Wed·Nov 28, 2018Wednesday·November 28, 2018

1. 01*

   Deformation of Axion Potentials: Implications for Spontaneous Baryogenesis, Dark Matter, and Isocurvature Perturbations

   Kyu Jung Bae🇰🇷 · Jeff Kost🇰🇷 · Chang Sub Shin🇰🇷

   We show that both the baryon asymmetry of the universe and dark matter (DM) can be accounted for by the dynamics of a single axion-like field. In this scenario, the observed baryon asymmetry is produced through spontaneous baryogenesis---driven by the early evolution of the axion---while its late-time coherent oscillations explain the observed DM abundance. Typically, spontaneous baryogenesis via axions is only successful in regions of parameter space where the axion is relatively heavy, rendering it highly unstable and unfit as a dark matter candidate. However, we show that a field-dependent wavefunction renormalization can arise which effectively "deforms" the axion potential, allowing for efficient generation of baryon asymmetry while maintaining a light and stable axion. Meanwhile, such deformations of the potential induce non-trivial axion dynamics, including a tracking behavior during its intermediate phase of evolution. This attractor-like dynamics dramatically reduces the sensitivity of the axion relic abundance to initial conditions and naturally suppresses DM isocurvature perturbations. Finally, we construct an explicit model realization, using a continuum-clockwork axion, and survey the details of its phenomenological viability.

   hep-phPRD(2019)·15 citations
2. 02*

   Extracting $\gamma$ from three-body $B$-meson decays

   Bhubanjyoti Bhattacharya🇺🇸 · David London🇨🇦

   To date, the weak-phase $\gamma$ has been measured using two-body $B$-meson decays such as $B\to DK$ and $B\to D\pi$, whose amplitudes contain only tree-level diagrams. But $\gamma$ can also be extracted from three-body charmless hadronic $B$ decays. Since the amplitudes for such decays contain both tree- and loop-level diagrams, $\gamma$ obtained in this way is sensitive to new physics that can enter into these loops. The comparison of the values of $\gamma$ extracted using tree-level and loop-level methods is therefore an excellent test for new physics. In this talk, we will show how U-spin and flavor-SU(3) symmetries can be used to develop methods for extracting $\gamma$ from $B\to K\pi \pi$ and $B\to KK\bar{K}$ decays. We describe a successful implementation of the flavor-SU(3) symmetry method applied to BaBar data.

   hep-phhep-ex3 citations
3. 03*

   Light Pseudoscalar and Axial Spectroscopy using AdS/QCD Modified Soft Wall Model

   Miguel Ángel Martín Contreras🇨🇱 · Alfredo Vega🇨🇱 · Santiago Cortés🇨🇴

   We study light pseudoscalar and axial states using a soft wall model that is modified by introducing two extra parameters: an UV-cutoff and an anomalous term in the conformal dimension of the fields involved such that meson fields with different parities are easily distinguishable. We find that 23 of these light mesonic states, including the scalars and vector states analyzed with one of our previous results, are fitted within the RMS error bounds given for this model, whose parameters are given by the quadratic dilaton profile, the UV locus $z_0$ and the anomalous term ${\Delta }_P$. Our results show that Regge trajectories for pseudoscalar and axial mesons are linear in the radial quantum number $n$, as expected for these sort of regular $q\overline{q}$ mesons.

   hep-phChin.J.Phys.(2020)·17 citations
4. 04*

   Strong decays of the ${\Xi }_b(6227)$ as a ${\Sigma }_b\bar{K}$ molecule

   Yin Huang🇨🇳 · Cheng-jian Xiao🇨🇳 · Li-Sheng Geng🇨🇳 · Jun He🇨🇳

   We study the strong decays of the newly observed ${\Xi }_b(6227)$ assuming that it is a pure ${\Sigma }_b\bar{K}$ molecular state. Considering four possible spin-parity assingments $J^P=1/2^{\pm }$ and $3/2^{\pm }$, the partial decay widths of the ${\Sigma }_b\bar{K}$ molecular state into ${\Lambda }_b\bar{K}$, ${\Xi }_b\pi$, and ${\Xi }_b^{{}^{\prime }}\pi$ final states through hadronic loops are evaluated with the help of the effective Lagrangians. In comparison with the LHCb data, the spin-party $1/2^{-}$ assignment is preferred while those of $J^P=1/2^{+}$ and $J^P=3/2^{\pm }$ are disfavored. In addition, we show that the two allowed decay modes ${\Lambda }_b\bar{K}$ and ${\Xi }_b\pi$ of the ${\Xi }_b(6227)$, being a $S$-wave ${\Sigma }_b\bar{K}$ molecular state, have almost equal branching ratios, consistent with the data.

   hep-phPRD(2019)·36 citations
5. 05*

   Anatomy of a six-parameter fit to the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies

   Bernat Capdevila🇪🇸 · Ursula Laa🇦🇺 · German Valencia🇦🇺

   Discrepancies between measurements of decay modes with an underlying quark level transition $b\to s{\ell }^{+}{\ell }^{-}$ and standard model (SM) predictions have persisted for several years, particularly for the muon channels. The inadequacy of the SM becomes more compelling in a global fit. For example, Ref. [1] described 175 observables by six parameters encoding new physics and quantified the disagreement with the SM at about the $5\sigma$ level. While certain one and two parameter fits have previously been considered in detail, we establish a framework for the detailed discussion of the full 6d fit. We visualize and quantify the 6d $1\sigma$ region around the best fit point and define fit uncertainties for both current and future observables. We then define metrics quantifying the deviations between measurements and both SM and best fit predictions. These metrics relate observables to directions in parameter space, revealing their precise role in the fit, thus providing guidance for future theoretical and experimental work. Some metrics further quantify the role of correlated uncertainties, which turns out to be significant. For example the relevance of angular observables such as $P_5^{\prime }$ is reduced in this context. Finally, studying the space of observables allows us to discuss the internal tensions in the fit.

   hep-phhep-exphysics.data-anEPJC(2019)·23 citations
6. 06*

   Quantum Chromodynamics and the Precision Phenomenology of Heavy Quarks

   M. A. Lim🇬🇧

   In this thesis we consider the phenomenology of QCD, with particular reference to the ongoing experimental program at the Large Hadron Collider in CERN. The current progress in precision measurement of Standard Model processes at the LHC experiments must be matched with corresponding precision in theoretical predictions. Such calculations are vital if we are to untangle signals of New Physics from LHC data. We consider in particular the amplitudes for five parton interactions at 1- and 2-loop order and present analytic results in terms of rational functions multiplying a basis of master integrals. We address the problem of the solution of a system of integration-by-parts identities for Feynman integrals and demonstrate how some current difficulties may be mitigated. We consider also the properties of the top quark, and present the real-virtual contributions to the calculation of its decay rate. These amplitudes constitute a necessary ingredient in the complete calculation of top quark pair production and decay at NNLO. Turning to phenomenology, we consider the extraction of two important SM parameters, the top mass and the strong coupling constant, from measurements of top pair production at the ATLAS and CMS experiments. We compare with NNLO theory predictions and extract the parameters simultaneously. We find values which are compatible with the current world averages published by the PDG. Finally, we examine the circumstances in which a heavy quark can be considered a constituent of the proton. We look at the production of a Higgs boson in association with b quarks in schemes in which the b may or may not be included in the initial state. We show that predictions in both schemes are well-motivated, and moreover that both are consistent provided a judicious choice of scales is made. We suggest a typical scale choice somewhat lower than the typical hard scale of the process.

   hep-ph3 citations
7. 07*

   Gravitational waves and collider signatures from holographic phase transitions in soft walls

   Eugenio Megias🇪🇸 · Germano Nardini🇳🇴 · Mariano Quiros🇪🇸

   Using a five-dimensional warped model including a scalar potential with an exponential behavior in the infrared, and strong back-reaction over the metric, we study the electroweak phase transition, and explore parameter regions that were previously inaccessible. The model exhibits gravitational waves and predicts a stochastic gravitational wave background observable, both at the Laser Interferometer Space Antenna and at the Einstein Telescope. Moreover, concerning the collider signatures predictions, the radion evades current constraints but may show up in future LHC runs.

   hep-phgr-qchep-thPoS(2018)·3 citations
8. 08*

   EMC effect at small Bjorken x values

   A.Kotikov🇷🇺 · B. Shaikhatdenov🇷🇺 · P. Zhang🇨🇳

   The Bessel-inspired behavior of parton densities at small Bjorken x values is used along with `frozen' and analytic modifications of the strong coupling constant [1] to study the so-called EMC effect. Among other results, this approach allowed predicting small x behavior of the gluon density in nuclei.

   hep-phEPJ Web Conf.(2019)·4 citations
9. 09*

   Where is the stable Pentaquark

   Woosung Park🇰🇷 · Sungtae Cho🇰🇷 · Su Houng Lee🇰🇷

   We systematically analyze the flavor color spin structure of the pentaquark $q^4\bar{Q}$ system in a constituent quark model based on the chromomagnetic interaction in both the SU(3) flavor symmetric and SU(3) flavor broken case with and without charm quarks. We show that the originally proposed pentaquark state $\bar{Q}sqqq$ by Gignoux et al and by Lipkin indeed belongs to the most stable pentaquark configuration, but that when charm quark mass correction based on recent experiments are taken into account, a doubly charmed antistrange pentaquark configuration ($udcc\bar{s}$) is perhaps the only flavor exotic configuration that could be stable and realistically searched for at present through the ${\Lambda }_c{K}^{+}{K}^{-}{\pi }^{+}$ final states. The proposed final state is just reconstructing $K^{+}$ instead of ${\pi }^{+}$ in the measurement of ${\Xi }_{cc}^{++}\to {\Lambda }_c{K}^{-}{\pi }^{+}{\pi }^{+}$ reported by LHCb collaboration and hence measurable immediately.

   hep-phPRD(2019)·29 citations
10. 10*

    Reconciling $B$-meson Anomalies, Neutrino Masses and Dark Matter

    Girish Kumar🇮🇳 · Chandan Hati🇫🇷 · Jean Orloff🇫🇷 · Ana M. Teixeira🇫🇷

    We explore the connection of the leptoquark solution to the recently reported $B$-meson anomalies with a mechanism of neutrino mass generation and a viable dark matter candidate. We consider a model consisting of two scalar leptoquarks and three generations of triplet fermions: neutrino masses are radiatively generated at the 3-loop level and, by imposing a discrete $Z_2$ symmetry, one can obtain a viable dark matter candidate. We discuss the constraints on the flavour structure of this model arising from numerous flavour observables. The rare decay $K\to {\pi }^{+}\nu \bar{\nu }$ and charged lepton flavour violating $\mu -e$ conversion in nuclei are found to provide the most stringent constraint on this class of models.

    hep-phSpringer Proc.Phys.(2019)·2 citations
11. 11*

    Probing nuclear PDFs with dijets in ultra-peripheral Pb+Pb collisions

    Ilkka Helenius🇫🇮

    In this talk we apply the photoproduction framework recently implemented into the Pythia 8 Monte Carlo event generator to study the potential of photo-nuclear dijets in ultra-peripheral Pb+Pb collisions at the LHC to further constrain the nuclear PDFs. These events can be described as $\gamma$A collisions where the relevant part of the flux of quasi-real photons from heavy-ions is obtained by using the equivalent photon approximation and cutting out impact-parameter values which would lead to hadronic interactions between the beam particles. In particular, we quantify the small-$x$ reach with different jet kinematics and show how well the values of $x$ derived from reconstructed jet momenta are correlated with the actual values of partonic momentum fractions probed in these measurements. Also the contributions from direct and resolved photons are separately presented. To demonstrate the potential, we compare the expected experimental uncertainties to the current nuclear-PDF errors and discuss other theoretical uncertainties including the uncertainty arising from poorly-constrained photon PDFs. We find that such a measurement would potentially provide a considerable reduction of the nuclear PDF uncertainties in a region $10^{-4}\lesssim x\lesssim 10^{-2}$.

    hep-phPoS(2018)·6 citations
12. 12*

    NLO prediction for the decays $\tau \to \ell {\ell }^{\prime }{\ell }^{\prime }\nu \bar{\nu }$ and $\mu \to eee\nu \bar{\nu }$

    Matteo Fael🇩🇪

    These proceedings review the differential decay rates and the branching ratios of the tau and muon decays $\tau \to \ell {\ell }^{\prime }{\ell }^{\prime }\nu \bar{\nu }$ (with $\ell ,{\ell }^{\prime }=\mu ,e$) and $\mu \to eee\nu \bar{\nu }$ in the Standard Model at NLO. These five-body leptonic decays are a tool to study the Lorentz structure of weak interactions and to test lepton flavour universality. They are also a source of SM background to searches for the lepton-flavour-violating decays $\mu \to eee$ and $\tau \to \ell {\ell }^{\prime }{\ell }^{\prime }$. Even if the shift in the branching ratios induced by radiative corrections turns out to be small and of order 1% --- mainly due to a running effect of the fine structure constant --- locally in the phase space these corrections can reach the 5 - 10% level, depending on the applied cuts. We found for instance that in the phase space region where the neutrino energies are small, and the momenta of the three charged leptons have a similar signature as in $\mu \to eee$ and $\tau \to \ell {\ell }^{\prime }{\ell }^{\prime }$, the NLO corrections decrease the leading-order prediction by about 10 - 20%.

    hep-phSciPost Phys.Proc.(2019)·1 citation
13. 13*

    Double interference effects in Higgs precision tests in the $e^{-}{e}^{+}\to \nu \bar{\nu }h$ process

    Yang Zhang🇨🇳

    Higgs precision program at future lepton collider aims at (sub) percent level precision measurement of the Higgs properties, shedding light to new physics through the Higgs lamppost. Amongst many exclusive Higgs channels that can be measured precisely, the $WW$-fusion to Higgs with subsequent decays into $b\bar{b}$ final state are of particular importance. This channel provide leading constrains on Higgs total width in the $\kappa$-framework and greatly improves the constraints in the EFT framework as a distinct production mode other than the Higgsstrahlung process. We argue in this paper that, there are two interference effects both affects the physical information one can extract from the precision measurements. One takes place at quantum level from the interference between the two amplitudes that amounts to $-10\%$ of the $WW$-fusion signal strength, failing to take into account which will result in a $4$-$5\sigma$ discrepancy between theory and measurement. The other takes place at the classical level from the global fitting procedure where the $ZH$ process is the dominant background with its cross section around six times larger than the $WW$-fusion signal. Despite that $ZH$ process can be measured to great precision at future lepton colliders, failing take this interplay in the coupling extraction will result in a 100\% too aggressive constraints on ${\kappa }_W$, the Higgs coupling to $W$-boson pairs. This effect will also be important for lepton colliders running at slightly higher energies where the phase space overlap are still sizable between the two processes.

    hep-phPRD(2019)·0 citations
14. 14*

    Probing CP nature of a mediator in associated production of dark matter with single top quark

    Genevieve Belanger🇫🇷 · Rohini M. Godbole🇮🇳 · Charanjit K. Khosa🇬🇧 · Saurabh D. Rindani🇮🇳

    We consider associated production of dark matter with single top quark, in a simplified dark matter model with spin-0 mediators. The produced top quark is polarized and the polarization depends on the CP of the mediator. We calculate both the cross-section and top polarization for these processes. We compute angular asymmetries which demonstrate the difference between the polarization expected for the scalar or pseudoscalar mediator. Both the cross section and top polarization are sensitive to the CP property of the mediator, depending on the mediator mass. We find that these polarization asymmetries add value to the determination of the CP property of the mediator particularly in the case of a state with indeterminate CP.

    hep-ph3 citations
15. 15*

    The role of leptons in electroweak baryogenesis

    Jordy de Vries🇺🇸 · Marieke Postma🇳🇱 · Jorinde van de Vis🇳🇱

    We investigate the role of leptons in electroweak baryogenesis by studying a relatively simple framework inspired by effective field theory that satisfies all Sakharov conditions. In particular, we study the effectiveness of CP-violating source terms induced by dimension-six Yukawa interactions for quarks and charged leptons. Despite the relatively small Yukawa coupling, CP-violating source terms involving taus are quite effective and can account for the observed matter-antimatter asymmetry. We obtain analytical and numerical expressions for the total baryon asymmetry, the former providing important insight into what makes lepton CP violation relatively effective compared to quark CP violation. Leptons also play an important role if the CP-violating source involves top quarks. While the tau Yukawa coupling in the Standard Model is small, it significantly enhances the baryon asymmetry by transferring the chiral asymmetry in quarks, which is washed out by strong sphalerons, to a chiral asymmetry in leptons. We conclude that leptons should not be ignored even if CP violation is limited to the quark sector. The role of leptons can be further increased in scenarios of new physics with additional chiral-symmetry-breaking interactions between quarks and leptons, as can happen in models with additional Higgs bosons or leptoquarks. Finally, we study CP-violating dimension-six Yukawa interactions for lighter quarks and leptons but conclude that these lead to too small baryon asymmetries.

    hep-phastro-ph.COJHEP(2019)·73 citations
16. 16*

    Constraining ultra light fermionic dark matter with Milky-Way observations

    J. Barranco🇲🇽 · A. Bernal🇲🇽 · D. Delepine🇲🇽

    The equation of state for a degenerate gas of fermions at zero temperature in the non-relativistic case is a polytrope, i.e. $p\sim {\rho }^{5/3}/m_F^{8/3}$. If dark matter is modeled by such a non-interacting fermion, this dependence in the mass of the fermion $m_F$ explains why if dark matter is very heavy the effective pressure of dark matter is negligible. Nevertheless, if the mass of the dark matter is very small, the effective pressure can be very large, and thus a system of self-gravitating fermions can be formed. In this work we model the dark matter halo of the Milky-Way by solving the Tolman-Oppenheimer-Volkoff equations, with the equation of state for a partially degenerate ultralight non-interacting fermion. We found that to fit the rotational velocity curve of the Milky-Way, the mass of the fermion should be in the range $31.5\text{mbox}eV<m_F<35$eV at $90\%$ C.L. Moreover, the central density is restricted to be in the range of $1.2<{\rho }_0<1.7$ GeV/cm${}^3$ at $90\%$ C.L. The fermionic dark matter halo has a very different profile as compared with the standard Navarro-Frenk-White profile, thus, the possible indirect signals for annihilating dark matter may change by orders of magnitude. We found bounds for the annihilation cross section in this case by using the Saggitarius A* spectral energy distribution.

    hep-phastro-ph.HEJ.Phys.G(2026)·11 citations
17. 17*

    Phase transition and vacuum stability in the classically conformal B-L model

    Carlo Marzo🇪🇪 · Luca Marzola🇪🇪 · Ville Vaskonen🇬🇧

    Within classically conformal models, the spontaneous breaking of scale invariance is usually associated to a strong first order phase transition that results in a gravitational wave background within the reach of future space-based interferometers. In this paper we study the case of the classically conformal gauged B-L model, analysing the impact of this minimal extension of the Standard Model on the dynamics of the electroweak symmetry breaking and derive its gravitational wave signature. Particular attention is paid to the problem of vacuum stability and to the role of the QCD phase transition, which we prove responsible for concluding the symmetry breaking transition in part of the considered parameter space. Finally, we calculate the gravitational wave signal emitted in the process, finding that a large part of the parameter space of the model can be probed by LISA.

    hep-phastro-ph.COEPJC(2019)·143 citations
18. 18*

    Dark, Cold, and Noisy: Constraining Secluded Hidden Sectors with Gravitational Waves

    Moritz Breitbach🇩🇪 · Joachim Kopp🇨🇭 · Eric Madge🇩🇪 · Toby Opferkuch🇩🇪 · Pedro Schwaller🇩🇪

    We explore gravitational wave signals arising from first-order phase transitions occurring in a secluded hidden sector, allowing for the possibility that the hidden sector may have a different temperature than the Standard Model sector. We present the sensitivity to such scenarios for both current and future gravitational wave detectors in a model-independent fashion. Since secluded hidden sectors are of particular interest for dark matter models at the MeV scale or below, we pay special attention to the reach of pulsar timing arrays. Cosmological constraints on light degrees of freedom restrict the number of sub-MeV particles in a hidden sector, as well as the hidden sector temperature. Nevertheless, we find that observable first-order phase transitions can occur. To illustrate our results, we consider two minimal benchmark models: a model with two gauge singlet scalars and a model with a spontaneously broken $U(1)$ gauge symmetry in the hidden sector.

    hep-phastro-ph.COJCAP(2019)·272 citations
19. 19*

    Nucleon matrix elements of the antisymmetric quark tensor

    Martin Hoferichter🇺🇸 · Bastian Kubis🇩🇪 · Jacobo Ruiz de Elvira🇨🇭 · Peter Stoffer🇺🇸

    If physics beyond the Standard Model enters well above the electroweak scale, its low-energy effects are described by Standard Model Effective Field Theory. Already at dimension six many operators involve the antisymmetric quark tensor $\bar{q}{\sigma }^{\mu \nu }q$, whose matrix elements are difficult to constrain from experiment, Ward identities, or low-energy theorems, in contrast to the corresponding vector and axial-vector or even scalar and pseudoscalar currents. However, with normalizations determined from lattice QCD, analyticity and unitarity often allow one to predict the momentum dependence in a large kinematic range. Starting from recent results in the meson sector, we extend this method to the nucleon case and, in combination with pole dominance, provide a comprehensive assessment of the current status of the nucleon form factors of the quark tensor.

    hep-phhep-latnucl-thPRL(2019)·46 citations
20. 20*

    U-Spin Sum Rules for CP Asymmetries of Three-Body Charmed Baryon Decays

    Yuval Grossman🇺🇸 · Stefan Schacht🇺🇸

    Triggered by a recent LHCb measurement and prospects for Belle II, we derive U-spin symmetry relations between integrated CP asymmetries of three-body ${\Lambda }_c^{+}$ and ${\Xi }_c^{+}$ decays. The sum rules read $A_{CP}({\Lambda }_c^{+}\to p{K}^{-}{K}^{+})+A_{CP}({\Xi }_c^{+}\to {\Sigma }^{+}{\pi }^{-}{\pi }^{+})=0$, $A_{CP}({\Lambda }_c^{+}\to p{\pi }^{-}{\pi }^{+})+A_{CP}({\Xi }_c^{+}\to {\Sigma }^{+}{K}^{-}{K}^{+})=0$, and $A_{CP}({\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^{-}{K}^{+})+A_{CP}({\Xi }_c^{+}\to p{K}^{-}{\pi }^{+})=0$. No such U-spin sum rule exists between $A_{CP}({\Lambda }_c^{+}\to p{K}^{-}{K}^{+})$ and $A_{CP}({\Lambda }_c^{+}\to p{\pi }^{-}{\pi }^{+})$. All of these sum rules are associated with a complete interchange of $d$ and $s$ quarks. Furthermore, there are no U-spin CP asymmetry sum rules which hold to first order U-spin breaking.

    hep-phPRD(2019)·46 citations
21. 21*

    Production and polarization of prompt ${\rm Y}$($n$S) in the improved color evaporation model using the $k_T$-factorization approach

    Vincent Cheung🇺🇸 · Ramona Vogt🇺🇸

    We calculate the polarization of prompt ${\rm Y}$($n$S) production in the improved color evaporation model at leading order employing the $k_T$-factorization approach. We present the polarization parameter ${\lambda }_{\vartheta }$ of prompt ${\rm Y}$($n$S) as a function of transverse momentum in $p+p$ and $p+\bar{p}$ collisions to compare with data in the helicity, Collins-Soper and Gottfried-Jackson frames. We also present calculations of the bottomonium production cross sections as a function of transverse momentum and rapidity. This is the first $p_T$-dependent calculation of bottomonium production and polarization in the improved color evaporation model. We find agreement with both bottomonium cross sections and polarization measurements.

    hep-phPRD(2019)·29 citations
22. 22*

    Cornell Model Calibration with NRQCD at N${}^3$LO

    Pablo G. Ortega🇪🇸 · Vicent Mateu🇪🇸 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸

    The typical binding energy of heavy hadron spectroscopy makes the system accessible to perturbative calculations in terms of non-relativistic QCD. Within NRQCD the predictions of heavy quarkonium energy levels rely on the accurate description of the static QCD potential $V_{\mathrm{QCD}}(r)$. Historically, heavy quarkonium spectroscopy was studied using phenomenological approaches such as the Cornell model $V_{\mathrm{Cornell}}=-\kappa /r+\sigma r$, which assumes a short-distance dominant Coulomb potential plus a liner rising potential that emerges at long distances. Such model works reasonably well in describing the charmonium and bottomonium spectroscopy. However, even when there are physically-motivated arguments for the construction of the Cornell model, there is no conection a priori with QCD parameters. Based on a previous work on heavy meson spectroscopy, we calibrate the Cornell model with NRQCD predictions for the lowest lying bottomonium states at N${}^3$LO, in which the bottom mass is varied within a wide range. We show that the Cornell model mass parameter can be identified with the low-scale short-distance MSR mass at the scale $R=1$ GeV. This identification holds for any value of ${\alpha }_s$ or the bottom mass. For moderate values of $r$, the NRQCD and Cornell static potentials are in head-on agreement when switching the pole mass to the MSR scheme, which allows to simultaneously cancel the renormalon and sum up large logarithms.

    hep-phPoS(2018)·2 citations
23. 23*

    Domain walls in high-T SU(N) super Yang-Mills theory and QCD(adj)

    Mohamed M. Anber🇺🇸 · Erich Poppitz🇨🇦

    We study the domain walls in hot $4$-D $SU(N)$ super Yang-Mills theory and QCD(adj), with $n_f$ Weyl flavors. We find that the $k$-wall worldvolume theory is $2$-D QCD with gauge group $SU(N-k)\times SU(k)\times U(1)$ and Dirac fermions charged under $U(1)$ and transforming in the bi-fundamental representation of the nonabelian factors. We show that the DW theory has a $1$-form ${\mathbb{Z}}_N^{(1)}$ center symmetry and a $0$-form ${\mathbb{Z}}_{2N{n}_f}^{d\chi }$ discrete chiral symmetry, with a mixed 't Hooft anomaly consistent with bulk/wall anomaly inflow. We argue that ${\mathbb{Z}}_N^{(1)}$ is broken on the wall, and hence, Wilson loops obey the perimeter law. The breaking of the worldvolume center symmetry implies that bulk $p$-strings can end on the wall, a phenomenon first discovered using string-theoretic constructions. We invoke $2$-D bosonization and gauged Wess-Zumino-Witten models to suggest that ${\mathbb{Z}}_{2N{n}_f}^{d\chi }$ is also broken in the IR, which implies that the $0$-form/$1$-form mixed 't Hooft anomaly in the gapped $k$-wall theory is saturated by a topological quantum field theory. We also find interesting parallels between the physics of high-temperature domain walls studied here and domain walls between chiral symmetry breaking vacua in the zero temperature phase of the theory (studied earlier in the semiclassically calculable small spatial circle regime), arising from the similar mode of saturation of the relevant 't Hooft anomalies.

    ↳ hep-thhep-lathep-phJHEP(2019)·56 citations
24. 24*

    Hadron yields and fluctuations at the CERN Super Proton Synchrotron: system size dependence from Pb+Pb to p+p collisions

    A. Motornenko🇩🇪 · V.V. Begun🇵🇱 · V. Vovchenko🇩🇪 · M.I. Gorenstein🇺🇦 · H. Stoecker🇩🇪

    The kaon to pion ratio $K^{+}/{\pi }^{+}$ and the scaled variance ${\omega }^{-}$ for fluctuations of negatively charged particles are studied within the statistical hadron resonance gas (HRG) model and the Ultra relativistic Quantum Molecular Dynamics (UrQMD) transport model. The calculations are done for p+p, Be+Be, Ar+Sc, and Pb+Pb collisions at the CERN Super Proton Synchrotron energy range to reveal the system size dependence of hadron production. For the HRG calculations the canonical ensemble is imposed for all conserved charges. In the UrQMD simulations the centrality selection in nucleus-nucleus collisions is done by calculating the forward energy $E_{\mathrm{F}}$ deposited in the Projectile Spectator Detector, and the acceptance maps of the NA61/SHINE detectors are used. A comparison of the HRG and UrQMD results with the data of the NA61/SHINE Collaboration is done. To understand a difference of the event-by-event fluctuations in p+p and heavy ion collisions the centrality selection procedure in the sample of all inelastic p+p events is proposed and analyzed within the UrQMD simulations.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2019)·21 citations
25. 25*

    $K\pi$ scattering and the $K^{\ast }(892)$ resonance in 2+1 flavor QCD

    Gumaro Rendon🇺🇸 · Luka Leskovec🇺🇸 · Stefan Meinel🇺🇸 · John Negele🇺🇸 · Srijit Paul🇨🇾 · Marcus Petschlies🇩🇪 · Andrew Pochinsky🇺🇸 · Giorgio Silvi🇩🇪 · Sergey Syritsyn🇺🇸

    In this project, we will compute the form factors relevant for $B\to K^{\ast }(\to K\pi ){\ell }^{+}{\ell }^{-}$ decays. To map the finite-volume matrix elements computed on the lattice to the infinite-volume $B\to K\pi$ matrix elements, the $K\pi$ scattering amplitude needs to be determined using Lüscher's method. Here we present preliminary results from our calculations with $2+1$ flavors of dynamical clover fermions. We extract the $P$-wave scattering phase shifts and determine the $K^{\ast }$ resonance mass and the $K^{\ast }K\pi$ coupling for two different ensembles with pion masses of $317(2)$ and $178(2)$ MeV.

    ↳ hep-lathep-phPoS(2019)·9 citations
26. 26*

    QCD gluon vertices from the string-inspired formalism

    Naser Ahmadiniaz🇰🇷 · Christian Schubert🇲🇽

    The Bern-Kosower formalism, developed around 1990 as a novel way of obtaining QCD amplitudes as the limit of infinite string tension of the corresponding string amplitudes, was originally designed as an on-shell formalism. Building on early work by Strassler, the authors have recently shown that this `string-inspired formalism' is extremely efficient also as a tool for the study of off-shell amplitudes in QCD, and in particular for achieving compact form factor decompositions of the N-gluon vertices. Among other things, this formalism allows one to achieve a manifestly gauge invariant decomposition of these vertices by way of integration-by-parts, rather than the usual tedious analysis of the nonabelian off-shell Ward identities, and to combine the spin zero, half and one cases. Here, we will provide a summary of the method, as well as its application to the three- and four-gluon vertices.

    ↳ hep-thhep-phIJMPE(2016)·21 citations
27. 27*

    Bounds from ISW-galaxy cross-correlations on generalized covariant Galileon models

    Francesco Giacomello🇮🇹 · Antonio De Felice🇯🇵 · Stefano Ansoldi🇮🇹

    Several modified cosmological models exist, which also try to address the tensions between data and predictions of the $\Lambda$-CDM model. Galileon models are particular scalar tensor theories that represent one such possibilities. While it is commonly understood that there may be inconsistencies between predictions of some Galileon models and observations, in particular concerning ISW-galaxy cross-correlations, there is no proof yet that these models are completely ruled out. Indeed, by using a specific background in the generalized covariant Galileon theory known as the the tracker solution, here we show that, after imposing all standard theoretical stability constraints, it is still possible to identify a region in the parameter space of the model that allows for positive ISW-galaxy cross-correlations. By a physical interpretation in terms of a chi-square analysis, we confirm the expectation that in this viable region the predictions of generalized covariant Galileon theory on the tracker solution background have higher likelihood when they approach the physics of the $\Lambda$-CDM model.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·16 citations
28. 28*

    Constraining the photon coupling of ultra-light dark-matter axion-like particles by polarization variations of parsec-scale jets in active galaxies

    M.M. Ivanov🇷🇺 · Y.Y. Kovalev🇷🇺 · M.L. Lister🇺🇸 · A.G. Panin🇷🇺 · A.B. Pushkarev🇺🇦 · T. Savolainen🇫🇮 · S.V. Troitsky🇷🇺

    Ultra-light dark matter may consist of axion-like particles with masses below 10^(-19) eV. Two-photon interactions of these particles affect the polarization of radiation propagating through the dark matter. Coherent oscillations of the Bose condensate of the particles induce periodic changes in the plane of polarisation of emission passing through the condensate. We estimate this effect and analyze MOJAVE VLBA polarization observations of bright downstream features in the parsec-scale jets of active galaxies. Through the non-observation of periodic polarization changes, we are able to constrain the photon coupling of the ultra-light dark-matter axion-like particles at the level of <~ 10^(-12)/GeV for masses between ~5*10^(-23) eV and ~1.2*10^(-21) eV.

    ↳ astro-ph.COhep-phhep-thJCAP(2019)·74 citations
29. 29*

    Precision computation of hybrid static potentials in SU(3) lattice gauge theory

    Stefano Capitani🇩🇪 · Owe Philipsen🇩🇪 · Christian Reisinger🇩🇪 · Carolin Riehl🇩🇪 · Marc Wagner🇩🇪

    We perform a precision computation of hybrid static potentials with quantum numbers ${\Lambda }_{\eta }^{ϵ}={\Sigma }_g^{-},{\Sigma }_u^{+},{\Sigma }_u^{-},{\Pi }_g,{\Pi }_u,{\Delta }_g,{\Delta }_u$ using SU(3) lattice gauge theory. The resulting potentials are used to estimate masses of heavy $\bar{c}c$ and $\bar{b}b$ hybrid mesons in the Born-Oppenheimer approximation. Part of the lattice gauge theory computation, which we discuss in detail, is an extensive optimization of hybrid static potential creation operators. The resulting optimized operators are expected to be essential for future projects concerning the computation of 3-point functions as e.g. needed to study spin corrections, decays or the gluon distribution of heavy hybrid mesons.

    ↳ hep-lathep-phPRD(2019)·87 citations
30. 30*

    Steepest growth of the power spectrum and primordial black holes

    Christian T. Byrnes🇬🇧 · Philippa S. Cole🇬🇧 · Subodh P. Patil🇩🇰

    We derive analytic bounds on the shape of the primordial power spectrum in the context of single-field inflation. In particular, the steepest possible growth has a spectral index of $n_s-1=4$ once transients have died down. Its primary implication is that any constraint on the power spectrum at a particular scale can be extrapolated to an upper bound over an extended range of scales. This is important for models which generate relics due to an enhanced amplitude of the primordial scalar perturbations, such as primordial black holes. In order to generate them, the power spectrum needs to grow many orders of magnitude larger than its observed value on CMB scales - typically achieved through a phase of ultra slow-roll inflation - and is thus subject to additional constraints at small scales. We plot all relevant constraints including CMB spectral distortions and gravitational waves sourced by scalar perturbations at second order. We show how this limits the allowed mass of PBHs, especially for the large masses of interest following recent detections by LIGO and prospects for constraining them further with future observations. We show that any transition from approximately constant $ϵ$ slow-roll inflation to a phase where the power spectrum rapidly rises necessarily implies an intervening dip in power. We also show how to reconstruct a potential that can reproduce an arbitrary time-varying $ϵ$, offering a complementary perspective on how ultra slow-roll can be achieved.

    ↳ astro-ph.COhep-phhep-thJCAP(2019)·418 citations
31. 31*

    Constraints on non-resonant photon-axion conversion from the Planck satellite data

    Suvodip Mukherjee🇫🇷 · Rishi Khatri🇮🇳 · Benjamin D. Wandelt🇫🇷

    The non-resonant conversion of Cosmic Microwave Background (CMB) photons into scalar as well as light pseudoscalar particles such as axion-like particles (ALPs) in the presence of turbulent magnetic fields can cause a unique, spatially fluctuating spectral distortion in the CMB. We use the publicly available Planck temperature maps for the frequency channels (70-545 GHz) to obtain the first ALP distortion map using $45\%$ clean part of the sky. The $95^{th}$ percentile upper limit on the RMS fluctuation of ALP distortions from the cleanest part of the CMB sky at $15$ arcmin angular resolution is $18.5\times 10^{-6}$. The RMS fluctuation in the distortion map is also consistent with different combinations of frequency channels and sky-fractions.

    ↳ astro-ph.COhep-phhep-thJCAP(2019)·26 citations
32. 32*

    Neutrino flavour as a test of the explosion mechanism of core-collapse supernovae

    Nitsan Bar🇮🇱 · Kfir Blum🇮🇱 · Guido D'Amico🇨🇭

    We study the ratio of neutrino-proton elastic scattering to inverse beta decay event counts, measurable in a scintillation detector like JUNO, as a key observable for identifying the explosion mechanism of a galactic core-collapse supernova. If the supernova is not powered by the core but rather, e.g., by collapse-induced thermonuclear explosion, then a prolonged period of accretion-dominated neutrino luminosity is predicted. Using 1D numerical simulations, we show that the distinct resulting flavour composition of the neutrino burst can be tested in JUNO with high significance, overcoming theoretical uncertainties in the progenitor star profile and equation of state.

    ↳ astro-ph.HEhep-phPRD(2019)·7 citations
33. 33*

    Why is quantum gravity so difficult (compared to QCD)?

    Hidenori Fukaya🇯🇵

    Gravity is difficult to quantize. This is a well-known fact but its reason is given simply by non-renormalizability of the Newton constant and little is discussed why among many quantum gauge theories, gravity is special. In this essay we try to treat the gravity as one of many gauge theories, and discuss how it is special and why it is difficult to quantize.

    ↳ hep-thgr-qchep-lathep-phSoryushiron Kenkyu(2016)·2 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.