. We show that, within the 3+1 scheme, the combination of the existing SBL data with the LBL results coming from the two currently running experiments NO$\nu$A and T2K, enables us to simultaneously constrain two active-sterile mixing angles ${\theta }_{14}$ and ${\theta }_{24}$ and two CP-phases ${\delta }_{13}\equiv \delta$ and ${\delta }_{14}$, albeit the information on the second CP-phase is still weak at the moment. The two mixing angles are basically determined by the SBL data, while the two CP-phases are constrained by the LBL experiments, once the information coming from the SBL setups is taken into account. We also assess the robustness/fragility of the estimates of the standard 3-flavor parameters in the more general 3+1 scheme. To this regard we find that: i) the indication of CP-violation found in the 3-flavor analyses persists also in the 3+1 scheme, with ${\delta }_{13}\equiv \delta$ having still its best fit value around $-\pi /2$; ii) the 3-flavor weak hint in favor of the normal hierarchy becomes even less significant when sterile neutrinos come into play; iii) the weak indication of non-maximal ${\theta }_{23}$ (driven by NO$\nu$A disappearance data) persists in the 3+1 scheme, where maximal mixing is disfavored at almost the 90\% C.L. in both normal and inverted mass hierarchy; iv) the preference in favor of one of the two octants of ${\theta }_{23}$ found in the 3-flavor framework (higher octant for inverted mass hierarchy) is completely washed out in the 3+1 scheme.

   hep-phhep-exphysics.ins-detPRD(2017)·36 citations
4. 04*

   Lowest lying even-parity ${\bar{B}}_s$ mesons: heavy quark spin-flavor symmetry, chiral dynamics, and constituent quark model bare masses

   Miguel Albaladejo🇪🇸 · Pedro Fernandez-Soler🇪🇸 · Juan Nieves🇪🇸 · Pablo G. Ortega🇪🇸

   The discovery of the $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between $Q\bar{q}$ and $(Q\bar{q})(q\bar{q})$ Fock components. In contrast to the $c\bar{s}$ sector, there is no experimental evidence of $J^P=0^{+},1^{+}$ bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark model P-wave ${\bar{B}}_s$ scalar and axial mesons and the ${\bar{B}}^{(\ast )}K$ channels is incorporated employing an effective interaction, consistent with heavy quark spin symmetry, constrained by the lattice energy levels.

   hep-phEPJC(2017)·20 citations
5. 05*

   Anarchy with Hierarchy: A Probabilistic Appraisal

   K.S. Babu🇺🇸 · Alexander Khanov🇺🇸 · Shaikh Saad🇺🇸

   The masses of the charged fermion and the mixing angles among quarks are observed to be strongly hierarchical, while analogous parameters in the neutrino sector appear to be structure-less or anarchical. We develop a class of unified models based on SU(5) symmetry that explains these differing features probabilistically. With the aid of three input parameters that are hierarchical, and with the assumption that all the Yukawa couplings are uncorrelated random variables described by Gaussian distributions, we show by Monte Carlo simulations that the observed features of the entire fermion spectrum can be nicely reproduced. We extend our analysis to an SU(5)-based flavor U(1) model making use of the Froggatt-Nielsen mechanism where the order one Yukawa couplings are modeled as random variables, which also shows good agreement with observations.

   hep-phPRD(2017)·15 citations
6. 06*

   Purely flavor-changing Z' bosons and where they might hide

   Patrick Foldenauer🇩🇪 · Joerg Jaeckel🇩🇪

   A plethora of ultraviolet completions of the Standard Model have extra U(1) gauge symmetries. In general, the associated massive $Z^{\prime }$ gauge boson can mediate flavor-changing neutral current processes at tree level. We consider a situation where the $Z^{\prime }$ boson couples solely via flavor-changing interactions to quarks and leptons. In this scenario the model parameter space is, in general, quite well constrained by existing flavor bounds. However, we argue that cancellation effects shelter islands in parameter space from strong flavor constraints and that these can be probed by multipurpose collider experiments like ATLAS or CMS as well as LHCb in upcoming runs at the LHC. In still allowed regions of parameter space these scenarios may help to explain the current tension between theory and experiment of $(g-2{)}_{\mu }$ as well as a small anomaly in $\tau$ decays.

   hep-phJHEP(2017)·18 citations
7. 07*

   Exploring correlations in the CGC wave function: odd azimuthal anisotropy

   Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱 · Vladimir Skokov🇺🇸

   We extend the CGC approach to calculation of the double inclusive gluon production by including high-density effect in the CGC wave function of the projectile (proton). Our main result is that these effects lead to the appearance of odd harmonics in the two-particle correlation C(k,p). We find that in the high momentum limit, |k|,|p|>>Q_s, this results in a positive c_1{2}. Additionally when the magnitudes of the two momenta are approximately equal, |k|/|p| ~ 1, the density effects also generate a positive third harmonic c_3{2}, which translates into a non-vanishing v_3 when the momenta of the trigger and associated particle are in the same momentum bin. The sign of c_3{2} becomes negative when |k|/|p|>1.1 suggesting an interesting experimental signature.

   hep-phnucl-thPRD(2017)·44 citations
8. 08*

   Beyond the Standard Model with leptogenesis and neutrino data

   Pasquale Di Bari🇬🇧

   In this short review I discuss how high energy (type I) seesaw models can be nicely embedded within grand-unified models and reproduce the observed matter-antimatter asymmetry with leptogenesis. In particular, after discussing general features and results in leptogenesis, I focus on $SO(10)$-inspired leptogenesis and on a particular solution, the strong thermal $SO(10)$-inspired solution, that provides an interesting way to understand neutrino mixing parameters: the non-vanishing reactor mixing angle, the emerging negative sign of $\sin \delta$ and the slight hints favouring normally ordered neutrino masses and an atmospheric mixing angle in the first octant. I also briefly discuss leptogenesis within two right-handed seesaw neutrino models. In this case a a third decoupled right-handed neutrino can provide a candidate for very heavy cold decaying dark matter produced from right-handed neutrino mixing with a mass in the TeV-EeV range and its decays would give a contribution to the IceCube high energy neutrino events in addition to an astrophysical component.

   hep-ph0 citations
9. 09*

   Prospects for Distinguishing Dark Matter Models Using Annual Modulation

   Samuel J. Witte🇺🇸 · Vera Gluscevic🇺🇸 · Samuel D. McDermott🇺🇸

   It has recently been demonstrated that, in the event of a putative signal in dark matter direct detection experiments, properly identifying the underlying dark matter-nuclei interaction promises to be a challenging task. Given the most optimistic expectations for the number counts of recoil events in the forthcoming Generation 2 experiments, differentiating between interactions that produce distinct features in the recoil energy spectra will only be possible if a strong signal is observed simultaneously on a variety of complementary targets. However, there is a wide range of viable theories that give rise to virtually identical energy spectra, and may only differ by the dependence of the recoil rate on the dark matter velocity. In this work, we investigate how degeneracy between such competing models may be broken by analyzing the time dependence of nuclear recoils, i.e. the annual modulation of the rate. For this purpose, we simulate dark matter events for a variety of interactions and experiments, and perform a Bayesian model-selection analysis on all simulated data sets, evaluating the chance of correctly identifying the input model for a given experimental setup. We find that including information on the annual modulation of the rate may significantly enhance the ability of a single target to distinguish dark matter models with nearly degenerate recoil spectra, but only with exposures beyond the expectations of Generation 2 experiments.

   hep-phastro-ph.COJCAP(2017)·14 citations
10. 10*

    Effective field theories for heavy Majorana neutrinos in a thermal bath

    Simone Biondini🇩🇪

    Heavy Majorana neutrinos enter in many scenarios of physics beyond the Standard Model and play a special role in the leptogenesis framework as origin of the baryon asymmetry in the universe. In this thesis, we develop an effective field theory for non-relativistic Majorana particles. We apply the effective field theory so obtained to address calculations in a hot medium which models the early stages of the universe evolution. In particular, we apply it to the case of a heavy Majorana neutrino decaying in a hot plasma of Standard Model particles, whose temperature is much smaller than the mass of the Majorana neutrino but still much larger than the electroweak scale, and the derivation of the neutrino thermal width is revisited in an EFT fashion. Assuming the same hierarchy between heavy neutrino masses and the temperature, we compute systematically thermal corrections to the direct and indirect CP asymmetries in the Majorana neutrino decays. These are key ingredients entering the equations that describe the thermodynamic evolution of the induced lepton-number asymmetry eventually leading to the baryon asymmetry in the universe. We consider the case of two Majorana neutrinos with nearly degenerate masses, that allows for a resonant enhancement of the CP asymmetry, and a hierarchical spectrum with one heavy neutrino much lighter than the other neutrino species. Flavour effects are also taken into account in the derivation of the CP asymmetries at finite temperature.

    hep-ph1 citation
11. 11*

    Lepton Number Violation in Low Scale Seesaw Mechanism and its Collider Complementarity

    Prativa Pritimita🇮🇳 · Nitali Dash🇮🇳 · Sudhanwa Patra🇮🇳

    We consider the TeV scale left-right symmetric theory which can accommodate low scale seesaw mechanisms consistent with neutrino oscillation data and find new physics contributions to neutrinoless double beta decay. The model facilitates natural type-II seesaw dominance and the presence of extra particles make the Dirac neutrino mass matrix $M_D$ large that leads to large light heavy neutrino mixing. The spontaneous symmetry breaking through doublets, triplets and bidoublet scalars at TeV scale offers rich phenomenology accessible to LHC. From the numerical studies of the new physics contributions to neutrinoless double beta decay we derive a lower limit on absolute scale of lightest neutrino mass and find that normal hierarchy (NH) pattern is favorable taking into account the cosmology and oscillation data.

    hep-phPoS(2016)·0 citations
12. 12*

    Polarization-operator approach to optical signatures of axion-like particles in strong laser pulses

    Selym Villalba-Chávez🇩🇪 · Tobias Podszus🇩🇪 · Carsten Müller🇩🇪

    Hypothetical oscillations of probe photons into axion-like particles might be revealed by exploiting the strong fields of high-intensity laser pulses. Considering an arbitrary plane-wave background, we determine the polarization tensor induced by the quantum fluctuations of the axion field and use it to calculate how the polarimetric properties of an initially linear-polarized probe beam are modified. We find that various experimental setups based on contemporary facilities and instrumentation might lead to new exclusion bounds on the parameter space of these particle candidates. The impact of the pulse shape on the discovery potential is studied via a comparison between the cases in which the wave is modulated by a Gaussian envelope and a ${\sin }^2$ profile. This analysis shows that the upper limits resulting from the ellipticity are relatively insensitive to this change, whereas those arising from the rotation of the polarization plane turn out to be more dependent on the field shape.

    hep-phPLB(2017)·21 citations
13. 13*

    $\psi (2S)$ enhancement in p-Pb collision as an indication of QGP formation at the LHC

    S. Ganesh🇮🇳 · Captain R. Singh🇮🇳 · M. Mishra🇮🇳

    Proton-nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus-nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and RHIC energies for the past several years, as it was thought that Quark-Gluon Plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton-lead (p$-$Pb) collisions. In this work, we have derived an expression for gluon induced excitation of $J/\psi$ to $\psi (2S)$, using pNRQCD, and show that the relative enhancement of $\psi (2S)$ vis a vis $J/\psi$, especially at high $p_T$, gives further indication that the QGP is indeed formed in p$-$Pb collisions at the most central collisions at LHC energy. $J/\psi$ and $\psi (2S)$ suppression effects seen at ALICE are also qualitatively explained.

    hep-phJ.Phys.G(2018)·5 citations
14. 14*

    Strange resonance poles from $K\pi$ scattering below 1.8 GeV

    J.R. Peláez🇪🇸 · A. Rodas🇪🇸 · J. Ruiz de Elvira🇩🇪

    In this work we present a determination of the mass, width and coupling of the resonances that appear in kaon-pion scattering below 1.8 GeV. These are: the much debated scalar $\kappa$-meson, nowdays known as $K_0^{\ast }(800)$, the scalar $K_0^{\ast }(1430)$, the $K^{\ast }(892)$ and $K_1^{\ast }(1410)$ vectors, the spin-two $K_2^{\ast }(1430)$ as well as the spin-three $K_3^{\ast }(1780)$. The parameters will be determined from the pole associated to each resonance by means of an analytic continuation of the $K\pi$ scattering amplitudes obtained in a recent and precise data analysis constrained with dispersion relations, which were not well satisfied in previous analyses. This analytic continuation will be performed by means of Padé approximants, thus avoiding a particular model for the pole parameterization. We also pay particular attention to the evaluation of uncertainties.

    hep-phEPJC(2017)·61 citations
15. 15*

    Direct CP violation in $K\to \pi \pi$ decays and supersymmetry

    Teppei Kitahara🇩🇪 · Ulrich Nierste🇩🇪 · Paul Tremper🇩🇪

    The quantities ${ϵ}_K^{\prime }$ and ${ϵ}_K$ measure the amount of direct and indirect CP violation in $K\to \pi \pi$ decays, respectively. Using the recent lattice results from the RBC and UKQCD Collaborations and a new compact implementation of the $\Delta S=1$ renormalization group evolution we predict $\text{mbox}Re\frac{{ϵ}_K^{\prime }}{{ϵ}_K}=\left(1.06\pm 5.07\right)\times 10^{-4}$ in the Standard Model. This value is $2.8\sigma$ below the experimental value of $\text{mbox}Re\frac{{ϵ}_K^{\prime }}{{ϵ}_K}=\left(16.6\pm 2.3\right)\times 10^{-4}.$ In generic models of new physics the well-understood ${ϵ}_K$ precludes large contributions to ${ϵ}_K^{\prime }$, if the new contributions enter at loop level. However, one can resolve the tension in ${ϵ}_K^{\prime }/{ϵ}_K$ within the Minimal Supersymmetric Standard Model. To this end two features of supersymmetry are crucial: First, one can have large isospin-breaking contributions (involving the strong instead of the weak interaction) which enhance ${ϵ}_K^{\prime }$. Second, the Majorana nature of gluinos permits a suppression of the MSSM contribution to ${ϵ}_K$, because two box diagrams interfere destructively.

    hep-phPoS(2016)·0 citations
16. 16*

    Renormalization Group Running of Fermion Observables in an Extended Non-Supersymmetric SO(10) Model

    Davide Meloni🇮🇹 · Tommy Ohlsson🇸🇪 · Stella Riad🇸🇪

    We investigate the renormalization group evolution of fermion masses, mixings and quartic scalar Higgs self-couplings in an $extended$ non-supersymmetric SO(10) model, where the Higgs sector contains the ${10}_{\mathrm{H}}$, ${120}_{\mathrm{H}}$, and ${126}_{\mathrm{H}}$ representations. The group SO(10) is spontaneously broken at the GUT scale to the Pati-Salam group and subsequently to the Standard Model (SM) at an intermediate scale $M_{\mathrm{I}}$. We explicitly take into account the effects of the change of gauge groups in the evolution. In particular, we derive the renormalization group equations for the different Yukawa couplings. We find that the computed physical fermion observables can be successfully matched to the experimental measured values at the electroweak scale. Using the same Yukawa couplings at the GUT scale, the measured values of the fermion observables cannot be reproduced with a SM-like evolution, leading to differences in the numerical values up to around 80 %. Furthermore, a similar evolution can be performed for a $minimal$ SO(10) model, where the Higgs sector consists of the ${10}_{\mathrm{H}}$ and ${126}_{\mathrm{H}}$ representations only, showing an equally good potential to describe the low-energy fermion observables. Finally, for both the extended and the minimal SO(10) models, we present predictions for the three Dirac and Majorana CP-violating phases as well as three effective neutrino mass parameters.

    hep-phJHEP(2017)·41 citations
17. 17*

    Aspects of hard QCD processes in proton-nucleus collisions

    François Arleo🇫🇷

    Hard processes in high-energy proton-nucleus collisions are a powerful tool in order to investigate several importants aspects of QCD in a nuclear medium, such as nuclear shadowing, parton multiple scattering or medium-induced gluon radiation. I review in these proceedings recent progress in that field.

    hep-phhep-exNucl.Part.Phys.Proc.(2017)·3 citations
18. 18*

    Photoproduction of the $B_c^{(\ast )}$ Meson at the LHeC

    Bi Huan-Yu🇨🇳 · Zhang Ren-You🇨🇳 · Hua-Yong Han🇨🇳 · Jiang Yi🇨🇳 · Xing-Gang Wu🇨🇳

    We make a detailed study on the photoproduction mechanism of the doubly heavy flavored $B_c^{(\ast )}$ meson at the purposed Large Hadron Electron Collider (LHeC) within the framework of nonrelativistic QCD. In addition to the photoproduction mechanism via the gluon-induced channel $\gamma +g\to B_c^{(\ast )}+b+\bar{c}$, the extrinsic heavy quark mechanism via the two channels $\gamma +c\to B_c^{(\ast )}+b$ and $\gamma +\bar{b}\to B_c^{(\ast )}+\bar{c}$ has also been studied. Those two extrinsic channels are generally suppressed by the heavy quark distribution functions in proton, which however provide significant contributions in low and intermediate $p_T$ region. A detailed comparison of those channels together with the theoretical uncertainties has been presented. By summing up all the mentioned photoproduction channels, we observe that about $(1.04_{-0.53}^{+0.90})\times 10^5$ $B_c$ and $(4.86_{-2.30}^{+3.72})\times 10^5$ $B_c^{\ast }$ events can be generated at the LHeC in one operation year with the proton-electron collision energy $\sqrt{S}=1.30$ TeV and the luminosity $\mathcal{L}\simeq 10^{33}$ ${\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$. Here the errors are for $m_c=1.50\pm 0.20$ GeV and $m_b=4.9\pm 0.40$ GeV. Thus, in addition to the hadronic experiments, the LHeC shall provide another helpful platform for studying the $B_c^{(\ast )}$ meson properties, especially to test the extrinsic heavy quark mechanism.

    hep-phPRD(2017)·15 citations
19. 19*

    Paving the Way Towards Precision Physics in Saturation Studies Through Exclusive Diffractive Light Neutral Vector Meson Production

    R. Boussarie🇵🇱 · A. V. Grabovsky🇷🇺 · D. Yu. Ivanov🇷🇺 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷

    We perform the first next-to-leading order computation of the ${\gamma }^{(\ast )}\to V$ ($\rho ,\varphi ,\omega$) impact factor in the QCD shockwave approach and in the most general kinematics. This paves the way to the very first quantitative study of high-energy nucleon and nucleus saturation beyond the leading order, in various processes to be measured in $ep$, $eA$, $pp$ and $pA$ collisions at existing and future colliders.

    hep-phPRL(2017)·100 citations
20. 20*

    The Axiflavon

    Lorenzo Calibbi🇨🇳 · Florian Goertz🇨🇭 · Diego Redigolo🇮🇱 · Robert Ziegler🇩🇪 · Jure Zupan🇺🇸

    We show that solving the flavor problem of the Standard Model with a simple $U(1{)}_H$ flavor symmetry naturally leads to an axion that solves the strong CP problem and constitutes a viable Dark Matter candidate. In this framework, the ratio of the axion mass and its coupling to photons is related to the SM fermion masses and predicted within a small range, as a direct result of the observed hierarchies in quark and charged lepton masses. The same hierarchies determine the axion couplings to fermions, making the framework very predictive and experimentally testable by future axion and precision flavor experiments.

    hep-phPRD(2017)·301 citations
21. 21*

    Open Effective Field Theories from Highly Inelastic Reactions

    Eric Braaten🇺🇸 · Hans-Werner Hammer🇩🇪 · G. Peter Lepage🇺🇸

    The loss of particles due to highly inelastic reactions has previously been taken into account in effective field theories for low-energy particles by adding local anti-Hermitian terms to the effective Hamiltonian. An additional modification is required in the time evolution equation for the density matrix of a multi-particle system. An effective density matrix can be defined by tracing over states containing high-momentum particles produced by the highly inelastic reactions and by a time average that eliminates short-time correlations. The effective density matrix satisfies the Lindblad equation, with local Lindblad operators that are determined by the anti-Hermitian terms in the effective Hamiltonian.

    hep-phPoS(2016)·5 citations
22. 22*

    Electroweak vacuum stability in the Higgs-Dilaton theory

    A. Shkerin🇨🇭

    We study the stability of the Electroweak (EW) vacuum in a scale-invariant extension of the Standard Model and General Relativity, known as a Higgs-Dilaton theory. The safety of the EW vacuum against possible transition towards another vacuum is a necessary condition for the model to be phenomenologically acceptable. We find that, within a wide range of parameters of the theory, the decay rate is significantly suppressed compared to that of the Standard Model. We also discuss properties of a tunneling solution that are specific to the Higgs-Dilaton theory.

    hep-phhep-thJHEP(2017)·11 citations
23. 23*

    Phase structure of compactified $SU(N)$ gauge theories in magnetic backgrounds

    Massimo D'Elia🇮🇹 · Marco Mariti🇮🇹

    We discuss the properties of non-abelian gauge theories formulated on manifolds with compactified dimensions and in the presence of fermionic fields coupled to magnetic backgrounds. We show that different phases may emerge, corresponding to different realizations of center symmetry and translational invariance, depending on the compactification radius and on the magnitude of the magnetic field. Our discussion focuses on the case of an $SU(3)$ gauge theory in 4 dimensions with fermions fields in the fundamental representation, for which we provide some exploratory numerical lattice results.

    ↳ hep-lathep-phhep-thPRL(2017)·6 citations
24. 24*

    Implications of Missing Resonances in Heavy Ions Collisions

    Jacquelyn Noronha-Hostler🇺🇸

    Between 2004 until today many new resonances in the QCD spectrum have been added by the Particle Data Group. However, it is still possible that there are further states that have yet to be measured, as predicted by Lattice QCD calculations and Quark Models. In this paper I review how these missing states would influence the field of heavy-ion collisions. Additionally, the quantum numbers that characterize these missing states are also discussed.

    ↳ nucl-thhep-phnucl-ex5 citations
25. 25*

    Alien calculus and a Schwinger--Dyson equation: two-point function with a nonperturbative mass scale

    Marc P. Bellon🇫🇷 · Pierre J. Clavier🇩🇪

    Starting from the Schwinger--Dyson equation and the renormalization group equation for the massless Wess--Zumino model, we compute the dominant nonperturbative contributions to the anomalous dimension of the theory, which are related by alien calculus to singularities of the Borel transform on integer points. The sum of these dominant contributions has an analytic expression. When applied to the two-point function, this analysis gives a tame evolution in the deep euclidean domain at this approximation level, making doubtful the arguments on the triviality of the quantum field theory with positive \(\beta\)-function. On the other side, we have a singularity of the propagator for time like momenta of the order of the renormalization group invariant scale of the theory, which has a nonperturbative relationship with the renormalization point of the theory. All these results do not seem to have an interpretation in terms of semiclassical analysis of a Feynman path integral.

    ↳ hep-thhep-phmath-phmath.MPLett.Math.Phys.(2018)·17 citations
26. 26*

    Testing parity-violating physics from cosmic rotation power reconstruction

    Toshiya Namikawa (Stanford, SLAC)🇺🇸

    We study the reconstruction of the cosmic rotation power spectrum produced by parity-violating physics, with an eye to ongoing and near future cosmic microwave background (CMB) experiments such as BICEP Array, CMBS4, LiteBIRD and Simons Observatory. In addition to the inflationary gravitational waves and gravitational lensing, measurements of other various effects on CMB polarization open new window into the early Universe. One of these is anisotropies of the cosmic polarization rotation which probes the Chern-Simons term generally predicted by string theory. The anisotropies of the cosmic rotation are also generated by the primordial magnetism and in the Standard Model extention framework. The cosmic rotation anisotropies can be reconstructed as quadratic in CMB anisotropies. However, the power of the reconstructed cosmic rotation is a CMB four-point correlation and is not directly related to the cosmic-rotation power spectrum. Understanding all contributions in the four-point correlation is required to extract the cosmic rotation signal. Assuming a scale-invariant rotation spectrum motivated by the inflationary cosmic-rotation models, we employ simulation to quantify each contribution to the four-point correlation and find that (1) a secondary contraction of the trispectrum increases the total signal-to-noise, (2) a bias from the lensing-induced trispectrum is significant compared to the statistical errors in, e.g., LiteBIRD and CMBS4-like experiments, (3) the use of a realization-dependent estimator decreases the statistical errors by 10%-20%, depending on experimental specifications, and (4) other higher-order contributions are negligible at least for near future experiments.

    ↳ astro-ph.COhep-phhep-thPRD(2017)·27 citations
27. 27*

    Boltzmann-Langevin Approach to Pre-equilibrium Correlations in Nuclear Collisions

    Sean Gavin🇺🇸 · George Moschelli🇺🇸 · Christopher Zin🇺🇸

    Correlations born before the onset of hydrodynamic flow can leave observable traces on the final state particles. Measurement of these correlations can yield important information on the isotropization and thermalization process. Starting from a Boltzmann-like kinetic theory in the presence of dynamic Langevin noise, we derive a new partial differential equation for the two-particle correlation function that respects the microscopic conservation laws. We illustrate how this equation can be used to study the effect of thermalization on long range correlations.

    ↳ nucl-thhep-phnucl-exPRC(2017)·20 citations
28. 28*

    On the chiral covariant approach to $\rho \rho$ scattering

    Li-Sheng Geng🇨🇳 · Raquel Molina🇺🇸 · Eulogio Oset🇪🇸

    We examine in detail a recent work (D.~Gülmez, U.-G.~Meißner and J.~A.~Oller, Eur. Phys. J. C 77:460 (2017)), where improvements to make $\rho \rho$ scattering relativistically covariant are made. The paper has the remarkable conclusion that the $J=2$ state disappears with a potential which is much more attractive than for $J=0$, where a bound state is found. We trace this abnormal conclusion to the fact that an "on-shell" factorization of the potential is done in a region where this potential is singular and develops a large discontinuous and unphysical imaginary part. A method is developed, evaluating the loops with full $\rho$ propagators, and we show that they do not develop singularities and do not have an imaginary part below threshold. With this result for the loops we define an effective potential, which when used with the Bethe-Salpeter equation provides a state with $J=2$ around the energy of the $f_2(1270)$. In addition, the coupling of the state to $\rho \rho$ is evaluated and we find that this coupling and the $T$ matrix around the energy of the bound state are remarkably similar to those obtained with a drastic approximation used previously, in which the $q^2$ terms of the propagators of the exchanged $\rho$ mesons are dropped, once the cut-off in the $\rho \rho$ loop function is tuned to reproduce the bound state at the same energy.

    ↳ nucl-thhep-phCPC(2017)·28 citations
29. 29*

    Fermion confinement via Quantum Walks in 2D+1 and 3D+1 spacetime

    I. Marquez-Martin🇪🇸 · G. Di Molfetta🇫🇷 · A. Perez🇪🇸

    We analyze the properties of a two and three dimensional quantum walk that are inspired by the idea of a brane-world model put forward by Rubakov and Shaposhnikov [1]. In that model, particles are dynamically confined on the brane due to the interaction with a scalar field. We translated this model into an alternate quantum walk with a coin that depends on the external field, with a dependence which mimics a domain wall solution. As in the original model, fermions (in our case, the walker), become localized in one of the dimensions, not from the action of a random noise on the lattice (as in the case of Anderson localization), but from a regular dependence in space. On the other hand, the resulting quantum walk can move freely along the "ordinary" dimension.

    ↳ quant-phhep-phhep-thPRA(2017)·18 citations
30. 30*

    Heavy-flavor production and medium properties in high-energy nuclear collisions - What next?

    G. Aarts🇬🇧 · J. Aichelin🇫🇷 · C. Allton🇬🇧 · R. Arnaldi🇮🇹 · S. A. Bass🇺🇸 · C. Bedda🇳🇱 · N. Brambilla🇩🇪 · E. Bratkovskaya🇩🇪 · P. Braun-Munzinger🇩🇪 · G. E. Bruno🇮🇹 · T. Dahms🇩🇪 · S. K. Das🇮🇹 and 37 other authors

    Open and hidden heavy-flavor physics in high-energy nuclear collisions are entering a new and exciting stage towards reaching a clearer understanding of the new experimental results with the possibility to link them directly to the advancement in lattice Quantum Chromo-dynamics (QCD). Recent results from experiments and theoretical developments regarding open and hidden heavy-flavor dynamics have been debated at the Lorentz Workshop "Tomography of the quark-gluon plasma with heavy quarks}, which was held in October 2016 in Leiden, the Netherlands. In this contribution, we summarize identified common understandings and developed strategies for the upcoming five years, which aim at achieving a profound knowledge of the dynamical properties of the quark-gluon plasma.

    ↳ nucl-thhep-lathep-phnucl-exEPJA(2017)·122 citations
31. 31*

    Hybrid Stars in the Framework of different NJL Models

    G. A. Contrera🇦🇷 · M. Orsaria🇦🇷 · I. F. Ranea-Sandoval🇦🇷 · F. Weber🇺🇸

    We compute models for the equation of state (EoS) of the matter in the cores of hybrid stars. Hadronic matter is treated in the non-linear relativistic mean-field approximation, and quark matter is modeled by three-flavor local and non-local Nambu$-$Jona-Lasinio (NJL) models with repulsive vector interactions. The transition from hadronic to quark matter is constructed by considering either a soft phase transition (Gibbs construction) or a sharp phase transition (Maxwell construction). We find that high-mass neutron stars with masses up to $2.1-2.4M_{\odot }$ may contain a mixed phase with hadrons and quarks in their cores, if global charge conservation is imposed via the Gibbs conditions. However, if the Maxwell conditions is considered, the appearance of a pure quark matter core either destabilizes the star immediately (commonly for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (generally for local NJL models).

    ↳ nucl-thastro-ph.HEastro-ph.SRhep-phInt.J.Mod.Phys.Conf.Ser.(2017)·7 citations
32. 32*

    Production of ${\Lambda }_c^{+}$ hypernuclei in antiproton - nucleus collisions

    R. Shyam🇮🇳 · K. Tsushima🇧🇷

    We investigate the production of charm-baryon hypernucleus ${}_{{\Lambda }_c^{+}}^{16}$O in the antiproton - ${}^{16}$O collisions within a fully covariant model that is based on an effective Lagrangian approach. The explicit ${\bar{\Lambda }}_c^{-}{\Lambda }_c^{+}$ production vertex is described by the $t$-channel $D^0$ and $D^{\ast 0}$ meson-exchanges in the initial collision of the incident antiproton with one of the protons of the target nucleus. The ${\Lambda }_c^{+}$ bound state spinors as well as the self-energies of the exchanged mesons employed in our calculations are derived from the quark-meson coupling model. The parameters of various vertices are taken to be the same as those used in our previous study of the elementary $\bar{p}+p\to {\bar{\Lambda }}_c^{-}+{\Lambda }_c^{+}$ reaction. We find that for antiproton beam momenta of interest to the $\bar{P}ANDA$ experiment, the 0${}^{\circ }$ differential cross sections for the formation of ${}_{{\Lambda }_c^{+}}^{16}$O hypernuclear states with simple particle-hole configurations, have magnitudes in the range of a few $\mu$b/sr.

    ↳ nucl-thhep-exhep-phnucl-exPLB(2017)·21 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.