Mon·Jan 22, 2018Monday·January 22, 2018

1. 01*

   Renormalization scheme and gauge (in)dependence of the generalized Crewther relation: what are the real grounds of the $\beta$-factorization property?

   A. V. Garkusha🇷🇺 · A. L. Kataev🇷🇺 · V. S. Molokoedov🇷🇺

   The scheme and gauge dependence of the factorization property of the RG $\beta$-function in the $SU(N_c)$ QCD generalized Crewther relation (GCR), which connects the non-singlet contributions to the Adler and Bjorken polarized sum rule functions, is investigated at the $\mathcal{O}(a_s^4)$ level. In the gauge-invariant $\overline{\mathrm{MS}}$-scheme this property holds at least at this order. To study whether this property is true in all gauge-invariant schemes, we consider the $\mathrm{MS}$-like schemes in QCD and the QED-limit of the GCR in the $\overline{\mathrm{MS}}$-scheme and in the $\mathrm{MOM}$ and the $\mathrm{OS}$ schemes. In these schemes we confirm the existence of the $\beta$-function factorization in the QCD and QED variants of the GCR. The problem of the possible $\beta$-factorization in the gauge-dependent renormalization schemes in QCD is studied. We consider the gauge non-invariant $\mathrm{mMOM}$ and $\mathrm{MOMgggg}$-schemes and demonstrate that in the $\mathrm{mMOM}$ scheme at the $\mathcal{O}(a_s^3)$ level the $\beta$-factorization is valid for three values of the gauge parameter $\xi$ only, namely for $\xi =-3,-1$ and $\xi =0$. In the $\mathcal{O}(a_s^4)$ order of PT it remains valid only for case of the Landau gauge $\xi =0$. The consideration of these two schemes for the QCD GCR allows us to conclude that the factorization of RG $\beta$-function will always be implemented in any $\mathrm{MOM}$-like schemes with linear covariant gauge at $\xi =0$ and $\xi =-3$ at the $\mathcal{O}(a_s^3)$ level. It is demonstrated that if factorization property for the $\mathrm{MS}$-like schemes is true in all orders of PT, as theoretically indicated, then the factorization will also occur in the arbitrary $\mathrm{MOM}$-like scheme in the Landau gauge in all orders of PT as well.

   hep-phhep-lathep-thJHEP(2018)·26 citations
2. 02*

   Axion-plasmon polaritons in strongly magnetized plasmas

   H. Terças🇵🇹 · J. D. Rodrigues🇵🇹 · J. T. Mendonça🇵🇹

   Axions are hypothetical particles related to the violation of the charge-parity symmetry, being the most prone candidates for dark matter. Multiple attempts to prove their existence are currently performed in different physical systems. Here, we anticipate the possibility of the axions coupling to the electrostatic (Langmuir) modes of a strongly magnetized plasma, by showing that a new quasi-particle can be defined, the axion-plasmon polariton. The excitation of axions can be inferred from the pronounced modification of the dispersion relation of the Langmuir waves, a feature that we estimate to be accessible in state-of-the-art plasma-based experiments. We further show that, under extreme density and magnetic field conditions (e.g. at the interior of dense neutron stars), the axion-plasmon polariton becomes dynamically unstable, similarly to the case of the Jeans instability occurring in self-gravitating fluids. This latter result anticipates a plausible mechanism to the creation of axion-like particles in the universe.

   hep-phphysics.plasm-phPRL(2018)·47 citations
3. 03*

   Hadron tomography and its application to gravitational radii of hadrons

   S. Kumano🇯🇵 · Qin-Tao Song🇯🇵 · O. V. Teryaev🇷🇺

   Hadron tomography has been investigated by three-dimensional structure functions, such as generalized parton distributions (GPDs) and generalized distribution amplitudes (GDAs). The GDAs are $s$-$t$ crossed quantities of the GPDs, and both functions probe gravitational form factors for hadrons. We determined the pion GDAs by analyzing Belle data on the differential cross section for the two-photon process ${\gamma }^{\ast }\gamma \to {\pi }^0{\pi }^0$. From the determined GDAs, we calculated timelike gravitational form factors of the pion and they were converted to the spacelike form factors by using the dispersion relation. These gravitational form factors ${\Theta }_1$ and ${\Theta }_2$ indicate mechanical (pressure, shear force) and gravitational-mass (or energy) distributions, respectively. Then, gravitational radii are calculated for the pion from the form factors, and they are compared with the pion charge radius. We explain that the new field of gravitational physics can be developed in the microscopic level of quarks and gluons.

   hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2018)·2 citations
4. 04*

   On phenomenological study of the solution of nonlinear GLR-MQ evolution equation beyond leading order

   M. Lalung🇮🇳 · P. Phukan🇮🇳 · J. K. Sarma🇮🇳

   We present a phenomenological study of the small-x behaviour of gluon distribution function $G(x,Q^2)$ at next-to-leading order (NLO) and next-to-next-to-leading order(NNLO) in light of the nonlinear Gribov-Ryskin-Levin-Mueller-Qiu (GLR-MQ)evolution equation by keeping the transverse size of the gluons ($\sim 1/Q$) fixed. We consider the NLO and NNLO corrections, of the gluon-gluon spitting function $P_{gg}(z)$ and strong coupling constant ${\alpha }_s(Q^2)$. We have suggested semi-analytical solutions based on Regge like ansatz of gluon density $G(x,Q^2)$, which are supposed to be valid in the moderate range of photon virtuality$(Q^2)$ and at small Bjorken variable$(x)$. The study of the effects of nonlinearities that arise due to gluon recombination effects at small-x is very interesting, which eventually tames down the unusual growth of gluon densities towards small-x as predicted by the linear DGLAP evolution equation.

   hep-phNPA(2019)·9 citations
5. 05*

   Predictions for the Dirac CP-Violating Phase from Sum Rules

   Luis A. Delgadillo🇲🇽 · Lisa L. Everett🇺🇸 · Raymundo Ramos🇹🇼 · Alexander J. Stuart🇲🇽

   We explore the implications of recent results relating the Dirac CP-violating phase to predicted and measured leptonic mixing angles within a standard set of theoretical scenarios in which charged lepton corrections are responsible for generating a non-zero value of the reactor mixing angle. We employ a full set of leptonic sum rules as required by the unitarity of the lepton mixing matrix, which can be reduced to predictions for the observable mixing angles and the Dirac CP-violating phase in terms of model parameters. These sum rules are investigated within a given set of theoretical scenarios for the neutrino sector diagonalization matrix for several known classes of charged lepton corrections. The results provide explicit maps of the allowed model parameter space within each given scenario and assumed form of charged lepton perturbations.

   hep-phPRD(2018)·16 citations
6. 06*

   Jet cross sections and transverse momentum distributions with NNLOJET

   T. Gehrmann🇨🇭 · X. Chen🇨🇭 · J. Cruz-Martinez🇬🇧 · J.R. Currie🇬🇧 · E.W.N. Glover🇬🇧 · T.A. Morgan🇬🇧 · J. Niehues🇬🇧 · D.M. Walker🇬🇧 · R. Gauld🇨🇭 · A. Gehrmann-De Ridder🇨🇭 · A. Huss🇨🇭 · Joao Pires🇵🇹

   This talk discusses recent results for next-to-next-to-leading order (NNLO) QCD corrections to jet cross sections and transverse momentum distributions. The results are obtained in the NNLOJET code framework, which provides an implementation of the antenna subtraction method for the handling of infrared singular contributions at NNLO. We briefly describe the NNLOJET implementation, with particular emphasis on the construction of the real radiation phase space, which is tailored to ensure stability in all infrared sensitive regions.

   hep-phPoS(2018)·75 citations
7. 07*

   Towards analytic local sector subtraction at NNLO

   Lorenzo Magnea🇮🇹 · Ezio Maina🇮🇹 · Paolo Torrielli🇮🇹 · Sandro Uccirati🇮🇹

   A new method for local subtraction at next-to-next-to-leading order in QCD is sketched, attempting to conjugate the minimal counterterm structure arising from a sector partition of the radiation phase space with the simplifications following from analytic integration of the counterterms.

   hep-phPoS(2018)·6 citations
8. 08*

   Factorization and subtraction

   Lorenzo Magnea🇮🇹 · Ezio Maina🇮🇹 · Paolo Torrielli🇮🇹 · Sandro Uccirati🇮🇹

   We explore the connection between the factorisation of virtual corrections to multi-particle massless gauge theory amplitudes and the problem of subtraction at NNLO and beyond. Taking inspiration from virtual factorisation, we provide a set of definitions for local soft and collinear counterterms, expressed in terms of matrix elements of operators involving fields and Wilson lines, and valid to all orders in perturbation theory. We hope that the connection between factorisation and subtraction will help in the construction of minimal, stable, and efficient subtraction algorithms, taking maximal advantage of existing analytic information.

   hep-phPoS(2018)·4 citations
9. 09*

   Model-Independent ${\bar{\nu }}_e$ Short-Baseline Oscillations from Reactor Spectral Ratios

   S. Gariazzo🇪🇸 · C. Giunti🇮🇹 · M. Laveder🇮🇹 · Y.F. Li🇨🇳

   We consider the ratio of the spectra measured in the DANSS neutrino experiment at 12.7 and 10.7~m from a nuclear reactor. These data give a new model-independent indication in favor of short-baseline ${\bar{\nu }}_e$ oscillations which reinforce the model-independent indication found in the late 2016 in the NEOS experiment. The combined analysis of the NEOS and DANSS spectral ratios in the framework of 3+1 active-sterile neutrino mixing favor short-baseline ${\bar{\nu }}_e$ oscillations with a statistical significance of $3.7\sigma$. The two mixing parameters ${\sin }^{2}2{\vartheta }_{ee}$ and $\Delta m_{41}^2$ are constrained at $2\sigma$ in a narrow-$\Delta m_{41}^2$ island at $\Delta m_{41}^2\simeq 1.3{\text{eV}}^2$, with ${\sin }^{2}2{\vartheta }_{ee}=0.049\pm 0.023$ ($2\sigma$). We discuss the implications of the model-independent NEOS+DANSS analysis for the reactor and Gallium anomalies. The NEOS+DANSS model-independent determination of short-baseline ${\bar{\nu }}_e$ oscillations allows us to analyze the reactor rates without assumptions on the values of the main reactor antineutrino fluxes and the data of the Gallium source experiments with free detector efficiencies. The corrections to the reactor neutrino fluxes and the Gallium detector efficiencies are obtained from the fit of the data. In particular, we confirm the indication in favor of the need for a recalculation of the ${}^{235}\text{U}$ reactor antineutrino flux found in previous studies assuming the absence of neutrino oscillations.

   hep-phhep-exnucl-exPLB(2018)·90 citations
10. 10*

    Investigating Local Parity Violation in Heavy-Ion Collisions Using Lambda Helicity

    L. Evan Finch🇺🇸 · Stephen J. Murray🇺🇸

    We propose the measurement of net $\Lambda$ and $\bar{\Lambda }$ helicity, correlated event-by-event with the magnitude and sign of charge separation along the event's magnetic field direction, as a probe to investigate the Chiral Magnetic Effect in Heavy-Ion Collisions. With a simple simulation model of heavy-ion events that includes effects of Local Parity Violation, we estimate the experimental correlation signal that could be expected at RHIC given the results of previous measurements that are sensitive to the CME.

    hep-phnucl-exPRC(2017)·11 citations
11. 11*

    The fate of the Littlest Higgs Model with T-parity under 13 TeV LHC Data

    Daniel Dercks🇩🇪 · Gudrid Moortgat-Pick🇩🇪 · Jurgen Reuter🇩🇪 · So Young Shim🇩🇪

    We exploit all LHC available Run 2 data at center-of-mass energies of 8 and 13 TeV for searches for physics beyond the Standard Model. We scrutinize the allowed parameter space of Little Higgs models with the concrete symmetry of T-parity by providing comprehensive analyses of all relevant production channels of heavy vectors, top partners, heavy quarks and heavy leptons and all phenomenologically relevant decay channels. Constraints on the model will be derived from the signatures of jets and missing energy or leptons and missing energy. Besides the symmetric case, we also study the case of T-parity violation. Furthermore, we give an extrapolation to the LHC high-luminosity phase at 14 TeV as well.

    hep-phhep-exJHEP(2018)·24 citations
12. 12*

    Top quark modelling in POWHEG BOX

    Tomáš Ježo🇨🇭

    We review recent theoretical improvements of Monte Carlo event generators for top-quark pair production and decay at the LHC based on the POWHEG method. We present an event generator that implements spin correlations and off-shell effects in top-decay chains described in terms of exact matrix elements for $pp\to {\ell }^{+}{\nu }_{\ell }{l}^{-}{\bar{\nu }}_{l}b\bar{b}$ at order ${\alpha }^4{\alpha }_s^2$, including full NLO QCD corrections and interference effects with single-top and non-resonant topologies yielding to the same final state. We then compare its predictions to previous generators that implement NLO corrections only in the top-pair production dynamics. We consider the mass distributions of the $W{j}_{\mathrm{B}}$ and $\ell j_{\mathrm{B}}$ systems, proxies for direct top-mass determinations, and jet-vetoed cross section, a probe of the $Wt$ single top contribution.

    hep-phhep-ex0 citations
13. 13*

    Compact Perturbative Expressions for Neutrino Oscillations in Matter: II

    Peter B. Denton · Hisakazu Minakata · Stephen J. Parke

    In this paper we rewrite the neutrino mixing angles and mass squared differences in matter given, in our original paper, in a notation that is more conventional for the reader. Replacing the usual neutrino mixing angles and mass squared differences in the expressions for the vacuum oscillation probabilities with these matter mixing angles and mass squared differences gives an excellent approximation to the oscillation probabilities in matter. Comparisons for T2K, NOvA, T2HKK and DUNE are also given for neutrinos and anti-neutrinos, disappearance and appearance channels, normal ordering and inverted ordering.

    hep-phhep-exJHEP(2018)·35 citations
14. 14*

    Probing the Seesaw Mechanism and Leptogenesis with the International Linear Collider

    Stefan Antusch🇨🇭 · Eros Cazzato🇨🇭 · Marco Drewes🇧🇪 · Oliver Fischer🇩🇪 · Bjorn Garbrecht🇩🇪 · Dario Gueter🇩🇪 · Juraj Klaric🇩🇪

    We investigate the potential of the International Linear Collider (ILC) to probe the mechanisms of neutrino mass generation and leptogenesis within the minimal seesaw model. Our results can also be used as an estimate for the potential of a Compact Linear Collider (CLIC). We find that heavy sterile neutrinos that simultaneously explain both, the observed light neutrino oscillations and the baryon asymmetry of the universe, can be found in displaced vertex searches at ILC. We further study the precision at which the flavour-dependent active-sterile mixing angles can be measured. The measurement of the ratios of these mixing angles, and potentially also of the heavy neutrino mass splitting, can test whether minimal type I seesaw models are the origin of the light neutrino masses, and it can be a first step towards probing leptogenesis as the mechanism of baryogenesis. Our results show that the ILC can be used as a discovery machine for New Physics in feebly coupled sectors that can address fundamental questions in particle physics and cosmology.

    hep-phastro-ph.COhep-ex6 citations
15. 15*

    Searches for vector-like quarks at future colliders and implications for composite Higgs models with dark matter

    Mikael Chala🇬🇧 · Ramona Gröber🇬🇧 · Michael Spannowsky🇬🇧

    Many composite Higgs models predict the existence of vector-like quarks with masses outside the reach of the LHC, e.g. $m_Q\gtrsim 2$ TeV, in particular if these models contain a dark matter candidate. In such models the mass of the new resonances is bounded from above to satisfy the constraint from the observed relic density. We therefore develop new strategies to search for vector-like quarks at a future $100$ TeV collider and evaluate what masses and interactions can be probed. We find that masses as large as $\sim 6.4$ ($\sim 9$) TeV can be tested if the fermionic resonances decay into Standard Model (dark matter) particles. We also discuss the complementarity of dark matter searches, showing that most of the parameter space can be closed. On balance, this study motivates further the consideration of a higher-energy hadron collider for a next generation of facilities.

    hep-phhep-exJHEP(2018)·48 citations
16. 16*

    Two clock transitions in neutral Yb for the highest sensitivity to variations of the fine-structure constant

    M. S. Safronova🇺🇸 · S. G. Porsev🇺🇸 · Christian Sanner🇺🇸 · Jun Ye🇺🇸

    We propose a new frequency standard based on a $4f^{14}6s6p{}^3{P}_0-4f^{13}6s^{2}5d(J=2)$ transition in neutral Yb. This transition has a potential for high stability and accuracy and the advantage of the highest sensitivity among atomic clocks to variation of the fine-structure constant $\alpha$. We find its dimensionless $\alpha$-variation enhancement factor to be $K=-15$, in comparison to the most sensitive current clock (Yb${}^{+}$ E3, $K=-6$), and it is 18 times larger than in any neutral-atomic clocks (Hg, $K=0.8$). Combined with the unprecedented stability of an optical lattice clock for neutral atoms, this high sensitivity opens new perspectives for searches for ultralight dark matter and for tests of theories beyond the standard model of elementary particles. Moreover, together with the well-established ${}^1{S}_0-{}^3{P}_0$ transition one will have two clock transitions operating in neutral Yb, whose interleaved interrogations may further reduce systematic uncertainties of such clock-comparison experiments.

    ↳ physics.atom-phhep-phphysics.opticsquant-phPRL(2018)·67 citations
17. 17*

    Kaon Structure in the confining Nambu-Jona-Lasino Model

    Parada. T. P. Hutauruk🇰🇷

    The elastic electromagnetic form factors in the space-like region and valence quark distribution functions for the K+ meson are calculated using the confining Nambu-Jona-Lasinio model with the help of the proper-time regularization scheme, which simulates quark confinement. In this model framework, the dynamics information on the nonperturbative aspects is obtained from quark propagators and bound state amplitudes via Bethe-Salpeter equations. We found that the results on the kaon form factors and valence quark distribution functions are qualitatively in excellent agreement with the existing kaon data as well as the perturbation QCD prediction at higher $Q^2$.

    ↳ nucl-thhep-ph6 citations
18. 18*

    On the convergence of the chiral expansion for the baryon ground-state masses

    M.F.M. Lutz🇩🇪 · Yonggoo Heo🇩🇪 · Xiao-Yu Guo🇩🇪

    We study the chiral expansion of the baryon octet and decuplet masses in the isospin limit. It is illustrated that a chiral expansion of the one-loop contributions is rapidly converging up to quark masses that generously encompasses the mass of the physical strange quark. We express the successive orders in terms of physical meson and baryon masses. In addition, owing to specific correlations amongst the chiral moments, we suggest a reordering of terms that make the convergence properties more manifest. Explicit expressions up to chiral order five are derived for all baryon masses at the one-loop level. The baryon masses obtained do not depend on the renormalization scale. Our scheme is tested against QCD lattice data, where the low-energy parameters are systematically correlated by large-Nc sum rules. A reproduction of the baryon masses from PACS-CS, LHPC, HSC, NPLQCD, QCDSF-UKQCD and ETMC is achieved for ensembles with pion and kaon masses smaller than 600 MeV. Predictions for baryon masses on ensembles from CLS as well as all low-energy constants that enter the baryon masses at N3LO are made.

    ↳ hep-lathep-phnucl-thNPA(2018)·42 citations
19. 19*

    On the Cosmological Frame Problem

    Sotirios Karamitsos🇬🇧 · Apostolos Pilaftsis🇬🇧

    We introduce a fully-frame covariant formalism for inflation by taking into account conformal transformations in addition to field reparametrizations. We begin by providing a brief overview of frame problems in the history of science before outlining the crux of the frame problem in inflationary cosmology. After introducing the concept of frame tensors in curved field space, we demonstrate how the quantum perturbations and the observables sourced by them can be made frame covariant. We then specialize to two-field models, examining the impact of isocurvature effects on the inflationary observables in a frame-covariant manner. We study the phenomenology of two particular models, a minimal polynomial model and a nonminimal model inspired by Higgs inflation. We observe that in the latter scenario, isocurvature effects are greatly enhanced. Moving beyond the tree-level approximation, we outline how our approach may be extended at the quantum level through the Vilkovisky--De Witt formalism and the generalization of frame tensors to configuration space, leading to a fully frame-invariant effective action. Finally, we summarize our findings and present possible future directions of research on the topic of frame covariance.

    ↳ hep-thgr-qchep-phPoS(2018)·26 citations
20. 20*

    Acceleration of ultrahigh-energy cosmic rays in starburst superwinds

    Luis Alfredo Anchordoqui🇺🇸

    The sources of ultrahigh-energy cosmic rays (UHECRs) have been stubbornly elusive. However, the latest report of the Pierre Auger Observatory provides a compelling indication for a possible correlation between the arrival directions of UHECRs and nearby starburst galaxies. We argue that if starbursts are sources of UHECRs, then particle acceleration in the large-scale terminal shock of the superwind that flows from the starburst engine represents the best known concept model in the market. We investigate new constraints on the model and readjust free parameters accordingly. We show that UHECR acceleration above about 10^{11} GeV remains consistent with observation. We also show that the model could accommodate hard source spectra as required by Auger data. We demonstrate how neutrino emission can be used as a discriminator among acceleration models.

    ↳ astro-ph.HEhep-phPRD(2018)·75 citations
21. 21*

    Equilibrium electric current of massive electrons with anomalous magnetic moments induced by a magnetic field and the electroweak interaction with matter

    Maxim Dvornikov (1 and 2) ((1) IZMIRAN, (2) Tomsk State University)🇷🇺

    We study the possibility of the existence of the electric current, formed by massive electrons and positrons, flowing along an external magnetic field. The charged fermions are supposed to have nonzero anomalous magnetic moments and electroweakly interact with background matter. The expression for the current is obtained on the basis of the exact solution of the Dirac equation in the corresponding external fields. We demonstrate that, in the state of equilibrium, such a current is vanishing for any characteristics of the electron-positron plasma as well as the external fields. Our results are compared with the recent findings of other authors.

    ↳ physics.plasm-phhep-phhep-thInt.J.Mod.Phys.A(2018)·3 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.