Mon·Sep 10, 2018Monday·September 10, 2018

1. 01*

   Diffractive scattering on the deuteron projectile in the NLO: triple interaction of reggeized gluons

   M.A. Braun🇷🇺 · S.S. Pozdnyakov🇮🇱 · M.Yu. Salykin🇷🇺 · M.I. Vyazovsky (Saint-Petersburg State University, Russia)🇷🇺

   High-mass diffractive production of protons on the deuteron target is studied in the next-to-leading order (NLO) of the perturbative QCD in the BFKL approach. The non-trivial part of the NLO contributions coming from the triple interactions of the exchanged reggeons is considered. Analytic formulas are presented and shown to be infrared free and so ready for practical calculation.

   hep-phEPJC(2018)·2 citations
2. 02*

   Constraints on a sub-eV scale sterile neutrino from non-oscillation measurements

   C. S. Kim🇰🇷 · G. López Castro🇲🇽 · Dibyakrupa Sahoo🇰🇷

   Anomalies in several short-baseline neutrino oscillation experiments suggest the possible existence of sterile neutrinos at about eV scale having appreciable mixing with the already known three neutrinos. We find that if such a light sterile neutrino exists, through a combined study of the leptonic decays of ${\mu }^{-}$, ${\tau }^{-}$, ${\pi }^{-}$ and $K^{-}$, some semi-leptonic decays of ${\tau }^{-}$ and the invisible decay width of the $Z$ boson, it is possible to constrain the relevant mixing matrix elements. Furthermore, we compare the constraints, derived by using the method presented here, with the experimental results obtained from short-baseline neutrino oscillation experiments. We find that a single light sterile neutrino cannot satisfy the existing short-baseline neutrino oscillation constraints and explain the anomalies mentioned above. Along the way we provide a number of experimentally clean observables which can be used to directly study the light sterile neutrino independently of the neutrino oscillation experiments.

   hep-phPRD(2018)·9 citations
3. 03*

   Non-parametric uncertainties in the dark matter velocity distribution

   Andrew Fowlie🇦🇺

   We investigate the impact of uncertainty in the velocity distribution of dark matter on direct detection experiments. We construct an multinomial prior with a hyperparameter $\beta$ that describes the strength of our belief in an isotropic Maxwell-Boltzmann velocity distribution. By varying $\beta$, we interpolate between a halo-independent and halo-dependent analysis. We present a novel approximation for the marginalisation of this prior that is applicable to any counting experiment. With this formula, we investigate the impact of the uncertainty in limits from XENON1T. For dark matter masses greater than about 60 GeV, we find extremely mild sensitivity to the distribution. Below about 60 GeV, the limit weakens by less than an order of magnitude if we assume an isotropic distribution in the galactic frame. If we permit anisotropic distributions, the limit further weakens, but at most by about two orders of magnitude. Lastly, we check the impact of parametric uncertainties and discuss the possible inclusion and impact of our technique in global fits.

   hep-phastro-ph.COphysics.data-anJCAP(2019)·12 citations
4. 04*

   Non-thermal production of Dark Matter after Inflation

   Nicolás Bernal🇨🇴 · Arindam Chatterjee🇮🇳 · Arnab Paul🇮🇳

   The existence of Dark Matter (DM) has been well established from various cosmological and astrophysical evidences. However, the particle properties of DM are largely undetermined and attempts to probe its interactions with the Standard Model (SM) particles have, so far, not met with any success. The stringent constraints on the DM-SM interactions, while does not exclude the standard lore of producing weakly massive interacting particle DM candidates through thermal freeze-out mechanism in its entirety, have certainly cast shadow on the same. In this work, we consider non-thermal production of DM within a simple extension of the SM including an inflaton field and a scalar DM candidate. Assuming negligible interactions between the SM particles and the DM, we study the production of the latter at the end of inflation, during the (p)reheating epoch. In this context, we explore the role of DM self-interactions and its interaction with the inflaton field, and find that DM can be over produced in a significant region of the parameter space. We further demonstrate that large self-interaction of the DM can suppress its abundance during preheating and to a certain extent helps to achieve the observed relic abundance via cannibalization.

   hep-phastro-ph.COJCAP(2018)·34 citations
5. 05*

   Chiral partner structure of light nucleons in an extended parity doublet model

   Takahiro Yamazaki🇯🇵 · Masayasu Harada🇯🇵

   We study chiral partner structure of four light nucleons, $N(939)$, $N(1440)$, $N(1535)$ and $N(1650)$ using an effective chiral model based on the parity doublet structure. In our model we introduce four chiral representations, $(1,2)$, $(2,1)$, $(2,3)$ and $(3,2)$ under $\mathrm{SU}(2{)}_{\mathrm{L}}\otimes \mathrm{SU}(2{)}_{\mathrm{R}}$ symmetry. We determine the model parameters by fitting them to available experimental values of masses, widths and the axial charge of $N(939)$ together with the axial charges of $N(1535)$ and $N(1650)$ by lattice analyses. We find five groups of solutions: In a group the chiral partner to $N(939)$ is $N(1440)$ having small chiral invariant mass. In another group, the chiral partner is a mixture of $N(1535)$ and $N(1650)$ having a large chiral invariant mass. We claim that off-diagonal elements of axial-charge matrix can be used for distinguishing these groups. We also discuss changes of masses associated with chiral symmetry restoration, which could emerge in high density matter.

   hep-phPRD(2019)·23 citations
6. 06*

   Boosting perturbative QCD stability in quarkonium production

   Hua-Sheng Shao🇫🇷

   The aim of this paper is to introduce a general way to stabilize the perturbative QCD computations of heavy quarkonium production in the boosted or high-momentum transferring region with tree-level generators only. Such an approach is possible by properly taking into account the power-enhanced perturbative contributions in a soft and collinear safe manner without requiring any complete higher-order computations. The complicated NLO results for inclusive quarkonium hadroproduction can be well reproduced within our approach based on a tree-level generator {\sc\small HELAC-Onia}. We have applied it to estimate the last missing leading-twist contribution from the spin-triplet color-singlet S-wave production at $\mathcal{O}({\alpha }_s^5)$, which is a NNLO term in the ${\alpha }_s$ expansion for the quarkonium $P_T$ spectrum. We conclude that the missing NNLO contribution will not change the order of the magnitude of the short-distance coefficient. Such an approach is also quite appealing as it foresees broad applications in quarkonium-associated production processes, which are mostly absent of complete higher-order computations and fragmentation functions.

   hep-phhep-exJHEP(2019)·17 citations
7. 07*

   Next-to-leading-order QCD corrections to the decay of $Z$ boson into ${\chi }_c({\chi }_b)$

   Zhan Sun🇨🇳 · Hong-Fei Zhang🇨🇳

   Based on the framework of nonrelativistic Quantum Chromodynamics (NRQCD), we carry out next-to-leading order (NLO) QCD corrections to the decay of $Z$ boson into ${\chi }_c$ and ${\chi }_b$, respectively. The branching ratio of $Z\to {\chi }_c({\chi }_b)+X$ is about $10^{-5}(10^{-6})$. It is found that, for $Z\to {\chi }_c({\chi }_b)+X$, the single gluon fragmentation diagrams of ${}^3{S}_1^{[8]}$, which first appear at the NLO level, can provide significant contributions, leading to a great enhancement on the leading-order results. Consequently the contributions from the color octet (CO) channels will account for a large proportion of the total decay widths. Moreover, the introduction of the CO processes will thoroughly change the color singlet (CS) predictions on the ratios of ${\Gamma }_{{\chi }_{c1}}/{\Gamma }_{{\chi }_{c0}}$, ${\Gamma }_{{\chi }_{c2}}/{\Gamma }_{{\chi }_{c0}}$, ${\Gamma }_{{\chi }_{b1}}/{\Gamma }_{{\chi }_{b0}}$ and ${\Gamma }_{{\chi }_{b2}}/{\Gamma }_{{\chi }_{b0}}$, which can be regarded as an outstanding probe to distinguish the CO and CS mechanism. With regard to the CS (${}^3{P}_J^{[1]}$) channels, the heavy quark pair associated processes serve as the leading role, however, in the case of ${\chi }_b$, $Z\to b\bar{b}{[}^3{P}_J^{[1]}]+g+g$ can also contribute significantly. Summing over all the feeddown contributions from ${\chi }_{cJ}$ and ${\chi }_{bJ}$, respectively, we find $\Gamma (Z\to J/\psi +X){|}_{{\chi }_c-\text{feeddown}}=(0.28-2.4)\times 10^{-5}$ and $\Gamma (Z\to {\rm Y}(1S)+X){|}_{{\chi }_b-\text{feeddown}}=(0.15-0.49)\times 10^{-6}$.

   hep-phPRD(2019)·7 citations
8. 08*

   NLO mixed QCD-EW corrections to Higgs gluon fusion

   Marco Bonetti🇩🇪

   The study of the Higgs boson properties is one of the main tasks of contemporary high-energy physics. Among Higgs properties, its interaction with gluons is interesting since it can be facilitated by yet unknown elementary particles. One of the major sources of uncertainty in the theoretical description of $ggH$ coupling originates from mixed QCD-electroweak contributions. The NLO QCD corrections to these contributions were evaluated in the approximation where electroweak boson masses were considered to be significantly larger than the mass of the Higgs boson and it is desirable to compute these corrections for physical masses of the gauge bosons and the Higgs boson. We present a major step towards this goal and describe first the analytic evaluation of NLO mixed QCD-EW three-loop virtual corrections to $gg\to H$, and then their implementation in the evaluation of the total cross section for $gg\to H$ in the soft-gluon approximation for real corrections.

   hep-phPoS(2018)·1 citation
9. 09*

   Whac-a-constraint with anomaly-free dark matter models

   Sonia El Hedri🇳🇱 · Karl Nordström🇳🇱

   Theories where a fermionic dark matter candidate interacts with the Standard Model through a vector mediator are often studied using minimal models, which are not necessarily anomaly-free. In fact, minimal anomaly-free simplified models are usually strongly constrained by either direct detection experiments or collider searches for dilepton resonances. In this paper, we study the phenomenology of models with a fermionic dark matter candidate that couples axially to a leptophobic vector mediator. Canceling anomalies in these models requires considerably enlarging their field content. For an example minimal scenario we show that the additional fields lead to a potentially much richer phenomenology than the one predicted by the original simplified model. In particular collider searches for pair-produced neutralinos and charginos can be more sensitive than traditional monojet searches in thermally motivated parts of the parameter space where the mediator is outside the reach of current searches.

   hep-phSciPost Phys.(2019)·11 citations
10. 10*

    Total hadronic cross sections at high energies in holographic QCD

    Akira Watanabe🇨🇳 · Mei Huang🇨🇳

    We present our analysis on high energy hadron-hadron scattering in the framework of the holographic QCD. Combining the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel and gravitational form factors of the involved hadrons which are obtained by using the bottom-up AdS/QCD models in the five-dimensional AdS space, we calculate the total cross sections at high energies. We show that our calculations for the nucleon-nucleon scattering agree with the experimental data including the recent ones taken by the TOTEM collaboration at the LHC. The present framework is applicable to any high energy process, in which the strong interaction can be approximated by the Pomeron exchange. We present the results for the pion-nucleon and pion-pion scattering as examples, which can be obtained without any additional parameter because all the adjustable parameters are fixed via the analysis on the nucleon-nucleon scattering. The resulting total cross section ratios are ${\sigma }_{tot}^{\pi N}/{\sigma }_{tot}^{NN}=0.63$ and ${\sigma }_{tot}^{\pi \pi }/{\sigma }_{tot}^{NN}=0.45$, respectively.

    hep-phnucl-thPLB(2019)·19 citations
11. 11*

    Single-top and top-antitop cross sections

    Nikolaos Kidonakis🇺🇸

    I present high-order calculations, including soft-gluon corrections, for single-top and top-antitop production cross sections and differential distributions. For single-top production, results are presented for the three different channels in the Standard Model, for associated production with a charged Higgs, and for processes involving anomalous couplings. For top-antitop pair production, total cross sections and top-quark transverse-momentum and rapidity distributions are presented for various LHC energies.

    hep-phEPJ Web Conf.(2018)·1 citation
12. 12*

    Symmetries and Algebraic Methods in Neutrino Physics

    A.B. Balantekin🇺🇸

    Symmetry properties associated with neutrino propagation with or without a background of other particles, including neutrinos, is reviewed. The utility of symmetries is illustrated with examples chosen from the see-saw mechanism and both matter-enhanced and collective neutrino oscillations. The role of symmetries in neutrino astrophysics is highlighted.

    hep-phastro-ph.SRnucl-thJ.Phys.G(2018)·14 citations
13. 13*

    Measuring the Weizsaecker-Williams distribution of linearly polarized gluons at an EIC through dijet azimuthal asymmetries

    Adrian Dumitru🇺🇸 · Vladimir Skokov🇺🇸 · Thomas Ullrich🇺🇸

    The production of a hard dijet with small transverse momentum imbalance in semi-inclusive DIS probes the conventional and linearly polarized Weizsaecker-Williams (WW) Transverse Momentum Dependent (TMD) gluon distributions. The latter, in particular, gives rise to an azimuthal dependence of the dijet cross-section. In this paper we analyze the feasibility of a measurement of these TMDs through dijet production in DIS on a nucleus at an Electron-Ion Collider. We introduce the MCDijet Monte-Carlo generator to sample quark-antiquark dijet configurations based on leading order parton level cross-sections with WW gluon distributions that solve the non-linear small-x QCD evolution equations. These configurations are fragmented to hadrons using PYTHIA, and final state jets are reconstructed. We report on background studies and on the effect of kinematic cuts introduced to remove beam jet remnants. We estimate that with an integrated luminosity of 20 fb^{-1}/A one can determine the distribution of linearly polarized gluons with a statistical accuracy of approximately 5%.

    hep-phnucl-thPRC(2019)·79 citations
14. 14*

    The Dual QCD @ Work

    Andrzej J. Buras🇩🇪

    The Dual QCD (DQCD) framework, based on the ideas of 't Hooft and Witten, and developed by Bill Bardeen, Jean-Marc Gerard and myself in the 1980s is not QCD, a theory of quarks and gluons, but a successful low energy approximation of it when applied to $K\to \pi \pi$ decays and $K^0-{\bar{K}}^0$ mixing. After years of silence, starting with 2014, this framework has been further developed in order to improve the SM prediction for the ratio ${ϵ}^{\prime }/ϵ$, the $\Delta I=1/2$ rule and ${\hat{B}}_K$. Most importantly, this year it has been used for the calculation of all $K\to \pi \pi$ hadronic matrix elements of BSM operators which opened the road for the general study of ${ϵ}^{\prime }/ϵ$ in the context of the SM effective theory (SMEFT). This talk summarizes briefly the past successes of this framework and discusses recent developments which lead to a master formula for ${ϵ}^{\prime }/ϵ$ valid in any extension of the SM. This formula should facilitate the search for new physics responsible for the ${ϵ}^{\prime }/ϵ$ anomaly hinted by 2015 results from lattice QCD and DQCD.

    hep-phhep-exhep-latEPJ Web Conf.(2018)·7 citations
15. 15*

    Scheme-Independent Calculations of Properties at a Conformal Infrared Fixed Point in Gauge Theories with Multiple Fermion Representations

    Thomas A. Ryttov🇩🇰 · Robert Shrock🇺🇸

    In previous work we have presented scheme-independent calculations of physical properties of operators at a conformally invariant infrared fixed point in an asymptotically free gauge theory with gauge group $G$ and $N_f$ fermions in a representation $R$ of $G$. Here we generalize this analysis to the case of fermions in multiple representations, focusing on the case of two different representations. Our results include the calculation of the anomalous dimensions of gauge-invariant fermion bilinear operators, and the derivative of the beta function, evaluated at the infrared fixed point. We illustrate our results in an SU($N_c$) gauge theory with $N_F$ fermions in the fundamental representation and $N_{Adj}$ fermions in the adjoint representation.

    ↳ hep-thhep-lathep-phPRD(2018)·18 citations
16. 16*

    Can the $H_0$ tension be resolved in extensions to $\Lambda$CDM cosmology?

    Rui-Yun Guo🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    We wish to investigate whether there is an extension to the base $\Lambda$CDM cosmology that can resolve the tension between the Planck observation of the cosmic microwave background anisotropies and the local measurement of the Hubble constant. We consider various plausible extended models in this work, and we use the Planck 2015 observation, combined with the baryon acoustic oscillation data, the JLA type Ia supernovae data, and the local measurement of the Hubble constant (by Riess et al. in 2016), to make an analysis. We find that the holographic dark energy plus sterile neutrino model can reduce the tension to be at the 1.11$\sigma$ level, but this model is obviously not favored by the current observations. Among these extended models, the $\Lambda$CDM+$N_{\mathrm{eff}}$ model is most favored by the current observations, and this model can reduce the tension to be at the 1.87$\sigma$ level. By a careful test, we conclude that none of these extended models can convincingly resolve the $H_0$ tension.

    ↳ astro-ph.COgr-qchep-phJCAP(2019)·199 citations
17. 17*

    Low temperature condensation and scattering data

    Oliver Orasch🇦🇹 · Christof Gattringer🇦🇹 · Mario Giuliani🇦🇹

    We study ${\varphi }^4$ lattice field theory at finite chemical potential $\mu$ in two and four dimensions, using a worldline representation that overcomes the complex action problem. We compute the particle number at very low temperature as a function of $\mu$ and determine the first three condensation thresholds, where the system condenses 1, 2 and 3 particles. The corresponding critical values of the chemical potential can be related to the 1-, 2- and 3-particle energies of the system, and we check this relation with a direct spectroscopy determination of the $n$-particle energies from $2n$-point functions. We analyze the thresholds as a function of the spatial size of the system and use the known finite volume results for the $n$-particle energies to relate the thresholds to scattering data. For four dimensions we determine the scattering length from the 2-particle threshold, while in two dimensions the full scattering phase shift can be determined. In both cases the scattering data computed from the 2-particle threshold already allow one to determine the 3-particle energy. In both, two and four dimensions we find very good agreement of this ''prediction'' with direct determinations of the 3-particle energy from either the thresholds or the 6-point functions. The results show that low temperature condensation is indeed governed by scattering data.

    ↳ hep-lathep-phhep-thPoS(2018)·1 citation
18. 18*

    Interplaying mechanisms behind single inclusive jet suppression in heavy-ion collisions

    Yayun He (CCNU, LBNL)🇨🇳 · Shanshan Cao (WSU)🇺🇸 · Wei Chen (CCNU)🇨🇳 · Tan Luo (CCNU)🇨🇳 · Long-Gang Pang (UCB, LBNL)🇺🇸 · Xin-Nian Wang (CCNU, LBNL, UCB)🇨🇳

    The suppression factor for single inclusive jets in Pb+Pb collisions at the Large Hadron Collider (LHC) has a weak dependence on the transverse momentum $p_T$ and remains almost the same at two colliding energies, $\sqrt{s}=2.76$ and 5.02 TeV, though the central rapidity density of bulk hadrons increases by about 20\%. This phenomenon is investigated within the Linear Boltzmann Transport (LBT) model, which includes elastic and inelastic processes based on perturbative QCD for both jet shower and recoil medium partons as they propagate through a quark-gluon plasma (QGP). With the dynamic evolution of the QGP given by the 3+1D CLVisc hydrodynamic model with event-by-event fully fluctuating initial conditions, single inclusive jet suppression in Pb+Pb collisions from LBT agrees well with experimental data. The weak $\sqrt{s}$ and $p_T$-dependence of the jet suppression factor at LHC are found to result directly from the $\sqrt{s}$-dependence of the initial jet $p_T$ spectra and slow $p_T$-dependence of the jet energy loss. Contributions from jet-induced medium response, influence of radial expansion, both of which depend on jet-cone size, and jet flavor composition all conjoin to give a slow $p_T$-dependence of jet energy loss and the single jet suppression factor $R_{\mathrm{AA}}$, their dependence on $\sqrt{s}$ and jet-cone size. Single inclusive jet suppression at $\sqrt{s}=200$ GeV is also predicted that actually decreases slightly with $p_T$ in the $p_T<50$ GeV/$c$ range because of the steeper initial jet spectra though the $p_T$-dependence of the jet energy loss is weaker than that at LHC.

    ↳ nucl-thhep-phPRC(2019)·133 citations
19. 19*

    Unique Fingerprints of Alternatives to Inflation in the Primordial Power Spectrum

    Xingang Chen🇺🇸 · Abraham Loeb🇺🇸 · Zhong-Zhi Xianyu🇺🇸

    Massive fields in the primordial universe function as standard clocks and imprint clock signals in the density perturbations that directly record the scale factor of the primordial universe as a function of time, a(t). A measurement of such signals would identify the specific scenario of the primordial universe in a model-independent fashion. In this Letter, we introduce a new mechanism through which quantum fluctuations of massive fields function as standard clocks. The clock signals appear as scale-dependent oscillatory signals in the power spectrum of alternative scenarios to inflation.

    ↳ astro-ph.COgr-qchep-phhep-thPRL(2019)·52 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.