Thu·Aug 2, 2018Thursday·August 2, 2018

1. 01*

   Observables of low-lying supersymmetric vectorlike leptonic generations via loop corrections

   Amin Aboubrahim🇺🇸 · Tarek Ibrahim🇪🇬 · Ahmad Itani🇱🇧 · Pran Nath🇺🇸

   A correlated analysis of observables arising from loop induced effects from a vectorlike generation is given. The observables include flavor changing radiative decays $\mu \to e\gamma ,\tau \to \mu \gamma ,\tau \to e\gamma$, electric dipole moments of the charged leptons $e,\mu ,\tau$, and corrections to magnetic dipole moments of $g_{\mu }-2$ and $g_e-2$. In this work we give a full analysis of the corrections to these observables by taking into account both the supersymmetry loops as well as the exchange of a vectorlike leptonic generation. Thus the fermion mass matrix involves a $5\times 5$ mixing matrix while the scalar sector involves a $10\times 10$ mixing matrix including the CP violating phases from the vectorlike sector. The analysis is done under the constraint of the Higgs boson mass at the experimentally measured value. The loops considered include the exchange of $W$ and $Z$ bosons and of leptons and a mirror lepton, and the exchange of charginos and neutralinos, sleptons and mirror sleptons. The correction to the diphoton decay of the Higgs $h\to \gamma \gamma$ including the exchange of the vectorlike leptonic multiplet is also computed.

   hep-phhep-exPRD(2018)·4 citations
2. 02*

   Quark Wigner distribution of the pion meson in light-cone quark model

   Zhi-Lei Ma🇨🇳 · Zhun Lu🇨🇳

   We study the quark Wigner distributions of the pion meson which are the phase-space distributions containing the most general one-parton information.Using the pion wavefunctions deduced from a light-cone quark model, we calculate the Wigner distributions of the unpolarized, longitudinally polarized and transversely polarized quarks inside the pion meson via the Fock-state overlap representation, respectively.We present the numerical results of the transverse Wigner distributions in which the longitudinal momentum fraction is integrated out. The mixed Wigner distributions as functions of $b_y$ and $k_x$ are also presented.As a intermediate step, we provide the analytic results for the generalized transverse momentum dependent distributions of the pion meson in the same model.

   hep-phPRD(2018)·25 citations
3. 03*

   Nucleon gravitational form factors from instantons: forces between quark and gluon subsystems

   Maxim V. Polyakov🇷🇺 · Hyeon-Dong Son🇩🇪

   Using the instanton picture of the QCD vacuum we compute the nucleon ${\bar{c}}^Q(t)$ form factor of the quark part of the energy momentum tensor (EMT). This form factor describes the non-conservation of the quark part of EMT and contributes to the quark pressure distribution inside the nucleon. Also it can be interpreted in terms of forces between quark and gluon subsystems inside the nucleon. We show that this form factor is parametrically small in the instanton packing fraction. Numerically we obtain for the nucleon EMT a small value of ${\bar{c}}^Q(0)\simeq 1.4\cdot 10^{-2}$ at the low normalisation point of $\sim 0.4$ GeV${}^2$. This smallness implies interesting physics picture - the forces between quark and gluon mechanical subsystems are smaller than the forces inside each subsystem. The forces from side of gluon subsystem squeeze the quark subsystem - they are compression forces. Additionally, the smallness of ${\bar{c}}^Q(t)$ might justify Teryaev's equipartition conjecture. We estimate that the contribution of ${\bar{c}}^Q(t)$ to the pressure distribution inside the nucleon is in the range of 1 -20 % relative to the contribution of the quark $D$-term.

   hep-phhep-exhep-latJHEP(2018)·83 citations
4. 04*

   $T_{bbb}$: a three $B-$meson bound state

   H. Garcilazo🇲🇽 · A. Valcarce🇪🇸

   By solving exactly the Faddeev equations for the bound-state problem of three mesons, we demonstrate that current theoretical predictions pointing to the existence of a deeply-bound doubly bottom axial vector tetraquark lead to the existence of a unique bound state of three $B$ mesons. We find that the $B{B}^{\ast }{B}^{\ast }-B^{\ast }{B}^{\ast }{B}^{\ast }$ state with quantum numbers $(I)J^P=(1/2)2^{-}$, $T_{bbb}$, is about 90\,MeV below any possible three $B$-meson threshold for the reported binding of the doubly bottom axial vector tetraquark, $T_{bb}$.

   hep-phnucl-thPLB(2018)·12 citations
5. 05*

   No-$\pi$ Theorem for Euclidean Massless Correlators

   P.A. Baikov🇷🇺 · K.G. Chetyrkin🇩🇪

   We provide the reader with a (very) short review of recent advances in our understanding of the $\pi$-dependent terms in massless (Euclidean) 2-point functions as well as in generic anomalous dimensions and $\beta$-functions. We extend the considerations of [1] by one more loop, that is for the case of 6-loop correlators and 7-loop renormalization group (RG) functions.

   hep-phhep-thPoS(2018)·8 citations
6. 06*

   Charged current deep inelastic scattering of muon neutrinos off ^{56}Fe

   Deepika Grover🇮🇳 · Kapil Saraswat🇮🇳 · Prashant Shukla🇮🇳 · Venktesh Singh🇮🇳

   In this paper, we study charged current deep inelastic scattering of muon neutrinos off ^{56}Fe nuclei using Hirai, Kumano and Saito model. The LHA Parton Distribution Functions (PDFs) - CT10 are used to describe the partonic content of hadrons. Modification of PDFs inside the nuclei is done using EPPS16 parameterization at next-to-leading order. Target mass correction has also been incorporated in the calculations. We calculate the structure functions (F_{2}(x,Q^{2}) and xF_{3}(x,Q^{2})), the ratios (R_{2}(x,Q^{2}) = \frac{F^{^{56}Fe}_{2}}{F^{Nucleon}_{2}} and R_{3}(x,Q^{2}) = \frac{F^{^{56}Fe}_{3}}{F^{Nucleon}_{3}}) and the differential cross sections of muon neutrino deep inelastic scattering off a nucleon and ^{56}Fe nuclei. We compare the obtained results with measured experimental data. The present theoretical approach gives a good description of data.

   hep-phPRC(2018)·6 citations
7. 07*

   Forward charm-production models and prompt neutrinos at IceCube

   Atri Bhattacharya🇧🇪 · J. R. Cudell🇧🇪

   We investigate the prompt neutrino background at IceCube, as determined from forward charm. We consider the role of intrinsic charm and of a recombination model and show that the contribution of these mechanisms is at most a factor two.

   hep-phJHEP(2018)·6 citations
8. 08*

   Neutrino spin and spin-flavour oscillations in transversal matter currents with standard and non-standard interactions

   Pavel Pustoshny🇷🇺 · Alexander Studenikin🇷🇺

   After a brief history of two known types of neutrino mixing and oscillations, including neutrino spin and spin-flavour oscillations in the transversal magnetic field, we perform systematic study of a new phenomenon of neutrino spin and spin-flavour oscillations engendered by the transversal matter currents on the bases of the developed quantum treatment of the phenomenon. Possibilities for the resonance amplification of these new types of oscillations by the longitudinal matter currents and longitudinal magnetic fields are analyzed. Neutrino spin-flavour oscillations engendered by the transversal matter currents in the case of non-standard interactions of neutrinos with background matter are also considered

   hep-phPRD(2018)·34 citations
9. 09*

   Color matrix element corrections for parton showers

   Simon Plätzer🇦🇹 · Malin Sjodahl🇸🇪 · Johan Thorén🇸🇪

   We investigate the effects of keeping the full color structure for parton emissions in parton showers for both LEP and LHC. This is done within the Herwig 7 dipole shower, and includes gluon emission, gluon splitting, initial state branching processes, as well as hadronization. The subleading Nc terms are included as color matrix element corrections to the splitting kernels by evolving an amplitude-level density operator and correcting the radiation pattern for each parton multiplicity, up to a fixed number of full color emissions, after which a standard leading color shower takes over. Our results are compared to data for a wide range of LEP and LHC observables and show that the subleading Nc corrections tend to be small for most observables probing hard, perturbative dynamics, for both LEP and LHC. However, for some of these observables they exceed 10%. On soft physics we find signs of significantly larger effects.

   hep-phJHEP(2018)·56 citations
10. 10*

    Constraining a Lighter Exotic Scalar via Same-sign Top

    Wei-Shu Hou🇹🇼 · Masaya Kohda🇹🇼 · Tanmoy Modak🇹🇼

    It was shown recently that, in two Higgs doublet models without $Z_2$ symmetry, extra Yukawa couplings such as ${\rho }_{tc}$, ${\rho }_{tt}$ can fuel enough $CP$ violation for electroweak baryogenesis (EWBG). We revisit an old proposal where a pseudoscalar $A^0$ has mass between $t\bar{c}$ and $t\bar{t}$ thresholds. With ${\rho }_{tt}$ small, it evades $gg\to A^0\to h^0(125)Z$ constraints, where approximate alignment also helps. We find this scenario with relatively light $A^0$ is not yet ruled out, and $cg\to t{A}^0\to tt\bar{c}$ can probe sizable ${\rho }_{tc}$ at the LHC, giving access to the second mechanism of EWBG provided by such models.

    hep-phhep-exPLB(2018)·33 citations
11. 11*

    Strangeness Neutrality and QCD Thermodynamics

    Wei-jie Fu🇨🇳 · Jan M. Pawlowski🇩🇪 · Fabian Rennecke🇺🇸

    Since the incident nuclei in heavy-ion collisions do not carry strangeness, the global net strangeness of the detected hadrons has to vanish. We investigate the impact of strangeness neutrality on the phase structure and thermodynamics of QCD at finite baryon and strangeness chemical potential. To this end, we study the low-energy sector of QCD within a Polyakov loop enhanced quark-meson effective theory with 2+1 dynamical quark flavors. Non-perturbative quantum, thermal, and density fluctuations are taken into account with the functional renormalization group. We show that the impact of strangeness neutrality on thermodynamic quantities such as the equation of state is sizable.

    hep-phnucl-thSciPost Phys.Core(2020)·60 citations
12. 12*

    Quark spin structures of bottom-charmed threshold molecular states

    M.B. Voloshin🇺🇸

    The implementation of the heavy quark spin symmetry in possible molecular states at the mixed bottom-charm threshold is somewhat different from that at the open charm or bottom thresholds. In particular it depends on two parameters describing separately the symmetry for the bottom and for charmed quarks. The corresponding spin structures of the $S$-wave molecular states of the meson pairs $B^{(\ast )}{D}^{(\ast )}$ are discussed as well as their consequences for properties of possible near-threshold resonances, analogs of the known charmonium-like and bottomonium-like $X$ and $Z$ states.

    hep-phPRD(2018)·2 citations
13. 13*

    Charge Quantization and Neutrino Mass from Planck-scale SUSY

    Wen Yin🇨🇳

    We show a possibility for the charge quantization of the standard model (SM) particles. If a global symmetry makes the three copies of a generation and supersymmetry (SUSY) relates the Higgs boson to a lepton, all the charges of the SM particles can be quantized through gauge-anomaly cancellation. In the minimal model realizing the possibility, the gravitino mass around the Planck-scale is needed to generate the SM couplings through (quantum) supergravity. Much below the Planck-scale, the SM is obtained as the effective theory. Interestingly, if the gaugino masses are generated through anomaly mediation, one of the neutrino masses is predicted to be around the neutrino oscillation scales. In an extension of the model, millicharged particles can exist without introducing massless hidden photons.

    hep-phPLB(2018)·10 citations
14. 14*

    On the impact of dimension-eight SMEFT operators on Higgs measurements

    Chris Hays🇬🇧 · Adam Martin🇺🇸 · Veronica Sanz🇬🇧 · Jack Setford🇬🇧

    Using the production of a Higgs boson in association with a $W$ boson as a test case, we assess the impact of dimension-8 operators within the context of the Standard Model Effective Field Theory. Dimension-8--SM-interference and dimension-6-squared terms appear at the same order in an expansion in $1/\Lambda$, hence dimension-8 effects can be treated as a systematic uncertainty on the new physics inferred from analyses using dimension-6 operators alone. To study the phenomenological consequences of dimension-8 operators, one must first determine the complete set of operators that can contribute to a given process. We accomplish this through a combination of Hilbert series methods, which yield the number of invariants and their field content, and a step-by-step recipe to convert the Hilbert series output into a phenomenologically useful format. The recipe we provide is general and applies to any other process within the dimension $\le 8$ Standard Model Effective Theory. We quantify the effects of dimension-8 by turning on one dimension-6 operator at a time and setting all dimension-8 operator coefficients to the same magnitude. Under this procedure and given the current accuracy on $\sigma (pp\to h{W}^{+})$, we find the effect of dimension-8 operators on the inferred new physics scale to be small, $\mathcal{O}(\text{few}\%)$, with some variation depending on the relative signs of the dimension-8 coefficients and on which dimension-6 operator is considered. The impact of the dimension-8 terms grows as $\sigma (pp\to h{W}^{+})$ is measured more accurately or (more significantly) in high-mass kinematic regions. We provide a FeynRules implementation of our operator set to be used for further more detailed analyses.

    hep-phhep-exJHEP(2019)·130 citations
15. 15*

    Anatomy of ${\epsilon }^{\prime }/\epsilon$ beyond the Standard Model

    Jason Aebischer🇩🇪 · Christoph Bobeth🇩🇪 · Andrzej J. Buras🇩🇪 · David M. Straub🇩🇪

    We present for the first time a model-independent anatomy of the ratio ${\epsilon }^{\prime }/\epsilon$ in the context of the $\Delta S=1$ effective theory with operators invariant under QCD and QED and in the context of the Standard Model Effective Field Theory (SMEFT) with the operators invariant under the full SM gauge group. Our goal is to identify the new physics scenarios that are probed by this ratio and which could help to explain a possible deviation from the SM that is hinted by the data. To this end we derive a master formula for ${\epsilon }^{\prime }/\epsilon$, which can be applied to any theory beyond the Standard Model (BSM) in which the Wilson coefficients of all contributing operators have been calculated at the electroweak scale. The relevant hadronic matrix elements of BSM operators are from the Dual QCD approach and the SM ones from lattice QCD. Within SMEFT, the constraints from $K^0$ and $D^0$ mixing as well as electric dipole moments limit significantly potential new physics contributions to ${\epsilon }^{\prime }/\epsilon$. Correlations of ${\epsilon }^{\prime }/\epsilon$ with $K\to \pi \nu \bar{\nu }$ decays are briefly discussed. Building on our EFT analysis and the model-independent constraints, we discuss implications of a possible deviation from the SM in ${\epsilon }^{\prime }/\epsilon$ for model building, highlighting the role of the new scalar and tensor matrix elements in models with scalar mediators.

    hep-phhep-exhep-latEPJC(2019)·55 citations
16. 16*

    Leptogenesis via Varying Weinberg Operator: the Closed-Time-Path Approach

    Jessica Turner🇺🇸 · Ye-Ling Zhou🇬🇧

    In this work we provide a detailed study of the CP violating phase transition (CPPT) which is a new mechanism proposed to produce a baryon asymmetry. This mechanism exploits the Weinberg operator whose coefficient is dynamically realised from the vacuum expectation values (VEVs) of new scalars. In the specific case of the first order phase transition, the scalar VEVs vary in the bubble wall which separates the two phases. This results in a spacetime varying coefficient for the Weinberg operator. The interference of two Weinberg operators at different spacetime points generates a CP asymmetry between lepton and anti-lepton production/annihilation processes, which eventually results in an asymmetry between baryon and anti-baryon number densities in the early Universe. We present the calculation of the lepton asymmetry, based on non-equilibrium quantum field theory methods, in full. We consider the influence of the bubble wall characteristics and the impact of thermal effects on the lepton asymmetry and draw a comparison between the CPPT mechanism and electroweak baryogenesis.

    hep-phJHEP(2020)·8 citations
17. 17*

    Leptogenesis via Varying Weinberg Operator: a Semi-Classical Approach

    Silvia Pascoli🇬🇧 · Jessica Turner🇺🇸 · Ye-Ling Zhou🇬🇧

    In this Letter, we introduce leptogenesis via a varying Weinberg operator from a semi-classical perspective. This mechanism is motivated by the breaking of an underlying symmetry which triggers a phase transition that causes the coupling of the Weinberg operator to become dynamical. Consequently, a lepton anti-lepton asymmetry arises from the interference of the Weinberg operator at two different spacetime points. Using this semi-classical approach, we treat the Higgs as a background field and show a reflection asymmetry between the leptons and anti-leptons is generated in the vicinity of the bubble wall. We solve the equations of motion of the lepton and anti-lepton quasiparticles to obtain the final lepton asymmetry.

    hep-phCPC(2019)·6 citations
18. 18*

    Confronting new physics theories to LHC data with MadAnalysis 5

    Eric Conte🇫🇷 · Benjamin Fuks🇫🇷

    We provide a comprehensive and pedagogical introduction to the MadAnalysis 5 framework, with a particular focus on its usage for reinterpretation studies. To this end, we first review the main features of the normal mode of the program and how a detector simulation can be handled. We then detail, step-by-step, how to implement and validate an existing LHC analysis in the MadAnalysis 5 framework and how to use this reimplementation, possibly together with other recast codes available from the MadAnalysis 5 Public Analysis Database, for reinterpreting ATLAS and CMS searches in the context of a new model. Each of these points is illustrated by concrete examples. Moreover, complete reference cards for the normal and expert modes of MadAnalysis 5 are provided in two technical appendices.

    hep-phhep-exInt.J.Mod.Phys.A(2018)·205 citations
19. 19*

    $p_t$- dependence of the flow coefficients for pp collisions in the color string scenario. Monte-Carlo simulations

    M.A. Braun🇷🇺 · C. Pajares🇪🇸

    In the color string picture with fusion and percolation the dependence of the flow coefficients $v_n$ on the transverse momentum is studied for pp collisions the LHC energy respectively. Monte-Carlo simulations are used to locate simple strings and their fused clusters. The results favorably agree with the CMS data in the region $0.2\le p_t\le 3.$ GeV/c appropriate for the string scenario.

    hep-phnucl-thEPJA(2018)·5 citations
20. 20*

    Effects of a caustic ring of dark matter on the distribution of stars and interstellar gas

    Sankha S. Chakrabarty🇺🇸 · Pierre Sikivie🇺🇸

    Caustic rings of dark matter with $\text{tricusp}$ cross-section were predicted to lie in the galactic disk. Their radii increase on cosmological time scales at a rate of order $1$ kpc/Gyr. When a caustic ring passes through the orbit of a star, the orbit is strongly perturbed. We find that a star moving in a nearly circular orbit is first attracted towards the caustic ring, then moves with and oscillates about the caustic for approximately $1$ Gyr before returning to its original orbit. As a result, a stellar overdensity forms around the caustic ring. We predict such overdensities to be of order $120\%$ near the 2nd caustic ring where the Monoceros Ring is observed and of order $45$, $30$ and $15\%$ near the 3rd, 4th and 5th caustic rings, respectively. We show that the associated bulk velocities of the stars near the caustic rings are less than a few km/s. We also determine the density profile of interstellar gas near the 5th caustic ring assuming it is in thermal equilibrium in the gravitational potential of the caustic and of the gas itself.

    ↳ astro-ph.GAhep-phPRD(2018)·8 citations
21. 21*

    Coaction for Feynman integrals and diagrams

    Samuel Abreu🇩🇪 · Ruth Britto🇮🇪 · Claude Duhr🇨🇭 · Einan Gardi🇬🇧 · James Matthew🇬🇧

    We propose a general coaction for families of integrals appearing in the evaluation of Feynman diagrams, such as multiple polylogarithms and generalized hypergeometric functions. We further conjecture a link between this coaction and graphical operations on Feynman diagrams. At one-loop order, there is a basis of integrals for which this correspondence is fully explicit. We discuss features and present examples of the diagrammatic coaction on two-loop integrals. We also present the coaction for the functions ${}_{p+1}{F}_p$ and Appell $F_1$.

    ↳ hep-thhep-phPoS(2018)·15 citations
22. 22*

    Re-examining the premise of isobaric collisions and a novel method to measure the chiral magnetic effect

    Hao-jie Xu🇨🇳 · Jie Zhao🇺🇸 · Xiaobao Wang🇨🇳 · Hanlin Li🇨🇳 · Zi-Wei Lin🇺🇸 · Caiwan Shen🇨🇳 · Fuqiang Wang🇺🇸

    In this proceeding we will show that the expectations of the isobaric ${}_{44}^{96}\mathrm{Ru}{+}_{44}^{96}\mathrm{Ru}$ and ${}_{40}^{96}\mathrm{Zr}{+}_{40}^{96}\mathrm{Zr}$ collisions on chiral magnetic effect (CME) search may not hold as originally anticipated due to large uncertainties in the isobaric nuclear structures. We demonstrate this using Woods-Saxon densities and the proton and neutron densities calculated by the density functional theory. Furthermore, a novel method is proposed to gauge background and possible CME contributions in the same system, intrinsically better than the isobaric collisions of two different systems. We illustrate the method with Monte Carlo Glauber and AMPT (A Multi-Phase Transport) simulations.

    ↳ nucl-thhep-phnucl-exNPA(2019)·4 citations
23. 23*

    A Fresh Look at the Calculation of Tunneling Actions including Gravitational Effects

    J. R. Espinosa🇪🇸

    Recently, the calculation of tunneling actions, that control the exponential suppression of the decay of metastable vacua, has been reformulated as an elementary variational problem in field space. This paper extends this formalism to include the effect of gravity. Considering tunneling potentials $V_t(\varphi )$ that go from the false vacuum ${\varphi }_{+}$ to some ${\varphi }_0$ on the stable basin of the scalar potential $V(\varphi )$, the tunneling action is the minimum of the functional $S_E[V_t]=6{\pi }^2{m}_P^4{\int }_{{\varphi }_{+}}^{{\varphi }_0}(D+V_t^{\prime }{)}^2/(V_t^{2}D)d\varphi$, where $D\equiv [(V_t^{\prime }{)}^2+6(V-V_t)V_t/m_P^2{]}^{1/2}$, $V_t^{\prime }=d{V}_t/d\varphi$ and $m_P$ is the reduced Planck mass. This one-line simple result applies equally to AdS, Minkowski or dS vacua decays and reproduces the Hawking-Moss action in the appropriate cases. This formalism provides new handles for the theoretical understanding of different features of vacuum decay in the presence of gravity.

    ↳ hep-thhep-phPRD(2019)·39 citations
24. 24*

    Goldstone bosons and the Englert-Brout-Higgs mechanism in non-Hermitian theories

    Philip D. Mannheim🇺🇸

    In recent work Alexandre, Ellis, Millington and Seynaeve have extended the Goldstone theorem to non-Hermitian Hamiltonians that possess a discrete antilinear symmetry such as $PT$. They restricted their discussion to those realizations of antilinear symmetry in which all the energy eigenvalues of the Hamiltonian are real. Here we extend the discussion to the two other realizations possible with antilinear symmetry, namely energies in complex conjugate pairs or Jordan-block Hamiltonians that are not diagonalizable at all. In particular, we show that under certain circumstances it is possible for the Goldstone boson mode itself to be one of the zero-norm states that are characteristic of Jordan-block Hamiltonians. While we discuss the same model as Alexandre et al. our treatment is quite different, though their main conclusion that one can have Goldstone bosons in the non-Hermitian case remains intact. In their paper Alexandre et al. presented a variational procedure for the action in which the surface term played an explicit role, to thus suggest that one has to use such a procedure in order to establish the Goldstone theorem in the non-Hermitian case. However, by taking certain fields that they took to be Hermitian to actually either be anti-Hermitian or be made so by a similarity transformation, we show that we are then able to obtain a Goldstone boson using a completely standard variational procedure. Since we use a standard variational procedure we can readily extend our analysis to a continuous local symmetry by introducing a gauge boson. We show that when we do this the gauge boson acquires a non-zero mass by the Higgs mechanism in all realizations of the antilinear symmetry, except the one where the Goldstone boson itself has zero norm, in which case, and despite the fact that the continuous local symmetry has been spontaneously broken, the gauge boson remains massless.

    ↳ hep-thhep-phPRD(2019)·56 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.