Wed·Jan 6, 2016Wednesday·January 6, 2016

1. 01*

   Heavy photophilic scalar at the LHC from a varying electromagnetic coupling

   Ulf Danielsson🇸🇪 · Rikard Enberg🇸🇪 · Gunnar Ingelman🇸🇪 · Tanumoy Mandal🇸🇪

   We investigate the phenomenology of a heavy scalar $\varphi$ of the type involved in Bekenstein's framework for varying electromagnetic coupling theories, with the difference that the scalar in our model has a large mass. The model has only two free parameters, the mass $M_{\varphi }$ of the scalar and the scale $\Lambda$ of new physics. The scalar is dominantly produced through photon-photon fusion at the LHC and leads to a diphoton final state. It can also be produced by quark-antiquark fusion in association with a photon or a fermion pair. Its dominating decay is to diphotons, but it also has a large three-body branching to a fermion pair and a photon, which can provide an interesting search channel with a dilepton-photon resonance. We derive exclusion limits on the $M_{\varphi }-\Lambda$ plane from the latest 13 TeV LHC diphoton resonance search data. For a benchmark mass of $M_{\varphi }\sim 1$ TeV, we find a lower limit on $\Lambda$ of 18 TeV. We discuss the more complex possibility of varying couplings in the full electroweak theory and comment on the possibility that the new physics is related to extra dimensions or string theory.

   hep-phNPB(2017)·61 citations
2. 02*

   The Diphoton Excess from an Exceptional Supersymmetric Standard Model

   Wei Chao🇺🇸

   In this paper we explain the diphoton excess in the invariant mass M $\approx$ 750 GeV , claimed by the ATLAS and CMS collaborations at the run-2 LHC, as the signal of a scalar singlet in a string inspired exceptional supersymmetric standard model (ESSM). The scalar singlet might play a rule in the spontaneous breaking of the $U(1{)}^{\prime }$ gauge symmetry of the ESSM and couples to diphoton and/or gluon pair with the help of exotic quarks and Higgs-like supermultiplets, which are contained in the fundamental representation of the $E_6$ group. The model might give rise to a large enough production cross section at the LHC but can hardly fit with the wide width of the resonance except in the strong couple regime.

   hep-ph72 citations
3. 03*

   Gluon vs. Photon Production of a 750 GeV Diphoton Resonance

   Csaba Csaki🇺🇸 · Jay Hubisz🇺🇸 · Salvator Lombardo🇺🇸 · John Terning🇺🇸

   The production mechanism of a 750 GeV diphoton resonance, either via gluon or photon fusion, can be probed by studying kinematic observables in the diphoton events. We perform a detector study of the two production modes of a hypothetical scalar or tensor diphoton resonance in order to characterize the features of the two scenarios. The nature of the resonance production can be determined from the jet multiplicity, the jet and diphoton rapidities, the rate of central pseudorapidity gaps, or the possible detection of forward protons from elastic photoproduction for events in the signal region. Kinematic distributions for both signals and expected irreducible diphoton background events are provided for comparison along with a study of observables useful for distinguishing the two scenarios at an integrated luminosity of 20 fb${}^{-1}$. We find that decay photons from a 750 GeV scalar resonance have a preference for acceptance in the central detector barrel, while background events are more likely to give accepted photons in the detector end caps. This disfavors the interpretation of the large number of excess events found by the the Run-2 CMS diphoton search with one photon detected in the end cap as a wide spin-0 resonance signal. However, one expects more end cap photons in the case of spin-2 resonance.

   hep-phPRD(2016)·100 citations
4. 04*

   750 GeV Diphoton excess from $E_6$ in F-theory GUTs

   Athanasios Karozas🇬🇷 · Stephen F. King🇬🇧 · George K. Leontaris🇬🇷 · Andrew K. Meadowcroft🇬🇧

   We interpret the 750-760 GeV diphoton resonance as one or more of the spinless components of a singlet superfield arising from the three 27-dimensional representations of $E_6$ in F-theory, which also contain three copies of colour-triplet charge $\mp 1/3$ vector-like fermions $D_i,{\bar{D}}_i$ and inert Higgs doublets to which the singlets may couple. For definiteness we consider (without change) a model that was proposed some time ago which contains such states, as well as bulk exotics, leading to gauge coupling unification. The smoking gun prediction of the model is the existence of other similar spinless resonances, possibly close in mass to 750-760 GeV, decaying into diphotons, as well as the three families of vector-like fermions $D_i,{\bar{D}}_i$.

   hep-phPLB(2016)·61 citations
5. 05*

   Light Higgsino as the tail of the $\mu$-$B_{\mu }$ solution

   Masaki Asano🇩🇪 · Norimi Yokozaki🇮🇹

   Gauge mediation predicts 10 TeV or heavier squarks because such a heavy stop is required to explain the observed 125 GeV Higgs boson mass without a large trilinear soft mass term in the minimal supersymmetric standard model. Although such a high scale cannot be searched by the LHC directly, gauge mediation also predicts a hierarchy ${\mu }^2\ll B_{\mu }$ by a simple and naive solution of the $\mu$ problem. We point out that this simple and naive way of generating the $\mu$ ($B_{\mu }$) term works in the case of 10 TeV or heavier squarks with a slight breaking of a GUT relation among messenger B-terms (or supersymmetric mass terms). Furthermore, the upper bound on the Higgsino mass is obtained from the observed Higgs boson mass, perturbativity of a relevant coupling, and conditions avoiding tachyonic sneutrinos and stop. It turns out that the light Higgsino of O(100) GeV is a promising signal of gauge mediation.

   hep-phhep-exPRD(2016)·4 citations
6. 06*

   Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry

   IceCube Collaboration: M. G. Aartsen🇦🇺 · K. Abraham🇩🇪 · M. Ackermann🇩🇪 · J. Adams🇳🇿 · J. A. Aguilar🇧🇪 · M. Ahlers🇺🇸 · M. Ahrens🇸🇪 · D. Altmann🇩🇪 · T. Anderson🇺🇸 · I. Ansseau🇧🇪 · G. Anton🇩🇪 · M. Archinger🇩🇪 and 305 other authors

   We present an improved event-level likelihood formalism for including neutrino telescope data in global fits to new physics. We derive limits on spin-dependent dark matter-proton scattering by employing the new formalism in a re-analysis of data from the 79-string IceCube search for dark matter annihilation in the Sun, including explicit energy information for each event. The new analysis excludes a number of models in the weak-scale minimal supersymmetric standard model (MSSM) for the first time. This work is accompanied by the public release of the 79-string IceCube data, as well as an associated computer code for applying the new likelihood to arbitrary dark matter models.

   hep-phastro-ph.COhep-exJCAP(2016)·229 citations
7. 07*

   Associated production of a Higgs boson at NNLO

   John M. Campbell🇺🇸 · R. Keith Ellis🇬🇧 · Ciaran Williams🇺🇸

   In this paper we present a Next-to-Next-to Leading Order (NNLO) calculation of the production of a Higgs boson in association with a massive vector boson. We include the decays of the unstable Higgs and vector bosons, resulting in a fully flexible parton-level Monte Carlo implementation. We also include all $\mathcal{O}({\alpha }_s^2)$ contributions that occur in production for these processes: those mediated by the exchange of a single off-shell vector boson in the $s$-channel, and those which arise from the coupling of the Higgs boson to a closed loop of fermions. We study final states of interest for Run II phenomenology, namely $H\to b\bar{b}$, $\gamma \gamma$ and $W{W}^{\ast }$. The treatment of the $H\to b\bar{b}$ decay includes QCD corrections at NLO. We use the recently developed $N$-jettiness regularization procedure, and study its viability in the presence of a large final-state phase space by studying $pp\to V(H\to W{W}^{\ast })\to$ leptons.

   hep-phhep-exJHEP(2016)·168 citations
8. 08*

   The $750\text{GeV}$ diphoton resonance in the light of a 2HDM with $S_3$ flavour symmetry

   A. E. Cárcamo Hernández🇨🇱 · I. de Medeiros Varzielas🇬🇧 · E. Schumacher🇩🇪

   Very recently we proposed a predictive 2 Higgs Doublet Model with $S_3$ flavour symmetry that successfully accounts for fermion masses and mixings. In this letter, motivated by the $750$ GeV Higgs diphoton resonance recently reported by the ATLAS and CMS collaborations, we modify this model by adding exotic top partners with electric charge $\frac{5}{3}$ and a electrically charged scalar singlet. These exotic top partners decay into a charged scalar singlet and the SM up type quarks, whereas the charged scalar singlet will mainly decay into SM up and down type quarks. This simple modification enables our model to successfully account for the Higgs diphoton excess at $750\text{GeV}$ provided that the exotic quark masses are in the range $[1,2]$ TeV, for $O(1)$ exotic quark Yukawa couplings.

   hep-ph66 citations
9. 09*

   $WW$ scattering in a radiative electroweak symmetry breaking scenario

   Kazuhiro Endo🇯🇵 · Koji Ishiwata🇯🇵 · Yukinari Sumino🇯🇵

   A classically scale invariant (CSI) extension of the standard model (SM) induces radiative electroweak symmetry breaking and predicts anomalously large Higgs self-interactions. Hence, $W_L{W}_L$ scattering processes can be a good probe of the symmetry breaking mechanism. We develop a theoretical framework for perturbative computation and calculate $WW$ scattering amplitudes in a CSI model. It is shown that $W_L{W}_L$ scattering amplitudes satisfy the equivalence theorem, and that a large deviation of $W_L{W}_L$ differential cross sections from the SM predictions is predicted depending on the c.m. energy and scattering angle. The results are more accurate than those based on the effective-potential approach. A prescription to implement predictions of the CSI model to Monte Carlo event generators is also presented.

   hep-phhep-exPRD(2016)·8 citations
10. 10*

    Some New Symmetric Relations and the Prediction of Left and Right Handed Neutrino Masses using Koide's Relation

    Yong-Chang Huang🇨🇳 · Syeda Tehreem Iqbal🇨🇳 · Zhen Lei🇨🇳 · Wen-Yu Wang🇨🇳

    Masses of the three generations of charged leptons are known to completely satisfy the Koide's mass relation. But the question remains if such a relation exists for neutrinos? In this paper, by considering SeeSaw mechanism as the mechanism generating tiny neutrino masses, we show how neutrinos satisfy the Koide's mass relation, on the basis of which we systematically give exact values of not only left but also right handed neutrino masses.

    hep-phCPC(2017)·3 citations
11. 11*

    Exploring open-charm decay mode ${\Lambda }_c{\bar{\Lambda }}_c$ of charmonium-like state $Y(4630)$

    Xuewen Liu🇨🇳 · Hong-Wei Ke🇨🇳 · Xiang Liu🇨🇳 · Xue-Qian Li🇨🇳

    The newly observed $X,Y,Z$ exotic states are definitely not in the standard $Q{\bar{Q}}^{\prime }$ structures, thus their existence composes a challenge to our understanding on the fundamental principles of hadron physics. Therefore the studies on their decay patterns which are determined by the non-perturbative QCD will definitely shed light on the concerned physics. Generally the four-quark states might be in a molecular state or tetraquark or their mixture. In this work, we adopt the suggestion that $Y(4630)$ is a charmonium-like tetraquark made of a diquark and an anti-diquark. If it is true, its favorable decay mode should be $Y(4630)$ decaying into an open-charm baryon pair, since such a transition occurs via strong interaction and is super-OZI-allowed. In this work, we calculate the decay width of $Y(4630)\to {\Lambda }_c{\bar{\Lambda }}_c$ in the framework of the quark pair creation (QPC) model. Our numerical results on the partial width computed in the tetraquark configuration coincide with the Belle data within a certain error tolerance.

    hep-phhep-exEPJC(2016)·23 citations
12. 12*

    Blind spots for neutralinos in NMSSM with light singlet scalar

    M. Badziak🇵🇱 · M. Olechowski🇵🇱 · P. Szczerbiak🇵🇱

    A substantial contribution to the SM-like Higgs mass may come from the mixing with the lightest singlet-dominated scalar in NMSSM for moderate or large values of $\tan \beta$ [1]. The LSP neutralino in this model may also contain the singlet component - singlino. In this work we analyze the direct detection cross section for a Higgsino-singlino LSP with the emphasis on possible direct detection blind spots in the parameter space. Correlations between the LSP properties and the effects in the Higgs sector coming from the mixing are also discussed.

    hep-phPoS(2015)·16 citations
13. 13*

    Modeling chiral criticality and its consequences for heavy-ion collisions

    Gábor András Almási🇩🇪 · Bengt Friman🇩🇪 · Krzysztof Redlich🇵🇱

    We explore the critical fluctuations near the chiral critical endpoint (CEP) in a chiral effective model and discuss possible signals of the CEP, recently explored experimentally in nuclear collision. Particular attention is paid to the dependence of such signals on the location of the phase boundary and the CEP relative to the chemical freeze-out conditions in nuclear collisions. We argue that in effective models, standard freeze-out fits to heavy-ion data should not be used directly. Instead, the relevant quantities should be examined on lines in the phase diagram that are defined self-consistently, within the framework of the model. We discuss possible choices for such an approach.

    hep-phNPA(2016)·5 citations
14. 14*

    Charmed meson and charmonium production in PbPb collisions at the LHC

    I.P. Lokhtin🇷🇺 · A.V. Belyaev🇷🇺 · G.Kh. Eyyubova🇨🇿 · G. Ponimatkin🇨🇿 · E.Yu. Pronina🇷🇺

    The phenomenological analysis of various characteristics of $J/\psi$ and $D$ meson production in PbPb collisions at the center-of-mass energy 2.76 TeV per nucleon pair is presented. The data on momentum spectra and elliptic flow are reproduced by two-component model HYDJET++ including thermal and non-thermal charm production mechanisms. The significant part of $D$-mesons is found to be in a kinetic equilibrium with the created medium, while $J/\psi$-mesons are characterized by earlier (as compared to light hadrons) freeze-out.

    hep-phnucl-thJ.Phys.G(2016)·14 citations
15. 15*

    750 GeV Diphoton excess from Gauged $B-L$ Symmetry

    Tanmoy Modak🇮🇳 · Soumya Sadhukhan🇮🇳 · Rahul Srivastava🇮🇳

    We show that the recently observed 750 GeV diphoton excess at LHC can be due to the decay of a $SU(2{)}_L$ singlet scalar particle having 3 units of charge under gauged $B-L$ symmetry. Such a particle arises as an essential ingredient of recently studied gauged $B-L$ extension of the Standard Model with unconventional charge assignment for right handed neutrinos. Apart from being one of the simplest extensions of the Standard Model, the model also contains a dark matter candidate and Dirac neutrinos with naturally small masses.

    hep-phhep-exPLB(2016)·67 citations
16. 16*

    Resonance on top of thresholds: the ${\Lambda }_c(2595{)}^{+}$ as an extremely fine-tuned state

    Zhi-Hui Guo🇨🇳 · J.A. Oller🇪🇸

    A dedicated study of the $\pi {\Sigma }_c$ scattering around its threshold is carried out in this work to probe the nature of ${\Lambda }_c(2595{)}^{+}$. We first demonstrate that the effective range expansion approach fails to work near the ${\Lambda }_c(2595{)}^{+}$ pole position, due to the presence of a nearby CDD pole around the $\pi {\Sigma }_c$ thresholds. We then develop a general framework to properly handle the situation with a CDD pole accompanied by nearby thresholds, which is first elaborated for the single-channel case and then generalized to the coupled-channel study. The isospin breaking effects of the three $\pi {\Sigma }_c$ channels with different thresholds are specially taken into account in our study. The finite-width effects from the ${\Sigma }_c$ baryons are considered and found to be relevant to give the ${\Lambda }_c(2595{)}^{+}$ width fully compatible to its experimental value. Through the compositeness analysis, our robust conclusion is that the ${\pi }^0{\Sigma }_c^{+}$ component is subdominant inside the ${\Lambda }_c(2595{)}^{+}$.

    hep-phhep-exhep-latnucl-thPRD(2016)·43 citations
17. 17*

    Diphoton Excess in Consistent Supersymmetric SU(5) Models with Vector-like Particles

    Bhaskar Dutta🇺🇸 · Yu Gao🇺🇸 · Tathagata Ghosh🇺🇸 · Ilia Gogoladze🇺🇸 · Tianjun Li🇨🇳 · Qaisar Shafi🇺🇸 · Joel W. Walker🇺🇸

    We consider the diphoton resonance at the 13 TeV LHC in the context of SU(5) grand unification. A leading candidate to explain this resonance is a standard model singlet scalar decaying to a pair of photon by means of vector-like fermionic loops. We demonstrate the effect of the vector-like multiplets (5, 5 bar) and (10, 10 bar) on the evolution of the gauge couplings and perturbatively evaluate the weak scale values of the new couplings and masses run down from the unification scale. We use these masses and couplings to explain the diphoton resonance after considering the new dijet constraints. We show how to accommodate the larger decay width of the resonance particle, which seems to be preferred by the experimental data. In addition, we consider new couplings relating various components of (5, 5 bar) and (10, 10 bar) in the context of the orbifold GUTs, where the resonance scalar can be a part of the new vector-like lepton doublets. We also calculate the Higgs mass and proton decay rate to positron and neutral pion in the context of SU(5) grand unification, including effects of the new vector-like multiplets.

    hep-phhep-ex76 citations
18. 18*

    Charge-dependent correlations from event-by-event anomalous hydrodynamics

    Yuji Hirono🇺🇸 · Tetsufumi Hirano🇯🇵 · Dmitri E. Kharzeev🇺🇸

    We report on our recent attempt of quantitative modeling of the Chiral Magnetic Effect (CME) in heavy-ion collisions. We perform 3+1 dimensional anomalous hydrodynamic simulations on an event-by-event basis, with constitutive equations that contain the anomaly-induced effects. We also develop a model of the initial condition for the axial charge density that captures the statistical nature of random chirality imbalances created by the color flux tubes. Basing on the event-by-event hydrodynamic simulations for hundreds of thousands of collisions, we calculate the correlation functions that are measured in experiments, and discuss how the anomalous transport affects these observables.

    hep-phnucl-exnucl-thNPA(2016)·3 citations
19. 19*

    Reproducing sterile neutrinos and the behavior of flavor oscillations with superconducting-magnetic proximity effects

    Thomas E. Baker🇺🇸

    The physics of a superconductor subjected to a magnetic field is known to be equivalent to neutrino oscillations. Examining the properties of singlet-triplet oscillations in the magnetic field, a sterile neutrino--shown to be a Majorana fermion--is suggested to be represented by singlet Cooper pairs and moderates flavor oscillations between three flavor neutrinos (triplet Cooper pairs). A superconductor-exchange spring system's rotating magnetization profile is used to simulate the mass-flavor oscillations in the neutrino case and the physics of neutrino oscillations are discussed. Symmetry protected triplet components are presented as weak process states. Phases acquired due to the Fulde-Ferrell-Larkin-Ovchinnikov effect produce a complex phase that may be responsible for charge-parity violation in flavor oscillations.

    hep-phastro-ph.HEcond-mat.supr-con1 citation
20. 20*

    Degeneracies in long-baseline neutrino experiments from nonstandard interactions

    Jiajun Liao🇺🇸 · Danny Marfatia🇺🇸 · Kerry Whisnant🇺🇸

    We study parameter degeneracies that can occur in long-baseline neutrino appearance experiments due to nonstandard interactions (NSI) in neutrino propagation. For a single off-diagonal NSI parameter, and neutrino and antineutrino measurements at a single L/E, there exists a continuous four-fold degeneracy (related to the mass hierarchy and ${\theta }_{23}$ octant) that renders the mass hierarchy, octant, and CP phase unknowable. Even with a combination of NO$\nu$A and T2K data, which in principle can resolve the degeneracy, both NSI and the CP phase remain unconstrained because of experimental uncertainties. A wide-band beam experiment like DUNE will resolve this degeneracy if the nonzero off-diagonal NSI parameter is ${ϵ}_{e\mu }$. If ${ϵ}_{e\tau }$ is nonzero, or the diagonal NSI parameter ${ϵ}_{ee}$ is O(1), a wrong determination of the mass hierarchy and of CP violation can occur at DUNE. The octant degeneracy can be further complicated by ${ϵ}_{e\tau }$, but is not affected by ${ϵ}_{ee}$.

    hep-phhep-exPRD(2016)·118 citations
21. 21*

    The Fourth Generation Quark and the 750 GeV Diphoton Excess

    Yu-Jie Zhang🇨🇳 · Bin-Bin Zhou🇨🇳 · Jia-Jia Sun🇨🇳

    Recently, the CMS and ATLAS collaborations have reported a diphoton peak at 750 GeV in the RunII of LHC at 13 TeV. We assume that the heavy fourth generation quark doublet $z,y$ with $380$GeV mass, and the width of $z,t$ is much less $b$ quark. Then we show that the contributions of the $(z\bar{z}+y\bar{y})/\sqrt{2}$ bound state ${\eta }_{zy}(1S)$ to the diphoton measurements through $\sigma (pp\to {\eta }_{zy}(1s)\to \gamma \gamma )$ are $5.6_{-2.8}^{+5.6}\mathrm{fb}$ at $\sqrt{S}=13$ TeV. They are constant with the 750 GeV diphoton excess measured by the CMS ant ATLAS collaborations.

    hep-ph26 citations
22. 22*

    Testing Modified Dark Matter with Galaxy Clusters: Does Dark Matter know about the Cosmological Constant?

    Doug Edmonds🇺🇸 · Duncan Farrah🇺🇸 · Chiu Man Ho🇺🇸 · Djordje Minic🇺🇸 · Y. Jack Ng🇺🇸 · Tatsu Takeuchi🇺🇸

    We discuss the possibility that the cold dark matter mass profiles contain information on the cosmological constant, and that such information constrains the nature of cold dark matter (CDM). We call this approach Modified Dark Matter (MDM). In particular, we examine the ability of MDM to explain the observed mass profiles of 13 galaxy clusters. Using general arguments from gravitational thermodynamics, we provide a theoretical justification for our MDM mass profile and successfully compare it to the NFW mass profiles both on cluster and galactic scales. Our results suggest that indeed the CDM mass profiles contain information about the cosmological constant in a non-trivial way.

    ↳ astro-ph.COastro-ph.HEhep-phInt.J.Mod.Phys.A(2017)·23 citations
23. 23*

    Jet Fragmentation via Recombination of Parton Showers

    Kyong Chol Han🇺🇸 · Rainer J. Fries🇺🇸 · Che Ming Ko🇺🇸

    We propose to model hadronization of parton showers in QCD jets through a hybrid approach involving quark recombination and string fragmentation. This is achieved by allowing gluons at the end of the perturbative shower evolution to undergo a non-perturbative splitting into quark and antiquark pairs, then applying a Monte-Carlo version of instantaneous quark recombination, and finally subjecting remnant quarks (those which have not found a recombination partner) to Lund string fragmentation. When applied to parton showers from the PYTHIA Monte Carlo event generator, the final hadron spectra from our calculation compare quite well to PYTHIA jets that have been hadronized with the default Lund string fragmentation. Our new approach opens up the possibility to generalize hadronization to jets embedded in a quark gluon plasma.

    ↳ nucl-thhep-phPRC(2016)·70 citations
24. 24*

    Effects of EoS in viscous hydro+cascade model for the RHIC Beam Energy Scan

    Iu. Karpenko🇺🇦 · M. Bleicher🇩🇪 · P. Huovinen🇩🇪 · H. Petersen🇩🇪

    A state-of-the-art 3+1 dimensional cascade + viscous hydro + cascade model vHLLE+UrQMD has been applied to heavy ion collisions in RHIC Beam Energy Scan range $\sqrt{s_{\mathrm{NN}}}=7.7\dots 200$ GeV. Based on comparison to available experimental data it was estimated that an effective value of shear viscosity over entropy density ratio $\eta /s$ in hydrodynamic stage has to decrease from $\eta /s=0.2$ to $0.08$ as collision energy increases from $\sqrt{s_{\mathrm{NN}}}=7.7$ to $39$ GeV, and to stay at $\eta /s=0.08$ for $39\le \sqrt{s_{\mathrm{NN}}}\le 200$ GeV. In this work we show how an equation of state with first order phase transition affects the hydrodynamic evolution at those collision energies and changes the results of the model as compared to "default scenario" with a crossover type EoS from chiral model.

    ↳ nucl-thhep-phnucl-exNPA(2016)·7 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.