Mon·Jun 4, 2018Monday·June 4, 2018

1. 01*

   The hyperbolic rotation group of neutral meson mixing and $CP$ violation

   Jordi Garra Ticó🇬🇧

   Neutral meson mixing and $CP$ violation are very well known weak processes that involve decays to meson states that are, in general, a superposition of flavor eigenstates. This paper describes a mathematical interpretation of the time-dependent mixing amplitudes as a complex hyperbolic rotation of the time evolution of those amplitudes without mixing, which involves a Lie group $SO(1,1,\mathbb{C})$. This allows a geometric interpretation of mixing as a curve into the $SO(1,1,\mathbb{C})$ manifold, parameterized with the proper decay time, where $CP$ violation is the image of this curve at $t=0$. To show the power of this new interpretation, it is applied to several aspects of the measurement of the CKM angle $\gamma$ in $B$ decays to neutral $D$ mesons. On one hand, the charm mixing correction on the $CPV$ parameters is derived. On the other hand, it is shown how the expressions used in GLW, ADS and GGSZ methods are affected by charm mixing. Finally, the complete example with both charm and strange mixing and $CPV$ is described.

   hep-ph0 citations
2. 02*

   Perspectives to find heavy neutrinos with NA62

   Marco Drewes🇧🇪 · Jan Hajer🇧🇪 · Juraj Klaric🇩🇪 · Gaia Lanfranchi🇮🇹

   The sensitivity of beam dump experiments to heavy neutrinos depends on the relative size of their mixings with the lepton flavours in the Standard Model. We study the impact of present neutrino oscillation data on these mixing angles in the minimal type I seesaw model. We find that current data significantly constrains the allowed heavy neutrino flavour mixing patterns. Based on this, we discuss the implications for the sensitivity of the NA62 experiment to heavy neutrinos when operated in the beam dump mode. We find that NA62 is currently the most sensitive experiment in the world for heavy neutrino masses between that of the kaon and the $D$-mesons. The sensitivity can vary by almost two orders of magnitude if the heavy neutrinos exclusively couple to the tau flavour, but depends only comparably weakly on the flavour mixing pattern within the parameter range preferred by light neutrino oscillation data.

   hep-phhep-ex9 citations
3. 03*

   Numerically Computing QCD Laplace Sum-Rules Using pySecDec

   S. Esau🇨🇦 · D. Harnett🇨🇦

   pySecDec is a program that numerically calculates dimensionally regularized integrals. We use pySecDec to compute QCD Laplace sum-rules for pseudoscalar (i.e., $J^{PC}=0^{-+}$) charmonium hybrids, and compare the results to sum-rules computed using analytic results for dimensionally regularized integrals. We find that the errors due to the use of numerical integration methods is negligible compared to the uncertainties in the sum-rules stemming from the uncertainties in the parameters of QCD, e.g., the coupling constant, quark masses, and condensate values. Also, we demonstrate that numerical integration methods can be used to calculate finite-energy and Gaussian sum-rules in addition to Laplace sum-rules.

   hep-phEPJA(2019)·3 citations
4. 04*

   $B^0$-${\bar{B}}^0$ mixing: matching to HQET at NNLO

   Andrey G. Grozin🇷🇺 · Thomas Mannel🇩🇪 · Alexei A. Pivovarov🇩🇪

   We compute perturbative matching coefficients to the Heavy Quark Effective Theory representation for the QCD effective local $\Delta B=2$ Hamiltonian that determines the mass difference in $B^0-{\bar{B}}^0$ system of states. We report on the results at NNLO in the strong coupling constant for matching coefficients of two physical operators in HQET. Our results provide the firm confirmation that the recent NLO sum rules analysis of the bag parameter $B_q$ is stable with regard of inclusion of higher order radiative corrections. As a by-product of our calculation we give a fully analytical solution for the one loop QCD-to-HQET matching problem: we present the explicit formulas for the renormalization of four quark operators of the full bases in both QCD and HQET and the expressions for matching coefficients in a closed form.

   hep-phPRD(2018)·21 citations
5. 05*

   Next-to-leading order electroweak corrections to off-shell WWW production at the LHC

   Marek Schönherr🇨🇭

   Triboson processes allow for a measurement of the triple and quartic couplings of the Standard Model gauge bosons, which can be used to constrain anomalous gauge couplings. In this paper we calculate the next-to-leading order electroweak corrections to fully off-shell $W^{-}{W}^{+}{W}^{+}$ production, namely the production of a ${\ell }_1^{-}{\ell }_2^{+}{\ell }_3^{+}{\bar{\nu }}_{{\ell }_1}{\nu }_{{\ell }_2}{\nu }_{{\ell }_3}$ final state with (${\ell }_i=e,\mu$), including all triple, double, single and non resonant topologies and interferences of diagrams with all different vector boson ($W,Z,\gamma$) intermediate states. We find large cancellations of the electroweak correction to the $q\bar{q}$-induced channel, which includes the exchange of virtual electroweak gauge bosons, and photon-induced jet radiation processes. This accidental compensation is found to be strongly phase space and observable dependent. The resulting corrections in a suitably defined fiducial region thus amount to $-2.0\%$, but rise rapidly for other observables.

   hep-phhep-exJHEP(2018)·38 citations
6. 06*

   Thermodynamical properties of strongly interacting matter in a model with explicit chiral symmetry breaking interactions

   J. Moreira🇵🇹 · J. Morais🇵🇹 · B. Hiller🇵🇹 · A. A. Osipov🇷🇺 · A. H. Blin🇵🇹

   We analyse the effects of the light and strange current quark masses on the phase diagram of QCD at finite temperature and vanishing baryonic chemical potential, computing the speed of sound, the trace anomaly of the energy momentum tensor and the fluctuations and correlations of the conserved charges associated to baryonic, electric and strangeness numbers. The framework is a known extension of the three flavor Nambu Jona Lasinio model, which includes the full set of explicit chiral symmetry breaking interactions (ESB) up to the same order in large $N_c$ counting as the 't Hooft flavor mixing terms and eight quark interactions. It is shown that the ESB terms are relevant for the description of a soft region in the system's speed of sound and overall slope behavior of the observables computed. At the same time the role of the 8q interactions gets highlighted. The model extension with the Polyakov loop is considered and the results are compared to lattice QCD data.

   hep-phPRD(2018)·7 citations
7. 07*

   Scalar mesons: fifty years of challenging the quark model

   George Rupp🇵🇹 · Eef van Beveren🇵🇹

   Half a century of work on the light scalar mesons $f_0(500)$, $f_0(980)$, $K_0^{\star }(700)$, and $a_0(980)$ is briefly reviewed. After summarising all light scalar candidates in the Review of Particle Physics since 1963, a selection of different theoretical and phenomenological descriptions is presented, including pure meson-meson models, a tetraquark construction, unitarised quark-meson models, unitarised effective chiral approaches, and a very recent lattice-QCD simulation.

   hep-phActa Phys.Polon.Supp.(2018)·7 citations
8. 08*

   Double heavy quarkonium production in diffractive processes at the Run 2 LHC energy

   C. Brenner Mariotto🇧🇷 · V. P. Goncalves🇧🇷 · R. Palota da Silva🇧🇷

   The double quarkonium production in single and double diffractive processes is investigated considering $pp$ collisions at the Run 2 LHC energy. Using the nonrelativistic QCD (NRQCD) factorization formalism for the quarkonium production and the Resolved Pomeron model to describe the diffractive processes, we estimate the rapidity and transverse momentum dependencies of the cross sections for the $J/\Psi J/\Psi$ and ${\rm Y}{\rm Y}$ production. The contributions of the color-singlet and color-octet channels are estimated and predictions for the total cross sections in the kinematical regions of the LHC experiments are also presented. Our results demonstrate that the double quarkonium production in diffractive processes is not negligible and that its study can be useful to test the underlying assumptions present in the description of the single and double diffractive processes.

   hep-phhep-exPRD(2018)·10 citations
9. 09*

   Assessing Perturbativity and Vacuum Stability in High-Scale Leptogenesis

   Seyda Ipek🇺🇸 · Alexis D. Plascencia🇬🇧 · Jessica Turner🇺🇸

   We consider the requirements that all coupling constants remain perturbative and the electroweak vacuum metastable up to the Planck scale in high-scale thermal leptogenesis, in the context of a type-I seesaw mechanism. We find a large region of the model parameter space that satisfies these conditions in combination with producing the baryon asymmetry of the Universe. We demonstrate these conditions require $\mathrm{Tr}[Y_N^{†}{Y}_N]\lesssim 0.66$ on the neutrino Yukawa matrix. We also investigate this scenario in the presence of a large number $N_F$ of coloured Majorana octet fermions in order to make quantum chromodynamics asymptotically safe in the ultraviolet.

   hep-phJHEP(2018)·34 citations
10. 10*

    Sharing but not Caring: Collider Phenomenology

    Nicolás Bernal🇨🇴 · Chee Sheng Fong🇧🇷 · Alberto Tonero🇧🇷

    Based on a previous work on scenarios where the Standard Model and dark matter particles share a common asymmetry through effective operators at early time in the Universe and later on decouple from each other (not care), in this work, we study in detail the collider phenomenology of these scenarios. In particular, we use the experimental results from the Large Hadron Collider (LHC) to constrain the viable parameter space. Besides effective operators, we also constrain the parameter space of some representative ultraviolet complete models with experimental results from both the LHC and the Large Electron-Positron Collider. Specifically, we use measurements related to jets + missing transverse energy (MET), di-jets and photon + MET. In the case of ultraviolet models, depending on the assumptions on the couplings and masses of mediators, the derived constraints can become more or less stringent. We consider also the situation where one of the mediators has mass below 100 GeV, in this case we use the ultraviolet model to construct a new effective operator responsible for the sharing of the asymmetry and study its phenomenology.

    hep-phJHEP(2018)·2 citations
11. 11*

    Dark side of the Seesaw

    Subhaditya Bhattacharya🇮🇳 · Ivo de Medeiros Varzielas🇵🇹 · Biswajit Karmakar🇮🇳 · Stephen F. King🇬🇧 · Arunansu Sil🇮🇳

    In an attempt to unfold (if any) a possible connection between two apparently uncorrelated sectors, namely neutrino and dark matter, we consider the type-I seesaw and a fermion singlet dark matter to start with. Our construction suggests that there exists a scalar field mediator between these two sectors whose vacuum expectation value not only generates the mass of the dark matter, but also takes part in the neutrino mass generation. While the choice of $Z_4$ symmetry allows us to establish the framework, the vacuum expectation value of the mediator field breaks $Z_4$ to a remnant $Z_2$, that is responsible to keep dark matter stable. Therefore, the observed light neutrino masses and relic abundance constraint on the dark matter, allows us to predict the heavy seesaw scale as illustrated in this paper.The methodology to connect dark matter and neutrino sector, as introduced here, is a generic one and can be applied to other possible neutrino mass generation mechanism and different dark matter candidate(s).

    hep-phJHEP(2018)·21 citations
12. 12*

    Big Bang Nucleosynthesis Constraint on Baryonic Isocurvature Perturbations

    Keisuke Inomata🇯🇵 · Masahiro Kawasaki🇯🇵 · Alexander Kusenko🇺🇸 · Louis Yang🇯🇵

    We study the effect of large baryonic isocurvature perturbations on the abundance of deuterium (D) synthesized in big bang nucleosynthesis (BBN). We found that large baryonic isocurvature perturbations existing at the BBN epoch ($T\sim 0.1$MeV) change the D abundance by the second order effect, which, together with the recent precise D measurement, leads to a constraint on the amplitude of the power spectrum of the baryon isocurvature perturbations. The obtained constraint on the amplitude is $\lesssim 0.016(2\sigma )$ for scale $k^{-1}\gtrsim 0.0025\text{pc}$. This gives the most stringent one for $0.1{\text{Mpc}}^{-1}\lesssim k\lesssim 4\times 10^8{\text{Mpc}}^{-1}$. We apply the BBN constraint to the relaxation leptogenesis scenario, where large baryon isocurvature perturbations are produced in the last $N_{\text{last}}$ $e$-fold of inflation, and we obtain a constraint on $N_{\text{last}}$.

    ↳ astro-ph.COhep-phJCAP(2018)·28 citations
13. 13*

    Forward-backward $b$-quark asymmetry at the Z pole: QCD uncertainties redux

    David d'Enterria🇨🇭 · Cynthia Yan🇨🇭

    The forward-backward asymmetry of $b$-quarks measured at LEP in $e^{+}{e}^{-}$ collisions at the Z pole, $A_{FB}^{0,b}{|}^{\exp }=0.0992\pm 0.0016$, remains today the electroweak precision observable with the largest disagreement (2.8$\sigma$) with the Standard Model theoretical prediction, $A_{FB}^{0,b}{|}^{\mathrm{th}}=0.1037\pm 0.0008$. The dominant systematic uncertainties are due to QCD effects --- $b,c$-quark showering and fragmentation, and $B,D$ meson decay models --- which have not been revisited in the last 20 years. We reassess the QCD uncertainties of the eight original LEP measurements of $A_{FB}^{0,b}$, using modern parton shower simulations based on PYTHIA-8 and PYTHIA-8 plus VINCIA with different tunes of soft and collinear radiation as well as of hadronization. Our analysis indicates QCD uncertainties, of order $\pm$0.4\% and $\pm$1\% for the jet-charge and lepton-charge based analyses, that are overall slightly smaller but still consistent with the original ones. Using the updated QCD systematic uncertainties, we obtain $A_{FB}^{0,b}=0.0996\pm 0.0016$.

    ↳ hep-exhep-ph8 citations
14. 14*

    Gravitational collapse and formation of universal horizons in Einstein-aether theory

    Madhurima Bhattacharjee🇺🇸 · Shinji Mukohyama🇯🇵 · Mew-Bing Wan🇨🇳 · Anzhong Wang🇺🇸

    We numerically study the gravitational collapse of a massless scalar field with spherical symmetry in Einstein-aether theory, and show that apparent, spin-0 and dynamical universal horizons (dUHs) can be all formed. The spacetime and the aether field are well-behaved and regular, including regions nearby these horizons (but away from the center of spherical symmetry). The spacetime outside the apparent and spin-0 horizons settles down to a static configuration, and some of such resulting static black holes were already found numerically in the literature. On the other hand, the proper distance of the outermost dUH from the apparent (or spin-0) horizon keeps increasing on $\text{mbox}\text{ae}$ther-orthogonal time slices. This indicates that the outermost dUH is evolving into the causal boundary, even for excitations with large speeds of propagation.

    ↳ gr-qcastro-ph.GAhep-phhep-thPRD(2018)·27 citations
15. 15*

    Unfolding with Generative Adversarial Networks

    Kaustuv Datta🇨🇭 · Deepak Kar🇿🇦 · Debarati Roy🇿🇦

    Correcting measured detector-level distributions to particle-level is essential to make data usable outside the experimental collaborations. The term unfolding is used to describe this procedure. A new method of unfolding data using a modified Generative Adversarial Network (MSGAN) is presented here. Applied to various distributions with widely different shapes, it performs roughly at par with currently used methods. This is a proof-of-principle demonstration of a state-of-the-art machine learning method that can be used to model detector effects well.

    ↳ physics.data-anhep-exhep-ph93 citations
16. 16*

    Polarized EMC Effect in the QMC Model

    Stephen Tronchin🇦🇺 · Hrayr H. Matevosyan🇦🇺 · Anthony W. Thomas🇦🇺

    The ratios of the in-medium to free nucleon structure functions for the unpolarized and polarized cases are obtained using the MIT bag model for the free case, along with the QMC model to incorporate the in-medium modifications of the structure functions. As discussed in earlier work, the observed nuclear EMC effect is reasonably well described. This gives us confidence to investigate the predictions of the model for the polarized EMC effect, the ratio $g_1^{\ast }(x)/g_1(x)$ for a bound proton to that of a free proton. This ratio is found to be substantially different from unity and very similar in shape and size to that found in the unpolarized case. This prediction of such a fundamental change in the valence structure of a bound nucleon needs to be tested experimentally at the earliest opportunity.

    ↳ nucl-thhep-phnucl-exPLB(2018)·12 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.