HEP Phenomenology·hep-ph

Tue·Nov 22, 2016Tuesday·November 22, 2016

38 papers—22 primary·16 cross-listed·reconstructed*

01*
Kaon Flavour Physics Strikes Back
Andrzej J. Buras🇩🇪
In this short presentation I emphasize the increased importance of kaon flavour physics in the search for new physics (NP) that we should witness in the rest of this decade and in the next decade. The main actors will be the branching ratios for the rare decays $K^{+} \to π^{+} ν ν ˉ$ and $K_{L} \to π^{0} ν ν ˉ$ , to be measured by NA62 and KOTO, and their correlations with the ratio $ε^{'} / ε$ on which recently progress by lattice QCD and large $N$ dual QCD approach has been made implying a new flavour anomaly. Further correlations of $K^{+} \to π^{+} ν ν ˉ$ , $K_{L} \to π^{0} ν ν ˉ$ and $ε^{'} / ε$ with $ε_{K}$ , $Δ M_{K}$ , $K_{L} \to μ^{+} μ^{-}$ and $K_{L} \to π^{0} ℓ^{+} ℓ^{-}$ will help us to identify indirectly possible NP at short distance scales. This talk summarizes the present highlights of this fascinating field including some results from concrete NP scenarios.
hep-phhep-exhep-latJ.Phys.Conf.Ser.(2017)·7 citations
02*
Wino dark matter annihilation through the radiative formation of bound states
Evan Johnson🇺🇸 · Eric Braaten🇺🇸 · Hong Zhang🇺🇸
The most dramatic "Sommerfeld enhancements" of neutral-wino-pair annihilation occur when the wino mass is tuned to near critical values where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold. If the wino mass is larger than the critical value, the resonance is a wino-pair bound state. If the wino mass is near a critical value, low-energy winos can be described by a zero-range effective field theory in which the winos interact nonperturbatively through a contact interaction. The parameters of the zero-range effective field theory can be determined by matching wino scattering amplitudes calculated by solving the Schrödinger equation for a nonrelativistic effective field theory in which the winos interact through a potential due to the exchange of electroweak gauge bosons. The utility of the zero-range effective field theory is illustrated by calculating the rate for formation of an S-wave bound state in the collision of two neutral winos through the emission of two soft photons.
hep-phPoS(2016)·7 citations
03*
Light Dark Matter in Superfluid Helium: Detection with Multi-excitation Production
Simon Knapen🇺🇸 · Tongyan Lin🇺🇸 · Kathryn M. Zurek🇺🇸
We examine in depth a recent proposal to utilize superfluid helium for direct detection of sub-MeV mass dark matter. For sub-keV recoil energies, nuclear scattering events in liquid helium primarily deposit energy into long-lived phonon and roton quasiparticle excitations. If the energy thresholds of the detector can be reduced to the meV scale, then dark matter as light as ~MeV can be reached with ordinary nuclear recoils. If, on the other hand, two or more quasiparticle excitations are directly produced in the dark matter interaction, the kinematics of the scattering allows sensitivity to dark matter as light as ~keV at the same energy resolution. We present in detail the theoretical framework for describing excitations in superfluid helium, using it to calculate the rate for the leading dark matter scattering interaction, where an off-shell phonon splits into two or more higher-momentum excitations. We validate our analytic results against the measured and simulated dynamic response of superfluid helium. Finally, we apply this formalism to the case of a kinetically mixed hidden photon in the superfluid, both with and without an external electric field to catalyze the processes.
hep-phastro-ph.COhep-exphysics.ins-detPRD(2017)·168 citations
04*
Bounds on Large Extra Dimensions from the Generalized Uncertainty Principle
Marco Cavaglia🇺🇸 · Benjamin Harms🇺🇸 · Shaoqi Hou🇺🇸
The Generalized Uncertainty Principle (GUP) implies the existence of a physical minimum length scale $l_{m}$ . In this scenario, black holes must have a radius larger than $l_{m}$ . They are hotter and evaporate faster than in standard Hawking thermodynamics. We study the effects of the GUP on black hole production and decay at the LHC in models with large extra dimensions. Lower bounds on the fundamental Planck scale and the minimum black hole mass at formation are determined from black hole production cross section limits by the CMS Collaboration. The existence of a minimum length generally decreases the lower bounds on the fundamental Planck scale obtained in the absence of a minimum length.
hep-phhep-thInt.J.Mod.Phys.A(2017)·0 citations
05*
String point of view for heavy-light mesons
Yubing Dong🇨🇳 · Qi-Fang Lü🇨🇳 · Takayuki Matsuki🇯🇵
An approximate rotational symmetry of a heavy-light meson is viewed from a string picture. Using a simple string configuration, we derive a formula, $(M - m_{c})^{2} = π σ L$ , whose coefficient of the r.h.s. is just 1/2 of that of a light meson with two light quarks. A numerical plot is obtained for $D$ mesons of experimental data as well as several theoretical models, which shows good agreement with this formula.
hep-phhep-exnucl-thEPJ Web Conf.(2017)·0 citations
06*
Dynamical bottomonium-suppression in a realistic AA background
Gossiaux Pol Bernard🇫🇷 · Katz Roland🇫🇷
We refine our dynamical Schroedinger-Langevin scheme designed for dealing with the suppression of quarkonium states in URHIC in order to allow for feed-downs from higher states and present updated results for the $R_{AA}$ as a function of the centrality.
hep-phJ.Phys.Conf.Ser.(2017)·4 citations
07*
Quarkonia at $T > 0$ and lattice QCD
Alexander Rothkopf🇩🇪
We report here on recent progress in the determination of S-wave and P-wave heavy-quarkonium states at finite temperature. Our results are based on the combination of effective field theories with numerical lattice QCD simulations. These non-perturbative tools allow us to compute the heavy-quarkonium in-medium spectral functions, from which we in turn determine the melting temperatures of individual states and estimate phenomenologically relevant observables, such as the $ψ^{'}$ to J/ $ψ$ ratio in heavy-ion collisions.
hep-phhep-latnucl-thEPJ Web Conf.(2017)·2 citations
08*
Analytic results for planar three-loop integrals for massive form factors
Johannes M. Henn🇩🇪 · Alexander V. Smirnov🇷🇺 · Vladimir A. Smirnov🇷🇺
We use the method of differential equations to analytically evaluate all planar three-loop Feynman integrals relevant for form factor calculations involving massive particles. Our results for ninety master integrals at general $q^{2}$ are expressed in terms of multiple polylogarithms, and results for fiftyone master integrals at the threshold $q^{2} = 4 m^{2}$ are expressed in terms of multiple polylogarithms of argument one, with indices equal to zero or to a sixth root of unity.
hep-phJHEP(2016)·35 citations
09*
Novel picture of the soft modes at the QCD critical point based on the FRG method
Takeru Yokota🇯🇵 · Teiji Kunihiro🇯🇵 · Kenji Morita🇯🇵
We investigate the soft mode at the QCD critical point (CP) on the basis of the functional renormalization group. We calculate the spectral functions in the meson channels in the two-flavor quark--meson model. Our result shows that the energy of the peak position of the particle--hole mode in the sigma channel becomes vanishingly small as the system approaches the QCD CP, which is a manifestation of the softening of the phonon mode. We also extract the dispersion curves of the mesonic and the phonon mode, a hydrodynamic mode which leads to a finding that the dispersion curve of the sigma-mesonic mode crosses the light-cone into the space-like momentum region, and then eventually merges into the phonon mode as the system approaches further close to the CP. This may suggest that the sigma-mesonic mode forms the soft mode together with the hydrodynamic mode at the CP.
hep-phnucl-thActa Phys.Polon.Supp.(2017)·1 citation
10*
Left-right symmetric extensions of 3-3-1 models
Edison T. Franco🇧🇷 · V. Pleitez🇧🇷
We propose four left-right symmetric extensions of several chiral 3-3-1 models. Although they have some common features they also have important difference due to different representation content.
hep-ph6 citations
11*
The Sommerfeld Enhancement in the Scotogenic Model with Large Electroweak Scalar Multiplets
Talal Ahmed Chowdhury🇧🇩 · Salah Nasri🇦🇪
We investigate the Sommerfeld enhancement (SE) in the generalized scotogenic model with large electroweak multiplets. We focus on scalar dark matter (DM) candidate of the model and compare DM annihilation cross sections to $W W$ , $Z Z$ , $γ γ$ and $γ Z$ at present day in the galactic halo for scalar doublet and its immediate generalization, the quartet in their respective viable regions of parameter space. We find that larger multiplet has sizable Sommerfeld enhanced annihilation cross section compared to the doublet and because of that it is more likely to be constrained by the current H.E.S.S. results and future CTA sensitivity limits.
hep-phJCAP(2017)·17 citations
12*
Exotic-Hadron Signature by Constituent-Counting Rule in Perturbative QCD
Wen-Chen Chang🇹🇼 · H. Kawamura🇯🇵 · S. Kumano🇯🇵 · T. Sekihara🇯🇵
We explain a method to find internal quark configurations of exotic hadron candidates by using the constituent counting rule. The counting rule was theoretically predicted in perturbative QCD for hard exclusive hadron reactions, and it has been tested in experiments for stable hadrons including compound systems of hadrons such as the deuteron, $^{3}$ H, and $^{3}$ He. It indicates that the cross section scales as $d σ / d t \sim 1/ s^{n - 2}$ , where $s$ is the center-of-mass energy squared and $n$ is the total number of constituents. We apply this method for finding internal configurations of exotic hadron candidates, especially $Λ (1405)$ . There is a possibility that $Λ (1405)$ could be five-quark state or a $K ˉ N$ molecule, and scaling properties should be different between the ordinary three-quark state or five-quark one. We predict such a difference in $π^{-} + p \to K^{0} + Λ (1405)$ , and it could be experimentally tested, for example, at J-PARC. On the other hand, there are already measurements for $γ + p \to K^{+} + Λ (1405)$ as well as the ground $Λ$ in photoproduction reactions. Analyzing such data, we found an interesting indication that $Λ (1405)$ looks like a five-quark state at medium energies and a three-quark one at high energies. However, accurate higher-energy measurements are necessary for drawing a solid conclusion, and it should be done at JLab by using the updated 12 GeV electron beam. Furthermore, we discuss studies of exotic hadron candidates, such as $f_{0} (980)$ and $a_{0} (980)$ , in electron-positron annihilation by using generalized distribution amplitudes and the counting rule. These studies should be possible as a KEKB experiment.
hep-phhep-exhep-latnucl-ex+1JPS Conf.Proc.(2017)·1 citation
13*
Analysis of the R-symmetric supersymmetric models including quantum corrections
Wojciech Kotlarski🇵🇱
We study the Minimal R-symmetric Supersymmetric Standard Model (MRSSM) at the quantum level. The thesis consists of two parts. First one treats about the electroweak sector of the model. Among others, it identifies the parameter region allowed by the electroweak precision observables. Since the MRSSM contains an $S U (2)_{L}$ -triplet with a non-zero vacuum expectation value the emphasis is put on the calculation of the $W$ boson mass. To that end, a full one-loop calculation of $m_{W}$ augmented with the leading two-loop SM result is presented. The region is then checked against the measurement of the Higgs boson mass. For this, the full one-loop and leading two-loop corrections to the Higgs boson mass in the MRSSM are calculated. Devised benchmark points, consistent with both of these observables, are shown to fulfill also a number of additional experimental constraints like properties of the Higgs boson(s), $b$ -physics observables and vacuum stability. Correlating all of these observables allows to put bounds on the parameters of the model. Second part of the thesis treats about the strongly interacting scalar sector. First, NLO QCD corrections to the production of scalar gluon (sgluon) pair at the LHC are calculated. A set of $K$ -factors for a selected sgluon masses at 13 and 14 TeV LHC is presented. This calculation is applied to constrain the sgluon mass using 2015 data set from Run 2 of the LHC. To that end, a same-sign lepton search by ATLAS is recasted for the case of the production of the sgluon pair decaying to $t t ˉ$ pairs. The analysis is reproduced with the help of shower Monte Carlo softwares and the program performing a fast detector response simulation. The analysis shows that already using 3.2/fb of integrated luminosity the exclusion limits from Run 2 are competitive with the 8 TeV ones.
hep-ph7 citations
14*
Spectral functions in functional renormalization group approach -- analysis of the collective soft modes at the QCD critical point --
Takeru Yokota🇯🇵 · Teiji Kunihiro🇯🇵 · Kenji Morita🇯🇵
We first review the method to calculate the spectral functions in the functional renormalization group (FRG) approach, which has been recently developed. We also provide the numerical stability conditions given by the present authors for a generic nonlinear evolution equation that are necessary for obtaining the accurate effective potential from the flow equation in the FRG. As an interesting example, we report the recent calculation of the spectral functions of the mesonic and particle-hole excitations using a chiral effective model of Quantum Chromodynamics (QCD); we extract the dispersion relations from them and try to reveal the nature of the soft modes at the QCD critical point (CP) where the phase transition is second order. Our result shows that a clear development and the softening of the phonon mode in the space-like region as the system approaches the CP; furthermore it turns out that the sigma mesonic mode once in the time-like region gets to merge with the phonon mode in the close vicinity of the CP, implying a novel possibility about the nature of the soft mode of the QCD CP.
hep-phnucl-th3 citations
15*
The lifetime of the $B_{c}^{-}$ meson and the anomalies in $B \to D^{(*)} τ ν$
Rodrigo Alonso🇨🇭 · Benjamín Grinstein🇺🇸 · Jorge Martin Camalich🇨🇭
We investigate a new constraint on new-physics interpretations of the anomalies observed in $B \to D^{(*)} τ ν$ decays making use of the lifetime of the $B_{c}^{-}$ meson. A constraint is obtained by demanding that the rate for $B_{c}^{-} \to τ^{-} ν ˉ$ does not exceed the fraction of the total width that is allowed by the calculation of the lifetime in the standard model. This leads to a very strong bound on new-physics scenarios involving scalar operators since they lift the slight, but not negligible, chiral suppression of the $B_{c}^{-} \to τ^{-} ν ˉ$ amplitude in the standard model. The new constraint renders a scalar interpretation of the enhancement measured in $R_{D^{*}}$ implausible, including explanations implementing extra Higgs doublets or certain classes of leptoquarks. We also discuss the complementarity of $R_{D^{(*)}}$ and a measurement of the longitudinal polarization of the $τ$ in the $B \to D^{*} τ ν$ decay in light of our findings.
hep-phhep-exPRL(2017)·289 citations
16*
Implications of Two-component Dark Matter Induced by Forbidden Channels and Thermal Freeze-out
Mayumi Aoki🇯🇵 · Takashi Toma🇫🇷
We consider a model of two-component dark matter based on a hidden $U (1)_{D}$ symmetry, in which relic densities of the dark matter are determined by forbidden channels and thermal freeze-out. The hidden $U (1)_{D}$ symmetry is spontaneously broken to a residual $Z_{4}$ symmetry, and the lightest $Z_{4}$ charged particle can be a dark matter candidate. Moreover, depending on the mass hierarchy in the dark sector, we have two-component dark matter. We show that the relic density of the lighter dark matter component can be determined by forbidden annihilation channels which require larger couplings compared to the normal freeze-out mechanism. As a result, a large self-interaction of the lighter dark matter component can be induced, which may solve small scale problems of $Λ$ CDM model. On the other hand, the heavier dark matter component is produced by normal freeze-out mechanism. We find that interesting implications emerge between the two dark matter components in this framework. We explore detectabilities of these dark matter particles and show some parameter space can be tested by the SHiP experiment.
hep-phastro-ph.COJCAP(2017)·24 citations
17*
Thermal relic abundance of the lightest Kaluza-Klein particle in phenomenological universal extra dimension models
Yoshiaki Ishigure🇯🇵 · Mitsuru Kakizaki🇯🇵 · Akiteru Santa🇯🇵
Universal extra dimension models with Kaluza-Klein parity provide us excellent candidates for dark matter. We consider phenomenological universal extra dimension models where the Kaluza-Klein (KK) mass spectrum is different from that of the minimal universal extra dimension model, and compute the thermal relic abundance of the first KK mode of the photon taking into account the production of second KK particles. It is pointed out that its thermal relic abundance depends significantly on the mass degeneracy between the KK-photon and other KK particles because of considerable coannihilation effects. The cosmologically favored compactification scale is shown to range from around 1 TeV to a few TeV even in the cases where one of the first KK particles is tightly degenerate with the first KK photon in mass.
hep-ph10 citations
18*
Probing neutrino and Higgs sectors in $S U (2)_{1} \times S U (2)_{2} \times U (1)_{Y}$ model with lepton-flavor non-universality
L. T. Hue🇻🇳 · A. B. Arbuzov🇷🇺 · N. T. K. Ngan🇻🇳 · H. N. Long🇻🇳
The neutrino and Higgs sectors in the $\mbox S U (2)_{1} \times \mbox S U (2)_{2} \times \mbox U (1)_{Y}$ model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling $μ$ . The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor $c_{h}$ , which must satisfy the recent global fit of experimental data, namely $0.995 < ∣ c_{h} ∣ < 1$ . We have analyzed a more general diagonalization of gauge boson mass matrices, then we show that the ratio of the tangents of the $W - W^{'}$ and $Z - Z^{'}$ mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed.
hep-phEPJC(2017)·12 citations
19*
New Statistical PDFs: Predictions and Tests up to LHC Energies
Jacques Soffer🇺🇸 · Claude Bourrely🇫🇷
The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in a broad range of $x$ and $Q^{2}$ and in terms of a rather small number of free parameters. There are several challenging issues, in particular the behavior of $d ˉ (x) / u ˉ (x)$ at large $x$ , a possible large positive gluon helicity distribution, etc.. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm}$ production in $p ˉ p$ and $pp$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.
hep-phAIP Conf.Proc.(2017)·0 citations
20*
A Three Doublet Lepton-Specific Model
Marco Merchand🇺🇸 · Marc Sher🇺🇸
In the lepton-specific version of two Higgs doublet models, a discrete symmetry is used to couple one Higgs, $Φ_{2}$ , to quarks and the other, $Φ_{1}$ , to leptons. The symmetry eliminates tree level flavor changing neutral currents (FCNC). Motivated by strong constraints on such currents in the quark sector from meson-antimeson mixing, and by hints of $h \to μτ$ in the lepton sector, we study a simple three Higgs doublet model in which one doublet couples to quarks and the other two to leptons. Unlike most other studies of three Higgs doublet models, we impose no flavor symmetry and just use a $Z_{2}$ symmetry to constrain the Yukawa couplings. We present the model and discuss the various mixing angles. Constraining the parameters to be consistent with observations of the Higgs boson at the LHC, we study the properties of the charged Higgs boson(s) in the model, focusing on the case in which the charged Higgs is above the top threshold. It is found that one can have the branching fraction of the charged Higgs into $τ ν_{τ}$ comparable to $t b ˉ$ decay without needing very large values for the ratios of vevs. One can also get a large branching fraction for the much more easily observable $μ ν_{τ}$ decay.
hep-phPRD(2017)·10 citations
21*
In-medium rho-meson properties in a light-front approach
J. P. B. C. de Melo🇧🇷 · K. Tsushima (Laboratorio de Fısica Teórica e Computacional - LFTC, Universidade Cruzeiro do Sul)🇧🇷
Properties of h̊o}-meson in symmetric nuclear matter are investigated within a light-front constituent quark model (LFCQM), using the in-medium input calculated by the quark-meson coupling (QMC) model. The LFCQM used here was previously applied in vacuum to calculate the h̊o}-meson electromagnetic properties, namely, charge G 0 , magnetic G 1 , and quadrupole G 2 form factors, as well as the electromagnetic radius and decay constant. We predict the in-medium modifications of the h̊o}-meson electromagnetic form factors in symmetric nuclear matter.
hep-phhep-thnucl-thFew Body Syst.(2017)·5 citations
22*
Towards the understanding of jet substructures and cross sections in heavy ion collisions using soft collinear effective theory
Yang-Ting Chien🇺🇸
The jet quenching phenomenon in heavy ion collisions provides a strong evidence of the modification of parton shower in the quark-gluon plasma (QGP). Jet substructure observables can probe various aspects of the jet formation mechanism. They contain useful information about the QGP and allow us to study the medium properties in great details. Here we present theoretical calculations of jet shapes and cross sections in proton-proton and lead-lead collisions at the LHC using soft-collinear effective theory, with Glauber gluon interactions in the medium. We find that resumming large logarithms in the jet substructure calculation is necessary for precise theoretical predictions. The resummation is performed using renormalization group evolution between characteristic jet scales. We also find that the medium induces power corrections to jet shapes. In the end we present the comparison between our calculations with the recent measurements at the LHC with very good agreement. Our calculations help initiate precise jet modification studies in heavy ion collisions.
hep-phnucl-thPoS(2016)·1 citation
23*
Weak Gravity Conjecture and Extremal Black Holes
William Cottrell🇺🇸 · Gary Shiu🇺🇸 · Pablo Soler🇩🇪
Motivated by the desire to improve our understanding of the Weak Gravity Conjecture, we compute the one-loop correction of charged particles to the geometry and entropy of extremal black holes in 4d. We find that fermion loops provide evidence for the necessity of the `magnetic' WGC cutoff. Moreover, for a certain regime of black holes, we find entropy corrections with unusual area scaling. The corrections are reduced when supersymmetry is present, and disappear in $N = 4$ supergravity. We further provide some speculative arguments that in a theory with only sub-extremal particles, classical Reissner-Nordstrom black holes actually possess an infinite microcanonical entropy, though only a finite amount is visible to an external observer.
↳ hep-thgr-qchep-phSCPMA(2019)·75 citations
24*
Inverse Magnetic Catalysis from improved Holographic QCD in the Veneziano limit
Umut Gürsoy🇳🇱 · Ioannis Iatrakis🇳🇱 · Matti Järvinen🇫🇷 · Govert Nijs🇳🇱
We study the dependence of the chiral condensate on external magnetic field in the context of holographic QCD at large number of flavors. We consider a holographic QCD model where the flavor degrees of freedom fully backreact on the color dynamics. Perturbative QCD calculations have shown that $B$ acts constructively on the chiral condensate, a phenomenon called "magnetic catalysis". In contrast, recent lattice calculations show that, depending on the number of flavors and temperature, the magnetic field may also act destructively, which is called "inverse magnetic catalysis". Here we show that the holographic theory is capable of both behaviors depending on the choice of parameters. For reasonable choice of the potentials entering the model we find qualitative agreement with the lattice expectations. Our results provide insight for the physical reasons behind the inverse magnetic catalysis. In particular, we argue that the backreaction of the flavors to the background geometry decatalyzes the condensate.
↳ hep-thhep-phnucl-thJHEP(2017)·65 citations
25*
A gauge invariant Debye mass for the complex heavy-quark potential
Yannis Burnier🇨🇭 · Alexander Rothkopf🇩🇪
The concept of a screening mass is a powerful tool to simplify the intricate physics of in-medium test charges surrounded by light charge carriers. While it has been successfully used to describe electromagnetic properties, its definition and computation in QCD is plagued by questions of gauge invariance and the presence of non-perturbative contributions from the magnetic sector. Here we present a recent alternative definition of a gauge invariant Debye mass parameter following closely the original idea of Debye and Hueckel. Our test charges are a static heavy quark-antiquark pair whose complex potential and its in-medium modification can be extracted using lattice QCD. By combining in a generalized Gauss-Law the non-perturbative aspects of quark binding with a perturbative ansatz for the medium effects, we succeed to describe the lattice values of the potential with a single temperature dependent parameter, in turn identified with a Debye mass. We find that its behavior, as evaluated in a recent quenched lattice QCD study, deviates from that in other approaches, such as hard-thermal-loop perturbation theory or from electric field correlators on the lattice. In particular around the phase transition its values tend to zero significantly faster than at weak-coupling.
↳ hep-lathep-phnucl-thPoS(2016)·1 citation
26*
What lattice QCD spectral functions can tell us about heavy quarkonium in the QGP
Alexander Rothkopf🇩🇪
The bound states of a heavy quark and antiquark ( $c c ˉ, b b ˉ$ ) are ideal probes to explore the quark-gluon plasma created in relativistic heavy-ion collisions at the RHIC and LHC. Not only have they become experimentally accessible with high precision but also efficient tools, so called effective field theories (EFT) have been developed to treat them theoretically. Here we present recent progress in understanding the in-medium behavior of heavy-quarkonium with the help of EFT's combined with non-perturbative and first principles simulations in lattice QCD. In particular we discuss computations of heavy quarkonium spectral functions with the help of Bayesian unfolding methods and the physics we can extract from them. Limitations and the underlying assumptions of the used approaches are pointed out.
↳ hep-lathep-phnucl-thPoS(2016)·3 citations
27*
Spin-Dependent Weakly-Interacting-Massive-Particle--Nucleon Cross Section Limits from First Data of PandaX-II Experiment
Changbo Fu🇨🇳 · Xiangyi Cui🇨🇳 · Xiaopeng Zhou🇨🇳 · Xun Chen🇨🇳 · Yunhua Chen🇨🇳 · Deqing Fang🇨🇳 · Karl Giboni🇨🇳 · Franco Giuliani🇨🇳 · Ke Han🇨🇳 · Xingtao Huang🇨🇳 · Xiangdong Ji🇨🇳 · Yonglin Ju🇨🇳 and 25 other authors
New constraints are presented on the spin-dependent WIMP-nucleon interaction from the PandaX-II experiment, using a data set corresponding to a total exposure of 3.3 $\times 1 0^{4}$ kg-days. Assuming a standard axial-vector spin-dependent WIMP interaction with $^{129}$ Xe and $^{131}$ Xe nuclei, the most stringent upper limits on WIMP-neutron cross sections for WIMPs with masses above 10 GeV/c $^{2}$ are set in all dark matter direct detection experiments. The minimum upper limit of $4.1 \times 1 0^{- 41}$ cm $^{2}$ at 90\% confidence level is obtained for a WIMP mass of 40 GeV/c $^{2}$ . This represents more than a factor of two improvement on the best available limits at this and higher masses. These improved cross-section limits provide more stringent constraints on the effective WIMP-proton and WIMP-neutron couplings.
↳ hep-exastro-ph.COhep-phPRL(2017)·188 citations
28*
Galactic Bulge Preferred Over Dark Matter for the Galactic Center Gamma-Ray Excess
Oscar Macias🇺🇸 · Chris Gordon🇳🇿 · Roland M. Crocker🇦🇺 · Brenna Coleman🇳🇿 · Dylan Paterson🇳🇿 · Shunsaku Horiuchi🇺🇸 · Martin Pohl🇩🇪
An anomalous gamma-ray excess emission has been found in Fermi Large Area Telescope data covering the centre of the Galaxy. Several theories have been proposed for this `Galactic Centre Excess'. They include self-annihilation of dark matter particles, an unresolved population of millisecond pulsars, an unresolved population of young pulsars, or a series of burst events. Here we report on a new analysis that exploits hydrodynamical modelling to register the position of interstellar gas associated with diffuse Galactic gamma-ray emission. We find evidence that the Galactic Centre Excess gamma rays are statistically better described by the stellar over-density in the Galactic bulge and the nuclear stellar bulge, rather than a spherical excess. Given its non-spherical nature, we argue that the Galactic Centre Excess is not a dark matter phenomenon but rather associated with the stellar population of the Galactic bulge and nuclear bulge.
↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phNature Astron.(2018)·198 citations
29*
QCD phase diagram with isospin chemical potential
Bastian B. Brandt🇩🇪 · Gergely Endrodi🇩🇪
In this contribution we investigate the phase diagram of QCD in the presence of an isospin chemical potential. To alleviate the infrared problems of the theory associated with pion condensation, we introduce the pionic source as an infrared regulator. We discuss various methods to extrapolate the results to vanishing pionic source, including a novel method based on the singular value spectrum of the massive Dirac operator, a leading-order reweighting and a spline Monte-Carlo fit. Our main results concern the phase transition boundary between the normal and the pion condensation phases and the chiral/deconfinement transition temperature as a function of the chemical potential. In addition, we perform a quantitative comparison between our direct results and a Taylor-expansion obtained at zero chemical potential to assess the applicability range of the latter.
↳ hep-lathep-phnucl-thPoS(2016)·67 citations
30*
FeynHelpers: Connecting FeynCalc to FIRE and Package-X
Vladyslav Shtabovenko🇩🇪
We present a new interface called FeynHelpers that connects FeynCalc, a Mathematica package for symbolic semi-automatic evaluation of Feynman diagrams and calculations in quantum field theory (QFT) to Package-X and FIRE. The former provides a library of analytic results for scalar 1-loop integrals with up to 4 legs, while the latter is a general-purpose tool for reduction of multi-loop scalar integrals using Integration-by-Parts (IBP) identities. With this add-on many types of calculations that were difficult or hardly feasible with FeynCalc previously, can now be done in a much simpler way. This is demonstrated with four different examples from QED, QCD and Higgs physics.
↳ physics.comp-phhep-phhep-thComput.Phys.Commun.(2017)·162 citations
31*
On chiral magnetic effect in Weyl superfluid 3He-A
G.E. Volovik🇫🇮
In the theory of the chiral anomaly in relativistic quantum field theories (RQFT) some results depend on regularization scheme at ultraviolet. In the chiral superfluid 3He-A, which contains two Weyl points and also experiences the effects of chiral anomaly, the "trans-Planckian" physics is known and the results can be obtained without regularization. We discuss this on example of the chiral magnetic effect (CME), which has been observed in 3He-A in 90's. There are two forms of the contribution of the CME to the Chern-Simons term in free energy, perturbative and non-perturbative. The perturbative term comes from the fermions living in the vicinity of the Weyl point, where the fermions are "relativistic" and obey the Weyl equation. The non-perturbative term originates from the deep vacuum, being determined by the separation of the two Weyl points. Both terms are obtained using the Adler-Bell-Jackiw equation for chiral anomaly, and both agree with the results of the microscopic calculations in the "trans-Planckian" region. Existence of the two nonequivalent forms of the Chern-Simons term demonstrates that the results obtained within the RQFT depend on the specific properties of the underlying quantum vacuum and may reflect different physical phenomena in the same vacuum.
↳ cond-mat.otherhep-phJETP Lett.(2017)·7 citations
32*
Efficient numerical integration of neutrino oscillations in matter
Fernando Casas🇪🇸 · Jose Angel Oteo🇲🇽 · Juan Carlos D'Olivo🇲🇽
A special purpose solver, based on the Magnus expansion, well suited for the integration of the linear three neutrino oscillations equations in matter is proposed. The computations are speeded up to two orders of magnitude with respect to a general numerical integrator, a fact that could smooth the way for massive numerical integration concomitant with experimental data analyses. Detailed illustrations about numerical procedure and computer time costs are provided.
↳ physics.comp-phcs.NAhep-phmath.NAPRD(2016)·4 citations
33*
Search for magnetic monopoles with the MoEDAL forward trapping detector in 13 TeV proton-proton collisions at the LHC
MoEDAL Collaboration: B. Acharya🇬🇧 · J. Alexandre🇬🇧 · S. Baines🇬🇧 · P. Benes🇨🇿 · B. Bergmann🇨🇿 · J. Bernabéu🇪🇸 · H. Branzas🇷🇴 · M. Campbell🇨🇭 · L. Caramete🇷🇴 · S. Cecchini🇮🇹 · M. de Montigny🇨🇦 · A. De Roeck🇨🇭 and 58 other authors
MoEDAL is designed to identify new physics in the form of long-lived highly-ionising particles produced in high-energy LHC collisions. Its arrays of plastic nuclear-track detectors and aluminium trapping volumes provide two independent passive detection techniques. We present here the results of a first search for magnetic monopole production in 13 TeV proton-proton collisions using the trapping technique, extending a previous publication with 8 TeV data during LHC run-1. A total of 222 kg of MoEDAL trapping detector samples was exposed in the forward region and analysed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges exceeding half the Dirac charge are excluded in all samples and limits are placed for the first time on the production of magnetic monopoles in 13 TeV $pp$ collisions. The search probes mass ranges previously inaccessible to collider experiments for up to five times the Dirac charge.
↳ hep-exhep-phPRL(2017)·122 citations
34*
Gluon momentum fraction of the nucleon from lattice QCD
Constantia Alexandrou🇨🇾 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Haralambos Panagopoulos🇨🇾 · Christian Wiese🇩🇪
We perform a direct calculation of the gluon momentum fraction of the nucleon using maximally twisted mass fermion ensembles with $N_{f} = 2 + 1 + 1$ flavors at a pion mass of about $370 MeV$ and a lattice spacing of $a \approx 0.082 fm$ and with $N_{f} = 2$ flavors at the physical pion mass and a lattice spacing of $a \approx 0.093 fm$ . In the definition of the gluon operator we employ stout smearing to obtain a statistically significant result for the bare matrix elements. In addition, we perform a lattice perturbative calculation including 2 levels of stout smearing to carry out the mixing and the renormalization of the quark and gluon operators. We find, after conversion to the $MS$ scheme at a scale of $2 GeV$ : $⟨ x ⟩_{g}^{R} = 0.284 (23) (23)$ for pion mass of about $370 MeV$ and $⟨ x ⟩_{g}^{R} = 0.283 (23) (15)$ for the physical pion mass.
↳ hep-lathep-exhep-phhep-th+1PRD(2017)·56 citations
35*
Hadron Resonance Gas Model for An Arbitrarily Large Number of Different Hard-Core Radii
K. A. Bugaev · V. V. Sagun · A. I. Ivanytskyi · I. P. Yakimenko · E. G. Nikonov · A.V. Taranenko · G. M. Zinovjev
We develop a novel formulation of the hadron-resonance gas model which, besides a hard-core repulsion, explicitly accounts for the surface tension induced by the interaction between the particles. Such an equation of state allows us to go beyond the Van der Waals approximation for any number of different hard-core radii. A comparison with the Carnahan-Starling equation of state shows that the new model is valid for packing fractions 0.2-0.22, while the usual Van der Waals model is inapplicable at packing fractions above 0.1-0.11. Moreover, it is shown that the equation of state with induced surface tension is softer than the one of hard spheres and remains causal at higher particle densities. The great advantage of our model is that there are only two equations to be solved and it does not depend on the various values of the hard-core radii used for different hadronic resonances. Using this novel equation of state we obtain a high-quality fit of the ALICE hadron multiplicities measured at center-of-mass energies of 2.76 TeV per nucleon. Furthermore, using the traditional hadron-resonance gas model with multi-component hard-core repulsion and the novel one we investigate the recently suggested model in which the proper volume of a hadron is proportional to its mass. We find that the high-temperature maximum of $χ^{2} / n df$ observed in the latter model always appears in the region located far above the limit of its applicability.
↳ nucl-thhep-ph7 citations
36*
The Peak Structure in the In-Flight $^{3} He (K^{-}, Λ p) n$ Reaction Around the $K ˉ N N$ Threshold
Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. amd Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U. and ICC, Barcelona U.)🇪🇸
We theoretically investigate the origin of the peak structure around the $K^{-} pp$ threshold observed in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction in the recent E15 experiment at J-PARC. For this purpose, we consider two scenarios to produce the peak. One is that the $Λ (1405)$ is generated but it does not correlate with $p$ , and the uncorrelated $Λ (1405) p$ system subsequently decays into $Λ p$ . The other one is that the $K ˉ N N$ bound state is indeed generated and decays into $Λ p$ . As a result, the experimental signal is qualitatively well reproduced in the $K ˉ N N$ bound scenario, definitely discarding the uncorrelated $Λ (1405) p$ one.
↳ nucl-thhep-phnucl-exJPS Conf.Proc.(2017)·2 citations
37*
Leading Neutrons From Polarized Proton-Nucleus Collisions
B. Z. Kopeliovich🇨🇱 · I. K. Potashnikova🇨🇱 · Ivan Schmidt🇨🇱
Leading neutron production on protons is known to be subject to strong absorptive corrections, which have been under debate for a long time. On nuclear targets these corrections are significantly enhanced and push the partial cross sections of neutron production to the very periphery of the nucleus. As a result, the A-dependences of inclusive and diffractive neutron production turn out to be similar. The mechanism of \pi-a_1 interference, which successfully explained the observed single-spin asymmetry of neutrons in polarized pp interactions, is extended here to polarized pA collisions. Corrected for nuclear effects it explains well the magnitude and sign of the asymmetry A_N observed in inelastic events, resulting in a violent break up of the nucleus. However the excessive magnitude of A_N observed in the diffractive sample, remains a challenge.
↳ nucl-thhep-phAIP Conf.Proc.(2017)·4 citations
38*
QCD, with Strings Attached
Alberto Guijosa🇲🇽
In the nearly twenty years that have elapsed since its discovery, the gauge-gravity correspondence has become established as an efficient tool to explore the physics of a large class of strongly-coupled field theories. A brief overview is given here of its formulation and a few of its applications, emphasizing attempts to emulate aspects of the strong-coupling regime of quantum chromodynamics (QCD). To the extent possible, the presentation is self-contained, and in particular, it does not presuppose knowledge of string theory.
↳ hep-thgr-qchep-phnucl-thIJMPE(2016)·4 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.