XXI DAE BRNS High Energy Physics Symposium : Proceedings Guwahati India December 8 – 12 2014 Physics in the light ﬂavoured sector Double parton scattering studies via di boson processes using the CMS detector at LHC Three loop HTLpt thermodynamics at ﬁnite temperature and chemical potential Charting the evolution of the Strong Interaction’s degrees of freedom Vector meson spectral function and dilepton rate in an effective mean ﬁeld model Axial vector form factors in the chiral quark constituent model Nucleon structure in AdS QCD Dual QCD formulation and quark antiquark static potential Infrared Abelian dominance in a special gauge Multiplicity Characteristics of Forward Backward Emitted Particles in Heavy Ion Interactions at SPS Energies. These proceedings gather invited and contributed talks presented at the XXI DAE BRNS High Energy Physics Symposium which was held at the Indian Institute of Technology Guwahati in December 2014. The contributions cover many of the most active research areas in particle physics namely (i) Electroweak Physics; (ii) QCD and Heavy Ion Physics; (iii) Heavy Flavour Physics and CP Violation; (iv) Neutrino Physics; (v) Astro particle Physics and Cosmology; (vi) Formal Theory; (vii) Future Colliders and New Machines; and (viii) BSM Physics: SUSY Extra Dimensions Composites etc. The DAE BRNS High Energy Physics Symposium widely considered to be one of the premiere symposiums organised in India in the field of elementary particle physics is held every other year and supported by the Board of Research in Nuclear Sciences Department of Atomic Energy India. Roughly 250 physicists and researchers participated in the 21st Symposium discussing the latest advancements in the field in 18 plenary review talks 15 invited mini review talks and approximately 130 contributed presentations. Bringing together the essential content the book offers a valuable resource for both beginning and advanced researchers in the field.