Fri·Aug 10, 2018Friday·August 10, 2018

1. 01*

   Same-sign Multilepton Signatures of an $SU(2{)}_R$ Quintuplet at the LHC

   Sanjib Kumar Agarwalla🇮🇳 · Kirtiman Ghosh🇮🇳 · Nilanjana Kumar🇮🇳 · Ayon Patra🇮🇳

   We study in detail the collider signatures of an $SU(2{)}_R$ fermionic quintuplet in the framework of left-right symmetric model in the context of the 13 TeV LHC. Apart from giving a viable dark matter candidate (${\chi }^0$), this model provides unique collider imprints in the form of same-sign multileptons through the decays of multi-charged components of the quintuplet. In particular, we consider the scenario where the quintuplet carries $(B-L)=4$ charge, allowing for the presence of high charge-multiplicity particles with relatively larger mass differences among them compared to $(B-L)$ = 0 or 2. In this paper, we mainly focus on the same-sign n-lepton signatures (nSSL). We show that with an integrated luminosity of 500 $f{b}^{-1}$, the mass of the neutral component, $M_{{\chi }^0}\le 480(800)$ GeV can be excluded at 95\% CL in the 2SSL (3SSL) channel after imposing several selection criteria. We also show that a $5\sigma$ discovery is also achievable if $M_{{\chi }^0}\le 390(750)$ GeV in the 2SSL (3SSL) channel with 1000 $f{b}^{-1}$ integrated luminosity.

   hep-phJHEP(2019)·10 citations
2. 02*

   Production and polarization of prompt $J/\psi$ in the improved color evaporation model using the $k_T$-factorization approach

   Vincent Cheung🇺🇸 · Ramona Vogt🇺🇸

   We calculate the polarization of prompt $J/\psi$ production in the improved color evaporation model at leading order employing the $k_T$-factorization approach. In this paper, we present the polarization parameter ${\lambda }_{\vartheta }$ of prompt $J/\psi$ as a function of transverse momentum in $p+p$ and $p$ + A collisions to compare with data in the helicity, Collins-Soper and Gottfried-Jackson frames. We also present calculations of the charmonium production cross sections as a function of rapidity and transverse momentum. This is the first $p_T$-dependent calculation of charmonium polarization in the improved color evaporation model. We find agreement with both charmonium cross sections and polarization measurements.

   hep-phPRD(2018)·77 citations
3. 03*

   U(1)' mediated decays of heavy sterile neutrinos in MiniBooNE

   Peter Ballett🇬🇧 · Silvia Pascoli🇬🇧 · Mark Ross-Lonergan🇺🇸

   The MiniBooNE low-energy excess is a longstanding problem which has received further confirmation recently with a reanalysis using newly collected data, with the anomaly now at the $4.8\sigma$ level. In this letter we propose a novel explanation which advocates a low-energy sector containing $Z^{\prime }$ bosons with GeV-scale masses and sterile neutrinos with masses around $100$-$500$ MeV. We show that this scenario can provide an excellent spectral agreement with the MiniBooNE low-energy excess in the form of $Z^{\prime }$-mediated neutral current production of heavy sterile states, a fraction of whose subsequent decay to $e^{+}{e}^{-}$ pairs are misidentified as single electron-like electromagnetic showers. Our model inscribes itself in the broad class of models in which sterile neutrinos are charged under novel interactions, allowing new couplings to hidden-sector physics. Alongside the electron-like MiniBooNE signature this model also predicts a novel, low-background, signal in LArTPC detectors such as MicroBooNE consisting of two distinguishable electron-like electromagnetic showers originating from a single vertex with no associated hadronic activity.

   hep-phPRD(2019)·143 citations
4. 04*

   Single-top production in the Standard Model and beyond

   Nikolaos Kidonakis🇺🇸

   I present high-order calculations for single-top production in the Standard Model and in models with anomalous top-quark couplings. Theoretical results are presented for total cross sections and top-quark transverse momentum and rapidity distributions for the $t$ and $s$ single-top channels as well as for the associated production of a top quark with a $W$ boson in the Standard Model. Corrections from soft-gluon emission though NNNLO are included. I also show results for the associated production of a top quark with a $Z$ boson in processes involving anomalous top-quark couplings.

   hep-ph7 citations
5. 05*

   Theoretical results for charged-Higgs production

   Nikolaos Kidonakis🇺🇸

   I discuss charged-Higgs production via two different processes: in association with a top quark, and in association with a $W$ boson. I present total cross sections and differential distributions that include higher-order corrections from soft and collinear gluon emission through aN${}^3$LO. I show that these radiative corrections are significant.

   hep-ph2 citations
6. 06*

   Charm rescattering contribution in rare $B_c^{+}\to K^{+}{K}^{-}{\pi }^{+}$ decay

   Ignacio Bediaga🇧🇷 · Tobias Frederico🇧🇷 · Patricia C Magalhaes🇧🇷

   Following the experimental results from LHCb on the rare decay $B_c^{+}\to K^{-}{K}^{+}{\pi }^{+}$, we investigate the possibility where this process is dominated by a double charm rescattering. The $B_c$ decay to double charm channels have a weak topology that is favoured in comparison with the direct production of $K^{-}{K}^{+}{\pi }^{+}$ in the final state, suppressed by quark annihilation. The decay amplitude for $B_c^{+}\to K^{-}{K}^{+}{\pi }^{+}$ with $B_c$ decaying first to double charm channels is described by a charm penguin diagram, represented by charm hadronic triangle loops, which reach the final state of interest after $D\bar{D}\to K\bar{K}$ or $D^{+}{D}_s^{-}\to {\pi }^{+}{K}^{-}$ transitions. We show that these processes give rise to non-resonant amplitudes with a clear signature in the Dalitz plot. In a near future, the new data from LHCb run II will be able to confirme if the main hypotheses of this work is correct and the dominant mechanism to produce $K^{+}{K}^{+}{\pi }^{-}$ from the decay of $B_c^{+}$ is through charm rescattering.

   hep-phhep-exPLB(2018)·7 citations
7. 07*

   $\rho$-meson leptoproduction as testfield for the unintegrated gluon distribution in the proton

   Andrèe Dafne Bolognino🇮🇹 · Francesco Giovanni Celiberto🇪🇸 · Dmitry Yu. Ivanov🇷🇺 · Alessandro Papa🇮🇹

   The gluon content of the proton is embodied by the unintegrated gluon distribution (UGD), which has universal validity. In literature many models of UGD have been proposed so far. The polarized $\rho$-meson leptoproduction at HERA offers a nowadays unexplored testfield to discriminate among existing models of UGD, via the comparison with theoretical predictions formulated in the $\kappa$-factorization approach.

   hep-phFrascati Phys.Ser.(2018)·65 citations
8. 08*

   Recent Anomalies in B Physics

   Ying Li🇨🇳 · Cai-Dian Lu🇨🇳

   $B$ physics plays important roles in searching for the new physics (NP) beyond the standard model (SM). Recently, some deviations between experimental data and SM predictions were reported, namely $R(D^{(\ast )})$, $P_5^{\prime }$ and $R_{K^{(\ast )}}$ anomalies. If these anomalies were further confirmed in future, they would be unambiguous hints of NP. Theoretically, in order to explain these anomalies, a large number of models have been proposed, such as models including leptoquark or $Z^{\prime }$. However, these new particles have not been discovered directly in LHC. Moreover, the models should pass the examination of $B_s\to {\mu }^{+}{\mu }^{-}$ and $B_s^0-{\bar{B}}_s^0$ mixing. In future, the analysis of data taken during the ongoing Run 2 of the LHC and the forthcoming Belle-II will present new insight both into the observables of interest and into new strategies to control uncertainties. Theoretically, the existed models should be further tested; and more NP models are welcomed to explain these anomalies simultaneously without affecting other measurements consistent with SM.

   hep-phhep-exSci.Bull.(2018)·72 citations
9. 09*

   Modular $A_4$ invariance and neutrino mixing

   Tatsuo Kobayashi🇯🇵 · Naoya Omoto🇯🇵 · Yusuke Shimizu🇯🇵 · Kenta Takagi🇯🇵 · Morimitsu Tanimoto🇯🇵 · Takuya H. Tatsuishi🇯🇵

   We study the phenomenological implications of the modular symmetry $\Gamma (3)\simeq A_4$ of lepton flavors facing recent experimental data of neutrino oscillations. The mass matrices of neutrinos and charged leptons are essentially given by fixing the expectation value of modulus $\tau$, which is the only source of modular invariance breaking. We introduce no flavons in contrast with the conventional flavor models with $A_4$ symmetry. We classify our neutrino models along with the type I seesaw model, the Weinberg operator model and the Dirac neutrino model. In the normal hierarchy of neutrino masses, the seesaw model is available by taking account of recent experimental data of neutrino oscillations and the cosmological bound of sum of neutrino masses. The predicted ${\sin }^2{\theta }_{23}$ is restricted to be larger than $0.54$ and ${\delta }_{CP}=\pm (50^{\circ }\text{mbox}--180^{\circ })$. Since the correlation of ${\sin }^2{\theta }_{23}$ and ${\delta }_{CP}$ is sharp, the prediction is testable in the future. It is remarkable that the effective mass $m_{ee}$ of the neutrinoless double beta decay is around $22$\,meV while the sum of neutrino masses is predicted to be $145$\,meV. On the other hand, for the inverted hierarchy of neutrino masses, only the Dirac neutrino model is consistent with the experimental data.

   hep-phJHEP(2018)·211 citations
10. 10*

    Contribution of the $a_1$ meson to the axial nucleon-to-$\Delta$ transition form factors

    Y. Unal🇹🇷 · A. Kucukarslan🇹🇷 · S. Scherer🇩🇪

    We analyze the low-$Q^2$ behavior of the axial form factor $G_A(Q^2)$, the induced pseudoscalar form factor $G_P(Q^2)$, and the axial nucleon-to-$\Delta$ transition form factors $C_5^A(Q^2)$ and $C_6^A(Q^2)$. Building on the results of chiral perturbation theory, we first discuss $G_A(Q^2)$ in a chiral effective-Lagrangian model including the $a_1$ meson and determine the relevant coupling parameters from a fit to experimental data. With this information, the form factor $G_P(Q^2)$ can be predicted. For the determination of the transition form factor $C_5^A(Q^2)$ we make use of an SU(6) spin-flavor quark-model relation to fix two coupling constants such that only one free parameter is left. Finally, the transition form factor $C_6^A(Q^2)$ can be predicted in terms of $G_P(Q^2)$, the mean-square axial radius $⟨r_A^2⟩$, and the mean-square axial nucleon-to-$\Delta$ transition radius $⟨r_{AN\Delta }^2⟩$.

    hep-phhep-exnucl-exnucl-thPRD(2019)·6 citations
11. 11*

    The thermal proton yield anomaly in Pb-Pb collisions at the LHC and its resolution

    Anton Andronic🇩🇪 · Peter Braun-Munzinger🇩🇪 · Bengt Friman🇩🇪 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱 · Johanna Stachel🇩🇪

    We propose a resolution of the discrepancy between the proton yield predicted by the statistical hadronization approach and data on hadron production in ultra-relativistic nuclear collisions at the LHC. Applying the S-matrix formulation of statistical mechanics to include pion-nucleon interactions, we reexamine their contribution to the proton yield, taking resonance widths and the presence of nonresonant correlations into account. The effect of multi-pion-nucleon interactions is estimated using lattice QCD results on the baryon-charge susceptibility. We show that a consistent implementation of these features in the statistical hadronization model, leads to a reduction of the predicted proton yield, which then quantitatively matches data of the ALICE collaboration for Pb-Pb collisions at the LHC.

    hep-phhep-exPLB(2019)·120 citations
12. 12*

    Collective Effects: the viewpoint of HEP MC codes

    Torbjörn Sjöstrand🇸🇪

    Collective effects are observed in high-multiplicity pp events, similar to the signals traditionally attributed to the formation of a Quark Gluon Plasma in heavy ion collisions. In core--corona models it is assumed that a partial plasma formation is indeed possible also in pp, but here the focus is on several recent models that attempt to explain pp data without invoking plasma formation. These attempts are partly successful, but there is still not a unified framework.

    hep-phnucl-thNPA(2019)·18 citations
13. 13*

    Hadronic production of the doubly charmed baryon via the proton-nucleus and the nucleus-nucleus collisions at the RHIC and LHC

    Gu Chen🇨🇳 · Chao-Hsi Chang🇨🇳 · Xing-Gang Wu🇨🇳

    We present a detailed discussion on the doubly charmed baryon ${\Xi }_{cc}$ production at the RHIC and LHC via the proton-nucleus ($p$-N) and nucleus-nucleus (N-N) collision modes. The extrinsic charm mechanism via the subprocesses $g+c\to (cc)[n]+\bar{c}$ and $c+c\to (cc)[n]+g$ together with the gluon-gluon fusion mechanism via the subprocess $g+g\to (cc)[n]+\bar{c}+\bar{c}$ have been taken into consideration, where the intermediate diquark is in $[n]={[}^1{S}_0{]}_6$-state or ${[}^3{S}_1{]}_{\bar{3}}$-state, respectively. Total and differential cross sections have been discussed under various collision energies. To compare with the ${\Xi }_{cc}$ production via proton-proton collision mode at the LHC, we observe that sizable ${\Xi }_{cc}$ events can also be generated via $p$-N and N-N collision modes at the RHIC and LHC. For examples, about $8.1\times 10^7$ and $6.7\times 10^7$ ${\Xi }_{cc}$ events can be accumulated in $p$-Pb and Pb-Pb collision modes at the LHC within one operation year.

    hep-phEPJC(2018)·19 citations
14. 14*

    Updating spin-dependent Regge intercepts

    Steven D. Bass🇵🇱 · Magdalena Skurzok🇵🇱 · Pawel Moskal🇵🇱

    We use new high statistics data from CLAS and COMPASS on the nucleon's spin structure function at low Bjorken x and low virtuality, Q^2 < 0.5 GeV^2, together with earlier measurements from the SLAC E-143, HERMES and GDH experiments to estimate the effective intercept(s) for spin dependent Regge theory. We find alpha_{a_1} = 0.31 \pm 0.04 for the intercept describing the high-energy behaviour of spin dependent photoabsorption together with a new estimate for the high-energy part of the Gerasimov-Drell-Hearn sum-rule, -15 \pm 2 mu b from photon-proton centre-of-mass energy greater than 2.5 GeV. Our value of alpha_[a_1} suggests QCD physics beyond a simple straight-line a_1 trajectory.

    hep-phnucl-exnucl-thPRC(2018)·15 citations
15. 15*

    Precision Dijet Acoplanarity Tomography of the Chromo Structure of Perfect QCD Fluids

    M. Gyulassy🇺🇸 · P. Levai🇭🇺 · J. Liao🇺🇸 · S. Shi🇺🇸 · F. Yuan🇺🇸 · X.N. Wang🇨🇳

    Dijet acoplanarity is dominated by vacuum (Sudakov) pQCD radiation even in Pb+Pb collisions, but future higher precision measurements of the tails of the acoplanarity distributions can help to resolve {\em separately} the medium opacity, $\chi =L/\lambda$, and the color screening scale ${\mu }^2$ from the path averaged BDMS saturation scale $Q_s^2[\chi ,\mu ]=\int dL\hat{q}(E,T(L))\propto {\mu }^{2}L/\lambda$, that is already well constrained by nuclear modification factor data on $R_{AA}(p_T)$. We compare Gaussian (BDMS) and non-Gaussian (GLV) models of medium broadening of vacuum (Sudakov) induced acoplanarity distributions in A+A. With few percent accuracy on the ratio of A+A to p+p distributions, experiments can easily identify non-Gaussian Landau and Rutherford tails due to multiple collisions. However, we find that sub-percent precision will be required to constrain $\chi$ and $\mu$ separately from $Q_s$.

    hep-phnucl-thNPA(2019)·16 citations
16. 16*

    Neutrino induced reactions in core-collapse supernovae: effects on the electron fraction

    M. M. Saez🇦🇷 · O. Civitarese🇦🇷 · M. E. Mosquera🇦🇷

    Neutrino induced reactions are a basic ingredient in astrophysical processes like star evolution. The existence of neutrino oscillations affects the rate of nuclear electroweak decays which participates in the chain of events that determines the fate of the star. Among the processes of interest, the production of heavy elements in core-collapse supernovae is strongly dependent upon neutrino properties, like the mixing between different species of neutrinos. In this work we study the effects of neutrino oscillations upon the electron fraction as a function of the neutrino mixing parameters, for two schemes: the $1+1$ scheme (one active neutrino and one sterile neutrino) and the $2+1$ scheme (two active neutrinos and one sterile neutrino). We have performed this analysis considering a core-collapse supernovae and determined the physical conditions needed to activate the nuclear reaction chains involved in the r-process. We found that the interactions of the neutrinos with matter and among themselves and the initial amount of sterile neutrinos in the neutrino-sphere might change the electron fraction, therefore affecting the onset of the r-process. We have set constrains on the active-sterile neutrino mixing parameters. They are the square-mass-difference $\Delta m_{14}^2$, the mixing angle ${\sin }^{2}2{\theta }_{14}$, and the hindrance factor ${\xi }_s$ for the occupation of sterile neutrinos. The calculations have been performed for different values of $X_{\alpha }$, which is the fraction of $\alpha$-particles. For $X_{\alpha }=0$ the r-process is taking place if $\Delta m_{14}^2\ge 2{\mathrm{eV}}^2$, ${\sin }^{2}2{\theta }_{14}<0.8$ and ${\xi }_s<0.5$. For larger values of $X_{\alpha }$ the region of parameters is strongly reduced. The present results are compared to results available in the literature.

    hep-phastro-ph.SRnucl-thInt.J.Mod.Phys.D(2018)·5 citations
17. 17*

    Molière Scattering in Quark-Gluon Plasma: Finding Point-Like Scatterers in a Liquid

    Francesco D'Eramo🇮🇹 · Krishna Rajagopal🇺🇸 · Yi Yin🇺🇸

    By finding rare (but not exponentially rare) large-angle deflections of partons within a jet produced in a heavy ion collision, or of such a jet itself, experimentalists can find the weakly coupled short-distance quark and gluon particles (scatterers) within the strongly coupled liquid quark-gluon plasma (QGP) produced in heavy ion collisions. This is the closest one can come to probing QGP via a scattering experiment and ultimately learning how a strongly coupled liquid emerges from an asymptotically free gauge theory. The short-distance, particulate, structure of liquid QGP can be revealed in events in which a jet parton resolves, and scatters off, a parton from the droplet of QGP. The probability for picking up significant transverse momentum via a single scattering was calculated previously, but only in the limit of infinite parton energy which means zero angle scattering. Here, we provide a leading order perturbative QCD calculation of the Molière scattering probability for incident partons with finite energy, scattering at a large angle. We set up a thought experiment in which an incident parton with a finite energy scatters off a parton constituent within a "brick" of QGP, which we treat as if it were weakly coupled, as appropriate for scattering with large momentum transfer, and compute the probability for a parton to show up at a nonzero angle with some energy. We include all relevant channels, including those in which the parton that shows up at a large angle was kicked out of the medium as well as the Rutherford-like channel in which what is seen is the scattered incident parton. The results that we obtain will serve as inputs to future jet Monte Carlo calculations and can provide qualitative guidance for how to use future precise, high statistics, suitably differential measurements of jet modification in heavy ion collisions to find the scatterers within the QGP liquid.

    hep-phnucl-exnucl-thJHEP(2019)·79 citations
18. 18*

    The abelian gauge-Yukawa $\beta$-functions at large $N_f$

    Tommi Alanne🇩🇪 · Simone Blasi🇩🇪

    We study the impact of the Yukawa interaction in the large-$N_f$ limit to the abelian gauge theory. We compute the coupled $\beta$-functions for the system in a closed form at $\mathcal{O}(1/N_f)$.

    hep-phhep-thPRD(2018)·17 citations
19. 19*

    Reactor Neutrino Spectral Distortions Play Little Role in Mass Hierarchy Experiments

    D. L. Danielson (1 and 2)🇺🇸 · A. C. Hayes (1)🇺🇸 · G. T. Garvey (3 and 4) ((1) Theoretical Division, Los Alamos National Laboratory, (2) Department of Physics, University of California at Davis, (3) Physics Division, Los Alamos National Laboratory, (4) Department of Physics, University of Washington)🇺🇸

    The Coulomb enhancement of low energy electrons in nuclear beta decay generates sharp cutoffs in the accompanying antineutrino spectrum at the beta decay endpoint energies. It has been conjectured that these features will interfere with measuring the effect of a neutrino mass hierarchy on an oscillated nuclear reactor antineutrino spectrum. These sawtooth-like features will appear in detailed reactor antineutrino spectra, with characteristic energy scales similar to the oscillation period critical to neutrino mass hierarchy determination near a 53 km baseline. However, these sawtooth-like distortions are found to contribute at a magnitude of only a few percent relative to the mass hierarchy-dependent oscillation pattern in Fourier space. In the Fourier cosine and sine transforms, the features that encode a neutrino mass hierarchy dominate by over sixteen (thirty-three) times in prominence to the maximal contribution of the sawtooth-like distortions from the detailed energy spectrum, given $3.2\%/\sqrt{E_{vis.}/\mathrm{MeV}}$ (perfect) detector energy resolution. The effect of these distortions is shown to be negligible even when the uncertainties in the reactor spectrum, oscillation parameters, and counting statistics are considered. This result is shown to hold even when the opposite hierarchy oscillation patterns are nearly degenerate in energy space, if energy response nonlinearities are controlled to below 0.5\%. Therefore with accurate knowledge of detector energy response, the sawtooth-like features in reactor antineutrino spectra will not significantly impede neutrino mass hierarchy measurements using reactor antineutrinos.

    hep-phhep-exphysics.ins-detPRD(2019)·12 citations
20. 20*

    Gravitational floating orbits around hairy black holes

    Jun Zhang🇨🇦 · Huan Yang🇨🇦

    We show that gravitational floating orbits may exist for black holes with rotating hairs. These black hole hairs could originate from the superradiant growth of a light axion field around the rotating black holes. If a test particle rotates around the black hole, its tidal field may resonantly trigger the dynamical transition between a co-rotating state and a dissipative state of the axion cloud. A tidal bulge is generated by the beating of modes, which feeds angular momentum back to the test particle. Following this mechanism, an extreme-mass-ratio-inspiral (EMRI) system, as a source for LISA, may face delayed merger as the EMRI orbit stalls by the tidal response of the cloud, until the cloud being almost fully dissipated. If the cloud depletes slower than the average time separation between EMRI mergers, it may lead to interesting interaction between multiple EMRI objects at comparable radii. Inclined EMRIs are also expected to migrate towards the black hole equatorial plane due to the tidal coupling and gravitational-wave dissipation. Floating stellar-mass back holes or stars around the nearby intermediate-mass black holes may generate strong gravitational-wave emission detectable by LISA.

    ↳ gr-qcastro-ph.HEhep-phPRD(2019)·105 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.