Mon·Oct 2, 2017Monday·October 2, 2017

1. 01*

   Study of $J/\psi$ $\to$ $D_{s,d}V$ decays with perturbative QCD approach

   Yueling Yang🇨🇳 · Junfeng Sun🇨🇳 · Jie Gao🇨🇳 · Qin Chang🇨🇳 · Jinshu Huang🇨🇳 · Gongru Lu🇨🇳

   Inspired by the recent measurements on two-body nonleptonic $J/\psi$ weak decay at BESIII, the charm-changing $J/\psi$ $\to$ $D_{s,d}V$ weak decays are studied with perturbative QCD approach, where $V$ denotes $\rho$ and $K^{\ast }$ vector mesons. It is found that branching ratio for $J/\psi$ $\to$ $D_s\rho$ decay can reach up to $\mathcal{O}(10^{-9})$, which is within the potential measurement capability of the future high-luminosity experiments.

   hep-phhep-exInt.J.Mod.Phys.A(2016)·4 citations
2. 02*

   ${\rm Y}(nS)$ $\to$ $B_c\rho$, $B_c{K}^{\ast }$ decays with perturbative QCD approach

   Junfeng Sun🇨🇳 · Yueling Yang🇨🇳 · Jinshu Huang🇨🇳 · Gongru Lu🇨🇳 · Qin Chang🇨🇳

   Inspired by the potential prospects of ${\rm Y}(nS)$ data samples ($n$ $=$ $1$, $2$, $3$) at LHC and SuperKEKB, ${\rm Y}(nS)$ $\to$ $B_c\rho$, $B_c{K}^{\ast }$ decays are studied phenomenologically with pQCD approach. Branching ratios for ${\rm Y}(nS)$ $\to$ $B_c\rho$ and $B_c{K}^{\ast }$ decays are estimated to reach up to $\mathcal{O}(10^{-11})$ and $\mathcal{O}(10^{-12})$, respectively. Given the identification and detection efficiency of final states, searching for these weak decay modes should be fairly challenging experimentally in the future.

   hep-phhep-exNPB(2016)·5 citations
3. 03*

   Collectivity and manifestations of minimum-bias jets in high-energy nuclear collisions

   Thomas A. Trainor🇺🇸

   Collectivity, as interpreted to mean flow of a dense medium in high-energy A-A collisions described by hydrodynamics, has been attributed to smaller collision systems -- p-A and even p-p collisions -- based on recent analysis of LHC data. However, alternative methods reveal that some data features attributed to flows are actually manifestations of minimum-bias (MB) jets. In this presentation I review the differential structure of single-particle $p_t$ spectra from SPS to LHC energies in the context of a two-component (soft + hard) model (TCM) of hadron production. I relate the spectrum hard component to measured properties of isolated jets. I use the spectrum TCM to predict accurately the systematics of ensemble-mean ${\bar{p}}_t$ in p-p, p-A and A-A collision systems over a large energy interval. Detailed comparisons of the TCM with spectrum and correlation data suggest that MB jets play a dominant role in hadron production near midrapidity. Claimed flow phenomena are better explained as jet manifestations agreeing quantitatively with measured jet properties.

   hep-phEPJ Web Conf.(2018)·0 citations
4. 04*

   The Mass and Decay Properties of the $1^{-+}$ Light Hybrid Meson

   Zhuo-Ran Huang🇨🇳 · Hong-Ying Jin🇨🇳 · T.G. Steele🇨🇦 · Zhu-Feng Zhang🇨🇳

   We calculate the complete form of the dimension-8 condensate contributions in the two-point correlator of the ($1^{-+}$,$0^{++}$) light hybrid current considering the operator mixing under renormalization. We find the inclusion these higher power corrections as well as the update of $⟨g^3{G}^3⟩$ increase the QCD sum rule mass prediction for the $1^{-+}$ light hybrid. The obtained conservative mass range 1.72--2.60 GeV does not favor the ${\pi }_1(1400)$ and the ${\pi }_1(1600)$ to be pure hybrid states and suggests the ${\pi }_1(2015)$ observed by E852 is more likely to have much of a hybrid constituent. We also study the $b_1\pi$ and $\rho \pi$ decay patterns of the $1^{-+}$ light hybrid with light-cone QCD sum rules. We obtain a relatively large partial decay width of the $b_1\pi$ mode, which is consistent with the predictions from the flux tube models and lattice QCD. More interestingly, using the tensor interpolating current we find the partial decay width of the $\rho \pi$ mode is small due to the absence of the leading twist contribution in the light-cone expansion of the correlation function.

   hep-phNucl.Part.Phys.Proc.(2018)·1 citation
5. 05*

   Neutrino Parameters from Reactor and Accelerator Neutrino Experiments

   Manfred Lindner🇩🇪 · Werner Rodejohann🇩🇪 · Xun-Jie Xu🇩🇪

   We revisit correlations of neutrino oscillation parameters in reactor and long-baseline neutrino oscillation experiments. A framework based on an effective value of ${\theta }_{13}$ is presented, which can easily reproduce experimental results. It also clarifies why current and future long-baseline experiments will have less precision on values around ${\delta }_{CP}=\pm \pi /2$ than on values around ${\delta }_{CP}=0$. Optimization potential for the determination of the theoretically very interesting values around ${\delta }_{CP}=-\pi /2$ is also pointed out, which would require that future runs of accelerator experiments are not equally shared $1:1$ in neutrino and antineutrino modes, but rather $2:1$. Recent hints on the CP phase and the mass ordering are then considered from the point of view that different reactor and long-baseline neutrino experiments provide currently different best-fit values of ${\theta }_{13}$ and ${\theta }_{23}$. We point out that the significance of the hints changes for the different available best-fit values.

   hep-phhep-exPRD(2018)·4 citations
6. 06*

   Scenarios with low mass Higgs bosons in the heavy supersymmetry

   M. N. Dubinin (1)🇷🇺 · E. Yu. Petrova (1 and 2) ((1) Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, (2) Physics Department, Lomonosov Moscow State University)🇷🇺

   Possible realistic scenarios are investigated in the minimal supersymmetric standard model (MSSM) Higgs sector extended by dimension-six effective operators. The CP-odd Higgs boson with low mass around 30--90 GeV could be consistently introduced in the regime of large threshold corrections to the effective MSSM two-doublet Higgs potential.

   hep-phInt.J.Mod.Phys.A(2018)·5 citations
7. 07*

   Future prospects for exploring present day anomalies in flavour physics measurements with Belle II and LHCb

   Johannes Albrecht🇩🇪 · Florian Bernlochner🇩🇪 · Matthew Kenzie🇬🇧 · Stefanie Reichert🇩🇪 · David Straub🇩🇪 · Alison Tully🇬🇧

   A range of flavour physics observables show tensions with their corresponding Standard Model expectations: measurements of leptonic flavour-changing neutral current processes and ratios of semi-leptonic branching fractions involving different generations of leptons show deviations of the order of four standard deviations. If confirmed, either would be an intriguing sign of new physics. In this manuscript, we analyse the current experimental situation of such processes and for the first time estimate the combined impact of the future datasets of the Belle II and LHCb experiments on the present tensions with the Standard Model expectations by performing scans of the new physics contribution to the Wilson coefficients. In addition, the present day and future sensitivity of tree-level CKM parameters, which offer orthogonal tests of the Standard Model, are explored. Three benchmark points in time are chosen for a direct comparison of the estimated sensitivity between the experiments. A high complementarity between the future sensitivity achieved by the Belle II and LHCb experiments is observed due to their relative strengths and weaknesses. We estimate that all of the anomalies considered here will be either confirmed or ruled out by both experiments independently with very high significance by the end of data-taking at Belle II and the LHCb upgrade.

   hep-phhep-ex61 citations
8. 08*

   Low temperature electroweak phase transition in the Standard Model with hidden scale invariance

   Suntharan Arunasalam🇦🇺 · Archil Kobakhidze🇦🇺 · Cyril Lagger🇦🇺 · Shelley Liang🇦🇺 · Albert Zhou🇦🇺

   We discuss a cosmological phase transition within the Standard Model which incorporates spontaneously broken scale invariance as a low-energy theory. In addition to the Standard Model fields, the minimal model involves a light dilaton, which acquires a large vacuum expectation value (VEV) through the mechanism of dimensional transmutation. Under the assumption of the cancellation of the vacuum energy, the dilaton develops a very small mass at 2-loop order. As a result, a flat direction is present in the classical dilaton-Higgs potential at zero temperature while the quantum potential admits two (almost) degenerate local minima with unbroken and broken eletroweak symmetry. We found that the cosmological electroweak phase transition in this model can only be triggered by a QCD chiral symmetry breaking phase transition at low temperatures, $T\lesssim 132$ MeV. Furthermore, unlike the standard case, the universe settles into the chiral symmetry breaking vacuum via a first-order phase transition which gives rise to a stochastic gravitational background with a peak frequency $\sim 10^{-8}$ Hz as well as triggers the production of approximately solar mass primordial black holes. The observation of these signatures of cosmological phase transitions together with the detection of a light dilaton would provide a strong hint of the fundamental role of scale invariance in particle physics.

   hep-phastro-ph.COhep-thPLB(2018)·36 citations
9. 09*

   Improved theoretical description of Mueller-Navelet jets at LHC

   Dimitri Colferai🇮🇹 · Federico Deganutti🇺🇸 · Alessandro Niccoli🇮🇹

   We present a method for improving the phenomenological description of Mueller-Navelet jets at LHC, which is based on matching the BFKL resummation with fixed order calculations. We point out the need of a consistent identification of jets between experimental measurements and theoretical descriptions. We hope as well to motivate an extensive analysis of MN jets at LHC in run 2.

   hep-ph5 citations
10. 10*

    Sensitivity to neutrino decay with atmospheric neutrinos at INO

    Sandhya Choubey🇮🇳 · Srubabati Goswami🇮🇳 · Chandan Gupta🇮🇳 · S. M. Lakshmi🇮🇳 · Tarak Thakore🇺🇸

    Sensitivity of the magnetised Iron CALorimeter (ICAL) detector at the proposed India-based Neutrino Observatory (INO) to invisible decay of the mass eigenstate ${\nu }_3$ using atmospheric neutrinos is explored. A full three-generation analysis including earth matter effects is performed in a framework with both decay and oscillations. The wide energy range and baselines offered by atmospheric neutrinos are shown to be excellent for constraining the ${\nu }_3$ lifetime. We find that with an exposure of 500 kton-yr the ICAL atmospheric experiment could constrain the ${\nu }_3$ lifetime to ${\tau }_3/m_3>1.51\times 10^{-10}$ s/eV at the 90\% C.L. This is two orders of magnitude tighter than the bound from MINOS. The effect of invisible decay on the precision measurement of ${\theta }_{23}$ and $|\Delta m_{32}^2|$ is also studied.

    hep-phPRD(2018)·47 citations
11. 11*

    On the production of hidden-flavored hadronic states at high energy

    Wei Wang🇨🇳

    I discuss the production mechanism of hidden-flavored hadrons at high energy. Using $e^{+}{e}^{-}$ collisions and light-meson pair production in high energy exclusive processes, I demonstrate that hidden quark pairs do not necessarily participate in short-distance hard scattering. Implications are then explored in a few examples. Finally, I discuss the production mechanism of $X(3872)$ in hadron collisions, where some misunderstandings have arisen in the literature.

    hep-phCPC(2018)·14 citations
12. 12*

    On the coverage of the pMSSM by simplified model results

    Ursula Laa🇫🇷

    ATLAS and CMS have been performing a large number of searches for physics beyond the Standard Model (BSM). In particular results of supersymmetry (SUSY) searches are typically interpreted in the context of simplified models. While mass limits obtained in this manner are highly model dependent, cross section upper limits (or efficiency maps) may be used to obtain constraints on generic BSM scenarios without any further event and detector simulation. This procedure has been automatised in the public tool SModelS, which first decomposes the generic scenario into its simplified model components which can then be tested directly against the experimental constraints in the SModelS database. We briefly introduce SModelS and then discuss how the coverage by simplified model results compares to what can be obtained in a full simulation study for the example of the 19 parameter phenomenological MSSM (pMSSM). Considering all parameter points that ATLAS has tested in a comprehensive study [1], we find that about 60 % of the points excluded by ATLAS can be excluded from simplified model constraints. This fraction could be improved by considering currently `missing' simplified model topologies. We show that in particular topologies with asymmetric branches are often important, while long cascade decays with more than one intermediate particle are less relevant. A particularly interesting asymmetric branch topology is a 3 jet + $E_T^{\mathrm{miss}}$ signature arising from gluino-squark production.

    hep-phhep-exPoS(2017)·4 citations
13. 13*

    Implications of the Fermi-LAT Pass 8 Galactic Center Excess on Supersymmetric Dark Matter

    Abraham Achterberg🇳🇱 · Melissa van Beekveld🇳🇱 · Sascha Caron🇳🇱 · Germán A. Gómez-Vargas🇨🇱 · Luc Hendriks🇳🇱 · Roberto Ruiz de Austri🇪🇸

    The Fermi Collaboration has recently updated their analysis of gamma rays from the center of the Galaxy. They reconfirm the presence of an unexplained emission feature which is most prominent in the region of $1-10$ GeV, known as the Galactic Center GeV excess (GCE). Although the GCE is now firmly detected, an interpretation of this emission as a signal of self-annihilating dark matter (DM) particles is not unambiguously possible due to systematic effects in the gamma-ray modeling estimated in the Galactic Plane. In this paper we build a covariance matrix, collecting different systematic uncertainties investigated in the Fermi Collaboration's paper that affect the GCE spectrum. We show that models where part of the GCE is due to annihilating DM can still be consistent with the new data. We also re-evaluate the parameter space regions of the minimal supersymmetric Standard Model (MSSM) that can contribute dominantly to the GCE via neutralino DM annihilation. All recent constraints from DM direct detection experiments such as PICO, LUX, PandaX and Xenon1T, limits on the annihilation cross section from dwarf spheroidal galaxies and Large Hadron Collider limits are considered in this analysis. Due to a slight shift in the energy spectrum of the GC excess with respect to the previous Fermi analysis, and the recent limits from direct detection experiments, we find a slightly shifted parameter region of the MSSM compared to our previous analysis that is consistent with the GCE. Neutralinos with a mass between $85-220$ GeV can describe the excess via annihilation into a pair of $W$-bosons or top quarks. Remarkably, there are low fine-tuning models among the regions that we have found. The complete set of solutions will be probed by upcoming direct detection experiments and with dedicated searches in the upcoming data of the Large Hadron Collider.

    hep-phastro-ph.COastro-ph.HEJCAP(2017)·25 citations
14. 14*

    A partially composite Goldstone Higgs

    Tommi Alanne🇩🇪 · Diogo Buarque Franzosi🇩🇪 · Mads T. Frandsen🇩🇰

    We consider a model of dynamical electroweak symmetry breaking with a partially composite Goldstone Higgs. The model is based on a strongly-interacting fermionic sector coupled to a fundamental scalar sector via Yukawa interactions. The SU(4) x SU(4) global symmetry of these two sectors is broken to a single SU(4) via Yukawa interactions. Electroweak symmetry breaking is dynamically induced by condensation due to the strong interactions in the new fermionic sector which further breaks the global symmetry SU(4) to Sp(4). The Higgs boson arises as a partially composite state which is an exact Goldstone boson in the limit where SM interactions are turned off. Terms breaking the SU(4) global symmetry explicitly generate a mass for the Goldstone Higgs. The model realizes in different limits both (partially) composite Higgs and (bosonic) Technicolor models, thereby providing a convenient unified framework for phenomenological studies of composite dynamics. It is also a dynamical extension of the recent elementary Goldstone-Higgs model.

    hep-phPRD(2017)·30 citations
15. 15*

    Electroweak resonances in HEFT

    Felipe J. Llanes-Estrada · Rafael L. Delgado y Antonio Dobado

    Due to the gap between the known 100 GeV scale and new physics if any, it is natural to employ an effective one-loop Lagrangian (HEFT) for the particles of the Electroweak Symmetry Breaking Sector (W_L, Z_L and h). To describe any new particles and resonances that may be found at the LHC we employ its unitarized amplitudes, valid even in the presence of new strong interactions. We have assessed the systematics by comparing several such methods, and find that they give qualitatively similar results and succesfully produce unitary amplitudes in the nonperturbative regime. We are thus in a position to describe new physics in the 0.5 TeV-3 TeV (region of validity of our approximations: the effective theory and the equivalence theorem to substitute W_L, Z_L by the Goldstone bosons of electroweak symmetry breaking). We have also computed the coupling of the EWSBS to the top-antitop and two-photon channels to describe resonances that decay through them or to study their photon-photon production, for example. The approach is universal and useful for many BSM theories at low energy.

    hep-ph3 citations
16. 16*

    Top quark physics in the Large Hadron Collider era

    Michael Russell🇬🇧

    We explore various aspects of top quark phenomenology at the Large Hadron Collider and proposed future machines. After summarising the role of the top quark in the Standard Model (and some of its well-known extensions), we discuss the formulation of the Standard Model as a low energy effective theory. We isolate the sector of this effective theory that pertains to the top quark and that can be probed with top observables at hadron colliders, and present a global fit of this sector to currently available data from the LHC and Tevatron. Various directions for future improvement are sketched, including analysing the potential of boosted observables and future colliders, and we highlight the importance of using complementary information from different colliders. Interpretational issues related to the validity of the effective field theory formulation are elucidated throughout. Finally, we present an application of artificial neural network algorithms to identifying highly-boosted top quark events at the LHC, and comment on further refinements of our analysis that can be made.

    hep-ph4 citations
17. 17*

    New Physics Scale from Higgs Observables with Effective Dimension-6 Operators

    Sudip Jana🇺🇸 · S. Nandi🇺🇸

    No matter what the scale of new physics is, deviations from the Standard Model for the Higgs observables will indicate the existence of such a scale. We consider effective six dimensional operators, and their effects on the Higgs productions and decays to estimate this new scale. We analyze and identify the parameter space consistent with known properties of the Higgs boson using recent Run II results from ATLAS and CMS experiments corresponding to $\sim$ 37 fb${}^{-1}$ of data. We then calculate the $\bar{t}th$ productions , as well as double Higgs production at the LHC using the effective couplings, and show that these can be much different than those predicted by the Standard Model, for a wide region of allowed parameters space. These predictions can be tested in the current or the future runs of the LHC. We find that the data are consistent with the existence of a new physics scale as low as 500 GeV for a significant region of parameter space of this six-dimensional couplings with these new physics effects at the LHC. We also find that for some region of the parameter space, di-Higgs production can be much larger than that predicted by the Standard Model giving rise to the prospect of its observation even in the current run II of the LHC.

    hep-phPLB(2018)·23 citations
18. 18*

    Neutrino Mass, Leptogenesis, and Dark Matter from The Dark Sector with $U(1{)}_D$

    Wei-Min Yang🇨🇳

    I suggest a new extension of the SM by introducing a dark sector which has several new particles and a local $U(1{)}_D$ symmetry. The dark particles bring about the new and interesting physics beyond the SM. The model can generate the tiny neutrino mass by a hybrid see-saw mechanism, achieve the leptogenesis at the TeV scale, and account for the cold dark matter. All of the three things collectively arise from the dark sector. In particular, it is very feasible to test the model predictions and probe the dark sector in near future experiments.

    hep-phJHEP(2018)·4 citations
19. 19*

    Precision Higgs Measurements at the 250 GeV ILC

    Jan Strube🇺🇸

    The plan for the International Linear Collider is now being prepared as a staged design, with the first stage at 250 GeV and later stages achieving the full project specifications with 4 ab-1 at 500 GeV. This talk will present the capabilities for precision Higgs boson measurements at 250 GeV and their relation to the full ILC program. It will show that the 250 GeV stage of ILC will already provide many compelling results in Higgs physics, with new measurements not available at LHC, model-independent determinations of key parameters, and tests for and possible discrimination of a variety of scenarios for new physics.

    ↳ hep-exhep-ph0 citations
20. 20*

    QCD at finite isospin chemical potential

    Bastian B. Brandt🇩🇪 · Gergely Endrodi🇩🇪 · Sebastian Schmalzbauer🇩🇪

    We investigate the properties of QCD at finite isospin chemical potential at zero and non-zero temperatures. This theory is not affected by the sign problem and can be simulated using Monte-Carlo techniques. With increasing isospin chemical potential and temperatures below the deconfinement transition the system changes into a phase where charged pions condense, accompanied by an accumulation of low modes of the Dirac operator. The simulations are enabled by the introduction of a pionic source into the action, acting as an infrared regulator for the theory, and physical results are obtained by removing the regulator via an extrapolation. We present an update of our study concerning the associated phase diagram using 2+1 flavours of staggered fermions with physical quark masses and the comparison to Taylor expansion. We also present first results for our determination of the equation of state at finite isospin chemical potential and give an example for a cosmological application. The results can also be used to gain information about QCD at small baryon chemical potentials using reweighting with respect to the pionic source parameter and the chemical potential and we present first steps in this direction.

    ↳ hep-lathep-phnucl-thEPJ Web Conf.(2018)·69 citations
21. 21*

    Detecting Axion Stars with Radio Telescopes

    Yang Bai🇺🇸 · Yuta Hamada🇯🇵

    When axion stars fly through an astrophysical magnetic background, the axion-to-photon conversion may generate a large electromagnetic radiation power. After including the interference effects of the spacially-extended axion-star source and the macroscopic medium effects, we estimate the radiation power when an axion star meets a neutron star. For a dense axion star with $10^{-13}{M}_{\odot }$, the radiated power is at the order of $10^{11}\text{mbox}W\times (100\mu \text{mbox}eV/m_a{)}^4(B/10^{10}\text{mbox}Gauss{)}^2$ with $m_a$ as the axion particle mass and $B$ the strength of the neutron star magnetic field. For axion stars occupy a large fraction of dark matter energy density, this encounter event with a transient $\mathcal{O}(0.1\text{mbox}s)$ radio signal may happen in our galaxy with the averaged source distance of one kiloparsec. The predicted spectral flux density is at the order of $\mu$Jy for a neutron star with $B\sim 10^{13}$ Gauss. The existing Arecibo, GBT, JVLA and FAST and the ongoing SKA radio telescopes have excellent discovery potential of dense axion stars.

    ↳ astro-ph.HEhep-phPLB(2018)·53 citations
22. 22*

    Beth-Uhlenbeck approach for repulsive interactions between baryons in a hadron gas

    Volodymyr Vovchenko🇩🇪 · Anton Motornenko🇩🇪 · Mark I. Gorenstein🇺🇦 · Horst Stoecker🇩🇪

    The quantum mechanical Beth-Uhlenbeck (BU) approach for repulsive hard-core interactions between baryons is applied to the thermodynamics of a hadron gas. The second virial coefficient $a_2$ -- the "excluded volume" parameter -- calculated within the BU approach is found to be temperature dependent, and it differs dramatically from the classical excluded volume (EV) model result. At temperatures $T=100-200$ MeV, the widely used classical EV model underestimates the EV parameter for nucleons at a given value of the nucleon hard-core radius by large factors of 3-4. Previous studies, which employed the hard-core radii of hadrons as an input into the classical EV model, have to be re-evaluated using the appropriately rescaled EV parameters. The BU approach is used to model the repulsive baryonic interactions in the hadron resonance gas (HRG) model. Lattice data for the second and fourth order net baryon susceptibilities are described fairly well when the temperature dependent BU baryonic excluded volume parameter corresponds to nucleon hard-core radii of $r_c=0.25-0.3$ fm. Role of the attractive baryonic interactions is also considered. It is argued that HRG model with a constant baryon-baryon EV parameter $v_{NN}\simeq 1$ fm${}^3$ provides a simple yet efficient description of baryon-baryon interaction in the crossover temperature region.

    ↳ nucl-thhep-phPRC(2018)·34 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.