Mon·Jan 25, 2016Monday·January 25, 2016

1. 01*

   Nonperturbative True Muonium on the Light Front with TMSWIFT

   Henry Lamm🇺🇸 · Richard F. Lebed🇺🇸

   The true muonium $(\mu \bar{\mu })$ bound state presents an interesting test of light-cone quantization techniques. In addition to exhibiting the standard problems of handling non-perturbative calculations, true muonium requires correct treatment of $e\bar{e}$ Fock-state contributions. Having previously produced a crude model of true muonium using the method of iterated resolvents, our current work has focused on the inclusion of the box diagrams to improve the cutoff-dependent issues of the model. Further, a parallel computer code, TMSWIFT, allowing for smaller numerical uncertainties, has been developed. This work focuses on the current state of these efforts to develop a model of true muonium that is testable at near-term experiments.

   hep-phnucl-thphysics.comp-phFew Body Syst.(2016)·2 citations
2. 02*

   Testing ATLAS Z+MET Excess with LHC Run 2

   Xiaochuan Lu🇺🇸 · Satoshi Shirai🇩🇪 · Takahiro Terada🇰🇷

   The ATLAS collaboration reported a 3sigma excess in the search of events containing on-Z dilepton, jets, and large missing momentum (MET) in the 8 TeV LHC run. Motivated by this excess, many models of new physics have been proposed. Recently, the ATLAS and CMS collaborations reported new results for similar Z+MET channels in the 13 TeV run. In this paper, we comprehensively discuss the consistency between the proposed models and the LHC results of Run 1 and Run 2. We find that in models with heavy gluino production, there is generically some tension between the 8 TeV and 13 TeV results. On the other hand, models with light squark production provide relatively better fitting to both results.

   hep-phhep-exJHEP(2016)·2 citations
3. 03*

   New Tests of NRQCD from Quarkonia Within Jets

   Thomas Mehen🇺🇸

   I review the current status of quarkonium production theory based on the non-relativistic QCD factorization formalism (NRQCD). While this theory describes much of the world's data on J/\psi and \Upsilon production, there are still outstanding problems, most notably the polarization of quarkonia at large p_T in hadron colliders. In this talk we will present new tests of NRQCD involving the distribution of quarkonia within jets. The distribution of hadrons within jets is determined by nonperturbative functions called fragmenting jet functions (FJFs). FJFs are convolutions of fragmentation functions, evolved to the jet energy scale, with perturbatively calculable matching coefficients. I show how the FJFs for quarkonia can be calculated in NRQCD in terms of a few NRQCD long-distance matrix elements (LDME), so the dependence of the cross section on the energy fraction of the heavy quarkonium, z, is sensitive to the underlying production mechanism, and therefore provides a new test of NRQCD. The jet energy and z dependence of the cross section can be used to perform an independent extraction of NRQCD LDME. Finally, I describe ongoing work building on this result. This includes comparison of analytic resummed calculations with Monte Carlo simulations for two-jet events in e^+e^- collisions with B mesons, and three-jet events with J/\psi, as well as the definition of boost invariant jet substructure variables and calculation of a boost invariant soft function that are necessary for analytic calculations of jet cross sections at the Large Hadron Collider.

   hep-phPoS(2016)·1 citation
4. 04*

   Properties of ground state pseudo scalar and vector $c\bar{b}$ states in a relativistic quark model

   Antony Prakash Monteiro🇮🇳 · Manjunath Bhat🇮🇳 · K. B. Vijaya Kumar🇮🇳

   The phenomenological relativistic quark model (RQM) has been employed to obtain the masses of ground state pseudo scalar and vector $c\bar{b}$ states. In the frame work of RQM a study of M1 radiative decays of $c\bar{b}$ has been made. The Hamiltonian used in the investigation has confinement potential and confined one gluon exchange potential (COGEP). An overall agreement is obtained with the experimental masses and decay widths. Calculated values are compared with other theoretical models.

   hep-ph1 citation
5. 05*

   Two-loop conformal generators for leading-twist operators in QCD

   V.M. Braun🇩🇪 · A.N. Manashov🇩🇪 · S. Moch🇩🇪 · M. Strohmaier🇩🇪

   QCD evolution equations in minimal subtraction schemes have a hidden symmetry: One can construct three operators that commute with the evolution kernel and form an $SL(2)$ algebra, i.e. they satisfy (exactly) the $SL(2)$ commutation relations. In this paper we find explicit expressions for these operators to two-loop accuracy going over to QCD in non-integer $d=4-2ϵ$ space-time dimensions at the intermediate stage. In this way conformal symmetry of QCD is restored on quantum level at the specially chosen (critical) value of the coupling, and at the same time the theory is regularized allowing one to use the standard renormalization procedure for the relevant Feynman diagrams. Quantum corrections to conformal generators in $d=4-2ϵ$ effectively correspond to the conformal symmetry breaking in the physical theory in four dimensions and the $SL(2)$ commutation relations lead to nontrivial constraints on the renormalization group equations for composite operators. This approach is valid to all orders in perturbation theory and the result includes automatically all terms that can be identified as due to a nonvanishing QCD $\beta$-function (in the physical theory in four dimensions). Our result can be used to derive three-loop evolution equations for flavor-nonsinglet quark-antiquark operators including mixing with the operators containing total derivatives. These equations govern, e.g., the scale dependence of generalized hadron parton distributions and light-cone meson distribution amplitudes.

   hep-phhep-thJHEP(2016)·45 citations
6. 06*

   The Higgs mass and the scale of SUSY breaking in the NMSSM

   Lucila Zarate🇩🇪

   In this letter we study the Higgs mass in the NMSSM with supersymmetry breaking at high scales $M_{SS}$. With the Standard Model as the effective low energy theory, the computation of the Higgs mass relies on the matching condition of the quartic coupling $\lambda$ at $M_{SS}$. In the MSSM, the latter is fixed to a semi-positive value and, thus, sets an upper bound on the SUSY-breaking scale near $M_{SS}\simeq 10^{10}\text{GeV}$. In the NMSSM, $\lambda (M_{SS})$ receives an additional contribution induced by the singlet which allows for negative values of $\lambda (M_{SS})$. In turn, for the measured value of the Higgs mass we find that $M_{SS}$ can take any value up to the GUT scale. Furthermore, the choice of universal soft terms favors SUSY-breaking scales close to the GUT scale.

   hep-phhep-thJHEP(2016)·6 citations
7. 07*

   Inflection point inflation and reheating

   Soo-Min Choi🇰🇷 · Hyun Min Lee🇰🇷

   We revisit the inflection point inflation with an extended discussion to large field values and consider the reheating effects on the inflationary predictions. Parametrizing the reheating dynamics in terms of the reheating temperature and the equation of state during inflation, we show how the observationally favored parameter space of inflection point inflation is affected by reheating dynamics. Consequently, we apply the general results to the inflation models with non-minimal coupling, such as the SM Higgs inflation and the $B-L$ Higgs inflation.

   hep-phastro-ph.COEPJC(2016)·49 citations
8. 08*

   Discovery Potential of T2K and NOvA in the Presence of a Light Sterile Neutrino

   Sanjib Kumar Agarwalla🇮🇳 · Sabya Sachi Chatterjee🇮🇳 · Arnab Dasgupta🇮🇳 · Antonio Palazzo🇮🇹

   We study the impact of one light sterile neutrino on the prospective data expected to come from the two presently running long-baseline experiments T2K and NOvA when they will accumulate their full planned exposure. Introducing for the first time, the bi-probability representation in the 4-flavor framework, commonly used in the 3-flavor scenario, we present a detailed discussion of the behavior of the numu to nue and numubar to nuebar transition probabilities in the 3+1 scheme. We also perform a detailed sensitivity study of these two experiments (both in the stand-alone and combined modes) to assess their discovery reach in the presence of a light sterile neutrino. For realistic benchmark values of the mass-mixing parameters (as inferred from the existing global short-baseline fits), we find that the performance of both these experiments in claiming the discovery of the CP-violation induced by the standard CP-phase delta13 equivalent to delta, and the neutrino mass hierarchy get substantially deteriorated. The exact loss of sensitivity depends on the value of the unknown CP-phase delta14. Finally, we estimate the discovery potential of total CP-violation (i.e., induced simultaneously by the two CP-phases delta13 and delta14), and the capability of the two experiments of reconstructing the true values of such CP-phases. The typical (1 sigma level) uncertainties on the reconstructed phases are approximately 40 degree for delta13 and 50 degree for delta14.

   hep-phhep-exphysics.ins-detJHEP(2016)·56 citations
9. 09*

   Family of dilatons and metrics for AdS/QCD models

   Alfredo Vega🇨🇱 · Paulina Cabrera🇨🇱

   We explore some possibilities for obtaining useful metrics and dilatons for AdS/QCD models. As a guideline, we consider dilatons and/or metrics that on the one hand reproduce the mesonic spectrum, and that on the other hand allow us a correct implementation of chiral symmetry breaking in AdS/QCD models. We discuss two procedures: one is based on supersymmetric quantum mechanics techniques and the other considers the interpolation between some limits on dilatons and/or metrics.

   hep-phhep-thmath-phmath.MPPRD(2016)·26 citations
10. 10*

    Status of diboson production in NNLO QCD

    Massimiliano Grazzini🇨🇭 · Stefan Kallweit🇩🇪 · Dirk Rathlev🇩🇪

    We present results from the first fully differential next-to-next-to leading order NNLO QCD computation of ZZ production, including off-shell effects, the leptonic decay and non-resonant contributions. We compare theoretical predictions to fiducial cross sections and distributions measured by ATLAS and CMS at 8 TeV and also perform a first comparison with early ATLAS measurements at 13 TeV.

    hep-phPoS(2016)·1 citation
11. 11*

    An effective strong-coupling theory of composite particles in UV-domain

    She-Sheng Xue🇮🇹

    We briefly review the effective field theory of massive composite particles, their gauge couplings and characteristic energy scale in the UV-domain of UV-stable fixed point of strong four-fermion coupling, then mainly focus the discussions on the decay channels of composite particles into the final states of the SM gauge bosons, leptons and quarks. We calculate the rates of composite bosons decaying into two gauge bosons $\gamma \gamma$, $\gamma Z^0$, $W^{+}{W}^{-}$, $Z^0{Z}^0$ and give the ratios of decay rates of different channels depending on gauge couplings only. It is shown that a composite fermion decays into an elementary fermion and a composite boson, the latter being an intermediate state decays into two gauge bosons, leading to a peculiar kinematics of final states of a quark (or a lepton) and two gauge bosons. These provide experimental implications of such an effective theory of composite particles beyond the SM. We also present some speculative discussions on the channels of composite fermions decaying into $WW$, $WZ$ and $ZZ$ two boson-tagged jets with quark jets, or to four-quark jets. Moreover, at the same energy scale of composite particles produced in high-energy experiments, composite particles are also produced by high-energy sterile neutrino (dark matter) collisions, their decays lead to excesses of cosmic ray particles in space and signals of SM particles in underground laboratories.

    hep-phhep-exhep-thJHEP(2017)·16 citations
12. 12*

    Influence of quantum conservation laws on particle production in hadron collisions

    Małgorzata Anna Janik🇵🇱 · Łukasz Kamil Graczykowski🇵🇱 · Adam Kisiel🇵🇱

    Conservation laws strongly influence production of particles in high-energy particle collisions. Effects connected to these mechanisms were studied in details using correlation techniques in \ee\ collisions. At the time, models were tuned to correctly reproduce the measurements. Similar studies for hadron-hadron collisions have never been performed, until recent ALICE measurements. ALICE has reported on studies of untriggered two-particle angular correlations of identified particles ($\pi$, $K$, and p) measured in pp collisions at center-of-mass energy of $\sqrt{s}=$ 7 TeV. Those preliminary results confirm that also in hadron-hadron collisions, at much higher energies, conservation laws strongly influence the shape of the correlation functions for different particle types and must be taken into account while analysing the data. Moreover, they show that the contemporary models (PYTHIA, PHOJET) no longer reproduce the experimental data well.

    hep-phNPA(2016)·1 citation
13. 13*

    Young and Millisecond Pulsar GeV Gamma-ray Fluxes from the Galactic Center and Beyond

    Ryan M. O'Leary🇺🇸 · Matthew D. Kistler🇺🇸 · Matthew Kerr🇦🇺 · Jason Dexter🇩🇪

    Gamma-ray observations have shown pulsars to be efficient converters of rotational energy into GeV photons and it is of wide-ranging interest to determine their contribution to the gamma-ray background. We arrive at flux predictions from both the young (<~ Myr) and millisecond (~Gyr) Galactic pulsar populations. We find that unresolved pulsars can yield both a significant fraction of the excess GeV gamma rays near the Galactic Center and an inverse Compton flux in the inner kpc similar to that inferred by Fermi. We compare models of the young pulsar population and millisecond pulsar population to constraints from gamma-ray and radio observations. Overall, we find that the young pulsars should outnumber millisecond pulsars as unassociated gamma-ray point sources in this region. The number of young radio pulsars discovered near the Galactic Center is in agreement with our model of the young pulsar population. Deeper radio observations at higher latitudes can constrain the total gamma-ray emission from both young and millisecond pulsars from the inner galaxy. While this is a step towards better understanding of pulsars, cosmic rays in the Milky Way, and searches for dark matter, we also discuss a few interesting puzzles that arise from the underlying physics of pulsar emission and evolution.

    ↳ astro-ph.HEastro-ph.GAhep-ph31 citations
14. 14*

    Neutrino propagation in the galactic dark matter halo

    P. F. de Salas🇪🇸 · R. A. Lineros🇪🇸 · M. Tórtola🇪🇸

    Neutrino oscillations are a widely observed and well established phenomenon. It is also well known that deviations with respect to flavor conversion probabilities in vacuum arise due to neutrino interactions with matter. In this work, we analyze the impact of new interactions between neutrinos and the dark matter present in the Milky Way on the neutrino oscillation pattern. The dark matter-neutrino interaction is modeled by using an effective coupling proportional to the Fermi constant $G_F$ with no further restrictions on its flavor structure. For the galactic dark matter profile we consider an homogeneous distribution as well as several density profiles, estimating in all cases the size of the interaction required to get an observable effect at different neutrino energies. Our discussion is mainly focused in the PeV neutrino energy range, to be explored in observatories like IceCube and KM3NeT. The obtained results may be interpreted in terms of a light $\mathcal{O}$(sub-eV--keV) or WIMP-like dark matter particle or as a new interaction with a mediator of $\mathcal{O}$(sub-eV--keV) mass.

    ↳ astro-ph.HEhep-phPRD(2016)·66 citations
15. 15*

    Resonance spectrum of a bulk fermion on branes

    Yu-Peng Zhang🇨🇳 · Yun-Zhi Du🇨🇳 · Wen-Di Guo🇨🇳 · Yu-Xiao Liu🇨🇳

    It is known that there are two mechanisms for localizing a bulk fermion on a brane, one is the well-known Yukawa coupling and the other is the new coupling proposed in [Phys. Rev. D 89, 086001 (2014)]. In this paper, we investigate localization and resonance spectrum of a bulk fermion on the same branes with the two localization mechanisms. It is found that both the two mechanisms can result in a volcano-like effective potential of the fermion Kaluza-Klein modes. The left-chiral fermion zero mode can be localized on the brane and there exist some discrete massive fermion Kaluza-Klein modes that quasilocalized on the brane (also called fermion resonances). The number of the fermion resonances increases linearly with the coupling parameter.

    ↳ hep-thgr-qchep-phPRD(2016)·21 citations
16. 16*

    Much ado about Zero

    Asis Kumar Chaudhuri🇮🇳

    A brief historical introduction for the enigmatic number Zero is given. The discussions are for popular consumption.

    ↳ math.HOhep-phnucl-exnucl-th+10 citations
17. 17*

    Leptonic decay-constant ratio $f_K/f_{\pi }$ from lattice QCD using 2+1 clover-improved fermion flavors with 2-HEX smearing

    Stephan Dürr🇩🇪 · Zoltán Fodor🇩🇪 · Christian Hoelbling🇩🇪 · Stefan Krieg🇩🇪 · Laurent Lellouch🇫🇷 · Thomas Lippert🇩🇪 · Thomas Rae🇩🇪 · Andreas Schäfer🇩🇪 · Enno E. Scholz🇩🇪 · Kálmán K. Szabó🇩🇪 · Lukas Varnhorst🇩🇪

    We present a calculation of the leptonic decay-constant ratio $f_K/f_{\pi }$ in 2+1 flavor QCD. Our data set includes five lattice spacings and pion masses reaching down below the physical one. Special emphasis is placed on a careful study of all systematic uncertainties, especially the continuum extrapolation. Our result is perfectly compatible with the first-row unitarity constraint of the Standard Model.

    ↳ hep-lathep-phPRD(2017)·30 citations
18. 18*

    Scaling properties of the mean multiplicity and pseudorapidity density in $e^{-}+e^{+}$, $e^{\pm }$+p, p($\bar{\mathrm{p}}$)+p, p+A and A+A(B) collisions

    Roy A. Lacey (1,2)🇺🇸 · Peifeng Liu (2)🇺🇸 · Niseem Magdy (1)🇺🇸 · M.Csanád (1,3)🇺🇸 · B. Schweid (2)🇺🇸 · N. N. Ajitanand (1)🇺🇸 · J. Alexander (1)🇺🇸 · R. Pak (4) ((1) Department of Chemistry, Stony Brook University, Stony Brook, NY, USA (2) Dept. of Physics, Stony Brook University, Stony Brook, NY, USA (3) Eotvos University, Department of Atomic Physics, Budapest, Hungary (4) Brookhaven National Laboratory, Upton, New York, USA)🇺🇸

    The pseudorapidity density (dN/deta) for p+p, p+A and A+A(B) collisions, and the mean multiplicity <Nch> for ee, ep, and p+p collisions, are studied for an inclusive range of beam energies (Root_s). Characteristic scaling patterns are observed for both dN/deta and <Nch>, consistent with a thermal particle production mechanism for the bulk of the soft particles produced in all of these systems. They also validate an essential role for quark participants in these collisions. The scaled values for dN/deta and <Nch> are observed to factorize into contributions which depend on log(Root_s) and the number of nucleon or quark participant pairs (Npp). Quantification of these contributions give expressions which serve to systematize dN/deta and <Nch> measurements spanning nearly four orders of magnitude in Root_s, and to predict their values as a function of Root_s and Npp.

    ↳ nucl-exhep-exhep-phnucl-thUniverse(2018)·36 citations
19. 19*

    A Dynamical model for non-geometric quantum black holes

    Euro Spallucci🇮🇹 · Anais Smailagic🇮🇹

    It has been recently proposed that quantum black holes can be described as N-graviton Bose-Einstein condensates. In this picture the quantum properties of BHs "... can be understood in terms of the single number N". However, so far, the dynamical origin of the occupational number N has not been specified. This description is alternative to the usual one, where black holes are believed to be well described geometrically even at the quantum level. In this paper we pursue the former point of view and develop a non-geometrical dynamical model of quantum black holes (BHs). In our model the occupational number N is proportional to the principal quantum number n of a Planckian harmonic oscillator. The so-called "classicalization" corresponds to the large-n limit, where the Schwarzschild horizon is recovered.

    ↳ hep-thgr-qchep-phquant-ph7 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.