HEP Phenomenology·hep-ph

Fri·Jun 16, 2017Friday·June 16, 2017

23 papers—17 primary·6 cross-listed·reconstructed*

01*
Locating the Gribov horizon
Fei Gao🇨🇳 · Si-Xue Qin🇨🇳 · Craig D. Roberts🇺🇸 · Jose Rodriguez-Quintero🇪🇸
We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behaviour at ultraviolet momenta. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent mass-scales, each with a value of roughly $0.5$ GeV; and wherefrom it appears plausible that the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.
hep-phhep-lathep-thnucl-thPRD(2018)·95 citations
02*
Mitigating Direct Detection Bounds in Non-minimal Higgs Portal Scalar Dark Matter Models
Subhaditya Bhattacharya🇮🇳 · Purusottam Ghosh🇮🇳 · Tarak Nath Maity🇮🇳 · Tirtha Sankar Ray🇮🇳
Minimal scalar Higgs portal dark matter model is increasingly in tension with recent results form direct detection experiments like LUX and XENON. In this paper we make a systematic study of minimal extension of the $Z_{2}$ stabilised singlet scalar Higgs portal scenario in terms of their prospects at direct detection experiments. We consider both enlarging the stabilising symmetry to $Z_{3}$ and incorporating multipartite features in the dark sector. We demonstrate that in these non-minimal models the interplay of annihilation, co-annihilation and semi-annihilation processes considerably relax constraints from present and proposed direct detection experiments while simultaneously saturating observed dark matter relic density. We explore in particular the resonant semi-annihilation channel within the multipartite $Z_{3}$ framework which results in new unexplored regions of parameter space that would be difficult to constrain by direct detection experiments in the near future. The role of dark matter exchange processes within multi-component $Z_{3} \times Z_{3}^{'}$ framework is illustrated. We make quantitative estimates to elucidate the role of the various annihilation processes in the different allowed regions of parameter space of these models.
hep-phastro-ph.COJHEP(2017)·77 citations
03*
Hidden-charm Pentaquark Production at $e^{+} e^{-}$ Colliders
Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Yu-Nan Liu🇨🇳 · Zong-Guo Si🇨🇳 · Xiao-Feng Zhang🇨🇳
We study one possible production mechanism for hidden charm pentaquark in e+e- collision, where it is produced via a color-octet c \bar c pair fragmentation. The pentaquark production at B factory energy is dominated by e+e- to c \bar c g to Pc + X. At Z^0 pole, for the pentaquark production, there are several partonic processes playing significant role. Our results show that it is possible to search for the direct pentaquark production signal at e+e- colliders, which is important to understand the properties of pentaquark.
hep-phCommun.Theor.Phys.(2018)·9 citations
04*
Quarkonium dissociation in a far-from-equilibrium holographic setup
L. Bellantuono🇮🇹 · P. Colangelo🇮🇹 · F. De Fazio🇮🇹 · F. Giannuzzi🇮🇹 · S. Nicotri🇮🇹
The real-time dissociation of the heavy quarkonium in a strongly coupled boost-invariant non-Abelian plasma relaxing towards equilibrium is analyzed in a holographic framework. The effects driving the plasma out of equilibrium are described by boundary quenching, impulsive variations of the boundary metric. Quarkonium is represented by a classical string with endpoints kept close to the boundary. The evolution of the string profile is computed in the time-dependent geometry, and the dissociation time is evaluated for different configurations with respect to the direction of the plasma expansion. Dissociation occurs fastly for the quarkonium placed in the transverse plane.
hep-phhep-thnucl-thPRD(2017)·19 citations
05*
Enhanced, high energy photon production from resonant Compton scattering in a strong external field
A. Hartin🇩🇪
A theoretical and phenomenological consideration is given to higher order, strong field effects in electron/laser interactions. A consistent strong field theory is the Furry interaction picture of intense field quantum field theory. In this theory, fermions are embedded in the strong laser field and the Volkov wavefunction solutions that result, are exact with respect to the strong field. When these Volkov fermions interact with individual photons from other sources, the transition probability is enhanced in a series of resonances when the kinematics allow the virtual fermion to go on-shell. An experiment is proposed in which, for the first time, resonances could be used to generate high energy photons from relativistic electrons at rates orders of magnitude in excess of usual mechanisms.
hep-phNucl.Instrum.Meth.B(2017)·2 citations
06*
Transverse momentum spectra of hadrons in high energy pp and heavy ion collisions
Kapil Saraswat🇮🇳 · Prashant Shukla🇮🇳 · Venktesh Singh🇮🇳
We present a study of transverse momentum ( $p_{T}$ ) spectra of unidentified charged particles in pp collisions at RHIC and LHC energies from $s$ = 62.4 GeV to 13 TeV using Tsallis/Hagedorn function. The power law of Tsallis/Hagedorn form gives excellent description of the hadron spectra in $p_{T}$ range from 0.2 to 300 GeV/ $c$ . The power index $n$ of the $p_{T}$ distributions is found to follow a function of the type $a + b / s$ with asymptotic value $a = 5.72$ . The parameter $T$ governing the soft bulk contribution to the spectra remains almost same over wide range of collision energies. We also provide a Tsallis/Hagedorn fit to the $p_{T}$ spectra of hadrons in pPb and different centralities of PbPb collisions at $s_{N N}$ = 5.02 TeV. The data/fit shows deviations from the Tsallis distribution which become more pronounced as the system size increases. We suggest simple modifications in the Tsallis/Hagedorn power law function and show that the above deviations can be attributed to the transverse flow in low $p_{T}$ region and to the in-medium energy loss in high $p_{T}$ region.
hep-phnucl-thJ.Phys.Comm.(2018)·34 citations
07*
On the Higgs-like boson in the Minimal Supersymmetric 3-3-1 Model
J. G. Ferreira Jr🇧🇷 · C. A. de S. Pires🇧🇷 · P. S. Rodrigues da Silva🇧🇷 · Clarissa Siqueira🇩🇪
It is imperative that any proposal of new physics possesses a Higgs-like boson with 125 GeV of mass and couplings with the standard particles that recover the branching ratios and signal strengths as measured by CMS and ATLAS. We address this issue within the supersymmetric version of the minimal 3-3-1 model. For this we develop the Higgs potential with focus on the lightest Higgs provided by the model. Our proposal is to verify if it recovers the properties of the standard Higgs. With respect to its mass, we calculate it up to one loop level by taking into account all contributions provided by the model. In regard to its couplings, we restrict our investigation to couplings of the Higgs-like boson with the standard particles, only. We then calculate the dominant branching ratios and the respective signal strengths and confront our results with the recent measurements of CMS and ATLAS. As distinctive aspects, we remark that our Higgs-like boson intermediates flavor changing neutral processes and then argue that its signature is the decay $t \to h + c$ . We calculate its branching ratio and compare it with current bounds. We also show that the potential is stable for the region of parameter space employed in our calculations.
hep-phEPJC(2018)·3 citations
08*
Anatomy of the magnetic catalysis by renormalization-group method
Koichi Hattori🇨🇳 · Kazunori Itakura🇯🇵 · Sho Ozaki🇯🇵
We first examine the scaling argument for a renormalization-group (RG) analysis applied to a system subject to the dimensional reduction in strong magnetic fields, and discuss the fact that a four-Fermi operator of the low-energy excitations is marginal irrespective of the strength of the coupling constant in underlying theories. We then construct a scale-dependent effective four-Fermi interaction as a result of screened photon exchanges at weak coupling, and establish the RG method appropriately including the screening effect, in which the RG evolution from ultraviolet to infrared scales is separated into two stages by the screening-mass scale. Based on a precise agreement between the dynamical mass gaps obtained from the solutions of the RG and Schwinger-Dyson equations, we discuss an equivalence between these two approaches. Focusing on QED and Nambu--Jona-Lasinio model, we clarify how the properties of the interactions manifest themselves in the mass gap, and point out an importance of respecting the intrinsic energy-scale dependences in underlying theories for the determination of the mass gap. These studies are expected to be useful for a diagnosis of the magnetic catalysis in QCD.
hep-phPLB(2017)·10 citations
09*
Study of Electroweak Vacuum Stability from Extended Higgs Portal of Dark Matter and Neutrinos
Purusottam Ghosh🇮🇳 · Abhijit Kumar Saha🇮🇳 · Arunansu Sil🇮🇳
We investigate the electroweak vacuum stability in an extended version of the Standard Model which incorporates two additional singlet scalar fields and three right handed neutrinos. One of these extra scalars plays the role of dark matter while the other scalar not only helps in making the electroweak vacuum stable but also opens up the low mass window of the scalar singlet dark matter (< 500 GeV). We consider the effect of large neutrino Yukawa coupling on the running of Higgs quartic coupling. We have analyzed the constraints on the model and identify the range of parameter space which is consistent with neutrino mass, appropriate relic density and direct search limits from the latest XENON 1T preliminary result as well as in realizing the stability of the electroweak vacuum upto the Planck scale.
hep-phPRD(2018)·42 citations
10*
Thermomagnetic correlation lengths of strongly interacting matter in the Nambu--Jona-Lasinio model
Alejandro Ayala🇲🇽 · L. A. Hernandez🇲🇽 · M. Loewe🇿🇦 · Alfredo Raya🇲🇽 · J. C. Rojas🇨🇱 · R. Zamora🇨🇱
We study the correlation length between test quarks with the same electric and color charges in the Nambu--Jona-Lasinio model, considering thermal and magnetic effects. We extract the correlation length from the quark correlation function. The latter is constructed from the probability amplitude to bring a given quark into the plasma, once a previous one with the same quantum numbers is placed at a given distance apart. For temperatures below the transition temperature, the correlation length starts growing as the field strength increases to then decrease for large magnetic fields. For temperatures above the critical temperature, the correlation length continues increasing as the field strength increases. We found that such behavior can be understood as a competition between the tightening induced by the classical magnetic force versus the random thermal motion. For large enough temperatures, the increase of the occupation number contributes to the screening of the interaction between the test particles. The growth of the correlation distance with the magnetic field can be understood as due to the closer proximity between one of the test quarks and the ones popped up from vacuum, which in turn appear due to the increase of the occupation number with temperature.
hep-phPRD(2017)·10 citations
11*
Discovering True Muonium in $K_{L} \to (μ^{+} μ^{-}) γ$
Yao Ji🇩🇪 · Henry Lamm🇺🇸
Theoretical and phenomenological predictions of $B R (K_{L} \to (μ^{+} μ^{-}) γ) \sim 7 \times 1 0^{- 13}$ are presented for different model form factors $F_{K_{L} γ γ^{*}} (Q^{2})$ . These rates are comparable to existing and near-term rare $K_{L}$ decay searches at J-PARC and CERN, indicating a discovery of true muonium is possible. The model uncertainties are sufficiently small that detection of true muonium could discriminate between the form factor models. Further discussion of potential backgrounds is made.
hep-phhep-exPRD(2018)·13 citations
12*
Enlarging Regions of the MSSM Parameter Space for Large $tan β$ via SUSY Decays of the Heavy Higgs Bosons
Anibal D. Medina🇫🇷 · Michael A. Schmidt🇦🇺
In the Minimal Supersymmetric Standard Model (MSSM) searches for the heaviest CP-even and CP-odd Higgs $H$ , $A$ to tau-lepton pairs severely constrain the parameter region for large values of $tan β$ and light Higgs bosons $H$ , $A$ . We demonstrate how the experimental constraint can be avoided by new decays to light third-generation sfermions, whose left-right couplings to $H$ can be maximised in regions of large trilinear couplings $A_{b}$ , $A_{τ}$ for sbottoms and staus, or large supersymmetric (SUSY) Higgs mass $μ$ for stops. Due to the $tan β$ -enhancement in the production cross-sections via gluon-fusion and in association with bottom-quark pairs for $H$ and $A$ , we find that down-type sfermions, in particular, sbottoms perform a better job in allowing more parameter space than up-type sfermions such as stops, which require much larger values of $μ$ to compensate for $tan β$ . Vacuum stability as well as flavour observables constraints and direct searches for SUSY particles are imposed. We also associate the lightest CP-even Higgs with the observed 125 GeV SM-like Higgs and impose the experimental constraints from the LHC.
hep-phJHEP(2017)·9 citations
13*
Resolving Combinatorial Ambiguities in Dilepton $t t ˉ$ Event Topologies with Constrained $M_{2}$ Variables
Dipsikha Debnath🇺🇸 · Doojin Kim🇨🇭 · Jeong Han Kim🇺🇸 · Kyoungchul Kong🇺🇸 · Konstantin T. Matchev🇺🇸
We advocate the use of on-shell constrained $M_{2}$ variables in order to mitigate the combinatorial problem in SUSY-like events with two invisible particles at the LHC. We show that in comparison to other approaches in the literature, the constrained $M_{2}$ variables provide superior ansatze for the unmeasured invisible momenta and therefore can be usefully applied to discriminate combinatorial ambiguities. We illustrate our procedure with the example of dilepton $t t ˉ$ events. We critically review the existing methods based on the Cambridge $M_{T 2}$ variable and MAOS-reconstruction of invisible momenta, and show that their algorithm can be simplified without loss of sensitivity, due to a perfect correlation between events with complex solutions for the invisible momenta and events exhibiting a kinematic endpoint violation. Then we demonstrate that the efficiency for selecting the correct partition is further improved by utilizing the $M_{2}$ variables instead. Finally, we also consider the general case when the underlying mass spectrum is unknown, and no kinematic endpoint information is available.
hep-phPRD(2017)·19 citations
14*
On the robustness of the primordial power spectrum in renormalized Higgs inflation
Fedor Bezrukov🇬🇧 · Martin Pauly🇩🇪 · Javier Rubio🇩🇪
We study the cosmological consequences of higher-dimensional operators respecting the asymptotic symmetries of the tree-level Higgs inflation action. The main contribution of these operators to the renormalization group enhanced potential is localized in a compact field range, whose upper limit is close to the end of inflation. The spectrum of primordial fluctuations in the so-called universal regime turns out to be almost insensitive to radiative corrections and in excellent agreement with the present cosmological data. However, higher-dimensional operators can play an important role in critical Higgs inflation scenarios containing a quasi-inflection point along the inflationary trajectory. The interplay of radiative corrections with this quasi-inflection point may translate into a sizable modification of the inflationary observables.
hep-phastro-ph.COhep-thJCAP(2018)·121 citations
15*
Dark Spectroscopy
Yonit Hochberg🇺🇸 · Eric Kuflik🇺🇸 · Hitoshi Murayama🇺🇸
Rich and complex dark sectors are abundant in particle physics theories. Here we propose performing spectroscopy of the mass structure of dark sectors via mono-photon searches at lepton colliders. The energy of the mono-photon tracks the invariant mass of the invisible system it recoils against, which enables studying the resonance structure of the dark sector. We demonstrate this idea with several well-motivated models of dark sectors. Such spectroscopy measurements could potentially be performed at Belle II, BES-III and future low-energy lepton colliders.
hep-phPRD(2018)·29 citations
16*
The ridge effect and three-particle correlations
Miguel-Angel Sanchis-Lozano🇪🇸 · Edward Sarkisyan-Grinbaum🇨🇭
Pseudorapidity and azimuthal three-particle correlations are studied based on a correlated-cluster model of multiparticle production. The model provides a common framework for correlations in proton-proton and heavy-ion collisions allowing easy comparison with the measurements. It is shown that azimuthal cluster correlations are definitely required in order to understand three-particle correlations in the near-side ridge effect. This is similar to the explanation of the ridge phenomenon found in our previous analysis of two-particle correlations and generalizes the model to higher-order correlations.
hep-phhep-exhep-thnucl-ex+1PRD(2017)·13 citations
17*
A model with isospin doublet $U (1)_{D}$ gauge symmetry
Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼
We propose a model with an extra isospin doublet $U (1)_{D}$ gauge symmetry, in which we introduce several extra fermions with odd parity under a discrete $Z_{2}$ symmetry in order to cancel the gauge anomalies out. A remarkable issue is that we impose nonzero $U (1)_{D}$ charge to the standard model Higgs, and it gives the most stringent constraint to the vacuum expectation value of a scalar field breaking the $U (1)_{D}$ symmetry that are severer than the LEP bound. We then explore relic density of a Majorana dark matter candidate without conflict of constraints from lepton flavor violating processes. A global analysis is carried out to search for parameters which can accommodate with observed data.
hep-phInt.J.Mod.Phys.A(2018)·11 citations
18*
Muon Creation in Supernova Matter Facilitates Neutrino-driven Explosions
R. Bollig (1,2)🇩🇪 · H.-Th. Janka (2)🇩🇪 · A. Lohs (3)🇩🇪 · G. Martinez-Pinedo (3,4)🇩🇪 · C.J. Horowitz (5)🇺🇸 · T. Melson (1) ((1) MPI Astrophysics, Garching, (2) Physik Dept., TUM, (3) GSI Darmstadt, (4) TU Darmstadt, (5) Indiana Univ., Bloomington)🇩🇪
Muons can be created in nascent neutron stars (NSs) due to the high electron chemical potentials and the high temperatures. Because of their relatively lower abundance compared to electrons, their role has so far been ignored in numerical simulations of stellar core collapse and NS formation. However, the appearance of muons softens the NS equation of state, triggers faster NS contraction and thus leads to higher luminosities and mean energies of the emitted neutrinos. This strengthens the postshock heating by neutrinos and can facilitate explosions by the neutrino-driven mechanism.
↳ astro-ph.HEhep-phnucl-thPRL(2017)·216 citations
19*
The reactions $π π \to π π$ and $γ γ \to π π$ in $χ$ PT with an isosinglet scalar resonance
Arbin Thapaliya🇺🇸 · Daniel R. Phillips🇺🇸
The lowest-lying resonance in the QCD spectrum is the $0^{++}$ isoscalar $σ$ meson, also known as the $f_{0} (500)$ . We augment SU(2) chiral perturbation theory ( $χ$ PT) by including the $σ$ meson as an additional explicit degree of freedom, as proposed by Soto, Talavera, and Tarrús and others. In this effective field theory, denoted $χ$ PT $_{S}$ , the $σ$ meson's well-established mass and decay width are not sufficient to properly renormalize its self energy. At $O (p^{4})$ another low-energy constant appears in the dressed $σ$ -meson propagator; we adjust it so that the isoscalar pion-pion scattering length is also reproduced. We compare the resulting amplitudes for the $π π \to π π$ and $γ γ \to π π$ reactions to data from threshold through the energies at which the $σ$ -meson resonance affects observables. The leading-order (LO) $π π$ amplitude reproduces the $σ$ -meson pole position, the isoscalar $π π$ scattering lengths and $π π$ scattering and $γ γ \to π π$ data up to $s \approx 0.5$ GeV. It also yields a $γ γ \to π π$ amplitude that obeys the Ward identity. The value obtained for the $π^{0}$ polarizability is, however, only slightly larger than that obtained in standard $χ$ PT.
↳ nucl-thhep-phEPJA(2017)·2 citations
20*
Gravitational Mechanisms to Self-Tune the Cosmological Constant: Obstructions and Ways Forward
Florian Niedermann🇬🇧 · Antonio Padilla🇬🇧
Gravitational models of self-tuning are those in which vacuum energy has no observable effect on spacetime curvature, even though it is a priori unsuppressed below the cut-off. We complement Weinberg's no go theorem by studying field theoretic completions of self-adjustment allowing for broken translations as well as other generalisations, and identify new obstructions. Our analysis uses a very general Kallen-Lehmann spectral representation of the exchange amplitude for conserved sources of energy-momentum and exploits unitarity and Lorentz invariance to show that a transition from self-tuning of long wavelength sources to near General Relativity on shorter scales is generically not possible. We search for novel ways around our obstructions and highlight two interesting possibilities. The first is an example of a unitary field configuration on anti-de Sitter space with the desired transition from self-tuning to GR. A second example is motivated by vacuum energy sequestering.
↳ hep-thastro-ph.COgr-qchep-phPRL(2017)·23 citations
21*
Effective description of dark matter self-interactions in small dark matter haloes
Janis Kummer🇩🇪 · Felix Kahlhoefer🇩🇪 · Kai Schmidt-Hoberg🇩🇪
Self-interacting dark matter may have striking astrophysical signatures, such as observable offsets between galaxies and dark matter in merging galaxy clusters. Numerical N-body simulations used to predict such observables typically treat the galaxies as collisionless test particles, a questionable assumption given that each galaxy is embedded in its own dark matter halo. To enable a more accurate treatment we develop an effective description of small dark matter haloes taking into account the two major effects due to dark matter self-scatterings: deceleration and evaporation. We point out that self-scatterings can have a sizeable impact on the trajectories of galaxies, diminishing the separation between galaxies and dark matter in merging clusters. This effect depends sensitively on the underlying particle physics, in particular the angular dependence of the self-scattering cross section, and cannot be predicted from the momentum transfer cross section alone.
↳ astro-ph.COhep-phMNRAS(2018)·53 citations
22*
Can decaying particle explain cosmic infrared background excess?
Kazunori Kohri🇯🇵 · Takeo Moroi🇯🇵 · Kazunori Nakayama🇯🇵
Recently the CIBER experiment measured the diffuse cosmic infrared background (CIB) flux and claimed an excess compared with integrated emission from galaxies. We show that the CIB spectrum can be fitted by the additional photons produced by the decay of a new particle. However, it also contributes too much to the anisotropy of the CIB, which is in contradiction with the anisotropy measurements by the CIBER and Hubble Space Telescope.
↳ astro-ph.COhep-phPLB(2017)·21 citations
23*
Power corrections from decoupling of the charm quark
Francesco Knechtli🇩🇪 · Tomasz Korzec🇩🇪 · Björn Leder🇩🇪 · Graham Moir🇬🇧
Decoupling of heavy quarks at low energies can be described by means of an effective theory as shown by S. Weinberg in Ref. [1]. We study the decoupling of the charm quark by lattice simulations. We simulate a model, QCD with two degenerate charm quarks. In this case the leading order term in the effective theory is a pure gauge theory. The higher order terms are proportional to inverse powers of the charm quark mass $M$ starting at $M^{- 2}$ . Ratios of hadronic scales are equal to their value in the pure gauge theory up to power corrections. We show, by precise measurements of ratios of scales defined from the Wilson flow, that these corrections are very small and that they can be described by a term proportional to $M^{- 2}$ down to masses in the region of the charm quark mass.
↳ hep-lathep-phPLB(2017)·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.