Thu·Aug 30, 2018Thursday·August 30, 2018

1. 01*

   New predictions for ${\Lambda }_b\to {\Lambda }_c$ semileptonic decays and tests of heavy quark symmetry

   Florian U. Bernlochner🇩🇪 · Zoltan Ligeti🇺🇸 · Dean J. Robinson🇺🇸 · William L. Sutcliffe🇩🇪

   The heavy quark effective theory makes model independent predictions for semileptonic ${\Lambda }_b\to {\Lambda }_c$ decays in terms of a small set of parameters. No subleading Isgur-Wise function occurs at order ${\Lambda }_{\mathrm{QCD}}/m_{c,b}$, and only two sub-subleading functions enter at order ${\Lambda }_{\mathrm{QCD}}^2/m_c^2$. These features allow us to fit the form factors and decay rates calculated up to order ${\Lambda }_{\mathrm{QCD}}^2/m_c^2$ to LHCb data and lattice QCD calculations. We derive a significantly more precise standard model prediction for the ratio $\mathcal{B}({\Lambda }_b\to {\Lambda }_c\tau \bar{\nu })/\mathcal{B}({\Lambda }_b\to {\Lambda }_c\mu \bar{\nu })$ than prior results, and find the expansion in ${\Lambda }_{\mathrm{QCD}}/m_c$ well-behaved, addressing a long-standing question. Our results allow more precise and reliable calculations of ${\Lambda }_b\to {\Lambda }_c\ell \bar{\nu }$ rates, and are systematically improvable with better data on the $\mu$ (or $e$) modes.

   hep-phhep-exPRL(2018)·73 citations
2. 02*

   Forward Drell-Yan production at the LHC in the BFKL formalism with collinear corrections

   F. G. Celiberto🇪🇸 · D. Gordo Gómez🇪🇸 · A. Sabio Vera🇪🇸

   Motivated by the recent work of Brzemiński, Motyka, Sadzikowski and Stebel in arXiv:1611.04449, where forward Drell--Yan production is studied in proton-proton collisions at the LHC, we improve their calculation by introducing an unintegrated gluon density obtained in arXiv:1209.1353 and arXiv:1301.5283 from a fit to combined HERA data at small values of Bjorken $x$. This gluon density was calculated within the BFKL formalism at next-to-leading order with collinear corrections. We show that it generates a good description of the forward Drell--Yan cross section dependence on the invariant mass of the lepton pair both for LHCb and ATLAS data.

   hep-phPLB(2018)·106 citations
3. 03*

   Novel physics opportunities at the HESR-Collider with PANDA at FAIR

   Leonid Frankfurt🇮🇱 · Mark Strikman🇺🇸 · Alexei Larionov🇩🇪 · Andreas Lehrach🇩🇪 · Rudolf Maier🇩🇪 · Hendrik van Hees🇩🇪 · Christian Spieles🇩🇪 · Volodymyr Vovchenko🇩🇪 · Horst Stoecker🇩🇪

   Exciting new scientific opportunities are presented for the PANDA detector at the High Energy Storage Ring in the redefined $\bar{\text{p}}\text{p}(A)$ collider mode, HESR-C, at the Facility for Antiproton and Ion Research (FAIR) in Europe. The high luminosity, $L\sim 10^{31}$ cm${}^{-2}$ s${}^{-1}$, and a wide range of intermediate and high energies, $\sqrt{s_{\text{NN}}}$ up to 30 GeV for $\bar{\text{p}}\text{p}(A)$ collisions will allow to explore a wide range of exciting topics in QCD, including the study of the production of excited open charm and bottom states, nuclear bound states containing heavy (anti)quarks, the interplay of hard and soft physics in the dilepton production, and the exploration of the regime where gluons -- but not quarks -- experience strong interaction.

   hep-phhep-exnucl-exnucl-th4 citations
4. 04*

   Anomalous Discrete Flavor Symmetry and Domain Wall Problem

   So Chigusa🇯🇵 · Kazunori Nakayama🇯🇵

   Discrete flavor symmetry is often introduced for explaining quark/lepton masses and mixings. However, its spontaneous breaking leads to the appearance of domain walls, which is problematic for cosmology. We consider a possibility that the discrete flavor symmetry is anomalous under the color SU(3) so that it splits the energy levels of degenerate discrete vacua as a solution to the domain wall problem. We find that in most known models of flavor symmetry, the QCD anomaly effect can only partially remove the degeneracy and there still remain degenerate vacua.

   hep-phPLB(2019)·18 citations
5. 05*

   Interactions between vector mesons and dynamically generated resonances

   Meng-Lin Du🇩🇪 · Dilege Gülmez🇩🇪 · Feng-Kun Guo🇨🇳 · Ulf-G. Meißner🇩🇪 · Qian Wang🇩🇪

   The $\rho \rho$ interaction and the corresponding dynamically generated bound states are revisited. We demonstrate that an improved unitarization method is necessary to study the pole structures of amplitudes outside the near-threshold region. In this work, we extend the study of the covariant $\rho \rho$ scattering in a unitarized chiral theory to the $S$-wave interactions for the whole vector-meson nonet. We demonstrate that there are unphysical left-hand cuts in the on-shell factorization approach of the Bethe-Salpeter equation. This is in conflict with the correct analytic behavior and makes the so-obtained poles, corresponding to possible bound states or resonances, unreliable. To avoid this difficulty, we employ the first iterated solution of the $N/D$ method and investigate the possible dynamically generated resonances from vector-vector interactions. A comparison with the results from the nonrelativistic calculation is provided as well.

   hep-phhep-exhep-latnucl-thEPJC(2018)·48 citations
6. 06*

   Fermiophobic gauge boson phenomenology in 221 Models

   Baradhwaj Coleppa🇮🇳 · Satendra Kumar🇮🇳 · Agnivo Sarkar🇮🇳

   Models with extra gauge symmetry are well-motivated extensions of the Standard Model. In this paper, we study an extended gauge model with a heavy neutral gauge boson $Z^{\prime }$ which is fermiophobic. Thus, the production of such particles can occur via vector boson fusion, with subsequent decays into $WW$ or $Zh$. We investigate the collider phenomenology of such $Z^{\prime }$s in the context of both the 14 TeV LHC and the future CLIC. We find that looking at $\ell \ell bb$ final states provides a rich opportunity to discover such new vector bosons where conventional search strategies in the dilepton channel would fail. In particular, we optimize our analysis by putting in kinematic cuts deriving model-independent values of $\sigma \times$BR needed for a 5$\sigma$ discovery at the LHC. We then translate this into the parameter space of a specific model for illustration purpose -- our results show that fermiophobic $Z^{\prime }$s are discoverable in the $\ell \ell bb$ channel for wide range of parameter values.

   hep-phPRD(2018)·7 citations
7. 07*

   Strongly intensive observable between multiplicities in two acceptance windows in a string model

   Evgeny Andronov🇷🇺 · Vladimir Vechernin🇷🇺

   The strongly intensive observable between multiplicities in two acceptance windows separated in rapidity and azimuth is calculated in the model with quark-gluon strings acting as sources. The dependence of this observable on the two-particle correlation function of a string, the width of observation windows and the rapidity gap between them is analyzed. In the case with independent identical strings the model calculation confirms the strongly intensive character of this observable: it is independent of both the mean number of string and its fluctuation. For this case the peculiarities of its behaviour for particles with different electric charges are also analyzed. In the case when the string fusion processes are taken into account and a formation of strings of a few different types takes place in a collision, this observable is proved to be equal to a weighted average of its values for different string types. Unfortunately, in this case through the weight factors this observable becomes dependent on collision conditions and, strictly speaking, can not be considered any more as strongly intensive variable. For a comparison the results of the calculation of considered observable with the PYTHIA event generator are also presented.

   hep-phnucl-thEPJA(2019)·26 citations
8. 08*

   Two particle azimuthal harmonics in pA collisions

   Manyika Kabuswa Davy🇨🇳 · Cyrille Marquet🇫🇷 · Yu Shi🇨🇳 · Bo-Wen Xiao🇨🇳 · Cheng Zhang🇨🇳

   We compute two-particle production in p+A collisions and extract azimuthal harmonics, using the dilute-dense formalism in the Color Glass Condensate framework. The multiple scatterings of the partons inside the projectile proton on the dense gluons inside the target nucleus are expressed in terms of Wilson lines. They generate interesting correlations, which can be partly responsible for the signals of collectivity measured at RHIC and at the LHC. Most notably, while gluon Wilson loops yield vanishing odd harmonics, quark Wilson loops can generate sizable odd harmonics for two particle correlations. By taking both quark and gluon channels into account, we find that the overall second and third harmonics lie rather close to the recent PHENIX data at RHIC.

   hep-phnucl-thNPA(2019)·18 citations
9. 09*

   Probing the gluon TMDs with quarkonia

   Jean-Philippe Lansberg🇫🇷 · Cristian Pisano🇮🇹 · Florent Scarpa🇫🇷 · Marc Schlegel🇺🇸

   We briefly review how quarkonium hadroproduction can be used to access the polarised and unpolarised gluon TMDs.

   hep-phhep-exnucl-exnucl-thPoS(2018)·2 citations
10. 10*

    Theoretical analysis of double parton scatterings in quarkonium production in proton-proton collisions at the LHC

    Nodoka Yamanaka🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Hua-Sheng Shao🇫🇷 · Yu-Jie Zhang🇨🇳

    The production process of quarkonia in proton-proton (pp) collision is a very good probe of the parton structure of the proton. Recent experimental data of the production of J/psi+vector boson or quarkonium pairs at the LHC and Tevatron suggest the relevance of double parton scatterings (DPS). We discuss here the single parton scattering (SPS) contribution to the J/psi +Z, J/psi +W, and J/psi +J/psi productions in hadron collisions. By revisiting the computations of the SPS contributions to the J/psi+Z and J/psi +W productions, we demonstrate that the ATLAS data in fact show evidence for DPS.

    hep-phhep-exnucl-exnucl-thPoS(2018)·0 citations
11. 11*

    Antinuclei in Heavy-Ion Collisions

    Jinhui Chen🇨🇳 · Declan Keane🇺🇸 · Yugang Ma🇨🇳 · Aihong Tang🇺🇸 · Zhangbu Xu🇺🇸

    We review progress in the study of antinuclei, starting from Dirac's equation and the discovery of the positron in cosmic-ray events. The development of proton accelerators led to the discovery of antiprotons, followed by the first antideuterons, demonstrating that antinucleons bind into antinuclei. With the development of heavy-ion programs at the Brookhaven AGS and CERN SPS, it was demonstrated that central collisions of heavy nuclei offer a fertile ground for research and discoveries in the area of antinuclei. In this review, we emphasize recent observations at Brookhaven's Relativistic Heavy Ion Collider and at CERN's Large Hadron Collider, namely, the antihypertriton and the antihelium-4, as well as measurements of the mass difference between light nuclei and antinuclei, and the interaction between antiprotons. Physics implications of the new observations and different production mechanisms are discussed. We also consider implications for related fields, such as hypernuclear physics and space-based cosmic-ray experiments.

    ↳ nucl-exhep-phnucl-thPhys.Rept.(2018)·160 citations
12. 12*

    Updated evaluation of ${\epsilon }_K$ in the Standard Model with lattice QCD inputs

    Jon A. Bailey🇰🇷 · Sunkyu Lee🇰🇷 · Weonjong Lee · Jaehoon Leem🇰🇷 · Sungwoo Park🇺🇸

    We report a strong tension in ${\epsilon }_K$ at the $4\sigma$ level between the experimental value and the theoretical value calculated directly from the standard model using lattice QCD inputs such as ${\hat{B}}_K$, $|V_{cb}|$, $|V_{us}|$, ${\xi }_0$, ${\xi }_2$, ${\xi }_{\text{LD}}$, $F_K$, and $m_c$. The standard model with lattice QCD inputs describes only 70% of the experimental value of ${\epsilon }_K$, and does not explain its remaining 30%. We also find that this tension disappears when we use the inclusive value of $|V_{cb}|$ (results of the heavy quark expansion based on QCD sum rules) to determine ${\epsilon }_K$. This tension is highly correlated with the present discrepancy between the exclusive and inclusive values of $|V_{cb}|$. In order to resolve, in part, the issue with $|V_{cb}|$, it would be highly desirable to have a comprehensive re-analysis over the entire set of experimental data on the $\bar{B}\to D^{\ast }\ell \bar{\nu }$ decays using an alternative parametrization of the form factors, such as the BGL parametrization, and a comparison with results of the CLN method.

    ↳ hep-lathep-phPRD(2018)·30 citations
13. 13*

    Inflation, (P)reheating and Neutrino Anomalies: Production of Sterile Neutrinos with Secret Interactions

    Arnab Paul🇮🇳 · Anish Ghoshal🇮🇹 · Arindam Chatterjee🇮🇳 · Supratik Pal🇮🇳

    A number of experimental anomalies involving neutrinos hint towards the existence of at least an extra (a very light) sterile neutrino. However, such a species, appreciably mixing with the active neutrinos, is disfavored by different cosmological observations like Big Bang Nucleosynthesis (BBN), Cosmic Microwave Background (CMB) and Large Scale Structure (LSS). Recently, it was shown that the presence of additional interactions in the sterile neutrino sector via light bosonic mediators can make the scenario cosmologically viable by suppressing the production of the sterile neutrinos from active neutrinos via matter-like effect caused by the mediator. This mechanism works assuming the initial population of this sterile sector to be negligible with respect to that of the Standard Model (SM) particles, before the production from active neutrinos. However, there is fair chance that such bosonic mediators may couple to the inflaton and can be copiously produced during (p)reheating epoch. Consequently, they may ruin this assumption of initial small density of the sterile sector. In this article we, starting from inflation, investigate the production of such a sterile sector during (p)reheating in a large field inflationary scenario and identify the parameter region that allows for a viable early Universe cosmology.

    ↳ astro-ph.COhep-phEPJC(2019)·20 citations
14. 14*

    The two-loop energy-momentum tensor within the gradient-flow formalism

    Robert V. Harlander🇩🇪 · Yannick Kluth🇩🇪 · Fabian Lange🇩🇪

    The gradient-flow formulation of the energy-momentum tensor of QCD is extended to NNLO perturbation theory. This means that the Wilson coefficients which multiply the flowed operators in the corresponding expression for the regular energy-momentum tensor are calculated to this order. The result has been obtained by applying modern tools of regular perturbation theory, reducing the occurring two-loop integrals, which also include flow-time integrations, to a small set of master integrals which can be calculated analytically.

    ↳ hep-lathep-phEPJC(2018)·73 citations
15. 15*

    Elliptic flow in ultra-relativistic collisions with polarized deuterons

    Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱

    Predictions are made for elliptic flow in collisions of polarized deuterons with a heavy nucleus. It is shown that the eccentricity of the initial fireball, evaluated with respect to the deuteron polarization axis perpendicular to the beam direction, has a substantial magnitude for collisions of highest multiplicity. Within the Glauber approach we obtain $\sim 7\%$ for the deuteron states with spin projection 0, and $\sim -3\%$ for spin projection $\pm 1$. We propose to measure the elliptic flow coefficient as the second order harmonic coefficient in the azimuthal distribution of produced charged hadrons with respect to the fixed polarization axis. Collective expansion yields a value of the order of $1\%$ for this quantity, as compared to zero in the absence of polarization and/or collectivity. Such a vivid rotational symmetry breaking could be measured with the current experimental accuracy of the relativistic heavy-ion experiments. The effect has a fundamental significance for understanding the nature of dynamics in small systems, as its experimental confirmation would prove the presence of the shape-flow transmutation mechanism, typical of hydrodynamic expansion or rescattering in the later stages of the fireball evolution.

    ↳ nucl-thhep-phnucl-exPRL(2018)·17 citations
16. 16*

    Massive Primordial Black Holes in Contemporary and Young Universe (old predictions and new data)

    A.D. Dolgov🇷🇺

    A brief review of the recent astronomical data, indicating that the universe is abundantly populated by heavy black holes (BH), is presented. Conventional astrophysics and cosmology cannot explain such a high population of BHs. A mechanism of the paper of 1963 is described, which at least qualitatively explained the observational data. In particular, the prediction that massive primordial BHs can be cosmological dark matter "particles" is discussed.

    ↳ astro-ph.COhep-phInt.J.Mod.Phys.A(2018)·11 citations
17. 17*

    Top FCNC searches at HL-LHC with the CMS experiment

    Petr Mandrik (for the CMS Collaboration)🇷🇺

    The Large Hadron Collider is the world's largest and highest center-of-mass energy particle accelerator. During the Phase I operation it is expected that the LHC operated at a centre-of-mass energy of 13 TeV will deliver to the CMS experiment total integrated luminosity of $\sim$300 fb${}^{-1}$ till 2023. The High Luminosity LHC upgrade is expected to run at a centre-of-mass energy of 14 TeV and will allow ATLAS and CMS to collect integrated luminosities of the order of 300 fb${}^{-1}$ per year, and up to 3000 fb${}^{-1}$ during the HL-LHC projected lifetime of ten years. The large expected integrated luminosity enables the exploration of the multi-TeV scale by searches for particles with high masses as well as by investigation of processes with very low cross sections such as Flavor-Change Neutral Current interactions in top quark sector. In this report we present a proposal for the top quark FCNC searches at HL-LHC based on Monte-Carlo simulation of the upgraded CMS detector.

    ↳ hep-exhep-phEPJ Web Conf.(2018)·7 citations
18. 18*

    Schwarzschild/CFT from soft black hole hair?

    Artem Averin🇩🇪

    Recent studies of asymptotic symmetries suggest, that a Hamiltonian phase space analysis in gravitational theories might be able to account for black hole microstates. In this context we explain, why the use of conventional Bondi fall-off conditions for the gravitational field is too restrictive in the presence of an event horizon. This implies an enhancement of physical degrees of freedom ($\mathcal{A}$-modes). They provide new gravitational hair and are responsible for black hole microstates. Using covariant phase space methods, for the example of a Schwarzschild black hole, we give a proposal for the surface degrees of freedom and their surface charge algebra. The obtained two-dimensional dual theory is conjectured to be conformally invariant as motivated from the criticality of the black hole. Carlip's approach to entropy counting reemerges as a Sugawara-construction of a 2D stress-tensor.

    ↳ hep-thgr-qchep-phJHEP(2019)·17 citations
19. 19*

    Photon Masses in the Landscape and the Swampland

    Matthew Reece🇺🇸

    In effective quantum field theory, a spin-1 vector boson can have a technically natural small mass that does not originate from the Higgs mechanism. For such theories, which may be written in Stückelberg form, there is no point in field space at which the mass is exactly zero. I argue that quantum gravity differs from, and constrains, effective field theory: arbitrarily small Stückelberg masses are forbidden. In particular, the limit in which the mass goes to zero lies at infinite distance in field space, and this distance is correlated with a tower of modes becoming light according to the Swampland Distance Conjecture. Application of Tower or Sublattice variants of the Weak Gravity Conjecture makes this statement more precise: for a spin-1 vector boson with coupling constant $e$ and Stückelberg mass $m$, local quantum field theory breaks down at energies at or below ${\Lambda }_{\mathrm{UV}}=\min ((m{M}_{\mathrm{Pl}}/e{)}^{1/2},e^{1/3}{M}_{\mathrm{Pl}})$. Combined with phenomenological constraints, this argument implies that the Standard Model photon must be exactly massless. It also implies that much of the parameter space for light dark photons, which are the target of many experimental searches, is compatible only with Higgs and not Stückelberg mass terms. This significantly affects the experimental limits and cosmological histories of such theories. I explain various caveats and weak points of the arguments, including loopholes that could be targets for model-building.

    ↳ hep-thhep-phJHEP(2019)·134 citations
20. 20*

    Pseudo-rapidity distribution from a perturbative solution of viscous hydrodynamics for heavy ion collisions at RHIC and LHC

    Ze Fang Jiang🇨🇳 · C. B. Yang🇨🇳 · Chi Ding🇨🇳 · Xiang-Yu Wu🇨🇳

    The charged-particle's final state spectrum is derived from an analytic perturbative solution for the relativistic viscous hydrodynamics. By taking into account the longitudinal acceleration effect in relativistic viscous hydrodynamics, the pseudorapidity spectrum describes well the nucleus-nucleus colliding systems at RHIC and LHC. Based on both the extracted longitudinal acceleration parameters ${\lambda }^{\ast }$ and a phenomenological description of the ${\lambda }^{\ast }$, the charged-particle's pseudorapidity distributions for $\sqrt{s_{NN}}$ = 5.44 TeV Xe+Xe collisions are computed from the final state expression in a limited space-time rapidity ${\eta }_s$ region.

    ↳ nucl-thhep-phhep-thCPC(2018)·11 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.